TWI609912B - Method for manufacturing (meth) acrylic resin composition, method for manufacturing optical element, and method for manufacturing polarizer - Google Patents

Abstract

By a block copolymer comprising a polymer block (a) having an alkyl (meth) acrylate unit and a polymer block (b) having a conjugated diene compound unit ( B) It is dissolved in a monomer mixture (a ') containing 50% by mass or more and 100% by mass or less of methyl methacrylate to obtain a polymerization reaction solution, and then the water content in the polymerization reaction solution is set to 1000 ppm or less, A method of polymerizing the bulk mixture (a ') to obtain a (meth) acrylic resin composition.

Description

Manufacturing method of (meth) acrylic resin composition, manufacturing method of optical member, and manufacturing method of polarizing plate

This invention relates to a (meth) acrylic resin composition, its manufacturing method, and an optical member. More specifically, the present invention relates to a (meth) acrylic resin composition having excellent toughness, high heat resistance, and almost no optical defects when used as a molded article, a method for producing the same, and a (meth) acrylic resin composition Optical component.

A polarizing plate usually has a polarizing film and a protective film layered on its two areas. This polarizing plate is an optical device incorporated in a liquid crystal display device or the like.

As a protective film for a polarizing plate, a triethyl cellulose (TAC) film was used. However, because triethyl cellulose is highly hygroscopic, if a polarizing plate using a protective film made of triethyl cellulose is exposed to high temperature conditions and high humidity and heat conditions, the degree of polarization or color will change, and there will be optical Degraded device performance.

As a substitute for triethylammonium cellulose, review the use of methacrylic resins in protective film materials.

A methacrylic resin is a material which is excellent in transparency and moisture and heat resistance, and has excellent optical homogeneity with small birefringence. Methacrylic acid Acid resins are also fragile and easy to break due to changes in tension. In order to impart toughness to such a methacrylic resin, a technique of blending a modifier into the methacrylic resin is known.

As such a modifier, the following is known. For example, Patent Document 1 discloses a multilayer structure acrylic rubber produced by an emulsion polymerization method. Patent Document 2 discloses a rubber-like substance composed of a butadiene-butyl acrylate copolymer. Patent Document 3 discloses a partially hydrogenated conjugated diene polymer. Patent Document 4 discloses a modified block copolymer composed of an alkyl (meth) acrylate unit and an aromatic vinyl monomer unit. Patent Document 5 discloses that a polymer block A mainly composed of a vinyl aromatic compound and a polymer block B mainly composed of a conjugated diene compound are epoxidized to a part of the polymer block B. Into a block copolymer. Patent Document 6 discloses an ethylene-vinyl acetate copolymer and the like. Patent Document 7 discloses a block copolymer composed of a vinyl bond-rich conjugated diene polymer component and an acrylate or methacrylate polymer component. Patent Document 8 discloses a star block copolymer having a polymer block (a) composed of an alkyl (meth) acrylate unit and a polymer block (b) composed of a conjugated diene compound unit. .

Prior art literature Patent literature

Patent Document 1 Japanese Patent Publication No. 59-36645

Patent Document 2 Japanese Patent Publication No. 45-26111

Patent Document 3 WO96 / 032440

Patent Document 4 Japanese Patent Laid-Open No. 2000-313786

Patent Document 5 Japanese Patent Application Laid-Open No. 7-207110

Patent Document 6 Japanese Unexamined Patent Publication No. 6-345933

Patent Document 7 Japanese Patent Laid-Open No. 49-45148

Patent document 8 WO2008 / 032732

However, the conventional (meth) acrylic resin composition contains a resin having a high molecular weight which is unexpectedly generated due to a polymerization reaction in a gas phase portion of a polymerization reactor and has difficulty in thermal fusion. The (meth) acrylic resin composition containing such a resin having difficulty in thermal fusion causes optical defects when forming a film or the like, and degrades the performance of an optical member.

An object of the present invention is to provide a (meth) acrylic resin composition having excellent toughness, high heat resistance, and almost no optical defects when used as a molded article, and an optical member containing the composition.

As a means for achieving the above-mentioned object, the present invention includes the following aspects.

[1] A (meth) acrylic resin composition containing 65 to 99 parts by mass so that the total of methyl methacrylate homopolymer (A) and block copolymer (B) becomes 100 parts by mass Homopolymer (A) of methyl methacrylate, and 1 to 35 parts by mass of a polymer block (a) having an alkyl (meth) acrylate unit and an conjugated diene compound unit Block copolymer (B) of the polymer block (b).

[2] The (meth) acrylic resin composition according to [1], wherein the block copolymer (B) contains a star block copolymer, and the star block copolymer contains at least a polymer block ( a) and / or the polymer block (b) formed by the arm polymer block, and the polystyrene-equivalent quantity average molecular weight calculated by gel permeation chromatography (GPC) satisfies Number average molecular weight of segment copolymer] / [number average molecular weight of arm polymer block]> 2.

[3] The (meth) acrylic resin composition according to [2], wherein the star block copolymer (B) is represented by a chemical structural formula: (polymer block (b) -polymer block ( a)-) _n X

(In the formula, X represents a coupler residue, and n represents a number exceeding 2).

[4] The (meth) acrylic resin composition according to any one of [1] to [3], further containing an ultraviolet absorber.

[5] An optical member containing the (meth) acrylic resin composition according to any one of [1] to [4].

[6] A film comprising the (meth) acrylic resin composition according to any one of [1] to [4].

[7] The film according to [6], which is obtained by applying an anti-glare treatment and / or an anti-reflection treatment.

[8] A polarizing plate comprising a polarizing film and the film according to any one of [6] or [7] bonded to at least one side thereof.

[9] A method for producing a (meth) acrylic resin composition, comprising: a polymer block (a) having an alkyl (meth) acrylate unit; and a conjugated diene compound unit. Polymer block (b) The segment copolymer (B) is dissolved in a monomer mixture (a ') containing 50% by mass or more and 100% by mass or less of methyl methacrylate to obtain a polymerization reaction solution, and then the water content in the polymerization reaction solution is set to 1000 ppm. Hereinafter, the monomer mixture (a ') is polymerized.

[10] The method for producing a (meth) acrylic resin composition according to [9], wherein the monomer mixture (a ') is made of 100% by mass of methyl methacrylate (may contain unavoidable impurities) Constituted by.

The (meth) acrylic resin composition of the present invention is excellent in toughness, high in heat resistance, and has almost no optical defects when used as a molded product. By molding the (meth) acrylic resin composition of the present invention, an optical member such as a protective film for a polarizing plate having almost no optical defects can be obtained.

According to the production method of the present invention, when the amount of water in the polymerization reaction solution is 1000 ppm or less, and a monomer mixture (a ') containing 50% by mass to 100% by mass of methyl methacrylate is polymerized, it can be easily obtained. A (meth) acrylic resin composition having excellent toughness, high heat resistance, and very few gel clumps or resin foreign matter. The (meth) acrylic resin composition obtained by the production method of the present invention is excellent in toughness and hardly causes pit-like optical defects. By molding the methacrylic resin composition obtained by the production method of the present invention, an optical member such as a protective film for a polarizing plate having almost no optical defects can be obtained.

The (meth) acrylic resin composition according to an embodiment of the present invention includes: a methyl methacrylate homopolymer (A); and a polymer block composed of an alkyl (meth) acrylate unit ( a) A block copolymer (B) of a polymer block (b) formed from conjugated diene compound units.

The amount of the methyl methacrylate homopolymer (A) is 65 to 99 parts by mass based on 100 parts by mass of the total of the methyl methacrylate homopolymer (A) and the block copolymer (B), and is preferably 77 to 99 parts by mass, more preferably 80 to 98 parts by mass, and even more preferably 83 to 97 parts by mass.

The amount of the block copolymer (B) is 1 to 35 parts by mass, preferably 1 to 23 parts by mass based on 100 parts by mass of the total of the methyl methacrylate homopolymer (A) and the block copolymer (B). Parts, more preferably 2 to 20 parts by mass, and even more preferably 3 to 17 parts by mass.

(Block copolymer (B))

The block copolymer (B) used in the present invention has a polymer block (a) made of an alkyl (meth) acrylate unit and a polymer block (b) made of a conjugated diene compound unit. )By. In addition, "(meth) acrylic acid" is a thing which abbreviate | omits "methacrylic acid or acrylic acid." The glass transition temperature of the block copolymer (B) -based polymer block (a) and / or polymer block (b) is preferably 0 ° C or lower, and more preferably -10 ° C or lower.

The polymer block (a) formed from an alkyl (meth) acrylate unit can be formed by polymerizing an alkyl (meth) acrylate. Examples of the alkyl (meth) acrylate include methyl methacrylate, ethyl methacrylate, Butyl methacrylate, cyclohexyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, and the like. These systems can be used alone or in combination of two or more. Among these, an alkyl (meth) acrylate or a combination thereof of a polymer block (a) having a glass transition temperature (Tg) of 0 ° C. or lower is preferred, and a Tg of -10 is more preferred. (Meth) acrylic acid alkyl esters of polymer blocks (a) or below, or a combination thereof. As such an alkyl (meth) acrylate, n-butyl acrylate and / or 2-ethylhexyl acrylate are preferable, and n-butyl acrylate is more preferable.

The polymer block (b) formed from a conjugated diene compound unit can be formed by polymerizing a conjugated diene. Examples of the conjugated diene include 1,3-butadiene, isoprene, pentadiene, and 2,3-dimethylbutadiene. These systems can be used alone or in combination of two or more. Among these, it is preferable to give the conjugated diene or a combination thereof of the polymer block (b) having a glass transition temperature (Tg) of 0 ° C or lower, and more preferably to give a Tg of -10 ° C or lower. Conjugated diene of polymer block (b) or a combination thereof. As such a conjugated diene, 1,3-butadiene and / or isoprene are preferred, and 1,3-butadiene is more preferred from the viewpoints of versatility, economy, and operability. Ene.

Conjugated diene systems include 1,4-addition polymerization and 1,2- or 3,4-addition polymerization. A conjugated diene having 1,4-addition polymerization has a carbon-carbon double bond in the main chain of the molecule. When conjugated diene is polymerized by 1,2- or 3,4-addition, it has a vinyl group (carbon-carbon double bond) as a side chain bond in the main chain of the molecule. The carbon-carbon double bond in the main chain of the molecule and / or the carbon-carbon double bond as the molecular side chain bond become the starting point of the grafting reaction or the crosslinking reaction. The ratio of carbon-carbon double bonds in the molecular side chain / carbon-carbon double bonds in the molecular main chain, It can be increased by adding polar compounds such as ethers to the polymerization reaction system.

The polymer block (b) may also be a hydrogenated carbon-carbon double bond in the main chain of the molecule and / or all or a part of the carbon-carbon double bond as a molecular side-chain bond. From the viewpoint of maintaining the efficacy of the present invention, the hydrogenation rate of the polymer block (b) is preferably less than 70 mol%, and more preferably less than 50 mol%. The method of hydrogenation is not particularly limited, and it can be achieved, for example, by the method disclosed in Japanese Patent Publication No. 5-20442.

The mass ratio of the polymer block (a) and the polymer block (b) is not particularly limited, but when the total of the polymer block (a) and the polymer block (b) is 100% by mass, polymerization is performed. The physical block (a) is usually 45 to 75% by mass, preferably 50 to 70% by mass. The polymer block (b) is usually 25 to 55% by mass, and preferably 30 to 50% by mass.

Although the block copolymer (B) is not particularly limited by its refractive index, when transparency is required in the (meth) acrylic resin composition of the present invention, the refractive index of the block copolymer (B) is preferably It is consistent with the refractive index of the methyl methacrylate homopolymer (A). Specifically, the refractive index of the block copolymer (B) is preferably 1.48 to 1.50, and more preferably 1.485 to 1.495.

The block copolymer (B) is preferably one containing a star block copolymer. The star block copolymer is a polymer arm connected to a plurality of arms and has a radial structure. The linking portion of the arm polymer block is usually composed of a group (coupling agent residue) derived from a polyfunctional monomer or a polyfunctional coupling agent.

The star-shaped block copolymer can be represented by, for example, the following chemical structural formula: (arm polymer block-) _n X

(In the formula, X represents a coupler residue, and n represents a number exceeding 2).

The arm polymer block preferably has at least a polymer block (a) (hereinafter also simply referred to as (a)) and a polymer block (b) (hereinafter only referred to as (b)). The structure of the arm polymer block is not particularly limited. Examples include a structure copolymerized with (a)-(b) type blocks, a structure copolymerized with (a)-(b)-(a) type blocks, and (b)-(a)- Structure of (b) type block copolymerization, structure of (a)-(b)-(a)-(b) type block copolymerization, and (a) and (b) a total of 5 or more block copolymerization Aggregation structure, etc. The plurality of arm polymer blocks constituting the star block copolymer (B) may have a structure in which all the same blocks are copolymerized, or a structure in which mutually different blocks are copolymerized. Among these, the arm polymer block is preferably a structure copolymerized with (a)-(b) type blocks. That is, the block copolymer (B) used in the present invention is preferably one containing a star-shaped block copolymer represented by the following chemical structural formula: (Polymer Block (b) -Polymer Block (a)- ) _n X, or (polymer block (a) -polymer block (b)-) _n X

(In the formula, X represents a coupling agent residue, and n represents a number exceeding 2.) More preferably, it contains a star block copolymer represented by the following chemical structural formula: (Polymer Block (b)-Polymer Block Paragraph (a)-) _n X

(In the formula, X represents a coupler residue, and n represents a number exceeding 2).

A star block copolymer suitable as a block copolymer (B) is a polystyrene-equivalent quantity average molecular weight calculated by gel permeation chromatography (GPC) which satisfies the [star average number of block copolymers] Molecular weight] / [Number average molecular weight of arm polymer block]> 2.

In addition, the ratio of [the number average molecular weight of the star block copolymer] / [the number average molecular weight of the arm polymer block] is also referred to as the number of arms.

Since the number average molecular weight of the star block copolymer is in a range exceeding 2 times the number average molecular weight of the arm polymer block, the particles of the star block copolymer (B) dispersed in the methacrylic resin are resistant to shear. The mechanical strength becomes higher, and the desired impact resistance can be obtained. Furthermore, since the number average molecular weight of the star block copolymer is greater than 100 times the number average molecular weight of the arm polymer block, it is difficult to synthesize, and the number of the industrially preferred star block copolymer (B) is average. The molecular weight is greater than 2 times and less than 100 times the number average molecular weight of the arm polymer block, more preferably 2.5 to 50 times, and even more preferably 3 to 10 times.

In addition, the block copolymer (B) used in the present invention may be an arm polymer block constituting a raw material of the star block copolymer in addition to the star block copolymer described above. The mixture residues are linked and remain in their original state.

The method for producing the block copolymer (B) used in the present invention is not particularly limited, and a method based on a known method can be adopted. Generally, as a method for obtaining a block copolymer, a method of living-polymerizing a monomer constituting a unit is adopted. Examples of such a living polymerization method include a method in which an organic rare earth metal complex is used as a polymerization initiator for polymerization; an organic alkali metal compound is used as a polymerization initiator in a mineral salt of an alkali metal or an alkaline earth metal. A method for performing anionic polymerization in the presence of a polymer; a method for performing anionic polymerization in the presence of an organoaluminum compound using an organic alkali metal compound as a polymerization initiator; an atomic mobile radical polymerization (ATRP) method and the like.

Among the above-mentioned production methods, an organic alkali metal compound is used as a polymerization initiator, and an anionic polymerization method in the presence of an organoaluminum compound is used to produce a block copolymer with a narrower molecular weight distribution and less residual monomers. It is better to implement under a relatively mild temperature condition, because the environmental load of industrial production (mainly the power consumption of the refrigerator required to control the polymerization temperature) is small.

As the polymerization initiator for the anionic polymerization, an organic alkali metal compound is usually used. As the organic alkali metal compound, methyllithium, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, second butyllithium, isobutyllithium, third butyllithium, and n-lithium can be used in combination. Alkyl lithium and alkyl dilithium such as amyl lithium, n-hexyl lithium, tetramethylene dilithium, pentamethylene dilithium, hexamethylene dilithium, etc .; phenyl lithium, m-tolyl lithium, p-toluene Aryl lithium and aryl dilithium, such as lithium, xylyl lithium, lithium naphthalene; benzyl lithium, diphenylmethyl lithium, trityl lithium, 1,1-diphenyl-3-methyl Aryl lithium and aralkyl dilithium such as dilithium produced by the reaction of amyl lithium, α-methyl styryl lithium, diisopropenylbenzene and butyl lithium; lithium dimethyl ammonium amine, lithium Lithium ammonium amines such as diethylammonium amine, lithium diisopropylammonium amine, etc .; lithium methoxylithium, lithium ethoxylate, lithium n-propoxylithium, lithium isopropoxide, lithium n-butoxide, second Lithium oxylithium, lithium third oxybutoxide, lithium pentyloxy, lithium hexyloxy, lithium heptyloxy, lithium octyloxy, lithium phenoxy, lithium 4-methylphenoxy, lithium benzyloxy, Organolithium compounds, such as lithium alkoxide, such as 4-methylbenzyloxylithium. These systems can be used alone or in combination of two or more.

Examples of the organoaluminum compound used in the anionic polymerization include the general formula: AlR ¹ R ² R ³

(Wherein R ¹ , R ² and R ³ each independently represent an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, An alkoxy group which may have a substituent, an aryloxy group which may have a substituent, or an N, N-disubstituted amine group, or R ¹ represents any of the foregoing groups, and R ² and R ³ together represent an extension which may have a substituent. Aryldioxy).

Specific examples of the organoaluminum compound represented by the general formula include trimethylaluminum, triethylaluminum, tri-n-butylaluminum, tri-secondary butyl aluminum, tri-third butyl aluminum, and triisocyanate. Trialkylaluminum such as butyl aluminum, tri-n-hexyl aluminum, tri-n-octyl aluminum, tri 2-ethylhexyl aluminum, triphenyl aluminum, dimethyl (2,6-di-third-butyl-4- Methylphenoxy) aluminum, dimethyl (2,6-di-tert-butylphenoxy) aluminum, diethyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum , Diethyl (2,6-di-tert-butylphenoxy) aluminum, diisobutyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum, diisobutyl ( 2,6-di-tert-butylphenoxy) aluminum, di-n-octyl (2,6-di-tert-butyl-4-methylphenoxy) aluminum, di-n-octyl (2,6-di Dialkyl phenoxy aluminum such as third butyl phenoxy) aluminum, methylbis (2,6-di-third butyl-4-methylphenoxy) aluminum, methyl bis (2,6 -Di-tert-butylphenoxy) aluminum, ethyl [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, ethylbis (2,6 -Di-tert-butyl-4-methylphenoxy) aluminum, ethylbis (2,6-di-tert-butylphenoxy) aluminum, ethyl [2,2'-methylenebis (4 -Methyl-6-tert-butylphenoxy)] aluminum, isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isobutylbis (2,6 -Di-tert-butylphenoxy) aluminum, isobutyl [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum, n-octylbis (2 , 6-Di-tertiary-butyl-4-methylphenoxy) aluminum, n-octyl bis (2,6-di-tertiary butyl) Alkylphenoxy) aluminum, n-octyl [2,2'-methylenebis (4-methyl-6-third-butylphenoxy)] aluminum, alkyl diphenoxy aluminum, methoxy Bis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, methoxybis (2,6-di-tert-butylphenoxy) aluminum, methoxy [2,2 '-Methylenebis (4-methyl-6-third-butylphenoxy)] aluminum, ethoxybis (2,6-di-third-butyl-4-methylphenoxy) aluminum, Ethoxybis (2,6-di-tert-butylphenoxy) aluminum, ethoxy [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] Aluminum, isopropoxy bis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isopropoxy bis (2,6-di-tert-butylphenoxy) aluminum, iso Propoxy [2,2'-methylenebis (4-methyl-6-third-butylphenoxy)] aluminum, third butoxybis (2,6-di-third-butyl-4 -Methylphenoxy) aluminum, third butoxybis (2,6-di-tert-butylphenoxy) aluminum, third butoxy [2,2'-methylenebis (4-methyl Alkyl-6-third butylphenoxy)] aluminum alkoxydiphenoxy aluminum, ginseng (2,6-di-third butyl-4-methylphenoxy) aluminum, ginseng (2 , 6-diphenylphenoxy) aluminum and the like.

These systems can be used alone or in combination of two or more. Among these organoaluminum compounds, isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) aluminum, isobutylbis (2,6-di-tert-butylbenzene) (Oxy) aluminum, isobutyl [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum system is easy to handle and does not lose activity under relatively mild temperature conditions It is preferred that anionic polymerization can be performed.

In the above anionic polymerization reaction system, in order to stabilize the polymerization reaction, dimethyl ether, dimethoxyethane, diethoxyethane, 12-crown-4, etc. Ethylamine, N, N, N ', N'-tetramethylethylenediamine, N, N, N', N ", N" -pentamethyldiethylenetriamine, 1,1,4, Coexistence of nitrogen-containing compounds such as 7,10,10-hexamethyltriethylenetetramine, pyridine, 2,2'-bipyridine and the like.

Examples of the method for obtaining the block copolymer used in the present invention include a method of polymerizing by adding a small amount of a polyfunctional monomer or a polyfunctional coupling agent to the anionic polymerization reaction system. Polyfunctional mono-system compounds having two or more ethylenically unsaturated groups. Specific examples include allyl methacrylate, ethylene glycol dimethacrylate, and 1,3-butyl dimethacrylate. Glycol esters, divinylbenzene, 1,6-hexanediol diacrylate, and the like.

The polyfunctional coupling agent is a compound having three or more reactive groups. Specific examples include trichloromethylsilane, tetrachlorosilane, butyltrichlorosilane, bis (trichlorosilyl) ethane, and Chlorotin, butyltrichlorotin, tetrachlorogermanium, etc.

From the viewpoint of improving the impact resistance of the obtained (meth) acrylic resin composition, the overall number average molecular weight (Mn) of the block copolymer (B) used in the present invention is preferably 5,000 to 1,000,000, more It is preferably 10,000 to 800,000, and particularly preferably 10,000 to 500,000.

(Methyl methacrylate homopolymer (A))

The methyl methacrylate homopolymer (A) used in the present invention is a resin obtained by polymerizing only methyl methacrylate. Since methyl methacrylate homopolymer is likely to undergo depolymerization, methyl methacrylate and methyl acrylate are usually copolymerized with a methacrylic resin. When methyl methacrylate and methyl acrylate are copolymerized, the heat resistance of the (meth) acrylic resin composition is reduced, and the composition ratio of the monomer units is deviated, and the reproduction accuracy of optical characteristics such as the refractive index is reduced.

The weight average molecular weight of the methyl methacrylate homopolymer is preferably 40,000 to 200,000, more preferably 50,000 to 180,000, and particularly preferably It is 60,000 ~ 160,000. If the weight average molecular weight is too small, the impact resistance or toughness of a molded article obtained from a (meth) acrylic resin composition tends to decrease. On the contrary, if the weight average molecular weight is too large, the fluidity of the (meth) acrylic resin composition will decrease, and the moldability will tend to decrease.

The molecular weight distribution (weight average molecular weight / number average molecular weight) of the methyl methacrylate homopolymer is preferably 1.9 to 3.0, more preferably 2.1 to 2.8, and particularly preferably 2.2 to 2.7. If the molecular weight distribution is too small, the moldability of the (meth) acrylic resin composition tends to decrease. On the contrary, if the molecular weight distribution is too large, the impact resistance of a molded article obtained from a (meth) acrylic resin composition tends to decrease.

The weight average molecular weight and the number average molecular weight are molecular weights in terms of standard polystyrene measured by GPC (gel permeation chromatography). The molecular weight or molecular weight distribution of the methacrylic resin can be controlled by adjusting the types or amounts of a polymerization initiator and a chain transfer agent.

The (meth) acrylic resin composition of the present invention is preferably one in which the block copolymer (B) forms a domain in the methyl methacrylate homopolymer (A) and is dispersed.

The size of the domain (average diameter of the domain) is not particularly limited, but is preferably 0.05 to 2.0 μm, and more preferably 0.1 to 1.0 μm. If the average domain diameter is small, the impact resistance tends to decrease, and if the average domain diameter is large, the rigidity tends to decrease, and the transparency tends to decrease. In addition, the structure and average diameter of the domains can be confirmed by a transmission electron microscope photograph of a slice cut out by an ultra-thin slice method.

The (meth) acrylic resin composition-based load deflection temperature of the present invention is preferably 90 ° C or higher, more preferably 92 ° C or higher, and even more preferably 94 ° C or higher. When the temperature is too low, the molded product is likely to be thermally deformed at a general use temperature. The deflection temperature under load is a value measured under a condition of applying a load of 1.82 MPa to a test piece having a thickness of 4 mm.

In the film made of the (meth) acrylic resin composition of the present invention, defects caused by the unmelted resin can be identified with an optical microscope or a laser microscope. The unmelted resin is transparent because it is not stained with osmium tetroxide. Therefore, the unstained defects are judged to be defects caused by the unmelted resin by microscopic observation. Among the optical defects detected in a film formed by molding a resin composition, there are defects caused by the resin composition itself, and defects caused by various conditions of the molding step. Defects caused by the resin composition itself are presumed to be mainly caused by gel clusters contained in the resin composition or unmelted resins which are difficult to melt by heat.

The (meth) acrylic resin composition system of this invention is not specifically limited by the manufacturing method. For example, there can be mentioned a method of obtaining a resin composition by melt-kneading a methyl methacrylate homopolymer (A) and a block copolymer (B) in a uniaxial or biaxial melt extruder or the like. ; Or a method of polymerizing methyl methacrylate in the presence of the block copolymer (B) to obtain a resin composition in-situ; or manufacturing an insert in the presence of a methyl methacrylate homopolymer Block copolymer (B), a method for obtaining a resin composition in situ, and the like. Among these, a method of polymerizing methyl methacrylate in the presence of the block copolymer (B) to obtain a resin composition in situ is preferable. The polymerization method is preferably a solution polymerization method or a block polymerization method, and more preferably a block polymerization method.

A method for producing a (meth) acrylic resin composition according to an embodiment of the present invention includes a step of forming a polymer block (a) having an alkyl (meth) acrylate unit and a conjugated diene compound unit. The resulting block copolymer (B) of the polymer block (b) is dissolved in a monomer mixture (a ') containing 50% by mass or more and 100% by mass or less of methyl methacrylate to obtain a polymerization reaction solution. The amount of water in the polymerization reaction solution was set to 1,000 ppm or less, and the monomer mixture (a ') was polymerized. This production method can be used in the production of the (meth) acrylic resin composition containing the methyl methacrylate homopolymer (A) and the block copolymer (B), and it can also be used to contain ( Production of (meth) acrylic resin composition of (meth) acrylic resin (A ') and block copolymer (B). In addition, the methyl methacrylate homopolymer (A) is a resin produced by polymerization of a monomer mixture (a ') composed of 100% by mass of methyl methacrylate, and a (meth) acrylic resin (A ') is a resin produced by polymerization of a monomer mixture (a') composed of less than 100% by mass of methyl methacrylate.

(Monomer mixture (a '))

The monomer mixture (a ') used in the present invention contains 50% by mass or more and 100% by mass or less, preferably contains 80% by mass or more and 100% by mass or less, and more preferably contains 80% by mass or more and 96% by mass or less of methacrylic acid. Methyl esters. The monomer mixture (a ') composed of 100% by mass of methyl methacrylate may contain unavoidable impurities.

Examples of monomers other than methyl methacrylate include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; and propyl acrylate and the like Aromatic acrylates; Cycloalkyl acrylates such as cyclohexyl acrylate and norbornene acrylate; Alkyl methacrylates other than methyl methacrylate such as ethyl methacrylate and butyl methacrylate; methyl Aryl methacrylate, such as phenyl acrylate; cyclohexyl methacrylate, norbornene methacrylate, etc .; naphthenate methacrylate; acrylamide, methacrylamide, acrylonitrile, methacrylic acid Non-crosslinkable vinyl monomers having only one polymerizable alkenyl group in one molecule, such as other vinyl monomers such as nitrile, styrene, and α-methylstyrene. The amount of monomers other than methyl methacrylate is preferably from 0% by mass to 50% by mass of all the monomer units, more preferably from 0% by mass to 20% by mass, and even more preferably from 4% by mass or more. 20% by mass or less. Among monomers other than methyl methacrylate, alkyl acrylate is preferred, and methyl acrylate is more preferred.

The amount of dissolved oxygen in the monomer mixture (a ') used in the production method of the present invention is preferably 10 ppm or less, more preferably 5 ppm or less, even more preferably 4 ppm or less, and most preferably 3 ppm or less. When the amount of dissolved oxygen is within such a range, the polymerization reaction proceeds smoothly, and a molded article without silver streaks or coloring is easily obtained.

The yellow color index of the monomer mixture (a ') used in the production method of the present invention is preferably 2 or less, and more preferably 1 or less. When the yellow index of the monomer mixture (a ') is small, when the obtained (meth) acrylic resin composition is molded, it is easy to obtain a molded product with almost no coloring at high production efficiency. In the polymerization of the monomer mixture (a ') as described later, when the polymerization conversion rate is not too high, the unreacted single system remains in the polymerization reaction solution. The unreacted single system can be recovered from the polymerization reaction solution and used again in the polymerization reaction. The yellow index of the recovered monomer will be affected by the heat applied at the time of recovery, etc. And get higher. The recovered monomer is preferably purified by an appropriate method to reduce the yellow index. The yellow index is a value measured in accordance with JIS Z-8722 using a colorimeter ZE-2000 manufactured by Nippon Denshoku Industries Co., Ltd.

The methyl methacrylate-based b ^* used in the production method of the present invention is preferably -1 to 2, and more preferably -0.5 to 1.5. When the b ^{* of the} monomer is within this range, it is easy to obtain a molded article with almost no coloring at a high productivity when the obtained (meth) acrylic resin composition is molded. In addition, b ^* is a value measured based on the International Commission on Illumination (CIE) standard (1976) or JIS Z-8722.

The mass of the block copolymer (B) relative to the monomer mixture (a ') is preferably 1/99 to 35/65, more preferably 1/99 to 23/77, and even more preferably 2/98 to 20/80. , The best is 3/97 ~ 17/83. If the block copolymer (B) is small, the impact resistance of the (meth) acrylic resin composition tends to decrease. Conversely, if the block copolymer (B) is large, not only the elastic modulus and rigidity tend to decrease, but also the reverse is unlikely to occur. It is difficult for the block copolymer (B) to be uniformly dispersed in the (meth) acrylic resin (A ') or the methyl methacrylate homopolymer (A).

The method for dissolving the block copolymer (B) in the monomer mixture (a ') is not particularly limited. For example, the block copolymer (B) can be dissolved in the monomer mixture (a ') by heating to about 30 to 60 ° C and stirring. After dissolving, it is preferable to remove unmelted resin from the polymerization reaction solution with a filter or the like.

After the block copolymer (B) is dissolved in the monomer mixture (a '), the monomer mixture (a') is polymerized. In this polymerization, the water content in the polymerization reaction solution is preferably 1,000 ppm or less, and more preferably 700 ppm. Below, it is particularly preferred to be 280 ppm or less. By reducing the amount of water in the polymerization system, it is possible to suppress the generation of resin foreign bodies of several μm to tens of μm generated during the polymerization reaction, thereby greatly reducing the use of this resin foreign body as a core when forming into a film or sheet. Occurrence of a defect of several tens of μm can obtain an optical member having high optical homogeneity. The method for adjusting the amount of water in the polymerization reaction liquid is not particularly limited. For example, a method of dehydrating the block copolymer (B), the monomer mixture (a '), and other polymerization auxiliary materials used as raw materials by adsorption or the like can be mentioned in the gas phase portion of the tank reactor. A method in which an inert gas is introduced, and a part of the monomer vapor is condensed with a brine-cooled condenser with the inert gas, and then extracted outside the system.

The polymerization is preferably performed while applying shear to the polymerization reaction solution. At the beginning of the polymerization reaction, the (meth) acrylic resin (A ') or the methyl methacrylate homopolymer (A) is dispersed in a continuous phase (polymerization reaction solution) containing the block copolymer (B). However, if the polymerization reaction is performed while applying shear, the phase containing the (meth) acrylic resin (A ') or methyl methacrylate homopolymer (A) is inverse to the phase containing the block copolymer (B). In turn, the phase containing the block copolymer (B) is dispersed in the phase containing the (meth) acrylic resin (A ') or the methyl methacrylate homopolymer (A). In addition, the polymerization conversion rate of the monomer when this reverse conversion occurs can be achieved by the block copolymer (B) and the (meth) acrylic resin (A ') or the methyl methacrylate homopolymer (A). The volume ratio, the molecular weight of the block copolymer (B), the graft ratio to the block copolymer (B), and the amount of the solvent or the type of the solvent are adjusted when a solvent is added.

During the period from the initial stage of polymerization until the reverse rotation occurs, the polymerization is preferably performed by a block polymerization method or a solution polymerization method. When the polymerization during this period is performed by a block polymerization method or a solution polymerization method, the shearing caused by the stirring is more applied to the phase containing the block copolymer (B), and reverse rotation is likely to occur.

Examples of a device for performing block polymerization or solution polymerization include a tank-type reactor with a stirrer, a tube-type reactor with a stirrer, and a tube-type reactor with a static stirring capability. These devices may be one or more, and two or more reactors of the same or different type may be connected in parallel or in series. The polymerization system may be either a batch system or a continuous system. The polymerization conversion rate of the block polymerization or the solution polymerization can be adjusted by the supply amount of the reaction raw material liquid, the extraction amount of the reaction production liquid, and the average residence time. The polymerization conversion rate is preferably 70% by mass or more. From the viewpoint of improving the toughness of a molded article such as an optical member obtained by molding the obtained methacrylic resin composition, the polymerization conversion rate is more preferably 85% by mass or more, and particularly preferably It is 90% by mass or more. In a tank-type reactor, there are usually a stirring means for stirring the liquid in the reaction tank, a supply unit for supplying a monomer mixture or a polymerization auxiliary material to the reaction tank, and a reaction product for extracting the reaction product from the reaction tank. Extraction. In a continuous flow type reaction, in order to balance the amount supplied to the reaction tank and the amount withdrawn from the reaction tank, the amount of liquid in the reaction tank should be made substantially constant. Relative to the volume of the reaction tank, the amount of liquid in the reaction tank is preferably 1/4 or more, more preferably 1/4 to 3/4, and even more preferably 1/3 to 2/3.

The size of the dispersed phase, if it is a reactor with a stirrer, can be controlled by factors such as the number of stirring rotations. If it is a tower reactor, The representative static stirred reactor can be controlled by various factors such as the linear velocity of the reaction solution, the viscosity of the polymerization reaction solution, and the graft ratio to the block copolymer (B) until the reverse rotation. In addition, after the reverse rotation occurs, a block polymerization method or a solution polymerization method may be adopted. In addition to this, a suspension polymerization method may also be adopted.

Solvents used for solution polymerization, as long as they are soluble in the monomer mixture (a '), (meth) acrylic resin (A'), or methyl methacrylate homopolymer (A) and block copolymer (B) The solvent of the ability is not particularly limited. Examples include aromatic hydrocarbons such as benzene, toluene, and ethylbenzene. These systems can be used alone or in combination of two or more. It is also possible to use the solvent which has the ability to dissolve the monomer mixture (a '), (meth) acrylic resin (A') or methyl methacrylate homopolymer (A) and block copolymer (B), Contains a solvent that does not have the ability to dissolve the monomer mixture (a '), the (meth) acrylic resin (A'), the methyl methacrylate homopolymer (A), and the block copolymer (B). Examples of the solvent having no solubility include alcohols such as methanol, ethanol, and butanol; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as hexane; and alicyclic hydrocarbons such as cyclohexane Wait. When the mixture of the monomer mixture (a ') and the solvent is taken as 100% by mass, the preferred amount of the solvent that can be used in the present invention is in the range of 0 to 90% by mass.

The polymerization initiator used in the production method of the present invention is not particularly limited as long as it generates reactive radicals, and examples thereof include azo compounds such as azobisisobutyronitrile and azobiscyclohexylcarbonitrile; Benzamidine oxide, third butyl peroxybenzoate, second third butyl peroxide, dicumene peroxide, 1,1-bis (third butyl peroxy) 3,3, 5-trimethylcyclohexane, third butyl peroxyisopropyl carbonate, Organic peroxides such as 1,1-bis (third butyl peroxy) cyclohexane, di-third butyl peroxide, third butyl peroxybenzoate, and the like. These systems can be used alone or in combination of two or more. The amount of addition of the polymerization initiator, the method of addition, and the like can be appropriately set according to the purpose, and are not particularly limited.

When the monomer mixture (a ') is polymerized, a chain transfer agent typified by an alkyl mercaptan or the like may be added to the polymerization reaction liquid as necessary. Examples of the alkyl mercaptan include n-dodecyl mercaptan, tertiary dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, and ethylene glycol dithiopropionic acid. Ester, butanediol dithioglycolate, butanediol dithiopropionate, hexanediol dithioglycolate, hexanediol dithiopropionate, trimethylolpropane ginseng- ( β-thiopropionate), pentaerythritol and thiopropionate.

The temperature during the polymerization of the monomer mixture (a ') is preferably 100 to 150 ° C, and more preferably 110 to 140 ° C. The polymerization reaction time is preferably 0.5 to 4 hours, and more preferably 1 to 3 hours. In the case of a continuous flow reactor, the polymerization reaction time is the average residence time in the reactor. If the polymerization reaction time is too short, the required amount of the polymerization initiator increases. In addition, it is difficult to control the polymerization reaction due to the increase of the polymerization initiator, and it is also difficult to control the molecular weight. On the other hand, if the polymerization reaction time is too long, it takes time until the reaction becomes stable, and productivity tends to decrease. The polymerization is preferably performed under an inert gas environment such as nitrogen.

After the polymerization is completed, unreacted monomers and solvents are usually removed. The removal method is not particularly limited, but it is preferably heating devolatilization. Examples of the devolatilization method include a balance flash method and a thermal insulation flash method. to Among these, a thermal insulation flash evaporation method is preferable. The devolatilization of the thermal insulation flash evaporation method is preferably performed at a temperature of 200 to 300 ° C, and more preferably 220 to 270 ° C. If it is lower than 200 ° C., it takes time for devolatilization, and if devolatilization is insufficient, appearance defects such as silver streaks are likely to occur in the molded body. On the contrary, when it exceeds 300 ° C., the (meth) acrylic resin composition may be colored due to oxidation, scorching, and the like.

In addition, the (meth) acrylic resin composition of the present invention may be applied to a (meth) acrylic acid by a known method in order to improve heat resistance, optical characteristics, and the like, as long as the effects of the present invention are not impaired. The resin (A ') or the methyl methacrylate homopolymer (A) is modified. The method of the modification treatment is not particularly limited. For example, the ammonium modification system can be made by dissolving a (meth) acrylic resin composition in a solvent, adding a monoalkylamine to the solution, and reacting it, or by extruding ( When a (meth) acrylic resin composition is melt-kneaded, a monoalkylamine or the like is added and reacted.

The (meth) acrylic resin composition of the present invention may further contain various additives as required. Further, if the content of the additive is too large, appearance defects such as silver streaks are liable to occur in the molded product.

Examples of the additives include antioxidants, thermal degradation inhibitors, ultraviolet absorbers, light stabilizers, slip agents, release agents, polymer processing aids, antistatic agents, flame retardants, dyes, pigments, light diffusing agents, organic Pigments, matting agents, impact modifiers, phosphors, etc.

Antioxidants are those which have the effect of preventing the resin from oxidative degradation with its monomers in the presence of oxygen. Examples include phosphorus-based antioxidants, hindered phenol-based antioxidants, and thioether-based antioxidants. These antioxidants can be used alone or in combination of two or more. Among these Among them, from the viewpoint of preventing the deterioration of optical characteristics due to coloring, a phosphorus-based antioxidant or a hindered phenol-based antioxidant is more preferred, and a combination of a phosphorus-based antioxidant and a hindered phenol-based antioxidant is more preferred.

When a phosphorus-based antioxidant and a hindered phenol-based antioxidant are used in combination, the ratio is not particularly limited, but the quality of the phosphorus-based antioxidant / hindered phenol-based antioxidant is preferably 1/5 to 2/1, and more preferably 1 / 2 ~ 1/1.

As the phosphorus-based antioxidant, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite (manufactured by Asahi Denka Co., Ltd .; trade name: ADEKA STAB HP-10) is preferred. , Ginseng (2,4-di-tert-butylphenyl) phosphite (manufactured by CIBA Special Chemicals; trade name: IRUGAFOS168) and the like.

As the hindered phenol-based antioxidant, pentaerythritol [3- (3,5-di-third-butyl-4-hydroxyphenyl) propionate] (manufactured by CIBA Specialty Chemicals; trade name IRGANOX1010), ten Octyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by CIBA Special Chemicals Corporation; trade name IRGANOX1076) and the like.

The anti-thermal deterioration agent can prevent thermal degradation of the resin by capturing polymer radicals generated when exposed to high heat in a substantially oxygen-free state.

As the thermal deterioration inhibitor, 2-third butyl-6- (3'-third butyl-5'-methyl-hydroxybenzyl) -4-methylphenylacrylate (Sumitomo Chemical Co., Ltd.) System; trade name Sumilizer GM), 2,4-di-third-pentyl-6- (3 ', 5'-di-third-pentyl-2'-hydroxy-α-methylbenzyl) phenyl acrylate ( Manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumilizer GS).

The ultraviolet absorber is a compound having an ability to absorb ultraviolet rays. The ultraviolet absorber mainly refers to a compound having a function of converting light energy into heat energy.

類、苯甲酸酯類、水楊酸酯類、氰基丙烯酸酯類、草醯替苯胺類、丙二酸酯類、甲脒類等。此等係可為單獨1種或組合2種以上使用。 Examples of the ultraviolet absorber include diphenyl ketones, benzotriazoles, and

Type, benzoate type, salicylate type, cyanoacrylate type, chlorhexidine type, malonate type, formazan type and the like. These systems can be used alone or in combination of two or more.

As the benzotriazoles, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by CIBA Special Chemicals Corporation) is preferred. ; Trade names TINUVIN329), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by CIBA Special Chemicals; trade names TINUVIN234), 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 6, 6'-bis (2H-benzotriazol-2-yl) -4,4'-bis (2,4,4-trimethylpent-2-yl) -2,2'-methylene diphenol (Made by ADEKA Corporation; trade name ADEKA STAB LA31), etc.

類，可舉出2-[4,6-二(2,4-二甲苯基)-1,3,5-三

-2-基]-5-辛氧基苯酚(CIBA特殊化學品公司製；商品名TINUVIN411L)、2-[4-[(2-羥基-3-十二氧基丙基)氧基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

/2-[4-[(2-羥基-3-參個十二氧基丙基)氧基]-2-羥基苯基]-4,6-雙(2,4-二甲基苯基)-1,3,5-三

(CIBA特殊化學品公司製；商品名TINUVIN400)、2-(4,6-二苯基-1,3,5-三

-2-基)-5-(己氧基)苯酚(CIBA特殊化學品公司製；商品名TINUVIN1577)等。 As three

Examples include 2- [4,6-bis (2,4-xylyl) -1,3,5-tris

2-yl] -5-octyloxyphenol (manufactured by CIBA Special Chemicals; trade name TINUVIN411L), 2- [4-[(2-hydroxy-3-dodecyloxypropyl) oxy] -4 , 6-bis (2,4-dimethylphenyl) -1,3,5-tri

/ 2- [4-[(2-hydroxy-3-parameter dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl)- 1,3,5-three

(Manufactured by CIBA Specialty Chemicals; trade name TINUVIN400), 2- (4,6-diphenyl-1,3,5-tris

-2-yl) -5- (hexyloxy) phenol (manufactured by CIBA Special Chemicals Corporation; trade name TINUVIN 1577) and the like.

These ultraviolet absorbers can be used individually by 1 type or in combination of 2 or more types.

The blending amount of the ultraviolet absorber is preferably 0.1 to 5 parts by mass, and more preferably 0.5 to 3 parts by mass based on 100 parts by mass of the (meth) acrylic resin composition. Examples of the method containing the ultraviolet absorber include a method in which a ultraviolet absorber is previously blended into a (meth) acrylic resin composition to be pelletized, and this is melt-extruded to form a film. In the case of melt extrusion molding Any method such as a method of directly adding an ultraviolet absorber can be used.

Light stabilizers are mainly compounds that have a function of capturing free radicals that are oxidized by light. Examples of suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

The release agent is a compound having a function of easily releasing a molded article from a mold. Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol, and higher glycerin fatty acid esters such as monoglyceryl stearate and diglyceryl stearate. In the present invention, it is preferable to use a higher alcohol and a glycerin fatty acid monoester as a release agent. When using higher alcohols and glycerol fatty acid monoesters, the ratio is not particularly limited, but the quality of higher alcohols / glycerol fatty acid monoesters is preferably 2.5 / 1 to 3.5 / 1, and more preferably 2.8 / 1 to 3.2 / 1.

The polymer processing aid is a compound that effectively exerts thickness accuracy and thinness when forming a (meth) acrylic resin composition. Polymer processing aids are generally polymer particles having a particle diameter of 0.05 to 0.5 μm that can be produced by an emulsion polymerization method.

The polymer particles may be single-layer particles composed of a polymer having a single composition ratio and a single limiting viscosity, and may also be multilayer particles composed of two or more polymers having different composition ratios or limiting viscosities. Among them, a polymer layer having a low limiting viscosity in the inner layer and a two-layer structure having a polymer layer having a high limiting viscosity of 5 dl / g or more in the outer layer are preferred.

The limiting viscosity of the polymer processing aid system is preferably 3 to 6 dl / g. If the limiting viscosity is too small, the effect of improving formability tends to decrease. If the limiting viscosity is too large, the melt flowability of the (meth) acrylic resin composition tends to decrease.

In the (meth) acrylic resin composition of the present invention, an impact modifier may be used. Examples of the impact resistance modifier include a core-shell type modifier containing acrylic rubber or diene rubber as a core layer component; a modifier containing plural rubber particles, and the like.

As the organic pigment, a compound having a function of converting ultraviolet rays harmful to the resin into visible light is preferably used.

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

Examples of the phosphor include a fluorescent pigment, a fluorescent dye, a fluorescent white dye, a fluorescent whitening agent, and a fluorescent bleach.

Examples of the lubricant include stearates such as stearic acid, linolic acid, methyl stearate, ethyl stearate, and monoglyceryl stearate; ammonium stearate and stearin Metal salts of zinc acid, calcium stearate, magnesium stearate, etc. With respect to 100 parts by mass of (methyl) The blending amount of the acrylic resin composition and the lubricant is preferably 0.01 to 0.1 parts by mass, and more preferably 0.03 to 0.07 parts by mass.

In addition, inorganic fillers such as silicon dioxide, pigment release agents such as iron oxide, paraffin-based processing oil, naphthenic-based processing oil, aromatic-based processing oil, paraffin, organic polysiloxane, and minerals can also be blended. Softeners for oils, plasticizers, flame retardants, antistatic agents, reinforcing agents for organic fibers, glass fibers, carbon fibers, metal whiskers, colorants, fluorescent whitening agents, dispersants, heat stabilizers, Light stabilizers, antioxidants and other additives or mixtures thereof.

The (meth) acrylic resin composition of the present invention can be used in combination with other resins such as impact-resistant polystyrene resin and vinyl chloride resin.

These additives may be added to the polymerization reaction solution when the monomer mixture (a ') is polymerized, or may be added to the produced (meth) acrylic resin composition.

Such a (meth) acrylic resin composition of the present invention can be molded by conventional molding methods such as injection molding, compression molding, extrusion molding, vacuum molding, and casting molding to obtain various molded products. In particular, even when the (meth) acrylic resin composition of the present invention is injection-molded at a high injection pressure at a low barrel temperature, it can provide thin-walled and wide-area molding with low residual strain and almost no coloration with high production efficiency. Product.

The (meth) acrylic resin composition system of this invention can be made into various molded articles by a well-known molding method. Examples of the molded product include an advertising tower, a vertical signboard, a side signboard, and a fence sign. Signs, roof signs, etc .; display parts such as display windows, partitions, shop displays, etc .; fluorescent lamp covers, atmosphere lighting covers, lamp covers, ceiling lights, wall lamps, chandeliers and other lighting parts; pendants, mirrors, etc. Decorative parts; Doors, domes, safety window glass, room partitions, staircase panels, balcony panels, roofs of leisure buildings, etc .; construction windshields, pilot masks, motorcycle, motorboat windshields , Parts for buses, sun visors for cars, side sun visors, rear sun visors, head wings, head lamp covers, etc .; transport parts for audio and video signs, stereo covers, TV covers, vending machines, and other electronic machine parts; conservation Parts of medical equipment such as monitors, X-ray machine parts, machinery covers, covers for measuring instruments, experimental devices, rulers, dials, observation windows, etc .; machine protection parts; LCD protection plates, light guide plates, light guide films, Fresnel Optical related parts such as lenses, lenticular lenses, front panels of various displays, diffusers, etc .; traffic related parts such as road signs, guide plates, curved mirrors, soundproof walls, etc. Pieces; polarizer protective film, polarizer protective film, retardation film, surface materials for automotive interiors, surface materials for mobile phones, marking films, etc .; top cover materials for washing machines or top surfaces of control panels, electric cookers Components for household appliances such as panels; greenhouses, large sinks, box-type sinks, clock panels, bathtubs, sanitary facilities, table mats, game parts, toys, face protection covers during welding, etc. Among these, the (meth) acrylic resin composition of the present invention is suitable for optical members, and among optical members, it is also suitable for films, and particularly suitable for protective films for polarizing plates.

[Optical member, film]

An optical member or film according to an embodiment of the present invention is a product containing a (meth) acrylic resin composition. Optical components or films A well-known molding method is obtained by, for example, an extrusion molding method or an injection molding method. Specifically, a (meth) acrylic resin composition is melt-kneaded using a single-shaft extruder, a twin-shaft extruder, a Banbury mixer, Brabender, various kneaders, and the like. Melt kneading is followed by molding using an extrusion molding machine or the like equipped with a die such as a T die, a round die, and the like to obtain a film or the like. In addition, the film of the present invention can also be obtained by blow molding, injection blow molding, inflation molding, foam molding, casting molding, etc., and a secondary processing molding method such as air pressure molding and vacuum molding can also be used. . The obtained film can be extended or surface-treated according to the application.

The film of one embodiment of the present invention has a haze value at 23 ° C of preferably 2% or less, more preferably 1.2% or less, and even more preferably 1.0% or less. If the haze value at 23 ° C is small, the film will be highly transparent, which is suitable for optical applications.

The absolute value of the photoelastic coefficient of the film according to one embodiment of the present invention at 23 ° C is preferably 8.0 × 10 ^-12 Pa ^-1 or less, more preferably 6.0 × 10 ^-12 Pa ^-1 or less, and particularly preferably 5.0 × 10 ^-12 Pa ^-1 or less. When the photoelastic coefficient is within the above range, there is little change in birefringence due to stress, and when used in a liquid crystal display device or the like, there is a tendency that the contrast or screen uniformity is excellent.

In addition, the so-called "photoelastic coefficient" is a coefficient C _R [Pa ^-1 ] indicating the ease of occurrence of a change in birefringence caused by an external force, and is defined by the following formula.

C _R = Δn / σ _R

Here, σ _R is a tensile stress [Pa], Δn is a birefringence when a stress is applied, and Δn is defined by the following formula.

Δn = n ₁ -n ₂

(In the formula, n ₁ is a refractive index in a direction parallel to the stretching direction, and n ₂ is a refractive index in a direction perpendicular to the stretching direction).

The thickness of the optical film system according to an embodiment of the present invention is preferably 100 μm or less, more preferably 10 μm or more and 90 μm or less, particularly preferably 20 μm or more and 80 μm or less, and particularly preferably 30 μm or more and 60 μm or less. In particular, when it is used as an optical film in the vicinity of a liquid crystal display, it is preferably a thickness of 100 μm or less from the viewpoint of fold-resistant strength.

The optical film system according to an embodiment of the present invention is not particularly limited by the values of the in-plane retardation value (Re), the thickness-direction retardation value (Rth), and the Nz coefficient. The hysteresis value (Re), the thickness hysteresis value (Rth), and the Nz coefficient in the plane direction can be obtained by combining the composition ratio of the materials constituting the (meth) acrylic resin composition, the thickness of the film, the extension temperature, the extension ratio, and the extension. The speed and the like are appropriately set and controlled.

Here, the in-plane direction retardation value (Re), the thickness direction retardation value (Rth), and the Nz coefficient are defined by the following formulas.

Re = (n _x -n _y ) × d

Rth = ((n _x + n _y ) / 2) -n _z ) × d

Nz = (n _x -n _z ) / ∣ (n _x -n _y ) ∣

(In the formula, n _x : the direction in which the maximum refractive index in the film plane is taken as the refractive index in the x direction when x, n _y : the direction in the film plane that is perpendicular to the x direction is taken as the y in y Refractive index in the direction, n _z : refractive index in the thickness direction of the film, d: thickness (nm) of the film).

When a film according to an embodiment of the present invention is used as a protective film for a polarizing plate, the absolute value of the retardation value (Rth) in the thickness direction is preferably 20 nm or less, more preferably 15 nm or less, and even more preferably 5 nm or less. If the absolute value of Rth exceeds 20 nm, the variation in the hysteresis value due to the incident angle is large, and problems such as a decrease in contrast may occur in the liquid crystal display device.

For the film of one embodiment of the present invention, for example, anti-glare treatment, anti-reflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, gas barrier treatment, hard coating treatment, antistatic treatment, and antifouling treatment can be suitably applied to the surface. deal with.

When a film according to an embodiment of the present invention is used as a protective film for a polarizing plate, an antistatic function can be imparted by surface treatment. Further, other members such as an adhesive layer incorporated in the optical film as required may be provided with an antistatic function.

When the film is subjected to anti-glare treatment, effects such as improvement of visibility, prevention of reflection of external light, and reduction of moire caused by drying out of light are achieved. An anti-glare layer is formed by forming a layer having a fine uneven shape on the surface of the film by an anti-glare treatment. For forming the anti-glare layer, a hard-coat material is preferably used. The thickness of the anti-glare layer is not particularly limited, but is preferably 2 μm or more and 30 μm or less, and more preferably 3 μm or more and 20 μm or less. If the thickness of the anti-glare layer is too thin, sufficient hardness cannot be obtained, and the surface tends to be easily damaged. In addition, if the thickness of the anti-glare layer is too thick, it is likely to be cracked or the film is curled due to the hardening and shrinkage of the anti-glare layer, which tends to reduce productivity.

The anti-reflection treatment is performed by providing a layer having a lower refractive index than the refractive index of the thin film on the surface of the film, or by stacking a layer having a high refractive index and a layer having a low refractive index. The low-refractive index layer or the high-refractive index layer can be formed by coating or by physical or chemical evaporation.

[Polarizer]

The polarizing plate of the present invention has a polarizing film and a film of the present invention bonded to at least one side thereof.

The polarizing film used in the present invention is not particularly limited. The polarizing film can be obtained, for example, by adding iodine or dye to polyvinyl alcohol, forming the film, and extending the film to align the molecules.

When the film attached to the polarizing film is a functional layer having an anti-reflection layer or an anti-glare layer on the surface, it is preferable to attach the film such that the functional layer becomes a surface away from the polarizing film.

Depending on the characteristics required by the polarizing plate, the film of the present invention may be laminated on both sides of the polarizing film, the film of the present invention may be laminated on one side of the polarizing film, and Films made of other resins are bonded on the surface.

The method of bonding the polarizing film and the film of the present invention is not particularly limited. For example, an adhesive containing an epoxy resin, a urethane resin, a cyanoacrylate resin, an acrylamide resin, or the like can be used for bonding.

Before laminating the polarizing film and the film of the present invention, one or both sides of the laminating surface may be subjected to a corona discharge treatment or the like. By applying the corona discharge treatment, the adhesion between the film of the present invention and the polarizing film can be improved. The so-called corona discharge treatment is to apply between electrodes A high voltage is applied to discharge, and the resin film placed between the electrodes is activated. The effect of the corona discharge treatment varies depending on the type of electrode, electrode interval, voltage, humidity, and type of resin film used, but for example, it is preferable to set the electrode interval to 1 to 5 mm and the movement speed. Around 3 ~ 20m / min. Next, the corona discharge treated surface is coated with the adhesive as described above, and the two films are bonded.

[Example]

The following examples show the present invention in more detail. The present invention is not limited by the following examples. In addition, the present invention includes all aspects in which the matters representing technical characteristics such as characteristic values, forms, manufacturing methods, and uses are arbitrarily combined.

The measurement of physical property values in the examples was performed by the following method.

<Moisture measurement>

Moisture measurement was performed using Karl Fisher (KMA-210) manufactured by Kyoto Electronics Industry Co., Ltd.

<Polymerization conversion rate>

An INERT CAP 1 (df = 0.4 μm, 0.25 mm I.D. × 60 m) manufactured by GL Sciences Inc. as a column was connected to a gas chromatograph GC-14A manufactured by Shimadzu Corporation, and the injection temperature was set to 180 ° C. The detector temperature was set to 180 ° C, the column temperature was set to 60 ° C (hold for 5 minutes) → heating rate 10 ° C / minute → 200 ° C (hold for 10 minutes), and analysis was performed to calculate based on the analysis.

<Measurement of load deflection temperature>

It measured based on JIS-K7191.

<Film appearance>

Using a pit counter (type FS-5) manufactured by Optical Control System, the resin composition was extruded at a cylinder and T die temperature of 260 ° C and a lip gap of 0.5 mm to adjust the film thickness to 75 μm to detect defects. Among the detected transparent defects, defects not stained with osmium tetroxide were regarded as unmelted pits. The following standards were used to evaluate the relative number of defects.

○: The number of unmelted pits is less than 50% of the number of unmelted pits in Example 1 (Table 2) or Example 12 (Table 3)

△: The number of unmelted pits is 50% or more and less than 100% of the number of unmelted pits in Example 1 (Table 2) or Example 12 (Table 3)

×: The number of unmelted pits is 100% or more of the number of unmelted pits in Example 1 (Table 2) or Example 12 (Table 3)

<Measurement of film thickness>

The thickness of the central portion of each film was measured using a micrometer (manufactured by MITUTOYO Co., Ltd.).

<Measurement of Haze Value>

It measured based on JIS-K7136. The haze value was measured for a film shortly after forming and a film left for 100 hours in an environment having a temperature of 85 ° C. and a relative humidity of 85%.

<Pant-shaped tear test>

The measurement was performed in accordance with JIS-K7128.

<< Synthesis Example 1 >> Production of block copolymer (B-1)

(1) Into a 1.5-liter autoclave container with a stirrer, put 640 ml of toluene and 0.009 ml of 1,2-dimethoxyethane, and perform nitrogen flushing for 20 minutes. To this was added a second butyl concentration of 1.3 mol / l A lithium cyclohexane solution was 2.86 ml, and then 72.6 ml of 1,3-butadiene was added, and reacted at 30 ° C for 1.5 hours to obtain a reaction mixture containing a 1,3-butadiene polymer. A part of the obtained reaction mixture was sampled and analyzed. As a result, the 1,3-butadiene polymer in the reaction mixture had an average molecular weight (Mn) of 24,000, a molecular weight distribution (Mw / Mn) of 1.06, and a side chain vinyl bond. The knot amount was 30 mol%.

(2) The reaction mixture obtained in the above (1) was cooled to -30 ° C, and 27.5 ml of isobutyl bis (2,6-di-tert-butyl-4-methylphenoxy) containing 0.45 mol / l was added. Base) aluminum toluene solution and 6.5 ml of 1,2-dimethoxyethane were stirred for 10 minutes to obtain a homogeneous solution.

(3) Next, while vigorously stirring the solution obtained in the above (2), 60.0 ml of n-butyl acrylate was added and polymerized at -30 ° C for 1 hour. A part of the obtained reaction mixture was sampled, and molecular weight was analyzed by GPC (polystyrene conversion). As a result, the butadiene-n-butyl acrylate diblock copolymer (arm polymer block) coefficient amount in the reaction mixture was averaged. The molecular weight was 41,000, and the weight average molecular weight / number average molecular weight ratio (Mw / Mn) was 1.02.

(4) The reaction mixture obtained in the above (3) was maintained at -30 ° C, and 3.2 ml of 1,6-hexanediol diacrylate was added under vigorous stirring, and polymerization was performed for 0.5 hours. Next, about 1 ml of methanol was added to stop the polymerization.

(5) A part of the reaction mixture obtained in the above (4) was taken out and precipitated with methanol. The obtained star block copolymer (B-1) contains 46% by mass of a polymer block (b) composed of 1,3-butadiene units and 54% by mass of an n-butyl acrylate unit The diblock copolymer composed of the polymer block (a) as the arm polymer block contains 56 molecules. A star block copolymer in which the number-average molecular weight (Mn) of the amount% (the ratio calculated from the area ratio of GPC) is 210,000 (the number of arms = 5.1) and the Mw / Mn is 1.16. Table 1 shows the characteristics of the star block copolymer (B-1). In the table, BA refers to n-butyl acrylate, and BD refers to 1,3-butadiene.

(6) 1000 g of water is added to the reaction mixture obtained in the above (4), and impurities contained in the reaction mixture are extracted with water by shaking. After standing, it was separated into a toluene solution and a water phase of the block copolymer (B-1), and the water phase was removed. Repeat this operation 4 times.

(7) The toluene solution of the block copolymer (B-1) after removing impurities by the aforementioned extraction is heated to 80 ° C., and a part of the toluene is distilled off under reduced pressure to adjust the amount of the block copolymer in the toluene solution. The concentration was 30% by mass, and a toluene solution of the block copolymer (B-1) was obtained.

<< Synthesis Example 2 >> Production of block copolymer (B-2)

A block copolymer (B-2) was produced in the same manner as in Synthesis Example 1 except that 1,6-hexanediol diacrylate was not added. The 1,3-butadiene polymer has an average molecular weight (Mn) of 24,000, a molecular weight distribution (Mw / Mn) of 1.06, and a side chain vinyl bond amount of 30 mol%. The butadiene-n-butyl acrylate diblock copolymer had a coefficient-average molecular weight of 41,000 and a weight-average molecular weight / number-average molecular weight ratio (Mw / Mn) of 1.02.

«Synthesis Example 3» Production of block copolymer (B-3)

A star block copolymer (B-3) was produced in the same manner as in Synthesis Example 1 except that the amount of 1,3-butadiene was changed to 71.1 ml and the amount of n-butyl acrylate was changed to 61.1 ml. The obtained star block copolymer (B-3) contains 45% by mass of a polymer block (b) composed of 1,3-butadiene units and 55% by mass of an n-butyl acrylate unit The polymer formed The diblock copolymer composed of the block (a) was an arm polymer block, and the number average molecular weight (Mn) containing 56% by mass (the ratio calculated from the area ratio of GPC) was 210,000 (the number of arms = 5.1). ), Mw / Mn is a star block copolymer of 1.16.

In addition, the 1,3-butadiene polymer produced during the production process had an average molecular weight (Mn) of 23,000, a molecular weight distribution (Mw / Mn) of 1.06, and a side chain vinyl bond amount of 30 mol%. The butadiene-n-butyl acrylate diblock copolymer produced in the course of production had a coefficient average molecular weight of 41,000 and a weight average molecular weight / number average molecular weight ratio (Mw / Mn) of 1.02.

«Synthesis Example 4» Production of block copolymer (B-4)

A block copolymer (B-4) was produced in the same manner as in Synthesis Example 3 except that 1,6-hexanediol diacrylate was not added. The 1,3-butadiene polymer has a molecular weight average molecular weight (Mn) of 23,000, a molecular weight distribution (Mw / Mn) of 1.06, and a side chain vinyl bond content of 30 mol%. The butadiene-n-butyl acrylate diblock copolymer had a coefficient-average molecular weight of 41,000 and a weight average molecular weight / number average molecular weight ratio (Mw / Mn) of 1.02.

Table 1 shows the characteristics of the block copolymers (B-1), (B-2), (B-3), and (B-4).

(example 1)

In an autoclave with a stirrer and a collection tube, 60 parts by mass of methyl methacrylate, 33 parts by mass of a 30% by mass toluene solution of the star block copolymer (B-1), and 7 parts by mass of toluene were added. Stir and mix. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and uniformly dissolved to obtain a polymerization reaction solution. The nitrogen in the reaction system was expelled by nitrogen. A part of this polymerization reaction liquid was collected, and the water content as measured by Karl Fischer was 1200 ppm.

The polymerization reaction liquid was heated to 115 ° C, and solution polymerization was performed for 2.5 hours. The reaction solution was separated by a collection tube. As measured by gas chromatography, the polymerization conversion ratio of the reaction solution was 60% by mass.

Next, 0.08 parts by mass of 1,1-bis (third butylperoxy) cyclohexane was added to the reaction solution, and solution polymerization was performed at 120 ° C for 2 hours to obtain a reaction solution (d-1). The polymerization conversion ratio of the reaction solution (d-1) measured by gas chromatography was 95% by mass. The reaction solution (d-1) was vacuum-dried to remove unreacted monomers and toluene to obtain a (meth) acrylic resin composition (e-1).

The dried (meth) acrylic resin composition was kneaded by an experimental plasticizer and hot-pressed to obtain a flat plate having a thickness of 4 mm. A predetermined test piece was cut out from this plate, and the load deflection temperature was measured. Table 2 shows the evaluation results.

The dried (meth) acrylic resin composition was granulated using a biaxial extruder KZW20TW-45MG-NH-600 manufactured by TECHNOVEL Co., Ltd. to form a film. Table 2 shows the evaluation results.

(Example 2)

A (meth) acrylic resin composition was obtained in the same manner as in Example 1 except that an adsorbent (Mizukasieves, manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to the polymerization reaction solution to adsorb moisture, and then the adsorbent was removed with a 2 μm filter. . The water content measured by Karl Fischer of the polymerization reaction liquid was 250 ppm. A film was formed in the same manner as in Example 1 except that the obtained (meth) acrylic resin composition was used. Table 2 shows the evaluation results.

(Example 3)

In an autoclave with a stirrer and a collection tube, 66.7 parts by mass of methyl methacrylate, 11.1 parts by mass of a 30% by mass toluene solution of the star block copolymer (B-1), and 22.2 parts by mass of toluene were added. Stir and mix. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and dissolved uniformly. The nitrogen in the reaction system was expelled by nitrogen. A part of this polymerization reaction liquid was collected, and the water content measured by Karl Fischer was 500 ppm. The polymerization reaction liquid was heated to 115 ° C, and solution polymerization was performed for 2.5 hours. The reaction solution was separated and collected by a collection tube. As measured by gas chromatography, the polymerization conversion ratio of the reaction solution was 60% by mass. A film was formed in the same manner as in Example 1 except that the obtained (meth) acrylic resin composition was used.

(Example 4)

The evaluation was performed in the same manner as in Example 3 except that the block copolymer (B-1) was changed to the block copolymer (B-2).

(Example 5)

In an autoclave with a stirrer and a collection tube, 42.9 parts by mass of methyl methacrylate, 27.1 parts by mass of the star block copolymer (B-1) and 30 parts by mass of toluene were added, and the mixture was stirred and mixed at 60 ° C. It becomes a homogeneous solution. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and dissolved uniformly. The nitrogen in the reaction system was expelled by nitrogen. A part of this polymerization reaction liquid was collected, and the water content measured by Karl Fisher was 300 ppm. The polymerization reaction liquid was heated to 115 ° C, and solution polymerization was performed for 2.5 hours. The reaction solution was separated by a collection tube. As measured by gas chromatography, the polymerization conversion ratio of the reaction solution was 60% by mass. Then, the same operation as in Example 1 was performed.

(Example 6)

In an autoclave with a stirrer and a collection tube, 61.7 parts by mass of methyl methacrylate, 5.0 parts by mass of methyl acrylate, and 11.1 parts by mass of the star block copolymer (B-3) obtained in Synthesis Example 3 were added. The toluene solution and 22.2 parts by mass of toluene were stirred and mixed. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and dissolved uniformly. The nitrogen in the reaction system was expelled by nitrogen. A part of this polymerization reaction liquid was collected, and the water content measured by Karl Fisher was 400 ppm. Solution polymerization was performed at 115 ° C for 2.5 hours. The reaction solution was separated and collected by a collection tube. As measured by gas chromatography, the polymerization conversion ratio of the reaction solution was 60% by mass. Then, the same operation as in Example 1 was performed.

As shown in Table 2, the ratio of the methyl methacrylate homopolymer (A) to the block copolymer (B) in the range of Examples 1 to 4 in the range of the present invention is low in the haze value ratio 5.

In addition, in Example 1 to Example 4 using methyl methacrylate homopolymer (A), compared with Example 6 using a copolymer of methyl methacrylate and methyl acrylate, the deflection temperature under load, that is, the heat-resistant temperature high.

(Example 7)

Iodine was adsorbed and aligned with polyvinyl alcohol to obtain a polarizing film having a thickness of about 30 μm. The film produced in Example 2 was bonded to both sides of a polarizing film via an adhesive to obtain a polarizing plate.

(Example 8) Production of (meth) acrylic resin composition (solution polymerization → solution polymerization)

In an autoclave with a mixer and a collection tube, 55.5 parts by mass of methyl methacrylate, 5.0 parts by mass of methyl acrylate, and 33 parts by mass were added. Parts of the toluene solution of the star block copolymer (B-3) obtained in Synthesis Example 3 and 7 parts by mass of toluene were stirred and mixed. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and dissolved uniformly. The nitrogen in the reaction system was expelled by nitrogen. An adsorbent (Mizukasieves, manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to the polymerization reaction solution to adsorb moisture. Then, the adsorbent was removed with a 2 μm filter. The polymerization reaction liquid was 250 ppm as measured by Karl Fisher.

This polymerization reaction liquid was heated to 115 ° C, and the solution was polymerized for 2.5 hours. The polymerization conversion was 60% by mass.

Next, 0.08 parts by mass of 1,1-bis (third butylperoxy) cyclohexane was added to the reaction solution, and the solution was polymerized at 120 ° C for 2 hours. The polymerization conversion was 95% by mass.

This was dried under vacuum to remove unreacted monomers and toluene to obtain a (meth) acrylic resin composition. The dried (meth) acrylic resin composition was pelletized using a biaxial extruder KZW20TW-45MG-NH-600 manufactured by TECHNOVEL Co., Ltd.

The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 9)

Using a biaxial extruder KZW20TW-45MG-NH-600 manufactured by TECHNOVEL Co., Ltd., 100 parts by mass of the pellet obtained in Example 8 and 200 parts by mass of (meth) acrylic resin (C) (Parapet EH- manufactured by Kuraray Corporation) were used. S) Knead and pelletize.

The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 10)

In an autoclave with a stirrer and a collection tube, 61.7 parts by mass of methyl methacrylate, 5.0 parts by mass of methyl acrylate, and 11.1 parts by mass of the star block copolymer (B-3) obtained in Synthesis Example 3 were added. The toluene solution and 22.2 parts by mass of toluene were stirred and mixed. Then, 0.03 parts by mass of 1,1-bis (third butylperoxy) cyclohexane and 0.2 parts by mass of n-dodecyl mercaptan were added and dissolved uniformly. The nitrogen in the reaction system was expelled by nitrogen. The water content of the polymerization reaction liquid measured by Karl Fisher was 500 ppm. The solution was polymerized at 115 ° C for 2.5 hours. The polymerization conversion was 60% by mass.

Next, 0.08 parts by mass of 1,1-bis (third butylperoxy) cyclohexane was added to the reaction solution, and the solution was polymerized at 120 ° C for 2 hours. The polymerization conversion was 95% by mass.

This was dried under vacuum to remove unreacted monomers and toluene to obtain a (meth) acrylic resin composition. The dried (meth) acrylic resin composition was pelletized using a biaxial extruder KZW20TW-45MG-NH-600 manufactured by TECHNOVEL Co., Ltd.

The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 11)

Except that the toluene solution of the star block copolymer (B-3) obtained in Synthesis Example 3 was changed to the toluene solution of the star block copolymer (B-4) obtained in Synthesis Example 4, the same procedure as in Example 8 was used. Particles of a (meth) acrylic resin composition were obtained by a method. The water content of the reaction solution was 690 ppm as determined by Karl Fisher. The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 12)

A pellet of a (meth) acrylic resin composition was obtained in the same manner as in Example 8 except that an adsorbent was not added to the polymerization reaction solution. The water content of the reaction solution was 1500 ppm as measured by Karl Fisher. The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 13)

Using a biaxial extruder KZW20TW-45MG-NH-600 manufactured by TECHNOVEL Co., Ltd., 100 parts by mass of the pellets obtained in Example 12 and 200 parts by mass of (meth) acrylic resin (C) (Parapet EH- manufactured by Kuraray Corporation) S) Granulated. The pellets are used for film forming. Table 3 shows the evaluation results.

(Example 14)

A pellet of a (meth) acrylic resin composition was obtained in the same manner as in Example 11 except that an adsorbent was not added to the polymerization reaction solution. The water content of the reaction solution was 2100 ppm as measured by Karl Fisher. The pellets are used for film forming. Table 3 shows the evaluation results.

As shown in Tables 2 and 3, it can be seen that when the (meth) acrylic resin was polymerized with a water content of 1,000 ppm or less compared to Examples 1 and 12 to 14 with a water content exceeding 1000 ppm, Examples 2 to 6 and Examples The defects caused by unmelted pits in 8 to 11 cases were reduced.

Claims (10)

A method for producing a (meth) acrylic resin composition, comprising: a polymer having a polymer block (a) composed of an alkyl (meth) acrylate unit and a polymer composed of a conjugated diene compound unit The block copolymer (B) of the block (b) is dissolved in a monomer mixture (a ') containing 100% by mass of methyl methacrylate (which may contain unavoidable impurities) to obtain a polymerization reaction solution. Next, the water content in the polymerization reaction solution is set to 1000 ppm or less, and the amount of the polymerization reaction solution in the reaction tank is adjusted to 1/4 to 3/4 with respect to the volume of the reaction tank. A polymerization initiator polymerizes the monomer mixture (a '). For example, the method for producing a (meth) acrylic resin composition according to claim 1, wherein the (meth) acrylic resin composition is a total of methyl methacrylate homopolymer (A) and block copolymer (B). The method of 100 parts by mass contains: 65 to 99 parts by mass of a methyl methacrylate homopolymer (A), and 1 to 35 parts by mass of a polymer block having a polymer block formed from an alkyl (meth) acrylate unit ( a) A block copolymer (B) with a polymer block (b) formed from a conjugated diene compound unit. The method for producing a (meth) acrylic resin composition according to claim 1, wherein the block copolymer (B) contains a star block copolymer, and the star block copolymer contains at least a polymer block (a ) And / or the polymer block of the polymer block (b), and The polystyrene-equivalent number average molecular weight calculated by gel permeation chromatography (GPC) satisfies [number average molecular weight of star block copolymer] / [number average molecular weight of arm polymer block]> 2. For example, the method for producing a (meth) acrylic resin composition according to claim 3, wherein the star block copolymer (B) is represented by the following chemical structural formula: (polymer block (b)-polymer block ( a)-) _n X (wherein X represents a coupling agent residue, and n represents a number exceeding 2). The method for producing a (meth) acrylic resin composition according to claim 1, further comprising adding an ultraviolet absorber. The method for producing a (meth) acrylic resin composition according to claim 1, wherein the dissolved oxygen content of the monomer mixture (a ') is 10 ppm or less. For example, the method for producing a (meth) acrylic resin composition according to claim 1, wherein the method for reducing the water content in the polymerization reaction solution to 1,000 ppm or less is to adsorb the block copolymer (B) and the monomer mixture (a) by adsorption. ') A method of dehydrating; or introducing an inert gas into the gas phase part of the tank-type reactor, so that a part of the monomer vapor and the inert gas are condensed by a condenser cooled by brine, and extracted to Method outside the system. A method for manufacturing an optical member, comprising: implementing the manufacturing method according to any one of claims 1 to 7 to obtain a (meth) acrylic resin composition; and molding the (meth) acrylic resin composition. The method for manufacturing an optical member according to claim 8, wherein the optical member is a film. A method of manufacturing a polarizing plate, comprising: obtaining an optical member by the manufacturing method of claim 9; and bonding the optical member to at least one side of a polarizing film.