Resin composition, and optical film using the same

Abstract

To provide an optical film excellent in storage elastic modulus under a high temperature using a resin composition excellent in retardation characteristics.SOLUTION: A resin composition contains fumaric acid ester polymer having a fumaric acid diester residue, and a cyclic siloxane compound or a cyclic silane compound. The cyclic siloxane compound includes octaphenylcyclotetrasiloxane, decaphenylcyclopentasiloxane, dodecaphenylcyclohexasiloxane, hexadecaphenylcyclooctasiloxane, and the like, and the cyclic silane compound includes octaphenylcyclotetrasilane, decaphenylcyclopentasilane, dodecaphenylcyclohexasilane, hexadecaphenylcyclooctasilane, and the like.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition suitable as an optical material. [Background technology]

[0002] Liquid crystal displays (LCDs) are the most important display devices in our multimedia society, and are widely used in everything from mobile phones and computer monitors to laptops and televisions. Many optical films are used as polarizers in LCDs to improve display characteristics such as contrast when viewed from the front or at an angle, and color compensation.

[0003] A typical example of an optical film related to polarizing plates is retardation film, which is used as an anti-reflection layer in liquid crystal displays, touch panels, and organic electroluminescence (EL) displays.

[0004] Conventional retardation films are made of polycarbonate or cyclic polyolefin, both of which have positive birefringence. Here, the positive and negative birefringence are defined as follows:

[0005] The optical anisotropy of a polymer film that has been molecularly oriented by stretching or casting using a coater can be expressed by an index ellipsoid, where nx is the refractive index in the fast axis direction (the direction with the smallest refractive index) within the film plane, ny is the refractive index in the direction perpendicular to that in the film plane (the slow axis), and nz is the refractive index in the thickness direction of the film (the perpendicular direction outside the film plane).

[0006] In other words, when a polymer with negative birefringence is uniaxially stretched, the refractive index in the direction of the stretching axis (fast axis: stretching direction) is small, and when a polymer with positive birefringence is uniaxially stretched, the refractive index in the direction perpendicular to the stretching axis is small (fast axis: direction perpendicular to the stretching direction).

[0007] Many polymers have positive birefringence. Polymers with negative birefringence include acrylic resin and polystyrene, but acrylic resin exhibits little retardation and does not have sufficient properties as a retardation film. Polystyrene is not currently used due to optical property issues such as a high wavelength dependency of retardation, practical issues such as low heat resistance, and retardation stability issues such as a large photoelastic coefficient at room temperature that causes the retardation to change with even slight stress.

[0008] There is a strong market demand for such a retardation film exhibiting negative birefringence, and various retardation films exhibiting negative birefringence have been developed to meet the above-mentioned required characteristics.

[0009] Patent Documents 1 and 2 propose fumaric acid ester resins as optical films that exhibit negative birefringence and have a high refractive index in the thickness direction.

[0010] A resin composition containing a fumaric acid ester polymer and a specific silicone resin has been proposed (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-064817 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-107281 [Patent Document 3] Japanese Patent Application Publication No. 2020-125418 Summary of the Invention [Problem to be solved by the invention]

[0012] The retardation films obtained in Patent Documents 1 and 2 are excellent in optical properties such as retardation characteristics and wavelength dependency, but when used with polarizing plates that require durability at high temperatures, they are prone to deformation under stress due to their low storage modulus at high temperatures, and therefore, improvement in the storage modulus at high temperatures has been desired.

[0013] Although the retardation film obtained in Patent Document 3 is excellent in retardation properties and dimensional stability, a material having a better storage modulus at high temperatures is desired.

[0014] The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin composition that is excellent in retardation properties and storage modulus at high temperatures when used as an optical film. [Means for solving the problem]

[0015] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a resin composition containing a specific polymer and a specific cyclic compound solves the above-mentioned problems, and have thus completed the present invention.

[0016] That is, the present invention relates to a resin composition containing a fumarate ester-based polymer having a fumarate diester residue represented by the following general formula (1) and a cyclic siloxane compound represented by the following general formula (2) or a cyclic silane compound represented by the following general formula (3):

[0017] [ka]

[0018] (wherein R1 and R2 each independently represent one of the group consisting of a linear or branched alkyl group having 1 to 12 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms).

[0019] [ka]

[0020] (In the formula, m represents an integer of 4 to 20.)

[0021] [ka]

[0022] (In the formula, n represents an integer of 4 to 20.) The present invention will be described in detail below.

[0023] The resin composition of the present disclosure relates to a resin composition containing a fumarate ester-based polymer containing a fumarate diester residue represented by the general formula (1) and a cyclic siloxane compound represented by the general formula (2) or a cyclic silane compound represented by the general formula (3).

[0024] The fumarate polymer contained in the resin composition of the present disclosure contains a fumarate diester residue represented by the following general formula (1).

[0025] [ka]

[0026] (wherein R1 and R2 each independently represent one of the group consisting of a linear or branched alkyl group having 1 to 12 carbon atoms or a cyclic alkyl group having 3 to 6 carbon atoms). Here, R1 and R2, which are ester substituents of the fumaric acid diester residue unit in general formula (1), are each independently a linear or branched alkyl group having 1 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms, such as an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a sec-pentyl group, a tert-pentyl group, a sec-hexyl group, a tert-hexyl group, a cyclopropyl group, a cyclopentyl group, or a cyclohexyl group. Among these, an ethyl group, an isopropyl group, a sec-butyl group, a tert-butyl group, a cyclopentyl group, or a cyclohexyl group is preferred, since when the resin composition is made into an optical film, the optical film will have excellent heat resistance and mechanical properties, and an isopropyl group is particularly more preferred.

[0027] The fumarate ester polymer in the present disclosure may be a copolymer containing residue units other than the residue units represented by general formula (1), or may be a polymer having only residue units represented by general formula (1). Preferably, the fumarate ester polymer is a polymer having only residue units represented by general formula (1).

[0028] Specific examples of the fumaric acid diester residue unit represented by general formula (1) include dimethyl fumarate residue, diethyl fumarate residue, diisopropyl fumarate residue, di-sec-butyl fumarate residue, di-tert-butyl fumarate residue, di-n-butyl fumarate residue, isobutyl fumarate residue, dipentyl fumarate residue, diisopentyl fumarate residue, di-sec-pentyl fumarate residue, di-tert-pentyl fumarate residue, di-sec-hexyl fumarate residue, di- -tert-hexyl residue, di-sec-isoamyl fumarate residue, dineopentyl fumarate residue, di-tert-pentyl fumarate residue, di-2-ethylhexyl fumarate residue, dicyclopropyl fumarate residue, dicyclobutyl fumarate residue, dicyclopentyl fumarate residue, dicyclohexyl fumarate residue, and residues in which R1 or R2 is replaced in these residues (e.g., ethyl isopropyl fumarate residue, ethyl-sec-butyl fumarate residue, etc.). Among these, diethyl fumarate residue, diisopropyl fumarate residue, di-sec-butyl fumarate residue, di-tert-butyl fumarate residue, dicyclopentyl fumarate residue, and dicyclohexyl fumarate residue are preferred, and diethyl fumarate residue, diisopropyl fumarate residue, di-sec-butyl fumarate residue, di-tert-butyl fumarate residue, dicyclopentyl fumarate residue, and dicyclohexyl fumarate residue are particularly preferred, with diethyl fumarate residue and diisopropyl fumarate residue being more preferred. These may be used alone or in combination of two or more.

[0029] When the fumarate polymer used in the present disclosure is a copolymer, the proportion of fumarate residues represented by general formula (1) is preferably 30 mol% or more, and more preferably 50 mol% or more, more preferably 70 mol% or more, and particularly preferably 80 mol% or more, since the resulting optical film has excellent heat resistance and mechanical properties. Furthermore, the proportion of fumarate residues represented by general formula (1) is preferably 100% or less.

[0030] Furthermore, the fumarate ester polymer constituting the resin composition of the present disclosure may contain other monomer residues as long as the residue does not deviate from the objectives of the present disclosure. Examples of the other monomer residues include one or more of: styrene residues such as styrene residue and α-methylstyrene residue; acrylic acid residues; acrylic acid ester residues such as methyl acrylate residue, ethyl acrylate residue, and butyl acrylate residue; methacrylic acid residues; methacrylic acid ester residues such as methyl methacrylate residue, ethyl methacrylate residue, and butyl methacrylate residue; vinyl ester residues such as vinyl acetate residue and vinyl propionate residue; acrylonitrile residues; methacrylonitrile residues; and olefin residues such as ethylene residue and propylene residue.

[0031] Fumarate ester polymers have particularly excellent mechanical properties and excellent processability during film formation. Therefore, they are suitable for use in polymers with a number average molecular weight (Mn) of 1×10 in terms of standard polystyrene obtained from the elution curve measured by gel permeation chromatography (GPC). 3 ~5×10 6 Preferably, it is 5×10 4 ~5×10 5 Even more preferably, 8×10 4 ~5×10 5 is.

[0032] The method for producing the fumaric acid ester-based polymer constituting the resin composition of the present disclosure is not particularly limited as long as it can produce a fumaric acid ester-based polymer, and can be produced, for example, by radical polymerization of fumaric acid esters (monomers).

[0033] The radical polymerization method used can be any known polymerization method, such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, emulsion polymerization, or the like.

[0034] Examples of polymerization initiators used in radical polymerization include organic peroxides such as benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, and t-butyl peroxypivalate; and azo initiators such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, and 1,1'-azobis(cyclohexane-1-carbonitrile).

[0035] Solvents that can be used in the solution polymerization method, suspension polymerization method, precipitation polymerization method, and emulsion polymerization method are not particularly limited, and examples thereof include aromatic solvents such as benzene, toluene, and xylene; alcoholic solvents such as methanol, ethanol, propyl alcohol, and butyl alcohol; cyclohexane; dioxane; tetrahydrofuran (THF); acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; water; and mixed solvents thereof.

[0036] The polymerization temperature during radical polymerization can be appropriately set depending on the decomposition temperature of the polymerization initiator, and is generally preferably in the range of 40°C or higher and 150°C or lower.

[0037] The suspension polymerization method in the present disclosure may be a known radical suspension polymerization method, and is not particularly limited as long as an aqueous medium is used. The aqueous medium is also not particularly limited, and examples thereof include water, industrial water, ion-exchanged water, and distilled water.

[0038] Dispersants that are commonly used in the suspension polymerization reaction of the present disclosure can be used, and there are no particular limitations on the dispersant, and known dispersants can be used. Examples include polyvinyl alcohol-based dispersants such as polyvinyl alcohol; cellulose-based dispersants such as methyl cellulose, ethyl cellulose, propyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, and carboxyethyl cellulose; and inorganic compounds such as calcium phosphate. Among these, cellulose-based dispersants are preferred because they provide more stable suspension polymerization, and hydroxypropyl methyl cellulose is more preferred.

[0039] The blending ratios of the aqueous medium, monomer, dispersant, and polymerization initiator in the method for producing a fumarate ester polymer of the present disclosure can be appropriately selected depending on the desired quality of the fumarate ester polymer. Among these, it is preferable to use 50 to 150 parts by weight of the monomer, 0.01 to 20 parts by weight of the dispersant, and 0.001 to 5 parts by weight of the polymerization initiator per 100 parts by weight of the aqueous medium, as this method for producing a fumarate ester polymer has better production efficiency.

[0040] The suspension polymerization reaction apparatus in the present disclosure is not particularly limited, and known apparatuses can be used, such as glass-lined (GL) or stainless steel (SUS) reaction vessels equipped with stirring blades, temperature control devices, etc. Examples of stirring blades include paddle blades, four-blade paddle blades, anchor blades, three-blade swept blades, six-blade turbine blades, and blue margin blades.

[0041] The resin composition according to the present disclosure is characterized in that, by containing a cyclic siloxane compound represented by the following general formula (2) or a cyclic silane compound represented by the following general formula (3), when formed into a film and used, it has an excellent storage modulus even at high temperatures.

[0042] [ka]

[0043] (In the formula, m represents an integer of 4 to 20.)

[0044] [ka]

[0045] (In the formula, n represents an integer of 4 to 20.) The cyclic siloxane compound and cyclic silane compound of the present disclosure are cyclic compounds rather than chain compounds. Because cyclic compounds are more rigid than chain compounds, their inclusion in a fumarate ester polymer improves the storage modulus at high temperatures.

[0046] In the present disclosure, the cyclic siloxane compound and the cyclic silane compound have a phenyl group. The phenyl group improves affinity with the fumarate ester-based polymer, allowing for the production of a highly transparent optical film. Furthermore, the rigid phenyl group improves the storage modulus at high temperatures when incorporated into the fumarate ester-based polymer.

[0047] The cyclic siloxane compound represented by general formula (2) is characterized by satisfying the condition that m = 4 to 20. Because of excellent affinity with the fumaric acid ester polymer, m = 4 to 10 is preferred, and m = 4 to 8 is particularly preferred.

[0048] Specific examples of the cyclic siloxane compound represented by the general formula (2) include octaphenylcyclotetrasiloxane, decaphenylcyclopentasiloxane, dodecaphenylcyclohexasiloxane, and hexadecaphenylcyclooctasiloxane.

[0049] The cyclic siloxane compound represented by the general formula (3) is characterized by satisfying the condition that n = 4 to 20. Because of excellent affinity with the fumaric acid ester polymer, n = 4 to 10 is preferred, and n = 4 to 8 is particularly preferred.

[0050] Specific examples of the cyclic silane compound represented by the general formula (3) include octaphenylcyclotetrasilane, decaphenylcyclopentasilane, dodecaphenylcyclohexasilane, and hexadecaphenylcyclooctasilane.

[0051] The proportions of the cyclic siloxane compound or cyclic silane compound in the resin composition of the present disclosure are preferably 80% by weight to 99.9% by weight of the fumarate ester polymer and 0.1% by weight to 20% by weight of the cyclic siloxane compound or cyclic silane compound, more preferably 85% by weight to 99.5% by weight of the fumarate ester polymer and 0.5% by weight to 15% by weight of the cyclic siloxane compound or cyclic silane compound, and even more preferably 90% by weight to 99.0% by weight of the fumarate ester polymer and 1.0% by weight to 10% by weight of the cyclic siloxane compound or cyclic silane compound.

[0052] These cyclic siloxane compounds or cyclic silane compounds may be used alone or in combination of two or more.

[0053] The resin composition may contain an antioxidant to improve thermal stability, such as a hindered phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, a lactone-based antioxidant, an amine-based antioxidant, a hydroxylamine-based antioxidant, a vitamin E-based antioxidant, or other antioxidants, and these antioxidants may be used alone or in combination of two or more.

[0054] The resin composition may contain a hindered amine light stabilizer or an ultraviolet absorber to enhance weather resistance, such as benzotriazole, benzophenone, triazine, or benzoate.

[0055] The resin composition may contain other polymers, surfactants, polymer electrolytes, conductive complexes, pigments, dyes, antistatic agents, antiblocking agents, lubricants, etc., within the scope of the invention.

[0056] The resin composition of the present disclosure can be produced by mixing the fumaric acid ester polymer with the cyclic siloxane compound or cyclic silane compound.

[0057] The optical film, which is one embodiment of the present disclosure, will be described in detail below.

[0058] The resin composition of the present disclosure can be suitably used as an optical film for optical components. In particular, the resin composition of the present disclosure contains a cyclic siloxane compound or a cyclic silane compound, which gives the composition an excellent storage modulus at high temperatures, and the resin composition is less likely to deform due to stress even in a high-temperature environment, allowing it to be used as a highly durable optical film.

[0059] In an optical film using the resin composition of the present disclosure, deformation due to stress is small even in a high-temperature environment, so that the storage modulus at 180°C is preferably 1.25 × 10 8 Pa or more, preferably 1.30 × 10 8 Pa or more 2.00×10 9Below, particularly preferably 1.40 × 10 8 Pa or more 1.00×10 9 The following is the result.

[0060] In this specification, the storage modulus of the optical film is a value measured, for example, by the measurement method in the examples described later.

[0061] In the optical film of the present disclosure, the out-of-plane retardation (Rth) measured at a wavelength of 589 nm and represented by the following formula (a) is preferably −700 to 0 nm, more preferably −240 to −20 nm, and particularly preferably −160 to −60 nm, in order to provide an optical film with excellent viewing angle characteristics. In this specification, the out-of-plane retardation of the optical film is a value measured, for example, by the measurement method in the examples described later.

[0062] Rth = [(nx + ny) / 2 - nz] × d (a) (In the formula, nx is the refractive index in the fast axis direction in the film plane, ny is the refractive index in the slow axis direction in the film plane, nz is the refractive index in the perpendicular direction outside the film plane, and d is the film thickness.) In terms of adaptability to thinner optical members, the optical film preferably has a thickness of 80.0 μm or less, more preferably 0.1 to 50.0 μm, and particularly preferably 0.1 to 35.0 μm.

[0063] The haze of the optical film is preferably 1.0% or less, and more preferably 0.5% or less. By controlling the haze within this range, a high-contrast image can be obtained when the optical film is incorporated into a display device. Here, the haze is a value measured at a wavelength of 380 to 780 nm using a general haze meter equipped with a white light source in accordance with JIS-K 7136 (2000 edition).

[0064] The method for producing the optical film is not particularly limited, and for example, the optical film can be produced by forming a raw material fumaric acid ester polymer into a long film by a method such as solution casting.

[0065] Here, the solution casting method is a method in which a fumaric acid ester-based polymer solution (resin solution) is cast onto a supporting substrate, and then the solvent is evaporated by heating and drying, and the film is peeled off from the substrate to obtain an optical film.

[0066] The solvent used for the resin solution in the solution casting method may be any solvent that can dissolve the fumaric acid ester-based polymer, etc., and the boiling point of the solvent is preferably 200°C or lower, more preferably 170°C or lower, so that residual solvent is less likely to remain when the optical film is obtained.

[0067] Examples of the solvent include halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and dichlorobenzene; phenols such as phenol and chlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, mesitylene, and dimethoxybenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, and N-methyl-2-pyrrolidone; and esters such as ethyl acetate and butyl acetate. alcohol-based solvents such as t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, and 2-methyl-2,4-pentanediol; amide-based solvents such as dimethylformamide and dimethylacetamide; nitrile-based solvents such as acetonitrile and butyronitrile; ether-based solvents such as diethyl ether, dibutyl ether, and tetrahydrofuran; and solvents obtained by using carbon disulfide, ethyl cellosolve, butyl cellosolve, and the like, either alone or in combination.

[0068] The viscosity of the resin solution can be adjusted by the molecular weight and concentration of each component and the type of solvent. There are no particular restrictions on the viscosity of the resin solution, but to facilitate film casting, it is preferably 100 to 30,000 cps, more preferably 300 to 20,000 cps, and particularly preferably 300 to 15,000 cps.

[0069] In the present disclosure, the concentration of the fumaric acid ester polymer in the resin solution is not particularly limited as long as dissolution and film formation are possible. The dissolution may be carried out so that the desired concentration is achieved during dissolution, or a low-concentration solution may be prepared in advance and then adjusted to a desired high-concentration solution by a concentration process. Furthermore, a high-concentration resin solution may be prepared in advance, and then various additives may be added to obtain a desired low-concentration resin solution.

[0070] The support substrate used is not particularly limited, and examples thereof include polymer substrates made of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polycarbonates, polystyrene, polyethylene, polypropylene, polyacrylic, polyvinyl chloride and polyvinylidene chloride, cellulose acetate, cellulose ether, polyvinyl alcohol, polyamide, polyimide, polyarylate, polysulfone, polyethersulfone, polyetherketone, phenolic resins, epoxy resins, alicyclic polyolefins, norbornene-based thermoplastic transparent resins, glass substrates such as glass plates and quartz substrates, metal substrates such as aluminum, stainless steel, and ferrotypes, and inorganic substrates such as ceramic substrates. Preferred examples of the substrate include polymer substrates such as polyesters such as polyethylene terephthalate and polyethylene naphthalate, polypropylene, polyacrylic, cellulose acetate and cellulose ether, polyimides, alicyclic polyolefins, and norbornene-based thermoplastic transparent resins. Particularly preferred are polymer substrates such as polyesters such as polyethylene terephthalate and polyethylene naphthalate, polypropylene, polyimides, alicyclic polyolefins, and norbornene-based thermoplastic transparent resins.

[0071] The casting method is not particularly limited, and a common method can be used, such as a T-die method, a doctor blade method, a bar coater method, a slot die method, a lip coater method, a reverse gravure coating method, a microgravure coating method, a spin coating method, a brush coating method, a roll coating method, or a flexographic printing method.

[0072] The drying method in the drying step is not particularly limited, and any ordinary heating means can be used, such as a hot air blower, a heating roll, or a far-infrared heater.

[0073] The drying temperature is preferably 30 to 200° C., and particularly preferably 40 to 160° C. The drying temperature may be a single-stage condition, or in order to maintain the appearance or shorten the drying time, multi-stage drying may be used in which the first stage is dried at a low temperature and the second and subsequent stages are dried at a high temperature.

[0074] The film peeling speed in the substrate peeling step is preferably in the range of 0.1 to 30 m / min, for example, and more preferably in the range of 1 to 30 m / min, in view of productivity, mechanical precision, stability, etc.

[0075] The optical film of the present disclosure may be a stretched optical film, and by stretching the optical film of the present disclosure, it is possible to control the retardation.

[0076] In the stretched optical film, the in-plane retardation (Re) measured at 589 nm and represented by the following formula (b) is 0 to 400 nm, preferably 5 to 350 nm, more preferably 30 to 300 nm, and particularly preferably 60 to 230 nm, since the optical film has excellent viewing angle characteristics such as low black brightness and high contrast. In this specification, the in-plane retardation of the optical film is a value measured, for example, by the measurement method in the examples described later.

[0077] Re=(ny-nx)×d (b) (In the formula, nx represents the refractive index in the fast axis direction in the film plane, ny represents the refractive index in the slow axis direction in the film plane, and d represents the thickness of the film.) In the case of a stretched optical film, the thickness is 80.0 μm or less, preferably 0.1 to 50.0 μm, more preferably 0.1 to 40.0 μm, and particularly preferably 0.1 to 25.0 μm, from the viewpoint of adaptability to thinner optical members.

[0078] The stretching method can be, for example, a uniaxial stretching method or a biaxial stretching method, since it allows for phase difference control. Examples of the uniaxial stretching method include a longitudinal uniaxial stretching method in which stretching is performed between rolls and a transverse axial stretching method in which stretching is performed using a tenter. Examples of the biaxial stretching method include a method in which stretching is performed using a tenter and a method in which the film is expanded into a tubular shape and stretched.

[0079] The temperature during stretching is preferably 90 to 300°C, particularly preferably 105 to 250°C, since this makes it difficult for thickness unevenness to occur and results in an optical film with excellent mechanical and optical properties.

[0080] The stretching ratio of the film (hereinafter referred to as "stretching ratio") is preferably 1.05 to 4.0 times, more preferably 1.05 to 3.5 times, and particularly preferably 1.1 to 3.0 times, so that the resulting optical film is thin and exhibits good retardation properties.

[0081] The thickness of the film to be subjected to the stretching step is preferably 5 to 200 μm, more preferably 5 to 150 μm, and particularly preferably 5 to 100 μm, from the viewpoint of ease of stretching treatment and suitability for thinning optical films.

[0082] In this way, by adjusting the stretching temperature and stretching ratio, the in-plane retardation of the resulting optical film can be controlled.

[0083] The film transport speed in the stretching step is preferably in the range of 0.5 to 30 m / min, for example, from the viewpoint of mechanical precision, stability, etc., and more preferably in the range of 1 to 20 m / min.

[0084] In the present disclosure, a shrinking step may be performed after the stretching to shrink the obtained optical film. Specifically, the stretched optical film is shrunk in the direction opposite to the stretching direction. This can relieve residual stress accumulated in the stretched film, and the obtained optical film will exhibit a high retardation even after a long period of time has passed.

[0085] The optical film can be further laminated with a film containing other resins as needed. Examples of other resins include polyethersulfone, polyarylate, polyethylene terephthalate, polynaphthalene terephthalate, polycarbonate, cyclic polyolefin, maleimide resin, fluorine-based resin, polyimide, etc. It is also possible to laminate a liquid crystal layer, a hard coat layer, a gas barrier layer, or a layer with a controlled refractive index (low reflection layer).

[0086] The optical film of the present disclosure has excellent heat resistance and optical properties, and is suitable for use as a retardation film in applications such as liquid crystal displays and organic EL displays.

[0087] Furthermore, by disposing the optical film of the present disclosure on at least one surface of a polarizer, a polarizing plate with excellent heat resistance and optical properties can be obtained, and the polarizing plate is suitably used as a polarizing plate for liquid crystal displays or an anti-reflection polarizing plate. [Example]

[0088] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, the reagents used were commercially available products.

[0089] The physical properties shown in the examples were measured by the following methods.

[0090] <Measurement of number average molecular weight> A gel permeation chromatography (GPC) system (Tosoh Corporation, product name: HLC-8320GPC) was used, and the column was a Tosoh Corporation TSKgel Super HM- Two columns of H were used, the column temperature was set at 40°C, and measurements were carried out at 40°C using tetrahydrofuran as a solvent, and the values were calculated in terms of standard polystyrene.

[0091] <Analysis of fumaric acid ester polymers> The structure of the fumarate ester polymer was analyzed using a nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., product name: JNM-ECZ400 / L1) and proton nuclear magnetic resonance spectroscopy ( 1 The values were determined by H-NMR spectroscopy.

[0092] <Haze measurement> The haze of the prepared film was measured using a spectroscopic haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: SH7000) in accordance with JIS-K 7136 (2000 edition). <Measurement of phase difference characteristics (Rth)> The out-of-plane retardation Rth shown in formula (a) was measured at a wavelength of 589 nm using a polarized retardation measurement system (manufactured by Axometrics, trade name: AxoScan). <Thickness measurement> The film thickness was measured using a high-resolution linear gauge sensor (manufactured by Ono Sokki, product name: GS-3813B).

[0093] <Measurement of storage modulus> Using a dynamic viscoelasticity measuring device Rheogel-E4000 (manufactured by UBM), the film was measured for tensile strength at a measurement frequency of 10 Hz, and the temperature dependency was measured when the temperature was raised from 40°C to 180°C at a rate of 2°C / min. The storage modulus of the film at 180°C was then measured.

[0094] Synthesis Example 1 A 1-liter reactor equipped with a stirrer, condenser, nitrogen inlet, and thermometer was charged with 600 g of distilled water, 3.4 g of hydroxypropyl methylcellulose (Shin-Etsu Chemical Co., Ltd., trade name: Metrose 60SH-50) as a dispersant, 350.9 g of diisopropyl fumarate, 49.1 g of diethyl fumarate (14.0 parts by weight per 100 parts by weight of diisopropyl fumarate), and 8.3 g of polymerization initiator t-butyl peroxypivalate. After nitrogen bubbling for 1 hour, the mixture was stirred at 400 rpm and maintained at 50°C for 28 hours to carry out radical suspension polymerization. After completion of the polymerization reaction, the contents were recovered from the reactor, and the polymer was filtered, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80°C (yield: 75%).

[0095] The number average molecular weight of the resulting fumaric acid ester polymer was 138,000. 1 H-NMR analysis confirmed that the fumarate polymer was a copolymer of diisopropyl fumarate and diethyl fumarate with a molar ratio of diisopropyl fumarate residues to diethyl fumarate residues of 86.7 / 13.3.

[0096] Synthesis Example 2 A 1-liter reactor equipped with a stirrer, condenser, nitrogen inlet, and thermometer was charged with 600 g of distilled water, 3.4 g of hydroxypropyl methylcellulose (Shin-Etsu Chemical Co., Ltd., trade name: Metrose 60SH-50) as a dispersant, 387.5 g of diisopropyl fumarate, 12.5 g of 3-ethyl-3-oxetanylmethyl acrylate (3.2 parts by weight per 100 parts by weight of diisopropyl fumarate), and 8.3 g of polymerization initiator t-butyl peroxypivalate. After nitrogen bubbling for 1 hour, the mixture was stirred at 400 rpm and maintained at 50°C for 24 hours to carry out radical suspension polymerization. After the polymerization reaction was completed, the contents were recovered from the reactor, and the polymer was filtered, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80°C (yield: 73%).

[0097] The number average molecular weight of the resulting fumaric acid ester polymer was 147,000. 1 H-NMR analysis confirmed that the fumarate polymer was a copolymer of diisopropyl fumarate and 3-ethyl-3-oxetanylmethyl acrylate, with a molar ratio of diisopropyl fumarate residues to 3-ethyl-3-oxetanylmethyl acrylate residues of 96.1 / 3.9.

[0098] Example 1 9.8 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.2 g of decaphenylcyclopentasilane were dissolved in a methyl ethyl ketone-toluene mixed solution (methyl ethyl ketone / toluene = 40 wt% / 60 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the resulting film were measured. The results are also shown in Table 1. The resulting film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0099] Example 2 9.7 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.3 g of decaphenylcyclopentasilane were dissolved in an ethyl acetate / toluene mixed solution (ethyl acetate / toluene = 40 wt% / 60 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the resulting film were measured. The results are also shown in Table 1. The resulting film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0100] Example 3 9.6 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.4 g of decaphenylcyclopentasilane were dissolved in a methyl ethyl ketone-toluene mixed solution (methyl ethyl ketone / toluene = 20 wt% / 80 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the resulting film were measured. The results are also shown in Table 1. The resulting film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0101] Example 4 9.0 g of the fumaric acid ester polymer obtained in Synthesis Example 1 and 1.0 g of decaphenylcyclopentasilane were dissolved in a tetrahydrofuran solution to prepare an 18 wt % resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater, and then dried in two stages at temperatures of 50°C and 130°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0102] Example 5 9.8 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.2 g of octaphenylcyclotetrasiloxane were dissolved in a tetrahydrofuran solution to prepare an 18 wt % resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater, and then dried in two stages at temperatures of 50°C and 130°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0103] Example 6 9.6 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.4 g of octaphenylcyclotetrasiloxane were dissolved in a tetrahydrofuran solution to prepare an 18 wt % resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater, and then dried in two stages at temperatures of 50°C and 130°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0104] Example 7 9.8 g of the fumarate ester polymer obtained in Synthesis Example 2 and 0.2 g of octaphenylcyclotetrasiloxane were dissolved in a tetrahydrofuran solution to prepare an 18 wt % resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater, and then dried in two stages at temperatures of 50°C and 130°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had an excellent storage modulus at high temperatures and was suitable as an optical film.

[0105] Comparative Example 1 10.0 g of the fumarate ester polymer obtained in Synthesis Example 1 was dissolved in a methyl ethyl ketone / toluene mixed solution (methyl ethyl ketone / toluene = 60 wt% / 40 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had a low storage modulus at 180°C and did not have the desired high-temperature storage modulus.

[0106] Comparative Example 2 9.8 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.2 g of silicone resin YR-3370 (Momentive Performance Materials Holdings, Inc.) were dissolved in a methyl ethyl ketone / toluene mixed solution (methyl ethyl ketone / toluene = 60 wt% / 40 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation, haze, and storage modulus at 180°C of the resulting film were measured. The results are also shown in Table 1. The resulting film had a low storage modulus at 180°C and did not have the desired high-temperature storage modulus.

[0107] Comparative Example 3 9.6 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.4 g of silicone resin YR-3370 (Momentive Performance Materials Holdings, Inc.) were dissolved in a methyl ethyl ketone / toluene mixed solution (methyl ethyl ketone / toluene = 60 wt% / 40 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation, haze, and storage modulus at 180°C of the resulting film were measured. The results are also shown in Table 1. The resulting film had a low storage modulus at 180°C and did not have the desired high-temperature storage modulus.

[0108] Comparative Example 4 9.8 g of the fumarate ester polymer obtained in Synthesis Example 1 and 0.2 g of silicone resin RSN-217 (Dow Corning) were dissolved in a methyl ethyl ketone / toluene mixed solution (methyl ethyl ketone / toluene = 60 wt% / 40 wt%) to prepare an 18 wt% resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries) using a coater and dried in three stages at temperatures of 60°C, 120°C, and 140°C to form a film. The film thickness, retardation, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had a low storage modulus at 180°C and did not have the desired high-temperature storage modulus.

[0109] Comparative Example 5 10.0 g of the fumaric acid ester polymer obtained in Synthesis Example 2 was dissolved in a tetrahydrofuran solution to prepare an 18 wt % resin solution. The solution was applied to a polyethylene terephthalate substrate (Lumirror T60, manufactured by Toray Industries, Inc.) using a coater, and dried in two stages at temperatures of 50°C and 130°C to form a film. The film thickness, retardation properties, haze, and storage modulus at 180°C of the obtained film were measured. The results are also shown in Table 1. The obtained film had a low storage modulus at 180°C and did not have the desired storage modulus at high temperatures.

[0110]

Table 1

Claims

1. A resin composition containing a fumarate ester polymer containing a fumarate diester residue represented by the following general formula (1), and a cyclic siloxane compound represented by the following general formula (2) or a cyclic silane compound represented by the following general formula (3): 【Chemical 1】 (In the formula, R １ and R ２ each independently represents one of the group consisting of a linear or branched alkyl group having 1 to 12 carbon atoms, or a cyclic alkyl group having 3 to 6 carbon atoms. 【Chemistry 2】 (In the formula, m represents an integer of 4 to 20.) 【Chemistry 3】 (In the formula, n represents an integer of 4 to 20.)

2. The fumaric acid diester residue represented by the general formula (1) is a dimethyl fumarate residue, a diethyl fumarate residue, a diisopropyl fumarate residue, a di-tert-butyl fumarate residue, a di-n-butyl fumarate residue, a di-sec-butyl fumarate residue, an isobutyl fumarate residue, a dipentyl fumarate residue, a diisopentyl fumarate residue, a di-sec-pentyl fumarate residue, a di-tert-pentyl fumarate residue, a di-sec-hexyl fumarate residue, The resin composition according to claim 1, characterized in that the fumarate diester residue is at least one selected from the group consisting of di-tert-hexyl fumarate residue, di-sec-isoamyl fumarate residue, dineopentyl fumarate residue, di-tert-pentyl fumarate residue, di-2-ethylhexyl fumarate residue, dicyclopropyl fumarate residue, dicyclobutyl fumarate residue, dicyclopentyl fumarate residue, and dicyclohexyl fumarate residue.

3. The resin composition according to claim 1, wherein the cyclic siloxane compound represented by the general formula (2) is one selected from the group consisting of octaphenylcyclotetrasiloxane, decaphenylcyclopentasiloxane, dodecaphenylcyclohexasiloxane, and hexadecaphenylcyclooctasiloxane.

4. The resin composition according to claim 1, wherein the cyclic silane compound represented by the general formula (3) is one selected from the group consisting of octaphenylcyclotetrasilane, decaphenylcyclopentasilane, dodecaphenylcyclohexasilane, and hexadecaphenylcyclooctasilane.

5. 2. The resin composition according to claim 1, comprising 80% by weight or more and 99.9% by weight or less of a fumarate ester polymer containing a fumarate diester residue represented by the general formula (1), and 0.1 to 20% by weight of a cyclic siloxane compound represented by the general formula (2) or a cyclic silane compound represented by the general formula (3).

6. An optical film comprising the resin composition according to any one of claims 1 to 5.

7. 7. The optical film according to claim 6, wherein the out-of-plane retardation (Rth) represented by the following formula (a) is −700 to 0 nm: Rth=[(nx+ny) / 2-nz]×d (a) (wherein nx represents the refractive index in the fast axis direction in the film plane, and ny represents the refractive index in the slow axis direction in the film plane) direction, nz indicates the refractive index outside the film plane, and d indicates the film thickness.

8. Storage modulus at 180°C is 1.25 x 10 ８ The optical film according to claim 6, wherein the modulus is 1 Pa or more.

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