JPH0639506B2 - Method for producing vinyl aromatic resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a vinyl aromatic resin composition, and more specifically, a vinyl aromatic resin composition excellent in gloss, impact resistance and heat resistance. The present invention relates to a method for producing a resin composition.

[Conventional technology and its problems] Conventionally, styrene-maleic anhydride copolymer (SMA)
Is used as various industrial materials because it has excellent heat resistance, but it is desired to improve gloss and impact resistance with the expansion of its applications.

JP-B-55-7849 discloses that butadiene rubber is dissolved in styrene to initiate copolymerization with maleic anhydride,
A method for producing a composition in which rubber particles containing a copolymer are dispersed and contained in a copolymer matrix is disclosed.

However, this method has a problem that a composition excellent in both gloss and impact resistance cannot be obtained.

On the other hand, Japanese Examined Patent Publication No. 59-13541 discloses a composition in which an MBS resin prepared by an emulsion polymerization method is mixed with SMA.

However, the impact resistance of this composition is still insufficient.

The present invention has been made based on the above circumstances.

That is, an object of the present invention is to solve the above problems and provide a method for producing a resin composition in which gloss, impact resistance and heat resistance are solved together so that there is no problem in practical use. .

[Means for Solving the Problems] The outline of the present invention for solving the problems is that a graft copolymer having a specific constitution and a vinyl aromatic monomer are mixed in a specific compounding composition. Then, an unsaturated dicarboxylic acid anhydride is mixed with this mixture, and the mixture obtained as described above is polymerized until the vinyl aromatic monomer reaches a predetermined conversion rate.

More specifically, in a method for producing a vinyl aromatic resin composition containing a rubber in a dispersed state by copolymerizing a vinyl aromatic monomer and an unsaturated dicarboxylic acid anhydride in the presence of rubber. A polymer main chain (a) containing 50% by weight or more of butadiene units as the rubber
In an amount of 50 to 85% by weight, the polymer main chain (a) was graft-polymerized with a methacrylic acid ester side chain (b) in an amount of 40 to 5% by weight, and the polymer main chain (a) was graft-polymerized. Styrene side chain (c)
In an amount of 0 to 40% by weight, and the graft copolymer having 2 to 25% by weight is mixed with 98 to 75% by weight of the vinyl aromatic monomer, and then the unsaturated dicarboxylic acid anhydride is added. A method for producing a vinyl aromatic resin composition, characterized in that the polymerization reaction is continued until the conversion rate of the vinyl aromatic monomer reaches 30 to 80% by weight.

The graft copolymer has a butadiene unit content of 50% by weight.
Included in the polymer main chain (a) the methacrylic acid ester side chain
It has (b) and a styrene side chain (c).

Since the polymer main chain (a) only needs to contain butadiene units in an amount of 50% by weight or more, the graft copolymer in the present invention may be a polymer main chain having 100% butadiene units. , And the butadiene unit is 50
It may be a polymer main chain containing not less than 50% by weight and other vinyl monomers less than 50% by weight.
If the butadiene unit content is less than 50% by weight, the impact resistance will decrease. Examples of the vinyl monomer include styrene and methacrylic acid ester.

Examples of the methacrylic acid ester as a monomer constituting the methacrylic acid ester side chain (b) include methyl methacrylate, ethyl methacrylate and the like.

There is no particular limitation on styrene as a monomer constituting the styrene side chain (c).

In the present invention, the structure of the graft copolymer is 50 wt% or more of butadiene monomer, preferably 70 wt%
The polymer main chain (a) contained in 50 to 85% by weight, preferably 65 to 80% by weight, and 40 to 40% of the methyl methacrylate side chain (b) graft-polymerized on the polymer main chain (a). 5% by weight, preferably 20 to 10% by weight, and 0% of the styrene side chain (c) graft-polymerized to the polymer main chain (a).
It is desirable to have the content of -40% by weight, preferably 0-20% by weight.

The content of the polymer main chain (a) is less than 50% by weight,
When the content of the methacrylic acid ester side chain (b) exceeds 40% by weight or the content of the styrene side chain (c) exceeds 40% by weight, the graft copolymer has a polymethacrylic acid ester or polystyrene content. The property is so large that the object of the present invention cannot be achieved. On the other hand, when the content of the polymer main chain (a) exceeds 85% by weight and the content of the polymethacrylic acid ester side chain (b) is less than 5% by weight, the properties of polybutadiene become large, The object of this invention cannot be achieved. As described above, the present invention has one advantage in using the graft copolymer having a specific structure.

Such a graft copolymer is obtained by emulsion-polymerizing butadiene according to a conventional method in the presence of a cross-linking agent such as ethylene dimethacrylate or divinylbenzene, which is added as necessary, and a methacrylic acid ester It can be obtained by adding styrene and emulsion-copolymerizing by a conventional method. The graft copolymerization may be a one-step method in which a methacrylic acid ester and styrene are simultaneously blended in a polymer latex to perform graft copolymerization, or one of the methacrylic acid ester and styrene is blended in the polymerized latex to obtain a methacrylic acid ester and It may be a multi-step method in which any one of styrene and styrene is graft-copolymerized and then the remaining monomers of methacrylic acid ester and styrene are graft-copolymerized.

Examples of the vinyl aromatic monomer include styrene,
α-methylstyrene, dimethylstyrene, diethylstyrene, vinyltoluene, isopropenylbenzene, monochlorostyrene, dichlorostyrene, vinylxylene,
Examples include ethyl vinyl xylene. Among these, styrene, α-methylstyrene and vinyltoluene are preferable.

Examples of the unsaturated dicarboxylic acid anhydrides include maleic anhydride, itaconic anhydride, oxymaleic anhydride, citraconic anhydride, phenylmaleic anhydride, aconitic anhydride, ethylmaleic anhydride, and chloromaleic anhydride. To be Among these, maleic anhydride is preferable.

In the method of the present invention, the graft copolymer, the vinyl aromatic monomer, and the unsaturated dicarboxylic acid anhydride are blended at a specific ratio, and then the conversion rate of the vinyl aromatic monomer is 30 to 30. The polymerization reaction is carried out until it reaches 80% by weight.

That is, first, 25 to 2% by weight of the graft copolymer,
Preferably 15 to 5% by weight and the vinyl aromatic monomer 7
5 to 98% by weight, preferably 80 to 95% by weight, are mixed, and an unsaturated dicarboxylic acid anhydride is further added to carry out the polymerization reaction.

If the blending amount of the graft copolymer is more than 25% by weight, the vinyl aromatic resin composition having sufficient heat resistance cannot be obtained even by the production method of the present invention, and the graft copolymer does not exist. If the blending amount is less than 2% by weight, a vinyl aromatic resin composition having sufficient impact resistance cannot be obtained.

Further, when the conversion rate of the vinyl aromatic monomer is less than 30% by weight, the productivity is lowered, and when the conversion rate exceeds 80% by weight, the viscosity of the system becomes high and the reaction becomes nonuniform. The physical properties of the composition deteriorate.

The above-mentioned mixing and polymerization reaction may be carried out in one reaction tank or a multi-stage continuous process in which a plurality of tanks are arranged in series.
Or the latter process of three stages is preferred. The polymerization tank to be used may be an ordinary polymerization tank, particularly a perfect mixing type is suitable, and further, for example, a double helical blade and a Crawford Russell blade are preferable.

When such a multi-stage continuous process, particularly a two-stage continuous process is adopted, 25 to 2% by weight of the graft copolymer and 75 to 98% by weight of the vinyl aromatic monomer are first added to the first polymerization tank of the first stage. It is charged and mixed by stirring, and then, unsaturated dicarboxylic acid anhydride is added to the first polymerization tank so that the conversion of the added vinyl aromatic monomer is 15 to 40% by weight.
The polymerization reaction is carried out until Then, the entire amount of the polymerization reaction product was transferred from the first polymerization tank to the second polymerization tank of the second stage, and further, the unsaturated dicarboxylic acid anhydride was charged into this second polymerization tank to obtain the vinyl aromatic monomer. Conversion rate of 40-80% by weight
It is preferable to carry out the polymerization reaction until

In this two-stage continuous process, the polymerization reaction may be carried out by either bulk polymerization or solution polymerization, but bulk polymerization is preferred from the viewpoint of eliminating the need for solvent recovery and separation.

The polymerization is usually 50 to 200 ° C., preferably 60 to 18
It is carried out at a temperature of 0 ° C.

In starting the polymerization reaction, for example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, t-
Butyl peroxybenzoate, dicumyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, diisopropyl peroxydicarbonate, t-butyl peroxypivalate, stearoyl peroxide, azobissisobutyronitrile, 1,1- Bis- (t-butylperoxy) -1,
3,5-trimethylcyclohexane, 1,1-bis-
(T-butylperoxyoctane), n-butyl-4,
4-bis- (t-butylperoxy) valerate, 2,
2-bis- (t-butylperoxy) butane, di-t-
A polymerization initiator such as butyldiperoxyisophthalate or 2,5-dimethyl-di (benzoylperoxy) hexane may be added.

After the completion of the polymerization reaction, the polymerization reaction product is usually transferred from the polymerization tank to the degassing tank, and unreacted vinyl aromatic monomer is recovered by degassing, and when the solvent is used, the solvent is also recovered. Then, a vinyl aromatic resin composition is obtained.

The resulting vinyl aromatic resin composition was compounded as a rubber in a copolymer of a vinyl aromatic monomer and an unsaturated dicarboxylic acid anhydride, for example, a copolymer of styrene and maleic anhydride (SMA). It is presumed that the composition has the graft copolymer dispersed therein, but in some cases, it may be possible that SMA is further grafted to the blended graft copolymer. In any case, in the vinyl aromatic resin composition obtained by the method of the present invention, the graft copolymer contains 10 to 35% by weight, particularly 15 to 30% by weight.
% By weight, 70-98 mol% styrene monomer units, especially 72-95 mol%, 2-30 maleic anhydride units.
Mol%, especially 5-28 mol% SMA 65-90
A vinyl aromatic resin composition containing 50% by weight, particularly 70 to 85% by weight, is preferable in terms of gloss, impact resistance, heat resistance and the like.

By the above, it is possible to obtain a vinyl aromatic resin composition having excellent gloss, impact resistance, heat resistance and the like, but in order to obtain a vinyl aromatic resin composition having further improved impact resistance, , The following general formula (In the formula, R ¹ and R ² represent an alkyl group, an aryl group or an aralkyl group.) It is preferable to add an organic polysiloxane having a repeating unit represented by the following formula.

The organic polysiloxane may be a homopolymer type organic polysiloxane having one kind of repeating unit, or a random type, block type or graft type copolymerizing organic polysiloxane having a combination of two or more kinds of repeating units. It may be siloxane. Further, in the present invention, a part of the organic groups of these organic polysiloxanes may be substituted with a hydroxyl group, an alkoxy group, a hydroxyalkyl group or a polyhydroxyalkylene group. These organic polysiloxanes may be used not only as one kind but also as a mixture of two or more kinds.

Examples of the organic polysiloxane include dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and the like.
Dimethylpolysiloxane is preferred. The viscosity of this organic polysiloxane is not particularly limited, but usually 10 to 100,
000 cSt (30 ° C), preferably 30 to 2000 cS
t (30 ° C.). Here, the viscosity at 30 ° C. is 10
Those having a viscosity of less than cSt have a high volatility, so that the molded product tends to have a poor appearance and has a viscosity at 30 ° C.
It is not preferable that the amount exceeds 100,000 cSt because it is difficult to uniformly mix with the vinyl aromatic resin composition.

The amount of the organic polysiloxane compounded is usually 1 part by weight or less, preferably 0.02 to 0.2 part by weight, based on 100 parts by weight of the vinyl aromatic resin composition. This organic polysiloxane may be added in advance during the polymerization, or may be added after the completion of the polymerization.

In the method of the present invention, additives such as hindered phenol-based and phosphorus-based antioxidants and flame retardants may be added before and after the polymerization.

The vinyl aromatic resin composition produced by the method of the present invention is excellent in gloss, impact resistance, heat resistance and the like, and thus is suitable for home electric appliances and automobile interior and exterior products by extrusion molding, injection molding, etc. It is also a useful resin composition which is suitably used in a wide range of fields such as food field, medical field, daily necessities field, etc.

[Effects of the Invention] According to the present invention, a graft copolymer having a specific constitution, a vinyl aromatic monomer, and an unsaturated dicarboxylic acid anhydride are compounded in a specific compounding composition in a specific compounding order. Since the polymerization reaction is carried out from the above, it is possible to produce a vinyl aromatic resin composition having excellent gloss, impact resistance and heat resistance.

[Examples] Next, examples and comparative examples of the present invention will be described.

(Examples 1 to 3) As shown in FIG. 1, a volume 1.
The first polymerization tank 1 of 8 and the second polymerization tank 2 having a capacity of 2.3, which is also equipped with double helical blades, are arranged in series and are connected to each other by a transfer pipe, and in front of the first polymerization tank 1. The rubber mixing tank 3 was arranged in the above and was mutually connected.

In this rubber mixing tank 3, 89.95% by weight of styrene and 10% by weight of powder of MBS resin (trade name "METABRENE C-223" manufactured by Mitsubishi Rayon Co., Ltd.) as a graft copolymer.
And 0.05% by weight of silicone oil, and the mixture is mixed with 1
The first polymerization tank 1 is supplied at a flow rate of
While supplying maleic anhydride at the flow rate shown in the table, 105
Polymerization reaction was carried out by heating to ˜135 ° C. until the conversion rate of styrene in the first polymerization tank 1 became the conversion rate shown in Table 1. Then, the reaction product liquid in the first polymerization tank 1 is directly transferred into the second polymerization tank 2 and at the same time, the first
By supplying maleic anhydride at the flow rate shown in the table, 135-1
While heating to 55 ° C, the styrene in the second polymerization tank 2 was the first
The polymerization reaction was carried out until the conversion rate shown in the table was reached.

After the polymerization reaction, the reaction product liquid discharged from the second polymerization tank 2 was passed through the degassing tank 4 to remove unreacted substances from the line 5, and subsequently, extruded from the vented extruder 6 to obtain pellets. The pellet was injection-molded to prepare a test piece.

For each test piece, the melt index, gloss, Izod impact strength, and heat distortion temperature were measured according to the following specifications. The results are shown in Table 1.

Gloss: Conforms to JIS K 7015 Izod Impact strength: Conforms to JIS K 7110 (with notch) Heat distortion temperature: Conforms to JIS K 7207 (Load 18.5Kg
/ cm ² , temperature rising rate 2 ° C / min) (Examples 4 to 8) The same procedure as in Examples 1 to 3 was performed except that silicone oil was not mixed during polymerization and degassed after polymerization. . The results are shown in Table 1.

(Examples 9 and 10) The same procedure as in Example 4 was carried out except that no silcon oil was used. The results are shown in Table 1.

(Comparative Examples 1 to 3) Polybutadiene (made by Asahi Kasei Co., Ltd., trade name "Asaprene 700A") styrene solution viscosity 3 instead of MBS resin
The same procedure as in Example 1 was performed except that 5 cp) was used. The results are shown in Table 1.

(Comparative Examples 4 and 5) The same procedure as in Example 1 was performed except that the amount of MBS resin was changed. The results are shown in Table 1.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a two-stage continuous process as an example for carrying out the method of the present invention. 1 ... 1st polymerization tank, 2 ... 2nd polymerization tank, 3 ... rubber mixing tank, 4 ... deaeration tank.

Claims (1)

[Claims] 1. A method for producing a vinyl aromatic resin composition containing a rubber in a dispersed state by copolymerizing a vinyl aromatic monomer and an unsaturated dicarboxylic acid anhydride in the presence of rubber. A polymer main chain (a) containing 50% by weight or more of butadiene units as the rubber
In an amount of 50 to 85% by weight, the methacrylic acid ester side chain (b) graft-polymerized to the polymer main chain (a) is 40 to 5% by weight, and the polymer main chain (a) is graft-polymerized. Styrene side chain (c)
In an amount of 0 to 40% by weight, and the graft copolymer having 2 to 25% by weight is mixed with 98 to 75% by weight of the vinyl aromatic monomer, and then the unsaturated dicarboxylic acid anhydride is added. A method for producing a vinyl aromatic resin composition, characterized in that the polymerization reaction is continued until the conversion rate of the vinyl aromatic monomer reaches 30 to 80% by weight.