Resin film, retardation film, and method of manufacturing resin film

Abstract

To provide a resin film which offers a superior anti-blocking property and can exhibit sufficient in-plane birefringence when stretched, and to provide a retardation film and a method of manufacturing the resin film.SOLUTION: A resin film according to an embodiment of the present invention contains a resin material used as a matrix and an anti-blocking agent dispersed in the resin material, where the content of the anti-blocking agent is 350-3000 ppm, and a difference in refractive index between the resin material and the anti-blocking agent is 0.10 or less in absolute terms.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin film, a retardation film, and a method for producing a resin film. [Background technology]

[0002] Resin films are widely used in various industrial products. For example, it is known that a retardation film is produced by stretching a resin film in a predetermined direction (see, for example, Patent Document 1).

[0003] Such resin films are generally collected by being wound into a roll with a release liner attached to its surface, but when the resin film with the release liner attached is wound into a roll, the unevenness of the release liner may be transferred to the resin film, resulting in dents being formed in the resin film.

[0004] For this reason, studies have been conducted on winding up resin films without attaching a release liner. However, when a resin film is wound into a roll without a release liner, there is a risk of blocking, in which resin films stick to each other. In this regard, while adding an antiblocking agent (hereinafter referred to as an AB agent) to a resin film can impart antiblocking properties to the resin film, it may not be possible to fully exhibit in-plane birefringence when the resin film is stretched. Therefore, it is difficult for a resin film to have both excellent antiblocking properties and the ability to exhibit in-plane birefringence through stretching. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7096940 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above-mentioned conventional problems, and its main object is to provide a resin film, a retardation film, and a method for producing a resin film that have excellent antiblocking properties and can fully exhibit in-plane birefringence by stretching. [Means for solving the problem]

[0007] [1] A resin film according to one embodiment includes a resin material as a matrix and an antiblocking agent dispersed in the resin material. The antiblocking agent has an average primary particle size of 0.1 μm to 1.3 μm. The content of the antiblocking agent in the resin film is 350 ppm to 3000 ppm. [2] In the resin film described in [1] above, the indentation modulus at 25°C is 2.0 N / mm 2 ~6.5N / mm 2 may be. [3] In the resin film according to the above [1] or [2], the coefficient of dynamic friction may be 1.0 or less. [4] In the resin film according to any one of [1] to [3] above, the resin material may contain a polycarbonate resin. [5] In another aspect of the present invention, a retardation film includes a resin material as a matrix and an antiblocking agent dispersed in the resin material. The average primary particle diameter of the antiblocking agent is 0.1 μm to 1.3 μm. The content of the antiblocking agent is 350 ppm to 3000 ppm. The retardation film has an in-plane birefringence Δn(550) of 0.0045 or more. [6] In yet another aspect of the present invention, a method for producing a resin film includes the steps of: mixing a molten resin material with an antiblocking agent to prepare a resin composition; passing the resin composition through a filter; and extrusion-molding the resin composition after passing through the filter. The average primary particle diameter of the antiblocking agent is 0.1 μm to 1.3 μm. The content of the antiblocking agent in the resin composition is 350 ppm to 3000 ppm. [7] In the method for producing a resin film according to the above item [6], the filter may be a screen mesh, and the opening of the screen mesh may be 0.035 mm to 0.070 mm. [8] The method for producing a resin film according to [6] or [7] above may further include a step in which a take-up member takes up the resin film. [Effects of the Invention]

[0008] According to an embodiment of the present invention, a resin film having excellent anti-blocking properties and capable of sufficiently exhibiting in-plane birefringence by stretching can be realized, and a retardation film having excellent anti-blocking properties and sufficient in-plane birefringence can be realized. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a resin film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Representative embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. In addition, in order to clarify the explanation, the width, thickness, shape, etc. of each part may be shown schematically in the drawings compared to the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

[0011] (Definition of terms and symbols) The definitions of terms and symbols used in this specification are as follows. (1) Refractive index (nx, ny, nz) "nx" is the refractive index in the direction in which the in-plane refractive index is greatest (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane birefringence (Δn) "Δn(λ)" is the in-plane birefringence measured with light of wavelength λ nm at 23° C. For example, "Δn(550)" is the in-plane birefringence measured with light of wavelength 550 nm at 23° C. In-plane birefringence (Δn) is calculated from the formula: Δn=nx-ny. (3) In-plane phase difference (Re) "Re(λ)" is the in-plane retardation measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane retardation measured with light of wavelength 550 nm at 23°C. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d, where d (nm) is the thickness of the layer (film). (4) Retardation in the thickness direction (Rth) "Rth(λ)" is the retardation in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the retardation in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) is calculated by the formula: Rth(λ) = (nx - nz) × d, where d (nm) is the thickness of the layer (film).

[0012] A. Overall structure of resin film FIG. 1 is a schematic cross-sectional view of a resin film according to one embodiment of the present invention. The resin film 1 in the illustrated example contains a resin material as a matrix and an antiblocking agent (hereinafter referred to as AB agent) dispersed in the resin material. The average primary particle diameter of the AB agent is 0.1 μm to 1.3 μm. The content (by mass) of the AB agent in the resin film 1 is 350 ppm to 3000 ppm. When the average primary particle size and content of the AB agent are within these ranges, it is possible to impart excellent anti-blocking properties to the resin film, and to realize a resin film that can fully exhibit in-plane birefringence by stretching.

[0013] The average primary particle size of the AB agent is preferably 0.1 μm to 1.0 μm, and more preferably 0.5 μm to 1.0 μm. The average primary particle size of the AB agent can be measured by laser diffraction. When the average primary particle size of the AB agent is within this range, excellent in-plane birefringence can be stably exhibited when the resin film is stretched.

[0014] The content (by mass) of the AB agent in the resin film 1 is preferably 500 ppm to 3000 ppm, more preferably 500 ppm to 2000 ppm, and even more preferably 500 ppm to 1500 ppm. When the content of the AB agent is within this range, sufficient antiblocking properties can be imparted to the resin film, and excellent in-plane birefringence can be more stably exhibited when the resin film is stretched.

[0015] The absolute value of the refractive index difference between the resin material and the AB agent is, for example, 0.10 or less, and preferably 0.08 or less. The lower limit of the absolute value of the refractive index difference between the resin material and the AB agent is typically 0. When the absolute value of the refractive index difference between the resin material and the AB additive is within this range, light diffusion caused by the AB additive can be suppressed in a retardation film that can be produced by stretching a resin film, and therefore the light transmittance can be improved and the haze can be reduced in the retardation film.

[0016] In one embodiment, the refractive index of the AB agent is equal to or lower than the refractive index of the resin material. When the refractive index of the AB agent is equal to or lower than the refractive index of the resin material and the refractive index difference between the resin material and the AB agent is within the above range, the light transmittance of the retardation film can be further improved and the haze can be further reduced.

[0017] The refractive index of the AB agent is, for example, 1.35 or more, preferably 1.40 or more. On the other hand, the refractive index of the AB agent is, for example, 1.65 or less, preferably 1.60 or less, more preferably 1.55 or less, and even more preferably 1.50 or less. The refractive index of the AB agent can be measured at 25°C using light with a wavelength of 590 nm, for example, in accordance with JIS K7142. The refractive index of the resin material is, for example, 1.40 or more, preferably 1.45 or more, and more preferably 1.48 or more. On the other hand, the refractive index of the resin material is, for example, 1.70 or less, preferably 1.65 or less, and more preferably 1.60 or less. The refractive index of the resin material can be measured at 25°C using light with a wavelength of 590 nm, for example, in accordance with JIS K7142.

[0018] The dynamic friction coefficient of the resin film 1 is, for example, 1.2 or less, and preferably 1.0 or less. On the other hand, the lower limit of the dynamic friction coefficient of the resin film 1 is typically 0.2. The dynamic friction coefficient of the resin film can be measured according to JIS K7125. If the dynamic friction coefficient of the resin film is within this range, excellent anti-blocking properties can be stably imparted to the resin film.

[0019] As described above, the resin film 1 has excellent anti-blocking properties. Therefore, the resin film 1 can be typically wound into a roll without a release liner. This can prevent dents from being formed on the resin film even when the resin film is wound into a roll.

[0020] The indentation elastic modulus of the resin film 1 at 25°C is, for example, 2.0 N / mm 2 ~6.5N / mm 2 or for example 2.5 N / mm 2 ~6.0N / mm 2 The indentation modulus of the resin film can be measured by a nanoindentation method. Even if the resin film has an indentation modulus within this range, the formation of dents in the resin film can be sufficiently suppressed by winding the resin film without a release liner.

[0021] B. Details of the resin film Before stretching, the resin film 1 is typically optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) and the thickness direction retardation Rth(550) are in the following ranges. The in-plane retardation Re(550) of the resin film 1 is, for example, 10 nm or less, preferably 5 nm or less, and more preferably 3 nm or less. On the other hand, the lower limit of the in-plane retardation Re(550) of the resin film 1 is typically 0 nm. The resin film 1 has a thickness direction retardation Rth(550) of, for example, −10 nm to +10 nm, and preferably −5 nm to +5 nm.

[0022] The thickness of the resin film 1 is, for example, 30 μm or more, preferably 40 μm or more. On the other hand, the thickness of the resin film 1 is, for example, 130 μm or less, preferably 120 μm or less. When the thickness of the resin film is within this range, a retardation film having a desired thickness can be stably produced by stretching the resin film.

[0023] B-1.Resin material The resin film 1 contains a resin material as a main component. Specific examples of the resin material include transparent resins such as cycloolefin (COP) resins such as polynorbornene; polyesters such as polyethylene terephthalate (PET); cellulose-based resins such as triacetyl cellulose (TAC); polycarbonate (PC) resins; (meth)acrylic resins; polyvinyl alcohol resins; polyamides; polyimides; polyethersulfones; polysulfones; polystyrenes; polyolefins; and acetate resins. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins. The term "(meth)acrylic resin" refers to an acrylic resin and / or a methacrylic resin. Other examples include glassy polymers such as siloxane polymers. Polymers described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials for this polymer include a resin composition containing a thermoplastic resin with substituted or unsubstituted imide groups in the side chain and a thermoplastic resin with substituted or unsubstituted phenyl and nitrile groups in the side chain, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer.The materials for the resin film can be used alone or in combination.

[0024] In one embodiment, the resin material of the resin film 1 is amorphous. When the resin film is made of an amorphous resin material, excellent transparency can be imparted to a retardation film produced from the resin film.

[0025] Of these resin materials, preferably, PC-based resins and COP-based resins are used, and more preferably, PC-based resins are used.

[0026] In one embodiment, the PC resin contains at least a structural unit derived from a dihydroxy compound having a bond structure represented by the following structural formula (1), and is produced by reacting a dihydroxy compound containing at least one dihydroxy compound having at least one bond structure -CH-O- in the molecule with a carbonate diester in the presence of a polymerization catalyst. In other words, the PC resin contains a structural unit derived from a dihydroxy compound and a carbonate group derived from a carbonate diester. [ka]

[0027] Here, the dihydroxy compound having the bond structure represented by structural formula (1) can be any compound having any structure, as long as it has two alcoholic hydroxyl groups, contains a structure having a linking group -CH-O- in the molecule, and is capable of reacting with a carbonate diester in the presence of a polymerization catalyst to produce a polycarbonate, and multiple types may be used in combination.

[0028] Furthermore, a dihydroxy compound not having the bond structure represented by the structural formula (1) may be used in combination with the dihydroxy compound used in the PC resin. Hereinafter, a dihydroxy compound having the bond structure represented by the structural formula (1) may be abbreviated as dihydroxy compound (A), and a dihydroxy compound not having the bond structure represented by the structural formula (1) may be abbreviated as dihydroxy compound (B).

[0029] (Dihydroxy compound (A)) The "linking group -CH2-O-" in the dihydroxy compound (A) means a structure in which atoms other than hydrogen atoms are bonded to form a molecule. In this linking group, the atom to which at least an oxygen atom can be bonded or the atom to which both a carbon atom and an oxygen atom can be bonded is preferably a carbon atom. The number of "linking groups -CH2-O-" in the dihydroxy compound (A) is preferably 1 or more, more preferably 2 to 4.

[0030] Specific examples of the dihydroxy compound (A) include 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isopropylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-isobutylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butylphenyl)fluorene, and 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene. a compound having an aromatic group in a side chain and an ether group bonded to the aromatic group in the main chain, such as 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3,5-dimethylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-tert-butyl-6-methylphenyl)fluorene, or 9,9-bis(4-(3-hydroxy-2,2-dimethylpropoxy)phenyl)fluorene;Bis[4-(2-hydroxyethoxy)phenyl]methane, bis[4-(2-hydroxyethoxy)phenyl]diphenylmethane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]ethane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]-1-phenylethane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxyethoxy)-3-methylphenyl]propane, 2,2-bis[3,5-dimethyl-4-(2-hydroxyethoxy)phenyl]propane 1,1-bis[4-(2-hydroxyethoxy)phenyl]propane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]-3,3,5-trimethylcyclohexane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,4-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,3-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 2,2-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]propane, 2,2-bis[(2-hydroxyethoxy)-3- isopropylphenyl]propane, 2,2-bis[3-tert-butyl-4-(2-hydroxyethoxy)phenyl]propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]butane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]-4-methylpentane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]octane, 1,1-bis[4-(2-hydroxyethoxy)phenyl]decane, 2,2-bis[3-bromo-4-(2-hydroxyethoxy)phenyl]propane bis(hydroxyalkoxyaryl)alkanes, such as 2,2-bis[3-cyclohexyl-4-(2-hydroxyethoxy)phenyl]propane; bis(hydroxyalkoxyaryl)cycloalkanes, such as 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane, 1,1-bis[3-cyclohexyl-4-(2-hydroxyethoxy)phenyl]cyclohexane, and 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclopentane;Dihydroxyalkoxy diaryl ethers, such as 4,4'-bis(2-hydroxyethoxy)diphenyl ether and 4,4'-bis(2-hydroxyethoxy)-3,3'-dimethyldiphenyl ether; bishydroxyalkoxy aryl sulfides, such as 4,4'-bis(2-hydroxyethoxyphenyl) sulfide and 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] sulfide; bishydroxyalkoxy aryl sulfoxides, such as 4,4'-bis(2-hydroxyethoxyphenyl) sulfoxide and 4,4'-bis[4-(2-dihydroxyethoxy)-3-methylphenyl] sulfoxide; 4,4'-bis(2-hydroxyethoxyphenyl) sulfone and 4,4'-bis[4-(2 Examples of suitable dihydroxy compounds include bishydroxyalkoxyarylsulfones, such as 1,4-bishydroxyethoxybenzene; bishydroxyalkoxybenzenes, such as 1,4-bishydroxyethoxybenzene; 1,3-bis[2-[4-(2-hydroxyethoxy)phenyl]propyl]benzene; 1,4-bis[2-[4-(2-hydroxyethoxy)phenyl]propyl]benzene; 4,4'-bis(2-hydroxyethoxy)biphenyl; 1,3-bis[4-(2-hydroxyethoxy)phenyl]-5,7-dimethyladamantane; anhydrosugar alcohols, such as the dihydroxy compound represented by the following formula (2); and compounds having a cyclic ether structure, such as the spiroglycol represented by the following general formula (3). The dihydroxy compounds (A) may be used alone or in combination.

[0031] [ka]

[0032] [ka]

[0033] Of these dihydroxy compounds (A), preferred is the dihydroxy compound represented by the above formula (2). Examples of the dihydroxy compound represented by the above formula (2) include isosorbide, isomannide, and isoidet, which are stereoisomers, and these may be used alone or in combination of two or more. Among the dihydroxy compounds (A), isosorbide, which is obtained by dehydration condensation of sorbitol produced from various starches that are abundant and easily available as resources, is most preferred in terms of availability, ease of production, optical properties, and moldability.

[0034] The proportion of the structural units derived from the dihydroxy compound (A) relative to the total structural units derived from the dihydroxy compounds contained in the PC resin is, for example, 10 mol% or more, preferably 40 mol% or more, and more preferably 60 mol% or more. On the other hand, the proportion of the structural units derived from the dihydroxy compound (A) is, for example, 100 mol% or less, preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less. When the proportion of the dihydroxy compound (A) is within the above range, the desired refractive index characteristics can be imparted to a retardation film that can be produced from the resin film.

[0035] (Dihydroxy compound (B)) As the dihydroxy compound that forms the structural unit of the PC resin, dihydroxy compound (A) and dihydroxy compound (B) can be used together. By using dihydroxy compounds (A) and (B) in combination, the desired refractive index characteristics can be stably imparted to a retardation film that can be produced from the resin film.

[0036] The dihydroxy compound (B) is typically a dihydroxy compound other than the dihydroxy compound (A). Examples of the dihydroxy compound (B) include alicyclic dihydroxy compounds, aliphatic dihydroxy compounds, oxyalkylene glycols, aromatic dihydroxy compounds, and diols having a cyclic ether structure. The dihydroxy compounds (B) may be used alone or in combination. Of the dihydroxy compounds (B), preferred are alicyclic dihydroxy compounds.

[0037] The alicyclic dihydroxy compound is not particularly limited, but preferably includes a compound having a five-membered ring structure or a six-membered ring structure. The six-membered ring structure may be fixed in a chair or boat shape by a covalent bond. The five-membered or six-membered ring structure of the alicyclic dihydroxy compound can improve the heat resistance of the resulting PC resin. The number of carbon atoms contained in the alicyclic dihydroxy compound is, for example, 70 or less, preferably 50 or less, and more preferably 30 or less.

[0038] Specific examples of the alicyclic dihydroxy compound containing a 5-membered ring structure or a 6-membered ring structure include alicyclic dihydroxy compounds represented by the following general formula (I) or (II). HOCH2-R 1 -CH2OH (I) HO-R 2 -OH (II) (In formulas (I) and (II), R 1 and R 2 Each of the represents a cycloalkylene group having 4 to 20 carbon atoms.

[0039] Cyclohexanedimethanol, which is an alicyclic dihydroxy compound represented by the general formula (I), is a compound represented by the general formula (I) in which R 1 is represented by the following general formula (Ia) (wherein R 3 represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom. Specific examples of such isomers include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol.

[0040] [ka]

[0041] The alicyclic dihydroxy compound represented by the general formula (I), tricyclodecane dimethanol or pentacyclopentadecanedimethanol, is a compound represented by the general formula (I), 1 The compound includes various isomers represented by the following general formula (Ib) (wherein n is 0 or 1).

[0042] [ka]

[0043] Decalin dimethanol or tricyclotetradecane dimethanol, which is an alicyclic dihydroxy compound represented by the above general formula (I), is a compound represented by the general formula (I) in which R 1 is represented by the following general formula (Ic) (wherein m is 0 or 1). Specific examples of such isomers include 2,6-decalindimethanol, 1,5-decalindimethanol, and 2,3-decalindimethanol.

[0044] [ka]

[0045] Norbornane dimethanol, which is an alicyclic dihydroxy compound represented by the above general formula (I), is a compound represented by the general formula (I) in which R 1 The isomers include various isomers represented by the following general formula (Id): Specific examples of such isomers include 2,3-norbornane dimethanol and 2,5-norbornane dimethanol.

[0046] [ka]

[0047] Adamantane dimethanol, which is an alicyclic dihydroxy compound represented by general formula (I), is 1The general formula (Ie) includes various isomers represented by the following general formula (Ie): Specific example of such isomer is 1,3-adamantanedimethanol.

[0048] [ka]

[0049] The cyclohexanediol, which is an alicyclic dihydroxy compound represented by the general formula (II), is a compound represented by the general formula (II) in which R 2 is represented by the following general formula (IIa) (wherein R 3 represents an alkyl group having 1 to 12 carbon atoms or a hydrogen atom. Specific examples of such isomers include 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 2-methyl-1,4-cyclohexanediol.

[0050] [ka]

[0051] The alicyclic dihydroxy compound represented by the general formula (II), tricyclodecanediol or pentacyclopentadecanediol, is a compound represented by the general formula (II), 2 includes various isomers represented by the following general formula (IIb) (wherein n is 0 or 1).

[0052] [ka]

[0053] Decalindiol or tricyclotetradecanediol, which is an alicyclic dihydroxy compound represented by the above general formula (II), is a compound represented by the general formula (II) in which R 2is represented by the following general formula (IIc) (wherein m represents 0 or 1). Specific examples of such isomers include 2,6-decalindiol, 1,5-decalindiol, and 2,3-decalindiol.

[0054] [ka]

[0055] Norbornanediol, which is an alicyclic dihydroxy compound represented by the above general formula (II), is 2 The isomers include various isomers represented by the following general formula (IId): Specific examples of such isomers include 2,3-norbornanediol and 2,5-norbornanediol.

[0056] [ka]

[0057] Adamantanediol, which is an alicyclic dihydroxy compound represented by the general formula (II), is a compound represented by the general formula (II) in which R 2 These include various isomers represented by the following general formula (IIe): Specific examples of such isomers include 1,3-adamantanediol.

[0058] [ka]

[0059] Among the specific examples of the alicyclic dihydroxy compound described above, preferred are cyclohexanedimethanols, tricyclodecane dimethanols, adamantanediols, and pentacyclopentadecanedimethanols. From the viewpoints of availability and ease of handling, more preferred are 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and tricyclodecane dimethanol, and even more preferred is tricyclodecane dimethanol.

[0060] The proportion of the structural units derived from the dihydroxy compound (B) relative to all structural units derived from dihydroxy compounds contained in the PC resin is, for example, 0 mol% or more, preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. On the other hand, the proportion of the structural units derived from the dihydroxy compound (B) is, for example, 90 mol% or less, preferably 60 mol% or less, and more preferably 40 mol% or less.

[0061] Details of these PC resins are described, for example, in JP 2012-31370 A (Patent No. 5448264), the disclosure of which is incorporated herein by reference.

[0062] In one embodiment, the PC resin contains a structural unit derived from the dihydroxy compound (A) represented by the above formula (2), a structural unit derived from the alicyclic dihydroxy compound (B) represented by the above general formula (I), and a carbonate group linking them. When a PC resin containing these structural units is applied to a resin film, excellent in-plane birefringence can be stably exhibited when the resin film is stretched. In such a PC resin, the molar ratio (A:B) of the structural units derived from the dihydroxy compound (A) represented by the above formula (2) to the structural units derived from the alicyclic dihydroxy compound (B) represented by the above general formula (I) is, for example, 5:5 to 9:1, and preferably 6:4 to 8:2. In such a PC resin, the combination of the dihydroxy compound (A) represented by the above formula (2) and the alicyclic dihydroxy compound (B) represented by the above general formula (I) is preferably a combination of isosorbide and tricyclodecane dimethanol.

[0063] B-2. Anti-blocking agent The resin film 1 contains an AB agent in addition to a resin material. The AB agent is typically in the form of particles, and is dispersed in the resin material as aggregates in which a plurality of particles of the AB agent aggregate together.

[0064] The AB agent is preferably transparent. Materials constituting the AB agent include, for example, metal oxides, resins, and glass. Examples of metal oxides include silica, alumina, titania, zirconia, and calcium oxide. Examples of resins include polymethyl methacrylate, polystyrene, polyurethane, (meth)acrylic resins, (meth)acrylic-styrene copolymers, benzoguanamine, melamine, polycarbonate, and silicone. Examples of glass include magnesium fluoride. The surface of the AB agent may be subjected to any suitable surface modification, such as chemical modification, preferably alkyl group modification. The AB agents may be used alone or in combination of two or more. Of these AB agents, metal oxides are preferred, silica is more preferred, alkyl group-modified silica is even more preferred, and methyl-modified silica is particularly preferred.

[0065] The resin film 1 may contain any appropriate additives in addition to the resin material and AB agent described above. Examples of additives include antioxidants, UV absorbers, light stabilizers, nucleating agents, fillers, pigments, surfactants, and antistatic agents. Any appropriate surface treatment layer may be provided on the surface of the resin film 1 (the surface opposite the pressure-sensitive adhesive layer 2). Examples of surface treatment layers include an easy-adhesion layer, an easy-slip layer, an antistatic layer, an antireflection layer, and an oligomer prevention layer.

[0066] C. Resin film manufacturing method The resin film 1 described above can be produced by any appropriate method. In one embodiment, the method for producing a resin film includes the steps of preparing a resin composition (preparation step), passing the resin composition through a filter (filtering step), and extruding the resin composition after passing through the filter (extrusion step).

[0067] In the preparation step, typically, the resin material is melted, and then the molten resin material is mixed with the AB agent to prepare a resin composition.

[0068] The resin material before melting may have any suitable shape. In one embodiment, the resin material is pelletized in advance. The method for pelletizing the resin material is not particularly limited, and may be a strand cut method or a hot cut method. Details of the pellet preparation process are described, for example, in JP 2013-181105 A. The disclosure of this patent document is incorporated herein by reference.

[0069] Next, the resin material (typically pellets) is heated and melted. Any appropriate heating temperature may be adopted depending on the resin material. The molten resin material and the AB agent are mixed together. This prepares a molten resin composition. The range of the content of the AB agent in the resin composition is, for example, the same as the range of the content of the AB agent in the resin film 1 described above.

[0070] In the filtering step, the molten resin composition is passed through a filter, which makes it possible to remove foreign matter and / or aggregates of the AB agent contained in the resin composition from the resin composition.

[0071] The filter may have any suitable configuration, and examples of the filter include a screen mesh and a disk filter, with a screen mesh being preferred. The opening of the screen mesh is, for example, 0.080 mm or less, preferably 0.070 mm or less, and more preferably 0.055 mm or less. When the screen mesh has such openings, it is possible to prevent excessively large foreign matter and / or aggregates of the AB agent from being mixed into the resin film to be formed. On the other hand, the opening of the screen mesh is, for example, 0.025 mm or more, preferably 0.035 mm or more. When the screen mesh has such openings, the resin composition can pass through the screen mesh smoothly. This can prevent the resin composition from stagnating and from being overheated. This can prevent the generation of gel-like matter due to thermal crosslinking of the resin material.

[0072] In the extrusion molding step, the molten resin after passing through the filter is extruded into a film shape, typically using a die, to prepare the resin film 1. The above-described preparation step, filter-passing step, and extrusion molding step can be performed using any appropriate film-forming device.

[0073] In addition to the preparation step and the film-forming step, the method for producing the resin film 1 may also include a step (winding step) in which a winding member winds up the resin film. In the winding step, the winding member winds up the resin film 1 into a roll. The winding member typically has a cylindrical shape and is rotatable about its axis. The resin film 1 has excellent anti-blocking properties, and therefore, even when the resin film 1 is wound into a roll, it is possible to sufficiently prevent the resin films 1 from sticking to each other. In this way, the resin film 1 is manufactured.

[0074] D. Retardation film The above-described resin film 1 can be applied to any appropriate application. The resin film 1 is excellent in exhibiting in-plane birefringence by stretching, and therefore can be suitably employed in the production of a retardation film. Specifically, by stretching the resin film, in-plane birefringence can be sufficiently exhibited, and a retardation film can be produced. The stretching conditions (e.g., stretching temperature, stretching ratio, stretching direction) and stretching method (e.g., longitudinal uniaxial stretching) can be arbitrarily and appropriately adjusted depending on the type of polymer and the desired optical properties (e.g., refractive index properties, in-plane retardation, thickness direction retardation).

[0075] Such a retardation film contains the above-mentioned resin material and the above-mentioned AB agent. The range of the content ratio of the AB agent in the retardation film is, for example, the same as the range of the content ratio of the AB agent in the resin film 1. Therefore, the retardation film has excellent anti-blocking properties, and therefore, the retardation film can be typically wound into a roll without a release liner.

[0076] Furthermore, the retardation film exhibits sufficient in-plane birefringence. In other words, the refractive indexes of the retardation film satisfy the relationship nx>ny. The in-plane birefringence Δn(550) of the retardation film is, for example, 0.0042 or more, preferably 0.0045 or more, more preferably 0.0048 or more. On the other hand, the upper limit of Δn(550) of the retardation film is typically 0.0050.

[0077] The retardation film may exhibit a reverse wavelength dispersion characteristic in which the in-plane birefringence increases according to the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the in-plane birefringence decreases according to the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the in-plane birefringence hardly changes depending on the wavelength of the measurement light. In one embodiment, the retardation film exhibits a flat wavelength dispersion characteristic.

[0078] The thickness of the retardation film can be arbitrarily and appropriately adjusted to obtain an in-plane retardation according to the application. The thickness of the retardation film is, for example, 1 μm or more, preferably 4 μm or more, and more preferably 10 μm or more. On the other hand, the thickness of the retardation film is, for example, 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less.

[0079] The total light transmittance of the retardation film is, for example, 80% or more, more preferably 85% or more, and even more preferably 90% or more. The upper limit of the total light transmittance of the retardation film is typically 100%. The total light transmittance of the retardation film can be measured in accordance with JIS R3106-2019. The haze value of the retardation film is, for example, 2.0% or less, preferably 1.5% or less, more preferably 1.0% or less, and even more preferably 0.8% or less. The lower limit of the haze value of the retardation film is typically 0%. The haze value of the resin film can be measured in accordance with JIS K7136.

[0080] The absolute value of the photoelastic coefficient of the retardation film is, for example, 20 × 10 -12 (m 2 / N) or less, preferably 1.0 × 10 -12 (m 2 / N)~15×10 -12 (m 2 / N), more preferably 2.0 × 10 -12 (m 2 / N)~12×10 -12 (m 2 When the absolute value of the photoelastic coefficient is within such a range, display unevenness can be suppressed when the retardation film is applied to an image display device. [Example]

[0081] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows.

[0082] (1) Slipperiness (anti-blocking properties) The resin films obtained in the examples and comparative examples were rubbed against each other to evaluate the slipperiness (anti-blocking property) according to the following criteria. The results are shown in Table 1. If the resin film has sufficient slip properties, blocking between the resin films can be sufficiently suppressed even when the resin film alone is wound into a roll. ◎: The base films slide well without sticking together 〇: The base films do not stick together, but they are slightly slippery compared to ◎ ×: The base films stick together and do not slide.

[0083] (2) In-plane birefringence Δn The resin films obtained in the examples and comparative examples were stretched laterally to 1.6 times at a stretching temperature of 135° C. and a stretching speed of 1% / sec, thereby preparing retardation films with a thickness of 25 μm. Next, the in-plane birefringence of the retardation film was automatically measured using Axoscan (manufactured by Axometrics). The measurement wavelength was 550 nm, and the measurement temperature was 23° C. The results are shown in Table 1.

[0084] <<Preparation Example 1: PC Resin Film>> 81.98 parts by mass of isosorbide (ISB), 47.19 parts by mass of tricyclodecane dimethanol (TCDDM), 175.1 parts by mass of diphenyl carbonate (DPC), and 0.979 parts by mass of a 0.2% by mass aqueous solution of cesium carbonate as a catalyst were charged into a reaction vessel. Under a nitrogen atmosphere, the heating vessel temperature was heated to 150°C as the first step of the reaction, and the raw materials were dissolved (approximately 15 minutes) with stirring as necessary. Next, the pressure was increased from atmospheric pressure to 13.3 kPa, and the heating vessel temperature was raised to 190°C over 1 hour, while the generated phenol was withdrawn from the reaction vessel. After the entire reaction vessel was held at 190°C for 15 minutes, the pressure inside the reaction vessel was increased to 6.67 kPa, and the heating vessel temperature was raised to 230°C over 15 minutes as the second step, and the generated phenol was withdrawn from the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and the pressure inside the reaction vessel was reduced to 0.200 kPa or less to remove the phenol that was generated. After the predetermined stirring torque was reached, the reaction was terminated and the reaction product was extruded into water to obtain pellets of PC resin.

[0085] [Example 1 and Comparative Example 1] The PC resin pellets obtained in Preparation Example 1 were vacuum dried at 100°C for 12 hours. Then, the PC resin pellets and an AB agent (methyl-modified silica fine particles, average primary particle diameter: 0.5 μm, refractive index: 1.43, manufactured by Nippon Shokubai Co., Ltd., product name: Seahoster KE) were supplied to a film-forming device. Table 1 shows the proportion of the AB agent added relative to the total amount of the pellets and the AB agent, and the average primary particle diameter of the AB agent. The film-forming device was equipped with a single-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a screen mesh with an opening of 0.045 mm, a T-die (width 1700 mm, set temperature: 250°C), a casting roll (set temperature: 60°C), and a winding member. More specifically, the pellets and the AB agent were supplied to a single-screw extruder and heated. This melted the pellets, and the molten PC resin and the AB agent were kneaded to prepare a resin composition. The resin composition was then extruded from the single-screw extruder and passed through a screen mesh and a T-die in that order. This produced a PC resin film with a thickness of 40 μm. The PC resin film passed through a cast roll and was then taken up by a take-up member. In this way, a PC resin film (resin film) was obtained.

[0086] [Example 2] A PC resin film (resin film) was obtained in the same manner as in Example 1, except that the AB agent (polymer particles, average primary particle size: 0.5 μm, refractive index: 1.5, manufactured by Sekisui Chemical Co., Ltd., product name: Techpolymer) was changed to an AB agent (average primary particle size: 1.0 μm, refractive index: 1.5, manufactured by Sekisui Chemical Co., Ltd., product name: Techpolymer), and the addition ratio of the AB agent to the total amount of pellets and AB agent was changed to 500 ppm.

[0087] Comparative Example 2 A PC resin film (resin film) was obtained in the same manner as in Example 1, except that no AB agent was used.

[0088] [Table 1]

[0089] [evaluation] As is clear from Table 1, when the average primary particle diameter of the AB agent in the resin film is 0.1 μm to 1.3 μm and the content of the AB agent is 350 ppm to 3000 ppm, the resin film can be imparted with excellent anti-blocking properties, and sufficient in-plane birefringence can be exhibited by stretching the resin film. [Industrial Applicability]

[0090] The resin film of the present invention can be applied to various industrial products, and can be particularly suitably used in the production of retardation films. [Explanation of symbols]

[0091] 1 Resin film

Claims

[Claim 1] a resin material as a matrix; an anti-blocking agent dispersed in the resin material; the average primary particle size of the antiblocking agent is 0.1 μm to 1.3 μm; A resin film, wherein the content of the antiblocking agent is 350 ppm to 3000 ppm.

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