CN112771422A

CN112771422A - Film for transfer of liquid crystal compound alignment layer

Info

Publication number: CN112771422A
Application number: CN201980064152.9A
Authority: CN
Inventors: 佐佐木靖; 村田浩一
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-10-26
Filing date: 2019-10-21
Publication date: 2021-05-07
Anticipated expiration: 2039-10-21
Also published as: JP7539038B2; CN112789531A; JPWO2020085310A1; JP7539036B2; KR20210082159A; CN112771423B; WO2020085310A1; CN112789531B; CN112805136A; JPWO2020085308A1; TW202033632A; JPWO2020085307A1; KR20210082163A; WO2020085309A1; JP7539037B2; TWI824046B; CN116804778A; JPWO2020085309A1; KR20210079272A; CN112771423A

Abstract

Providing: a cellulose transfer film for transferring an alignment layer of a liquid crystal compound, wherein a retardation layer and a polarizing layer (alignment layer of a liquid crystal compound) are formed on the film to reduce the occurrence of defective spots such as pinholes. A cellulose film for transferring an alignment layer of a liquid crystal compound to an object, wherein the surface roughness (SRa) of a release surface of the film is 1nm or more and 30nm or less.

Description

Film for transfer of liquid crystal compound alignment layer

Technical Field

The present invention relates to a transfer film for transferring an alignment layer of a liquid crystal compound. More specifically, the present invention relates to: the transfer film for transferring the liquid crystal compound alignment layer can be used for manufacturing a polarizing plate such as a circular polarizing plate laminated with a retardation layer formed by the liquid crystal compound alignment layer, a retardation plate, a polarizing plate having a polarizing layer formed by the liquid crystal compound alignment layer, and the like.

Background

Conventionally, in an image display device, a circularly polarizing plate is disposed on a panel surface of an image display panel on a viewer side in order to reduce reflection of external light. The circularly polarizing plate is composed of a laminate of a linearly polarizing plate and a λ/4 equal phase difference film, and converts the external light on the panel surface facing the image display panel into linearly polarized light by the linearly polarizing plate and then into circularly polarized light by the λ/4 equal phase difference film. When the external light based on the circularly polarized light is reflected on the surface of the image display panel, the rotation direction of the polarizing surface is reversed, and the reflected light is reversely converted into linearly polarized light in the direction of being shielded by the linear polarizing plate through the retardation film such as λ/4 and then shielded by the linear polarizing plate, so that the external emission can be suppressed. As described above, the circularly polarizing plate is used in which a retardation film of λ/4 or the like is laminated on the polarizing plate.

As the retardation film, a single retardation film such as a cyclic olefin (see patent document 1), a polycarbonate (see patent document 2), a stretched film of triacetyl cellulose (see patent document 3) or the like is used. As the retardation film, a retardation film having a laminate in which a transparent film is provided with a retardation layer made of a liquid crystal compound is used (see patent documents 4 and 5). It is described that when a retardation layer (liquid crystal compound alignment layer) made of a liquid crystal compound is provided in the above description, the liquid crystal compound can be transferred.

In addition, a method of forming a retardation film by transferring a retardation layer formed of a liquid crystal compound to a transparent film is known in patent document 6 and the like. In such a transfer method, a method is also known in which a retardation layer made of a liquid crystal compound of λ/4 or the like is provided on a transparent film to form a λ/4 film (see patent documents 7 and 8).

In these transfer methods, various substrates are introduced as substrates for transfer, and transparent resin films such as polyester, triacetyl cellulose, and cyclic polyolefin are exemplified in a large number. Among these, a cellulose-based film such as triacetyl cellulose is free from refractive index anisotropy, and therefore, it is preferable to inspect (evaluate) the state of the retardation layer in a state where the retardation layer is provided on the film base.

However, when a retardation layer laminated polarizing plate (circularly polarizing plate) produced using a cellulose film such as triacetyl cellulose as a film base for transfer is used for antireflection of an image display device, pinhole-like or scratch-like light leakage may occur, which is problematic.

Further, the following methods are also known: a polarizing plate is manufactured by transferring a polarizing layer (liquid crystal compound alignment layer) including a liquid crystal compound and a dichroic dye, which is laminated on a transfer film, to a protective film, but in this case, as in the above case, pinhole-like or scratch-like light leakage may occur, which is a problem.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2012 and 563222

Patent document 2: japanese patent laid-open publication No. 2004-144943

Patent document 3: japanese laid-open patent publication No. 2004-46166

Patent document 4: japanese patent laid-open No. 2006 and 243653

Patent document 5: japanese laid-open patent publication No. 2001-4837

Patent document 6: japanese laid-open patent publication No. 4-57017

Patent document 7: japanese patent laid-open No. 2014-071381

Patent document 8: japanese patent laid-open publication No. 2017-146616

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above problems of the prior art. That is, an object of the present invention is to provide: a cellulose transfer film for transferring an alignment layer of a liquid crystal compound, wherein a retardation layer and a polarizing layer (alignment layer of a liquid crystal compound) are formed on the film to reduce the occurrence of defective spots such as pinholes.

Means for solving the problems

In order to achieve the above object, the present inventors have studied the cause of occurrence of defective spots such as pinholes in a retardation layer laminated polarizing plate (circularly polarizing plate) produced using a cellulose-based film as a film base material for transfer. As a result, they found that: the microstructure of the surface of the film base material largely affects the alignment state and retardation of the liquid crystal compound in the retardation layer formed of the liquid crystal compound on the film base material, and the alignment state and retardation conforming to the design may not be obtained, and thus, a defect such as a pinhole may occur. The present inventors have focused on the surface roughness of the film base material expressed by specific parameters in these microstructures, and have found that: by using a film base material whose surface roughness is controlled to be within a specific range, a retardation layer and a polarizing layer (liquid crystal compound alignment layer) in which generation of defective spots such as pinholes is reduced can be formed without causing the above-described conventional problems, and the present invention has been completed.

That is, the present invention has the following configurations (1) to (4).

(1) A cellulose film for transferring an alignment layer of a liquid crystal compound to an object, wherein the surface roughness (SRa) of a release surface of the transfer film is 1nm to 30 nm.

(2) The film for transferring an alignment layer of a liquid crystal compound according to (1), wherein a ten-point surface roughness (SRz) of a release surface of the transfer film is 5nm or more and 200nm or less.

(3) A laminate for transfer printing of an alignment layer of a liquid crystal compound, which comprises a laminate comprising an alignment layer of a liquid crystal compound and a transfer film, wherein the transfer film is the transfer film described in (1) or (2).

(4) A method for manufacturing a liquid crystal compound oriented layer laminated polarizing plate, comprising the steps of: a step of forming an intermediate laminate by laminating a polarizing plate to the liquid crystal compound alignment layer of the laminate of (3); and a step of peeling the transfer film from the intermediate laminate.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the orientation state and the phase difference of the liquid crystal compound in the retardation layer and the polarizing layer can be designed by using the cellulose-based film whose surface roughness is controlled to be within a specific range as the transfer film for the retardation layer and the polarizing layer, the retardation layer and the polarizing layer (liquid crystal compound alignment layer) in which the occurrence of the defect such as pinhole is reduced can be formed.

Detailed Description

The transfer film of the present invention is used for transferring an alignment layer of a liquid crystal compound to an object (other transparent resin film, polarizing plate, or the like), and is characterized in that the surface roughness (SRa) of the release surface of the transfer film is 1nm or more and 30nm or less. The transfer film may be a single film, or a release layer may be provided on a film serving as a base material by coating or the like. In addition, an antistatic layer, an easy-slip layer, or the like may be provided on the back surface. In the present invention, a film used alone as a transfer film without using a layer such as a release coat layer, a film provided with a release coat layer, a coating layer on the back surface, or the like is collectively referred to as a transfer film, and a film in a state before the coating layer or the like is provided is referred to as a base film.

The resin constituting the film base used in the transfer film of the present invention is a cellulose-based resin, and triacetyl cellulose is preferable among them. Triacetyl cellulose can be suitably used for the optical film.

The transfer film of the present invention may be a single layer or a multilayer structure formed by coextrusion. In the case of a multilayer, the surface layer (release surface side layer a)/back surface side layer (B), a/intermediate layer (C)/a (release surface side layer and back surface side layer are the same), a/C/B, and the like can be given. Further, the structure may be a multilayer structure having 4 or more layers.

Transfer films are industrially supplied in the form of rolls formed by winding the films. The lower limit of the roll width is preferably 30cm, more preferably 50cm, further preferably 70cm, particularly preferably 90cm, and most preferably 100 cm. The upper limit of the roll width is preferably 5000cm, more preferably 4000cm, and still more preferably 3000 cm.

The lower limit of the roll length is preferably 100m, more preferably 500m, and still more preferably 1000 m. The upper limit of the roll length is preferably 100000m, more preferably 50000m, and still more preferably 30000 m.

(surface roughness of mold release)

The release surface (surface of a layer a) of the transfer film of the present invention is preferably smooth. In the present invention, the "release surface" of the transfer film refers to a surface of the transfer film on which the liquid crystal compound alignment layer transferred by the transfer film is intended to be provided. In the case where a flattening coat layer, a release layer, or the like, which will be described later, is provided, if a liquid crystal compound alignment layer is provided thereon, the surface (surface in contact with the liquid crystal compound alignment layer) of the flattening layer, the release layer, or the like is the "release surface" of the transfer film.

The lower limit of the three-dimensional arithmetic mean roughness (SRa) of the release surface of the transfer film of the present invention is preferably 1nm, more preferably 2 nm. If lower than the above, it may be difficult to achieve a value in practice. The upper limit of the SRa on the release surface of the transfer film of the present invention is preferably 30nm, more preferably 25nm, still more preferably 20nm, particularly preferably 15nm, most preferably 10 nm. If the amount exceeds the above range, the alignment of the liquid crystal compound may be disturbed.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the release surface of the transfer film of the present invention is preferably 5nm, more preferably 10nm, and still more preferably 13 nm. If lower than the above, it may be difficult to achieve a value in practice. The upper limit of the SRz of the release surface of the transfer film of the present invention is preferably 200nm, more preferably 150nm, still more preferably 120nm, particularly preferably 100nm, most preferably 80 nm. If the amount exceeds the above range, the alignment of the liquid crystal compound may be disturbed.

The lower limit of the maximum height of the release surface of the transfer film of the present invention (SRy: maximum peak height of release surface SRp + maximum valley depth of release surface SRv) is preferably 10nm, more preferably 15nm, and still more preferably 20 nm. If lower than the above, it may be difficult to achieve a value in practice. The upper limit of SRy on the release surface of the transfer film of the present invention is preferably 300nm, more preferably 250nm, still more preferably 150nm, particularly preferably 120nm, most preferably 100 nm. If the amount exceeds the above range, the alignment of the liquid crystal compound may be disturbed.

The upper limit of the number of protrusions having a height difference of 0.5 μm or more on the release surface of the transfer film of the present invention is preferably 5 protrusions/m²More preferably 4/m²More preferably 3/m²Particularly preferably 2/m²Most preferably 1/m². If the amount exceeds the above range, the alignment of the liquid crystal compound may be disturbed.

If the roughness of the release surface exceeds the above range, the fine portion of the liquid crystal compound alignment layer formed on the transfer film of the present invention does not become an alignment state or a retardation in accordance with the design, and pinhole-like or scratch-like defects may occur. The reason for this is considered as follows. First, as will be described later, an alignment control layer such as a brushing-off alignment control layer or a photo-alignment control layer may be provided between the transfer film and the liquid crystal compound alignment layer, but if the alignment control layer is a brushing-off alignment control layer, the alignment control layer in the convex portion is peeled off during brushing, and the brushing of the peak portion and the concave portion of the convex portion becomes insufficient, which may cause the generation of defective dots. In addition, when the release surface layer contains particles, the particles are detached during brushing, and the surface is considered to be a cause of generation of a flaw. In addition, in the case of either the rubbing treatment of the alignment control layer or the optical alignment control layer, when the film is wound in a state where the alignment control layer is provided, the film is rubbed against the back layer, and therefore, voids are generated in the alignment control layer in the convex portion, or alignment disorder is caused by pressure, which is also considered to be a cause of generation of the defective spot. When the liquid crystal compound alignment layer is provided on the alignment control layer due to the defects of the alignment control layer, the alignment of the liquid crystal compound is improperly caused in a minute portion thereof, and an alignment state and a retardation which are in accordance with the design are not obtained.

In addition, when the liquid crystal compound is applied to the transfer film without providing an alignment control layer by directly forming the liquid crystal compound alignment layer on the transfer film, the reason is that the retardation that does not satisfy the design cannot be obtained, and it is considered to be a cause of generation of a defect, for example, the thickness of the liquid crystal compound alignment layer becomes thin at the convex portion of the release surface of the transfer film, or conversely, the thickness of the liquid crystal compound alignment layer becomes thick at the concave portion of the release surface of the transfer film.

In order to set the roughness of the release surface (a) within the above range, the following method may be mentioned.

The release side layer (surface layer) of the base film is made to contain no particles.

When the release surface side layer (surface layer) of the base film contains particles, the particles are made to have small particle diameters.

Smoothing the casting belt.

Reduction of the solvent content of the base film when the base film is peeled from the casting tape.

When the release surface side layer (surface layer) of the base film contains particles, a flattening coating layer is provided.

In the present invention, the "release surface side layer" of the base film refers to a layer in which a release surface is present among layers of the resin constituting the base film. Here, when the base film is a single layer, it is also referred to as a release surface side layer. In this case, the back-surface-side layer and the release-surface-side layer, which will be described later, are the same layer.

In addition to the above, it is also important to clean the raw materials and the production process as described below.

The particle dispersion, triacetyl cellulose solution, and cast dope added to the dope were filtered.

The coating agent is filtered to remove foreign matter.

Film formation, coating, and drying are performed in a clean environment.

The surface layer is preferably substantially free of particles for smoothing. By substantially free of particles is meant that the particle content is below 50ppm, preferably below 30 ppm.

To improve the sliding properties of the surface, the surface layer may comprise particles. When the particles are contained, the lower limit of the surface layer particle content is preferably 0ppm, more preferably 50ppm, and further preferably 100 ppm. The upper limit of the surface layer particle content is preferably 20000ppm, more preferably 10000ppm, still more preferably 8000ppm, particularly preferably 6000 ppm. If the amount exceeds the above range, the roughness of the surface layer may not be in the preferable range.

The lower limit of the particle size of the surface layer is preferably 0.005. mu.m, more preferably 0.01. mu.m, and still more preferably 0.02. mu.m. The upper limit of the particle size of the surface layer is preferably 3 μm, more preferably 1 μm, still more preferably 0.5 μm, and particularly preferably 0.3. mu.m. If the amount exceeds the above range, the roughness of the surface layer may not be in the preferable range.

Even when the surface layer does not contain particles or when particles having a small particle diameter are formed, if the lower layer contains particles, the roughness of the release surface layer may be increased by the influence of the particles of the lower layer. In this case, it is preferable to adopt a method of increasing the thickness of the release surface layer, or providing an under layer (intermediate layer) containing no particles.

The lower limit of the thickness of the surface layer is preferably 0.1. mu.m, more preferably 0.5. mu.m, still more preferably 1. mu.m, particularly preferably 3 μm, most preferably 5 μm. The upper limit of the thickness of the surface layer is preferably 97%, more preferably 95%, and still more preferably 90% of the total thickness of the transfer film.

An intermediate layer free of particles means substantially free of particles, the content of particles being less than 50ppm, preferably less than 30 ppm. The lower limit of the thickness of the intermediate layer with respect to the total thickness of the transfer film is preferably 10%, more preferably 20%, and still more preferably 30% with respect to the total thickness of the transfer film. The upper limit is preferably 95%, more preferably 90%.

When the surface layer of the transfer film (base film) has high roughness, a planarizing coating layer may be provided. Examples of the resin used for the planarizing coat layer include resins generally used as coating agents, such as polyester, acrylic, polyurethane, polystyrene, and polyamide. Also, a crosslinking agent such as melamine, isocyanate, epoxy resin, oxazoline compound, or the like is preferably used. They are applied as a coating agent dissolved or dispersed in an organic solvent, water and dried. Or acrylic, it may be applied solvent-free and cured under radiation. The planarizing coating can be an oligomer barrier coating. In the case where the release layer is provided by coating, the release layer itself may be thickened.

The lower limit of the thickness of the surface-flattening coating layer is preferably 0.01. mu.m, more preferably 0.1. mu.m, still more preferably 0.2. mu.m, and particularly preferably 0.3. mu.m. If the amount is less than the above, the planarization effect may be insufficient. The upper limit of the thickness of the surface-flattening coating layer is preferably 10 μm, more preferably 7 μm, still more preferably 5 μm, and particularly preferably 3 μm. Even if the amount exceeds the above, the planarization effect cannot be obtained in some cases.

The planarization coating may be applied on-line during the film formation process or may be separately provided off-line.

(Release surface)

The obtained base film can have either the casting band surface or the opposite surface as the release surface, and the casting band surface is preferably made to have a release surface because the roughness of the casting band surface is generally reduced.

(Release layer)

The obtained base film can be used as it is as a transfer film as long as it has a peeling property from a transfer (liquid crystal compound alignment layer). In order to adjust the releasability, the film may be subjected to a surface treatment. Examples of the surface treatment include saponification treatment, corona treatment, and plasma treatment.

In addition, a release layer may be provided. As the releasing layer, a known releasing agent can be used, and preferable examples thereof include alkyd resin, amino resin, long-chain acrylic acrylate, silicone resin, and fluororesin. These can be appropriately selected depending on the adhesion to the transferred material. The base film may be surface-treated in order to improve the adhesion between the base film and the release layer. The surface treatment may be the above-mentioned treatment. In addition, an easy adhesion coating may be performed.

(backside roughness)

In addition, even if the release surface of the transfer film of the present invention is made smooth, a defective dot may occur in the liquid crystal compound alignment layer. This is known to be because the transfer film is supplied in a rolled state, the front surface is in contact with the back surface, and the roughness of the back surface is transferred to the front surface (the convex portion of the back surface is transferred to the release layer to form the concave portion). In the transfer film provided with the liquid crystal compound alignment layer, a masking film may be bonded and wound up in order to protect the liquid crystal compound alignment layer, but in order to reduce the cost, the masking film is often wound up as it is. When the liquid crystal compound alignment layer is wound in a state where the liquid crystal compound alignment layer is provided, the liquid crystal compound alignment layer is likely to have a phenomenon of a depression, a void, or a disturbance in alignment due to a convex portion on the back surface. Further, it is considered that, when the liquid crystal compound alignment layer is provided later than the liquid crystal compound alignment layer without winding the liquid crystal compound alignment layer, voids are generated in the liquid crystal compound alignment layer due to the convex portions on the back surface, and the alignment is disturbed. In particular, the pressure is high in the core portion, and these phenomena are likely to occur. Based on the above findings, it is possible to prevent the above-described defective spots by setting the roughness of the surface (back surface) opposite to the release surface to be within a specific range.

The lower limit of the three-dimensional arithmetic mean roughness (SRa) of the back surface of the transfer film of the present invention is preferably 3nm, more preferably 4nm, and still more preferably 5 nm. If the amount is less than the above range, the slidability is deteriorated, and the sliding is not smooth during roll feeding, winding, or the like, and scratches may be easily generated. The upper limit of the SRa on the back surface of the transfer film of the present invention is preferably 50nm, more preferably 45nm, and still more preferably 40 nm. If the number exceeds the above, the number of defective pixels may increase.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the back surface of the transfer film of the present invention is preferably 15nm, more preferably 20nm, and still more preferably 25 nm. The upper limit of the SRz of the back surface of the transfer film of the present invention is preferably 1500nm, more preferably 1200nm, still more preferably 1000nm, particularly preferably 700nm, most preferably 500 nm. If the number exceeds the above, the number of defective pixels may increase.

The lower limit of the maximum height of the back surface of the transfer film of the present invention (SRy: back surface maximum peak height SRp + back surface maximum valley depth SRv) is preferably 20nm, more preferably 30nm, still more preferably 40nm, and particularly preferably 50 nm. The upper limit of the maximum height SRy of the back surface of the transfer film of the present invention is preferably 2000nm, more preferably 1500nm, still more preferably 1200nm, particularly preferably 1000nm, and most preferably 700 nm. If the number exceeds the above, the number of defective pixels may increase.

The upper limit of the number of protrusions having a height difference of 2 μm or more on the back surface of the transfer film of the present invention is preferably 5 protrusions/m²More preferably 4/m²More preferably 3/m²Particularly preferably 2/m²Most preferably 1/m². If the number exceeds the above, the number of defective pixels may increase.

If the roughness of the back surface of the transfer film of the present invention shown by the above parameters is less than the above range, the slip property of the film is deteriorated, and the film is less likely to slip when being transported in a roll, wound up, or the like, and scratches are likely to be generated in some cases. Further, in winding during film production, winding is unstable, wrinkles are generated, and defective products are produced, or irregularities at the end of the wound roll become large, and the film tends to be warped or to be broken in the subsequent steps.

If the roughness of the back surface of the transfer film of the present invention exceeds the above, the above-described defective spots are likely to occur.

In order to set the roughness of the back surface to the above range, the following method may be mentioned.

The specific particles are contained in the back surface layer (back surface layer) of the base film.

The intermediate layer of the base film is made thin so as to contain no particles on the back layer side (back layer) by using a layer containing particles.

When the roughness of the back surface side layer (back surface layer) of the base film is large, a planarizing coating layer is provided.

When the back surface side layer (back surface layer) of the base film does not contain particles, or when the roughness is small, an easy-slip coating layer (particle-containing coating layer) is provided.

The lower limit of the particle size of the back layer is preferably 0.005. mu.m, more preferably 0.01. mu.m, still more preferably 0.05. mu.m, and particularly preferably 0.1. mu.m. If the amount is less than the above range, the slidability is deteriorated, and poor winding may occur. The upper limit of the particle size of the back layer is preferably 5 μm, more preferably 3 μm, and still more preferably 2 μm. If the amount exceeds the above range, the back surface may be excessively roughened.

In the case where the back surface contains particles, the lower limit of the content of particles in the back surface layer is preferably 50ppm, and more preferably 100 ppm. If the amount is less than the above range, the effect of the slipperiness by the addition of the particles may not be obtained. The upper limit of the back surface layer particle content is preferably 10000ppm, more preferably 7000ppm, and still more preferably 5000 ppm. If the amount exceeds the above range, the back surface may be excessively roughened.

The lower limit of the thickness of the back surface layer is preferably 0.1. mu.m, more preferably 0.5. mu.m, still more preferably 1. mu.m, particularly preferably 3 μm, most preferably 5 μm. The upper limit of the thickness of the back surface layer is preferably 95%, more preferably 90%, and still more preferably 85% of the total thickness of the transfer film.

It is also preferred that the intermediate layer contain particles and the back layer be thinned without particles to control the roughness of the back surface. By adopting such a form, it is possible to ensure the roughness of the back surface while preventing the particles from falling off.

The particle diameter and the amount of addition of the particles as the intermediate layer are the same as those of the particles of the back layer. The lower limit of the thickness of the back layer in this case is preferably 0.5 μm, more preferably 1 μm, and still more preferably 2 μm. The upper limit of the thickness is preferably 30 μm, more preferably 25 μm, and still more preferably 20 μm.

When the back surface of the base film is rough, a planarizing coating layer is preferably provided. The planarization coating can be the same as those listed in the planarization coating of the surface.

The lower limit of the thickness of the back surface planarization coating layer is preferably 0.01. mu.m, more preferably 0.03. mu.m, and still more preferably 0.05. mu.m. If the amount is less than the above, the effect of planarization may be reduced. The upper limit of the thickness of the back surface planarization coating layer is preferably 10 μm, more preferably 5 μm, and still more preferably 3 μm. Even if the above is exceeded, the planarization effect is saturated.

An easy-to-slip coating containing particles may be provided on the back side. When the particles are not contained on the back surface side of the base film or the roughness is insufficient, the slip-resistant coating layer is effective.

The lower limit of the particle size of the back surface slipping coating layer is preferably 0.01 μm, more preferably 0.05 μm. If the content is less than the above range, slipperiness may not be obtained. The upper limit of the particle size of the back surface slipping coating layer is preferably 5 μm, more preferably 3 μm, still more preferably 2 μm, and particularly preferably 1 μm. If the amount exceeds the above range, the roughness of the back surface may be too high.

The lower limit of the particle content of the back surface slipping coating layer is preferably 0.1 mass%, more preferably 0.5 mass%, further preferably 1 mass%, particularly preferably 1.5 mass%, most preferably 2 mass%. If the content is less than the above range, slipperiness may not be obtained. The upper limit of the particle content of the back surface slipping coating layer is preferably 20 mass%, more preferably 15 mass%, and still more preferably 10 mass%. If the amount exceeds the above range, the roughness of the back surface may be too high.

The lower limit of the thickness of the back surface slipping coating layer is preferably 0.01 μm, more preferably 0.03 μm, and still more preferably 0.05. mu.m. The upper limit of the thickness of the back surface slipping coating layer is preferably 10 μm, more preferably 5 μm, still more preferably 3 μm, particularly preferably 2 μm, and most preferably 1 μm.

When these coatings are provided, the substrate film is preferably subjected to the above-described surface treatment and easy adhesion coating.

The cellulose-based film can be produced by a general method such as a casting method or a melt extrusion method. Hereinafter, the description will be briefly made, referring to the casting method as an example.

First, a cellulose resin is dissolved in a solvent to prepare a cement in which particles are dispersed as needed. In the case of adding the particles, it is also preferable to prepare a dispersion of the particles in advance and add the dispersion to a solution of the cellulose resin.

In order to achieve an appropriate surface roughness, it is preferable that the dispersion liquid of particles or the slurry is filtered by a filter to remove coarse particles. The lower limit of the filtration accuracy of the filter used is preferably 0.5 μm, more preferably 1 μm. The upper limit of the filtration accuracy of the filter is preferably 100 μm, more preferably 50 μm, still more preferably 25 μm, particularly preferably 20 μm, most preferably 10 μm. The value thereof can be determined suitably according to the particle size of the added particles.

The dope flows out from the die and spreads on a casting belt of metal or the like.

Casting belt roughness (conveyer belt roughness)

The lower limit of the casting band roughness (SRa) is preferably 1nm, more preferably 2 nm. The upper limit of the casting band roughness (SRa) is preferably 15nm, more preferably 12 nm.

The lower limit of the casting band roughness (SRz) is preferably 1nm, more preferably 2 nm. The upper limit of the casting belt roughness (SRz) is preferably 50nm, more preferably 40 nm.

The lower limit of the maximum height (SRy) of the casting band roughness is preferably 2 nm. The upper limit of the maximum height (SRy) of the casting band roughness is preferably 100 nm.

By setting the parameters of the respective roughness of the casting belt to the above ranges, it becomes easy to control the roughness of the base film to an appropriate range.

And blowing air to the mucilage on the casting belt to remove the solvent. The air supply temperature is preferably 20-100 ℃. The upper limit of the blowing temperature is preferably not more than the boiling point of the solvent contained in the cement. In addition, the temperature is preferably higher for the second half. Further, the air volume is preferably initially small to prevent the surface of the cement from being rippled by the wind or the latter half from becoming large. The dope (film) from which the solvent has been removed to some extent is peeled off from the casting belt, and is further introduced into a drying step.

(solvent content)

The roughness of the casting band face of the film when the film is peeled from the casting band substantially reflects the roughness of the casting band surface. However, a large amount of solvent generally remains in the film when peeled from the casting belt, and the amount of the remaining solvent is removed to 1% or less in the subsequent drying step. At this time, the volume is reduced, and the irregularities generated by the particles gradually float on the surface of the film. Therefore, by reducing the solvent content of the film when the film is peeled from the casting belt, it is possible to reduce the volume shrinkage thereof, or reduce the surface unevenness. In contrast, fine adjustment is performed by increasing the amount of the residual solvent to increase the unevenness.

The lower limit of the residual solvent at the time of peeling the casting tape is preferably 10 mass%, more preferably 15 mass%, further preferably 20 mass%, particularly preferably 25 mass%. If the amount is less than the above range, the drying time may be prolonged, or the productivity may be lowered. The upper limit of the residual solvent in the casting tape peeling is preferably 250 mass%, more preferably 200 mass%, further preferably 150 mass%, particularly preferably 100 mass%, most preferably 80 mass%. If the amount exceeds the above range, the roughness may increase or the film formability may decrease.

In the drying step, the following may be used: a flow dryer that blows dry air from above and below to float and feed the film, a roll dryer that has a plurality of rolls in the dryer, a roll dryer that gradually feeds the film in a W-shape on the rolls, a tenter dryer that fixes both ends of the film with clips and dries the film in a tenter, and the like. They may be used in a suitable combination. Among these drying, the drying is preferably carried out at 50 to 170 ℃ and more preferably at 60 to 160 ℃. Further, it is also preferable to apply some stretching in the flow direction by utilizing the difference in peripheral speed of the rollers, or to apply some stretching in the width direction by expanding the width of the clip in the tenter. Depending on the purpose, the stretch ratio is preferably 101 to 200%, more preferably 103 to 150%, and particularly preferably 105 to 130%. By setting the retardation of the cellulose film to the above range, the retardation of the cellulose film can be maintained at a low level, and the alignment state of the liquid crystal compound alignment layer with the film can be easily and accurately inspected. In addition, the wrinkles of the film are pressed, or the uniformity of the thickness may be improved.

The dried film was wound up on a core. In the winding, both ends may be subjected to thickness alignment processing (cutting processing).

The lower limit of the residual solvent of the final film is preferably 0%, more preferably 0.001%. If lower than the above, it may be difficult to achieve a value in practice. The upper limit of the final residual solvent is preferably 2%, more preferably 1%, and still more preferably 0.5%. By setting the above range, the dimensional stability when used as a release film is excellent.

In the case of in-line coating, it is preferable to perform coating in front of a tenter dryer or a flow dryer used for drying the film and dry the film in these dryers, but a separate coating-drying machine may be provided after the film is dried.

The air in these steps is preferably air of class 10000 or less, further class 1000 or less by a HEPA filter or the like.

Next, additional features of the transfer film of the present invention will be described.

(in-plane retardation of transfer film)

The transfer film of the present invention preferably has a low in-plane retardation. Specifically, the in-plane retardation of the transfer film of the present invention is preferably 50nm or less, more preferably 30nm or less, further preferably 20nm or less, and particularly preferably 10nm or less. By setting the in-plane retardation of the transfer film to the above range, the alignment state of the liquid crystal compound alignment layer can be inspected by irradiating the transfer film with linearly polarized light in a state where the liquid crystal compound alignment layer is laminated thereon. For example, when the liquid crystal compound alignment layer is a retardation layer, a sample is irradiated with linearly polarized light in an oblique direction (for example, 45 degrees) with respect to the slow axis of the retardation layer to be examined, and the polarized light that becomes elliptically polarized light is returned to linearly polarized light by passing through the other retardation layer by the retardation layer, and light is received through a polarizing plate in which the linearly polarized light becomes an extinction state. Thus, when a pinhole-like defective dot is present in the retardation layer, the defective dot can be detected as a bright spot.

The retardation of the transfer film can be determined by measuring the refractive index and thickness in the 2-axis direction, or can be determined by using a commercially available automatic birefringence measuring device such as KOBRA-21ADH (prince's instruments).

In order to set the in-plane retardation of the transfer film to the above range, the following methods may be mentioned: in the case of stretching without stretching or in the case of stretching in the film forming step of the base film, the stretching ratios in the flow direction and the width direction are adjusted, or triacetyl cellulose used as a raw material is used, and acetyl groups or additives having a low birefringence are adjusted.

The lower limit of the haze of the transfer film of the present invention is preferably 0.01%, more preferably 0.1%. If lower than the above, it may be difficult to achieve a value in practice. The upper limit of the haze of the transfer film of the present invention is preferably 3%, more preferably 2.5%, still more preferably 2%, and particularly preferably 1.7%. If the amount exceeds the above range, the polarized light may be disturbed by the irradiation of polarized UV, and a retardation layer conforming to the design may not be obtained. In addition, light leakage may occur due to diffuse reflection when inspecting the retardation layer, which may make inspection difficult.

The lower limit of the antistatic property (surface resistance) of the transfer film of the present invention is preferably 1X 10⁵Omega/□, more preferably 1X 10⁶Omega/□. Even if the amount is less than the above range, the effect is saturated, and the effect more than the above range may not be obtained. Further, the upper limit of the antistatic property (surface resistance) of the transfer film of the present invention is preferably 1X 10¹³Omega/□, more preferably 1X 10¹²Omega/□, more preferably 1X 10¹¹Omega/□. If the amount exceeds the above range, repulsion by static electricity may occur, or the alignment direction of the liquid crystal compound may be disturbed. The antistatic property (surface resistance) can be set within the above range by kneading an antistatic agent into the transfer film, providing an antistatic coating layer on the lower layer or the opposite surface of the release layer, or adding an antistatic agent to the release layer.

Examples of the antistatic agent to be added to the antistatic coating layer, the release layer, and the transfer film include conductive polymers such as polyaniline and polythiophene, conductive fine particles such as polystyrene sulfonate plasma polymers, tin-doped indium oxide, and antimony-doped tin oxide.

The transfer film may be provided with a release layer. However, the film itself has low adhesion to a transfer such as a retardation layer or an alignment layer, and when sufficient releasability is obtained even without a release layer, the release layer may not be provided. When the adhesion is too low, the adhesion may be adjusted by performing corona treatment or the like on the surface. The releasing layer can be formed using a known releasing agent, and preferable examples thereof include alkyd resin, amino resin, long-chain acrylic acrylate, silicone resin, and fluororesin. These can be appropriately selected depending on the adhesion to the transferred material.

(liquid Crystal Compound alignment layer transfer laminate)

Next, the liquid crystal compound alignment layer transfer laminate of the present invention will be described.

The laminate for transferring an alignment layer of a liquid crystal compound of the present invention has a structure in which an alignment layer of a liquid crystal compound and the transfer film of the present invention are laminated. The liquid crystal compound alignment layer must be coated on the transfer film and aligned. As a method of orientation, there is the following method: a method of imparting an alignment control function by performing a brushing treatment or the like on the lower layer (release surface) of the liquid crystal compound alignment layer; a method of directly aligning a liquid crystal compound by applying the liquid crystal compound and irradiating the liquid crystal compound with polarized ultraviolet rays or the like.

(orientation control layer)

In addition, a method of providing an alignment control layer on a transfer film and providing an alignment layer of a liquid crystal compound on the alignment control layer is also preferable. In the present invention, the alignment control layer and the liquid crystal compound alignment layer may be collectively referred to as a liquid crystal compound alignment layer, instead of the liquid crystal compound alignment layer alone. The alignment control layer may be any alignment control layer as long as the liquid crystal compound alignment layer can be brought into a desired alignment state, and examples thereof include a brushing alignment control layer obtained by brushing a coating film of a resin, and a photo-alignment control layer having an alignment function by aligning molecules by irradiation with polarized light.

(rubbing treatment orientation control layer)

As the polymer material used in the orientation control layer formed by the brushing treatment, polyvinyl alcohol and derivatives thereof, polyimide and derivatives thereof, acrylic resins, polysiloxane derivatives, and the like are preferably used.

Next, a method for forming an alignment control layer by a brushing process will be described. First, a coating liquid for an alignment control layer subjected to brushing treatment containing the polymer material is applied to a release surface of a film, and then heated and dried to obtain an alignment control layer before brushing treatment. The orientation controlling layer coating liquid may have a crosslinking agent.

As the solvent of the orientation control layer coating liquid for the brushing treatment, any solvent may be used without limitation as long as the polymer material is dissolved. Specific examples thereof include alcohols such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, and cellosolve; ester solvents such as ethyl acetate, butyl acetate, and γ -butyrolactone; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; ether solvents such as tetrahydrofuran and dimethoxyethane. These solvents may be used alone or in combination.

The concentration of the orientation control layer coating liquid for the brushing treatment can be suitably adjusted depending on the kind of the polymer and the thickness of the orientation control layer to be produced, and is preferably in the range of 0.2 to 20 mass%, particularly preferably 0.3 to 10 mass%, in terms of the solid content concentration. As the coating method, known methods such as a coating method such as a gravure coating method, a die coating method, a bar coating method, and an applicator method, and a printing method such as a flexo method can be used.

The heating and drying temperature is preferably in the range of 30 to 170 ℃, more preferably 50 to 150 ℃, and further preferably 70 to 130 ℃. When the drying temperature is low, it is necessary to take a long drying time, and the productivity is poor. When the drying temperature is too high, the transfer film may be thermally stretched or thermally shrunk to fail to achieve a designed optical function or to deteriorate planarity. The heating and drying time may be, for example, 0.5 to 30 minutes, more preferably 1 to 20 minutes, and still more preferably 2 to 10 minutes.

The thickness of the orientation control layer in the brush-polishing treatment is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm, and particularly preferably 0.1 to 1 μm.

Subsequently, a brushing process is performed. The brushing treatment can be usually performed by rubbing the surface of the polymer layer with paper or cloth in a constant direction. The surface of the orientation control layer is usually subjected to brushing treatment using a brush roller of a napped cloth of fibers such as nylon, polyester, acrylic or the like. In order to provide an alignment control layer for a liquid crystal compound aligned in a predetermined direction inclined with respect to the longitudinal direction of a long film, the direction of brushing of the alignment control layer also needs to be an angle corresponding thereto. The angle adjustment can be matched with the angle adjustment of the brush grinding roller and the film, the conveying speed of the film and the rotation speed of the roller.

The surface of the transfer film may be subjected to a direct brushing process on the release surface of the transfer film to provide the orientation control function, and this is included in the technical scope of the present invention.

(optical orientation control layer)

The optical alignment control layer refers to an alignment film as follows: a coating liquid containing a polymer or monomer having a photoreactive group and a solvent is applied to a film, and polarized light, preferably polarized ultraviolet light, is irradiated to impart an alignment regulating force. The photoreactive group is a group that generates liquid crystal alignment ability by light irradiation. Specifically, a photoreaction is generated which is a source of the liquid crystal aligning ability, such as an alignment induction or isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction of molecules by irradiation with light. Among the photoreactive groups, a group that causes a dimerization reaction or a photocrosslinking reaction is preferable in terms of excellent alignment properties and maintaining a smectic liquid crystal state of the liquid crystal compound alignment layer. As the photoreactive group capable of causing the above reaction, an unsaturated bond, particularly a double bond is preferable, and a group having at least one selected from the group consisting of a C ═ C bond, a C ═ N bond, an N ═ N bond, and a C ═ O bond is particularly preferable.

Examples of the photoreactive group having a C ═ C bond include a vinyl group, a polyene group, a stilbene group (stilbene), a stilbene group, an azostilbazolium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a C ═ N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of the photoreactive group having an N ═ N bond include groups having a basic structure of azoxybenzene, such as an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, and a formazanyl group. Examples of the photoreactive group having a C ═ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and haloalkyl groups.

Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a photo-alignment layer which requires a small amount of polarized light for photo-alignment of a cinnamoyl group and a chalcone group, is easy to obtain thermal stability, and is excellent in stability with time is preferable. Further, as the polymer having a photoreactive group, a cinnamoyl group having a cinnamic acid structure at a terminal portion of a side chain of the polymer is particularly preferable. Examples of the main chain structure include polyimide, polyamide, (meth) acrylic, and polyester.

Specific examples of the orientation control layer include orientation control layers described in Japanese patent laid-open Nos. 2006-285197, 2007-76839, 2007-138138, 2007-94071, 2007-121721, 2007-140465, 2007-156439, 2007-133184, 2009-109831, 2002-229039, 2002-265541, 2002-317013, 2003-520878, 2004-529220, 2013-33248, 2015-7702, 2015-129210.

The solvent of the coating liquid for forming a photo-alignment control layer can be used without limitation as long as the polymer having a photoreactive group and the monomer are dissolved. As a specific example, those listed as methods for forming an alignment control layer by brushing treatment can be given. It is also preferable to add a photopolymerization initiator, a polymerization inhibitor, and various stabilizers to the coating liquid for forming a photo-alignment control layer. Further, a polymer having a photoreactive group, a polymer other than a monomer, or a monomer having no photoreactive group copolymerizable with the monomer having a photoreactive group may be added.

The concentration of the coating liquid for forming the photo-alignment control layer, the coating method, and the drying conditions may be those exemplified as the method for forming the alignment control layer by brushing. The thickness is also the same as the preferred thickness of the orientation control layer for the brushing treatment.

The polarized light may be either of a method of irradiating from the direction of the surface of the photo-alignment control layer before alignment or a method of irradiating from the direction of the surface of the transfer film through the transfer film.

The wavelength of the polarized light is preferably a wavelength region in which the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, ultraviolet rays having a wavelength of 250 to 400nm are preferable. Examples of the light source of polarized light include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an ultraviolet laser such as KrF or ArF, and the like, and a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp are preferable.

The polarized light can be obtained by, for example, passing light from the aforementioned light source through a polarizing plate. The direction of the polarized light can be adjusted by adjusting the polarization angle of the polarizing plate. Examples of the polarizing plate include a polarizing filter, a polarizing prism such as a Geran-Torpson polarizer and a Glan-Taylor polarizer, and a wire grid type polarizing plate. The polarized light is preferably substantially parallel light.

By adjusting the angle of the polarized light to be irradiated, the direction of the orientation restriction force of the optical orientation control layer can be arbitrarily adjusted.

The irradiation intensity depends on the polymerization initiator and the resin (monomer)Body) and the amount thereof, for example, based on 365nm, preferably 10 to 10000mJ/cm²More preferably 20 to 5000mJ/cm²。

(liquid Crystal Compound alignment layer)

The liquid crystal compound alignment layer is not particularly limited as long as the liquid crystal compound is aligned. Specific examples thereof include a polarizing film (polarizing plate) containing a liquid crystal compound and a dichroic dye, and a retardation layer containing a rod-like or discotic liquid crystal compound.

(polarizing film)

The polarizing film has a function of passing only one-way polarized light, and includes a dichroic dye.

(dichroic dye)

The dichroic dye is a dye having a property that the absorbance in the major axis direction and the absorbance in the minor axis direction of a molecule are different from each other.

The dichroic dye preferably has an absorption maximum wavelength (λ MAX) within a range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, anthraquinone dyes, and the like, and among them, azo dyes are preferable. The azo dyes include monoazo dyes, disazo dyes, trisazo dyes, tetraazo dyes, stilbene azo dyes, and the like, and disazo dyes and trisazo dyes are preferable. The dichroic dyes may be used alone or in combination, and 2 or more kinds thereof are preferably used in combination for adjusting (achromatic) color tone. Combinations of 3 or more are particularly preferred. It is particularly preferable to combine 3 or more azo compounds.

Preferred azo compounds include the dyes described in Japanese patent application laid-open Nos. 2007-126628, 2010-168570, 2013-101328, and 2013-210624.

The dichroic dye is also preferably a polymer of dichroic dye introduced into a side chain of a polymer such as acrylic. Examples of the dichroic dye polymers include polymers listed in Japanese patent application laid-open No. 2016 and 4055 and polymers obtained by polymerizing compounds of formulae 6 to 12 of Japanese patent application laid-open No. 2014 and 206682.

The content of the dichroic dye in the polarizing film is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, even more preferably 1.0 to 15% by mass, and particularly preferably 2.0 to 10% by mass, in the polarizing film, from the viewpoint of improving the orientation of the dichroic dye.

The polarizing film preferably further contains a polymerizable liquid crystal compound for improving the film strength, the degree of polarization, and the film homogeneity. The polymerizable liquid crystal compound herein also includes a film obtained by polymerization.

(polymerizable liquid Crystal Compound)

The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity.

The polymerizable group is a group participating in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group capable of undergoing a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxirane group, and an oxetanyl group. Among them, acryloxy, methacryloxy, vinyloxy, oxirane and oxetanyl groups are preferable, and acryloxy group is more preferable. The compound exhibiting liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, and may be a nematic liquid crystal or a smectic liquid crystal in the thermotropic liquid crystal.

The polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a higher order smectic liquid crystal compound, in terms of obtaining higher polarization characteristics. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher order smectic phase, a polarizing film having a higher degree of alignment order can be produced.

Specific examples of the preferable polymerizable liquid crystal compound include those described in Japanese patent application laid-open Nos. 2002-308832, 2007-16207, 2015-163596, 2007-510946, 2013-114131, WO2005/045485, Lub et al Recl. Travv. Chim. Pays-Bas, 115, 321-328(1996), and the like.

The content ratio of the polymerizable liquid crystal compound in the polarizing film is preferably 70 to 99.5% by mass, more preferably 75 to 99% by mass, further preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass, in the polarizing film, from the viewpoint of improving the alignment property of the polymerizable liquid crystal compound.

The polarizing film may be provided by coating a polarizing film composition coating. The polarizing film composition coating may include a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, and a polymerizable non-liquid crystal compound, a crosslinking agent, and the like.

As the solvent, those listed as the solvent of the alignment layer coating liquid are preferably used.

The polymerization initiator is not limited as long as it is capable of polymerizing the polymerizable liquid crystal compound, and is preferably a photopolymerization initiator which generates active radicals by light. Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, sulfonium salts, and the like.

The sensitizer is preferably a photosensitizer. Examples thereof include xanthone compounds, anthracene compounds, phenothiazine, rubrene, and the like.

Examples of the polymerization inhibitor include hydroquinones, orthophthalic diphenols and thiophenols.

The polymerizable non-liquid crystal compound is preferably a compound copolymerizable with the polymerizable liquid crystal compound, and for example, when the polymerizable liquid crystal compound has a (meth) acryloyloxy group, a (meth) acrylate is exemplified. The (meth) acrylates may be monofunctional or polyfunctional. By using a polyfunctional (meth) acrylate, the strength of the polarizing film can be improved. When a polymerizable non-liquid crystal compound is used, the amount of the polymerizable non-liquid crystal compound in the polarizing film is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 7% by mass. If it exceeds 15 mass%, the degree of polarization may be lowered.

Examples of the crosslinking agent include compounds capable of reacting with functional groups of the polymerizable liquid crystal compound and the polymerizable non-liquid crystal compound, and examples thereof include isocyanate compounds, melamine, epoxy resins, oxazoline compounds, and the like.

The polarizing film composition coating is directly applied to a transfer film or an orientation control layer, and then dried, heated, and cured as necessary to provide a polarizing film.

As the coating method, known methods such as a coating method such as a gravure coating method, a die coating method, a bar coating method, an applicator method, and the like, a printing method such as a flexo method, and the like can be used.

The transfer film after coating is introduced into a hot air dryer, an infrared dryer, or the like, and dried at 30 to 170 ℃, more preferably 50 to 150 ℃, and still more preferably 70 to 130 ℃. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, and further more preferably 2 to 10 minutes.

Heating may be performed to more firmly align the dichroic dye and the polymerizable liquid crystal compound in the polarizing film. The heating temperature is preferably within a temperature range in which the polymerizable liquid crystal compound forms a liquid crystal phase.

When the polymerizable liquid crystal compound is contained in the polarizing film composition coating material, curing is preferably performed. Examples of the curing method include heating and light irradiation, and light irradiation is preferable. The dichroic dye may be fixed in a state of being aligned by curing. The curing is preferably performed in a state where a liquid crystal phase is formed in the polymerizable liquid crystal compound, and the curing may be performed by light irradiation at a temperature at which the liquid crystal phase is present. Examples of light in light irradiation include visible light, ultraviolet light, and laser light. In terms of ease of handling, ultraviolet light is preferable.

The irradiation intensity varies depending on the kind and amount of the polymerization initiator and the resin (monomer), and is preferably 100 to 10000mJ/cm, for example, 365nm²More preferably 200 to 5000mJ/cm²。

In the case where the polarizing film is directly applied to a transfer film without providing an orientation control layer, the polarizing film may be oriented by irradiating the polarizing film composition with polarized light to cure the polarizing film forming composition. At this time, polarized light (for example, polarized light in an oblique direction) having a desired direction with respect to the longitudinal direction of the transfer film is irradiated. More preferably, the dichroic dye is strongly oriented in accordance with the orientation direction of the polymer liquid crystal by heat treatment thereafter.

The polarizing film has a thickness of 0.1 to 5 μm, preferably 0.3 to 3 μm, and more preferably 0.5 to 2 μm.

(retardation layer)

Examples of the retardation layer include: a layer for optical compensation, a λ/4 layer of a circularly polarizing plate, a λ/2 layer of a circularly polarizing plate, and the like are typically provided between a polarizing plate and a liquid crystal cell of a liquid crystal display device. As the liquid crystal compound, rod-like liquid crystal compounds such as positive and negative a plates, positive and negative C plates, and O plates, discotic liquid crystal compounds, and the like can be used depending on the purpose.

In the case of use as optical compensation of a liquid crystal display device, the degree of retardation can be set as appropriate depending on the type of liquid crystal cell and the properties of the liquid crystal compound used in the cell. For example, in the case of the TN system, an O plate using discotic liquid crystal is preferably used. In the case of the VA system and the IPS system, C-plates and a-plates using rod-like liquid crystal compounds and discotic liquid crystal compounds are preferably used. In the case of the λ/4 retardation layer and the λ/2 retardation layer of the circularly polarizing plate, it is preferable to form the a plate by using a rod-like compound. These retardation layers may be used not only as a single layer but also as a combination of a plurality of layers.

As the liquid crystal compound used in these retardation layers, a polymerizable liquid crystal compound having a polymerizable group such as a double bond is preferable in that the alignment state can be fixed.

Examples of the rod-like liquid crystal compounds include those having a polymerizable group described in Japanese patent application laid-open Nos. 2002-030042, 2004-204190, 2005-263789, 2007-119415, 2007-186430, and 11-513360.

Specific examples of the compound include:

CH₂＝CHCOO-(CH₂)m-O-Ph1-COO-Ph2-OCO-Ph1-O-(CH₂)n-OCO-CH＝CH₂

CH₂＝CHCOO-(CH₂)m-O-Ph1-COO-NPh-OCO-Ph1-O-(CH₂)n-OCO-CH＝CH₂

CH₂＝CHCOO-(CH₂)m-O-Ph1-COO-Ph2-OCH₃

CH₂＝CHCOO-(CH₂)m-O-Ph1-COO-Ph1-Ph1-CH₂CH(CH₃)C₂H₅

wherein m and n are integers of 2 to 6,

ph1 and Ph2 are 1, 4-phenyl (2-position of Ph2 can be methyl),

NPh is 2, 6-naphthyl.

These rod-like liquid crystal compounds are commercially available as LC242 and the like from BASF corporation, and they can be used.

These rod-like liquid crystal compounds may be used in combination of a plurality of kinds at an arbitrary ratio.

Further, examples of the discotic liquid crystal compounds include benzene derivatives, Truxene derivatives, cyclohexane derivatives, aza crown ether type, phenylacetylene type macrocycles and the like, and various substances disclosed in Japanese patent application laid-open No. 2001-155866 are described and suitably used.

Among them, as the discotic compound, a compound having a triphenylene ring shown by the following general formula (1) is preferably used.

In the formula, R₁～R₆Each independently hydrogen, halogen, alkyl, or a group represented by-O-X (wherein X is alkyl, acyl, alkoxybenzyl, epoxy-modified alkoxybenzyl, acryloxy-modified alkyl). R₁～R₆Preferably, the acryloyloxy-modified alkoxybenzyl group is represented by the following general formula (2) (here, m is 4 to 10).

The retardation layer can be provided by applying a composition coating for retardation layer. The composition coating for retardation layer may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, and the like. As these, the alignment control layer and the liquid crystal polarizing plate described in the section of the liquid crystal polarizing plate can be used.

The composition coating material for a retardation layer is applied to a release surface or an orientation control layer of a transfer film, and then dried, heated, and cured to provide a retardation layer.

These conditions are also the conditions described in the section of the alignment control layer and the liquid crystal polarizing plate as preferable conditions.

In this case, a plurality of retardation layers may be provided on 1 transfer film and transferred to an object, or a plurality of materials provided with a single retardation layer on 1 transfer film may be prepared and sequentially transferred to an object.

Further, a polarizing layer and a retardation layer may be provided on 1 transfer film, and the film may be transferred to an object. Further, a protective layer may be provided between the polarizing plate and the retardation layer, or a protective layer may be provided on the retardation layer or between the retardation layers. These protective layers may be provided on the transfer film together with the retardation layer and the polarizing layer and transferred to an object.

The protective layer may be a coating layer of a transparent resin. The transparent resin is not particularly limited to polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyester, polyurethane, polyamide, polystyrene, acrylic resin, epoxy resin, and the like. A crosslinking agent may be added to these resins to form a crosslinked structure. Further, a photocurable composition such as an acrylic resin may be cured, such as a hard coat layer. Further, after providing the protective layer on the transfer film, the protective layer may be subjected to a brushing treatment to provide the liquid crystal compound alignment layer thereon without providing the alignment layer.

(method for producing liquid Crystal Compound alignment layer laminated polarizing plate)

Next, a method for manufacturing a liquid crystal compound alignment layer laminated polarizing plate of the present invention will be described.

The method for manufacturing a liquid crystal compound alignment layer laminated polarizing plate of the present invention includes the steps of: a step of forming an intermediate laminate by laminating a polarizing plate to the liquid crystal compound alignment layer side of the laminate for transferring an alignment layer of a liquid crystal compound of the present invention; and a step of peeling the transfer film from the intermediate laminate.

Hereinafter, a case where the liquid crystal compound alignment layer is used for a circularly polarizing plate will be described as an example. In the case of a circularly polarizing plate, a λ/4 layer is used as a retardation layer (in the transfer laminate, it is called a liquid crystal compound alignment layer). The front retardation of the lambda/4 layer is preferably 100 to 180 nm. Further preferably 120 to 150 nm. When only the λ/4 layer is used as the circular polarizing plate, the orientation axis (slow axis) of the λ/4 layer and the transmission axis of the polarizer are preferably 35 to 55 degrees, more preferably 40 to 50 degrees, and further preferably 42 to 48 degrees. When the polarizing plate is used in combination with a polarizing plate of a stretched film of polyvinyl alcohol, the absorption axis of the polarizing plate is generally the longitudinal direction of the long polarizing plate film, and therefore, when a λ/4 layer is provided on the long transfer film, it is preferable to orient the liquid crystal compound so that the longitudinal direction of the long transfer film is within the above range. In addition, when the angle of the transmission axis of the polarizing plate is different from that in the above case, the liquid crystal compound is aligned in the above relationship in consideration of the angle of the transmission axis of the polarizing plate.

A circularly polarizing plate is produced by transferring a lambda/4 layer in a transfer laminate, in which a lambda/4 layer and a transfer film are laminated, to a polarizing plate. Specifically, a polarizing plate is laminated to the λ/4 layer of the transfer laminate to form an intermediate laminate, and the transfer film is peeled from the intermediate laminate. The polarizing plate may be provided with a protective film on both sides of the polarizer, and preferably with a protective film on only one side. In the case of a polarizing plate having a protective film provided only on one side, it is preferable to bond the retardation layer to the opposite side (polarizing plate side) of the protective film. If protective films are provided on both sides, the phase difference layer is preferably attached to the surface on the assumed image unit side. The surface on the image unit side is assumed to be a surface which is not subjected to surface processing and is generally provided on the visible side, such as a low reflection layer, an antireflection layer, and an antiglare layer. The protective film on the side to which the retardation layer is attached is preferably a protective film having no retardation such as TAC, acrylic, or COP.

Examples of the polarizing plate include: a polarizing plate obtained by separately stretching a PVA-based film; a polarizing plate obtained by coating PVA on an unstretched substrate such as polyester or polypropylene and stretching the substrate together with PVA to form a polarizing plate, and transferring the polarizing plate to a polarizing plate protective film; a polarizing plate formed by coating or transferring a polarizing plate composed of a liquid crystal compound and a dichroic dye on a polarizing plate protective film; and the like, are preferably used.

As a method of adhesion, conventionally known substances such as adhesives and bonding agents can be used. As the adhesive, a polyvinyl alcohol adhesive, an ultraviolet-curable adhesive such as acrylic or epoxy, or a heat-curable adhesive such as epoxy or isocyanate (urethane) is preferably used. Examples of the adhesive include acrylic, urethane, and rubber adhesives. Further, an optical transparent pressure-sensitive adhesive sheet free of an acrylic base material is also preferably used.

When a transfer-type polarizing plate is used as the polarizing plate, the polarizing plate may be transferred onto the retardation layer (liquid crystal compound alignment layer) of the transfer laminate, and then the polarizing plate and the retardation layer may be transferred onto an object (polarizing plate protective film).

As the polarizer protective film on the side opposite to the side on which the retardation layer is provided, commonly known ones such as TAC, acrylic, COP, polycarbonate, and polyester can be used. Among them, TAC, acrylic, COP, and polyester are preferable. The polyester is preferably polyethylene terephthalate. In the case of polyester, a zero retardation film having an in-plane retardation of 100nm or less, particularly 50nm or less, or a high retardation film of 3000nm to 30000nm is preferable.

In the case of using a polyester high retardation film, the angle between the transmission axis of the polarizing plate and the slow axis of the polyester high retardation film is preferably in the range of 30 to 60 degrees, and more preferably in the range of 35 to 55 degrees, for the purpose of preventing glare and coloration when viewing an image by wearing polarized sunglasses. In order to reduce the rainbow unevenness when viewed from a low-angle oblique direction under naked eyes, the angle between the transmission axis of the polarizing plate and the slow axis of the high retardation film of polyester is 10 degrees or less, more preferably 7 degrees or less, or preferably 80 to 100 degrees, more preferably 83 to 97 degrees.

An antiglare layer, an antireflection layer, a low reflection layer, a hard coat layer, and the like may be provided on the polarizer protective film on the opposite side.

(composite retardation layer)

In the λ/4 layer alone, the layer may not be λ/4 over a wide range in the visible light region, and may be colored. Therefore, a λ/4 layer and a λ/2 layer may be used in combination. The front surface retardation of the lambda/2 layer is preferably 200 to 360 nm. Further preferably 240 to 300 nm.

In this case, it is preferable to arrange the λ/4 layer at an angle of λ/4 by laminating λ/2. Specifically, the angle (θ) between the orientation axis (slow axis) of the λ/2 layer and the transmission axis of the polarizing plate is preferably 5 to 20 degrees, and more preferably 7 to 17 degrees. The angle between the orientation axis (slow axis) of the λ/2 layer and the orientation axis (slow axis) of λ/4 is preferably in the range of 2 θ +45 degrees ± 10 degrees, more preferably in the range of 2 θ +45 degrees ± 5 degrees, and still more preferably in the range of 2 θ +45 degrees ± 3 degrees.

In this case, when the polarizing plate is used in combination with a polarizing plate of a stretched film of polyvinyl alcohol, the absorption axis of the polarizing plate is generally the longitudinal direction of the long polarizing plate film, and therefore, when a λ/2 layer or a λ/4 layer is provided on the long transfer film, it is preferable to align the liquid crystal compound so that the longitudinal direction or the direction perpendicular to the length of the long transfer film is within the above range. In addition, when the angle of the transmission axis of the polarizing plate is different from that in the above case, the liquid crystal compound is aligned in the above relationship in consideration of the angle of the transmission axis of the polarizing plate.

Examples of such methods and retardation layers include jp 2008-149577 a, jp 2002-303722 a, WO2006/100830 a, and jp 2015-64418 a.

Further, in order to reduce a change in coloring or the like when viewed obliquely, it is also a preferable embodiment to provide a C plate layer on the λ/4 layer. The C plate layer is positive or negative according to the characteristics of the lambda/4 layer and the lambda/2 layer.

As a method of stacking them, for example, if there is a combination of λ/4 layers and λ/2 layers, it is possible to adopt:

disposing a λ/2 layer on the polarizing plate by transfer, and further disposing a λ/4 layer thereon by transfer.

A lambda/4 layer and a lambda/2 layer were sequentially provided on the transfer film, and the films were transferred onto the polarizing plate.

A lambda/4 layer, a lambda/2 layer, and a polarizing layer are sequentially provided on a transfer film, and the film is transferred to an object.

A λ/2 layer and a polarizing layer are sequentially provided on a transfer film, and the film is transferred to an object and further a λ/4 layer is transferred thereon.

And the like.

In addition, when the C-plates are laminated, it is possible to adopt: a method of transferring a C plate layer onto a λ/4 layer provided on a polarizing plate, a method of providing a C plate layer onto a film, further providing a λ/4 layer or a λ/2 layer and a λ/4 layer thereon, and transferring them, and the like.

The thickness of the circularly polarizing plate thus obtained is preferably 120 μm or less. More preferably 100 μm or less, still more preferably 90 μm or less, particularly preferably 80 μm or less, and most preferably 70 μm or less.

Examples

The present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples described below, and can be carried out by appropriately changing the examples within a range that can meet the gist of the present invention, and these examples are included in the technical scope of the present invention. The evaluation methods of the physical properties in the examples are as follows.

(1) Three-dimensional surface roughness SRa, SRz, SRy

Using a stylus type three-dimensional roughness meter (SE-3AK, manufactured by Seikagaku corporation), under the conditions of a stylus radius of 2 μm and a load of 30mg, the cut-off value was 0.25mm along the longitudinal direction of the film and the feeding speed of the stylus was 0.1 mm/sec over a measurement length of 1mm, the film was divided into 500 dots at a pitch of 2 μm, and the height of each dot was collected by a three-dimensional roughness analyzer (SPA-11). The same operation was continuously performed 150 times at 2 μm intervals in the width direction of the film, that is, 0.3mm in the width direction of the film, and data was collected by an analyzer. Then, the center plane average roughness (SRa), ten-point average roughness (SRz), and maximum height (SRy) were obtained by an analyzer.

(2) The height difference between the release surfaces is 0.5 μm or more (release surface) and the number of protrusions is 2.0 μm or more (back surface)

A test piece having a width of 100mm and a length of 100mm was cut out in the longitudinal direction of the film, and the test piece was sandwiched between 2 polarizing plates to form a cross prism state, and was mounted in a state where the extinction position was maintained. In this state, light was transmitted by a Nikon universal projector V-12 (measurement conditions: 50 times projection lens, 50 times transmission illumination beam switching knob, and transmission inspection), and the long diameter of a portion (scratch or foreign matter) which looked shiny was detected to be 50 μm or more. The test piece was cut into an appropriate size, and the thus-detected portion was observed and measured from a direction perpendicular to the film surface using a three-dimensional shape measuring apparatus (Ryoka System co., ltd. System, Micromap TYPE 550; measurement conditions: wavelength 550nm, WAVE mode, 10 times of objective lens). In this case, the irregularities close to within 50 μm when viewed in a direction perpendicular to the film surface are rectangles which are assumed to cover the same scratches and foreign matter, and the length and width of the rectangles are regarded as the length and width of the scratches and foreign matter. The number of the scratch or foreign matter was quantified by using a cross-sectional image (SURFACE PROFILE DISPLAY). The measurement was performed on 20 test pieces in terms of 1m per each²The number of bad points. The number of bad spots having a height difference (difference between the highest point and the lowest point) of 0.5 μm or more was counted on the release surface, and the number of bad spots having a height difference of 2.0 μm or more was counted on the back surface.

(3) Film thickness (thickness of each layer)

After the film was embedded in an epoxy resin, a cross section was cut out and observed with an optical microscope to determine the thickness.

(4) Residual solvent content

The film was cut into pieces of 10cm X10 cm, and the weight thereof was measured (W1). Thereafter, the film was dried in a circulation dryer at 150 ℃ for 60 minutes and stored in a dryer. The weight of the film at room temperature was measured (W2). The value (%) of W1/(W1-W2). times.100 was calculated as the residual solvent amount.

(5) Inspection of phase difference layer for defect

A sample in which a brushing alignment control layer or a photo alignment control layer as an alignment control layer was disposed between a transfer film and a liquid crystal compound alignment layer was prepared as a sample for inspection. The specific preparation steps are as follows.

(the orientation control layer is a case of the orientation control layer subjected to the brushing treatment)

The transfer film was cut into a size of A4, and a coating material for an orientation control layer by brushing having the following composition was applied to the surface of a release layer by a bar coater and dried at 80 ℃ for 5 minutes to form a film having a thickness of 100 nm. Then, the surface of the obtained film was treated with a brush roll wound with a nylon-made napped cloth to obtain a transfer film in which an orientation control layer for brush treatment was laminated. The brushing was performed at 45 degrees to the longitudinal direction of the transfer film.

Molecular weight of completely saponified polyvinyl alcohol 8002 parts by mass

100 parts by mass of ion-exchanged water

0.1 part by mass of a surfactant

Then, a retardation layer forming solution having the following composition was applied to the brushed surface by a bar coating method. The sheet was dried at 110 ℃ for 3 minutes, cured by irradiation with ultraviolet light, and an 1/4 wavelength layer was formed to obtain a sample for inspection.

(in the case where the orientation control layer is an optical orientation control layer)

A cyclopentanone 5 mass% solution of a polymer represented by the following formula was prepared as a coating material for a light alignment control layer based on the descriptions of example 1, example 2, and example 3 in jp 2013-33248 a.

Subsequently, the transfer film was cut into a size of A4, and the coating material for an optical alignment control layer having the above-mentioned composition was applied to the surface of a release layer by a bar coater, followed by drying at 80 ℃ for 1 minute to form a film having a thickness of 80 nm. Then, the film was irradiated with polarized UV light in a direction of 45 degrees with respect to the longitudinal direction of the film, to obtain a transfer film in which an optical alignment control layer was laminated. These coatings were filtered through a membrane filter having a pore size of 0.2 μm, and then coated and dried in a clean room.

Then, a solution for forming a retardation layer was applied by a bar coating method to the surface on which the optical alignment control layer was laminated. The sheet was dried at 110 ℃ for 3 minutes, cured by irradiation with ultraviolet light, and an 1/4 wavelength layer was formed to obtain a sample for inspection.

Next, using these test samples, the phase difference layer was inspected for defective spots by the following procedure.

A lower polarizing plate was placed on a surface-emitting light source using a white LED using a yellow phosphor as a light source, and the inspection sample prepared as described above was placed thereon such that the extinction axis direction (absorption axis direction) of the polarizing plate was parallel to the longitudinal direction of the inspection sample. Further, a λ/4 film formed by placing a stretched film of a cyclic polyolefin thereon was such that the orientation main axis was in a direction of 45 degrees to the extinction axis of the lower polarizing plate, and an upper polarizing plate was placed thereon such that the extinction axis of the upper polarizing plate was parallel to the extinction axis of the lower polarizing plate. In this state, the extinction state was observed with the naked eye (center portion 15cm × 20cm) and a 20-fold magnifying glass (5cm × 5cm), and evaluated according to the following criteria.

Very good: the bright spots were not observed with the naked eye, and almost no bright spots (2 or less in 5cm × 5cm) were observed with a magnifier.

O: the bright spots were not observed with the naked eye, and a few bright spots (3 or more and 20 or less in 5cm × 5cm) were observed with a magnifier.

And (delta): the bright spots were not observed with the naked eye, but were observed with a magnifying glass (more than 20 out of 5 cm. times.5 cm).

X: the bright point was visually recognized, or the light leakage was considered to be caused by the presence of a large number of bright points which could be observed with a magnifying glass, although the bright point was not recognized.

(6) Inspection of overlapped defective dots 1

Two samples for inspection using the alignment control layer subjected to the brushing treatment were prepared, and the retardation layer mounting surface and the opposite surface were superposed on each other and applied at 1kg/cm²Load of (2) for 10 minutes. The phase difference layer of this sample was examined for defects in the same manner as in (5) examination for defects in the phase difference layer.

(7) Inspection of overlapped defective dots 2

In the inspection 1 of the overlapped defective dots, since the influence of the roughness of the back surface is not easily known when the roughness of the release surface is large, the influence of the roughness of the back surface of the inspection sample using the photo-alignment control layer of example 3 in which the roughness of the release surface is small was examined using the samples for inspection using the photo-alignment control layers of other examples and comparative examples.

Specifically, the retardation layer mounting surface of the inspection sample having the 1/4 wavelength layer provided on the optical orientation control layer of example 3 was superimposed on the opposite surface of the inspection sample using the optical orientation control layers of examples and comparative examples, and applied at 1kg/cm²Load of (2) for 10 minutes. The retardation layer of this sample (sample for inspection of example 3) was inspected for defective spots in the same manner as in (5) inspection of defective spots in the retardation layer.

Example 1

(adjustment of Fine particle Dispersion (P1))

2.00 parts by mass of hydrophobic fumed silica (AEROSIL R812, manufactured by Nippon Aerosil Co. Ltd.) 2.00 parts by mass of triacetyl cellulose, 78.00 parts by mass of methylene chloride, 15 parts by mass of methanol, and 3.00 parts by mass of 1-butanol were put into a grinder and dispersed. The obtained dispersion was filtered through a filter having a nominal diameter of 1 μm to obtain a fine particle dispersion having a volume average particle diameter of 80nm (0.08 μm).

(preparation of triacetylcellulose solution (A1))

Triacetyl cellulose solution (a1) was prepared by stirring and dissolving 20.00 parts by mass of triacetyl cellulose, 68 parts by mass of methylene chloride, 9.5 parts by mass of methanol, and 2.5 parts by mass of 1-butanol.

(preparation of mucilage (D1))

To the triacetyl cellulose solution (a1), the fine particle dispersion (P1) was added, and stirring was performed at 50 ℃ to obtain a dope (D1). The resulting dope was filtered through a filter having a nominal pore size of 2 μm, and then defoamed.

(film making)

The resulting dope (D1) was spread on a casting belt made of chromium-plated stainless steel, and dried by blowing dry air at 35 ℃. The casting belt used was a casting belt having an arithmetic average roughness (SRa) of 3nm, a ten-point average roughness (SRz) of 15nm, and a maximum height (SRy) of 23 nm.

After that, the film was peeled from the casting belt. The peeled film was further dried by applying it in a W-shape to 6 rolls while feeding it into a 50 ℃ wind, and then introduced into a tenter dryer. The residual solvent amount of the film when peeled from the casting tape was 65 mass%, and the residual solvent amount of the film when introduced into the tenter was 18 mass%.

Both sides of the film fed to the tenter were held by clips and conveyed in the drying zone. The drying zone was as follows: the film was stretched in the width direction by supplying 120 ℃ dry air to the first half and 130 ℃ dry air to the second half.

The edges of the film were cut at the tenter exit. The film was further passed through a roll dryer formed of 8 rolls. In the roll dryer, dry air of 140 ℃ was blown. The dried film was cooled, and the end was knurled and wound. The film had a thickness of 50 μm and a residual solvent content of 0.3% by mass. The casting surface of the obtained film was used as a release surface.

Example 2

A fine particle dispersion having dispersed particles with an average particle diameter of 270nm (0.27 μm) was obtained in the same manner as in example 1 except that the dispersion conditions of the fine particle dispersion were changed, and a cement (D2) was obtained using the dispersion. Then, a film was formed in the same manner as in example 1, except that the blowing amount was adjusted so that the residual solvent amount at the time of peeling from the casting tape became 100 mass%.

Example 3

In casting, a film was formed in the same manner as in example 1 except that a 2-layer mold was used, and a triacetyl cellulose solution (a1) was spread on the casting belt surface as a release layer, and a dope (D1) used in example 1 as the upper layer (back layer) was spread. The thicknesses were as follows: the release layer was 10 μm and the back layer was 40 μm.

Example 4

(preparation of mucilage (D3))

Spherical silica particles (KE-P50 manufactured by Japan catalyst) having a particle size of 0.5 μm were added to the triacetylcellulose solution (A1) so that the particle content became 3000ppm in terms of solid content, and the mixture was stirred at 50 ℃ to obtain a slurry (D3). The resulting dope (D3) was filtered through a filter having a nominal pore size of 5 μm, and then defoamed.

A film was formed in the same manner as in example 3, except that the upper layer (back layer) was formed using the adhesive (D3) instead of the adhesive (D1).

Example 5

A film was formed in the same manner as in example 1, except that the dope (D3) prepared in example 4 was used instead of the dope (D1). The casting surface side of the obtained film was subjected to corona treatment, and a coating agent having the following composition was applied thereon as a release layer (surface-flattening coating layer), followed by drying in a heating oven at 150 ℃ for 3 minutes. The thickness of the coating was 2 μm.

10 parts by mass of a melamine crosslinked alkyl-modified alkyd resin (Hitachi Kasei Polymer Co., Ltd.; made by Ltd.: Tesfine 322: 40% in terms of solid content)

0.1 part by mass of p-toluenesulfonic acid (Hitachi Kasei Polymer Co., manufactured by Ltd.: Dryer 900)

40 parts by mass of a solvent (toluene/methyl ethyl ketone: 1/1 parts by mass)

The coating agent was filtered through a 2 μm filter and used.

Example 6

(preparation of mucilage (D4))

Spherical silica particles (KE-P250 manufactured by Japan catalyst) having a particle size of 2.5 μm were added to a triacetylcellulose solution (A1) so that the particle content was 1000ppm in terms of solid content, and the mixture was stirred at 50 ℃ to obtain a cement (D4). The resulting dope (D4) was filtered through a filter having a nominal pore size of 10 μm, and then defoamed.

A film was formed in the same manner as in example 3, except that the upper layer (back layer) was formed using a paste (D4) instead of the paste (D1) so that the thickness of the release layer was 25 μm and the thickness of the back layer was 25 μm.

The air used in the drying was filtered with a HEPA filter having a 95% cutoff diameter of 1 μm, and then filtered with a HEPA filter having a 99.9% cutoff diameter of 0.3 μm with high precision. Further, the coating of the coating liquid to the film was performed in an environment of class 1000. Hereinafter, the coating/drying process is performed under the same environment.

Example 7

On the back side of the film of example 4, Peltron C-4402 (antimony-doped tin oxide particles) having a solid content of 5% using MEK was applied as an antistatic layer (back surface planarization coating), and dried in a heating oven at 80 ℃ for 3 minutes. The thickness of the coating was 200 nm. The surface resistance was 7.3 × 10⁷Ω/□。

Comparative example 1

A film was formed in the same manner as in example 1, except that the dope (D3) prepared in example 4 was used instead of the dope (D1).

Table 1 shows the production conditions, characteristics, and evaluation results of the transfer films of examples 1 to 7 and comparative example 1.

[ Table 1]

As shown in table 1, in examples 1 to 7 in which the surface roughness of the release surface satisfied the characteristics of the present invention, the number of dead spots was significantly small in the evaluation of dead spots, and the occurrence of pin-hole-shaped and scratch-shaped light leakage was sufficiently suppressed. In examples 1 to 5 and 7, the surface roughness of the back surface was also suppressed to a low level, and therefore, in the evaluation of the dead spots, the dead spots 1 and 2 after the overlapping were also significantly reduced, and the occurrence of pin-hole-like or scratch-like light leakage was sufficiently suppressed. On the other hand, in comparative example 1 in which the particle size contained in the surface layer was too large and the surface roughness of the release surface was too large, the number of dead spots was significantly large in the evaluation of dead spots, and the generation of pin-hole-like or scratch-like light leakage could not be suppressed.

Table 1 does not show, but the in-plane retardation (Re) of the base films used in the examples and comparative examples was determined, and as a result, the base films were all 10nm or less and sufficiently low to a level at which the alignment state of the liquid crystal compound alignment layer could be checked by irradiating the transfer film with linearly polarized light in a state in which the liquid crystal compound alignment layer was laminated.

The specific procedure for measuring the in-plane retardation is as follows. That is, a rectangle of 4cm × 2cm was cut out from the base film used in the examples and comparative examples so that the flow direction was the long side, and the sample was used as a measurement sample. For this sample, the refractive index (flow direction nx, width direction ny) was measured by an Abbe refractometer (ATAGO CO., manufactured by LTD., NAR-4T, measurement wavelength 589 nm). The in-plane retardation (Re) was determined as the average of 5 points (center, both ends, and the intermediate portion between the center and the ends) measured in the width direction of the film by the product ((nx-ny). times.d) of the thickness d (nm) of the film.

Industrial applicability

The film for transferring an alignment layer of a liquid crystal compound of the present invention uses a film whose surface roughness is controlled to a specific range as a film for transferring a retardation layer or a polarizing layer, and therefore, the alignment state and the retardation of the liquid crystal compound in the retardation layer or the polarizing layer can be designed, and a retardation layer or a polarizing layer (alignment layer of a liquid crystal compound) in which the occurrence of defective spots such as pinholes is reduced can be formed. Therefore, according to the present invention, a retardation layer laminated polarizing plate such as a circular polarizing plate can be stably manufactured with high quality.

Claims

1. A cellulose film for transferring an alignment layer of a liquid crystal compound to an object, wherein the surface roughness (SRa) of a release surface of the film is 1nm or more and 30nm or less.

2. The film for transferring an alignment layer of a liquid crystal compound according to claim 1, wherein the release surface of the film has a ten-point surface roughness (SRz) of 5nm or more and 200nm or less.

3. A laminate for transfer printing of an alignment layer of a liquid crystal compound, which comprises a laminate comprising an alignment layer of a liquid crystal compound and a film, wherein the film is the film according to claim 1 or 2.

4. A method for manufacturing a liquid crystal compound oriented layer laminated polarizing plate, comprising the steps of: a step of forming an intermediate laminate by laminating a polarizing plate to the liquid crystal compound alignment layer of the laminate according to claim 3; and a step of peeling the film from the intermediate laminate.