JP2020007515A - Film - Google Patents

Abstract

To provide a film that has, by simple means, a very small phase difference.SOLUTION: The film is a film in which a phase separation portion is formed in matrix, having a positive form birefringence based on the phase separation structure, a negative orientation birefringence is introduced into matrix, and the form birefringence and the orientation birefringence are canceling each other.SELECTED DRAWING: None

Description

  The present invention relates to a film.

  2. Description of the Related Art In recent years, image display devices have been required to use optical materials having advanced optical characteristics in response to a demand for improvement in image clarity. As one of advanced optical characteristics, small birefringence is required. In general, a polymer compound used for an optical material has birefringence because the refractive index of the molecule in the main chain direction and the refractive index in the direction perpendicular to the main chain direction are different. As a technique for reducing birefringence, that is, a technique for reducing the phase difference, for example, Patent Document 1 discloses an acrylic copolymer having a lactone ring structure providing a positive phase difference and a structural unit providing a negative phase difference. Acrylic copolymers which are coalesced and have a retardation of 20 nm or less are disclosed. Patent Document 2 discloses a film formed from a resin composition in which a (meth) acrylic resin having a ring structure in the main chain is blended with a flexible resin having a low glass transition temperature. Patent Literature 3 discloses a resin composition including a core-shell rubber having a negative orientation birefringence in a lactone ring having a positive orientation birefringence.

JP 2007-63541 A JP 2007-100044 A JP 2007-254726 A

  Patent Document 1 merely describes phase difference control in a copolymer, and does not consider phase difference control when a rubber component is added for the purpose of imparting strength. In Patent Document 2, when imparting strength by biaxial stretching, there is a problem that anisotropy of strength occurs due to a stretching ratio or the like. Further, no consideration has been given to the phase difference of the flexible resin. In Patent Document 3, both the positive birefringence and the negative birefringence depend on the orientation, and it is difficult to individually control each of the values because the values are interlocked, and it is obtained from such a resin composition. Strict control from the component side is indispensable to reduce the retardation of the whole film, and it is complicated.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a film having a very small retardation by simple means.

  The present inventors have completed the present invention by forming a film having a phase separation structure and introducing a negative orientation birefringence into a matrix.

  That is, the present invention includes the following inventions.

  1. A film in which a phase separation portion is formed in a matrix, having a positive form birefringence based on the phase separation structure, a negative orientation birefringence is introduced into the matrix, and the form birefringence and the orientation birefringence are Films canceling each other.

  2. A film in which a phase-separated structure is formed in a matrix and the matrix contains a resin (R) having negative orientation birefringence. The film has an in-plane retardation Re with respect to light having a wavelength of 589 nm. A film having a thickness of 10 nm or less and a thickness direction retardation Rth of -10 to 10 nm with respect to light having a wavelength of 589 nm.

3. The above (2), wherein the stress optical coefficient Cr of the resin (R) is -30.0 × 10 ⁻⁹ Pa ⁻¹ or more and −0.1 × 10 ⁻⁹ Pa ⁻¹ or less. The film according to 1.

  4. 2. The resin according to the above item 2., wherein the resin (R) contains a (meth) acrylic polymer (Q). Or 3. The film according to 1.

  5. The film according to the above 1., wherein the film contains a polymer chain having a polymer block (a1) having a unit derived from a diene and / or an olefin. ~ 4. The film according to any one of the above.

  6. The film is a copolymer having a polymer chain (A) having a polymer block (a1) having a unit derived from a diene and / or olefin and a polymer block (a2) having a unit derived from an aromatic vinyl monomer. The above 1. ~ 4. The film according to any one of the above.

  7. 5. The above-mentioned 6. wherein the polymer chain (A) is contained in the film in an amount of 0.1 to 20% by mass. The film according to 1.

  8. The above-mentioned 1. having a glass transition temperature of 115 ° C. or more. ~ 7. The film according to any one of the above.

  9. (1) The internal haze is 1.0% or less. ~ 8. The film according to any one of the above.

  10. The above-mentioned 1., wherein the film is a biaxially stretched film having a thickness of 60 μm or less. ~ 9. The film according to any one of the above.

  Since the retardation of the film of the present invention is controlled by the phase separation structure, the retardation can be easily reduced.

3 is a scanning electron micrograph showing the sea-island structure of the film in Example 1.

  The present invention relates to a film in which negative orientation birefringence is introduced into a matrix (the matrix contains a resin (R) having negative orientation birefringence). A phase-separated structure is formed in the matrix of the film, and this phase-separated structure exhibits a positive form birefringence, so that the orientation birefringence and the form birefringence cancel each other, and the phase difference of the film is easily determined. Can be very small. Hereinafter, “the phase difference is extremely small”, “orientation birefringence”, “morphological birefringence”, and “phase separation structure” will be described.

  In the film of the present invention, the in-plane retardation Re for light having a wavelength of 589 nm is preferably 10 nm or less, and the retardation Rth in the thickness direction for light having a wavelength of 589 nm is preferably -10 to 10 nm. The phrase "the phase difference is very small" refers to a film that satisfies the above conditions. The in-plane retardation Re is more preferably 0 nm or more and 5.0 nm or less, the thickness direction retardation Rth is more preferably -5.0 nm or more and 10 nm or less, and the in-plane retardation Re is 0 nm or more and 2.0 nm or less and the thickness direction retardation. Rth is more preferably 0 nm or more and 7.0 nm or less. A film exhibiting such an in-plane retardation Re and a thickness direction retardation Rth has good viewing angle characteristics and contrast characteristics, and can be suitably applied to an image display device such as a liquid crystal display. Become. The in-plane retardation Re and the thickness direction retardation Rth are determined by the methods described in the examples.

Orientation birefringence is generally birefringence that occurs when the main chain of a chain polymer (polymer chain) is oriented. When the stress optical coefficient Cr of a given resin is negative, Is referred to as a resin having negative orientation birefringence. Preferably stress optical coefficient Cr of the resin (R) is -0.1 × 10 ^-9 Pa ^-1 or less -30.0 × 10 ^-9 Pa ^-1 or higher, -22.0 × 10 ^-9 Pa ^- It is more preferably not less than ^{1 and not} more than -1.0 × 10 ⁻⁹ Pa ⁻¹ , more preferably not less than −10 × 10 ⁻⁹ Pa ^{−1 and not} more than −2.0 × 10 ⁻⁹ Pa ^−1. preferable. By setting the stress optical coefficient Cr of the resin (R) to -30.0 × 10 ⁻⁹ Pa ⁻¹ or more, the positive form birefringence and the negative orientation birefringence can cancel each other. The phase difference can be made very small. The stress optical coefficient of the resin (R) is determined by the method described in Examples.

  The retardation of the film matrix itself is the retardation of a film prepared without phase separation (ie, no component involved in morphological birefringence), for example, a film prepared only from a resin having negative orientation birefringence. (Hereinafter, sometimes referred to as a matrix equivalent film), and the thickness direction retardation Rth of the matrix equivalent film is less than 0 nm. The in-plane retardation Re of the film equivalent to the matrix is preferably 10 nm or less, the thickness direction retardation Rth is preferably -30 nm or more and less than 0 nm, the in-plane retardation Re is 0 nm or more and 5.0 nm or less, and the thickness direction retardation is Rth is more preferably -20 nm or more and less than 0 nm, the in-plane retardation Re is more preferably 0 nm or more and 3.0 nm or less, and the thickness direction retardation Rth is more preferably -10.0 nm or more and less than 0 nm. It is particularly preferable that the phase difference Re is 0 nm or more and 1.0 nm or less, and the thickness direction phase difference Rth is -5.0 nm or more and less than 0 nm. By setting the thickness direction retardation Rth to be −30 nm or more and less than 0 nm, the negative orientation birefringence can be canceled by the positive form birefringence, and the retardation of the film can be easily reduced. The in-plane retardation Re and the thickness direction retardation Rth of the matrix equivalent film are determined by the methods described in Examples.

  Form birefringence is a birefringence of a material that has a structure much larger than a molecule and smaller in size than the wavelength of light, such as a periodic or collective structure. The form birefringence always takes a positive value. The degree of retardation corrected by the morphological birefringence in the film is greater than 0 nm in the thickness direction retardation Rth. The degree of the phase difference corrected by the form birefringence is preferably −5.0 nm or more and 0 nm or less in in-plane retardation Re of the film, and more than 0 nm and 30 nm or less in thickness direction retardation Rth. More preferably, the retardation Re is -2.0 nm or more and 0 nm or less, and the thickness direction retardation Rth is more than 0 nm and 15 nm or less, and the in-plane retardation Re is -0.5 nm or more and 0 nm or less, and the thickness direction retardation Rth is 0 nm. More preferably, it is larger than 10 nm. In addition, the value obtained by subtracting the in-plane retardation Re or the thickness direction retardation Rth of the matrix equivalent film from the in-plane retardation Re or the thickness direction retardation Rth of the film of the present invention is corrected by morphological birefringence, respectively. In-plane retardation Re or thickness-direction retardation Rth.

  As used herein, the term “phase-separated structure” refers to a state where two or more phases are formed when a film is observed with a scanning electron microscope (SEM). The phase separation structure is formed by using a resin (R) exhibiting negative orientation birefringence and a resin (S) having a portion incompatible with the resin (R), and forming a film from the resin mixture. Can be.

Examples of the phase separation structure include a sea-island structure, a continuous spherical structure, a composite dispersed phase structure, and a bicontinuous phase structure. The sea-island structure refers to a structure in which a small volume dispersed phase (island structure) is dispersed in a continuous phase (sea structure), and a particulate or spherical dispersed phase (island structure) is included in the continuous phase (sea structure). It is a scattered structure. The continuous spherical structure is a structure in which substantially spherical dispersed phases are connected and dispersed in the continuous phase. The composite dispersion structure is a structure in which a dispersed phase is dispersed in a continuous phase, and a resin constituting the continuous phase is dispersed in the dispersed phase. The bicontinuous structure is a structure in which a continuous phase and a dispersed phase form a complicated three-dimensional network.
Since the film of the present invention has a phase separation structure, orientation birefringence and form birefringence can be improved by a continuous phase containing a resin (R) having negative orientation birefringence and a dispersed phase having positive form birefringence. Cancel each other out, and the phase difference of the film can be reduced extremely easily.

  The film of the present invention preferably has a sea-island structure, and the island size in the structure is preferably 450 nm or less, more preferably 400 nm or less, further preferably 350 nm or less, and particularly preferably 300 nm or less. A film having a sea-island structure tends to have high transparency. The lower limit of the island size of the sea-island structure is not particularly limited, and may be, for example, 10 nm or more, 50 nm or more, or 100 nm or more. Observation of the sea-island structure of the film is performed by a scanning electron microscope (STEM), and the specific measurement method is referred to the method described in Examples.

1. Resin (S)
The resin (S) preferably contains a polymer chain having a polymer block (a1) having a unit derived from a diene and / or an olefin. When the film of the present invention has a sea-island structure, the island structure results from a polymer chain having a polymer block (a1). The resin (S) has a polymer block (a1) having a polymer block (a1) having a unit derived from a diene and / or olefin and a polymer chain (A) having a polymer block (a2) having a unit derived from an aromatic vinyl monomer. And a polymer chain (A) having a polymer block (a1) having a unit derived from a diene and / or an olefin and a polymer block (a2) having a unit derived from an aromatic vinyl monomer. And a polymer chain (B) having a unit derived from a (meth) acrylic monomer. The mechanical strength of the copolymer (P) is increased by including a polymer chain (A) having a polymer block (a1) functioning as a soft component and a polymer block (a2) functioning as a hard component, The resin composition containing such a copolymer (P) has high mechanical strength (for example, folding resistance (MIT strength)). Further, transparency and heat resistance are enhanced by including the polymer chain (B), and the resin composition including such a copolymer (P) has high transparency and high mechanical strength (for example, folding resistance). (MIT intensity)).

  The copolymer (P) preferably contains 2 to 30% by mass of the polymer chain (A), more preferably 3 to 20% by mass, and even more preferably 5 to 10% by mass. If the amount is less than 2% by mass, the effect of improving mechanical strength expected as a soft component may not be sufficient, which is not preferable. If the content is more than 30% by mass, aggregation of the dispersed phase is likely to occur, and the transparency may be reduced. The resin composition containing such a copolymer (P) can achieve both high transparency and high mechanical strength, and cancels out the negative orientation birefringence derived from the resin (R) in a film in which a phase separation structure is formed. A matching positive form birefringence can be exhibited.

Examples of the diene forming the diene-derived unit of the polymer block (a1) include 1,3-butadiene (alias: butadiene), 2-methyl-1,3-butadiene (alias: isoprene), 1,3-pentadiene, Alkadienes such as 1,4-pentadiene, 1,5-hexadiene, 2,5-dimethyl-1,5-hexadiene (also called diisobutene) are preferably used, and among them, 1,3-butadiene, 2-methyl-1, Conjugated dienes such as 3-butadiene and 1,3-pentadiene are more preferred.
Examples of the olefin forming the olefin-derived unit of the polymer block (a1) include ethylene, propylene, 1-butene, isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 1-tetradecene, and 1-tetradecene. Monoolefins such as octadecene (also referred to as alkenes) are preferably used, and among them, α-olefins which are alkenes having a carbon-carbon double bond at the α-position are more preferable. The carbon number of these dienes and olefins is preferably 2 or more, more preferably 3 or more, and preferably 20 or less, more preferably 10 or less, and even more preferably 6 or less.

  The units derived from diene and / or olefin are defined as units formed by polymerization of diene and / or olefin. The unit derived from an olefin is not limited to a unit actually formed by homopolymerization or copolymerization of an olefin as long as the same structure is formed, and may be formed by hydrogenating a unit derived from a diene. In the present specification, “homopolymerization or copolymerization” is referred to as “homopolymerization / copolymerization”, and “homopolymerization or copolymerization” is referred to as “(homopolymerization / copolymerization)”. May be written). In the polymer block (a1), as units derived from diene and / or olefin, units derived from butadiene, units derived from isoprene, units derived from ethylene, units derived from propylene, units derived from 1-butene, and units derived from isobutene. It is preferable that at least one selected from units is included.

  Examples of the polymer block (a1) include olefin (homo / co) polymers such as polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymer, and ethylene-butene copolymer; polyisoprene, polybutadiene, isoprene- Diene (homo / co) polymers such as butadiene copolymers; and olefin and diene copolymers such as ethylene-propylene-diene copolymers and isobutene-isoprene copolymers. As the olefin (homo / co) polymer, an α-olefin (homo / co) polymer is preferable, and as the diene (homo / co) polymer, a conjugated diene (homo / co) polymer is preferable. As the polymer, a copolymer of an α-olefin and a conjugated diene is preferable. Among these, a copolymer of an α-olefin and a conjugated diene such as polyisoprene and an isobutene-isoprene copolymer, and polyethylene and polypropylene are more preferable.

  The polymer block (a1) may have a unit derived from another unsaturated monomer in addition to a unit derived from a diene and / or an olefin. The other unsaturated monomer is not particularly limited as long as it has a polymerizable double bond, and examples thereof include vinyl esters such as vinyl acetate and vinyl propionate; (meth) acrylic acid, maleic anhydride, and (meth) ) Unsaturated carboxylic acids and esters thereof such as methyl acrylate and ethyl (meth) acrylate; vinyl silanes such as vinyl trimethoxysilane and γ- (meth) acryloyloxypropyl methoxy silane; and aromatic vinyl monomers. No.

  The aromatic vinyl monomer is not particularly limited as long as it is a compound in which a vinyl group is bonded to an aromatic ring, and examples thereof include styrene, vinyl toluene, methoxystyrene, α-methylstyrene, α-hydroxymethylstyrene, and α-hydroxyethyl. Styrene monomers such as styrene; polycyclic aromatic hydrocarbon ring monomers such as 2-vinylnaphthalene; aromatic heterocyclic vinyl monomers such as N-vinylcarbazole, 2-vinylpyridine, vinylimidazole and vinylthiophene And the like. Of these, styrene monomers are preferred. The styrene-based monomer includes not only styrene but also a styrene derivative in which an arbitrary substituent is bonded to a polymerizable double bond carbon or benzene ring of styrene, and the substituent includes an alkyl group, an alkoxy group, Examples include a hydroxy group, a halogen group, an amino group, a nitro group, and a sulfo group. The alkyl group and the alkoxy group bonded to styrene preferably have 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms. In the alkyl group and the alkoxy group bonded to styrene, at least a part of the hydrogen atom is a hydroxy group or a halogen. May be substituted with a group. From the viewpoint of reducing the coloring of the copolymer (P), the styrene monomer preferably has no amino group. Further, the styrene monomer is preferably unsubstituted styrene in which a substituent is not bonded to the polymerizable double bond carbon or benzene ring of styrene.

  The polymer block (a1) may be a copolymer of these other unsaturated monomers with diene and / or olefin. As the other unsaturated monomer, an aromatic vinyl monomer is preferable. When the copolymer of the aromatic vinyl monomer and the diene and / or olefin is used as the polymer block (a1), the transparency of the copolymer (P) is easily increased. For example, even when the refractive index difference between the polymer chain (A) and the polymer chain (B) of the copolymer (P) is large, it is easy to increase the transparency of the copolymer (P).

  When the polymer block (a1) has a unit derived from an aromatic vinyl monomer, the content ratio of the unit derived from the aromatic vinyl monomer may be 1% by mass or more in the polymer block (a1). It is preferably at least 2% by mass, more preferably at least 3% by mass, further preferably at most 40% by mass, more preferably at most 35% by mass, even more preferably at most 30% by mass. In this case, in the polymer block (a1), the total content of units derived from diene and / or olefin and units derived from aromatic vinyl monomer is preferably 70% by mass or more, and more preferably 80% by mass or more. Is more preferable, and 90 mass% or more is still more preferable. The polymer block (a1) may be substantially composed of only units derived from a diene and / or olefin and units derived from an aromatic vinyl monomer. For example, the total content of these units is 99% by mass. It may be the above.

  When the polymer block (a1) has a unit derived from another unsaturated monomer in addition to a unit derived from a diene and / or an olefin, the polymer block (a1) is composed of these monomers. Is preferred.

  The polymer block (a1) preferably contains a diene and / or olefin-derived unit as a main component, and the content ratio of the diene and / or olefin-derived unit is 50% in 100% by mass of the polymer block (a1). It is preferably at least 60 mass%, more preferably at least 60 mass%, even more preferably at least 70 mass%. The polymer block (a1) may be substantially composed of only units derived from diene and / or olefin. For example, the content of units derived from diene and / or olefin may be 99% by mass or more.

  The polymer chain (A) may have a polymer block (a2) having a unit derived from an aromatic vinyl monomer. Examples of the aromatic vinyl monomer forming the polymer block (a2) include the aromatic vinyl monomers exemplified in the above polymer block (a1).

  The polymer block (a2) may have a unit derived from another unsaturated monomer in addition to a unit derived from an aromatic vinyl monomer. The other unsaturated monomer is not particularly limited as long as it is a compound having a polymerizable double bond. For example, vinyl esters such as vinyl acetate and vinyl propionate; (meth) acrylic acid, maleic anhydride, and (meth) A) unsaturated carboxylic acids such as methyl acrylate and ethyl (meth) acrylate and esters thereof; vinyl silanes such as vinyl trimethoxy silane and γ- (meth) acryloyloxypropyl methoxy silane; The polymer block (a2) may be a copolymer (especially a random copolymer) of these other unsaturated monomers and an aromatic vinyl monomer. The content of the units derived from diene and / or olefin in the polymer block (a2) is preferably 1% by mass or less, and the polymer block (a2) has units derived from diene and / or olefin. Preferably not.

  The polymer block (a2) preferably contains a unit derived from an aromatic vinyl monomer as a main component. Specifically, in the polymer block (a2), the content ratio of the unit derived from the aromatic vinyl monomer is preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. preferable. The polymer block (a2) may be substantially composed of only units derived from an aromatic vinyl monomer. Is also good.

  Examples of the polymer chain (A) composed of the polymer block (a1) and the polymer block (a2) include a styrene-butadiene block copolymer, a styrene-butadiene-styrene block copolymer, and a styrene-butadiene-polymer. Hydrogenated styrene block copolymer (for example, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-butadiene / butylene-styrene block copolymer), styrene-isoprene block copolymer, styrene- Examples include an isoprene-styrene block copolymer and a hydrogenated product of a styrene-isoprene-styrene block copolymer (for example, a styrene-ethylene / propylene-styrene block copolymer (SEPS)). In these block copolymers, there may be mentioned those in which a butadiene block has become a butadiene / styrene block and those in which an isoprene block has become an isoprene / styrene block. In the above description, each block is divided by “-”, and the notation “/” in each block represents a monomer unit constituting the block.

  The polymer chain (A) is preferably one in which the polymer block (a2) is bonded to both sides of the polymer block (a1). Thereby, the polymer chain (A) functions as an elastomer, and the mechanical strength of the copolymer (P) can be further increased. In this case, the polymer chain (A) may be a triblock copolymer, a multiblock copolymer, or a radial block copolymer. A triblock copolymer is preferred because the properties can be easily controlled and the polymer chain (B) can be easily introduced into the copolymer (P). Examples of such a copolymer include a styrene-butadiene-styrene block copolymer and a hydrogenated product thereof, and a styrene-isoprene-styrene block copolymer and a hydrogenated product thereof.

  In the polymer chain (A), the content ratio of the polymer block (a2) may be 0% by mass (composed of only the polymer block (a1)), but is preferably 5% by mass or more, and preferably 10% by mass or more. More preferably, 15% by mass or more is further preferable, 55% by mass or less is preferable, 50% by mass or less is more preferable, 45% by mass or less is further preferable, 35% by mass or less is particularly preferable, and 25% by mass or less is most preferable . Thereby, the polymer chain (A) has a soft component and a hard component in a well-balanced manner, and it is easy to increase the mechanical strength of the copolymer (P). From the same viewpoint, the content of the polymer block (a1) in the polymer chain (A) is preferably 45% by mass or more, more preferably 50% by mass or more, still more preferably 55% by mass or more, and 65% by mass. % Or more is particularly preferable, 75% by mass or more is most preferable, and 95% by mass or less is preferable, 90% by mass or less is more preferable, and 85% by mass or less is further preferable. In the polymer chain (A), the content of the unit derived from the aromatic vinyl monomer may be 0% by mass, but is preferably 5% by mass or more, more preferably 10% by mass or more, and 15% by mass. % Or more, more preferably 55% by mass or less, more preferably 50% by mass or less, further preferably 45% by mass or less, particularly preferably 35% by mass or less, and most preferably 25% by mass or less.

  The weight average molecular weight of the polymer chain (A) is preferably not less than 0.1000, more preferably not less than 50000, still more preferably 10,000 or more, still more preferably 30,000 or more, and preferably 300,000 or less, It is more preferably at most 250,000, more preferably at most 200,000. By setting the weight average molecular weight of the polymer chain (A) in such a range, the mechanical strength of the copolymer (P) is ensured, and the moldability of the copolymer (P) is easily increased. .

  The copolymer (P) may have the polymer chain (B). The polymer chain (B) has at least a unit derived from a (meth) acrylic monomer (hereinafter sometimes referred to as “(meth) acrylic unit”). By having the polymer chain (B), the transparency of the copolymer (P) can be increased.

  In the present specification, the (meth) acrylic monomer is a monomer containing an acrylic group in which a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms) is bonded at the α-position and / or the β-position. In the alkyl group, at least a part of a hydrogen atom may be substituted with a hydroxy group or a halogen group. The (meth) acrylic monomer preferably means a monomer having an acryl group or a methacryl group. The (meth) acrylic monomer includes (meth) acrylic acid (that is, free acid) and a derivative thereof, and the derivative includes an ester, a salt, an acid amide, and the like.

  The (meth) acrylic monomer is preferably a (meth) acrylate. As the (meth) acrylic acid ester, a (meth) acrylic acid ester in which a linear, branched or cyclic aliphatic hydrocarbon group or aromatic hydrocarbon group is bonded to the oxygen atom of the ester bond of (meth) acrylic acid Is mentioned.

  Examples of the (meth) acrylate having a linear or branched aliphatic hydrocarbon group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acryl. Isopropyl acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, amyl (meth) acrylate , Isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, (meth) ) Dodecyl acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meth) Le acid heptadecyl, (meth) of octadecyl acrylate (meth) acrylic acid alkyl. The alkyl group of the alkyl (meth) acrylate is preferably a C1-18 alkyl group, more preferably a C1-12 alkyl group, and still more preferably a C1-6 alkyl group. In addition, in this specification, description of "C1-18" and "C1-12" means "C1-18" and "C1-12", respectively.

  Examples of the (meth) acrylate having a cyclic aliphatic hydrocarbon group include (meth) acrylates such as cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, and cyclohexyl (meth) acrylate. A) cycloalkyl acrylate; cross-linked cyclic (meth) acrylate such as isobornyl (meth) acrylate; The cycloalkyl group of the cycloalkyl (meth) acrylate is preferably a C3-20 cycloalkyl group, more preferably a C4-12 cycloalkyl group, and still more preferably a C5-10 cycloalkyl group.

  Examples of the (meth) acrylate having an aromatic hydrocarbon group include phenyl (meth) acrylate, tolyl (meth) acrylate, xylyl (meth) acrylate, naphthyl (meth) acrylate, and binaphthyl (meth) acrylate. Aryl (meth) acrylates such as anthryl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; aryloxyalkyl (meth) acrylates such as phenoxyethyl (meth) acrylate No. The aryl group of the aryl (meth) acrylate is preferably a C6-20 aryl group, and more preferably a C6-14 aryl group. The aralkyl group of the aralkyl (meth) acrylate is preferably a C6-10 aryl C1-4 alkyl group. The aryloxyalkyl group of the aryloxyalkyl (meth) acrylate is preferably a C6-10 aryloxy C1-4 alkyl group, more preferably a phenoxy C1-4 alkyl group.

  The (meth) acrylic acid ester may have a substituent such as a hydroxy group, an amino group, a halogen group, an alkoxy group, an epoxy group and the like. In particular, in a (meth) acrylate having a linear or branched aliphatic hydrocarbon group, the aliphatic hydrocarbon group preferably has a hydroxy group, an amino group, a halogen group, an alkoxy group, an epoxy group, or the like. Examples of such (meth) acrylates include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate; and chloromethyl (meth) acrylate and 2-chloroethyl (meth) acrylate. (Meth) acrylic acid alkyl halide; 2-methyethyl ethyl (meth) acrylate; alkoxyalkyl (meth) acrylate; and epoxyalkyl (meth) acrylate such as glycidyl (meth) acrylate. The alkyl group of hydroxyalkyl (meth) acrylate and epoxyalkyl (meth) acrylate is preferably a C1-12 alkyl group, more preferably a C1-6 alkyl group. The alkoxyalkyl group of the alkoxyalkyl (meth) acrylate is preferably a C1-12 alkoxy C1-12 alkyl group, more preferably the alkoxy group is C1-6, and the alkyl group is more preferably C1-6.

  The (meth) acrylic monomer also includes monomers exemplified by (meth) acrylic monomer A and (meth) acrylic monomer B having a protic hydrogen atom-containing group described below. .

  The polymer chain (B) preferably has a ring structure in the main chain. That is, the polymer chain (B) preferably has a unit having a ring structure in the main chain of the polymer chain (B) (hereinafter, may be referred to as a “ring structure unit”). When the polymer chain (B) has a ring structure in the main chain, the transparency and heat resistance of the resin composition containing the copolymer (P) can be improved. Further, improvements in solvent resistance, dimensional stability, surface hardness, adhesiveness, barrier properties against oxygen and water vapor, and various optical properties can be expected. Further, when a stretched film is obtained from the resin composition, it is possible to develop a phase difference derived from the ring structure of the polymer chain (B) depending on the stretching conditions.

  The ring structure of the main chain of the polymer chain (B) may include part or all of the (meth) acrylic monomer in the ring structure, and is introduced separately from the (meth) acrylic monomer. Or a ring structure. In this manner, the components necessary for forming a ring structure in the main chain of the polymer chain (also referred to as a monomer for forming a ring structure) include part or all of the (meth) acrylic monomer in the ring structure. In this case, for example, the two carboxylic acid groups of adjacent units derived from a (meth) acrylic monomer may be linked by acid anhydride, imidation or the like. When one of the adjacent units derived from the (meth) acrylic monomer has a protic hydrogen atom-containing group such as a hydroxy group or an amino group, the unit derived from the one (meth) acrylic monomer The ring structure can also be formed by condensing the protic hydrogen atom-containing group of the unit with the carboxylic acid group of the unit derived from the other (meth) acrylic monomer. When a ring structure is introduced separately from a unit derived from a (meth) acrylic monomer, for example, a (meth) acrylic monomer and a monomer having a polymerizable double bond in the ring structure may be used. What is necessary is just to copolymerize.

  The ring structure may be any of a four-membered ring structure, a five-membered ring structure, a six-membered ring structure, a seven-membered ring structure, and an eight-membered ring structure, and is preferably a five-membered ring structure or a six-membered ring structure.

  As the ring structure, from the viewpoint of heat resistance of the copolymer (P), a lactone ring structure, a lactam ring structure, a cyclic imide structure (for example, a succinimide structure, a glutarimide structure, etc.), a cyclic anhydride structure (for example, anhydrous succinimide) Acid structure, glutaric anhydride structure, etc.). One of these ring structures may be contained in the main chain of the polymer chain (B), or two or more thereof may be contained. Among these, at least one selected from a lactone ring structure, a succinimide structure, a succinic anhydride structure, a glutarimide structure, and a glutaric anhydride structure is preferable, and a lactone ring structure is more preferable.

  When the polymer chain (B) has a lactone ring structure or a lactam ring structure as a ring structure of the main chain, the number of ring members of the lactone ring structure or the lactam ring structure is not particularly limited, and for example, any one of a 4-membered ring to an 8-membered ring Should be fine. The lactone ring structure or the lactam ring structure is preferably a 5- or 6-membered ring, and more preferably a 6-membered ring, from the viewpoint of excellent stability of the ring structure.

Examples of the lactone ring structure include a structure disclosed in JP-A-2004-168882, and the introduction of the lactone ring structure is easy. For example, the polymerization yield of the (meth) acrylate is high, the lactone ring content in the cyclization condensation reaction of the precursor can be increased, and the polymer having a unit derived from (meth) acrylate can be used as the precursor. The structure represented by the formula (1a) is preferably shown. As the lactam ring structure, a structure represented by the following formula (1b) is preferable. In the following formula (1a) or the following formula (1b), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituent.

Examples of the substituent of R ¹ , R ² and R ^{3 in} the formulas (1a) and (1b) include an organic residue such as a hydrocarbon group, for example, C1-20 which may have a substituent. And the like. Examples of the hydrocarbon group include a saturated or unsaturated linear, branched, or cyclic aliphatic hydrocarbon group and an aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include a C1-20 alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group (preferably a C1-10 alkyl group, more preferably a C1-6 alkyl group). A C2-20 alkenyl group such as an ethenyl group or a propenyl group (preferably a C2-10 alkenyl group, more preferably a C2-6 alkenyl group); a C3-20 cycloalkyl such as a cyclopentyl group or a cyclohexyl group Groups (preferably a C4-12 cycloalkyl group, more preferably a C5-8 cycloalkyl group). Examples of the aromatic hydrocarbon group include a C6-20 aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group (preferably a C6-14 aryl group, more preferably a C6-10 aryl group). An aryl group); a C7-20 aralkyl group such as a benzyl group and a phenylethyl group (preferably a C7-15 aralkyl group, more preferably a C7-11 aralkyl group). These hydrocarbon groups may contain an oxygen atom or a halogen atom. Specifically, at least one of the hydrogen atoms of the hydrocarbon group is selected from a hydroxy group, a carboxy group, an ether group and an ester group. It may be substituted by at least one group.

In the lactone ring structure represented by the formula (1a) or the lactam ring structure represented by the formula (1b), R ¹ and R ² are selected from the viewpoint that it is easy to obtain a copolymer (P) having excellent heat resistance and a small birefringence. R ³ is preferably a hydrogen atom or a methyl group; R ¹ and R ² are each independently a hydrogen atom or a methyl group; R ³ is a hydrogen atom or a methyl group; More preferably, it is a hydrogen atom or a methyl group.

  The unit derived from the (meth) acrylic monomer A having a protic hydrogen atom-containing group such as a hydroxy group or an amino group and the unit derived from the (meth) acrylic monomer A A lactone ring structure and / or a lactam ring structure can be introduced into the polymer chain (B) by cyclocondensing an adjacent ester group of a unit derived from a (meth) acrylate ester. As a polymerization component, a (meth) acrylic monomer A having a protic hydrogen atom-containing group such as a hydroxy group or an amino group is essential, and the (meth) acrylic monomer B includes the monomer A. I do. Monomer B may or may not match monomer A. When the monomer B coincides with the monomer A, the monomer A is homopolymerized.

  Examples of the (meth) acrylic monomer A1 having a hydroxy group include 2- (hydroxymethyl) acrylic acid, 2- (hydroxyethyl) acrylic acid, and alkyl 2- (hydroxymethyl) acrylate (for example, 2- (hydroxy) Methyl) methyl acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, n-butyl 2- (hydroxymethyl) acrylate, t-butyl 2- (hydroxymethyl) acrylate And alkyl 2- (hydroxyethyl) acrylate (for example, methyl 2- (hydroxyethyl) acrylate, ethyl 2- (hydroxyethyl) acrylate) and the like, and preferably a monomer having a hydroxyallyl moiety. Certain 2- (hydroxymethyl) acrylic acid or 2- (hydroxymethyl) ), And alkyl acrylate. Particularly preferred are methyl 2- (hydroxymethyl) acrylate and ethyl 2- (hydroxymethyl) acrylate.

  Examples of the (meth) acrylic monomer A2 having an amino group include compounds in which the hydroxy group of the monomer A1 has been changed to an amino group. When the polymer chain (B) has a lactone ring structure and / or a lactam ring structure, the (meth) acrylic monomer A becomes a monomer for forming a ring structure.

  As the (meth) acrylic monomer B, a monomer having a vinyl group and an ester group or a carboxy group is preferable. For example, (meth) acrylic acid, alkyl (meth) acrylate (for example, (meth) acrylic) Methyl acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, etc., aryl (meth) acrylate (Eg, phenyl (meth) acrylate, benzyl (meth) acrylate), alkyl 2- (hydroxyalkyl) acrylate (eg, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate Alkyl 2- (hydroxymethyl) acrylate, methyl 2- (hydroxyethyl) acrylate Of 2- (hydroxyethyl) alkyl acrylate) and the like.

  The polymer chain (B) may have only one kind of the lactone ring structure or the lactam structure represented by the formula (1a) or (1b), or may have two or more kinds.

When the polymer chain (B) has a succinic anhydride structure (that is, a structure derived from a maleic anhydride monomer) or a succinimide structure (that is, a structure derived from a maleimide monomer) as a ring structure of the main chain, succinic anhydride is used. As the structure or succinimide structure, a structure represented by the following formula (2) is preferable. In the following formula (2), R ⁴ and R ⁵ each independently represent a hydrogen atom or a methyl group, R ⁶ represents a hydrogen atom or a substituent, X ¹ represents an oxygen atom or a nitrogen atom, and X ¹ There are n1 = 0 when the oxygen atom is n1 = 1 when X ¹ is a nitrogen atom.

Examples of the substituent of R ^{6 in} the formula (2) include an organic residue such as a hydrocarbon group, and include, for example, a C1-20 hydrocarbon group which may have a substituent. Examples of the hydrocarbon group include a saturated or unsaturated linear, branched, or cyclic aliphatic hydrocarbon group and an aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include a C1-20 alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group (preferably a C1-10 alkyl group, more preferably a C1-6 alkyl group). A C2-20 alkenyl group such as an ethenyl group or a propenyl group (preferably a C2-10 alkenyl group, more preferably a C2-6 alkenyl group); a C3-20 cycloalkyl such as a cyclopentyl group or a cyclohexyl group Groups (preferably a C4-12 cycloalkyl group, more preferably a C5-8 cycloalkyl group). Examples of the aromatic hydrocarbon group include a C6-20 aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group (preferably a C6-14 aryl group, more preferably a C6-10 aryl group). An aryl group); a C7-20 aralkyl group such as a benzyl group and a phenylethyl group (preferably a C7-15 aralkyl group, more preferably a C7-11 aralkyl group). These hydrocarbon groups may have a substituent such as halogen.

When X ¹ is an oxygen atom, the ring structure represented by the formula (2) is a succinic anhydride structure. The succinic anhydride structure can be introduced into the polymer chain (B) by, for example, copolymerizing maleic anhydride and a (meth) acrylic monomer (for example, (meth) acrylate). . When the polymer chain (B) has a succinic anhydride structure, maleic anhydride becomes a monomer for forming a ring structure.

When X ¹ is a nitrogen atom, the ring structure represented by the formula (2) is a succinimide structure. The succinimide structure can be introduced into the polymer chain (B), for example, by copolymerizing an N-substituted maleimide and a (meth) acrylic monomer (for example, (meth) acrylate). Examples of the succinimide structure include an unsubstituted succinimide structure at the N-position, an N-methylsuccinimide structure, an N-ethylsuccinimide structure, an N-cyclohexylsuccinimide structure, an N-phenylsuccinimide structure, an N-naphthylsuccinimide structure, and an N-benzylsuccinimide structure. And the like. Further, as the maleimide that gives a succinimide structure, maleimide in which the N-position is unsubstituted, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-naphthylmaleimide, N-benzylmaleimide, or the like is used. be able to. When the polymer chain (B) has a succinimide structure, the N-substituted maleimide is a monomer for forming a ring structure.

When the polymer chain (B) has a succinimide structure in which X ¹ is a nitrogen atom, R ⁴ and R ⁵ are excellent in heat resistance and easy to obtain a copolymer (P) having a small birefringence. R ⁶ is preferably a C 3-20 cycloalkyl group or a C 6-20 aromatic group (aryl group, aralkyl group, etc.), R ⁴ and R ⁵ are hydrogen atoms, and R ⁶ is cyclohexyl More preferably, it is a group or a phenyl group.

  The polymer chain (B) may have only one kind of the ring structure represented by the formula (2), or may have two or more kinds.

When the polymer chain (B) has a glutarimide structure or a glutaric anhydride structure as a ring structure of the main chain, a structure represented by the following formula (3) is preferably represented as the glutarimide structure or the glutaric anhydride structure. In Formula (3), R ⁷ and R ⁸ each independently represent a hydrogen atom or an alkyl group, R ⁹ represents a hydrogen atom or a substituent, X ² represents an oxygen atom or a nitrogen atom, X ² There are n2 = 0 when the oxygen atom, a n2 = 1 when X ² is a nitrogen atom.

In the formula (3), as the alkyl group of R ⁷ and R ^8, a linear or branched alkyl group is preferably exemplified, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an n-butyl group. Group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, n-hexyl group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, 2-ethylhexyl group, etc. And an alkyl group. R ⁷ and R ⁸ are each independently preferably a hydrogen atom or a C1-4 alkyl group from the viewpoint that it is easy to obtain a copolymer (P) having excellent heat resistance and a small birefringence. An atom or a methyl group is more preferred.

Examples of the substituent of R ^{9 in} the formula (3) include an organic residue such as a hydrocarbon group, for example, a C1-20 hydrocarbon group which may have a substituent. Examples of the hydrocarbon group include a saturated or unsaturated linear, branched, or cyclic aliphatic hydrocarbon group and an aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include a C1-20 alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group (preferably a C1-10 alkyl group, more preferably a C1-6 alkyl group). A C2-20 alkenyl group such as an ethenyl group or a propenyl group (preferably a C2-10 alkenyl group, more preferably a C2-6 alkenyl group); a C3-20 cycloalkyl such as a cyclopentyl group or a cyclohexyl group Groups (preferably a C4-12 cycloalkyl group, more preferably a C5-8 cycloalkyl group). Examples of the aromatic hydrocarbon group include a C6-20 aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group (preferably a C6-14 aryl group, more preferably a C6-10 aryl group). An aryl group); a C7-20 aralkyl group such as a benzyl group and a phenylethyl group (preferably a C7-15 aralkyl group, more preferably a C7-11 aralkyl group). These hydrocarbon groups may have a substituent such as halogen. Among them, R ⁹ is preferably an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, from the viewpoint of obtaining a copolymer (P) having excellent heat resistance and a small birefringence. Preferably, a methyl group, a cyclohexyl group, a phenyl group, or a tolyl group is more preferable.

When X ² is an oxygen atom, the ring structure represented by the formula (3) is a glutaric anhydride structure. The glutaric anhydride structure can be introduced into the polymer chain (B) by, for example, converting two carboxylic acid groups of adjacent (meth) acrylic monomer-derived units into acid anhydrides.

When X ² is a nitrogen atom, the ring structure represented by the formula (3) is a glutarimide structure. The glutarimide structure is formed, for example, by imidating two carboxylic acid groups of an adjacent (meth) acrylic monomer-derived unit, or by bonding an amide group of an adjacent (meth) acrylic amide-derived unit to (meth) Cyclocondensation with an ester group of a unit derived from an acrylate ester allows introduction into the polymer chain (B). When the polymer chain (B) has a glutarimide structure, the (meth) acrylic monomer is a monomer for forming a ring structure.

In the case where the ring structure of the formula (3) has a glutarimide structure in which X ² is a nitrogen atom, R ⁷ has excellent heat resistance and is easy to obtain a copolymer (P) having a small birefringence. And R ⁸ are each independently a hydrogen atom or a methyl group, R ⁹ is more preferably a methyl group, a cyclohexyl group, a phenyl group, or a tolyl group, and R ⁷ and R ⁸ are each independently a hydrogen atom. Particularly preferably, it is an atom or a methyl group, and R ⁹ is a cyclohexyl group or a phenyl group.

  The polymer chain (B) may have only one kind of the ring structure represented by the formula (3), or may have two or more kinds.

  Among the above-described ring structures, the polymer chain (B) is preferred from the viewpoint of imparting good surface hardness, solvent resistance, adhesiveness, barrier properties, and optical properties to the resin composition containing the copolymer (P). Preferably contains a lactone ring structure and / or a succinimide structure (a structure derived from a maleimide monomer), and more preferably a lactone ring structure.

  The content of the ring structural unit in the main chain in the polymer chain (B) is not particularly limited, but the content of the ring structural unit in the polymer chain (B) is preferably 3% by mass or more, more preferably 4% by mass or more. 5% by mass or more is further preferable, 50% by mass or less is preferable, 45% by mass or less is more preferable, and 40% by mass or less is further preferable. By adjusting the content of the cyclic structural unit in the main chain in this way, both the heat resistance and the mechanical strength can be imparted to the resin composition containing the copolymer (P) in a well-balanced manner. When high heat resistance or mechanical strength is imparted to the resin composition, the content of the structural unit in the polymer chain (B) is preferably 10% by mass or more, and more preferably 15% by mass or more. It is more preferably at least 20% by mass. The content ratio of the ring structural unit described herein means the content ratio of a unit having a ring structure contained in the main chain of the polymer chain (B), and is represented by, for example, the above formulas (1) to (3). Means the content of the structure.

  The polymer chain (B) may further have a unit derived from a vinyl monomer copolymerizable with the (meth) acrylic monomer. The vinyl monomer copolymerizable with the (meth) acrylic monomer is not particularly limited as long as it is a compound having a polymerizable double bond. For example, vinyl esters such as vinyl acetate and vinyl propionate; styrene, Aromatic vinyl compounds such as vinyltoluene, methoxystyrene, α-methylstyrene and 2-vinylpyridine; vinylsilanes such as vinyltrimethoxysilane and γ- (meth) acryloyloxypropylmethoxysilane; For example, when the polymer chain (B) has a unit derived from an aromatic vinyl monomer, it becomes easy to adjust the refractive index and retardation characteristics of the copolymer (P). For details of the aromatic vinyl monomer, refer to the description of the aromatic vinyl monomer in the polymer chain (A). When the polymer chain (B) is formed from two or more types of monomer components, the polymer chain (B) is preferably a random copolymer.

  The unit derived from a vinyl monomer copolymerizable with the (meth) acrylic monomer is, for example, 0.1 part by mass or more, preferably 0.5 part by mass or more in 100 parts by mass of the polymer chain (B). And more preferably 1 part by mass or more, for example, 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 10 parts by mass or less.

  The copolymer (P) is preferably a graft copolymer in which the polymer chain (B) is grafted on the polymer chain (A). According to the glossary of basic terms of polymer science by the International Union of Pure and Applied Chemistry (IUPAC) Polymer Nomenclature Committee, a graft polymer is "a polymer that has been bonded to the main chain as a side chain in a certain polymer. If there is one or several types of blocks, and these side chains have different structural (chemical structure) or arrangement characteristics from the main chain, this polymer is called a graft polymer. " I have. The graft copolymer can be obtained by a known production method such as a chain transfer reaction method, a polymer initiator method, a coupling method, a macromonomer method, and a surface graft method, and only one of these methods is used. Or a plurality of them may be used in combination. Details of these methods can be referred to the Chemical Society of Japan, Chemical Handbook (Applied Chemistry), 6th edition.

  In the copolymer (P), the polymer chain (B) is more preferably grafted on the polymer block (a1) of the polymer chain (A), and the polymer chain (B) is preferably a polymer block (a1). Most preferably, it is bonded to a unit derived from a diene and / or an olefin. In this most preferred case, the polymer chain (B) may be bonded to a carbon atom of the main chain of the unit derived from diene and / or olefin, and may be a hydrocarbon group bonded as a substituent (side chain) to the main chain. May be bonded to a carbon atom of The polymer chain (B) may be bonded to, for example, a diene-derived double bond of the main chain of the copolymer block (a1), or may be bonded to an adjacent carbon atom of the double bond. Alternatively, the polymer chain (B) bonds to a diene-derived double bond bonded as a substituent (side chain) to the main chain of the copolymer block (a1), or bonds to a carbon atom adjacent to the double bond. It may be.

2. Method for producing resin (S) (method for producing copolymer (P))
As described above, the resin (S) preferably contains the copolymer (P), and the copolymer (P) comprises a polymer block (a1) having a unit derived from a diene and / or an olefin and an aromatic vinyl. In the presence of a copolymer (P1) having a polymer block (a2) having a unit derived from a monomer (hereinafter sometimes referred to as “raw material copolymer (P1)”), a (meth) acrylic monomer It can be produced by polymerizing a monomer component containing a monomer (hereinafter, sometimes referred to as “raw material (meth) acrylic monomer”). The raw material copolymer (P1) corresponds to the polymer chain (A), and the polymer of the raw material (meth) acrylic monomer forms the polymer chain (B). Hereinafter, a method for producing a copolymer (P) containing all of the polymer block (a1), the polymer block (a2), and the polymer chain (B) will be described. In addition, when the resin (S) is a (co) polymer that does not contain the polymer block (a2) and / or the polymer chain (B), it can be produced with reference to the production method described below.

2.1 Production Raw Materials and Reagents The method for producing the raw material copolymer (P1) is not particularly limited. For example, the monomer components constituting the polymer block (a1) are polymerized to form the polymer block (a1). After that, it can be obtained by polymerizing the monomer components constituting the polymer block (a2) in the presence of the polymer block (a1). The raw material copolymer (P1) may be hydrogenated. Further, one kind or two or more kinds may be combined. When two or more kinds are combined, it becomes easy to adjust the average molecular weight and the double bond amount of the resin composition.

  The amount of the olefinic double bond in the raw material copolymer (P1) is preferably from 0.2 mmol / g to 2.0 mmol / g. By using the raw material copolymer (P1) having an olefinic double bond amount of 0.2 mmol / g or more, it becomes easy to obtain a highly transparent copolymer (P). On the other hand, by using the raw material copolymer (P1) having an olefinic double bond amount of 2.0 mmol / g or less, it becomes easy to obtain a copolymer (P) with less generation of a gelled product. The amount of the olefinic double bond in the raw material copolymer (P1) is more preferably 0.4 mmol / g or more, further preferably 0.6 mmol / g or more, and more preferably 1.5 mmol / g or less. It is more preferably at most 2 mmol / g, particularly preferably at most 1.0 mmol / g. The raw material copolymer (P1) may contain a plurality of resins having different amounts of olefinic double bonds, and even if the amount of olefinic double bonds of some resins exceeds 2.0 mmol / g. It is preferable that the amount of the olefinic double bond in the entire raw material copolymer (P1) be 2.0 mmol / g or less. The amount of the olefinic double bond in the raw material copolymer (P1) can be determined by an iodine titration method.

  As the raw material (meth) acrylic monomer, the (meth) acrylic monomer described for the polymer chain (B) can be appropriately used. Further, a vinyl monomer copolymerizable with the (meth) acrylic monomer may be present together with the raw material (meth) acrylic monomer, and these may be copolymerized. Further, components necessary for forming a ring structure in the main chain of the polymer chain (B) (monomers for forming a ring structure), for example, a protic hydrogen atom-containing group for forming a lactone ring structure or a lactam ring structure (Meth) acrylic monomer A and (meth) acrylic monomer B having a polymerizable double bond in the ring structure (maleic anhydride for forming a succinic anhydride structure; A maleimide for forming a succinimide structure), and (meth) acrylic acid for forming a glutaric anhydride structure or a glutarimide structure as the raw material (meth) acrylic monomer, or It can also be used as a copolymerization component of a raw material (meth) acrylic monomer.

  The amount of the raw material copolymer (P1) used in the polymerization is determined by the amount of the raw material copolymer (P1) and the monomer component (raw material (meth) acrylic monomer, raw material (meth) acrylic monomer and 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, with respect to 100 parts by mass in total of a polymerizable vinyl monomer and a monomer for forming a ring structure. It is still more preferably at least 9 parts by mass, particularly preferably at least 9 parts by mass, more preferably at most 50 parts by mass, even more preferably at most 40 parts by mass, even more preferably at most 30 parts by mass, particularly preferably at most 20 parts by mass. The amount of the monomer component to be used is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and preferably 70 parts by mass or more, based on 100 parts by mass of the raw material copolymer (P1) and the monomer component in total. It is still more preferably 80 parts by mass or more, particularly preferably 99 parts by mass or less, more preferably 97 parts by mass or less, still more preferably 95 parts by mass or less, and even more preferably 93 parts by mass or less.

  Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) .dihydrochloride, and dimethyl-2,2′-azobis (2- Azo compounds such as methylpropionate) and 4,4′-azobis (4-cyanopentanoic acid); persulfates such as potassium persulfate; cumene hydroperoxide, diisopropylbenzene hydroperoxide, di-t-butylperoxide Oxide, lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate (TBIC), t-amyl peroxy-2-ethylhexanoate, t-amyl peroxy octoate, t-amyl peroxy isononanoate (TAIN), t-amyl peroxyisopropyl carbonate DOO, can be used organic peroxides such as t- amyl peroxy 2-ethylhexyl carbonate. These may be used alone or in combination of two or more. Of these, organic peroxides are preferred. The organic peroxide is particularly useful when the raw material copolymer (P1) is a hydrogenated product. According to the organic peroxide, a radical having a high activity such as a vinyl position or an allyl position of a double bond (olefinic double bond) of a unit derived from an olefin can be extracted to generate a radical at the site, and a polymer chain (B This is useful for the addition polymerization of the monomer component forming the compound (1). The amount of the radical polymerization initiator used is preferably, for example, 0.01 to 1 part by mass with respect to 100 parts by mass of the monomer component.

  The polymerization can be carried out using a known polymerization method such as a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method, but it is preferable to use a solution polymerization method. When the solution polymerization method is used, the entry of minute foreign matter into the copolymer (P) can be suppressed, and the copolymer (P) can be easily suitably applied to optical material applications and the like.

  The solvent used for the solution polymerization can be appropriately selected according to the composition of the monomer component, and an organic solvent used in a usual radical polymerization reaction can be used. Specifically, aromatic hydrocarbons such as toluene, xylene and ethylbenzene; aliphatic hydrocarbons such as hexane and cyclohexane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; tetrahydrofuran, dioxane, ethylene glycol dimethyl ether , Diethylene glycol dimethyl ether, ethers such as anisole; ethyl acetate, butyl acetate, esters such as propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve; methanol, ethanol, isopropanol, alcohols such as n-butanol; nitriles such as acetonitrile, propionitrile, butyronitrile, and benzonitrile S; chloroform; dimethyl sulfoxide and the like. These solvents may be used alone or in combination of two or more.

2.2 Addition procedure As a method for producing the resin composition used in the present invention, a radical polymerization reaction is carried out by allowing the raw material copolymer (P1), the raw material (meth) acrylic monomer and a radical polymerization initiator to coexist. And a step of adding a radical polymerization initiator to the reaction solution after the initiation of the radical polymerization reaction. By adding a radical polymerization initiator after the initiation of the radical polymerization reaction, the composition distribution of the polymer chain (B) can be reduced, and the reaction rate between the raw material copolymer (P1) and the (meth) acrylic monomer can be reduced. And the aggregation phenomenon of the obtained copolymer (P) can be reduced, and a decrease in transparency of the resin composition containing the copolymer (P) under heating conditions can be prevented. Hereinafter, a mixture of the raw material copolymer (P1), the raw material (meth) acrylic monomer, and the radical polymerization initiator until the radical polymerization reaction starts is referred to as an “initial mixture”, and the mixture after the radical polymerization reaction has started. The reaction mixture (reaction liquid) may be referred to as “reaction continuation liquid”.

  The preparation procedure of the initial mixture is not particularly limited, and a raw material (meth) acrylic monomer and a radical polymerization initiator may be added to the raw material copolymer (P1). A radical polymerization initiator may be added to the mixture with the (meth) acrylic monomer. The temperature control until the start of radical polymerization can also be set as appropriate. For example, after heating a mixture of the raw material copolymer (P1) and the raw material (meth) acrylic monomer to a temperature at which polymerization can be started, A radical polymerization reaction may be started by adding a radical polymerization initiator to the mixture.

  The addition of the radical polymerization initiator to the reaction liquid (reaction continuation liquid) after the start of the radical polymerization reaction may be continuously performed without interruption from the addition of the radical polymerization initiator for preparing the initial mixture. However, it is preferable that after the addition of the radical polymerization initiator for the preparation of the initial mixture, the addition is temporarily stopped and the addition of the radical polymerization initiator is restarted after the radical polymerization reaction starts. By temporarily stopping the addition, re-addition after the start of the radical polymerization reaction is confirmed, the radical reaction can be safely performed. The start of the radical polymerization reaction can be confirmed by component confirmation by sampling or the like, change in liquid property or liquid temperature, or the like.

  Addition of the radical polymerization initiator to the reaction continuation liquid may be either divisional addition or dropping (including continuous dropping). The number of additions at the time of divided addition is not particularly limited as long as it is at least two times, and each addition may be performed dropwise. To improve the conversion of the monomer component, a radical polymerization initiator is preferably added dropwise, more preferably continuously. The dropping rate is, for example, about 0.1 to 1.0 part by mass / min, preferably 0.1 to 0.8 part by mass, when the total amount of the radical polymerization initiator used until the end of the reaction is 100 parts by mass. Parts / minute. The end of the reaction can be confirmed by measuring the conversion, and it is determined that the conversion of all the monomers is 85% or more.

  The amount of the radical polymerization initiator added to the reaction continuation liquid is, for example, 30 to 500 parts by mass, preferably 100 to 450 parts by mass, based on 100 parts by mass of the radical polymerization initiator added to the initial mixture. And more preferably 150 to 350 parts by mass.

  The raw material copolymer (P1) may be added to the reaction continuation liquid (divided addition, dropping, etc.), but it is preferable not to add it. When not added, the reaction rate between the raw material copolymer (P1) and the (meth) acrylic monomer can be increased. The amount of the raw material copolymer (P1) added to the reaction continuation liquid is, for example, 0 to 100 parts by mass with respect to 100 parts by mass of the raw material copolymer (P1) added to the initial mixture. Is from 0 to 50 parts by mass, more preferably 0 parts by mass.

  The raw material (meth) acrylic monomer may be added to the reaction continuation liquid (divided addition, dropping, etc.), or may not be added. The presence or absence of addition to the reaction continuation liquid can be determined by comparing the reactivity with the copolymer component. In the case where the copolymerization component is an aromatic vinyl monomer, it is better to reduce the amount of the reaction continuation liquid of the raw material (meth) acrylic monomer (not particularly adding) to the raw material (meth) acrylic monomer. Conversion rate can be increased. Further, the composition distribution of the polymer chains (B) when copolymerizing the aromatic vinyl monomer can be reduced, the dispersion stability of the copolymer (P) can be increased, and the transparency under heating conditions can be reduced. More can be prevented. When the copolymerization component is an aromatic vinyl monomer, the amount of the raw material (meth) acrylic monomer to be added to the reaction continuation liquid is 100 times the amount of the raw material (meth) acrylic monomer added to the initial mixture. The amount is, for example, 0 to 50 parts by mass, preferably 0 to 30 parts by mass, and more preferably 0 to 10 parts by mass with respect to parts by mass.

  In this polymerization reaction, the (meth) acrylic monomer A and the (meth) acrylic monomer B having a protic hydrogen atom-containing group and the monomer having a polymerizable double bond in the ring structure ( It is also possible to polymerize a monomer for forming a ring structure such as maleic anhydride or maleimide) or (meth) acrylic acid. These monomers for forming a ring structure may be added to the initial mixture or may be added to the reaction continuation liquid (divided addition, dropping, etc.). The ratio of the amount added to the initial mixture to the amount added to the reaction continuation liquid can be determined by comparing the reactivity with the copolymer component. For example, when the copolymerization component is an aromatic vinyl monomer and the amount used is 15 parts by mass or less in 100 parts by mass of all monomers, a monomer for forming a ring structure is added to the initial mixture, and the reaction is continued. It is preferable not to add to the liquid or to reduce the amount of addition. When the copolymerization component is an aromatic vinyl monomer and the amount used exceeds 15 parts by mass in 100 parts by mass of the total monomers, it is preferable that the ring-forming component is added to the initial mixture and the reaction continuation liquid. . By adjusting the ratio of the amount added to the initial mixture to the amount added to the reaction continuation liquid in this manner, the conversion of the monomer for forming a ring structure can be increased, or the (meth) acrylic monomer can be used as described above. Distribution of the polymer chain (B) when reacting the polymer with the aromatic vinyl monomer can be reduced, and the dispersion stability of the (meth) acrylic block copolymer (P) can be increased. Can be prevented from lowering in transparency. The amount of the monomer for forming a ring structure to be added to the initial mixture when reacting the aromatic vinyl monomer is, for example, 20 parts by mass with respect to 100 parts by mass of the total amount of the monomer for forming a ring structure. Or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and most preferably 100 parts by mass.

  In this polymerization reaction, a vinyl monomer (which does not include a monomer for forming a ring structure) may be copolymerized with the raw material (meth) acrylic monomer. The vinyl monomer may be added to the initial mixture or may be added to the reaction continuation liquid (divided addition, dropping, etc.). The ratio of the amount added to the initial mixture to the amount added to the reaction continuation liquid can be determined by comparing the reactivity of the raw material (meth) acrylic monomer and the vinyl monomer. When the vinyl monomer is an aromatic vinyl monomer, it is preferable to add the vinyl monomer to the reaction continuation liquid while not adding it to the initial mixture or reducing the amount thereof. By increasing the amount added in the reaction continuation liquid, the composition distribution of the polymer chain (B) when copolymerizing the aromatic vinyl monomer can be reduced, and the dispersion stability of the copolymer (P) can be improved. And a decrease in transparency under heating conditions can be further prevented. The addition amount of the vinyl monomer to the reaction continuation liquid is, for example, 70 parts by mass or more, preferably 80 parts by mass or more, more preferably 100 parts by mass, based on 100 parts by mass of the total addition amount of the vinyl monomer. It is 90 parts by mass or more, and most preferably 100 parts by mass.

  In the polymerization reaction, a chain transfer agent may be added to at least one of the initial mixture and the reaction continuation liquid, preferably to the initial mixture. The molecular weight distribution can be reduced by using a chain transfer agent. Examples of the chain transfer agent include butanethiol, octanethiol, octadecanethiol, dodecanethiol, cyclohexylmercaptan, thiophenol, octyl thioglycolate, octyl 2-mercaptopropionate, octyl 3-mercaptopropionate, and 2-ethylhexyl mercaptopropionate. Mercaptans such as octanoic acid 2-mercaptoethyl ester, 1,8-dimercapto-3,6-dioxaoctane, n-dodecylmercaptan, ethylene glycol bisthioglycolate; carbon tetrachloride, carbon tetrabromide, methylene chloride; Halogen compounds such as bromoform and bromotrichloroethane; and α-methylstyrene dimer. The amount of the chain transfer agent used is preferably, for example, 0.01 to 3 parts by mass based on 100 parts by mass of all the monomer components used in the initial mixture and the reaction continuation liquid.

2.3 Reaction Conditions In the initial mixture, the raw material copolymer (P1) and a monomer (raw material (meth) acrylic monomer, ring structure forming monomer, vinyl monomer, etc., especially raw material (meth) acrylic) The system monomer and the monomer for forming a ring structure) may be dissolved or dispersed in the solvent, and the total concentration of the raw material copolymer (P1) and the monomer is, for example, 10 to 80% by mass. , Preferably 30 to 70% by mass, more preferably 40 to 60% by mass.
The radical polymerization initiator added to the reaction continuation liquid may be dissolved or dispersed in the solvent, and the concentration of the radical polymerization initiator added to the reaction continuation liquid is, for example, 1 to 50% by mass, preferably 2 to 50% by mass. It is 30% by mass, more preferably 3 to 25% by mass.
The monomer (raw material (meth) acrylic monomer, monomer for forming a ring structure, vinyl monomer, etc., particularly an aromatic vinyl monomer) added to the reaction continuation liquid is dissolved or dispersed in the solvent. Or when it is a liquid, it may be added as it is without being mixed with a solvent.
The radical polymerization initiator and the monomer to be added to the reaction continuation liquid may be separately added to the reaction continuation liquid, or both may be mixed first and then added to the reaction continuation liquid.

  The reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen gas or in a stream. The reaction temperature is, for example, 50 to 200C, preferably 70 to 150C, and more preferably 90 to 120C. The reaction time is preferably, for example, 1 hour to 20 hours. Further, after the addition of the radical polymerization initiator added to the initial mixture, or after the addition of the radical polymerization initiator to the reaction continuation liquid may include a step of aging, the progress of the polymerization reaction, the degree of formation of a gelled product It may be adjusted appropriately while watching. The aging temperature may be the same as the polymerization temperature at the time of addition of the radical polymerization initiator, or may be maintained at a temperature higher than the polymerization temperature at the time of addition.

The polymerization conversion rate in the polymerization reaction is 85% or more, that is, each monomer (copolymerizable with the raw material (meth) acrylic monomer and the raw material (meth) acrylic monomer) in the polymerization reaction , All of which are 85% or more. By adjusting the polymerization conversion, the amount of olefinic double bonds in the resin composition can be adjusted. When the conversion rate of each monomer is lower than 85%, a new facility for separately recovering the monomer is required, or the residual monomer causes an undesired reaction in the next step, and a gel is generated. Productivity may be significantly impaired. The conversion of each monomer in the polymerization reaction is preferably as follows.
Conversion rate of raw material (meth) acrylic monomer: preferably 90% or more Conversion rate of vinyl monomer copolymerizable with raw material (meth) acrylic monomer (excluding ring structure forming monomer) : Preferably 90% or more, more preferably 95% or more Conversion of the monomer for forming a ring structure: preferably 90% or more, more preferably 94% or more

2.4 Degassing Step In the case where a ring structure is not introduced into the polymer chain (B), a post-treatment step including a devolatilizing step is performed as necessary after the above-mentioned polymerization step. Further, a monomer having a polymerizable double bond in the ring structure (preferably, at least one selected from maleic anhydride and maleimide) is used as a ring-forming monomer to form a ring structure on the polymer chain (B). In the case where is introduced, a special cyclization step is unnecessary, and after the polymerization step, a post-treatment step including a devolatilization step is performed as necessary.

  In the devolatilization step, the polymerization reaction solution containing the polymerization solvent is heated and / or reduced in pressure to remove the solvent. In the devolatilization step, an autoclave, a kettle type reactor, a device including a heat exchanger and a devolatilization tank, an extruder with a vent, and the like can be used, and a dryer may be used.

  When a vented extruder is used, the extruder preferably has a cylinder, a screw provided in the cylinder, and is provided with a heating means. The cylinder is provided with one or more vents. The vent is preferably provided at least on the downstream side of the raw material charging section with respect to the transfer direction in the extruder, and may be provided on the upstream side of the raw material charging section.

  While the polymerization reaction product supplied into the extruder is kneaded with a screw and transferred from the upstream side to the downstream side of the extruder, devolatilization proceeds, and the copolymer (P) is discharged from the downstream side of the extruder. You. A die is preferably provided on the downstream side of the extruder, and the copolymer (P) can be formed into a predetermined shape (film shape or rod shape) by discharging the copolymer (P) from the die. For example, if a rod-shaped copolymer is finely cut, pellets can be produced.

2.5 Cyclization step (ring structure formation step) and devolatilization step On the other hand, (meth) acrylic monomer A, (meth) acrylic monomer B, and (meth) acrylic monomer having a protic hydrogen atom-containing group When copolymerization of the polymer chain (B) is performed using an acid or the like as a monomer for forming a ring structure, a cyclization reaction (ring structure formation step) is performed after the copolymerization reaction, whereby the polymer chain (B) is obtained. Can introduce a ring structure into the main chain. Specifically, the reactive group of the adjoining monomer units of the polymer chains formed in the polymerization step (B) condensation between (ester group, -COOH group, -OH group, -NH ₂ group) reactive Thus, a ring structure is formed in the main chain of the polymer chain (B). The cyclization condensation reaction includes an esterification reaction, an amidation reaction, an acid anhydride reaction, an imidation reaction and the like. For example, a glutaric anhydride structure can be formed by acidifying two carboxylic acid groups of adjacent (meth) acrylic units, and a glutarimide structure can be formed by imidization. When one of the adjacent (meth) acryl units has a protic hydrogen atom-containing group such as a hydroxy group or an amino group, the one (meth) acryl unit has a protic hydrogen atom-containing group and the other (meth) acryl unit has By condensing with the carboxylic acid group of the (meth) acryl unit, a lactone ring structure or a lactam ring structure can be formed.

  In the ring structure forming step, the condensation reaction between the reactive groups of adjacent monomer units is preferably performed in the presence of a catalyst (cyclization catalyst). As the cyclization catalyst, at least one selected from the group consisting of acids, bases and salts thereof can be used. The acids, bases and salts thereof may be organic or inorganic and are not particularly limited. Among them, it is preferable to use an organic phosphorus compound as a catalyst for the cyclization reaction. By using the organic phosphorus compound as the cyclization catalyst, the cyclization condensation reaction can be performed efficiently, and the coloring of the obtained copolymer (P) can be reduced.

  Examples of the organic phosphorus compound that can be used as a cyclization catalyst include alkyl (aryl) phosphonous acids and monoesters or diesters thereof; dialkyl (aryl) phosphinic acids and esters thereof; alkyl (aryl) phosphonic acids and Monoesters or diesters of: alkyl (aryl) phosphinous acid and esters thereof; monoester, diester or triester of phosphite; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate , Lauryl phosphate, stearyl phosphate, isostearyl phosphate, phenyl phosphate, dimethyl phosphate, diethyl phosphate, di-2-ethylhexyl phosphate, diisodecyl phosphate, dilauryl phosphate, distearyl phosphate, phosphorus Monoester, diester or triester of phosphoric acid such as diisostearyl, diphenyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate, triphenyl phosphate, etc. Mono-, di- or tri-alkyl (aryl) phosphine; alkyl (aryl) halogen phosphine; mono-, di- or tri-alkyl (aryl) phosphine; tetraalkyl (aryl) phosphonium halide; These may be used alone or in combination of two or more. Among these, phosphoric acid monoesters or diesters are particularly preferred because of their high catalytic activity and low colorability. The use amount of the cyclization catalyst is preferably, for example, 0.001 to 1 part by mass based on 100 parts by mass of the copolymer obtained in the polymerization step.

  The reaction temperature in the ring structure forming step is preferably from 50C to 300C. The reaction time may be appropriately adjusted while observing the progress of the cyclization condensation reaction, and is preferably performed, for example, for 5 minutes to 6 hours.

  The ring structure forming step is preferably performed under heating. At this time, the polymerization solution containing the polymerization solvent obtained in the polymerization step may be heated as it is, may be heated after devolatilization of the polymerization solvent, or may be performed in combination of both. Examples of the reactor used for the cyclization condensation reaction include an autoclave, a kettle-type reactor, a device including a heat exchanger and a devolatilizing tank, and an extruder with a vent.

  In the ring structure forming step, devolatilization is preferably performed. The devolatilization can be performed by reducing the pressure in the reactor with a vacuum pump or the like. It can also be devolatilized by heating it in an autoclave and drying it in vacuum. By devolatilization, the polymerization solvent used in the polymerization step and brought into the ring structure forming step, alcohol by-produced by the cyclization condensation reaction, and the like are removed, and the residual volatile matter in the obtained copolymer (P) is reduced. can do. Further, since alcohol and the like by-produced in the cyclocondensation reaction are removed, the reaction equilibrium is inclined toward the production side, which is advantageous.

  When performing a cyclization condensation reaction while performing devolatilization, it is preferable to perform the cyclization condensation reaction under reduced pressure from the viewpoint of performing devolatilization efficiently. The reduced pressure in the cyclization condensation reaction is, for example, preferably 90 kPa or less, more preferably 80 kPa or less, and even more preferably 70 kPa or less in absolute pressure. On the other hand, the absolute pressure at the time of depressurization is preferably 0.1 kPa or more, more preferably 1 kPa or more, from the viewpoint that facilities for realizing the depressurized state do not become excessive specifications and keep equipment costs low. When the cyclization condensation reaction is performed without devolatilization, the cyclization condensation reaction may be performed under normal pressure or under pressure.

  When cyclizing while devolatilizing, it is preferable to use a vented extruder. The structure of the vented extruder is the same as the vented extruder used in the devolatilization step. The cyclocondensation reaction proceeds while the polymerization reaction product supplied into the extruder is transferred from the upstream side to the downstream side of the extruder while being kneaded with a screw, and the copolymer (P) is formed from the downstream side of the extruder. Is discharged. A die is preferably provided on the downstream side of the extruder, and the copolymer (P) can be formed into a predetermined shape (film shape or rod shape) by discharging the copolymer (P) from the die. For example, if the rod-shaped copolymer (P) is finely cut, pellets can be produced.

  When the cyclization condensation reaction is performed in the presence of a cyclization catalyst in the ring structure formation step, it is preferable to add a deactivator after or during the cyclization condensation reaction. For example, when a resin composition containing the copolymer (P) is pelletized or formed into a film, if a cyclization catalyst remains in the resin composition, a cyclization condensation reaction occurs to generate alcohol or the like. Thus, undesired foaming may occur. However, such foaming can be prevented by adding a deactivator after or during the cyclocondensation reaction.

  As the deactivator, a substance capable of neutralizing the cyclization catalyst is suitably used. For example, when the cyclization catalyst is an acidic substance, a basic substance can be used as the deactivator, and when the cyclization catalyst is a basic substance, an acidic substance can be used as the deactivator. . As described above, an organic phosphorus compound is suitably used as a cyclization catalyst, and since the compound is often an acidic substance, it is preferable to use a basic substance as a deactivator. The basic substance is not particularly limited as long as it has a function of stopping the cyclization condensation reaction, and examples thereof include a metal carboxylate, a metal complex, and a metal oxide. Conversely, when a basic substance is used as the cyclization catalyst, the above-described acidic substance usable for the cyclization catalyst can be used as the deactivator.

  The timing of adding the deactivator is preferably during or after the cyclocondensation reaction and before pelletizing or film-forming the resin composition containing the copolymer (P). For example, a quenching agent may be added to the molten resin composition, or a quenching agent may be added to the resin composition dissolved in the solvent. When a cyclization condensation reaction is performed using an extruder as described above, a deactivator may be added to a position after the cyclization condensation reaction is sufficiently performed in the extruder.

3. Resin Composition As described above, the resin composition used in the present invention preferably contains the resin (S), and more preferably the resin (S) contains the above-mentioned copolymer (P). Further, the resin composition used in the present invention preferably contains a resin (R) having negative alignment birefringence as a resin component (matrix resin). The resin (R) preferably contains a (meth) acrylic polymer (Q), and the (meth) acrylic polymer (Q) has excellent compatibility with the copolymer (P). preferable. By including the (meth) acrylic polymer (Q), the transparency and heat resistance of the film can be easily increased.

  The (meth) acrylic polymer (Q) may be any polymer having a unit derived from the (meth) acrylic monomer described in the polymer chain (B), and preferably the polymer chain (B) )). The (meth) acrylic polymer (Q) may have a unit derived from another unsaturated monomer described in the polymer chain (B). The structural unit of the (meth) acrylic polymer (Q) is preferably the same as the structural unit of the polymer chain (B) from the viewpoint of increasing the compatibility with the copolymer (P).

  The (meth) acrylic polymer (Q) preferably has a ring structure, and more preferably has a ring structure in the main chain. Thereby, the transparency and heat resistance of the film can be increased. The ring structure of the main chain of the (meth) acrylic polymer (Q) includes a lactone ring structure, a lactam ring structure, a cyclic imide structure (eg, a succinimide structure, a glutarimide structure, etc.), and a cyclic anhydride structure (eg, anhydrous Preferable examples include a succinic acid structure and a glutaric anhydride structure. For details of these ring structures, refer to the description regarding the ring structure of the polymer chain (B). In particular, the (meth) acrylic polymer (Q) preferably has the same ring structure in the main chain as the polymer chain (B) of the copolymer (P).

  The (meth) acrylic polymer (Q) has the same (meth) acrylic unit as the (meth) acrylic unit in the polymer chain (B) of the copolymer (P), and has a ring in the polymer chain (B). It preferably has the same ring structural unit as the structural unit. Thereby, the compatibility between the (meth) acrylic polymer (Q) and the copolymer (P) is increased, and the transparency and heat resistance of the film can be easily increased.

  Such a (meth) acrylic polymer (Q) is obtained by polymerizing the polymer chain (B) -forming monomer separately from the raw material copolymer (P1) when polymerizing the copolymer (P). By doing so, it is convenient to polymerize together in the same polymerization reaction system. In the method for producing the copolymer (P) described above, the (meth) acrylic polymer (Q) corresponding to the polymer chain (B) of the copolymer (P) is simultaneously formed with the copolymer (P). The resin composition containing the copolymer (P) and the (meth) acrylic polymer (Q) is produced by not separating the copolymer (P) and the (meth) acrylic polymer (Q). You can get things. The resin composition containing only the (meth) acrylic copolymer (Q) and the copolymer (P) as a polymer, which is obtained in this manner, is hereinafter referred to as a “two-component mixture”. There is. In order to make the resin composition contain a polymer other than the (meth) acrylic polymer (Q), the copolymer (P) may or may not be isolated be blended with another polymer. .

  The content of the copolymer (P) in the resin composition is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and still more preferably 15% by mass or more. It is easy to increase the mechanical strength of the resin molded body. The upper limit of the content ratio of the copolymer (P) in the resin composition is not particularly limited, and the resin composition may be composed of only the copolymer (P). The content ratio of P) may be 90% by mass or less, 70% by mass or less, 50% by mass or less, 40% by mass or less, or 30% by mass or less.

  The content of the polymer chain (A) in the copolymer (P) in the resin composition is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and 50% by mass or less. Is preferably 40% by mass or less, and more preferably 30% by mass or less. When the content ratio of the polymer chain (A) in the resin composition is 1% by mass or more, it is easy to increase the mechanical strength of the resin molded body. When the content ratio of the polymer chain (A) in the resin composition is 50% by mass or less, the transparency and heat resistance of the resin molded product are easily increased. When the content of the polymer chain (A) in the resin composition is 50% by mass or less, the positive alignment canceling out the negative orientation birefringence derived from the resin (R) in the film on which the phase separation structure is formed. Form birefringence can be expressed.

  The content of the ring structural unit in the solid content of 100% by mass of the resin composition is not particularly limited, but is preferably 3% by mass or more, more preferably 4% by mass or more, still more preferably 5% by mass or more, and 50% by mass. Is preferably not more than 45% by mass, more preferably not more than 40% by mass. By adjusting the content of the ring structural unit within the above range, it becomes easy to increase both the heat resistance and the mechanical strength of the resin composition in a well-balanced manner. The content of the ring structural unit described here is determined by the content of the unit having a ring structure contained in the main chain of the polymer chain (B) of the copolymer (P) and the content of the (meth) acrylic polymer ( Q) means the ring structure contained in the main chain, and means, for example, the content ratio of the structures represented by the above formulas (1) to (3).

  The content ratio of the (meth) acrylic polymer (Q) in the resin composition is preferably 1% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and still more preferably 30% by mass or more. Preferably, it is 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less. In addition, the total content of the (meth) acrylic polymer (Q) and the polymer chain (B) in the resin composition is preferably 30% by mass or more, more preferably 50% by mass or more, and further preferably 70% by mass or more. Preferably, it is 99% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less.

  The total content of the copolymer (P) and the (meth) acrylic polymer (Q) in the resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. , 90% by mass or more is even more preferable. The upper limit of the content ratio of the copolymer (P) and the (meth) acrylic polymer (Q) in the film is not particularly limited, and the film is substantially composed of the copolymer (P) and the (meth) acrylic polymer. It may be composed only of (Q).

  The resin composition used in the present invention may contain a polymer other than the (meth) acrylic polymer (Q) described above. Examples of such a polymer include polyethylene, polypropylene, Olefin polymers such as ethylene-propylene polymer and poly (4-methyl-1-pentene); halogen-containing polymers such as vinyl chloride and chlorinated vinyl resin; polystyrene, styrene-methyl methacrylate copolymer, styrene Styrene-based polymers such as acrylonitrile copolymer and acrylonitrile-butadiene-styrene copolymer; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate; polyamides such as nylon 6, nylon 66 and nylon 610; polyacetals; polycarbonate. ; Polyphenylene Oxide; Polyphenylene sulfide; Polyetheretherketone; Polysulfone; Polyethersulfone; Polyoxypendylene; Polyamideimide; Cycloolefin polymer; Cellulose derivative; And the like.

  The weight average molecular weight of the resin composition (preferably a two-component mixture) is preferably 20,000 or more, more preferably 50,000 or more, still more preferably 30,000 or more, still more preferably 50,000 or more. It is particularly preferably not less than 10,000, more preferably not more than 600,000, more preferably not more than 400,000, still more preferably not more than 300,000, still more preferably not more than 200,000, and particularly preferably not more than 150,000. By setting the weight average molecular weight of the resin composition in such a range, the moldability of the copolymer (P) is improved.

  The molecular weight distribution (= weight average molecular weight / number average molecular weight) of the resin composition (preferably a two-component mixture) is, for example, 1.5 or more, preferably 1.8 or more, more preferably 2.0 or more, For example, it is 5.0 or less, preferably 4.0 or less, and more preferably 3.0 or less.

  The weight average molecular weight of the resin composition (preferably a two-component mixture) is preferably at least 1.1 times, more preferably at least 1.2 times, more preferably at least 1.3 times the weight average molecular weight of the polymer chain (A). It is preferably 10 times or less, more preferably 7 times or less, and even more preferably 5 times or less. Thereby, it becomes easy to give each property of transparency and mechanical strength to the copolymer (P) in a well-balanced manner.

  The refractive index of the resin composition is preferably a value close to the refractive index of the polymer chain (A) of the copolymer (P), which facilitates ensuring the transparency of the resin composition. Specifically, the difference between the refractive index of the resin composition and the refractive index of the polymer chain (A) of the copolymer (P) is preferably less than 0.1, more preferably 0.05 or less, and 0 or less. 0.02 or less is more preferable.

  The resin composition preferably has an insoluble content in chloroform of 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. In this case, the resin composition has a small amount of foreign matter contained therein. For example, when a film is formed from the resin composition, a highly transparent film having few surface irregularities and defects can be easily obtained. In addition, when removing foreign matter from the resin composition, the load on the foreign matter removing filter is reduced, and the production efficiency is improved. The amount of insoluble matter in chloroform of the resin composition was determined by adding 1 g of the resin composition to 20 g of chloroform, filtering the resin composition through a Teflon (registered trademark) membrane filter having a pore size of 0.5 μm, and collecting the insoluble matter in the membrane filter. Can be determined by measuring

  The internal haze per 100 μm thickness when formed into an unstretched film is preferably 2.0% or less, more preferably 1.0% or less, still more preferably 0.50% or less, and 0.30% or less. % Or less is particularly preferable, and 0.18% or less is most preferable. The lower limit of the internal haze is not particularly limited, but is, for example, 0.01% or more. The internal haze is determined by the method described in the examples.

  The breaking energy (impact strength) of the unstretched film having a thickness of 160 μm is preferably 30 mJ or more, more preferably 40 mJ or more. By setting the film to have a breaking energy of 30 mJ or more, the film has high mechanical strength. The breaking energy is determined by the method described in the examples.

  The resin composition may contain various additives. Examples of the additives include an ultraviolet absorber; an antioxidant such as a hindered phenol-based compound, a phosphorus-based compound and a sulfur-based compound; a stabilizer such as a light stabilizer, a weather stabilizer and a heat stabilizer; Reinforcing material; Near infrared absorbing agent; Flame retardant such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide; Retardation adjusting agent such as retardation increasing agent, retardation reducing agent, retardation stabilizer; Antistatic agents including cationic or nonionic surfactants; coloring agents such as inorganic pigments, organic pigments, and dyes; organic fillers and inorganic fillers; resin modifiers; organic fillers and inorganic fillers; . The content ratio of each additive in the resin composition is preferably in the range of 0 to 5% by mass, more preferably 0 to 2% by mass.

  The resin composition preferably has a glass transition temperature of 115 ° C. or higher, and more preferably has a glass transition temperature of 115 ° C. or higher and lower than 115 ° C., respectively. The glass transition temperature of 115 ° C. or higher is referred to as “high-temperature glass transition temperature”, and the glass transition temperature of less than 115 ° C. is referred to as “low-temperature glass transition temperature”. The resin composition may have a plurality of glass transition temperatures on the high temperature side, or may have a plurality of glass transition temperatures on the low temperature side. Since the resin composition has a glass transition temperature on the high temperature side, the heat resistance of the resin composition is increased, and when the resin composition is formed into a film or the like, the resin composition does not soften even at a high temperature, and improves moldability. Can be. When the resin composition has a low glass transition temperature, the mechanical strength and impact resistance of the resin composition can be increased. The glass transition temperature on the high temperature side of the resin composition is 115 ° C. or higher, preferably 120 ° C. or higher, and from the viewpoint of improving the processability of the resin composition, is preferably lower than 300 ° C., more preferably lower than 200 ° C., The temperature is more preferably less than 180 ° C, particularly preferably 150 ° C or less, most preferably 140 ° C or less. The glass transition temperature on the low temperature side of the resin composition is preferably -100 ° C or higher, more preferably -70 ° C or higher, preferably less than 50 ° C, more preferably less than 30 ° C, still more preferably less than 10 ° C, and -20 ° C. Is particularly preferred, and less than -50C is most preferred.

4. Film The resin composition can be molded into a film by molding according to a known method. The method for forming the film will be described later.

  From the viewpoint of increasing the strength of the film, the thickness of the film is preferably 5 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. On the other hand, from the viewpoint of reducing the thickness of the film, the thickness of the film is preferably 350 μm or less, more preferably 200 μm or less, further preferably 150 μm or less, and particularly preferably 60 μm or less. The thickness of the film can be measured using, for example, a Digimatic micrometer manufactured by Mitutoyo Corporation.

The film of the present invention is preferably a uniaxially or biaxially stretched film. By using a uniaxially or biaxially stretched film, the degree of orientation birefringence can be adjusted. Since the orientation birefringence can be adjusted independently of the form birefringence, the retardation of the film can be easily reduced.
In addition, by using a uniaxially or biaxially stretched film, a film having high mechanical strength can be obtained. Specifically, the film of the present invention has a number of folding times of 1000 or more in an MIT test based on JIS P 8115 (2001). On the other hand, for example, in the case of a polymethyl methacrylate or a (meth) acrylic polymer having a lactone ring structure in the main chain as disclosed in JP-A-2008-191426, even if this is formed into a stretched film, It is difficult to provide high mechanical strength, and the number of times of folding in the MIT test is at most about several hundred times. The film of the present invention preferably has a fold resistance of 2000 times or more, more preferably 3000 times or more. The folding number may be 5000 times or more, 7000 times or more, or 9000 times or more. The upper limit of the number of times of folding is not particularly limited. The number of folding endurance by the MIT test is determined by the method described in the examples.

  The film of the present invention preferably has an internal haze of 1.0% or less, more preferably 0.50% or less, particularly preferably 0.30% or less, and most preferably 0.10% or less. The lower limit of the internal haze is not particularly limited, but is, for example, 0.01% or more. The internal haze is determined by the method described in the examples.

  The film of the present invention preferably has an internal haze per 100 μm thickness of 2.0% or less, more preferably 1.0% or less, still more preferably 0.50% or less, and 0.30% or less. The following is particularly preferred, and the most preferred is 0.18% or less. The lower limit of the internal haze is not particularly limited, but is, for example, 0.01% or more. The internal haze is determined by the method described in the examples.

  The film of the present invention preferably has a breaking energy (impact strength) of 30 mJ or more, more preferably 40 mJ or more. By setting the film to have a breaking energy of 30 mJ or more, the film has high mechanical strength. The breaking energy is determined by the method described in the examples.

The film of the present invention preferably has a glass transition temperature in a temperature range of 115 ° C. or higher from the viewpoint of increasing heat resistance. The glass transition temperature is preferably 120 ° C. or higher, more preferably 130 ° C. or higher. In addition, from the viewpoint of enhancing workability during film formation, the glass transition temperature is preferably lower than 300 ° C, more preferably lower than 200 ° C, further preferably lower than 180 ° C, particularly preferably 150 ° C or lower, and particularly preferably 140 ° C or lower. Most preferred.
When the glass transition temperature described above is defined as the glass transition temperature on the high temperature side, the film of the present invention preferably has a glass transition temperature on the low temperature side in a temperature range of less than 115 ° C. If the film has such a low glass transition temperature, the mechanical strength and impact resistance of the film can be increased. The glass transition temperature on the low temperature side is preferably less than 50 ° C, more preferably less than 30 ° C, still more preferably less than 10 ° C, particularly preferably less than -20 ° C, most preferably less than -50 ° C, and more preferably -100 ° C or more. Preferably, it is -90 ° C or higher, more preferably -80 ° C or higher.

5. Method for Forming Film As a method for forming the film, known methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method can be used. Among these, the solution casting method and the melt extrusion method are preferred.

  Examples of an apparatus for performing the solution casting method include a drum-type casting machine, a band-type casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method. When a film is formed by a melt extrusion method, a stretched film may be formed by stretching. By stretching, the mechanical strength of the film can be further improved. As a stretching method for obtaining a stretched film, a conventionally known stretching method can be applied. For example, uniaxial stretching such as free-width uniaxial stretching and constant-width uniaxial stretching; biaxial stretching such as sequential biaxial stretching and simultaneous biaxial stretching; and when a film is stretched, a shrinkable film is adhered to one or both surfaces to form a laminate. Forming, by applying a heat-stretching treatment to the laminate and applying a shrinkage force in a direction perpendicular to the stretching direction to the film, a birefringent film in which molecules oriented in the stretching direction and the thickness direction are mixed is formed. Stretching to be obtained. From the viewpoint of improving the mechanical strength such as the folding resistance of the film, biaxial stretching is preferably used. The stretching conditions such as the stretching ratio, the stretching temperature, and the stretching speed may be appropriately set according to the desired mechanical strength and retardation value, and are not particularly limited.

  Examples of the stretching device include a roll stretching machine, a tenter-type stretching machine, and a small-sized experimental stretching device such as a tensile tester, a uniaxial stretching machine, a sequential biaxial stretching machine, and a simultaneous biaxial stretching machine. An apparatus can be used.

6. Optical Film The film of the present invention can be suitably used as an optical film because the retardation is very small. The optical film may be a uniaxially or biaxially stretched film or an unstretched film, but is preferably a uniaxially or biaxially stretched film, and more preferably a biaxially stretched film. When the stretched film is applied to an optical film, a heat treatment (annealing) may be performed as needed after stretching in order to stabilize the optical properties and mechanical properties of the optical film.

  Examples of the optical film include an optical protective film (specifically, a protective film for a substrate of various optical disks (VD, CD, DVD, MD, LD, etc.)) and a polarizing plate provided in an image display device such as a liquid crystal display. And a viewing angle compensation film, a light diffusion film, a reflection film, an antireflection film, an antiglare film, a brightness enhancement film, a conductive film for a touch panel, a light conversion film, and the like.

  The optical film of the present invention can also be used as a polarizer protective film by laminating it on one or both sides of a polarizer. By forming a transparent conductive layer on the surface, it can be used as a transparent conductive film.

  The optical film (for example, a polarizer protective film and a transparent conductive film) of the present invention can be suitably used for an image display device. Examples of the image display device include a liquid crystal display device and the like. For example, in the case of a liquid crystal display device, the image display section can be configured to include the optical film of the present invention together with members such as a liquid crystal cell, a polarizing plate, and a backlight. Examples of the image display device other than the liquid crystal display device include an electroluminescence (EL) display panel, a plasma display panel (PDP), a field emission display (FED), a QLED, and a micro LED.

  Hereinafter, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to the following Examples, and may be appropriately modified within a range that can be adapted to the purpose of the preceding and the following. It is of course possible to carry out them, and all of them are included in the technical scope of the present invention. In the following description, “parts” means “parts by mass” and “%” means “% by mass” unless otherwise specified.

(1) Analysis method (1-1) Weight average molecular weight (Mw) and number average molecular weight (Mn)
The weight average molecular weight and the number average molecular weight were determined by gel permeation chromatography (GPC) in terms of polystyrene. The apparatus and measurement conditions used for the measurement are as follows.
-Measurement system: GPC system HLC-8220 manufactured by Tosoh Corporation
-Measurement side column configuration Guard column: Tosoh Corporation, TSKguardcolumn SuperHZ-L
Separation column: Tosoh Corp., TSKgel SuperHZM-M two-series connection-reference side column configuration Reference column: Tosoh Corp., TSKgel SuperH-RC
-Developing solvent: chloroform (Wako Pure Chemical Industries, special grade)
-Solvent flow rate: 0.6 mL / min-Standard sample: TSK standard polystyrene (Tosoh Corporation, PS-oligomer kit)

(1-2) Glass transition temperature (Tg)
The glass transition temperature was determined based on JIS K 7121 (2012). Specifically, using a differential scanning calorimeter (manufactured by Rigaku Corporation, Thermo plus EVO DSC-8230), the sample is heated from normal temperature to 200 ° C. (temperature rising rate: 20 ° C./min) under a nitrogen gas atmosphere. From the obtained DSC curve, evaluation was made by the starting point method. Α-alumina was used as a reference. The glass transition temperature of less than 40 ° C. was raised from -100 ° C. to 60 ° C. (temperature rising rate 10 ° C./min) in a nitrogen gas atmosphere using a differential scanning calorimeter (DSC-3500, manufactured by Netsch). Was evaluated by the starting point method from the obtained DSC curve. An empty container was used as a reference.

(1-3) Conversion rate of monomer and composition of resin composition The conversion rate (reaction rate) of the monomer and the composition of the resin composition were measured by gas chromatography (GC-2014, manufactured by Shimadzu Corporation) in the polymerization solution. It was determined by measuring the amount of residual monomer. The measurement apparatus and measurement conditions for gas chromatography are as follows.
Column: ULBON HR-1, manufactured by Shinwa Kabushiki Kaisha, length 50 m, inner diameter 0.25 mm, film thickness 0.25 μm
Column temperature raising condition: After maintaining at 60 ° C. for 5 minutes, the temperature was raised to 235 ° C. over 35 minutes at a rate of 5 ° C./min, and further over 3.2 minutes to 315 ° C. at a rate of 25 ° C./min. And the temperature was maintained for 10 minutes.
Evaporation chamber temperature: 250 ° C
Detector (FID) temperature: 320 ° C
Carrier gas: helium (250 kPa)
Total flow rate: 19.2 mL / min Column flow rate: 2.69 mL / min Split ratio: 5.0

(1-4) Breaking energy (impact strength)
The resin composition was hot-pressed at 250 ° C. to produce a 160 μm-thick film (unstretched film). A test of dropping a ball having a mass of 0.0054 kg from a certain height on this film was performed 10 times, and an average value of the height (breaking height) when the film was broken was obtained. Specifically, the height was set in several stages, and when the sphere was dropped in order from the lower height, the height at which the film broke was obtained, and this was repeated 10 times to break the film. The height was determined 10 times, and the average value was determined as the breaking height. Whether or not the film was broken was determined by visually checking whether or not the film was deformed after the ball was dropped on the film. If deformation occurred, the film was considered to have been destroyed. The breaking energy (E) was determined according to the following equation: breaking energy E (mJ) = mass of sphere (kg) × mean value of breaking height (mm) × 9.8 (m / s ² ).

(1-5) Dispersion state (Observation of sea-island structure size by STEM)
The resin composition was hot-pressed at 250 ° C. to produce a film (unstretched film) having a thickness of about 160 μm. The dispersed state (sea-island structure) of the film due to phase separation was observed with a scanning electron microscope (FE-SEM S-4800, manufactured by Hitachi High-Technologies Corporation). The measurement conditions were as follows: acceleration voltage 20 kV, emission current 5 μA or 10 μA, W. D. = 8 mm. The island size was calculated as the average value of the maximum lengths of any 10 islands.

(1-6) Folding Resistance Number by MIT Test The resin composition was hot-pressed at 250 ° C. to produce a film (unstretched film) having a thickness of about 160 μm. The obtained unstretched film is cut out to a size of 96 mm x 96 mm, and is sequentially heated at 240 mm / min at a temperature of Tg of the resin composition + 24 ° C using a sequential biaxial stretching machine (X6-S, manufactured by Toyo Seiki Seisaku-sho, Ltd.). The biaxial stretching was sequentially performed so that the stretching ratio became twice in the longitudinal direction (MD direction) and the transverse direction (TD direction) at the stretching speed, and the film was cooled to obtain a stretched film having a thickness of 40 μm. The obtained stretched film was cut into a size of 90 mm (MD direction) × 15 mm (TD direction) to obtain a test piece, and a temperature of 23 ° C. was measured by using an MIT bending resistance tester (BE-201, manufactured by Tester Sangyo Co., Ltd.). A 200 g load was applied in an atmosphere at a relative humidity of 50%, and a MIT bending resistance test was performed based on JIS P 8115 (2001) to measure the number of times of folding.

(1-7) Internal haze A quartz cell is filled with 1,2,3,4-tetrahydronaphthalene (tetralin), and a 40 μm-thick stretched film produced by the method described in (1-6) is immersed therein. The haze was measured using a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.). Further, the internal haze per 100 μm thickness was calculated according to the following formula: internal haze per 100 μm thickness (%) = obtained measured value (%) × (100 μm / thickness of film (μm)). The measurement was performed using three films, and the internal haze per 100 μm thickness was calculated from the average value.

(1-8) Phase difference The stretched film produced by the same method as described in the above (1-6) is incident on a stretched film using a fully automatic birefringence meter (KOBRA-WR, manufactured by Oji Scientific Instruments). Under the condition of 40 °, the in-plane retardation Re and the thickness direction retardation Rth for light having a wavelength of 589 nm were measured. The refractive index in the slow axis direction in the plane of the film is nx, the refractive index in the fast axis direction in the plane of the film is ny, the refractive index in the thickness direction of the film is nz, and the thickness of the film is d. The in-plane retardation Re and the thickness direction retardation Rth were determined from the equations.
In-plane retardation Re = (nx−ny) × d
Thickness direction phase difference Rth = [(nx + ny) / 2−nz] × d

(1-9) Stress optical coefficient Cr
The stress optical coefficient Cr of the resin composition was determined as follows, with the measurement wavelength being 589 nm.

First, the prepared resin composition was hot-pressed by a hot press at 250 ° C. to obtain an unstretched film (190 μm in thickness) of the polymer. Next, the produced unstretched film was cut out in a size of 20 mm × 60 mm to obtain a test piece for evaluating Cr. Next, on one short side of the test piece, a weight having a weight of 1 N / mm ² or less is applied to the test piece during stretching, and the weight is selected and attached. It was accommodated in the held constant-temperature dryer (DOV-450A, manufactured by AS ONE) and left for 1 hour. When storing the test piece in the constant temperature dryer, the other short side of the test piece is fixed by a chuck, and the test piece is uniaxially free-ended in the long side direction (vertical direction) by the stress applied to the test piece by the weight. It was stretched. When the test piece was accommodated, the distance between the chuck and the weight in the test piece was 40 mm. After heating and stretching for one hour, the heater of the dryer was turned off, and the test piece was naturally cooled in the dryer as it was. When the temperature in the oven reached Tg-40 ° C. of the polymer, the test piece (uniaxially stretched film) was taken out, and the thickness of the taken out test piece and the in-plane retardation Re with respect to light having a wavelength of 589 nm were measured. The in-plane birefringence Δn of the test piece was calculated. Separately from this, the cross-sectional area of the test piece after being stretched by the weight load was obtained, and the stress σ (Pa) applied to the film was calculated from the cross-sectional area and the weight load. While changing the weight of the weight, Δn and σ were obtained for each load, and the slope of Δn with respect to the obtained σ was obtained by the least square method, and this was defined as the stress optical coefficient Cr (Pa ⁻¹ ). When the orientation angle at the time of measuring the in-plane retardation Re is close to 0 ° with respect to the stretching direction (load application direction), the sign of the stress optical coefficient Cr is positive. In this case, the orientation birefringence of the polymer to be evaluated is positive. On the other hand, when the orientation angle is near 90 ° with respect to the stretching direction, the sign of the stress optical coefficient Cr becomes negative. In this case, the orientation birefringence of the polymer to be evaluated is negative. The larger the absolute value of Cr, the higher the birefringence due to stretching (the retardation).

<Example 1>
In a reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen inlet pipe, a first SEBS triblock copolymer (Taftec (registered trademark) P1083, manufactured by Asahi Kasei Corporation, olefinic double bond amount 2.01 mmol / g, styrene unit content: 18.3% by mass, refractive index: 1.500, weight average molecular weight: 94,000, number average molecular weight: 64,000), 3 parts, a second SEBS triblock copolymer (Asahi Kasei Corporation) Manufactured by Tuftec (registered trademark) H1052, olefinic double bond content 0.27 mmol / g, styrene unit content 15.7 mass%, refractive index 1.500, weight average molecular weight 94,000, number average molecular weight 6. 90,000), 73.8 parts of methyl methacrylate (MMA), 10.8 parts of methyl 2- (hydroxymethyl) acrylate (MHMA), n-dodecyl mercaptan (nDM) 0.025 parts, was charged 100 parts of toluene as a polymerization solvent, was this was warmed to 105 ° C. while nitrogen gas. Thereafter, 0.06 parts of t-butyl peroxyisopropyl carbonate (Kayacaron (registered trademark) Bic75, manufactured by Kayaku Akzo) was added as an initiator. After confirming the start of the polymerization reaction by raising the temperature of the polymerization solution, the addition of styrene (St) and t-butylperoxyisopropyl carbonate was started. Styrene (St) (5.4 parts) was added at a constant rate over 3 hours, and 0.185 parts of t-butylperoxyisopropyl carbonate diluted with 1 part of toluene was added dropwise at a constant rate over 4 hours. Solution polymerization was carried out at 105 to 110 ° C while adding t-butylperoxyisopropyl carbonate, and then aging was performed for 2 hours. To this, 0.075 part of stearyl phosphate was added as a cyclization catalyst, and a cyclization condensation reaction for forming a lactone ring structure was performed under reflux at 90 to 110 ° C for 2 hours. To the obtained reaction solution, a sulfur-based antioxidant (ADEKA Corporation, Adekastab (registered trademark) AO-412S) and a hindered phenol-based antioxidant (ADEKA Corporation, Adekastab (registered trademark) AO-60) were respectively added. 0.05 parts were added. Thereby, a (meth) acrylic copolymer having a lactone ring structure in the main chain formed by polymerization of MMA, MHMA, and St, and the copolymer chain is derived from a diene / olefin of a SEBS triblock copolymer chain A resin composition containing a graft copolymer bonded to units was obtained. The conversion of MMA calculated from the amount of residual monomer in the polymerization solution at the end of the reaction was 94%, the conversion of MHMA was 94%, and the conversion of St was 99%. The composition ratio (by mass) of the (meth) acrylic copolymer chain and the (meth) acrylic copolymer bonded to the SEBS triblock copolymer chain calculated from the conversion rate is MMA: MHMA: St. = 82.6: 11.9: 5.5, and the content of the ring structural unit was 22.0% by mass.
Next, the obtained polymerization solution was passed through a multitubular heat exchanger heated to 240 ° C. to complete the cyclocondensation reaction. Thereafter, the polymer subjected to cyclocondensation was heated at a barrel temperature of 250 ° C., one rear vent, four forvents (first, second, third, and fourth vents from the upstream side) and a fourth vent. A vent-type screw twin-screw extruder (L / D = 52) provided with a side feeder between the third vent and the fourth vent and having a leaf disk-type polymer filter (filtration accuracy: 5 μm) at the tip end is provided with 33 It was introduced at a processing speed of 0.7 parts / hour (in terms of resin amount). At that time, ion-exchanged water was introduced from the back of the second vent at an introduction rate of 0.50 parts / hour, and 0.66 parts of an ultraviolet absorber (ADEKA STAB (registered trademark) LA-F70, manufactured by ADEKA) was added to toluene 1 .23 parts of the solution was introduced from behind the third vent at a rate of 0.64 parts / hour, and ion-exchanged water was introduced from behind the fourth vent at a rate of 0.50 parts / hour. And devolatilized.
After the devolatilization is completed, the resin composition in the hot melt state remaining in the extruder is discharged from the tip of the extruder while being filtered by a polymer filter, and after passing through a die provided, a filter having a pore diameter of 1 μm (manufactured by Organo Corporation) The strands are cooled by a water tank filled with cooling water maintained at a temperature within a range of 30 ± 10 ° C., filtered through a micropore filter 1EU), and introduced into a cutting machine (pelletizer), whereby a lactone ring is formed. A lactone ring polymer having a structure in the main chain, a graft copolymer in which the copolymer chain is bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain, and an ultraviolet absorber (UV absorber). A pellet comprising the resin composition (P-1) was obtained.
The weight average molecular weight of the obtained resin composition (P-1) is 138,000, the number average molecular weight is 52,000, the glass transition temperature on the high temperature side is 121 ° C, and the glass transition temperature on the low temperature side is -54 ° C. And the refractive index was 1.500. When the obtained polymer composition was formed into a press film, the size of the sea-island structure was 140 nm. From the dispersion state shown in FIG. 1, it was determined to have a phase separation state. The breaking energy was 40 mJ or more. When the film of the resin composition (P-1) was stretched to Tg + 24 ° C., the number of MITs in the stretched film having a thickness of 40 μm was 10,000 or more, and the film had strong strength. The internal haze of the stretched film having a thickness of 40 μm was 0.06% (0.14% per 100 μm thickness). The stretched film having a thickness of 40 μm had Re of 0.1 nm and Rth of +6.3 nm, and was confirmed to be a low retardation film.

<Example 2>
The polymerization solution was the same as in Example 1, and the polymerization solution was introduced at a processing rate of 33.7 parts / hour (in terms of the amount of resin) under the charging conditions of the twin-screw extruder. After that, ion-exchanged water was charged at a charging rate of 0.50 parts / hour, and devolatilization was carried out in the same manner as in Example 1, except that the lactone ring structure was changed to the main chain. A pellet comprising a resin composition (P-2) containing a lactone ring-based polymer having the above and a graft copolymer in which the copolymer chain is bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain. Obtained.
The weight average molecular weight of the obtained resin composition (P-2) is 1370, the number average molecular weight is 51,000, the glass transition temperature on the high temperature side is 122 ° C, and the glass transition temperature on the low temperature side is -54 ° C. And the refractive index was 1.500. The size of the sea-island structure when the obtained polymer composition was formed into a press film was 120 nm, and it was determined that the polymer composition had a phase separation structure as in Example 1. The breaking energy was 40 mJ or more. When the film of the resin composition (P-2) was stretched to Tg + 24 ° C., the number of MITs in the stretched film having a thickness of 40 μm was 10,000 or more, and had a strong strength. The internal haze of the stretched film having a thickness of 40 μm was 0.07% (0.18% per 100 μm thickness). Further, Re of the stretched film having a thickness of 40 μm was 0.1 nm and Rth was +3.0 nm, and it was confirmed that the film was a low retardation film.

<Example 3>
In a reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing pipe, a third SEBS triblock copolymer (A1536, manufactured by Kraton, 0.08 mmol / g of olefinic double bond, containing styrene unit) 38.8% by mass, refractive index 1.519), 15 parts, methyl methacrylate (MMA) 65.7 parts, phenylmaleimide (PMI) 15.7 parts, n-dodecylmercaptan (nDM) 0.1 part. 07 parts and 100 parts of toluene as a polymerization solvent were charged, and the temperature was raised to 105 ° C. while passing nitrogen through the mixture. Thereafter, 0.058 parts of t-butyl peroxyisopropyl carbonate (Kayacarbon (registered trademark) Bic75, manufactured by Kayaku Akzo) was added as an initiator. After confirming the start of the polymerization reaction by raising the temperature of the polymerization solution, the addition of styrene (St) and t-butylperoxyisopropyl carbonate was started. Solution polymerization at 105 to 110 ° C. while dropping 3.6 parts of styrene (St) and 0.115 parts of t-butyl peroxyisopropyl carbonate in 1 part of toluene at a constant rate over 4 hours. After completion of the addition of t-butyl peroxyisopropyl carbonate, the mixture was further aged for 3 hours. Thereby, a (meth) acrylic copolymer polymerized and formed from MMA, PMI, and St, and a graft copolymer in which the copolymer chain is bonded to a diene / olefin-derived unit of a SEBS triblock copolymer chain Was obtained. The conversion of MMA calculated from the amount of residual monomers in the polymerization solution at the end of the reaction was 94%, the conversion of PMI was 98%, and the conversion of St was 99%. The composition ratio (by mass) of the (meth) acrylic copolymer chain and the (meth) acrylic copolymer bonded to the SEBS triblock copolymer chain calculated from the conversion is MMA: PMI: St. = 78: 17.8: 4.8, and the content of the ring structural unit was 17.8% by mass.
Next, the obtained polymerization solution was treated in a vent-type screw twin-screw extruder (pore diameter: 15 mm, L / D: 45) having one rear vent and two forevents at a resin conversion of 600 g / h. The mixture was introduced at a speed, devolatilized in the extruder, and extruded to obtain pellets of a transparent resin composition (P-3). The operating conditions of the twin-screw extruder were a barrel temperature of 260 ° C., a rotation speed of 300 rpm, and a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg). The obtained resin composition has a weight average molecular weight of 1390,000, a number average molecular weight of 58,000, a glass transition temperature on the high temperature side of 138 ° C, a glass transition temperature on the low temperature side of -68 ° C, and a refractive index of 1 .517. The size of the sea-island structure when the obtained resin composition (P-3) was formed into a press film was 260 nm, and it was determined that the resin composition (P-3) had a phase separation structure as in Example 1. The breaking energy was 40 mJ or more. When the film of the resin composition (P-3) was stretched to Tg + 24 ° C., the number of MITs in the stretched film of 40 μm was 3,000 or more, and the film had strong strength. The internal haze of the stretched film having a thickness of 40 μm was 0.03% (0.08% per 100 μm thickness). The stretched film having a thickness of 40 μm had Re of 0.6 nm and Rth of +3.2 nm, and was confirmed to be a low retardation film.

<Comparative Example 1>
The glass transition temperature of a commercially available PMMA resin (manufactured by Sumitomo Chemical Co., Ltd., Sumipex EX weight average molecular weight: 146,000, number average molecular weight: 73,000, hereinafter sometimes referred to as a resin composition (P-4)) was measured to be 107. ° C. Further, the stress optical coefficient Cr was −15 × 10 ⁻⁹ Pa ⁻¹ and had negative orientation birefringence. Further, the resin composition (P-4) was hot-pressed at 250 ° C. to form an unstretched film having a thickness of 160 μm, and Tg + 24 was obtained by using a sequential biaxial stretching machine (X-6S, manufactured by Toyo Seiki Seisaku-sho, Ltd.). Stretching was performed at a temperature of ° C to obtain a stretched film of 40 µm. The number of MITs of the stretched film was 700 times, and did not have sufficient strength. The internal haze of the stretched film having a thickness of 40 μm was 0.02% (0.05% per 100 μm thickness). Further, Re of the stretched film having a thickness of 40 μm was 1.8 nm, and Rth was −12.0 nm. That is, it was confirmed that the PMMA resin had negative orientation birefringence.

<Reference Example 1>
Same as Example 1 except that the first SEBS triblock copolymer and the second SEBS triblock copolymer were not added to a reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe. According to the method, pellets composed of a resin composition containing a lactone ring-based polymer having a lactone ring structure in the main chain and an ultraviolet absorber (UV absorber) were obtained. Hereinafter, the resin composition obtained in Reference Example 1 may be referred to as a resin composition (P-1-0). The stress optical coefficient Cr of the resin composition (P-1-0) was −3 × 10 ⁻⁹ Pa ⁻¹ , and had negative orientation birefringence. In addition, the resin composition (P-1-0) was hot-pressed at 250 ° C. to form an unstretched film having a thickness of 160 μm, and a sequential biaxial stretching machine (X-6S, manufactured by Toyo Seiki Seisaku-sho, Ltd.) And stretched at a temperature of Tg + 24 ° C. to obtain a stretched film of 40 μm. Re of the stretched film was 0.4 nm, and Rth was -1.5 nm. That is, it was confirmed that in the resin composition (P-1), the matrix resin containing no graft copolymer bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain had negative orientation birefringence.

<Reference Example 2>
Same as Example 2 except that the first SEBS triblock copolymer and the second SEBS triblock copolymer were not added to a reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction pipe. According to the method, pellets comprising a resin composition containing a lactone ring-based polymer having a lactone ring structure in the main chain were obtained. Hereinafter, the resin composition obtained in Reference Example 2 may be referred to as a resin composition (P-2-0). The stress optical coefficient Cr of the resin composition (P-2-0) was −5 × 10 ⁻⁹ Pa ⁻¹ and had negative orientation birefringence. In addition, the resin composition (P-2-0) was hot-pressed at 250 ° C. to form an unstretched film having a thickness of 160 μm, and a sequential biaxial stretching machine (X-6S, manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used. And stretched at a temperature of Tg + 24 ° C. to obtain a stretched film of 40 μm. Re of the stretched film was 0.6 nm, and Rth was -2.5 nm. That is, it was confirmed that in the resin composition (P-2), the matrix resin not containing the graft copolymer bonded to the diene / olefin-derived unit of the SEBS triblock copolymer chain had negative orientation birefringence.

<Reference Example 3>
Polymerization from MMA, PMI and St in the same manner as in Example 1 except that the third SEBS triblock copolymer was not added to a reactor equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen inlet pipe. A pellet composed of the formed (meth) acrylic copolymer was obtained. Hereinafter, the resin composition obtained in Reference Example 3 may be referred to as a resin composition (P-3-0). The stress optical coefficient Cr of the resin composition (P-3-0) was −22 × 10 ⁻⁹ Pa ⁻¹ and had negative orientation birefringence. The resin composition (P-3-0) was hot-pressed at 250 ° C. to form a 160 μm-thick unstretched film, and a sequential biaxial stretching machine (manufactured by Toyo Seiki Seisaku-sho, Ltd., X-6S) was used. And stretched at a temperature of Tg + 24 ° C. to obtain a stretched film of 40 μm. Re of the stretched film was 2.0 nm, and Rth was -11.1 nm. That is, it was confirmed that in the resin composition (P-3), the matrix resin containing no graft copolymer bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain had negative orientation birefringence.

<Reference example 4>
A fourth SEBS triblock copolymer (manufactured by Kraton, G1652, olefinic double bond amount 0.10 mmol / g, styrene unit content 25.9% by mass, refractive index 1.510, weight average molecular weight) is placed in a pressure-resistant tube. 80,000, number average molecular weight 68,000), 79.2 parts of methyl methacrylate (MMA), 10.8 parts of styrene (St), 0.1 part of n-dodecyl mercaptan (nDM), initiator 0.5 parts of t-butyl peroxyisopropyl carbonate (manufactured by Kayaku Akzo Co., Ltd., Kayacaron (registered trademark) Bic75) and 100 parts of toluene as a polymerization solvent were charged, and nitrogen was sealed therein. The reaction was performed in an oil bath at 115 ° C. for 6 hours. The conversion of MMA calculated from the amount of residual monomers in the polymerization solution was 76%, and the conversion of St was 98%. The composition ratio (by mass) of the (meth) acrylic copolymer chain and the (meth) acrylic copolymer bonded to the SEBS triblock copolymer chain calculated from the conversion rate is MMA: St = 85. 0.0: 15.0, the obtained polymerization solution was diluted with chloroform, and the resulting polymer was precipitated by dropwise addition into methanol. Thereafter, suction filtration is performed, and the resultant is dried in a vacuum drier at 100 ° C. for 1 hour, and then dried in a vacuum drier at 240 ° C. for 1 hour to remove unreacted monomers to thereby obtain an acrylic having no ring structure in the main chain. A resin composition (P-5) containing a copolymer and a graft copolymer in which the copolymer chain is bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain was obtained.
The weight average molecular weight of the obtained resin composition (P-5) is 135,000, the number average molecular weight is 61,000, the glass transition temperature on the high temperature side is 114 ° C, and the glass transition temperature on the low temperature side is -54 ° C. And the refractive index was 1.505. The size of the sea-island structure when the obtained polymer composition was formed into a press film was confirmed to be 190 nm, and it was determined that the polymer composition had a phase-separated structure as in Example 1. The breaking energy was 40 mJ or more. The film of the resin composition (P-5) was stretched at a temperature of Tg + 24 ° C. to obtain a stretched film of 40 μm. The number of MITs in the stretched film was 3000 times or more, and had a strong strength. The internal haze of the stretched film having a thickness of 40 μm was 0.08% (0.20% per 100 μm thickness). The stretched film having a thickness of 40 μm had Re of 0.4 nm and Rth of −15.5 nm, and was a negative retardation film. As shown in the results of Reference Example 5 described later, when the orientation birefringence of the matrix resin is too large, the morphological complexation caused by the island structure composed of the graft copolymer bonded to the diene / olefin-derived unit of the SEBS triblock copolymer chain. It is considered that it is difficult to cancel negative alignment birefringence by refraction to obtain a low retardation film.

<Reference Example 5>
Pellets made of the resin composition were obtained in the same manner as in Reference Example 4, except that the fourth SEBS triblock copolymer was not added to the pressure-resistant tube. Hereinafter, the resin composition obtained in Reference Example 5 may be referred to as a resin composition (P-5-0). The stress optical coefficient Cr of the resin composition (P-5-0) was -70 × 10 ⁻⁹ Pa ⁻¹ , and had a large negative orientation birefringence. In addition, the resin composition (P-5-0) was hot-pressed at 250 ° C. to form an unstretched film having a thickness of 160 μm, and a sequential biaxial stretching machine (X-6S, manufactured by Toyo Seiki Seisaku-sho, Ltd.) was used. And stretched at a temperature of Tg + 24 ° C. to obtain a stretched film of 40 μm. Re of the stretched film was 4.9 nm, and Rth was −35.5 nm. That is, it was confirmed that in the resin composition (P-5), the matrix resin containing no graft copolymer bonded to a diene / olefin-derived unit of the SEBS triblock copolymer chain had a large negative orientation birefringence.

Claims (10)

  A film in which a phase separation portion is formed in a matrix, having a positive form birefringence based on the phase separation structure, a negative orientation birefringence is introduced into the matrix, and the form birefringence and the orientation birefringence are Films canceling each other. A film in which a phase-separated structure is formed in a matrix and the matrix contains a resin (R) having negative orientation birefringence,
A film, wherein the in-plane retardation Re of the film with respect to light having a wavelength of 589 nm is 10 nm or less, and the retardation Rth in the thickness direction with respect to light having a wavelength of 589 nm is -10 to 10 nm. The film according to claim 2, wherein the stress optical coefficient Cr of the resin (R) is −30.0 × 10 ⁻⁹ Pa ⁻¹ or more and −0.1 × 10 ⁻⁹ Pa ⁻¹ or less.   The film according to claim 2, wherein the resin (R) contains a (meth) acrylic polymer (Q).   The film according to any one of claims 1 to 4, wherein the film includes a polymer chain having a polymer block (a1) having a unit derived from a diene and / or an olefin.   The film is a copolymer having a polymer chain (A) having a polymer block (a1) having a unit derived from a diene and / or olefin and a polymer block (a2) having a unit derived from an aromatic vinyl monomer. The film according to claim 1, comprising:   The film according to claim 6, wherein the polymer chain (A) is contained in the film in an amount of 0.1 to 20% by mass.   The film according to claim 1, having a glass transition temperature of 115 ° C. or higher.   The film according to any one of claims 1 to 8, wherein the internal haze is 1.0% or less. The film according to any one of claims 1 to 9, wherein the film is a biaxially stretched film having a thickness of 60 µm or less.