JP2790522B2 - Method for producing graft copolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is highly excellent in weather resistance, impact resistance and secondary workability, and is formed by pressure forming or vacuum forming a molded product obtained by molding. The present invention relates to a method for producing a specific graft copolymer used for preparing a vinyl chloride-based illustrated composition which can be uniformly and highly stretched.

[Prior Art] As is generally known, a vinyl chloride resin molded article is inferior in impact resistance. Many methods have been proposed to improve this impact resistance. Above all, MBS resins obtained by graft polymerization of methyl methacrylate, styrene or acrylonitrile to a butadiene rubber-like polymer are widely used at present.

However, when MBS resin is used in combination with a vinyl chloride resin, the impact resistance is improved but the weather resistance is poor, and when the manufactured molded article is used outdoors, the impact resistance is significantly reduced. is there. Therefore, the use of MBS resins is currently limited.

It is considered that the main cause of the decrease in weather resistance is due to ultraviolet degradation of butadiene units contained in the MBS resin. In order to improve the weather resistance of the MBS resin and impart impact resistance, a crosslinked alkyl acrylate rubbery polymer comprising an alkyl acrylate containing no double bond and a crosslinking agent, methyl methacrylate, an aromatic vinyl compound, A method of graft-polymerizing an unsaturated nitrile has been proposed (JP-B-51-28117).

When the graft copolymer obtained by this method is used, the molded article produced has excellent weather resistance, and has recently been used in earnest in fields requiring long-term weather resistance such as window frames.

The use of the graft copolymer according to this method is satisfactory in terms of the weather resistance of the molded article to be produced, but it is necessary to reheat the molded plate, which is generally called secondary workability, simultaneously with the impact resistance. It is still insufficient to satisfy the moldability and workability during rework.

The importance of the secondary workability has been increasing for the following reasons.

For example, large signboards, large televisions, display housings, etc. were conventionally molded in large quantities by the injection molding method. And the production of many varieties in small quantities is increasing.

Under such circumstances, the cost of the injection molding method is high because the cost of the mold is high, and the cost has been reduced.

Therefore, in recent years, for such applications, a molded plate is obtained by molding a vinyl chloride-based resin composition comprising a vinyl chloride-based resin and a weather resistance enhancer by a calendering method or an extrusion molding method, and then forming the molded sheet again at 150 to There is an increasing number of processing methods for obtaining a desired molded product by heating to about 200 ° C. and performing pressure forming or vacuum forming.

When a composition using a weathering enhancer made by a conventional technique is applied to such a molding method, 150
Since the elongation at -200 ° C. (elongation under high temperature) is insufficient, the corners of the molded article do not become acute angles, or the thickness of the molded article becomes uneven, so that a uniform molded article cannot be obtained. Therefore, the use of weathering enhancers for these applications is limited.

That is, in the composition according to the conventionally disclosed technology, the formability and workability (secondary processing method) when the formed plate obtained as described above is reheated and reworked are not sufficient, This is because demands for those satisfying such characteristics are increasing.

[Problems to be Solved by the Invention] In a graft copolymer using a crosslinked rubber polymer mainly composed of an alkyl acrylate, when the graft copolymer is used for a vinyl chloride resin composition, a molding obtained is obtained. When the use ratio of the crosslinked rubber polymer is increased in order to improve the impact resistance of the molded article, the molded article is reduced to a pressure such as pressure molding.
When subjected to the next processing, the elongation at high temperature becomes insufficient, resulting in thinning and uneven thickness, resulting in insufficient so-called secondary workability.

The present invention solves the problem of secondary workability resulting from increasing the use ratio of the crosslinked rubber polymer as described above,
The purpose of the present invention is to provide a graft polymer which can exhibit high impact resistance to a molded article of a vinyl chloride resin composition and which has excellent weather resistance.

[Means for Solving the Problems] The present invention relates to an alkyl acrylate having an alkyl group having 2 to 8 carbon atoms in an amount of 79.9 to 99.9% (% by weight, hereinafter the same), a polyfunctional monomer.
0.1 to 5% and other monomers 0 to 2 copolymerizable therewith
0 to 100 parts of a crosslinked rubber polymer (parts by weight, hereinafter the same), 50 to 100% of methyl methacrylate, alkyl methacrylate having an alkyl group having 2 to 4 carbon atoms.
~ 50% and other monomers copolymerizable therewith
A branch monomer component of 30% is polymerized from 60 to 25 parts to a total amount of 100 parts, and a 0.2 g / 100 cc acetone solution of a component extracted with methyl ethyl ketone from the obtained graft copolymer is added to 30 parts. Η _sp determined by measuring at 100 ° C. and the obtained number of crosslinked rubber polymer parts (A) in 100 parts of the graft copolymer are represented by the following formula (1): η _sp / C> (A) / 80 (1) (Where C is the g of the component dissolved in 100 cc of acetone)
Number, that is, 0.2), and the ratio (%) in the graft copolymer of the component separated as an insoluble matter in the extraction with methyl ethyl ketone and the ratio (%) of the crosslinked rubber polymer in the graft copolymer. Is the formula (2): ｛(Ratio of insoluble content in graft copolymer (%)) / (Ratio of crosslinked rubber polymer in graft copolymer (%)) −
1)> 0.1 A method for producing a graft copolymer satisfying the relationship of (2).

[Examples] The crosslinked rubber polymer used in the present invention has an alkyl acrylate having 2 to 8 carbon atoms of 79.9 to 99.9%,
Using 0.1 to 5%, preferably 0.5 to 5%, more preferably 1 to 4% of a polyfunctional monomer and 0 to 20% of another monomer copolymerizable therewith, for example, a usual emulsifying weight Manufactured legally.

The alkyl acrylate having 2 to 8 carbon atoms in the alkyl group has excellent weather resistance and is a component used for forming an impact resistance improving rubber component. Specific examples thereof include:
For example, ethyl acrylate, propyl allylate,
Butyl acrylate, 2-ethylhexyl acrylate and the like are exemplified as typical ones. These may be used alone or in combination.

The polyfunctional monomer is a component used as a crosslinking agent. Specific examples thereof include aromatic polyfunctional vinyl compounds such as divinylbenzene, monoethylene glycol dimethacrylate, and 1,3-butanediol dimethacrylate. Polyhydric alcohols such as dimethacrylate or trimethacrylate or diacrylate or triacrylate, allyl acrylate,
Typical examples thereof include allyl esters of unsaturated carboxylic acids such as allyl methacrylate, diallyl compounds such as diallyl phthalate and triallyl isocyanurate, and triallyl compounds. Among these polyfunctional crosslinking agents, those in which the reactivity of at least one of the functional groups is different from the reactivity of the other functional groups can obtain a crosslinked rubber polymer with a small amount of the polyfunctional monomer. Therefore, it is preferable.

The alkyl acrylate used in the production of the crosslinked rubber polymer and the monomer copolymerizable with the polyfunctional monomer include, as specific examples, an alkyl acrylate having an alkyl group other than 2 to 8 carbon atoms. , Other acrylic esters, acrylic acid, metal salts of acrylic acid,
Examples include acrylamide, alkyl methacrylate, methacrylic acid, metal salts of methacrylic acid, methacrylamide, aromatic vinyl compounds, derivatives thereof, acrylonitrile, methacrylonitrile, vinyl ester compounds, and vinyl halides. These may be used alone,
You may use together.

When the proportion of the alkyl acrylate in producing the crosslinked rubber polymer is less than 79.9%, impact resistance or weather discoloration becomes a problem, and when it exceeds 99.9%, the proportion of the polyfunctional monomer becomes too small, Cannot be sufficiently obtained. When the ratio of the polyfunctional monomer exceeds 5%, when a vinyl chloride resin composition containing a graft copolymer produced from the crosslinked rubber polymer is molded, the impact resistance is reduced. Is undesirably reduced.

The average particle size of the crosslinked rubber polymer produced in this manner is preferably large from the viewpoint of improving impact resistance, practically 1500 ° or more, and preferably 17 ° C or more.
Desirably, it is not less than 00 °. There are various methods for obtaining the average particle diameter of such a crosslinked rubber polymer, and there is no particular limitation.However, the one having an average particle diameter of about 1000 mm, which is usually easily produced, is usually prepared before graft polymerization. The coagulation and enlargement may be performed by the method described above. However, it is more preferable to obtain a crosslinked rubber polymer having an average particle diameter of 1500 ° C. or more by a usual seed polymerization method, since the ratio of small particles that hardly contribute to impact resistance decreases.

In the present invention, the crosslinked rubber polymer may contain an alkyl methacrylate having 50 to 100%, preferably 70 to 100% of methyl methacrylate, and an alkyl group having 2 to 4 carbon atoms.
The branch monomer component consisting of .about.50%, preferably 0-30% and other monomers copolymerizable therewith, is graft-polymerized.

The branch monomer component is a component used to increase the degree of improvement in impact resistance and secondary workability, and it is important that the branch monomer component be a component that is compatible with the vinyl chloride resin. As a typical component compatible with the vinyl chloride resin, methyl methacrylate is well known, and it is essential to use methyl methacrylate in the present invention.

On the other hand, the alkyl methacrylate in which the alkyl group has 2 to 4 carbon atoms is a component used for improving the dispersibility of the graft copolymer without lowering excellent compatibility with methyl methacrylate, and specific examples thereof. Examples thereof include ethyl methacrylate, butyl methacrylate, and propyl methacrylate.

Further, other monomer components copolymerizable with methyl methacrylate and the like used as the branch monomer include, in particular, methyl acrylate, ethyl acrylate, alkyl acrylate such as butyl acrylate, styrene, acrylonitrile, and the like. The monomer component selected from the above is preferable because the effect of developing impact resistance and secondary workability is high without impairing the excellent compatibility of methyl methacrylate.

When the amount of methyl methacrylate in the branch monomer component is less than 50%, a decrease in secondary workability is observed,
Not preferred.

The graft copolymer according to the present invention is a crosslinked rubber polymer 40.
To 75 parts, preferably 45 to 65 parts, and branch monomer 60 to 25 parts.
Parts, preferably 55 to 35 parts, in a total amount of 100 parts. When the amount of the crosslinked rubber polymer is 40
If the amount is less than 5 parts, the effect of improving the impact resistance becomes inferior when a molded article is produced by preparing a vinyl chloride resin composition, and the method becomes impractical. The improvement effect is not sufficient.

At the time of graft polymerization, the whole amount of the branch monomer component may be added at once, and the polymerization may be performed, or the whole amount or a part thereof may be continuously or intermittently added for polymerization. In order to increase the degree of polymerization, it is preferable to add the whole or a part of the branch monomer component at a time in the presence of a small amount of a catalyst and proceed with the polymerization.
Further, all of the branch monomer components may be used as a mixture, or two or more stages may be prepared such that each of them has a different composition within the composition range of the branch monomer components. May be polymerized.

The thus obtained graft copolymer latex is subjected to spray drying, salting out or aciding out, and after heat treatment, is filtered, washed and dried.

An antioxidant or an ultraviolet absorber usually added at the time of coagulation may be added.

In addition, in the presence of a crosslinked rubber polymer latex, a part of the branch monomer is added and polymerized to obtain a latex, and the remaining branch monomer is emulsified in a system without a crosslinked rubber polymer. The latex obtained by polymerization may be mixed in a latex state, coagulated, dehydrated, and dried to obtain a graft copolymer according to the present invention.

In addition, after adding a part of the branch monomer in the presence of the crosslinked rubber polymer latex and polymerizing, the powder obtained by coagulation, dehydration, and drying, and the remaining powder in a system without a crosslinked rubber polymer are left. And a powder obtained by polymerizing the above branch monomer may be mixed in a powder state to obtain a graft copolymer according to the present invention.

In the present invention, the degree of polymerization of the branch polymer (hereinafter, also referred to as a graft branch) in the graft copolymer is increased, that is, 0.2 g / 100 cc of acetone extracted from the graft copolymer by methyl ethyl ketone. 30 ° C of the solution
The η _sp determined from the viscosity at is expressed by the following formula (1): η _sp / C> (A) / 80 (1) (where C is the g of the component dissolved in 100 cc of acetone)
Number, ie, 0.2, (A) The number of crosslinked rubber polymer parts in the obtained graft copolymer, ie, the graft copolymer
(Representing the number of crosslinked rubber polymers in 100 parts) in order to maintain good secondary workability and improve the impact resistance by increasing the use ratio of the crosslinked rubber polymer. Required above. When η _sp / C does not satisfy the formula (1), the degree of polymerization of the graft branch becomes low,
Sufficient secondary workability cannot be obtained, and elongation at high temperatures decreases.

The η _sp / C of the methyl ethyl ketone extraction component is given by the formula (1)
The mixture may be a range that satisfies the condition, and may be a mixture of components having different molecular weight distributions.

Further, in the present invention, when the obtained graft copolymer is extracted with methyl ethyl ketone, the ratio (%) in the graft copolymer of the component separated as insoluble by methyl ethyl ketone extraction and the crosslinking in the graft copolymer The ratio (%) of the rubber polymer is represented by the formula (2): ｛(Ratio of insoluble content in graft copolymer (%)) / (Ratio of crosslinked rubber polymer in graft copolymer (%)) -1｝> 0.1 (2) must be satisfied, and in this case, both the high-temperature elongation and the strength are good.

The ratio (%) of the insoluble matter in the graft copolymer in the above formula (2) is the number of parts of the precipitate obtained by dissolving 100 parts of the graft copolymer in methyl ethyl ketone and centrifuging. The ratio (%) of the crosslinked rubber polymer in the graft copolymer refers to the number of parts of the crosslinked rubber polymer used when polymerizing 100 parts of the graft copolymer.

The graft copolymer according to the present invention as described above is formed from a crosslinked rubber polymer mainly composed of an alkyl acrylate and a specific branch monomer component containing an alkyl methacrylate as a main component. The degree of polymerization (the degree of polymerization of the methyl ethyl ketone extract) of the graft branch) and the ratio of the insoluble portion of the methyl ethyl ketone extract are adjusted so as to satisfy the relationship of the formulas (1) and (2). Further, the ratio of the crosslinked rubber polymer contained in the graft copolymer is 40 to 75%.
As a result, the impact resistance of a molded article made of a vinyl chloride resin composition can be kept high, and at the same time, the secondary workability of the molded article can be greatly improved. Becomes

By mixing the obtained graft copolymer with a vinyl chloride resin, it is possible to maintain high weather resistance and impact resistance when forming a molded product, and at the same time, to greatly improve the secondary workability of the molded product. A vinyl chloride resin-based composition is obtained.

In addition, the vinyl chloride resin referred to in this specification is a concept including a vinyl chloride homopolymer, a copolymer containing 70% or more of vinyl chloride, and a derivative of a vinyl chloride resin such as chlorinated polyvinyl chloride. is there.

The amount of the graft copolymer mixed with the vinyl chloride resin varies depending on the application, but is generally 10 to 30 parts of the graft copolymer per 100 parts of the vinyl chloride resin. If the amount is less than 10 parts, sufficient strength, secondary workability cannot be obtained,
If the amount exceeds 30 parts, a reduction in the tensile strength of the molded product becomes a problem. Next, the method of the present invention will be described based on examples.

Example 1 (A) Production of seed used for production of crosslinked rubber polymer The following was charged into a glass reactor having a thermometer, a stirrer, a reflux condenser, a nitrogen inlet device, and a monomer addition device. It is.

Distilled water 250 parts Potassium rosinate 0.5 〃 Potassium stearate 0.5 ナ ト リ ウ ム Sodium formaldehyde sulfoxylate (SFS)
0.1 〃 Na ₃ PO ₄・ 12H ₂ O 0.45 〃 EDTA ・ 2Na 0.008〃 Ferrous sulfate heptahydrate 0.002〃 Then, heat to 40 ° C with stirring in a nitrogen stream, and 100 parts of butyl acrylate, allyl Methacrylate
If 2.0 parts and 0.1 part of cumene hydroperoxide were used, 5% of the monomer mixture solution was charged. Then, the remaining 95% monomer mixed solution was added dropwise over 4 hours. After the addition
After 1.5 hours, polymerization was carried out to complete the polymerization.

The yield of the obtained polymer was 97%, and the average particle diameter of the obtained latex was 900 °.

(B) Production of Crosslinked Rubber Polymer Seed polymerization was performed using the latex obtained in (A) as a seed.

Latex obtained from 250 parts of distilled water (as solid) (as solid content) 10 〃 SFS 0.1 〃 EDTA ・ 2Na 0.008 第 Ferrous sulfate heptahydrate 0.002 を The mixture having the above composition was charged into a glass reactor and heated at 40 ° C. , A monomer mixture consisting of 90 parts of butyl acrylate, 2 parts of allyl methacrylate and 0.1 part of cumene hydroperoxide was continuously added over 4 hours. Simultaneously with the addition of the monomer mixture, 1 part of a 5% aqueous solution of potassium stearate was continuously added over 4 hours. After the addition was completed, 0.05 parts of SFS was added, and polymerization was carried out for 5 hours to obtain a crosslinked rubber polymer latex.

The conversion of the monomer mixture was 98%, and the average particle size of the obtained latex was 2000 °.

(C) Production of graft copolymer Raw materials were charged into a glass reactor so as to have the following composition,
The oxygen concentration of the aqueous dispersion is 0.5 ppm under nitrogen flow at 45 ° C.
The mixture was heated and stirred until the temperature became below.

Crosslinked rubber polymer latex obtained as (B) (as solid content) 55 parts SFS 0.05 〃 EDTA 2Na 0.01 第 Ferrous sulfate heptahydrate 0.005 〃 Then, the following branched monomer component is continuously used for 3 hours Was added.

Methyl methacrylate 40 parts Butyl acrylate 5 〃 Cumene hydroperoxide 0.04 後 After addition, cumene hydroperoxide 0.01
Then, stirring was continued for 2 hours to complete the polymerization. The conversion was 99.7%.

The obtained graft copolymer latex is salted out, dehydrated,
By drying, the intended graft copolymer was obtained.

Η _sp / C and the graft ratio of the components extracted from the obtained graft copolymer with methyl ethyl ketone were determined by the methods described below. The results are shown in Table 1.

(Η _sp / C) After immersing the graft copolymer in methyl ethyl ketone at 30 ° C for 24 hours, the soluble components are separated by centrifugation, purified by reprecipitation with methanol, and dried.
Measure the viscosity at 30 ° C with 0.2 g / 100 cc acetone solution, η
_{Issue sp} . C is the g of the extracted component dissolved in 100 cc of solvent
Number, in this case 0.2.

(Graft ratio) The graft copolymer is immersed in methyl ethyl ketone at 30 ° C for 24 hours, and then the insoluble matter and the soluble matter are separated by centrifugation. Ratio (%) of the insoluble component in the graft copolymer and ratio (%) of the crosslinked rubber polymer contained in the graft copolymer
Then, the graft ratio is calculated according to the following equation.

Graft ratio = (Ratio of insoluble content in graft copolymer (%)) / (Ratio of crosslinked rubber polymer in graft copolymer (%))-1 The obtained graft copolymer was mixed with the following compound. The mixture was blended according to Formulation 1, roll-kneaded at 180 ° C. for 8 minutes, and compression-molded with a hot press at 190 ° C. for 15 minutes, and the Izod impact strength at 0 ° C. and the elongation at high temperature were measured by the following methods. First result
It is shown in the table.

(Formulation 1) Vinyl chloride resin (= 800) 100 parts Graft copolymer 20 ブ チ ル Butyltin mercapto stabilizer 3 ブ チ ル Butyl stearate 1 ポ リ Polyglycol ester of fatty acid 0.5〃 (Izod impact strength) ASTM D 256-56 Based on the above, the strength (kg · cm / cm ² ) of a sample having a V notch at 0 ° C. and a thickness of 3 mm was measured.

(Elongation at High Temperature) A 3 mm thick plate obtained by a roll press was cut to produce a JIS No. 2 dumbbell. This dumbbell is JIS K6745 1
It was pulled at 80 ° C., and the elongation at break (%) was measured.

Examples 2 to 4 By changing the number of parts of the crosslinked rubber polymer used in (C) of Example 1 and the number of parts of the initiator system (SFS, cumene hydroperoxide) used during the graft polymerization, the methyl ethyl ketone soluble component was changed. A graft copolymer was obtained in the same manner as in Example 1 except that η _sp / C was changed.

In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 1.

Comparative Examples 1 to 5 Same as Example 1 except that in (C) of Example 1, the number of parts of the crosslinked rubber polymer and the number of parts of the initiator system were changed to change η _sp / C of the methyl ethyl ketone-soluble component. Thus, a graft copolymer was obtained.

In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 1.

According to the results in Table 1, the graft ratio exceeds 0.1 and η
_sp / C and the number of crosslinked rubber polymer parts in the graft copolymer (A)
Satisfies the relationship of the formula (1), and the graft copolymer containing at least 40 parts of the crosslinked rubber polymer has excellent Izod impact strength and elongation at high temperature (Examples 1 to 4).

On the other hand, when η _sp / C does not satisfy the relationship of equation (1), it can be seen that the high-temperature elongation is significantly reduced (Comparative Examples 1 to 3).

In addition, when the graft ratio is 0.1 or less, the elongation at high temperature is low (Comparative Example 4).

Furthermore, when the crosslinked rubber polymer is less than 40 parts, the Izod impact strength is significantly reduced (Comparative Example 5).

Examples 5 to 7 The same operation as in Example 1 was carried out except that the branch monomer component in (C) of Example 1 was changed as shown in Table 2, to obtain a graft copolymer.

In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 2.

Further, (A) / 80 of all the obtained graft copolymers was 0.69.

MMA in Table 2 is methyl methacrylate, B
MA is butyl methacrylate, BA is butyl acrylate,
AN represents acrylonitrile.

Comparative Examples 6 to 8 A graft copolymer was obtained in the same manner as in Example 1 except that the branch monomer component in (C) of Example 1 was changed as shown in Table 2.

In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 2.

Further, (A) / 80 of all the obtained graft copolymers was 0.69.

From the results shown in Table 2, when the composition of the branch monomer component is within the composition range in the present invention, the molded article exhibits excellent high-temperature elongation, but the methyl methacrylate in the branch monomer component has a high elongation. When the ratio is less than 50% (Comparative Examples 6 and 8) and even when the ratio of methyl methacrylate is 50% or more, the ratio of the monomer other than methyl methacrylate and the alkyl methacrylate having 2 to 4 carbon atoms is increased. When it exceeds 30% (Comparative Example 7), it is understood that the elongation at high temperature decreases.

Example 8 (D) Production of a copolymer consisting of only a branch monomer 200 parts of distilled water, 2.0 parts of potassium stearate, and 0.1 part of potassium persulfate were charged into a glass reactor and heated at 70 ° C.
Then, 100 parts of a monomer mixture (88.9 parts of methyl methacrylate, 11.1 parts of butyl acrylate) having the same composition as the branch monomer used in (C) of Example 1 were continuously added over 5 hours. did. After completion of the addition, stirring was continued for 2 hours to obtain a copolymer latex (L-1) consisting only of a branch monomer.

After coagulating and drying the obtained latex, 0.2g / 100
η _sp / C determined by preparing a cc acetone solution was 1.0.

(E) Production of graft copolymer Latex of copolymer obtained in Comparative Example 1 and (D)
The copolymer latex (L-1) obtained from only the branch monomer obtained in the above was mixed in a latex state so as to have a ratio of 3: 1 in terms of solid content, and then coagulated and dried to obtain a final product. A graft copolymer was obtained.

The η _sp / C of the methyl ethyl ketone-soluble component of the obtained graft copolymer was 0.95.

In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 3.

Comparative Example 9 (F) Production of Copolymer from Branch Monomer Only In the copolymerization of only the branch monomer of Example 8 (D), tertiary decyl mercaptan was added to the monomer mixture.
The same operation as in (D) of Example 8 was performed, except that 0.5 part was added, to obtain a copolymer latex (L-2). After coagulating and drying the obtained latex, 0.2 g / 100 cc acetone solution was prepared, and η _Ps / C was 0.2.

(G) Production of graft copolymer Example 8 (E) of Example 8 except that latex (L-2) was used instead of latex (L-1).
The same operation as (E) was performed to obtain the final graft copolymer.

The η _sp / C of the methyl ethyl ketone soluble component of the final graft copolymer obtained was 0.3. In the same manner as in Example 1, the graft copolymer was evaluated, and the physical properties of the molded article were measured. The results are shown in Table 3.

Example 9 Instead of mixing, coagulating and drying in the latex state performed in (E) of Example 8, each latex was separately coagulated and dried, and mixed in a powder state.
The final graft copolymer was obtained.

The η _sp / C of the methyl ethyl ketone soluble component of the obtained graft copolymer was 0.95. In the same manner as in Example 1, the graft copolymer was evaluated and the physical properties of the molded product were measured. The results are shown in Table 3.

From the results in Table 3, it was found that a part of the branch monomer was separately polymerized in a system without the crosslinked rubber polymer and the remaining branch monomer was polymerized in the presence of the crosslinked rubber polymer. The final graft copolymer may be produced by mixing the obtained graft copolymer portion in a latex state to produce a final graft copolymer (Example 8), or by mixing in a powder state to produce a final graft copolymer. It can also be seen from Example 9 that a graft copolymer having the desired properties was obtained.

[Effect of the Invention] When the graft copolymer obtained by the method of the present invention is used, a vinyl chloride resin composition which gives a molded article having excellent weather resistance, impact resistance and secondary workability can be obtained.

Claims (4)

(57) [Claims] 1. An alkyl acrylate having an alkyl group having 2 to 8 carbon atoms, 79.9 to 99.9% by weight, a polyfunctional monomer 0.1
To 5% by weight and other monomers copolymerizable therewith
For 40 to 75 parts by weight of a crosslinked rubber polymer composed of 20% by weight,
A branch monomer comprising 50 to 100% by weight of methyl methacrylate, 0 to 50% by weight of an alkyl methacrylate having an alkyl group having 2 to 4 carbon atoms and 0 to 30% by weight of another monomer copolymerizable therewith; Ingredient 60 to 25 parts by weight, total amount is 10
Polymerized to 0 parts by weight, η _sp determined by measuring a 0.2 g / 100 cc acetone solution of a component extracted with methyl ethyl ketone from the obtained graft copolymer at 30 ° C., and η _sp of the graft copolymer. The number of crosslinked rubber polymer parts (A) used for the polymerization of 100 parts by weight is represented by the following formula (1): η _sp / C> (A) / 80 (1) (where C is dissolved in 100 cc of acetone) Ingredient g
Number, that is, 0.2), and the ratio (%) in the graft copolymer of the component separated as an insoluble matter in the extraction with methyl ethyl ketone and the ratio (%) of the crosslinked rubber polymer in the graft copolymer. Is represented by the following formula (2): {(Ratio of insoluble content in graft copolymer (%)) / (Ratio of crosslinked rubber polymer in graft copolymer (%))-1}> 0.1 (2) A method for producing a graft copolymer satisfying the relationship. 2. In the presence of a crosslinked rubber polymer latex,
The method according to claim 1, wherein after the branching monomer is added and polymerized, coagulation, dehydration and drying are performed. 3. In the presence of a latex of a crosslinked rubber polymer,
A latex obtained by adding and polymerizing a part of the branch monomer and a latex obtained by emulsion-polymerizing the remaining branch monomer in a system without a crosslinked rubber polymer are in a latex state. 2. The method according to claim 1, wherein the mixture is subjected to coagulation, dehydration and drying. 4. In the presence of a latex of a crosslinked rubber polymer,
After adding and polymerizing a part of the branch monomer, the solidified, dehydrated, and dried powder, and the powder obtained by polymerizing the remaining branch monomer in a system without a crosslinked rubber polymer, 2. The method according to claim 1, wherein the compound is mixed in a powder state.