JP6368178B2 - Resin composition, film containing the resin composition, polarizer protective film using the film, polarizing plate and image display device - Google Patents

Description

  The present invention relates to a resin composition containing an acrylic resin containing a cyclic structure in the main chain and a cellulose ester, an optical film containing the resin composition, a polarizer protective film using the film, a polarizing plate, and an image display device About.

  Since the cellulose ester resin is excellent in bonding property, handling property, and transparency with polyvinyl alcohol (PVA) used for a polarizer, application to an optical film for an image display device is being promoted. However, the cellulose ester resin has problems such as a high photoelastic coefficient.

Conventionally, a technique of blending an acrylic resin with a cellulose ester resin has been proposed as a technique for reducing the photoelastic coefficient of the cellulose ester resin.
Patent Document 1 discloses a film containing an acrylic resin having a haze value of less than 1%, a tension softening point of 100 to 145 ° C., and an in-plane retardation Ro in a certain range, and a cellulose resin. Yes.

However, these conventional techniques have a problem in that the transparency of the resin and the film after blending these resins may deteriorate due to the poor compatibility between the cellulose ester resin and the acrylic resin. It was. In addition, when these resins have a high molecular weight, there is a problem that the compatibility is particularly poor.
Furthermore, these conventional techniques cannot simultaneously satisfy the above-described transparency and the required physical properties of heat resistance and flexibility of a film using a resin after blending.

JP 2009-179731 A

  The present invention has been made in view of such problems of the prior art, and provides an optical film having a small photoelastic coefficient and an excellent balance of transparency, heat resistance and flexibility, and the film. It is an object of the present invention to provide a resin composition, a polarizer protective film using the film, a polarizing plate, and an image display device.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the ring structure of a resin composition containing an acrylic resin and a cellulose ester containing a ring structure in the main chain is a substitution on N. The resin composition was used by being a structural unit derived from a substituted maleimide monomer whose group is a C3-C12 cycloalkyl group, and having a weight average molecular weight (Mw) of the acrylic resin of 120,000 or more. It has been found that the optical film has a small photoelastic coefficient and has an excellent balance of transparency, heat resistance and flexibility.
In addition to the above, the present inventors have obtained various new findings as will be described below, and have made further studies and completed the present invention.

That is, the present invention relates to the following resin compositions and the like.
[1] A resin composition containing an acrylic resin containing a cyclic structure in the main chain and a cellulose ester, wherein the cyclic structure is a substituted maleimide monomer wherein the substituent on N is a C3-C12 cycloalkyl group A resin composition, which is a structural unit derived from a body, and wherein the acrylic resin has a weight average molecular weight (Mw) of 120,000 or more.
[2] The resin composition as described in [1] above, wherein the glass transition temperature of the resin composition is 120 ° C. or higher.
[3] An optical film comprising the resin composition according to any one of [1] or [2].
[4] A polarizer protective film, wherein the optical film according to [3] is used.
[5] A polarizing plate comprising the optical film according to [4].
[6] An image display device comprising the polarizing plate according to [5].

The resin composition of the present invention is highly compatible with the cellulose ester resin and the acrylic resin while the acrylic resin has a high molecular weight, and thus can have high transparency, and the optical film using the resin composition is also high. It can have transparency.
In addition, according to the present invention, an optical film having a small photoelastic coefficient and excellent balance of transparency, heat resistance and flexibility can be obtained.
Furthermore, since the acrylic resin contained in the resin composition of the present invention has a high molecular weight, the optical film of the present invention using the resin composition has high strength and excellent handling properties.

Hereinafter, the present invention will be described in detail.
The resin composition of the present invention is a resin composition containing an acrylic resin containing a ring structure in the main chain (hereinafter also referred to as an acrylic resin) and a cellulose ester, wherein the ring structure has a substituent on N. A structural unit derived from a substituted maleimide monomer that is a C3-C12 cycloalkyl group, wherein the acrylic resin has an Mw of 120,000 or more.

[Acrylic resin containing a ring structure in the main chain]
The acrylic resin containing a ring structure in the main chain used in the present invention is derived from a substituted maleimide monomer in which the ring structure contained in the main chain is a C3-C12 cycloalkyl group. For example, the main chain preferably includes a structural unit derived from a (meth) acrylate monomer (hereinafter also referred to as a (meth) acrylate unit). .

The (meth) acrylic acid ester unit is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) T-butyl acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate , Dicyclopentanyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth ) Acrylic acid 2,3,4,5,6-pentahydroxyhexyl, (meth) acrylic acid 2,3, , And structural units derived from monomers such as 5-tetrahydroxy-pentyl and the like. These structural units may contain one kind or two or more kinds.
The (meth) acrylic acid ester unit is preferably methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyl methacrylate, etc. More preferred are structural units derived from monomers such as methyl acrylate, methyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and dicyclopentanyl methacrylate. In this case, the heat resistance of the molded product such as a film obtained by molding the resin composition of the present invention containing the acrylic resin and cellulose ester and the resin composition is improved.

The acrylic resin containing a ring structure in the main chain may contain structural units other than the (meth) acrylic acid ester unit.
The structural unit other than the (meth) acrylic acid ester unit is not particularly limited, and examples thereof include styrene, vinyl toluene, acrylonitrile, methacrylonitrile, vinyl acetate, methyl vinyl ketone, N-vinyl pyrrolidone, and N-vinyl carbazole. Examples include structural units derived from monomers. These structural units may contain one kind or two or more kinds.

The acrylic resin containing a ring structure in the main chain used in the present invention has a substituted maleimide monomer whose ring structure contained in the main chain is usually a C3-C12 cycloalkyl group. A structural unit derived from the body. Examples of the substituted maleimide include N-cyclopropylmaleimide, N-cyclobutylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, N-cycloheptylmaleimide, N-cyclooctylmaleimide, and preferably N-cyclooctylmaleimide. Cyclohexylmaleimide, N-cyclooctylmaleimide and the like. These may contain 1 type, or 2 or more types.
By containing these ring structures in the main chain of the acrylic resin, the glass transition temperature (Tg) of the acrylic resin is increased. By increasing the Tg of the acrylic resin, the heat resistance of the resin composition of the present invention and the film obtained by molding the resin composition can be increased. The acrylic resin main chain contains the ring structure, so that the acrylic resin has a high molecular weight and excellent compatibility with the cellulose resin. Therefore, the resin composition has high transparency, high strength, and excellent bleed-out resistance. It can be a thing.

  In the acrylic resin containing a ring structure in the main chain used in the present invention, the ratio of the ring structure contained in the main chain of the acrylic resin is not particularly limited, but is 7% by mass or more based on the total amount of the acrylic resin. It is preferable that it is 30 mass% or less, 7 mass% or more and 25 mass% or less are more preferable, and 10 mass% or more and 20 mass% or less are more preferable. Within these ranges, the transparency, heat resistance and strength of a molded article such as a film obtained by molding the resin composition of the present invention containing an acrylic resin and a cellulose ester are improved.

The weight average molecular weight (Mw) of the acrylic resin containing a ring structure in the main chain used in the present invention is not particularly limited, but is usually 120,000 or more, preferably 120,000 or more and 1,000,000 or less. Preferably they are 80,000 or more and 800,000 or less. Within these ranges, the transparency, heat resistance, strength and bleed-out resistance of molded articles such as films obtained by molding the resin composition of the present invention containing an acrylic resin and a cellulose ester are improved.
Further, the dispersity (weight average molecular weight / number average molecular weight) of the acrylic resin is preferably 3.5 or less, and more preferably 3 or less. In this case, while maintaining the transparency, heat resistance and strength of the molded product at a high level, bleeding out due to the low molecular weight is further suppressed, and the appearance of the molded product is improved.
Mw and dispersity are values calculated in terms of polystyrene by gel permeation chromatography (GPC) using the method described in the examples below.

  The glass transition temperature (Tg) of the acrylic resin containing a ring structure in the main chain used in the present invention is not particularly limited, but is preferably 120 ° C. or higher and 170 ° C. or lower, more preferably 122 ° C. or higher and 150 ° C. or lower. It is. If it is these ranges, the heat resistance of the resin composition of this invention becomes high enough, and since the flexibility of molded articles, such as a film obtained by shape | molding a resin composition, is easy to be secured, it is preferable. Tg is a value evaluated by the method described in Examples described later.

  Moreover, it is preferable that the acrylic resin containing a cyclic structure in the main chain used in the present invention is thermoplastic. If it is thermoplastic, the resin can be melt-molded, including pelletized, and the moldability is improved.

[Method for producing acrylic resin containing ring structure in main chain]
The method for producing an acrylic resin containing a ring structure in the main chain used in the present invention is not particularly limited, and may be a conventionally known method for producing an acrylic resin.
The acrylic resin whose ring structure is a substituted maleimide structure can be produced, for example, according to the method described in JP-A-2007-31537.

  Examples of the method for producing an acrylic resin containing a ring structure in the main chain used in the present invention include (meth) acrylic acid ester and a substituted maleimide in which the substituent on N is a C3-C12 cycloalkyl group. A method of radical polymerization of the monomer composition is preferred. The radical polymerization method is not particularly limited, and conventionally known methods such as solution polymerization, emulsion polymerization and suspension polymerization can be used, and solution polymerization is preferable.

  Although the content ratio of the (meth) acrylic acid ester in the monomer composition in the polymerization step is not particularly limited, it is preferably 30 to 93% by mass, more preferably based on the total amount of the monomer composition. It is 50-90 mass%, More preferably, it is 60-90 mass%, Most preferably, it is 65-85 mass%. When the content ratio of the (meth) acrylic acid ester is less than 30% by mass, the optical properties of the obtained acrylic resin may be inferior. Moreover, when the content rate of (meth) acrylic acid ester exceeds 93 mass%, the heat resistance of the obtained acrylic resin may fall.

  In the monomer composition in the polymerization step, the content ratio of the substituted maleimide in which the substituent on N is a C3-C12 cycloalkyl group is not particularly limited, but is preferably relative to the total amount of the monomer composition. It is 7-30 mass%, More preferably, it is 7-25 mass%, More preferably, it is 10-20 mass%.

  The monomer composition may contain one or more monomers other than the (meth) acrylic acid ester and a substituted maleimide in which the substituent on N is a C3-C12 cycloalkyl group. Good. As these monomers, for example, monomers derived from structural units other than the above-mentioned (meth) acrylic acid ester units can be used.

  The polymerization solvent used in the solution polymerization is not particularly limited, but an organic solvent is preferable. The organic solvent is not particularly limited. For example, aromatic hydrocarbon solvents such as toluene, xylene, and ethylbenzene; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; ether solvents such as tetrahydrofuran; methanol, ethanol, butanol, and the like Examples include alcohol solvents. These solvents may be used alone or in combination of two or more.

Moreover, since the residual volatile matter of the acrylic resin finally obtained will increase when the boiling point of the polymerization solvent is too high, the polymerization solvent is preferably a solvent having a boiling point of 40 to 200 ° C. In view of carrying out solution film formation using the resin composition of the present invention contained, a solvent having a boiling point of 40 to 100 ° C. is more preferable.
When the boiling point of the polymerization solvent exceeds 100 ° C., a method of lowering the boiling point of the organic solvent by reducing the pressure in the polymerization tank, or cooling the jacket part or cooling with a coil introduced into the polymerization tank is performed. The temperature may be controlled by the method.

  The amount of the polymerization solvent used is not particularly limited, but may be appropriately selected from the range of usually 10 to 200 parts by mass with respect to 100 parts by mass of the total amount of the monomer composition in the polymerization system, preferably 15 It is -150 mass parts, More preferably, it is 15-100 mass parts.

  The polymerization temperature can be appropriately selected according to the reaction scale and the like, but is usually within the range of the internal temperature of the reaction solution of 30 to 200 ° C, preferably 50 to 180 ° C, more preferably 70. ~ 160 ° C. In this case, coloring of the acrylic resin can be suppressed, and a molded product having an excellent appearance can be obtained.

  The polymerization time is not constant depending on the reaction scale, reaction temperature, and the like, but is usually selected appropriately in the range of several minutes to 20 hours, preferably 0.5 to 20 hours, more preferably 1 to 10 hours. It is. Several minutes means about 1 to 10 minutes.

In the polymerization of the acrylic resin, a polymerization initiator may be used during the polymerization. A polymerization initiator is not specifically limited, A well-known compound can be used.
Examples of the polymerization initiator include cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, and t-amyl peroxyisononanoate. , Organic peroxides such as t-amylperoxy-2-ethylhexanoate and 1,1-di (t-butylperoxy) cyclohexane; 2,2′-azobis (isobutyronitrile), 1,1 Azo compounds such as' -azobis (cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate; and the like. These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited as long as it is appropriately set according to the combination of monomers and reaction conditions.

In the polymerization of the acrylic resin, a chain transfer agent may be used during the polymerization. A chain transfer agent is not specifically limited, A well-known compound can be used.
Chain transfer agents include, for example, thiol compounds such as dodecyl mercaptan, 2-mercaptoethanol, 3-mercaptopropionic acid, halogen compounds such as chloroform and carbon tetrachloride, polycyclic aromatic quinone compounds, α-methylstyrene dimer, etc. Is mentioned. These chain transfer agents may be used alone or in combination of two or more. The amount of chain transfer agent used is not particularly limited as long as it is appropriately set according to the combination of the monomers, reaction conditions, and the like.

Further, an organic solvent may be added during the polymerization in order to control the viscosity of the polymerization solution and the polymerization temperature. Although it does not specifically limit as a form to add, For example, a polymerization solvent may be continuously added to a polymerization solution, and a polymerization solvent may be added intermittently.
In addition, the polymerization solvent to be added may be, for example, the same type of polymerization solvent as that used at the initial stage of the polymerization reaction or a different type of polymerization solvent. It is preferred to use the same type of solvent that is sometimes used.
Further, the polymerization solvent to be added may be only one kind of single solvent or two or more kinds of mixed solvents. By adding a polymerization solvent during the polymerization of the resin, the viscosity of the polymerization solution in the polymerization tank can be controlled within a certain range, and sufficient stirring can be performed. Branching and cross-linking of the generated polymer chain can be suppressed. In addition, since a polymerization solvent having a temperature lower than the polymerization temperature is added, the polymerization temperature in the polymerization system that generates heat during the polymerization can be easily controlled.

  The polymerization solution after completion of the polymerization may be subjected to a devolatilization step described in JP-A No. 2000-230016, JP-A No. 2007-262396, JP-A No. 2007-262399, and the like. The devolatilization step refers to a step of removing volatile components such as a solvent and a residual monomer under reduced pressure heating conditions as necessary. If this removal treatment is insufficient, the residual volatile components in the produced resin increase, resulting in problems such as coloration due to alteration during molding, and molding defects such as bubbles and silver streaks. The devolatilized acrylic resin can be redissolved in the solvent used at the time of polymerization and a solvent preferable for solution film formation, and used for solution film formation for producing a film.

  The polymer solution containing an acrylic resin containing a ring structure in the main chain obtained as described above reduces foreign matters contained in the acrylic resin by filtering with a filter having a filtration accuracy of 0.01 to 15 μm. Can do. The filtration method is not particularly limited, and may be a conventional method.

[Cellulose ester]
Although the cellulose ester used for this invention is not specifically limited, For example, aromatic carboxylic acid ester, the lower fatty acid ester of a cellulose, etc. are mentioned, Properties, such as optical characteristics (transparency etc.) of the film obtained, improve. Therefore, a lower fatty acid ester of cellulose is preferable.
In the present invention, the lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 5 or less carbon atoms. Examples of the lower fatty acid ester of cellulose include cellulose acetate, cellulose propionate, cellulose butyrate, and cellulose. Pivalate is preferred. These can use 1 type (s) or 2 or more types. A mixed fatty acid ester such as cellulose acetate propionate or cellulose acetate butyrate may be used in order to achieve both the mechanical properties (strength and the like) of the obtained film and the solution film-forming property. Among these, cellulose acetate propionate and cellulose acetate butyrate are preferably used.

  The number average molecular weight (Mn) of the cellulose ester used in the present invention is preferably from 50,000 to 150,000, more preferably from 55,000 to 120,000, and even more preferably from 60000 to 100,000. In addition, the weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of the cellulose ester is preferably 1.3 to 5.5, more preferably 1.5 to 5.0, and 1.7 to 4.0. Is more preferable, and 2.0 to 3.5 is most preferable.

  The method for producing the cellulose ester used in the present invention is not particularly limited, and a cellulose ester produced according to a conventionally known method can be used. For example, the hydroxyl group of the raw material cellulose used as the raw material for cellulose ester can be converted to acetic anhydride. Cellulose ester obtained by substituting acetyl group, propionyl group and / or butyl group by a conventional method using propionic anhydride and / or butyric anhydride can be used. Such a cellulose ester can be produced by referring to, for example, the method described in JP-A-10-45804 or JP-A-6-501040.

  The raw material cellulose is not particularly limited, and examples thereof include wood pulp and cotton linter. The wood pulp includes, for example, pulps such as conifers and hardwoods, and conifer pulps are preferable. As the raw material cellulose, a cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester manufactured from these raw material celluloses can be used individually by 1 type or in mixture as appropriate.

In the present invention, the cellulose ester is preferably dissolved in a solvent in order to be used for solution casting.
The method for dissolving the cellulose ester in the solvent is not particularly limited. For example, the cellulose ester or the additive is dissolved in the organic solvent while stirring in a dissolving kettle to form a cellulose ester solution, and the cellulose ester is previously dissolved in the organic solvent. And a method of forming a cellulose ester solution by mixing the polymer solution and the additive solution therewith. The dissolution method is, for example, a method performed at normal pressure, a method performed at a boiling point or lower of the main solvent, a method performed at a pressure higher than the boiling point of the main solvent, Japanese Patent Laid-Open No. 9-95544, Japanese Patent Laid-Open No. 9-95557, or A dissolution method such as a method performed by the cooling dissolution method described in JP-A-9-95538 and a method performed at a high pressure described in JP-A-11-21379 can be used.

Moreover, as for the density | concentration of the cellulose ester in the said cellulose-ester solution, 10-35 mass% is preferable. An additive excluding the matting agent is added and dissolved in the solution during or after dissolution, and then filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump. The filtration method is not particularly limited, and a conventional method can be used.
The filter medium for filtration preferably has an absolute filtration accuracy of 0.04 mm or less, and more preferably in the range of 0.01 to 0.02 mm. There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, filter fibers made of plastic fibers such as polypropylene and Teflon (registered trademark) and metal filter media such as stainless steel fibers can cause the fibers to fall off. Less preferred.

[Resin composition]
The resin composition of the present invention contains an acrylic resin containing a ring structure in the main chain and the cellulose ester.

  The blending ratio of the acrylic resin containing the ring structure in the main chain and the cellulose ester contained in the resin composition of the present invention is not particularly limited, but the blending ratio of acrylic resin / cellulose ester containing the ring structure in the main chain ( (Mass ratio) is usually 5/95 to 95/5, preferably 20/80 to 80/20, and more preferably 30/70 to 70/30.

  The solubility parameter (SP value) of the acrylic resin and cellulose ester contained in the resin composition of the present invention is a value obtained by subtracting the SP value of the acrylic resin from the SP value of the cellulose ester. Or less, more preferably from −0.9 to 0.9, and even more preferably from −0.7 to 0.7. Note that the SP value is a value calculated using the method described in Examples described later. The smaller the difference in SP value between resins, the better the compatibility between resins.

  The glass transition temperature (Tg) of the resin composition of the present invention is not particularly limited, but is usually 120 ° C or higher, preferably 120 ° C or higher and 170 ° C or lower, more preferably 122 ° C or higher and 150 ° C or lower. . Within these ranges, the heat resistance of the resin composition of the present invention is sufficiently high, and the flexibility of a molded product such as a film obtained by molding the resin composition is easily ensured. It is preferable because it is suitable for applications such as optical films.

  In addition, it can confirm that the acrylic resin and cellulose ester are thermodynamically compatible by measuring the glass transition point of the resin composition obtained by mixing these. Specifically, it can be said that the resin composition is thermodynamically compatible by observing only one glass transition point of the resin composition by using the method described in Examples described later. When thermodynamically compatible, the resin composition generally has high transparency. When two or more glass transition points of the resin composition are observed, it is thermodynamically incompatible and the transparency of the resin composition is generally low. However, even when two or more glass transition points are observed and thermodynamically incompatible, the resin composition may have high transparency depending on the combination of resins contained in the resin composition. At this time, the difference in the refractive index of each resin in the resin composition is relatively small, and it is considered that the resin is microdispersed so as to have a domain sufficiently smaller than the wavelength of visible light.

The resin composition of the present invention may contain compounds other than essential compounds (acrylic resin and cellulose ester) as long as the effects of the present invention are exhibited. These may be added during or after polymerization of the acrylic resin, may be added during or after the production of the cellulose ester, or may be added to a resin composition containing the acrylic resin and the cellulose ester. .
Although it does not specifically limit as compounds other than the said essential compound, For example, a ultraviolet absorber, antioxidant, another additive, another resin component, etc. are mentioned. These can use 1 type (s) or 2 or more types.

The ultraviolet absorber (UVA) is not limited as long as it is a substance that has ultraviolet absorbing ability and is compatible with the resin composition of the present invention. It is preferable that UVA does not contain a repeating unit derived from a monomer (that is, it is not a polymer). The ultraviolet absorber that is a polymer is generally difficult to ensure compatibility with the resin composition, and is obtained by further molding the resin composition with an additive such as a polymerization initiator remaining in the polymer. Coloring may occur in the molded body.
As UVA, for example, at least one selected from a benzophenone compound, a silicate compound, a benzoate compound, a triazole compound, and a triazine compound can be used. Of these, UVA, which is a triazole compound and a triazine compound, is preferable because of its high ultraviolet absorption ability.

  Triazole compounds include, for example, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (3 5-Di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl)- 4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazol-2-yl-4,6-di-t-butylphenol, 2- [5-chloro (2H) -benzotriazole-2 -Yl] -4-methyl-6- (t-butyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-di-t-butylphenol, 2- (2H-ben Triazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5, 6-tetrahydrophthalimidylmethyl) phenol, methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product, 2 -(2H-benzotriazol-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy- 3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 3- (2H-benzotriazol-2-yl) -5 It is a (1,1-dimethylethyl) -4-hydroxy -C7-9 side chain and straight-chain alkyl ester. A triazole compound having a halogen atom, such as a chlorine atom, is preferred because of its high ultraviolet absorption ability.

  Examples of triazine compounds include 2,4-diphenyl-6- (2-hydroxy-4-methoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-ethoxy). Phenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-propoxyphenyl) -1,3,5-triazine, 2,4-diphenyl- (2-hydroxy-4-butoxy) Phenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy) -4-hexyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, , 4-Diphenyl-6- (2-hydroxy-4-dodecyloxyphenyl) -1,3,5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-benzyloxyphenyl) -1,3 , 5-triazine, 2,4-diphenyl-6- (2-hydroxy-4-butoxyethoxy) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butoxyphenyl) -6 (2,4-dibutoxyphenyl) -1,3-5-triazine, 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine, 2 , 4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyloxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (a Rukyloxy; long chain alkyloxy groups such as octyloxy, nonyloxy, decyloxy, etc.). Among them, 2,4-bis (2,4-dimethylphenyl) -6- [2-hydroxy-4- (3-alkyl) has high compatibility with acrylic resins and excellent ultraviolet absorption performance. UVA having an oxy-2-hydroxypropyloxy) -5-α-cumylphenyl] -s-triazine skeleton (alkyloxy; long-chain alkyloxy groups such as octyloxy, nonyloxy, decyloxy, etc.) is preferred.

  The molecular weight of UVA is not particularly limited, but is preferably 600 or more. The upper limit of the molecular weight of UVA is, for example, 10,000. When the molecular weight of UVA becomes excessively large, the compatibility with the resin composition decreases, and the optical transparency of the resin composition of the present invention and the molded product obtained by molding the composition decreases. The upper limit of the molecular weight of UVA is preferably 8000, more preferably 5000.

UVA may be a commercially available substance, such as ADK STAB LA-31, LA-F70 (both manufactured by ADEKA), Tinuvin 1577, Tinuvin 460, and Tinuvin 477 (all manufactured by BASF).
The UV absorption ability of UVA is 10000 (L · mol ⁻¹ · cm ⁻¹ ) in terms of a molar extinction coefficient (chloroform solution) with respect to light having a wavelength within the wavelength range of 300 to 380 nm and the maximum absorption by UVA. The above is preferable.
UVA may be a mixture of two or more compounds.

  When the resin composition of this invention contains UVA, the content rate of UVA in the said composition is 0.1-5 mass parts with respect to 100 mass parts of the said resin compositions, for example, and 0.5-5 mass Part is preferable, and 0.7 to 3 parts by mass, 1 to 3 parts by mass, and 1 to 2 parts by mass are more preferable. If the UVA content is excessively small, the desired ultraviolet absorbing ability cannot be obtained. On the other hand, if the UVA content is excessively high, the disadvantages such as foaming and bleeding out during molding of the resin composition, and the coloring of the resin composition become stronger than the merit of obtaining the ultraviolet absorbing ability. Becomes larger.

  Although it does not specifically limit as antioxidant, For example, well-known antioxidants, such as a hindered phenol type, a phosphorus type, or a sulfur type, are raised. These can be used individually by 1 type or in combination of 2 or more types. Examples of commercially available products include “ADK STAB 2112” (manufactured by ADEKA) as a hindered phenol-based antioxidant.

The antioxidant may be a phenolic antioxidant.
Examples of the phenolic antioxidant include n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, n-octadecyl-3- (3,5-di-t-butyl- 4-hydroxyphenyl) acetate, n-octadecyl-3,5-di-t-butyl-4-hydroxybenzoate, n-hexyl-3,5-di-t-butyl-4-hydroxyphenylbenzoate, n-dodecyl- 3,5-di-t-butyl-4-hydroxyphenylbenzoate, neododecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, dodecyl-β- (3,5-di-t -Butyl-4-hydroxyphenyl) propionate, ethyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, Kutadecyl-α- (4-hydroxy-3,5-di-t-butylphenyl) isobutyrate, octadecyl-α- (4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2- (N-octylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (n-octylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- ( n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxyphenyl acetate, 2- (n-octadecylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-hydroxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, diethyl glycol bis- (3,5-di- t-butyl-4-hydroxy-phenyl) propionate, 2- (n-octadecylthio) ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, stearamide-N, N-bis- [Ethylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], n-butylimino-N, N-bis- [ethylene-3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], 2- (2-stearoyloxyethylthio) ethyl-3,5-di-t-butyl-4-hydroxybenzoate, 2- (2-stearoyloxyethylthio) ethyl-7- ( 3-methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,2-propylene glycol bis- [3- (3,5-di- -Butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], neopentyl glycol bis- [3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionate], ethylene glycol bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), glycerin-1-n-octadecanoate-2,3 -Bis- (3,5-di-t-butyl-4-hydroxyphenyl acetate), pentaerythritol tetrakis- [3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate], 1,1,1-trimethylolethanetris- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propyl Pionate], sorbitol hexa- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2-hydroxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) ) Propionate, 2-stearoyloxyethyl-7- (3-methyl-5-tert-butyl-4-hydroxyphenyl) heptanoate, 1,6-n-hexanediol bis [(3 ', 5'-di-t- Butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis (3,5-di-t-butyl-4-hydroxyhydrocinnamate), 3,9-bis [1,1-dimethyl-2- [β- ( 3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl] -2,4,8,10-tetraoxaspir [5,5] - undecane.

The phenol-based antioxidant is preferably used in combination with a thioether-based antioxidant or a phosphate-based antioxidant.
The amount of the antioxidant added when these are combined is not particularly limited, but the phenolic antioxidant and the thioether antioxidant are each 0.01 parts by mass with respect to 100 parts by mass of the resin composition of the present invention. It is preferable that each of the phenolic antioxidant and the phosphoric acid antioxidant is 0.025 parts by mass or more.

  Examples of the thioether-based antioxidant include pentaerythrityl tetrakis (3-lauryl thiopropionate), dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl- 3,3′-thiodipropionate and the like.

  Examples of the phosphoric acid antioxidant include tris (2,4-di-t-butylphenyl) phosphite, 2-[[2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo [d. , F] [1,3,2] dioxaphosphin-6-yl] oxy] -N, N-bis [2-[[2,4,8,10-tetrakis (1,1 dimethylethyl) dibenzo [D, f] [1,3,2] dioxaphosphin-6-yl] oxy] -ethyl] ethanamine, genyltridecyl phosphite, triphenyl phosphite, 2,2-methylenebis (4,6- Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, Lee neopentane tetraylbis (2,6-di -t- butyl-4-methylphenyl) phosphite, and the like.

  Although the compounding quantity of the said antioxidant is not specifically limited, 0.01-2 mass parts normally with respect to 100 mass parts of resin compositions of this invention, Preferably it is 0.02-1 mass parts, More preferably It is 0.02-0.5 mass part. When the amount of the antioxidant added is excessively large, antioxidant bleed out and silver streaks may occur during molding of the resin composition of the present invention.

  Other additives contained in the resin composition of the present invention include, for example, light stabilizers, weather stabilizers, heat stabilizers and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; near infrared absorbers; Flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; antistatic agents typified by anionic, cationic and nonionic surfactants; colorants such as inorganic pigments, organic pigments, dyes; Examples include organic fillers, inorganic fillers, resin modifiers, antiblocking agents, matting agents, acid scavengers, metal deactivators, plasticizers, lubricants, flame retardants, and rubber masses such as ASA and ABS.

  The compounding amount of the other additives contained in the resin composition of the present invention is not particularly limited, but is usually 0 to 5 parts by mass with the exception of UVA with respect to 100 parts by mass of the resin composition of the present invention. More preferably, it is 0-2 mass parts, More preferably, it is 0-1 mass part.

  Although it does not specifically limit as said other resin component contained in the resin composition of this invention, For example, a thermoplastic resin etc. are mentioned. Examples of the thermoplastic resin include olefin polymers such as polyethylene, polypropylene, ethylene-propylene copolymer, and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resins; polystyrene, styrene- Styrene polymers such as methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; nylon 6, nylon 66, nylon 610 Polyacetal: Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide: Polyether ether ketone; Polyether nitrile; Polysulfone; Terusaruhon; polyoxyethylene Penji alkylene; polyamideimide; and the like. These may contain 1 type, or 2 or more types.

  Among the thermoplastic resins exemplified above, a copolymer containing a constitutional unit derived from a vinyl cyanide monomer and a constitutional unit derived from an aromatic vinyl monomer is provided because of excellent compatibility with an acrylic resin. preferable. The copolymer is, for example, a styrene-acrylonitrile copolymer.

[Optical film]
This invention contains the optical film containing the resin composition of this invention.
The optical film of the present invention can be formed into an arbitrary shape (for example, film or sheet) by using the resin composition of the present invention by a conventionally known molding method such as injection molding, blow molding, extrusion molding, cast molding, or the like. It can be obtained by molding into.

  Although the thickness of the optical film of this invention is not specifically limited, Usually, they are 10 micrometers-500 micrometers, Preferably they are 20 micrometers-300 micrometers, More preferably, they are 30 micrometers-100 micrometers.

  The total light transmittance of the optical film of the present invention is not particularly limited, but is usually 85% or more, preferably 90% or more, and more preferably 91% or more. The total light transmittance is a measure of the transparency of the optical film, and if it is less than 85%, the transparency is lowered and it is not suitable as an optical film.

  The optical film of the present invention is less colored, and the b value per 250 μm thickness is preferably 0.5 or less, more preferably 0.3 or less.

  The haze of the optical film of the present invention is preferably 5% or less, more preferably 3% or less. If the haze exceeds 5%, the transmittance is lowered and may not be suitable for optical applications.

The photoelastic coefficient (Cd) of the optical film of the present invention is not particularly limited, but the photoelastic coefficient (Cd) of a film having a thickness of 50 μm is preferably −12 × 10 ^{−12 to} 12 × 10 ⁻¹² / Pa. More preferably, it is −10 × 10 ⁻¹² to 10 × 10 ⁻¹² / Pa. The photoelastic coefficient (Cd) is a value calculated using the method described in Examples described later.

[Method for producing optical film]
The production method of the optical film of the present invention is not particularly limited, and examples thereof include a solution casting method (solution casting method), a melt extrusion method, a calendering method, a compression molding method, and the like. Preferably, the solution casting method (solution Casting method) and melt extrusion method, more preferably solution casting method (solution casting method). Conventionally known methods can be used for these.

  When the optical film of the present invention is produced by a solution casting method, a method having (1) a dissolution step, then (2) a casting step, and then (3) a drying step is preferable.

(1) Dissolution process:
The dissolution step is a step of producing a composition used in the production of the optical film of the present invention. Specifically, the acrylic resin and cellulose ester containing a ring structure in the main chain, and if necessary, UV absorption It is a step of preparing a solution containing the resin composition of the present invention containing an agent, an antioxidant, other additives, other resin components, and the like, and, if desired, a solvent.

  In the production of the composition, when the acrylic resin containing a cyclic structure in the main chain and the cellulose ester are dissolved in a solvent, the acrylic resin containing the cyclic structure in the main chain and the cellulose ester are separately dissolved in the solvent before the solution. They may be mixed together or dissolved in the same solvent at the same time. In the present invention, the acrylic resin containing a ring structure in the main chain can be used in the dissolving step in a polymerization solution containing a polymerization solvent without going through a devolatilization step, and a separately prepared cellulose ester solution is used. By adding the acrylic resin solution little by little while stirring, the composition used for solution casting can be prepared without solidifying the cellulose ester. After the necessary additive is added and dissolved in the composition during or after dissolution, it is filtered through a filter medium, defoamed, and sent to the next step with a liquid feed pump. The filter medium for filtration preferably has an absolute filtration accuracy of 0.04 mm or less, and more preferably in the range of 0.01 to 0.02 mm. There is no particular limitation on the material of the filter medium, and a normal filter medium can be used. However, a filter medium made of plastic fibers such as polypropylene and Teflon and a metal filter medium such as stainless steel fibers are preferable because they do not drop off fibers.

  The solvent for dissolving the acrylic resin or cellulose ester having a ring structure in the main chain is not particularly limited, but for example, a good solvent used in a solution casting method such as methylene chloride, methyl acetate, dioxolane, etc. can be used. Simultaneously, a poor solvent such as methanol, ethanol, or butanol may be used. In the present invention, a polymerization solvent contained in an acrylic resin polymerization solution containing a ring structure in the main chain can also be used. These solvents can be used alone or in combination of two or more. Moreover, you may cool to -20 degrees C or less in the process of dissolution, or you may heat to 80 degrees C or more.

As a method for preparing the cellulose ester solution, for example, the cellulose ester and other necessary resins and additives are dissolved in an organic solvent mainly containing a good solvent for cellulose ester (flakes) while stirring. Or a method of mixing other resin solution or additive solution with the cellulose ester solution.
The method for dissolving the cellulose ester is not particularly limited. For example, the method is carried out at normal pressure, the method is carried out below the boiling point of the main solvent, the method is carried out under pressure above the boiling point of the main solvent, JP-A-9-95544, A method of performing the cooling and melting method described in JP-A-9-95557 or JP-A-9-95538, a method of performing at a high pressure described in JP-A-11-21379, and the like can be used.

  The ratio of the acrylic resin containing a ring structure in the main chain contained in the composition used for the production of the optical film of the present invention is not particularly limited, but usually 70 to 30 mass relative to the total amount of the composition. % Is preferred. Moreover, the ratio of the cellulose ester contained in the composition is not particularly limited, but is usually preferably 30 to 70% by mass with respect to the total amount of the composition.

  The viscosity of the composition used for the production of the optical film of the present invention is preferably 10 poise to 100 poise, more preferably 15 poise to 70 poise. When the composition has a low viscosity, (2) when the composition is applied in the casting step, the film thickness is preferably uniformed by the leveling effect. Further, if the viscosity of the composition is lower than 10 poise, (2) since it flows out from the support in the casting step, it is necessary to take measures such as appropriately providing a partition plate.

(2) Casting process:
In this process, the composition used for producing the optical film of the present invention is cast on a support to obtain a uniform film.

Generally, if a deformation stress is applied in the film forming process, the orientation proceeds and the birefringence value of the film increases. As the birefringence value increases, it becomes difficult to maintain the uniformity of the film and the variation in optical characteristics also increases. Therefore, it is desirable to form a film under a relatively small stress with the viscosity of the composition being low. .

  The coating method for casting the composition on a support is not particularly limited, and a conventionally known coating method can be used. For example, a die coater, a doctor blade coater, a roll coater, a comma coater, A method using a lip coater or the like is preferable. These may use conventional methods.

  The support for casting the composition is not particularly limited, and a conventionally known support used for solution casting can be used. Examples thereof include a stainless steel endless belt and a rotating metal drum. Examples thereof include a metal support, a film such as a polyimide film and a biaxially stretched polyethylene terephthalate film.

(3) Drying process:
A step of heating a film of the composition obtained by casting the composition used for the production of the optical film of the present invention on a support and evaporating the solvent to obtain a dry film (heating and drying the film of the composition) It is.

In heat drying, in the state where the liquid film immediately after casting or application of the composition is not dry, if there is a rapid wind flow or heating, etc., thickness unevenness is likely to occur, so take care to eliminate thickness unevenness It is preferable to dry. For example, it is preferable not to give wind directly to the film, or to use a means of heating by applying a microwave instead of the wind.
It is also preferable to prevent rapid heating / cooling. Furthermore, since the film | membrane of the said composition foams with the humidity in atmosphere, the state which controlled humidity is preferable. After these are dried to be in a semi-solid state, it is preferably dried by blowing hot air or the like so as to reduce the residual solvent.

Heat drying can be performed with the film of the composition supported on the support, but if necessary, the pre-dried film is peeled from the support until it has self-supporting property, It can also be dried.
The heat drying method is not particularly limited, and a conventionally known method can be used. For example, a float method, a tenter method, a roll conveying method, or the like can be used.
In the case of the float process, the film itself is subjected to complicated stress, and optical characteristics are likely to be uneven. In the case of the tenter method, it is necessary to balance the film width shrinkage due to solvent drying and the tension to support its own weight depending on the distance between the pins or clips that support both ends of the film. There is a need. On the other hand, in the case of the roll conveyance method, since the tension for stable film conveyance is in principle applied to the film flow direction (MD direction), it has a characteristic that the direction of stress is easily made constant. Therefore, the film is most preferably dried by a roll conveyance method. Above all, in order to reduce the stress caused by gravity, the vertical path method (vertical suspension path method) that arranges multiple rolls on the top and bottom and passes the film up, down, up, down, etc. is a long drying path while omitting the oven installation space. Can be ensured.
Further, drying in an atmosphere kept at a low humidity so that the film does not absorb moisture when the solvent is dried is an effective method for obtaining a film having high mechanical strength and transparency.

  In addition to the steps (1) to (3) described above, the optical film production process of the present invention includes saponification treatment, corona treatment, plasma treatment, and further application of an easy-adhesion layer, etc. You may have a process. It is also possible to have a process of providing a functional coating layer and a stretching process. The method of these processes, application | coating, coating, and extending | stretching is not specifically limited, A conventionally well-known method can be used.

  Examples of the functional coating layer include an antistatic layer, an adhesive layer, an adhesive layer, an easy-adhesion layer, an antiglare layer (non-glare) layer, an antifouling layer such as a photocatalyst layer, an antireflection layer, a hard coat layer, and an ultraviolet ray. Examples thereof include a shielding layer, a heat ray shielding layer, an electromagnetic wave shielding layer, and a gas barrier layer. The method for forming these functional coating layers is not particularly limited, and may be according to a conventional method.

  The stretching method may be uniaxial stretching or biaxial stretching. When biaxial stretching, simultaneous biaxial stretching or sequential biaxial stretching may be used. When stretched, the mechanical strength of the film is improved and the film performance is improved.

  Although it does not specifically limit as temperature of the said extending | stretching, For example, it is preferable to carry out in the glass transition temperature vicinity of an optical film. Specifically, it is preferably performed at (glass transition temperature −30) ° C. to (glass transition temperature +100) ° C., and (glass transition temperature −20) ° C. to (glass transition temperature +80) ° C. of the optical film. More preferred. When it is lower than (glass transition temperature-30) ° C., a sufficient draw ratio cannot be obtained, which is not preferable. On the other hand, a temperature higher than (glass transition temperature + 100) ° C. is not preferable because a resin flow occurs and stable stretching cannot be performed.

  The stretching ratio is not particularly limited, but the court stretching ratio defined by the area ratio is preferably in the range of 1.1 to 25 times, more preferably in the range of 1.3 to 10 times. When it is less than 1.1 times, it is not preferable because it does not lead to improvement of toughness accompanying stretching. If it is larger than 25 times, the effect of increasing the draw ratio is not recognized.

  Although it does not specifically limit as the speed | rate (one direction) of the said extending | stretching, Preferably it is the range of 10-20000% / min, More preferably, it is the range of 100-10000% / min. If it is slower than 10% / min, it takes time to obtain a sufficient draw ratio, and the production cost is increased, which is not preferable. If it is faster than 20000% / min, the optical film may be broken, which is not preferable.

In order to stabilize the optical isotropy and mechanical properties of the film, heat treatment (annealing) or the like may be performed after the solution film formation or after the stretching process.

  Moreover, as for the optical film of this invention, the various functional coating layers may be formed in the film surface as needed. Functional coating layers include, for example, antistatic layers, adhesive layers, adhesive layers, easy adhesion layers, antiglare (non-glare) layers, antifouling layers such as photocatalyst layers, antireflection layers, hard coat layers, and UV shielding Layer, heat ray shielding layer, electromagnetic wave shielding layer, gas barrier layer and the like. The method for forming these functional coating layers is not particularly limited, and may be according to a conventional method.

Although the use of the optical film of the present invention obtained as described above is not particularly limited, it can be suitably used as an optical member due to its high transparency and heat resistance.
Although it does not specifically limit as an optical member, For example, an optical protective film etc. are mentioned, Specifically, the protective film of various optical disk (VD, CD, DVD, MD, LD, etc.) board | substrates, a liquid crystal display device ( Examples thereof include a polarizer protective film used for a polarizing plate provided in an image display device such as an LCD).
The optical film of the present invention can be used as a retardation film, a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, a conductive film for a touch panel, and the like. The optical film of the present invention is particularly suitably used as a polarizer protective film or a retardation film.

<Polarizer protective film>
The optical film of the present invention can be used as a polarizer protective film used for a polarizing plate provided in an image display device such as a liquid crystal display device (LCD), and the present invention is a polarized light using the optical film of the present invention. Also contains a child protective film. The optical film of the present invention can usually be used as a polarizer protective film as it is.

<Polarizing plate>
The present invention also includes a polarizing plate having the optical film of the present invention.
That is, the optical film of the present invention can be used as a polarizer protective film for a polarizing plate.
In this invention, the manufacturing method of a polarizing plate is not specifically limited, You may follow a conventionally well-known method. For example, a polarizing plate can be obtained by bonding the optical film of the present invention to at least one surface of a polarizer using a conventional method. In the bonding, the side of the optical film of the present invention bonded to the polarizer is subjected to alkali saponification treatment, and after applying a completely saponified polyvinyl alcohol aqueous solution to at least one surface of the polarizer, the optical film of the present invention and the polarizer are combined. It can implement suitably by bonding.

  The polarizer is an element that passes only polarized waves in a certain direction. The polarizer used in the present invention is not particularly limited, and conventionally known polarizers can be used, and examples thereof include a polyvinyl alcohol film. As a polyvinyl alcohol-type film, what dye | stained the iodine and what dye | stained the dichroic dye can be used.

The polyvinyl alcohol film is formed, for example, by forming a polyvinyl alcohol aqueous solution and uniaxially stretching it to dye or dyeing it and then uniaxially stretching it, and then preferably performing a durability treatment using a boron compound. Etc. can be used suitably.
Moreover, 5-30 micrometers is preferable and, as for the film thickness of a polarizer, 10-20 micrometers is more preferable.

<Image display device>
The present invention also includes an image display device having the polarizing plate of the present invention described above.
In the present invention, the manufacturing method of the image display device is not particularly limited, and may be a conventionally known method. As the image display device, a liquid crystal display device (LCD) or the like is preferable.

  The liquid crystal display device is usually composed of a liquid crystal cell and polarizing plates disposed on both sides thereof, and it is preferable to dispose the optical film of the present invention in contact with the liquid crystal cell. Moreover, it is preferable to further laminate | stack a prism sheet and a diffusion film in a liquid crystal display device using a conventional method.

The present invention will be specifically described with reference to the following examples and comparative examples, but the present invention is not limited thereto.
Initially, the evaluation method of the resin composition produced in the present Example is shown.

[Weight average molecular weight and number average molecular weight]
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the acrylic resin were determined by gel permeation chromatography (GPC) in terms of polystyrene. The apparatus and measurement conditions used for the measurement are as follows.
System: Tosoh GPC system HLC-8220
Measurement column configuration:
Guard column (manufactured by Tosoh, TSK guard column Super HZ-L)
・ Two separation columns (manufactured by Tosoh, TSKgel SuperHZM-M) in series connection Reference side column configuration:
・ Reference column (manufactured by Tosoh Corporation, TSKgel SuperH-RC)
Developing solvent: Chloroform (Wako Pure Chemical Industries, special grade)
Flow rate of developing solvent: 0.6 mL / min Standard sample: TSK standard polystyrene (manufactured by Tosoh, PS-oligomer kit)
Column temperature: 40 ° C

[Glass transition temperature (Tg)]
The glass transition temperature (Tg) of the acrylic resin and the optical film was determined in accordance with JIS K7121 regulations. Specifically, using a differential scanning calorimeter (Rigaku, Thermo plus EVO DSC-8230), a sample of about 10 mg was heated from room temperature to 200 ° C. (heating rate 20 ° C./min) in a nitrogen gas atmosphere. From the DSC curve obtained in this way, the starting point method was used for evaluation. Α-alumina was used as a reference.

[Calculation of SP value]
About SP value (solubility parameter), Materials Studio R Ver. 6.1 Can be calculated using the MS-Synthia module. First, a monomer structure is created and a repeating structure is defined. Using the defined monomer structure, polymer physical properties (solubility parameters, etc.) are calculated with the MS-Synthia module. The MS-Synthia module is a software that can calculate the physical properties of polymers by using Quantitative Structure Property Relationships (QSPR). Physical properties can be calculated. Detailed theory is described in Document 1 below. This time, the value of van Krevelen method was used among SP values (solubility parameters) of Fedors method and van Krevelen method improved by Bicerano that can be calculated by MS-Synthia.
(Reference 1)
Title: “Prediction of Polymer Properties, Third Edition”
Author: Josef Bicerano
Publisher: Marcel Dekker Ink. , New York
Copyright: 2002

[Photoelastic coefficient (Cd)]
The photoelastic coefficient (Cd) of the acrylic resin was determined as follows. First, an acrylic resin was melt-extruded to obtain a film (unstretched film) having a thickness of 100 μm. Next, the film was cut into a rectangle having a width of 7 mm to obtain a test piece. Next, the cut out test piece is mounted at a distance of 30 mm between chucks on a retardation film / optical material inspection apparatus RETS-100 (manufactured by Otsuka Electronics Co., Ltd.) equipped with a tensile tester stage, and an elongation stress ( (σR) was applied (chuck moving speed 5 mm / min), and its birefringence with respect to light having a wavelength of 590 nm was measured. From the relationship between the measured absolute value of birefringence (| Δn |) and the tensile stress (σR) applied to the test piece, the slope | Δn | / σR was determined by the least square method, and the photoelastic coefficient (Cd) was calculated. (Cd = | Δn | / σR). For the calculation of Cd, data in which the tensile stress is in the range of 2.5 MPa ≦ σR ≦ 10 MPa was used. | Δn | is | Δn | = | nx−ny |.
The Cd of the optical film was determined in the same manner as in the case of the acrylic resin, except that the film having a thickness of 50 μm was used for the measurement as it was.

[Haze]
The haze of the produced optical film was determined in accordance with JIS K7136 using a turbidimeter (Nippon Denshoku Industries, NDH-5000).

[Film thickness]
The thickness of the film obtained by molding the acrylic resin and the optical film was determined with a Digimatic micrometer (manufactured by Mitutoyo Corporation).

[Flexibility = Ductile fracture]
The flexibility was evaluated by the following ductile fracture test.
An optical film conditioned for 24 hours in an air-conditioned room at 23 ° C. and 55% RH is cut out at 100 mm (length) × 10 mm (width) under the conditions of 5 ° C. and 22% RH. The film was folded once into a mountain fold and a valley fold so that the film was exactly overlapped at 0 mm and a folding angle of 180 °, and this evaluation was measured 10 times and evaluated as follows. In addition, "break" by evaluation here represents that it broke and separated into two or more pieces.
○ ・ ・ ・ Cannot be folded out of 10 times × ・ ・ ・ Folded once or more in 10 times

[acrylic resin]
(Production Example 1)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, a nitrogen introducing pipe, and a dropping funnel, 90 parts by mass of methyl methacrylate (MMA), 10 parts by mass of N-cyclohexylmaleimide (CMI), an antioxidant (ADK STAB 2112) ADEKA) and 0.05 parts by mass of toluene and 80.5 parts by mass of toluene were charged, and the contents were heated to 105 ° C. while introducing nitrogen gas. At the start of the reflux due to the temperature rise, 0.103 parts by mass of t-amylperoxyisononanoate (manufactured by Arkema Yoshitomi, Luperox 570) was added as a polymerization initiator, and t-amylperoxy was added to 21 parts by mass of toluene. Solution polymerization was allowed to proceed while dropping 0.205 parts by mass of isononanoate over 2 hours, and after completion of the dropwise addition, aging was further performed for 6 hours. Subsequently, the obtained polymerization solution was dried at 240 ° C. under a reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-1).

(Production Example 2)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, a nitrogen introduction pipe, and a dropping funnel, 80 parts by mass of MMA, 20 parts by mass of CMI, 0.05 part by mass of an antioxidant (ADK STAB 2112, manufactured by ADEKA), and xylene 99 4 parts by mass were charged, and the content was heated to 100 ° C. while introducing nitrogen gas. Thereafter, as a polymerization initiator, a solution prepared by dissolving 0.16 parts by mass of 1,1-di (t-butylperoxy) cyclohexane (manufactured by NOF Corporation, Perhexa C) in 0.48 parts by mass of xylene was added all at once. Solution polymerization was allowed to proceed, and aging was performed for 3.5 hours. Subsequently, the obtained polymerization solution was poured into 1000 parts by mass of methanol and reprecipitated to remove residual monomers and solvents. The obtained polymer solid was dried at 240 ° C. under a reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-2).

(Production Example 3)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, a nitrogen introduction tube, and a dropping funnel, 75 parts by mass of methyl methacrylate (MMA), 20 parts by mass of CMI, 0.1 mass of dodecyl mercaptan (DM) as a chain transfer agent Part, an antioxidant (ADK STAB 2112, manufactured by ADEKA) 0.05 part by mass and toluene 30.2 part by mass were charged with nitrogen gas, and the content was heated to 105 ° C. When the reflux accompanying the temperature increase started, 0.052 parts by mass of t-amylperoxyisononanoate (manufactured by Arkema Yoshitomi, Luperox 570) was added as a polymerization initiator. Subsequently, Solution 1 (a solution in which 0.205 parts by mass of t-amylperoxyisononanoate was dissolved in 21 parts by mass of toluene) and 5.0 parts by mass of styrene (St) were respectively added over 2 hours and 30 minutes. The solution polymerization was carried out dropwise, and after completion of the dropwise addition of the solution 1, aging was further performed for 6 hours. Subsequently, the obtained polymerization solution was dried at 240 ° C. under a reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-3).

(Production Example 4)
In a reaction vessel equipped with a stirrer, temperature sensor, cooling tube, nitrogen introduction tube, and dropping funnel, 100 parts by mass of methyl methacrylate (MMA), 0.1 part by mass of dodecyl mercaptan (DM) as a chain transfer agent, antioxidant 0.05 parts by mass of an agent (Adeka Stub 2112, manufactured by ADEKA) and 80.5 parts by mass of toluene were charged, and the content was heated to 105 ° C. while introducing nitrogen gas. At the start of the reflux due to the temperature rise, 0.103 parts by mass of t-amylperoxyisononanoate (manufactured by Arkema Yoshitomi, Luperox 570) was added as a polymerization initiator, and t-amylperoxy was added to 21 parts by mass of toluene. Solution polymerization was allowed to proceed while dropping 0.205 parts by mass of isononanoate over 2 hours, and after completion of the dropwise addition, aging was further performed for 6 hours. Subsequently, the obtained polymerization solution was dried at 240 ° C. under a reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-4).

(Production Example 5)
In Production Example 3, the same except that MMA was changed to 90 parts by mass, CMI to 5 parts by mass, initial charge of toluene to 100 parts by mass, and initial t-amylperoxyisonanoate to 0.205 parts by mass. Operation was performed to obtain an acrylic resin (A-5).

(Production Example 6)
In a plate-like container formed using two identical glass plates, MMA 21.5 parts by mass, CMI 2.5 parts by mass, methyl acrylate (MA) 1.0 part by mass, dimethyl 2,2′-azobis (2 -Methylpropionate) 0.0375 parts by mass and 5.0 parts by mass of toluene were charged, and the mixture was heated in a hot water bath at 80 ° C. for 3 hours to perform a stationary polymerization reaction. The obtained acetone solution of the polymer was poured into methanol and reprecipitated to remove the remaining monomer and solvent. The obtained polymer solid was dried at 240 ° C. under reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-6).

(Production Example 7)
The same operation as in Production Example 1 was performed except that 90 parts by mass of MMA was changed to 91 parts by mass and 10 parts by mass of CMI was changed to 3 parts by mass of N-phenylmaleimide (PMI) and 6 parts by mass of CMI, and acrylic resin (A-7) was obtained. Obtained.

(Production Example 8)
MMA 70 parts by weight, PMI 13 parts, CMI 17 parts by mass, and xylene 66.7 parts by mass were introduced into a reaction vessel equipped with a stirrer, temperature sensor, cooling pipe, nitrogen introduction pipe, and dropping funnel, and nitrogen gas was introduced into this. However, the contents were heated to 120 ° C. Thereafter, as a polymerization initiator, a solution prepared by dissolving 0.20 parts by mass of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, perbutyl O) in 20 parts by mass of xylene was dropped in 6 hours. After completion, aging was further performed for 2 hours. Subsequently, the obtained polymerization solution was dried at 240 ° C. under a reduced pressure of 0.01 MPa for 1 hour to obtain an acrylic resin (A-8).

Example 1
[Creation of optical film 1]
Dope solution composition / CAP482-20 (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56 manufactured by Eastman Chemical): 70 parts by mass / acrylic resin A-1: 30 masses Parts / methylene chloride: 515 parts by mass / ethanol: 52 parts by mass The above composition was sufficiently dissolved to prepare a dope solution.
This dope solution was uniformly cast on a glass plate using an applicator. The glass film was dried for 30 minutes at room temperature, further dried in an oven at 100 ° C. for 3 minutes, and then peeled off from the glass plate to obtain an optical film 1. The film thickness after drying was 50 μm.

(Example 2)
[Creation of optical film 2]
Except having changed acrylic resin A-1 into acrylic resin A-2, operation similar to Example 1 was performed and the optical film 2 was obtained. The film thickness after drying was 50 μm.

(Example 3)
[Creation of optical film 3]
Dope solution composition / CAP482-20 (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56 manufactured by Eastman Chemical): 50 parts by mass / acrylic resin A-1: 50 masses Parts / methylene chloride: 515 parts by mass / ethanol: 52 parts by mass The above composition was sufficiently dissolved to prepare a dope solution.
This dope solution was uniformly cast on a glass plate using an applicator. The film was dried on the glass plate at room temperature for 30 minutes, further dried in an oven at 100 ° C. for 3 minutes, and then peeled off from the glass plate to obtain an optical film 3. The film thickness after drying was 50 μm.

Example 4
[Creation of optical film 4]
An optical film 4 was obtained in the same manner as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-3. The film thickness after drying was 50 μm.

(Example 5)
[Creation of optical film 8]
An optical film 8 was obtained in the same manner as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-6. The film thickness after drying was 50 μm.

(Example 6)
[Creation of optical film 9]
Except for changing CAP482-20, 70 parts by mass to 30 parts by mass, and changing acrylic resin A-1, 30 parts by mass to acrylic resin A-6, 70 parts by mass, the same operations as in Example 1 were performed, An optical film 9 was obtained. The film thickness after drying was 50 μm.

(Example 7)
[Creation of optical film 10]
An optical film 10 was obtained by performing the same operation as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-7. The film thickness after drying was 50 μm.

(Example 8)
[Creation of optical film 11]
An optical film 11 was obtained in the same manner as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-8. The film thickness after drying was 50 μm.

(Comparative Example 1)
[Creation of optical film 5]
An optical film 5 was obtained in the same manner as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-4. The film thickness after drying was 50 μm.

(Comparative Example 2)
[Creation of optical film 6]
An optical film 6 was obtained in the same manner as in Example 1 except that the acrylic resin A-1 was changed to the acrylic resin A-5. The film thickness after drying was 50 μm.

(Comparative Example 3)
[Creation of optical film 7]
Dope solution composition / CAP482-20 (acyl group total substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56 manufactured by Eastman Chemical): 100 parts by mass / methylene chloride: 515 parts by mass / ethanol : 52 mass parts The said composition was fully melt | dissolved and the dope liquid was created.
This dope solution was uniformly cast on a glass plate using an applicator. The film was dried on the glass plate at room temperature for 30 minutes, further dried in an oven at 100 ° C. for 3 minutes, and then peeled off from the glass plate to obtain an optical film 7. The film thickness after drying was 50 μm.

  Table 1 shows the physical properties of the acrylic resins prepared in Production Examples 1 to 8, and Table 2 shows the evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3. In Table 2, “CAP” indicates CAP482-20 used as the cellulose ester, and “SP value (CAP-acrylic)” is obtained by subtracting the SP value of the acrylic resin from the SP value of the cellulose ester. Show. Moreover, in Table 2, two Tg of the optical film of the comparative example 1, Examples 5-6, and Example 8 was confirmed.

  Comparative Example 1 using an acrylic resin containing no structural unit derived from a substituted maleimide monomer in which the substituent on N is a C3-C12 cycloalkyl group, an acrylic resin having an Mw of less than 120,000 In the comparative example 2 used and the comparative example 3 which does not use an acrylic resin, it was not possible to satisfy all of the photoelastic coefficient, transparency, heat resistance and flexibility of the obtained optical film.

  On the other hand, Examples 1 to 1 using an acrylic resin containing a structural unit derived from a substituted maleimide monomer in which the substituent on N is a C3-C12 cycloalkyl group and having an Mw of 120,000 or more. In No. 8, the obtained optical film had a small photoelastic coefficient, a small haze and excellent transparency, a Tg of 120 ° C. or higher, excellent heat resistance, and excellent flexibility.

  From the above results, the resin composition of the present invention contains a structural unit derived from a substituted maleimide monomer in which the substituent on N is a C3-C12 cycloalkyl group, and the Mw is 120,000 or more. By containing the acrylic resin and cellulose ester, it is possible to obtain an optical film having a small photoelastic coefficient, excellent transparency, heat resistance, and flexibility using the resin composition. it can.

  According to the present invention, since an optical film having a small photoelastic coefficient and excellent balance of transparency, heat resistance, and flexibility can be obtained, an excellent polarizer protective film using the optical film, A polarizing plate and an image display device can be manufactured.

Claims (7)

A resin composition comprising an acrylic resin containing a ring structure in the main chain and a cellulose ester, wherein the ring structure is derived from a substituted maleimide monomer in which the substituent on N is a C3-C12 cycloalkyl group The ratio of the ring structure is 7% by mass or more and 30% by mass or less with respect to the total amount of the acrylic resin, and the weight average molecular weight (Mw) of the acrylic resin is 120,000 or more. Resin composition [However, the following general formula (1)
(In the formula, R ₁ represents a hydrogen atom, an alkyl group, a cycloalkyl group, or an aryl group, and R ₂ and R ₃ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. N is 0 or 1 is represented.)
And a resin composition containing a polymer (A) having at least one repeating unit represented by general formula (A) having at least one repeating unit composed of a monomer having a hydroxyl group or an amide bond, and a cellulose ester . The acrylic resin containing a ring structure in the main chain includes a structural unit derived from a (meth) acrylate monomer in the main chain, and the structural unit is methyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid. The resin composition according to claim 1, which is a structural unit derived from at least one monomer selected from butyl, cyclohexyl methacrylate, benzyl methacrylate, dicyclopentanyl acrylate, and dicyclopentanyl methacrylate. object. The resin composition according to claim 1 or 2 , wherein a glass transition temperature of the resin composition is 120 ° C or higher. An optical film comprising the resin composition according to any one of claims 1 to 3 . The optical film of Claim 4 is used, The polarizer protective film characterized by the above-mentioned.   A polarizing plate comprising the optical film according to claim 4. An image display device comprising the polarizing plate according to claim 6 .