JPH05345812A - Production of graft copolymer - Google Patents

Abstract

PURPOSE:To produce a graft copolymer having excellent composition uniformity by the two-stage graft-copolymerization of a monomer mixture composed of a large amount of a vinyl cyanide monomer and a small amount of an aromatic vinyl compound to an acrylic acid ester rubber. CONSTITUTION:This graft copolymer is produced in high latex stability by adding (A) 23-69.5 pts.wt. of a monomer mixture consisting of 50-85wt.% of a vinyl cyanide monomer and 15-50wt.% of an aromatic vinyl monomer to (B) 30-70 pts.wt. of a rubber elastomer having rubber particle diameter of preferably 0.05-0.5mum (especially 0.1-0.35mum) and obtained by the emulsion polymerization of a monomer mixture consisting of 70-99.2wt.% of an ester of a 2-12C monohydric alcohol and acrylic acid (preferably butyl acrylate), 0-27wt.% of a vinyl monomer copolymerizable therewith and 0.08-3wt.% of a polyfunctional vinyl monomer, grafting the components by emulsion polymerization, adding 0.5-7 pts.wt. of an aromatic vinyl monomer to the polymerization system and continuing the grafting reaction by emulsion polymerization.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to a method for producing a graft copolymer having a rubber polymer as a trunk polymer. More specifically, the present invention comprises grafting a monomer mixture consisting of a high proportion of vinyl cyanide monomer and a small proportion of aromatic vinyl monomer to an acrylate rubber by emulsion polymerization. The present invention relates to a method for producing a copolymer. The graft copolymer obtained by the present invention has excellent latex stability in the latex state, and a molded article having excellent physical properties can be obtained from this copolymer.

[0002]

BACKGROUND ART Graft copolymerization is well known as one of the methods for obtaining an impact resistant resin, and it has been known that in the presence of a rubbery polymer (for example, a latex of a conjugated diene polymer).
A graft copolymer resin composition produced by polymerizing a monomer (for example, styrene + acrylonitrile) to give a resinous polymer has been praised as an impact resistant resin. Of these, polybutadiene /
Graft copolymers consisting of styrene / acrylonitrile are well known as ABS resins.

Rubber-reinforced styrene copolymers represented by ABS resins have been known as thermoplastic resins having good moldability and excellent physical properties, and have been used in electric appliances, automobiles and other parts, and housings. Widely used as a material for

In this case, a conjugated diene polymer such as polybutadiene, polyisoprene, styrene-butadiene copolymer (SBR) is widely used as the rubber elastic body. This is because the conjugated diene polymer has a double bond in the molecule, so that it is easy to crosslink, and the graft bond with the matrix (continuous phase) is easily formed. This is because an excellent rubber-modified resin of is easily obtained, but on the other hand, since these rubber-modified resins use the rubber elastic body in which the double bond remains in the molecule as described above, the weather resistance, In particular, the physical properties were remarkably deteriorated when exposed to direct sunlight, and it could not be used as a casing of equipment used outdoors.

As means for solving these problems, polybutyl acrylate and other polymers of acrylic acid ester, ethylene-propylene-non-conjugated diene terpolymer (EPDM) and other mono-olefin rubber elastic materials are used as rubber elastic materials. It has been known to use a saturated rubber elastic body such as a body having no double bond in the molecule or having a small amount. However, in these saturated rubber-modified resins, a remarkable effect is observed in improving the weather resistance, but in the case of an acrylic ester polymer, the graft reaction is carried out on the latex, but the graft reaction does not proceed sufficiently, Further, in the case of EPDM or the like, the grafting reaction is performed on the solution, but the solubility of EPDM or the like in the monomer as a solvent is poor, and it is difficult to obtain EPDM or the like in a latex state. Therefore, there was a problem in mechanical properties such as impact resistance because the particle size distribution could not be controlled sufficiently.

Further, the ABS resin is usually inferior in properties such as gas barrier property and chemical resistance, because the content of acrylonitrile component is usually smaller than that of styrene component.

In order to obtain a resin excellent in these properties, A
It is known to increase the blending ratio of acrylonitrile in the monomer mixture in the BS resin manufacturing process (see, for example, JP-A-47-5594). But,
In the method of graft-polymerizing acrylonitrile and styrene to such a conjugated diene rubber, since the reactivity ratios of the monomers are significantly different between acrylonitrile and styrene, the graft copolymer formed in the early and late stages of the polymerization The composition ratio of coalescence is different.

That is, the side chain portion of the graft copolymer graft-reacted on the conjugated diene rubber and the composition of acrylonitrile / styrene of acrylonitrile and styrene which are not grafted on the rubber by-produced during the graft copolymerization reaction are the final stage of the graft reaction. This is because a material having a remarkably high acrylonitrile component content is produced.

Therefore, the graft copolymers obtained by the conventional method have different compatibility between those which can be formed in the initial stage and those which can be formed in the latter stage of the graft reaction, and those in which the dispersibility and transparency of the rubber particles are poor. Or the thermal stability deteriorates, and when molded or exposed to a high temperature of more than 250 ° C., coloring or deterioration of fluidity due to resin burning may occur. Further, the molded article obtained from the graft copolymer may have poor weather resistance, may be colored, or may undergo intramolecular cross-linking, resulting in deterioration of appearance and physical properties.

Further, in the conventional grafting reaction by the emulsion polymerization method, since a monomer mixture consisting of a high proportion of acrylonitrile and a small proportion of styrene is used as it is for the conjugated diene rubber, the latex obtained during the polymerization is In some cases, it became unstable, and in an extreme case, the viscosity of the entire polymerization system rises or solidifies, and in some cases polymerization cannot be continued.

Even when the graft polymerization reaction can be continued until the end, the polymer mass adheres to various accessory parts in the polymerization container to reduce the yield, and the latex obtained is stored for post-treatment. Then, problems such as increase in viscosity and solidification may occur.

[Outline of the Invention]

DISCLOSURE OF THE INVENTION The inventors of the present invention have the above-mentioned problems that exist when graft-copolymerizing a monomer containing a high proportion of vinyl cyanide monomer component to a conjugated diene rubber. The present invention has been achieved as a result of intensive studies aimed at solving various drawbacks. That is, a monomer mixture consisting of a high proportion of a vinyl cyanide monomer and a small proportion of an aromatic vinyl is added to an acrylic acid ester rubber by an emulsion polymerization method, followed by a first step of graft reaction, and then a polymerization system. The second step of continuing the emulsion graft reaction by adding a small amount of an aromatic vinyl monomer, and by adopting a method for producing a graft copolymer, which comprises the stability of the latex in the polymerization system during the polymerization, the latex obtained. Storage stability, composition uniformity of the graft copolymer obtained from the latex, weather resistance as a molded product, chemical resistance, gas barrier property, impact resistance and molding processability. It is intended to provide a manufacturing method of coalescence.

<Outline>

The method for producing a graft copolymer according to the present invention comprises: an ester compound of a monohydric alcohol having 2 to 12 carbon atoms and acrylic acid; 70 to 99.2% by weight;
0 to 50 vinyl monomers copolymerizable with the acrylic ester
To 30 to 70 parts by weight (solid content) of a rubber elastic body obtained by emulsion polymerization of a monomer mixture consisting of 27% by weight and 0.08 to 3% by weight of a polyfunctional vinyl monomer, a vinyl cyanide monomer is added. 50 to 85% by weight of the body and 15 to 15 aromatic vinyl monomers
Monomer mixture (I) 23-69.5 consisting of 50% by weight
1 part by weight of the aromatic vinyl monomer (II) is added to the first step of carrying out the graft reaction by the emulsion polymerization method and the polymerization system after the first step is added. , The second step of continuing the graft reaction by the emulsion polymerization method,
It is characterized by that.

<Effect> (1) According to the method of the present invention, an acrylic acid ester rubber is emulsified with a monomer mixture consisting of a high proportion of a vinyl cyanide monomer and a small proportion of an aromatic vinyl monomer. When the graft reaction is carried out by the polymerization method, excellent latex stability is exhibited, and the polymerization process can be stably carried out. (2) The latex of the graft copolymer obtained by the method of the present invention has excellent latex storage stability. (3) The graft copolymer obtained by the method of the present invention has improved composition uniformity, so that when it is used as a molded product, it has chemical resistance, gas barrier property, decomposition coloration upon heating, and moldability. Is excellent in (4) Since the graft copolymer obtained by the method of the present invention is optimized and blended with the acrylic ester rubber as the base rubber, it has not only excellent weather resistance but also excellent impact resistance. , Can be mixed with other resins and used as an impact resistance imparting agent.

[Detailed Description of the Invention] The method for producing a graft copolymer according to the present invention comprises a first step and a subsequent second step.

<First Step> The first step in the present invention is
Acrylic ester-based rubber consisting of acrylic acid ester and vinyl monomer copolymerizable with acrylic acid ester and polyfunctional vinyl monomer, and a high proportion of vinyl cyanide monomer and a small proportion of aromatic vinyl monomer. In this step, a monomer mixture (I) consisting of a monomer is added and a graft reaction is carried out by an emulsion polymerization method. In this first step, most of the monomer mixture (I) undergoes a graft reaction with the acrylate rubber.

(A) Acrylate ester rubber In the present invention, the acrylate ester rubber has 2 carbon atoms.
To 12 monohydric alcohol and acrylic acid ester compound 70 to 99.2% by weight, vinyl monomer copolymerizable with the acrylic acid ester 0 to 27% by weight, and polyfunctional vinyl monomer 0.08 It is obtained by emulsion polymerization of a monomer mixture of 3 wt%.

Since the graft copolymerization is carried out by emulsion polymerization, this acrylic ester rubber is obtained by subjecting the latex obtained by the emulsion polymerization method to the latex as it is or after the solid content concentration, the rubber particle size and the like are adjusted. , The first step of the present invention.

As the acrylic ester used for producing the acrylic ester rubber, an ester of acrylic acid and a monohydric alcohol having 2 to 12, preferably 4 to 8 carbon atoms is suitable. is there. Specifically, butyl acrylate, 2-ethylhexyl acrylate and the like are preferable. If the carbon number is out of the above range, sufficient rubber elasticity cannot be obtained, which is not preferable. These esters may be used alone or in combination of two or more.

The vinyl monomer copolymerizable with the acrylic acid ester improves and improves the properties of the acrylic rubber obtained by copolymerization as a reinforcing rubber with respect to the graft copolymer and the graft polymerization reactivity. Those having a function are preferable. Specific examples thereof include acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, p-vinyltoluene and other vinyltoluenes, alkyl methacrylate, 2-chloroethyl vinyl ether, vinyl monochloroacetate and methoxyethyl acrylate.

As the polyfunctional vinyl monomer, that is, a monomer having a plurality of ethylenic double bonds, divinylbenzene, ethylene glycol dimethacrylate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, Examples include diallyl phthalate, trimethylolpropane triacrylate, allyl methacrylate and the like.

By using these polyfunctional vinyl monomers, intermolecular cross-linking of the acrylic ester copolymer,
Graft bonding with the matrix is facilitated, and the impact resistance of the final graft copolymer is improved.

The acrylic ester rubber used in the method of the present invention has a rubber particle diameter of 0.05 to.
It is preferably 0.50 μm, especially 0.10 to 0.35 μm.

When the rubber particle diameter is small, for example, less than 0.05 μm, the moldability (fluidity) in forming the final graft copolymer is lowered and, more importantly, the impact resistance is lowered. However, this causes deterioration of the rubber addition efficiency. On the other hand, when the rubber particle size is large, for example, more than 0.50 μm, the latex is destabilized during emulsion graft polymerization, which causes problems such as an increase in the amount of scale during polymerization, which is not preferable. ..

(B) Grafting reaction monomer The grafting monomer used in the first step is a mixture of a vinyl cyanide monomer in a high proportion and an aromatic vinyl monomer in a small proportion (a single monomer). It is a monomer (I)).

Specific examples of the vinyl cyanide monomer include:
Examples thereof include acrylonitrile, methacrylonitrile and α-chloroacrylonitrile. These may be one kind or a mixture of two or more kinds. The ratio of the vinyl cyanide monomer in the monomer mixture (I) is 50 to 85.
Must be% by weight. When it is less than 50% by weight,
It is not preferable because desired properties such as chemical resistance and gas barrier property cannot be imparted to the graft copolymer. A particularly preferable ratio is 55% by weight or more. On the other hand, if this ratio exceeds 85% by weight, properties of the resulting graft copolymer such as molding processability and coloring property upon heating are deteriorated, which is not preferable.

Specific examples of the aromatic vinyl monomer include styrene, α-alkylstyrenes such as α-methylstyrene, nuclear-substituted alkylstyrenes such as p-methylstyrene, and the like.
Examples thereof include halogenated styrene and vinylnaphthalene. These may be one kind or a mixture of two or more kinds.

Monomer mixture of aromatic vinyl monomers (I)
The proportion of them must be 10 to 50% by weight. When the ratio is out of the above range, the properties of the resulting graft copolymer are unfavorable since the properties such as desired chemical resistance, gas barrier property, moldability and colorability upon heating are deteriorated.

(C) First Stage Graft Copolymerization In the first step of the method of the present invention, 30 to 70 parts by weight of the acrylic ester rubber is added to the vinyl cyanide monomer and the aromatic vinyl monomer. 23 to 69.5 parts by weight of the monomer mixture (I) is added and a graft reaction is carried out by an emulsion polymerization method.

In the present invention, the proportion of acrylic ester rubber added should be 30 to 70 parts by weight. When the proportion of the acrylate rubber is less than 30 parts by weight, the impact resistance of the obtained graft copolymer is lowered, and it is difficult to obtain a molded article having the desired physical properties. In use, it is not preferable because the effect is small. On the other hand, if it exceeds 70 parts by weight, the graft ratio of the resulting graft copolymer becomes small, and the problems of dispersibility of rubber particles and rubber efficiency, that is, impact resistance and the like increase, which is not preferable.

The addition ratio of the monomer mixture (I) in the method of the present invention is 23 with respect to the acrylate rubber.
Must be ~ 69.5 parts by weight. If the proportion of the monomer mixture (I) is out of the above range, the physical properties of the resulting graft copolymer will change and the intended product will not be obtained.

The graft polymerization reaction in the first step of the method of the present invention is carried out by a usual emulsion polymerization method using water as a medium. At this time, the monomer mixture (I), the emulsifier, the polymerization initiator and the like can be appropriately selected, divided appropriately according to the polymerization reaction rate of the graft reaction, and added to the reaction system as the graft reaction time elapses. ..

Further, when the amount of the acrylic ester rubber is increased in the graft reaction in the first step, the graft ratio of the graft copolymer produced is lowered, and the rubber efficiency, that is, the impact resistance is lowered. There is. In such a case, it is advisable to select the graft reaction conditions that improve the graft ratio, with emphasis on the addition method and amount of the emulsifier and the addition method and amount of the molecular weight modifier.

<Second Step> In the second step of the method of the present invention, the polymerization system in which the first step has been completed is further followed by
Add 0.5 to 7 parts by weight of the aromatic vinyl monomer (II),
It consists of carrying out the grafting reaction by an emulsion polymerization method. In this second step, by adding a small amount of aromatic vinyl monomer (II) to the polymerization system, the stability of the latex during emulsion polymerization is increased and the composition uniformity of the resulting graft copolymer is improved. You can

The aromatic vinyl monomer (II) is a vinyl monomer having the same meaning as the aromatic vinyl monomer exemplified above as the constituent component of the monomer mixture (I) in the first step. The same as or different from the one used in the first step (preferably the former) can be selected.

In the second step, the amount of the aromatic vinyl monomer (II) added to the polymerization system should be selected in the range of 0.5 to 7 parts by weight. If this range is less than 0.5 part by weight, the stability and compositional uniformity of the latex cannot be obtained. On the other hand, if it exceeds 7 parts by weight, the content of the vinyl cyanide monomer component in the graft copolymer decreases, which is not preferable.

The second step in the method of the present invention is the known emulsion polymerization using water as the medium in the first step, followed by the type and amount of the emulsifier and the polymerization catalyst, the method for adding them, and the aromatic vinyl monomer (II It can be carried out by appropriately combining known emulsion polymerization conditions such as batch addition, division, addition method such as continuous method and the like.

In the method of the present invention, the acrylic ester rubber and the monomer mixture (I) added in the first step
And the total weight of the aromatic vinyl monomer (II) added in the second step must be 100 parts by weight.
The ratio of the monomer mixture (I) in the first step and the aromatic vinyl monomer (II) in the second step, that is, the monomer mixture (I) / aromatic vinyl monomer (II), 98 /
It is preferably 2 to 90/10. If this weight ratio is out of this range, the latex stability and the storage stability of the latex may decrease, or the content of the vinyl cyanide monomer component in the graft copolymer may decrease, which is not preferable. ..

The latex of the graft copolymer obtained by the method of the present invention is added to the polymerization system after the above-mentioned first step and second step by known post-treatments such as salting out, separation, washing / drying, mixing and kneading. The resin material for molding can be used by appropriately combining the steps of, volatilization, pelletization and the like.

[0040]

EXAMPLES The following examples and comparative examples are for specifically explaining the present invention. The present invention is not limited to the following examples as long as the gist thereof is not exceeded.

Example 1 (1) Production of Acrylic Ester Rubber In a 3 L glass flask, 151 parts by weight of deionized water (hereinafter simply referred to as water) and higher fatty acid soap (of fatty acid containing 18 carbon atoms as a main component) 2 parts by weight of sodium salt and 1 part by weight of sodium bicarbonate were charged, and the temperature was raised to 75 ° C. under a nitrogen stream.
After adding 0.075 parts by weight of potassium persulfate, 5 minutes later, 93.3 parts by weight of acrylic acid butyl ester (BA) and 6.2 parts by weight of acrylonitrile (AN), and methacrylic acid allyl ester (AMA) 0 4 parts by weight of a monomer mixture of 0.5 parts by weight was charged. Exothermic heat was generated in about several minutes, and the initiation of polymerization was confirmed. After 15 minutes from the charging of the first monomer mixture, 0.075 parts by weight of potassium persulfate was further added, and at the same time, the continuous addition of the remaining monomer mixture was started, and the addition was completed at 2 hours and 30 minutes. On the way 1
At the time of 30 minutes, 0.6 part by weight of fatty acid soap was added.
After the addition of the monomer mixture was completed, the polymerization was allowed to proceed for another hour at the same temperature. The conversion was 98% and the average particle size was 0.08 μm.

(2) First Step The latex of (1) above is treated with acetic anhydride to give an average particle size of 0.15.
50 parts by weight of latex (solid content) having a particle size enlarged to μm,
Alkyl diphenyl ether disulfonate sodium 2.0
5 parts by weight, 200 parts by weight of water (as the total amount of water), a stirrer, a reflux condenser, a thermometer, and an auxiliary agent addition device
The mixture was placed in a glass flask, and the internal temperature was raised to 65 ° C while stirring under a nitrogen stream.

Subsequently, an aqueous potassium persulfate solution (containing 0.09 parts by weight of potassium persulfate) was added to the flask, and 35 parts by weight of acrylonitrile, 11.7 parts by weight of styrene, and n-dodecyl were added at the same temperature. The graft reaction was started by continuously adding the monomer mixture (I) in which 2 parts by weight of mercaptan was mixed. From immediately after the reaction to 4 hours later, the monomer mixture (I) was added to the polymerization system at a constant addition rate.

Also, 30 minutes after starting the reaction, 4
Until 30 minutes later, potassium persulfate aqueous solution (0.1
It contains 7 parts by weight of potassium persulfate. ) Was continuously added to the polymerization system at a constant addition rate. After starting the reaction, 4
After a lapse of time, addition of the monomer mixture (I) was completed, and the graft reaction of the first step was completed.

(3) Second step While continuing the continuous addition of the potassium persulfate aqueous solution in the above-mentioned (2) first step, the same apparatus of the above-mentioned (2) was used as it was to immediately carry out the graft reaction of the second step. Has entered.

The polymerization system was maintained at 65 ° C. and styrene (II)
Starting the continuous addition of 3.3 parts by weight, the grafting reaction of the second step was started. Styrene (II) was added to the polymerization system at a constant addition rate from immediately after the start of the reaction in the second step until 1 hour later. Then, after starting the reaction of the second step, the reaction was continued at the same temperature until 2 hours later, and the graft reaction was completed. The solid content concentration of the obtained latex was 33% by weight.

Based on the following measuring methods, the storage stability, mechanical stability and scale amount of the latex were measured. The obtained results are as shown in Table 1.

(I) Storage stability of latex: Take latex in a 300 ml glass bottle and store at room temperature.
The number of days until coagulation was generated was measured. (Ii) Mechanical stability of latex: Latex 200
ml was taken in a commercially available household mixer, and the process of stirring for 1 minute at high speed and then standing for 2 minutes was set as one cycle, and this was repeated to measure the total stirring time (seconds) until a latex coagulates. (Iii) The graft reaction in the first step and the graft reaction in the second step are performed in the same flask, and the weight of the water-containing scale per batch of the graft reaction produced and attached to the inner wall of the flask and the stirring blade used is measured, The scale amount (g) was used. The total amount charged per batch of graft reaction was 3.
It was fixed at 8 kg.

After adding 15 g of an antioxidant to the obtained graft polymer latex, it was added to an aqueous magnesium sulfate solution heated to 95 ° C. with stirring to coagulate.
The solidified product was washed with water and dried to obtain a white powdery high rubber-containing resin composition.

The resin composition thus obtained was treated with a styrene-acrylonitrile copolymer having the same composition except rubber (AN / St weight ratio 70/30, melt flow rate 10 g / 10 min (220 ° C., 10 kg). )) And the content of the rubbery polymer in the entire composition to be 17% by weight using an extruder, and after pelletizing, each test piece was prepared by injection molding, and each physical property was obtained. Was evaluated by the following method. The results are as shown in Table 1.

(I) Izod impact strength: JIS K
7110. (Ii) Melt flow rate: Measured according to JIS K7210 under the conditions of 220 ° C. and 10 kg, and expressed as the number of g flowing out for 10 minutes. (Iii) Appearance (gloss, color tone, etc.): The test piece was visually judged. ◎: Excellent, ○: Good, △: Slightly good, ×: Bad

Example 2 (1) Production of Acrylate Ester Rubber The same as described in Example 1 (1). (2) First Step The procedure of Example (2) was the same as that of Example 1 (2), except that the composition of the monomer mixture (I) was changed as follows. Monomer mixture (I) Acrylonitrile 27.5 parts by weight Styrene 19.2 parts by weight n-dodecyl mercaptan 3.2 parts by weight (3) Second step Same as described in Example 1 (3). The solid content concentration of the obtained latex was 33% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

(1) Production of Acrylic Ester Rubber The same as described in Example 1 (1).

(2) First step Same as in Example 1 (2) except that the composition of the monomer mixture (I) and the amount of each auxiliary agent added were changed as follows. The procedure was the same as in Example (2). Monomer mixture (I) Acrylonitrile 49 parts by weight Styrene 16 parts by weight n-dodecyl mercaptan 3.2 parts by weight Auxiliary agent (1) Acrylate ester rubber 30 parts by weight Alkyl diphenyl ether disulfonic acid sodium 4 parts by weight Water 210 parts by weight Potassium persulfate (I) 0.12 parts by weight Potassium persulfate (II) 0.24 parts by weight

(3) Second step The same procedure as in Example (3) except that the continuous addition amount of styrene (II) was changed to 5 parts by weight in the example described in Example 1 (3). did. The solid content concentration of the obtained latex was 32% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

Example 4 (1) Production of Acrylic Ester Rubber The same as described in Example 1 (1). (2) First Step and Second Step In the examples described in Example 1 (2) and (3), except that the rubber particle diameter was changed to 0.30 μm, the same as in Examples (2) and (3). The procedure was similar. The solid content concentration of the obtained latex was 31% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

Comparative Example 1 (1) Production of Acrylic Ester Rubber The same as described in Example 1 (1). (2) First Step and Second Step In the examples described in Examples 1 (2) and (3), the composition of the monomer mixture (I) was changed as shown below, and the monomer mixture ( I) was added continuously for 5 hours, and styrene (II) was added.
The procedure was the same as in Examples (2) and (3), except that the continuous addition of was added.

Monomer mixture (I) Acrylonitrile 35 parts by weight Styrene 15 parts by weight n-Dodecyl mercaptan 2.3 parts by weight The solid content of the obtained latex was 33% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

Comparative Example 2 (1) Production of Acrylate Ester Rubber The same as that described in Example 1 (1). (2) First step and second step In the examples described in Example 1 (2) and (3), except that the composition of the monomer mixture (I) was changed as shown below,
The same procedure as in the example (2) was performed. Monomer mixture (I) Acrylonitrile 35 parts by weight Styrene 5 parts by weight n-dodecyl mercaptan 2.3 parts by weight (3) Second step In the example described in Example 1 (3), the continuous addition amount of styrene (II). Was changed to 10 parts by weight, and the procedure was the same as in Example (3). The solid content concentration of the obtained latex was 30% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

Comparative Example 3 (1) Production of Acrylate Ester Rubber The same as described in Example 1 (1). (2) First step The same procedure as in Example (2) except that the composition of the monomer mixture (I) in the example described in Example 1 (2) was changed as shown below. did. Monomer mixture (I) Acrylonitrile 46 parts by weight Styrene 0.7 parts by weight n-dodecyl mercaptan 3.2 parts by weight (3) Second step The same as described in Example 1 (3). The solid content concentration of the obtained latex was 33% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

Comparative Example 4 (1) Production of Acrylate Ester Rubber The same as that described in Example 1 (1). (2) First Step and Second Step In the examples described in Example 1 (2) and (3), except that the rubber particle diameter was changed to 0.65 μm, the same as in Examples (2) and (3). The procedure was similar. The solid content concentration of the obtained latex was 30% by weight. The storage stability, mechanical stability, scale amount and physical properties of the latex were measured. The results are as shown in Table 1.

[0062]

[Table 1]

From Table 1, the following is clear. (1) According to the method of the present invention, the obtained latex of the graft copolymer has excellent mechanical properties (latex stability) (see Examples 1 to 4). On the other hand, the latex of the graft copolymer not produced by the method of the present invention is inferior in mechanical stability (latex stability) (see Comparative Examples 1 to 4). (2) The latex of the graft copolymer obtained by the method of the present invention is excellent in latex storage stability (see Examples 1 to 4). (3) In the method of the present invention, the amount of scale produced during the grafting reaction is small (see Examples 1 to 4). (4) The graft copolymer obtained by the method of the present invention has an excellent balance of impact resistance and workability (see Examples 1 to 4).

[0064]

EFFECT OF THE INVENTION The vinyl cyanide monomer, which is recognized when graft-copolymerizing a monomer containing a high proportion of vinyl cyanide monomer to a conjugated diene rubber, is used as another comonomer. As described above in the section "Means for Solving the Problems", the two-stage graft copolymerization according to the present invention solves the above-mentioned problems caused by the low polymerizability.

Claims (1)

[Claims] 1. An ester compound of a monohydric alcohol having 2 to 12 carbon atoms and acrylic acid, 70 to 99.2% by weight, 0 to 27% by weight of a vinyl monomer copolymerizable with the acrylic ester, and a polyfunctional compound. Elastic body 3 obtained by emulsion polymerization of a monomer mixture consisting of 0.08 to 3% by weight of a polymerizable vinyl monomer
To 0 to 70 parts by weight, 23 to 69.5 parts by weight of a monomer mixture (I) consisting of 50 to 85% by weight of a vinyl cyanide monomer and 15 to 50% by weight of an aromatic vinyl monomer is added, First step of carrying out graft reaction by emulsion polymerization method, 0.5 to 7 parts by weight of aromatic vinyl monomer (II) is further added to the polymerization system after the above first step, and grafting is carried out by emulsion polymerization method. A method for producing a graft copolymer, comprising a second step of continuing the reaction.