Optical film, method for manufacturing an optical film, and resin composition for phase difference film

Abstract

To provide an optical film which has a glass transition temperature adjusted to a desired range in such a manner that it can be processed at a suitable temperature, and which is excellent in a balance among bleed-out resistance, solvent crack resistance and thermal stability, a method for manufacturing the optical film, and a resin composition for a retardation film.SOLUTION: An optical film contains a cycloolefin resin (A) and an additive (B), wherein the cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight average molecular weight of 100,000 or more, solubility of the additive (B) to hexane of 10 ml at a temperature of 25°C is 100 mg / 10 ml or less, the optical film has a glass transition temperature of 120°C or higher and lower than 154°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an optical film, a method for manufacturing an optical film, and a resin composition for a phase difference film. [Background technology]

[0002] Cycloolefin resins possess excellent transparency, optical properties, and mechanical properties. Therefore, their application to optical films incorporated into image display devices such as liquid crystal displays, plasma display panels, and organic EL displays is progressing (see, for example, Patent Documents 1-3).

[0003] In recent years, as image display devices have become more sophisticated, there has been a growing demand for improvements in various physical properties of the optical films that make up these devices. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2016 / 181756 [Patent Document 2] International Publication No. 2016 / 163213 [Patent Document 3] Japanese Patent Publication No. 2016-074776 [Overview of the project] [Problems that the invention aims to solve]

[0005] By the way, according to the studies of the present inventors, some optical films containing cycloolefin resins have insufficient solvent crack resistance, and it has been found that using a high molecular weight cycloolefin resin is effective in solving this problem. However, when using a high molecular weight cycloolefin resin, due to its toughness, it has poor moldability, and also has a tendency for the processing temperature to be high, and new problems such as coloring and yellowing due to oxidative degradation easily occur. Therefore, it has been found that by blending additives, the processing temperature can be lowered while maintaining the solvent crack resistance. However, when the blending amount of the additives increases, bleeding out easily occurs, and it has also become clear that the processing temperature drops too much and the weight loss temperature decreases, resulting in a decrease in thermal stability.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide an optical film having a glass transition temperature adjusted to a desired range so as to be processed at a suitable temperature, excellent in the balance of bleed-out resistance, solvent crack resistance, and thermal stability, a method for producing the optical film, and a resin composition for a retardation film.

Means for Solving the Problems

[0007] The inventors have found that the above problems can be solved by blending a specific additive having a low solubility in hexane in an optical film containing a high molecular weight cycloolefin resin, and have completed the present invention.

[0008] Aspects of the present invention relate to the following optical film, method for producing an optical film, and resin composition for a retardation film, which contain a high molecular weight cycloolefin resin (A) and a specific additive (B).

[0009] [1] An optical film containing a cycloolefin resin (A) and an additive (B), wherein the cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight average molecular weight of 100,000 or more, At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. An optical film having a glass transition temperature of 120°C or higher and less than 154°C.

[0010] [2] The optical film according to [1], wherein the cycloolefin resin (A) contains a cycloolefin resin (A2) having a weight-average molecular weight of 80,000 or less. [3] The optical film according to [1] or [2], wherein the additive (B) contains a compound (Ba) having two or more phenolic structures. [4] The optical film according to [3], wherein the molecular weight of the compound (Ba) is 550 or more. [5] The optical film according to [3] or [4], wherein the compound (Ba) is a compound selected from the group consisting of the following spiro compound derivatives (Ba-1), the following isocyanuric acid derivatives (Ba-2), and the following benzene derivatives (Ba-3). Spiro compound derivative (Ba-1): A spiro compound derivative having a spiro ring skeleton formed by the linking of two cyclic acetal skeletons. Isocyanuric acid derivative (Ba-2): An isocyanuric acid derivative having a structure in which three hydrogen atoms of isocyanuric acid are replaced by substituted benzyl groups on a benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring. Benzene derivative (Ba-3): A benzene derivative having a structure in which three hydrogen atoms of benzene are replaced by substituted benzyl groups on the benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring of the benzyl group.

[0011] [6] The optical film according to [5], wherein the spiro compound derivative (Ba-1) is a compound represented by the following general formula (BI). [ka] (In formula (BI), R 1 and R2 (This refers to a group represented as -C(CH3)2-CH2―OC(=O)―CH2―CH2―Y, where Y is a phenyl group having a hydroxyl group and optionally other substituents besides the hydroxyl group.)

[0012] [7] The optical film according to [6], wherein the spiro compound derivative (Ba-1) is 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diyl)dipropane-1,1-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate]. [8] The optical film according to any one of [1] to [7], wherein the content of the additive (B) is 0.5 parts by weight or more and 14 parts by weight or less per 100 parts by weight of the cycloolefin resin (A). [9] The optical film according to any one of [2] to [8], wherein the content of the cycloolefin resin (A1) and the cycloolefin resin (A2) is in a weight ratio of cycloolefin resin (A1) / cycloolefin resin (A2) = 80 / 20 to 60 / 40.

[10] The optical film according to any one of [1] to [9], wherein the temperature at which the optical film loses 1% of its weight is 300°C or higher.

[0013]

[11] A phase difference film formed by an optical film described in any one of [1] to

[10] .

[0014]

[12] A method for producing an optical film according to any one of [1] to

[11] , comprising the steps of casting a resin composition containing a cycloolefin resin (A), an additive (B), and a solvent (S) onto a support, evaporating the solvent (S), and peeling off the formed unstretched film, The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. A method for producing an optical film, wherein the content of the additive (B) is 0.5 parts by weight or more and 14 parts by weight or less per 100 parts by weight of the cycloolefin resin (A).

[0015]

[13] A resin composition for phase difference film containing a cycloolefin resin (A) and an additive (B), The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. A resin composition for phase difference films that provides a phase difference film having a glass transition temperature of 120°C or higher and less than 154°C. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an optical film in which the glass transition temperature is adjusted to a desired range and which has an excellent balance of bleed-out resistance, solvent crack resistance, and thermal stability, a method for manufacturing the optical film, and a resin composition for a phase difference film. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic perspective view showing an evaluation experiment of solvent crack resistance for an optical film according to one aspect of the present invention. [Modes for carrying out the invention]

[0018] Optical film The optical film contains a cycloolefin resin (A) and an additive (B). The optical film contains a cycloolefin resin (A) which is a cycloolefin resin (A1) with a weight-average molecular weight of 100,000 or more, and the solubility of the additive (B) in 10 ml of hexane is 100 mg / 10 ml or less at a temperature of 25°C. The glass transition temperature of optical films is between 120°C and 154°C. The optical film contains a high molecular weight cycloolefin resin (A) and an additive (B), so that the glass transition temperature is adjusted to a desired range so that it can be processed at a suitable temperature, and it has an excellent balance of bleed-out resistance, solvent crack resistance, and thermal stability.

[0019] Hereinafter, the essential or optional components contained in the optical film will be described.

[0020] (Cycloolefin resin (A)) The cycloolefin resin (A) is preferably a polymer of a cycloolefin monomer or a copolymer of a cycloolefin monomer and other copolymerizable monomers.

[0021] The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, and more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

[0022] [Chemical formula]

[0023] In general formula (A-1), R a1 ~R a4 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. p represents an integer of 0 to 2. However, all of R a1 ~R a4 do not simultaneously represent hydrogen atoms, and R a1 and R a2 do not simultaneously represent hydrogen atoms, and R a3 and R a4 do not simultaneously represent hydrogen atoms.

[0024] In general formula (A-1), R a1 ~R a4The hydrocarbon group having 1 to 30 carbon atoms represented by is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have linking groups containing, for example, halogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms, or silicon atoms. Examples of such linking groups include divalent polar groups such as carbonyl groups, imino groups, ether bonds, silyl ether bonds, and thioether bonds. Examples of hydrocarbon groups having 1 to 30 carbon atoms include methyl groups, ethyl groups, propyl groups, and butyl groups.

[0025] In general formula (A-1), R a1 ~R a4 Examples of polar groups represented by include carboxyl groups, hydroxyl groups, alkoxy groups, alkoxycarbonyl groups, aryloxycarbonyl groups, amino groups, amide groups, and cyano groups. Among these, carboxyl groups, hydroxyl groups, alkoxycarbonyl groups, and aryloxycarbonyl groups are preferred.

[0026] In general formula (A-1), p is preferably 1 or 2 from the viewpoint of improving the heat resistance of the optical film. This is because when p is 1 or 2, the resulting polymer becomes bulkier, and the glass transition temperature tends to improve.

[0027] [ka]

[0028] In general formula (A-2), R a5 R represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having 1 to 5 carbon atoms. a6 m represents a carboxyl group, hydroxyl group, alkoxycarbonyl group, aryloxycarbonyl group, amino group, amide group, cyano group, or halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom). m represents an integer from 0 to 2.

[0029] R in general formula (A-2)a5 It is preferable that this represents a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.

[0030] R in general formula (A-2) a6 Preferably, represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or an aryloxycarbonyl group.

[0031] In general formula (A-2), m is preferably 1 or 2 from the viewpoint of improving the heat resistance of the optical film. This is because when m is 1 or 2, the resulting polymer becomes bulkier, and the glass transition temperature tends to improve.

[0032] Cycloolefin monomers having the structure represented by general formula (A-2) are preferred because they improve solubility in organic solvents. Generally, organic compounds lose their crystallinity by disrupting their symmetry, thus improving their solubility in organic solvents. In general formula (A-2), R a5 and R a6 Because the substitution occurs only on one side of the ring-forming carbon atoms relative to the molecular axis of symmetry, the molecular symmetry is low. As a result, cycloolefin monomers having the structure represented by general formula (A-2) have high solubility and are suitable for manufacturing optical films by solution casting.

[0033] The content of cycloolefin monomers having the structure represented by general formula (A-2) in a polymer of cycloolefin monomers can be, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol% of the total amount of cycloolefin monomers constituting the cycloolefin resin. When a certain amount of cycloolefin monomers having the structure represented by general formula (A-2) is included, the orientation of the resin increases, and the phase difference value tends to rise.

[0034] Specific examples of cycloolefin monomers having the structure represented by general formula (A-1) are shown below in example compounds 1 to 14, and specific examples of cycloolefin monomers having the structure represented by general formula (A-2) are shown in example compounds 15 to 34.

[0035] [ka]

[0036] Examples of copolymerizable monomers that can copolymerize with cycloolefin monomers include copolymerizable monomers that can undergo ring-opening copolymerization with cycloolefin monomers, and copolymerizable monomers that can undergo addition copolymerization with cycloolefin monomers.

[0037] Examples of ring-opening copolymerizable monomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0038] Examples of copolymerizable monomers that can be added copolymerized include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 carbon atoms, such as ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0039] The content of cycloolefin monomers in a copolymer of cycloolefin monomers and copolymerizable monomers can be, for example, 20 to 80 mol%, preferably 30 to 70 mol%, relative to the total amount of monomers constituting the copolymer.

[0040] As described above, cycloolefin resin (A) is a polymer obtained by polymerizing or copolymerizing cycloolefin monomers having a norbornene skeleton, preferably cycloolefin monomers having a structure represented by general formula (A-1) or (A-2), and examples include the following.

[0041] (1) Cycloolefin monomer ring-opening polymer (2) A ring-opening copolymer of a cycloolefin monomer and a copolymerizable monomer that can be ring-opened therewith. (3) Hydrogenated ring-opening (co) polymers of the above (1) or (2) (4) The ring-opened (co)polymer of (1) or (2) above is cyclized by a Friedel-Crafts reaction, and then the (co)polymer is hydrogenated. (5) Saturated copolymer of a cycloolefin monomer and an unsaturated double bond-containing compound (6) Addition copolymers of cycloolefin monomers with vinyl cyclic hydrocarbon monomers and hydrogenated thereof (7) Alternating copolymer of cycloolefin monomer and (meth)acrylate

[0042] The polymers described in (1) to (7) above can all be obtained by known methods, for example, the methods described in Japanese Patent Publication No. 2008-107534 and Japanese Patent Publication No. 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization described in (2) above can be those described in paragraphs 0019 to 0024 of Japanese Patent Publication No. 2008-107534. The catalysts used in the hydrogenation described in (3) and (6) above can be those described in paragraphs 0025 to 0028 of Japanese Patent Publication No. 2008-107534. The acidic compound used in the Friedel-Crafts reaction described in (4) above can be those described in paragraph 0029 of Japanese Patent Publication No. 2008-107534. The catalysts used in the addition polymerization described in (5) to (7) above can be those described in paragraphs 0058 to 0063 of Japanese Patent Publication No. 2005-227606. The alternating copolymerization reaction described in (7) above can be carried out, for example, by the method described in paragraphs 0071 and 0072 of Japanese Patent Application Publication No. 2005-227606.

[0043] Among these, the polymers of (1) to (3) and (5) above are preferred, and the polymers of (3) and (5) above are more preferred. That is, the cycloolefin resin (A) is preferably made up of at least one of the structural units represented by the following general formula (B-1) and the following general formula (B-2), and is more preferably made up of only the structural units represented by general formula (B-2), or both the structural units represented by general formula (B-1) and the structural units represented by general formula (B-2), in order to increase the glass transition temperature and light transmittance of the obtained cycloolefin resin. The structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).

[0044] [ka]

[0045] In general formula (B-1), X represents -CH=CH- or -CH2CH2-. a1 ~R a4 and p are R in general formula (A-1), respectively. a1 ~R a4 It is synonymous with p.

[0046] [ka]

[0047] In general formula (B-2), X represents -CH=CH- or -CH2CH2-. a5 , R a6 and m are R in general formula (A-2), respectively. a5 , R a6 It is synonymous with m.

[0048] (High molecular weight cycloolefin resin) As the cycloolefin resin (A), a high molecular weight resin is preferred. The molecular weight of the high molecular weight cycloolefin resin (A) is preferably 30,000 to 100,000 in polystyrene terms, measured by gel permeation chromatography (GPC), more preferably 33,000 to 80,000, and even more preferably 33,000 to 65,000. The weight-average molecular weight (Mw) is 100,000 or higher, preferably 100,000 to 300,000, more preferably 110,000 to 250,000, and even more preferably 110,000 to 200,000. Using such a high molecular weight cycloolefin resin (A) improves the solvent crack resistance of the optical film. Hereinafter, the high molecular weight cycloolefin resin (A) may be referred to as "cycloolefin resin (A1)".

[0049] The cycloolefin resin (A1) may be a commercially available product. Examples of commercially available cycloolefin resins (A1) include Arton G (e.g., G7810, etc.) manufactured by JSR Corporation.

[0050] (Low molecular weight cycloolefin resin) As the cycloolefin resin (A), both high molecular weight cycloolefin resin (A) and low molecular weight cycloolefin resin (A) can be used in combination. The molecular weight of the low molecular weight cycloolefin resin (A) is preferably 3,000 to 25,000 in polystyrene terms, as measured by gel permeation chromatography (GPC), and more preferably 65,000 to 20,000. The weight-average molecular weight (Mw) is preferably 80,000 or less, more preferably 10,000 to 70,000, and even more preferably 20,000 to 65,000. By using such a low molecular weight cycloolefin resin (A) in combination, the content of the high molecular weight cycloolefin resin (A) is relatively reduced, resulting in the glass transition temperature of the entire cycloolefin resin (A) not becoming too high, thus allowing for a reduction in the content of the additive (B) described later. Hereinafter, the low molecular weight cycloolefin resin (A) may be referred to as "cycloolefin resin (A2)".

[0051] The cycloolefin resin (A2) may be a commercially available product. Examples of commercially available cycloolefin resins include Arton R manufactured by JSR Corporation (e.g., R4500, R4900, and R5000, etc.).

[0052] When cycloolefin resin (A1) and cycloolefin resin (A2) are used in combination, the weight ratio of cycloolefin resin (A1) / cycloolefin resin (A2) is preferably 90 / 10 to 40 / 60, more preferably 80 / 20 to 50 / 50, even more preferably 80 / 20 to 60 / 40, and particularly preferably 75 / 25 to 60 / 40, from the viewpoint of suppressing a decrease in the compatibility between the resins and suppressing whitening of the film using the resins. By using both resins in such proportions, the glass transition temperature can be lowered compared to when cycloolefin resin (A1) is used alone. As a result, the content of additive (B), which will be described later, can be reduced, thus suppressing the bleed-out of additive (B), and the decrease in the weight loss temperature is also suppressed, and as a result, the decrease in thermal stability can be suppressed.

[0053] The glass transition temperature (Tg) of the cycloolefin resin (A) is more preferably between 120°C and 250°C, and even more preferably between 120°C and 220°C. When the Tg is 120°C or higher, deformation can be suppressed when used under high-temperature conditions or when subjected to secondary processing such as coating or printing. On the other hand, when the Tg exceeds 350°C, molding becomes difficult, and the resin is more likely to deteriorate due to the heat generated during molding.

[0054] The cycloolefin resin (A) may contain additives such as specific hydrocarbon resins described in, for example, Japanese Patent Publication No. 9-221577 and Japanese Patent Publication No. 10-287732, or known thermoplastic resins, thermoplastic elastomers, rubbery polymers, rubber particles, etc., to the extent that the effects of the present invention are not impaired.

[0055] (Additive (B)) Additive (B) is used to adjust the glass transition temperature of the resulting optical film to a desired range so that it can be processed at a suitable temperature, and to achieve an excellent balance of bleed-out resistance, solvent crack resistance, and thermal stability. Additive (B) is a compound that is insoluble in hexane. In this specification, "insoluble in hexane" means that the solubility of additive (B) in 10 ml of hexane at a temperature of 25°C is 100 mg / 10 ml or less. The insolubility of additive (B) in hexane correlates with the solvent crack resistance of the optical film. From the viewpoint of improving the solvent crack resistance of the optical film, the solubility of additive (B) in 10 ml of hexane is preferably 50 mg / 10 ml or less, and more preferably 10 mg / 10 ml or less. The lower limit of the solubility of additive (B) in 10 ml of hexane is not particularly limited, but it is preferably 0 mg / 10 ml.

[0056] The weight loss temperature of additive (B) is not particularly limited, but from the viewpoint of suppressing bleed-out, it is preferable that the 5% weight loss temperature be 300°C or higher, and more preferably 320°C or higher. The upper limit of the 5% weight loss temperature of additive (B) is not particularly limited, but it is preferable that it be 500°C or lower. Furthermore, the temperature at which additive (B) loses 1% of its weight is preferably 250°C or higher, and more preferably 280°C or higher, from the viewpoint of suppressing bleed-out. The upper limit of the temperature at which additive (B) loses 1% of its weight is not particularly limited, but it is preferably 500°C or lower.

[0057] As an additive (B) that satisfies the aforementioned physical properties, for example, a compound (Ba) containing two or more phenol structures is used. As compound (Ba), for example, a compound used as a hindered phenol antioxidant is preferred.

[0058] (Compound Ba) Compound (Ba) can be selected from the group consisting of the following spiro compound derivatives (Ba-1), isocyanuric acid derivatives (Ba-2), and benzene derivatives (Ba-3). These compounds will be described in order below.

[0059] (Spiro compound derivative (Ba-1)) Spiro compound derivative (Ba-1) is a spiro compound derivative having a spiro ring skeleton formed by the linkage of two cyclic acetal skeletons. Spiro compound derivative (Ba-1) has the function of reducing the glass transition temperature of cycloolefin resin (A).

[0060] As the spiro compound derivative (Ba-1), the compound represented by the following formula (BI) is preferred. [ka]

[0061] In equation (BI), R 1 and R 2 This is a group represented as -C(CH3)2-CH2―OC(=O)―CH2―CH2―Y, where Y is a phenyl group having a hydroxyl group and optionally other substituents besides the hydroxyl group. Other substituents that the phenyl group Y may have include, for example, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and a tert-butyl group.

[0062] The spiro compound derivative (Ba-1) represented by formula (BI) is preferably 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diyl)dipropane-1,1-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate]. A commercially available compound can preferably be used; for example, ADEKA AO-80 manufactured by ADEKA Corporation can be used.

[0063] (Isocyanuric acid derivative (Ba-2)) The isocyanuric acid derivative (Ba-2) has a structure in which three hydrogen atoms of isocyanuric acid are replaced by substituted benzyl groups on a benzene ring, and has two or three phenol structures, each having one hydroxyl group on the benzene ring. The isocyanuric acid derivative (Ba-2) has the function of reducing the glass transition temperature of cycloolefin resin (A).

[0064] As the isocyanuric acid derivative (Ba-2), the compound represented by the following formula (B-II) is preferred. [ka]

[0065] In formula (B-II), R b1 ~R b15 Each of these is independently a hydrogen atom, a fluorine atom, a chlorine atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, provided that R b1 ~R b5 , R b6 ~R b10 , and R b11 ~R b15 In each of the three groups, only one substituent in each group is a hydroxyl group.

[0066] R b1 ~R b15 Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, and n-tridecyl groups, as well as alkyl groups that are structurally isomers of these alkyl groups.

[0067] R b1 ~R b15Examples of alkoxy groups having 1 to 20 carbon atoms include methoxy, ethoxy, n-propanoxy, isopropanoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-dodecyloxy, n-undecyloxy, and alkoxy groups that are structurally isomers of these alkoxy groups.

[0068] The isocyanuric acid derivative (Ba-2) represented by formula (B-II) is preferably 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione. A commercially available compound can preferably be used; for example, ADEKA AO-20 manufactured by ADEKA Corporation can be used.

[0069] (Benzene derivative (Ba-3)) The benzene derivative (Ba-3) has a structure in which three hydrogen atoms of benzene are replaced by substituted benzyl groups on the benzene ring, and the benzyl group has two or three phenol structures, each having one hydroxyl group on the benzene ring. The benzene derivative (Ba-3) has the function of reducing the glass transition temperature of the cycloolefin resin (A).

[0070] As the benzene derivative (Ba-3), a compound represented by the following formula (B-III) is preferred. [ka]

[0071] In formula (B-III), R c1 ~R c18 Each of these is independently a hydrogen atom, a fluorine atom, a chlorine atom, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, provided that R c4 ~R c8 , R c9 ~R c13, and R c14 ~R c18 In each of the three groups, only one substituent in each group is a hydroxyl group.

[0072] R c1 ~R c18 Examples of alkyl groups having 1 to 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, t-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, and n-tridecyl groups, as well as alkyl groups that are structurally isomers of these alkyl groups.

[0073] R c1 ~R c18 Examples of alkoxy groups having 1 to 20 carbon atoms include methoxy, ethoxy, n-propanoxy, isopropanoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-dodecyloxy, n-undecyloxy, and alkoxy groups that are structurally isomers of these alkoxy groups.

[0074] The benzene derivative (Ba-3) represented by formula (B-III) is preferably 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene. A commercially available compound can preferably be used; for example, ADEKA AO-330 manufactured by ADEKA Corporation can be used.

[0075] The molecular weight of additive (B) is preferably 550 or more, more preferably 600 or more, and even more preferably 650 or more.

[0076] From the viewpoint of reducing the glass transition temperature of the optical film, the content of additive (B) is preferably 0.2 parts by weight or more, and more preferably 0.5 parts by weight or more, per 100 parts by weight of cycloolefin resin (A). From the viewpoint of suppressing bleed-out, the upper limit of the content of additive (B) is preferably 14 parts by weight or less, more preferably 10 parts by weight or less, even more preferably 7 parts by weight or less, and even more preferably 5 parts by weight or less, per 100 parts by weight of cycloolefin resin (A). When using a blend of cycloolefin resin (A1) and cycloolefin resin (A2) as the cycloolefin resin (A), the content of additive (B) is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and most preferably 1.5 parts by weight or less, from the viewpoint of further suppressing bleed-out. In order to reduce the content of additive (B), it is effective to incorporate the low molecular weight cycloolefin resin (A) mentioned above. By adjusting the content of additive (B), the glass transition temperature of the optical film can be adjusted to a desired range.

[0077] The amount of compound (Ba) contained in additive (B) is not particularly limited, but is preferably more than 50 parts by weight (i.e., the main component) per 100 parts by weight of additive (B), more preferably 80 parts by weight or more, even more preferably 90 parts by weight or more, even more preferably 95 parts by weight or more, and particularly preferably 100 parts by weight.

[0078] (Other ingredients) The optical film may contain components other than the cycloolefin resin (A) and the spiro compound derivative (B) (hereinafter also referred to as "other components"), as long as they do not impair the effects of the present invention. Examples of other components include antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, specific wavelength absorbers, phase difference adjusters, lubricants, antiblocking agents, plasticizers, antistatic agents, fluorescent whitening agents, and the like.

[0079] ≪Manufacturing Method for Optical Films≫ Examples of methods for manufacturing optical films include melt extrusion, solution casting (solution casting), calendering, and compression molding. Among these, solution casting is preferred.

[0080] The solution casting method includes, for example, a step of preparing a resin composition by mixing a cycloolefin resin (A), a spiro compound derivative (B), other components, and a solvent (S); a step of casting the resin composition; a step of evaporating the solvent; a step of peeling the unstretched film; a drying step; and a stretching step.

[0081] Solvents used in the solution casting method include, for example, chlorinated solvents such as chloroform and methylene chloride; aromatic solvents such as toluene, xylene, benzene, and mixtures thereof; alcoholic solvents such as methanol, ethanol, isopropanol, n-butanol, and 2-butanol; and methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, and diethyl ether. Only one solvent may be used, or two or more may be used in combination.

[0082] In the method for manufacturing the optical film described above, a preferred embodiment of the solution casting method includes the steps of casting a resin composition containing a cycloolefin resin (A), an additive (B), and a solvent (S) onto a support, evaporating the solvent (S), and peeling off the formed unstretched film. The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. An example of a method for manufacturing an optical film is one in which the content of additive (B) is 0.5 parts by weight or more and 14 parts by weight or less per 100 parts by weight of the cycloolefin resin (A). Examples of the above-mentioned support include polyester film. The cycloolefin resin (A) and additive (B) described above are the same as those explained in the section on "Optical Films" above.

[0083] ≪Physical Properties of Optical Films≫ (Glass transition temperature) In optical films, the upper limit of the glass transition temperature (Tg) is less than 154°C, preferably 153°C or lower, more preferably 152°C or lower, and even more preferably 150°C or lower. Having a Tg below 154°C allows for the stable manufacture of optical films even when there are constraints on increasing the molding temperature. In optical films, the lower limit of the glass transition temperature (Tg) is 120°C or higher, more preferably 130°C or higher, and even more preferably 140°C or higher. When the glass transition temperature is 120°C or higher, it can be suitably used even in applications where heat resistance is required, such as automotive applications, where there are constraints.

[0084] (Solvent crack resistance) The optical film preferably has excellent solvent crack resistance. Specifically, when 500 μl of hexane is dropped onto the surface of the optical film and held for 30 seconds, then the optical film is inverted, and 500 μl of hexane is dropped onto the back surface of the optical film and held for 30 seconds, and the process is repeated, such that (1) film is set, (2) first hexane exposure, (3) first inversion, (4) second hexane exposure, (5) second inversion, (6) third hexane exposure, ... (and so on), it is preferable that the film does not break after the first inversion until before the second hexane exposure (exposure to both sides of the film) (breakage occurs from (3) onwards), more preferably that the film does not break after the first inversion until after the completion of the second hexane exposure (breakage occurs from (4) onwards), even more preferably that the film does not break after the second inversion until before the third hexane exposure (breakage occurs from (5) onwards), and particularly preferably that the film does not break after the second inversion until after the completion of the third hexane exposure (breakage occurs from (6) onwards).

[0085] (Phase difference manifestation) The optical film preferably exhibits excellent phase difference characteristics. Specifically, when the optical film is stretched to 100% at a stretching rate of 100% / min at Tg+5°C relative to its Tg, the front phase difference [nm] / thickness [μm] value should be 4 × 10⁻⁶. -3 It is preferable that the above conditions are met.

[0086] (weight loss temperature) Optical films preferably exhibit excellent thermal stability. Thermal stability can be evaluated based on the temperature of weight loss. The lower limit of the 1% weight loss temperature of the optical film is not particularly limited, but is preferably 300°C or higher, and more preferably 320°C or higher. The upper limit of the 1% weight loss temperature of the optical film is not particularly limited, but is preferably 500°C or lower. The lower limit of the 5% weight loss temperature of the optical film is not particularly limited, but is preferably 380°C or higher, and more preferably 400°C or higher. The upper limit of the 5% weight loss temperature of the optical film is not particularly limited, but is preferably 500°C or lower. Thermal stability can be improved by reducing the content of triazine derivative (B).

[0087] (Bleed-out resistance) The optical film preferably has excellent bleed-out resistance. Bleed-out resistance can be improved by reducing the content of triazine derivative (B). Specifically, when optical films are left for 336 hours under conditions of 85°C and 85% humidity, and then the haze of each film is measured, it is preferable that the increase in the total haze value is less than 1.0%, and more preferably less than 0.5%.

[0088] (Application) The optical film of this embodiment is preferably a functional film used in various display devices such as liquid crystal displays, plasma displays, and organic EL displays, as well as touch panels. Specifically, the optical film of this embodiment may be a polarizing plate protective film for liquid crystal displays, a phase difference film, an anti-reflective film, a brightness-enhancing film, a hard coat film, an anti-glare film, an anti-static film, an optical compensation film for widening the viewing angle, etc. Typically, the optical film of this embodiment is a phase difference film.

[0089] ≪Resin composition for phase difference film≫ The resin composition for phase difference films contains a cycloolefin resin (A) and an additive (B). The resin composition for phase difference films contains a cycloolefin resin (A) which is a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. A phase difference film is provided with a glass transition temperature of 120°C or higher and less than 154°C. The resin composition for phase difference films contains a high molecular weight cycloolefin resin (A) and an additive (B), thereby adjusting the glass transition temperature within a desired range so that the resulting phase difference film can be processed at a suitable temperature, and exhibiting an excellent balance of bleed-out resistance, solvent crack resistance, and thermal stability.

[0090] The resin composition for phase difference films is a raw material for manufacturing the optical films mentioned above. The cycloolefin resin (A) and additive (B) described above are the same as those described in the section on "Optical Films" above. The physical properties of the phase difference film described above are the same as those of the optical film described in the section on "Physical Properties of Optical Films" above. [Examples]

[0091] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0092] [Examples 1-13 and Comparative Examples 1-7] (Materials used) In the examples and comparative examples, the following A1 to A2 were used as cycloolefin resin (A). Hereafter, cycloolefin resin (A) will be abbreviated as "COP resin (A)". A1: ARTON G7810 (manufactured by JSR, weight average molecular weight = 140,000) A2: ARTON R5000 (manufactured by JSR, weight average molecular weight = 50,000)

[0093] In the examples and comparative examples, the following B1 to B5 were used as additives (B). B1 to B3 are compounds corresponding to specific additives (B) in the embodiment of the present invention, and B4 to B5 are comparative compounds. B1: ADEKA stub AO-80 (made by ADEKA) B2: ADEKA stub AO-20 (made by ADEKA) B3: ADEKA stub AO-330 (made by ADEKA) B4: Sumirizer GM (manufactured by Sumitomo Chemical Co., Ltd.) B5: Chimassorb 81 (manufactured by BASF Japan)

[0094] [ka]

[0095] In the examples and comparative examples, the following S1 was used as the solvent (S). S1: Methylene chloride

[0096] (Production of optical films) Each resin composition was obtained by mixing COP resin (A), additive (B), and solvent (S) in the quantities shown in Table 2 below. As the support film, a coated PET film was used, which consisted of a PET film manufactured by Toray Industries, Inc. (product name: Lumirror) with a length of 1000 m, a film thickness of 100 μm, and a width of 1600 mm, with one side surface coated with an acrylic resin composition with a film thickness of 1.2 μm. The roughness Ry of the coated surface of this support film was 210 nm, and the pencil hardness was B. Using this support film, a resin solution consisting of the above resin composition at a temperature of 20°C was applied to the opposite side of the coated surface and dried, and the resulting primary dried film was wound together with the support film. Subsequently, the obtained primary dried film and support film were separated and dried using a roll suspension type drying apparatus until the residual solvent content was 0.25% by weight, to produce optical films of Examples 1 to 13 and Comparative Examples 1 to 7 with an average film thickness of 60 μm and a length of 900 m.

[0097] <Rating> The solubility of additive (B) used in the experiment was evaluated according to the following method, including its methylene chloride solubility, hexane solubility, and weight loss temperature. The results are shown in Table 1. Furthermore, the glass transition temperature, solvent crack resistance, phase difference formation, weight loss temperature, and bleed-out resistance of the resulting optical film were evaluated according to the following method. The results are shown in Table 2.

[0098] [Physical properties of additive (B)] (Soluble to methylene chloride) At a temperature of 25°C, the solubility of additive (B) in 10 ml of methylene chloride was evaluated as dissolved ("○") if 100 mg / 10 ml or more dissolved and the solution became completely clear; otherwise, it was evaluated as insoluble ("×").

[0099] (Hexane solubility) At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane was evaluated as dissolved if 100 mg / 10 ml or more dissolved, resulting in a completely clear solution; otherwise, it was evaluated as insoluble.

[0100] (1% weight loss temperature) The temperature at which a 1% weight loss was observed at a heating rate of 20°C / min was defined as the 1% weight loss temperature.

[0101] (5% weight loss temperature) The temperature at which a 5% weight loss was observed at a heating rate of 20°C / min was defined as the 5% weight loss temperature.

[0102] [Physical properties of optical films] (Glass transition temperature (Tg)) Measurements were taken using a differential scanning calorimeter (DSC, SII Corporation, DSC7020) under a nitrogen atmosphere at a heating rate of 20°C / min, and the results were determined by the midpoint method.

[0103] (Solvent crack resistance) Each optical film with an average thickness of 60 μm was cut to 9 cm vertically and 2 cm horizontally. As shown in Figure 1, a weight adjusted to 2.45 MPa was suspended from one end of the optical film in the longitudinal direction using a clip, and the film was suspended from a metal bar with a diameter of 1 cm as shown in Figure 1. The other end of the optical film in the longitudinal direction was fixed with a fixing means (not shown), and 500 μl of hexane was dropped from the top dropping funnel and held for 30 seconds. If the film did not break after 30 seconds, the front and back surfaces of the optical film were reversed, and 500 μl of hexane was dropped onto the surface that had been in contact with the bar during the first dropping, making it the air surface, and held for 30 seconds in the same manner. This was repeated, and the solvent crack resistance was evaluated based on how many reversals it took before the film broke. The evaluation criteria are described below. The steps were as follows: (1) film set, (2) first hexane exposure, (3) first inversion, (4) second hexane exposure, (5) second inversion, (6) third hexane exposure, ... (and so on). ○: Breakdown occurs after the second inversion ((5) Breakdown occurs after the second inversion) △: Rupture occurred between the first inversion and the second hexane drop (exposure to both sides) and before the second inversion ((3) Rupture occurred during the first inversion or (4) second hexane exposure). ×: Breakdown occurs with the first hexane drop before inversion (first hexane exposure, i.e., (1) film set or (2) first hexane exposure).

[0104] (Phase difference manifestation) Each optical film was cut to a length of 7 cm and width of 4 cm, stretched to 100% at a stretching speed of 100% / min at a temperature of Tg + 5°C relative to the optical film's Tg, and evaluated as having phase difference [nm] / thickness [μm].

[0105] (1% weight loss temperature) The temperature at which a 1% weight loss was observed at a heating rate of 20°C / min was defined as the 1% weight loss temperature.

[0106] (5% weight loss temperature) The temperature at which a 5% weight loss was observed at a heating rate of 20°C / min was defined as the 5% weight loss temperature.

[0107] (Bleed-out resistance) Each optical film was left for 336 hours under conditions of 85°C and 85% humidity. After that, haze measurements were taken for each film, and its bleed-out resistance was evaluated according to the following criteria. ○: Total haze value increase is less than 0.5% △: Total haze value increase is less than 1.0% ×: The increase in total haze value is 1.0% or more.

[0108] [Table 1]

[0109] [Table 2]

[0110] Table 2 shows that in the optical films containing COP resin (A), Comparative Examples 4 and 5, which contained any of B4 to B5 as additive (B), all showed a reduction in Tg to below 154°C compared to Comparative Example 1, which did not contain additive (B). However, the weight loss temperature was significantly lower, and the bleed-out resistance was also inferior. On the other hand, when any of B1 to B3 was added as additive (B), as shown in Examples 1 to 3 and 12 to 13, the Tg was reduced to below 154°C, and an optical film with an excellent balance of bleed-out resistance, solvent crack resistance, and thermal stability was obtained.

Claims

1. An optical film containing a cycloolefin resin (A) and an additive (B), The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. The additive (B) contains a compound (B-a) having two or more phenol structures, The compound (B-a) is a compound selected from the group consisting of the following spiro compound derivatives (B-a-1), the following isocyanuric acid derivatives (B-a-2), and the following benzene derivatives (B-a-3). An optical film having a glass transition temperature of 120°C or higher and less than 154°C. Spiro compound derivative (B-a-1): A spiro compound derivative having a spiro ring skeleton formed by the linking of two cyclic acetal skeletons. Isocyanuric acid derivative (B-a-2): An isocyanuric acid derivative having a structure in which three hydrogen atoms of isocyanuric acid are replaced by substituted benzyl groups on a benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring. Benzene derivative (B-a-3): A benzene derivative having a structure in which three hydrogen atoms of benzene are replaced by substituted benzyl groups on the benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring of the benzyl group.

2. The optical film according to claim 1, wherein the cycloolefin resin (A) contains a cycloolefin resin (A2) having a weight-average molecular weight of 80,000 or less.

3. The optical film according to claim 1, wherein the molecular weight of the compound (B-a) is 550 or more.

4. The optical film according to claim 1, wherein the spiro compound derivative (B-a-1) is a compound represented by the following general formula (B-I). 【Chemistry 1】 (In formula (BI), R １ and R ２ is -C(CH ３ ) ２ -CH ２ -OC(=O)-CH ２ ―CH ２ —This is a group represented by Y, where Y is a phenyl group having a hydroxyl group and optionally other substituents besides the hydroxyl group.

5. The optical film according to claim 4, wherein the spiro compound derivative (B-a-1) is 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5,5]undecane-3,9-diyl)dipropane-1,1-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate].

6. The optical film according to claim 1 or 2, wherein the content of the additive (B) is 0.5 parts by weight or more and 14 parts by weight or less per 100 parts by weight of the cycloolefin resin (A).

7. The optical film according to claim 2, wherein the content of the cycloolefin resin (A1) and the cycloolefin resin (A2) is such that, by weight ratio, cycloolefin resin (A1) / cycloolefin resin (A2) = 80 / 20 to 60 / 40.

8. The optical film according to claim 1 or 2, wherein the temperature at which the optical film loses 1% of its weight is 300°C or higher.

9. A phase difference film formed by the optical film described in claim 1 or 2.

10. A method for producing an optical film according to claim 1, comprising the steps of casting a resin composition containing a cycloolefin resin (A), an additive (B), and a solvent (S) onto a support, evaporating the solvent (S), and peeling off the formed unstretched film, The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. The additive (B) contains a compound (B-a) having two or more phenol structures, The compound (B-a) is a compound selected from the group consisting of the following spiro compound derivatives (B-a-1), the following isocyanuric acid derivatives (B-a-2), and the following benzene derivatives (B-a-3). A method for manufacturing an optical film, wherein the content of the additive (B) is 0.5 parts by weight or more and 14 parts by weight or less per 100 parts by weight of the cycloolefin resin (A). Spiro compound derivative (B-a-1): A spiro compound derivative having a spiro ring skeleton formed by the linking of two cyclic acetal skeletons. Isocyanuric acid derivative (B-a-2): An isocyanuric acid derivative having a structure in which three hydrogen atoms of isocyanuric acid are replaced by substituted benzyl groups on a benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring. Benzene derivative (B-a-3): A benzene derivative having a structure in which three hydrogen atoms of benzene are replaced by substituted benzyl groups on the benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring of the benzyl group.

11. A resin composition for phase difference films containing a cycloolefin resin (A) and an additive (B), The cycloolefin resin (A) contains a cycloolefin resin (A1) having a weight-average molecular weight of 100,000 or more. At a temperature of 25°C, the solubility of additive (B) in 10 ml of hexane is 100 mg / 10 ml or less. The additive (B) contains a compound (B-a) having two or more phenol structures, The compound (B-a) is a compound selected from the group consisting of the following spiro compound derivatives (B-a-1), the following isocyanuric acid derivatives (B-a-2), and the following benzene derivatives (B-a-3). A resin composition for phase difference films that provides a phase difference film having a glass transition temperature of 120°C or higher and less than 154°C. Spiro compound derivative (B-a-1): A spiro compound derivative having a spiro ring skeleton formed by the linking of two cyclic acetal skeletons. Isocyanuric acid derivative (B-a-2): An isocyanuric acid derivative having a structure in which three hydrogen atoms of isocyanuric acid are replaced by substituted benzyl groups on a benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring. Benzene derivative (B-a-3): A benzene derivative having a structure in which three hydrogen atoms of benzene are replaced by substituted benzyl groups on the benzene ring, and having two or three phenol structures, each having one hydroxyl group on the benzene ring of the benzyl group.

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