JP6607329B2 - Retardation film - Google Patents

Description

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

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

  In addition, in the image display panel, a method for improving various optical characteristics such as viewing angle characteristics and color using an A plate, a C plate, etc. has been proposed. 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 that reduces light leakage in an oblique direction from the linear polarizing plate during black display. The C plate is represented by nx = ny <nz or nx = ny> nz, where 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, where nx> ny = nz is a positive A plate and nz = nx> ny is a negative A plate. Note that nx and ny (nx ≧ 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 produced with a positive chromatic dispersion characteristic and a reverse dispersion characteristic using a liquid crystal material with a positive chromatic dispersion characteristic and a liquid crystal material with a reverse dispersion characteristic applied to the retardation layer, respectively. be able to. Further, a positive C plate can be produced by applying a coating liquid made of a liquid crystal material for a so-called C plate and drying and curing it. In vertical alignment (VA) liquid crystal display devices and the like, a liquid crystal material is aligned in the vertical direction by a 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 liquid crystal compound molecules in the retardation layer in a predetermined direction reliably and strictly. On the other hand, in some embodiments, it is important to appropriately control the thickness of the alignment film, the film thickness of the alignment film can be appropriately controlled, and the alignment regulating force is effectively exerted on the liquid crystal compound in the retardation layer. There is a need for a retardation film having an alignment film having a novel structure that can be applied.

JP-A-10-68816 U.S. Pat. No. 8,119,026 Japanese translation of PCT publication No. 2010-52892 JP-T 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 having a novel structure. And in one certain aspect, it aims at providing the phase difference film which can control the film thickness of an orientation film appropriately, and can exhibit the orientation regulation power effectively to the liquid crystal compound in a phase contrast layer. .

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

  (2) Further, the present invention is the retardation film according to the invention of (1), wherein in the alignment film, the ultraviolet curable resin and the thermosetting resin are present in phase separation.

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

  (4) Further, in the invention according to any one of (1) to (3), the base material is subjected to anti-blocking treatment and has irregularities, and the film thickness of the alignment film is The retardation film has a size equal to or greater than the height of the convex portion on the surface of the substrate.

  (5) Further, 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, the retardation layer, The retardation film is characterized in that the substrate and the alignment film are peeled using the interface of the film as a peeling interface.

  (6) Further, the present invention is the retardation film according to the invention of (5), wherein the transfer layer is transferred to an optical functional layer that imparts a phase difference of ¼ wavelength.

  According to the present invention, a retardation film having an alignment film having a novel configuration can be provided. In one embodiment, the thickness of the alignment film can be appropriately controlled, and the alignment regulating 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 is formed by laminating a liquid crystal layer with an alignment film composed of a PET base material, an ultraviolet curable resin and a thermosetting resin, and when the film 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 a liquid crystal layer side interface (A) and an alignment film side interface (B). (A) is a graph showing a reference peak of a vertically aligned thermosetting material, and (B) is a graph showing a reference peak of a UV curable material. It is a flowchart which shows the flow of the production process of retardation film. It is a figure for demonstrating the flow which produces an optical film by the 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 “present embodiments”) 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. 1. Configuration of retardation film 2. Alignment film 3. Production method of retardation film 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 base material 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 laminated 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 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 the retardation film 1 having the novel alignment film 12 formed of a mixed material of two kinds of different resins, such as an ultraviolet curable resin and a thermosetting resin, the ultraviolet curable resin is included in the alignment film 12. For example, the following retardation film can be obtained by utilizing the property that phase and thermosetting resin exist in phase separation. That is, as will be described in detail later, as an example, the alignment film is a vertical alignment film for effectively homeotropic alignment of the molecular axes of the liquid crystal compound molecules in the retardation layer, and an alignment having a predetermined thickness. It is a film | membrane, It can be set as the phase difference film which can suppress effectively generation | occurrence | production of the repellency of the coating liquid at the time of forming the phase difference layer 13 (coating liquid for phase difference layer formation).

  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 that has a function of supporting the alignment film 12 and is formed 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, and the surface thereof. Those having an adhesive strength that can be peeled off are preferred.

  Examples of the film material constituting the substrate 11 include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and polyarylate, polyolefins such as polyethylene, polypropylene, and polymethylpentene, triacetyl cellulose, and acrylic. A polymer etc. can be mentioned. The substrate 11 may be a single layer made of these materials, but may be a laminate in which two or more materials are laminated. Moreover, when it is set as the laminated body of a some layer, the layer of the same composition may be laminated | stacked.

  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. When the thickness of the base material 11 is less than 20 μm, the minimum self-supporting property as the transfer laminate for optical films may not be imparted. On the other hand, when the thickness exceeds 200 μm, when the optical film transfer laminate is long, the long optical film transfer laminate is cut to obtain a single wafer optical film transfer laminate. In some cases, the amount of processing waste increases or the cutting blade wears out quickly.

  Here, the base material 11 may be subjected to various anti-blocking treatments. Examples of the anti-blocking process include an easy adhesion process, a process for preventing blocking by kneading a filler and the like, a knurling process, and the like. By applying such an anti-blocking treatment to the base material 11, it is possible to effectively prevent sticking between the base materials when winding the base material 11, so-called blocking, and to produce a retardation film with high productivity. It can be manufactured.

  When the anti-blocking treatment is performed on the base material 11 in this way, irregularities are formed on the surface of the base material 11. Although it does not specifically limit as a height (size) of the convex part of the surface of the base material 11 in which the blocking prevention process was performed, Generally, it is about 0.5 micrometer-1.5 micrometers.

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

  The alignment film 12 is not particularly limited. For example, the alignment film 12 can be a vertical alignment film that homeotropically aligns the molecular axes of the liquid crystal compound molecules in the retardation layer 13 (vertical alignment). 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 using an LB film, or the like can be applied.

  As described above, the alignment film 12 is not limited to be composed of a vertical alignment film, and may be an alignment film that causes the molecular axis of the liquid crystal compound to be homogeneously aligned (horizontal alignment). May be an alignment film that hybrid-aligns (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 at 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, propylene glycol monoethyl ether (PGME), alkyl halide solvents such as chloroform and dichloromethane, methyl acetate Ester solvents such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate (PGMEA), amide solvents such as N, N-dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, anan solvents such as cyclohexane, Methanol, ethanol can be exemplified an alcohol solvent such as isopropyl alcohol. Moreover, one type of solvent may be sufficient and the mixed solvent of two or more types of solvents may be sufficient.

  Such an alignment film 12 is produced by applying a coating liquid made of an alignment film composition containing the material as described above to the substrate 11 and drying it, followed by a predetermined curing treatment. The alignment film 12 is composed of the cured product thus produced.

  Here, the retardation film 1 according to the present embodiment is characterized in that the alignment film 12 is made of a mixed material of an ultraviolet curable resin and a thermosetting resin. As will be described in detail later, according to the retardation film 1 having such an alignment film 12 made of a mixed material of an ultraviolet curable resin and a thermosetting resin, the ultraviolet curable resin is contained in the film. The resin and the thermosetting resin are present in a phase-separated state, and in particular, the thermosetting resin is unevenly distributed on the interface side 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. This polymerizable liquid crystal composition contains a liquid crystal compound (rod-like compound) exhibiting 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 a desired retardation by regularly arranging the liquid crystal compound. 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 easier in order to arrange regularly than liquid crystal compounds exhibiting other liquid crystal phases. It is preferable to use a material exhibiting the above liquid crystallinity. The liquid crystal compound exhibiting a nematic phase is preferably a material having spacers at both ends of the mesogen. Since the liquid crystal compound having spacers at both ends of the mesogen is excellent in flexibility, the retardation film 1 can be excellent in transparency.

  For example, when the alignment film 12 is made of a vertical alignment film and the liquid crystal compound is homeotropically aligned, the liquid crystal compound is particularly a homeotropic liquid crystal material capable of forming homeotropic alignment. It is not limited. Examples of the homeotropic liquid crystal material include materials that can form homeotropic alignment without using a vertical alignment film, and materials that can form 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 is possible to polymerize and fix the liquid crystal compound, so that the alignment stability is excellent and the phase change is less likely to occur over time. The polymerizable liquid crystal compound more preferably has a polymerizable functional group capable of three-dimensional crosslinking in the molecule. By having a polymerizable functional group capable of three-dimensional crosslinking, the sequence stability can be further enhanced. Note that “three-dimensional crosslinking” means that liquid crystal molecules are polymerized three-dimensionally to form a network structure.

  Examples of the polymerizable functional group include those that polymerize by the action of ionizing radiation such as ultraviolet rays and electron beams, or heat. Examples of these polymerizable functional groups include radical polymerizable functional groups and cationic polymerizable functional groups. Representative examples of radically polymerizable functional groups include functional groups having at least one addition-polymerizable ethylenically unsaturated double bond, such as vinyl groups having or without substituents, acrylate groups (acryloyl). Group, methacryloyl group, acryloyloxy group, generic name including methacryloyloxy group) and the like. Moreover, an epoxy group etc. are mentioned as a specific example of a cationically polymerizable functional group. In addition, examples of the polymerizable functional group include an isocyanate group and an unsaturated triple bond. 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 onto the alignment film 12. For example, the amount in the liquid crystal composition can be in the range of about 5 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 liquid crystal compounds and the like. For example, hydrocarbon solvents such as benzene and hexane, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone (CHN). Solvent, 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 Ester solvents such as (PGMEA), 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. Moreover, one type of solvent may be single and 2 or more types of mixed solvents may be sufficient as it.

  The amount of the solvent is not particularly limited and can 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 dissolved uniformly, which is not preferable. On the other hand, when the amount exceeds 900 parts by mass, a part of the solvent remains, which may reduce reliability and may not be uniformly applied.

  In addition, the liquid crystal composition may contain other compounds as necessary, as long as the alignment order of the liquid crystal compounds described above is not impaired. Examples thereof include a polymerization inhibitor, a plasticizer, a surfactant, and a silane coupling agent.

  The thickness of the retardation layer 13 formed by applying the liquid crystal composition as described above on the alignment film 12 is not particularly limited. The thickness is preferably 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 composed of a mixed material of an ultraviolet curable resin and a thermosetting resin.

  In such an alignment film 12 made of 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 alignment film 12. And 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 between the alignment film 12 and the retardation layer 13. This is considered to be because the thermosetting resin migrates to the atmosphere side (comparably hydrophobic) rather than the substrate 11 side, which is relatively hydrophilic, and becomes easier to stabilize.

  Here, in FIG. 2, a retardation film in which a PET substrate, an alignment film composed of a mixed material of an ultraviolet curable resin and a thermosetting resin, and a retardation layer (liquid crystal layer) are laminated in this order. Shows the analysis results 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. Specifically, in this XPS analysis, an ultraviolet (UV) curable material (referred to as “UV curable material (a)”) and a thermosetting material exhibiting vertical orientation (“thermosetting material (b)”). ”), And a mixed material mixed at a weight ratio of 1: 100 is applied onto the PET substrate as a material constituting the alignment film so that the film thickness of the alignment film is 3 μm. The alignment film was formed by curing by irradiating with ultraviolet rays.

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

  From this, in the alignment film constituted by 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 it is unevenly distributed on the interface side between the liquid crystal layer and the alignment film.

(Utilization example of retardation film 1 having alignment film 12)
By the way, generally, in the retardation film, various anti-blocking treatments for preventing blocking or the like for winding are performed on the base material. However, conventionally, when a retardation film is formed using a base material that has been subjected to such an anti-blocking treatment, irregularities are formed on the surface of the base material by the anti-blocking treatment, and an alignment film is coated on the base material. 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 substrate. Then, when a coating solution for forming a retardation layer containing a liquid crystal composition is applied on the alignment layer having such unevenness and having a large surface roughness (Ra), it follows the unevenness on the surface of the alignment film. As a result, the coating solution for forming the retardation layer cannot be uniformly applied onto the alignment layer, and so-called “repellency” occurs in which the alignment layer is exposed. Occurrence of coating defects such as repellency reduces the yield of retardation films, and when a visual inspection is performed by laminating a polarizing plate on an optical film where cissing has occurred, the phase difference in the part where cissing has occurred is small. This causes defects and the like and causes poor appearance.

  In order to deal with such a conventional problem, in this embodiment, the alignment film 12 made of the mixed material of the ultraviolet curable resin and the thermosetting resin described above is subjected to an antiblocking treatment. The base material 11 is formed so as to have a thickness (film thickness) equal to or higher than the height of the convex portion on the surface. Thus, the surface roughness of the alignment film 12 resulting from the unevenness of the substrate 11 is reduced 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. Can do. That is, by forming the alignment layer 12 having a predetermined thickness or more, the unevenness of the base material 11 is embedded in the alignment film 12 and can be canceled. Thereby, generation | occurrence | production of the repellency at the time of liquid crystal composition application | coating on the alignment film 12 can be suppressed effectively.

  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. For example, the liquid crystal compound is surely and strictly homeotropic aligned (vertical alignment). It is demanded. The alignment direction of the molecules of the liquid crystal compound is not limited to vertical alignment, and may be homogeneous alignment (horizontal alignment) or hybrid alignment (tilt alignment). However, in order to align a liquid crystal compound in a desired direction, when forming an alignment film using a thermosetting resin showing the alignment in the desired direction, from the viewpoint of the high viscosity of the thermosetting resin, etc. The film thickness of the alignment film that can be formed only by the thermosetting resin is limited, and a sufficiently thick alignment film cannot be formed. From this, in order to effectively suppress the occurrence of repelling when forming the retardation layer as described above, in the conventional retardation film, the film thickness is equal to or higher than the height of the convex portion on the surface of the substrate. Thus, the alignment film cannot be formed effectively.

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

  That is, for example, the thermosetting resin constituting the alignment film 12 is a thermosetting resin exhibiting vertical alignment that homeotropically aligns the molecular axes of the liquid crystal compound molecules in the retardation layer 13. In the retardation film 1, the alignment film 12 is composed of a mixed material of an ultraviolet curable resin and a thermosetting resin exhibiting such vertical alignment, so that the ultraviolet curable resin and the heat in the alignment film 12 are formed. The curable resin is present in a phase-separated state, and in particular, the thermosetting resin exhibiting vertical alignment is unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13. On the other hand, since the alignment film 12 is composed of a mixed material of an ultraviolet curable resin and a thermosetting resin, in the alignment film 12 exhibiting vertical alignment, the ultraviolet curable resin (on the substrate 11 side). 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 that is unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13 effectively exerts the alignment regulating force on the liquid crystal compound, and the alignment film is formed 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 higher than the height of the convex portion on the surface of the substrate can be effectively formed.

  By this, as described above, it becomes possible to effectively suppress the occurrence of cissing at the time of coating the liquid crystal composition, and by the thermosetting resin exhibiting vertical alignment unevenly distributed on the phase difference layer 13 side, The liquid crystal compound in the liquid crystal layer formed on the alignment film 12 can be surely and strictly homeotropically aligned.

  In addition, as an example of utilization of the phase difference film 1 which has such an alignment film 12, it illustrated only as a certain aspect, and 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 with ultraviolet rays. For example, monomers such as acrylates and methacrylates, prepolymers, or these A mixture obtained by adding a photopolymerization initiator such as acetophenone, benzophenone, and aromatic iodonium to the above mixture can be used.

  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, dipenta Resins such as erythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate can be used.

(Thermosetting resin material)
The thermosetting resin constituting the alignment film 12 is a component that is unevenly distributed on the interface side between the alignment film 12 and the retardation layer 13 in the alignment film 12 as described above. Therefore, the thermosetting resin affects the orientation of the molecules of the liquid crystal compound in the retardation layer 13. From this, the thermosetting resin is not particularly limited as long as it can be cured by heat. However, in order to exert the alignment regulating force to align the liquid crystal compound of the retardation layer 13 in a desired direction. It is preferable to select an optimal resin.

  For example, in order to vertically align the liquid crystal compound, it is preferable to select a thermosetting resin exhibiting vertical alignment. Specifically, the thermosetting resin exhibiting vertical alignment is not particularly limited as long as it can be cured by heat and the liquid crystal compound can be homeotropically aligned. For example, thermosetting polyimide or long chain alkyl can be used. And a polyamic acid having a group or an alicyclic structure in the side chain. Examples of thermosetting resin materials exhibiting vertical alignment include lecithin, silane surfactants, titanate surfactants, pyridinium salt polymer surfactants, n-, as well as the above-described thermosetting resins. Silane coupling agents such as octadecyltriethoxysilane can also be mixed.

  The alignment direction of the molecules of the liquid crystal compound is not limited to vertical alignment, and may be homogeneous alignment (horizontal alignment) or hybrid alignment (gradient alignment), and exhibits an alignment property that aligns 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 is thermosetting with respect to the ultraviolet curable resin material 100 in weight ratio. It is preferable to mix a resin material in the ratio of 0.1-10, and it is more preferable to mix in the ratio of 1-5.

  Regarding the mixing ratio, if 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 by weight ratio, the alignment regulation force in the alignment film becomes weak, and the retardation layer There is a possibility that the liquid crystal compound in 13 cannot be sufficiently aligned in a predetermined direction. On the other hand, when the mixing amount of the thermosetting resin material is a ratio exceeding 10 with respect to the ultraviolet curable resin material 100 by weight ratio, the mixed material becomes cloudy and gels effectively on the substrate. There is a possibility that an alignment film that cannot be applied and exhibits a desired effect cannot be formed.

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

  As shown in FIG. 4, in the production of the retardation film 1, first, a base material 11 such as a PET film is provided from a long film wound around a roll (S1).

  Next, in the alignment film forming step (S2), a coating liquid (alignment film composition) for forming an alignment film is applied onto the base material 11 drawn out from the roll, and after being dried, a curing process is performed. Thereby, the alignment film 12 is formed on the substrate 11. At this time, in the present embodiment, 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 treatment, and then an ultraviolet ray is applied. The alignment film 12 is formed by curing by irradiation. In addition, 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 liquid crystal composition coating liquid containing a liquid crystal compound (a retardation layer forming coating liquid) is applied onto the alignment film 12. Thereafter, the retardation layer (liquid crystal layer) 13 is formed by drying and curing by irradiation with ultraviolet rays or the like. In addition, you may make it perform the leveling process for making the layer thickness of the phase difference layer 13 uniform before an ultraviolet irradiation process.

  Here, in the present embodiment, as described above, the alignment film 12 is formed by coating the alignment film composition composed of the mixed material of the ultraviolet curable resin and the thermosetting resin on the substrate 11. Is forming. 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 present in phase separation in the film, and in particular, the thermosetting resin is aligned with the alignment film 12 and the retardation layer 13. And become unevenly distributed on the interface side.

  Thus, after manufacturing the laminated body film by which the base material 11 / alignment film 12 / retardation layer 13 are laminated | stacked in this order, after winding up the obtained film with a take-up reel etc., desired size is obtained. A cutting process is performed. Through such a process, the retardation film 1 is produced.

  In addition, the coating method of the alignment film composition on the substrate 11 and the coating method of the coating liquid for forming the retardation layer on the alignment film 12 are not particularly limited. 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, dipping and lifting 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 >>
Now, the optical film applied to a flat panel display or the like uses, for example, a transfer laminate for an optical film having a transfer layer transferred to an optical functional layer such as a linear polarizing plate that functions as a linear polarizing plate. It can be produced by a transfer method. In the transfer method, for example, when a desired layer is formed on a predetermined base material, the desired layer is not directly formed on the base material, but once a releasable support (support After the layer is formed in a peelable manner on the body substrate), a transfer laminate is produced, and then the layer formed on the support is finally laminated according to the process, demand, etc. In this method, a desired layer is formed on a predetermined base material by bonding and laminating on the (transfer base material) and then peeling off and removing the support. It is considered that an optical film having a small overall thickness can be provided by producing an optical film by such a transfer method. In addition, the optical film produced by the transfer method is described in patent document 5 and patent document 6, for example.

  The retardation film 1 according to the present embodiment can be applied as an optical film transfer laminate used when an optical film is produced using a transfer method. As described above, the transfer laminate for an optical film is obtained by changing a retardation layer constituting the retardation film from a substrate having a releasability (releasing substrate) or an alignment film to any other substrate. Is used to form a retardation layer on an arbitrary substrate. In the transfer laminate for an optical film, for example, an optical functional layer of a linear polarizing plate, a reverse dispersion stretched film, or a laminate of a λ / 2 retardation plate and a λ / 4 retardation plate is used. The transfer layer can be transferred by bonding to an optical functional layer or the like that provides a phase difference for four wavelengths. The optical film transfer laminate is not particularly limited. For example, the interface between the alignment film 12 and the retardation layer 13 becomes a peeling interface, and the optical film transfer laminate is used in the production of the optical film. After the transfer layer (retardation layer 13) is transferred to a substrate such as a reverse dispersion stretched film, the substrate 11 and the alignment film 12 are peeled 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 an optical film transfer laminate will be described. In the following, the optical film transfer laminate is described as “optical film transfer laminate 1A”.

  FIG. 5 shows an optical film obtained by transferring the transfer layer of the optical film transfer laminate 1A to an optical functional layer that imparts a phase difference of ¼ wavelength to transmitted light using the optical film transfer laminate 1A. 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 the layer structure of the film in each process. Further, 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 retardation containing a liquid crystal composition on the alignment film 12. A layer forming coating solution is applied to form a retardation layer (liquid crystal layer) 13 to produce an optical film transfer laminate 1A. Here, as described above, in the production of the optical film transfer laminate 1A, the alignment film 12 is formed using an alignment film composition made of a mixed material of an ultraviolet curable resin and a thermosetting resin. Yes.

  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 optical film transfer laminate 1A. For example, the reverse dispersion stretched film 22 is formed to transfer the optical film transfer laminate 1A.

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

  Moreover, as long as it plays a role as a retardation layer for a quarter-wave plate, it is not particularly limited. For example, a stretched film having reverse dispersion characteristics (hereinafter also referred to as “reverse dispersion stretched film 22”) is formed on the adhesive layer 21. Can be formed. The reverse dispersion stretched film 22 is formed of, for example, a PC (polycarbonate) film stretched in the longitudinal direction, 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. Are arranged so as to form an angle of about 45 degrees, and serve as a retardation layer for a quarter-wave plate for imparting a quarter-wave phase difference to transmitted light. By using such a reverse dispersion stretched film 22, for example, the configuration of the base material, the resin layer for a quarter wavelength plate, and the alignment film for a quarter wavelength plate can be omitted. The layer thickness can be reduced.

  When the reverse dispersion stretched film 22 is laminated and transferred to the optical film transfer laminate 1A, the substrate 11 and the alignment film 12 of the optical film transfer laminate 1A are then peeled off as shown in FIG. 5 (c). To do. The optical film transfer laminate 1A thus serves as a releasable support in order to transfer the transfer layer (retardation layer 13) to another substrate (polymer film or the like). 11 and the alignment film 12 are peeled off. In addition, you may make it perform peeling of the base material 11 and the oriented film 12 after laminating | stacking the linear polarizing plate mentioned later.

  And if the base material 11 and the alignment film 12 of 1 A of transcription | transfer laminated bodies for optical films are peeled, next, as shown in FIG.5 (d), the linearly-polarizing plate provided with the adhesive layer 31 is laminated | stacked.

  As the linear polarizing plate, the optical functional layer is disposed after the lower surface side of the base material 34 made of a transparent film such as TAC (triacetyl cellulose) is saponified. In addition, the base material 34 is poly (meth) methyl acrylate, poly (meth) butyl acrylate, (meth) methyl acrylate- (meth) butyl acrylate copolymer, (meth) methyl acrylate-styrene copolymer. Resins such as acrylic resin such as coalescence, glass such as soda glass, potassium glass, lead glass, and quartz glass can also be applied.

  The optical functional layer is a part 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 are used. Can do. Such a linearly polarizing plate is bonded to the reverse dispersion stretched film 22 via the pressure-sensitive adhesive layer 31.

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

  Note that, as described above, the optical film transfer laminate 1A has the alignment film 12 made of a vertical alignment film, and is reversed on the retardation layer 13 of the optical film transfer laminate 1A via the adhesive layer 21. By laminating the dispersion-stretched film 22, and providing the linearly polarizing plate provided with the polarizer 33 sandwiched by the base materials 32, 34 made of a transparent film on the reverse dispersion-stretched film 22, it is easy and high in productivity. Thus, an optical film having a positive C plate with reverse dispersion characteristics can be obtained.

  In the above-described example, the interface between the alignment film 12 and the retardation layer 13 is used as a peeling interface, and the substrate 11 and the alignment film 12 are peeled off after transfer. However, the peeling interface is not limited thereto. Instead, the interface between the base material 11 and the alignment film 12 may be the peeling interface, and only the base material 11 may be peeled after transfer to transfer the alignment film 12 and the retardation layer 13 to another base material.

DESCRIPTION OF SYMBOLS 1 Retardation film 1A Transfer laminated body for optical films 11 Base material 12 Orientation film 13 Retardation layer (liquid crystal layer)

Claims (7)

The base material, the alignment film, and the retardation layer are laminated in this order,
The retardation layer includes a liquid crystal compound,
The alignment film is composed of a mixed material of an ultraviolet curable resin and a thermosetting resin,
The thermosetting resin has an alignment regulating force for aligning the liquid crystal compound contained in the retardation layer in a desired direction,
In the alignment film, the ultraviolet curable resin is phase-separated on the substrate side, and the thermosetting resin is phase-separated on an interface side between the alignment film and the retardation layer. However, the ultraviolet curable resin excludes liquid crystal compounds. 2. The retardation film according to claim 1, wherein the thermosetting resin contained in the alignment film has an alignment regulating force for vertically aligning a liquid crystal compound contained in the retardation layer . The base material is subjected to anti-blocking treatment and has irregularities,
3. The retardation film according to claim 1, wherein a thickness of the alignment film is not less than a height of a convex portion on a surface of the base material. The retardation film is a transfer laminate for an optical film having a transfer layer,
The base material and the alignment film are peeled from the retardation layer by using the interface between the alignment film and the retardation layer as a peeling interface. Retardation film.   The retardation film according to claim 4, wherein the transfer layer is transferred to an optical functional layer that imparts a retardation corresponding to a quarter wavelength. A method for producing a retardation film for producing the retardation film according to any one of claims 1 to 5,
  An alignment film composition composed of a mixed material of an ultraviolet curable resin and a thermosetting resin is coated on a base material, dried, and then cured by irradiating ultraviolet rays to form an alignment film. An alignment film forming step to be formed;
  Retardation layer forming step of forming a retardation layer by coating and curing a retardation layer forming coating liquid of a liquid crystal composition containing a liquid crystal compound on the alignment film;
  With
  A method for producing a retardation film. An optical film in which the retardation film according to any one of claims 1 to 5 is disposed in a state where the base material and the alignment film are peeled off.

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