JPH0660275B2 - Impact-resistant thermoplastic resin composition having good translucency and plating properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel impact-resistant thermoplastic resin composition which is excellent in translucency and can be mixed.

In recent years, in fields such as audio parts and automobile front panels, switches that use a display method to illuminate characters and figures from the inside using LED lamps have been adopted so that the operating status of functions can be more clearly confirmed. Has been done. It is preferable to use a thermoplastic resin for such a material from the viewpoint of design freedom, but it is indispensable to give a matte for the purpose of giving a metallic feeling in addition to the translucency.

Conventionally, double-molded products such as translucent polystyrene and ABS resin with excellent mating properties were used for such products, but this product has been diversified because it requires a special mold. However, there is a problem that the molding operation is complicated, and that the defective interface between the polystyrene and the ABS resin causes defective plating. Further, although the conventional ABS resin has an excellent mating property, it has a poor light-transmitting property. Therefore, it has been desired to develop an impact-resistant thermoplastic resin which is capable of solving these problems at once and which has excellent translucency and can be mixed.

On the other hand, transparent ABS resin is known as a special grade of ABS resin (US Pat. Nos. 2,843,561 and 302,922).
No. 3 specification and Japanese Patent Publication No. 35-4889). However, these resins use an MMA monomer for the purpose of matching the refractive indexes of the rubber and the matrix resin, and have poor mating properties, and therefore cannot be used for the above-mentioned applications.

Therefore, an object of the present invention is to provide an impact-resistant thermoplastic resin composition which has excellent translucency and can be mixed.

The present inventors, as a result of detailed examination of the particle size of the rubber to be used and the crosslinked structure as well as the graft polymerization conditions,
The present invention has been completed by finding that an impact-resistant thermoplastic resin excellent in translucency and plating properties can be obtained when these are in a specific range.

The present invention relates to synthetic rubber (A) latex 15-65 having a gel content of 60% or more and an average particle size of 0.04-0.1μ, which is obtained from 50-100% by weight of 1,3-butadiene and 0-50% by weight of styrene. 35 to 85 parts by weight of a monomer mixture (B) for graft polymerization, which comprises 60 to 90% by weight of an aromatic vinyl monomer and 10 to 40% by weight of a vinyl cyanide monomer, based on parts by weight (as solid content). The total amount of (B) is 100 parts by weight]
Graft copolymer (I) having a graft ratio of 80% (based on synthetic rubber), and aromatic vinyl monomer 60 to 9
0% by weight and 10 to 40% by weight of vinyl cyanide monomer
In the resin composition comprising the copolymer (II) obtained from (1), the synthetic rubber (A) in the entire composition is 5 to 30% by weight, and the impact-resistant thermoplastic resin has good light-transmitting property and mating property. It is a resin composition.

In the present invention, the gel content of the synthetic rubber (A) and the graft ratio of the graft copolymer (I) are defined as follows.

Gel content: A certain amount of coagulated and dried rubber is weighed (W ₀ ) and left in 50 times volume of toluene at 30 ° C. for 48 hours. The toluene-insoluble agglomerated rubber is separated, dried and weighed (W ₁ ). The gel content is shown by the following formula.

Graft ratio: A fixed amount of the aggregated and dried graft rubber was weighed (W ₀ ),
Reflux for 2 hours at 60 ° C. in 50 volumes of acetone. The acetone-insoluble graft rubber is separated by centrifugation, dried, and weighed (W ₁ ). When the content of the synthetic rubber (A) in the graft rubber is A%, the graft ratio is calculated by the following formula.

The synthetic rubber (A) in the present invention is 1,3-butadiene 50-
It is composed of 100% by weight and 0-50% by weight of styrene, has a gel content of 60% or more and 0.04-0.
It has an average particle size of 1μ. These synthetic rubbers can be usually produced by known emulsion polymerization. If the particle size exceeds 0.1 μm, the light-transmitting property is remarkably reduced, and if the particle size is less than 0.04 μm, the impact strength decreases, which is not preferable. Further, if the gel content is less than 60%, the rubber is likely to be deformed at the time of molding and the surface gloss is deteriorated.

In the graft polymerization, the amount of the monomer mixture (B) for graft polymerization is 35 to 85 parts by weight, preferably 40 to 70 parts by weight, relative to 15 to 65 parts by weight, preferably 30 to 60 parts by weight of the synthetic rubber (A). used. 1 synthetic rubber (A)
When it is less than 5 parts by weight, productivity is poor and not practical, and when it exceeds 65 parts by weight, the graft copolymer (I) is melt-mixed with the aromatic vinyl monomer-vinyl cyanide monomer copolymer (II). In the resin composition obtained in this way, the graft copolymer (I) may be dispersed while partially agglomerated, and the molded appearance, light-transmitting property, and plating property may deteriorate.

The monomer mixture (B) for graft polymerization is a mixture of an aromatic vinyl monomer and a vinyl cyanide monomer, and the aromatic vinyl monomer is 60 to 90% by weight, preferably 65 to
It is used for graft polymerization in a mixing ratio of 80% by weight and 10 to 40% by weight, and preferably 20 to 35% by weight of vinyl cyanide monomer. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, and alkyl nucleus-substituted styrene, with styrene being preferred. Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred. When the graft polymerization is carried out at a mixing ratio of the vinyl cyanide monomer of more than 40% by weight, a vinyl cyanide homopolymer is produced during the graft copolymerization, which causes coloring of the obtained composition and also the vinyl cyanide monomer. Is 10
It is not preferable to carry out the graft polymerization at a mixing ratio of less than wt% because the composition will have poor plating properties.

In the emulsion graft polymerization, generally known emulsifiers, initiators and chain transfer agents are used. The monomer mixture (B) for graft polymerization may be added to the rubber latex at once, or may be added dividedly or continuously. The type of emulsifier, initiator, chain transfer agent, etc., the amount to be added, and the method of adding the monomer are selected so that the graft ratio of the resulting graft copolymer (I) is 20 to 80%. When the graft ratio is less than 20%, when the graft copolymer (I) is melt-mixed with the aromatic vinyl monomer-vinyl cyanide monomer copolymer (II), the rubber particles are likely to aggregate, and the particle size is Agglomerated rubber having a size of 0.1 μm or more is produced, and the surface appearance, translucency and plating properties are remarkably deteriorated, and when the graft ratio exceeds 80%, the impact strength is deteriorated.
Therefore, the graft ratio of the graft copolymer (I) is 20 to 80.
It is necessary to control in the range of%.

The aromatic vinyl monomer-vinyl cyanide monomer copolymer (II) comprises 60 to 90% by weight of aromatic vinyl monomer, preferably 65 to 80% by weight and 10 to 40% by weight of vinyl cyanide monomer, preferably 20 to 35%. It is a copolymer obtained by polymerizing wt%. Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, and alkyl nucleus-substituted styrene, with styrene being preferred.
Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile, with acrylonitrile being preferred. Similar to the case of the monomer mixture for graft polymerization, if the amount of the vinyl cyanide monomer exceeds 40% by weight, coloring tends to occur, and if it is less than 20% by weight, the matting property is deteriorated, which is not preferable. This aromatic vinyl monomer
The polymerization method of the vinyl cyanide monomer copolymer (II) is not particularly limited, and a known bulk polymerization method, suspension polymerization method or emulsion polymerization method may be used.

Thus obtained graft copolymer (I) and aromatic vinyl monomer-vinyl cyanide monomer copolymer (II),
By blending the synthetic rubber (A) in an amount of 5 to 30% by weight based on the total composition, the impact-resistant thermoplastic resin composition of the present invention having excellent light-transmitting property and excellent mating property is obtained. To be If the content of the synthetic rubber (A) in this resin composition is less than 5% by weight, it is not of practical value because the slickness is lowered and the impact resistance is also low. And the fluidity and workability are deteriorated. The graft copolymer (I) may be used alone or in the form of two or more graft copolymers (I) in which the gel content and particle size of the rubber, the type and amount of the grafting monomer, the graft ratio, etc. are within the above specified ranges. ) Can be used as a mixture. The aromatic vinyl monomer-vinyl cyanide monomer copolymer (II) may also be used in combination of two or more kinds.

In order to blend the graft copolymer (I) and the aromatic vinyl monomer-vinyl cyanide monomer copolymer (II), when the copolymer (II) is produced by emulsion polymerization, both are in an emulsion state. It is possible to mix. In addition, both can be used as powder, or by combining powder with beads, pellets, etc., a Hensiel mixer, extruder,
It is also possible to knead and blend using various equipment such as a Banbury mixer and a heating roll.

The resin composition of the present invention, if necessary, an antioxidant, a lubricant,
Customary auxiliaries such as fillers can be added.

The thermoplastic resin composition of the present invention is superior to conventionally known thermoplastic resin compositions in particular because of the following advantages.

(1) While the conventional transparent ABS resin does not have good mating properties, it has a significantly improved translucency while maintaining the same excellent matting properties as ordinary ABS resins.

(2) In the case of double-molded products of polystyrene and ABS resin, which are conventionally used for molding optical display switches having a metallic appearance, the molding cost is high because the molding die is complicated and the molding operation is complicated. While it is not possible to respond to diversification, it is possible to reduce molding processing cost and respond to diversification of design.

Parts and% in the following examples mean parts by weight and% by weight, respectively. Impact strength is ASTM D-256, optical properties are AS
According to TM-D-1003-61, a sample having a plate thickness of 1.5 mm was measured using an integrating sphere haze maker manufactured by Nippon Seimitsu Optics. The molding appearance and the plating characteristics were measured by the following methods.

Molding appearance: Using a 5 ounce screen type injection molding machine, a flat plate having a plate thickness of 3 mm was molded under the conditions of a cylinder temperature of 250 ° C. and a mold temperature of 60 ° C., and the color tone, gloss, and texture were observed.

Plating characteristics: Using a flat plate sample for molding appearance judgment, after applying electrolytic copper plating with a film thickness of about 35μ, the surface appearance was observed and the plating film was 3
Adhesion strength was measured by peeling in a perpendicular direction at a speed of 0 mm / min.

Example 1 Synthesis of Synthetic Rubber (A-1) 1,3-Butadiene 75 parts Styrene 25 parts 1,3-Butylenedimethacrylate 0.5 parts Potassium oleate 1.0 part Disproportionated potassium rosinate 1.0 part Diisopropylbenzene peroxide 0.2 parts Ferrous sulfate 0.005 parts Sodium pyrophosphate 0.5 parts Dextrose 0.3 parts Water 200 parts According to the above composition, using 100 autoclave, 50
Polymerization was carried out at ° C. Polymerization was almost completed in 9 hours, and a rubber latex having a conversion rate of 98%, a particle diameter of 0.078μ and a gel content of 99% was obtained.

Synthesis of graft copolymer (G-1) Rubber latex (A-1) 30 parts (as solid content) Styrene 49 parts Acrylonitrile 21 parts Disproportionated potassium rosinate 1/0 part Cumene hydroperoxide 0.35 part Ferrous sulfate 0.01 part Sodium pyrophosphate 0.2 part Dextrose 0.35 part t-dodecyl mercaptan 0.7 part Water 200 parts (including water in rubber latex) Using rubber latex (A-1), a graft copolymer was synthesized according to the above composition. The polymerization temperature is 70 ° C. and the polymerization time is 4 hours. Cumene hydroperoxide and t-dodecyl mercaptan were mixed and dissolved in styrene and acrylonitrile, and this was added dropwise to the rubber latex (A-1) over 2 hours. The polymerization rate was 97.2% and the graft rate was 51%. To the obtained polymer latex, 2 parts of butylated hydroxytoluene and 0.5 part of dilauryl thiopropionate were added as antioxidants, coagulated with a 5% aqueous solution of sulfuric acid, washed and dried to obtain a white powder.

Synthesis of styrene-acrylonitrile copolymer (M-1) Styrene 70 parts Acrylonitrile 30 parts Calcium phosphate 1.0 part Gafferk GB520 0.003 parts (Toho Chemical Co., Ltd. dispersion aid) Lauryl peroxide 0.6 parts t-dodecyl mercaptan 0.5 parts Water 200 parts A styrene-acrylonitrile copolymer was synthesized according to the above composition. The polymerization temperature is 80 ° C. and the polymerization time is 6 hours. The polymerization rate was 98%.

Production of Resin Composition and Evaluation of Physical Properties 50 parts of the above-mentioned graft copolymer (G-1) and styrene-
50 parts of acrylonitrile copolymer (M-1) was mixed with a Henschel mixer at 3000 rpm for 5 minutes to make the content of the synthetic rubber (A-1) in the entire composition 15%, and pelletized by an extruder (cylinder. Temperature 230 ° C). Using this pellet, various test pieces were prepared by injection molding, and various physical properties were evaluated. The results are shown in Table 3.

Comparative Example 1 50 parts of the above-mentioned graft copolymer (G-1), styrene-
35 parts of acrylonitrile copolymer (M-1) and polymer
Chillmethacrylate (Acrypet VH, Mitsubishi Rayon
(Manufactured) and blended 15 parts, and test pieces in the same manner as in Example 1.
Was molded and various physical properties were evaluated. The results are shown in Table 3.
You This resin composition had poor mating properties.

Comparative Example 2 Synthesis of Styrene-Acrylonitrile-Methyl Methacrylate Copolymer (M-2) Styrene 50 parts Acrylonitrile 20 parts Methyl methacrylate 30 parts Calcium phosphate 1.0 part Gafferk GB520 0.003 parts (Toho Chemical Co., Ltd. dispersion aid) Lauryl peroxide 0.6 part t-dodecyl mercaptan 0.5 part Water 200 parts A styrene-acrylonitrile-methyl methacrylate copolymer was synthesized according to the above composition. Polymerization temperature is 80 ℃,
The polymerization time is 6 hours. The polymerization rate was 96.4%.

50 parts of the above-mentioned graft copolymer (G-1) and styrene-
Acrylonitrile-methyl methacrylate copolymer (M-
2) 50 parts were mixed and evaluated in the same manner as in Example 1. The results are shown in Table 3. This resin composition also had poor plating property as in Comparative Example 1.

Examples 2 to 5 and Comparative Examples 3 to 4 Synthetic rubbers (A-2 to A-) according to the polymerization conditions shown in Table 1.
5 and B-1 to B-2), and using the obtained synthetic rubber, the graft copolymers (G-2 to G-5 and H-1 to H-) under the same conditions as in Example 1 respectively. 2) was produced.

Table 1 shows the polymerization rate, average particle size, gel content, and polymerization rate and grafting rate of the graft copolymer of the obtained synthetic rubber. The resin composition containing each graft copolymer was evaluated in the same manner as in Example 1, and the result was evaluated as 3rd.
Shown in the table.

Comparative Example 5 Synthesis of Synthetic Rubber (B-3) 1,3-Butadiene 75 parts Styrene 25 parts Potassium oleate 0.5 parts Disproportionated potassium rosinate 0.5 parts Potassium persulfate 0.3 parts Dodecyl mercaptan 0.4 parts Water 50 parts The mixture was charged into a 100 autoclave and polymerization was started at 60 ° C. with stirring at 80 rpm. Polymerization conversion rate is 30
%, The stirring speed is increased to 140 rpm,
When the polymerization conversion rate exceeded 50%, the stirring speed was reduced to 100 rpm, and a mixture of 1.0 part of potassium oleate, 1.0 part of disproportionated potassium rosinate and 15 parts of water was continuously added to the polymerization system. The polymerization was completed in 45 hours, and the polymerization conversion rate was 97.5.
%, A particle size of 0.28μ, and a gel content of 85% were obtained.

Using this synthetic rubber (B-3), a graft copolymer (H-3) was produced under the same conditions as in Example 1. Polymerization rate is 9
The graft ratio was 7.3% and the graft ratio was 51%. (See Table 1).

Table 1 shows the polymerization rates of the synthetic rubber (B-3) and the graft copolymer (H-3). Further, the graft copolymer (H-
The properties of the resin composition containing 3) are shown in Table 3.

Examples 6 to 8 and Comparative Examples 6 to 7 Using the synthetic rubber (A-2) obtained in the same manner as in Example 2, the graft copolymer (G-6 was used under the polymerization conditions shown in Table 2.
~ G-8, H-4 and H-5) were synthesized. The polymerization rate and the graft rate of the obtained graft copolymer are shown in Table 2. A styrene-acrylonitrile copolymer (M-, obtained in the same manner as in Example 1 was added to these graft copolymers.
The content of synthetic rubber (A-2) in 1) is 15%.
Were blended at the compounding ratio shown in Table 3. The properties of each resin composition are shown in Table 3.

Example 9 α-Methylstyrene-acrylonitrile copolymer (M-
Synthesis of 3) α-methylstyrene 70 parts Acrylonitrile 30 parts Potassium oleate 2.0 parts Cumene hydroperoxide 0.5 parts Ferrous sulfate 0.01 parts Sodium pyrophosphate 0.2 parts Dextrose 0.35 parts t-Dodecyl mercaptan 0.5 parts Water 250 parts The above composition According to the above, an α-methylstyrene-acrylonitrile copolymer (M-3) was synthesized. Polymerization temperature is 65 ℃,
The polymerization time is 4 hours. Acrylonitrile was added dropwise in 2.5 hours. The polymerization rate was 94%.

Α-methylstyrene-acrylonitrile copolymer (M-3) was used in place of the styrene-acrylonitrile copolymer (M-1), and otherwise the same as in Example 1,
The properties of the resin composition were evaluated. The results are shown in Table 3.

Examples 10-11 and Comparative Examples 8-9 The graft copolymer (G-7) used in Example 7 was blended with the styrene-acrylonitrile copolymer (M-1) at the compounding ratio shown in Table 3. . The results of evaluating the properties of these resin compositions in the same manner as in Example 1 are shown in Table 3.

Comparative Examples 10 to 11 The procedure of Example 1 was repeated except that the styrene / acrylonitrile copolymer (M-1) had a styrene / acrylonitrile weight ratio of 90/10 or 55/45 (M-4). Alternatively, M-5) was synthesized and blended with the graft copolymer (G-1). The results obtained are shown in Table 3.

The symbols in Table 3 have the following meanings.

St Styrene AN Acrylonitrile PMMA Polymethylmethacrylate Evaluation of molding appearance and matte surface appearance: ◎ Very good 〇 Good △ Fair Somewhat bad × Poor Evaluation of gluing adhesion strength: ◎ 1.5kg / cm or more 〇 1.0 to 1.5kg / cm △ 0.5-1.0kg / cm × 0-0.5kg / cm

Claims (1)

[Claims] 1. A gel content of 60% obtained from 50-100% by weight of 1,3-butadiene and 0-50% by weight of styrene.
The aromatic vinyl monomer (60 to 90% by weight) and the vinyl cyanide monomer (10) to 15 to 65 parts by weight (as solid content) of the synthetic rubber (A) latex having the above average particle diameter of 0.04 to 0.1 μm. 35 to 85 parts by weight of a monomer mixture (B) consisting of ˜40% by weight [(A) and (B)]
The total amount of 100 parts by weight] of the graft copolymer (I) having a graft ratio of 20 to 80% (based on the synthetic rubber), 60 to 90% by weight of an aromatic vinyl monomer, and Vinyl cyanide monomer 10-4
In the resin composition comprising the copolymer (II) obtained from 0% by weight, the synthetic rubber (A) in the entire composition is 5 to 30%.
And a resin composition.