TW201905013A - Methacrylic acid copolymer and formed body - Google Patents

Abstract

The present invention provides a methacrylic copolymer containing 5 to 50% by mass of a structural unit derived from a monomer represented by formula (1) and 50 to 95% by mass of a structural unit derived from methyl methacrylate. (In formula (1), R1 represents a hydrogen atom or a methyl group; and R2 and R3 independently represent a linear, branched or cyclic monovalent hydrocarbon group having 1 to 15 carbon atoms, or R2 and R3 may bond to each other to form, in conjunction with a carbon atom to which R2 and R3 are bonded, an aliphatic hydrocarbon ring).

Description

Methacrylic acid copolymer and shaped body

The present invention relates to a methacrylic acid copolymer and a formed body containing the same.

BACKGROUND OF THE INVENTION In general, methacrylic resins have excellent optical properties such as transparency and weather resistance. Therefore, they have been conventionally used in various applications such as lighting fixtures, display members for sign boards, electronic and electrical members, and medical members. on. In these applications, in addition to optical characteristics and weather resistance, thermal decomposition resistance may be particularly important.

Examples of the method for improving the physical properties of the methacrylic resin include a method of copolymerizing a monomer having a specific structure. For example, Patent Document 1 discloses a copolymerization of a monomer derived from a cycloalkyl methacrylate, which can produce less coloring, high transparency, low haze, high impact strength, low saturated water absorption, small dimensional change, and Good appearance molded product.

On the other hand, copolymerization of a monomer having a functional group such as a hydroxyl group is also expected to improve the physical properties of the resin. However, Patent Document 2 discloses that if methyl methacrylate is copolymerized with a monomer having a hydroxyl group, gelation will occur during the reaction, and thus there remains a problem in preparing a copolymer for molding materials.

Prior Art Literature Patent Literature Patent Literature 1: WO2013-161267 Patent Literature 2: Japanese Patent No. 3550152

Summary of the Invention Problems to be Solved by the Invention The object of the present invention is to provide a copolymer that uses a polymerizable monomer containing a hydroxyl group in an appropriate amount, is not easily thermally decomposed, has good chemical resistance, and can suppress gelation during melt molding.

Means for Solving the Problems According to the present invention, the aforementioned objects can be achieved by the following aspects. [1] A methacrylic acid copolymer comprising 5 to 50% by mass of a structural unit derived from a monomer represented by the following formula (1) and 50 to 95% by mass of a structural unit derived from methyl methacrylate;

[Chemical Formula 1]

(In formula (1), R ¹ represents a hydrogen atom or a methyl group; R ² and R ³ are each independently a linear, branched or cyclic monovalent hydrocarbon group having 1 to 15 carbon atoms, or R ² and R ³ They may also be bonded to each other to form an aliphatic hydrocarbon ring with the carbon atoms to which they are bonded). [2] The methacrylic acid copolymer according to [1], wherein the sum of the carbon number of R ^{2 and} the carbon number of R ³ in the monomer represented by the formula (1) is 2 to 9. [3] The methacrylic acid copolymer according to [1] or [2], wherein the weight average molecular weight is 40,000 to 300,000. [4] The methacrylic acid copolymer according to any one of [1] to [3], wherein a ratio of a weight average molecular weight to a number average molecular weight is 1.01 to 3.0. [5] The methacrylic acid copolymer according to any one of [1] to [4], wherein a ratio Mw / Mn of a weight average molecular weight Mw to a number average molecular weight Mn is heat-treated at 260 ° C for 1 hour The value is 1.4 times or less the value before the treatment. The weight average molecular weight Mw and the number average molecular weight Mn are calculated based on a chromatogram obtained by gel permeation chromatography and converted into polystyrene. [6] The copolymer according to any one of [1] to [5], wherein the Mw / Mn after the heat treatment at 260 ° C for 1 hour is 1.2 times or less the value before the treatment. [7] A molded article containing the copolymer according to any one of [1] to [6] in an amount of 80% by mass or more. [8] The formed article according to [7], which is a molten formed article. [9] The formed article according to [7] or [8], which is a sheet having a thickness of 0.5 mm or more. [10] The formed article according to [7] or [8], which is a thin film having a thickness of 1 μm to 500 μm.

ADVANTAGE OF THE INVENTION The methacrylic acid copolymer of this invention has the outstanding chemical resistance, and has inhibited the generation | occurrence | production of a gel substance at the time of melt molding.

Mode for Carrying Out the Invention The methacrylic acid copolymer (hereinafter sometimes referred to simply as "copolymer") of the present invention contains a structural unit derived from a monomer represented by formula (1).

The monomer represented by the formula (1) has a hydroxyl group, and after being copolymerized, drug resistance can be imparted. In addition, it can also be expected to improve the mechanical strength and improve its adhesion to dissimilar materials such as metals. By having the substituents R ² and R ³ , it is possible to impart high heat resistance to the obtained copolymer. In addition, the carbon atom at the bonding site of (meth) acryloxymethyl and hydroxymethyl becomes a fourth-order carbon atom through substituents R ² and R ^3, and is bonded to (methyl) via methylene ) Acrylic fluorenyloxy and hydroxyl groups are less likely to be detached by heating and have excellent thermal decomposition resistance. If the carbon atom is a second- or third-order carbon atom, the thermal decomposition resistance of the obtained copolymer is reduced, and the molding temperature is limited.

[Chemical Formula 2]

(In formula (1), R ¹ represents a hydrogen atom or a methyl group; R ² and R ³ are each independently a linear, branched or cyclic monovalent hydrocarbon group having 1 to 15 carbon atoms, or R ² and R ³ They may also be bonded to each other to form an aliphatic hydrocarbon ring with the carbon atoms to which they are bonded).

The copolymer of the present invention contains 5 to 50% by mass of the structural unit derived from the monomer represented by the formula (1) based on the mass of the copolymer, and preferably contains 8 to 40% by mass, and more preferably 10 to 20% by mass. When the content of the structural unit derived from the monomer represented by the formula (1) is within this range, the thermal decomposition resistance of the copolymer of the present invention is excellent. In a preferred embodiment of the present invention, the sum of the carbon number of R ^{2 and} the carbon number of R ³ in the monomer represented by the formula (1) is preferably 2 to 9.

The carbon number of the monovalent hydrocarbon group represented by R ² and R ³ is 1 to 15, and preferably 1 to 12, more preferably 1 to 8, more preferably 1 to 6, and particularly preferably 1 to 4. Specifically, the monovalent hydrocarbon groups having 1 to 15 carbon atoms represented by R ² and R ³ can independently list the following linear, branched, or cyclic monovalent hydrocarbon groups: methyl, ethyl, propyl, and isopropyl , N-butyl, secondary butyl, tertiary butyl, pentyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopropyl, cyclobutyl, cyclo Amyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, methylcyclohexylmethyl, ethylcyclohexyl Methyl, ethylcyclohexylethyl, bicyclo [2.2.1] heptyl, bicyclo [2.2.1] heptylmethyl, bicyclo [2.2.1] heptylethyl, bicyclo [2.2.1] heptylbutyl Methyl, methylbicyclo [2.2.1] heptylmethyl, ethylbicyclo [2.2.1] heptylmethyl, ethylbicyclo [2.2.1] heptylethyl, bicyclo [2.2.2] octyl, Bicyclo [2.2.2] octylmethyl, bicyclo [2.2.2] octylethyl, bicyclo [2.2.2] octylbutyl, methylbicyclo [2.2.2] octylmethyl, ethylbicyclo [ 2.2.2] octylmethyl, ethylbicyclo [2.2.2] octylethyl, tricyclo [5.2.1.0 ^2,6 ] decyl, tricyclo [5.2.1.0 ^2,6 ] decylmethyl, Tricyclic [5. 2.1.0 ^2,6 ] decylethyl, tricyclo [5.2.1.0 ^2,6 ] decylbutyl, methyltricyclo [5.2.1.0 ^2,6 ] decylmethyl, ethyltricyclo [5.2 .1.0 ^2,6 ] decylmethyl, ethyltricyclo [5.2.1.0 ^2,6 ] decylethyl, adamantyl, adamantylmethyl, adamantylethyl, adamantylbutyl, methyl adamantyl group, ethyl adamantyl group, methyl, ethyl adamantyl group, tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl, tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecylmethyl, tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecyl group, tetracyclo [4.4.0.1 ^2,5 .1 ^{7 , 10]} dodecane butyl, ethyl tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] dodecylmethyl, ethyltetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] Dodecylethyl, phenyl, tolyl, naphthyl, and the like. Among these monovalent hydrocarbon groups, methyl, ethyl, n-propyl, isopropyl, and n-butyl are preferred. When R ² and R ^{3 are} different, the carbon atom to which R ² and R ³ are bonded is an asymmetric carbon, and R ² and R ³ may have asymmetric carbon. When the monomer represented by formula (1) of the present invention is an optically active compound having one or more asymmetric carbons, it includes all of the following: simple mirror image isomers of R or S with respect to each asymmetric carbon, Or a monomer (including a racemic mixture) in which the R-form and the S-form are mixed at an arbitrary ratio.

R ² and R ³ may also be bonded to each other to form an aliphatic hydrocarbon ring with the carbon atoms to which they are bonded. In this case, the aliphatic hydrocarbon ring may include cyclopropane, cyclobutane, cyclopentane, and cyclohexane. , bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6] decane, adamantane, tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] Alicyclic hydrocarbons with 3 to 12 carbons, such as dodecane, and which may contain condensed rings of this type, or some of the hydrogen atoms of these alicyclic hydrocarbons have been linear, branched, or cyclic carbons Monovalent hydrocarbon groups of 1 to 15 are substituted. Among these aliphatic hydrocarbon rings, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, adamantane It is better to use cyclopentane and cyclohexane.

The monomer represented by the formula (1) of the present invention may further specifically include the following, but is not limited thereto.

[Chemical Formula 3] (Wherein R ¹ is the same as above).

The copolymer of the present invention contains, in addition to the monomer represented by the above formula (1), 50% to 95% by mass of structural units derived from methyl methacrylate based on the mass of the copolymer. The content of the structural unit derived from methyl methacrylate is preferably 60% by mass to 92% by mass, and particularly preferably 80% by mass to 90% by mass.

The copolymer of the present invention may have a monomer derived from a radically polymerizable monomer (hereinafter sometimes referred to as a radically polymerizable monomer (2)) other than the monomer represented by the formula (1) and methyl methacrylate. Structural units. Examples of the radical polymerizable monomer (2) include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, secondary butyl acrylate, and tertiary acrylic acid. Butyl, pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate and other alkyl acrylates; 2-hydroxyethyl acrylate, 2-ethyl acrylate Acrylic acid derivatives such as oxyethyl ester, propylene acrylate, allyl acrylate, and benzyl acrylate; vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, p-methylstyrene, and m-methylstyrene ; Vinyl cyclohexane, vinyl cyclopentane, vinyl cyclohexene, vinyl cycloheptane, vinyl cycloheptene, vinyl norbornene and other vinyl alicyclic hydrocarbons; maleic anhydride, maleic Ethylenically unsaturated carboxylic acids such as acids and itaconic acids; olefins such as ethylene, propylene, 1-butene, isobutylene, and 1-octene; conjugated dienes such as butadiene, isoprene, and laurene; propylene Fluoramine, methacrylamide, acrylonitrile, methacrylonitrile, ethyl acetate Alkenyl ester, vinyl ketone, vinyl chloride, vinylidene chloride, difluoroethylene; 2-vinylfuran, 2-isopropenylfuran, 2-vinylbenzofuran, 2-isopropenylbenzofuran, 2-vinyldibenzofuran, 2-vinylthiophene, 2-isopropenylthiophene, 2-vinyldibenzothiophene, 2-vinylpyrrole, N-vinylindole, N-vinylcarbazole 2-vinyl Azole, 2-isopropenyl Azole, 2-vinylbenzo Azole, 3-vinyl iso Azole, 3-isopropenyl iso Azole, 2-vinylthiazole, 2-vinylimidazole, 4 (5) -vinylimidazole, N-vinylimidazole, N-vinylimidazoline, 2-vinylbenzimidazole, 5 (6) -ethylene Benzimidazole, 5-isopropenylpyrazole, 2-isopropenyl 1,3,4- Diazole, vinyltetrazole, 2-vinylpyridine, 4-vinylpyridine, 2-isopropenylpyridine, 3-vinylpyridine, 3-isopropenylpyridine, 2-vinylquinoline, 2-iso Propylquinoline, 4-vinylquinoline, 4-vinylpyrimidine, 2,4-dimethyl-6-vinyl-S-triazine , 3-methinedihydrofuran-2 (3H) -one, 4-methyl-3-methinedihydrofuran-2 (3H) -one, 4-decyl-3-methinedihydro Ethylene unsaturated heterocyclic compounds such as furan-2 (3H) -one; dimethylmethacryloxymethyl phosphate, 2-methacryloxy-1-methylethyl phosphate, etc. Phosphate esters with ethylenically unsaturated groups, etc.

From the viewpoint of the balance of heat resistance, low water absorption, melt moldability, etc., the amount of the structural unit derived from the radical polymerizable monomer (2) contained in the copolymer of the present invention is appropriate relative to the mass of the copolymer. 15 mass% or less, more preferably 10 mass% or less, and even more preferably 5 mass% or less. The amount of the structural unit derived from the radical polymerizable monomer (2) contained in the copolymer of the present invention may be 0.5% by mass or more.

The weight average molecular weight of the copolymer of the present invention is preferably 40,000 to 300,000, more preferably 60,000 to 250,000, and particularly preferably 80,000 to 200,000. When the weight average molecular weight is within this range, strength and moldability are excellent.

The measurement by gel permeation chromatography can be performed in the following manner. Tetrahydrofuran as the eluent and two TSKgel SuperMultiporeHZM-M manufactured by Tosoh Corporation as a column were used in series with SuperHZ4000. As the analysis device, HLC-8320 (model) manufactured by Tosoh Corporation with a differential refractive index detector (RI detector) was used. 4 mg of a methacrylic acid copolymer, which is a test target resin material, was dissolved in 5 ml of tetrahydrofuran, and then filtered through a 0.1 μm filter to prepare a test target solution. The column oven temperature was set to 40 ° C, and 20 μl of the test object solution was injected at a flow rate of 0.35 ml / min of the eluent, and the chromatogram was measured. The chromatogram is a graph obtained by comparing the electric signal value (intensity Y) of the refractive index difference between the test solution and the control solution with the retention time X.

Gel permeation chromatography was used to measure standard polystyrene with a molecular weight in the range of 400 to 5,000,000, and a detection line showing the relationship between retention time and molecular weight was made. In the chromatogram, the line connecting the point where the slope of the high molecular weight side turns from zero to a positive value and the point where the slope of the low molecular weight side turns from a negative value to zero is used as a baseline. When there are multiple peaks in the chromatogram, the line connecting the point where the slope of the highest molecular weight side turns from zero to a positive value and the point where the slope of the lowest molecular weight side turns from a negative value to zero is used as the baseline.

The weight-average molecular weight / number-average molecular weight ratio of the copolymer of the present invention (hereinafter, this ratio is referred to as "molecular weight distribution") is preferably 1.01 to 3.0, and more preferably 1.05 in a state before heat treatment at 260 ° C for 1 hour. ~ 2.7, more preferably 1.10 ~ 2.5. When the molecular weight distribution is within this range, a copolymer having excellent moldability can be obtained. The weight average molecular weight and the number average molecular weight are values measured by GPC (gel permeation chromatography) and converted into standard polystyrene.

The weight average molecular weight and molecular weight distribution can be controlled by adjusting the type or amount of a polymerization initiator and a chain transfer agent during the polymerization reaction.

The Mw / Mn value of the copolymer of the present invention after being subjected to heat treatment at 260 ° C for one hour should preferably be 1.0 to 1.4 times the value before the treatment, and preferably 1.0 to 1.2 times, more preferably 1.0 to 1.15 times, and 1.0 to 1.1. Times better. The smaller this value is, the more it tends to suppress the occurrence of gels during melt molding.

The 1-hour heat treatment at 260 ° C is used to evaluate the gelation of the methacrylic acid copolymer. With this treatment, the copolymer with a Mw / Mn value greater than 1.4 times the value before the treatment will be partially contained in the molding machine. Gelation produces a gel.

The methacrylic acid copolymer of the present invention includes molding materials having various shapes such as powder and pellets. For example, a pellet-like molding material can be extruded from a dies plate into a bundled resin by extruding a molding machine, and the resin is cooled and cut to be made of. The method for cutting the aforementioned bundles into pellets may adopt water cutting, hot cutting, strand cutting and the like.

When formed into pellets and other shapes, the methacrylic acid copolymer will withstand the thermal history; the methacrylic acid copolymer of the present invention may be a monomer containing a (meth) acrylate having a hydroxyl group and a methyl methacrylate. The powder is then purified by reprecipitation, etc., and the powder has less thermal history after drying, and can also be formed into various shapes such as pellets and thermal history.

The glass transition temperature of the copolymer of the present invention is preferably 100 to 350 ° C, and more preferably 110 to 250 ° C. If the glass transition temperature is too low, the heat resistance of the copolymer will be insufficient, and the applicable applications will be limited. If the glass transition temperature is too high, the copolymer will become brittle and easily break. The glass transition temperature is a value measured in accordance with JIS K7121. That is, the intermediate-point glass transition temperature can be set as the glass-transition temperature of the present invention. The intermediate-point glass-transition temperature is that the copolymer of the present invention is first heated to 270 ° C, then cooled to room temperature, and then at 10 ° C / The DSC curve was measured by differential scanning calorimetry under the condition that the temperature was raised from room temperature to 270 ° C in one minute, and was obtained from the DSC curve measured at the second temperature increase.

The thermal decomposition temperature of the copolymer of the present invention is preferably 270 ° C or higher, more preferably 290 ° C or higher, more preferably 295 ° C or higher, and particularly preferably 300 ° C or higher. The thermal decomposition temperature may be 320 ° C or lower. In addition, the thermal decomposition temperature can be measured by the method set forth in the examples.

The method for producing the copolymer of the present invention is not particularly limited. In general, from the viewpoint of productivity, a method for producing a copolymer by adjusting a polymerization temperature, a polymerization time, a type and amount of a chain transfer agent, a type and amount of a polymerization initiator, and the like by using a radical polymerization method is preferable. In addition, the monomer represented by the formula (1) can also be anionically polymerized. Therefore, when a block copolymer or a copolymer having high stereoregularity is to be obtained, an anion polymerization method can also be adopted.

The radical polymerization method for producing the copolymer of the present invention is preferably carried out in a solvent-free or solvent, and from the viewpoint of obtaining a copolymer having a low impurity concentration, it is preferably carried out in a solvent-free manner. From the viewpoint of suppressing the generation of silver marks or coloration in the formed body, the polymerization reaction should preferably be carried out after reducing the amount of dissolved oxygen in the polymerization reaction raw material. The polymerization reaction is preferably performed in an inert gas environment such as nitrogen.

The polymerization initiator which can be used in the radical polymerization method for producing the copolymer of the present invention is not particularly limited as long as it can generate reactive radicals. Examples include tertiary hexylperoxyisopropyl monocarbonate, tertiary hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethyl Caproate, tertiary butyl peroxy trimethylacetate, tertiary hexanoyl trimethylacetate, tertiary butyl peroxydecanoate, tertiary hexaperoxide neodecanoate, neodecyl peroxide Acid 1,1,3,3-tetramethylbutyl ester, 1,1-bis (tertiary hexylperoxy) cyclohexane, benzamidine peroxide, 3,5,5-trimethylhexane Samarium, Laurel peroxide, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), dimethyl 2,2'-azobis (2- Methyl propionate) and the like. Among these, tertiary hexylperoxy 2-ethylhexanoate, 1,1-bis (tertiary hexylperoxy) cyclohexane, and dimethyl 2,2'-azobis (2- Methylpropionate) is preferred.

The one-hour half-life temperature of the polymerization initiator is preferably 60 to 140 ° C, and more preferably 80 to 120 ° C. In addition, the hydrogen abstraction energy of the polymerization initiator used for producing the copolymer is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. Such a polymerization initiator may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the polymerization initiator used is preferably 0.0001 to 0.02 parts by mass, more preferably 0.001 to 0.01 parts by mass, and even more preferably 0.005 to 0.007 parts by mass, relative to 100 parts by mass of the monomers used for the polymerization reaction.

In addition, the hydrogen abstraction energy can be obtained from the technical information of the polymerization initiator manufacturer (for example, the technical information of "Nippon Oil and Fat Co., Ltd." Hydrogen Abstraction Energy of Organic Peroxides and Initiator Efficiency "(prepared in April 2003)). The measurement can be performed by a radical capture method using an α-methylstyrene dimer, that is, an α-methylstyrene dimer capture method. This measurement is generally performed as follows. First, in the presence of an α-methylstyrene dimer as a radical trapping agent, the polymerization initiator is cracked to generate radical fragments. Among the generated free radical fragments, free radical fragments with lower hydrogen abstraction energy are added to the double bond of α-methylstyrene dimer and captured. On the other hand, free radical fragments with higher hydrogen abstraction energy are obtained by taking hydrogen from cyclohexane to generate cyclohexyl radicals, which will be added to the double of the α-methylstyrene dimer. The bond is captured, and a cyclohexane capture product is generated. Therefore, the ratio (mole fraction) of free radical fragments with high hydrogen abstraction energy to the theoretical amount of free radical fragments generated can be obtained by quantifying the cyclohexane or the products captured by cyclohexane and quantify them. Think of hydrogen abstraction.

Examples of the chain transfer agent used in the radical polymerization method for producing the copolymer of the present invention include n-octyl mercaptan, n-dodecyl mercaptan, tertiary dodecyl mercaptan, and 1,4-butane. Dithiol, 1,6-hexanedithiol, ethylene glycol dithiopropionate, butanediol dithiopropionate, butanediol dithiopropionate, hexanediol dithiopropionate, Alkyl mercaptans such as hexanediol dithiopropionate, trimethylolpropane ginseng- (β-thiopropionate), neopentaerythritol and thiopropionate, and the like. Among these, monofunctional alkyl mercaptans such as n-octyl mercaptan and n-dodecyl mercaptan are preferred. These chain transfer agents may be used individually by 1 type, or may be used in combination of 2 or more type.

The use amount of the chain transfer agent is preferably 0.1 to 1 part by mass, more preferably 0.15 to 0.8 part by mass, still more preferably 0.2 to 0.6 part by mass, and most preferably 0.2 part by mass relative to 100 parts by mass of the monomer used for the polymerization reaction. ~ 0.5 parts by mass. In addition, the use amount of the chain transfer agent is preferably 2500 to 10,000 parts by mass, more preferably 3000 to 9,000 parts by mass, and more preferably 3500 to 6000 parts by mass relative to 100 parts by mass of the polymerization initiator. If the amount of the chain transfer agent used is within the above range, the molecular weight of the copolymer obtained can be controlled, so that the obtained copolymer can have good formability and high mechanical strength.

When the radical polymerization method is selected for producing the copolymer of the present invention, if a solvent is used, there is no limitation as long as it is a monomer and a copolymer that can be dissolved, but it is preferably an aromatic hydrocarbon such as benzene, toluene, ethylbenzene, and the like. These solvents may be used singly or in combination of two or more kinds. The amount of the solvent used should be appropriately set from the viewpoint of the viscosity and productivity of the reaction solution. For example, the amount of the solvent used is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, relative to 100 parts by mass of the polymerization reaction raw material.

When the radical polymerization method is selected for producing the copolymer of the present invention, the temperature during the polymerization reaction is preferably 100 to 200 ° C, and more preferably 110 to 180 ° C. If the polymerization temperature is 100 ° C or higher, the productivity tends to be improved due to an increase in the polymerization speed and a decrease in the viscosity of the polymerization solution. In addition, if the polymerization temperature is 200 ° C or lower, it is easy to control the polymerization rate and further suppress the formation of by-products, so the coloring of the copolymer of the present invention can be suppressed. The polymerization reaction time is preferably 0.5 to 4 hours, more preferably 1.5 to 3.5 hours, and even more preferably 1.5 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 temperature during the polymerization reaction and the polymerization reaction time are within the above ranges, a copolymer having excellent transparency can be efficiently produced.

Although a batch type reaction apparatus may be used for the radical polymerization, a continuous flow type reaction apparatus is preferably used from the viewpoint of productivity. Continuous flow type reaction, for example, is used to prepare raw materials for polymerization in a nitrogen environment (including monomers (refer to the monomer represented by formula (1), methyl methacrylate, and a radical polymerizable monomer (2) added as required)) (Mixture of polymerization initiator, chain transfer agent, etc.), and then supply it to the reactor at a fixed flow rate, and withdraw the liquid in the reactor at a flow rate corresponding to the supplied amount. As the reactor, a tubular reactor that can be brought into an approximately plug flow state and / or a tank reactor that can be brought into an almost completely mixed state can be used. In addition, continuous flow polymerization may be performed by one reactor, or continuous flow polymerization may be performed by connecting two or more reactors.

In the present invention, it is preferable to have at least one tank reactor of a continuous flow type. During the polymerization reaction, the amount of liquid in the tank type reactor is preferably 1/4 to 3/4, and more preferably 1/3 to 2/3, relative to the volume of the tank type reactor. The reactor is usually equipped with a stirring device. Examples of the stirring device include a static stirring device and a dynamic stirring device. Examples of the dynamic stirring device include a MAXBLEND type stirring device, a stirring device having a grid-shaped blade arranged in the center and rotating around a vertical rotation axis, a propeller type stirring device, and a spiral type stirring device. Among these, from the standpoint of uniform mixing, a MAXBLEND type stirring device is preferably used.

When a free-radical polymerization method is selected for manufacturing the copolymer of the present invention, if a batch-type reaction device is used for suspension polymerization, the polymerization conversion rate is preferably 50 to 100% by mass, and more preferably 70 to 99% by mass.

In addition, if a continuous-flow tank reactor is used, the polymerization conversion rate is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 35 to 65% by mass. With a polymerization conversion rate of 20% by mass or more, the remaining unreacted monomer can be easily removed, and the appearance of a molded article composed of a copolymer tends to be better. If the polymerization conversion rate is 80% by mass or less, the viscosity of the polymerization solution tends to decrease and the productivity tends to be improved.

In the methacrylic acid copolymer of the present invention, the ratio (mass%) of the structural unit derived from the monomer represented by the formula (1) to the structural unit derived from methyl methacrylate is almost equal to the feed of the monomer that is a raw material. Into the ratio. The ratio of each structural unit can be determined by ¹ H-NMR.

After the polymerization is completed, volatile components such as unreacted monomers may be removed as required. There is no particular limitation on the removal method, but it is better to remove it by heating. Examples of the devolatization method include an equilibrium flash vaporization method and an adiabatic flash vaporization method. As long as the deaeration temperature using the adiabatic flash vaporization method is lower than the thermal decomposition temperature of the methacrylic acid copolymer, it is preferably 200 to 280 ° C, and more preferably 220 to 260 ° C. The time for heating the resin by adiabatic flash vaporization is preferably 0.3 to 5 minutes, more preferably 0.4 to 3 minutes, and more preferably 0.5 to 2 minutes. Devolatization is performed in the above temperature range and heating time, and a copolymer with little coloration is easily obtained. The removed unreacted monomer can be recovered and reused for polymerization. The yellow index of the recovered monomer may become high due to the heat applied during the recovery operation and the like. Therefore, the recovered monomer should be purified by an appropriate method to reduce the yellow index.

When the molded article of the present invention is produced, other copolymers can be mixed with the copolymer of the present invention and molded to the extent that the effects of the present invention are not impaired. Examples of the other polymer include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene-based ionic polymers; polystyrene and benzene Styrene resins such as ethylene-maleic anhydride copolymer, impact-resistant polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin; methyl methacrylate polymer, methyl methacrylate Ester-styrene copolymer; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamides such as nylon 6, nylon 66, and polyamide elastomers; polycarbonate, poly Vinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacetal, polydifluoroethylene, polyurethane, modified polyphenylene ether, polyphenylene sulfide, poly Silicone modified resin; acrylic rubber, acrylic thermoplastic elastomer, polysiloxane; styrene thermoplastic elastomers such as SEPS, SEBS, SIS; olefin rubbers such as IR, EPR, EPDM, etc.

The shaped body of the present invention preferably contains 80% by mass or more of the copolymer of the present invention, and more preferably contains 90% by mass or more. The manufacturing method of the molded object of this invention is not specifically limited. Examples of the method include forming the copolymer of the present invention or a molding material containing the copolymer of the present invention: T-die method (layer method, coextrusion method, etc.), inflation method (coextrusion method, etc.), compression molding method, Melt forming method such as blow molding method, calendering method, vacuum forming method, injection molding method (embedding method, two-color method, pressing method, core-back method, sandwich method, etc.) and solution casting method, etc. . Among these, from the viewpoints of high productivity and cost, a T-die method, an inflation method, or an injection molding method is preferable. The formed article of the present invention is preferably a molten formed article produced by a melt forming method.

The copolymer of the present invention can be formed into pellets or the like in order to improve convenience during storage, transportation, or molding. In addition, in order to obtain the molded body of the present invention, the molding may be performed multiple times. For example, the copolymer of the present invention can be molded to obtain a pellet-shaped molded body, and then the pellet-shaped molded body can be further formed into a molded body having a desired shape. The formed body of the present invention includes pellets.

The copolymer of the present invention can also be added with antioxidants, anti-heat deterioration agents, ultraviolet absorbers, light stabilizers, slip agents, release agents, polymer processing aids, antistatic agents, flame retardants, dyes, Various additives such as light diffusing agents, organic pigments, matting agents, and phosphors. Relative to the copolymer of the present invention, the blending amount of these various additives is preferably 7 mass% or less, more preferably 5 mass% or less, and even more preferably 4 mass% or less.

Various additives may be added to the polymerization reaction liquid when the copolymer is produced, or may be added to the copolymer produced by the polymerization reaction, or may be added when the formed article is produced.

Antioxidants have the effect of preventing the resin from oxidative degradation in the presence of oxygen with its monomers. Examples include phosphorus-based antioxidants, hindered phenol-based antioxidants, and thioether-based antioxidants. These antioxidants may be used individually by 1 type, and may use 2 or more types together. Among them, from the viewpoint of preventing the deterioration of optical characteristics due to coloration, a phosphorus-based antioxidant or a hindered phenol-based antioxidant is preferable, and a phosphorus-based antioxidant and a hindered phenol-based antioxidant are preferably used in combination.

When combined with phosphorus-based antioxidants and hindered phenol-based antioxidants, the amount of phosphorus-based antioxidants used: The amount of hindered phenol-based antioxidants should preferably be 1: 5 ~ 2: 1 by mass ratio, and 1: 2 ~ 1: 1 is better.

The phosphorus-based antioxidant is preferably 2,2-methylenebis (4,6-di-tert-butylphenyl) octylphosphite (manufactured by ADEKA; trade name: ADEKASTAB HP-10), ginseng (2 , 4-Di-tertiary-butylphenyl) phosphite (manufactured by BASF; trade name: IRGAFOS168), 3,9-bis (2,6-di-tertiary-butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (manufactured by ADEKA Corporation; trade name: ADEKASTAB PEP-36) and the like.

The hindered phenolic antioxidant is preferably pentaerythrityl-penta [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF Corporation; trade name IRGANOX1010 ), Octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF Corporation; trade name IRGANOX1076), and the like.

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

The anti-thermal deterioration agent is preferably 2-tertiarybutyl-6- (3'-tertiarybutyl-5'-methyl-hydroxybenzyl) -4-methylphenylacrylate (manufactured by Sumitomo Chemical Co., Ltd .; Trade name Sumilizer GM), 2,4-di-tertiary pentyl-6- (3 ', 5'-di-tertiary pentyl-2'-hydroxy-α-methylbenzyl) phenyl acrylate ( Manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumilizer GS).

Ultraviolet absorbers are compounds that have the ability to absorb ultraviolet rays. It is reported that they have the function of converting light energy into heat energy.

Examples of the ultraviolet absorber include diphenyl ketones, benzotriazoles, and triazine Types, benzoates, salicylates, cyanoacrylates, ethylenediamine benzenes, malonates, formazan and the like. These may be used individually by 1 type, and may use 2 or more types together.

Benzotriazoles have a high effect of suppressing degradation of optical properties such as coloration due to ultraviolet irradiation, and are therefore suitable as ultraviolet absorbers used when the film of the present invention is applied to optical applications. The benzotriazoles are preferably 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF; trade name TINUVIN329), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234), 2,2'-sub Methylbis [6- (2H-benzotriazol-2-yl) -4-tertiary octylphenol] (made by ADEKA Corporation; LA-31), 2- (5-octylthio-2H-benzene Benzotriazol-2-yl) -6-tert-butyl-4-methylphenol and the like.

Again Examples of the ultraviolet absorber include 2,4,6-ginseng (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (Manufactured by ADEKA; LA-F70) and its hydroxyphenyltriazine UV absorber (manufactured by BASF; TINUVIN477 or TINUVIN460), 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine Wait.

In addition, if you want to absorb light with a wavelength of 380 to 400 nm particularly effectively, International Publication No. 2011/089794, International Publication No. 2012/124395, Japanese Patent Application Publication No. 2012-012476, and Japanese Patent Application Publication No. 2013-023461 should be used. Japanese Patent Application Publication No. 2013-112790, Japanese Patent Application Publication No. 2013-194037, Japanese Patent Application Publication No. 2014-62228, Japanese Patent Application Publication No. 2014-88542, Japanese Patent Application Publication No. 2014-88543, etc. A metal complex of a heterocyclic ligand serves as an ultraviolet absorber.

Light stabilizers are known to be compounds that mainly have the function of capturing free radicals generated by oxidation caused by light. Examples of suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

Examples of the lubricant include stearic acid, rosic acid, stearoamide acid, methylene distearylamine, triglyceride of hydroxystearate, paraffin, ketone wax, octanol , Hardened oil, etc.

Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; and glycerin higher fatty acid esters such as monoglyceryl stearate and diglyceryl stearate. In the present invention, the release agent is preferably a combination of a higher alcohol and a glycerol fatty acid monoester. When using higher alcohols and glycerol fatty acid monoesters, the ratio is not particularly limited, but the amount of higher alcohols used: the amount of glycerin fatty acid monoesters should preferably be 2.5: 1 to 3.5: 1 in mass ratio, and 2.8: 1 ~ 3.2: 1 is preferred.

As the polymer processing aid, polymer particles that can be produced by an emulsion polymerization method and have a particle diameter of 0.05 to 0.5 μm can be generally used. The polymer particles may be single-layer particles composed of a polymer having a single composition ratio and a single limiting viscosity, or multilayer particles composed of two or more polymers having different composition ratios or different limiting viscosities. Among them, a two-layer structure particle is ideally exemplified. The two-layer structure particle has a polymer layer with a low limiting viscosity in the inner layer and a polymer layer with a high limiting viscosity of 5 dl / g or more in the outer layer. The limiting viscosity of polymer processing aid should be 3 ~ 6dl / g. If the limiting viscosity is too small, the effect of improving formability tends to be low. If the limiting viscosity is too large, the molding processability of the copolymer tends to decrease.

Examples of the antistatic agent include sodium heptylsulfonate, sodium octylsulfonate, sodium nonylsulfonate, sodium decylsulfonate, sodium dodecylsulfonate, sodium cetylsulfonate, and octadecylsulfonic acid. Sodium, sodium diheptylsulfonate, potassium heptylsulfonate, potassium octylsulfonate, potassium nonylsulfonate, potassium decylsulfonate, potassium dodecylsulfonate, potassium cetylsulfonate, eighteen Potassium alkylsulfonate, potassium diheptylsulfonate, lithium heptylsulfonate, lithium octylsulfonate, lithium nonylsulfonate, lithium decylsulfonate, lithium dodecylsulfonate, cetylsulfonic acid Alkyl sulfonates such as lithium, lithium octadecylsulfonate, and lithium diheptylsulfonate.

Examples of the flame retardant include metal hydrates having a hydroxyl group or crystal water such as magnesium hydroxide, aluminum hydroxide, aluminum silicate hydrate, magnesium silicate hydrate, and hydrotalcite, phosphate compounds such as polyphosphate amine and phosphate, and polysiloxanes. And the like, and trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tricyclohexyl phosphate, triphenyl phosphate, tricresyl phosphate, Phosphate-based flame retardants such as tris (xyl) phosphate, dimethyl ethyl phosphate, methyl dibutyl phosphate, ethyl dipropyl phosphate, and hydroxyphenyl diphenyl phosphate are preferred.

Dyeing pigments include: red organic pigments such as para red, flaming red, pyrazosin red, thioindigo, osmium red, blue organic pigments such as cyan, indanthrene blue, and green organic pigments such as cyan, naphthol green ; And one or more of these can be used.

The organic pigment is preferably a compound capable of converting ultraviolet rays into visible rays.

Examples of the phosphor include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent whitening agents, and fluorescent bleaches.

Examples of the light diffusing agent or matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, and barium sulfate. The copolymers of the present invention are preferably free of acid generators.

The molding system of this invention contains the copolymer of this invention. The formed body of the present invention is not particularly limited in terms of its production method. The formed body of the present invention can be produced, for example, by forming the copolymer of the present invention in the following methods: T-die method (layer method, coextrusion method, etc.), inflation method (coextrusion method, etc.), compression molding method, Melt forming methods such as blow molding method, calendering method, vacuum forming method, injection molding method (embedding method, two-color method, pressing method, core drawing method, sandwich method, etc.), and cell-casting polymerization method Iso-reaction forming. Among these forming methods, from the viewpoints of high productivity and cost, a T-die method, an inflation method, an injection molding method, and a mold casting polymerization method are preferred.

In addition, in order to obtain the molded body of the present invention, the molding may be performed multiple times. For example, the methacrylic resin composition of the present invention can be molded to obtain a pellet-shaped molded body, and then the pellet-shaped molded body can be further formed into a molded body having a desired shape.

The sheet or film which is one form of the formed body of the present invention is preferably an extrusion molding method or a mold casting polymerization method. The thickness of the obtained sheet is 0.5 mm or more, for example, preferably 0.5 to 20 mm. In addition, the thickness of the prepared film is preferably 1 μm to 500 μm, more preferably 10 μm to 300 μm, and even more preferably 15 to 50 μm.

The use of the formed body of the present invention can include kanban members such as billboards, upright kanbans, side-hanging kanbans, beam kanbans, roof kanbans, etc .; display cabinets, decorative boards, store display and other display parts; fluorescent lamp covers, situations Lighting cover, lamp cover, luminous ceiling, light wall, chandelier and other lighting parts; interior decoration parts such as chandelier, mirror, door, vault, safety window glass, compartment, step waist wall panel, balcony waist wall panel, leisure Construction parts such as roofs of buildings; aircraft windshields, pilot goggles, locomotives, motorboat windshields, bus visors, automobile side sun visors, rear sun visors, head wing, head Parts of transport organs such as lampshades; instruction boards for audio and video, stereo enclosures, TV covers, vending machine display enclosures and other electronic machine parts; heat preservation boxes, X-ray parts and other medical machine parts; mechanical cases, instrument panel covers, experimental devices , Measuring scales, keyboards, observation windows and other machine-related parts; LCD protection boards, light guide plates, light guide films, Fresnel lenses, lenticular lenses, various displays Optical related parts such as front panels, diffusers, etc .; traffic related parts such as road signs, direction boards, curved mirrors, sound insulation walls; film materials such as surface materials for car interiors, mobile phone surface materials, and marking films; top cover materials for washing machines or Control panel, top panel of rice cooker and other components for household appliances; other such as greenhouses, large sinks, box sinks, clock panels, bathtubs, bathrooms, table mats, game machine parts, toys, face protection covers during welding, etc. . Examples

Hereinafter, the present invention will be described more specifically using examples and comparative examples, but the present invention is not limited to the following examples. The measurement of physical properties and the like was performed by the following method.

(Measure the chromatogram by GPC and determine the molecular weight distribution obtained from the chromatogram, etc.) 4 mg of the resin material of the test object is dissolved in 5 ml of tetrahydrofuran, and then filtered through a 0.1 μm filter to prepare a test solution. 20 μl of the test object solution was injected into a GPC device (HLC-8320 manufactured by Tosoh Corporation), and a chromatogram was measured. The GPC device was equipped with a column formed by connecting two TSKgel SuperMultiporeHZM-M manufactured by Tosoh Corporation and SuperHZ4000 in series. And the detection section is a differential refractive index detector. Tetrahydrofuran as the eluent was poured at a flow rate of 0.35 ml / min, and the column temperature was set to 40 ° C.

The test line is made with 10 points of standard polystyrene. Gel permeation chromatography was used to measure standard polystyrene with a molecular weight in the range of 400 to 5,000,000, and a detection line showing the relationship between retention time and molecular weight was made. In the chromatogram, the line connecting the point where the slope of the high molecular weight side turns from zero to a positive value and the point where the slope of the low molecular weight side turns from a negative value to zero is used as a baseline. When there are multiple peaks in the chromatogram, the line connecting the point where the slope of the highest molecular weight side turns from zero to a positive value and the point where the slope of the lowest molecular weight side turns from a negative value to zero is used as the baseline.

The weight average molecular weight Mw and the number average molecular weight Mn in terms of polystyrene were calculated from the chromatogram using a known calculation method, and the molecular weight distribution (Mw / Mn) was further calculated.

( ¹ H-NMR measurement) The structure confirmation of the compound synthesized in the production example and the copolymerization composition in the copolymers of the examples and comparative examples were performed by ¹ H-NMR. ^{The 1} H-NMR mass spectrometer uses a nuclear magnetic resonance apparatus (ULTRA SHIELD 400 PLUS manufactured by Bruker), and 10 mg of the sample is measured using 1 mL of deuterated chloroform as a solvent at room temperature and 64 times of accumulation.

(Thermal decomposition temperature) Under a nitrogen environment, thermal mass analysis (TG) of the copolymer was performed at a heating rate of 10 ° C / min in accordance with JIS K7120. Taking the weight at 250 ° C as the origin, the temperature at which the weight was reduced by 2.5% was taken as the thermal decomposition temperature. The measuring device was TGA-50 (model) manufactured by Shimadzu Corporation.

(Heating retention test) The copolymer was heated at 260 ° C. for 1 hour using a melt index meter (L-220 manufactured by Tateyama Scientific Industries). GPC measurement was performed on the samples before and after heating, and Mw / Mn was calculated, and the change rate (Mw / Mn change rate in a heating test) was calculated.

(Drug Resistance Test (Methanol Resistance)) The copolymer was hot-pressed to obtain a test piece of 80 mm × 10 mm × thickness 1.0 mm. The test piece was allowed to stand for 16 hours or more under the conditions of 23 ° C and 50% RH, and the humidity was adjusted. Using a micro syringe, 10 mL of a solvent (methanol) was dropped on the test piece, and the appearance was observed with the naked eye. A: No change. B: Remaining traces of droplets. C: Cloudiness. D: Swelling and dissolution.

The following were prepared as monomers used in Examples and Comparative Examples.

・ Methyl methacrylate (hereinafter referred to as "MMA") ・ methyl acrylate (hereinafter referred to as "MA") ・ (3-hydroxy-2,2-dimethyl) propyl methacrylate (refer to formula (2) ), The following is expressed as "NPGMA")-(3-hydroxy-2-cyclohexyl) propyl methacrylate (refer to formula (3), the following is expressed as "CHDMA")-methacrylic acid (3-hydroxy-2, 2-diethyl) propyl ester (refer to formula (4), hereinafter referred to as "PRDMA") ・ (3-hydroxy-2-butyl-2-ethyl) propyl methacrylate (refer to formula (5), The following is referred to as "BEPMA")-(2-Hydroxyethyl) methacrylate (hereinafter referred to as "HEMA") The NPGMA is produced using the product obtained in Production Example 1 described later, and the PRDMA is produced in the Production Example 2 described later. For the obtained product, the BEPMA uses the product obtained in Production Example 3 described later, and the CHDMA uses the product obtained in Production Example 4 described later.

[Chemical Formula 3]

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

<Manufacturing Example 1> Synthesis of (3-hydroxy-2,2-dimethyl) propyl methacrylate (NPGMA) In a four-necked flask equipped with a thermometer, a stirrer, and a dropping funnel, 644 parts by mass of toluene and 313 parts by mass were fed. 2,2-dimethyl-1,3-propanediol, 12 parts by mass of sodium methoxide (28% methanol solution), and 0.75 parts by mass of hydroquinone were stirred. The temperature was raised to 60 ° C, and 180 parts by mass of methyl methacrylate was dropped from the dropping funnel over 1 hour. Then, the pressure was reduced to 600 Torr, and methanol as a by-product was distilled off and reacted for 4 hours. After completion of the reaction, it was washed twice with 750 parts by mass of ion-exchanged water. After concentration by distillation under reduced pressure, purification was performed with a column chromatography to obtain 113 parts by mass of (3-hydroxy-2,2-dimethyl) propyl methacrylate (NPGMA, refer to formula (2)).

<Manufacturing Example 2> Synthesis of (3-hydroxy-2-cyclohexyl) propyl methacrylate (CHDMA) Instead of using 2-cyclohexyl-1,3-propanediol instead of 2,2-dimethyl-1,3- 98 parts by mass of (3-hydroxy-2-cyclohexyl) propyl methacrylate (CHDMA, see formula (3)) was obtained in the same manner as in Production Example 1 except that propylene glycol was reacted at 70 ° C.

〈Production Example 3〉 Synthesis of (3-hydroxy-2,2-diethyl) propyl methacrylate (PRDMA) except that 2,2-diethyl-1,3-propanediol was used instead of 2,2-dimethyl. 105 parts by mass of (3-hydroxy-2,2-diethyl) propyl methacrylate (PRDMA, see formula (4)) was obtained in the same manner as in Production Example 1 except for the alkyl-1,3-propanediol.

<Manufacturing Example 4> Synthesis of (3-hydroxy-2-butyl-2-ethyl) propyl methacrylate (BEPMA) Instead of using 2-butyl-2-ethyl-1,3-propanediol instead of 2, Except for 2-dimethyl-1,3-propanediol, 110 parts by mass of (3-hydroxy-2-butyl-2-ethyl) propyl methacrylate (BEPMA) was obtained in the same manner as in Production Example 1. (Eq. (5)). It was confirmed by ¹ H-NMR that methacrylates of the formulae (2) to (5) were obtained.

<Example 1> Nitrogen was substituted in a pressure-resistant container with a stirring device that had been sufficiently dried. 7.9 parts by mass of MMA, 2.0 parts by mass of NPGMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan were fed into this pressure-resistant container.

After the pressure-resistant container was sufficiently replaced with nitrogen, the temperature was raised to 140 ° C while stirring. Then, 0.00015 parts by mass of di-tertiary butyl peroxide (PERBUTYL D made by Japan Oils and Fats) was added to the pressure-resistant container to initiate polymerization. After the polymerization was initiated, it was cooled to room temperature after 4 hours to stop the polymerization. After adding 50 parts by mass of toluene to the obtained solution and diluting, 4,000 parts by mass of methanol was injected to precipitate a solid. The precipitated solid was separated by filtration and sufficiently dried to obtain 7.4 parts by mass of the copolymer (A1). The ¹ H-NMR of the copolymer (A1) was measured. As a result, the content of the structural unit derived from MMA was 81.6% by mass, the content of the structural unit derived from NPGMA was 17.7% by mass, and the content of the structural unit derived from MA was 0.8% by mass. The weight average molecular weight (Mw) of the copolymer (A1) was 209,000, and the molecular weight distribution (Mw / Mn) was 2.09. The results of other evaluations are listed in Table 1.

<Example 2> A copolymer was obtained in the same manner as in Example 1 except that 7.9 parts by mass of MMA, 2.0 parts by mass of CHDMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan were fed into this pressure-resistant container. A2) 7.2 parts by mass. The ¹ H-NMR of the copolymer (A2) was measured, and as a result, the content of the structural unit derived from MMA was 83.3% by mass, the content of the structural unit derived from CHDMA was 16.1% by mass, and the content of the structural unit derived from MA was 0.7% by mass. The weight average molecular weight (Mw) of the copolymer (A2) was 165,000, and the molecular weight distribution (Mw / Mn) was 1.99. The results of other evaluations are listed in Table 1.

<Example 3> A copolymer was obtained in the same manner as in Example 1 except that 5.9 parts by mass of MMA, 4.1 parts by mass of CHDMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan were fed into this pressure-resistant container. A3) 7.4 parts by mass. The ¹ H-NMR of the copolymer (A3) was measured, and as a result, the content of the structural unit derived from MMA was 65.3% by mass, the content of the structural unit derived from CHDMA was 35.5% by mass, and the content of the structural unit derived from MA was 0.8% by mass. The weight average molecular weight (Mw) of the copolymer (A3) was 158,000, and the molecular weight distribution (Mw / Mn) was 2.08. The results of other evaluations are listed in Table 1.

<Example 4> After feeding 7.9 parts by mass of MMA, 2.0 parts by mass of PRDMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan into this pressure-resistant container, the polymerization was started after cooling for 2 hours. In the same manner as in Example 1, 7.4 parts by mass of a copolymer (A4) was obtained. The ¹ H-NMR of the copolymer (A4) was measured. As a result, the content of the structural unit derived from MMA was 83.3% by mass, the content of the structural unit derived from PRDMA was 16.0% by mass, and the content of the structural unit derived from MA was 0.7% by mass. The weight average molecular weight (Mw) of the copolymer (A4) was 186,000, and the molecular weight distribution (Mw / Mn) was 1.68. The results of other evaluations are listed in Table 1.

<Example 5> After charging 7.9 parts by mass of MMA, 2.0 parts by mass of BEPMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan into this pressure-resistant container, the polymerization was started after cooling for 2 hours. In the same manner as in Example 1, 7.2 parts by mass of a copolymer (A5) was obtained. The ¹ H-NMR of the copolymer (A5) was measured. As a result, the content of the structural unit derived from MMA was 83.7% by mass, the content of the structural unit derived from BEPMA was 15.5% by mass, and the content of the structural unit derived from MA was 0.8% by mass. The weight average molecular weight (Mw) of the copolymer (A5) was 187,000, and the molecular weight distribution (Mw / Mn) was 1.73. The results of other evaluations are listed in Table 1.

<Comparative Example 1> A copolymer was obtained in the same manner as in Example 1 except that 7.9 parts by mass of MMA, 2.0 parts by mass of HEMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan were fed to this pressure-resistant container. B1). Most of it sinks to the bottom of the container and does not dissolve (gelate). Therefore, only the soluble component is recovered to perform physical property evaluation. The evaluation results are shown in Table 1.

<Comparative Example 2> A copolymer was obtained in the same manner as in Example 1 except that 5.9 parts by mass of MMA, 4.1 parts by mass of HEMA, 0.1 parts by mass of MA, and 0.012 parts by mass of n-octyl mercaptan were fed into this pressure-resistant container. B2). Most of it sinks to the bottom of the container and does not dissolve (gelate). Therefore, only the soluble component is recovered to perform physical property evaluation. The evaluation results are shown in Table 1.

[Table 1]

As can be seen from Table 1, the copolymers (A1) to (A5) containing a structural unit derived from the monomer represented by the formula (1) did not cause gelation during polymerization. In addition, since the thermal decomposition temperature is high, it is found that the thermal decomposition resistance is excellent. In addition, the rate of change of Mw / Mn before and after the heating test was small, and it was found that the generation of gels during melt molding has been suppressed. In addition, it is known that the drug resistance is good.

Claims (10)

A methacrylic acid copolymer comprising 5 to 50% by mass of a structural unit derived from a monomer represented by the following formula (1) and 50 to 95% by mass of a structural unit derived from methyl methacrylate; [Chemical Formula 1 ] (In formula (1), R ¹ represents a hydrogen atom or a methyl group; R ² and R ³ are each independently a linear, branched or cyclic monovalent hydrocarbon group having 1 to 15 carbon atoms, or R ² and R ³ They may also be bonded to each other to form an aliphatic hydrocarbon ring with the carbon atoms to which they are bonded). The methacrylic acid copolymer according to claim 1, wherein the sum of the carbon number of R ^{2 and} the carbon number of R ³ in the monomer represented by the aforementioned formula (1) is 2-9. For example, the methacrylic acid copolymer of claim 1 or 2 has a weight average molecular weight of 40,000 to 300,000. For example, the methacrylic acid copolymer according to any one of claims 1 to 3 has a weight average molecular weight / number average molecular weight ratio of 1.01 to 3.0. For example, the methacrylic acid copolymer according to any one of claims 1 to 4, the ratio of the weight average molecular weight Mw to the number average molecular weight Mn, Mw / Mn, is the value before the heat treatment at 260 ° C for 1 hour. The value is 1.4 times or less. The weight average molecular weight Mw and the number average molecular weight Mn are calculated based on a chromatogram obtained by gel permeation chromatography and converted into polystyrene. The methacrylic acid copolymer according to any one of claims 1 to 5, wherein the Mw / Mn after the heat treatment at 260 ° C for 1 hour is 1.2 times or less the value before the treatment. A molded article containing the copolymer according to any one of claims 1 to 6 in an amount of 80% by mass or more. The formed article as claimed in item 7 is a melt-formed article. If the formed article of claim 7 or 8 is a sheet having a thickness of 0.5 mm or more. If the formed article of claim 7 or 8 is a thin film having a thickness of 1 μm to 500 μm.