JP2015086250A - Methacrylic resin composition and molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a methacrylic resin composition which is excellent in transparency and fire retardancy, is low water absorptive and excellent in dimension stability.SOLUTION: There is provided the methacrylic resin composition containing (A) a methacrylic resin containing 10 to 40 mass% of a structural unit derived from methacrylic acid ester represented by the formula (I) and 60 to 90 mass% of a structural unit derived from a radical polymerizable monomer (II) other than the methacrylic acid ester represented by the formula (I) and having the content of a phosphorus atom in the methacrylic resin composition of 0.8 to 5 mass%. (I), where Rrepresents a polycyclic aliphatic hydrocarbon group, an alkyl substituted monocyclic aliphatic hydrocarbon group, -CHCHRR, -CHR-CHRRor -CRRR, R, Rand Rrepresent each independently an alkyl group having 1 to 3 carbon atoms, Rrepresents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

Description

  The present invention relates to a methacrylic resin composition having excellent transparency and flame retardancy, low water absorption, and excellent dimensional stability, and a molded article comprising the composition.

Methacrylic resins having excellent transparency are used for applications such as optical materials, lighting materials, signboards, and decorative members. In these applications, flame retardancy may be required.
Various methods for increasing the flame retardancy of resins have been proposed. For example, patent document 1 is disclosing the resin composition which mix | blended inorganic compounds, such as basic magnesium carbonate, with resin. However, such a resin composition is usually not suitable for applications requiring high transparency such as optical materials because of its low transparency. Patent Document 2, 3 or 4 discloses a methacrylic resin composition containing a phosphorus compound. In order to sufficiently increase the flame retardancy, it is necessary to increase the amount of phosphorus compound added. A methacrylic resin composition to which a large amount of a phosphorus compound is added has a low glass transition temperature, and therefore is not suitable for use at high temperatures. Patent Document 5 discloses a method of combining a small amount of a phosphorus compound with a methacrylic resin copolymerized with methacrylic acid. However, since the copolymerization of methacrylic acid increases the water absorption rate of the methacrylic resin composition, such a methacrylic resin composition is not suitable for use under high humidity.

JP 61-141759 A JP 59-41349 Japanese Patent Laid-Open No. 9-302191 Japanese Patent Laid-Open No. 9-169882 Japanese Patent Laid-Open No. 9-169882

  An object of the present invention is to provide a methacrylic resin composition having excellent transparency and flame retardancy, low water absorption, and excellent dimensional stability.

  In order to achieve the above object, the present invention provides the following aspects.

[1] 10-40% by mass of a structural unit derived from a methacrylic acid ester represented by the formula (I) and a structural unit derived from a radical polymerizable monomer (II) other than the methacrylic acid ester represented by the formula (I) A methacrylic resin composition containing 60 to 90% by mass of a methacrylic resin (A) and an organophosphorus compound (B),
The methacrylic resin composition whose content of the phosphorus atom in this methacrylic resin composition is 0.8-5 mass%.

（式（I）中、Ｒ¹は多環脂肪族炭化水素基、アルキル置換単環脂肪族炭化水素基、−ＣＨ₂ＣＨＲ²Ｒ³、−ＣＨＲ²−ＣＨＲ³Ｒ⁴、または−ＣＲ²Ｒ³Ｒ⁵を表し、Ｒ²、Ｒ³およびＲ⁵はそれぞれ独立に炭素数１〜３のアルキル基を表し、Ｒ⁴は水素原子、または炭素数１〜３のアルキル基を表す。）

(In the formula (I), R ¹ is a polycyclic aliphatic hydrocarbon group, an alkyl-substituted monocyclic aliphatic hydrocarbon group, —CH ₂ CHR ² R ³ , —CHR ² —CHR ³ R ⁴ , or —CR ² R ³ represents R ⁵ , R ² , R ³ and R ⁵ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

[2] The methacrylic resin according to [1], wherein R ¹ is at least one selected from the group consisting of a t-butyl group, a norbornyl group, an isobornyl group, a tricyclodecanyl group, and a 4-t-butylcyclohexyl group. Composition.
[3] The methacrylic resin composition according to [1] or [2], wherein the radical polymerizable monomer (II) is methyl (meth) acrylate.
[4] The methacrylic resin composition according to [1] or [2], wherein the radical polymerizable monomer (II) is an aromatic vinyl compound.
[5] The methacrylic resin composition according to any one of [1] to [4], wherein the organic phosphorus compound (B) is a phosphate ester or a condensed phosphate ester.
[6] The methacrylic resin composition according to any one of [1] to [5], which has a flame retardancy according to the UL-94 test of V-2 or more and a water absorption of 5% or less.
[7] A molded article comprising the methacrylic resin composition according to any one of [1] to [6].

  The methacrylic resin composition and molded product of the present invention are excellent in transparency and flame retardancy, have low water absorption, and are excellent in dimensional stability. The methacrylic resin composition and molded product of the present invention can be used in fields where high dimensional accuracy is required. In addition, the methacrylic resin composition and the molded body of the present invention have a particularly high amount of carbide (char) generated when burned, and the carbide suppresses heat transfer and diffusion of combustion gas, so that high flame retardancy is achieved. Have.

(Resin composition)
The methacrylic resin composition of the present invention contains a methacrylic resin (A) and an organic phosphorus compound (B).

  The methacrylic resin (A) comprises a structural unit derived from the radical polymerizable monomer (I) and a structural unit derived from the radical polymerizable monomer (II).

  The radical polymerizable monomer (I) is a methacrylic acid ester represented by the formula (I).

In the formula (I), R ¹ is a polycyclic aliphatic hydrocarbon group, an alkyl-substituted monocyclic aliphatic hydrocarbon group, —CH ₂ CHR ² R ³ , —CHR ² —CHR ³ R ⁴ , or —CR ² R ^3. R ⁵ is represented. R ² , R ³ and R ⁵ each independently represents an alkyl group having 1 to 3 carbon atoms. R ⁴ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

Examples of the polycyclic aliphatic hydrocarbon group for R ¹ include a norbornyl group, an isobornyl group, a tricyclodecanyl group, a dicyclopentadienyl group, an adamantyl group, a fenkyl group, and a decalinyl group. Among these, a norbornyl group, an isobornyl group, a tricyclodecanyl group, a dicyclopentadienyl group, and an adamantyl group are preferable, and a norbornyl group, an isobornyl group, and a tricyclodecanyl group are more preferable.

The alkyl-substituted monocyclic aliphatic hydrocarbon group for R ¹ is not particularly limited, but is a monocyclic aliphatic hydrocarbon group substituted with an alkyl group having 1 to 4 carbon atoms such as a methyl group, an isopropyl group, or a t-butyl group. Is preferred. Examples of the alkyl-substituted monocyclic aliphatic hydrocarbon group include 4-methylcyclohexyl group, 2-methylcyclohexyl group, 4-isopropylcyclohexyl group, 2-isopropylcyclohexyl group, 4-t-butylcyclohexyl group, 2-t- And a butylcyclohexyl group. Of these, 4-t-butylcyclohexyl group is preferred.

Examples of —CH ₂ CHR ² R ³ in R ¹ include an isobutyl group, 2-methylbutyl group, 2-ethylbutyl group, 2-isopropylbutyl group, 2-isopropyl-4-methylbutyl group, and 2,3-dimethylbutyl group. 2-methylpentyl group, 2-ethylpentyl group, 2-propylpentyl group, 2-isopropylpentyl group, and the like.

Examples of —CHR ² —CHR ³ R ⁴ in R ¹ include s-butyl group, 1-methylbutyl group, 1-methylpentyl group, 1,3-dimethylbutyl group, 1,2-dimethylpropyl group, 1, 2-dimethylbutyl group, 1,2-dimethylpentyl group, 1,2,3-trimethylbutyl group, 2-ethyl-1-methylbutyl group, 2-ethyl-1-methylpentyl group, 2-ethyl-1,3 -Dimethylbutyl group, 1-methyl-2-propylpentyl group, 2-isopropyl-1-methylpentyl group, 2-isopropyl-1,3-dimethylbutyl group, 1-ethylpropyl group, 1-ethylbutyl group, 1- Ethylpentyl group, 1-ethyl-3-methylbutyl group, 1-ethyl-2-methylpropyl group, 1-ethyl-2-methylbutyl group, 1-ethyl-2-methylpentyl group 1-ethyl-2,3-dimethylbutyl group, 1,2-diethylbutyl group, 1,2-diethylpentyl group, 1,2-diethyl-3-methylbutyl group, 1-ethyl-2-propylpentyl group, 2-isopropyl-1-ethylpentyl group, 1-ethyl-2-isopropyl-3-methylbutyl group, 1-propylbutyl group, 1-propylpentyl group, 3-methyl-1-propylbutyl group, 1-isopropylbutyl group 2-methyl-1-propylbutyl group, 2-methyl-1-propylpentyl group, 2,3-dimethyl-1-propylbutyl group, 2-ethyl-1-propylbutyl group, 2-ethyl-1-propyl Pentyl group, 2-ethyl-3-methyl-1-propylbutyl group, 1,2-dipropylpentyl group, 2-isopropyl-1-propylpentyl group, 2- Sopropyl-3-methyl-1-propylbutyl group, 1-isopropylpentyl group, 1-isopropyl-3-methylbutyl group, 1-isopropyl-2-methylpropyl group, 1-isopropyl-2-methylbutyl group, 1-isopropyl- 2-methylpentyl group, 1-isopropyl-2,3-dimethylbutyl group, 2-ethyl-1-isopropylbutyl group, 2-ethyl-1-isopropylpentyl group, 2-diethyl-1-isopropyl-3-methylbutyl group 1-isopropyl-2-propylpentyl group, 1,2-diisopropylpentyl group, 1,2-isopropyl-3-methylbutyl group, and the like.

Examples of —CR ² R ³ R ⁵ in R ¹ include a t-butyl group, 1,1-dimethylpropyl group, 1-ethyl-1-methylpropyl group, 1,1-diethylpropyl group, 1,1- Dimethylbutyl group, 1-ethyl-1-methylbutyl group, 1,1-diethylbutyl group, 1-methyl-1-propylbutyl group, 1-ethyl-1-propylbutyl group, 1,1-dipropylbutyl group, 1,1,2-trimethylpropyl group, 1-ethyl-1,2-dimethylpropyl group, 1,1-diethyl-2-methylpropyl group, 1-isopropyl-1-methylbutyl group, 1-ethyl-1-isopropyl Butyl group, 1-isopropyl-1-propylbutyl group, 1-isopropyl-1,2-dimethylpropyl group, 1,1-diisopropylpropyl group, 1,1-diisopropylbutyl Group, 1,1-diisopropyl-2-methylpropyl group and the like.

  Specific examples of the radical polymerizable monomer (I) include isobutyl methacrylate, 2-methylbutyl methacrylate, 2-ethylbutyl methacrylate, 2-isopropylbutyl methacrylate, 2-isopropyl-4-methylbutyl methacrylate, methacrylic acid. 2,3-dimethylbutyl, 2-methylpentyl methacrylate, 2-ethylpentyl methacrylate, 2-propylpentyl methacrylate, 2-isopropylpentyl methacrylate;

  S-butyl methacrylate, 1-methylbutyl methacrylate, 1-methylpentyl methacrylate, 1,3-dimethylbutyl methacrylate, 1,2-dimethylpropyl methacrylate, 1,2-dimethylbutyl methacrylate, 1, methacrylate 2-dimethylpentyl, 1,2,3-trimethylbutyl methacrylate, 2-ethyl-1-methylbutyl methacrylate, 2-ethyl-1-methylpentyl methacrylate, 2-ethyl-1,3-dimethylbutyl methacrylate, 1-methyl-2-propylpentyl methacrylate, 2-isopropyl-1-methylpentyl methacrylate, 2-isopropyl-1,3-dimethylbutyl methacrylate, 1-ethylpropyl methacrylate, 1-ethylbutyl methacrylate, methacrylic acid 1-ethylpentyl, methacrylic acid -Ethyl-3-methylbutyl, 1-ethyl-2-methylpropyl methacrylate, 1-ethyl-2-methylbutyl methacrylate, 1-ethyl-2-methylpentyl methacrylate, 1-ethyl-2,3-dimethyl methacrylate Butyl, 1,2-diethylbutyl methacrylate, 1,2-diethylpentyl methacrylate, 1,2-diethyl-3-methylbutyl methacrylate, 1-ethyl-2-propylpentyl methacrylate, 2-isopropyl-1 methacrylate -Ethylpentyl, 1-ethyl-2-isopropyl-3-methylbutyl methacrylate, 1-propylbutyl methacrylate,

  1-propylpentyl methacrylate, 3-methyl-1-propylbutyl methacrylate, 1-isopropylbutyl methacrylate, 2-methyl-1-propylbutyl methacrylate, 2-methyl-1-propylpentyl methacrylate, methacrylic acid 2 , 3-dimethyl-1-propylbutyl, 2-ethyl-1-propylbutyl methacrylate, 2-ethyl-1-propylpentyl methacrylate, 2-ethyl-3-methyl-1-propylbutyl methacrylate, methacrylic acid 1 , 2-dipropylpentyl, 2-isopropyl-1-propylpentyl methacrylate, 2-isopropyl-3-methyl-1-propylbutyl methacrylate, 1-isopropylpentyl methacrylate, 1-isopropyl-3-methylbutyl methacrylate, 1-Isopropyl methacrylate 2-methylpropyl, 1-isopropyl-2-methylbutyl methacrylate, 1-isopropyl-2-methylpentyl methacrylate, 1-isopropyl-2,3-dimethylbutyl methacrylate, 2-ethyl-1-isopropylbutyl methacrylate 2-ethyl-1-isopropylpentyl methacrylate, 2-diethyl-1-isopropyl-3-methylbutyl methacrylate, 1-isopropyl-2-propylpentyl methacrylate, 1,2-diisopropylpentyl methacrylate, 1, methacrylate 2-isopropyl-3-methylbutyl;

  T-butyl methacrylate, 1,1-dimethylpropyl methacrylate, 1-ethyl-1-methylpropyl methacrylate, 1,1-diethylpropyl methacrylate, 1,1-dimethylbutyl methacrylate, 1-ethyl methacrylate 1-methylbutyl, 1,1-diethylbutyl methacrylate, 1-methyl-1-propylbutyl methacrylate, 1-ethyl-1-propylbutyl methacrylate, 1,1-dipropylbutyl methacrylate, 1,1 methacrylate , 2-trimethylpropyl, 1-ethyl-1,2-dimethylpropyl methacrylate, 1,1-diethyl-2-methylpropyl methacrylate, 1-isopropyl-1-methylbutyl methacrylate, 1-ethyl-1-methacrylate Isopropylbutyl, 1-isopropyl-1-propyl methacrylate Chill, methacrylic acid 1-isopropyl-1,2-dimethylpropyl, methacrylic acid, 1,1-diisopropyl-propyl, 1,1-diisopropyl-butyl methacrylate, 1,1-diisopropyl-2-methylpropyl methacrylate;

  4-methylcyclohexyl methacrylate, 2-methylcyclohexyl methacrylate, 4-isopropylcyclohexyl methacrylate, 2-isopropylcyclohexyl methacrylate, 4-t-butylcyclohexyl methacrylate, 2-t-butylcyclohexyl methacrylate;

2-norbornyl methacrylate, 2-methyl-2-norbornyl methacrylate, 2-ethyl-2-norbornyl methacrylate, 2-isobornyl methacrylate, 2-methyl-2-isobornyl methacrylate, 2-ethyl-2-methacrylate Isobornyl, 8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 8-methyl-8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate, 8-ethyl methacrylate 8-tricyclo [5.2.1.0 ^2,6 ] decanyl, 2-adamantyl methacrylate, 2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate, 1-adamantyl methacrylate, methacryl Acid 2-fenkyl, 2-methyl-2-fenkyl methacrylate, 2-ethyl-2-methacrylate Nkiru, decalin methacrylic acid-1-yl, and the like methacrylic acid decalin-2-yl.

Of these, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, 2-norbornyl methacrylate, 2-isobornyl methacrylate, 8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate , 8-tricyclo [5.2.1.0 ^2,6 ] deca-3,8-dienyl methacrylate, 2-adamantyl methacrylate, 1-adamantyl methacrylate, and 4-t-butylcyclohexyl methacrylate are preferred and heat resistant. From the standpoints of properties and availability, t-butyl methacrylate, 2-isobornyl methacrylate, 8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate or 4-t-butylcyclohexyl methacrylate are more preferred. preferable.

  As the radically polymerizable monomer (I), one type may be used alone or two or more types may be used in combination in order to achieve both high water absorption and heat resistance.

  The amount of the structural unit derived from the radical polymerizable monomer (I) contained in the methacrylic resin (A) varies depending on the structure of the radical polymerizable monomer (I) used, but the methacrylic resin (A) It is preferable that it is 10-40 mass% with respect to all the structural units contained in, and it is more preferable that it is 15-35 mass%. In addition, when using in combination of 2 or more types of radically polymerizable monomers (I), content of the structural unit derived from the above-mentioned radically polymerizable monomer (I) is such 2 or more types of radically polymerizable properties. It means the total content of monomer (I).

When the structural unit derived from the radical polymerizable monomer (I) is heated, the R ¹ side chain is detached and converted into a methacrylic acid structural unit. The organophosphorus compound (B) acts on this methacrylic acid structural unit, and the amount of carbide (char) produced increases due to the synergistic effect. Carbide (char) has the effect of increasing the flame retardancy of the resin composition. On the other hand, since the detached side chain is easily combusted, it has the effect of reducing the flame retardancy of the resin composition. Therefore, when the amount of the structural unit derived from the radical polymerizable monomer (I) contained in the methacrylic resin (A) is less than 10% or more than 40%, the flame retardancy is lowered. Tend to.

  The radical polymerizable monomer (II) is a radical polymerizable monomer other than the methacrylic acid ester represented by the formula (I).

  Examples of the radical polymerizable monomer (II) include vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, p-methylstyrene, and m-methylstyrene; vinylcyclohexane, vinylcyclopentane, vinylcyclohexene, and vinylcyclohexane. Vinyl alicyclic hydrocarbons such as heptane, vinylcycloheptene, vinyl norbornene; ethylenically unsaturated carboxylic acids such as maleic anhydride, maleic acid, itaconic acid; ethylene, propylene, 1-butene, isobutylene, 1-octene, etc. Conjugated dienes such as butadiene, isoprene and myrcene; acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl ketone, vinyl chloride, vinylidene chloride, vinylidene fluoride;

  Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, s-butyl acrylate, t-butyl acrylate, amyl acrylate, isoamyl acrylate, acrylic acid alkyl acrylates such as n-hexyl, 2-ethylhexyl acrylate, pentadecyl acrylate, dodecyl acrylate; 2-hydroxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, allyl acrylate;

  Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, pentadecyl methacrylate, dodecyl methacrylate Methacrylic acid alkyl esters other than radical polymerizable monomers (I) such as: 2-hydroxyethyl methacrylate, 2-ethoxyethyl methacrylate, glycidyl methacrylate, allyl methacrylate; cyclohexyl (meth) acrylate, (meth) (Meth) acrylic acid unsubstituted monocyclic aliphatic hydrocarbon esters such as cyclopentyl acrylate and cycloheptyl (meth) acrylate; (meth) acrylic acid aryl esters such as phenyl methacrylate and phenyl acrylate; Benzyl acrylic acid, (meth) (meth) aralkyl acrylates, such as phenoxyethyl acrylate;

  2-vinylfuran, 2-isopropenylfuran, 2-vinylbenzofuran, 2-isopropenylbenzofuran, 2-vinyldibenzofuran, 2-vinylthiophene, 2-isopropenylthiophene, 2-vinyldibenzothiophene, 2-vinylpyrrole, N -Vinylindole, N-vinylcarbazole, 2-vinyloxazole, 2-isopropenyloxazole, 2-vinylbenzoxazole, 3-vinylisoxazole, 3-isopropenylisoxazole, 2-vinylthiazole, 2-vinylimidazole, 4 (5) -vinylimidazole, N-vinylimidazole, N-vinylimidazoline, 2-vinylbenzimidazole, 5 (6) -vinylbenzimidazole, 5-isopropenylpyrazole, 2-isopropenyl 1, , 4-oxadiazole, vinyltetrazole, 2-vinylpyridine, 4-vinylpyridine, 2-isopropenylpyridine, 3-vinylpyridine, 3-isopropenylpyridine, 2-vinylquinoline, 2-isopropenylquinoline, 4- Vinylquinoline, 4-vinylpyrimidine, 2,4-dimethyl-6-vinyl-S-triazine, 3-methylidenedihydrofuran-2 (3H) -one, 4-methyl-3-methylidenedihydrofuran-2 (3H ) -One, ethylenically unsaturated heterocyclic compounds such as 4-decyl-3-methylidenedihydrofuran-2 (3H) -one, and the like. Of these, vinyl aromatic hydrocarbons, alkyl acrylates and alkyl methacrylates other than the radical polymerizable monomer (I) are preferred, and styrene, methyl acrylate and methyl methacrylate are more preferred. A radically polymerizable monomer (II) may be used individually by 1 type, and may be used in combination of 2 or more type. “(Meth) acryl” means “methacryl or acryl”.

  The amount of structural units derived from the radically polymerizable monomer (II) contained in the methacrylic resin (A) varies depending on the structure of the radically polymerizable monomer (II) used, but the methacrylic resin (A) It is preferable that it is 60-90 mass% with respect to all the structural units contained, and it is more preferable that it is 65-85 mass%. When two or more radically polymerizable monomers (II) are used in combination, the content of the structural unit derived from the radically polymerizable monomer (II) is such two or more radically polymerizable monomers. It means the total content of structural units derived from the body (II).

The amount of the structural unit contained in the methacrylic resin (A) can be quantified by ¹ H-NMR measurement. Further, if quantification becomes difficult due to overlapping peaks in ¹ H-NMR measurement, it can be quantified using pyrolysis gas chromatography measurement.

Specific examples of the methacrylic resin (A) used in the present invention include t-butyl methacrylate / methyl methacrylate copolymer, 2-isobornyl methacrylate / methyl methacrylate copolymer, 8-tricyclomethacrylate [5.2. 1.0 ^2,6 ] decanyl / methyl methacrylate copolymer, 4-t-butylcyclohexyl methacrylate / methyl methacrylate copolymer, t-butyl methacrylate / methyl acrylate copolymer, 2-methacrylic acid 2- Isobornyl / methyl acrylate copolymer, methacrylate 8-tricyclo [5.2.1.0 ^2,6 ] decanyl / methyl acrylate copolymer, 4-t-butylcyclohexyl methacrylate / methyl acrylate copolymer , T-butyl methacrylate / styrene copolymer, 2-isobornyl methacrylate / styrene copolymer, Tacrylic acid 8-tricyclo [5.2.1.0 ^2,6 ] decanyl / styrene copolymer, 4-t-butylcyclohexyl methacrylate / styrene copolymer, t-butyl methacrylate / methyl methacrylate / acrylic acid Methyl copolymer, 2-isobornyl methacrylate / methyl methacrylate / methyl acrylate copolymer, 8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate / methyl methacrylate / methyl acrylate copolymer Copolymer, 4-t-butylcyclohexyl methacrylate / methyl methacrylate / methyl acrylate copolymer, t-butyl methacrylate / methyl methacrylate / styrene copolymer, 2-isobornyl methacrylate / methyl methacrylate copolymer / styrene, methacrylic acid 8-tricyclo [5.2.1.0 ^{2, 6]} decanyl / methacryl Methyl acid / styrene copolymer, 4-t-butylcyclohexyl methacrylate / methyl methacrylate / styrene copolymer, t-butyl methacrylate / methyl acrylate / styrene copolymer, 2-isobornyl methacrylate / methyl acrylate Copolymer / styrene, 8-tricyclo [5.2.1.0 ^2,6 ] decanyl methacrylate / methyl acrylate / styrene copolymer, 4-t-butylcyclohexyl methacrylate / methyl acrylate / styrene copolymer Examples include coalescence.

  The methacrylic resin (A) has a weight average molecular weight of preferably 50,000 to 1,000,000, more preferably 70,000 to 500,000, particularly preferably 80,000 to 300,000. When the weight average molecular weight is within this range, the moldability of the methacrylic resin (A) and the impact resistance and toughness of the molded product obtained from the methacrylic resin (A) are good.

The ratio of the weight average molecular weight / number average molecular weight of the methacrylic resin (A) (hereinafter this ratio is referred to as “molecular weight distribution”) is preferably 1.1 to 10.0, more preferably 1.5. It is -5.0, Most preferably, it is 1.6-3.0. When the molecular weight distribution is within this range, the moldability of the methacrylic resin (A) and the impact resistance and toughness of the molded product obtained from the methacrylic resin (A) are good.
In addition, a weight average molecular weight and molecular weight distribution are the values of standard polystyrene conversion measured by GPC (gel permeation chromatography).
Such weight average molecular weight and molecular weight distribution can be controlled by adjusting the types and amounts of the polymerization initiator and the chain transfer agent.

  The methacrylic resin (A) is obtained by copolymerizing the radical polymerizable monomer (I) and the radical polymerizable monomer (II) in a proportion corresponding to the content of the structural unit. The copolymerization method is not particularly limited, and examples thereof include an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, and a solution polymerization method. Further, it is preferable to employ a reaction molding method such as a cell cast polymerization method because heat applied to the methacrylic resin (A) during molding can be reduced and a molded product having a small yellow index can be obtained. Copolymerization can be initiated at a predetermined temperature in the presence of a polymerization initiator. Moreover, the weight average molecular weight etc. of the methacryl resin (A) obtained can be adjusted using a chain transfer agent as needed.

The radical polymerizable monomer (I) and the radical polymerizable monomer (II) which are raw materials for obtaining the methacrylic resin (A) preferably have a yellow index of 2 or less at an optical path length of 10 mm. The following is more preferable. When this yellow index is small, coloring of the methacrylic resin (A) obtained can be suppressed.
The above yellow index is a yellowness value calculated according to JIS K7373 based on a value measured according to JIS Z8722.

  The polymerization initiator used when producing the methacrylic resin (A) is not particularly limited as long as it generates a reactive radical. For example, t-hexylperoxyisopropyl monocarbonate, t-hexylperoxy 2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, t-butylperoxypivalate T-hexylperoxypivalate, t-butylperoxyneodecanoate, t-hexylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1 , 1-bis (t-hexylperoxy) cyclohexane, benzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, lauroyl peroxide and other organic peroxides; 2,2′-azobis (2-methylpro) Pionitrile), 2,2′-azobis (2-methylbutyronitrile), dimethyl 2 2'-azobis (2-methyl propionate) azo compounds, such as ammonium persulfate, potassium persulfate, and a persulfate such as sodium persulfate. Of these, azo compounds are preferred. These polymerization initiators may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the usage-amount of a polymerization initiator, the addition method, etc. should just be set suitably according to the objective, and are not specifically limited. For example, the amount of the polymerization initiator used is preferably 0.0001 to 0.2 parts by mass and more preferably 0.001 to 0.1 parts by mass with respect to 100 parts by mass of all monomers. In addition, when using it in combination of 2 or more types of polymerization initiators, the usage-amount of above-described polymerization initiator means the total usage-amount of this 2 or more types of polymerization initiator.

  The chain transfer agent used for producing the methacrylic resin (A) is n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, 1,4-butanedithiol, 1,6-hexanedithiol, ethylene glycol bisthiol. Propionate, butanediol bisthioglycolate, butanediol bisthiopropionate, hexanediol bisthioglycolate, hexanediol bisthiopropionate, trimethylolpropane tris- (β-thiopropionate), pentaerythritol Alkyl mercaptans such as tetrakisthiopropionate; α-methylstyrene dimer; terpinolene and the like. Of 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, and may be used in combination of 2 or more type. The amount of the chain transfer agent used is preferably 0.01 to 1 part by weight, more preferably 0.02 to 0.8 part by weight, and 0.03 to 0.6 part by weight with respect to 100 parts by weight of all monomers. Part is more preferred. In addition, when using 2 or more types of chain transfer agents in combination, the usage-amount of the above-mentioned chain transfer agent means the total usage-amount of these 2 or more types of chain transfer agents.

  In the copolymerization of the radically polymerizable monomer (I) and the radically polymerizable monomer (II), all the substances necessary for the production of the methacrylic resin (A) may be mixed and supplied to the reactor. The materials necessary for the production of the methacrylic resin (A) may be separately supplied to the reactor, but it is preferable that all the materials necessary for the production of the methacrylic resin (A) are mixed and supplied to the reactor. Such mixing is preferably performed in an inert gas atmosphere such as nitrogen gas.

  The temperature at the time of copolymerization is preferably in the range of 0 to 200 ° C, more preferably in the range of 20 to 180 ° C. The copolymerization time depends on the reaction scale, but is preferably in the range of 0.1 to 20 hours, more preferably in the range of 0.5 to 10 hours from the viewpoint of high economic efficiency. The copolymerization is preferably performed in an inert gas atmosphere such as nitrogen gas.

  After completion of the copolymerization, unreacted monomers and solvents can be removed according to a known method. Moreover, in order to make a methacryl resin (A) easy to shape | mold, you may granulate and pelletize by a well-known method.

  The organophosphorus compound used in the present invention is known as one that can be blended with a resin and imparted with flame retardancy. In the present invention, as the organic phosphorus compound (B), a phosphate ester or a condensed phosphate ester is preferably used.

  Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl di 2,6-xylenyl phosphate, and the like. Of these, triphenyl phosphate is preferred.

  Examples of the condensed phosphate ester include 1,3-phenylene diphenyl phosphate (for example, CR-733S manufactured by Daihachi Chemical Co., Ltd.) and 1,3-phenylenebis (2,6-dimethylphenyl phosphate) (for example, PX- manufactured by Daihachi Chemical Co., Ltd.). 200), 1,4-phenylenebis (2,6-dimethylphenyl phosphate) (for example, PX-201 manufactured by Daihachi Chemical Co., Ltd.), 1,6-biphenylenebis (2,6-dimethylphenylphosphate) (for example, Daihachi Chemical) PX-202), a reaction product of biphenyl-4,4′-diol / phenol / phosphoryl = trichloride based on 4,4′-bis (diphenylphosphoryl) -1,1′-biphenyl (for example, FP-800 manufactured by ADEKA), 10-benzyl-9,10-dihydro-9-oxa-10-phosphaphenant Such emissions 10- oxide (e.g. Sankosha manufactured BCA) and the like.

  The mass ratio (methacrylic resin (A) / organic phosphorus compound (B)) of the methacrylic resin (A) and the organic phosphorus compound (B) contained in the methacrylic resin composition is preferably 2 or more and 20 or less, more preferably 2. 5 or more and 15 or less, more preferably 3 or more and 10 or less.

  The amount of phosphorus atoms contained in the methacrylic resin composition of the present invention is usually 0.8 to 5% by mass, preferably 0, based on the methacrylic resin (A) from the viewpoint of the balance between heat resistance and flame retardancy. 0.8 to 4% by mass, more preferably 0.9 to 3% by mass, and still more preferably 1 to 3% by mass.

  The total mass of the methacrylic resin (A) and the organic phosphorus compound (B) contained in the methacrylic resin composition is preferably 99% by mass or more, more preferably 99.5% by mass or more, based on the methacrylic resin composition. 99.8 mass% or more is more preferable.

  The methacrylic resin composition of the present invention can be obtained by mixing a methacrylic resin (A) and an organic phosphorus compound (B). Such mixing can be performed by, for example, a melt mixing method, a solution mixing method, or the like. In the melt mixing method, for example, using a melt kneader such as a uniaxial or multiaxial kneader, an open roll, a Banbury mixer, a kneader, and the like, under an inert gas atmosphere such as nitrogen gas, argon gas, helium gas, etc. Melt kneading can be performed to obtain a methacrylic resin composition. In the solution mixing method, a methacrylic resin composition can be obtained by dissolving the methacrylic resin (A) and the organic phosphorus compound (B) in an organic solvent such as toluene, tetrahydrofuran, methyl ethyl ketone, and mixing. The methacrylic resin composition of the present invention can also be obtained by polymerizing a polymerizable composition containing the radical polymerizable monomer (I), the radical polymerizable monomer (II), and the organophosphorus compound (B). Can be obtained. Such polymerization can be carried out in the same manner as the copolymerization for producing the methacrylic resin (A).

  The methacrylic resin composition of the present invention has a glass transition temperature of preferably 70 to 150 ° C, more preferably 80 to 130 ° C. If the glass transition temperature is too low, the heat resistance of the resin is insufficient, and if the glass transition temperature is too high, the resin becomes brittle. The glass transition temperature is a value measured according to JIS K7121. That is, the methacrylic resin composition of the present invention is heated once to 230 ° C., then cooled to room temperature, and then DSC by differential scanning calorimetry under the condition of increasing the temperature from room temperature to 230 ° C. at 10 ° C./min. The curve was measured, and the midpoint glass transition temperature obtained from the DSC curve measured at the second temperature increase was defined as the glass transition temperature of the present invention.

  The methacrylic resin composition of the present invention preferably has a flame retardance index of V-2 or higher in a UL94V test using a test piece having a thickness of 3.0 to 3.2 mm.

The methacrylic resin composition of the present invention has a water absorption rate of preferably 5% or less, more preferably 2% or less. When the water absorption rate is too high, the dimensional stability of the methacrylic resin is deteriorated. The water absorption is a value measured by the following method. The test piece was dried for 3 days in an environment of 50 ° C. and 667 Pa (5 mmHg) to obtain an absolutely dry test piece. The mass W0 of the absolutely dry test piece was measured. Thereafter, the absolutely dry test piece was immersed in water at a temperature of 23 ° C. and left for 2 months. After lifting from the water, the mass W1 of the test piece was measured. The water absorption rate (%) was calculated by the following formula.
Water absorption rate = {(W1-W0) / W0} × 100

  The molded product of the present invention contains the methacrylic resin composition of the present invention. The molded product of the present invention is not particularly limited in its production method. The molded body of the present invention is, for example, a T-die method (lamination method, coextrusion method, etc.), inflation method (coextrusion method, etc.), compression molding method, blow molding method, calendar molding method, vacuum molding method, injection molding method It can be obtained by molding the methacrylic resin composition of the present invention by a melt molding method such as an insert method, a two-color method, a press method, a core back method, a sandwich method, or the like, and a solution casting method. The molded product of the present invention can also be obtained by a reaction molding method such as a cell cast polymerization method. Specifically, the polymerization reaction of the polymerizable composition containing the radical polymerizable monomer (I), the radical polymerizable monomer (II), and the organophosphorus compound (B) is performed in a desired type. Thus, the molded product of the present invention can be obtained. Among these molding methods, the T-die method, the inflation method, the injection molding method, and the cell cast polymerization method are preferable from the viewpoint of high productivity and cost.

  In obtaining the molded product of the present invention, the molding may be performed a plurality of times. For example, after the methacrylic resin composition of the present invention is molded to obtain a pellet-shaped molded body, the pellet-shaped molded body can be further molded to obtain a molded body having a desired shape.

  In the production of the molded article of the present invention, other polymers may be mixed with the methacrylic resin composition of the present invention and molded as long as the effects of the present invention are not impaired. Examples of such other polymers include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and polynorbornene; ethylene ionomers; polystyrene, styrene-maleic anhydride copolymer, and high impact polystyrene. , AS resins, ABS resins, AES resins, AAS resins, ACS resins, MBS resins and other styrene resins; methyl methacrylate polymers, methyl methacrylate-styrene copolymers; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; nylon 6, polyamides such as nylon 66 and polyamide elastomer; polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, poly Tar, polyvinylidene fluoride, polyurethane, modified polyphenylene ether, polyphenylene sulfide, silicone modified resin; acrylic rubber, silicone rubber; styrene thermoplastic elastomer such as SEPS, SEBS, SIS; olefin rubber such as IR, EPR, EPDM, etc. Can be mentioned.

  Moreover, in this invention, you may add various additives etc. to a methacryl resin composition as needed. Additives include antioxidants, thermal degradation inhibitors, UV absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, impact modifiers, organic dyes, light diffusing agents, matte Agents, phosphors, antistatic agents, plasticizers, inorganic fillers, fibers and the like. The compounding quantity of such various additives can be appropriately set within a range not impairing the effects of the present invention. The amount of each additive is preferably in the range of 0.001 to 5 parts by mass with respect to 100 parts by mass of the total amount of the methacrylic resin composition and other polymers added as necessary. More preferably, the content is in the range of 0.01 to 1 part by mass.

The antioxidant alone has an effect of preventing oxidative deterioration of the resin in the presence of oxygen. Examples thereof include phosphorus antioxidants, hindered phenol antioxidants, and thioether antioxidants. These antioxidants may be used individually by 1 type, and may be used in combination of 2 or more type. Among these, from the viewpoint of preventing the deterioration of optical properties due to coloring, phosphorus-based antioxidants and hindered phenol-based antioxidants are preferable, and the combined use of phosphorus-based antioxidants and hindered phenol-based antioxidants is more preferable. preferable.
In the case where a phosphorus antioxidant and a hindered phenol antioxidant are used in combination, the ratio is not particularly limited, but is preferably a mass ratio of phosphorus antioxidant / hindered phenol antioxidant, preferably 1/5. ˜2 / 1, more preferably ½ to 1/1.

  Examples of phosphorus antioxidants include 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite (manufactured by ADEKA; trade name: ADK STAB HP-10), tris (2,4-di-t- Butylphenyl) phosphite (manufactured by BASF; trade name: IRUGAFOS168).

  As the hindered phenol-based antioxidant, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name IRGANOX 1010), octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (manufactured by BASF; trade name IRGANOX1076).

  The thermal degradation inhibitor can prevent thermal degradation of the methacrylic resin composition by scavenging polymer radicals generated when exposed to high heat in a substantially oxygen-free state. As the thermal degradation inhibitor, 2-t-butyl-6- (3′-t-butyl-5′-methyl-hydroxybenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumilizer GM), 2,4-di-t-amyl-6- (3 ′, 5′-di-t-amyl-2′-hydroxy-α-methylbenzyl) phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumitizer GS) Can be mentioned.

The ultraviolet absorber is a compound having an ability to absorb ultraviolet rays. The ultraviolet absorber is a compound that is said to have a function of mainly converting light energy into heat energy.
Examples of ultraviolet absorbers include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, oxalic acid anilides, malonic acid esters, formamidines, and the like. Benzotriazoles, anilides Is preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

As benzotriazoles, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by Ciba Specialty Chemicals; trade name TINUVIN329), 2 -(2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234) and the like.
Examples of the anilides include 2-ethyl-2′-ethoxy-oxalanilide (manufactured by Clariant Japan; trade name Sundebore VSU).
Of these ultraviolet absorbers, benzotriazoles are most preferably used from the viewpoint of effectively suppressing deterioration of the methacrylic resin composition due to ultraviolet exposure.

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

  Examples of the lubricant include stearic acid, behenic acid, stearamic acid, methylene bisstearamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, and hardened oil.

  The mold release agent is a compound having a function of facilitating mold release from the mold. Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; glycerin higher fatty acid esters such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, it is preferable to use a higher alcohol and a glycerin fatty acid monoester in combination as a release agent. When higher alcohols and glycerin fatty acid monoester are used in combination, the ratio is not particularly limited, but the mass ratio of higher alcohols / glycerin fatty acid monoester is preferably 2.5 / 1 to 3.5 / 1. Preferably it is 2.8 / 1 to 3.2 / 1.

The polymer processing aid is a compound that exhibits an effect on thickness accuracy and thinning when a methacrylic resin composition is molded. The polymer processing aid is polymer particles having a particle diameter of 0.05 to 0.5 μm, which can be usually produced by an emulsion polymerization method.
The polymer particles may be single layer particles composed of polymers having a single composition ratio and single intrinsic viscosity, or multilayer particles composed of two or more kinds of polymers having different composition ratios or intrinsic viscosities. May be. Among these, particles having a two-layer structure having a polymer layer having an intrinsic viscosity of less than 5 dl / g in the inner layer and a polymer layer having an intrinsic viscosity of 5 dl / g or more in the outer layer are preferable. The polymer processing aid as a whole preferably has an intrinsic viscosity of 3 to 6 dl / g.

  Examples of the impact modifier include a core-shell type modifier containing acrylic rubber or diene rubber as a core layer component; a modifier containing a plurality of rubber particles, and the like.

As the organic dye, a compound having a function of converting ultraviolet light, which is considered harmful to the methacrylic resin composition, into visible light is preferably used.
Examples of the light diffusing agent and matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, and barium sulfate.
Examples of the phosphor include a fluorescent pigment, a fluorescent dye, a fluorescent white dye, a fluorescent brightener, and a fluorescent bleach.

  Examples of the antistatic agent include stearoamidopropyldimethyl-β-hydroxyethylammonium nitrate.

  Examples of the plasticizer include tricresyl phosphate, trixylenyl phosphate, triphenyl phosphate, triethylphenyl phosphate, diphenyl cresyl phosphate, monophenyl dicresyl phosphate, diphenyl monoxylenyl phosphate, Phosphoric acid triester plasticizers such as monophenyldixylenyl phosphate, tributyl phosphate, triethyl phosphate; dimethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-2-phthalate Phthalate plasticizers such as ethylhexyl, diisononyl phthalate, octyldecyl phthalate, and butylbenzyl phthalate; fatty acid monobasic acid esters such as butyl oleate and glycerol monooleate Plasticizers; dihydric alcohol ester-based plasticizers; etc. oxyacid ester-based plasticizers.

Moreover, as a plasticizer, squalane (alias: 2,6,10,15,19,23-hexamethyltetracosane, C ₃₀ H ₆₂ , Mw = 422.8), liquid paraffin (white oil, JIS-K-2231) ISO VG10, ISO VG15, ISO VG32, ISO VG68, ISO VG100, ISO VG8, ISO VG21, etc.), polyisobutene, hydrogenated polybutadiene, hydrogenated polyisoprene and the like. Of these, squalane, liquid paraffin and polyisobutene are preferred.

Examples of the inorganic filler include calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, and magnesium carbonate.
Examples of the fiber include glass fiber and carbon fiber.

You may use the molded object of this invention for manufacture of a laminated body. The laminate may be a laminate of two or more molded articles of the present invention, or may be a laminate of the molded article of the present invention and other materials.
The method for producing the laminate is not particularly limited. For example, a method of extruding two or more polymers at the same time (coextrusion method); a method of fusing two or more molded products with heat, ultrasonic waves, high frequency, etc. (fusion method); Method of bonding with ultraviolet curable adhesive, thermosetting adhesive, radiation curable adhesive, etc. (adhesion method); Method of setting a sheet or film in a mold and pouring the molten polymer into the mold (Insert molding method); a method of depositing another substrate by chemical vapor deposition or physical vapor deposition (vapor deposition method); a method of applying a paint containing another substrate to form a film (coating method), and the like. In the fusing method or the bonding method, the surface to be fused or the surface to be bonded may be surface-treated with a known primer, or subjected to corona discharge treatment or plasma treatment before fusing or bonding. Also good.

  The other raw material laminated | stacked on the molded object of this invention is not restrict | limited in particular, According to the use of a laminated body, it can select suitably. Other materials in the case where the laminate is used as an optical component are not particularly limited. For example, hard coating materials, antireflection materials, liquid crystals, cyclic olefin-based ring-opening polymers or hydrogenated products thereof, and cyclic olefin-based addition polymers. Aliphatic olefin resin, acrylic polymer, polycarbonate resin, liquid crystal polymer, soda glass, quartz glass and the like.

  The molded body of the present invention or a laminate including the molded body can be printed on the surface, or the surface can be shaped by cutting, embossing or the like. After printing or shaping, if it is laminated with other materials by insert molding, etc., the characters, patterns, irregularities, etc. formed by printing or shaping are enclosed between the molded body of the present invention and other materials. . Since the molded article of the present invention is excellent in transparency, encapsulated characters, patterns, irregularities and the like can be clearly observed.

  The molded body according to the present invention or the laminate including the molded body is preferably a film or a sheet. Generally, a film refers to a planar molded body having a thickness of 0.005 mm or more and 0.25 mm or less, and a sheet refers to a planar molded body having a thickness of more than 0.25 mm.

  The methacrylic resin composition and molded product of the present invention are excellent in transparency, flame retardancy, and low water absorption, so that they are used in various fields such as the optical field, food field, medical field, automobile field, and electric / electronic field. Can be used, for example, various optical members for optical equipment (microscope, binoculars, camera, etc.) (finder, filter, prism, Fresnel lens, etc.), display equipment (TV, touch panel, personal computer, mobile terminal, etc.) Various optical members (light guide film / sheet, retardation film / sheet, polarizing film / sheet, polarizing plate protective film / sheet, light diffusion film / sheet, prism film / sheet, reflective film / sheet, antireflection film / sheet, Wide viewing angle film / sheet, anti-glare film / sheet, brightness enhancement film / sheet, front plate, etc.), light switch Ji, optical members such as optical connectors; lighting member such as a lighting cover is useful for such. Further, it is useful for applications such as house parts (roofs, windows, gutters, walls, etc.), retroreflective films / sheets, agricultural films / sheets, signs, decorative members, etc.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In addition, this invention is not restrict | limited by a following example.

  The physical properties of the methacrylic resin (A) and the methacrylic resin composition obtained in Examples and Comparative Examples were measured by the following methods.

[Proportion of structural units constituting methacrylic resin (A) and phosphorus atom content in methacrylic resin composition]
Ratio of structural units constituting methacrylic resin (A) using a nuclear magnetic resonance apparatus (Bruker ULTRA SHIELD 400 PLUS; solvent = deuterated chloroform; measurement nuclide = ¹ H; measurement temperature = room temperature; integration number = 64 times) The phosphorus atom content in the methacrylic resin composition was analyzed.

[Weight average molecular weight, molecular weight distribution]
The weight average molecular weight and molecular weight distribution of the methacrylic resin (A) were determined in terms of polystyrene based on measurements by gel permeation chromatography (GPC). Here, as a GPC device, HLC-8320 (product number) manufactured by Tosoh Corporation is used, and as a column, two TSKgel SuperMultipore HZM-M manufactured by Tosoh Corporation and one SuperHZ4000 are used in series. It was.
Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml / min Column temperature: 40 ° C
Calibration curve: Created using 10 standard polystyrene points

[Flame retardance]
A 3.2 mm-thick test piece was allowed to stand for 48 hours in an environment of 23 ° C. and 50% RH. In accordance with the UL94V test, the test piece held vertically was contacted with a burner twice for 10 seconds. Flame retardancy was evaluated by each afterflame time and drip property. In addition, the flame retardance was very low, and those outside the UL94V test standard were designated as “BS” (Below Standard).

[transparency]
According to JIS K7361-1, the total light transmittance of a 3.2 mm thick test piece was measured using HR-100 (product number) manufactured by Murakami Color Research Laboratory.

[Water absorption]
The 3.2 mm-thick test piece was dried for 3 days in an environment of 50 ° C. and 667 Pa (5 mmHg) to obtain an absolutely dry test piece. The mass W0 of the absolutely dry test piece was measured. Thereafter, the absolutely dry test piece was immersed in water at a temperature of 23 ° C. and left for 2 months. After lifting from the water, the mass W1 of the test piece was measured. The water absorption rate (%) was calculated by the following formula.
Water absorption rate = {(W1-W0) / W0} × 100

[Char amount]
Thermogravimetric measurements were performed on the resin compositions obtained in Examples and Comparative Examples in accordance with JIS K7120 under the conditions of raising the temperature from room temperature to 600 ° C. at 10 ° C./min in the air. Shimadzu-50 (product number) was used as a measuring device. The char amount (% by mass) was calculated by the following formula. It is considered that the greater the amount of char, the higher the flame retardancy.
Char amount (mass%) = (W3 / W2) × 100
W2: Weight of methacrylic resin composition at start of measurement W3: Weight of methacrylic resin composition at 500 ° C.

The compounds used in Examples and Comparative Examples are shown below.
<Radically polymerizable monomer (I)>
-Methacrylic acid 8-tricyclo [5.2.1.0 ^2,6 ] decanyl (hereinafter referred to as “TCDMA”)
-2-isobornyl methacrylate (hereinafter referred to as “IBMA”)
-4-t-butylcyclohexyl methacrylate (hereinafter referred to as “t-BCHMA”)
T-butyl methacrylate (hereinafter referred to as “t-BMA”)

<Radically polymerizable monomer (II)>
・ Methyl methacrylate (hereinafter referred to as “MMA”)
・ Methyl acrylate (hereinafter referred to as “MA”)
Styrene (hereinafter referred to as “St”) was used.
-Methacrylic acid (hereinafter referred to as "MAA") was used.

<Organic phosphorus compounds>
・ FP-800
・ BCA
・ PX-200

<Others>
・ Orthophosphoric anhydride

[Example 1]
30% by mass of TCDMA, 68% by mass of MMA, and 2% by mass of MA were mixed to obtain a monomer mixture. To 100 parts by mass of this monomer mixture, 0.1 part by mass of a polymerization initiator (2,2′-azobis (2-methylpropionitrile), hydrogen abstraction capacity: 1%, 1 hour half-life temperature: 83 ° C.) And 0.1 part by mass of a chain transfer agent (n-octyl mercaptan) were added and dissolved to obtain a raw material liquid.
100 parts by mass of ion-exchanged water, 0.03 parts by mass of sodium sulfate, and 0.46 parts by mass of a suspension dispersant were mixed to obtain a mixed solution.
420 parts by mass of the mixed solution and 210 parts by mass of the raw material liquid were charged into a pressure-resistant polymerization tank, and the polymerization reaction was started at a temperature of 70 ° C. while stirring in a nitrogen atmosphere. After 3 hours from the start of the polymerization reaction, the temperature was raised to 90 ° C., and stirring was continued at 90 ° C. for 1 hour to obtain a dispersion in which bead-shaped fine particles were dispersed. Fine particles were scraped from the dispersion, washed with ion-exchanged water, and then dried under reduced pressure at 100 Pa for 4 hours at 80 ° C. to obtain bead-like methacrylic resin (a1).

  12 parts by mass of FP-800 was added to 100 parts by mass of the methacrylic resin (a1), and this was supplied to a twin screw extruder controlled at 230 ° C. and melt-kneaded. The kneaded product was then extruded into a strand. The strand was cut with a pelletizer to obtain a pellet-like methacrylic resin composition.

[Preparation of test piece]
The pellet-like methacrylic resin composition was hot press molded at 230 ° C. to obtain a sheet having a thickness of 3.2 mm. A test piece having a length of 127 mm, a width of 13 mm, and a thickness of 3.2 mm was cut out from the obtained sheet. As described above, flame retardancy, water absorption and transparency were evaluated using the test pieces. The results are shown in Table 1.

[Examples 2 to 12 and Comparative Examples 1 to 5]
A pellet-shaped methacrylic resin composition and a test piece were obtained in the same manner as in Example 1 except that the formulation shown in Table 1 was changed. As described above, flame retardancy, water absorption and transparency were evaluated using the test pieces. The evaluation results are shown in Tables 1 and 2.

[Comparative Example 6]
A monomer mixture was obtained by mixing 85% by mass of MMA and 15% by mass of MAA. To 100 parts by mass of this monomer mixture, 5 parts by mass of orthophosphoric anhydride and 0.09 parts by mass of 2,2′-azobisisobutyronitrile were added. Subsequently, it deaerated for 30 minutes at 650 mmHg (87 kPa), and the raw material liquid was obtained.
The raw material solution was poured into a glass cell composed of two water-repellent glass plates (thickness 10 mm, 30 cm square) and a vinyl chloride resin gasket, and the mixture was charged at 72 ° C. for 3 hours and then at 120 ° C. for 1 hour. Polymerization was carried out in a hot air circulating furnace for a time to obtain a sheet having a thickness of 3.2 mm. A test piece having a length of 127 mm, a width of 13 mm, and a thickness of 3.2 mm was cut out from the obtained sheet. As described above, flame retardancy, water absorption and transparency were evaluated using the test pieces. The results are shown in Table 1. In addition, this test piece was cloudy, the total light transmittance was low, and there existed two values of the glass transition temperature. The obtained sheet-like molded product did not dissolve in the solvent because the obtained methacrylic resin (a18) had a very high molecular weight, and only swelled. Therefore, the molecular weight of the methacrylic resin (a18) could not be measured by GPC. The estimated weight average molecular weight is 1 million g / mol or more. The phosphorus atom content (% by mass) in the methacrylic resin composition was calculated by ¹ H-NMR measurement in a swollen state. The results are shown in Table 2.

The methacrylic resin according to the present invention is excellent in flame retardancy even in a range where the content of the phosphorus compound is low. For example, the methacrylic resin composition of Example 1 is superior to the methacrylic resin composition of Comparative Example 1 in terms of flame retardancy, although the content of the organic phosphorus compound is small. When the methacrylic acid ester represented by the formula (I) is copolymerized, it exhibits high flame retardancy even if the content of the organic phosphorus compound (B) is small, so the amount of the relatively expensive organic phosphorus compound (B) used. Therefore, a methacrylic resin excellent in the balance of flame retardancy, transparency and heat resistance can be obtained at low cost (Examples 1 to 12).
As described above, the methacrylic resin composition of the present invention has excellent dimensional stability due to excellent transparency and flame retardancy and low water absorption.

Claims (7)

Structural units 60 to 90 derived from radically polymerizable monomers (II) other than methacrylic acid esters represented by formula (I) and 10 to 40% by mass of structural units derived from methacrylic acid esters represented by formula (I) A methacrylic resin composition containing a methacrylic resin (A) and an organic phosphorus compound (B),
The methacrylic resin composition whose content of the phosphorus atom in this methacrylic resin composition is 0.8-5 mass%.

(In the formula (I), R ¹ is a polycyclic aliphatic hydrocarbon group, an alkyl-substituted monocyclic aliphatic hydrocarbon group, —CH ₂ CHR ² R ³ , —CHR ² —CHR ³ R ⁴ , or —CR ² R ³ represents R ⁵ , R ² , R ³ and R ⁵ each independently represents an alkyl group having 1 to 3 carbon atoms, and R ⁴ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) 2. The methacrylic resin composition according to claim 1, wherein R ¹ is at least one selected from the group consisting of a t-butyl group, a norbornyl group, an isobornyl group, a tricyclodecanyl group, and a 4-t-butylcyclohexyl group.   The methacrylic resin composition according to claim 1 or 2, wherein the radical polymerizable monomer (II) is methyl (meth) acrylate.   The methacrylic resin composition according to claim 1 or 2, wherein the radical polymerizable monomer (II) is an aromatic vinyl compound.   The methacrylic resin composition according to any one of claims 1 to 4, wherein the organic phosphorus compound (B) is a phosphate ester or a condensed phosphate ester.   The methacrylic resin composition according to any one of claims 1 to 5, wherein the flame retardancy according to the UL-94 test is V-2 or more and the water absorption is 5% or less.   The molded object containing the methacrylic resin composition as described in any one of Claims 1-6.