JP2003221421A - Graft copolymer having multilayered structure and methacrylic resin composition using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a graft copolymer having a multilayered structure in order to obtain a methacrylic resin composition having excellent transparency and impact resistance, good weather resistance and processability. <P>SOLUTION: The graft copolymer having the multilayered structure is comprised of an innermost layer polymer (A) obtained from a 1-4C alkyl methacrylate, a 1-8C alkyl acrylate, other monomers and polyfunctional monomers, an intermediate layer polymer (B) obtained by polymerizing a 108C alkyl acrylate, an aromatic vinyl compound, other monomers and polyfunctional monomers in the presence of (A) and an outermost layer polymer (C) obtained by polymerizing a 1-4C alkyl methacrylate, a 1-8C alkyl acrylate and other monomers in the presence of (B). The particle size to (B) as well as weight ratio of C/(A+B) are within specific ranges. (A), (B) and (C) are all obtained by emulsion polymerization using a water soluble inorganic polymerization initiator. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a multi-layered graft copolymer having excellent transparency and impact resistance, and a methacrylic resin composition using the same.

[0002]

BACKGROUND OF THE INVENTION Methacrylic resin is excellent in transparency, weather resistance and moldability and is widely used in automobile parts, lighting equipment, various panels and the like. However, in general, methacrylic resin is not sufficient in impact resistance, so that its application is narrowed. Therefore, many means have been proposed for improving the impact resistance of methacrylic resin.

For example, Japanese Examined Patent Publication No. 55-27576 discloses adding impact resistance of a hard resin such as methacrylic resin by adding a multi-step polymer having a specific hard-soft-hard three-step basic structure. It is proposed to improve. However, even with this method, the improvement of impact resistance is insufficient. Further, JP-A-9-309938 proposes a method for improving the temperature dependence of haze by using a specific polymerization initiator. However, even in this method, the effect of improving the transparency can be seen, but the impact resistance is insufficient, and a resin composition having sufficient impact resistance without impairing the excellent transparency of the methacrylic resin is sought. Has been.

[0004]

The object of the present invention is to improve impact resistance, which was insufficient with conventional methacrylic resins, and to have excellent transparency and impact resistance, as well as good weather resistance and workability. Another object of the present invention is to provide a multi-layered structure graft copolymer which provides a simple resin composition and a methacrylic resin composition containing the same.

[0005]

Means for Solving the Problems The present inventors have made diligent studies in view of such a situation, and as a result, appropriately selected a polymerization initiator to be used for polymerizing a graft copolymer having a multilayer structure,
The present invention has been completed by finding that the above problems can be solved by combining appropriate composition of the innermost layer, ratio of each layer, and particle size.

That is, according to the present invention, 40 to 70% by mass of an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms,
Alkyl acrylate 3 whose alkyl group has 1 to 8 carbon atoms
0-60 mass% and other copolymerizable monomers 0-
Innermost layer polymer (A) obtained by polymerizing a mixture of 100 parts by mass of a monomer mixture consisting of 20% by mass and 0.1 to 10 parts by mass of a polyfunctional monomer, and the innermost layer polymer ( In the presence of A), 70 to 90% by mass of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms, and an aromatic vinyl compound 10 to 3 are used.
It is obtained by polymerizing a mixture of 100 parts by mass of a monomer mixture consisting of 0% by mass and 0 to 20% by mass of another copolymerizable monomer and 0.1 to 5 parts by mass of a polyfunctional monomer. In the presence of the intermediate layer polymer (B) and the intermediate layer polymer (B),
50 to 100 mass% of alkyl methacrylate having 1 to 4 carbon atoms of alkyl group, 0 to 50 mass% of alkyl acrylate having 1 to 8 carbon atoms of alkyl group, and 0 to 20 mass% of other copolymerizable monomer The outermost layer polymer (C) obtained by polymerizing the monomer mixture consisting of, the particle size up to the intermediate layer polymer (B) is 200 to 300 nm, and the mass of the innermost layer polymer (A). Outermost layer polymer (C) with respect to the sum of (a) and mass (b) of intermediate layer polymer (B)
Mass ratio (c) / ((a) + (b)) of 0.2
Is 1.0 to 1.0, and all of the innermost layer polymer (A), the intermediate layer polymer (B) and the outermost layer polymer (C) are obtained by emulsion polymerization using a water-soluble inorganic polymerization initiator. It is a multi-layered structure graft copolymer obtained by the above method.

Further, the present invention is a methacrylic resin composition comprising 50 to 95% by mass of a hard methacrylic resin containing methyl methacrylate as a main component and 5 to 50% by mass of the above graft copolymer having a multilayer structure.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The multi-layer structure graft copolymer of the present invention comprises at least three layers of a polymer comprising an innermost layer polymer (A), an intermediate layer polymer (B) and an outermost layer polymer (C). And each layer is composed of a monomer having the composition shown below.

The innermost layer polymer (A) is an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, 40 to 70% by mass, more preferably 50 to 65% by mass, and an alkyl group having 1 to 8 carbon atoms. Acrylate 30 to 60% by mass, more preferably 35 to 50% by mass, and other copolymerizable monomer 0 to 20% by mass, more preferably 1
100 parts by mass of a monomer mixture consisting of 10 to 10% by mass and 0.1 to 10 parts by mass of a polyfunctional monomer, more preferably 1 to 5
Obtained by polymerizing a mixture with wt.%. Excellent impact resistance and transparency can be obtained by controlling the monomer composition within the above ranges. Particularly, when the amount of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is less than 30% by mass, Impact resistance cannot be obtained.

The alkyl group used here has a carbon number of 1
Examples of the alkyl methacrylates of to 4 include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate and the like, and these can be used alone or in combination of two or more kinds. Examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, i-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like, which may be used alone or in combination of two or more kinds. Can be used. The other copolymerizable monomer is not particularly limited as long as it is a vinyl monomer copolymerizable with these, for example, phenyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate,
In addition to methacrylic acid, acrylic acid, hydroxyethyl methacrylate, acrylamide, glycidyl methacrylate, and the like, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and the like can be given. These can be used alone or in combination of two or more. Can be used.

The polyfunctional monomers include ethylene glycol diacrylate, 1,3-butanediol diacrylate, allyl methacrylate, triallyl cyanurate, diallyl maleate, divinylbenzene, diallyl phthalate, diallyl fumarate, and triaryl fumarate. Triallyl meritate and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

The intermediate layer polymer (B) is contained in the presence of the innermost layer polymer (A) in an amount of 70 to 90% by mass, more preferably 7 to 90% by mass of an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms.
100 parts by mass of a monomer mixture consisting of 5 to 85% by mass, an aromatic vinyl compound 10 to 30% by mass, more preferably 15 to 25% by mass, and 0 to 20% by mass of another copolymerizable monomer. It is obtained by polymerizing a mixture of 0.1 to 5% by mass of the polyfunctional monomer, and more preferably 1 to 3% by mass. Examples of the alkyl acrylate, aromatic vinyl compound and polyfunctional monomer used in this intermediate layer (B) include
The same monomers as those mentioned above as examples of the monomer usable for the innermost layer polymer (A) can be used.

The outermost layer polymer (C) comprises the innermost layer polymer (A) and the intermediate layer polymer (B) in the presence of the above-mentioned intermediate layer polymer (B), more accurately. In the presence of a polymer, the alkyl group has 50 to 100% by mass of an alkyl methacrylate having 1 to 4 carbon atoms, more preferably 80% by mass.
To 97% by mass, an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, 0 to 50% by mass, and more preferably 3 to 20% by mass.
It is obtained by polymerizing a monomer mixture composed of 0 to 20% by mass of other copolymerizable monomers. As the monomer used for the outermost layer polymer (C), the same monomers as those mentioned above as examples of the monomer usable for the innermost layer polymer (A) can be used.

Further, in order to improve the compatibility with the matrix resin, the fluidity and the impact resistance, it is preferable to use a chain transfer agent such as alkyl mercaptan. Examples of the alkyl mercaptan include n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, and t-dodecyl mercaptan, and the outermost layer polymer (C).
It is preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the monomer mixture used in.

The particle size up to the intermediate layer polymer (B) is 200.
˜300 nm, more preferably 220 to 270 nm. If the particle size up to the intermediate layer polymer (B) is less than 200 nm, it becomes difficult to make the impact strength sufficient, and if it exceeds 300 nm, the transparency tends to decrease.

The composition ratio of each layer is such that the mass (a) of the innermost layer polymer (A) and the mass (b) of the intermediate layer polymer (B).
The ratio with is preferably 20:80 to 60:40. The mass of the polymer in each layer is the total mass of the monomers forming each layer.

The ratio (c) of the mass (c) of the outermost layer polymer (C) to the sum of the mass (a) of the innermost layer polymer (A) and the mass (b) of the intermediate layer polymer (B). / ((A) +
(B)) is 0.2 to 1.0, more preferably 0.
It is 5 to 0.7. When this ratio is less than 0.2, it becomes difficult to make the impact resistance sufficient, and when it exceeds 1.0, it becomes difficult to make the impact resistance sufficient.

In the multi-layer structure graft copolymer of the present invention, all of the innermost layer polymer (A), the intermediate layer polymer (B) and the outermost layer polymer (C) use a water-soluble inorganic polymerization initiator. It must be emulsion-polymerized. If no water-soluble inorganic polymerization initiator is used, it is difficult to make the impact strength sufficient. The water-soluble inorganic polymerization initiator referred to in the present invention, potassium persulfate, sodium persulfate, persulfates such as ammonium persulfate, potassium perborate, sodium perborate, perborate salts such as ammonium perborate, hydrogen peroxide. Means a water-soluble inorganic polymerization initiator such as Among these, it is preferable to use a persulfate selected from potassium persulfate, sodium persulfate and ammonium persulfate from the viewpoints of economy and handleability.

The amount of the water-soluble inorganic polymerization initiator used varies slightly depending on the kind of the initiator, but the innermost layer polymer (A), the intermediate layer polymer (B) and the outermost layer polymer (C) are formed. The amount is preferably 0.03 to 2 parts by mass, more preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the monomer.

As the emulsifier used in the production of the multi-layer structure graft copolymer of the present invention, any of anionic, cationic and nonionic emulsifiers can be used, but anionic emulsifiers are particularly preferable. As anionic emulsifier, potassium oleate, sodium stearate,
Carboxylic acid salts such as sodium myristate, sodium N-lauroyl sarcosinate, dipotassium alkenyl succinate, sulfate ester salts such as sodium lauryl sulfate,
Examples thereof include sulfonates such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium alkyldiphenyl ether disulfonate, and polyoxyethylene alkyl ether phosphate salts, and more preferably represented by the following general formula (1).

[0021]

[R ¹ -O (R ² O) _m ] _n -P (= O)-(OM) _q (1) (In the formula, R ¹ is a linear or branched alkyl group having 10 to 18 carbon atoms. R ² is a linear or branched alkylene group having 2 or 3 carbon atoms, M is an alkali metal or alkaline earth metal, m is an integer of 1 to 20, n is 1 or 2,
q is 1 or 2, and n + q is 3. ) Mono-n-decyloxytetraoxyethylene phosphoric acid,
Di-n-decyloxytetraoxyethylene phosphoric acid, mono-n-dodecyloxytetraoxyethylene phosphoric acid,
Di-n-dodecyloxytetraoxyethylene phosphoric acid,
Mono-n-tetradecyloxytetraoxyethylene phosphoric acid, di-n-tetradecyloxytetraoxyethylene phosphoric acid, mono-n-hexadecyloxytetraoxyethylene phosphoric acid, di-n-hexadecyloxytetraoxyethylene phosphoric acid Acid, mono-n-octadecyloxytetraoxyethylene phosphoric acid, di-n-octadecyloxytetraoxyethylene phosphoric acid, mono-n-decyloxyhexaoxyethylene phosphoric acid, di-n-decyloxyhexaoxyethylene phosphoric acid, Mono-n-dodecyloxyhexaoxyethylene phosphoric acid, di-n-dodecyloxyhexaoxyethylene phosphoric acid, mono-n-tetradecyloxyhexaoxyethylene phosphoric acid, di-n-tetradecyloxyhexaoxyethylene phosphoric acid, Mono-n-
Hexadecyloxyhexaoxyethylene phosphoric acid, di-
n-hexadecyloxyhexaoxyethylene phosphoric acid,
Mono-n-octadecyloxyhexaoxyethylene phosphoric acid, di-n-octadecyloxyhexaoxyethylene phosphoric acid, mono-n-decyloxyoctaoxyethylene phosphoric acid, di-n-decyloxyoctaoxyethylene phosphoric acid, mono- n-dodecyloxyoctaoxyethylene phosphoric acid, di-n-dodecyloxyoctaoxyethylene phosphoric acid, mono-n-tetradecyloxyoctaoxyethylene phosphoric acid, di-n-tetradecyloxyoctaoxyethylene phosphoric acid, mono- Directly such as n-hexadecyloxyoctaoxyethylenephosphoric acid, di-n-hexadecyloxyoctaoxyethylenephosphoric acid, mono-n-octadecyloxyoctaoxyethylenephosphoric acid, di-n-octadecyloxyoctaoxyethylenephosphoric acid. Chain alkyloxypolio Alkali metal salts or alkaline earth metal salts of ciethylene phosphoric acid, mono-isodecyloxytetraoxyethylene phosphoric acid, di-isodecyloxytetraoxyethylene phosphoric acid, mono-isododecyloxytetraoxyethylene phosphoric acid, di-iso Dodecyloxytetraoxyethylene phosphoric acid, mono-isotetradecyloxytetraoxyethylene phosphoric acid, di-isotetradecyloxytetraoxyethylene phosphoric acid, mono-isohexadecyloxytetraoxyethylene phosphoric acid, di-
Isohexadecyloxytetraoxyethylene phosphoric acid,
Mono-isooctadecyloxytetraoxyethylene phosphoric acid, di-isooctadecyloxytetraoxyethylene phosphoric acid, mono-isodecyloxyhexaoxyethylene phosphoric acid, di-isodecyloxyhexaoxyethylene phosphoric acid, mono-isododecyloxyhexa Oxyethylene phosphoric acid, di-isododecyloxyhexaoxyethylene phosphoric acid, mono-isotridecyloxyhexaoxyethylene phosphoric acid, di-isotridecyloxyhexaoxyethylene phosphoric acid, mono-isotetradecyloxyhexaoxyethylene phosphoric acid Acid, di-isotetradecyloxyhexaoxyethylene phosphoric acid, mono-isohexadecyloxyhexaoxyethylene phosphoric acid, di-isohexadecyloxyhexaoxyethylene phosphoric acid, mono-isooctadecyloxy Oxyethylenated phosphoric acid, di - iso octadecyloxy hexaoxyethylene phosphate, mono - isodecyloxy oct oxyethylene phosphate, di -
Isodecyloxyoctaoxyethylene phosphoric acid, mono-
Isododecyloxyoctaoxyethylene phosphoric acid, di-
Isododecyloxyoctaoxyethylene phosphoric acid, mono-isotridecyloxyoctaoxyethylene phosphoric acid,
Di-isotridecyloxyoctaoxyethylene phosphoric acid, mono-isotetradecyloxyoctaoxyethylene phosphoric acid, di-isotetradecyloxyoctaoxyethylene phosphoric acid, mono-isohexadecyloxyoctaoxyethylene phosphoric acid, di- Alkali metal salt or alkaline earth metal of branched alkyloxypolyoxyethylene phosphoric acid such as isohexadecyloxyoctaoxyethylene phosphoric acid, mono-isooctadecyloxyoctaoxyethylene phosphoric acid, di-isooctadecyloxyoctaoxyethylene phosphoric acid Examples include salt. Examples of the alkali metal include sodium or potassium, and examples of the alkaline earth metal include calcium or barium. These phosphoric acid ester salts can be used alone or in combination of two or more.

In the production of the multi-layer structure graft copolymer of the present invention, the monomer, the polymerization initiator and the like can be added by various methods such as a batch addition method, a divided addition method, a continuous addition method or a monomer addition method and an emulsion addition method. It can be added. In order to smoothly proceed the reaction, a method such as substituting the reaction system with nitrogen or adding a special catalyst after completion of the reaction to remove residual monomers may be adopted.

Various methods such as an acid coagulation method, a salt coagulation method, a freeze coagulation method, and a spray drying method can be used as a method for recovering the multi-layer structure graft copolymer from the latex.
As the recovering agent used in the salt coagulation method, aluminum chloride,
Inorganic salts such as aluminum sulfate, sodium sulfate, magnesium sulfate, sodium nitrate and calcium acetate can be mentioned, but calcium acetate is particularly preferable in order to suppress the coloring property of the recovered multilayer structure graft copolymer.

The concentration of the recovery agent aqueous solution is 0.1 to 20% by mass.
Is preferable, and 1 to 15 mass% is more preferable. If the concentration is too low, it may not be possible to stably recover the resin, and if the concentration is too high, a large amount of recovery agent remains in the recovered resin,
It may undesirably deteriorate the performance of the molded article such as coloring property. The temperature at which the latex is brought into contact with the aqueous solution of the collecting agent is preferably 30 ° C to 100 ° C. The deposited resin is washed, dehydrated and dried by various methods.

The multi-layer structure graft copolymer of the present invention is blended with a hard methacrylic resin containing methyl methacrylate as a main component (which becomes a matrix resin) to give a methacrylic resin composition excellent in transparency and impact resistance. Is obtained. The mixing ratio of the multi-layer structure graft copolymer and the hard methacrylic resin varies depending on the use, but the multi-layer structure graft copolymer is 5 to 50 mass% and the hard methacrylic resin 50.
It is preferable to mix at a ratio of ˜95% by mass.

[0026]

The present invention will be described in more detail with reference to the following examples. In addition, "part" in an Example represents "mass part", and "%" other than haze% represents "mass%", respectively. The particle size of the intermediate layer polymer (B) is the same as that of Matec Applied.
Using a CHDF2000 type particle size distribution analyzer manufactured by Sciences, the measurement was performed at a column temperature of 35 ° C. and a carrier liquid flow rate of 1.4 ml / min. Further, the obtained methacrylic resin composition was injection-molded under the following conditions, and then various properties were measured.

Injection molding of Izod impact strength test pieces Equipment: PS-60E injection molding machine manufactured by Nissei Plastic Co., Ltd. Cylinder temperature: 260 ℃ Test piece size: 100 mm x 50 mm x 2 mm thickness 127 mm x 12.7 mm x 6.35 mm thickness Izod impact strength It was measured according to ASTM-D-256. Haze It was measured according to ASTM-D1003. Yellow index (YI) It was measured according to ASTM-D1925.

Example 1 Stirrer, reflux condenser, nitrogen blowing port, monomer addition port,
A 5-neck flask equipped with a thermometer was charged with 300 parts of deionized water, 0.1 part of sodium carbonate and 1.0 part of boric acid. Next, the system was heated to 80 ° C. while substituting with nitrogen, 1/10 of the mixture (1-a) having the following composition was added, and 0.075 part of potassium persulfate (KPS) was added as a polymerization initiator. After maintaining for 15 minutes, the rest of the mixture (1-a) was added over 2 hours, and the polymerization was completed by maintaining the temperature at 80 ° C. for 1 hour. The polymerization rate of the obtained latex (1-A) was 99% or more.

[0029]   Mixture (1-a) Methyl methacrylate 32.0 parts Styrene 4.0 parts Butyl acrylate 24.0 parts 1.0 parts of 1,3-butanediol dimethacrylate Allyl methacrylate 0.2 parts Sodium mono-isotridecyloxyhexaoxyethylene phosphate and di-iso Sodium tridecyloxyhexaoxyethylene phosphate and isotridecyl oxy A mixture of cipentaoxyethyleneoxyethanol in a weight ratio of 1: 1: 0.1. Osfanol RS-610NA, trade name, manufactured by Toho Chemical Co., Ltd. (hereinafter emulsifier) (A) 0.9 parts

Subsequently, the polymerization initiator KPS was added to 1-A above.
0.2 part was added, the mixture (1-b) having the following composition was added dropwise over 3 hours, and the mixture was kept for 3 hours to complete the polymerization. The polymerization rate of the obtained latex (1-B) was 99% or more, and the particle size was 220 nm.

[0031]   Mixture (1-b) Styrene 17.0 parts Butyl acrylate 73.0 parts 0.2 parts of 1,3-butanediol dimethacrylate Allyl methacrylate 1.0 part Emulsifier A 0.9 parts

Subsequently, 0.1 part of a polymerization initiator KPS was added to the latex (1-B) to prepare a mixture (1-
c) was added dropwise over 2 hours and kept for 1 hour to complete the polymerization. The polymerization rate of the obtained final latex (1-C) was 99% or more.

[0033]   Mixture (1-c) Methyl methacrylate 85.5 parts Methyl acrylate 4.5 parts n-octyl mercaptan 0.3 part

1.6 as a recovery agent in a stainless steel container
% Aqueous solution of calcium acetate (300 parts) and charged to 90 ° C. with mixing and stirring to obtain the final latex (1-C) 300
Parts were added continuously over 10 minutes and then held for 5 minutes. The mixture was cooled to room temperature, filtered by centrifugal dehydration (1300 G, 3 minutes) while washing with deionized water to obtain a wet resin, and dried at 75 ° C. for 48 hours to obtain a white powder resin.

Next, a mixture of 1600 parts of the powdery resin and 2400 parts of methacrylic resin (Acrypet VH, trade name, manufactured by Mitsubishi Rayon Co., Ltd.) was used to form a 2 mm outer diameter of 30 mmφ.
Axial screw type extruder (PCM-30 made by Ikegai Corporation)
Type, L / D = 25), cylinder temperature 230 ° C
The pellets were prepared by melt-kneading at ~ 260 ° C and a die temperature of 260 ° C. A molded body was prepared using this pellet, and the Izod impact strength, haze, and YI were evaluated, and the results are shown in Table 1.

Example 2 To the latex (1-B) obtained in the same manner as in Example 1, 0.07 part of a polymerization initiator KPS was added, and a mixture (2
-C) was added dropwise over 2 hours and kept for 1 hour to complete the polymerization. Then, the same operation as in Example 1 was performed to produce a molded body.

[0037]   Mixture (2-c) Methyl methacrylate 57.0 parts Methyl acrylate 3.0 parts 0.2 parts of n-octyl mercaptan

Example 3 To the latex (1-B) obtained in the same manner as in Example 1, 0.13 part of a polymerization initiator KPS was added, and a mixture (3
-C) was added dropwise over 2 hours and kept for 1 hour to complete the polymerization. Then, the same operation as in Example 1 was performed to produce a molded body.

[0039]   Mixture (3-c) Methyl methacrylate 114.0 parts Methyl acrylate 6.0 parts 0.4 parts of n-octyl mercaptan

Example 4 The mixture (1-a) of Example 1 was mixed with the mixture (4
A molded product was produced in the same manner as in Example 1 except that the procedure was changed to -a). The particle size up to the intermediate layer polymer is 280 nm
Met.

[0041]   Mixture (4-a) Methyl methacrylate 32.0 parts Styrene 4.0 parts Butyl acrylate 24.0 parts 1.0 parts of 1,3-butanediol dimethacrylate Allyl methacrylate 0.2 parts Emulsifier A 0.65 parts

Example 5 A molded product was produced in the same manner as in Example 1 except that magnesium sulfate was used as the recovering agent in Example 1.

Comparative Example 1 Stirrer, reflux condenser, nitrogen blowing port, monomer addition port,
300 parts of deionized water, sodium formaldehyde sulfoxylate (hereinafter referred to as SF
0.48 parts, ferrous sulfate 0.6 × 10 ⁻⁴ parts and ethylenediaminetetraacetic acid disodium 1.8 × 10.
^{-Built in 4} parts. Next, the system was heated to 80 ° C. while substituting with nitrogen, 1/10 of the mixture (5-a) having the following composition was added, and the mixture was held for 15 minutes, and then the rest of (5-a) was taken over 2 hours. The mixture was charged and kept at 80 ° C. for 1 hour to complete the polymerization. The polymerization rate of the obtained latex (5-A) was 99% or more.

[0044]   Mixture (5-a) Methyl methacrylate 32.0 parts Styrene 4.0 parts Butyl acrylate 24.0 parts 1.0 parts of 1,3-butanediol dimethacrylate Allyl methacrylate 0.2 parts t-Butyl hydroperoxide 0.1 part Emulsifier A 2.0 parts

Subsequently, 0.2 part of SFS and 5 parts of deionized water were added to the above 5-A and held for 15 minutes, then a mixture (5-b) having the following composition was added dropwise over 3 hours, and the mixture was held for 3 hours. The polymerization was completed. The obtained latex (5
The polymerization rate of -B) was 99% or more, and the particle size was 250 nm.

[0046]   Mixture (5-b) Styrene 17.0 parts Butyl acrylate 73.0 parts 0.2 parts of 1,3-butanediol dimethacrylate Allyl methacrylate 1.0 part Cumene hydroperoxide 0.2 parts Emulsifier A 2.5 parts

Subsequently, SFS 0.
After adding 3 parts and 5.0 parts of deionized water and holding for 15 minutes, the mixture (5-c) having the following composition was added dropwise over 2 hours and maintained for 1 hour to complete the polymerization. The polymerization rate of the obtained final latex (5-C) was 99% or more.

[0048]   Mixture (5-c) Methyl methacrylate 85.5 parts Methyl acrylate 4.5 parts t-butyl hydroperoxide 0.15 parts n-octyl mercaptan 0.3 part

Comparative Example 2 (1-B) of Example 1 was supplemented with 0.2 part of SFS, 5.0 parts of deionized water, 0.6 × 10 ^-4 parts of ferrous sulfate and disodium ethylenediaminetetraacetate. Add 8 × 10 ^-4 parts,
After holding for 15 minutes, the mixture (6-c) having the following composition was added to 2
The mixture was added dropwise over a period of time and kept for 1 hour to complete the polymerization.
The polymerization rate of the obtained final latex (6-C) was 99% or more. Then, the same operation as in Example 1 was performed to produce a molded body.

[0050]   Mixture (6-c) Methyl methacrylate 85.5 parts Methyl acrylate 4.5 parts t-butyl hydroperoxide 0.15 parts n-octyl mercaptan 0.3 part

Comparative Example 3 A molded product was produced in the same manner as in Example 1 except that the amount of the emulsifier A used in the mixture (1-a) of Example 1 was changed to 0.45 part. The particle size up to the polymer of the intermediate layer at this time was 350 nm.

Comparative Example 4 A molded product was produced in the same manner as in Example 1 except that the amount of the emulsifier A used in the mixture (1-a) of Example 1 was changed to 1.8 parts. The particle size up to the polymer of the intermediate layer at this time was 160 nm.

Comparative Example 5 The mixture (1-a) of Example 1 was mixed with a mixture (7
A molded product was produced in the same manner as in Example 1 except that the procedure was changed to -a). The particle size up to the polymer of the intermediate layer at this time was 230 nm. Mixture (7-a) Methyl methacrylate 57.0 parts Methyl acrylate 3.0 parts 1,3-Butanediol dimethacrylate 1.0 parts Allyl methacrylate 0.2 parts Emulsifier A 0.9 parts

Example 6 A molded product was prepared in the same manner as in Example 1 except that all emulsifiers A used in Example 1 were changed to sodium di (2-ethylhexyl) sulfosuccinate. The particle size up to the polymer of the intermediate layer at this time was 240 nm.

[0055]

[Table 1]

[0056]

By incorporating the multi-layered structure graft copolymer of the present invention, it is possible to provide a methacrylic resin composition having excellent transparency and impact resistance as well as weather resistance and processability.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 51:00) F term (reference) 4J002 BG061 BN122 GN00 GP00 4J011 HA05 KB08 KB13 KB19 KB22 4J026 AA17 AA43 AA45 AA48 AA50 AA55 AA60 BA04 BA27 BB02 BB03 BB04 DA04 DA07 DA17 DB04 DB08 DB17 EA04 FA03 FA07 GA01

Claims (5)

[Claims] 1. An alkyl methacrylate having a carbon number of 1 to 4 of 40 to 70% by mass, an alkyl acrylate having a carbon number of 1 to 8 of an alkyl group of 30 to 60% by mass, and other copolymerizable monomers. 100 parts by mass of a monomer mixture consisting of 0 to 20% by mass, and a polyfunctional monomer of 0.1 to 1
Innermost layer polymer (A) obtained by polymerizing a mixture with 0 part by mass, and in the presence of the innermost layer polymer (A), an alkyl acrylate having an alkyl group having 1 to 8 carbon atoms 70 to 90
100 parts by mass of a monomer mixture consisting of 10% by mass to 10% to 30% by mass of an aromatic vinyl compound and 0 to 20% by mass of another copolymerizable monomer, and 0.1 to 5 parts by mass of a polyfunctional monomer. Intermediate layer polymer (B) obtained by polymerizing a mixture with
And, in the presence of the intermediate layer polymer (B), an alkyl methacrylate having a carbon number of 1 to 4 of 50 to 100% by mass, an alkyl acrylate having a carbon number of 1 to 8 of an alkyl group of 0 to 50% by mass. And an outermost layer polymer (C) obtained by polymerizing a monomer mixture consisting of 0 to 20% by mass of another copolymerizable monomer, and an intermediate layer polymer (B).
To 200-300 nm, and the mass of the outermost layer polymer (C) to the sum of the mass (a) of the innermost layer polymer (A) and the mass (b) of the intermediate layer polymer (B) (c). ) Ratio (c) / ((a) + (b)) is 0.2 to 1.0, and the innermost layer polymer (A), the intermediate layer polymer (B) and the outermost layer polymer (C). All of them are obtained by emulsion polymerization using a water-soluble inorganic polymerization initiator, and a multilayer structure graft copolymer. 2. The multi-layer structure graft copolymer according to claim 1, wherein the water-soluble inorganic polymerization initiator is at least one selected from potassium persulfate, sodium persulfate and ammonium persulfate. 3. The multi-layer structure graft copolymer according to claim 1, wherein the emulsifier used for the polymerization contains at least one kind of a phosphoric acid ester salt represented by the following general formula (I). [R ¹ -O (R ² O) _m ] _n -P (= O)-(OM) _q (1) (In the formula, R ¹ is a linear or branched alkyl group having 10 to 18 carbon atoms. R ² is a linear or branched alkylene group having 2 or 3 carbon atoms, M is an alkali metal or alkaline earth metal, m is an integer of 1 to 20, n is 1 or 2,
q is 1 or 2, and n + q is 3. ) 4. A latex obtained by emulsion polymerization is added to 0.1.
The multi-layer structure graft copolymer according to claim 1, 2 or 3, which is recovered by contacting with an aqueous solution of calcium acetate having a concentration of -20% by mass. 5. A hard methacrylic resin containing methyl methacrylate as a main component in an amount of 50 to 95% by mass,
Alternatively, a methacrylic resin composition comprising 5 to 50% by mass of the multilayer structure graft copolymer described in 4.