Resin film for optical films and method for producing resin film for optical films

Abstract

Provided is a resin film for optical films which comprises an amorphous resin that has positive birefringence and a diacetal compound that is represented by formula (1). In the film, the diacetal compound is precipitated in an associated state or as a crystal exhibiting negative birefringence. [Formula 1] (In the formula, R1, R2, R3, R4, R5, and R6 are the same or different and each represent a hydrogen atom, C1-4 alkyl group, a C1-4 alkoxy group, a C1-4 alkoxy carbonyl group, a C1-4 halogenated alkyl group, or a halogen atom. R7 represents a hydrogen atom, a C1-4 alkyl group, a C1-4 alkenyl group, a C1-4 alkoxy group, a C1-4 alkoxy carbonyl group, or a C1-4 halogenated alkyl group.)

Description

Resin film for optical films and method for manufacturing a resin film for optical films

[0001] The present invention relates to a resin film for optical films and a method for manufacturing a resin film for optical films. This application claims priority under Japanese Patent Application No. 2024-161487 filed on 18 September 2024, Japanese Patent Application No. 2024-205493 filed on 26 November 2024, Japanese Patent Application No. 2025-7676 filed on 20 January 2025, and Japanese Patent Application No. 2025-072082 filed on 24 April 2025, and incorporates all the provisions of the said Japanese Patent Applications.

[0002] Acrylic acid-based resin films with distinctive optical properties are known. For example, Patent Document 1 discloses a resin film for optical films comprising a methacrylic acid ester polymer and a diacetal compound having a specific structure. The resin film disclosed in Patent Document 1 is characterized by not experiencing dispersion defects and having low birefringence. The resin film produced in Patent Document 1 is disclosed to have a positive change in orientational birefringence due to the inclusion of the diacetal compound, resulting in lower birefringence than a resin film that does not contain the diacetal compound.

[0003] Patent Document 2 discloses a substrate for a surface protection film for protecting the surface of an image display device. The substrate for the surface protection film disclosed in Patent Document 2 is characterized by having a specific range of phase difference characteristics. The specific composition of this film substrate is disclosed to include at least one resin selected from polycarbonate, polyester, cycloolefin resin, acrylic resin, and cellulose resin. It is also disclosed that the film substrate may include a resin having an alicyclic structure or an aromatic ring structure exhibiting negative intrinsic birefringence.

[0004] Japanese Patent Publication No. 2010-254730, WO2020 / 054135

[0005] The present invention aims to provide a resin film for optical films comprising a resin having positive birefringence and a diacetal compound, wherein the birefringence is adjusted in the negative direction, and a method for producing the same.

[0006] The resin film for optical films according to this disclosure is a film containing an amorphous resin having positive birefringence and a diacetal compound represented by formula (1). In the film, the diacetal compound precipitates as crystals or aggregated states exhibiting negative birefringence. (In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ These are identical or different, and each represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, a C1-C4 halogenated alkyl group, or a halogen atom, respectively. ７ (This represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkenyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, or a C1-C4 halogenated alkyl group.)

[0007] The resin film according to this disclosure comprises a resin having positive birefringence and a diacetal compound, and the birefringence is adjusted in the negative direction.

[0008] Figure 1 is a TEM image of the resin film of Example 4.

[0009] [Summary of Embodiments] First, embodiments of the resin film for optical films and the method for manufacturing the same according to this disclosure will be listed and described. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more, B or less".

[0010] The resin film for optical films according to this disclosure is a film containing an amorphous resin having positive birefringence and a diacetal compound represented by formula (1). In the film, the diacetal compound precipitates as crystals or aggregated states exhibiting negative birefringence. (In the formula, R １ , R２ , R ３ , R ４ , R ５ and R ６ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbon atoms, a halogenated alkyl group having 1 to 4 carbon atoms or a halogen atom. R ７ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbon atoms or a halogenated alkyl group having 1 to 4 carbon atoms. )

[0011] Conventionally, many proposals have been made for resin films with adjusted optical properties. As described above, in Patent Document 2, a resin film in which a chemical structure showing negative birefringence is incorporated into the side chain of the resin constituting the film has been proposed. On the other hand, in Patent Document 1, it is described that a methacrylic acid ester polymer and a diacetal compound are kneaded, and the diacetal compound is dissolved in the molten methacrylic acid ester polymer to obtain a mixture in which the diacetal compound is uniformly dispersed in the polymer.

[0012] In Examples 1 and 2 of Patent Document 1, it is described that a film in which the diacetal compound was not dissolved in polymethyl methacrylate and was dispersed in a powdery state was obtained. In Example 3, it is described that a film produced by a production method different from those of Examples 1 and 2 had the same orientation birefringence and photoelastic coefficient as those of Example 1. However, in any case, the specific dispersion state of the diacetal compound is unknown. Also, due to the presence of the diacetal compound, the birefringence has changed in the positive direction.

[0013] In contrast, in the resin film for an optical film according to the present disclosure, the birefringence is adjusted in the negative direction by the diacetal compound. The film according to the present disclosure is excellent in the control effect of birefringence, and a resin film for an optical film having birefringence adjusted in the negative direction or a resin film for an optical film having no birefringence can be obtained.

[0014] In the aforementioned resin film for optical films, the diacetal compound may be contained in an amount of 1% to 20% relative to the amorphous resin. When the amount is within this range, the diacetal compound can be reliably precipitated in the film, and a film with birefringence adjusted in the negative direction can be obtained.

[0015] In the aforementioned resin film for optical films, the amorphous resin may be a resin that includes at least one selected from the group consisting of cycloolefin resin, polycarbonate resin, and polyester resin.

[0016] A method for manufacturing a resin film for optical films according to this disclosure includes the steps of: obtaining a resin composition by heating and mixing an amorphous resin having positive birefringence and a diacetal compound represented by formula (1) at a temperature above the softening point of the amorphous resin to dissolve the diacetal compound in the amorphous resin; heating the resin composition and molding it while applying shear force in a molten state; and cooling it while continuously applying shear force from the molding step. (In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ These are identical or different, and each represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, a C1-C4 halogenated alkyl group, or a halogen atom, respectively. ７ (This represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkenyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, or a C1-C4 halogenated alkyl group.)

[0017] In the above manufacturing method, the diacetal compound precipitates in the resin film for optical films as a crystal or aggregated state, and the diacetal compound adjusts the birefringence in the negative direction. According to this manufacturing method, a resin film in which the birefringence characteristics are controlled in the negative direction can be obtained.

[0018] The resin film related to this disclosure will be described in more detail below.

[0019] (Resin) The resin film according to this disclosure contains an amorphous resin having positive birefringence as the resin that constitutes the film. The amorphous resin is not particularly limited as long as it has positive birefringence and transparency appropriate to the application. Examples of amorphous resins having positive birefringence include polycarbonate resin, polyester resin, cycloolefin resin, polyimide resin, cellulose ester resin, etc. Among these, from the viewpoint of productivity and cost, it is preferable that the resin having positive birefringence includes at least one selected from the group consisting of cycloolefin resin, polycarbonate resin, and polyester resin.

[0020] The resin film according to this disclosure is based on an amorphous resin having positive birefringence, but since the birefringence is adjusted in the negative direction, the birefringence of the resin film may be positive, negative, or show no birefringence (zero). In the resin film according to this disclosure, a diacetal compound exists in the film in a crystalline or associated state, and the diacetal compound adjusts the birefringence in the negative direction.

[0021] Furthermore, the birefringence of a resin film is determined by the refractive index (n) in two orthogonal axial directions within the film plane. ｘ , n ｙ It is defined as the difference (Δn) between ) and is expressed by the following equation: Δn = n ｘ -n ｙ In the above formula, n ｘ is the refractive index of the slow axis, n ｙ n represents the refractive index of the phase-advancing axis. When the resin film has positive birefringence, n ｘ >n ｙ As a result, the refractive index of the slow axis in the flow or deformation direction is higher than the refractive index of the fast axis in the direction perpendicular to it. When the resin film has negative birefringence, n ｘ <n ｙAs a result, the refractive index of the leading axis is higher than the refractive index of the lagging axis. The birefringence of the resin film can be measured, for example, using a polarizing microscope in accordance with known methods. Specific methods for measuring birefringence are described in detail in the examples. In this specification, "birefringence adjusted in the negative direction" means the birefringence value (Δn) of a resin film that does not contain the acetal compound specified by formula (1). ０ For ) the birefringence value (Δn) of the resin film containing the acetal compound specified by formula (1) ａｄ This means that it is small.

[0022] When the resin that forms the base of the resin film is a polycarbonate resin, any known resin used as an optical resin can be used without particular limitation. Examples of polycarbonate resins include bisphenol-based polycarbonate resins and isosorbide-based polycarbonate resins. For example, a bisphenol-based polycarbonate resin may be an aromatic polycarbonate resin containing constituent units (carbonate constituent units) composed of bisphenol A or bisphenol C.

[0023] Bisphenol A type polycarbonate resin is a resin having carbonate structural units derived from bisphenol A and its derivatives. In bisphenol A type polycarbonate resin, the content of structural units derived from bisphenol A is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, of all structural units excluding both ends. The upper limit is not particularly limited, and 100 mol% may be structural units derived from formula bisphenol A. Preferably, bisphenol A type polycarbonate is a resin in which substantially all structural units excluding both ends are structural units derived from bisphenol A. Bisphenol A type polycarbonate resin may have structural units other than carbonate structural units derived from bisphenol A and its derivatives, and these other structural units may be structural units derived from aromatic dihydroxy compounds.

[0024] Examples of isosorbide-based polycarbonate resins include those containing constituent units derived from isosorbide and constituent units derived from aliphatic dihydroxy compounds and / or alicyclic dihydroxy compounds. Examples of aliphatic dihydroxy compounds include 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 2-ethyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, hydrogenated dilinoleyl glycol, hydrogenated dioleyl glycol, and the like. Examples of alicyclic dihydroxy compounds include compounds containing a five-membered ring structure or a six-membered ring structure, such as cyclohexanedimethanol, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, decalindimethanol, tricyclotetradecanedimethanol, norbornanedimethanol, adamantanedimethanol, and tricyclodecanediol, pentacyclopentadecanediol, decalindiol, tricyclotetradecanediol, norbornanediol, adamantanediol, and others.

[0025] Polycarbonate resin can be any optical resin available on the market, such as the "Yupilon" series from Mitsubishi Gas Chemical Company, Inc., the "Panlight" series from Teijin Limited, and the "Durabio" series from Mitsubishi Chemical Corporation.

[0026] When the resin that forms the base of the resin film is a polyester resin, any known polyester resin that is used as an optical resin and has positive birefringence can be used without particular limitation. The polyester resin is obtained by polymerizing a dicarboxylic acid and a diol, and it is preferable that 70% or more of the dicarboxylic acid constituent units (constituent units derived from dicarboxylic acid) are derived from aromatic dicarboxylic acids, and 70% or more of the diol constituent units (constituent units derived from diols) are derived from aliphatic diols.

[0027] Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,4'-biphenyldicarboxylic acid, and their ester-forming derivatives.

[0028] Examples of the aliphatic diol include ethylene glycol, 1,3-propylenediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, and their ester-forming derivatives.

[0029] Preferred polyester resins include, for example, polyethylene terephthalate resin, polyethylene terephthalate-isophthalate copolymer resin, polyethylene-1,4-cyclohexanedimethylene-terephthalate copolymer resin, polyethylene-2,6-naphthalenedicarboxylate resin, polyethylene-2,6-naphthalenedicarboxylate-terephthalate copolymer resin, polyethylene-terephthalate-4,4'-biphenyldicarboxylate resin, poly-1,3-propylene-terephthalate resin, polybutylene terephthalate resin, and polybutylene-2,6-naphthalenedicarboxylate resin.

[0030] Polyester resins that are available on the market can be optical resins, such as Toyobo Co., Ltd.'s "Byron" series, Eastman Chemical Co., Ltd.'s "Tritan" series, and SK Chemical Co., Ltd.'s "Ecozen" series.

[0031] When the resin that forms the base of the resin film is a cycloolefin resin, any known resin used as an optical resin can be used without particular limitation. The cycloolefin resin may be a resin consisting of a cycloolefin polymer obtained by polymerizing copolymerizable cyclic olefin monomers, a resin consisting of a cycloolefin copolymer obtained by polymerizing a cyclic olefin compound with other monomers, or a resin consisting of a mixture thereof. Examples of copolymerizable monomers include cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene. The cycloolefin resin may contain polymers of one or more of these monomers.

[0032] Cycloolefin resins can be optical resins available on the market, such as the Zeon Corporation's "Zeonex" series, JSR Corporation's "Arton" series, and Mitsui Chemicals, Inc.'s "Appel" series.

[0033] When the resin that forms the base of the resin film is a polyimide resin, the polyimide resin can be any known resin used as an optical resin without particular limitations. The polyimide resin can be an optical resin available on the market, such as the "Surprim" series from Mitsubishi Gas Chemical Company, Inc., or the "Aurum" series from Mitsui Chemicals, Inc.

[0034] When the resin that forms the base of the resin film is a cellulose ester resin, the cellulose ester resin can be any known resin used as an optical resin without particular limitations. Examples of cellulose ester resins include cellulose acetate propionate resin and cellulose acetate butyrate resin. The cellulose ester resin can be an optical resin available on the market, such as the "CAB" series or "CAP" series from Nagase & Co., Ltd.

[0035] (Optical Modifier) ​​The resin film for optical films according to this disclosure is characterized by containing a diacetal compound represented by formula (1). This diacetal compound functions as an optical modifier to adjust the optical properties of the film. According to this disclosure, by containing a diacetal compound of a specific structure, crystals or aggregate states exhibiting negative birefringence precipitate in a fibrous manner, and a resin film is obtained in which the birefringence is adjusted in the negative direction.

[0036] (In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ These are identical or different, and each represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, a C1-C4 halogenated alkyl group, or a halogen atom, respectively. ７ (This represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkenyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, or a C1-C4 halogenated alkyl group.)

[0037] In a resin film for optical films, from the viewpoint of obtaining a function to precipitate and adjust the birefringence of the resin film, R １ , R ２ , R ３ , R ４ , R ５ and R ６ Each of these elements may be the same or different from the others, and is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. １ , R ２ and R ３ One of them may be a hydrogen atom, and the other two may be alkyl groups having 1 to 4 carbon atoms. Also, R １ , R ２ and R ３ Two of these may be hydrogen atoms, and one may be an alkyl group having 1 to 4 carbon atoms. ４ , R ５ and R ６ One of them may be a hydrogen atom, and the other two may be alkyl groups having 1 to 4 carbon atoms. Also, R４ , R ５ and R ６ Two of these may be hydrogen atoms, and one may be an alkyl group having 1 to 4 carbon atoms. １ , R ２ , R ３ , R ４ , R ５ and R ６ All of these can be hydrogen atoms.

[0038] R ７ It is preferably a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkenyl group, and more preferably a hydrogen atom or a C1-C4 alkyl group.

[0039] As shown in equation (1), R ７Specifically, compounds in which the atom is a hydrogen atom include: 1,3:2,4-bis-O-benzylidene-D-sorbitol, 1,3:2,4-bis-O-(o-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-ethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-ethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-isopropylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-isopropylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-n-propylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-n-propylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-n-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-n-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-n-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-tert-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-tert-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-tert-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2',3'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2',4'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2',5'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3',5'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2',3'-Diethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(2',4'-Diethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(2',5'-Diethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(3',4'-Diethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(3',5'-Diethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(2',4',5'-Trimethylbenzylidene)-D-sorbitol, 1,3:2,4-Bis-O-(3',4',5'-Trimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2',4',5'-triethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3',4',5'-triethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-methoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-methoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-methoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-ethoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-ethoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-isopropoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-isopropoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-n-propoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-n-propoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-n-propoxybenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-methoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-methoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-methoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-ethoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-ethoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-isopropoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-isopropoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-n-propoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-n-propoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-n-propoxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-fluorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-fluorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-fluorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-chlorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-chlorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-chlorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-bromobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-bromobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-bromobenzylidene)-D-sorbitol, 1,3-O-benzylidene-2,4-O-(p-methylbenzylidene)-D-sorbitol, 1,3-O-(p-methylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(p-ethylbenzylidene)-D-sorbitol, 1,3-O-(p-ethylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(p-chlorobenzylidene)-D-sorbitol, 1,3-O-(p-chlorobenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(2',4'-dimethylbenzylidene)-D-sorbitol, 1,3-O-(2',4'-dimethylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(3',4'-dimethylbenzylidene)-D-sorbitol, 1,3-O-(3',4'-dimethylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-(p-methylbenzylidene)-2,4-O-(p-ethylbenzylidene)-D-sorbitol, 1,3-O-(p-ethylbenzylidene)-2,4-O-(p-methylbenzylidene)-D-sorbitol, 1,3-(p-methylbenzylidene)-2,4-O-(3',4'-dimethylbenzylidene)-D-sorbitol, 1,3-O-(3',4'-dimethylbenzylidene)-2,4-O-(p-methylbenzylidene)-D-sorbitol, 1,3-(p-ethylbenzylidene)-2,4-O-(3',4'-dimethylbenzylidene)-D-sorbitol, 1,3-O-(3',4'-dimethylbenzylidene)-2,4-O-(p-ethylbenzylidene)-D-sorbitol, 1,3-O-(p-methylbenzylidene)-2,4-O-(p-chlorobenzylidene)-D-sorbitol, Examples include 1,3-O-(p-chlorobenzylidene)-2,4-O-(p-methylbenzylidene)-D-sorbitol.

[0040] As shown in equation (1), R ７Specifically, compounds in which the group is a methyl group include: 1,3:2,4-bis-O-benzylidene-1-methylsorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(2',3'-dimethylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(2',4'-dimethylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(2',5'-dimethylbenzylidene)-1-methylsorbitol 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(3',5'-dimethylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-methoxybenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(3',4'-dichlorobenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(p-methoxycarbonylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-fluorobenzylidene)-1-methylsorbitol Examples include 1,3:2,4-bis-O-(3'-bromo-4'-ethylbenzylidene)-1-methylsorbitol.

[0041] As shown in equation (1), R ７Specifically, compounds in which the group is an ethyl group include: 1,3:2,4-bis-O-benzylidene-1-ethylsorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(2',3'-dimethylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(2',4'-dimethylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(2',5'-dimethylbenzylidene)-1-ethylsorbitol 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(3',5'-dimethylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-methoxybenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(3',4'-dichlorobenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(p-methoxycarbonylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-fluorobenzylidene)-1-ethylsorbitol Examples include 1,3:2,4-bis-O-(3'-bromo-4'-ethylbenzylidene)-1-ethylsorbitol.

[0042] As shown in equation (1), R ７Specifically, compounds in which the n-propyl group is present include: 1,3:2,4-bis-O-benzylidene-1-n-propylsorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(2',3'-dimethylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(2',4'-dimethylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(2',5'-dimethylbenzylidene)-1-n-propylsorbitol 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(3',5'-dimethylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-methoxybenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(3',4'-dichlorobenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(p-methoxycarbonylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-fluorobenzylidene)-1-n-propylsorbitol Examples include 1,3:2,4-bis-O-(3'-bromo-4'-ethylbenzylidene)-1-n-propylsorbitol.

[0043] As shown in equation (1), R ７Specifically, compounds in which the group is an allyl group include: 1,3:2,4-bis-O-benzylidene-1-allylsorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-1-allylsorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-1-allylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-allylsorbitol, 1,3:2,4-bis-O-(2',3'-dimethylbenzylidene)-1-allylsorbitol, 1,3:2,4-bis-O-(2',4'-dimethylbenzylidene)-1-allylsorbitol, 1,3:2,4-bis-O-(2',5'-dimethylbenzylidene)-1-allylsorbitol 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-1-allyl sorbitol, 1,3:2,4-bis-O-(3',5'-dimethylbenzylidene)-1-allyl sorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-methoxybenzylidene)-1-allyl sorbitol, 1,3:2,4-bis-O-(3',4'-dichlorobenzylidene)-1-allyl sorbitol, 1,3:2,4-bis-O-(p-methoxycarbonylbenzylidene)-1-allyl sorbitol, 1,3:2,4-bis-O-(3'-methyl-4'-fluorobenzylidene)-1-allyl sorbitol, Examples include 1,3:2,4-bis-O-(3'-bromo-4'-ethylbenzylidene)-1-allylsorbitol.

[0044] As shown in equation (1), R ７Further examples of compounds in which the atom is a hydrogen atom include, specifically, bis-1,3:2,4-(4'-ethyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-n-propyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-isopropyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-n-butyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-isobutyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-tert-butyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-secbutyl-2'-methylbenzylidene)sorbitol, Examples include bis-1,3:2,4-(4'-n-pentyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-isopentyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-neopentyl-2'-methylbenzylidene)sorbitol, bis-1,3:2,4-(4'-tertiarypentyl-2'-methylbenzylidene)sorbitol, and bis-1,3:2,4-(4'-secpentyl-2'-methylbenzylidene)sorbitol.

[0045] R ７ R may be any of a methyl group, an ethyl group, a propyl group, or a butyl group. For example, R ７ If is a methyl group, then the compounds represented by formula (1) can similarly be listed as 1-methylsorbitol having the benzylidene structure listed above. Instead of 1-methylsorbitol, 1-ethylsorbitol (R ７ (When it is an ethyl group), 1-n-propylsorbitol (R ７ (When it is an n-propyl group), 1-allylsorbitol (R ７ Compounds in which (the group is a 2-propenyl group) can be similarly listed. The resin film according to this disclosure may contain one or more of these compounds.

[0046] More preferably, the compound represented by formula (1) is 1,3:2,4-bis-O-benzylidene-D-sorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3',4'-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-methylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-ethylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene) 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-n-propylsorbitol, 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-n-propylsorbitol and 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-allylsorbitol are more preferred, and 1,3:2,4-bis-O-benzylidene-D-sorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-D-sorbitol and 1,3:2,4-bis-O-(p-n-propylbenzylidene)-1-n-propylsorbitol are even more preferred.

[0047] Diacetal compounds are commercially available, for example, as GELOL D, GELOL MD, GELOL DXR, Rika-I Just-100, Rika-I Just-200, Rika-I Just-300, and Milliken Corporation; Millad NX8000J, but the present invention is not limited to these examples.

[0048] (Resin Film) In the resin film according to this disclosure, the mass ratio of the optical modifier, which is a diacetal compound, to the amorphous resin is preferably 1% by mass or more, more preferably 5% by mass or more, from the viewpoint of allowing the optical modifier to exist in a crystalline or aggregated state and improving the dispersibility of the crystalline or aggregated diacetal compound, and preferably 20% by mass or less, more preferably 10% by mass or less, from the viewpoint of maintaining dispersibility and forming a film. At least a portion of the optical modifier contained in the resin film according to this disclosure precipitates in the film as crystals or in an aggregated state. The diacetal compound is typically in the form of fibrous crystals or aggregated states, and may include crystals with a high aspect ratio, such as needle-shaped crystals, columnar crystals, or plate-shaped crystals. The diacetal compound adjusts the birefringence in the negative direction.

[0049] The precipitation of diacetal compounds in the resin film can be confirmed, for example, by the following method. Specifically, as a pretreatment device, the resin film is cryopreserved (-125°C) using a cryomicrotome (with a diamond knife) in a Leica EM UC7 / FC7 frozen sectioning system (manufactured by Leica Microsystems) to produce ultrathin sections with a thickness of approximately 100 nm. The obtained sections are then processed using RuO2. ４ The section is exposed to a vapor atmosphere (room temperature) for 20 minutes to perform staining. The presence of precipitated diacetal compounds can be confirmed in images taken with a transmission electron microscope (TEM) of this stained section. For example, a field emission transmission electron microscope (FE-TEM) JEM-F200 (manufactured by JEOL Ltd.) can be used as the TEM, and imaging can be performed under conditions of an acceleration voltage of 200 kV. Note that the equipment and conditions used are examples and are not limited thereto. In the resin film according to this disclosure, in the TEM image, there may be multiple crystals or aggregated states of the diacetal compound in the form of elongated fibers, which are positioned in unspecified directions and intersect to form a network (mesh). Alternatively, the crystals or aggregated states of the diacetal compound may be oriented in the direction of flow. The precipitation of crystals or aggregated states in the film can also be confirmed by measuring the viscoelasticity of the film using a rheometer.

[0050] The birefringence of the resin film relating to this disclosure is not particularly limited, but for example, if the base resin is a cycloolefin copolymer or cycloolefin polymer, it is -5.0 × 10 －４ ~5.6 x 10 －４ It may be within this range. If the base resin is polycarbonate resin, then -2.0 × 10 －４ ~1.4 x 10 －４ It may be within that range.

[0051] The transparency of the resin film according to this disclosure is measured by a haze meter. Preferably, the haze value of the resin film according to this disclosure is 0.5 or less for a resin film with a thickness of 80 μm, and more preferably, the haze value of the resin film according to this disclosure is 0.2 or less for a resin film with a thickness of 40 μm. When the haze value is within this range, the resin film can be evaluated as transparent, and the resin film according to this disclosure can be applied to applications where transparency is required.

[0052] The thickness of the resin film according to this disclosure can be appropriately selected depending on the application and is not particularly limited, but as an example, it may be about 5 to 500 μm, and preferably about 10 to 200 μm. The resin film according to this disclosure has high transparency even in relatively thick films of about 100 μm (0.1 mm).

[0053] The resin film according to this disclosure may have controlled wavelength dispersibility. For example, the resin film according to this disclosure may have stronger wavelength dispersibility than a similar resin film that does not contain optical modifiers. In this case, the resin film according to this disclosure can be suitably used in applications where strong wavelength dispersibility is required (e.g., decorative films, reflective sheets, phase difference films, etc.).

[0054] Furthermore, the resin film according to this disclosure may have wavelength dispersibility equivalent to that of a similar resin film that does not contain an optical modifier. That is, it is preferable that the wavelength dispersibility of the base resin does not change even when an optical modifier is added. This is useful when it is desired to use a film in which the birefringence is adjusted in the negative direction while maintaining the wavelength dispersibility of the base resin film. Such a film can be used, for example, as a display film (more specifically, for example, a display film for VR / AR, a foldable display film, a rollable display film), etc.

[0055] Furthermore, the resin film according to this disclosure may have the opposite wavelength dispersion compared to a similar resin film that does not contain an optical modifier. That is, a resin film without an optical modifier may have wavelength dispersion (a property in which birefringence decreases from the short wavelength side to the high wavelength side), while a film to which an optical modifier is added may have inverse wavelength dispersion (a property in which birefringence increases from the short wavelength side to the high wavelength side). In this case, the resin film according to this disclosure can be suitably used, for example, in applications such as phase difference films.

[0056] The resin film relating to this disclosure may, insofar as it exhibits the effects relating to this disclosure, contain additives such as stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, foaming agents, lubricants, fillers, colorants, and plasticizers, as needed, in addition to amorphous resins and optical modifiers (diacetal compounds).

[0057] Because the resin film of the present invention has adjusted birefringence and transparency, it can be suitably used as an optical film, such as a polarizing plate protective film or phase difference film used in liquid crystal displays. This film can be applied to advanced displays such as organic EL and 3D displays, as well as pickup lenses.

[0058] (Method for manufacturing a resin film) The resin film according to this disclosure is obtained by mixing an amorphous resin and an optical modifier, heating the mixture to a first temperature which is above the softening temperature of the amorphous resin and below the decomposition temperature of the amorphous resin, and molding the resulting mixture in a specific manner. The manufacturing method includes the steps of: obtaining a resin composition by heating and mixing an amorphous resin having positive birefringence and a diacetal compound represented by formula (1) at a temperature above the softening point of the amorphous resin to dissolve the diacetal compound in the amorphous resin; molding the resin composition into a film; heating the resin composition at a temperature above the glass transition point of the amorphous resin and molding it while applying shear force in a molten state; and cooling while applying shear force.

[0059] In the process of obtaining the resin composition, the amorphous resin and the optical modifier may be mixed and then heated to a temperature above the softening temperature of the amorphous resin and below the decomposition temperature of the amorphous resin. Alternatively, the amorphous resin may be heated to the aforementioned temperature range and then mixed with the optical modifier. The latter method is preferred from the viewpoint of precipitating crystals or aggregated states in the resin film and obtaining a uniform film.

[0060] A mixture of amorphous resin and optical modifier is heated to a temperature above the softening temperature of the amorphous resin in order to dissolve the optical modifier in the molten amorphous resin. The softened amorphous resin then acts as a solvent for the optical modifier. That is, in the molten state, the optical modifier is considered to be dissolved in the amorphous resin. It is preferable to uniformly disperse the optical modifier in this molten mixture in the amorphous resin by known means such as stirring and kneading. Alternatively, the mixing of the amorphous resin and optical modifier may be carried out by solvent mixing (solution casting method).

[0061] The manufacturing method according to this disclosure includes a step of molding the resin composition while applying a shear force at a temperature above the glass transition temperature of the amorphous resin. Before or after this step, the resin composition may be temporarily molded into a film form by pressing, extrusion molding, injection molding, etc.

[0062] The resin composition can be molded into a film by, for example, extruding the obtained resin composition and then cooling it. The molding can be carried out by a general method for manufacturing composite materials made of thermoplastic resins, and is not particularly limited. Examples of manufacturing equipment include single-screw extruders, twin-screw extruders, Banbury mixers, and roll kneaders.

[0063] Next, the obtained resin composition (which may be molded) is heated to a temperature above the glass transition temperature of the amorphous resin, and molded while applying a shear force to the resin composition in a molten state. The shear force is not limited as long as the effects of this disclosure are obtained, but for example, when the thickness of the resin composition before molding is 500 μm, the shear force can be applied at a temperature of about 150 to 230°C. The shear rate is also not limited as long as the effects of this disclosure are obtained, but for example, 0.01 to 1000 s －１ It may be to a certain extent. In the manufacturing method according to this disclosure, the resin composition is molded by applying a shear force while heated to a temperature above its glass transition temperature, so that the diacetal compound is oriented in a form having negative birefringence and precipitates from the substrate resin.

[0064] Next, cooling is performed while applying a shear force. Cooling under shear force causes the diacetal compound to orient itself into a fibrous structure, and the diacetal compound precipitates in the film.

[0065] Next, the present invention will be described in more detail based on examples, but the present invention is not limited to such examples.

[0066] [Example 1] The weight ratio of cycloolefin resin (COP, Arton D4000, manufactured by JSR Corporation, glass transition temperature approximately 159°C) to 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol (BDMDS, manufactured by Shin Nippon Rika Co., Ltd.) was adjusted to 97:3, and the mixture was kneaded using an internal mixer (Laboplastmill model 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.). First, the raw materials were added at 220°C and 5 rpm for 5 minutes, and then kneaded at the same temperature at 30 rpm for 5 minutes to obtain the resin composition. Before kneading, the mixture was vacuum dried at 60°C for 3 hours. The obtained resin composition was pressed at 280°C and 4 MPa for 2 minutes using a manual hydraulic heating press (model IMS-481E, manufactured by Imoto Seisakusho Co., Ltd.). Next, the film was cooled at 25°C for 2 minutes to obtain a film with a thickness of approximately 500 μm. The obtained film was evaluated as follows. The glass transition temperature was determined by calculating E'' (loss modulus) using dynamic viscoelasticity measurement, and the peak of this value was taken as the glass transition temperature. The glass transition temperature of the resin composition in Example 1 was 150°C.

[0067] <Measurement and calculation of birefringence using a polarizing microscope> The obtained film was placed on a hot stage with a shearing function attached to the polarizing microscope and heated to 240°C. Then 1 second －１ The temperature was lowered to 190°C at a rate of 10°C / min while applying shear, and the light transmittance (DLI) was measured using a cross polarizer system during this time. A color filter was installed in the photodetector. The gap between the parallel disks was set to 500 μm. Using the DLI obtained from the measurement, the birefringence Δn was calculated according to the following formula. (DLI: light transmittance [%], I ０ : Light transmittance in an orthogonal polarizer system [-], I / / : Light transmittance in a parallel polarizer system [-], π: Pi, Γ: Phase difference [nm], λ ０ Wavelength: 633 nm, Light source: White light, d: Gap during measurement [nm], Δn: Birefringence [-]) The sign of Δn was determined by inserting a quarter-wave plate into the polarizing microscope after measuring birefringence with a polarizing microscope. ｘ >n ｙ In this case, birefringence is considered "positive", n ｘ <n ｙIn this case, the birefringence was defined as "negative". This measurement simulates the "step of heating the resin composition and molding it in a molten state while applying a shear force" in the method for producing the film according to the present disclosure.

[0068] <Measurement of Shear Stress> Shear stress was measured using a rheometer (manufactured by Anton Paar, model 302e). A parallel plate was used, and the gap between the plates was set to 1 mm. In the steady flow measurement, the shear stress was measured at 190 °C and a shear rate of 1 s －１ .

[0069] <Calculation of Stress-Optical Coefficient> The stress-optical coefficient (C Ｒ ) was calculated using the following formula based on the birefringence Δn calculated by a polarizing microscope and the shear stress (σ) calculated by a rheometer. C Ｒ [×10 －９ Pa －１ ] = Δn [×10 ４ ] / σ [Pa]

[0070] <Confirmation of Precipitation> Since the viscoelastic properties are different between a film in which the diacetal compound is precipitated in a crystalline or associated state and a film in which the diacetal compound exists without becoming a crystalline or associated state, precipitation was confirmed using a rheometer (manufactured by Anton Paar, model 302e). A parallel plate was used, the gap between the plates was set to 1 mm, and the measurement was performed at 200 °C in the frequency dependence measurement. The obtained results were plotted with the angular frequency (log ω) on the horizontal axis and the storage modulus (log G') on the vertical axis, and the slope was calculated from the value of log G' when the range of log ω was from 0 to -1 (log G' / log ω). When the ratio of log G' / log ω of the film containing the diacetal compound to log G' / log ω of the film consisting only of the base resin (shown as "log G' / log ω ratio" in the table) was 0.8 or less, the precipitation was marked as ○.

[0071] [Example 2] A resin composition was obtained in the same manner as in Example 1, except that the weight ratio of cycloolefin resin to 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol was 96:4. A film was then prepared in the same manner as in Example 1. The glass transition temperature of the resin composition in Example 2 was 148°C. The obtained film was evaluated in the same manner as in Example 1.

[0072] [Example 3] A resin composition was obtained in the same manner as in Example 1, except that the weight ratio of cycloolefin resin to 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol was 95:5. A film was then prepared in the same manner as in Example 1. The glass transition temperature of the resin composition in Example 3 was 145°C. The obtained film was evaluated in the same manner as in Example 1.

[0073] [Example 4] A resin composition was obtained in the same manner as in Example 1, except that the weight ratio of cycloolefin resin to 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol was 90:10. Next, a film was prepared in the same manner as in Example 1. The glass transition temperature of the resin composition in Example 4 was 145°C. The obtained film was evaluated in the same manner as in Example 1. Furthermore, frozen sections were prepared from the film after birefringence measurement using a polarizing microscope using the method described above, and TEM observation was performed. The TEM image is shown in [Figure 1]. As shown in [Figure 1], it was confirmed that diacetal compounds precipitated in the film and were oriented in the flow direction.

[0074] [Example 5] A resin composition was obtained in the same manner as in Example 1, except that 1,3:2,4-bis-O-(4-propylbenzylidene)-D-sorbitol (BPMN, Millad NX8000J, Milliken) was used as the diacetal compound instead of 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol. The glass transition temperature of the resin composition in Example 5 was 150°C. The obtained resin composition was pressed at 280°C and 4 MPa for 2 minutes using a manual hydraulic heating press (model IMS-481E, manufactured by Imoto Seisakusho Co., Ltd.). It was then cooled at 25°C for 2 minutes to obtain a film with a thickness of approximately 500 μm. The obtained film was evaluated in the same manner as in Example 1.

[0075] [Example 6] A resin composition was obtained in the same manner as in Example 5, except that the weight ratio of cycloolefin resin to 1,3:2,4-bis-O-(4-propylbenzylidene)-D-sorbitol was 90:10. The glass transition temperature of the resin composition in Example 6 was 133°C. A film was prepared by the same method and evaluated in the same manner as in Example 1.

[0076] [Comparative Example 1] A resin composition was prepared in the same manner as in Example 1, except that a diacetal compound was not mixed, and a film with a thickness of approximately 500 μm was obtained using the same method. The glass transition temperature of the resin composition of Comparative Example 1 was 159°C. It was evaluated in the same manner as in Example 1.

[0077] The configurations and evaluation results of Examples 1 to 6 and Comparative Example 1 are summarized in [Table 1]. The criteria for 〇 (Good) and ◎ (Very Good) were as follows: 〇 (Good): Δn value is 0 or less and 5.6 or less, and stress optical coefficient is 0 or less and 3.7 or less. ◎ (Very Good): Δn value is negative, and stress optical coefficient is negative.

[0078]

[0079] As shown in Table 1, in Examples 1 to 6, crystals or associated states of the diacetal compound were present in the film, and a resin film was obtained in which the birefringence changed in the negative direction compared to Comparative Example 1 that did not contain the diacetal compound. When comparing Δn of Examples 1 to 4 and Comparative Example 1, the birefringence changed more greatly in the negative direction by increasing the addition amount of the diacetal compound. Also, by increasing the addition amount, the stress-optical coefficient also changed in the negative direction. In particular, in Example 4, the birefringence and the applied optical coefficient became negative. It was confirmed that the same results were obtained in the comparison between Examples 5 and 6 and Comparative Example 1. It was confirmed that the modified cycloolefin polymer containing the diacetal compound increased Δn more to the negative side and decreased the stress-optical coefficient depending on the concentration of the additive.

[0080] <Measurement and Calculation of Wavelength Dispersion> Test pieces were obtained by cutting out each of the films of Example 1 and Comparative Example 1 into strips of 10 × 20 mm. The temperature was set to a temperature at which the value of log E' (Pa) by dynamic viscoelastic measurement became 8.5 (Pa), and the test piece for measurement was placed on a tensile machine (model DVE-3 S1000; manufactured by UBM Co., Ltd.), and the initial distance between the clamps was 10 mm, and it was stretched at a strain rate of 0.1 s －１ and stretched to 1.5 times. The film stretched to 1.5 times was immediately quenched by blowing cold air to obtain a test piece for wavelength dispersion measurement. The wavelength dispersion was measured using a phase difference measuring device (model KOBRA-WPR, manufactured by Oji Scientific Instruments Co., Ltd.). The phase differences (R449.9 nm, R498.0 nm, R548.0 nm, R588.8 nm, R628.8 nm, R751.0 nm) at each measurement wavelength (449.9 nm, 498.0 nm, 548.0 nm, 588.8 nm, 628.8 nm, 751.0 nm) were measured. The birefringence (Δn) at each wavelength was calculated by dividing the phase difference measured at each wavelength by the thickness of the stretched film. The ratio (Δn / Δn ５８８．８ｎｍ ) of the birefringence (Δn) at each wavelength to the birefringence (Δn ５８８．８ｎｍ ) at a wavelength of 588.8 nm was calculated.

[0081] The measurement results of the wavelength dispersibility of Example 1 and Comparative Example 1 are summarized in [Table 2].

[0082]

[0083] As shown in Table 2, the film of Example 1 exhibited wavelength dispersibility equivalent to that of Comparative Example 1, which was composed solely of cycloolefin resin. In other words, the wavelength dispersibility did not change with or without the addition of an optical modifier.

[0084] [Example 7] The weight ratio of bisphenol A polycarbonate resin (Yupilon H-3000R, manufactured by Mitsubishi Chemical Corporation, glass transition temperature approximately 153°C) to 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol (BDMDS, manufactured by Shin Nippon Rika Co., Ltd.) was adjusted to 99:1, and the mixture was kneaded using an internal mixer (Laboplastmill model 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.). First, the raw materials were added at 200°C and 5 rpm for 5 minutes, and then kneaded at the same temperature at 30 rpm for 5 minutes to obtain the resin composition. Before kneading, the mixture was vacuum dried at 60°C for 3 hours. The obtained resin composition was pressed at 220°C and 10 MPa for 2 minutes using a manual hydraulic heating press (model IMS-481E, manufactured by Imoto Seisakusho Co., Ltd.). Next, the film was cooled at 25°C for 2 minutes to obtain a film with a thickness of approximately 500 μm. The obtained film was evaluated as follows. The glass transition temperature of the obtained resin composition was measured in the same manner as in Example 1. The glass transition temperature of the resin composition of Example 7 was 144°C.

[0085] The obtained film was evaluated in the same manner as in Example 1. However, in the measurement of birefringence using a polarizing microscope, the cooling (cooling) start temperature was 220°C and the shear rate was 0.1 s. －１ The following conditions were met: In addition, the rheometer temperature was set to 180°C for the measurement of shear stress. Furthermore, in confirming precipitation, the slope was calculated from the value of logG' when logω was in the range of -1 to -2 (logG' / logω). Precipitation was considered successful if the ratio of logG' / logω of the film containing the diacetal compound to logG' / logω of the film consisting only of the substrate resin (indicated as "logG' / logω ratio" in the table) was 0.8 or less.

[0086] [Example 8] A resin composition was obtained in the same manner as in Example 7, except that the weight ratio of polycarbonate resin to BDMDS was 95:5. Next, a film was prepared in the same manner as in Example 7. The glass transition temperature of the resin composition in Example 8 was 143°C. The obtained film was evaluated in the same manner as in Example 7.

[0087] [Example 9] A resin composition was obtained in the same manner as in Example 7, except that 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol (BMDS, manufactured by Shin-Nippon Rika Co., Ltd.) was used as the diacetal compound instead of BDMDS. A film was then prepared in the same manner as in Example 7. The glass transition temperature of the resin composition of Example 9 was 148°C. The obtained film was evaluated in the same manner as in Example 7.

[0088] [Comparative Example 2] A resin composition was prepared in the same manner as in Example 7, except that a diacetal compound was not mixed, and a film with a thickness of approximately 500 μm was obtained using the same method. It was evaluated in the same manner as in Example 7. The glass transition temperature of the resin composition of Comparative Example 2 was 153°C.

[0089] The configurations and evaluation results of Examples 7 to 9 and Comparative Example 2 are summarized in [Table 3]. The criteria for 〇 (Good) and ◎ (Very Good) were as follows: 〇 (Good): Δn value is 0 or less and 1.4 or less, and stress optical coefficient is 0 or less and 2.2 or less. ◎ (Very Good): Δn value is negative, and stress optical coefficient is negative.

[0090]

[0091] As shown in Table 3, in Examples 7-9, crystalline or aggregated states of the diacetal compound were present in the film, resulting in resin films with a more negative birefringence than Comparative Example 2, which did not contain the diacetal compound. When comparing Δn of Examples 7-8 with that of Comparative Example 2, increasing the amount of diacetal compound added resulted in a greater negative change in birefringence. Increasing the amount of additive also changed the stress optical coefficient in a negative direction. In particular, in Example 8, both birefringence and applied optical coefficient became negative. It was confirmed that bisphenol A-polycarbonate polymers containing diacetal compounds increased Δn to the negative side and lowered the stress optical coefficient depending on the concentration of the additive.

[0092] The wavelength dispersibility of the films of Example 7 and Comparative Example 2 was measured using the method described above. The measurement results for wavelength dispersibility are summarized in [Table 4].

[0093]

[0094] As shown in Table 4, the film of Example 7 exhibited inverse wavelength dispersion (a property in which birefringence increases from the short wavelength side to the long wavelength side), while Comparative Example 2, which was composed only of bisphenol A-polycarbonate polymer, exhibited wavelength dispersion (a property in which birefringence decreases from the short wavelength side to the long wavelength side). In other words, by adding an optical modifier to the polycarbonate polymer, a film with inverse wavelength dispersion was obtained.

[0095] [Example 10] The weight ratio of amorphous polyethylene terephthalate resin (Byron 200, manufactured by Toyobo MC Co., Ltd., glass transition temperature approximately 79°C) and 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol (BMDS, manufactured by Shin Nippon Rika Co., Ltd.) was adjusted to 95:5, and the mixture was kneaded using an internal mixer (Laboplastmill model 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.). First, the raw materials were added at 240°C and 5 rpm for 3 minutes, and then kneaded at the same temperature at 50 rpm for 3 minutes to obtain the resin composition. Before kneading, the mixture was vacuum dried at 70°C for 4 hours. The obtained resin composition was pressed at 250°C and 10 MPa for 1 minute using a manual hydraulic heating press (model IMS-481E, manufactured by Imoto Seisakusho Co., Ltd.). Then it was cooled at 25°C for 2 minutes to obtain a film with a thickness of approximately 1 mm. The obtained films were evaluated as follows. The glass transition temperature of the obtained resin composition was measured in the same manner as in Example 1. The glass transition temperature of the resin composition of Example 10 was 77°C.

[0096] The obtained film was evaluated in the same manner as in Example 1. However, in the measurement of birefringence using a polarizing microscope, the cooling (cooling) start temperature was 240°C and the shear rate was 0.1 s. －１ The following conditions were met: In addition, the rheometer temperature was set to 90°C for the measurement of shear stress. Furthermore, in confirming precipitation, the slope was calculated from the value of logG' when logω was in the range of 0 to -1 (logG' / logω). Precipitation was considered successful if the ratio of logG' / logω of the film containing the diacetal compound to logG' / logω of the film consisting only of the substrate resin (indicated as "logG' / logω ratio" in the table) was 0.9 or less.

[0097] [Example 11] A resin composition was obtained in the same manner as in Example 10, except that the weight ratio of amorphous polyethylene terephthalate resin to BMDS was 90:10. Next, a film was prepared in the same manner as in Example 10. The glass transition temperature of the resin composition of Example 11 was 75°C. The obtained film was evaluated in the same manner as in Example 10.

[0098] [Example 12] A resin composition was obtained in the same manner as in Example 10, except that 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol (BDMDS, manufactured by Shin-Nippon Rika Co., Ltd.) was used as the diacetal compound instead of BMDS. A film was then prepared in the same manner as in Example 10. The glass transition temperature of the resin composition of Example 12 was 78°C. The obtained film was evaluated in the same manner as in Example 10.

[0099] [Comparative Example 3] A resin composition was prepared in the same manner as in Example 10, except that a diacetal compound was not mixed, and a film with a thickness of approximately 1 mm was obtained using the same method. It was evaluated in the same manner as in Example 10. The glass transition temperature of the resin composition of Comparative Example 3 was 79°C.

[0100] The configurations and evaluation results of Examples 10 to 12 and Comparative Example 3 are summarized in [Table 5]. The criteria for 〇 (Good) and ◎ (Very Good) were as follows: 〇 (Good): Δn value is 0 or less and 4.0 or less, and stress optical coefficient is 0 or less and 2.0 or less. ◎ (Very Good): Δn value is negative, and stress optical coefficient is negative.

[0101]

[0102] As shown in Table 5, in Examples 10-12, crystalline or aggregated states of the diacetal compound were present in the film, resulting in resin films with a more negative birefringence than Comparative Example 3, which did not contain the diacetal compound. When comparing Δn of Examples 10-12 with that of Comparative Example 3, increasing the amount of diacetal compound added resulted in a greater negative change in birefringence. Increasing the amount of additive also resulted in a negative change in the stress optical coefficient. In particular, in Example 11, both birefringence and applied optical coefficient became negative. It was confirmed that amorphous polyethylene terephthalate resin containing a diacetal compound increased Δn to the negative side and lowered the stress optical coefficient depending on the concentration of the additive.

[0103] The wavelength dispersibility of the films of Example 10 and Comparative Example 3 was measured using the method described above. The measurement results for wavelength dispersibility are summarized in [Table 6].

[0104]

[0105] As shown in Table 6, the film of Example 10 exhibited inverse wavelength dispersion (a property in which birefringence increases from the short wavelength side to the long wavelength side), whereas Comparative Example 3, which is composed only of amorphous polyethylene terephthalate polymer, exhibited wavelength dispersion (a property in which birefringence decreases from the short wavelength side to the long wavelength side). In other words, an inverse wavelength dispersion film was obtained by adding an optical modifier to amorphous polyethylene terephthalate polymer.

[0106] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the present invention is defined by the claims and is intended to include all modifications in the sense and scope equivalent to the claims.

Claims

1. A resin film for optical films, comprising an amorphous resin having positive birefringence and a diacetal compound represented by formula (1), wherein the diacetal compound precipitates in the film as crystals or aggregated states exhibiting negative birefringence. (In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ These are identical or different, and each represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, a C1-C4 halogenated alkyl group, or a halogen atom, respectively. ７ (This represents a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkenyl group, a C1-C4 alkoxy group, a C1-C4 alkoxycarbonyl group, or a C1-C4 halogenated alkyl group.) 2. The resin film for optical films according to claim 1, wherein the diacetal compound is contained in an amount of 1% by mass or more and 20% by mass or less relative to the amorphous resin.

3. The resin film for optical films according to claim 1 or claim 2, wherein the amorphous resin is a resin comprising at least one selected from the group consisting of cycloolefin resin, polycarbonate resin, and polyester resin.

4. A step of obtaining a resin composition by heating and mixing an amorphous resin having positive birefringence and a diacetal compound represented by the formula (1) at a temperature not lower than the softening point of the amorphous resin to dissolve the diacetal compound in the amorphous resin; a step of heating the resin composition and molding it in a molten state while applying a shearing force; and a step of cooling while continuously applying a shearing force from the molding step, the method for producing a resin film for an optical film. (In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbon atoms, a halogenated alkyl group having 1 to 4 carbon atoms or a halogen atom. R ７ represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkenyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 1 to 4 carbon atoms or a halogenated alkyl group having 1 to 4 carbon atoms.) 5. The method for producing a resin film for optical films according to claim 4, wherein the diacetal compound precipitates in the resin film for optical films as a crystal or aggregated state and is oriented in the flow direction, and the diacetal compound adjusts the birefringence in the negative direction.

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