JP2022072382A - Methacrylic based copolymer, composition, molding, film, method for manufacturing sheet, and laminate - Google Patents

Abstract

To provide a methacrylic based copolymer excellent in heat resistance, small in both orientation birefringence and photoelastic birefringence and high in surface hardness; a composition, molding, film including the copolymer; a method for manufacturing a sheet; and a laminate.SOLUTION: A methacrylic based copolymer includes: a methyl methacrylate unit; a α-methylstyrene unit; a maleic anhydride unit; and a structural unit (R) including at least one ring structure selected from a group consisting of the following formulae (1)-(3) in a main chain. The absolute value of a photoelastic coefficient is 3.0×10-12 Pa-1 or less; the absolute value of orientation birefringence of a stretched film obtained by stretching a sheet having an area of 20 mm×40 mm and a thickness of 1.0 mm by 100% in one direction at a temperature higher by 10°C than the glass transition temperature and at a speed of 3 mm/minute is 2.5×10-4 or less, (where, the formulae (1)-(3) are as described in the specification.).SELECTED DRAWING: None

Description

The present invention relates to a methacrylic copolymer, a composition, a molded product, a method for producing a film or a sheet, and a laminate.

(Meta) Acrylic resin is widely used as a material for constituting optical members such as lenses, prisms, retardation films, light guide plates, light diffusing films, and polarizing plate protective films because of its excellent transparency and low optical distortion. .. In these applications, the birefringence of the part affects the performance of the device. For example, in a device such as a liquid crystal display device, an optical disk device, or a projection screen, the presence of a birefringent film, lens, or the like in the optical path adversely affects the image quality and signal reading performance. Therefore, in recent years, there has been a demand for a material having birefringence as small as possible.

The birefringence exhibited by the resin includes orientation birefringence due to the orientation of the polymer molecule and photoelastic birefringence due to stress, which are polymer-specific properties derived from the primary structure of the polymer.

In a general polymer repeating unit, the polarizabilities in the main chain direction and the side chain direction are different, and the polarizability has anisotropy. In the state where the polymer is not strained, the repeating units are randomly oriented, so that the anisotropy of the repeating units cancels each other out and the macroscopic refractive index becomes isotropic. However, in general polymer molding processes, such as extrusion molding and stretching processes during polymer film production, or injection molding processes often used during the production of various optical components, processes involving material flow may occur. Orientation of the polymer backbone occurs, and the orientation is fixed and remains on the optical member. In the state where the main chain is oriented, the microscopic isotropic property is broken, and the polarizability anisotropy derived from the repeating unit of the polymer is developed in the optical member according to the degree of the orientation of the main chain. Such birefringence caused by the orientation of the polymer main chain is called orientation birefringence. Here, when the refractive index increases in the direction parallel to the orientation direction of the main chain, it is expressed as positive orientation birefringence, and when the refractive index increases in the orthogonal direction, it is expressed as negative orientation birefringence.

It is also known that birefringence occurs when a polymer is elastically deformed, which is called photoelastic birefringence. For example, when an optical member containing a polymer receives an external force while being fixed to an instrument and is elastically deformed, photoelastic birefringence corresponding to the photoelastic coefficient is exhibited. In addition, strain remaining in the material due to volume shrinkage when cooling from a molding temperature equal to or higher than the glass transition temperature of the polymer during molding of the optical member can also cause photoelastic birefringence to occur.

Various attempts have been made to suppress the birefringence of the polymer by simultaneously reducing the orientation birefringence and the photoelastic birefringence.

As a method for obtaining a material having low birefringence, a plurality of monomers having different codes of the intrinsic birefringence and the photoelastic coefficient as a homopolymer are combined, and the composition is adjusted so that the intrinsic birefringence and the photoelastic coefficient are offset. A technique for reducing orientation birefringence and photoelastic birefringence as a copolymer is known. For example, Patent Document 1 discloses that a copolymer containing a methyl methacrylate unit, a methacrylic acid 2,2,2-trifluoroethyl unit, and a benzyl methacrylate unit can simultaneously reduce orientation birefringence and photoelastic birefringence. Has been done. However, since the glass transition temperature of the resin is low, the heat resistance is inferior, and there is a problem that the application to electronic devices and in-vehicle applications that are expected to be used under high temperature conditions is limited.

Therefore, as a resin having heat resistance and reduced birefringence, Patent Document 2 proposes a (meth) acrylic resin containing a glutarimide unit. However, although this resin has low orientation birefringence, it cannot sufficiently reduce photoelastic birefringence, so it is said that birefringence develops due to residual strain of the molded product and stress applied when the optical member is attached to the device. There was a challenge.

In response to these requests, as a resin having heat resistance and reduced both orientation double refraction and photoelastic double refraction, a methacrylate monomer unit, a vinyl aromatic monomer unit, and a methacrylate monomer having an aromatic group. Acrylic thermoplastic resin containing a weight unit, a cyclic acid anhydride repeating unit (Patent Document 3), an N-substituted or unsubstituted glutalimide unit, a (meth) acrylic acid ester monomer unit, a vinyl aromatic unit. An imide resin containing a body unit (Patent Document 4) is disclosed. However, according to the studies by the authors, the resins of Patent Documents 3 and 4 have insufficient surface hardness, and there are still problems in their application as optical members.

Japanese Unexamined Patent Publication No. 2006-308682 Japanese Unexamined Patent Publication No. 2006-328330 WO2009 / 084541 A1 WO2005 / 054311 A1

An object of the present invention is a methacrylic copolymer having excellent heat resistance, small orientation birefringence and small photoelastic birefringence, and high surface hardness, and a composition, molded product, film or sheet containing the copolymer. Is to provide a manufacturing method of the above, a laminated body.

As a result of diligent studies to achieve the above object, the present invention has been completed including the following embodiments.
[1]
A methyl methacrylate unit, an α-methylstyrene unit, a maleic anhydride unit, and a structural unit (R) having at least one ring structure selected from the group consisting of the following formulas (1) to (3) in the main chain. The absolute value of the photoelastic coefficient is 3.0 × ^10-12 Pa ^-1 or less, and a sheet of 20 mm × 40 mm × thickness 1.0 mm is 3 mm / at a temperature 10 ° C higher than the glass transition temperature. A methacrylic copolymer having an absolute value of orientation and double refraction of a stretched film obtained by stretching 100% in one direction at a rate of minutes of 2.5 × 10 ^-4 or less.

(In formula (1), R ¹¹ and R ¹² are independently hydrogen atoms or alkyl groups having 1 to 5 carbon atoms, respectively.)

(In the formula (2), R ²¹ and R ²² are independently hydrogen atoms or methyl groups, respectively, and R ²³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or It is an organic group having 6 to 15 carbon atoms including an aromatic ring.)

(In the formula (3), R ³¹ and R ³² are independently hydrogen atoms, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms, and R ³³ is a hydrogen atom and 1 carbon atom. It is an alkyl group of ~ 18, a cycloalkyl group having 3 to 12 carbon atoms, or an organic group having 6 to 15 carbon atoms including an aromatic ring.)
[2]
At least one structural unit (R) selected from the group consisting of N-substituted or unsubstituted glutarimide units represented by the formula (2) or N-substituted or unsubstituted maleimide units represented by the formula (3). The methacrylic copolymer according to [1], which is the structural unit of.
[3]
The methacrylic copolymer according to [1] or [2], wherein the glass transition temperature is 120 ° C. or higher.
[4]
It contains 22 to 87% by mass of methyl methacrylate unit, 7 to 30% by mass of α-methylstyrene unit, 1 to 30% by mass of maleic anhydride unit, and 3 to 70% by mass of structural unit (R) [1]. ] To [3]. The methacrylic copolymer according to any one of.
[5]
A resin composition containing the methacrylic copolymer according to any one of [1] to [4].
[6]
A molded product containing the methacrylic copolymer according to any one of [1] to [4] or the composition according to [5].
[7]
The molded product according to [6], wherein the molded product is a film or a sheet.
[8]
A method for producing a film or sheet, which comprises a step of molding the methacrylic copolymer according to any one of [1] to [4] or the composition according to [5] into a film or sheet by a melt molding method.
[9]
A method for producing a film or sheet, which comprises a step of molding the methacrylic copolymer according to any one of [1] to [4] or the composition according to [5] into a film or sheet by a solution casting method.
[10]
A laminate having at least one layer composed of the methacrylic copolymer according to any one of [1] to [4] or the film or sheet containing the composition according to [5].

According to the present invention, a methacrylic copolymer having excellent heat resistance, small orientation birefringence and small photoelastic birefringence, and high surface hardness, and a composition, molded product, film or sheet containing the copolymer. The manufacturing method and laminate can be obtained.

(Metal-based copolymer)
The methacrylic copolymer of the present invention contains a methyl methacrylate unit, an α-methylstyrene unit, a maleic anhydride unit, and a structural unit (R).

In the methacrylic copolymer of the present invention, the ratio of the methyl methacrylate unit is preferably 22 to 87% by mass, more preferably 27 to 85% by mass, still more preferably 32 to 80% by mass with respect to the total structural units. Is. If the proportion of methyl methacrylate units is less than this range, the total light transmittance of the obtained methacrylic acid copolymer deteriorates, and if the proportion of methyl methacrylate units is higher than this range, the obtained methacrylic acid copolymer weight is deteriorated. The heat resistance of the coalescence is low.

In the methacrylic copolymer of the present invention, the ratio of α-methylstyrene units is preferably 7 to 30% by mass, more preferably 8 to 27% by mass, still more preferably 11 to 25% by mass with respect to the total structural units. %. If the proportion of α-methylstyrene units is less than this range, the surface hardness of the obtained methacrylic copolymer will be low. Further, when the ratio of the α-methylstyrene unit is larger than this range, the polymerizability of the obtained methacrylic copolymer is low, and the productivity is lowered.

In the methacrylic copolymer of the present invention, the ratio of maleic anhydride units is preferably 1 to 29.5% by mass, more preferably 2 to 27% by mass, and further preferably 3 to 25 with respect to all structural units. It is mass%. If the proportion of maleic anhydride units is less than this range, the compound refraction of the obtained methacrylic acid copolymer will be high, and if the proportion of maleic anhydride units is more than this range, the obtained methacrylic acid copolymer will have a higher compound refraction. Heat resistance and melt viscosity increase unnecessarily, and molding processability deteriorates. When the structural unit (R) includes a glutarimide unit represented by the formula (2) and a maleimide unit represented by the formula (3) (R ³¹ = R ³² = H and R ³³ = R ²³ ), this In the methacrylic copolymer of the present invention, the ratio of the maleic anhydride unit is preferably 0.5 to 27% by mass, more preferably 1 to 25% by mass, and further preferably 2 with respect to the total structural units. It is ~ 23% by mass.

The structural unit (R) is a structural unit having at least one ring structure selected from the group consisting of an anhydrous glutaric acid unit, an N-substituted or unsubstituted glutarimide unit, and an N-substituted or unsubstituted maleimide unit in the main chain. ..

The glutaric anhydride unit is a unit having a 2,6-dioxodihydropyrandiyl structure. Examples of the unit having a 2,6-dioxodihydropyranziyl structure include a structural unit represented by the formula (1).

In the formula (1), R ¹¹ and R ¹² are independently hydrogen atoms or alkyl groups having 1 to 5 carbon atoms, and are preferably methyl groups.

The unit having a 2,6-dioxodihydropyranjiyl structure is derived from the methods described in JP-A-2007-197703, JP-A-2010-96919, etc., for example, two adjacent (meth) acrylic acids. It can be contained in a methacrylic copolymer by intramolecular cyclization of structural units, intramolecular cyclization of structural units derived from (meth) acrylic acid and structural units derived from methyl (meth) acrylate. ..

An N-substituted or unsubstituted glutarimide unit is a unit having an N-substituted or unsubstituted 2,6-dioxopiperidinediyl structure.

Examples of the unit having an N-substituted or unsubstituted 2,6-dioxopiperidinediyl structure include a structural unit represented by the formula (2).

In the formula (2), R ²¹ and R ²² are independently hydrogen atoms or methyl groups, and are preferably methyl groups. R ²³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an organic group having 6 to 15 carbon atoms including an aromatic ring, preferably a hydrogen atom, a methyl group, or n. -A butyl group, a cyclohexyl group or a benzyl group, more preferably a methyl group, an n-butyl group or a cyclohexyl group.

The structural unit represented by the formula (2) may be produced, for example, by the reaction of the corresponding acid anhydride (1a) and the imidizing agent represented by R ²³ -NH ₂ as shown in the scheme (i). Often, it may be produced by an intramolecular cyclization reaction of a copolymer having a partial structure of the formula (4). It is preferable to heat the structural unit represented by the formula (4) in order to convert it into the structural unit represented by the formula (2) by an intramolecular cyclization reaction.
Scheme (i)

(In the formula, R ²¹ , R ²² , and R ²³ are as defined above.)
The N-substituted or unsubstituted glutarimide unit is the method described in WO2005 / 10838A1, JP-A-2010-254742, JP-A-2008-273140, JP-A-2008-274187, and the like, specifically, adjacent to each other. Structural units or glutaric acid anhydride units derived from two matching methyl methacrylates include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, n-hexylamine and the like. Arophilic hydrocarbon group-containing amines such as aliphatic hydrocarbon group-containing amines, aniline, toluidine, and trichloroaniline, alicyclic hydrocarbon group-containing amines such as cyclohexylamine, urea, 1,3-dimethylurea, 1,3. -It can be obtained by reacting with an imidizing agent such as diethylurea and 1,3-dipropylurea. Of these, methylamine is preferred.

The N-substituted or unsubstituted maleimide unit is a unit having an N-substituted or unsubstituted 2,5-dioxo-2,5-dihydropyrrole-3,4-diyl structure.

Examples of the unit having an N-substituted or unsubstituted 2,5-dioxo-2,5-dihydropyrrole-3,4-diyl structure include a structural unit represented by the formula (3).

In the formula (3), R ³¹ and R ³² are independently hydrogen atoms, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms, and R ³³ is a hydrogen atom and 1 to 12 carbon atoms. It is an alkyl group having 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an organic group having 6 to 15 carbon atoms containing an aromatic ring.

The method for forming the N-substituted or unsubstituted maleimide unit is not particularly limited, and may be formed by a method of copolymerizing the corresponding N-substituted or unsubstituted maleimide monomer. Examples of the N-substituted or unsubstituted maleimide monomer include maleimide; N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N. -S-butylmaleimide, Nt-butylmaleimide, Nn-pentylmaleimide, Nn-hexylmaleimide, Nn-heptylmaleimide, Nn-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide N-alkylmaleimide such as N-cyclopentylmaleimide, N-cyclohexylmaleimide, 1-cyclohexyl-3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1 -Phenyl-1H-pyrol-2,5-dione, 1-cyclohexyl-3-phenyl-1H-pyrol-2,5-dione, 1-cyclohexyl-3,4-diphenyl-1H-pyrol-2,5-dione N-Cycloalkylmaleimide, etc .; N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N- (4-chlorophenyl) maleimide, N- (4-bromophenyl) maleimide, N- (2-methylphenyl) maleimide, etc. , N- (2-ethylphenyl) maleimide, N- (2-methoxyphenyl) maleimide, N- (2-nitrophenyl) maleimide, N- (2,4,6-trimethylphenyl) maleimide, N- (4-) Benzylphenyl) maleimide, N- (2,4,6-tribromophenyl) maleimide, N-naphthylmaleimide, N-anthrasenylmaleimide, 3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1,3-diphenyl-1H-pyrrole-2,5-dione, 1,3,4-triphenyl-1H-pyrrole-2 , 5-Dione and the like N-arylmaleimide; N-benzylmaleimide and the like. Among these monomers, N-methylmaleimide, N-ethylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, and N-benzylmaleimide are selected from the viewpoint of weather resistance of methacrylic copolymers. Preferably, N-methylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide are particularly preferable.

The N-substituted or unsubstituted maleimide unit can also be obtained by reacting an imidizing agent with the method described in JP-A-2006-124592, specifically, a maleic anhydride unit. Examples of the imidizing agent include aliphatic hydrocarbon group-containing amines such as ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine and n-hexylamine, and aniline. Aromatic hydrocarbon group-containing amines such as toluidine, trichloroaniline, benzylamine, alicyclic hydrocarbon group-containing amines such as cyclohexylamine, urea, 1,3-dimethylurea, 1,3-diethylurea, 1,3- Examples thereof include dipropylurea, and among these imidizing agents, methylamine is preferable.

In the methacrylic copolymer of the present invention, the ratio of the structural unit (R) is preferably 3 to 70% by mass, more preferably 5 to 65% by mass, and further preferably 8 to 60% by mass with respect to all the structural units. %. When the ratio of the structural unit (R) is within the above range with respect to all the structural units, a methacrylic copolymer having high heat resistance, suitable control of birefringence of the resin, and excellent molding processability can be obtained. It is preferable because it can be obtained.

The methacrylic copolymer of the present invention may optionally contain other copolymerizable vinyl-based monomer units in addition to the methyl methacrylate unit, α-methylstyrene unit, maleic anhydride unit, and structural unit (R). It may be included. Other copolymerizable vinyl-based monomers include methacrylic acid alkyl esters other than methyl methacrylate such as ethyl methacrylate and butyl methacrylate; methacrylic acid aryl esters such as phenyl methacrylate; cyclohexyl methacrylate and methacrylic acid. Methacrylic acid cycloalkyl ester such as norbornenyl acid; Acrylic acid alkyl ester such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate; Acrylic acid aryl ester such as phenyl acrylate; Cyclohexyl acrylate, acrylate Acrylic acid cycloalkyl ester such as norbornenyl; aromatic vinyl monomer other than α-methylstyrene such as styrene; acrylamide; methacrylicamide; vinyl cyanide monomer such as acrylonitrile and methacrylic nitrile; Examples thereof include vinyl monomers having only one sex alkenyl group. Of these monomers, acrylic acid alkyl esters, aromatic vinyl monomers other than α-methylstyrene, and vinyl cyanide monomers are preferable, from the viewpoint of highly controlling the double refraction of the methacrylic copolymer. Methyl acid, styrene and acrylonitrile are more preferred, and styrene is even more preferred.

In the methacrylic copolymer of the present invention, the proportion of other copolymerizable vinyl-based monomer units is preferably 30% by mass or less with respect to the total structural units.

The methacrylic copolymer of the present invention has a weight average molecular weight (Mw) of preferably 40,000 to 200,000, more preferably 50,000 to 1,800,000, still more preferably 55,000 to 1,600,000. When Mw is 40,000 or more, the strength and toughness of the molded product of the present invention are improved. When Mw is 200,000 or less, the fluidity of the methacrylic copolymer of the present invention is improved, and the molding processability is improved.

The weight average molecular weight (Mw) is a value calculated by converting a chromatogram measured by gel permeation chromatography (GPC) into a molecular weight of standard polystyrene.

The methacrylic copolymer of the present invention has an acid value of preferably 0.01 to 0.30 mmol / g, more preferably 0.05 to 0.28 mmol / g. The acid value is a value proportional to the content of the carboxylic acid unit and the carboxylic acid anhydride unit in the methacrylic copolymer. The acid value can be calculated, for example, by the method described in JP-A-2005-23272. When the acid value is within the above range, the balance between heat resistance, mechanical properties, and molding processability is excellent.

The methacrylic copolymer of the present invention has a glass transition temperature of preferably 120 ° C., more preferably 121 ° C., still more preferably 122 ° C. as a lower limit, and the upper limit is not particularly limited, but is preferably 200 ° C. be. The higher the glass transition temperature of the methacrylic copolymer, the less likely the molded body containing the methacrylic copolymer to be deformed or shrunk due to heat, that is, the higher the heat resistance.

In the present specification, the "glass transition temperature (Tg)" is measured according to JIS K7121. Specifically, the DSC curve is measured under the condition that the temperature is raised to 230 ° C., then cooled to room temperature, and then the temperature is raised from room temperature to 230 ° C. at 10 ° C./min. The intermediate point obtained from the DSC curve measured at the time of the second temperature rise is obtained as the "glass transition temperature (Tg)".

In the methacrylic copolymer of the present invention, the absolute value of the photoelastic coefficient measured by the method described later is preferably 3.0 × ^10-12 Pa ^-1 or less. More preferably, it is 2.5 × 10 ^-12 Pa ^-1 or less, and even more preferably 2.0 × 10 ^-12 Pa ^-1 or less.

The photoelastic coefficient is 100 N on a press-formed sheet made of a methacrylic copolymer having a width of 15 mm, a length of 60 mm, and a thickness of 1.0 mm, and the tension is increased by 10 N from 0 N at a chuck distance of 45 mm and a temperature of 23 ° C. When the tension is increased, the central part of the sheet is measured for double refraction at a temperature of 23 ° C and a D-line wavelength of Na, and the relationship between the measured stress and double refraction is first-ordered by the minimum square method. It is the slope calculated when it approximates the function. The stress is a value obtained by dividing the tension by the cross-sectional area of the sheet. The sheet cross-sectional area was calculated as the product of the sheet width of 15 mm and the thickness at the measurement point of the central portion of the sheet. _{Birefringence} is defined as the difference ( _Δn = n _p − no) between the refractive index n _p of light having a polarization plane parallel to the tensile direction and the refractive index no of light having a polarizing plane perpendicular to the tensile direction. Ru.

In the methacrylic copolymer of the present invention, the absolute value of the orientation birefringence measured by the method described later is preferably 2.5 × 10 ^-4 or less. It is more preferably 2.3 × 10 ^-4 or less, further preferably 2.2 × 10 ^-4 or less, and even more preferably 2.0 × 10 ^-4 or less.

Orientation double refraction is 100% in one direction at a rate of 3 mm / min at a temperature 10 ° C higher than the glass transition temperature of a press-formed sheet made of a methacrylic copolymer having a width of 20 mm, a length of 40 mm, and a thickness of 1.0 mm. The central portion of the stretched film obtained by stretching is a double refraction measured at a temperature of 23 ° C. and a D-line wavelength of Na without applying tension.
(Manufacturing method of methacrylic copolymer)
The methacrylic copolymer of the present invention is, for example, a copolymer of methyl methacrylate, α-methylstyrene, maleic anhydride, and an arbitrarily selected copolymerizable other vinyl-based monomer (hereinafter, precursor). It can be obtained by a method including a ring structure forming reaction (sometimes referred to as a body polymer).

That is, the method for producing a methacrylic copolymer of the present invention is 51 to 94% by mass of methyl methacrylate, 5 to 30% by mass of α-methylstyrene, 1 to 30% by mass of maleic anhydride, and other copolymerizable vinyl-based copolymers. A step of continuously supplying a reaction raw material containing a monomer mixture containing 0 to 30% by mass of a monomer, a radical polymerization initiator, and, if necessary, a chain transfer agent, to a tank-type reactor.
A step of bulk polymerization of the monomer mixture to a polymerization conversion rate of 30 to 60% by mass in a tank-type reactor to obtain a reaction product, and removal of the monomer mixture in the reaction product to obtain a precursor polymer. Getting process,
Each step can be carried out by a known technique, including a step of allowing the obtained precursor polymer to undergo a ring structure forming reaction.

The precursor polymer is produced by polymerizing from a reaction raw material containing a monomer mixture, a radical polymerization initiator and, if necessary, a chain transfer agent, and the monomer mixture contains methyl methacrylate as a monomer. The mixture contains 51 to 94% by mass, preferably 55 to 85% by mass. α-Methylstyrene is contained in an amount of 5 to 30% by mass, preferably 7 to 25% by mass. Maleic anhydride is contained in an amount of 1 to 30% by mass, preferably 3 to 25% by mass. The other copolymerizable vinyl-based monomer contains 0 to 30% by mass, preferably 3 to 25% by mass.

The monomer mixture may contain other copolymerizable vinyl-based monomers other than methyl methacrylate, α-methylstyrene and maleic anhydride, and specifically, the monomers exemplified above. The same applies to preferred examples.

The monomer mixture preferably has b * of -1 to 2, more preferably -0.5 to 1.5. When b * is in this range, it is advantageous to obtain a molded product having almost no coloring when the obtained methacrylic copolymer composition is molded with high production efficiency. Note that b * is a value measured in accordance with the International Commission on Illumination (CIE) standard (1976) or JIS Z-8722.

The polymerization initiator used is not particularly limited as long as it generates a reactive radical. Examples thereof include a peroxide-based initiator such as diisopropylbenzene hydroperoxide and t-butyl hydroperoxide, and an azo-based initiator such as 2,2'-azobis (2-methylpropionitrile).

The polymerization initiator used has an uncracked average initiator concentration in the range of 5.1 × ^10-5 to 2.4 × 10 ^-4 (mol / L) at the polymerization temperature in the tank reactor described later. Is desirable.

The amount of the polymerization initiator used is adjusted to the polymerization temperature and added to the monomer mixture so as to have the above-mentioned initiator concentration.

As the chain transfer agent used, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecyl mercaptan are preferable. These chain transfer agents can be used alone or in combination of two or more. The amount of the chain transfer agent used is preferably 0 to 1 part by mass, more preferably 0.01 to 0.8 part by mass, and further preferably 0.02 to 0.6 part by mass with respect to 100 parts by mass of the monomer mixture. It is a mass part.

In bulk polymerization, a solvent is not used in principle, but an organic solvent can be included in the reaction raw material as needed for the purpose of adjusting the polymerization reaction rate and the viscosity of the reaction solution. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone, and ethers such as tetrahydrofuran and 1,4-dioxane. Methyl ethyl ketone, methyl isobutyl ketone, and toluene are preferable from the viewpoints of solubility of the body and copolymer and ease of solvent recovery. The organic solvent may be used alone or in combination of two or more. The upper limit of the amount of the organic solvent used is preferably 30 parts by mass, more preferably 25 parts by mass, and further preferably 20 parts by mass with respect to 100 parts by mass of the monomer mixture. The lower limit of the amount of the organic solvent used is usually 0 parts by mass, preferably 1 part by mass.

The temperature in the tank reactor, that is, the temperature of the liquid in the reaction tank is preferably 110 to 140 ° C, more preferably 114 to 135 ° C. If the temperature is higher than this range, it is difficult to form a high molecular weight substance containing α-methylstyrene, which causes a decrease in heat resistance.

In the tank reactor, bulk polymerization is preferably carried out until the polymerization conversion is 30 to 65% by mass, preferably 35 to 60% by mass.

The average residence time (θ) of the reaction raw material in the tank reactor is preferably 1.5 to 5 hours, more preferably 2 to 4.5 hours, and further preferably 2.5 to 4 hours. If the average residence time is too short, the required amount of polymerization initiator will increase. Further, increasing the amount of the polymerization initiator makes it difficult to control the polymerization reaction and tends to make it difficult to control the molecular weight. On the other hand, if the average residence time is too long, it takes time for the reaction to reach a steady state, and the productivity tends to decrease. The average residence time can be adjusted by the capacity of the tank reactor and the supply amount of the reaction raw material.

Bulk polymerization is preferably carried out in an atmosphere of an inert gas such as nitrogen gas.

The preferred production method according to the present invention comprises the step of removing the monomer mixture in the reaction product. The removal method is not particularly limited, but a heat volatilization method is preferable. After removing the monomer mixture, the methacrylic copolymer composition can be pelletized or powdered according to a known method in order to facilitate handling as a molding material. The content of the monomer mixture in the obtained methacrylic resin composition is preferably 1% by mass or less, more preferably 0.5% by mass or less.

The precursor polymer has a glass transition temperature of preferably 114 ° C., more preferably 115 ° C., and even more preferably 117 ° C. as the lower limit. The glass transition temperature can be changed by adjusting the molecular weight, the amount of α-methylstyrene copolymerization, and the like. The higher the glass transition temperature of the precursor polymer, the better the heat resistance. Since the methacrylic copolymer obtained by using the precursor polymer having a high glass transition temperature has high heat resistance even if the amount of the structural unit (R) is small, it is unlikely to cause deterioration of the saturated water absorption rate.

The precursor polymer has a total content of 51 to 92% by mass of structural units derived from methyl methacrylate, a total content of 5 to 30% by mass of structural units derived from α-methylstyrene, and is derived from maleic anhydride. The total content of the structural unit is not particularly limited as long as it is 1 to 30% by mass. From the viewpoint of polymerizable property, transparency, etc., the total content of structural units derived from methyl methacrylate of the precursor polymer is preferably 51% by mass or more and 92% by mass or less, more preferably 55% by mass or more and 92% by mass or less. Most preferably, it is 60% by mass or more and 92% by mass or less.

From the viewpoint of heat resistance, polymerizability, water absorption, etc., the total content of structural units derived from α-methylstyrene of the precursor polymer is preferably 7 to 30% by mass, more preferably 8 to 27% by mass, and further. It is preferably 11 to 25% by mass. If the number of structural units derived from α-methylstyrene is less than this range, sufficient heat resistance cannot be obtained, and if it is more than this range, the polymerizable property is significantly lowered.

From the viewpoint of heat resistance and controllability of optical properties (particularly birefringence), the total content of structural units derived from maleic anhydride of the precursor polymer is preferably 1 to 30% by mass, more preferably 2 to 27. It is by mass, more preferably 3 to 27% by mass. If the number of structural units derived from maleic anhydride is less than this range, birefringence will be high, and if it is more than this range, the heat resistance and melt viscosity of the precursor polymer will be unnecessarily increased, and the ring structure formation reaction described later will be performed. Productivity is reduced.

The precursor polymer has a polystyrene-equivalent weight average molecular weight Mw of preferably 40,000 or more and 200,000 or less, more preferably 40,000 or more and 180,000 or less, and further preferably 50,000 or more and 160000 or less in a chromatogram obtained by gel permeation chromatography. .. If the weight average molecular weight Mw is smaller than this range, the obtained molded product becomes brittle, and if it is higher than this range, the productivity deteriorates. Mw can be controlled by adjusting the type, amount, addition timing, etc. of the polymerization initiator and chain transfer agent (arbitrary component) used in the production of the precursor polymer.

The ring structure forming reaction can be carried out using, for example, an extruder. Examples of the extruder include a single-screw extruder, a twin-screw extruder, a multi-screw extruder and the like. A twin-screw extruder is preferable from the viewpoint of mixing performance. The twin-screw extruder includes a non-meshing type same-direction rotation type, a meshing type same-direction rotation type, a non-meshing type different-direction rotation type, and a meshing type different-direction rotation type. The meshing type co-rotation type is preferable because it can rotate at high speed and can efficiently promote mixing. These extruders may be used alone or in series.

In the ring structure formation reaction using an extruder, for example, a precursor polymer as a raw material is charged from the raw material charging section of the extruder, the precursor polymer is melted, filled in a cylinder, and then an addition pump is used. By injecting an imidizing agent (arbitrary component) or the like into the extruder, the ring structure forming reaction can be allowed to proceed in the extruder. With an imidizing agent, the structural unit (R) comprises at least one of N-substituted or unsubstituted glutarimide units, N-substituted or unsubstituted maleimide units, and optionally lactone ring units and / or. It may contain glutaric anhydride units. Preferred imidizing agents are represented by R ²³ -NH ₂ (R ²³ is as defined above) or R ³³ -NH ₂ (R ³³ is as defined above). The imidizing agent is preferably used in an amount of 1.6 to 20 parts by mass with respect to 100 parts by mass of the methacrylic copolymer. When the amount of the imidizing agent used is within the above range, the by-product of the methacrylic acid amide unit can be suppressed. When the imidizing agent R ³³ -NH ₂ (R ³³ is as defined above) is used, a part of the maleic anhydride unit of the precursor polymer is represented by the formula (3) (maleimide unit). It is converted to R ³¹ = R ³² = H). In one embodiment of the invention, the imidizing agent R ²³ -NH ₂ (R ²³ is as defined above) is used to generate the structural unit (R) represented by formula (2). At the same time, a maleimide unit (R ³¹ = R ³² = H) represented by the formula (3) is generated, and the structural unit (R) includes the structural units of the formulas (2) and (3), and is R. ²³ = R ³³ .

The resin temperature of the reaction zone in the extruder is preferably in the range of 180 to 300 ° C, more preferably in the range of 200 to 300 ° C. If the resin temperature in the reaction zone is less than 180 ° C., the heat resistance of the methacrylic copolymer tends to decrease due to a decrease in the reaction efficiency of the ring structure forming reaction, a by-product of the methacrylic acid amide unit, and the like. When the resin temperature in the reaction zone exceeds 300 ° C., the resin is significantly decomposed, and the mechanical strength such as the tensile breaking strength of the molded body and the film made of the methacrylic copolymer tends to decrease. The reaction zone in the extruder is a region in the cylinder of the extruder from the injection position of the imidizing agent or the like to the resin discharge port (die portion).

By lengthening the reaction time in the reaction zone of the extruder, the ring structure forming reaction can be further promoted. The reaction time in the reaction zone of the extruder is preferably longer than 10 seconds, more preferably longer than 30 seconds. If the reaction time is 10 seconds or less, the ring structure formation reaction may hardly proceed.

The resin pressure in the extruder is preferably in the range of atmospheric pressure to 50 MPa, more preferably in the range of 1 to 30 MPa. If it is 50 MPa or more, the limit of the mechanical pressure resistance of a normal extruder is exceeded, and a special device is required, which is not preferable in terms of cost.

It is preferable to use an extruder having a vent hole capable of reducing the pressure below atmospheric pressure. According to such a configuration, unreacted substances, by-products such as methanol and monomers can be removed, and the breaking strength of the molded product containing the acrylic resin composition of the present invention tends to be improved.

For the ring structure formation reaction, instead of the extruder, for example, a horizontal twin-screw reactor such as Vivolac manufactured by Sumitomo Heavy Industries, Ltd. or a vertical twin-screw tank such as Super Blend can be used for high viscosity. The reaction device of the above can also be preferably used.

A carboxy group may be produced as a by-product in the methacrylic copolymer during the ring structure formation reaction. This carboxy group may be converted into an ester group by an esterifying agent, a catalyst or the like, if necessary. This can reduce the foaming of the resin when manufacturing the optical film. Such an ester group contains a methyl methacrylate unit from the viewpoint of reducing the melt viscosity of the resin during melt molding, the reactivity of esterification, and the heat resistance of the resin after esterification, although it varies depending on the esterifying agent and the catalyst used. It is preferable, and it is more preferable to contain both the methyl methacrylate unit and the ethyl methacrylate unit.

As the esterifying agent, dimethyl carbonate is preferable from the viewpoint of cost, reactivity and the like.

The amount of the esterifying agent added can be set, for example, so that the acid value of the methacrylic copolymer becomes a desired value.

In addition to the above esterifying agent, a catalyst can also be used in combination. The type of catalyst is not particularly limited, and examples thereof include amine compounds such as trimethylamine, triethylamine, monomethyldiethylamine, and dimethylmonoethylamine. Among these, triethylamine is preferable from the viewpoint of cost, reactivity and the like.

(Resin composition)
Additives generally used in resin compositions may be included as long as the object of the present invention is not impaired. Additives include fillers, antioxidants, thermal degradation inhibitors, UV absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, colorants, dyes, pigments, Examples thereof include light diffusing agents, organic dyes, matting agents, impact resistance modifiers, and phosphors. The total amount of such additives other than the filler is preferably 7% by mass or less, more preferably 5% by mass or less, still more preferably 4% by mass or less.

Examples of the filler include calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, magnesium carbonate and the like. The amount of the filler that can be contained in the methacrylic copolymer composition of the present invention is preferably 3% by mass or less, more preferably 1.5% by mass or less.

The antioxidant is effective in preventing oxidative deterioration of the resin by itself in the presence of oxygen. For example, phosphorus-based antioxidants, hindered phenol-based antioxidants, thioether-based antioxidants, and the like can be mentioned. These antioxidants may be used alone or in combination of two or more.

The heat deterioration inhibitor can prevent the heat deterioration of the resin by capturing the polymer radicals generated when exposed to high heat under a substantially oxygen-free state.

Examples of the heat deterioration inhibitor include 2-tert-butyl-6- (3'-tert-butyl-5'-methyl-hydroxybenzyl) -4-methylphenylacrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name: Smilizer GM). 2,4-Di-tert-amyl-6- (3', 5'-di-tert-amyl-2'-hydroxy-α-methylbenzyl) phenylacrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Smilizer GS), etc. Can be mentioned.

An ultraviolet absorber is a compound having the ability to absorb ultraviolet rays. The ultraviolet absorber is a compound that is said to have a function of mainly converting light energy into heat energy.

Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, malonic acid anilides, malonic acid esters, formamidines and the like. These may be used alone or in combination of two or more. Among these, benzotriazoles, triazines, or an ultraviolet absorber having a maximum molar extinction coefficient ε _max of 1200 dm ³ · mol ^-1 cm ^-1 or less at a wavelength of 380 to 450 nm is preferable.

The light stabilizer is a compound that is said to have a function of capturing radicals mainly generated by oxidation by light. Suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

Examples of the lubricant include stearic acid, behenic acid, stearoamic acid, methylenebisstearoamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, hydrogenated oil and the like.

Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; and glycerin higher fatty acid esters such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, it is preferable to use higher alcohols and glycerin fatty acid monoester in combination as a release agent. When the higher alcohols and the glycerin fatty acid monoester are used in combination, the ratio is not particularly limited, but the amount of the higher alcohols used: the amount of the glycerin fatty acid monoester used is 2.5: 1 to 3. 5: 1 is preferable, and 2.8: 1 to 3.2: 1 are more preferable.

As the polymer processing aid, polymer particles (non-crosslinked rubber particles) having a particle size of 0.05 to 0.5 μm, which can be usually produced by an emulsion polymerization method, are used. The polymer particles may be single-layer particles made of a polymer having a single composition ratio and a single extreme viscosity, or may be multilayer particles made of two or more kinds of polymers having different composition ratios or extreme viscosities. You may.

Antistatic agents include sodium heptyl sulfonate, sodium octyl sulfonate, sodium nonyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium cetyl sulfonate, sodium octadecyl sulfonate, sodium diheptyl sulfonate, heptyl sulfonic acid. Potassium, potassium octyl sulfonate, potassium nonyl sulfonate, potassium decyl sulfonate, potassium dodecyl sulfonate, potassium cetyl sulfonate, potassium octadecyl sulfonate, potassium diheptyl sulfonate, lithium heptyl sulfonate, lithium octyl sulfonate, nonyl sulfonate Examples thereof include alkyl sulfonates such as lithium acid, lithium decyl sulfonate, lithium dodecyl sulfonate, lithium cetyl sulfonate, lithium octadecyl sulfonate, and lithium diheptyl sulfonate.

Examples of the flame retardant include magnesium hydroxide, aluminum hydroxide, hydrated aluminum silicate, hydrated magnesium silicate, metal hydrate having a hydroxyl group or crystalline water such as hydrotalcite, and phosphoric acid such as polyphosphate amine and phosphate ester. Examples thereof include compounds, silicon compounds and the like, such as trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate and dimethyl ethyl. Phosphate-based flame retardants such as phosphate, methyldibutyl phosphate, ethyldipropyl phosphate, hydroxyphenyldiphenyl phosphate and the like are preferred.

Dyes / pigments include red organic pigments such as parared, fire red, pyrazolone red, thioindico red, and perylene red, blue organic pigments such as cyanine blue and indanslen blue, and green organic pigments such as cyanine green and naphthol green. Pigments are mentioned, and one or more of these can be used.

As the organic dye, a compound having a function of converting ultraviolet rays into visible light is preferably used.

Examples of the light diffusing agent and the matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, barium sulfate and the like.

Examples of the fluorescent substance include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent whitening agents, and fluorescent bleaching agents.

The methacrylic copolymer composition of the present invention is not particularly limited depending on the production method thereof, and for example, the methacrylic copolymer of the present invention, an additive such as an ultraviolet absorber, and other polymers as needed. It can be manufactured by melt-kneading. The melt-kneading can be performed using, for example, a melt-kneading device such as a kneader ruder, an extruder, a mixing roll, or a Banbury mixer. The temperature at the time of kneading can be appropriately set according to the softening temperature of the methacrylic copolymer and other polymers, and can be set to, for example, 150 to 300 ° C. Further, the shear rate at the time of kneading can be set to, for example, 10 to 5000 sec ^-1 .

The methacrylic copolymer composition of the present invention can be in the form of pellets or the like in order to enhance convenience during storage, transportation, or molding.
(Molded body)
The molded product of the present invention contains the methacrylic copolymer or the methacrylic copolymer composition of the present invention. The method for producing the molded product of the present invention is not particularly limited. For example, T-die method (lamination method, coextrusion method, etc.), inflation method (coextrusion method, etc.), compression molding method, blow molding method, calendar forming method, vacuum forming method, injection molding method (insert method, two-color method, etc.) A melt molding method such as a press method, a core back method, a sandwich method, etc., and a solution casting method can be mentioned. Of these, the T-die method, the inflation method, the injection molding method, or the solution casting method is preferable from the viewpoint of high productivity, cost, and the like. The type of the molded body is not limited, but a film (a planar molded body having a thickness of 5 μm or more and 250 μm or less) or a sheet (a planar molded body thicker than 250 μm) is preferable.

In the molded product of the present invention, the average value of the absolute values of the in-plane phase difference (Re) of the molded product is preferably 10.0 nm or less, more preferably 6.0 nm or less as a value per 1 mm of thickness. Yes, more preferably 5.0 nm or less, and even more preferably 3.0 nm or less.

The film, which is one form of the molded product of the present invention, can be produced by a solution casting method, a melt casting method, an extrusion molding method, an inflation molding method, a blow molding method, or the like. Of these, the extrusion molding method or the solution casting method can be used from the viewpoint of obtaining a film having excellent transparency, improved toughness, excellent handleability, and an excellent balance between toughness and surface hardness and rigidity. Is preferable. The temperature of the molten resin discharged from the extruder is preferably set to 160 to 270 ° C, more preferably 220 to 260 ° C.

Of the extrusion molding methods, the T-die method is preferable from the viewpoint of obtaining a film having good surface smoothness, good mirror gloss, and low haze. In this T-die method, it is preferable that the molten resin discharged from the T-die via an extruder, a gear pump, a polymer filter, and a mixer is sandwiched between two or more mirror rolls or a mirror belt to form a film. Banks may or may not be formed when sandwiched between mirror rolls or mirror belts. The die has a function of automatically adjusting the lip opening, and the air gap is preferably 100 mm or less.

The mirror roll or mirror belt is preferably made of metal. As the mirror surface roll, a metal rigid body roll, a metal elastic body roll, or the like can be used, and it is preferable to use a metal bullet elastic body roll and a metal rigid body roll in combination. Further, it is preferable that the surface temperature of the mirror surface roll or the mirror surface belt is 130 ° C. or lower. Further, it is preferable that the surface temperature of at least one of the pair of mirror rolls or mirror belts is 60 ° C. or higher. When the surface temperature is set to such a value, the molten resin discharged from the extruder can be cooled at a speed higher than that of natural cooling, and it is easy to produce a film having excellent surface smoothness and low haze. The linear pressure between the pair of rolls or belts is preferably 10 N / mm or more, more preferably 30 N / mm or more. The thickness of the unstretched film obtained by extrusion molding is preferably 10 to 300 μm. The haze of the film is preferably 0.7% or less, more preferably 0.5% or less, still more preferably 0.3% or less at a thickness of 100 μm.

The unstretched film obtained as described above may be subjected to a stretching treatment. By the stretching treatment, the mechanical strength is increased, and a film that is not easily cracked can be obtained. The stretching method is not particularly limited, and examples thereof include a simultaneous biaxial stretching method, a sequential biaxial stretching method, and a tuber stretching method. From the viewpoint of being able to be uniformly stretched and obtaining a high-strength film, the lower limit of the temperature at the time of stretching is a temperature 10 ° C. higher than the glass transition temperature of the methacrylic copolymer or the methacrylic copolymer composition, and is at the time of stretching. The upper limit of the temperature is a temperature 40 ° C. higher than the glass transition temperature of the methacrylic copolymer or the methacrylic copolymer composition. Stretching is usually performed at 100-5000% / min. By performing heat fixation after stretching, a film having less heat shrinkage can be obtained. The thickness of the stretched film is preferably 10 to 200 μm.

A functional layer may be provided on the surface of a film which is a form of a molded product of the present invention. Examples of the functional layer include a hard coat layer, an anti-glare layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, an anti-static layer, an anti-fouling layer, and an easy-to-slip layer such as fine particles.

Further, in order to improve the adhesive strength with the functional layer on at least one side of the film of the present invention, or to improve the adhesive strength in laminating with another film via an adhesive or an adhesive, under. It is preferable to provide a coat layer.

The methacrylic copolymer or the methacrylic copolymer composition of the present invention is suitable as a molding material. The molded product of the present invention can be used as a member for various purposes. Specific uses include, for example, signboard parts and marking films such as advertising towers, stand signs, sleeve signs, column signs, roof signs; display parts such as showcases, dividers, and store displays; fluorescent lamp covers, mood lighting. Lighting parts such as covers, lamp shades, light ceilings, light walls, chandeliers; interior parts such as furniture, pendants, mirrors; doors, dome, safety window glass, partitions, staircase wainscots, balcony wainscots, roofs of leisure buildings, etc. Building parts; aircraft windshields, pilot visors, motorcycles, motor boat windshields, bus shading plates, automobile side visors, rear visors, head wings, headlight covers, automobile interior parts, automobile exterior parts such as bumpers, etc. Related parts; Electronic equipment parts such as audiovisual name plates, stereo covers, TV protective masks, vending machines, mobile phones, personal computers; Medical equipment parts such as incubators and roentgen parts; Machine covers, instrument covers, experimental equipment, rulers , Equipment-related parts such as dials and observation windows; Optical-related parts such as liquid crystal protective plates, light guide plates, light guide films, frennel lenses, lenticular lenses, front plates of various displays, diffuser plates; road signs, guide plates, curves Traffic-related parts such as mirrors and soundproof walls; Others, greenhouses, large water tanks, box water tanks, bathroom parts, watch panels, bathtubs, sanitary, desk mats, game parts, toys, musical instruments, face protection masks during welding, solar cells Back sheets, front sheets for flexible solar cells, decorative films; surface materials used for personal computers, mobile phones, furniture, vending machines, bathroom materials, and the like.

By laminating a layer containing the methacrylic copolymer or the methacrylic copolymer composition of the present invention with another material (for example, a layer containing another thermoplastic copolymer), the laminated body is formed. Obtainable. Examples of other materials used for the laminate include steel, plastic (for example, thermoplastic resin), wood, glass and the like. The laminate obtained by the present invention is suitably used for wallpaper; the surface of an automobile interior member; the surface of an automobile exterior member such as a bumper; the surface of a mobile phone; the surface of furniture; the surface of a personal computer; the surface of a vending machine; the surface of a bathroom member such as a bathtub. be able to.

The film, which is a form of the molded body of the present invention, has high transparency and heat resistance, and is therefore suitable for optical applications. It is particularly suitable for display window protective films, light guide films, transparent conductive films coated with silver nanowires and carbon nanotubes on the surface, and front panel applications of various displays. Since the film of the present invention has high transparency and heat resistance, it is used as an infrared cut film, a security film, a shatterproof film, a decorative film, a metal decorative film, a shrink film, and an in-mold label film for applications other than optical applications. Can be used for.

When the film which is one form of the molded product of the present invention is used as a polarizing element protective film or a retardation film, it may be laminated on only one side of the polarizing element film or may be laminated on both sides. When laminated with the polarizing film, it can be laminated via an adhesive layer or an adhesive layer. As the polarizing film, a stretched film made of a polyvinyl alcohol-based resin and iodine can be used, and the film thickness is preferably 1 to 100 μm.

Next, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples.

The physical properties were measured by the following method.
(Polymerization conversion rate)
A gas chromatograph GC-14A manufactured by Shimadzu Corporation was used as a column on GL Sciences Inc. INERTCAP 1 (df = 0.4 μm, 0.25 mm ID × 60 m) manufactured by INERTCAP 1 was connected, and analysis was performed under the following conditions, and calculation was performed based on the analysis.

Injection temperature = 250 ° C
detector temperature = 250 ° C
Temperature conditions: Hold at 60 ° C for 5 minutes → Raise to 250 ° C at 10 ° C / min → Hold at 250 ° C for 10 minutes

(Molecular weight)
The weight average molecular weight (Mw) of the resin was determined by the GPC method (gel permeation chromatography method). A sample solution was prepared by dissolving 4 mg of the resin to be measured in 5 ml of tetrahydrofuran. The temperature of the column oven was set to 40 ° C., the eluent flow rate was 0.35 ml / min, 20 μl of the sample solution was injected into the apparatus, and the chromatogram was measured. 10 points of standard polystyrene having a molecular weight in the range of 400 to 5,000,000 were measured by GPC, and a calibration curve showing the relationship between the retention time and the molecular weight was prepared. The Mw of the resin to be measured was determined based on this calibration curve.

Equipment: Tosoh GPC equipment HLC-8320
Separation column: TSKguardcoIumSuperHZ-H, TSKgeIHZM-M and TSKgeISuperHZ4000 manufactured by Tosoh Co., Ltd. are connected in series. Eluent: Tetrahydrofuran Eluent flow rate: 0.35 mI / min Column temperature: 40 ° C.
Detection method: Differential refractometer (RI)

(Composition of each unit in the precursor polymer)
Inverse gate decoupling method ¹³ By C-NMR, carbonyl carbon of methyl methacrylate unit, 1-position aromatic carbon of α-methylstyrene unit, 1-position aromatic carbon of styrene unit, and carbonyl of maleic anhydride unit. The integrated value ratio of carbon was obtained, and the composition of each unit in the precursor polymer was calculated by this.

(Glass transition temperature Tg)
The methacrylic copolymer obtained in the production examples and the examples was once heated to 250 ° C. using a differential scanning calorimetry device (manufactured by Shimadzu Corporation, DSC-50 (product number)) in accordance with JIS K7121. Then, the DSC curve was measured under the condition of cooling to room temperature and then raising the temperature from room temperature to 230 ° C. at 10 ° C./min. The midpoint glass transition temperature obtained from the DSC curve measured at the time of the second temperature rise was defined as the glass transition temperature in the present invention.

(Imidization rate)
¹ H-NMR measurement of the copolymer was performed using ¹ H-NMR (manufactured by Bruker; trade name ULTRA SHIELD 400 PLUS), and ₃ O-CH groups of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm. The imidization rate (Im) is the value obtained by the following equation from the peak area A derived from the above and the peak area B derived from the _three N-CH groups of glutarimide and maleimide in the vicinity of 3.0 to 3.3 ppm. And said.
Imidization rate (R) (%) = [B / (A + B)] × 100

(Amount of maleic anhydride unit in methacrylic copolymer)
The IR spectrum of the methacrylic copolymer obtained in the examples was measured at room temperature using Nicolet iN10MX manufactured by Thermo Scientific. From the obtained spectrum, the absorption intensity of the peak derived from the carbonyl of maleic anhydride near 1780 cm ^-1 and the absorption intensity of the peak derived from the carbonyl of maleimide near 1685 cm ^-1 indicate the imidization rate of maleic anhydride (Im). '; Mol%) was calculated. ¹³ Maleic anhydride in the resin obtained in Examples and Comparative Examples is the value obtained by the following formula from the unit amount (m; mass%) of maleic anhydride of the precursor polymer obtained by C-NMR and the imidization rate. The unit amount ( _RM ; mass%) was used.
Maleic anhydride Unit amount (R- _m ) = m × (100-Im'') / 100

(surface hardness)
Acrylic resin obtained in Examples and Comparative Examples using an injection molding machine (M-100C manufactured by Meiki Co., Ltd.) under the conditions of a cylinder temperature of 260 ° C., a mold temperature of 50 ° C., and an injection speed of 50 mm / sec. The composition was injection molded to obtain a square test piece having a thickness of 3 mm and a side of 50 mm.
Further, using a single-screw extruder having a shaft diameter of 20 m, the acrylic resin compositions obtained in Examples and Comparative Examples were extruded from a T-die having a width of 150 mm at a resin temperature of 260 ° C., and the width was 100 mm and the thickness was 80 μm. Single layer film was obtained.
The pencil hardness of each test piece and single-layer film was measured according to JIS K5600-5-4 under a load of 0.75 kg.
◯: Pencil hardness of test piece or single layer film is H or more ×: Pencil hardness of test piece or single layer film is F or less

(Photoelastic coefficient)
The methacrylic copolymer was press-molded to obtain a 1.0 mm sheet. A 15 mm × 60 mm test piece was cut out from the central portion of the obtained press-formed sheet. Both ends of the cut sheet in the long side direction are fixed so that the distance between the chucks is 45 mm, and tension is applied to the sheet step by step from 0N to 100N using the X-axis dovetail stage B05-11BM manufactured by Suruga Seiki. Granted. The tension T was monitored by a sensor separate type digital force gauge ZPS-DPU-50N manufactured by Imada Co., Ltd. The phase difference PD with each tension applied was measured at the D-line wavelength of Na using KOBRA-WR manufactured by Oji Measuring Instruments. After the phase difference measurement, the sheet was removed from the jig, and the thickness d of the phase difference measurement portion was measured. From the measured values, the cross-sectional area S of the sheet S = 15 mm × d, stress σ (= T / S) and birefringence Δn (= PD / d) are calculated, and stress σ is plotted on the horizontal axis and birefringence Δn is plotted on the vertical axis. Then, the slope of a straight line obtained by the minimum self-squared method was used as the photoelastic coefficient.

(Orientation birefringence)
The methacrylic copolymer was press-molded to obtain a 1.0 mm sheet. A 20 mm × 40 mm test piece was cut out from the central portion of the obtained press-molded sheet, and the test piece was placed in an autograph with a heating chamber (manufactured by SHIMADZU). The gripping distance in the autograph was set to 20 mm, and the glass transition temperature was maintained at + 10 ° C. for 3 minutes. Then, it was stretched 100% in one direction at a speed of 3 mm / min (the distance between grips became 40 mm). The obtained stretched film was cooled to 23 ° C., removed from the autograph, and the phase difference PD at the center of the stretched film was measured at the D-line wavelength of Na using KOBRA-WR manufactured by Oji Measuring Instruments. The thickness d of the phase difference measuring portion was measured. The birefringence Δn (= PD / d) was calculated from the measured value, and this was defined as the orientation birefringence.

Production Example 1
Purified methyl methacrylate (MMA), α-methylstyrene, maleic anhydride, 2,2'-azobis (2-methylpropionitrile) (AIBN) and n-octyl mercaptan (n) in an autoclave A with a stirrer. -OM) was charged at the ratio shown in Table 1 and uniformly dissolved to obtain a polymerization raw material.

The polymerization raw material is continuously supplied from the autoclave A to a tank reactor controlled at a polymerization temperature of 120 ° C. at 1.5 kg / hr, and the polymerization reaction is carried out by a massive polymerization method with an average residence time of 2.5 hours. The liquid containing the methacrylic copolymer was continuously discharged from the mold reactor. The polymerization conversion rate was the value shown in Table 1. Then, the liquid discharged from the reactor was heated to 230 ° C. and supplied to a twin-screw extruder controlled to 240 ° C. In the twin-screw extruder, the volatile matter containing the unreacted monomer as a main component was separated and removed, and the methacrylic copolymer was extruded into strands. The strands were cut with a pelletizer to give the precursor polymer A-a. The weight average molecular weight Mw of the obtained precursor polymer Aa, each unit composition of the copolymer, and the glass transition temperature Tg were measured. The results are shown in Table 1. In this production example, the amount of the unit derived from MMA is the amount of the unit other than the α-methylstyrene unit, the styrene unit, and the maleic anhydride unit, so the description in the table is omitted.

Production Examples 2 to 7
Precursor polymers AB to Ag were obtained in the same manner as in Production Example 1 except that the monomer composition in the polymerization raw material and the amount of the chain transfer agent used were changed as shown in Table 1.

Production Example 8
MS resin (copolymer of methyl methacrylate (MMA) and styrene (St)) is produced according to the method for producing a copolymer (A) described in the section of [Example] of JP-A-2003-231785. bottom. By changing the mass ratio of MMA, St and t-dodecyl mercaptan (t-DM) charged in the autoclave, the precursor polymer Ah; Mw = 95000, Tg = 113 ° C., content of styrene monomer unit 20 mass. % Was obtained.

<Example 1>
Transport section of a twin-screw extruder (manufactured by Technobel Co., Ltd .; trade name KZW20TW-45MG-NH-600) consisting of a transport section, a melt kneading section, a volatilization section, and a discharge section and set to a screw rotation speed of 120 rpm and a temperature of 280 ° C. The precursor polymer [Aa] shown in Production Example 1 was supplied at 2 kg / hr, and monomethylamine was added at 0.41 kg / hr in a melt-kneaded portion in which a kneading block was installed as an additive for a twin-screw extruder. It was injected from the supply port to react the precursor polymer [Aa] with monomethylamine. A reverse flight was installed on the screw at the end of the reaction zone.

In the devolatilization section set to 20 Torr (about 2.7 kPa), by-products and excess monomethylamine were volatilized from the molten resin that had passed through the melt kneading section and discharged through the vent.

The molten resin extruded as a strand from a die provided at the end of the discharge section of the twin-screw extruder is cooled in a water tank and then cut with a pelletizer to form a pellet-shaped methacrylic copolymer (A-a-1). ) Was obtained.

Transport section of a twin-screw extruder (manufactured by Technobel Co., Ltd .; trade name KZW20TW-45MG-NH-600) consisting of a transport section, a melt-kneading section, a volatilization section, and a discharge section and set to a screw rotation speed of 100 rpm and a temperature of 280 ° C. The copolymer (A-a-1) was supplied at 1 kg / hr, and in the melt-kneaded portion in which the kneading block was installed, a liquid consisting of 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine was added to 0. The mixture was injected at 112 kg / hr, and the carboxy group in the methacrylic copolymer (A-a-1) was reacted with dimethyl carbonate. A reverse flight was installed on the screw at the end of the reaction zone.

In the devolatilization section set to 20 Torr (about 2.7 kPa), by-products and excess dimethyl carbonate were volatilized from the molten resin that had passed through the melt kneading section and discharged through the vent.

The molten resin extruded as a strand from a die provided at the end of the discharge section of the twin-screw extruder is cooled in a water tank and then cut with a pelletizer to form a pellet-shaped methacrylic copolymer (A-a-2). ) Was obtained.

Transport section of a twin-screw extruder (manufactured by Technobel Co., Ltd .; trade name KZW20TW-45MG-NH-600) consisting of a transport section, a melt-kneading section, a devolatilization section, and a discharge section and set to a screw rotation speed of 100 rpm and a temperature of 280 ° C. A methacrylic copolymer (A-a-2) was supplied at 1 kg / hr.

In the devolatilization section set to 20 Torr (about 2.7 kPa), volatile components such as unreacted substances were volatilized from the molten resin that had passed through the melt-kneading section and discharged through the vent.

The molten resin extruded as a strand from a die provided at the end of the discharge section of the twin-screw extruder is cooled in a water tank and then cut with a pelletizer to obtain a pellet-shaped methacrylic copolymer (A-1). Obtained. The methacrylic copolymer (A-1) has an imidization ratio of 62 wt%, a maleic anhydride unit amount of M of 2 wt%, a glass transition temperature of 186 ° C., an orientation birefringence of 0.10 × 10 ^-4 , and light. The elastic coefficient was 0.21 × ^10-12 Pa ^-1 . Table 2 shows the physical characteristics of the methacrylic copolymer (A-1).

<Example 2>
Using the precursor polymer [Ab] instead of the precursor polymer [Aa], the amount of monomethylamine added is 0.29 kg / hr, from 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine. A methacrylic copolymer (A-2) was obtained by the same method as in Example 1 except that the solution was injected at 0.077 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-2).

<Example 3>
Using the precursor polymer [A-c] instead of the precursor polymer [A-a], the amount of monomethylamine added is 0.32 kg / hr, from 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine. A methacrylic copolymer (A-3) was obtained by the same method as in Example 1 except that the solution was injected at 0.086 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-3).

<Example 4>
Instead of the precursor polymer [AA], the precursor polymer [Ad] was used, and the amount of monomethylamine added was 0.38 kg / hr, from 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine. A methacrylic copolymer (A-4) was obtained by the same method as in Example 1 except that the solution was injected at 0.103 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-4).

<Example 5>
Instead of the precursor polymer [Aa], the precursor polymer [Ae] was used, and the amount of monomethylamine added was 0.33 kg / hr, from 0.8 parts by mass of dimethyl carbonate and 0.2 parts by mass of triethylamine. A methacrylic copolymer (A-5) was obtained by the same method as in Example 1 except that the solution was injected at 0.088 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-5).

<Comparative Example 1>
Using the precursor polymer [AF] instead of the precursor polymer [AA], the temperature of the twin-screw extruder was set to 250 ° C., the amount of monomethylamine added was 0.03 kg / hr, and dimethyl carbonate was used. A methacrylic copolymer (A-6) was obtained by the same method as in Example 1 except that a liquid consisting of 0.8 parts by mass and 0.2 parts by mass of triethylamine was injected at 0.009 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-6).

<Comparative Example 2>
Using the precursor polymer [Ag] instead of the precursor polymer [Aa], the temperature of the twin-screw extruder was set to 250 ° C., the amount of monomethylamine added was 0.15 kg / hr, and dimethyl carbonate. A methacrylic copolymer (A-7) was obtained by the same method as in Example 1 except that a liquid consisting of 0.8 parts by mass and 0.2 parts by mass of triethylamine was injected at 0.04 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-7).

<Comparative Example 3>
Using the precursor polymer [Ah] instead of the precursor polymer [A-a], the temperature of the twin-screw extruder was set to 250 ° C., the amount of monomethylamine added was 0.26 kg / hr, and dimethyl carbonate. A methacrylic copolymer (A-8) was obtained by the same method as in Example 1 except that a liquid consisting of 0.8 parts by mass and 0.2 parts by mass of triethylamine was injected at 0.07 kg / hr. Table 2 shows the physical characteristics of the methacrylic copolymer (A-8).

<Comparative Example 4>
An acrylic copolymer (A-9) was obtained by the same method as in Example 1 except that the precursor polymer [Aa] was used, no additives were added, and the extruder was passed through. Table 2 shows the physical characteristics of the acrylic copolymer (A-9).

The methacrylic polymers obtained in Examples 1 to 5 have high heat resistance, high optical isotropic properties (extremely small orientation birefringence and extremely small photoelastic coefficient), and have high surface hardness. , Can be suitably used as a material constituting an optical member. On the other hand, the methacrylic copolymers obtained in Comparative Examples 1 to 4 are inferior to the present invention because they are not within the scope of the present invention and therefore have low optical isotropic properties or low surface hardness. rice field.

Claims (12)

A methyl methacrylate unit, an α-methylstyrene unit, a maleic anhydride unit, and a structural unit (R) having at least one ring structure selected from the group consisting of the following formulas (1) to (3) in the main chain. The absolute value of the photoelastic coefficient is 3.0 × ^10-12 Pa ^-1 or less, and a sheet of 20 mm × 40 mm × thickness 1.0 mm is 3 mm / at a temperature 10 ° C higher than the glass transition temperature. A methacrylic copolymer having an absolute value of orientation and double refraction of a stretched film obtained by stretching 100% in one direction at a rate of minutes of 2.5 × 10 ^-4 or less.

(In formula (1), R ¹¹ and R ¹² are independently hydrogen atoms or alkyl groups having 1 to 5 carbon atoms, respectively.)

(In the formula (2), R ²¹ and R ²² are independently hydrogen atoms or methyl groups, respectively, and R ²³ is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or It is an organic group having 6 to 15 carbon atoms including an aromatic ring.)

(In the formula (3), R ³¹ and R ³² are independently hydrogen atoms, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms, and R ³³ is a hydrogen atom and 1 carbon atom. It is an alkyl group of ~ 18, a cycloalkyl group having 3 to 12 carbon atoms, or an organic group having 6 to 15 carbon atoms including an aromatic ring.) At least one structural unit (R) selected from the group consisting of N-substituted or unsubstituted glutarimide units represented by the formula (2) or N-substituted or unsubstituted maleimide units represented by the formula (3). The methacrylic copolymer according to claim 1, which is the structural unit of the above. The methacrylic copolymer according to claim 1 or 2, wherein the glass transition temperature is 120 ° C. or higher. Claimed to contain 22 to 87% by mass of a methyl methacrylate unit, 7 to 30% by mass of an α-methylstyrene unit, 1 to 30% by mass of a maleic anhydride unit, and 3 to 70% by mass of a structural unit (R). The methacrylic copolymer according to any one of 1 to 3. The methacrylic copolymer according to any one of claims 1 to 4, which contains 0 to 30% by mass of another copolymerizable vinyl-based monomer unit. Claimed that the other copolymerizable vinyl-based monomer unit is at least one structural unit selected from the group consisting of an acrylic acid alkyl ester unit, an aromatic vinyl unit excluding α-methylstyrene, and a vinyl cyanide unit. Item 6. The methacrylic copolymer according to any one of Items 1 to 5. A resin composition containing the methacrylic copolymer according to any one of claims 1 to 6. A molded product containing the methacrylic copolymer according to any one of claims 1 to 6 or the composition according to claim 7. The molded product according to claim 8, wherein the molded product is a film or a sheet. A method for producing a film or sheet, which comprises a step of molding the methacrylic copolymer according to any one of claims 1 to 6 or the composition according to claim 7 into a film or sheet by a melt molding method. A method for producing a film or sheet, which comprises a step of molding the methacrylic copolymer according to any one of claims 1 to 6 or the composition according to claim 7 into a film or sheet by a solution casting method. A laminate having at least one layer composed of the methacrylic copolymer according to any one of claims 1 to 6 or a film or sheet containing the composition according to claim 7.