JP2015123618A - Method for producing optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a film free from the unevenness of a phase difference causing deterioration in the quality of the film upon production of an optical film made of a thermoplastic resin composition comprising a rubber-containing copolymer by a melt extrusion method.SOLUTION: Provided is a method for producing an optical film made of a resin composition including a thermoplastic resin and a rubber-containing polymer, including: a step of extruding the resin composition into the shape of a sheet from a T die; and a step of holding the sheet-shaped resin composition with a roll 3 and/or a belt, in which orientation birefringence lies in the range from -2.0×10to 2.0×10.

Description

  The present invention relates to a method for producing an optical film based on a melt extrusion method, and an optical film produced by the production method.

In recent years, along with the downsizing, thinning, and weight reduction of notebook computers, word processors, mobile phones, personal digital assistants, etc., liquid crystal display devices that take advantage of the light weight and compactness of these electronic devices have come to be widely used. It is coming. In the liquid crystal display device, various films such as a polarizing film are used in order to maintain the display quality. In order to further reduce the weight of liquid crystal display devices for portable information terminals and mobile phones, liquid crystal display devices using resin films instead of glass substrates have been put into practical use.

For plastic films used in devices that handle polarized light, such as liquid crystal display devices,
Optical transparency and optical homogeneity are required. For this reason, a polarizer protective film for protecting a polarizer and an optical film typified by a film substrate for a liquid crystal display device are required to have a small phase difference expressed by the product of birefringence and thickness. Is done.

  Acrylic resin films have excellent optical transparency and have recently been developed in the field of optical films, but have the disadvantage of low film strength and toughness and low film formability and transportability. Regarding the transportability when it is formed into a film, a method is known in which a rubber-containing copolymer is added to the resin component to improve the strength. However, it has been difficult to produce a high-quality optical film containing the rubber-containing copolymer due to fine aggregates and the like generated in the production process of the rubber-containing copolymer. In the manufacturing method by melt extrusion film formation of an optical film that requires a low foreign matter level, it is common to perform filtration with a filter at the stage of pelletization and / or film formation (Patent Documents 1 and 2). The supplement of aggregates derived from the containing copolymer was not always sufficient.

JP2012-149268 JP2007-254727

In the melt filtration step that can be placed in the melt extrusion film-forming of the thermoplastic resin composition containing the rubber-containing copolymer, inorganic substances such as dust and dust that are externally mixed foreign matter can be captured to some extent, but the rubber-containing copolymer Fine aggregates produced in the manufacturing process, and undispersed and re-agglomerated rubber-containing copolymers in the pelletizing or filming process are melted in the same manner as the resin and cannot be captured by the filter, and are projected on the film surface. It is detected as a foreign object. On the other hand, as for the surface property of the thermoplastic resin composition film, a method of obtaining a film having good surface property by extruding the thermoplastic resin composition into a sheet form from a T-die and sandwiching it with a roll is known. . However, in the case of a film made of a thermoplastic resin composition containing a rubber-containing copolymer, if the protrusions on the film surface due to the above-mentioned fine aggregates are sandwiched between rolls, the resin in that part is oriented. It has been found.
When this oriented portion is observed in a crossed Nicol state, the oriented portion is confirmed as a fine contrast between light and darkness, and unevenness occurs in the phase difference in the film, thereby impairing the properties as an optical film.

  The present invention provides a method for producing a film free from retardation unevenness that causes deterioration in film quality when producing an optical film comprising a thermoplastic resin composition containing a rubber-containing copolymer by a melt extrusion method. With the goal.

In order to solve the above-described problems of the prior art, the present invention has studied a manufacturing method. As a result, a resin composition containing a thermoplastic resin having an orientation birefringence of -2.0 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ when formed into a film and a rubber-containing copolymer is a T-die. It has been found that a film having no phase difference unevenness can be obtained by extruding the sheet into a sheet and then pinching with a roll and a belt, and the present invention has been completed.

That is, the present invention is a method for producing an optical film comprising a resin composition containing a thermoplastic resin and a rubber-containing copolymer, the step of extruding the resin composition in a sheet form from a T-die, and a sheet A method for producing an optical film having an orientation birefringence of −2.0 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ (hereinafter, “having a step of sandwiching the resin composition in a shape with a roll and / or a belt” It may be referred to as “the manufacturing method of the present invention”).

  In the production method of the present invention, the surface of the roll and / or belt is preferably a mirror surface.

  In the manufacturing method of this invention, it is preferable to have the process of filtering the said resin composition fuse | melted with the polymer filter.

  In the production method of the present invention, the orientation birefringence of the thermoplastic resin and the rubber-containing copolymer may be different.

In the production method of the present invention, the orientation birefringence between the thermoplastic resin and the rubber-containing copolymer may be -2.0 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ .

  In the production method of the present invention, the rubber-containing polymer includes a (meth) acrylic crosslinked polymer layer and a vinyl monomer having an alicyclic structure, a heterocyclic structure or an aromatic group as a structural unit. It is preferable to have a hard polymer layer.

  In the manufacturing method of this invention, it is preferable that the said rubber-containing polymer has a hard polymer layer which contains the monomer represented by following formula (4) in a structural unit.

(In the above formula (4), R ⁹ represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms. R ¹⁰ represents a substituted or unsubstituted carbon. An aromatic group having 1 to 24 carbon atoms, or a substituted or unsubstituted alicyclic group having 1 to 24 carbon atoms, having a monocyclic structure or a heterocyclic structure, wherein l is an integer of 1 to 4; M represents an integer of 0 to 1. n represents an integer of 0 to 10.)
In the production method of the present invention, the rubber-containing copolymer is at least one selected from the group consisting of benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and phenoxyethyl (meth) acrylate. It is preferable to have a hard polymer layer containing in a structural unit.

  In the production method of the present invention, the thermoplastic resin is preferably an acrylic thermoplastic resin.

  In the production method of the present invention, the thermoplastic resin is obtained by polymerizing maleimide acrylic resin, glutarimide acrylic resin, lactone ring-containing acrylic polymer, styrene monomer and other monomers copolymerizable therewith. A partially hydrogenated styrene polymer obtained by partial hydrogenation of the aromatic ring of the styrene polymer obtained, an acrylic polymer containing a cyclic acid anhydride repeating unit, and a hydroxyl group and a carboxyl group It is preferable to include at least one selected from the group consisting of acrylic polymers.

  In the production method of the present invention, the thermoplastic resin preferably includes a glutarimide acrylic resin having a unit represented by the following general formula (1) and a unit represented by the following general formula (2). .

(In the formula, R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 3 to 12 carbon atoms. A cycloalkyl group or a substituent of 5 to 15 carbon atoms containing an aromatic ring.)

(In the formula, R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent having 5 to 15 carbon atoms including an aromatic ring.)

  According to the method for producing an optical film of the present invention, it is possible to provide a method for producing an optical film with few film surface defects and no retardation unevenness.

The schematic diagram of the pinching shaping | molding process in the manufacturing method of the optical film of this invention.

  Hereinafter, although embodiment of this invention is described in detail, this invention is not limited to these embodiment.

  In the production method of the present invention, a resin composition containing a thermoplastic resin and a rubber-containing copolymer is melt-extruded.

(Thermoplastic resin)
In the present invention, the thermoplastic resin can be any resin that is generally transparent. Specifically, polycarbonate resin represented by bisphenol A polycarbonate, polystyrene, styrene-acrylonitrile copolymer, styrene-maleic anhydride resin, styrene-maleimide resin, styrene- (meth) acrylic acid resin, styrene-based thermoplastic elastomer Aromatic vinyl resins and their hydrogenated products, amorphous polyolefins, transparent polyolefins with a refined crystal phase, polyolefin resins such as ethylene-methyl methacrylate resin, polymethyl methacrylate, styrene-methyl methacrylate Acrylic resins such as resins, heat-resistant acrylic resins modified by imide cyclization, lactone cyclization, methacrylic acid modification, etc., polyethylene terephthalate, polycyclohexane dimethylene group, polyphthalene partially modified with isophthalic acid, etc. Amorphous polyester resin such as tylene terephthalate, polyethylene naphthalate, polyarylate, or transparent polyester resin with a refined crystal phase, polyimide resin, polyethersulfone resin, polyamide resin, cellulose resin such as triacetyl cellulose resin, A wide variety of thermoplastic resins having transparency, such as polyphenylene oxide resins, are exemplified. In consideration of actual use, it is preferable to select a resin so that the total light transmittance of the obtained molded body is 85% or more, preferably 90%, more preferably 92% or more.

  Among the above resins, acrylic resins are particularly preferable in terms of excellent optical properties, heat resistance, moldability, and the like. The acrylic resin may be a resin formed by polymerizing a vinyl monomer containing a (meth) acrylic acid alkyl ester, but methyl methacrylate 30 to 100% by weight and a monomer 70 to 0 copolymerizable therewith An acrylic resin obtained by polymerizing wt% is more preferable.

  As another vinyl monomer copolymerizable with methyl methacrylate, for example, a (meth) acrylic acid ester having 1 to 10 carbon atoms of an alkyl residue (excluding methyl methacrylate) is preferable. Specific examples of other vinyl monomers copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, glycidyl methacrylate, epoxy cyclohexyl methyl methacrylate, methacrylic acid. Methacrylic acid esters such as 2-hydroxyethyl acid, 2-hydroxypropyl methacrylate, dicyclopentanyl methacrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,2-trichloroethyl methacrylate, isobornyl methacrylate Methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, epoxycyclohexylmethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy acrylate Acrylic acid esters such as roxypropyl; Carboxylic acids such as methacrylic acid and acrylic acid and esters thereof; Vinyl cyanes such as acrylonitrile and methacrylonitrile; Vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene Maleic acid, fumaric acid and esters thereof; vinyl halides such as vinyl chloride, vinyl bromide and chloroprene; vinyl acetate; alkenes such as ethylene, propylene, butylene, butadiene and isobutylene: halogenated alkenes; Allyl methacrylate, diallyl phthalate, triallyl cyanurate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, divinyl A polyfunctional monomer such as benzene may be mentioned. These vinyl monomers can be used alone or in combination of two or more.

  In the methyl methacrylate polymer, methyl methacrylate is contained in an amount of 30 to 100% by weight, preferably 50 to 99.9% by weight, more preferably 50 to 98% by weight. The monomer copolymerizable with methyl methacrylate is It is contained in an amount of 70 to 0% by weight, preferably 50 to 0.1% by weight, more preferably 50 to 2% by weight. If the content of methyl methacrylate is less than 30% by weight, the optical characteristics, appearance, weather resistance, and heat resistance unique to acrylic resins tend to be lowered. Moreover, it is desirable not to use a polyfunctional monomer from the viewpoint of processability and appearance.

  The glass transition temperature of the thermoplastic resin used in the present invention can be set according to the conditions and applications to be used. The glass transition temperature is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, further preferably 115 ° C. or higher, and most preferably 120 ° C. or higher.

  Specific examples of acrylic resins having a glass transition temperature of 120 ° C. or higher include acrylic resins containing glutarimide structures, glutaric anhydride structures, (meth) acrylic acid units, or lactone rings in the molecule, and N-substituted maleimides. An acrylic resin in which the compound is copolymerized is exemplified. For example, maleimide acrylic resin, polyglutarimide acrylic resin, glutaric anhydride acrylic resin, lactone cyclized acrylic resin, acrylic resin containing hydroxyl group and / or carboxyl group, methacrylic resin, styrene monomer and A partially hydrogenated styrene polymer obtained by partially hydrogenating the aromatic ring of a styrene polymer obtained by polymerizing another monomer copolymerizable therewith, and an acrylic containing cyclic acid anhydride repeating units System polymers and the like. As other resins having a glass transition temperature of 120 ° C. or higher, polyethylene terephthalate resin, polybutylene terephthalate resin, or the like can be used. In particular, when an acrylic resin or glutarimide acrylic resin in which an N-substituted maleimide compound is copolymerized is used, the heat resistance of the resulting film is improved, and the optical properties during stretching are particularly excellent. preferable. An acrylic resin and a glutarimide acrylic resin in which an N-substituted maleimide compound is copolymerized may be used in combination. The compatibility is high, the excellent transparency of each resin can be maintained, the optical isotropy is excellent, and the high thermal stability and solvent resistance can be maintained.

(Glutarimide acrylic resin)
The glutarimide acrylic resin has a glass transition temperature of 120 ° C. or higher, and includes a unit represented by the following general formula (1) and a unit represented by the following general formula (2).

In the general formula (1), R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or a carbon number. It is a C3-C15 cycloalkyl group or a C5-C15 substituent containing an aromatic ring. Hereinafter, the unit represented by the general formula (1) is also referred to as “glutarimide unit”.

In the general formula (1), preferably, R ¹ and R ² are each independently hydrogen or a methyl group, and R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group, and more preferably, R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

The glutarimide acrylic resin may contain only a single type as a glutarimide unit, or a plurality of different ones or all of R ¹ , R ² , and R ^{3 in} the general formula (1). The type may be included.

  The glutarimide unit can be formed by imidizing a (meth) acrylic acid ester unit represented by the following general formula (2). Further, an acid anhydride such as maleic anhydride, a half ester of the acid anhydride and a linear or branched alcohol having 1 to 20 carbon atoms, or an α, β-ethylenically unsaturated carboxylic acid (for example, acrylic acid) The glutarimide unit can also be formed by imidizing methacrylic acid, maleic acid, itaconic acid, crotonic acid, fumaric acid, citraconic acid).

In the glutarimide acrylic resin, the content of the glutarimide unit is not particularly limited, and can be appropriately determined in consideration of, for example, the structure of R ³ . However, the content of the glutarimide unit is preferably 1.0% by weight or more, more preferably 3.0% by weight to 90% by weight, and more preferably 5.0% by weight to 60% by weight in the total amount of the glutarimide acrylic resin. Further preferred. When the content of the glutarimide unit is less than the above range, the resulting glutarimide acrylic resin tends to have insufficient heat resistance or its transparency may be impaired. On the other hand, if it exceeds the above range, the heat resistance and melt viscosity will be unnecessarily high, the molding processability will be poor, the mechanical strength during film processing will be extremely low, and the transparency will be impaired. Tend.

  The content of the glutarimide unit is calculated by the following method.

^{Using 1} H-NMR BRUKER Avance III (400 MHz), ¹ H-NMR measurement of the resin is performed to determine the content (mol%) of each monomer unit such as glutarimide unit or ester unit in the resin, and the content The amount (mol%) is converted to the content (% by weight) using the molecular weight of each monomer unit.

For example, in the case of a resin comprising a glutarimide unit in which R ³ is a methyl group in the above general formula (1) and a methyl methacrylate unit, it is derived from the O-CH ₃ proton of methyl methacrylate appearing in the vicinity of 3.5 to 3.8 ppm. From the peak area a and the peak area b derived from the N—CH ₃ proton of glutarimide that appears in the vicinity of 3.0 to 3.3 ppm, the content (% by weight) of the glutarimide unit is obtained by the following formula. Can do.
[Methyl methacrylate unit content A (mol%)] = 100 × a / (a + b)
[Content B (glut%) of glutarimide unit] = 100 × b / (a + b)
[Content of glutarimide unit (% by weight)] = 100 × (b × (molecular weight of glutarimide unit)) / (a × (molecular weight of methyl methacrylate unit) + b × (molecular weight of glutarimide unit))
In addition, also when a unit other than the above is included as a monomer unit, content (weight%) of a glutarimide unit can be calculated | required similarly from content (mol%) and molecular weight of each monomer unit in resin.

  When the thermoplastic resin of the present invention is used, for example, in a polarizer protective film, the content of glutarimide units is preferably 20% by weight or less, more preferably 15% by weight or less, and more preferably 10% by weight because it is easy to suppress birefringence. The following is more preferable.

In the general formula (2), R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or 3 to 3 carbon atoms. 12 cycloalkyl groups or substituents having 5 to 15 carbon atoms including an aromatic ring. Hereinafter, the unit represented by the general formula (2) is also referred to as “(meth) acrylic acid ester unit”. In the present application, “(meth) acryl” refers to “methacryl or acrylic”.

In the general formula (2), preferably, R ⁴ and R ⁵ are each independently hydrogen or a methyl group, R ⁶ is hydrogen or a methyl group, and more preferably R ⁴ is hydrogen, ⁵ is a methyl group, and R ⁶ is a methyl group.

The glutarimide acrylic resin may contain only a single type as a (meth) acrylic acid ester unit, or any or all of R ⁴ , R ⁵ and R ⁶ in the above general formula (2) A plurality of different types may be included.

  The glutarimide acrylic resin may further contain a unit represented by the following general formula (3) (hereinafter also referred to as “aromatic vinyl unit”) as necessary.

In the general formula (3), R ⁷ is hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁸ is an aryl group having 6 to 10 carbon atoms.

  Although it does not specifically limit as an aromatic vinyl unit represented by the said General formula (3), A styrene unit and an alpha-methylstyrene unit are mentioned, A styrene unit is preferable.

The glutarimide acrylic resin may contain only a single type as an aromatic vinyl unit, or may contain a plurality of units in which either or both of R ⁷ and R ⁸ are different.

  In the glutarimide acrylic resin, the content of the aromatic vinyl unit is not particularly limited, but is preferably 0 to 50% by weight, more preferably 0 to 20% by weight, and more preferably 0 to 15% by weight of the total amount of the glutarimide acrylic resin. Is particularly preferred. When the content of the aromatic vinyl unit is larger than the above range, sufficient heat resistance of the glutarimide acrylic resin cannot be obtained.

  However, in the present invention, it is preferable that the glutarimide acrylic resin does not contain an aromatic vinyl unit from the viewpoints of improvement of bending resistance and transparency, reduction of fish eyes, and improvement of solvent resistance or weather resistance.

  The glutarimide acrylic resin may further contain other units other than the glutarimide unit, the (meth) acrylic acid ester unit, and the aromatic vinyl unit, if necessary.

  Examples of other units include amide units such as acrylamide and methacrylamide, glutaric anhydride units, nitrile units such as acrylonitrile and methacrylonitrile, maleimide, N-methylmaleimide, N-phenylmaleimide, and N-cyclohexylmaleimide. And maleimide-based units.

  These other units may be contained in the glutarimide acrylic resin by random copolymerization or may be contained by graft copolymerization.

  These other units were introduced by copolymerizing the monomers constituting the units with glutarimide acrylic resins and / or resins used as raw materials for producing glutarimide acrylic resins. It may be a thing. Further, when the imidization reaction is performed, these other units may be by-produced and included in the glutarimide acrylic resin.

Although the weight average molecular weight of glutarimide acrylic resin is not specifically limited, It is preferable to exist in the range of 1 * 10 < ⁴ > -5 * 10 < ⁵ >. If it is in the said range, moldability will not fall or the mechanical strength at the time of film processing will not be insufficient. On the other hand, when the weight average molecular weight is smaller than the above range, the mechanical strength when formed into a film tends to be insufficient. Moreover, when larger than the said range, the viscosity at the time of melt-extrusion is high, there exists a tendency for the moldability to fall and the productivity of a molded article to fall.

  The glass transition temperature of the glutarimide acrylic resin is preferably 120 ° C. or higher so that the film exhibits good heat resistance. More preferably, it is 125 ° C. or higher. If the glass transition temperature is lower than the above range, the film cannot exhibit sufficient heat resistance.

  Next, an example of a method for producing a glutarimide acrylic resin will be described.

  First, a (meth) acrylic acid ester polymer is produced by polymerizing a (meth) acrylic acid ester. When the glutarimide acrylic resin contains an aromatic vinyl unit, a (meth) acrylic acid ester and an aromatic vinyl are copolymerized to produce a (meth) acrylic acid ester-aromatic vinyl copolymer.

  In this step, examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic acid t. -Butyl, benzyl (meth) acrylate, and cyclohexyl (meth) acrylate are preferably used, and methyl methacrylate is more preferably used.

  (Meth) acrylic acid esters may be used alone or in combination of two or more. By using multiple types of (meth) acrylic acid esters, it is possible to include multiple types of (meth) acrylic acid ester units in the finally obtained glutarimide acrylic resin.

  The structure of the (meth) acrylic acid ester polymer or the (meth) acrylic acid ester-aromatic vinyl copolymer is not particularly limited as long as the subsequent imidization reaction is possible. Specific examples include linear polymers, block polymers, core-shell polymers, branched polymers, ladder polymers, and crosslinked polymers.

  In the case of a block polymer, it may be any of AB type, ABC type, ABA type, and other types of block polymers. In the case of the core-shell polymer, it may be composed of only one core and one shell, or one or both of the core and shell may be composed of multiple layers.

  Next, an imidation reaction is performed by reacting the (meth) acrylic acid ester polymer or the (meth) acrylic acid ester-aromatic vinyl copolymer with an imidizing agent. Thereby, glutarimide acrylic resin can be manufactured.

  The imidizing agent is not particularly limited as long as the glutarimide unit represented by the general formula (1) can be generated. Specifically, ammonia or a primary amine can be used. Examples of the primary amine include aliphatic hydrocarbon group-containing primary amines such as methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine, and n-hexylamine; Examples include aromatic hydrocarbon group-containing primary amines such as aniline, benzylamine, toluidine, and trichloroaniline, and alicyclic hydrocarbon group-containing primary amines such as cyclohexylamine.

  As the imidizing agent, urea compounds that generate ammonia or primary amines by heating, such as urea, 1,3-dimethylurea, 1,3-diethylurea, 1,3-dipropylurea, can also be used.

  Among the imidizing agents, ammonia, methylamine, and cyclohexylamine are preferably used, and methylamine is particularly preferably used from the viewpoints of cost and physical properties.

  In this imidization step, a ring closure accelerator may be added as necessary in addition to the imidizing agent.

  In this imidization step, the content of glutarimide units in the resulting glutarimide acrylic resin can be adjusted by adjusting the ratio of the imidizing agent added.

  The method for carrying out the imidization reaction is not particularly limited, and a conventionally known method can be used. For example, the imidization reaction can be advanced by using an extruder or a batch type reaction vessel (pressure vessel).

  Although it does not specifically limit as said extruder, Various extruders can be used, For example, a single screw extruder, a twin screw extruder, a multi screw extruder, etc. can be used.

  Among these, it is preferable to use a twin screw extruder. According to the twin screw extruder, mixing of the raw material polymer and the imidizing agent (in the case of using a ring closure accelerator, an imidizing agent and a ring closure accelerator) can be promoted.

  Examples of the twin-screw extruder include a non-meshing type same direction rotating type, a meshing type same direction rotating type, a non-meshing type different direction rotating type, and a meshing type different direction rotating type. Among these, the meshing type co-rotating type is preferable. Since the meshing type co-rotating twin-screw extruder can rotate at a high speed, the mixing of the raw material polymer with the imidizing agent (in the case of using a ring closure accelerator, an imidizing agent and a ring closure accelerator) It can be further promoted.

  The above-exemplified extruders may be used alone, or a plurality of the extruders may be connected in series.

  In producing a glutarimide acrylic resin, in addition to the imidization step, an esterification step of treating with an esterifying agent can be included. By this esterification step, the carboxyl group contained in the resin, which is by-produced in the imidization step, can be converted into an ester group. Thereby, the acid value of glutarimide acrylic resin can be adjusted in a desired range.

  The acid value of the glutarimide acrylic resin is not particularly limited, but is preferably 0.50 mmol / g or less, and more preferably 0.45 mmol / g or less. Although a minimum in particular is not restrict | limited, 0 mmol / g or more is preferable, 0.05 mmol / g or more is preferable and 0.10 mmol / g or more is especially preferable. If the acid value is within the above range, a glutarimide acrylic resin having an excellent balance of heat resistance, mechanical properties, and moldability can be obtained. On the other hand, when the acid value is larger than the above range, foaming of the resin is likely to occur during melt extrusion for film forming, the moldability tends to be lowered, and the productivity of the molded product tends to be lowered. The acid value can be calculated by, for example, a titration method described in JP-A-2005-23272.

  The esterifying agent is not particularly limited. For example, dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, Methyl trifluoromethyl sulfonate, methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-t-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, Tetra-N-butoxysilane, dimethyl (trimethylsilane) phosphite, trim Le phosphite, trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and benzyl glycidyl ether. Among these, dimethyl carbonate and trimethyl orthoacetate are preferable from the viewpoint of cost and reactivity, and dimethyl carbonate is particularly preferable from the viewpoint of cost.

  Although the usage-amount of the said esterifying agent is not specifically limited, It is 0-12 weight part with respect to 100 weight part of the said (meth) acrylic acid ester polymer or the said (meth) acrylic acid ester-aromatic vinyl copolymer. It is preferably 0 to 8 parts by weight. If the amount of the esterifying agent used is within the above range, the acid value of the glutarimide acrylic resin can be adjusted to an appropriate range. On the other hand, outside the above range, unreacted esterifying agent may remain in the resin, which may cause foaming or odor generation when molding is performed using the resin.

  In addition to the esterifying agent, a catalyst may be used in combination. The type of the catalyst is not particularly limited, and examples thereof include aliphatic tertiary amines such as trimethylamine, triethylamine, and tributylamine. Among these, triethylamine is preferable from the viewpoint of cost and reactivity.

  An esterification process can be advanced by using an extruder or a batch-type reaction tank similarly to the said imidation process, for example.

  This esterification step can be carried out only by heat treatment without using an esterifying agent. The heat treatment can be achieved by kneading and dispersing the molten resin in the extruder. When only the heat treatment is performed as the esterification step, dehydration reaction between the carboxyl groups in the resin by-produced in the imidization step and / or dealcoholization reaction between the carboxyl group in the resin and the alkyl ester group in the resin For example, part or all of the carboxyl group can be converted to an acid anhydride group. At this time, it is also possible to use a ring closure accelerator (catalyst).

  In the esterification step using an esterifying agent, acid anhydride grouping by heat treatment can be advanced in parallel.

  In both the imidization step and the esterification step, it is preferable to attach a vent port that can be depressurized to atmospheric pressure or less to the extruder to be used. According to such a machine, unreacted imidizing agent, esterifying agent, by-products such as methanol, or monomers can be removed.

  For the production of glutarimide acrylic resin, instead of an extruder, for example, a horizontal biaxial reactor such as Violac manufactured by Sumitomo Heavy Industries, Ltd., a vertical biaxial agitation tank such as Super Blend, etc. A high-viscosity reactor can also be suitably used.

  When manufacturing glutarimide acrylic resin using a batch type reaction vessel (pressure vessel), the structure of the batch type reaction vessel (pressure vessel) is not particularly limited. Specifically, it has a structure in which the raw material polymer can be melted by heating and stirred, and an imidizing agent (in the case of using a ring closure accelerator, an imidizing agent and a ring closure accelerator) can be added. However, it is preferable to have a structure with good stirring efficiency. According to such a batch-type reaction vessel, it is possible to prevent the polymer viscosity from increasing due to the progress of the reaction and insufficient stirring. As a batch type reaction tank having such a structure, for example, a stirred tank max blend manufactured by Sumitomo Heavy Industries, Ltd. and the like can be mentioned.

  As described above, a glutarimide acrylic resin in which the content of glutarimide units is controlled to a specific value can be easily produced.

(Resin composition)
When a film is produced by ordinary melt extrusion molding other than molding in which the polymer is oriented in the film, such as high discharge conditions, film take-up conditions, and low temperature molding, the orientation of the polymer in the film is not so large. Actually, if it is an acrylic resin typified by PMMA, the birefringence of a melt-extruded film (hereinafter also referred to as a raw film or a raw material film) that does not have an intentional stretching process is not so large, and it depends on the application, but it is practical. There may be no problem. Of course, under molding conditions in which the polymer is oriented, the polymer is oriented in the film, resulting in birefringence. The birefringence in this case is generally called birefringence because it is birefringence generated by the orientation of the polymer.

The method of the present invention, a resin composition orientation birefringence gives a film which is in the range of ^{-2.0 × 10 -4 ~2.0 × 10 -4} .

The resin composition may be formed by blending a thermoplastic resin and a rubber-containing copolymer so that the orientation birefringence falls within the above range, and if necessary, the orientation birefringence of the rubber-containing copolymer and / or the thermoplastic resin. The orientation birefringence of the above may be set. When the orientation birefringence of the thermoplastic resin is large, the orientation birefringence of the rubber-containing copolymer can be made different from the orientation birefringence of the thermoplastic resin by reducing the orientation birefringence. The compounding amount of the rubber-containing copolymer may be such that the rubber-containing copolymer is added in an amount that can cancel the orientation birefringence of the thermoplastic resin. Preferably, the orientation birefringence is obtained by blending a thermoplastic resin and a rubber-containing copolymer both having an orientation birefringence in the range of −2.0 × 10 ^{−4 to} 2.0 × 10 ^−4. May be adjusted within a range of −2.0 × 10 ^{−4 to} 2.0 × 10 ⁻⁴ .

  Here, we would like to define the measurement conditions of “orientation birefringence” as referred to in the present invention. As described above, the orientation birefringence is a birefringence expressed by the orientation of the polymer chain, but the birefringence (orientation birefringence) in the polymer film varies depending on the degree of orientation of the polymer chain. Therefore, in the present invention, the “alignment birefringence” is defined as measurement under the following conditions.

  The thermoplastic resin and the rubber-containing copolymer need to be formed into some form, and the orientation birefringence needs to be measured. In the present invention, the form is a film or a sheet. Here, a melt-extruded film and a press-formed sheet will be described.

・ Measurement of “Oriented Birefringence” in Film First, cut out a 25 mm × 90 mm test piece from a 125 μm-thick film (raw film) (cut so that the long side comes in the MD direction), and hold both short sides. Then, the glass transition temperature is kept at + 30 ° C. for 2 minutes, and the film is stretched uniaxially at a speed of 200 mm / min in the length direction (also referred to as stretching to 100%) (in this case, both long sides are not fixed). Thereafter, the obtained film is cooled to 23 ° C., the center portion of the sample is sampled, and birefringence is measured.

  Since the above “orientation birefringence” depends on the degree of orientation of the polymer and is affected by various sample preparation conditions including the stretching conditions, the evaluation conditions are specified as described above. For example, the stretching temperature is preferably −30 ° C. to + 30 ° C. or + 0 ° C. to + 30 ° C. with respect to the glass transition temperature, and may be set as appropriate, for example, within the temperature range of + 5 ° C. to + 30 ° C. However, in order to quantitatively obtain the birefringence sign and the relative magnitude relationship between the samples, it is important to use measurement values at the same measurement conditions such as the stretching conditions.

  As described above, in the optical film obtained by the production method of the present invention, the degree of orientation of the polymer in the molded body is not so large, and the orientation birefringence of the molded body has no practical problem. There is no particular need to consider orientation birefringence in the design of the coalescence. On the other hand, when the orientation birefringence in the obtained optical film becomes a problem in practice, the orientation birefringence of the rubber-containing copolymer may be different from the orientation birefringence of the thermoplastic resin.

(Rubber-containing copolymer)
The rubber-containing copolymer contained in the resin composition of the present invention can be reduced in orientation birefringence and added to a resin material having high optical isotropy, if necessary, by adding to a thermoplastic resin. It can also be made to act as a component.

  The rubber-containing copolymer used in the present invention may be a polymer having a weight average molecular weight exceeding 5000, preferably 10,000 or more, more preferably 20000 or more. When the weight average molecular weight is 5000 or less, physical properties such as mechanical properties, heat resistance, and hardness of the molded body may be deteriorated, or the surface of the molded body may be bleed out during high-temperature molding and the appearance of the molded body may be impaired.

  The rubber-containing copolymer preferably has a crosslinked structure portion in part from the viewpoint of improving mechanical strength, and examples thereof include a multilayer structure polymer having a crosslinked polymer layer. The rubber-containing copolymer preferably has a hard polymer portion from the viewpoint of heat resistance, and preferably has a non-crosslinked structure from the viewpoint of reducing birefringence. It preferably has a polymer part. For example, a multilayer structure polymer having a hard polymer layer is exemplified. The rubber-containing copolymer is more preferably a multilayer structure polymer including a crosslinked polymer layer and a hard polymer layer. In general, the multilayer structure polymer is also expressed as a graft copolymer or a core-shell polymer, but the rubber-containing copolymer of the present invention includes these.

  In U.S. Pat. No. 4,373,065, the structures of the two types of polymers are quite different, and basically they are hardly completely compatible. In fact, when two types of non-crosslinked polymers are blended, one polymer aggregates into a micron-order domain, or an apparently large lump, or even a surface unevenness, which deteriorates transparency, Causes foreign objects such as fish eyes. For this reason, in order to facilitate the complete compatibility of two types of polymers, it is necessary to design the polymer in consideration of two factors, birefringence control and compatibility control. Become. Here, the characteristics of the rubber-containing copolymer of the present invention are exhibited. In the present invention, the rubber-containing copolymer has a cross-linked polymer (layer) and a hard polymer (layer) so that the size of each rubber-containing copolymer is submicron-sized fine particles. When designed, blending a rubber-containing copolymer with a thermoplastic resin has a sea-island structure in which the rubber-containing copolymer is dispersed in a submicron size in the matrix thermoplastic resin. The rubber-containing copolymer aggregates indefinitely, such as several mm or several cm, and hardly deteriorates transparency and causes foreign matters such as fish eyes. Since the dispersibility in the matrix can be controlled by designing the rubber-containing copolymer into a submicron-size multilayer structure in advance, the rubber-containing copolymer can be contained in the matrix even if it is not completely compatible. Since the polymer can be dispersed, the degree of freedom in designing the polymer can be increased for both the thermoplastic resin and the rubber-containing copolymer as the matrix, such as a polymer design with emphasis on birefringence control.

  In the optical film obtained by the production method of the present invention, there are cases where high heat resistance and mechanical strength are required. In particular, when used as an optical film for a liquid crystal display, high heat resistance is required because it is exposed to high temperatures in the manufacturing process such as a film coating process as well as in actual use. Further, not only during film production, but also mechanical strength such as trimming and cracking resistance, such as a punching process after coating on a film or after being bonded to another member, is required. In such a case, by making the crosslinked polymer layer of the rubber-containing copolymer “soft”, the mechanical strength can be increased by adding the rubber-containing copolymer to the thermoplastic resin as the matrix component. At the same time, it can be improved dramatically, and at the same time, high heat resistance can be realized. In order to exhibit the effect, the rubber-containing copolymer is preferably a graft copolymer (core-shell polymer) having a soft crosslinked polymer layer and a hard polymer layer. Usually, a method of adding a soft polymer to improve the mechanical strength is also mentioned as a method. In this case, however, the matrix resin (here, a thermoplastic resin) and the soft polymer are mixed homogeneously, and the resulting film There is a disadvantage that heat resistance is lowered. On the other hand, in the case of a graft copolymer (core-shell polymer) having a soft cross-linked polymer layer and a hard polymer layer, the soft cross-linked polymer layer is “island”, and the thermoplastic resin and the hard polymer layer are in the film. Since it has a discontinuous sea-island structure that becomes the “sea”, it is possible to improve the mechanical strength and to achieve an excellent effect of hardly reducing the heat resistance. Moreover, since a soft crosslinked polymer usually has a composition different from that of a matrix (thermoplastic resin), it is difficult to uniformly disperse the matrix in a matrix. It becomes a defect. However, if the graft copolymer has both a soft crosslinked polymer layer and a hard polymer layer, the soft crosslinked polymer can be uniformly dispersed in the matrix as described above.

  “Soft” here means that the glass transition temperature of the polymer is less than 20 ° C. From the viewpoint of enhancing the impact absorbing ability of the soft layer and enhancing the impact resistance improving effect such as crack resistance, the glass transition temperature of the polymer is preferably less than 0 ° C, more preferably less than -20 ° C. .

  The term “hard” as used herein means that the glass transition temperature of the polymer is 20 ° C. or higher. When the glass transition temperature of the polymer is less than 20 ° C., the heat resistance of the film containing the rubber-containing copolymer is lowered, or when the rubber-containing copolymer is produced, Problems such as lumping are likely to occur.

  In this application, the glass transition temperatures of “soft” and “hard” polymers are calculated using the Fox equation using the values described in the Polymer Handbook (Polymer Hand Book (J. Brandrup, Interscience 1989)). The calculated value is used (for example, polymethyl methacrylate is 105 ° C. and polybutyl acrylate is −54 ° C.).

  Here, when a high mechanical strength is not so required for the film made of the resin composition of the present invention, the crosslinked polymer layer may be “soft” or “hard”, and this definition is It is as follows.

  In the present application, regarding the rubber-containing copolymer, a parameter called graft ratio is used to express how much the hard polymer layer is covalently bonded to the crosslinked polymer layer.

  The graft ratio of the rubber-containing copolymer is an index representing the weight ratio of the grafted hard polymer layer to the crosslinked polymer layer when the weight of the crosslinked polymer layer is 100. The graft ratio is preferably 10 to 250%, more preferably 40 to 230%, and most preferably 60 to 220%. If the graft ratio is less than 10%, the rubber-containing copolymer tends to aggregate in the molded product, which may reduce transparency and cause foreign matter. Moreover, there exists a tendency for the elongation at the time of a tensile fracture to fall and to become easy to generate | occur | produce a crack at the time of film cutting. If it is 250% or more, the melt viscosity at the time of molding, for example, at the time of film molding tends to be high, and the moldability of the film tends to decrease. The calculation formula will be described in the section of the embodiment.

  In some cases, a polymer (also referred to as a free polymer) that is not bonded to the crosslinked polymer layer (also referred to as a free polymer) may exist in a part of the hard polymer layer. This free polymer is also a rubber-containing copolymer. To include.

(Description of cross-linked polymer layer)
Here, the crosslinked polymer layer in the case where the rubber-containing copolymer is a graft copolymer will be described.

  When the rubber-containing copolymer has a “soft” cross-linked polymer layer, as described above, the “soft” means that the glass transition temperature of the polymer is less than 20 ° C., and a rubbery polymer is preferably used. Is done. Specific examples include butadiene-based crosslinked polymers, (meth) acrylic crosslinked polymers, and organosiloxane-based crosslinked polymers. Among these, a (meth) acrylic crosslinked polymer is particularly preferable in terms of weather resistance (light resistance) and transparency of the film.

  Here, the (meth) acrylic crosslinked polymer layer, which is a suitable “soft” crosslinked polymer layer, will be described in detail.

  The (meth) acrylic crosslinked polymer in the (meth) acrylic crosslinked polymer layer is not particularly limited as long as it is a (meth) acrylic crosslinked polymer. From the viewpoint of impact resistance such as crack resistance, acrylic 50 to 100% by weight of acid alkyl ester, 50 to 0% by weight of vinyl monomer copolymerizable with alkyl acrylate, and 0.05 to 10 parts by weight of polyfunctional monomer (alkyl acrylate and And a polymer obtained by polymerizing a vinyl monomer copolymerizable with 100 parts by weight in total). A layer formed by mixing all the monomer components and polymerizing in one step may be used, or a layer formed by polymerizing in two or more steps by changing the monomer composition.

  The alkyl acrylate ester used here is preferably an alkyl group having 1 to 12 carbon atoms in view of polymerization reactivity and cost, and may be linear or branched. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, benzyl acrylate, and n-octyl acrylate. , Β-hydroxyethyl acrylate, dimethylaminoethyl acrylate, glycidyl acrylate, and the like. These monomers may be used alone or in combination of two or more. The alkyl acrylate is preferably 50 to 100% by weight, more preferably 60 to 100% by weight based on the total monofunctional monomer (the total amount of the alkyl acrylate and the vinyl monomer copolymerizable therewith). Preferably, 70 to 100% by weight is most preferable. If it is less than 50% by weight, the crack resistance of the film may deteriorate.

  Examples of the monomer copolymerizable with an acrylic acid alkyl ester (hereinafter, also referred to as “copolymerizable monomer”) include, for example, methacrylic acid alkyl ester, which are polymerizable and cost-effective. More preferably, the alkyl group has 1 to 12 carbon atoms, and may be linear or branched. Specific examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, octyl acrylate, β-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid. Examples thereof include glycidyl acid. Other copolymerizable monomers include vinyl halides such as vinyl chloride and vinyl bromide, (meth) acrylamides such as acrylamide, methacrylamide and N-methylolacrylamide, acrylonitrile, methacrylonitrile and the like. Vinyl esters such as vinyl cyanide, vinyl formate, vinyl acetate and vinyl propionate, aromatic vinyl such as styrene, vinyltoluene and α-methylstyrene and derivatives thereof, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic acid And acrylic acid such as sodium acrylate and calcium acrylate and salts thereof, methacrylic acid such as methacrylic acid, sodium methacrylate and calcium methacrylate and salts thereof, and the like. Two or more of these monomers may be used in combination.

  Since the above-mentioned monofunctional monomer is copolymerized with a polyfunctional monomer having two or more non-conjugated reactive double bonds per molecule, the resulting polymer is a crosslinked product (rubber). It becomes. Polyfunctional monomers used here include allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl maleate, divinyl adipate, divinyl Benzene, ethylene glycol dimethacrylate, divinylbenzene ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, trimethylolpropane Trimethacrylate, trimethylolpropane triacrylate, tetramethylol methane tetramethacrylate, tetramethylol methane tetraacrylate, dipropylene glycol dimethacrylate and dipro Renguriko - diacrylate - DOO and the like, these two or more kinds may be used in combination.

  The addition amount of the polyfunctional monomer with respect to the monofunctional monomer is preferably 0.05 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the total amount of the monofunctional monomer. Is more preferable. If the addition amount of the polyfunctional monomer is less than 0.05 parts by weight, there is a tendency that a crosslinked product cannot be formed, and even if it exceeds 10 parts by weight, the crack resistance of the film tends to be lowered.

  On the other hand, the rubber-containing copolymer used in the present invention may have a “hard” crosslinked polymer layer, and as described above, “hard” means that the glass transition temperature of the polymer is 20 ° C. The above is shown.

  There is no particular limitation as long as the glass transition temperature is 20 ° C. or higher. Specifically, the monomers described in the description of the “soft” crosslinked polymer layer can be used as appropriate.

(Description of hard polymer layer)
The rubber-containing copolymer is transformed into a matrix (thermoplastic resin) by appropriately selecting monomers and polymerizing the "hard" polymerization that forms the hard polymer layer into a polymer that is easily compatible with the matrix component. It can be uniformly dispersed in.

  When partially oriented by the film forming method, the orientation birefringence of the hard polymer should be different from that of the matrix (thermoplastic resin) so as to reduce the orientation birefringence of the resin composition. Thus, the birefringence of the thermoplastic resin can be canceled out.

  The effect of canceling the birefringence of the matrix thermoplastic resin is larger in the “hard” polymer layer, and the effect is less in the polymer layer having a crosslinked structure. Either a cross-linked polymer layer of a rubber-containing copolymer, a hard polymer layer, or both may be provided with a function of canceling the birefringence of the thermoplastic resin without limiting the layer in particular. A “hard” polymer layer is most preferred. The reason is that when the polymer is oriented when the matrix (thermoplastic resin) is molded or when the polymer is oriented due to stress, the polymer of the rubber-containing heavy copolymer is oriented in the direction in which the polymer chain of the matrix is oriented by an external force. It is believed that birefringence can be canceled by aligning the chains. In this case, since the polymer layer having a crosslinked structure is not easily deformed by an external force, the polymer chain is difficult to be oriented, and the effect of canceling the birefringence of the matrix becomes small. Of course, if the crosslink density is low, it can be easily deformed by an external force, so even a polymer layer having a crosslink structure can be expected to have some effect of canceling the birefringence of the matrix. The polymer layer may have a function of canceling the birefringence of the matrix. Preferably, a polymer layer other than the cross-linked polymer layer is used, and a polymer layer that can be oriented by external force is preferable, and specifically, a “hard” polymer layer is used. More preferably, it is a “hard” polymer layer that does not have a cross-linked structure, and even more preferably, it is an outer layer of a rubber-containing copolymer that has a cross-linked structure at a site that is easily in direct contact with the matrix. There is no “hard” polymer layer.

  Taking as an example a `` hard '' polymer layer located in the outer layer of a rubber-containing copolymer that has a high effect of canceling the birefringence of the thermoplastic resin and increasing the optical isotropy of the film of the present invention. This will be described below.

  Additivity is established between the orientation birefringence of the rubber-containing copolymer and the intrinsic birefringence of each homopolymer corresponding to the monomer species used in the copolymerization. The same applies to a mixture of two or more polymers (alloy), and an additivity is established between the intrinsic birefringence of each polymer. Regarding the monomer species used for the hard polymer layer of rubber-containing copolymer and suitable for canceling the orientation birefringence of thermoplastic resin, the orientation birefringence of each of thermoplastic resin and rubber-containing copolymer is different. It may be selected so that In setting the orientation birefringence of the polymer, examples of specific monomers to be used as reference (inherent birefringence of homopolymers composed of the monomers) are described below, but are not limited thereto. The intrinsic birefringence is birefringence (orientation birefringence) when the polymer is completely oriented in one direction.

Polymer exhibiting positive intrinsic birefringence:
Polybenzyl methacrylate [+0.002]
Polyphenylene oxide [+0.210]
Bisphenol A polycarbonate [+0.106]
Polyvinyl chloride [+0.027]
Polyethylene terephthalate [+0.105]
Polyethylene [+0.044]
Polymer exhibiting negative intrinsic birefringence:
Polymethyl methacrylate [−0.0043]
Polystyrene [-0.100]
The data on the orientation birefringence of some polymers has been described above. However, depending on the polymer, both birefringences such as “positive” are not necessarily the same sign.

  Next, the detailed polymer composition of a hard polymer is demonstrated.

  From the viewpoint of improving the dispersibility of the rubber-containing copolymer in the thermoplastic resin in order to reduce appearance defects such as mechanical strength, heat resistance, and fish eyes (ie, increase compatibility), if necessary The composition of the hard polymer is not particularly limited as long as the viewpoint of canceling the orientation birefringence of the thermoplastic resin as the matrix is taken into consideration. Among them, a monomer (monomer) that can be particularly preferably used is a vinyl monomer having a ring structure such as an alicyclic structure, a heterocyclic structure, or an aromatic group in the molecular structure. Among them, a vinyl monomer having an alicyclic structure, a heterocyclic structure or an aromatic group is more preferable. In the vinyl monomer having an alicyclic structure, the ring structure is preferably a polycyclic structure, and more preferably a condensed cyclic structure. Specifically, it is preferable that the structural unit contains a monomer represented by the following formula (4). Examples of the monomer having an alicyclic structure include (meth) acrylic acid dicyclopentanyl, dicyclopentenyloxyethyl (meth) acrylate, and the like. Examples of the monomer having an aromatic group include vinyl arenes such as styrene, α-methylstyrene, monochlorostyrene, dichlorostyrene, benzyl (meth) acrylate, phenyl (meth) acrylate, and (meth) acrylic. Phenoxyethyl acid etc. can be mentioned. Examples of the monomer having a heterocyclic structure include pentamethylpiperidinyl (meth) acrylate, tetramethylpiperidinyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate. Of these, benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and phenoxyethyl (meth) acrylate are preferred.

R ⁹ represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms. R ¹⁰ is a substituted or unsubstituted aromatic group having 1 to 24 carbon atoms, or a substituted or unsubstituted alicyclic group having 1 to 24 carbon atoms, and has a monocyclic structure or a heterocyclic structure. Have. Examples of the substituent that R ⁹ and R ¹⁰ may have include, for example, a halogen, a hydroxyl group, a carboxyl group, an alkoxy group, a carbonyl group (ketone structure), an amino group, an amide group, an epoxy group, and a carbon-carbon group. Examples thereof include at least one selected from the group consisting of a double bond, an ester group (carboxyl group derivative), a mercapto group, a sulfonyl group, a sulfone group, and a nitro group. Among these, at least one selected from the group consisting of halogen, hydroxyl group, carboxyl group, alkoxy group, and nitro group is preferable. l represents an integer of 1 to 4, preferably 1 or 2. m is an integer of 0-1. n shows the integer of 0-10, Preferably the integer of 0-2 is shown, More preferably, it is 0 or 1.

The vinyl monomer having an alicyclic structure, a heterocyclic structure or an aromatic group is preferably a (meth) acrylic monomer having an alicyclic structure, a heterocyclic structure or an aromatic group. In the formula (4), R ⁹ is preferably a (meth) acrylate monomer which is a substituted or unsubstituted alkyl group having 1 carbon atom. In the formula (4), R ¹⁰ is a substituted or unsubstituted aromatic group having 1 to 24 carbon atoms, or a substituted or unsubstituted alicyclic group having 1 to 24 carbon atoms, and a monocyclic structure More preferably, it is a (meth) acrylate monomer.

  In Formula (4), it is more preferable that l is an integer of 1 to 2, and n is an (meth) acrylate monomer that is an integer of 0 to 2.

  Among the (meth) acrylic monomers represented by the formula (4), benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and phenoxyethyl (meth) acrylate are preferable.

  Among the monomers represented by the formula (4), benzyl (meth) acrylate is most preferable in terms of optical isotropy, compatibility with thermoplastic resins, and moldability. Furthermore, benzyl methacrylate is preferable in terms of heat resistance because of its high glass transition temperature. For example, when the thermoplastic resin is an acrylic resin, the orientation birefringence of the molded product is large, and in cases where there is a practical problem, the orientation birefringence of the acrylic resin is negative, whereas benzyl methacrylate is oriented. Since the birefringence is positive, the orientation birefringence can be reduced.

  Containing the monomer represented by the formula (4) from the viewpoint of improving the dispersibility of the rubber-containing copolymer and reducing appearance defects such as fish eyes while maintaining excellent optical isotropy. The hard polymer contained in the unit is 1 to 100% by weight of the monomer represented by the formula (4), 99 to 0% by weight of another monomer copolymerizable therewith, and 0 to the polyfunctional monomer. It is preferable to polymerize .about.2.0 parts by weight (based on 100 parts by weight of the total amount of the monomer represented by the formula (4) and other monomers copolymerizable therewith). The hard polymer layer may be formed by mixing all the monomers and polymerizing in one step, or may be formed by polymerizing in two or more steps by changing the monomer composition. .

  In the present invention, as the monomer represented by the formula (4), any of benzyl methacrylate, benzyl acrylate, dicyclopentanyl (meth) acrylate, and phenoxyethyl (meth) acrylate is preferably used. Any one or a combination of them can be used. For applications requiring higher heat resistance, it is preferable to use benzyl methacrylate from the viewpoint of glass transition temperature.

  Examples of the other monomer copolymerizable with the monomer represented by the formula (4) include methacrylic acid alkyl ester, which has 1 to 12 carbon atoms in the alkyl group from the viewpoint of polymerizability and cost. Those are preferable, and may be linear or branched. Specific examples thereof include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl acrylate, β-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate. Etc. Also, alkyl acrylates can be suitably used, and those having an alkyl group with 1 to 12 carbon atoms are preferable from the viewpoint of polymerization reactivity and cost, and may be linear or branched. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, and β-acrylate. -Hydroxyethyl, dimethylaminoethyl acrylate, glycidyl acrylate and the like. Other copolymerizable monomers include maleic anhydride, citraconic anhydride, dimethyl maleic anhydride, dichloromaleic anhydride, bromomaleic anhydride, dibromomaleic anhydride, phenylmaleic anhydride, diphenylmaleic anhydride. Unsubstituted and / or substituted maleic anhydrides such as acids, vinyl halides such as vinyl chloride and vinyl bromide, (meth) acrylamides such as acrylamide, methacrylamide and N-methylolacrylamide, cyan such as acrylonitrile and methacrylonitrile Vinyl esters such as vinyl fluoride, vinyl formate, vinyl acetate, vinyl propionate, aromatic vinyl such as styrene, vinyltoluene, α-methylstyrene and derivatives thereof, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic acid, Acrylic acid Acrylic acid and salts thereof such as thorium and calcium acrylate, methacrylic acid and salts thereof such as methacrylic acid, sodium methacrylate and calcium methacrylate, methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate And (hydroxyalkyl) acrylic acid esters such as 2- (hydroxymethyl) acrylic acid isopropyl, 2- (hydroxymethyl) acrylic acid normal butyl, 2- (hydroxymethyl) acrylic acid tertiary butyl, and the like. These monomers may be used alone or in combination of two or more. Among these, methacrylic acid alkyl esters and acrylic acid alkyl esters are preferable, and methyl methacrylate is more preferable in terms of compatibility with acrylic resins, and methyl acrylate, ethyl acrylate, or acrylic acid is effective in suppressing zipper depolymerization. It is preferable to use n-butyl.

  The amount of the monomer represented by the formula (4) is 1 to 100 in a total amount of 100% by weight of the monomer represented by the formula (4) and other monomers copolymerizable therewith. % By weight is preferred, 5 to 70% by weight is more preferred, and 5 to 50% by weight is most preferred.

  In addition, in the hard polymer layer which has the (meth) acrylate monomer represented by said Formula (4) in a structural unit, the polyfunctional monomer which has a 2 or more reactive double bond per molecule | numerator May be used. Here, as a polyfunctional monomer, the polyfunctional monomer which can be used for a crosslinked polymer layer can be used similarly. The amount of polyfunctional monomer used in the hard polymer layer (based on the total amount of the monomer represented by the formula (4) and the vinyl monomer copolymerizable therewith is 100 parts by weight) is: From the viewpoint of optical isotropy and dispersibility, 0 to 2.0 parts by weight is preferable, 0 to 1.0 parts by weight is more preferable, 0 to 0.5 parts by weight is further preferable, and 0 to 0.04 parts by weight. Part by weight is even more preferred and 0 part by weight is most preferred.

  The rubber-containing copolymer is a multilayer structure polymer having at least one (meth) acrylic crosslinked polymer layer and at least one hard polymer layer having the monomer represented by the formula (4) as a constituent unit. It is preferable. To illustrate one preferred form of the rubber-containing polymer, it has a soft inner layer and a hard outer layer, the inner layer has a (meth) acrylic crosslinked polymer layer, and the outer layer is represented by the formula (4). The form which has the hard polymer layer which has the monomer made into a structural unit can be mentioned. This form is preferable from the viewpoint of productivity. Moreover, by having it in the hard outermost layer, it becomes easier to be compatible with the acrylic resin, the orientation birefringence can be further reduced, and a film excellent in optical isotropy can be easily obtained. As another preferred embodiment, the rubber-containing copolymer has a hard inner layer, a soft intermediate layer and a hard outer layer, and the inner layer is composed of at least one hard polymer layer. Examples include a soft polymer layer composed of a (meth) acrylic crosslinked polymer layer, and the outer layer having a hard polymer layer having a monomer represented by the formula (4) as a constituent unit. This form may also have a softer innermost layer. In the present invention, these may be used singly or in combination of two or more.

  In the present application, a soft inner layer, a soft intermediate layer, and a soft layer (hereinafter referred to as a soft layer) refer to an inner layer, an intermediate layer, and a layer made of at least one soft polymer.

  On the other hand, the hard (outermost) outer layer and the hard inner layer in the present application refer to the (outermost) outer layer and inner layer made of at least one hard polymer. Here, “soft” and “hard” are the same as “soft” and “hard” described above.

  When the rubber-containing copolymer has a hard layer in the innermost layer, for example, a multilayer structure composed of a hard inner layer, a soft intermediate layer, and a hard outer layer, And from the viewpoint of a balance of crack resistance, methacrylic acid ester 40 to 100% by weight, acrylic acid ester 0 to 60% by weight, aromatic vinyl monomer 0 to 60% by weight, polyfunctional monomer 0 to 10% A hard polymer composed of 0 to 20% by weight of a vinyl monomer copolymerizable with methacrylic acid ester, acrylic acid ester and aromatic vinyl monomer can be suitably exemplified.

  The rubber-containing copolymer is, for example, a hard inner layer having a soft inner layer having a (meth) acrylic crosslinked polymer layer and a polymer layer having a monomer represented by the formula (4) as a constituent unit. In the case of a multilayer structure composed of outer layers, a layer structure in which the soft inner layer is completely covered with the outer hard polymer is ideal, but depending on the weight ratio of the soft inner layer to the hard outer layer, etc. There may be cases where the amount of hard polymer to form is insufficient. In such a case, it is not necessary to have a complete layer structure, and a structure in which a part of a soft inner layer is coated with an external hard polymer, or a part of a soft inner layer is grafted with an external hard polymer. A polymerized structure can also be preferably used. The same applies to multilayer structures of other forms.

  The volume average particle diameter of the rubber-containing copolymer to the (meth) acrylic crosslinked polymer layer is preferably 20 to 450 nm, more preferably 20 to 300 nm, still more preferably 20 to 150 nm, and most preferably 30 to 80 nm. If it is less than 20 nm, crack resistance may deteriorate. On the other hand, if it exceeds 450 nm, the transparency may decrease. Furthermore, it is preferable to make it less than 80 nm from a viewpoint of bending whitening resistance. Moreover, from a trimming viewpoint, 20-450 nm is preferable, 50-450 nm is more preferable, 60-450 nm is more preferable, 100-450 nm is still more preferable. The volume average particle diameter can be measured by a dynamic light scattering method, for example, by using MICROTRAC UPA150 (manufactured by Nikkiso Co., Ltd.). Here, the volume average particle diameter of the rubber-containing copolymer to the (meth) acrylic crosslinked polymer layer is specifically the center of the rubber-containing copolymer particles (meth) acrylic crosslinked polymer layer. Refers to the volume average particle diameter of the particles up to. When the rubber-containing copolymer has two or more (meth) acrylic crosslinked polymer layers, it means the volume average particle diameter up to the (meth) acrylic crosslinked polymer layer located on the outermost side with respect to the center. And

  The content of the acrylic cross-linked polymer in the rubber-containing copolymer is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, and more preferably 30 to 60% when the rubber-containing copolymer is 100% by weight. % By weight is more preferred and 35 to 55% by weight is most preferred. If it is less than 10% by weight, the mechanical strength such as crack resistance of the obtained resin material may be lowered. On the other hand, if it exceeds 90% by weight, the dispersibility of the rubber-containing copolymer is impaired, the smoothness of the surface of the molded article cannot be obtained, and there is a tendency that appearance defects such as fish eyes occur. In addition, the content of the hard polymer is not sufficient, and there is a tendency that optical isotropy cannot be maintained, such as an increase in birefringence during orientation.

  The method for producing the rubber-containing copolymer is not particularly limited, and a known emulsion polymerization method, emulsion-suspension polymerization method, suspension polymerization method, bulk polymerization method or solution polymerization method can be applied. An emulsion polymerization method is particularly preferred for the polymerization of the rubber-containing copolymer.

  The rubber-containing copolymer is preferably obtained by multistage polymerization, and is represented by the above formula (4) in the presence of (meth) acrylic rubber-containing polymer particles as at least one stage of this multistage polymerization. A multi-stage polymerization (meth) acrylic rubber-containing graft copolymer obtained by polymerizing a monomer-containing monomer and a mixture containing another monomer copolymerizable therewith can be preferably used.

  The mixture containing the monomer represented by the formula (4) and another monomer copolymerizable therewith is composed of the monomer represented by the formula (4) and the other copolymerizable therewith. In the total amount of the monomers of 100% by weight, the content of the monomer represented by the formula (4) is preferably 1 to 100% by weight, more preferably 5 to 70% by weight, and 5 to 50% by weight. Most preferred. This mixture may contain a polyfunctional monomer, and the total amount of the monomer represented by the formula (4) and other monomers copolymerizable therewith is 100 parts by weight. It is preferable to use 0 to 2.0 parts by weight of the monofunctional monomer, more preferably 0 to 1.0 parts by weight, still more preferably 0 to 0.5 parts by weight, and 0 to 0.04 parts by weight. Even more preferred is 0 part by weight. By polymerizing the mixture here, a hard polymer having the monomer represented by the formula (4) as a constituent unit is formed. Other monomers copolymerizable with the monomer represented by the formula (4) are the same as those exemplified above, and can be preferably used in the same manner. The same applies to the preferred content of other monomers copolymerizable with the monomer represented by the formula (4). Further, the polyfunctional monomer is the same as the above-described example, and can be preferably used similarly.

  The (meth) acrylic rubber-containing polymer particles need only be multistage polymer particles containing at least (meth) acrylic rubber, and can be copolymerized with 50 to 100% by weight of acrylic acid alkyl ester and acrylic acid alkyl ester. 50 to 0% by weight of other monomers, and 0.05 to 10 parts by weight of a polyfunctional monomer (based on a total amount of 100 parts by weight of alkyl acrylate ester and other monomers copolymerizable therewith) It is preferable to have a rubber ((meth) acrylic cross-linked polymer) part obtained by polymerizing. The rubber part may be polymerized in one stage by mixing all the monomer components, or may be polymerized in two or more stages by changing the monomer composition.

  The (meth) acrylic rubber-containing polymer particles are not particularly limited as long as a (meth) acrylic crosslinked polymer (rubber part) is formed as at least one stage of polymerization in multistage polymerization. The hard polymer may be polymerized before and / or after the polymerization step of the system cross-linked polymer.

  Among these, from the viewpoint of productivity, the rubber-containing copolymer is (b-1) 50 to 100% by weight of an acrylic acid alkyl ester, 50 to 0% by weight of a monomer copolymerizable therewith, and a polyfunctional monomer. Contains a (meth) acrylic rubber by polymerizing a monomer mixture consisting of 0.05 to 10 parts by weight of a monomer (based on a total amount of 100 parts by weight of alkyl acrylate and monomers copolymerizable therewith) (B-2) In the presence of the (meth) acrylic rubber-containing polymer particles, 1 to 100% by weight of the monomer represented by the formula (4) can be copolymerized therewith. 99 to 0% by weight of other monomers and 0 to 2.0 parts by weight of a polyfunctional monomer (monomer represented by the formula (4) and other monomers copolymerizable therewith) (Meth) acrylic polymerized monomer mixture consisting of 100 parts by weight of the total amount of Preferable to use those obtained as beam-containing graft copolymer. Here, (b-1) the monomer mixture in the polymerization stage and / or (b-2) the monomer mixture in the polymerization stage may be polymerized in one stage by mixing all the monomer components. The polymerization may be carried out in two or more stages by changing the monomer composition. In addition, the alkyl ester of acrylic acid, the monomer and polyfunctional monomer copolymerizable therewith in (b-1), and the preferred amounts of these are used in the above-mentioned (meth) acrylic acid crosslinked polymer. This is the same as illustrated. In (b-2), the components of the monomer mixture and the preferred amounts thereof used are the same as those in the above-mentioned hard polymer layer.

  The volume average particle diameter of the above (meth) acrylic rubber-containing graft copolymer to the (meth) acrylic rubber layer is the volume average of the above rubber-containing copolymer to the (meth) acrylic crosslinked polymer layer. It is measured in the same manner as the particle diameter, and the preferred range is also the same.

  When the rubber-containing copolymer is produced by emulsion polymerization, it can be produced by ordinary emulsion polymerization using a known emulsifier. Specifically, for example, anionic interfaces such as sodium alkyl sulfonate, sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, sodium lauryl sulfate, fatty acid sodium, polyoxyethylene lauryl ether sodium phosphate, etc. Activators, alkylphenols, nonionic surfactants such as reaction products of aliphatic alcohols with propylene oxide and ethylene oxide are shown. These surfactants may be used alone or in combination of two or more. Furthermore, if necessary, a cationic surfactant such as an alkylamine salt may be used. Among these, from the viewpoint of improving the thermal stability of the obtained acrylic rubber polymer, in particular, phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate (alkali metal salt, ammonium salt or alkaline earth metal salt) ) Is preferably used for polymerization.

  The rubber-containing copolymer thus produced by emulsion polymerization is obtained in a so-called latex state in which primary particles of a crosslinked structure-containing polymer are emulsified and dispersed in an aqueous phase. The latex of such a rubber-containing copolymer has a larger particle size, often referred to as a scale, which is a by-product of the multilayer polymerization process of the rubber-containing copolymer particles, and often has a partially or totally crosslinked structure. Often includes accompanying polymer particles and polymer masses. In addition, foreign substances including inorganic substances, dust in the gas phase and water may be mixed from the external environment through the polymerization process. These scales and foreign matters are undesirable because they cause optical defects when mixed into the resin composition used in the optical film of the present invention. For this reason, it is preferable to filter the latex of the rubber-containing copolymer with a mesh or a filter for the purpose of reducing or removing these scales and foreign matters. In the case of filtration, the meshes and filters used can be widely applied well-known ones proposed for the purpose of filtering liquid substances, and the openings within a range that allows the primary particles of the rubber-containing copolymer to pass through. Thus, the method, the mesh size, the number of stages, the filtration capacity, etc. may be appropriately selected according to the polymerization scale produced as a by-product, the size of foreign matter to be mixed and the required removal rate.

  The rubber-containing copolymer latex obtained by emulsion polymerization is, for example, spray-dried, freeze-dried, or coagulated by adding a salt such as calcium chloride or magnesium sulfate, or an acid such as hydrochloric acid or sulfuric acid as a coagulant, A powdery multilayer structure polymer can be obtained by treating the resin solidified by heat treatment or the like by a known method such as separation from the aqueous phase, washing and drying. In the case of obtaining a multilayer structure polymer by coagulation of a polymer latex, a magnesium salt, particularly magnesium sulfate, may be used as a coagulant from the viewpoint of improving the thermal stability during molding of the obtained copolymer. Particularly preferred.

  The rubber-containing copolymer is preferably blended so that 1 to 60 parts by weight of the (meth) acrylic crosslinked polymer ((meth) acrylic rubber) is contained in 100 parts by weight of the resin material. Part is more preferable, and 1 to 25 parts by weight is further preferable. If it is less than 1 part by weight, the crack resistance and vacuum formability of the film may deteriorate. On the other hand, when it exceeds 60 parts by weight, the heat resistance, surface hardness, transparency, and bending whitening resistance of the film tend to deteriorate.

  As for the blending ratio of the thermoplastic resin and the rubber-containing copolymer, there is no particular problem as long as the blending conditions are satisfied, and depending on the amount of the acrylic crosslinked polymer contained in the rubber-containing copolymer, When the total of the thermoplastic resin and the rubber-containing copolymer is 100% by weight, the rubber-containing copolymer is preferably 1 to 90% by weight, more preferably 1 to 75% by weight, and further preferably 1 to 60% by weight. . If it is less than 1% by weight, the crack resistance and vacuum formability of the film may deteriorate. On the other hand, when it exceeds 90% by weight, the heat resistance, surface hardness, transparency, and bending whitening resistance of the film tend to deteriorate.

  The resin material of the present invention remains in a granular form or is formed into pellets by an extruder, and is then molded into a shape suitable for the application by heating, extrusion molding, injection molding, compression molding, blow molding, spinning molding, etc. It can be. It is particularly useful as a film, and can be satisfactorily processed by, for example, an ordinary melt extrusion method such as an inflation method, a T-die extrusion method, a calendar method, or a solvent casting method. Among them, it is preferable to use a melt extrusion method that does not use a solvent. According to the melt extrusion method, it is possible to reduce the burden on the global environment and the working environment due to manufacturing costs and solvents.

In the present invention, a resin composition having an orientation birefringence value of the obtained optical film of −2.0 × 10 ^{−4 to} 2.0 × 10 ⁻⁴ is used. From the viewpoint of obtaining stable optical characteristics, it is preferably −1.6 × 10 ^{−4 to} 1.6 × 10 ⁻⁴ , and is −1.5 × 10 ^{−4 to} 1.5 × 10 ⁻⁴ . Is more preferable, −1.0 × 10 ^{−4 to} 1.0 × 10 ⁻⁴ is further preferable, and −0.5 × 10 ^{−4 to} 0.5 × 10 ⁻⁴ is particularly preferable. , and most preferably ^{-0.2 × 10 -4 ~0.2 × 10 -4} .

  When forming a film, both surfaces of the film are brought into contact with a roll or a metal belt at the same time (sandwiched), and particularly by bringing into contact with a roll or a metal belt heated to a temperature near the glass transition temperature at the same time, the surface property is more excellent It is possible to obtain a film.

In the present invention, when the birefringence of the obtained film is in the above range, the optical properties are not impaired even when the both surfaces of the film obtained by melt extrusion are simultaneously brought into contact with a roll or a metal belt (sandwich). The point is a feature. When the orientation birefringence of the obtained film is −2.0 × 10 ^{−4 to} 2.0 × 10 ⁻⁴ , protrusions due to fine aggregates generated on the film surface after extrusion are sandwiched by a roll or the like. Even if the film is smoothed by the above method, the retardation of the film does not occur and the optical characteristics are not impaired. When the protrusions on the film caused by fine aggregates are smoothed by a roll or the like, it can be considered that the smoothed original protrusion part is oriented, but the orientation birefringence of the film of the present invention is − In the case of 2.0 × 10 ^{−4 to} 2.0 × 10 ⁻⁴ , surprisingly, the original protrusion does not cause phase difference unevenness.
The present invention can achieve both good optical properties and excellent surface smoothness.

  The agglomerate is often an agglomerate produced in the production process of the rubber-containing copolymer, but also a rubber-containing copolymer that has not been sufficiently dispersed in the pelletizing or filming process, or pelletized, In some cases, the rubber-containing copolymer is re-agglomerated at the time of film extrusion.

  The size of the aggregate is measured in the prepared film, and the smaller the number of aggregates of 20 μm or more, more preferably 50 μm or more, is preferable in terms of the smoothness of the film.

  Hereinafter, as an embodiment of the method for producing a film according to the present invention, a method for producing a film by molding the resin material according to the present invention by a melt extrusion method will be described in detail.

  In the following description, a film formed by the melt extrusion method is distinguished from a film formed by another method such as a solution casting method and is referred to as a “melt extrusion film”.

  When the resin material according to the present invention is formed into a film by a melt extrusion method, first, the resin material according to the present invention is supplied to an extruder, and the resin material is heated and melted.

  The resin material is preferably pre-dried before being supplied to the extruder. By performing such preliminary drying, foaming of the resin extruded from the extruder can be prevented.

  Although the method of preliminary drying is not particularly limited, for example, the raw material (that is, the resin material according to the present invention) can be formed into pellets or the like and can be performed using a hot air dryer or the like.

  Further, the extruder for molding the resin material according to the present invention preferably has one or more devolatilizers for removing volatile components generated during heating and melting. By having a deaeration device, it is possible to reduce deterioration of the film appearance due to resin foaming and decomposition degradation reaction.

Furthermore, in melt extrusion for molding the resin material according to the present invention, it is preferable to supply an inert gas such as nitrogen or helium to the cylinder of the extruder along with the supply of the resin material. By supplying the inert gas, it is possible to reduce the concentration of oxygen in the system and to reduce deterioration in appearance and quality such as decomposition, crosslinking, and yellowing due to oxidative deterioration.
Next, the resin material heated and melted in the extruder is supplied to the T die through a gear pump and a filter. At this time, if a gear pump is used, the uniformity of the extrusion amount of the resin can be improved and thickness unevenness can be reduced. On the other hand, if a filter is used, the foreign material in a resin material can be removed and the film excellent in the external appearance without a defect can be obtained.

  As the type of filter, it is preferable to use a stainless steel leaf disc filter capable of removing foreign substances from the molten polymer, and it is preferable to use a fiber type, a powder type, or a composite type thereof as the filter element. The filter can be suitably used for an extruder or the like used for pelletization or film formation.

  The aperture of the filter is preferably 10 μm or less, more preferably 5 μm or less from the viewpoint of removing foreign substances in the molten resin.

Next, as shown in FIG. 1, the resin composition supplied to the T die 1 is extruded from the T die 1 as a sheet-like molten resin 2. The sheet-like molten resin 2 is preferably sandwiched between two cooling rolls and cooled to form a film. The T die 1 is not particularly limited, and a known T die 1 can be used as appropriate. For example, it is preferable that the T die 1 has a discharge port having a shape capable of extruding the sheet-like molten resin 2, but the shape is not particularly limited. Further, the shape of the discharge port is not particularly limited.
The sheet-like molten resin 2 is extruded from the discharge port of the T die 1. The shape of the molten resin 2 may be a sheet shape, and the thickness and width are not particularly limited. For example, the thickness of the sheet-like molten resin 2 is not particularly limited as long as it can be manufactured. For example, the thickness of the molten resin 2 is preferably about 20 μm to 300 μm, but is not limited thereto. If the thickness of the molten resin 2 is less than 20 μm, the thickness of the manufactured film tends to increase due to the large influence of the bending of the roll. On the other hand, if the thickness of the molten resin 2 is thicker than 300 μm, it becomes difficult to manufacture because the conveyance becomes difficult.

  The width of the sheet-like molten resin 2, in other words, the length of the molten resin 2 in a direction substantially perpendicular to the extrusion direction, and the direction of the force applied to the molten resin 2 in film formation The length of the molten resin 2 in the substantially vertical direction is not particularly limited.

  In the above extrusion, the melt viscosity of the molten resin 2 extruded from the discharge port of the T die 1 is not particularly limited, but is preferably, for example, 1500 Pa · sec or less. In addition, the said melt viscosity can be adjusted by changing the content rate of each structural unit in acrylic resin, for example. The melt viscosity can be measured according to a known method as appropriate.

If the melt viscosity of the molten resin 2 extruded from the discharge port of the T-die 1 is within the above range, the thickness unevenness of the produced film can be more reliably reduced and the occurrence of a die line can be prevented. Can do.
The extruded sheet-like molten resin 2 is taken up by a cast roll 4, cooled, solidified, and wound up to form a film. At this time, it is preferable to sandwich and form between the two rolls of the cast roll 4 and the touch roll 3.
More specifically, the two rolls of the cast roll 4 and the touch roll 3 are arranged to face each other, and the sheet-like molten resin 2 is sandwiched therebetween. And when force is applied to the molten resin 2 by the roll, the film thickness in the width direction (TD) of the molten resin 2 becomes uniform and thin. As a result, a desired film can be produced. At this time, the force for sandwiching the cast roll 4 and the touch roll 3 with respect to the molten resin 2 is P (N), and the force for sandwiching the sheet-like molten resin 2 is the sheet-like molten resin 2 discharged from the T die 1. It is preferable to apply a linear pressure to the molten resin 2 so that 30.0 ≦ P / H ≦ 300.0, where H is the width of H (cm).

  The touch roll 3 and the cast roll 4 are not particularly limited, and known rolls can be used as appropriate. For example, the same roll can be used as the touch roll 3 and the cast roll 4, and different rolls can be used. For example, when different rolls are used as the touch roll 3 and the cast roll 4, it is preferable to use an elastic roll as the touch roll 3 and a rigid roll as the cast roll 4.

The surface property of the elastic roll and the rigid roll is preferably a mirror surface. As the mirror surface, the arithmetic average roughness Ra is preferably 0.1 μm or less, more preferably 0.07 μm or less, and still more preferably 0.05 μm or less.
The method for applying the P (N) force to the sheet-like molten resin 2 is not particularly limited. For example, when the width of the sheet-like molten resin 2 changes, at least one roll may be moved with respect to the other roll so that the force P (N) can be changed accordingly. . Moreover, when the width | variety of the sheet-like molten resin 2 is substantially constant, what is necessary is just to fix the distance between the touch roll 3 and the cast roll 4 according to the said width | variety.
Moreover, the temperature of each roll is not specifically limited, It can set suitably. For example, when the glass transition temperature of the resin material is Tg (° C.) and the roll temperature is T (° C.), it is preferable to set the temperature of each roll so that Tg−70 ≦ T ≦ Tg + 30. In addition, the glass transition temperature here means the glass transition temperature measured with the differential scanning calorimeter (DSC).

According to the said structure, since the difference of the temperature of a roll and the glass transition temperature of the molten resin 2 is small, a linear pressure can be applied to the molten resin 2 on the temperature conditions close | similar to a glass transition temperature. As a result, the thickness unevenness of the thermoplastic sheet to be produced can be reduced, and the occurrence of die lines and dent defects can be suppressed.
Further, the rotation speed of the roll is R (cm / sec), and from the discharge port of the T die 1 for extruding the resin material to the contact point of the cast roll 4 and the touch roll 3 with the sheet-like molten resin 2. When the distance is L (cm), it is preferable that L / R ≦ 1.0. As described above, a film having desired characteristics can be produced.

  The film obtained by the production method of the present invention is extremely tough and rich in flexibility, so there is no need to stretch to improve strength, productivity is improved by omitting the stretching process, and cost benefits There is. The film obtained by the production method of the present invention is highly transparent and can have a thickness of 10 μm or more with high strength. Furthermore, orientation birefringence due to stretching hardly occurs, and it can be made optically isotropic. In addition, shrinkage due to heat during secondary molding such as vacuum molding or during use at high temperatures is small.

  The optical film obtained by the production method of the present invention utilizes the properties such as heat resistance, transparency, flexibility, etc., and uses a light guide plate for liquid crystal, a diffusion plate, a back sheet, a reflection sheet, an optical isotropic film, a polarizer. Protective film, polarizing film, transparent resin sheet, retardation film, light diffusion film, film for liquid crystal display such as prism sheet, information equipment field such as surface protective film, and well-known optical devices such as transparent conductive film and the periphery of liquid crystal display devices It can be particularly suitably used for applications.

  The thickness of the film obtained by the production method of the present invention is not particularly limited, but is preferably 500 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less. Further, it is preferably 10 μm or more, more preferably 30 μm or more, further preferably 50 μm or more, and particularly preferably 100 μm or more. If the thickness of the film is within the above range, there is an advantage that it is difficult to be deformed when vacuum forming is performed using the film, and it is difficult to cause breakage at the deep drawing portion, and the optical characteristics are uniform, A film with good transparency can be produced. On the other hand, when the thickness of the film exceeds the above range, cooling of the film after molding becomes nonuniform, and the optical characteristics tend to be nonuniform. Moreover, when the thickness of a film is less than the said range, handling of a film may become difficult.

  The film obtained by the production method of the present invention preferably has a haze value of 2.0% or less, more preferably 1.0% or less, still more preferably 0.8% or less, and It is particularly preferable that it is 5% or less. If the haze value of the film of the present invention is within the above range, the transparency of the film is sufficiently high, and it is suitable for optical use, decoration use, interior use, or vacuum forming use that requires transparency. .

  The film of the present invention preferably has a total light transmittance of 85% or more, and more preferably 88% or more. If the total light transmittance is within the above range, the transparency of the film is sufficiently high, and it can be suitably used in optical applications, decoration applications, interior applications, or vacuum forming applications that require transparency. .

  The film obtained by the production method of the present invention preferably has a glass transition temperature of 100 ° C. or higher, more preferably 115 ° C. or higher, further preferably 120 ° C. or higher, and still more preferably 124 ° C. or higher. When the glass transition temperature is within the above range, a film having sufficiently excellent heat resistance can be obtained.

  The film obtained by the production method of the present invention preferably has a tensile elongation at break of 10% or more, more preferably 20% or more, further preferably 30% or more, and 40% or more. Even more preferably, it is particularly preferably 50% or more, particularly preferably 60% or more, and most preferably 90% or more. The film of the present invention showing the tensile elongation at break within the above range is less likely to crack when trimming the film with a Thomson blade or a cutter blade (trimming property), and when the film is wound on a roll, Or it is hard to fracture | rupture, when post-processing, such as coating, vapor deposition, sputtering, bonding of a protective film, with respect to the surface of the said film. Moreover, the crack resistance when the film is bent is high, and troubles such as cracking do not occur not only in the post-processing process but also in actual use as a product. In particular, the tensile strength at break at break is correlated with the crackability, and the higher the tensile elongation at break, the better the crack resistance.

EXAMPLES Hereinafter, although this invention is demonstrated concretely in an Example, this invention is not limited to these Examples. In the following, “parts” and “%” mean “parts by weight” and “% by weight” unless otherwise specified.

(Volume average particle diameter to (meth) acrylic crosslinked polymer layer of graft copolymer)
The volume average particle diameter (volume average particle diameter of acrylic rubber particles) up to the (meth) acrylic crosslinked polymer layer of the graft copolymer was measured in the state of acrylic rubber particle latex. The volume average particle diameter (μm) was measured using MICROTRAC UPA150 manufactured by Nikkiso Co., Ltd. as a measuring device.

(Polymerization conversion)
First, a part of the obtained slurry was collected and precisely weighed and dried in a hot air drier at 120 ° C. for 1 hour, and the weight after drying was precisely weighed as a solid content. Next, the ratio of the result of precise weighing before and after drying was determined as the ratio of solid components in the slurry. Finally, using this solid component ratio, the polymerization conversion rate was calculated by the following calculation formula. In this calculation formula, the chain transfer agent was handled as a charged monomer.
Polymerization conversion rate (%)
= [(Total weight of charged raw materials x solid component ratio-total weight of raw materials other than water and monomer)
/ Charged monomer weight] x 100

(Graft rate)
2 g of the rubber-containing copolymer obtained was dissolved in 50 ml of methyl ethyl ketone, and centrifuged for 1 hour at a rotation speed of 30000 rpm using a centrifuge (manufactured by Hitachi Koki Co., Ltd., CP60E). Minutes were separated (total of 3 sets of centrifugation work). The graft ratio was calculated by the following formula using the obtained insoluble matter.
Graft rate (%) = {(weight of methyl ethyl ketone insoluble matter−weight of crosslinked polymer layer) / weight of crosslinked polymer layer} × 100
The weight of the crosslinked polymer layer is the charged weight of the monofunctional monomer constituting the crosslinked polymer layer.

(Imidation rate)
The imidation ratio was calculated as follows using IR. The product pellets were dissolved in methylene chloride, and the IR spectrum of the solution was measured at room temperature using a TravelIR manufactured by SensIR Technologies. From the obtained IR spectrum, and the absorption intensity attributable to the ester carbonyl group of 1720cm ^-1 (Absester), the imidization ratio from the ratio of the absorption intensity attributable to the imide carbonyl group of ^{1660cm -1 (Absimide) (Im%} ( IR)). Here, the “imidation rate” refers to the ratio of the imide carbonyl group in the total carbonyl group.

(Content of glutarimide unit)
^{Using 1} H-NMR BRUKER Avance III (400 MHz), ¹ H-NMR measurement of the resin is performed to determine the content (mol%) of each monomer unit such as glutarimide unit or ester unit in the resin, and the content The amount (mol%) was converted to content (% by weight) using the molecular weight of each monomer unit.

(Acid value)
0.3 g of the obtained glutarimide acrylic resin was dissolved in a mixed solvent of 37.5 ml of methylene chloride and 37.5 ml of methanol. After adding 2 drops of phenolphthalein ethanol solution, 5 ml of 0.1N sodium hydroxide aqueous solution was added. Excess base was titrated with 0.1N hydrochloric acid and the acid value was calculated as the difference in milliequivalents between the added base and the hydrochloric acid used to reach neutralization.

(Glass-transition temperature)
Using a differential scanning calorimeter (DSC) SSC-5200 manufactured by Seiko Instruments Inc., the sample was once heated to 200 ° C. at a rate of 25 ° C./minute, held for 10 minutes, and then at a rate of 25 ° C./minute to 50 ° C. Measurement is performed while the temperature is raised to 200 ° C. at a rate of temperature increase of 10 ° C./min through preliminary adjustment to lower the temperature, and an integral value is obtained from the obtained DSC curve (DDSC), and the glass transition temperature is determined from the maximum point. Asked.

(Film thickness)
The film thickness was measured using a Digimatic Indicator (manufactured by Mitutoyo Corporation).

(Oriented birefringence of film)
A test piece of 40 mm × 40 mm was cut out from the film (film thickness 125 μm), and using an automatic birefringence meter (KOBRA-WR manufactured by Oji Scientific Co., Ltd.) at a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%, a wavelength of 590 nm, Measurement was performed at an incident angle of 0 °. At the same time, the in-plane retardation Re and the thickness direction retardation Rth (incident angle 40 °) were also measured.

(Evaluation of convex foreign matter)
1 m ² minutes were cut out from the obtained film, and convex objects of 20 μm or more were counted by observation with a microscope, etc., and totaled to obtain the number of convex foreign substances.
○: Less than 100 pieces / m ² ×: 100 pieces / m ² or more

(Evaluation of phase difference unevenness (confirmation of light and dark difference in crossed Nicols state))
A backlight, a polarizing plate, an evaluation film, and a polarizing plate are arranged in this order, and the presence or absence of a light / dark difference is visually confirmed in a state where the polarizing plates are inclined by 90 ° to each other (crossed Nicol state). It was judged that there was phase difference unevenness. In Table 1, “◯” indicates that there is phase difference unevenness, and “X” indicates that there is no phase difference unevenness.

(Production Example 1)
<Manufacture of glutarimide acrylic resin>
A glutarimide acrylic resin (A1) was produced using polymethyl methacrylate as the raw material resin and monomethylamine as the imidizing agent.

  In this production, a tandem reaction extruder in which two extrusion reactors were arranged in series was used.

  As for the tandem type reactive extruder, the meshing type co-directional twin-screw extruder having a diameter of 75 mm for both the first and second extruders and L / D (ratio of the length L to the diameter D of the extruder) of 74. The raw material resin was supplied to the raw material supply port of the first extruder using a constant weight feeder (manufactured by Kubota Corporation).

  The degree of vacuum of each vent in the first extruder and the second extruder was set to -0.095 MPa. Furthermore, the pressure control mechanism in the part connects the first extruder and the second extruder with a pipe having a diameter of 38 mm and a length of 2 m, and connects the resin discharge port of the first extruder and the raw material supply port of the second extruder. Used a constant flow pressure valve.

  The resin (strand) discharged from the second extruder was cooled by a cooling conveyor and then cut by a pelletizer to form pellets. Here, in order to determine the pressure in the component connecting the resin discharge port of the first extruder and the raw material supply port of the second extruder, or to determine the extrusion fluctuation, the discharge port of the first extruder, the first extruder and the first extruder Resin pressure gauges were provided at the center of the connecting parts between the two extruders and at the discharge port of the second extruder.

  In the 1st extruder, the polymethyl methacrylate resin (Mw: 105,000) was used as raw material resin, and the imide resin intermediate body 1 was manufactured using monomethylamine as an imidation agent. At this time, the temperature of the highest temperature part of the extruder was 280 ° C., the screw rotation speed was 55 rpm, the raw material resin supply amount was 150 kg / hour, and the addition amount of monomethylamine was 2.0 parts with respect to 100 parts of the raw material resin. The constant flow pressure valve was installed immediately before the raw material supply port of the second extruder, and the monomethylamine press-fitting portion pressure of the first extruder was adjusted to 8 MPa.

  In the second extruder, the imidizing agent and by-products remaining in the rear vent and the vacuum vent were devolatilized, and then dimethyl carbonate was added as an esterifying agent to produce an imide resin intermediate 2. At this time, each barrel temperature of the extruder was 260 ° C., the screw rotation speed was 55 rpm, and the addition amount of dimethyl carbonate was 3.2 parts with respect to 100 parts of the raw resin. Furthermore, after removing the esterifying agent with a vent, it was extruded from a strand die, cooled in a water tank, and then pelletized with a pelletizer to obtain a glutarimide acrylic resin.

  The obtained glutarimide acrylic resin is an acrylic resin in which a glutamylimide unit represented by the general formula (1) and a (meth) acrylic acid ester unit represented by the general formula (2) are copolymerized.

  For the glutarimide acrylic resin, the imidization rate, glutarimide unit content, acid value, glass transition temperature, and refractive index were measured according to the above methods. As a result, the imidation ratio was 13%, the content of glutarimide units was 7% by weight, the acid value was 0.4 mmol / g, the glass transition temperature was 130 ° C., and the refractive index was 1.50.

(Production Example 2)
<Production of rubber-containing copolymer>
The following substances were charged into an 8 L polymerization apparatus equipped with a stirrer.
Deionized water 200 parts Polyoxyethylene lauryl ether sodium phosphate 0.05 parts sodium formaldehyde sulfoxylate 0.11 parts ethylenediaminetetraacetic acid-2-sodium 0.004 parts ferrous sulfate 0.001 parts Was sufficiently replaced with nitrogen gas to make it substantially free of oxygen, the internal temperature was set to 40 ° C., and 45.266 parts of the following raw material mixture (B-1) was continuously added over 135 minutes.
Total amount of monofunctional monomer 45 parts, butyl acrylate 90%
・ Methyl methacrylate 10%
Allyl methacrylate 0.225 parts cumene hydroperoxide 0.041 parts (B-1) 12 minutes, 24 minutes and 36 minutes after the start of addition, sodium polyoxyethylene lauryl ether phosphate (polyoxyethylene lauryl ether phosphate) (Toho Chemical Co., Ltd., trade name: sodium salt of phosphanol RD-510Y) 0.2 parts each was added to the polymerization machine. (Polymer of (B-1)) was obtained, and the polymerization conversion was 99.4%.

Thereafter, the internal temperature was set to 60 ° C., 0.2 part of sodium formaldehyde sulfoxide was charged, and then 55.254 parts of the raw material mixture of the following hard polymer layer (B-2) was continuously added over 165 minutes. The polymerization was continued for 1 hour to obtain a graft copolymer latex.
Total amount of monofunctional monomer 55 parts, methyl methacrylate 57.8%
・ Butyl acrylate 4%
・ Benzyl methacrylate 38.2%
Cumene hydroperoxide 0.254 parts The polymerization conversion rate was 100.0%. The obtained latex was salted out and coagulated with magnesium sulfate, washed with water and dried to obtain a white powdery rubber-containing copolymer.

  The average particle diameter of the rubber particles (polymer of B-1) of the rubber-containing copolymer was 133 nm. The graft ratio of the rubber-containing copolymer was 77%.

Example 1
A glutarimide acrylic resin (A1) obtained in Production Example 1 was prepared using a single screw extruder using a full flight screw with a diameter of 40 mm, a set temperature of the temperature adjustment zone of the extruder was 255 ° C., and a screw rotation speed was 52 rpm. ) And a rubber-containing copolymer obtained in Production Example 2 at a rate of 47% were fed at a rate of 10 kg / hr. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and pelletized with a pelletizer.

  Using the 90 mmφ single-screw melt-kneading extruder (made by Hitachi Zosen Corporation) whose barrel temperature was adjusted to 230 ° C., the obtained resin pellet was equipped with a leaf disk filter with an opening of 5 μm and attached to the tip. A film having a thickness of 125 μm is melted and extruded by sandwiching the extruded sheet-like molten resin between two rolls, a cast roll and a touch roll, and then cooled by a cooling roll. Manufactured. The cast roll used had a surface roughness Ra of 0.01 μm, and the touch roll had a surface roughness Ra of 0.04 μm.

The linear pressure P / H between the cast roll and the touch roll with respect to the molten resin in the film forming process of this example was 250 N / cm. Moreover, the cast roll temperature in a present Example was 85 degreeC, and the touch roll temperature was 50 degreeC.
The orientation birefringence of the obtained film was + 0.1 × 10 ⁻⁴ , the number of convex foreign matters in the film was 100 or less, and there was no color unevenness in the crossed Nicols state.

(Comparative Example 2)
In Example 1, a film was produced in the same manner as in Example 1 except that the extruded sheet-like molten resin was not sandwiched between two rolls, a cast roll and a touch roll.
The orientation birefringence of the obtained film was + 0.1 × 10 ⁻⁴ , the number of convex foreign matters in the film was 100 or more, and there was no color unevenness in the crossed Nicols state.

1. Discharge port Molten resin Touch roll 4. Cast roll

Claims (11)

A method for producing an optical film comprising a resin composition containing a thermoplastic resin and a rubber-containing copolymer, the step of extruding the resin composition in a sheet form from a T-die, and the sheet-like resin composition A method for producing an optical film having an orientation birefringence of −2.0 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ , which includes a step of sandwiching the film with a roll and / or a belt.   The manufacturing method of the optical film of Claim 1 whose surface of the said roll and / or belt is a mirror surface.   The method for producing an optical film according to claim 1, further comprising a step of filtering the resin composition melted by a polymer filter.   The method for producing an optical film according to claim 1, wherein the orientation birefringence of the thermoplastic resin and the rubber-containing copolymer has different signs. 5. The orientation birefringence of the thermoplastic resin and the rubber-containing copolymer is −2.0 × 10 ⁻⁴ to 2.0 × 10 ⁻⁴ . 5. Manufacturing method of optical film.   The rubber-containing polymer has a (meth) acrylic cross-linked polymer layer and a hard polymer layer containing, in a structural unit, a vinyl monomer having an alicyclic structure, a heterocyclic structure or an aromatic group. The manufacturing method of the optical film in any one of Claims 1-5. The manufacturing method of the optical film in any one of Claims 1-6 in which the said rubber-containing polymer has a hard polymer layer which contains the monomer represented by following formula (4) in a structural unit.

(In the above formula (4), R ⁹ represents a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms. R ¹⁰ represents a substituted or unsubstituted carbon. An aromatic group having 1 to 24 carbon atoms, or a substituted or unsubstituted alicyclic group having 1 to 24 carbon atoms, having a monocyclic structure or a heterocyclic structure, wherein l is an integer of 1 to 4; M represents an integer of 0 to 1. n represents an integer of 0 to 10.)   The rubber-containing polymer is a hard polymer contained in at least one structural unit selected from the group consisting of benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and phenoxyethyl (meth) acrylate. The manufacturing method of the optical film in any one of Claims 1-7 which has a layer.   The method for producing an optical film according to claim 1, wherein the thermoplastic resin is an acrylic thermoplastic resin.   The thermoplastic resin is a maleimide acrylic resin, a glutarimide acrylic resin, a lactone ring-containing acrylic polymer, a styrene monomer and a styrene polymer obtained by polymerizing other monomers copolymerizable therewith. A partially hydrogenated styrene polymer obtained by partial hydrogenation of an aromatic ring, an acrylic polymer containing a cyclic acid anhydride repeating unit, and an acrylic polymer containing a hydroxyl group and a carboxyl group The manufacturing method of the optical film in any one of Claims 1-9 containing at least 1 sort (s) selected from a group. The thermoplastic resin includes a glutarimide acrylic resin having a unit represented by the following general formula (1) and a unit represented by the following general formula (2). The manufacturing method of the optical film of description.

(In the formula, R ¹ and R ² are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ is hydrogen, an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 3 to 12 carbon atoms. A cycloalkyl group or a substituent of 5 to 15 carbon atoms containing an aromatic ring.)

(In the formula, R ⁴ and R ⁵ are each independently hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ⁶ is an alkyl group having 1 to 18 carbon atoms or a cycloalkyl having 3 to 12 carbon atoms. Or a substituent having 5 to 15 carbon atoms including an aromatic ring.)

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