JP2014199332A - Production method of retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a retardation film, which gives a retardation film showing excellent adhesiveness to an acrylic resin substrate and an alignment layer and reduction in alignment defects.SOLUTION: The production method of a retardation film includes steps of: preparing an acrylic resin substrate containing at least one of an antioxidant and a UV absorbent; preparing a composition for forming an alignment layer, the composition comprising a photo-aligning compound and a solvent in which solubility 23°C of the antioxidant and the UV absorbent included in the acrylic resin substrate is each 15 (g/100 g of the solvent) of less, solubility at 23°C of the acrylic resin substrate is 0.1 (g/100 g of the solvent) or more, and solubility at 23°C of the photo-aligning compound is 3.0 (g/100 g of the solvent) or more; forming an alignment layer on one surface side of the acrylic resin substrate; and forming a retardation layer on the alignment layer.

Description

  The present invention relates to a method for producing a retardation film.

Conventionally, in a liquid crystal display device, various techniques have been developed in order to improve the problem of viewing angle dependency. As one of them, a retardation film having a retardation layer exhibiting birefringence is used as a liquid crystal cell. Liquid crystal display devices disposed between polarizing plates are known (for example, Patent Documents 1 and 2).
The retardation film having the retardation layer includes an alignment layer having an alignment regulating force for aligning liquid crystal compounds in a certain direction on a substrate, and a liquid crystal compound formed on the alignment layer and aligned in a certain direction. A layer having a retardation layer containing s is used.

  Conventionally, as a flat panel display, a two-dimensional display has been mainstream, but in recent years, a flat panel display capable of three-dimensional display has begun to attract attention. Further, in future flat panel displays, it is a natural tendency to be capable of three-dimensional display, and flat panel displays capable of three-dimensional display are being studied in a wide range of fields.

In order to perform three-dimensional display on a flat panel display, it is usually necessary to display a right-eye video and a left-eye video separately to the viewer in some manner. As a method for separately displaying the right-eye video and the left-eye video, for example, a passive method is known. Such a passive three-dimensional display method will be described with reference to the drawings. FIG. 2 is a schematic view showing an example of a liquid crystal display device capable of displaying a three-dimensional image in a passive manner. As shown in FIG. 2, in this method, first, the pixels constituting the flat panel display are classified into two types of pixels, a right-eye video display pixel and a left-eye video display pixel, and the right-eye pixel is displayed in the display display area. The pixels are arranged in a pattern so that the left-eye pixels are adjacent to each other. One group of pixels displays a right-eye image, and the other group of pixels displays a left-eye image. Also, using a linear polarizing plate and a pattern phase difference film (hereinafter simply referred to as a pattern phase difference film) in which a pattern phase difference layer corresponding to the arrangement pattern of the pixel is formed, an image for the right eye is used. And the image for the left eye are each converted into circularly polarized light. In addition, the viewer wears circularly polarized glasses that employ a right-eye lens and a left-eye lens, and the right-eye image passes only through the right-eye lens, and the left-eye image passes only through the left-eye lens. Like that. In this way, the right-eye video reaches only the right eye, and the left-eye video reaches only the left eye, thereby enabling three-dimensional display.
Such a passive method has an advantage that three-dimensional display can be easily performed by using the pattern retardation film and the corresponding circular polarizing glasses.

  As the pattern retardation film, for example, in Patent Document 3, a photo-alignment layer in which the alignment regulating force is controlled in a pattern shape on a glass substrate, and the alignment layer of the liquid crystal compound formed on the photo-alignment layer. A pattern retardation plate having a retardation layer (liquid crystal layer) patterned so as to correspond to the pattern of the alignment layer is disclosed.

  Here, in order for the retardation film and the pattern retardation film to exhibit excellent optical performance, the change in the retardation value in the thickness direction is small, and the liquid crystal compound is arranged in a certain direction by the alignment layer. The optical axis is required to be constant throughout the film or within each pattern in the film.

JP-A-3-67219 JP-A-4-322223 JP 2005-49865 A

Therefore, in order to further improve the optical performance of the retardation film, the present inventors used a film instead of the triacetyl cellulose (TAC) substrate, which has been the mainstream, as a resin substrate used for the retardation film. The use of an acrylic resin substrate having a small thickness direction retardation was studied.
However, considering the solvent resistance of the base material and the adhesion between the base material and the coating film formed on the base material, when using an acrylic resin base material, it is used for the coating liquid applied directly to the base material. The types of possible solvents are limited.
Furthermore, as a solvent in the coating liquid for the alignment layer applied on the acrylic resin base material, it can be formed even if usable from the viewpoint of solvent resistance of the base material and adhesion between the base material and the coating film. In some cases, alignment failure occurred in the alignment layer.

  The present invention has been made in view of the above circumstances, and provides a method for producing a retardation film that is capable of obtaining a retardation film having excellent adhesion between an acrylic resin substrate and an alignment layer and having reduced alignment defects. The purpose is to do.

The method for producing a retardation film according to the present invention is a method for producing a retardation film in which an alignment layer and a retardation layer are provided in this order on one side of an acrylic resin substrate,
Preparing an acrylic resin substrate containing at least one of an antioxidant and an ultraviolet absorber;
The solubility at 23 ° C. of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate is 15 (g / 100 g solvent) or less, respectively, and the solubility at 23 ° C. of the acrylic resin substrate is 0.1 (g / 100 g solvent) or more, and a composition for forming an alignment layer comprising a photoalignment compound and a solvent in which the solubility of the photoalignment compound at 23 ° C. is 3.0 (g / 100 g solvent) or more is prepared. Process,
Applying the alignment layer forming composition on one side of the acrylic resin substrate, drying, and irradiating with light, thereby forming an alignment layer;
A step of applying a composition for forming a retardation layer containing a liquid crystal compound on the alignment layer, and orienting the liquid crystal compound to form a retardation layer.

  In the method for producing a retardation film according to the present invention, before the step of forming the alignment layer, the solubility of the acrylic resin substrate at 23 ° C. on the one surface side of the acrylic resin substrate is 0.1 ( It is preferable from the point which further improves the orientation using the solvent which is less than (g / 100g solvent).

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the retardation film from which the retardation film excellent in the adhesiveness of an acrylic resin base material and an orientation layer and the orientation defect was reduced can be provided.

It is the schematic which shows an example of the phase difference film obtained by the phase difference film manufacturing method concerning this invention. It is the schematic which shows an example of the liquid crystal display device which can display a three-dimensional image | video with a passive system.

Hereinafter, the method for producing the retardation film according to the present invention will be described.
In the present invention, the optical axis means a slow axis.
In the present invention, the retardation film includes a pattern retardation film unless otherwise specified.
In the present invention, (meth) acryl represents each of acryl and methacryl, and (meth) acrylate represents each of acrylate and methacrylate.

The method for producing a retardation film according to the present invention is a method for producing a retardation film in which an alignment layer and a retardation layer are provided in this order on one side of an acrylic resin substrate,
Preparing an acrylic resin substrate containing at least one of an antioxidant and an ultraviolet absorber;
The solubility at 23 ° C. of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate is 15 (g / 100 g solvent) or less, respectively, and the solubility at 23 ° C. of the acrylic resin substrate is 0.1 (g / 100 g solvent) or more, and a composition for forming an alignment layer comprising a photoalignment compound and a solvent in which the solubility of the photoalignment compound at 23 ° C. is 3.0 (g / 100 g solvent) or more is prepared. Process,
Applying the alignment layer forming composition on one side of the acrylic resin substrate, drying, and irradiating with light, thereby forming an alignment layer;
A step of applying a composition for forming a retardation layer containing a liquid crystal compound on the alignment layer, and orienting the liquid crystal compound to form a retardation layer.

  In FIG. 1, the schematic of an example of the phase difference film obtained by the phase difference film manufacturing method concerning this invention is shown. A retardation film 1 illustrated in FIG. 1 is obtained by providing an alignment layer 3 and a retardation layer 4 in this order on at least one surface side of an acrylic resin substrate 2.

As the solvent in the composition for forming an alignment layer used for the production of the retardation film, it is necessary to select and use a usable solvent from the viewpoint of the solvent resistance of the substrate and the adhesion between the substrate and the coating film. . However, when an acrylic resin substrate is used as the substrate, alignment defects may occur in the formed alignment layer even if an appropriate solvent is used from these viewpoints.
As a result of intensive studies, the present inventors have included an additive in the acrylic resin base material, and the additive is dissolved in the solvent in the coating liquid applied on the base material to be eluted into the alignment layer. In addition, the inventors have found that an alignment defect occurs because impurities are mixed in the alignment layer. Furthermore, the present inventors have focused on antioxidants and ultraviolet absorbers as typical additives in acrylic resin base materials that cause poor alignment.
In addition, the solvent contained in the composition for forming an alignment layer needs to have solubility in the acrylic resin substrate to such an extent that it can penetrate into the acrylic resin substrate from the viewpoint of adhesion between the substrate and the alignment layer. From the viewpoint of force, it is necessary to have solubility in the photo-alignment compound to such an extent that the photo-alignment compound used can be uniformly dissolved.
Therefore, the present inventors have a low solubility of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate as a solvent contained in the composition for forming an alignment layer, and the acrylic resin substrate and the alignment layer have a low solubility. By producing a retardation film using a solvent having a solubility of the photo-alignment compound of a predetermined value or more as appropriate according to the type of each material, the adhesion between the acrylic resin substrate and the alignment layer can be improved. It has been found that a retardation film excellent in orientation and having excellent alignment properties with a uniform alignment regulating force can be obtained with excellent alignment inhibition of the alignment layer.

The method for producing a retardation film according to the present invention includes an acrylic resin substrate preparation step, an alignment layer forming composition preparation step, an alignment layer formation step, and a retardation layer formation step, preferably the alignment layer formation step. The method further includes a step of cleaning the acrylic resin substrate, and may further include other steps as necessary.
Hereinafter, each process in the manufacturing method of this invention is demonstrated in order.

<Acrylic resin substrate preparation process>
What is necessary is just to select suitably as an acrylic resin of the acrylic resin base material used for this invention from what is used for a conventionally well-known acrylic resin base material as an optical film use. Examples thereof include acrylic resins obtained by polymerizing monomers such as (meth) acrylic acid esters, acrylamide, acrylonitrile, (meth) acrylic acid or derivatives thereof. Among these, from the viewpoint of transparency and weather resistance, polymethyl methacrylate, a copolymer having a methyl methacrylate unit as a main component, or a styrene-methyl methacrylate copolymer is preferable.

Moreover, the acrylic resin base material used for this invention contains an antioxidant or a ultraviolet absorber at least as an additive.
The antioxidant in the present invention refers to an additive that is added to suppress the oxidation of the acrylic resin, and has any of a radical chain inhibiting action, a triplet elimination action, and a hydroperoxide decomposition action. is there. In addition, the antioxidant in the present invention includes compounds that can bring about the action of the above antioxidant in addition to known compounds conventionally used as an antioxidant.
Although it does not specifically limit as antioxidant contained in the said acrylic resin base material, For example, a phenol type, amine type, sulfur type, phosphorus type antioxidant, etc. are mentioned.

  The phenolic antioxidant is not particularly limited. For example, 2,6-di-tert-butyl-p-cresol (Yosinox BHT manufactured by API Corporation), 4,4′-butylidenebis- (6-tert- Butyl-3-methylphenol) (Yoshinox BB, manufactured by API Corporation), 2,2'-methylenebis- (4-methyl-6-tert-butylphenol) (Yosinox 2246G, manufactured by API Corporation), 2,2'- Methylene bis- (4-ethyl-6-tert-butylphenol (Yosinox 425 manufactured by API Corporation), 2,6-di-tert-butyl-4-ethylphenol (250 manufactured by API Corporation), 1,1,3 -Tris (2-methyl- Hydroxy-5-butylphenyl) butane (Yoshinox 930 manufactured by API Corporation), n-octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Tominox SS manufactured by API Corporation) ), Tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane (Tominox TT manufactured by API Corporation), triethylene glycol bis [3- (3-tert- Butyl-4-hydroxy-5-methylphenyl) propionate] (Tominox 917 manufactured by API Corporation), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl- 4-hydroxybenzyl) benzene ( Product name: IRGANOX 1330 manufactured by Ciba Japan), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 1010 manufactured by Ciba Japan), 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (trade name: Sumilizer GM, manufactured by Sumitomo Chemical Co., Ltd.), 2- [1- (2- Hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate (trade name: Sumilizer GS, manufactured by Sumitomo Chemical Co., Ltd.), N, N′-hexamethylenebis (3 5-di-t-butyl-4-hydroxy-hydrocinnamamide) (trade name: IRGANOX 1098, manufactured by Ciba Japan), 1,6-hexanediol-bis [3- (3 -Di-t-butyl-4-hydroxyphenyl) propionate] (trade name: IRGANOX 259 manufactured by Ciba Japan), 3,9-bis [2- [3- (3-t-butyl-4-hydroxy-5 -Methylphenyl) propionyloxy] 1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro [5.5] undecane (trade name: Sumilizer GA-80 manufactured by Sumitomo Chemical Co., Ltd.), Tris- (3 5-di-t-butyl-4-hydroxybenzyl) isocyanurate (trade name: IRGANOX 3114, manufactured by Ciba Japan), isooctyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ( Product name: IRGANOX 1135, manufactured by Ciba Japan), 4,4'-thiobis (6-tert-butyl-3-methylphenol) (product name: Sumilizer WX-R, manufactured by Sumitomo Chemical Co., Ltd.) And 6- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3,2] Examples include dioxaphosphepine (trade name: Sumilizer GP, manufactured by Sumitomo Chemical Co., Ltd.), tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid (Cyanox 1790, manufactured by Cytec), and the like.

  The amine-based antioxidant is not particularly limited, and examples thereof include N-isopropyl-N′-phenyl-p-phenylenediamine (Antage 3C manufactured by Kawaguchi Chemical Industry Co., Ltd.), N- (1,3-dimethylbutyl) -N. '-Phenyl-p-phenylenediamine (Antage 6C manufactured by Kawaguchi Chemical Industry Co., Ltd.), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (Antage AW manufactured by Kawaguchi Chemical Industry Co., Ltd.), octyl diphenylamine, N -N-butyl-p-aminophenol, N, N-diisopropyl-p-phenylenediamine, n-butylamine, triethylamine, diethylaminomethyl methacrylate and the like.

  The sulfur-based antioxidant is not particularly limited, and examples thereof include dilauryl thiodipropionate (DLTP manufactured by API Corporation), distearyl thiodipropionate (DSTP manufactured by API Corporation), and dimyristylthiodipropioate. Nate (DMTP manufactured by API Corporation), ditridecylthiodipropionate (DTTP manufactured by API Corporation), and the like.

  The phosphorus antioxidant is not particularly limited, and examples thereof include triphenyl phosphite (TTP) and triisodecyl phosphite (TDP).

  Among these antioxidants, phenolic antioxidants are preferably used as the antioxidant contained in the acrylic resin substrate.

In the present invention, the ultraviolet absorber refers to a compound having an absorption spectrum in an ultraviolet region having a wavelength of 380 nm or less, and includes those capable of exhibiting an ultraviolet absorbing function in addition to known compounds conventionally used as ultraviolet absorbers.
Although it does not specifically limit as an ultraviolet absorber contained in the said acrylic resin base material, For example, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) Benzotriazoles such as -4,6-bis (1-methyl-1-phenylethyl) phenol and 2- (2'-hydroxy-5'-methylphenyl) benzotriazole; 2,2'-dihydroxy-4-methoxy Triazines such as benzophenone, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol; octabenzone, 2,4-dihydroxybenzophenone, 2, Benzophenone series such as 2'-dihydroxy-4-methoxyphenone; salicylate series such as phenyl salicylate; 2,4-di- Organic ultraviolet absorbers such as benzoates such as tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate and hexadecyl-2,5-t-butyl-4-hydroxybenzoate, and titanium oxide And inorganic ultraviolet absorbers such as zinc oxide, cerium oxide, iron oxide, and barium sulfate. Of these, benzophenone and benzotriazole are preferably used as the ultraviolet absorber contained in the acrylic resin substrate.

  Although the total content of the antioxidant and the ultraviolet absorber in the total solid content of the acrylic resin substrate is not particularly limited, it can sufficiently exhibit at least one of the antioxidant effect and the ultraviolet absorber effect. The amount of the antioxidant and the ultraviolet absorber from the acrylic resin substrate can be prevented, and the amount is usually about 0.01 to 10% by mass.

  What is necessary is just to set suitably the thickness of the said acrylic resin base material within the range which can provide required self-supporting property according to the use etc. of retardation film, and it is in the range of about 0.02-10 mm normally.

<Alignment layer forming composition preparation step>
The alignment layer contains a photo-alignment compound or a reaction product thereof, and the liquid crystal compound having refractive index anisotropy contained in the retardation layer can be arranged in a certain direction by irradiation with polarized ultraviolet rays. It is a layer having an orientation regulating force.
In the present invention, the composition of the composition for forming an alignment layer used for forming the alignment layer is such that the solubility at 23 ° C. of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate is 15 (g / 100 g solvent). The solubility of the acrylic resin substrate at 23 ° C. is 0.1 (g / 100 g solvent) or more, and the solubility of the photoalignable compound at 23 ° C. is 3.0 (g / 100 g solvent) or more. The solvent and the photo-alignment compound are not particularly limited, and other components may be included as necessary.
Here, the photo-alignment compound refers to a compound that can exhibit an alignment regulating force by irradiation with polarized ultraviolet rays. Further, “alignment regulating force” means an interaction for aligning liquid crystal compounds described later.

  Such a photo-alignment compound is not particularly limited as long as it exhibits the above-mentioned alignment regulating force by irradiating polarized light. Such photo-alignment compounds include a photoisomerization material that reversibly changes the alignment regulation force by changing only the molecular shape by cis-trans change, and a photoreaction material that changes the molecule itself by irradiating polarized light. Can be broadly classified. In the present invention, any of the photoisomerization material and the photoreaction material can be suitably used, but it is more preferable to use the photoreaction material. As described above, the photoreactive material is a material that reacts with polarized light to develop an alignment regulating force by irradiating polarized light. Therefore, the photoreactive material can irreversibly develop an alignment regulating force. Therefore, the photoreactive material is superior in the temporal stability of the orientation regulating force.

  The photoreactive material can be further classified according to the type of reaction caused by polarized light irradiation. Specifically, a photodimerization type material that develops an alignment regulation force by causing a photodimerization reaction, a photodegradable material that produces an orientation regulation force by producing a photodecomposition reaction, an orientation regulation by producing a photobinding reaction It can be divided into a photocoupled material that expresses force, and a photolytic-coupled material that develops alignment regulation force by causing a photodecomposition reaction and a photocoupled reaction. In the present invention, any of the above-mentioned photoreactive materials can be suitably used, and among these, it is more preferable to use a photodimerization type material from the viewpoint of stability and reactivity (sensitivity).

  The photodimerization-type material used for this invention will not be specifically limited if it is a material which can express an orientation control force by producing photodimerization reaction. Especially, it is preferable that the wavelength of the light which produces a photodimerization reaction is 280 nm or more, It is preferable to exist in the range of 280 nm-400 nm especially, Furthermore, it is preferable to exist in the range of 300 nm-380 nm.

  Examples of such photodimerization-type materials include cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleinimide, cinnamylideneacetic acid, and polymers having derivatives thereof. . In particular, in the process, a polymer having at least one of cinnamate or coumarin, a polymer having cinnamate and coumarin, and derivatives thereof are preferably used. Specific examples of such a photodimerization type material include, for example, JP-A-9-118717, JP-A-10-506420, JP-A-2003-505561, WO2010 / 150748, WO2011 / 126019. And the compounds described in Japanese Laid-Open Patent Publication No. WO2011 / 126021 and WO2011 / 126022.

  As the cinnamate and coumarin, those represented by the following formulas Ia and Ib are preferably used.

In the above formula, A represents pyrimidine-2,5-diyl, pyridine-2,5-diyl, 2,5-thiophenylene, 2,5-furylene, 1,4- or 2,6-naphthylene, Unsubstituted, fluorine, chlorine or a cyclic, linear or branched alkyl residue of 1 to 18 carbon atoms (unsubstituted or mono- or polysubstituted by fluorine, chlorine, 1 Represents phenylene that is mono- or polysubstituted by more than one non-adjacent —CH ₂ — group, which may be independently substituted by Z ₁ ).
Z ₁ represents —O—, —CO—, —CO—O—, —O—CO—, —NR ₁ —, —NR ₁ —CO—, —CO—NR ₁ —, —NR ₁ —CO—. O—, —O—CO—NR ₁ —, —NR ₁ —CO—NR ₁ —, —CH═CH—, —C≡C—, —O—CO—O— and —Si (CH ₃ ) ₂ — It represents a group selected from O—Si (CH ₃ ) ₂ — (R ₁ represents a hydrogen atom or lower alkyl).
In the above formula, B represents a hydrogen atom or a group capable of reacting or interacting with a second substance such as a polymer, oligomer, monomer, photoactive polymer, photoactive oligomer, photoactive monomer, or surface. Represent.
In the above formula, S ₁ and S ₂ are independently of each other a single bond or a spacer unit, for example a linear or branched alkylene group having 1 to 40 carbon atoms (unsubstituted, fluorine or chlorine Mono- or poly-substituted, and one or more non-adjacent —CH ₂ — groups may be independently substituted by Z ₂ , but the oxygen atoms are not directly bonded to each other).
Z ₂ represents —O—, —CO—, —CO—O—, —O—CO—, —NR ₁ —, —NR ₁ —CO—, —CO—NR ₁ —, —NR ₁ —CO—. O—, —O—CO—NR ₁ —, —NR ₁ —CO—NR ₁ —, —CH═CH—, —C≡C—, —O—CO—O— and —Si (CH ₃ ) ₂ — A group selected from O—Si (CH ₃ ) ₂ — (R ₁ represents a hydrogen atom or lower alkyl), an aromatic group or an alicyclic group.
In the above formula, Q represents an oxygen atom or —NR ₁ — (R ₁ represents a hydrogen atom or lower alkyl).
In the above formula, X and Y are independently of each other hydrogen, fluorine, chlorine, cyano, alkyl having 1 to 12 carbon atoms (optionally substituted by fluorine and optionally not one or more adjacent). alkyl -CH ₂ - groups are -O -, - CO-O - , - O-CO- and / or an) are replaced by -CH = CH-.
In addition, as such a photodimerization-type material, specifically, what is commercially available as ROP-103 (trade name) from Rolic in WO08 / 031243 and WO08 / 130555 can be used. .

  Moreover, as a photo-alignment compound used for this invention, you may have refractive index anisotropy. As the photo-alignment compound having such refractive index anisotropy, specifically, those described in JP-A-2002-82224 can be used.

  In addition, the photo-alignment compound used for this invention may be only one type, or may use 2 or more types.

The composition for forming an alignment layer contains at least a photo-alignment compound, but may contain other compounds as necessary.
Such other compounds are not particularly limited as long as they do not impair the alignment regulating force of the alignment layer, but monomers or oligomers having one or more functional groups are preferably used. By including such a monomer or oligomer, when a retardation layer containing a liquid crystal compound having refractive index anisotropy is formed on the alignment layer, it can be excellent in adhesion to the retardation layer.

  Examples of the monomer or oligomer include a monofunctional monomer having an acrylate functional group (for example, reactive ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone), and a polyfunctional monomer. (For example, polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, triethylene (polypropylene) glycol diacrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) Acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate Isocyanuric acid poly (meth) acrylate (for example, isocyanuric acid EO diacrylate)), bisphenol fluorene derivatives (for example, bisphenoxyethanol fluorenedi (meth) acrylate, bisphenol fluorenedin epoxy (meth) acrylate), etc. alone or mixed It can be used as a thing.

  Furthermore, it is preferable to use a monomer or oligomer that is solid at room temperature (20 to 25 ° C.). Thereby, even when the retardation film is stored in a rolled state, blocking due to the alignment layer sticking to the back surface of the substrate can be prevented.

  The content of the monomer or oligomer is not particularly limited as long as it does not impair the alignment regulating force of the alignment layer formed in this step and can exhibit desired adhesion and the like. The range of 0.01 to 3 times the mass of the orientation compound is preferable, and the range of 0.05 to 1.5 times is particularly preferable.

  In the composition for forming an alignment layer, the content of solids other than the solvent containing the photo-alignment compound may be appropriately adjusted and is not particularly limited, but is 2 for the entire composition for forming the alignment layer containing the solvent. It is preferable that it is -50 mass%.

The solvent contained in the composition for forming an alignment layer has a solubility at 23 ° C. of each of an antioxidant and an ultraviolet absorber contained in the acrylic resin substrate of 15 (g / 100 g solvent) or less, and the acrylic resin group The solubility of the material at 23 ° C. is 0.1 (g / 100 g solvent) or more, and the solubility of the photoalignable compound at 23 ° C. is 3.0 (g / 100 g solvent) or more.
The solubility of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate at 23 ° C. is 15 (g / 100 g solvent) or less, respectively. Both the antioxidant and the ultraviolet absorber are included in the acrylic resin substrate. When both are contained, the solubility of the antioxidant at 23 ° C. is 15 (g / 100 g solvent) or less, and the solubility of the ultraviolet absorber at 23 ° C. is 15 (g / 100 g solvent) or less. . Moreover, when two or more types of antioxidants are contained in the acrylic resin base material, the solubility at 23 ° C. is 15 or less (g / 100 g solvent) for each antioxidant.
In addition, the solvent contained in the composition for forming an alignment layer has a solubility at 23 ° C. of the acrylic resin substrate of 3 (g / 100 g solvent) or less from the viewpoint of preventing deformation and cracking of the acrylic resin substrate. Preferably there is.

  Such a solvent can be appropriately selected depending on the acrylic resin substrate to be used and the antioxidant, ultraviolet absorber and photo-alignment compound contained in the acrylic resin substrate, and is not particularly limited. Alcohol solvents such as methanol, ethanol, ethylene glycol, 2-propanol (IPA), propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy-2-propanol (PGME); ethyl acetate, butyl acetate, ethylene Ester solvents such as glycol methyl ether acetate, γ-butyrolactone, propylene glycol 1-monomethyl ether 2-acetate (PGMEA), ethyl lactate; acetone, cyclopentanone, cyclohexanone, 2-heptanone, Ketone solvents such as tilethylketone (MEK) and methylisobutylketone (MIBK); chlorinated aliphatic hydrocarbon solvents such as pentane, hexane and heptane; non-chlorine aromatic hydrocarbon solvents such as toluene and xylene; Examples thereof include nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene.

These solvents may be used alone or in combination of two or more. When a mixed solvent is used as the solvent contained in the alignment layer forming composition, the mixed solvent is appropriately selected so as to satisfy the specific solubility condition.
Regarding the solubility in antioxidants and UV absorbers contained in acrylic resin substrates, the structure of antioxidants and UV absorbers contained in acrylic resin substrates is specified in advance, and the antioxidants and UV absorbers are targeted. Select a solvent.
The antioxidant and ultraviolet absorber in the acrylic resin base material can be identified by, for example, dissolving the acrylic resin base material in a good solvent for the acrylic resin base material and performing gas chromatography mass spectrometry. Or you may specify the structure of the antioxidant and ultraviolet absorber in an acrylic resin base material by performing secondary ion mass spectrometry, without dissolving an acrylic resin base material in a solvent.

Moreover, as a standard in the case of using a mixed solvent, among them, from the viewpoint of preventing poor alignment of the retardation film, the solubility of the antioxidant and the ultraviolet absorber at 23 ° C. is 13 (g / 100 g solvent) or less respectively. Is preferably contained in an amount of not less than 70% by mass, more preferably not less than 80% by mass, and still more preferably not less than 90% by mass.
For example, the solubility at 23 ° C. of a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid is 13 (g / 100 g solvent) or less. Examples of the solvent include IPA, PGME, and ethanol.
Further, as the solvent, from the viewpoint of preventing poor alignment of the retardation film, the content of the solvent having the solubility of each of the antioxidant and the ultraviolet absorber at 23 ° C. of 15 (g / 100 g solvent) or more is the whole solvent. Is preferably 30% by mass or less, and more preferably 20% by mass or less.
For example, the solubility at 23 ° C. of a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid is 15 (g / 100 g solvent) or more. Examples of the solvent include PGMEA and MIBK.
In addition, as the solvent, from the viewpoint of preventing orientation failure of the retardation film, the content of the solvent having the solubility of each of the antioxidant and the ultraviolet absorber at 23 ° C. of 20 (g / 100 g solvent) or more is the whole solvent. Is preferably less than 10% by mass, and more preferably less than 5% by mass.
For example, the solubility at 23 ° C. of a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid is 20 (g / 100 g solvent) or more. Examples of the solvent include MEK and ethyl acetate.

In addition, as the solvent, the solubility of the acrylic resin substrate at 23 ° C. is improved because the solvent is infiltrated into the acrylic resin substrate at the time of forming the alignment layer to improve the adhesion between the acrylic resin substrate and the alignment layer. A solvent of 0.1 (g / 100 g solvent) or more is used, and preferably a solvent of 0.2 (g / 100 g solvent) or more is used. By adding a solvent having a relatively high solubility at 23 ° C. of the acrylic resin substrate to a solvent having a low solubility at 23 ° C. of the acrylic resin substrate, the solubility of the mixed solvent at 23 ° C. of the acrylic resin substrate is increased. It can also be 0.1 (g / 100 g solvent) or more. In the mixed solvent, the amount of the solvent having a relatively high solubility at 23 ° C. of the acrylic resin base material depends on the degree of solubility, so the solubility of the acrylic resin base material at 23 ° C. is 0.1 ( (g / 100 g solvent) may be adjusted as appropriate.
As a guideline for preparing the mixed solvent, for example, it is preferable that the acrylic resin base material contains a solvent having a solubility at 23 ° C. of 0.2 (g / 100 g solvent) or more of 2% by mass or more of the total solvent.
Examples of the solvent having a solubility of the acrylic resin substrate at 23 ° C. of 0.2 (g / 100 g solvent) or more include PGMEA, MIBK, MEK, and ethyl acetate.

It is preferably used when the acrylic resin substrate contains a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid. As the solvent, for example, a mixed solvent of PGME and PGMEA, wherein PGME: PGMEA (mass ratio) is 70:30 to 90:10, more preferably a mixed solvent of 75:25 to 85:15; PGME And MEK, a mixed solvent having a PGME: MEK (mass ratio) of 95: 5 to 98: 2; a mixed solvent of PGME and MIBK, and a PGME: MIBK (mass ratio) of 80: A mixed solvent of 20 to 95: 5; a mixed solvent of PGME and ethyl acetate, and a mixed solvent of PGME: ethyl acetate (mass ratio) of 95: 5 to 98: 2 It is.
In addition, what is necessary is just to adjust the detailed ratio of a mixed solvent suitably according to each antioxidant and ultraviolet absorber contained in an acrylic resin base material.

  The content of the solvent in the composition for forming an alignment layer may be appropriately adjusted and is not particularly limited, but from the viewpoint of coating properties, it is 50 to 98 mass with respect to the entire composition for forming an alignment layer containing a solvent. % Is preferred.

<Acrylic resin substrate cleaning process>
In the method for producing a retardation film of the present invention, before the alignment layer forming step described later, the solubility of the acrylic resin substrate at 23 ° C. on one side of the acrylic resin substrate on which the alignment layer is formed is 0.1. It is preferable to include a cleaning step using a solvent that is less than (g / 100 g solvent). By the said washing | cleaning process, the antioxidant and ultraviolet absorber which exist in the acrylic resin base material surface can be reduced, without having a bad influence on an acrylic resin base material. As a result, since the elution of the additive from the acrylic resin substrate to the alignment layer can be further prevented, the alignment property of the retardation film can be improved.
Further, the solvent used in the washing step is not particularly limited, but the oxidation contained in the acrylic resin base material is excellent in the action of removing the antioxidant and the ultraviolet absorber present on the acrylic resin base material. The solubility of the inhibitor and the ultraviolet absorber at 23 ° C. is preferably 10 (g / 100 g solvent) or more. In addition, it is preferable that the solubility of the solvent used for the said washing | cleaning process is 15 (g / 100g solvent) or less from the point which does not elute the antioxidant and ultraviolet absorber which are contained in an acrylic resin base material.

  As the solvent used in the washing step, a solvent having a relative evaporation rate of 50 to 700 is preferably used because drying of the washing step takes time if the volatility is too low. Here, the relative evaporation rate refers to a relative evaporation rate when the evaporation rate of acetic acid-n-butyl is 100.

  The solvent used in the washing step is not particularly limited as long as it has a solubility in the acrylic resin substrate as defined above, and can be appropriately selected according to the material to be used. For example, an acrylic resin base material containing a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid as an antioxidant is used. When used, examples of the solvent that can be used in the washing step include 1-methoxy-2-propanol (PGME), 2-propanol (IPA), and ethanol.

  Moreover, although the said washing | cleaning process is not specifically limited, You may perform several times using a different solvent. Among them, the solubility at 23 ° C. of the antioxidant and the UV absorber contained in the acrylic resin substrate is selected from the solvents whose solubility at 23 ° C. of the acrylic resin substrate is less than 0.1 (g / 100 g solvent). Is used in the previous washing step, and then the solubility of the antioxidant and the UV absorber contained in the acrylic resin substrate at 23 ° C. is relatively low, but the relative evaporation rate is relatively low. Substitution with a high solvent and drying quickly are preferable from the viewpoint that the antioxidant and ultraviolet absorber on the substrate can be efficiently washed away. For example, an acrylic resin base material containing a phenolic antioxidant such as 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid as an antioxidant is used. In this case, the washing step includes washing with PGME, which is a solvent having a higher solubility of the antioxidant, and then substituting with IPA, which is a solvent having a lower solubility of the antioxidant but a higher relative evaporation rate. It is preferable to do.

  The method for cleaning the acrylic resin substrate in the cleaning step is not particularly limited and can be performed by a general cleaning method. For example, one surface side of the acrylic resin substrate on which the alignment layer is formed is generally cleaned. A method of quickly drying by washing with the above-mentioned solvent such as PGME using an apparatus or the like, and evaporating the solvent while blowing air for 0.1 to 3 minutes using an air blow or the like at 20 to 25 ° C. Etc.

<Alignment layer formation process>
The alignment layer is formed by applying and drying the alignment layer forming composition on one surface side of the acrylic resin substrate, and irradiating with light.

(Application)
The method for applying the alignment layer forming composition to one side of the acrylic resin substrate is particularly limited as long as the alignment layer forming composition can be uniformly applied to the acrylic resin substrate surface. For example, dip coating, air knife coating, curtain coating, roll coating, wire bar coating, gravure coating, die coating, blade coating, micro gravure coating, spray coating, spin coating A known method such as a method is used.

  Moreover, the coating amount of the composition for forming an alignment layer on the acrylic resin substrate may be adjusted as long as the obtained alignment layer expresses a desired alignment regulating force. Especially, it is preferable that the thickness of the alignment layer obtained will be 50-300 nm, and it is more preferable that it will be 100-200 nm. When the thickness of the alignment layer is within the above range, the alignment layer is excellent in the alignment regulating force.

(Dry)
After coating by any of the coating methods, the solvent contained in the alignment layer forming composition is dried.
Specifically, it may be dried while blowing air with a blower or the like immediately after coating. As specific drying temperature, 30 degreeC-120 degreeC is mentioned, for example, 40-110 degreeC is preferable. Further, the drying wind speed is preferably 0.2 m / s to 50 m / s, and the drying time is suitably adjusted within a range of 20 seconds to 3 minutes, preferably 30 seconds to 2 minutes.
Here, the solid content concentration of the composition for forming the alignment layer, the temperature of the composition for forming the alignment layer, the drying temperature, the wind speed of the drying air, the drying time, the solvent atmosphere concentration in the drying zone, and the like will be described later. The thickness of the osmotic layer can be adjusted. In particular, a method of adjusting the thickness of the osmotic layer by selecting drying conditions is preferable.
The drying may be naturally dried at 20 to 30 ° C. without blowing air in order to increase the thickness of the permeation layer.

(Light irradiation)
Light irradiation may be appropriately selected from conventionally known methods. As irradiation light, ultraviolet rays, visible light, an electron beam, ionizing radiation, etc. are used, for example. In the case of irradiating ultraviolet rays, ultraviolet rays emitted from light rays such as an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be used.
Light irradiation may be performed from the side on which the alignment layer forming composition is applied, or light irradiation may be performed from the acrylic resin substrate side opposite to the surface on which the alignment layer forming composition is applied.
What is necessary is just to adjust an irradiation amount suitably so that it may become the exposure amount which can orient the photoalignment compound contained in the composition for alignment layer formation.

(Penetration layer)
In the present invention, by irradiating with light, the dried coating film is photo-aligned and cured at the same time, whereby an alignment layer is formed and the osmotic layer in which the photo-alignment compound has penetrated into the acrylic resin substrate. May be formed. Here, the permeation layer refers to a layer in which at least a component of the acrylic resin base material and a photoalignment compound are mixed.
In this invention, it is preferable to have a osmosis | permeation layer from the point which can improve the adhesiveness of an acrylic resin base material and an orientation layer.
The presence of the permeation layer can be confirmed by, for example, an electron micrograph of a cross section of the retardation film, mapping by a microscopic IR of the cross section, or a TOF-SIMS method.

<Phase difference layer forming step>
The retardation layer forming step is a step of forming a retardation layer by applying a composition for forming a retardation layer containing a liquid crystal compound on the alignment layer and aligning the liquid crystal compound.
In the retardation layer, a desired retardation is imparted by regularly arranging liquid crystal compounds along the alignment regulating force of the alignment layer.
In addition, the composition for forming a retardation layer contains at least a liquid crystal compound and a solvent, and may contain other components as necessary.

  Examples of the liquid crystal compound include a liquid crystalline molecular material exhibiting a liquid crystal phase such as a nematic phase or a smectic phase. Among these, a nematic liquid crystalline molecular material is preferable because it can be regularly arranged. Furthermore, among the nematic liquid crystalline molecular materials, those having spacers at both mesogenic ends are more preferable because a retardation film having excellent flexibility and excellent transparency can be produced.

The liquid crystal compound is preferably a polymerizable liquid crystal compound having a polymerizable functional group in the molecule, and more preferably a polymerizable liquid crystal compound having a polymerizable functional group capable of three-dimensional crosslinking.
The polymerizable liquid crystal compound has a polymerizable functional group in the liquid crystal molecule, and can be cross-linked between the liquid crystal molecules by the action of a radical generated from the photopolymerization initiator by irradiation of light or an electron beam. Stability of the retardation film is improved. Examples of the polymerizable liquid crystal compound include a nematic liquid crystalline molecular material, a cholesteric liquid crystalline molecular material, a chiral nematic liquid crystalline molecular material, a smectic liquid crystalline molecular material, and a discotic liquid crystalline molecular material having a polymerizable group. Can do.

  The method for forming the retardation layer is not particularly limited as long as it can accurately coat a retardation layer having a desired thickness. About the method of application | coating, drying, and hardening, the method similar to the said orientation layer formation process can be used.

  Although the thickness of a phase difference layer is not specifically limited, For example, it can set within the range of 1 nm-2000 nm, Preferably, it is 500 nm-1500 nm.

  Moreover, in the case of a pattern phase difference film, it can manufacture with reference to the method etc. of Unexamined-Japanese-Patent No. 2012-14064, for example.

Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the present invention. In addition, the symbol in an Example is as follows.
PGME: 1-methoxy-2-propanol PGMEA: Propylene glycol 1-monomethyl ether 2-acetate MEK: Methyl ethyl ketone IPA: 2-propanol

Example 1
First, a solution in which an acrylic resin substrate of the same type as the acrylic resin substrate used for the production of the retardation film was dissolved in PGME was obtained. The resulting solution was subjected to gas chromatograph mass spectrometry, whereby antioxidant A (1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) was added to the acrylic resin substrate. It was confirmed that isocyanuric acid) was contained.

Next, an orientation containing 4.5% by mass of photodimerization reaction type photo-alignment compound A and 95.5% by mass of mixed solvent 1 in which PGME and PGMEA are mixed at a ratio of 80:20 (mass ratio). A layer forming composition was prepared.
Mixed solvent 1 has a solubility of antioxidant A at 23 ° C. of 13 (g / 100 g solvent), the solubility of the acrylic resin substrate at 23 ° C. of 0.2 (g / 100 g solvent), and photo-alignment The solubility of the functional compound A at 23 ° C. was 4.5 (g / 100 g solvent).

Next, the said composition for alignment layer formation was apply | coated to the one surface side of the said acrylic resin base material, it was made to dry at 100 degreeC, and it was set as the coating film whose film thickness after drying is 150 nm. The coating film was irradiated with the first polarized ultraviolet ray through a mask having a stripe pattern having a width of 500 μm at an exposure amount of 10 mJ. Next, the second polarized ultraviolet ray having a polarization axis of 90 ° formed by the polarization axis of the first polarized ultraviolet ray is irradiated at an exposure amount of 10 mJ without passing through a mask, and the film thickness having a stripe pattern is 150 nm. An alignment layer was formed.
On the alignment layer, a retardation layer forming composition containing a polymerizable liquid crystal compound and methyl isobutyl ketone is applied and cured by irradiating with ultraviolet rays to form a retardation layer having a thickness of 1 μm. The retardation film of Example 1 was obtained.

<Orientation evaluation>
Two polarizing plates were placed in crossed Nicols, the retardation film of Example 1 was put between the two polarizing plates and rotated, and the unevenness of black luminance was visually observed. If there is no shading unevenness in black luminance, it is evaluated that there is no optical axis shift or retardation change, and no partial alignment failure occurs in the alignment layer.
The retardation film of Example 1 had almost no orientation failure and good orientation.

<Cross cut test (adhesion evaluation)>
In order to evaluate the adhesion between the acrylic resin substrate of the retardation film of Example 1 and the alignment layer, a cross-cut test was performed in accordance with JIS K5400. Judgment is represented by the number of squares that do not peel out of 100 squares. The greater the number of squares that do not peel, the better the adhesion.
The retardation film of Example 1 obtained a 100/100 result in the cross-cut test, and was found to be excellent in adhesion between the substrate and the alignment layer.

(Example 2)
Example 2 was performed in the same manner as Example 1 except that the mixed solvent 2 in which PGME and MEK were mixed at a ratio of 98: 2 (mass ratio) was used as the solvent contained in the composition for forming an alignment layer. A retardation film was obtained.
Mixed solvent 2 has a solubility of antioxidant A at 23 ° C. of 13 (g / 100 g solvent), the solubility of the acrylic resin substrate at 23 ° C. of 0.2 (g / 100 g solvent), and photo-alignment The solubility of the functional compound A at 23 ° C. was 4.5 (g / 100 g solvent).

  The retardation film of Example 2 was subjected to orientation evaluation and crosscut test in the same manner as in Example 1. As a result, the retardation film of Example 2 showed almost no orientation failure and good orientation, and obtained a 100/100 result in the cross-cut test, resulting in adhesion between the substrate and the orientation layer. It was revealed that it was excellent.

(Example 3)
The retardation film of Example 3 was used in the same manner as in Example 2 except that a photoalignment compound B different from the photoalignment compound A was used as the alignment compound to be contained in the composition for forming an alignment layer. Obtained.
Moreover, the mixed solvent 2 had a solubility of the photoalignment compound B at 23 ° C. of 6.0 (g / 100 g solvent).

  The retardation film of Example 3 was subjected to orientation evaluation and crosscut test in the same manner as in Example 1. As a result, the retardation film of Example 3 has almost no orientation failure, and the orientation is good. The result of 100/100 is obtained in the cross-cut test, and the adhesion between the substrate and the orientation layer is improved. It was revealed that it was excellent.

Example 4
Before applying the alignment layer forming composition on one side of the acrylic resin substrate, one side of the acrylic resin substrate is washed with a solvent of 100% PGME, further substituted with 100% IPA, and solvented with air. A retardation film of Example 4 was obtained in the same manner as in Example 3 except that the film was washed by quickly drying.
100% PGME had an antioxidant A solubility at 23 ° C. of 10 (g / 100 g solvent) and the acrylic resin substrate had a solubility at 23 ° C. of 0.05 (g / 100 g solvent).
100% IPA had an antioxidant A solubility at 23 ° C. of 0.8 (g / 100 g solvent) and the acrylic resin substrate had a solubility at 23 ° C. of less than 0.05 (g / 100 g solvent). It was.

  The retardation film of Example 4 was subjected to orientation evaluation and crosscut test in the same manner as in Example 1. As a result, in the retardation film of Example 4, no alignment failure was observed, and the orientation was improved as compared with Example 3 in which the alignment film was not washed. Moreover, the result of 100/100 was obtained in the cross-cut test, and it was revealed that it was excellent in the adhesiveness of a base material and an orientation layer.

(Comparative Example 1)
A retardation film of Comparative Example 1 was obtained in the same manner as Example 1 except that 100% PGME was used as the solvent to be included in the alignment layer forming composition.
100% PGME has the solubility of antioxidant A at 23 ° C. of 10 (g / 100 g solvent), the solubility of the acrylic resin substrate at 23 ° C. of 0.05 (g / 100 g solvent), and photo-alignment The solubility of the functional compound A at 23 ° C. was 4.5 (g / 100 g solvent).

  The retardation film of Comparative Example 1 was subjected to orientation evaluation and crosscut test in the same manner as in Example 1. As a result, the retardation film of Comparative Example 1 showed almost no orientation failure and good orientation, but obtained a result of 80/100 in the cross-cut test, and the adhesion between the substrate and the orientation layer. It was revealed that it was inferior.

(Comparative Example 2)
Comparative Example 2 was performed in the same manner as in Example 1 except that the mixed solvent 3 in which PGME and MEK were mixed at a ratio of 90:10 (mass ratio) was used as the solvent to be contained in the alignment layer forming composition. A retardation film was obtained.
The mixed solvent 3 has an antioxidant A having a solubility at 23 ° C. of 20 (g / 100 g solvent), the acrylic resin base material having a solubility at 23 ° C. of 0.3 (g / 100 g solvent), and photo-alignment. The solubility of the functional compound A at 23 ° C. was 4.5 (g / 100 g solvent).

  The retardation film of Comparative Example 2 was subjected to orientation evaluation and crosscut test in the same manner as in Example 1. As a result, the retardation film of Comparative Example 2 had many poor orientations and was poor in orientation. In the cross-cut test, a result of 100/100 was obtained, and it was revealed that the adhesion between the substrate and the alignment layer was excellent.

(Reference Examples 1-4)
A composition in which 0% by mass, 0.3% by mass, 0.9% by mass, and 1.5% by mass of antioxidant A were added to the composition for forming an alignment layer used in Example 1, respectively. The composition was applied to a glass substrate so that the film thickness after curing was 150 nm, dried at 100 ° C., and then cured by ultraviolet irradiation with an exposure amount of 10 mJ to form an alignment layer. A retardation layer was formed on the alignment layer in the same manner as in Example 1 to obtain retardation films of Reference Examples 1 to 4.
With respect to the retardation films of Reference Examples 1 to 4, orientation evaluation was performed in the same manner as in Example 1. In Reference Example 1 in which antioxidant A was not added, the orientation was good, but in Reference Examples 2 to 4 in which antioxidant A was added, poor alignment was observed.

(Summary of results)
Since the retardation films obtained in Examples 1 to 4 were produced by the method for producing a retardation film of the present invention, the orientation was good, and the adhesion between the acrylic resin substrate and the orientation layer was excellent. . Moreover, the orientation property of the retardation film obtained in Example 4 in which the acrylic resin substrate was washed was further improved.
On the other hand, in the retardation film obtained in Comparative Example 1, since the solvent contained in the composition for forming an alignment layer had low solubility in the acrylic resin substrate, the adhesion between the acrylic resin substrate and the alignment layer was It was inferior to.
In addition, the retardation film obtained in Comparative Example 2 was inferior in orientation because the solvent contained in the composition for forming an alignment layer had high solubility in the antioxidant in the acrylic resin substrate. . In addition, from the results of Reference Examples 1 to 4, it can be seen that alignment failure occurs when the alignment layer contains the antioxidant A. Therefore, in Comparative Example 2, the alignment was inferior in the alignment layer. It is estimated that the antioxidant A in the acrylic resin substrate was eluted.

DESCRIPTION OF SYMBOLS 1 Retardation film 2 Acrylic resin base material 3 Orientation layer 4 Retardation layer

Claims (2)

On one surface side of the acrylic resin substrate, an alignment layer and a retardation layer are provided in this order, and a method for producing a retardation film,
Preparing an acrylic resin substrate containing at least one of an antioxidant and an ultraviolet absorber;
The solubility at 23 ° C. of the antioxidant and the ultraviolet absorber contained in the acrylic resin substrate is 15 (g / 100 g solvent) or less, respectively, and the solubility at 23 ° C. of the acrylic resin substrate is 0.1 (g / 100 g solvent) or more, and a composition for forming an alignment layer comprising a photoalignment compound and a solvent in which the solubility of the photoalignment compound at 23 ° C. is 3.0 (g / 100 g solvent) or more is prepared. Process,
Applying the alignment layer forming composition on one side of the acrylic resin substrate, drying, and irradiating with light, thereby forming an alignment layer;
A step of applying a composition for forming a retardation layer containing a liquid crystal compound on the alignment layer, and orienting the liquid crystal compound to form a retardation layer. Method.   Prior to the step of forming the alignment layer, a solvent having a solubility of the acrylic resin substrate at 23 ° C. of less than 0.1 (g / 100 g solvent) is further used on one side of the acrylic resin substrate. The manufacturing method of the retardation film of Claim 1 which has the process to wash | clean.