TWI808224B - Optical film - Google Patents

Abstract

An object of the invention is to provide an optical film which has excellent film strength. The optical film has an optically anisotropic layer composed of a polymer obtained by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state, wherein the number of alignment defects per 1 mm² of the optically anisotropic layer whose actual size is 0.3 μm or more and 50 μm or less satisfies 0 ≦ number of alignment defects [pieces] ≦ 14.

Description

optical film

The present invention relates to an optical film, a retardation laminate, and a polarizing plate.

As an optical film used in a flat panel display device, for example, an optical film having an optically anisotropic layer obtained by dissolving a polymerizable liquid crystal compound in a solvent, coated on a support substrate, and polymerized is proposed (Patent Document 1).

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2011-207765

In recent years, along with the thinning of optical films, we have been seeking to improve the film strength and processability of the optically anisotropic layer.

It is an object of the present invention to provide an optical film with improved film strength. Another object of the present invention is to provide an optical film having improved processability when processing a polarizing plate.

The present invention provides the following aspects [1] to [12].

[1] An optical film comprising an optical film comprising an optically anisotropic layer formed by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state; the number of alignment defects per 1 ^mm of the optically anisotropic layer satisfying the following formula (1): 0≦Number of alignment defects [pieces]≦14 (1).

[2] An optical film having an optically anisotropic layer composed of a polymer formed by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state; the defect rate defined by the following formula (2) in the aforementioned optically anisotropic layer satisfies the following formula (3);

[In the formula, the total defect area is the sum of the areas of alignment defects whose actual size is 0.3 μm to 50 μm observed in one field of view of an optical microscope, and the observation field of microscope is the area of the optically anisotropic layer when the optically anisotropic layer exists in the entire field of view of the optical microscope]; 0≦defect rate [ppm]≦1000 (3).

[3] An optical film comprising an optical film having an optically anisotropic layer formed by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state; the number of alignment defects with an actual size of 0.3 μm to 50 μm per 1 mm of the optically anisotropic layer satisfies the following formula ( ¹ ), and the defect rate defined by the following formula (2) satisfies the following formula (3); (1);

[In the formula, the total defect area is the sum of the areas of alignment defects whose actual size is 0.3 μm to 50 μm observed in one field of view of an optical microscope, and the observation field of microscope is the area of the optically anisotropic layer when the optically anisotropic layer exists in the entire field of view of the optical microscope]; 0≦defect rate [ppm]≦1000 (3).

[4] The optical film according to any one of [1] to [3], wherein the polymerizable functional group is an acryloxy group.

[5] The optical film according to any one of [1] to [4], wherein the alignment defect includes a defect caused by microcrystals of a polymerizable liquid crystal compound.

[6] The optical film according to any one of [1] to [5], wherein the thickness of the optically anisotropic layer is not less than 0.05 μm and not more than 10 μm.

[7] A retardation laminate comprising one or more optical films according to any one of [1] to [6].

[8] A polarizing plate comprising the phase difference laminate as described in [7].

[9] The polarizing plate according to [8], which has a cut surface.

[10] The polarizing plate according to [8] or [9], which is a deformed polarizing plate.

[11] The polarizing plate according to any one of [8] to [10], which includes at least one of a panel or a touch sensor.

[12] A flexible image display device comprising the polarizing plate according to any one of [8] to [11].

According to an aspect of the present invention, an optical film having improved film strength can be provided. Furthermore, according to one aspect of the present invention, an optical film having improved processability can be provided.

10‧‧‧optical film

11‧‧‧Optical anisotropic layer

12‧‧‧Alignment layer

13‧‧‧Substrate layer

20‧‧‧Phase difference laminate

31‧‧‧The first substrate layer

32‧‧‧The first alignment layer

33‧‧‧The first retardation layer

34‧‧‧adhesion layer

35‧‧‧The second retardation layer

36‧‧‧The second alignment layer

37‧‧‧The second substrate layer

38‧‧‧adhesive layer

39‧‧‧Polarizer

40‧‧‧polarizer

FIG. 1 shows a schematic cross-sectional view of an optical film according to an aspect of the present invention.

Fig. 2 shows a schematic cross-sectional view of a retardation laminate according to an aspect of the present invention.

Fig. 3 shows a schematic cross-sectional view of a polarizing plate according to an aspect of the present invention.

FIG. 4 shows a schematic cross-sectional view of a flexible image display device according to an aspect of the present invention.

[Optical film]

An optical film according to an aspect of the present invention has an optically anisotropic layer composed of a polymer polymerized in an aligned state by a polymerizable liquid crystal compound having one or more polymerizable functional groups (hereinafter also referred to simply as "polymerizable liquid crystal compound"), and the number of alignment defects (hereinafter also referred to as specific defects) whose actual size is 0.3 μm to 50 μm per ¹ mm of the optically anisotropic layer satisfies the following formula (1).

0≦Number of alignment defects [pieces]≦14 (1)

The polymer in which the polymerizable liquid crystal compound contained in the optically anisotropic layer is polymerized in an aligned state is preferably polymerized in a state aligned in one direction. The alignment can be horizontal alignment in which the optical axis of the polymerizable liquid crystal compound aligns parallel to the plane of the optical film, or vertical alignment in which the optical axis of the polymerizable liquid crystal compound aligns vertically to the plane of the optical film. The so-called optical axis refers to the direction in which the cross-section of the refractive index ellipsoid formed by the alignment of the polymerizable liquid crystal compound in a direction perpendicular to the optical axis becomes circular, that is, the direction in which the refractive indices in the two directions are equal.

The optically anisotropic layer can exhibit an in-plane retardation by polymerizing the polymerizable liquid crystal compound in a state of proper alignment. When the polymerizable liquid crystal compound is rod-shaped, the optical axis of the polymerizable liquid crystal compound is aligned parallel to the plane of the optical film, and an in-plane phase difference can be exhibited. In this case, the direction of the optical axis coincides with the direction of the slow axis. When the polymerizable liquid crystal compound is discoid, the optical axis of the polymerizable liquid crystal compound is aligned parallel to the plane of the optical film, and an in-plane retardation can be exhibited. In this case, the direction of the optical axis is perpendicular to the direction of the slow axis. The alignment state of the polymerizable liquid crystal compound can be adjusted by the combination of the alignment film and the polymerizable liquid crystal compound described later.

Examples of polymerizable liquid crystal compounds include rod-shaped polymerizable liquid crystal compounds and discotic polymerizable liquid crystal compounds. When the rod-shaped polymerizable liquid crystal compound is aligned horizontally or vertically to the plane of the optical film, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. In the case of alignment of a discotic polymerizable liquid crystal compound, the optical axis of the polymerizable liquid crystal compound exists in a direction perpendicular to the disc surface of the polymerizable liquid crystal compound.

The polymerizable liquid crystal compound is a compound having one or more polymerizable functional groups and having liquid crystallinity. The so-called polymerizable functional group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical, an acid, or the like generated by a photopolymerization initiator described later. Examples of the polymerizable functional group include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloxy group, methacryloxy group, oxiranyl group, oxetanyl group and the like. Among them, acryloxy, methacryloxy, ethyleneoxy, oxirane and oxetanyl are more preferable, and acryloxy is more preferable. The liquid crystal property of the polymerizable liquid crystal compound can be either thermotropic liquid crystal or lyotropic liquid crystal. When thermotropic liquid crystal is classified according to order degree, it can be nematic liquid crystal or smectic liquid crystal. The polymerizable liquid crystal compound preferably has two or more polymerizable functional groups. More preferably, it has two polymerizable functional groups.

The molecular weight of the polymerizable liquid crystal compound is preferably 250 or more with respect to one polymerizable functional group. For example, when the polymerizable liquid crystal compound has two polymerizable functional groups, the molecular weight of the polymerizable liquid crystal compound may be 500 or more. When the molecular weight of a polymerizable liquid crystal compound is 250 or more with respect to one polymerizable functional group, favorable liquid crystallinity tends to be acquired easily. The molecular weight of the polymerizable liquid crystal compound is preferably not less than 280, more preferably not less than 300, more preferably not less than 400, and usually not more than 1000 per one polymerizable functional group.

The molecular weight of the polymerizable liquid crystal compound is preferably at least 500, more preferably at least 560, even more preferably at least 600, especially preferably at least 800, usually less than 2000, and may be less than 1500. The smaller the molecular weight of the polymerizable liquid crystal compound, the less likely it is to crystallize. Therefore, from the viewpoint of reducing specific defects caused by microcrystals, it is preferable to use a polymerizable liquid crystal compound with a small molecular weight. On the other hand, the larger the molecular weight of the polymerizable liquid crystal compound, the easier it is to crystallize, and there is a tendency for more alignment defects caused by crystallization. In the case of using a polymerizable liquid crystal compound with a relatively large molecular weight, for example, 500 or more, in order to make the number of specific defects within the range specified in the present invention, for example, a combination of two or more kinds of liquid crystal compounds can be used as the polymerizable liquid crystal compound to polymerize and form a polymer, or the humidity when coating the polymerizable liquid crystal compound on the substrate can be reduced.

As the rod-shaped polymerizable liquid crystal compound and the disc-shaped polymerizable liquid crystal compound, those known in the art can be used. For example, compounds having a polymerizable group among the compounds described in "3.8.6 Network (Completely Crosslinked Type)" and "6.5.1 Liquid Crystal Material b. 0-24438 A, JP-A No. 2015-163937, JP-A No. 2017-179367, JP-A No. 2016-42185, International Publication No. 2016/158940, JP-A No. 2016-224128 and the like. The optically anisotropic layer may contain only one type of polymerizable liquid crystal compound polymer, or may contain two or more types.

In recent years, no one has sought thinned optical films, and thinned optical films of polymers containing polymerizable liquid crystal compounds have also been sought. However, an optically anisotropic layer in which the polymer of the polymerizable liquid crystal compound is thin and aligned in one direction is extremely prone to cracking, and the film strength tends to be low. As a result of studies on the improvement of the film strength of the optical film, the present inventors have learned the correlation between the film strength and processability of an optically anisotropic layer composed of a polymer formed by polymerizing a polymerizable liquid crystal compound in an aligned state, and the number of alignment defects in the optically anisotropic layer. Focusing on this, the present inventors conducted further research and found that the smaller the number of the above-mentioned specific defects in the optically anisotropic layer, the better the film strength of the optical film, and the better the film strength and processability of the optically anisotropic layer when the number of specific defects satisfies the above-mentioned formula (1). Of course, it is ideally desirable for an optical film to have zero specific defects, but it is difficult to manufacture an optically anisotropic layer in which the number of specific defects is zero. Therefore, optical films usually have specific defects. When an optical film with specific defects is used or processed, the stress generated by the optical film is concentrated on the specific defects, and it is inferred that the optical film will crack or tear. Therefore, when the number of specific defects present in an optically anisotropic layer composed of an aligned polymer of a polymerizable liquid crystal compound having a specific molecular weight is small, the concentration of stress decreases, and as a result, the optical film becomes less likely to be cracked or torn, and it is considered that the processability of the optical film is improved.

The specific defect is a region where poor alignment of the polymerizable liquid crystal compound occurs, and bright spots are observed in the crossed Nicols state of an optical microscope. Specific defects also include defects caused by microcrystals and gels of polymerizable liquid crystal compounds, foreign matter, repulsion of coating films of polymerizable liquid crystal compounds, unevenness, alignment film defects, unevenness of substrates, scratches, and contamination of substrates.

The actual size of specific defects is not less than 0.3 μm and not more than 50 μm. The actual size refers to the value of the measured length of the largest portion of the contour of the identified defect when the above-mentioned bright spot is observed after canceling the cross-Nicol state of the optical microscope. For example, when the outline of a defect is identified as a circle, the actual size is the length of the diameter of the circle. For example, when the outline of a defect is recognized as a square, the actual size is the length of the diagonal of the square. When the actual size of the defect is less than 0.3 μm, it tends to be difficult to observe bright spots in the crossed Nicol state of an optical microscope. When the actual size of the defect exceeds 50 μm, the optical film tends to be unusable because it is easily recognized with the naked eye and the appearance is poor. Defects with an actual size of 0.3 μm or more and 50 μm or less are not considered as bright spots because the polarization degree of conventional polarizers is lower than the current situation, and it tends to be difficult to observe bright spots in the crossed Nicol state of an optical microscope. However, in recent years, reduction of such defects has been demanded from the viewpoint of further quality improvement. Ideally, the number of defects whose actual size exceeds 50 μm is expected to be 0/mm ² , but as long as the number of defects in the range that does not affect the appearance, film strength, and processability of the optical film can exist, it is usually 3/mm ² or less, and at most 5/mm ² or 6/mm ² . Furthermore, defects whose actual size exceeds 50 μm are almost caused by foreign matter.

The actual size may be, for example, 0.5 μm or more, or may be 1 μm or more, or may be 5 μm or more. On the other hand, the actual size may be, for example, 40 μm or less, or may be 30 μm or less, or may be 20 μm or less.

The average value of the actual size observed by the optical film may be, for example, 0.5 μm or more, or may be 1 μm or more, or may be 5 μm or more. On the other hand, the average value of the actual size may be, for example, 40 μm or less, or may be 30 μm or less, or may be 20 μm or less.

In order to make the number of specific defects satisfy the formula (1), for example, adjustment of the composition of the liquid crystal composition described later constituting the optically anisotropic layer, adjustment of manufacturing conditions, or a combination thereof can be performed.

In the case of adjusting the composition of the liquid crystal composition, for example, the ratio of the polymerizable liquid crystal compound, the ratio of the poorly soluble polymerizable liquid crystal compound, the solid concentration, etc. can be adjusted in the liquid crystal composition.

From the viewpoint of reducing specific defects caused by microcrystals in the optically anisotropic layer, the liquid crystal composition may preferably contain two or more polymerizable liquid crystal compounds, or may contain three or more polymerizable liquid crystal compounds. The upper limit of the types of polymerizable liquid crystal compounds contained in the liquid crystal composition may be, for example, 20 types. When the liquid crystal composition contains two or more polymerizable liquid crystal compounds, crystals of the polymerizable liquid crystal compounds tend to precipitate easily when the mass ratio of the main polymerizable liquid crystal compound is high. Therefore, when the mass ratio of the main polymerizable liquid crystal compound in the liquid crystal composition is low, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains two or more polymerizable liquid crystal compounds, the mass ratio of the main polymerizable liquid crystal compound in the liquid crystal composition may be, for example, 90% by mass or less, preferably 85% by mass or less, relative to the total amount of the polymerizable liquid crystal compound. The so-called microcrystals refer to crystals, crystal grains, and aggregates thereof with a size ranging from several nm to hundreds of nm. The so-called "main polymerizable liquid crystal compound" refers to the polymerizable liquid crystal compound contained in the largest proportion among the polymerizable liquid crystal compounds contained in the liquid crystal composition.

As described above, the larger the molecular weight of the polymerizable liquid crystal compound, the easier it is to crystallize, and the specific defects caused by microcrystals tend to increase. Therefore, in the case of using a polymerizable liquid crystal compound with a relatively large molecular weight, for example, a polymerizable liquid crystal compound with a molecular weight of 500 or more, in order to make the number of alignment defects within the range specified in the present invention, for example, two or more liquid crystal compounds can be combined as a polymerizable liquid crystal compound and polymerized.

Specifically, the liquid crystal composition preferably contains 2 or more polymerizable liquid crystal compounds with a molecular weight of 600 or more, more preferably 3 or more, and may contain 20 or less. The liquid crystal composition preferably contains 2 or more polymerizable liquid crystal compounds with a molecular weight of 800 or more, more preferably 3 or more, and may contain 10 or less. In such cases, the liquid crystal composition may contain a polymerizable liquid crystal compound with a molecular weight of less than 800 and less than 600.

When the liquid crystal composition contains a poorly soluble polymerizable liquid crystal compound, crystals of the poorly soluble polymerizable liquid crystal compound tend to precipitate easily. Therefore, when the mass ratio of the poorly soluble liquid crystal compound is reduced or the mass ratio of the easily soluble polymerizable liquid crystal compound is increased, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains a poorly soluble polymerizable liquid crystal compound, the total amount of the poorly soluble polymerizable liquid crystal compound relative to the polymerizable liquid crystal compound in the liquid crystal composition may be, for example, 90% by mass or less, preferably 85% by mass or less.

In the liquid crystal composition, when the amount of the solvent increases and the solid content decreases, crystals of the polymerized liquid crystal compound are less likely to be precipitated, and the number of specific defects caused by microcrystals tends to decrease. Furthermore, when the amount of solvent increases and the solid content decreases, since the solvent in the coating film is difficult to completely volatilize, the crystals of the polymerizable liquid crystal compound are difficult to precipitate, and the number of specific defects caused by microcrystals tends to decrease. The solid content of the liquid crystal composition may be, for example, 50% by mass or less, preferably 25% by mass or less.

In the liquid crystal composition, by adding monomers other than polymerizable liquid crystal compounds (such as low-molecular monomers such as acrylates and methacrylates) or polymers (such as polymers such as polyvinyl alcohol and polyethylene glycol and their modified products), or before aligning and polymerizing the polymerizable liquid crystal compounds, even if part or all of them are converted into dimers, trimers or oligomers above, the number of specific defects caused by microcrystals tends to decrease. When the liquid crystal composition contains monomers or polymers other than polymerizable liquid crystal compounds, or dimers, trimers, or oligomers of polymerizable liquid crystal compounds, the solubility to solvents tends to be improved and precipitation of crystals tends to be easily suppressed.

When adjusting the production conditions, for example, the temperature of the substrate when coating the liquid crystal composition, the humidity of the surrounding environment during coating, the surrounding environment of the die used for coating, and the like can be adjusted.

By keeping the substrate on which the liquid crystal composition is applied at a constant temperature when the liquid crystal composition is applied, the number of specific defects caused by microcrystals tends to decrease. The temperature of the heat preservation can be, for example, not less than 15°C and not more than 60°C, preferably not less than 20°C and not more than 50°C.

By using a substrate with good surface smoothness and improving the uniformity of the coating film of the polymerizable liquid crystal compound, the number of specific defects caused by coating film repulsion caused by the polymerizable liquid crystal compound and defects in the alignment film tends to decrease. As means for improving the surface smoothness of the base material, for example, annealing (surface repair) and the like. Annealing can be performed by heating the substrate. The heating temperature is, for example, 60°C to 100°C, or a temperature 5 to 20°C lower than the glass transition point of the substrate, and the heating time is, for example, 1 second to 60 seconds.

By keeping the humidity of the surrounding environment constant during coating, the crystallization of the polymerizable liquid crystal compound is suppressed, and the number of specific defects caused by microcrystals tends to decrease. The humidity of the surrounding environment during coating is, for example, below 90%RH, preferably below 85%RH, more preferably below 60%RH, more preferably below 55%RH, especially preferably below 40%RH. On the other hand, the humidity of the surrounding environment during coating may be, for example, 10% RH or higher, preferably 20% RH or higher. In the case of using a polymerizable liquid crystal compound with a relatively high molecular weight, the humidity can be reduced when coating the polymerizable liquid crystal compound on the substrate so that the number of specific defects falls within the range specified in the present invention.

By adjusting the surrounding environment of the die used for coating to the vapor pressure of the solvent contained in the polymerizable liquid crystal compound (under a solvent environment), the solvent of the polymerizable liquid crystal compound becomes less volatile, crystallization of the polymerizable liquid crystal compound can be suppressed, and the number of specific defects caused by microcrystals tends to decrease.

Before coating the polymerizable liquid crystal compound, by removing the contamination on the substrate surface, such as PET lubricant, PET oligomer, silicone oil, etc., the number of specific defects caused by foreign matter tends to decrease. Furthermore, by applying the polymerizable liquid crystal compound in a clean room with a high degree of cleanliness, the number of specific defects caused by foreign matter tends to decrease. Furthermore, by removing foreign matter, microcrystals, etc. in the liquid crystal composition before coating with a filter, the number of specific defects caused by microcrystals and foreign matter tends to decrease.

The number of specific defects per 1 mm ² of the optically anisotropic layer is preferably at most 10, more preferably at most 7, more preferably at most 6, particularly preferably at most 3, and most preferably at most 1. In addition, the number of specific defects per 1 mm ² of the optically anisotropic layer is preferably 0, may be 0.001 or more, and may be 0.01 or more.

The ratio of the number of specific defects per 1 mm ² of the optically anisotropic layer to the number of defects caused by microcrystals may be, for example, 70% or more, or may be 85% or more, preferably 90% or more. In the case of microcrystals, it is presumed that when microcrystals exist in the optically anisotropic layer, when stress is applied, the crystal part becomes a stress concentration point and is destroyed. Therefore, it is estimated that when more than 70% of the specific defects are caused by microcrystals, the number of specific defects caused by microcrystals is reduced to 14 or less, and the stress is moderately dispersed in the thickness of the optically anisotropic layer of the present invention, and the film strength increases.

The ratio of the number of specific defects per 1 mm ² of the optically anisotropic layer to the number of defects caused by foreign matter may be, for example, 10% or less, or 0%.

The ratio of the number of defects caused by the repulsion of the number of specific defects per 1 mm ² of the optically anisotropic layer may be, for example, 10% to 70%, or 20% to 60%.

The film strength of the optically anisotropic layer can be evaluated in accordance with the method of measuring the puncture strength described in the section of Examples described later. The puncture strength of the optical film may be, for example, not less than 5 gmm and not more than 100 gmm, preferably not less than 10 gmm and not more than 80 gmm, more preferably not less than 15 gmm and not more than 50 gmm. When the puncture strength of the optical film is within the above-mentioned range, even when the optical film is thinned, it tends to be easy to obtain good film strength.

The film strength of the optically anisotropic layer can be evaluated in accordance with the method of measuring the puncture strength described in the section of Examples described later. The puncture strength of the optical film may be, for example, not less than 5 gmm and not more than 100 gmm, preferably not less than 10 gmm and not more than 80 gmm, more preferably not less than 15 gmm and not more than 50 gmm. When the puncture strength of the optical film is within the above-mentioned range, even when the optical film is thinned, it tends to be easy to obtain good film strength.

The film strength of the optically anisotropic layer can be evaluated in accordance with the measuring method of tensile stress described in the section of Examples described later. The tensile stress of the optical film can be, for example, 30N/mm ² to 200N/mm ² , preferably 40N/mm ² to 150N/mm ² , more preferably 50N/mm ² to 100N/mm ² . When the tensile stress of the optical film is within the above range, even when the optical film is thinned, it tends to be easy to obtain good film strength.

The optical film may further have a substrate layer and an alignment layer in addition to the optically anisotropic layer.

The base layer can be composed of, for example, a resin film or the like. The resin constituting the resin film is a light-transmitting thermoplastic resin, preferably an optically transparent thermoplastic resin, for example: polyolefin resins such as polyethylene and polypropylene; cyclic polyolefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; Cellulose ester-based resins such as cellulose acid esters; vinyl alcohol-based resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate-based resins; polystyrene-based resins; polyarylate-based resins; polyamide-based resins; polyether-based resins; polyamide-based resins; Among these resins, it is preferable to use any one of cyclic polyolefin resins, polyester resins, cellulose ester resins, and (meth)acrylic resins, or a mixture thereof.

The thickness of the substrate layer may be, for example, 1 μm to 300 μm, preferably from 5 μm to 200 μm, more preferably from 10 μm to 120 μm, from the viewpoint of workability such as strength and handleability.

The heat capacity per ¹ cm of the substrate layer is not particularly limited. From the viewpoint of easy control of the temperature of the optical film by environmental temperature control devices such as drying ovens and cooling furnaces, the heat capacity per 1 ^cm of the substrate layer is preferably 0.1J/cm ² ‧℃ or less, more preferably 0.05J/cm ² ‧℃ or less, and more preferably 0.03J/cm ² ‧℃ or less. Here, the heat capacity per 1 cm ² of the base material layer refers to the heat capacity of the volume contained when only 1 cm ² of the base material layer is cut out.

Furthermore, the specific heat of the substrate layer is not particularly limited, but from the same point of view, it is preferably 2,000 J/kg‧°C or less, more preferably 1,500 J/kg‧°C or less.

In the case where the optical film has a substrate layer and an alignment layer, in order to improve the adhesion between the substrate layer and the alignment layer, corona treatment, plasma treatment, flame treatment, etc. can be performed on the surface of the substrate layer on the side where the alignment layer is formed to form an undercoat layer.

The alignment layer system has an alignment control force for aligning the polymerizable liquid crystal compound in a desired direction. The alignment layer system can include, for example, an alignment polymer layer formed by an alignment polymer, a photo-alignment polymer layer formed by a photo-alignment polymer, a groove alignment layer with a concave-convex pattern and multiple grooves (grooves) on the surface of the layer. The thickness of the alignment layer is usually not less than 10nm and not more than 4000nm, preferably not less than 50nm and not more than 3000nm.

The alignment polymer layer can be formed by applying a composition in which the alignment polymer is dissolved in a solvent to the substrate layer, removing the solvent, and performing brushing treatment as needed. In this case, in the alignment polymer layer formed of the alignment polymer, the alignment control force can be arbitrarily adjusted by the surface state of the alignment polymer and the wiping conditions.

The photo-alignment polymer layer can be formed by applying a composition containing a polymer having a photoreactive group or a monomer and a solvent (hereinafter also referred to as a composition for forming a photo-alignment film) on a substrate layer, and then irradiating it with light such as ultraviolet rays. In particular, when an alignment control force is exhibited in the horizontal direction, it can be formed by irradiating polarized light. In this case, in the photo-alignment polymer layer, the alignment control force can be arbitrarily adjusted by the conditions of irradiation of polarized light on the photo-alignment polymer, and the like.

The groove alignment layer system can be formed by, for example, the following methods: a method of exposing and developing a concave-convex pattern on the surface of the photosensitive polyimide film through an exposure mask having pattern-shaped slits; a method of forming an uncured layer of an active energy ray-curable resin on a plate-shaped master having grooves on the surface, transferring this layer to a base layer and curing it; A method of hardening after forming unevenness on a disk.

When the optical film includes a base layer and an alignment layer, when the base layer is peeled off, the base layer and the alignment layer may be peeled off together, or the alignment layer may remain on the optically anisotropic layer. The alignment layer is peeled off together with the substrate layer or remains in the optically anisotropic layer, which can be set by adjusting the relationship between the adhesive forces between the layers, and can be adjusted by, for example, subjecting the substrate layer to surface treatments such as corona treatment, plasma treatment, flame treatment, and primer layer, or the components of the liquid crystal composition used to form the optically anisotropic layer.

An optical film according to another aspect of the present invention has an optically anisotropic layer composed of a polymer formed by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state, and is characterized in that the defect rate defined by the following formula (2) in the optically anisotropic layer satisfies the following formula (3).

[In the formula, the total defect area is the sum of the defect areas whose actual size is not less than 0.3 μm and not more than 50 μm observed in one field of view of the optical microscope, and the field of view of the microscope is the area of the optically anisotropic layer observed in one field of view of the above-mentioned optical microscope]

0≦defect rate [ppm]≦1000 (3).

The microscope observation field of formula (2) can be, for example, 4.53 mm ² . The defect rate can be determined according to the method of measuring the defect rate described in the section of Examples described later.

When the defect rate of the optically anisotropic layer satisfies the formula (3), the film strength and processability of the optically anisotropic layer tend to become better. From the viewpoint of film strength and processability of the optically anisotropic layer, the defect rate of the optically anisotropic layer is preferably at most 600 ppm, more preferably at most 300 ppm, more preferably at most 100 ppm, and most preferably at most 50 ppm. The defect rate of the optically anisotropic layer is ideally 0 ppm, may be 0.01 ppm or more, and may be 0.1 ppm or more.

In order to make the defect rate of the optically anisotropic layer satisfy the formula (3), for example, the type of polymerizable liquid crystal compound, selection of molecular weight, adjustment of composition, adjustment of manufacturing conditions, and combinations thereof can be performed. Specific examples of the type of polymerizable liquid crystal compound, selection of molecular weight, adjustment of composition, and adjustment of production conditions are applicable as long as the number of defects with an actual size of 0.3 μm or more and 50 μm or less per ¹ mm of the above-mentioned optically anisotropic layer satisfies the formula (1).

The optical film according to yet another aspect of the present invention has an optically anisotropic layer comprising a polymer formed by polymerizing a polymerizable liquid crystal compound having one or more polymerizable functional groups in an aligned state, and the number of defects with an actual size of 0.3 μm to 50 μm per 1 mm of the optically anisotropic layer satisfies the following formula ( ¹ ), and the defect rate defined by the following formula (2) satisfies the following formula (3).

0≦Number of alignment defects [pieces]≦14 (1);

0≦Defect rate [ppm]≦1000 (3)

[In the formula, the total defect area is the sum of the defect areas whose actual size is not less than 0.3 μm and not more than 50 μm observed in one field of view of the optical microscope, and the field of view of the microscope is the area of the optically anisotropic layer observed in one field of view of the optical microscope]

When the number of defects with an actual size of 0.3 μm to 50 μm per ¹ mm of the optically anisotropic layer satisfies the formula (1) and the defect rate satisfies the formula (3), the film strength and processability of the optically anisotropic layer tend to be improved.

The optical film system has good transparency, and can be used in various applications together with substrates and/or alignment films or various optical films in a single-layer or multi-layer structure (for example, a structure of more than 2 layers and less than 4 layers). In addition, in the case of plural laminated layers, the same film may be used, or a combination of different types may be used. Here, the term "optical film" refers to a film that can transmit light and has an optical function, and the term "optical function" refers to refraction, birefringence, and the like.

Examples of the optical film include:

The first form: a retardation film in which the rod-shaped liquid crystal compound is aligned in the horizontal direction to the support substrate;

The second form: a retardation film in which the rod-shaped liquid crystal compound is aligned vertically to the support substrate;

The third form: a retardation film in which the rod-shaped liquid crystal compound changes the alignment direction in a helical manner in the plane;

The fourth form: a phase difference film with oblique alignment of discotic liquid crystal compounds;

Fifth form: a biaxial retardation film in which a discotic liquid crystal compound is aligned perpendicular to a support substrate.

The retardation value (Re(550nm)) of the optical film at a wavelength of 550nm can be, for example, 113nm to 163nm, preferably 130nm to 150nm, more preferably about 135nm to 150nm. When the optical film has a retardation value at a wavelength of 550 nm in the above-mentioned range, it is suitable as a 1/4 wavelength retardation film.

The optical film is preferably one with reverse wavelength dispersion. The so-called reverse wavelength dispersion refers to the optical characteristic that the retardation value in the short-wavelength liquid crystal alignment plane is smaller than the retardation value in the long-wavelength liquid crystal alignment plane. The optical film preferably satisfies the following formula (i) and formula (ii).

Re(450)/Re(550)≦1 (i)

1≦Re(630)/Re(550) (ii)

When the optical film is in the above-mentioned first form and has reverse wavelength dispersibility, it is preferable because it reduces coloring during black display of the display device. In formula (1), if it is 0.82≦Re(450)/Re(550)≦0.93, it is more preferable. Furthermore, 120≦Re(550)≦150 is more preferable.

When the optical film is in the above-mentioned second form, the in-plane retardation value Re(550) is adjusted to be in the range of 0 to 10 nm, preferably in the range of 0 to 5 nm, and the retardation value R _th in the thickness direction is adjusted to be in the range of -10 to -300 nm, preferably in the range of -20 to -200 nm.

The retardation value R _th in the thickness direction of the refractive index anisotropy in the thickness direction, the fast axis in the plane is the tilt axis, and can be calculated from the measured retardation value R ₅₀ and the in-plane retardation value R _e by tilting it at 50 degrees. That is, the retardation value R _th in the thickness direction can be obtained from the following equations (iv) to ( _vi ) from the in-plane retardation value R _e , the retardation value R ₅₀ measured with the fast axis as the tilt axis and tilting it at 50 degrees, the thickness _d of the retardation film, and the average refractive index n ₀ of the retardation _film .

R _th =[(n _x +n _y )/2-n _z ]×d (iii)

R _e =(n _x -n _y )×d (iv)

(n _x +n _y +n _z )/3=n ₀ (vi)

here,

In order to use the optical film as an optical film for VA (vertical alignment) mode, the content of the polymerizable liquid crystal compound in the liquid crystal composition may be appropriately adjusted to adjust the thickness of the optical film. Specifically, the film thickness can be adjusted so that Re(550) is, for example, not less than 40 nm and not more than 100 nm, preferably not less than 60 nm and not more than 80 nm.

[Manufacturing method of optical film]

The optical film system can be produced by, for example, preparing a liquid crystal composition, coating the liquid crystal composition on a substrate or an alignment film, drying it, and polymerizing a polymerizable liquid crystal compound.

<Liquid crystal composition>

The liquid crystal composition can be prepared by mixing a polymerizable liquid crystal compound with optional solvents, polymerization initiators, sensitizers, polymerization inhibitors, and/or leveling agents.

The larger the molecular weight of the polymerizable liquid crystal compound, the easier it is to crystallize. Since the specific defects caused by microcrystals tend to increase, in the case of using a polymerizable liquid crystal compound with a larger molecular weight, in order to make the number of specific defects within the range specified in the present invention, for example, two or more liquid crystal compounds can be combined as polymerizable liquid crystal compounds to be polymerized.

(polymerizable liquid crystal compound)

As the polymerizable liquid crystal compound, for example, JP 2011-207765 A, JP 2010-24438 A, JP 2015-163937 A, JP 2017-179367 A, JP 2016-42185 A, International Publication No. 2016/158940, JP Those exemplified in the Publication No. 2016-224128, etc. The polymerizable liquid crystal compound has 1 or more polymerizable functional groups, preferably has 2 or more polymerizable functional groups, more preferably has 2 or more and 4 or less polymerizable functional groups, and more preferably has 2 polymerizable functional groups.

The molecular weight of the polymerizable liquid crystal compound may be, for example, 250 or more with respect to one polymerizable functional group. For example, when the polymerizable liquid crystal compound has two polymerizable functional groups, the molecular weight of the polymerizable liquid crystal compound may be 500 or more, 600 or more, or 800 or more. When the molecular weight of a polymerizable liquid crystal compound is 250 or more with respect to one polymerizable functional group, favorable liquid crystallinity tends to be acquired easily. The molecular weight of the polymerizable liquid crystal compound is preferably not less than 280, more preferably not less than 300, more preferably not less than 400, and usually not more than 1000 per one polymerizable functional group.

The molecular weight of the polymerizable liquid crystal compound is preferably at least 500, more preferably at least 560, more preferably at least 600, even more preferably at least 800, usually less than 2000, and may be less than 1500.

The polymerizable liquid crystal compound is, for example, a compound that satisfies all of the following (1) to (4).

(1) A compound that can form a nematic phase;

(2) It has π electrons in the major axis direction (a) of the polymerizable liquid crystal compound.

(3) There are π electrons in the direction intersecting with the major axis direction (a) [intersecting direction (b)].

(4) The sum of the π electrons present in the major axis direction (a) is N(πa), the sum of the molecular weights present in the major axis direction is N(Aa), and the π electron density in the major axis direction (a) of the polymerizable liquid crystal compound defined by the following formula (i):

D(πa)=N(πa)/N(Aa) (i)

And the sum of the π electrons existing in the crossing direction (b) is N(πb), the sum of the molecular weights present in the crossing direction is N(Ab), and the π electron density of the crossing direction (b) of the polymerizable liquid crystal compound defined by the following formula (ii):

D(πb)=N(πb)/N(Ab) (ii)

have

The relationship of 0≦[D(πa)/D(πb)]≦1 [that is, the π-electron density in the cross direction (b) is greater than the π-electron density in the long-axis direction (a)].

Furthermore, the polymerizable liquid crystal compound that satisfies all of the above (1) to (4) can form a nematic phase by, for example, coating on an alignment film and heating to a temperature above the phase transition temperature. The nematic phase formed by the alignment of the polymerizable liquid crystal compound is usually aligned with the long axes of the polymerizable liquid crystal compound parallel to each other, and the long axis direction becomes the alignment direction of the nematic phase.

Since the compound satisfying the above (3) has π electrons in the intersecting direction (b), it tends to be easily crystallized due to π-π interaction. According to this embodiment, even when such a polymerizable liquid crystal compound is used, the number of specific defects caused by microcrystals can be reduced.

Polymerizable liquid crystal compounds having the above characteristics generally exhibit reverse wavelength dispersion. As a compound that satisfies the characteristics of the above-mentioned (1) to (4), specifically, the following formula (I) can be exemplified:

所示的化合物。

Compounds shown.

In formula (I), Ar represents a divalent aromatic group which may have a substituent. The term "aromatic group" here refers to a group having a planar ring structure, and the number of π electrons in the ring structure is [4n+2] according to Hückel's law. Here, n represents an integer. In the case of forming a ring structure including heteroatoms such as -N=, -S-, it also includes: including non-covalent bond electron pairs on these heteroatoms, satisfying Huckel's law, and having aromaticity. Among the divalent aromatic groups, those containing at least one of a nitrogen atom, an oxygen atom, and a sulfur atom are preferable.

G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted by a halogen atom, an alkyl group having 1 to 4 carbons, a fluoroalkyl group having 1 to 4 carbons, an alkoxy group having 1 to 4 carbons, a cyano group or a nitro group, and the carbon atoms constituting the divalent aromatic group or alicyclic hydrocarbon group may be substituted by an oxygen atom, a sulfur atom or a nitrogen atom.

L ¹ , L ² , B ¹ and B ² are each independently a single bond or a divalent linking group.

k and l each independently represent an integer of 0 to 3, and satisfy the relationship of 1≦k+1. Here, in the case of 2≦k+1, B ¹ and B ² , G ¹ and G ² may be the same as or different from each other.

E ¹ and E ² independently represent an alkanediyl group having 1 to 17 carbon atoms, where the hydrogen atoms contained in the alkanediyl group may be substituted by halogen atoms, and the -CH ₂ - contained in the alkanediyl group may be substituted by -O-, -S-, or -Si-.

P ¹ and P ² independently represent a polymerizable functional group or a hydrogen atom, and at least one of them is a polymerizable functional group.

^G1 and ^G2 are each independently preferably 1,4-benzenediyl which may be substituted by at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbons, or 1,4-cyclohexanediyl which may be substituted by at least one substituent selected from a group consisting of a halogen atom and an alkyl group having 1 to 4 carbons. Preferably, unsubstituted 1,4-benzenediyl or unsubstituted 1,4-trans-cyclohexanediyl is more preferred.

Furthermore, it is preferable that at least one of the plural G ¹ and G ² is a divalent alicyclic hydrocarbon group, and more preferably at least one of the G ¹ and G ² bonded to L ¹ or L ² is a divalent alicyclic hydrocarbon group.

C-更佳。此處，R^a1至R^a8分別獨立地表示單鍵或碳數1至4的伸烷基，R^c及R^d表示碳數1至4的烷基或氫原子。L¹及L²分別獨立地以單鍵、-OR^a2-1-、-CH₂-、-CH₂CH₂-、-COOR^a4-1-或OCOR^a6-1-為佳。此處，R^a2-1、R^a4-1、R^a6-1，分別獨立地表示單鍵、-CH₂-、-CH₂CH₂-的任一者。L¹及L²分別獨立地以單鍵、-O-、-CH₂CH₂-、-COO-、-COO CH₂CH₂-或OCO-更佳。 L ¹ and L ² are independently single bond, alkylene group with 1 to 4 carbons, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC=OOR ^a8 -, -N=N-, -CR ^c =CR ^d -, or C

C-better. Here, R ^a1 to R ^a8 each independently represent a single bond or an alkylene group having 1 to 4 carbons, and R ^c and R ^d represent an alkyl group having 1 to 4 carbons or a hydrogen atom. L ¹ and L ² are each independently preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 - or OCOR ^a6-1 -. Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent any of a single bond, -CH ₂ -, and -CH ₂ CH ₂ -. L ¹ and L ² are preferably each independently a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COO CH ₂ CH ₂ - or OCO-.

Preferably, B ¹ and B ² are each independently a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 - or R ^a15 OC=OOR ^a16 -. Here, R ^a9 to R ^a16 each independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 - or OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 , and R ^a14-1 each independently represent any of a single bond, -CH ₂ -, and -CH ₂ CH ₂ -. B ¹ and B ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO- or OCOCH ₂ CH ₂ -.

From the viewpoint of reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, more preferably k+l=4, k=2 and l=2. When k=2 and l=2, it is preferable because it becomes a symmetrical structure.

E ¹ and E ² are each independently preferably an alkanediyl group having 1 to 17 carbon atoms, more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable functional group represented by ^P1 or ^P2 include epoxy group, vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloxy group, methacryloxy group, oxiranyl group, and oxetanyl group. Among them, acryloxy, methacryloxy, ethyleneoxy, oxirane and oxetanyl are preferred, and acryloxy is more preferred.

The Ar system preferably has at least one selected from an optionally substituted aromatic hydrocarbon ring, an optionally substituted aromatic heterocyclic ring, and an electron-attracting group. The aromatic hydrocarbon ring includes, for example, a benzene ring, a naphthalene ring, an anthracene ring, and the like, preferably a benzene ring and a naphthalene ring. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, those having a thiazole ring, a benzothiazole ring or a benzofuran ring are preferable, and those having a benzothiazole ring are more preferable. Furthermore, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (I), the total number Nπ of π electrons contained in the divalent aromatic group represented by Ar is preferably 8 or more, more preferably 10 or more, more preferably 14 or more, and most preferably 16 or more. Moreover, it is better to be below 30, better to be below 26, and even better to be below 24.

Examples of the aromatic group represented by Ar include the following groups.

In formula (Ar-1) to formula (Ar-23), * represents the connecting part, Z⁰,Z¹and Z²Each independently represents a hydrogen atom, a halogen atom, an alkyl group with 1 to 12 carbons, a cyano group, a nitro group, an alkylsulfinyl group with 1 to 12 carbons, an alkylsulfonyl group with 1 to 12 carbons, a carboxyl group, a fluoroalkyl group with 1 to 12 carbons, an alkoxy group with 1 to 6 carbons, an alkylthio group with 1 to 12 carbons, an N-alkylamine group with 1 to 12 carbons, an N,N-dialkylamino group with 1 to 12 carbons, or a carbon number 1 to 1 2 N-alkylsulfamoyl group or N,N-dialkylsulfamoyl group with 2 to 12 carbons.

Q ¹ , Q ² and Q ³ each independently represent -CR ^2' R ^3' -, -S-, -NH-, -NR ^2' -, -CO- or O-, R ^2' and R ^3' each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbons.

J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.

Y ¹ , Y ² and Y ³ each independently represent an optionally substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group or a halogen atom, and m represents an integer of 0 to 6.

The aromatic hydrocarbon groups of Y ¹ , Y ² and Y ³ include aromatic hydrocarbon groups with 6 to 20 carbons such as phenyl, naphthyl, anthracenyl, phenanthryl, and biphenyl, preferably phenyl and naphthyl, and more preferably phenyl. Examples of the aromatic heterocyclic group include: furyl, pyrrolyl, thienyl, pyridyl, thiazolyl, benzothiazolyl and other aromatic heterocyclic groups with 4 to 20 carbon atoms containing at least one of heteroatoms such as nitrogen atoms, oxygen atoms, and sulfur atoms. Furanyl, thienyl, pyridyl, thiazolyl, and benzothiazolyl are preferred.

Each of Y ¹ , Y ² and Y ³ independently may be an optionally substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. A polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aggregate of aromatic rings. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aggregate of aromatic rings.

Z ⁰ , Z ¹ and Z ² are independently preferably hydrogen atom, halogen atom, alkyl group with 1 to 12 carbons, cyano group, nitro group, alkoxy group with 1 to 12 carbon atoms, Z ⁰ is more preferably hydrogen atom, alkyl group with 1 to 12 carbon atoms, and cyano group, and Z ¹ and Z ² are more preferably hydrogen atom, fluorine atom, chlorine atom, methyl group or cyano group.

Q ¹ , Q ² and Q ³ are preferably -NH-, -S-, -NR ^2' -, -O-, and R ^2' is preferably a hydrogen atom. Among them, -S-, -O-, and -NH- are particularly preferred.

Among formula (Ar-1) to formula (Ar-23), formula (Ar-6) and formula (Ar-7) are preferable from the viewpoint of molecular stability.

In formula (Ar-16) to formula (Ar-23), Y ¹ can form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ⁰ . As the aromatic heterocyclic group, the above-mentioned aromatic heterocyclic group that may be included as Ar can be mentioned, for example: pyrrole ring, imidazole ring, pyrroline ring, pyridine ring, pyrazine ring, pyrimidine ring, indole ring, quinoline ring, isoquinoline ring, purine ring, pyrrolidine ring, etc. This aromatic heterocyclic group may have a substituent. Furthermore, Y ¹ and the nitrogen atom to which it may be bonded are, together with Z ⁰ , the aforementioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted. Examples thereof include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

As a compound satisfying the above-mentioned characteristics (1) to (4), for example, a compound in which Ar of the above-mentioned formula (I) is a group (II) having the following structure.

In formula (II), * represents a linking part with ^L1 or ^L2 .

^D1 and ^D2 each independently represent a group selected from the following general formula (D-1).

C-取代之碳數1至20的直鏈狀或分支狀的烷基。該烷基中之任意的氫原子可經氟原子取代。 取代基X、X ¹及X ²分別獨立地表示氟原子、氯原子、溴原子、碘原子、五氟硫烷基、硝基、氰基、異氰基、胺基、羥基、巰基、甲基胺基、二甲基胺基、二乙基胺基、二異丙基胺基、三甲基矽基、二甲基矽基、硫異氰基、或1個-CH ₂ -或不相鄰的2個以上的-CH ₂ -分別獨立地可經-O-、-S-、 -CO-、-COO-、-OCO-、-CO-S-、-S-CO-、-O-CO-O-、-CO-NH-、-NH-CO-、-CH=CH-COO-、-CH=CH-OCO-、-COO-CH=CH-、-OCO-CH=CH-、-CH=CH-、-CF=CF-或-C

C-substituted linear or branched alkyl group with 1 to 20 carbons. Arbitrary hydrogen atoms in the alkyl group may be substituted with fluorine atoms.

In the general formula (D-1), M ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbons. This alkyl group may be substituted with one or more of the aforementioned substituents X, or may be unsubstituted.

U ¹ represents an organic group having 2 to 30 carbon atoms having an aromatic hydrocarbon group. Any carbon atom of the aromatic hydrocarbon group may be substituted with a heteroatom. The aromatic hydrocarbon group may be substituted with one or more of the aforementioned substituents X, or may be unsubstituted.

C-取代。該環烷基或環烯基中的1個-CH₂-或不相鄰的2個以上的-CH₂-分別獨立地可經-O-、-CO-、-COO-、-OCO-或-O-CO-O-取代。U¹及U²可鍵結構成環。 T ¹ represents -O-, -S-, -COO-, -OCO-, -OCO-O-, -NU ² -, -N=CU ² -, -CO-NU ² -, -OCO-NU ² -, or -O-NU ² -. ^U represents a hydrogen atom, an alkyl group with 1 to 20 carbons, a cycloalkyl group with 3 to 12 carbons, a cycloalkenyl group with 3 to 12 carbons, or an organic group with 2 to 30 carbons having an aromatic hydrocarbon group (any carbon atom of the aromatic hydrocarbon group may be replaced by a heteroatom). Each of the alkyl group, cycloalkyl group, cycloalkenyl group and aromatic hydrocarbon group may be substituted with one or more of the aforementioned substituents X, or may be unsubstituted. The alkyl group may be substituted by the cycloalkyl group or cycloalkenyl group. One -CH ₂ - or two or more non-adjacent -CH ₂ -s in the alkyl group can independently pass through -O-, -S-, -CO-, -COO-, -OCO-, -CO-S-, -S-CO-, -SO ₂ -, -O-CO-O-, -CO-NH-, -NH-CO-, -CH=CH-COO-, -CH=CH-OCO-, -COO-CH=CH-, -OCO- CH=CH-, -CH=CH-, -CF=CF-, or -C

C-substitution. One -CH ₂ - or two or more non-adjacent -CH ₂ - in the cycloalkyl or cycloalkenyl may be independently substituted by -O-, -CO-, -COO-, -OCO- or -O-CO-O-. U ¹ and U ² can be bonded to form a ring.

In the general formula (D-1), M ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbons. The hydrogen atom which this alkyl group has may be substituted with a fluorine atom. M ¹ is preferably a hydrogen atom.

From the viewpoint of better wavelength dispersibility, the U ¹ group is preferably an organic group having an aromatic heterocycle substituted with one or more carbon atoms by a heteroatom. From the viewpoint of good wavelength dispersion and high birefringence, U ¹ is more preferably an organic group having a condensed aromatic heterocyclic ring belonging to a 5-membered ring and a 6-membered ring.

It is preferable that U ¹ is a group represented by the following formula. Again, such groups have a bond to ^T1 at any position.

From the viewpoint of good birefringence and easy synthesis, T ¹ is preferably -O-, -S-, -N=CU ² - or -NU ² -. From the viewpoint of good wavelength dispersion and birefringence, T ¹ is more preferably -O-, -S- or -NU ² -.

Here, ^U2 may be substituted by one or more of the aforementioned substituents X, one _-CH2- or two or more non-adjacent _-CH2 -s may be independently substituted by -O-, -CO-, -COO-, -OCO- or -O-CO-O-, and may be substituted by an alkyl or alkenyl group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 12 carbon atoms, or a cycloalkenyl group with 3 to 12 carbon atoms, or the cycloalkyl, cycloalkenyl or aryl group. Alkenyl is preferred.

Among them, from the viewpoint of birefringence and solvent solubility, ^U2 is more preferably a straight-chain alkyl group with 2 to 20 carbon atoms that can be substituted by a hydrogen atom by a fluorine atom, and one _-CH2- or two or more non-adjacent _-CH2 -s can be independently substituted by -O-, -CO-, -COO-, -OCO-.

U ¹ and U ² can be bonded to form a ring. In this case, for example, a cyclic group represented by -NU ¹ U ² or a cyclic group represented by -N=CU ¹ U ² .

D ¹ and D ² each represent a group selected from the following formula (D-1) to formula (D-47), and are particularly preferred from the viewpoint of easy acquisition of raw materials, good solubility, and high birefringence.

The content of the polymerizable liquid crystal compound in the liquid crystal composition is usually not less than 50 parts by mass and not more than 99.5 parts by mass, preferably not less than 60 parts by mass and not more than 99 parts by mass, more preferably not less than 70 parts by mass and not more than 98 parts by mass, and more preferably not less than 80 parts by mass and not more than 97 parts by mass, based on 100 parts by mass of the solid content of the liquid crystal composition. The content ratio of a polymeric liquid crystal exists in the said range, for example, and there exists a tendency for orientation to become high. Here, the term "solid content" refers to the total amount of components of the liquid crystal composition excluding the solvent.

From the viewpoint of reducing defects caused by microcrystals in the optically anisotropic layer, the liquid crystal composition preferably contains two or more polymerizable liquid crystal compounds. When the liquid crystal composition contains two or more polymerizable liquid crystal compounds, the liquid crystal composition contains the main polymerizable liquid crystal compound, for example, 90% by mass or less, preferably 85% by mass or less of the total polymerizable liquid crystal compound.

From the viewpoint of improving solubility in solvents, the liquid crystal composition preferably contains dimers, trimers, or oligomers thereof together with a polymerizable liquid crystal compound. This tends to easily suppress the precipitation of fine crystals.

(solvent)

When the liquid crystal composition contains an organic solvent, since the precipitation of crystals of the polymerizable liquid crystal compound contained in the liquid crystal composition can be suppressed, it tends to be easy to suppress the occurrence of defects caused by microcrystals in the optically anisotropic layer. Furthermore, when the liquid crystal composition contains an organic solvent, the handling and film formation at the time of forming an optical film tend to be easier. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound and is inert to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of solvents include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; Aliphatic hydrocarbon solvents such as alkanes; aromatic hydrocarbon solvents such as toluene and xylene, nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorinated solvents such as chloroform and chlorobenzene; These solvents may be used alone or in combination of two or more.

The content of the solvent is preferably not less than 50% by mass and not more than 98% by mass relative to the total amount of the liquid crystal composition. In other words, the solid content of the liquid crystal composition is preferably not less than 2% by mass and not more than 50% by mass. When the solid content is 50% by mass or less, since the viscosity of the liquid crystal composition becomes low, the thickness of the polarizing layer 12 becomes slightly uniform, and unevenness tends to be less likely to occur in the polarizing layer 12 . Moreover, the content of such solid content can be determined in consideration of the thickness of the polarizing layer 12 to be manufactured.

(polymerization initiator)

The liquid crystal composition may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating polymerization reactions such as polymerizable liquid crystals. The polymerization initiator is preferably a photopolymerization initiator that generates active radicals by the action of light from the viewpoint of not depending on the phase state of the thermotropic liquid crystal.

As a polymerization initiator, a benzoin compound, a benzophenone compound, an alkyl phenone compound, an acyl phosphine oxide compound, a triazine compound, an iodonium salt, a perium salt, etc. are mentioned, for example.

Examples of the benzoin compound include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of the benzophenone compound include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3',4,4'-tetrakis(3-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

Examples of the alkylphenone compound include diethoxyacetophenone, 2-methyl-2-N-morpholino-1-(4-methylthiophenyl)propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1 Oligomers of [4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one, etc.

Examples of the acylphosphine oxide compound include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and the like.

Examples of triazine compounds include 2,4-bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methyl Furan-2-yl)vinyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)vinyl]-1,3,5-triazine and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethyl oxyphenyl)vinyl]-1,3,5-triazine, etc.

A commercially available item can be used as a polymerization initiator. The commercially available agglomeration can be listed. For example: IRGACURE (registered trademark) 907, 184, 651, 819, 250 and 369, 379, 127, 754, Oxe01, Oxe02, Oxe03 (System System); SEIKUOL (registered trademark) BZ, Z and Bee Company system); KayAcure (registered trademark) BP100 and UVI-6992 (System of Daofe Chemistry Co., Ltd.); Adekaoptomer SP-152, N-1717, N-1919, SP-170, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (Adeka Co., Ltd. System); Taz-A and TAZ-PP (System System of Siber Hegner Co., Ltd.); TAZ-104 (Sanhe Chemical Co., Ltd.); et al. The polymerization initiator in the liquid crystal composition may be 1 type, and a plurality of 2 or more types of polymerization initiators may be mixed according to the light source.

The content of the polymerization initiator in the liquid crystal composition can be appropriately adjusted according to the type and amount of the polymerizable liquid crystal compound, and is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When content of a polymerization initiator is in the said range, it can superpose|polymerize without disturbing the alignment of a polymerizable liquid crystal.

(sensitizer)

The liquid crystal composition may contain a sensitizer. The sensitizer is preferably a photosensitizer. Examples of the sensitizer include: xanthone compounds such as xanthone and thioxanthone (such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy-containing anthracene (such as dibutoxyanthracene), etc.; phenthiazine and rubrene.

When the liquid crystal composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the liquid crystal composition can be further accelerated. Such a sensitizer is used in an amount of 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound.

(polymerization inhibitor)

From the viewpoint of stably advancing the polymerization reaction, the liquid crystal composition may contain a polymerization inhibitor. The progress of the polymerization reaction of the polymerizable liquid crystal compound can be controlled by the polymerization inhibitor.

Examples of polymerization inhibitors include radical scavengers such as hydroquinone, alkoxy-containing hydroquinone, alkoxy-containing catechol (such as butylcatechol), pyrogallol, and 2,2,6,6-tetramethyl-1-piperidinyloxy radical; thiophenols; β-naphthylamines; β-naphthols, etc.

When the liquid crystal composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When content of a polymerization inhibitor is in the said range, it can superpose|polymerize without disturbing the alignment of a polymerizable liquid crystal.

(leveling agent)

The liquid crystal composition may contain a leveling agent. The so-called leveling agent refers to an additive that has the function of adjusting the fluidity of the composition and making the film obtained by coating the composition more flat, such as organically modified silicone oil-based, polyacrylate-based and perfluoroalkyl-based leveling agents. Specifically, the above series can be listed as: DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all of the above are manufactured by TORAY‧DOW CORNING Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22-16 1A, KF6001 (manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (manufactured by Momentive Performance Materials LLC), Flourinert (registered trademark) FC-72, FC-40, same FC-43, same FC-3283 (all of the above are made by Sumitomo 3M Co., Ltd.), MEGAFAC (registered trademark) R-08, same R-30, same R-90, same F-410, same F-411, same F-443, same F-445, same F-470, same F-477, same F-479, same F-482, same F-483 (the above are all DIC Co., Ltd. ), EFTOP (registered trademark) EF301, EF303, EF351, EF352 (all of the above are manufactured by Mitsubishi Materials Corporation), SURFLON (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, SA-100 (all of the above are manufactured by AGC SEIMI Chemical Co., Ltd.), trade name E1 830, the same as E5844 (manufactured by Daikin Institute of Fine Chemicals Co., Ltd.), BM-1000, BM-1100, BYK-352, BYK-353 and BYK-361N (all trade names: manufactured by BM CHEMIE), etc. Among them, polyacrylate-based and perfluoroalkyl-based leveling agents are preferred.

When the liquid crystal composition contains a leveling agent, relative to 100 parts by mass of the polymerizable liquid crystal compound, it is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 5 parts by mass, more preferably 0.1 to 3 parts by mass. When content of a leveling agent is in the said range, it will become easy to align a polymerizable liquid crystal compound horizontally, and the obtained polarizing film will tend to be smoother. When content of a leveling agent exceeds the said range with respect to a polymeric liquid crystal compound, unevenness tends to generate|occur|produce easily in the polarizing film obtained. In addition, the liquid crystal composition may contain two or more types of leveling agents.

Furthermore, by appropriately adjusting the coating amount and concentration of the liquid crystal composition, the film thickness can be adjusted to provide a desired retardation. In the case of a liquid crystal composition in which the amount of the polymerizable liquid crystal compound is constant, the retardation value (retardation value, Re(λ)) of the obtained retardation film is determined by the following formula (a), and the film thickness d can be adjusted in order to obtain a desired Re(λ).

Re(λ)=d×△n(λ) (a)

[In the formula, Re(λ) represents the retardation value of the wavelength λnm, d represents the film thickness, △n(λ) represents the birefringence of the wavelength λnm]

(Coating of liquid crystal composition)

The methods of coating the liquid crystal composition on the substrate or the alignment film include, for example, extrusion coating method, direct gravure coating method, reverse gravure coating method, CAP coating method, slit coating method, micro gravure coating method, die coating method, inkjet method, etc. Moreover, the method etc. which use coaters, such as a dip coater, a bar coater, and a spin coater, are also mentioned, for example. Among them, when continuous coating is carried out in the form of roll to roll (Roll to Roll), the coating method by micro-gravure coating method, inkjet method, slit coating method, and die coating method is preferred. When the substrate is in the form of a sheet, the spin coating method with high uniformity is preferred. In the case of roll-to-roll coating, a composition for forming an alignment film is coated on a base material to form an alignment film, and then a liquid crystal composition is continuously coated on the obtained alignment film.

By keeping the substrate on which the liquid crystal composition is applied at a constant temperature when the liquid crystal composition is applied, the number of specific defects caused by microcrystals tends to decrease. The maintained temperature may be, for example, not less than 20°C and not more than 60°C, preferably not less than 30°C and not more than 50°C.

From the viewpoint of improving the uniformity of the coating film of the polymerizable liquid crystal compound, the repelling of the coating film caused by the polymerizable liquid crystal compound, and reducing the number of specific defects of poor alignment film, the smoothness of the surface of the substrate can be improved by annealing (surface repair). The annealing temperature is, for example, 60°C to 100°C, or a temperature lower than the glass transition point of the substrate by 5°C to 20°C, and the time is, for example, 1 second to 60 seconds.

By keeping the humidity of the surrounding environment constant during coating, it becomes easier to suppress the crystallization of the polymerizable liquid crystal compound, and the number of specific defects caused by microcrystals tends to decrease. The humidity of the surrounding environment can be, for example, below 90% RH, preferably below 85% RH, more preferably below 60% RH, more preferably below 55% RH, and most preferably below 40% RH. On the other hand, the humidity of the surrounding environment during coating may be, for example, 10% RH or higher, preferably 20% RH or higher. In the case of using a polymerizable liquid crystal compound with a relatively high molecular weight, in order to keep the number of specific defects within the range specified in the present invention, the humidity at the time of coating the polymerizable liquid crystal compound on the substrate can be reduced.

By adjusting the surrounding environment of the die used for coating to the vapor pressure of the solvent contained in the polymerizable liquid crystal compound (solvent environment), the solvent of the polymerizable liquid crystal compound is less likely to volatilize, the crystallization of the polymerizable liquid crystal compound is suppressed, and the number of specific defects caused by microcrystals tends to decrease.

Regarding the substrate, from the viewpoint of reducing the number of specific defects caused by foreign matter, it is preferable to clean the substrate before coating the liquid crystal composition to remove surface contamination, such as PET lubricants, PET oligomers, silicone oil, etc.

In order to remove foreign substances, fine crystals, etc. in the applied liquid crystal composition, it is preferable to perform filtration immediately before application before application. Moreover, the coating of the liquid crystal composition is carried out in a clean room, which can reduce the number of specific defects caused by foreign matter.

(drying of liquid crystal composition)

Examples of the drying method for removing the solvent contained in the liquid crystal composition include natural drying, ventilation drying, heat drying, reduced-pressure drying, and a combination thereof. Among them, natural drying or heating drying is preferable. The drying temperature can be, for example, in the range of 0°C to 200°C, more preferably in the range of 20°C to 150°C, and more preferably in the range of 50°C to 130°C. The drying time may be, for example, not less than 10 seconds and not more than 10 minutes, preferably not less than 30 seconds and not more than 5 minutes. The alignment polymer composition can also be dried in the same way.

(polymerization of polymerizable liquid crystal compound)

As a method of polymerizing the polymerizable liquid crystal compound, photopolymerization is preferable. Photopolymerization is carried out by irradiating active energy rays to the polymerizable liquid crystal compound of the laminate coated with the liquid crystal composition on the substrate or the alignment film. The active energy ray to be irradiated can be appropriately selected according to the type of polymerizable liquid crystal compound contained in the dry film (especially the type of photopolymerizable functional group contained in the polymerizable liquid crystal compound), and the type and amount of the photopolymerization initiator contained in the photopolymerization initiator. Specifically, for example, one or more kinds of light selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays can be mentioned. Among them, from the point of view of easy control of the progress of the polymerization reaction and the point of being widely used as a photopolymerization device in this field, ultraviolet light is preferable, and it is preferable to select a type of polymerizable liquid crystal compound that can be photopolymerized by ultraviolet light.

As the light source of the aforementioned active energy rays, for example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources that emit light in a wavelength range of 380 nm to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc.

The ultraviolet irradiation intensity is generally not less than 10 mW/cm ² and not more than 3,000 mW/cm ² . Preferable one of the intensity of ultraviolet irradiation is the intensity of the wavelength region in which the activation of the cationic polymerization initiator or the radical polymerization initiator is effective. The light irradiation time is usually from 0.1 second to 10 minutes, preferably from 0.1 second to 5 minutes, more preferably from 0.1 second to 3 minutes, and more preferably from 0.1 second to 1 minute. Under such ultraviolet irradiation intensity for one time or multiple times, the cumulative light intensity is 10mJ/ ^cm2 to 3,000mJ/ ^cm2 , preferably 50mJ/ ^cm2 to 2,000mJ/ ^cm2 , more preferably 100mJ/ ^cm2 to 1,000mJ/ ^cm2 . When the accumulated light amount is within this range, the polymerizable liquid crystal compound is sufficiently cured, and favorable transferability tends to be easily obtained, and the coloring of the optical layered body tends to be easily controlled.

FIG. 1 shows a schematic diagram of an implementation of an optical film according to an aspect of the present invention. The optical film 10 has an optically anisotropic layer 11 , an alignment layer 12 and a substrate layer 13 in this order.

[retardation laminate]

The retardation layer system includes one or more of the aforementioned optical films. The retardation laminate has one or more retardation layers, and may be used, for example, to convert linearly polarized light into circularly polarized light or elliptically polarized light, and vice versa.

When the retardation laminate has a first retardation layer and a second retardation layer, the retardation laminate can be bonded to a polarizing plate and used as a circular polarizing plate. When used as a circular polarizing plate, the first retardation layer is a 1/4 wavelength retardation layer with reverse wavelength dispersion, and the second retardation layer is a positive C plate, or the first retardation layer is a 1/2 wavelength retardation layer, and the second retardation layer is a 1/4 wavelength retardation layer.

The retardation laminate will be described with reference to the drawings.

FIG. 2 shows a schematic diagram of an embodiment of a retardation laminate. The retardation laminate 20 has a first base material layer 31 , a first alignment layer 32 , a first retardation layer 33 , an adhesive layer 34 , a second retardation layer 35 , a second alignment layer 36 and a second base material layer 37 in this order.

The first laminate 21 composed of the first base material layer 31 , the first alignment layer 32 and the first retardation layer 33 can be composed of the above-mentioned optical film 10 of the present invention.

The second laminate 22 composed of the second retardation layer 35 , the second alignment layer 36 , and the second base material layer 37 can be composed of the above-mentioned optical film 10 of the present invention.

The adhesive layer 34 can be formed by an adhesive, an adhesive, or a combination thereof. The next layer 34 is usually one layer, but may be two or more layers. The adhesive layer 34 can be formed by applying an adhesive composition to the bonding surface of the base material layer and the retardation layer. As the coating method, common coating techniques such as die coater, cut corner coater, reverse roll coater, gravure coater, rod coater, wire bar coater, knife coater, and air knife coater can be used.

As the adhesive system, (meth)acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, and epoxy copolymer adhesives can be used.

The adhesive agent system can be formed of, for example, one or a combination of two or more of water-based adhesives, active energy ray-curable adhesives, adhesives, and the like. Examples of the water-based adhesive include polyvinyl alcohol-based resin aqueous solutions, water-based two-component urethane-based emulsion adhesives, and the like. Examples of active energy ray-curable adhesives that are cured by irradiation with active energy rays such as ultraviolet rays include, for example, those containing a polymerizable compound and a photopolymerizable initiator, those containing a photoreactive resin, and those containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers; oligomers derived from these monomers; and the like. Examples of the photopolymerization initiator include those containing active species that generate neutral radicals, anion radicals, and cationic radicals by irradiating active energy rays such as ultraviolet rays.

The thickness of the bonding layer 34 may be, for example, 0.1 μm to 25 μm, preferably 0.5 μm to 20 μm, more preferably 1 μm to 15 μm, more preferably 2 μm to 10 μm, and most preferably 2.5 μm to 5 μm.

The retardation laminate 20 can be produced, for example, by including the steps of preparing the first laminate 21 and the second retardation layer 22, forming the adhesive layer 34 on the surface of the first laminate 21 on the first retardation layer 33 side, and laminating the first laminate 21 and the second retardation layer 22 using the respective retardation layer sides as bonding surfaces.

[polarizer]

A polarizing plate such as an elliptical polarizing plate and a circular polarizing plate is provided by combining the above retardation laminate and a polarizing plate.

Since the polarizing plate of the present invention has an optically anisotropic layer with improved film strength and processability, cracks and the like tend not to occur even when cut. Therefore, the polarizing plate of the present invention is suitable as a polarizing plate having a cut surface and a deformed polarizing plate. The deformed polarizing plate may be, for example, a polarizing plate having a planar shape other than a rectangle or a square, or a polarizing plate having a through hole extending from the outermost periphery toward the inner planar region. The polarizing plate can be strip-shaped or sheet-shaped.

FIG. 3 shows a schematic diagram of an embodiment of a polarizing plate. The polarizer 40 has a polarizer 39 , an adhesive layer 38 , a first alignment layer 32 , a first retardation layer 33 , an adhesive layer 34 , a second retardation layer 35 , a second alignment layer 36 and a second substrate layer 37 in sequence.

Polarizer 39 can adopt any suitable polarizer. The so-called polarizer refers to a linear polarizer having the property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light is incident. For example, the resin film forming the polarizer may be a single-layer resin film, or may be a laminated film of two or more layers. The polarizer 39 may be a cured film in which a dichroic dye is aligned with a polymerizable liquid crystal compound to polymerize the polymerizable liquid crystal compound.

Specific examples of polarizers made of a single-layer resin film include those obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (hereinafter abbreviated as "PVA") films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films with dichroic substances such as iodine or dichroic dyes, and polyene-based alignment films such as dehydrated PVA and dehydrochlorinated polyvinyl chloride. Because of its good optical properties, it is better to use a polarizer obtained by uniaxially stretching a PVA film dyed with iodine.

Polyvinyl alcohol-based resins can be produced by saponifying polyvinyl acetate-based resins. The polyvinyl acetate-based resin may be, for example, a copolymer of vinyl acetate and other monomers copolymerizable with vinyl acetate, other than polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is usually not less than 85 mol % and not more than 100 mol %, preferably not less than 98 mol %. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually not less than 1,000 and not more than 10,000, preferably not less than 1,500 and not more than 5,000.

A film maker of such a polyvinyl alcohol-based resin uses a base film as a polarizer. The film-forming method of the polyvinyl alcohol-based resin is not particularly limited, and a known method can be used to form a film. The film thickness of the polyvinyl alcohol-based resin embryo film is, for example, 10 μm to 100 μm, preferably 10 μm to 60 μm, more preferably 15 μm to 30 μm.

As other manufacturing methods of the polarizer 39, those comprising the steps of first preparing a base film, coating a resin solution such as a polyvinyl alcohol-based resin on the base film, performing drying to remove the solvent, etc., to form a resin layer on the base film can be cited. In addition, a primer layer may be previously formed on the surface of the base film on which the resin layer is to be formed. As the base film, resin films such as PET can be used. As a material of an undercoat layer, the crosslinked resin etc. of the hydrophilic resin used for a polarizer are mentioned, for example.

Then, after adjusting the amount of solvent such as moisture in the resin layer as required, the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with a dichroic dye such as iodine, so that the dichroic dye is adsorbed and aligned on the resin layer. Next, if necessary, the resin layer on which the dichroic dye has been adsorbed and aligned is treated with a boric acid aqueous solution, and a cleaning step of washing away the boric acid aqueous solution is performed. In this way, the resin layer on which the dichroic dye is adsorbed and aligned, that is, the film of the polarizer is produced. Each step can adopt known methods.

The uniaxial stretching of the base film and the resin layer may be performed before dyeing, may be performed during dyeing, may be performed during boric acid treatment after dyeing, or may be uniaxially stretched in multiple stages of these. The base film and the resin layer can be uniaxially stretched in the MD direction (the direction in which the film is transported). In this case, uniaxial stretching can be performed between rollers having different rotational speeds, or can be uniaxially stretched using heated rollers. In addition, the base film and the resin layer can be uniaxially stretched in the TD direction (transfer direction perpendicular to the film), and in this case, a tenter method can be used. Furthermore, the stretching of the base film and the resin layer may be a dry stretching in which the stretching is performed in the air, or a wet stretching in which the resin layer is stretched in a swollen state with a solvent. In order to exhibit the performance of the polarizer, the stretching ratio is at least 4 times, preferably at least 5 times, and particularly preferably at least 5.5 times. The upper limit of the draw ratio is not particularly limited, but it is preferably 8 times or less from the viewpoint of suppressing cracking and the like.

The polarizer 39 produced by the above method can be obtained by peeling off the base film after laminating the protective layer described later. According to this method, the polarizer can be further thinned.

As a method for producing the polarizer 39 of the cured film in which the polymerizable liquid crystal compound is aligned by aligning the dichroic liquid crystal compound to polymerize the polymerizable liquid crystal compound, for example, a polarizer forming composition containing a polymerizable liquid crystal compound and a dichroic dye is coated on a base film, and the polymerizable liquid crystal compound is polymerized while maintaining a liquid crystal state to be cured to form a polarizer. The polarizer thus obtained is in a state of being laminated on a base film, and can be used as a polarizer with a base film. Alternatively, the polarizer with a base film is used after being laminated on a retardation laminate through an adhesive layer, or after being laminated on an adhesive layer with a release layer, and then peeling off the base film.

As the dichroic dye, a dye having a property in which the absorbance in the long-axis direction and the short-axis direction of the molecule is different, for example, a dye having a maximum absorption wavelength (λmax) in the range of 300 nm to 700 nm is preferable. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, among which azo dyes are preferred. Examples of the azo dyes include monoazo dyes, disazo dyes, trisazo dyes, tetrasazo dyes, and stilbene azo dyes, among which disazo dyes and trisazo dyes are preferred.

The composition for forming a polarizer may contain a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, and the like. The polymerizable liquid crystal compound, dichroic dye, solvent, polymerization initiator, photosensitizer, polymerization inhibitor, etc. contained in the composition for forming a polarizer can use known ones, for example, those exemplified in JP-A-2017-102479 and JP-A-2017-83843 can be used. Furthermore, as the polymerizable liquid crystal compound, the same ones as those exemplified as the polymerizable liquid crystal compound used to obtain the above-mentioned optically anisotropic layer can be used. As a method of forming a polarizer using the composition for forming a polarizer, the methods exemplified in the above publications can be employed.

The thickness of the polarizer 39 can be, for example, more than 2 μm, preferably more than 3 μm. On the other hand, the thickness of the polarizer 39 may be, for example, less than 25 μm, preferably less than 15 μm. In addition, the above-mentioned upper limit and lower limit can be combined arbitrarily. The thinner the polarizer 39 is, the less rigid it is, and the shrinkage stress of the above-mentioned optically anisotropic layer tends to be easily affected.

A protective layer can be laminated on one or both sides of the polarizer 39 through a conventional adhesive layer or adhesive layer. As the protective layer that can be laminated on one or both sides of the polarizer 39, for example, a film made of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, stretchability, etc. can be used. Specific examples of such thermoplastic resins include: cellulose ester resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether resins; polyamide resins; polycarbonate resins; polyamide resins such as nylon and aromatic polyamide; polyimide resins; Polyolefin resins (also called norcamphene-based resins); (meth)acrylic resins; polyarylate resins; polystyrene resins; polyvinyl alcohol resins, and mixtures thereof. When protective layers are laminated on both sides of the polarizer 39 , the resin compositions of the two protective layers may be the same or different. In this specification, "(meth)acrylic acid" means either acrylic acid or methacrylic acid. "(meth)" in (meth)acrylate etc. has the same meaning.

Films made of thermoplastic resins can be surface-treated (such as corona treatment, etc.) in order to improve adhesion to polarizers made of PVA-based resins and dichroic substances, and thin layers such as primer layers (also called primer layers) can also be formed.

The protective layer may be, for example, stretched thermoplastic resin, or may be unstretched (hereinafter referred to as "unstretched resin"). As stretching treatment, uniaxial stretching, biaxial stretching, etc. are mentioned, for example.

The thickness of the protective layer may be, for example, more than 3 μm, preferably more than 5 μm. On the other hand, the thickness of the protective layer may be, for example, less than 50 μm, preferably less than 30 μm. In addition, the above-mentioned upper limit and lower limit can be combined arbitrarily.

The surface of the protective layer opposite to the polarizer may have a surface treatment layer, for example, a hard coat layer, an antireflection layer, an antisticking layer, an antiglare layer, a diffusion layer, and the like. The surface treatment layer may be another layer laminated on the protective layer, or may be formed by performing surface treatment on the surface of the protective layer.

The hard coat layer is formed for the purpose of preventing scratches on the surface of the polarizing plate, and can be formed by attaching a cured film excellent in hardness and sliding properties of ultraviolet curable resins such as acrylic and polysiloxane to the surface of the protective layer. The anti-reflection layer is formed for the purpose of preventing the reflection of external light on the surface of the polarizer, and can be achieved by forming an anti-reflection film or the like according to conventional techniques. Furthermore, the anti-sticking layer is formed for the purpose of preventing adhesion with adjacent layers.

The anti-glare layer is formed by reflecting external light on the surface of the polarizing plate to prevent the view of the penetrating light from the polarizing plate from being hindered. For example, it can be formed by imparting a fine uneven structure on the surface of the protective layer by sandblasting, roughening by embossing, or by mixing transparent fine particles. Examples of transparent fine particles used to provide a fine uneven structure on the surface of the protective layer include conductive inorganic fine particles such as silicon oxide, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and organic fine particles such as cross-linked or non-cross-linked polymers with an average particle diameter of 0.5 μm to 50 μm. The content of the transparent fine particles is generally not less than 2 parts by mass and not more than 50 parts by mass, preferably not less than 5 parts by mass and not more than 25 parts by mass, based on 100 parts by mass of the resin forming the layer forming the fine concavo-convex structure. The anti-glare layer may also serve as a diffusion layer (viewing angle widening function, etc.) that diffuses transmitted light from a polarizing plate to widen the viewing angle.

When the surface treatment layer is another layer laminated on the protective layer of the polarizing plate, the thickness of the surface treatment layer may be, for example, 0.5 μm or more, preferably 1 μm or more. On the other hand, the thickness of the surface treatment layer may be, for example, less than 10 μm, preferably less than 8 μm. When the thickness is within the above range, scratches on the surface of the polarizing plate can be effectively prevented, curing shrinkage can be suppressed, and reverse warping of the polarizing plate tends to be easily suppressed.

The adhesive layer 38 can be made of adhesive. As the adhesive, conventionally known adhesives with good optical transparency can be used without particular limitation, for example, adhesives having matrix polymers such as acrylic, urethane, polysiloxane, polyvinyl ether, etc. can be used. Furthermore, an active energy ray-curable adhesive, a thermosetting adhesive, or the like may be used. Among them, an adhesive having an acrylic resin excellent in transparency, adhesive force, re-peelability, weather resistance, heat resistance, etc. as a matrix polymer is suitable. The adhesive layer is preferably composed of a reaction product of an adhesive composition including a (meth)acrylic resin, a crosslinking agent, and a silane compound.

It is also useful to form an active energy ray-curable adhesive by blending a UV-curable compound such as polyfunctional acrylate into the adhesive composition. After forming an adhesive layer of the active energy ray-curable adhesive, it is also useful to irradiate ultraviolet rays to harden it to form a harder adhesive layer. Active energy ray-curable adhesives have a property of being cured by irradiation with energy rays such as ultraviolet rays and electron beams. The active energy ray-curable adhesive has adhesiveness even before energy ray irradiation, so it can be adhered to adherends such as optical films and liquid crystal layers, and has the property of adjusting the adhesive force by hardening by energy ray irradiation.

The active energy ray-curable adhesive generally contains an acrylic adhesive and an energy ray polymerizable compound as main components. Usually, a cross-linking agent is formulated, and a photopolymerization initiator, a photosensitizer, etc. can be formulated as needed.

The thickness of the adhesive layer 38 may be, for example, not less than 3 μm and not more than 40 μm, preferably not less than 3 μm and not more than 30 μm.

[Flexible image display device]

The flexible image display device is composed of a flexible image display device laminate and an organic EL display panel, and the organic EL display panel is arranged on the viewing side to form a flexible image display device laminate. The so-called flexible means that it can be bent without cracking or breaking. A polarizing plate provided with at least one of a front panel and a touch sensor may be used as a laminate for a flexible image display device. In the case where the polarizing plate has both the front panel and the touch sensor, the lamination sequence can be arbitrary, but it is better to stack the front panel, polarizing plate, and touch sensor sequentially from the viewing side, or to stack the front panel, touch sensor, and polarizing plate sequentially from the viewing side. When the polarizing plate is present on the viewing side of the touch sensor, it is preferable because the pattern of the touch sensor becomes difficult to see and the visibility of the displayed image becomes better. Each component system can be laminated using adhesives, adhesives, etc. Furthermore, it may include a light-shielding pattern formed on at least one surface of any layer of the front panel, polarizing plate, or touch sensor. Each layer (front panel, polarizing plate, touch sensor) forming a laminate for a flexible image display device, and film members (linear polarizing plate, 1/4 wavelength retardation plate, etc.) constituting each layer can be formed with an adhesive. The polarizing plate is a polarizing plate comprising the optical film or retardation laminate of the present invention, preferably a circular polarizing plate. Furthermore, the polarizing plate may be a polarizing plate having a cut surface, or a deformed polarizing plate.

(front panel)

The front panel is preferably a light-permeable plate. The panel may be composed of only one layer, or may be composed of two or more layers. The panel not only has the function of protecting the front surface (screen) of the image display device (window film), but also functions as a touch sensor, a function of blocking blue light, and a function of adjusting the viewing angle. The panel is preferably window film.

(window film)

The window film is arranged, for example, on the viewing side of the flexible image display device described later, and is responsible for protecting other components from external impacts and environmental changes such as temperature and humidity. Conventionally, glass is used as such a protective layer, but the window film of the flexible image display device described later is not as hard as glass, but flexible. Window films consist of a flexible, transparent substrate that includes a hard coat on at least one side.

(transparent substrate)

The visible light transmittance of the transparent substrate is more than 70%, preferably more than 80%. As the transparent substrate, any transparent polymer film can be used. Specifically, polyolefins such as cycloolefin-based derivatives containing monomer units of polyethylene, polypropylene, polymethylpentene, norcamphene, or cycloolefin; (modified) celluloses such as diacetyl cellulose, triacetyl cellulose, and acryl cellulose; acrylics such as methyl methacrylate (co)polymers; polystyrenes such as styrene (co)polymers; acrylonitrile/butadiene/styrene copolymers; Copolymers; polyvinyl chloride; polyvinylidene chloride; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate and other polyesters; polyamides such as nylon; polyimides; polyamideimides; polyetherimides; polyether imides; As a film formed of such a polymer, an unstretched uniaxially or biaxially stretched film can be used. These polymers can be used alone or in combination of two or more. Among the above-mentioned transparent substrates, polyamide films, polyamideimide films or polyimide films, polyester films, olefin films, acrylic films, and cellulose films excellent in transparency and heat resistance are preferable. In the polymer film, it is preferable to disperse inorganic particles such as silicon oxide, organic microparticles, and rubber particles. Furthermore, it may also contain coloring agents such as pigments and dyes, fluorescent whitening agents, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, solvents and other formulations. The thickness of the transparent substrate is not less than 5 μm and not more than 200 μm, preferably not less than 20 μm and not more than 100 μm.

(hard coat)

In the window film, a hard coat layer may be provided on at least one side of the transparent substrate. The thickness of the hard coat layer is not particularly limited, and may be, for example, not less than 2 μm and not more than 100 μm. When the thickness of the hard coat layer is less than 2 μm, it is difficult to ensure sufficient scratch resistance, and when it exceeds 100 μm, the bending resistance is low, and there is a problem that warping due to curing shrinkage occurs.

The hard coat layer is preferably one that can be cured by active energy rays by curing a hard coat composition containing a reactive material that forms a crosslinked structure by irradiation with active energy rays or thermal energy. The so-called active energy line is defined as an energy line that can generate active species by decomposing a compound that produces active species. Examples of active energy rays include visible light, ultraviolet rays, infrared rays, X-rays, α-rays, β-rays, and γ-rays, and electron beams. Ultraviolet rays are especially good. The hard coat composition is at least one polymer containing a radical polymerizable compound and a cation polymerizable compound.

The term "radical polymerizable compound" refers to a compound having a radical polymerizable group. The radical polymerizable group contained in the radical polymerizable compound may be any functional group as long as it can cause a radical polymerization reaction, and includes, for example, a group including a carbon-carbon unsaturated double bond. Specifically, a vinyl group, a (meth)acryloyl group, etc. are mentioned. Furthermore, when the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different. The number of radical polymerizable groups contained in one molecule of the radical polymerizable compound is preferably 2 or more from the viewpoint of increasing the hardness of the hard coat layer. As the radically polymerizable compound, a compound having a (meth)acryl group is preferable from the viewpoint of high reactivity, and a compound called a polyfunctional acrylate monomer having 2 to 6 (meth)acryl groups in one molecule, or an oligomer having several (meth)acryl groups in a molecule called epoxy (meth)acrylate, urethane (meth)acrylate, or polyester (meth)acrylate and having a molecular weight of several hundred to several thousand can be used. It is preferable to contain 1 or more types selected from the group which consists of epoxy (meth)acrylate, an urethane (meth)acrylate, and a polyester (meth)acrylate.

The term "cationically polymerizable compound" refers to a compound having a cationic polymerizable group such as an epoxy group, an oxetanyl group, or a vinyl ether group. The number of cationically polymerizable groups in one molecule of the cationically polymerizable compound is preferably 2 or more, more preferably 3 or more, from the viewpoint of increasing the hardness of the hard coat layer. Furthermore, as the cationically polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferable. Cyclic ether groups such as epoxy groups and oxetanyl groups are preferable from the viewpoint of small shrinkage accompanying polymerization reaction. In addition, among the cyclic ether groups, compounds having epoxy groups are easy to obtain as compounds with various structures, do not adversely affect the durability of the obtained hard coat layer, and have the advantage of being easy to control the compatibility with radically polymerizable compounds. In addition, among the cyclic ether groups, the degree of polymerization of the oxetanyl group is higher than that of the epoxy group, and the toxicity is low, and the speed of network formation from the cationic polymerizable compound of the resulting hard coat layer is accelerated. Even in the region where the radical polymerizable compound is mixed, no unreacted monomer remains in the film, and there are advantages such as forming an independent network.

Examples of cationic polymerizable compounds having an epoxy group include: polyglycidyl ethers of polyols having alicyclic rings or compounds containing cyclohexene rings and cyclopentene rings, cycloaliphatic epoxy resins obtained by epoxidation with suitable oxidants such as hydrogen peroxide and peracids; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, and homopolymers and copolymers of glycidyl (meth)acrylate; bisphenol A, bisphenol F. Glycidyl ethers produced by the reaction of bisphenols such as hydrogenated bisphenol A or derivatives such as alkylene oxide adducts and caprolactone adducts with epichlorohydrin, and glycidyl ether-type epoxy resins derived from bisphenols such as novolac epoxy resins, etc.

The hard coat composition may further include a polymerization initiator. As the polymerization initiator, there are radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and the like, which can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations to perform radical polymerization and cationic polymerization.

The radical polymerization initiator should just be a substance which emits and initiates radical polymerization by at least any one of active energy ray irradiation and heating. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and perbenzoic acid, azo compounds, such as azobisisobutyronitrile, etc. are mentioned, for example.

As active energy ray radical polymerization initiators, there are Type 1 radical polymerization initiators that generate radicals by molecular decomposition and Type 2 radical polymerization initiators that generate radicals through hydrogen extraction reactions in the presence of tertiary amines. They can be used alone or in combination.

The cationic polymerization initiator should just be a substance which releases and initiates cationic polymerization by at least any one of active energy ray irradiation and heating. As the cationic polymerization initiator, aromatic iodonium salts, aromatic permeic acid salts, cyclopentadienyl iron (II) complexes, and the like can be used. These may vary depending on the structure, and either one or both of active energy ray irradiation and heating can initiate cationic polymerization.

The polymerization initiator may be contained in an amount of 0.1 to 10% by weight relative to 100% by weight of the entire hard coat composition. When the content of the polymerization initiator is less than 0.1% by weight, sufficient hardening cannot be achieved, and the mechanical properties and adhesion of the final coating film are difficult to achieve. When it exceeds 10% by weight, poor adhesion, cracking, and warping due to hardening shrinkage may occur.

The hard coat composition may further contain one or more selected from the group consisting of solvents and additives. Since the solvent can dissolve or disperse the polymerizable compound and the polymerization initiator, solvents known as hard coat compositions in this technical field can be used without particular limitation. The additive system may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, etc.

(circular polarizer)

A circular polarizer is a functional layer that only transmits right or left circularly polarized light components by laminating a 1/4 wavelength retardation layer (hereinafter also referred to as a λ/4 retardation layer) on a linear polarizer. For example, the external light is converted into right circularly polarized light, reflected by the organic EL panel, and the left circularly polarized external light is blocked, and only the light-emitting component of the organic EL is transmitted, suppressing the influence of reflected light, and making it easier to see images. In order to achieve the circular polarization function, the absorption axis of the linear polarizer or the linear polarizer and the slow axis of the λ/4 retardation layer should be 45° in theory, but 45±10° in practice. The linear polarizer or the linear polarizer and the λ/4 retardation layer do not have to be laminated adjacent to each other, as long as the relationship between the absorption axis and the slow axis satisfies the aforementioned range. It is desirable to achieve complete circular polarization at all wavelengths, but it is not necessarily necessary in practice. The circular polarizing plate of the present invention also includes an elliptically polarizing plate. On the viewing side of the linear polarizer or linear polarizing plate, a λ/4 retardation film can be laminated, and the output light is circularly polarized, which improves the visibility when wearing polarized sunglasses.

The linear polarizer is a functional layer that has the function of blocking the polarized light of the vibration component perpendicular to the light vibrating in the direction of the transmission axis. The linear polarizer may include a single linear polarizer, or a linear polarizer and a protective film attached to at least one side thereof. The thickness of the linear polarizer may be less than 200 μm, preferably not less than 0.5 μm and not more than 100 μm. When the thickness exceeds 200 μm, the flexibility is low.

The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA) film. In the PVA-based film aligned by stretching, a dichroic dye such as iodine is adsorbed or stretched in a state of being adsorbed on PVA to align the dichroic dye and exhibit a polarizing function. In the manufacture of film-type polarizers, there may be other steps such as swelling, cross-linking by boric acid, cleaning by aqueous solution, and drying. The steps of stretching and dyeing can be performed alone with a PVA-based film, or in a state of being laminated with another polyethylene terephthalate film. The PVA-based film used is preferably 10 μm or more and 100 μm or less, and the draw ratio is preferably 2 to 10 times.

Furthermore, as another example of the linear polarizer, a liquid crystal coating type polarizer formed by coating a liquid crystal polarizing composition may be used. The liquid crystal polarizer composition may include a liquid crystal compound and a dichroic pigment compound. As the liquid crystal compound, any liquid crystal compound may be used as long as it has the property of displaying a liquid crystal state. In particular, it is preferable to have a high-order alignment state with equal smectic properties and exhibit high polarizing performance. Furthermore, those having a polymerizable functional group are also preferable. The dichroic dye compound is a dye that is aligned with a liquid crystal compound to exhibit dichroism, and the dichroic dye itself may have liquid crystallinity or may have a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group. The liquid crystal polarizer composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal polarizing layer can be manufactured by coating a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer. The thickness of the liquid crystal polarizer can be formed thinner than that of the film polarizer. The thickness of the liquid crystal polarizing layer is not less than 0.5 μm and not more than 10 μm, preferably not less than 1 μm and not more than 5 μm.

The alignment film is manufactured by, for example, coating an alignment film-forming composition on a substrate, and imparting alignment by brushing, polarized light irradiation, or the like. In addition to the alignment agent, the composition for forming an alignment film may further include a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the alignment agent, for example, polyvinyl alcohols, polyacrylates, polyamide acids, and polyimides can be used. In the case of photo-alignment, it is better to use an alignment agent containing cinnamate groups. The polymer used as the alignment agent has a weight average molecular weight of about 10,000 to 1,000,000. The alignment film is preferably not less than 5nm and not more than 10000nm, especially when it is not less than 10nm and not more than 500nm, because it can exhibit sufficient alignment control force. The liquid crystal polarizing layer can also be peeled off from the substrate, transferred and laminated, or directly laminated on the substrate. The substrate also preferably functions as a transparent substrate for a protective film, retardation plate, or window film.

As the protective film, as long as it is a transparent polymer film, materials and additives used for transparent substrates can be used. Preferable are cellulose-based films, olefin-based films, acrylic films, and polyester-based films. It may also be a coating-type protective film obtained by applying a cation-curing composition such as epoxy resin or a radical-curing composition such as acrylate and curing it. If necessary, plasticizers, ultraviolet absorbers, infrared absorbers, coloring agents such as pigments or dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. may be included. The thickness of the protective film may be 200 μm or less, preferably 1 μm or more and 100 μm or less. When the thickness exceeds 200 μm, the flexibility is low. It can also function as a transparent base material for window films.

The λ/4 retardation layer may be the optical film of the present invention, or may be a film that imparts a λ/4 retardation in a direction (in-plane direction of the film) perpendicular to the traveling direction of incident light. The film imparting a retardation of λ/4 can be a stretched retardation plate produced by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. As required, phase difference adjusters, ultraviolet absorbers, infrared absorbers, coloring agents such as pigments or dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. may be included. The thickness of the stretched phase difference plate may be less than 200 μm, preferably not less than 1 μm and not more than 100 μm. When the thickness exceeds 200 μm, the flexibility is low. The λ/4 retardation layer is preferably the optical film of the present invention from the viewpoint of workability and flexibility.

Furthermore, as another example of the λ/4 retardation layer, a liquid crystal coating type retardation plate formed by coating a liquid crystal composition may be used. The liquid crystal composition contains a liquid crystal compound having a property of exhibiting a liquid crystal state such as a nematic type, a cholesteric type, and a smectic type. Any compound including a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. Liquid crystal coated phase difference plate can further contain initiator, solvent, dispersant, leveling agent, stabilizer, surfactant, crosslinking agent, silane coupling agent, etc. The liquid crystal coating type retardation plate can be produced by applying a liquid crystal composition on an alignment film and curing it to form a liquid crystal retardation layer, as in the description of the liquid crystal polarizing layer. The liquid crystal coating type retardation plate can be formed thinner than the stretched type retardation plate. The thickness of the liquid crystal polarizing layer is not less than 0.5 μm and not more than 10 μm, preferably not less than 1 μm and not more than 5 μm. The liquid crystal coating type retardation plate can be laminated by peeling from the base material, transferring it, or directly laminating the base material. The base material is also preferably a transparent base material having a protective film, a phase difference plate, and a window film.

Generally, the shorter the wavelength, the larger the birefringence, and the longer the wavelength, the smaller the birefringence. In this case, since the retardation of λ/4 cannot be achieved in the entire visible light region, the in-plane retardation of λ/4 is usually designed to be 100nm to 180nm, preferably 130nm to 150nm, near 560nm, which has high visual sensitivity. The use of an anti-dispersion λ/4 retardation layer of a material having a birefringence wavelength dispersion characteristic opposite to that of general ones is preferable because visibility is good. As such a material, it is preferable to use those described in JP-A-2007-232873 and the like in the case of stretched retardation plates, and those described in JP-A-2010-30979 and the like in the case of liquid crystal coating-type retardation plates.

Furthermore, as another method, a technique of obtaining a broadband λ/4 retardation layer in combination with a 1/2 wavelength retardation layer (hereinafter also referred to as a λ/2 retardation layer) is known (Japanese Patent Application Laid-Open No. 10-90521). The λ/2 retardation layer may be the optical film of the present invention, or may be manufactured using the same material and method as the λ/4 retardation layer. Any combination of a stretched phase difference plate and a liquid crystal coating type phase difference plate may be used, and the use of a liquid crystal coating type phase difference plate is preferable because the thickness of the film can be reduced. The λ/2 retardation layer is preferably the optical film of the present invention from the viewpoint of workability and flexibility.

In order to improve the visibility of a circular polarizing plate in an oblique direction, a method of laminating a positive C plate is known (Japanese Patent Laid-Open No. 2014-224837). The positive C plate can be the optical film of the present invention, or it can be a liquid crystal coating type retardation plate or a stretched retardation plate. The retardation in the thickness direction may be, for example, not less than -200 nm and not more than 20 nm, preferably not less than -140 nm and not more than 40 nm. The positive C plate is preferably the optical film of the present invention from the viewpoint of workability and bendability of a polarizing plate. The positive C plate can also be used in combination with the λ/4 retardation layer as a retardation laminate.

(touch sensor)

A touch sensor is used as an input means. Various methods such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitive method have been proposed as touch sensors, and any method may be used. Among them, the capacitive method is preferable. The capacitive touch sensor is divided into an active area and an inactive area located around the active area. The active area is an area of the display panel corresponding to an area where a screen is displayed (display section), and is an area for sensing a user's touch, and the inactive area is an area corresponding to an area where no screen is displayed (non-display section) in the image display device. The touch sensor may include: a flexible substrate; sensing patterns formed on the active area of the substrate; sensing lines formed on the inactive area of the substrate and connected to external driving circuits through the sensing patterns and pads. As the substrate having flexible properties, the same materials as the transparent substrate of the above-mentioned window film can be used. The toughness of the substrate of the touch sensor is more than 2,000 MPa%, which is preferable from the point of view of suppressing cracking of the touch sensor. More preferably, the toughness can be more than 2,000MPa% and less than 30,000MPa%.

The sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in directions different from each other. The first pattern and the second pattern can be formed on the same layer, and in order to sense the touched point, the patterns must be electrically connected. The first pattern has a structure in which unit patterns are connected to each other through a tab, and the second pattern has a structure in which unit patterns are separated from each other in an island form, and another bridge electrode is required to electrically connect the second patterns. Known transparent electrode materials can be applied to the sensing pattern. For example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), cadmium tin oxide (CTO), PEDOT (poly(3,4-ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, etc., can be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, tellurium, and chromium. These can be used individually or in mixture of 2 or more types.

The bridge electrode can be formed on the upper part of the insulating layer through the insulating layer on the upper part of the sensing pattern, and the bridge electrode is formed on the substrate, and the insulating layer and the sensing pattern can be formed thereon. The bridge electrode system can be formed of the same material as the sensing pattern, and can be formed of metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more thereof. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrodes. The insulating layer may be formed only between the contact and the bridge electrodes of the first pattern, or may be formed in a layer covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern through a contact hole formed in the insulating layer. The touch sensor may further include an optical adjustment layer between the substrate and the electrodes. Due to the difference in transmittance between the patterned area and the non-patterned area, more specifically, due to the difference in light transmittance caused by the difference in refractive index in these areas, the optical adjustment layer may include an inorganic insulating material or an organic insulating material as a suitable compensation means. The optical adjustment layer can be formed by coating a photocurable composition including a photocurable organic binder and a solvent on the substrate. The photocurable composition may further include inorganic particles. With the inorganic particles, the refractive index of the optical adjustment layer can be increased.

The photocurable organic binder system may contain, for example, copolymers of monomers such as acrylate-based monomers, styrene-based monomers, and carboxylic acid-based monomers. The photocurable organic binder may be, for example, a copolymer of repeating units different from each other, such as epoxy group-containing repeating units, acrylate repeating units, and carboxylic acid repeating units. The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing assistant.

(next layer)

Each layer (window film, circular polarizer, touch sensor) and film components (linear polarizer, λ/4 phase difference plate, etc.) constituting each layer can be formed by adhesives. As the adhesive system, water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curing adhesives, heat-curing adhesives, anaerobic-curing adhesives, active energy ray-curing adhesives, hardener-mixed adhesives, hot-melt adhesives, pressure-sensitive adhesives (adhesives), and remoistening adhesives are widely used. Among them, water-based solvent-volatile adhesives, active energy ray-curable adhesives, and adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted according to the required adhesive force, etc., and it can be from 0.01 μm to 500 μm, preferably from 0.1 μm to 300 μm. In the case of multiple adhesive layers, each thickness can be the same or different.

As the water-based solvent-volatile adhesive, water-dispersed polymers such as polyvinyl alcohol-based polymers, water-soluble polymers such as starch, and ethylene-vinyl acetate-based emulsions and styrene-butadiene-based emulsions can be used as main polymers. In addition to water and main polymers, crosslinking agents, silane compounds, ionic compounds, crosslinking catalysts, antioxidants, dyes, pigments, inorganic fillers, organic solvents, etc. can be formulated. In the case of bonding with a water-based solvent-volatile adhesive, the water-based solvent-volatile adhesive is injected between the layers to be bonded, and the layers to be bonded are bonded and then dried to impart adhesiveness. When using a water-based solvent-volatile adhesive, the thickness of the adhesive layer is not less than 0.01 μm and not more than 10 μm, preferably not less than 0.1 μm and not more than 1 μm. In the case of using a plurality of layers of the water-based solvent-volatile adhesive, the thickness of each layer may be the same or different.

The active energy ray-curable adhesive can be formed by curing an active energy ray-curable composition including a reactive material that forms an adhesive layer by irradiating active energy rays. The active energy ray-curable composition may contain at least one polymer of the same radical polymerizable compound and cation polymerizable compound as the hard coat composition. The radically polymerizable compound is the same as the hard coat composition, and the same type as the hard coat composition can be used. The radically polymerizable compound used as the adhesive is preferably a compound having an acryl group. In order to reduce the viscosity of the adhesive composition, a compound containing a monofunctional group is preferable.

The cationically polymerizable compound is the same as the hard coat composition, and the same type as the hard coat composition can be used. Epoxy compounds are particularly preferred as the cationic polymerizable compound used in the active energy ray-curable adhesive. In order to reduce the viscosity of the adhesive composition, it is preferable to use a compound containing a monofunctional group as a reactive diluent.

The active energy ray curing composition may further contain a polymerization initiator. As the polymerization initiator, there are radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and the like, which can be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cations to perform radical polymerization and cationic polymerization. In describing the hard coat composition, an initiator that initiates at least one of radical polymerization and cationic polymerization by irradiation with active energy rays can be used.

The active energy ray hardening composition may further include ion trapping agent, antioxidant, chain transfer agent, tackifier, thermoplastic resin, filler, flow viscosity regulator, plasticizer, defoamer, additive, and solvent. In the case of bonding with an active energy ray-curable adhesive, one or both of the adhered layers is coated with an active energy ray-curable composition and bonded, and either or both of the adhered layers are irradiated with active energy rays to be cured and bonded. When using an active energy ray-curable adhesive, the thickness of the adhesive layer is not less than 0.01 μm and not more than 20 μm, preferably not less than 0.1 μm and not more than 10 μm. In the case of using a plurality of layers of active energy ray-curable adhesive, the thickness of each layer may be the same or different.

Adhesives can be classified into acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, etc. depending on the main polymer. For adhesives, in addition to the main polymer, cross-linking agents, silane compounds, ionic compounds, cross-linking catalysts, antioxidants, tackifiers, plasticizers, dyes, pigments, inorganic fillers, etc. can be formulated. The components constituting the adhesive are dissolved/dispersed in a solvent to obtain an adhesive composition, and the adhesive composition is coated on a substrate and dried to form an adhesive layer. The adhesive layer can be formed directly, or it can be transferred to other substrates. In order to cover the adhesive surface before bonding, it is also good to use a release film. When using an active energy ray-curable adhesive, the thickness of the adhesive layer is from 0.1 μm to 500 μm, preferably from 1 μm to 300 μm. In the case of using a plurality of layers of the adhesive, the thickness of each layer may be the same or different.

(shading pattern)

The light-shielding pattern can be used as at least a part of the frame or shell of the flexible image display device. The light-shielding pattern can hide the wiring arranged on the edge of the flexible image display device from being seen, thereby improving the visibility of the image. The light-shielding pattern may be in the form of a single layer or a plurality of layers. The color of the light-shielding pattern is not particularly limited, and there are various colors such as black, white, and metallic. The light-shielding pattern can be formed by pigments, acrylic resins, ester resins, epoxy resins, polyurethanes, polysiloxanes and other polymers for expressing colors. These can be used individually or in mixture of 2 types. The light-shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light-shielding pattern may be not less than 1 μm and not more than 100 μm, preferably not less than 2 μm and not more than 50 μm. In addition, it is preferable that the thickness direction of the light pattern is in a shape such as an inclination.

FIG. 4 is a schematic cross-sectional view of one form of the flexible image display device. The circular polarizer 100 shown in FIG. 4 includes a panel 101 , a circular polarizer 102 , a touch sensor 103 , and an organic EL display panel 104 in sequence.

[Example]

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. "%" and "parts" in the examples refer to mass % and mass parts unless otherwise specified. Various measurements and evaluations were performed as follows.

[Number of Defects in Optically Anisotropic Layer]

<Confirmation of defects>

The obtained optical film was cut into 50 mm x 50 mm, and the actual size and number of the alignment defects on the screen were confirmed using an optical microscope (ECLIPSE ME600, manufactured by Nikon Corporation). For observation, a linear polarizer is inserted under the stage of the optical microscope. Then, the direction of the slow axis of the obtained optical film coincided with the direction of the absorption axis of the linear polarizer inserted into the lower part of the stage. Furthermore, when the polarizer of the optical microscope is rotated, it becomes a crossed Nicol state, and the region that becomes a bright spot is an alignment defect. When the region was observed with the depolarized state removed, the size of the region confirmed to be a defect was measured as the length of the largest portion, and it was taken as the actual size of the alignment defect. As a result of observation, all the defects were crystals induced by the polymerizable liquid crystal compound. The results are shown in Table 2. In addition, the defect actual size shown in Table 2 is the average value of the measured actual size. The actual size of the cut optical film is more than 6 defects/mm ² . In either embodiment, the actual size of the alignment defect is 20 μm or less.

<ECLIPSE observation setting>

Illumination of lamp: fully open

Aperture under the stage: 0.5

Exposure time: 200ms

GAIN: 2.00

AWB: not set

[Defect rate of optically anisotropic layer]

After measuring the number of the above-mentioned defects, capture a field of view image (including the defect part) of the optical microscope in the crossed Nicol state on the personal computer, divide the brightest part and the darkest part into 256 levels, use the image processing software attached to the personal computer, and binarize the captured image with a threshold of 127 to obtain the area of the alignment defect and calculate the defect rate. The results are shown in Table 2.

[Measurement of puncture strength]

、0.5R)針的KATO TECH公司製的便攜式壓縮試驗機「KES-G5針穿透力試驗規範」，溫度23±3℃的環境下，穿刺速度0.0033cm/秒的測定條件下進行。穿刺試驗所測定的穿刺強度，係對3個試驗片進行穿刺試驗而獲得的平均值。結果呈示於表2。 For the puncture test, it is equipped with a ball at the front end (diameter of the front end is 1mm)

, 0.5R) needles of KATO TECH's portable compression testing machine "KES-G5 Needle Penetration Test Specification", the temperature is 23±3°C, and the puncture speed is 0.0033cm/second. The puncture strength measured by the puncture test is an average value obtained by performing the puncture test on three test pieces. The results are shown in Table 2.

[Measurement of tensile stress]

The tensile test was carried out using a precision universal testing machine "Autograph AG-IS" manufactured by Shimadzu Corporation, under the conditions of a temperature of 23±3° C. and a tensile speed of 1 mm/min. The size of the optical film used for the evaluation was 10×10 mm. Tensile tests were implemented for the slow axis direction of the optical film or the direction perpendicular to the slow axis direction (that is, the fast axis direction). The tensile stress measured by the tensile test is an average value obtained by performing a tensile test on three test pieces. The results are shown in Table 2.

[Liquid crystal composition solution]

A polymerizable liquid crystal compound (A-1) (molecular weight: 1156), a polymerizable liquid crystal compound (B-1) (molecular weight: 664), and a polymerizable liquid crystal compound (C-1) (molecular weight: 1083) represented by the following formula were prepared.

Polymerizable liquid crystal compound (A-1):

Polymeric liquid crystal compound (B-1):

Polymeric liquid crystal compound (C-1):

The polymerizable liquid crystal compound (A-1) was synthesized by the method described in JP-A-2011-207765.

The polymerizable liquid crystal compound (B-1) was synthesized by the method described in JP-A-2010-24438.

The polymerizable liquid crystal compound (C-1) was synthesized by the method described in JP-A-2010-24438.

83 parts by mass of the polymerizable liquid crystal compound (A-1), 3 parts by mass of the polymerizable liquid crystal compound (B-1), and 14 parts by mass of the polymerizable liquid crystal compound (C-1) were mixed to obtain a liquid crystal mixture (1) (100 parts by mass in total).

Referring to the patent document (Japanese Patent Laid-Open No. 2017-179367), according to the composition described in Table 1, the liquid crystal mixture (1), polymerization initiator, leveling agent, polymerization inhibitor and solvent were fed in to prepare the liquid crystal composition solution (1). In addition, the quantity of the polymerization initiator shown in Table 1, a leveling agent, and a polymerization inhibitor is the feeding quantity with respect to 100 mass parts of liquid crystal mixtures (1). In addition, the compounding amount of the solvent is the mass % of the liquid crystal mixture (1), and is set to 10 mass % with respect to the entire amount of the liquid crystal composition solution [100 mass parts of the liquid crystal composition solution (1) is added with a solvent so as to contain the liquid crystal mixture (1) 100 mass parts].

Polymerization initiator: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by BASF Japan)

Leveling agent: polyacrylate compound (BYK-361N; manufactured by BYK-Chemie Japan Co., Ltd.)

Polymerization inhibitor: BHT (manufactured by Wako Pure Chemical Industries, Ltd.)

Solvent: N-methylpyrrolidone (NMP; manufactured by Kanto Chemical Co., Ltd.)

[Composition for forming a photoalignment film]

The following components were mixed, and the resulting mixture was stirred at 80° C. for 1 hour to obtain a photoalignment film-forming composition (1). The photo-alignment material represented by the following formula was synthesized by the method described in JP-A-2013-33248.

Photoalignment material (5 parts):

Solvent (95 parts): cyclopentanone

[Example 1]

An optical film was produced as follows. Cyclic olefin polymer film (COP) (ZF-14, manufactured by Japan Zeon Co., Ltd., thickness 23 μm, heat capacity per 1 cm ² of substrate: 0.004 J/cm ² ‧°C) was treated once using a corona treatment device (AGF-B10, manufactured by Kasuga Electric Co., Ltd.) with an output of 0.3 kW and a processing speed of 3 m/min. On the corona-treated surface, the aforementioned photoalignment film-forming composition (1) was coated with a bar coater, dried at 80° C. for 1 minute, and polarized UV exposure was performed at a cumulative light intensity of 100 mJ/cm ² using a polarized UV irradiation device (SPOT CURE SP-7; manufactured by USHIO Electric Co., Ltd.). The thickness of the obtained alignment film was 100 nm when measured with a laser microscope (LEXT, manufactured by Olympus Corporation).

接著，室溫25℃、濕度30%RH下，將調製的液晶組成物溶液(1)通過孔徑0.2μm的PTFE製膜過濾器(Advantech Toyo股份有限公司製、商品編號：T300A025A)，使用棒塗器，塗佈所得之液晶組成物溶液(1)於25℃下保溫的附配向膜的基材上，120℃下乾燥1分鐘後，使用高壓汞燈(Unicure VB-15201BY-A、USHIO電機股份有限公司製)，照射紫外線(氮氣環境下、波長：365nm、波長365nm的累積光量：1000mJ/cm ² )，製作光學膜。 The thickness of the obtained coating film was 2 μm when measured with a laser microscope (LEXT, manufactured by Olympus Corporation).

[Example 2]

An optical film was produced in the same manner as in Example 1, except that the base material with an alignment film was coated while keeping the temperature at 40°C.

[Example 3]

An optical film was produced in the same manner as in Example 1, except that the substrate with an alignment film was heated at 80° C. for 10 seconds before coating, and then coated.

[Example 4]

An optical film was produced in the same manner as in Example 1 except that the composition ratio of the polymerizable liquid crystal compound was 82 parts by mass (A-1), 4 parts by mass (B-1), and 14 parts by mass (C-1).

[Example 5]

An optical film was produced in the same manner as in Example 1 except that the composition ratio of the polymerizable liquid crystal compound was 77 parts by mass, (B-1) 9 parts by mass, and (C-1) 14 parts by mass.

[Example 6]

The non-coated surface of the COP (the surface not coated with the liquid crystal composition solution) was produced, and a 0.3 mm-thick soda glass was bonded with an adhesive as a substrate. The base material has a heat capacity per 1 cm ² of 0.05J/cm ² ‧℃. Except having used this base material, it carried out similarly to Example 1, and produced the optical film.

[Comparative example 1]

Except having set the humidity at the time of coating to 65%RH, it carried out similarly to Example 1, and produced the optical film.

[Comparative example 2]

An optical film was produced in the same manner as in Example 1 except that the composition ratio of the polymerizable liquid crystal compound was 99 parts by mass (A-1), 1 part by mass (B-1), and 0 parts by mass (C-1).

[Comparative example 3]

An optical film was produced in the same manner as in Example 1 except that the composition ratio of the polymerizable liquid crystal compound was 92 parts by mass (A-1), 3 parts by mass (B-1), and 5 parts by mass (C-1).

[Comparative example 4]

The non-coated surface of the COP is made of soda glass with a thickness of 10mm, which is used as the base material. The base material has a heat capacity per 1 cm ² of 1.68J/cm ² ‧℃. Except having used this base material, it carried out similarly to Example 1, and produced the optical film.

[Table 2]

[retardation laminate]

<Manufacturing of the first retardation layer>

The optical films produced in Examples 1, 4, and 5 and Comparative Examples 2 and 3 were used as the first retardation layer.

<Manufacturing of the second retardation layer>

A PET base material with a thickness of 38 μm was used as a transparent base material, and the vertical alignment layer composition was coated on one side thereof so as to have a film thickness of 3 μm, and an alignment layer was prepared by irradiating ultraviolet rays. Furthermore, as the composition for the vertical alignment layer, a mixture of 2-phenoxyethyl acrylate, tetrahydrofuryl methyl acrylate, diperythritol triacrylate, and bis(2-vinyloxyethyl)ether was mixed at a ratio of 1:1:4:5, and LUCIRIN TPO was added as a polymerization initiator at a ratio of 4%.

Next, on the formed alignment layer, a liquid crystal composition containing a photopolymerizable nematic liquid crystal (manufactured by Merck, RMM28B) was applied on the alignment layer with a die coater. Here, in the liquid crystal composition, the solvent is a mixed solvent in which methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) with a boiling point of 155° C. are mixed at a mass ratio (MEK:MIBK:CHN) of 35:30:35. Then, the prepared liquid crystal composition with a solid content of 1 to 1.5 g is coated on the alignment layer, so that the coating amount is 4 to 5 g (wet).

Then, after coating the liquid crystal composition on the alignment layer, drying treatment was performed at a drying temperature of 75° C. and a drying time of 120 seconds. Next, by irradiating ultraviolet rays (UV) to polymerize, a positive C layer composed of a photopolymerizable nematic liquid crystal hardened layer, an alignment layer, and a transparent substrate is obtained. The total thickness of the photopolymerizable nematic liquid crystal cured layer and the alignment layer was 4 μm.

<Manufacturing of retardation laminate>

The first retardation layer and the second retardation layer are bonded together with an ultraviolet curable adhesive so that each retardation layer (the surface opposite to the transparent substrate) becomes the bonded surface. Then, ultraviolet rays are irradiated to harden the ultraviolet curable adhesive. In this manner, a retardation laminate (1) of two retardation layers including a first retardation layer and a second retardation layer was produced.

[Polarizer]

The polyvinyl alcohol film with an average degree of polymerization of about 2400, a saponification degree of more than 99.9 mole%, and a thickness of 30 μm is immersed in pure water at 30°C, and then immersed in an aqueous solution with a mass ratio of iodine:potassium iodide:water of 0.02:2:100 at 30°C for iodine dyeing (hereinafter also referred to as iodine dyeing step). The polyvinyl alcohol film after the iodine dyeing step was immersed in an aqueous solution with a mass ratio of potassium iodide:boric acid:water of 12:5:100 at 56.5°C for boric acid treatment (hereinafter also referred to as boric acid treatment step). The polyvinyl alcohol film subjected to the boric acid treatment step was washed with pure water at 8° C. and dried at 65° C. to obtain a polarizer (thickness after stretching: 12 μm) in which polyvinyl alcohol was adsorbed and aligned with iodine. At this time, stretching is performed in the iodine staining step and the boric acid treatment step. The overall stretching ratio of such stretching was 5.3 times.

A saponified triacetylcellulose film (KC4UYTAC 40 μm, manufactured by Konica Minolta Co., Ltd.) was attached to both sides of the obtained polarizer with a nip roller through a water-based adhesive. The obtained bonded product was dried at 60° C. for 2 minutes while maintaining a tension of 430 N/m to obtain a polarizer ( 1 ) having triacetylcellulose films as protective films on both sides. In addition, the aforementioned water-based adhesive was prepared by adding 3 parts of carboxy-modified polyvinyl alcohol (KURARAY POVAL KL318 manufactured by KURARAY Co., Ltd.) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650, 30% solid content concentration, aqueous solution manufactured by Taoka Chemical Industry Co., Ltd.) to 100 parts of water.

The optical properties of the obtained polarizer (1) were measured using a spectrophotometer (V7100, manufactured by JASCO Corporation). The resulting light sensitivity-corrected single transmittance was 42.1%, the light sensitivity-corrected polarization degree was 99.996%, the single hue a* was -1.1, and the single hue b* was 3.7.

[polarizer]

Adhesive B as the first adhesive layer was transferred to one side of the polarizer (1), the separator film was peeled off, and laminated on the side of the retardation laminate (1) where the transparent substrate on the first retardation layer side was peeled off. On the surface of the retardation laminate (1) opposite to the surface on which the polarizer is laminated, the adhesive F as the second adhesive layer is laminated. In this way, a polarizing plate sequentially comprising a protective film, a polarizer, a protective film, a first adhesive layer, a first retardation layer, an adhesive layer, a second retardation layer, and a second adhesive layer is produced.

[Evaluation method of workability of polarizing plate]

When the obtained polarizing plate is cut into 100mm×100mm with a super cutting machine, the cut end face is observed with an optical microscope. If more than 3 cracks are seen in the retardation laminate, it is marked as ×, if 1 or 2 cracks are seen, it is marked as ○, and if no cracks are seen, it is marked as ◎. The crack lengths of the retardation laminates produced at this time were all 300 μm to 400 μm, and there was no difference in length.

[table 3]

[Polarizing plate with agglomerated polyimide film]

The separation film of the 2nd adhesive layer of the obtained polarizing plate was peeled off, and it laminated|stacked on the polyimide film (Ube Industries, Ltd., Upilex S type 75S) of thickness 75 micrometers. In this way, a polarizing plate of an agglomerated polyimide film comprising a protective film, a polarizer, a protective film, a first adhesive layer, a first retardation layer, an adhesive layer, a second retardation layer and a second adhesive layer, and a polyimide film is produced in sequence.

[Evaluation method of bending resistance of polarizing plate agglomerated with polyimide film]

When the obtained polarizing plate with agglomerated polyimide film was cut into 100 mm x 10 mm with a super cutter, and when the polyimide film was bent to 0.5 R so that the polyimide film protruded, the retardation laminate was marked with 5 or more cracks, ○ with 1 to 4 cracks, and ◎ with no cracks. The length of cracks generated in Example 1 was 250 μm, and the length of cracks generated in Comparative Example 3 was 220 μm to 250 μm. There was no difference in the length of cracks between Example 1 and Comparative Example 3.

[Table 4]

10‧‧‧optical film

11‧‧‧Optical anisotropic layer

12‧‧‧Alignment layer

13‧‧‧Substrate layer

Claims (12)

An optical film, which has an optically anisotropic layer composed of a polymer formed by polymerizing two or more polymerizable liquid crystal compounds having one or more polymerizable functional groups and a molecular weight of 500 or more in an aligned state; the number of alignment defects with an actual size of 0.3 μm to 50 μm per ¹ mm of the aforementioned optically anisotropic layer satisfies the following formula (1): 0≦Number of alignment defects [pieces]≦14 (1). An optical film, which has an optically anisotropic layer composed of a polymer, the polymer is formed by polymerizing two or more polymerizable liquid crystal compounds having one or more polymerizable functional groups and a molecular weight of 500 or more in an aligned state; the defect rate defined by the following formula (2) in the aforementioned optically anisotropic layer satisfies the following formula (3);

In the formula, the total defect area is the sum of the areas of alignment defects whose actual size is 0.3 μm to 50 μm observed in one field of view of the optical microscope, and the field of view of the microscope observation is the area of the optically anisotropic layer when the optical anisotropic layer exists in the entire field of view of the optical microscope; 0≦defect rate [ppm]≦1000 (3). An optical film, which has an optically anisotropic layer made of a polymer, the polymer is formed by polymerizing two or more polymerizable liquid crystal compounds having more than one polymerizable functional group and a molecular weight of more than 500 in an aligned state; the number of alignment defects whose actual size is not less than 0.3 μm and not more than 50 μm per ¹ mm of the aforementioned optically anisotropic layer satisfies the following formula (1), and the defect rate defined by the following formula (2) satisfies the following formula (3); ≦Number of alignment defects [pieces]≦14 (1);

In the formula, the total defect area is the sum of the areas of alignment defects whose actual size is 0.3 μm to 50 μm observed in one field of view of the optical microscope, and the field of view of the microscope is the area of the optically anisotropic layer when the optically anisotropic layer exists in the entire field of view of the optical microscope; 0≦defect rate [ppm]≦1000 (3). The optical film according to any one of claims 1 to 3, wherein the polymerizable functional group is an acryloxy group. The optical film according to any one of claims 1 to 3, wherein the aforementioned alignment defects include defects caused by microcrystals of polymerizable liquid crystal compounds. The optical film according to any one of claims 1 to 3, wherein the thickness of the optically anisotropic layer is not less than 0.05 μm and not more than 10 μm. A retardation laminate comprising more than one optical film as described in any one of the first to sixth claims of the patent application. A polarizing plate comprising the retardation laminate as described in item 7 of the patent application. The polarizing plate as described in claim 8 of the claims, which has a cut surface. The polarizing plate described in item 8 of the scope of the patent application is a deformed polarizing plate. The polarizing plate as described in claim 8 of the patent application, which is provided with at least one of a panel or a touch sensor. A flexible image display device, which is equipped with a polarizing plate as described in any one of the eighth to eleventh items in the scope of the patent application.

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