Methacrylic polymer, production method thereof, and molded body

Abstract

To provide a methacrylic polymer which has high heat resistance, a high coefficient of elasticity, a not high coefficient of water absorption, and good heat and warm water stability.SOLUTION: A methacrylic copolymer comprises: 15-83 mass% of methyl methacrylate units; 7-35 mass% of α-methylstyrene units; 0-20 mass% of maleic anhydride units (M); 10-65 mass% of structural units (R) having in the main chain at least one or more ring structures selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, an N-substituted or -unsubstituted glutarimide unit, and an N-substituted or -unsubstituted maleimide unit; and 0-20 mass% of other vinylic monomer units (C) copolymerizable with methyl methacrylate units.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a methacrylic polymer, a method for producing the same, and a molded article including a film, an optical film, and a laminate.

Background Art

[0002] Methacrylic resins are excellent in transparency, weather resistance, surface hardness, etc. By molding an acrylic resin composition containing the methacrylic resin, various members used for display members, electronic and electrical members, transportation equipment parts, etc. can be obtained. In recent years, higher performance of various members has been demanded, and in particular, improvement of heat resistance and elastic modulus has been strongly demanded.

[0003] In order to improve the heat resistance and elastic modulus of (meth)acrylic resins, random copolymers of methyl methacrylate and α-methylstyrene have been known for a long time. However, α-methylstyrene does not have radical polymerization homopolymerizability under industrial conditions, and its copolymerizability with other monomers is also low, making it difficult to produce copolymers. For example, Patent Document 1 discloses a copolymer synthesized by a batch-type bulk polymerization method, but the polymerization time is very long and the productivity is low.

[0004] As a method for increasing the polymerization rate of the binary copolymer (random copolymer of methyl methacrylate and α-methylstyrene) and having further excellent heat resistance, a method of copolymerizing maleic anhydride is known. For example, Patent Document 2 discloses a method of copolymerizing methyl methacrylate, α-methylstyrene, and maleic anhydride. Patent Document 3 also discloses a method of copolymerizing methyl methacrylate, α-methylstyrene, maleic anhydride, and styrene. These polymers obtained by copolymerizing an α-methylstyrene copolymer and maleic anhydride have a high polymerization rate and further high heat resistance, but are liable to undergo chemical changes and decompose when exposed to heat or warm water, and are significantly restricted during molding. Also, when the processed product is brought into contact with water or steam, or exposed to high temperature and high humidity, there is a drawback that it causes deterioration of physical properties.

[0005] As a method for improving the thermal decomposition resistance and suppressing the deterioration of physical properties under high temperature and high humidity, an imidization reaction has been proposed. Patent Document 4 discloses a method for producing an imidized resin of a copolymer composed of an aromatic vinyl monomer, maleic anhydride, and methyl methacrylate as a vinyl monomer copolymerizable therewith. Further, Patent Document 5 discloses an imidized resin of a terpolymer of methyl methacrylate, styrene, and maleic anhydride and a resin composition thereof.

[0006] Although the thermal stability is improved in any of the disclosed examples, water absorption and coloring are likely to occur due to a high imidization rate. As described above, there has been room for study regarding a method for further balancing heat resistance, high elastic modulus, thermal and hot water stability, and low water absorption at a higher level.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0008] In view of the above circumstances, an object of the present invention is to provide a methacrylic polymer having high heat resistance, high elastic modulus, low water absorption rate, and good thermal and hot water stability.

Means for Solving the Problems

[0009] As a result of investigations to achieve the above object, the present invention has been completed, including the following aspects. 〔1〕 A methacrylic copolymer having 15 to 83% by mass of methyl methacrylate units, 7 to 35% by mass of α-methylstyrene units, 0 to 20% by mass of maleic anhydride units (M), and 10 to 65% by mass of a structural unit (R) having at least one or more ring structures selected from the group consisting of lactone ring units, glutaric anhydride units, N-substituted or unsubstituted glutarimide units, and N-substituted or unsubstituted maleimide units in the main chain, and 0 to 20% by mass of other vinyl monomer units (C) copolymerizable with methyl methacrylate. 〔2〕 The methacrylic copolymer according to 〔1〕, wherein the structural unit (R) is an N-substituted or unsubstituted glutarimide unit represented by the formula (I).

Chemical formula

Chemical formula

[14] , wherein the ring structure formation reaction is an imidocyclization reaction in which an imidizing agent is added to a precursor polymer in an extruder, kneaded, and reacted.

Effect of the Invention

[0010] According to the present invention, a methacrylic polymer excellent in stability in heat and warm water, having high heat resistance, high elastic modulus, and low water absorption can be obtained.

Embodiment for Carrying Out the Invention

[0011] (Methacrylic copolymer) The methacrylic copolymer of the present invention contains methyl methacrylate units, α-methylstyrene units, and structural units (R). The methacrylic copolymer of the present invention may further contain maleic anhydride units (M) and other vinyl monomer units (C) copolymerizable with methyl methacrylate. Other vinyl monomer units (C) copolymerizable with methyl methacrylate may be methacrylamide units represented by the following formula (A) and 2-(hydroxyalkyl)acrylate ester units represented by the following formula (B).

[0012]

Chemical formula

[0013] In the methacrylic copolymer of the present invention, the proportion of methyl methacrylate units is preferably 15 to 83% by mass, more preferably 30 to 80% by mass, and still more preferably 35 to 75% by mass with respect to all structural units. When the proportion of methyl methacrylate units is less than this range, the total light transmittance of the resulting methacrylic copolymer deteriorates. When the proportion of methyl methacrylate units is more than this range, the heat resistance of the resulting methacrylic copolymer decreases.

[0014] In the methacrylic copolymer of the present invention, the proportion of α-methylstyrene units is preferably 7 to 35% by mass, more preferably 8 to 30% by mass, and still more preferably 11 to 25% by mass with respect to all structural units. When the proportion of α-methylstyrene units is less than this range, the saturated water absorption rate of the resulting methacrylic copolymer increases. In addition, a methacrylic copolymer in which the proportion of α-methylstyrene units exceeds 35% by mass has low polymerizability and reduced productivity. Further, it inhibits the glutarimidation reaction due to intramolecular cyclization of structural units derived from two adjacent (meth)acrylic acids described below.

[0015] In the methacrylic copolymer of the present invention, the proportion of maleic anhydride units (M) is preferably 0 to 20% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.1 to 3% by mass with respect to all structural units. A methacrylic copolymer in which the proportion of maleic anhydride units exceeds 20% by mass has reduced hot water stability.

[0016] The structural unit (R) is a structural unit having at least one ring structure selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, an N-substituted or unsubstituted glutarimide unit, and an N-substituted or unsubstituted maleimide unit in the main chain. The methacrylic copolymer of the present invention may contain, in the main chain, a methacrylic acid amide unit represented by the above formula (A) and / or a 2-(hydroxyalkyl)acrylate unit represented by the above formula (B).

[0017] The lactone ring unit is a structural unit containing a >CH-O-C(=O)- group in the ring structure. The structural unit containing a >CH-O-C(=O)- group in the ring structure preferably has 4 to 8, more preferably 5 to 6, and most preferably 6 ring-constituting elements. Examples of the structural unit containing a >CH-O-C(=O)- group in the ring structure include lactone diyl structural units such as β-propiolactone diyl structural unit, γ-butyrolactone diyl structural unit, and δ-valerolactone diyl structural unit. The structural unit containing a >CH-O-C(=O)- group in the ring structure can be obtained, for example, by intramolecular cyclization of a polymer having a hydroxy group and an ester group with respect to the hydroxy group and the ester group. Note that ">"C" in the formula means that there are two bonds to the carbon atom C.

[0018] For example, examples of the δ-valerolactone diyl structural unit include the structural unit represented by formula (IV).

[0019]

Chemical formula

[0020] In formula (IV), R 8 , R 9 and R 10 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms, preferably a hydrogen atom or an organic group having 1 to 10 carbon atoms, more preferably a hydrogen atom or an organic group having 1 to 5 carbon atoms. Here, the organic group is not particularly limited as long as it has 1 to 20 carbon atoms, and examples thereof include linear or branched alkyl groups, linear or branched aryl groups, -COOCH3 groups, -CN groups, etc. The organic group may contain a hetero atom such as an oxygen atom. R 8 is preferably a methyl group, R 9 is preferably a -COOCH3 group, and R 10 is preferably a hydrogen atom.

[0021] The lactone ring unit can be incorporated into a methacrylic copolymer by methods described in, for example, JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, JP-A-2002-254544, JP-A-2005-146084, etc., such as intramolecular cyclization of a structural unit derived from 2-(hydroxyalkyl)acrylate and a structural unit derived from methyl (meth)acrylate.

[0022] The glutaric anhydride unit is a unit having a 2,6-dioxodihydropyranediyl structure. Examples of the unit having a 2,6-dioxodihydropyranediyl structure include the structural unit represented by formula (V).

[0023] [Chemical formula] In formula (II), each R 11 is independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and is preferably a methyl group.

[0024] The unit having a 2,6-dioxodihydropyranediyl structure can be incorporated into a methacrylic copolymer by methods described in, for example, JP-A-2007-197703, JP-A-2010-96919, etc., such as intramolecular cyclization of two adjacent structural units derived from (meth)acrylic acid, and intramolecular cyclization of a structural unit derived from (meth)acrylic acid and a structural unit derived from methyl (meth)acrylate.

[0025] The 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 the structural unit represented by formula (I).

[0026] [Chemical formula] In formula (I), R1 is independently a hydrogen atom or a methyl group, and the two Rs 1 are preferably both methyl groups. R 2 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 containing an aromatic ring, preferably a hydrogen atom, a methyl group, an n-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 (I) may be produced, for example, by reacting the corresponding acid anhydride (IIa) with an imidizing agent represented by R 2 NH2, or may be produced by an intramolecular cyclization reaction of a copolymer having a partial structure of the formula (III). It is preferable to heat in order to convert the structural unit represented by the formula (III) into the structural unit represented by the formula (I) by an intramolecular cyclization reaction. Scheme (i)

Chemical formula

[0027] The N-substituted or unsubstituted glutarimide unit can be obtained by reacting with an imidizing agent such as ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, n-hexylamine and other aliphatic hydrocarbon group-containing amines, aniline, toluidine, trichloroaniline and other aromatic hydrocarbon group-containing amines, cyclohexylamine and other alicyclic hydrocarbon group-containing amines, urea, 1,3-dimethylurea, 1,3-diethylurea, 1,3-dipropylurea, etc. according to the methods described in WO2005 / 10838A1, JP-A-2010-254742, JP-A-2008-273140, JP-A-2008-274187, etc., specifically, by reacting with an imidizing agent on the structural unit or glutaric anhydride unit derived from two adjacent methyl methacrylates. Among these, methylamine is preferred. During this imidization reaction, a part of the methyl methacrylate unit may be hydrolyzed to form a carboxyl group, and this carboxyl group is preferably returned to the original methyl methacrylate unit by an esterification reaction with an esterifying agent. The esterifying agent is not particularly limited as long as the effects of the present application can be exhibited, but dimethyl carbonate and trimethyl acetate can be preferably used. In addition to the esterifying agent, a tertiary amine such as trimethylamine, triethylamine, tributylamine can also be used in combination as a catalyst.

[0028] The N-substituted or unsubstituted maleimide unit is a unit having an N-substituted or unsubstituted 2,5-pyrrolidinedione structure. Examples of the unit having an N-substituted or unsubstituted 2,5-pyrrolidinedione structure include the structural unit represented by the formula (II).

[0029]

Chemical formula

[0030] The N-substituted or unsubstituted maleimide unit can be obtained by the methods described in Japanese Patent Publication No. 61-026924, Japanese Patent Publication No. 7-042332, Japanese Patent Laid-Open No. 9-100322, Japanese Patent Laid-Open No. 2001-329021, etc. Specifically, maleic anhydride units are reacted with imidizing agents such as ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, n-hexylamine and other aliphatic hydrocarbon group-containing amines, aniline, toluidine, trichloroaniline and other aromatic hydrocarbon group-containing amines, cyclohexylamine and other alicyclic hydrocarbon group-containing amines, urea, 1,3-dimethylurea, 1,3-diethylurea, 1,3-dipropylurea and the like. Among these, methylamine is preferred.

[0031] In the methacrylic copolymer of the present invention, the proportion of the structural unit (R) is preferably 10 to 65% by mass, more preferably 12 to 62% by mass, still more preferably 14 to 60% by mass based on all the structural units. The higher the content of the structural unit (R), the better the heat decomposition resistance of the methacrylic copolymer, but the melt viscosity increases and the molding processability tends to decrease.

[0032] Other vinyl monomer units (C) copolymerizable with the methyl methacrylate unit (hereinafter may be referred to as (C) monomer units) include acrylic ester monomer units (C-1), aromatic vinyl monomer units (C-2), vinyl cyanide monomer units (C-3), and other monomer units (C-4). Other vinyl monomer units (C) copolymerizable with the methyl methacrylate unit may be used alone or in combination of two or more.

[0033] The (C) monomer unit can be appropriately selected according to the properties required for the methacrylic copolymer of the present invention. However, when properties such as heat stability, fluidity, chemical resistance, optical properties, and compatibility with other resins are particularly required, at least one selected from the group consisting of acrylate monomer units, aromatic vinyl monomer units, and vinyl cyanide monomer units is preferable.

[0034] The acrylate monomer unit (C-1) constituting the methacrylic copolymer of the present invention is not particularly limited. However, from the viewpoints of heat resistance, fluidity, heat stability, productivity, etc., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, 2-ethylhexyl acrylate, benzyl acrylate, cyclohexyl acrylate, phenyl acrylate, etc. are preferable, and more preferably methyl acrylate, ethyl acrylate, and n-butyl acrylate. From the viewpoint of productivity, methyl acrylate and ethyl acrylate are even more preferable. The above acrylate monomer unit (C-1) may be used alone or in combination of two or more.

[0035] When the acrylate monomer unit (C-1) is used, the content is preferably 20% or less, more preferably 10% or less, based on all structural units, from the viewpoints of heat resistance and heat stability.

[0036] The aromatic vinyl monomer unit (C-2) constituting the methacrylic copolymer of the present invention is not particularly limited as long as it is other than α-methylstyrene. However, from the viewpoints of heat resistance, fluidity, heat stability, productivity, etc., styrene (St), o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, p-ethylstyrene, m-ethylstyrene, o-ethylstyrene, p-tert-butylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 1,1-diphenylethylene, isopropenyltoluene, isopropenylethylbenzene, isopropenylpropylbenzene, isopropenylpropylbenzene, isopropenylbutylbenzene, isopropenylbenzylbenzene, isopropenylhexylbenzene, isopropenyloctylbenzene, etc. are preferable, and styrene is more preferable from the viewpoint of productivity. The above aromatic vinyl monomer unit (C-2) may be used alone as only one kind, or two or more kinds may be used in combination.

[0037] When using the aromatic vinyl monomer unit (C-2), the content is preferably 20% or less, more preferably 15% or less, based on all the structural units, from the viewpoints of heat resistance and thermal stability.

[0038] The vinyl cyanide monomer unit (C-3) constituting the methacrylic copolymer of the present invention is not particularly limited. However, from the viewpoints of heat resistance, fluidity, heat stability, chemical resistance, productivity, etc., acrylonitrile (AN), methacrylonitrile, vinylidene cyanide, etc. are preferable, and acrylonitrile is preferable especially from the viewpoints of easy availability and imparting chemical resistance. The above vinyl cyanide monomer unit (C-3) may be used alone as only one kind, or two or more kinds may be used in combination.

[0039] When using the vinyl cyanide monomer unit (C-3), the content is preferably 20% or less, more preferably 10% or less, based on all the structural units, from the viewpoints of heat resistance and thermal stability.

[0040] The monomer forming the monomer unit (C-4) other than (C-1) to (C-3) constituting the methacrylic copolymer of the present invention is not particularly limited, but a monomer corresponding to a methacrylic acid amide unit represented by the formula (A), It may be a monomer corresponding to a 2-(hydroxyalkyl)acrylic acid ester unit represented by the formula (B). For example, amides such as acrylamide and methacrylamide; ethylene glycols such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, or both terminal hydroxyl groups of its oligomer are esterified with acrylic acid or methacrylic acid; neopentyl glycol di(meth)acrylate, di(meth)acrylate, etc. in which the hydroxyl groups of two alcohols are esterified with acrylic acid or methacrylic acid; polyhydric alcohol derivatives such as trimethylolpropane and pentaerythritol esterified with acrylic acid or methacrylic acid; polyfunctional monomers such as divinylbenzene and the like can be mentioned.

[0041] Among the monomers constituting the above-mentioned (C) monomer unit, at least one selected from the group consisting of methyl acrylate (MA), ethyl acrylate, styrene, and acrylonitrile is preferable from the viewpoint of easy availability.

[0042] In the methacrylic copolymer of the present invention, the proportion of other vinyl monomer units (C) copolymerizable with methyl methacrylate units is preferably 0 to 20% by mass, more preferably 0 to 15% by mass, still more preferably 0 to 10% by mass, based on all structural units. In a methacrylic copolymer in which the proportion of other vinyl monomer units (C) copolymerizable with methyl methacrylate units exceeds 20% by mass, the heat resistance and rigidity decrease. The proportions of methyl methacrylate units, α-methylstyrene units, maleic anhydride units (M), structural units (R), and monomer units (C) are 1 H-NMR, 13 It can be measured by C-NMR or the like.

[0043] From the viewpoints of heat resistance and hot water resistance, the mass ratio of the maleic anhydride unit (M) to the structural unit (R) having at least one ring structure selected from the group consisting of a lactone ring unit, a glutaric anhydride unit, and an N-substituted or unsubstituted glutarimide unit in the main chain of the methacrylic copolymer of the present invention, {100×(M) / (R)}, is preferably in the range of 0 to 20%, more preferably 0 to 10% by mass.

[0044] The weight average molecular weight (Mw) of the methacrylic copolymer of the present invention is preferably 40,000 to 200,000, more preferably 50,000 to 180,000, and still more preferably 55,000 to 160,000. When Mw is 40,000 or more, the strength and toughness of the molded article 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 moldability is improved.

[0045] The weight average molecular weight (Mw) is a value calculated by converting the chromatogram measured by gel permeation chromatography into the molecular weight of standard polystyrene.

[0046] The acid value of the methacrylic copolymer of the present invention is 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 carboxylic acid units and carboxylic anhydride units 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 of heat resistance, mechanical properties, and moldability is excellent.

[0047] The glass transition temperature of the methacrylic copolymer of the present invention has a lower limit of preferably 140°C, more preferably 141°C, and still more preferably 142°C, and an upper limit which is not particularly limited, but is preferably 170°C. In this specification, the "glass transition temperature (Tg)" is measured in accordance with JIS K7121. Specifically, the temperature is first raised to 230°C, then cooled to room temperature, and then the DSC curve is measured under the condition of raising the temperature from room temperature to 230°C at a rate of 10°C / min. The midpoint obtained from the DSC curve measured during the second heating is determined as the "glass transition temperature (Tg)".

[0048] The measurement of the saturated water absorption rate of the methacrylic copolymer of the present invention can be carried out under the following conditions. The methacrylic copolymer is formed into a sheet with a thickness of 1.0 mm by press molding. A test piece of 50 mm × 50 mm is cut out from the central part of the obtained press-molded sheet and dried in a dryer at 80°C for 16 hours or more. After the dried test piece is cooled to room temperature in a desiccator, the weight is measured to 0.1 mg, and this weight is defined as the initial weight Wo. The test piece is immersed in distilled water at 23°C. After 24 hours of immersion, the test piece is taken out of the water, and all the moisture on the surface is wiped off with a clean and dry cloth or filter paper. Within 1 minute after taking out from the water, the test piece is weighed again to 0.1 mg. The test piece is immersed again, and after 24 hours, the weight is measured again in the same manner as above. The weight at which the weight change rate of the test piece is within 0.02% of Wo is defined as the saturated weight Ws. The saturated water absorption rate can be calculated from Equation (2).

[0049] [Number] The saturated water absorption rate is preferably 5.0% or less, more preferably 4.5% or less, and still more preferably 4.0% or less.

[0050] The 1% thermogravimetric weight loss temperature of the methacrylic copolymer of the present invention in a nitrogen atmosphere is preferably 300°C or higher, more preferably 310°C or higher. The 1% thermogravimetric weight loss temperature can be measured using a thermogravimetric analyzer (TGA). The 1% thermogravimetric weight loss temperature can be determined as the temperature at which the weight loss is 1% with respect to the charged weight.

[0051] (Method for producing a methacrylic copolymer) The methacrylic copolymer of the present invention can be obtained by a method including subjecting a copolymer of methyl methacrylate (MMA), α-methylstyrene (αMSt), maleic anhydride (Mah), and other vinyl monomers as optional components (hereinafter sometimes referred to as a precursor polymer) to a ring structure forming reaction. That is, the production method of the present invention includes a step of continuously supplying a reaction raw material comprising a monomer mixture containing 50 to 92% by mass of methyl methacrylate, 30 to 7% by mass of α-methylstyrene, 1 to 20% by mass of maleic anhydride, and 0 to 20% by mass of other copolymerizable vinyl monomers, a radical polymerization initiator, and, if necessary, a chain transfer agent to a tank reactor, a step of bulk polymerizing the monomer mixture in the tank reactor until the polymerization conversion rate reaches 30 to 60% by mass to obtain a reaction product, and a step of removing the monomer mixture in the reaction product to obtain a precursor polymer, and a step of subjecting the obtained precursor polymer to a ring structure forming reaction. Each step can be carried out by known techniques.

[0052] The precursor polymer is polymerized from a reaction raw material containing a monomer mixture, a radical polymerization initiator, and, if necessary, a chain transfer agent. The monomer mixture contains 50 to 92% by mass, preferably 55 to 90% by mass of methyl methacrylate in the monomer mixture. Also, α-methylstyrene is contained in an amount of 30 to 7% by mass, preferably 25 to 10% by mass. Maleic anhydride is contained in an amount of 1 to 20% by mass, preferably 3 to 15% by mass, and the copolymerizable monomer is contained in an amount of 0 to 20% by mass, preferably 0 to 10% by mass. The monomers that can be copolymerized are not particularly limited, but may be monomers corresponding to methacrylamide units represented by formula (A), monomers corresponding to 2-(hydroxyalkyl) acrylate units represented by formula (B), for example, alkyl methacrylates other than methyl methacrylate such as ethyl methacrylate and butyl methacrylate; aryl methacrylates such as phenyl methacrylate; cycloalkyl methacrylates such as cyclohexyl methacrylate and norbornenyl methacrylate; aryl acrylates such as phenyl acrylate; cycloalkyl acrylates such as cyclohexyl acrylate and norbornenyl acrylate; aromatic vinyl monomers such as styrene; acrylamide; methacrylamide; acrylonitrile; methacrylonitrile; and vinyl monomers having only one polymerizable alkenyl group in one molecule.

[0053] The monomer mixture preferably has a b* value of -1 to 2, more preferably -0.5 to 1.5. When the b* value is within this range, when the obtained methacrylic copolymer composition is molded, it is advantageous for obtaining a molded product with almost no coloring at high production efficiency. The b* value is a value measured in accordance with the International Commission on Illumination (CIE) standard (1976) or JIS Z-8722. The monomer mixture removed from the reaction product by the step of removing the monomer mixture in the reaction product can be recovered and used again in the present invention. When the b* value of the recovered monomer mixture increases due to heat added during recovery or the like, it is preferably purified by an appropriate method so that the b* value is within the above-mentioned range.

[0054] The polymerization initiator used in the present invention is not particularly limited as long as it generates reactive radicals. For example, t-hexyl peroxyisopropyl monocarbonate, t-hexyl peroxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutyl peroxy 2-ethylhexanoate, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1,1-bis(t-hexylperoxy)cyclohexane, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide, 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), dimethyl 2,2'-azobis(2-methylpropionate) are preferred; examples include t-hexyl peroxy 2-ethylhexanoate, 1,1-bis(t-hexylperoxy)cyclohexane, dimethyl 2,2'-azobis(2-methylpropionate).

[0055] The polymerization initiator used in the present invention preferably has an uncracked average initiator concentration (I) in the range of 5.1×10 -5 ~2.4×10 -4 (mol / L) at the polymerization temperature in the tank reactor described later.

[0056] The amount of the polymerization initiator used is adjusted according to the polymerization temperature and added to the monomer mixture so as to achieve the above initiator concentration (I).

[0057] As the chain transfer agent used in the present invention, there are alkyl mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, ethylene glycol bisthiopropionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris-(β-thiopropionate), pentaerythritol tetrakisthiopropionate; terpinolene and the like. Among these, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecyl mercaptan are preferred. 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, still more preferably 0.02 to 0.6 part by mass, based on 100 parts by mass of the monomer mixture.

[0058] In bulk polymerization, a solvent is not used in principle, but when it is necessary to adjust the viscosity of the reaction solution, etc., the solvent can be included in the monomer mixture. As the solvent, aromatic hydrocarbons such as benzene, toluene, and ethylbenzene, and ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferred. These solvents can be used alone or in combination of two or more. The amount of such a solvent used is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the monomer mixture.

[0059] The reaction raw material used in the present invention preferably has a dissolved oxygen amount of 10 ppm or less, more preferably 5 ppm or less, still more preferably 4 ppm or less, and most preferably 3 ppm or less. When the dissolved oxygen amount is within such a range, the polymerization reaction proceeds smoothly, and a molded product without silver streaks or coloring is easily obtained.

[0060] The temperature in the tank reactor, i.e., 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 generate high molecular weight polymers containing α-methylstyrene, which causes a decrease in heat resistance.

[0061] In the method for producing the methacrylic copolymer composition of the present invention, the water content in the reaction liquid in the tank reactor is preferably 1000 ppm or less, more preferably 700 ppm or less, and even more preferably 280 ppm or less. By setting the water content to 1000 ppm or less, the generation of resin foreign matters with a size of several μm to several tens of μm during the polymerization reaction can be suppressed, and when the obtained methacrylic copolymer composition is formed into a film or sheet by melt molding, the occurrence of defects with an outer diameter of several tens of μm with these resin foreign matters as nuclei can be significantly reduced.

[0062] In the tank reactor, bulk polymerization is preferably carried out until the polymerization conversion rate reaches 30 to 60% by mass, preferably until it reaches 35 to 55% by mass.

[0063] Also, the average residence time (θ) of the reaction raw materials in the tank reactor is preferably 1.5 to 5 hours, more preferably 2 to 4.5 hours, and even more preferably 2.5 to 4 hours. If the average residence time is too short, the required amount of the polymerization initiator increases. In addition, with the increase in the amount of the polymerization initiator, it becomes difficult to control the polymerization reaction, and the control of the molecular weight tends to be difficult. 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 materials.

[0064] Bulk polymerization is preferably carried out in an inert gas atmosphere such as nitrogen gas.

[0065] The manufacturing method of the present invention includes a step of removing the monomer mixture in the reaction product. Here, the reaction product is not limited to the reaction product obtained by bulk polymerization in a tank reactor, and may be a reaction product obtained in another reactor connected to the tank reactor as needed, that is, an unreacted monomer mixture in the reaction product obtained by bulk polymerization in the tank reactor is further polymerized by another reactor to increase the polymerization conversion rate. Also, in this step, a solvent may be removed simultaneously as needed. The removal method is not particularly limited, but a heat devolatilization method is preferred. Examples of the heat devolatilization method include an equilibrium flash evaporation method and an adiabatic flash evaporation method, and the adiabatic flash evaporation method is preferred. The temperature at which the adiabatic flash evaporation method is carried out is preferably 200 to 280°C, more preferably 220 to 280°C, and even more preferably 220 to 270°C. If the temperature at which the adiabatic flash evaporation method is carried out is less than 200°C, it takes time for devolatilization, resulting in insufficient devolatilization and possibly causing appearance defects such as silver streaks in the molded product. On the other hand, if the temperature at which the adiabatic flash evaporation method is carried out exceeds 280°C, the methacrylic copolymer composition tends to be colored and undergo a depolymerization reaction due to oxidation, burning, decomposition, etc. The adiabatic flash evaporation method may be carried out in multiple stages. In this case, the reaction product flowing through the heat transfer tube can be heated with the vapor of the flash-evaporated monomer mixture, and the heated reaction product can be supplied into a low-pressure flash tank for flash evaporation. The reaction product can be pressurized by a pump or the like. After removing the monomer mixture, the methacrylic copolymer composition can be made into pellets or powder according to a known method to facilitate handling as a molding material. The content of the monomer mixture in the methacrylic copolymer composition obtained in the present invention is preferably 1% by mass or less, and more preferably 0.5% by mass or less.

[0066] The precursor polymer has a glass transition temperature which is preferably 124 °C, more preferably 125 °C, still more preferably 127 °C as the lower limit, and preferably 150 °C as the upper limit. The glass transition temperature can be changed by adjusting the molecular weight, the copolymerization amount of α-methylstyrene, the copolymerization amount of maleic anhydride, etc. The higher the glass transition temperature of the precursor polymer, the better the heat resistance. The methacrylic copolymer obtained using a precursor polymer with a high glass transition temperature has high heat resistance even when the amount of the structural unit (R) is small, and thus is less likely to cause deterioration of the saturated water absorption rate, etc.

[0067] The precursor polymer is not particularly limited as long as the total content of the structural units derived from methyl methacrylate is 50 to 92% by mass, the total content of the structural units derived from α-methylstyrene is 35 to 7% by mass, and the total content of the structural units derived from maleic anhydride is 1 to 20% by mass. From the viewpoints of polymerizability, transparency, etc., the total content of the structural units derived from methyl methacrylate in the precursor polymer is preferably 50% by mass or more and 92% by mass or less, more preferably 55% by mass or more and 91% by mass or less, and most preferably 60% by mass or more and 90% by mass or less.

[0068] From the viewpoints of heat resistance, polymerizability, water absorption rate, etc., the total content of the structural units derived from α-methylstyrene in the precursor polymer is preferably 7% by mass or more and 27% by mass or less, more preferably 8% by mass or more and 25% by mass or less. If the structural units derived from α-methylstyrene are less than this range, sufficient heat resistance cannot be obtained, and if they are more than this range, the polymerizability significantly decreases.

[0069] From the viewpoints of heat resistance, polymerizability, thermal stability, etc., the total content of the structural units derived from maleic anhydride in the precursor polymer is preferably 1% by mass or more and 18% by mass or less, more preferably 2% by mass or more and 15% by mass or less. If the structural units derived from maleic anhydride are less than this range, sufficient heat resistance cannot be obtained, and if they are more than this range, significant yellowing occurs.

[0070] The precursor polymer preferably has a weight average molecular weight Mw in terms of polystyrene of 30,000 or more and 200,000 or less, more preferably 40,000 or more and 180,000 or less, still more preferably 50,000 or more and 160,000 or less, in the chromatogram obtained by gel permeation chromatography. If the weight average molecular weight Mw is less than this range, the resulting molded article 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 (optional component) used in the production of the precursor polymer.

[0071] The ring structure forming reaction can be carried out, for example, using an extruder. Examples of the extruder include a single-screw extruder, a twin-screw extruder, and a multi-screw extruder. From the viewpoint of mixing performance, a twin-screw extruder is preferred. The twin-screw extruder includes a non-intermeshing co-rotating type, an intermeshing co-rotating type, a non-intermeshing counter-rotating type, and an intermeshing counter-rotating type. The intermeshing co-rotating type is preferred because it can rotate at high speed and efficiently promote mixing. These extruders can be used alone or connected in series.

[0072] In the ring structure forming reaction using an extruder, for example, the precursor polymer as a raw material is introduced from the raw material inlet of the extruder, the precursor polymer is melted and filled in the cylinder, and then an imidizing agent (optional component) etc. is injected into the extruder using an addition pump, whereby the ring structure forming reaction can proceed in the extruder. When an imidizing agent is used, the structural unit (R) includes an N-substituted or unsubstituted glutarimide unit and an N-substituted or unsubstituted maleimide unit, and may contain a lactone ring unit and / or a glutaric anhydride unit as required. When no imidizing agent is used, the structural unit (R) is composed of a lactone ring unit and / or a glutaric anhydride unit. Preferred imidizing agents are R 4 -NH2 (R 4It is represented by (as defined above). The imidizing agent is used in an amount of 1.6 to 30 parts by mass, preferably 2.0 to 12 parts by mass, per 100 parts by mass of the methacrylic copolymer. When the amount of the imidizing agent used is within the above range, the by-production of methacrylamide units can be suppressed.

[0073] The resin temperature in the reaction zone in the extruder is preferably in the range of 180 to 280°C, more preferably in the range of 200 to 280°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 formation reaction, by-production of methacrylamide units, etc. If the resin temperature in the reaction zone exceeds 280°C, the resin may be significantly decomposed, and the mechanical strength such as the tensile fracture strength of molded articles, films including optical films, laminates, etc. made of the resulting methacrylic copolymer tends to decrease. Note that the reaction zone in the extruder refers to the region in the cylinder of the extruder from the injection position of the imidizing agent, etc. to the resin discharge port (die part).

[0074] By increasing the reaction time in the reaction zone of the extruder, the ring structure formation reaction can proceed further. The reaction time in the reaction zone of the extruder is preferably longer than 10 seconds, more preferably longer than 30 seconds. With a reaction time of 10 seconds or less, the ring structure formation reaction may hardly proceed.

[0075] 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, it exceeds the mechanical pressure resistance limit of a normal extruder, and special equipment is required, which is not preferable in terms of cost.

[0076] 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, or monomers can be removed, and the heat resistance of the molded article containing the methacrylic copolymer of the present invention tends to improve.

[0077] For the ring structure forming reaction, instead of an extruder, a high-viscosity compatible reaction apparatus such as a horizontal twin-screw reaction apparatus like the Bivolac manufactured by Sumitomo Heavy Industries, Ltd. or a vertical twin-screw stirring tank like a Super Blend can also be suitably used.

[0078] During the ring structure forming reaction, carboxy groups may be by-produced in the methacrylic copolymer. This carboxy group may be converted to an ester group with an esterifying agent, a catalyst, etc. as necessary. Thereby, foaming of the resin when manufacturing an optical film can be reduced. Such an ester group varies depending on the esterifying agent and catalyst used, but from the viewpoints of reducing the resin melt viscosity during melt molding, the reactivity of esterification, and the heat resistance of the resin after esterification, it preferably contains a methyl methacrylate unit. As the esterifying agent, dimethyl carbonate is preferable from the viewpoints of cost, reactivity, etc.

[0079] The addition amount of the esterifying agent can be set so that, for example, the acid value of the methacrylic copolymer becomes a desired value.

[0080] 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 include amine compounds such as trimethylamine, triethylamine, monomethyldiethylamine, dimethylmonoethylamine, and dimethylbenzylamine. Among these, triethylamine is preferable from the viewpoints of cost, reactivity, etc.

[0081] (Methacrylic copolymer composition) The methacrylic copolymer composition of the present invention may contain other polymers as long as the effects of the present invention are not impaired. Examples of other polymers include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionomers; styrene-based resins such as polystyrene, styrene-maleic anhydride copolymer, high-impact polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, and MBS resin; methyl methacrylate-styrene copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6, nylon 66, and polyamide elastomers; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacetal, polyvinylidene fluoride, polyurethane, phenoxy resin, modified polyphenylene ether, polyphenylene sulfide, silicone-modified resin; silicone rubber; acrylic multilayer copolymer elastomer; acrylic thermoplastic elastomers such as diblock copolymers and triblock copolymers of methyl methacrylate polymer block and n-butyl acrylate polymer block; (hydrogenated) styrene-based thermoplastic elastomers such as SEPS, SEBS, and SIS; and olefin-based rubbers such as IR, EPR, and EPDM. The amount of other polymers that can be contained in the resin composition of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and most preferably 0% by mass.

[0082] The present invention may contain additives generally used in resin compositions as long as the object of the present invention is not impaired. Examples of additives include fillers, antioxidants, heat degradation inhibitors, ultraviolet absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, colorants, dyes, pigments, light diffusing agents, organic dyes, matting agents, impact resistance modifiers, phosphors, and the like. The total amount of such additives other than fillers is preferably 7% by mass or less, more preferably 5% by mass or less, and even more preferably 4% by mass or less.

[0083] 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.

[0084] The antioxidant is effective in preventing oxidative degradation of the resin by itself in the presence of oxygen. Examples thereof include phosphorus-based antioxidants, hindered phenol-based antioxidants, thioether-based antioxidants and the like. These antioxidants may be used alone or in combination of two or more.

[0085] The thermal degradation inhibitor can prevent thermal degradation of the resin by capturing polymer radicals generated when exposed to high heat in a substantially oxygen-free state. Preferred examples of the thermal degradation inhibitor include 2-tert-butyl-6-(3'-tert-butyl-5'-methyl-hydroxybenzyl)-4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd.; trade name Sumilizer GM), 2,4-di-tert-amyl-6-(3',5'-di-tert-amyl-2'-hydroxy-α-methylbenzyl)phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd.; trade name Sumilizer GS), 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol (manufactured by BASF SE; trade name Irganox 565), tetrakis[methylene-3-(dodecylthio)propionate]methane (manufactured by ADEKA Corporation; trade name AO-412S) and the like.

[0086] The ultraviolet absorber is a compound having the ability to absorb ultraviolet rays. The ultraviolet absorber is a compound that is mainly said to have a function of converting light energy into thermal energy. Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid anilides, malonic acid esters, formamidines, etc. These may be used alone or in combination of two or more. Among these, benzotriazoles, triazines, or an ultraviolet absorber having a maximum value ε of the molar extinction coefficient at a wavelength of 380 to 450 nm max is 1200 dm 3 ·mol -1 cm -1 or less is preferred.

[0087] A light stabilizer is a compound that is said to mainly have a function of capturing radicals generated by oxidation by light. Examples of suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

[0088] Examples of the lubricant include stearic acid, behenic acid, stearoamidic acid, methylene bisstearamide, triglyceride hydroxystearate, paraffin wax, ketone wax, octyl alcohol, hydrogenated oil, etc.

[0089] Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; glycerin higher fatty acid esters such as monoglyceride stearate and diglyceride stearate. In the present invention, it is preferable to use higher alcohols and glycerin fatty acid monoesters in combination as the release agent. When higher alcohols and glycerin fatty acid monoesters are used in combination, the ratio is not particularly limited, but the usage amount of higher alcohols: the usage amount of glycerin fatty acid monoesters is preferably 2.5:1 to 3.5:1, more preferably 2.8:1 to 3.2:1, by mass ratio.

[0090] As a polymer processing aid, polymer particles (non-crosslinked rubber particles) having a particle diameter of 0.05 to 0.5 μm, which can usually be produced by an emulsion polymerization method, are used. The polymer particles may be single-layer particles composed of a polymer having a single composition ratio and a single limiting viscosity, or may be multi-layer particles composed of two or more polymers having different composition ratios or limiting viscosities. Examples of the antistatic agent include alkyl sulfonates such as sodium heptyl sulfonate, sodium octyl sulfonate, sodium nonyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium cetyl sulfonate, sodium octadecyl sulfonate, sodium diheptyl sulfonate, potassium heptyl sulfonate, 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, lithium nonyl sulfonate, lithium decyl sulfonate, lithium dodecyl sulfonate, lithium cetyl sulfonate, lithium octadecyl sulfonate, and lithium diheptyl sulfonate. Examples of the flame retardant include metal hydrates having a hydroxyl group or crystal water such as magnesium hydroxide, aluminum hydroxide, hydrated aluminum silicate, hydrated magnesium silicate, and hydrotalcite, phosphate compounds such as polyphosphoric acid amines and phosphate esters, and silicon compounds. Phosphate ester-based flame retardants such as trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, dimethylethyl phosphate, methyldibutyl phosphate, ethyldipropyl phosphate, and hydroxyphenyldiphenyl phosphate are preferred. Examples of dyes and pigments include red organic pigments such as para red, fire red, pyrazolone red, thioindigo red, and perylene red; blue organic pigments such as cyanine blue and indanthrene blue; and green organic pigments such as cyanine green and naphthol green. One or more of these can be used.

[0091] 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 matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, and barium sulfate. Examples of the phosphor include fluorescent pigments, fluorescent dyes, fluorescent whitening dyes, fluorescent brighteners, and fluorescent bleaching agents.

[0092] The methacrylic copolymer composition of the present invention is not particularly limited by its production method. For example, it can be produced by melt-kneading the methacrylic copolymer of the present invention, additives such as an ultraviolet absorber, and, if necessary, another polymer. The melt-kneading can be carried out using a melt-kneading apparatus such as a kneader extruder, an extruder, a mixing roll, or a Banbury mixer. The temperature during kneading can be appropriately set according to the softening temperatures of the methacrylic copolymer and the other polymer, and can be set, for example, at 150 to 300 °C. Also, the shear rate during kneading can be set, for example, at 10 to 5000 sec -1 to.

[0093] The methacrylic copolymer composition of the present invention can be formed into pellets or the like in order to enhance convenience during storage, transportation, or molding.

[0094] (Molded article) The molded article of the present invention contains the methacrylic copolymer or methacrylic copolymer composition of the present invention. The method for producing the molded article of the present invention is not particularly limited. For example, melt molding methods such as the T-die method (lamination method, coextrusion method, etc.), inflation method (coextrusion method, etc.), compression molding method, blow molding method, calender molding method, vacuum molding method, injection molding method (insert method, two-color method, press method, core-back method, sandwich method, etc.) and solution casting method can be mentioned. Among these, from the viewpoints of high productivity, cost, etc., the T-die method, inflation method or injection molding method is preferable. There is no limitation on the type of the molded article, but films (planar molded articles having a thickness of 5 μm or more and 250 μm or less) and sheets (planar molded articles thicker than 250 μm) are preferably mentioned, and among them, films are particularly preferable.

[0095] The film which is one form of the molded article 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, etc. Among these, from the viewpoint that a film excellent in transparency, having improved toughness, excellent in handleability, and excellent in the balance between toughness, surface hardness and rigidity can be obtained, the extrusion molding method is preferable. The temperature of the molten resin discharged from the extruder is preferably set at 160 to 270°C, more preferably 220 to 260°C.

[0096] Among the extrusion molding methods, the T-die method is preferable from the viewpoint that a film having good surface smoothness, good specular gloss and low haze can be obtained. In this T-die method, it is preferable to sandwich the molten resin discharged from the T-die through an extruder, a gear pump, a polymer filter, and a mixer between two or more mirror rolls or mirror belts to form a film. A bank may or may not be formed when sandwiching between the mirror roll or mirror belt. The die has an automatic adjustment function for the lip opening width, and the air gap is preferably 100 mm or less. The mirror roll or mirror belt is preferably made of metal. As the mirror roll, a metal rigid body roll, a metal elastic body roll, etc. can be used, and it is preferable to use a combination of a metal elastic body roll and a metal rigid body roll. Also, the surface temperatures of both the mirror roll and the mirror belt are preferably 130°C or lower. Further, at least one of the surface temperatures of the pair of mirror rolls or mirror belts is preferably 60°C or higher. When set to such surface temperatures, the molten resin discharged from the extruder can be cooled at a faster rate than natural cooling, and it is easy to manufacture a film with 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, and still more preferably 0.3% or less at a thickness of 100 μm.

[0097] The unstretched film obtained as described above may be subjected to a stretching treatment. By the stretching treatment, the mechanical strength can be increased, and a film that is difficult to crack can be obtained. The stretching method is not particularly limited, and examples include a simultaneous biaxial stretching method, a sequential biaxial stretching method, and a tubular stretching method. From the viewpoint of being able to stretch uniformly and obtaining a film with high strength, the lower limit of the temperature during stretching is a temperature 10°C higher than the glass transition temperature of the methacrylic copolymer or methacrylic copolymer composition, and the upper limit of the temperature during stretching is a temperature 40°C higher than the glass transition temperature of the methacrylic copolymer or methacrylic copolymer composition. Stretching is usually performed at 100 to 5000% / min. After stretching, heat setting is performed to obtain a film with little heat shrinkage. The thickness of the film after stretching is preferably 10 to 200 μm.

[0098] A functional layer may be provided on the surface of the film, which is one form of the molded body of the present invention. Examples of the functional layer include a hard coat layer, an antiglare layer, an antireflection layer, an anti-sticking layer, a diffusion layer, an antiglare layer, an antistatic layer, an antifouling layer, and a lubricity layer such as fine particles.

[0099] Further, in order to improve the adhesion strength with the above functional layer or the adhesion strength in lamination via an adhesive or an adhesive agent with another film, it is preferable to provide an undercoat layer on at least one side of the film of the present invention.

[0100] The methacrylic copolymer or the methacrylic copolymer composition of the present invention is suitable as a molding material. The molded article of the present invention can be used as a member for various applications. Specific applications include, for example, sign parts such as advertising towers, stand signs, sleeve signs, lattice signs, rooftop signs, etc. and marking films; display parts such as showcases, partition boards, store displays, etc.; lighting parts such as fluorescent lamp covers, mood lighting covers, lamp shades, light ceilings, light walls, chandeliers, etc.; interior parts such as furniture, pendants, mirrors, etc.; building parts such as doors, domes, safety window glasses, partitions, staircase waistboards, balcony waistboards, roofs of leisure buildings, etc.; transportation-related parts such as aircraft windshields, pilot visors, motorcycles, motorboat windshields, bus sunshades, automobile side visors, rear visors, head wings, headlight covers, automobile interior members, bumpers, etc.; electronic device parts such as audio-visual nameplates, stereo covers, TV protection masks, vending machines, mobile phones, personal computers, etc.; medical device parts such as incubators, X-ray parts, etc.; equipment-related parts such as machine covers, instrument covers, experimental devices, rulers, dials, observation windows, etc.; optical-related parts such as liquid crystal protection plates, light guide plates, light guide films, Fresnel lenses, lenticular lenses, front panels of various displays, diffusion plates, etc.; traffic-related parts such as road signs, guide plates, curve mirrors, soundproof walls, etc.; and others, such as greenhouse, large aquariums, box aquariums, bathroom members, watch panels, bathtubs, sanitary ware, desk mats, gaming parts, toys, musical instruments, masks for protecting the face during welding, backsheets of solar cells, front sheets for flexible solar cells, decorative films; surface materials used for personal computers, mobile phones, furniture, vending machines, bathroom members, etc.

[0101] A laminate can be obtained by laminating a layer containing the methacrylic copolymer or methacrylic copolymer composition of the present invention and another material (for example, a layer containing another thermoplastic copolymer). Examples of the other materials used in the laminate include steel materials, plastics (for example, thermoplastic resins), wood, glass, and the like. The laminate obtained by the present invention can be suitably used for wallpapers; surfaces of automotive interior members; surfaces of automotive exterior members such as bumpers; surfaces of mobile phones; surfaces of furniture; surfaces of personal computers; surfaces of vending machines; surfaces of bathroom members such as bathtubs, etc.

[0102] Since the film, which is one form of the molded article of the present invention, has high transparency and heat resistance, it is suitable for optical applications, and is particularly suitable for polarizer protection films, liquid crystal protection plates, surface materials of portable information terminals, display window protection films for portable information terminals, light guide films, transparent conductive films with silver nanowires or carbon nanotubes coated on the surface, and front panel applications of various displays. Since the film of the present invention has high transparency and heat resistance, as applications other than optical applications, it can be used for infrared cut films, anti-crime films, anti-scattering films, decorative films, metal decorative films, shrink films, and films for in-mold labels.

[0103] When the film, which is one form of the molded article of the present invention, is used as a polarizer protection film or a retardation film, it may be laminated on only one side of the polarizer film or on both sides. When laminating with the polarizer film, it can be laminated via an adhesive layer or an adhesive layer. As the polarizer film, a stretched film composed of a polyvinyl alcohol-based resin and iodine can be used, and its film thickness is preferably 1 to 100 μm.

Examples

[0104] Next, examples are shown to more specifically explain the present invention. It should be noted that the present invention is not limited by the examples.

[0105] Measurements of physical properties and the like were carried out by the following methods.

[0106] (Coincidence conversion rate) It was calculated based on the analysis performed under the following conditions by connecting GL Sciences Inc.'s INERTCAP1 (df = 0.4 μm, 0.25 mm I.D. × 60 m) as a column to a gas chromatograph GC-14A manufactured by Shimadzu Corporation. Injection temperature = 250 °C Detector temperature = 250 °C Temperature condition: Hold at 60 °C for 5 minutes → Heat up to 250 °C at 10 °C / min → Hold at 250 °C for 10 minutes

[0107] (Weight average molecular weight) The weight average molecular weight (Mw) of the resin obtained in the production example was determined by the GPC method (gel permeation chromatography). 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 at 40 °C, and 20 μl of the sample solution was injected into the apparatus at an eluent flow rate of 0.35 ml / min to measure the chromatogram. Ten standard polystyrenes with molecular weights 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 created. Based on this calibration curve, the Mw of the resin to be measured was determined. The value corresponding to the molecular weight of the standard polystyrene was taken as the molecular weight of the copolymer from the chromatogram measured by GPC. Apparatus: GPC apparatus HLC-8320 manufactured by Tosoh Corporation Separation column: TSKguardcolum SuperHZ-H, TSKgel HZM-M, and TSKgel SuperHZ4000 manufactured by Tosoh Corporation were connected in series Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml / min Column temperature: 40 °C Detection method: Differential refractive index (RI)

[0108] (Composition of each unit in the copolymer) 13The carbon ratios of the phenyl group of the α-methylstyrene unit, the methoxy group of the methyl methacrylate unit, and the carbonyl group of the maleic anhydride unit were determined by 13C-NMR, and the respective unit compositions were calculated therefrom. For the copolymer containing acrylonitrile units, the carbon ratio obtained by adding the phenyl group bonded to the α-position carbon was determined, and the respective unit compositions were calculated. For the copolymer containing methyl acrylate units, 13 In addition to 13C-NMR, the unit compositions were calculated by determining the methyl acrylate units by pyrolysis gas chromatography.

[0109] (Glass transition temperature; Tg) The resins obtained in the production examples, examples, and comparative examples were dissolved in chloroform, reprecipitated with methanol, and then the precipitated resins were vacuum dried at 80 °C for 12 hours or more. The vacuum-dried resin was measured for a DSC curve under the conditions of raising the temperature to 250 °C once, then cooling to room temperature, and then raising the temperature from room temperature to 200 °C at 10 °C / min using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-50 (product number)) in accordance with JIS K7121. The midpoint glass transition temperature determined from the DSC curve measured during the second heating was defined as the glass transition temperature in the present invention.

[0110] (Imidization rate) 1 Using 1H-NMR (manufactured by Bruker; trade name ULTRA SHIELD 400 PLUS), the 1 1H-NMR measurement was performed on the copolymer, and the value obtained by the following formula was defined as the imidization rate (R) from the area A of the peak derived from the O-CH3 group of methyl methacrylate in the vicinity of 3.5 to 3.8 ppm and the area B of the peak derived from the N-CH3 group of glutarimide and maleimide in the vicinity of 3.0 to 3.3 ppm. Imidization rate (R) (%) = [B / (A + B)] × 100

[0111] (Amount of maleic anhydride in methacrylic copolymer) Using an infrared spectrophotometer, at 1780 cm -1The absorption intensity of the peak derived from the carbonyl of maleic anhydride in the vicinity and the imidization rate (R -1 ; mol%) of maleic anhydride were determined from the absorption intensity of the peak derived from the carbonyl of maleimide in the vicinity. m 13 Based on the amount of maleic anhydride (m; mass%) and the imidization rate of the production examples determined by C-NMR, the value obtained by the following formula was taken as the amount of maleic anhydride (M; mass%) in the resins obtained in the examples and comparative examples. Amount of maleic anhydride (M) = m × (100 - R m ) / 100

[0112] (1% Thermogravimetric Decrease Temperature) The resins obtained in the production examples, examples, and comparative examples were dissolved in chloroform, reprecipitated with methanol, and then the precipitated resins were vacuum dried at 80 °C for 12 hours or more. Using a thermogravimetric analyzer (TGA-50, manufactured by Shimadzu Corporation), the temperature was raised at 10 °C / min under a nitrogen atmosphere, and the temperature at the time of 1% weight decrease was taken as the 1% thermogravimetric decrease temperature (°C).

[0113] (Flexural Modulus) The resins obtained in the production examples, examples, and comparative examples were press-molded and then machined by cutting to obtain test pieces with a thickness of 4 mm, a length of 80 mm, and a width of 10 mm. Each test piece was subjected to three-point bending at 23 °C in accordance with the method described in JIS K7171 using an autograph (manufactured by Shimadzu Corporation), and the flexural modulus (MPa) was measured.

[0114] (Saturated Water Absorption Rate) ​The resins obtained in the examples and comparative examples were subjected to cutting after press molding to obtain test pieces with a thickness of 1 mm and a side length of 50 mm. The test pieces were vacuum dried for 24 hours under the conditions of a temperature of 80°C and 5 mmHg. Then, the test pieces were allowed to cool in a desiccator. Immediately after taking out the test pieces from the desiccator, the mass (initial mass) was measured. Next, the test pieces were immersed in distilled water at 23°C. The test pieces were taken out of the water, the water adhering to the surface was wiped off, and the mass was measured. The immersion in distilled water and the mass measurement were repeated until there was no change in mass. The saturated water absorption rate (23°C) was calculated by the following formula from the mass (water absorption mass) when the mass change disappeared and the initial mass. Saturated water absorption rate (23°C) (%) = [(water absorption mass - initial mass) / initial mass] × 100

[0115] (Surface hardness) The resins obtained in the examples and comparative examples were subjected to cutting after press molding to obtain test pieces with a thickness of 3 mm and a side length of 50 mm. Using a table moving type pencil scratching tester (model P, manufactured by Toyo Seiki Co., Ltd.), while pressing the lead of the pencil against the surface of each test piece at an angle of 45 degrees and a load of 750 g, the presence or absence of scratch marks was confirmed. The hardness of the lead of the pencil increased in order, and the hardness of the lead that was one grade softer than the point at which scratch marks occurred was taken as the pencil scratching hardness. 〇: Pencil hardness is 3H or higher ×: Pencil hardness is 2H or lower

[0116] (Hot water resistance) The resins obtained in the examples and comparative examples were subjected to cutting after press molding to obtain test pieces with a thickness of 1 mm and a side length of 50 mm. The test pieces were vacuum dried for 24 hours under the conditions of a temperature of 80°C and 5 mmHg. Then, the test pieces were allowed to cool in a desiccator. Immediately after taking out the test pieces from the desiccator, the mass (initial mass) was measured. Immediately after taking out the test pieces from the desiccator, the mass (initial mass) was measured. Next, the test pieces were immersed in distilled water at 80°C. The test pieces were taken out of the water, the water adhering to the surface was wiped off, and the mass was measured. The immersion in distilled water and the mass measurement were repeated until there was no change in mass. The saturated water absorption rate (80°C) was calculated by the following formula from the mass (water absorption mass) when the mass change disappeared and the initial mass. Saturated water absorption rate (80 °C) (%) = [(absorbed water mass - initial mass) / initial mass] × 100 The heat resistance in water was evaluated from the ratio of the saturated water absorption rate (23 °C) to the saturated water absorption rate (80 °C). ◎: Saturated water absorption rate (80 °C) / saturated water absorption rate (23 °C) is less than 1.5 〇: Saturated water absorption rate (80 °C) / saturated water absorption rate (23 °C) is 1.5 or more and less than 2 ×: Saturated water absorption rate (80 °C) / saturated water absorption rate (23 °C) is 2 or more

[0117] (Moldability) Using an injection molding machine (manufactured by Meiki Seisakusho Co., Ltd., M-100C), the acrylic resin compositions obtained in the examples and comparative examples were injection molded under the conditions of a cylinder temperature of 280 °C, a mold temperature of 80 °C, and a molding cycle of 2 minutes to produce flat plates with a length of 200 mm, a width of 60 mm, and a thickness of 0.6 mm. The appearance of the flat plates was visually observed. The moldability was judged based on the presence or absence of molding defects such as sink marks due to insufficient fluidity or silver streaks due to insufficient heat resistance to decomposition. ◎: No sink marks on the molded product and no silver streaks 〇: Slight occurrence of sink marks or silver streaks on the molded product ×: Presence of sink marks or silver streaks on the molded product

[0118] <Examples of various materials> The precursor polymer (B) used the materials shown below. Precursor polymer (B); Denka's Resifine (Mw = 80000, styrene / maleic anhydride / MMA = 56% / 18% / 26%, Tg = 134 °C, 1% weight loss temperature = 340 °C, flexural modulus = 3590 MPa)

[0119] (Production example: Precursor polymer) <Production examples 1 to 8> The precursor polymers A-a to A-h were produced by the following method. Into an autoclave equipped with a stirrer, various purified monomers, 2,2'-azobis(2-methylpropionitrile) (AIBN) and n-octyl mercaptan (n-OM) were charged at the ratios shown in Table 1 and uniformly dissolved to obtain a polymerization raw material. The polymerization raw materials were continuously supplied from the autoclave to a tank reactor controlled at the polymerization temperature shown in Table 1 at a rate of 1.5 kg / hr, and a polymerization reaction was carried out by the bulk polymerization method with an average residence time of 2 to 3 hours. A liquid containing a methacrylic copolymer was continuously discharged from the tank reactor. The polymerization conversion rate became the value shown in Table 1. Next, the liquid discharged from the reactor was heated to 230 °C and supplied to a twin-screw extruder controlled at 240 °C. In the twin-screw extruder, volatile components mainly composed of unreacted monomers were separated and removed, and the methacrylic copolymer was extruded into strands. The strands were cut by a pelletizer to obtain a precursor polymer. The weight-average molecular weight Mw, the ratio of each unit composition, the glass transition temperature Tg, the 1% weight loss temperature, and the flexural modulus of the obtained precursor polymer were measured. The results are shown in Table 1. In Table 1, the following abbreviations were used. MMA: Methyl methacrylate αMSt: α-Methylstyrene Mah: Maleic anhydride MA: Methyl acrylate St: Styrene AN: Acrylonitrile

[0120]

Table 1

[0121] <Example 1> It consists of a conveying section, a melt-kneading section, a devolatilization section, and a discharge section. The precursor polymer [A-a] was supplied to the conveying section of a twin-screw extruder (manufactured by Japan Steel Works, Ltd.; trade name TEX30α-77AW-3V) set at a screw rotation speed of 100 rpm and a temperature of 230°C at a rate of 10 kg / hr. Methylamine was injected into the melt-kneading section equipped with a kneading block from the additive supply port of the twin-screw extruder at a rate of 1.0 kg / hr, and the precursor polymer [A-a] and methylamine were reacted. The melt-kneading section is mostly composed of kneading disks, and seal elements are attached to both ends thereof. In the devolatilization section set at 37 Torr (about 5 kPa), by-products and excess methylamine were volatilized from the molten resin that had passed through the melt-kneading section and discharged through a plurality of vents. The molten resin extruded as a strand from a die provided at the end of the discharge section of the twin-screw extruder was cooled in a water bath and then cut by a pelletizer to obtain pelletized methacrylic copolymer [1]. The methacrylic copolymer [1] had an imidization rate (proportion of structural unit (R)) of 17 wt% and maleic anhydride (M) of 0 wt%. Table 2 shows the physical properties of the methacrylic copolymer (A-a).

[0122] <Example 2> A methacrylic copolymer [2] was obtained in the same manner as in Example 1, except that the precursor polymer [A-b] was used instead of the precursor polymer [A-a]. Table 2 shows the physical properties of the methacrylic copolymer [2].

[0123] <Example 3> A methacrylic copolymer [3] was obtained in the same manner as in Example 1, except that the precursor polymer [A-c] was used instead of the precursor polymer [A-a]. Table 2 shows the physical properties of the methacrylic copolymer [3].

[0124] <Example 4> A methacrylic copolymer [4] was obtained in the same manner as in Example 1, except that the amount of methylamine injected was 2.0 kg / hr. Table 2 shows the physical properties of the methacrylic copolymer [4].

[0125] <Example 5> A methacrylic copolymer [5] was obtained in the same manner as in Example 1, except that the precursor polymer [A-b] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 2.6 kg / hr. The physical properties of the methacrylic copolymer [5] are shown in Table 2.

[0126] <Example 6> A methacrylic copolymer [6] was obtained in the same manner as in Example 1, except that the precursor polymer [A-d] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 0.7 kg / hr. The physical properties of the methacrylic copolymer [6] are shown in Table 2.

[0127] <Example 7> A methacrylic copolymer [7] was obtained in the same manner as in Example 1, except that the precursor polymer [A-e] was used instead of the precursor polymer [A-a]. The physical properties of the methacrylic copolymer [7] are shown in Table 2.

[0128] <Example 8> A methacrylic copolymer [8] was obtained in the same manner as in Example 1, except that the precursor polymer [A-e] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 2.7 kg / hr. The physical properties of the methacrylic copolymer [8] are shown in Table 2.

[0129] <Example 9> A methacrylic copolymer [9] was obtained in the same manner as in Example 1, except that the precursor polymer [A-f] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 2.8 kg / hr. The physical properties of the methacrylic copolymer [9] are shown in Table 2.

[0130] <Example 10> A methacrylic copolymer

[10] was obtained in the same manner as in Example 1, except that the precursor polymer [A-g] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 2.9 kg / hr. The physical properties of the methacrylic copolymer

[10] are shown in Table 2.

[0131]

Table 2

[0132] <Comparative Example 1> A methacrylic copolymer

[11] was obtained in the same manner as in Example 1, except that the precursor polymer [A-h] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 0.5 kg / hr. The physical properties of the methacrylic copolymer

[11] are shown in Table 3.

[0133] <Comparative Example 2> A methacrylic copolymer

[12] was obtained in the same manner as in Example 1, except that the precursor polymer [A-g] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 0.5 kg / hr. The physical properties of the methacrylic copolymer

[12] are shown in Table 3.

[0134] <Comparative Example 3> A methacrylic copolymer

[13] was obtained in the same manner as in Example 1, except that the precursor polymer [A-b] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 0.1 kg / hr. The physical properties of the methacrylic copolymer

[13] are shown in Table 3.

[0135] <Comparative Example 4> A methacrylic copolymer

[14] was obtained in the same manner as in Example 1, except that the precursor polymer [A-b] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 3.8 kg / hr. The physical properties of the methacrylic copolymer

[14] are shown in Table 3.

[0136] <Comparative Example 5> A methacrylic copolymer

[15] was obtained in the same manner as in Example 1, except that the precursor polymer [B] was used instead of the precursor polymer [A-a], and the amount of monomethylamine added was injected at 0.3 kg / hr. The physical properties of the methacrylic copolymer

[15] are shown in Table 3.

[0137]

Table 3

[0138] The methacrylic copolymers obtained in Examples 1 to 10 are suitable as molding materials and optical members such as polarizer protection films because they have high heat resistance, rigidity, and thermal decomposition resistance, and also excellent surface hardness, hot water resistance, and moldability. On the other hand, the methacrylic copolymers obtained in Comparative Examples 1 to 5 are outside the scope of the present invention, and thus are inferior to the present invention in any item such as poor thermal decomposition resistance, excessively high saturated water absorption rate, or poor hot water resistance and moldability.

Claims

1. A polarizer protective film comprising a methacrylic copolymer having 15 to 83 mass% of methyl methacrylate units, 7 to 35 mass% of α-methylstyrene units, 10 to 65 mass% of N-substituted glutarimide units (R) represented by formula (I), and 0 to 20 mass% of other vinyl monomer units (C) copolymerizable with methyl methacrylate, and having 0 mass% of maleic anhydride units (M). 【Chemistry 1】 (In formula (I), R １ are each independently a hydrogen atom or a methyl group; R ２ is 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 and containing an aromatic ring.

2. 2. The polarizer protective film according to claim 1, wherein the other vinyl-based monomer unit (C) copolymerizable with the methyl methacrylate unit is formed of at least one monomer selected from the group consisting of an acrylic ester monomer, an aromatic vinyl monomer, and a vinyl cyanide monomer.

3. 3. The polarizer protective film according to claim 1, wherein the other vinyl-based monomer unit (C) copolymerizable with the methyl methacrylate unit is formed of at least one selected from the group consisting of methyl acrylate, ethyl acrylate, styrene, and acrylonitrile.

4. 4. The polarizer protective film according to claim 1, wherein the methacrylic copolymer has a glass transition temperature of 140° C. or higher.

5. A polarizer protective film comprising a methacrylic copolymer composition containing a methacrylic copolymer having 15 to 83 mass% of methyl methacrylate units, 7 to 35 mass% of α-methylstyrene units, 10 to 65 mass% of N-substituted glutarimide units (R) represented by formula (I), and 0 to 20 mass% of other vinyl monomer units (C) copolymerizable with methyl methacrylate, and having 0 mass% of maleic anhydride units (M). 【Chemistry 2】 (In formula (I), R １ are each independently a hydrogen atom or a methyl group; R ２ is 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 and containing an aromatic ring.

6. 6. A laminate comprising a layer of the polarizer protective film according to claim 1 and a layer containing another material.

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