JP2019082740A - Retardation film - Google Patents

Abstract

To provide a retardation film having an alignment film of new composition.SOLUTION: A retardation film 1 includes a substrate 11, an alignment film 12, and a retardation layer 13, which are laminated in this order. The alignment film 12 is composed of a mixed material of a UV curable resin and a thermosetting resin. In the alignment film 12 of the retardation film 1, the UV curable resin and the thermosetting resin exist in phase separation, and particularly the thermosetting resin is localized at ab interface side between the alignment film 12 and the retardation layer 13.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a retardation film, and to a retardation film having an alignment film of a novel constitution.

  In recent years, a retardation film applied to a flat panel display or the like has been provided which imparts a desired retardation to transmitted light by a retardation layer to secure desired optical characteristics (see, for example, Patent Document 1) ). In this type of retardation film, an alignment film is produced on the surface of a substrate made of a transparent film or the like, and the liquid crystal material is cured in a state where the liquid crystal material is aligned by the alignment regulating force of this alignment film. Although liquid crystal materials applied to such retardation layers usually have positive wavelength dispersion characteristics, in recent years, liquid crystal materials having reverse dispersion characteristics have been proposed (see, for example, Patent Documents 2 and 3). . Here, the inverse dispersion characteristic is a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller toward the shorter wavelength side, and more specifically, the retardation (R450) at the wavelength of 450 nm and the retardation (R550) at the wavelength of 550 nm The relationship of is R450 <R550.

  Further, in the image display panel, methods have been proposed to improve various optical characteristics such as viewing angle characteristics and color tones by using A plate, C plate, etc. For example, Patent Document 4 discloses A plate, A device for optical compensation of an IPS liquid crystal display device using a C plate has been proposed. Here, the optical compensation is a configuration for reducing light leakage in the oblique direction from the linear polarizing plate at the time of black display. The C plate is represented by nx = ny <nz or nx = ny> nz, nx = ny <nz is a positive C plate, and nx = ny> nz is a negative C plate. The A plate is represented by nx> ny = nz or nz = nx> ny, nx> ny = nz is a positive A plate, and nz = nx> ny is a negative A plate. In addition, nx and ny (nx ny ny) are refractive indexes in the in-plane direction, and nz is a refractive index in the thickness direction.

  Among these, the positive A plate is manufactured by using positive liquid crystal material by positive wavelength dispersion property and liquid crystal material by reverse dispersion property applied to the retardation layer, respectively by positive wavelength dispersion property and reverse dispersion property. be able to. In addition, a positive C plate can be produced by applying a coating solution of a liquid crystal material for so-called C plate and drying and curing it. In vertical alignment (VA) liquid crystal displays and the like, the liquid crystal material is aligned in the vertical direction by the vertical alignment film, and various devices for the vertical alignment film for VA liquid crystal have been proposed.

  Now, in such a retardation film, it is important to align the molecules of the liquid crystal compound in the retardation layer reliably and strictly in a predetermined direction. On the other hand, in one aspect, it is important to control the thickness of the alignment film appropriately, so that the film thickness of the alignment film can be appropriately controlled, and the liquid crystal compound in the retardation layer is effectively exerting an alignment regulating force. There is a need for a retardation film having an alignment film of a novel constitution that can be used.

Japanese Patent Application Laid-Open No. 10-68816 U.S. Pat. No. 8,119,026 Japanese Patent Publication No. 2010-522892 Japanese Patent Application Publication No. 2006-520008 JP 2005-49865 A JP 2007-156234 A

  An object of the present invention is to provide a retardation film having an alignment film of a novel constitution. And, in one aspect, it is an object of the present invention to provide a retardation film which can appropriately control the film thickness of the alignment film and can effectively exert the alignment control power to the liquid crystal compound in the retardation layer. .

  (1) In the present invention, the base material, the alignment film, and the retardation layer are laminated in this order, and the alignment film is made of a mixed material of an ultraviolet curable resin and a thermosetting resin. Retardation film characterized by

  (2) The present invention is the retardation film according to the invention (1), characterized in that, in the alignment film, the ultraviolet curable resin and the thermosetting resin are separated into phases.

  (3) The present invention is the retardation film according to the invention (1) or (2), wherein the thermosetting resin contained in the alignment film exhibits vertical alignment.

  (4) In the invention according to any one of (1) to (3), the base material is subjected to antiblocking treatment to have unevenness, and the film thickness of the alignment film is the above-mentioned. The retardation film is characterized in that the size is equal to or larger than the height of the convex portion on the surface of the base material.

  (5) In the invention according to any one of (1) to (4), the retardation film is a transfer laminate for an optical film having a transfer layer, and the alignment film and the retardation layer The retardation film is characterized in that the base material and the alignment film are peeled off with the interface of (1) as a peeling interface.

  (6) Further, the present invention is the retardation film characterized in that, in the invention of (5), the transfer layer is transferred to an optical functional layer giving a retardation of 1⁄4 wavelength.

  According to the present invention, it is possible to provide a retardation film having an alignment film of a novel constitution. In one aspect, the thickness of the alignment film can be appropriately controlled, and the alignment control force can be effectively exerted on the liquid crystal compound in the retardation layer.

It is a cross-sectional schematic diagram which shows an example of retardation film. When a retardation film in which a liquid crystal layer is laminated with a liquid crystal layer and a phase difference film formed by laminating a PET base material, a mixed material of a UV curable resin and a thermosetting resin, is peeled off at the interface between the alignment film and the liquid crystal layer It is a graph which shows the analysis result by the X-ray photoelectron spectroscopy in the liquid crystal layer side interface (A) and the alignment film side interface (B). (A) shows the reference peak of a vertical alignment thermosetting material, (B) is a graph which shows the reference peak of UV curable material. It is a flowchart which shows the flow of the preparation processes of retardation film. It is a figure for demonstrating the flow which produces an optical film by a transfer method, using retardation film as a transfer laminated body for optical films.

Hereinafter, specific embodiments of the retardation film according to the present invention (hereinafter, referred to as "the present embodiment") will be described in detail in the following order. In addition, this invention is not limited to the following embodiment, A various change is possible in the range which does not change the summary of this invention.
1. Composition of retardation film About alignment film 3. Production method of retardation film 4. Application as a transfer laminate for optical films

<< 1. Composition of retardation film >>
FIG. 1 is a cross-sectional view schematically showing an example of a retardation film 1 according to the present embodiment. As shown in FIG. 1, the retardation film 1 is formed by laminating a substrate 11 made of a transparent film material, an alignment film 12, and a retardation layer (liquid crystal layer) 13 in this order.

  The retardation film 1 according to the present embodiment is characterized in that the alignment film 12 stacked on the substrate 11 is made of a mixed material of an ultraviolet curable resin and a thermosetting resin. In such a retardation film 1, the ultraviolet curable resin and the thermosetting resin are phase separated and present in the alignment film 12. Specifically, in the alignment film 12, the thermosetting resin is unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13.

  In such a retardation film 1 having a novel alignment film 12 composed of a mixed material of two different resins of an ultraviolet curable resin and a thermosetting resin, the ultraviolet curable resin in the alignment film 12 The following phase difference film can be obtained, for example, by utilizing the property of phase separation of the thermosetting resin and the thermosetting resin. That is, although it will be described in detail later, as one example, the alignment film is a vertical alignment film for effectively homeotropically aligning the molecular axes of the molecules of the liquid crystal compound in the retardation layer, and an alignment having a predetermined thickness. It is a film | membrane, It can be set as the retardation film which can suppress generation | occurrence | production of the repelling of the coating liquid (coating liquid for retardation layer formation) at the time of forming the retardation layer 13 effectively.

  Hereinafter, the configuration of the retardation film 1 according to the present embodiment will be described in order.

<1-1. Base material>
The substrate 11 is a transparent film material having a function of supporting the alignment film 12 and formed to be long. For example, when the retardation film 1 is used for transfer, the substrate 11 functions as a releasable support and supports the alignment layer 12 and the retardation layer 13 for transfer, as well as the surface thereof. It is preferable that the adhesive has a releasable adhesive strength.

  The film material constituting the substrate 11 is, for example, polyester such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyarylate, etc., polyolefin such as polyethylene, polypropylene, polymethylpentene, etc., triacetyl cellulose, acrylic type Polymer etc. can be mentioned. The base material 11 may be a single layer made of these materials, or may be a laminate in which two or more materials are laminated. In the case of a laminate of a plurality of layers, layers having the same composition may be laminated.

  Although it does not specifically limit as thickness of the base material 11, For example, it is preferable to set it as the range of 20 micrometers-200 micrometers. If the thickness of the substrate 11 is less than 20 μm, the minimum required self-supporting property may not be imparted as a transfer laminate for an optical film. On the other hand, if the thickness exceeds 200 μm, and the transfer laminate for an optical film has a long shape, the transfer laminate for a long optical film is cut and processed, and the transfer laminate for an optical film for a single wafer In doing so, cutting waste may increase and wear of the cutting blade may be accelerated.

  Here, the base material 11 may be subjected to various blocking prevention treatments. Examples of the antiblocking process include an easy adhesion process, a process of preventing blocking by kneading a filler or the like, and a knurling process. By applying such antiblocking treatment to the base material 11, sticking of the base materials at the time of winding up the base material 11, so-called blocking can be effectively prevented, and the retardation film can be produced with high productivity. It becomes possible to manufacture.

  When the base material 11 is subjected to the antiblocking treatment as described above, irregularities are formed on the surface of the base material 11. The height (size) of the projections on the surface of the base material 11 subjected to the antiblocking treatment is not particularly limited, but is generally about 0.5 μm to 1.5 μm.

<1-2. Alignment film>
The alignment film 12 is obtained by applying and curing the composition for alignment film (alignment film composition) on the base material 11 mentioned above, and expresses alignment control force. Here, when the layer (retardation layer 13) made of a polymerizable liquid crystal compound (liquid crystal material) is formed on the alignment film 12, the alignment regulating force is a function of aligning (orienting) the liquid crystal compound in a predetermined direction. Say

  The alignment film 12 is not particularly limited, but can be, for example, a vertical alignment film in which the molecular axes of the molecules of the liquid crystal compound in the retardation layer 13 are homeotropically aligned (vertically aligned). As the vertical alignment film, various vertical alignment films applied to a VA liquid crystal display device or the like can be applied. For example, a polyimide alignment film, an alignment film of LB film, etc. can be applied.

  As described above, the alignment film 12 is not limited to the vertical alignment film, and may be an alignment film in which the molecular axes of the liquid crystal compound are homogeneously aligned (horizontal alignment), and the molecular axes of the liquid crystal compound The alignment film may be a hybrid alignment (tilt alignment).

  The solvent (dilution solvent) used in the alignment film composition is not particularly limited as long as it can dissolve the alignment material to a desired concentration. For example, hydrocarbon solvents such as benzene and hexane, methyl ethyl ketone, Ketone solvents such as methyl isobutyl ketone and cyclohexanone (CHN), ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane and propylene glycol monoethyl ether (PGME), halogenated alkyl solvents such as chloroform and dichloromethane, methyl acetate Ester solvents such as ethyl acetate, butyl acetate and propylene glycol monomethyl ether acetate (PGMEA), amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, Methanol, ethanol can be exemplified an alcohol solvent such as isopropyl alcohol. The solvent may be of one type or a mixed solvent of two or more types of solvents.

  Such an alignment film 12 is produced by applying a coating solution of an alignment film composition containing the above-described material to the substrate 11 and drying it, and then performing a predetermined curing treatment. The alignment film 12 is constituted by the cured product produced in this manner.

  Here, in the retardation film 1 according to the present embodiment, the alignment film 12 is characterized by being made of a mixed material of an ultraviolet curable resin and a thermosetting resin. As described later in detail, according to the retardation film 1 having the alignment film 12 made of such a mixed material of an ultraviolet curable resin and a thermosetting resin, the ultraviolet curing is performed in the film. The resin and the thermosetting resin are separated into phases, and in particular, the thermosetting resin is unevenly distributed on the interface between the alignment film 12 and the retardation layer 13.

<1-3. Retardation Layer (Liquid Crystal Layer)>
The retardation layer (liquid crystal layer) 13 contains a polymerizable liquid crystal composition. The polymerizable liquid crystal composition contains a liquid crystal compound (rod-like compound) having liquid crystallinity and having a polymerizable functional group in the molecule.

  The liquid crystal compound has refractive index anisotropy, and has a function of imparting desired retardation by arranging regularly. Examples of the liquid crystal compound include materials exhibiting a liquid crystal phase such as a nematic phase and a smectic phase, but the nematic phase is easy to arrange regularly as compared with liquid crystal compounds showing other liquid crystal phases. It is preferable to use a material that exhibits liquid crystallinity. It is preferable that it is a material which has a spacer in mesogen both ends as a liquid crystal compound which shows a nematic phase. The liquid crystal compound having spacers at both ends of the mesogen is excellent in flexibility, so that the retardation film 1 can be made excellent in transparency.

  Further, for example, in the case where the above-mentioned alignment film 12 is formed of a vertical alignment film and homeotropic alignment of the liquid crystal compound is made, it is particularly a homeotropic liquid crystal material which can form homeotropic alignment as a liquid crystal compound. It is not limited. Examples of homeotropic liquid crystal materials include those capable of forming homeotropic alignment without using a vertical alignment film, and those capable of forming homeotropic alignment by using a vertical alignment film. Either can be used suitably.

  The liquid crystal compound is a polymerizable liquid crystal compound having a polymerizable functional group in the molecule as described above. By having a polymerizable functional group, it becomes possible to polymerize and fix the liquid crystal compound, so that it is excellent in the alignment stability and hardly changes with time due to retardation. The polymerizable liquid crystal compound more preferably has a polymerizable functional group capable of three-dimensionally crosslinking in the molecule. By having a three-dimensionally crosslinkable polymerizable functional group, the sequence stability can be further enhanced. Note that “three-dimensional crosslinking” refers to polymerizing liquid crystal molecules three-dimensionally with one another to form a network (network) structure.

  Examples of the polymerizable functional group include those which can be polymerized by the action of ionizing radiation such as ultraviolet light and electron beam, or heat. Examples of these polymerizable functional groups include radically polymerizable functional groups and cationically polymerizable functional groups. Representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenic unsaturated double bond, and examples thereof include vinyl groups with and without substituents, acrylate groups (acryloyl Group, a methacryloyl group, an acryloyloxy group, a generic term including a methacryloyloxy group) and the like. Moreover, an epoxy group etc. are mentioned as a specific example of a cationically polymerizable functional group. In addition, as a polymerizable functional group, an isocyanate group, unsaturated triple bond, etc. are mentioned. Among them, a functional group having an ethylenically unsaturated double bond is preferably used from the viewpoint of the process.

  The amount of the polymerizable liquid crystal compound is not particularly limited as long as the viscosity of the retardation layer forming coating liquid (liquid crystal composition) can be adjusted to a desired value according to the coating method applied on the alignment film 12. For example, the amount in the liquid crystal composition can be in the range of about 5 parts by mass to 40 parts by mass. In addition, a polymeric liquid crystal compound can be used individually by 1 type or in mixture of 2 or more types.

  The liquid crystal compound described above is usually dissolved in a solvent (dilution solvent). The solvent is not particularly limited as long as it can uniformly disperse the liquid crystal compound etc. For example, hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone (CHN) Solvents, ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, propylene glycol monoethyl ether (PGME), halogenated alkyl solvents such as chloroform and dichloromethane, methyl acetate, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate (PGMEA) ester solvents, amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anone solvents such as cyclohexane, methanol, ethanol, isopropyl It can be exemplified an alcohol solvent such as alcohol, but is not limited thereto. The solvent may be used alone or in combination of two or more.

  The amount of the solvent is not particularly limited, and may be, for example, about 66 parts by mass to 900 parts by mass with respect to 100 parts by mass of the liquid crystal compound. If the amount of the solvent is less than 66 parts by mass, the liquid crystal compound may not be uniformly dissolved, which is not preferable. On the other hand, when it exceeds 900 parts by mass, a part of the solvent remains, and there is a possibility that the reliability may be reduced, and a possibility that uniform application can not be performed is not preferable.

  In addition, the liquid crystal composition may contain other compounds as needed as long as it does not impair the alignment order of the liquid crystal compound described above. For example, polymerization inhibitors, plasticizers, surfactants, and silane coupling agents can be mentioned.

  The thickness of the retardation layer 13 formed by coating the liquid crystal composition as described above on the alignment film 12 is not particularly limited, but in order to obtain appropriate alignment performance, 500 nm It is preferable that it is about 2000 nm.

<< 2. About alignment film >>
(Configuration of alignment film 12)
As described above, in the retardation film 1 according to the present embodiment, the alignment film 12 is made of a mixed material of the ultraviolet curable resin and the thermosetting resin.

  In the alignment film 12 made of such a mixed material of an ultraviolet curable resin and a thermosetting resin, the ultraviolet curable resin and the thermosetting resin are phase-separated in the film of the alignment film 12. Come to exist. More specifically, the ultraviolet curable resin is phase separated on the substrate 11 side, and the thermosetting resin is phase separated on the interface side of the alignment film 12 and the retardation layer 13. It is considered that this is because the thermosetting resin migrates to the atmosphere side (compared to the hydrophobicity) rather than the base material 11 side, which is relatively hydrophilic, to be easily stabilized.

  Here, in FIG. 2, a retardation film in which a retardation film (liquid crystal layer) is laminated in this order on an alignment film made of a PET substrate, a mixed material of an ultraviolet curable resin and a thermosetting resin, and The results of analysis by X-ray photoelectron spectroscopy (XPS) at each of the liquid crystal layer side interface and the alignment film side interface when peeled at the interface between the alignment film and the liquid crystal layer are shown. Specifically, in this XPS analysis, an ultraviolet (UV) curable material (referred to as "UV curable material (a)") and a thermosetting material ("thermocurable material (b)" exhibiting vertical orientation) And a mixture of materials mixed at a weight ratio of 1: 100 is applied to the PET substrate so that the film thickness of the alignment film is 3 μm. The alignment film was formed by curing by irradiation with ultraviolet light.

  As shown in the results of XPS analysis in FIG. 2, a thermosetting material (vertically oriented) ((A) in the liquid crystal layer side interface and (B) in the alignment film side interface) It can be seen that the peak in which b) is the main component is detected. FIG. 3 (A) shows the reference peak of the UV curable material (a), and FIG. 3 (B) shows the reference peak of the thermosetting material (b) showing vertical orientation.

  From this, in the alignment film composed of the mixed material of the ultraviolet curable resin and the thermosetting resin, the ultraviolet curable resin and the thermosetting resin are phase separated in the film, and the thermosetting resin is It can be seen that localized distribution occurs on the interface side between the liquid crystal layer and the alignment film.

(Example of use of retardation film 1 having alignment film 12)
By the way, generally, in a retardation film, various blocking prevention processing for preventing blocking etc. is given to the substrate as it is for winding up. However, conventionally, when a retardation film is formed using a substrate that has been subjected to such antiblocking treatment, irregularities are formed on the substrate surface by the antiblocking treatment, and an alignment film is coated on the substrate. If an alignment layer is to be formed, unevenness is also caused on the surface of the alignment layer (contact surface with the retardation layer) due to the convex portion on the surface of the base material. Then, when a coating solution for forming a retardation layer containing a liquid crystal composition is applied on the alignment layer having such unevenness formed and the surface roughness (Ra) increased, the unevenness on the surface of the alignment film is followed. As a result, a so-called "repelling" is generated in which the coating solution for forming a retardation layer can not be uniformly coated on the alignment layer and the alignment layer is exposed. The occurrence of coating defects such as repelling reduces the yield of a retardation film, and when a polarizing plate is laminated on an optical film in which repelling has occurred and the appearance inspection is conducted, the retardation of the portion where repelling occurs is small. Cause defects and cause appearance defects.

  In order to address such conventional problems, in the present embodiment, the alignment film 12 made of the mixed material of the ultraviolet curable resin and the thermosetting resin described above is subjected to the antiblocking process. It forms so that it may become thickness (film thickness) more than the height of the convex part of the surface of the base material 11 mentioned above. As described above, by forming the alignment film 12 having a film thickness equal to or greater than the height of the convex portion on the surface of the substrate 11, the surface roughness of the alignment film 12 resulting from the unevenness of the substrate 11 is reduced. Can. That is, by forming the alignment layer 12 having a predetermined film thickness or more, the unevenness of the substrate 11 can be canceled as the alignment film 12 is embedded. Thereby, the generation of repelling during coating of the liquid crystal composition on the alignment film 12 can be effectively suppressed.

  Here, in the retardation film, it is required to reliably align the molecules of the liquid crystal compound in the retardation layer in a desired direction, and for example, the liquid crystal compound is homeotropically (vertically aligned) reliably and strictly. Is required. The alignment direction of the molecules of the liquid crystal compound is not limited to the vertical alignment, and may be homogeneous alignment (horizontal alignment) or hybrid alignment (tilt alignment). However, in order to form an alignment film using a thermosetting resin that exhibits the orientation in the desired direction in order to align the liquid crystal compound in the desired direction, from the viewpoint of high viscosity of the thermosetting resin, etc. The film thickness of the alignment film which can be formed is limited only by the thermosetting resin, and a sufficiently thick alignment film can not be formed. From this, in order to effectively suppress the generation of repelling when forming the retardation layer as described above, in the conventional retardation film, the film thickness and the thickness of the convex portion on the surface of the base material Can not be effectively formed.

  In this respect, in the retardation film 1 according to the present embodiment, as described above, generation of repelling is caused by having the alignment film 12 made of the mixed material of the ultraviolet curable resin and the thermosetting resin. While being effectively suppressed, it is possible to reliably align the molecules of the liquid crystal compound in the retardation layer in a predetermined direction.

  That is, for example, the thermosetting resin that forms the alignment film 12 is a thermosetting resin that exhibits vertical alignment that causes the molecular axes of the molecules of the liquid crystal compound in the retardation layer 13 to be homeotropically aligned. In the retardation film 1, by forming the alignment film 12 with a mixed material of an ultraviolet-curable resin and a thermosetting resin exhibiting such vertical alignment, the ultraviolet-curable resin and the heat in the alignment film 12 are used. The curable resin is separated from the phase to be present, and in particular, the thermosetting resin exhibiting vertical alignment property is localized at the interface between the alignment film 12 and the retardation layer 13. On the other hand, since the alignment film 12 is made of a mixed material of an ultraviolet curable resin and a thermosetting resin, the ultraviolet curable resin (on the side of the substrate 11 in the alignment film 12 exhibiting vertical alignment) The thickness of the alignment film 12 can be increased by the amount of the separated resin. That is, the thermosetting resin exhibiting vertical alignment, which is unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13, effectively exerts an alignment control force on the liquid crystal compound, and the alignment film by the ultraviolet curable resin. The film thickness of 12 can be controlled to a predetermined thickness. For example, an alignment film having a film thickness equal to or greater than the height of the convex portion on the surface of the base material can be effectively formed.

  By this, it becomes possible to effectively suppress the generation of repelling during liquid crystal composition coating as described above, and at the same time, by the thermosetting resin showing the vertical alignment property localized on the retardation layer 13 side, The liquid crystal compound in the liquid crystal layer formed on the alignment film 12 can be homeotropically aligned with certainty.

  In addition, as an application example of the retardation film 1 which has such an alignment film 12, it illustrates only as a certain aspect, It is not limited to this.

(UV-curable resin material)
The ultraviolet curable resin material constituting the alignment film 12 is not particularly limited as long as it can be cured by irradiation of ultraviolet rays, but, for example, monomers such as acrylates and methacrylates, prepolymers, or these It is possible to use one obtained by adding a photopolymerization initiator such as acetophenone, benzophenone or aromatic iodonium to the mixture of

  More specifically, for example, trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentameric Resins such as erythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate and the like can be used.

(Thermosetting resin material)
As described above, the thermosetting resin constituting the alignment film 12 is a component that becomes unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13 in the alignment film 12. Therefore, the thermosetting resin affects the orientation of the molecules of the liquid crystal compound in the retardation layer 13 and the like. From this, the thermosetting resin is not particularly limited as long as it can be cured by heat, but in order to exert the alignment control force for aligning the liquid crystal compound of the retardation layer 13 in a desired direction. It is preferred to select the most suitable resin.

  For example, in order to vertically align the liquid crystal compound, it is preferable to select a thermosetting resin exhibiting vertical orientation. Specifically, the thermosetting resin exhibiting vertical alignment property is not particularly limited as long as it can be cured by heat to homeotropically align the liquid crystal compound. For example, thermosetting polyimide, long chain alkyl, etc. Examples include polyamic acids having a group or an alicyclic structure in the side chain. Further, as a thermosetting resin material exhibiting vertical orientation, for example, lecithin, a silane surfactant, a titanate surfactant, a pyridinium salt polymer surfactant, n-, together with the above-mentioned thermosetting resin Silane coupling agents such as octadecyltriethoxysilane can also be mixed.

  The orientation direction of the molecules of the liquid crystal compound is not limited to the vertical orientation, and may be homogeneous orientation (horizontal orientation) or hybrid orientation (tilt orientation), and exhibits orientation for orienting in the desired direction. It is preferable to select a thermosetting resin.

(Mixing ratio of UV curable resin material and thermosetting resin material)
The mixing ratio of the ultraviolet curable resin material and the thermosetting resin material in the mixed material constituting the alignment film 12 is not particularly limited, but a thermosetting ratio with respect to the ultraviolet curable resin material 100 in weight ratio It is preferable to mix the resin material in a ratio of 0.1 to 10, and more preferable to mix in a ratio of 1 to 5.

  With respect to the mixing ratio, when the mixing amount of the thermosetting resin material is a ratio of less than 0.1 with respect to the ultraviolet curable resin material 100 in weight ratio, the alignment control force in the alignment film becomes weak, and the retardation layer There is a possibility that the liquid crystal compound at 13 can not be sufficiently oriented in a predetermined direction. On the other hand, when the mixing amount of the thermosetting resin material is a ratio by weight ratio exceeding 10 with respect to the ultraviolet curable resin material 100, the mixed material becomes turbid and gelatinizes, effectively on the substrate It may not be able to apply | coat and can not form the alignment film which exhibits the desired effect.

<< 3. Production method of retardation film >>
Next, a method of manufacturing the retardation film 1 will be described. FIG. 4 is a flow diagram showing the flow of the manufacturing process of the retardation film 1. In the following description of the manufacturing method, although the case where the alignment film 12 is formed of a vertical alignment film is described as an example, the present invention is not limited thereto.

  As shown in FIG. 4, in the production of the retardation film 1, first, a base film 11 such as a PET film is provided from a long film wound on a roll (S 1).

  Next, in the alignment film forming step (S2), a coating liquid for forming an alignment film (alignment film composition) is applied onto the substrate 11 drawn out from the roll, dried, and then subjected to a curing treatment. Thus, the alignment film 12 is formed on the substrate 11. At this time, in the present embodiment, after an alignment film composition composed of a mixed material of an ultraviolet curable resin and a thermosetting resin is applied on the substrate 11 and subjected to a drying process, ultraviolet light is applied. Is cured to form an alignment film 12. Note that the thermosetting resin in the mixed material constituting the alignment film 12 can be effectively cured by the heat accompanying the ultraviolet irradiation.

  Next, in the retardation layer forming step (S3), a coating solution of a liquid crystal composition containing a liquid crystal compound (coating solution for forming a retardation layer) is applied onto the alignment film 12. Thereafter, it is dried and cured by irradiation with ultraviolet light or the like to form a retardation layer (liquid crystal layer) 13. In addition, prior to the ultraviolet irradiation process, a leveling process may be performed to make the layer thickness of the retardation layer 13 uniform.

  Here, in the present embodiment, as described above, the alignment film 12 is formed by applying the alignment film composition formed of a mixed material of the ultraviolet curable resin and the thermosetting resin on the substrate 11. Form. That is, the alignment film 12 is made of a mixed material of an ultraviolet curable resin and a thermosetting resin. In such an alignment film 12, the ultraviolet curable resin and the thermosetting resin are separated in phase in the film, and in particular, the thermosetting resin is an alignment film 12 and a retardation layer 13. It becomes unevenly distributed on the interface side with

  In this manner, a laminate film in which the base material 11 / alignment film 12 / retardation layer 13 are laminated in this order is manufactured, and the obtained film is wound by a take-up reel or the like, and then the desired size is obtained. Perform cutting processing to cut into pieces. The retardation film 1 is produced through such a process.

  In addition, it does not specifically limit as a coating method of the alignment film composition on the base material 11, and a coating method of the coating liquid for retardation layer formation on the alignment film 12, For example, a diecoat Method, gravure coating method, reverse coating method, knife coating method, dip coating method, spray coating method, air knife coating method, spin coating method, roll coating method, printing method, immersion pulling method, curtain coating method, casting method, bar A coating method, an extrusion coating method, an E-type coating method or the like can be used.

<< 4. Application as a transfer laminate for optical films »
An optical film applied to a flat panel display or the like uses, for example, an optical film transfer laminate having a transfer layer to be transferred to an optical functional layer such as a linear polarizing plate having a function as a linear polarizing plate. It can be produced by the transfer method. In the transfer method, for example, when a desired layer is formed on a predetermined substrate, the desired layer is not formed directly on the substrate, but once the support has been released (support (support (A base material) on which the layer is releasably laminated to produce a transfer laminate, and the layer formed on the support is finally laminated according to the process, demand, etc. This is a method of forming a desired layer on a predetermined substrate by adhering and laminating on a (transferred substrate) and then peeling off the support. By producing an optical film by such a transfer method, it is considered that an optical film having a small overall thickness can be provided. In addition, the optical film produced by the transfer method is described, for example in patent document 5 and patent document 6.

  The retardation film 1 which concerns on this Embodiment can be applied as an optical film transfer laminated body used when producing an optical film using a transfer method. As described above, the transfer laminate for an optical film, as described above, the retardation layer or the like constituting the retardation film is a substrate having releasability (a releasable substrate) or any other substrate from an alignment film. Is used to form a retardation layer on any of the substrates. In the transfer laminate for an optical film, for example, 1/1 of transmitted light comprising an optical functional layer of a linear polarization plate, a reverse dispersion stretched film, or a laminate of a λ / 2 retardation plate and a λ / 4 retardation plate, etc. The transfer layer can be transferred by bonding to an optical functional layer or the like that imparts a phase difference of 4 wavelengths. In addition, in such a transfer laminate for an optical film, the interface between the alignment film 12 and the retardation layer 13 is a peeling interface, for example, although not particularly limited, in the production of the optical film, the transfer laminate for an optical film is After transferring the transfer layer (retardation layer 13) to a substrate such as a reverse dispersion stretched film, the substrate 11 and the alignment film 12 are peeled off from the retardation layer 13.

  More specifically, a method for producing an optical film by a transfer method using the retardation film 1 according to the present embodiment as a transfer laminate for an optical film will be described. In addition, below, the transfer laminated body for optical films is demonstrated as "transfer laminated body 1A for optical films."

  FIG. 5 shows an optical film by transferring the transfer layer of the transfer laminate 1A for optical film to an optical functional layer that imparts a retardation of 1⁄4 wavelength to transmitted light using the transfer laminate 1A for optical film It is a figure which shows the flow of the process at the time of producing. In addition, this FIG. 5 is a figure which shows the cross section of a film, and is a figure which shows the flow of a process, showing about the layer structure of the film in each process. In addition, the layer structure of the film is not limited to this.

  First, as shown in FIG. 5A, an alignment film 12 made of, for example, a vertical alignment film is formed on a substrate 11 made of a PET film or the like, and a phase difference containing a liquid crystal composition on the alignment film 12 The coating liquid for layer formation is coated to form a retardation layer (liquid crystal layer) 13, and a transfer laminate 1A for an optical film is produced. Here, as described above, in the preparation of the optical film transfer laminate 1A, the alignment film 12 is configured using the alignment film composition made of a mixed material of the ultraviolet curable resin and the thermosetting resin. There is.

  Next, as shown in FIG. 5B, an adhesive layer 21 containing, for example, a UV adhesive is formed on the retardation layer 13 of the produced transfer laminate 1A for an optical film, and the adhesive layer 21 is formed. For example, the reverse dispersion stretched film 22 is formed to transfer the transfer laminate 1A for an optical film.

  As the adhesive layer 21, various adhesives such as an ultraviolet curable resin, a thermosetting resin, a pressure sensitive adhesive and the like can be widely applied. Among them, ultraviolet rays (UV) from the viewpoint of reducing the overall thickness It is preferable to apply a curable resin to form a UV adhesive layer, and in this case, an adhesive layer having a thickness of about 1 μm can be produced. In addition, an adhesive layer may be applied to the adhesive layer 21.

  Moreover, it is not particularly limited as long as it plays a role as a retardation layer for a quarter wave plate, but for example, a stretched film having reverse dispersion characteristics (hereinafter, also referred to as "reverse dispersed stretched film 22") Can be formed. The reverse dispersion stretched film 22 is formed of, for example, a PC (polycarbonate) film which is stretched in the longitudinal direction or the transverse direction, or obliquely stretched in a desired direction, and the slow axis is relative to the absorption axis of the linear polarizing plate It is arranged to form an angle of about 45 degrees, and plays a role as a retardation layer for a quarter-wave plate that imparts a quarter wavelength retardation to transmitted light. By using such an inverse dispersion stretched film 22, for example, the configurations of the substrate, the resin layer for 1⁄4 wavelength plate, and the alignment film for 1⁄4 wavelength plate can be omitted, so that the entire optical film Layer thickness can be reduced.

  When the reverse dispersion stretched film 22 is laminated on the optical film transfer laminate 1A and transferred, as shown in FIG. 5C, the base 11 and the alignment film 12 of the optical film transfer laminate 1A are peeled off next. Do. The transfer laminate 1A for an optical film has a role as a releasable support in order to transfer the transfer layer (retardation layer 13) to another substrate (polymer film etc.) as described above. 11 and the alignment film 12 are peeled off. Peeling of the substrate 11 and the alignment film 12 may be performed after laminating a linear polarizing plate described later.

  Then, when the base material 11 and the alignment film 12 of the optical film transfer laminate 1A are peeled off, next, as shown in FIG. 5D, a linear polarizing plate provided with a pressure-sensitive adhesive layer 31 is laminated.

  As the linear polarizing plate, after the lower surface side of the base material 34 made of a transparent film such as TAC (triacetyl cellulose) is saponified, an optical function layer is disposed. The base material 34 may be methyl poly (meth) acrylate, butyl poly (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, methyl (meth) acrylate-styrene copolymer It is also possible to apply a resin such as an acrylic resin such as coalesced, a glass such as soda glass, potassium glass, lead glass, quartz glass or the like.

  The optical function layer is a portion responsible for the optical function as a linear polarizing plate, and for example, a layer in which a polarizer 33 and a transparent protective film (base material) 32 made of an acrylic resin or the like are sequentially laminated is used. Can. Such a linear polarizing plate is attached to the reverse dispersion stretched film 22 via the pressure-sensitive adhesive layer 31.

  By using the retardation film 1 as a transfer laminate for an optical film based on the steps as described above, an optical film can be easily produced based on a transfer method.

  As described above, in the optical film transfer laminate 1A, the alignment film 12 formed of the vertical alignment film is provided, and the optical film transfer laminate 1A is reversed with the adhesive layer 21 on the retardation layer 13 of the optical film transfer laminate 1A. By laminating the dispersion stretched film 22 and providing a linear polarizing plate provided with the polarizer 33 sandwiched between the substrates 32 and 34 made of transparent film on the reverse dispersion stretched film 22, it is easy and high productivity. Thus, it is possible to obtain an optical film provided with a positive C plate by reverse dispersion characteristics.

  In the above example, the interface between the alignment film 12 and the retardation layer 13 is taken as the peeling interface, and the substrate 11 and the alignment film 12 are peeled off after transfer as an example, but the peeling interface is limited to this. Instead of using the interface between the substrate 11 and the alignment film 12 as a peeling interface, only the substrate 11 may be peeled off after transfer to transfer the alignment film 12 and the retardation layer 13 to another substrate.

1 Retardation film 1A Transfer laminate for optical film 11 Substrate 12 Alignment film 13 Retardation layer (liquid crystal layer)

Claims (1)

A substrate, an alignment film, and a retardation layer are laminated in this order,
The retardation film characterized in that the alignment film is made of a mixed material of an ultraviolet curable resin and a thermosetting resin.

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