JPH0617428B2 - Method for producing thermoplastic resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a light transmissive resin which can be plated, and an object of the invention is to industrially advantageously produce an ABS resin having good plating adhesion strength. It is what

[Conventional technology]

Resin-plated products are lightweight and have excellent decorative properties and corrosion resistance.
It is used in many fields such as office automation equipment. Especially ABS
The resin has a very strong adhesion to the plated metal,
It is used in various fields as a composite material having both metal and resin properties.

Particularly in resin-plated products that use light-transmitting and plateable ABS resin, the non-plated part is light-transmitting, and therefore changes in transmitted light intensity and transmitted light color may occur. It has an information display function as a signal. For example, the function state can be displayed by converting the shape of the non-plated portion into a signal.

By the way, as a technique for imparting light transmittance to the ABS resin, there are known techniques of i) matching the refractive indexes of the dispersed phase and the continuous phase, and ii) reducing the particle diameter of the dispersed phase. Copolymerization of methyl methacrylate in the continuous phase is generally performed, but it is known that the presence of an alkoxycarbonyl group in the continuous phase lowers the plating adhesion strength. Adhesion strength decreases. That is AB
One of the factors that makes S resin excellent in plating adhesion is that the diene rubber particles, which are the dispersed phase, are oxidized and eluted by etching with a mixed solution of concentrated chromic acid and sulfuric acid, and the plated metal enters into the resulting depressions and anchors the effect. It is known that a holding effect of the plating metal called "effect" occurs, but when diene rubber particles with a small particle size are used to impart light transparency, the anchor effect decreases and the plating adhesion Strength is reduced.

As described above, the light-transmissive resin-plated product has a drawback that it is inferior in the plating adhesion strength, though it is extremely useful industrially, which has been a serious obstacle in practical use.

[Problems to be solved by the invention]

An object of the present invention is to solve the practical problem that the plating adhesion strength is insufficient for an ABS resin-plated product using small diene rubber particles.

[Means for solving problems]

The inventors of the present invention have 100 parts by weight (as solid content) of a diene rubber latex having a weight average particle diameter of 120 mμ or less.
When emulsion polymerization is carried out by adding 60 to 900 parts by weight of a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of 10% by weight to 9% by weight of the monomer mixture.
0% by weight was added all at once to the diene rubber latex to start the polymerization, and the remaining monomer mixture was continuously added at the start of the polymerization of the batch-added monomers, during the polymerization or after the completion of the polymerization. A thermoplastic resin characterized by being polymerized, wherein the thermoplastic resin is light-transmissive, and it has been found that it is possible to produce a resin-plated product having excellent plating adhesion strength. It was completed.

The ABS resin according to the present invention can be obtained by emulsion-polymerizing a monomer mixture containing a vinyl cyanide monomer and an aromatic vinyl monomer in the presence of a diene rubber latex having a specified particle size. The diene rubbers mentioned here are polybutadiene, polyisoprene, polychloroprene, poly (butadiene-styrene), poly (butadiene-methylmethacrylate), poly (butadiene-acrylonitrile) and the like. The aromatic vinyl monomer is styrene, α-methylstyrene, t-butylstyrene, vinyltoluene, or the like. The vinyl cyanide monomer is acrylonitrile, methacrylonitrile or the like. The amount of the aromatic vinyl monomer used is 40 to 100% by weight, preferably 50 to 85% by weight of the total monomer mixture, and the amount of the vinyl cyanide monomer used is the entire monomer mixture. It is preferably 0 to 50% by weight, more preferably 10 to 45% by weight. If the amounts of the aromatic vinyl monomer and vinyl cyanide monomer deviate from the above ranges, the moldability and impact resistance may be poor. In some cases, a copolymerizable monomer can be copolymerized with the monomer. Examples of such monomers include (meth) acrylic acid ester monomers such as methyl methacrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, hydroxyethyl acrylate, and glycidyl (meth) acrylate, (meth ) There are unsaturated carboxylic acid monomers such as acrylic acid and itaconic acid, and fatty acid vinyl monomers such as vinyl acetate and vinyl decanoate, and the amount thereof is preferably 0 to 20% by weight of the total monomer mixture. .

The diene rubber of the ABS resin of the present invention is required to have a weight average particle diameter of 120 mμ or less, and preferably 100 mμ or less. Weight average particle size is 12
An ABS resin containing a diene rubber exceeding 0 mμ is not suitable for the purpose of the present invention because of its poor light transmittance.

The light-transmitting ABS resin of the present invention contains diene rubber in an amount of 10 to 10.
It is preferable to contain 24% by weight. If it is less than 10% by weight, the plating adhesion strength is poor, and if it exceeds 24% by weight, the fluidity is lowered, which is not preferable.

In the present invention, a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer, which is added and copolymerized in the presence of 100 parts by weight of diene rubber latex (as a solid content), is 60 To 900 parts by weight, preferably 60 to 3
It should be 100 parts by weight. When the amount of the monomer mixture is less than 60 parts by weight, silver streaks are generated on the surface of the molded product to deteriorate the surface condition, and when it exceeds 900 parts by weight, the plating adhesion strength is deteriorated.

When emulsion polymerization is carried out by further adding these monomer mixtures, 10% by weight to 90% by weight of the monomer mixtures are added all at once to the diene rubber latex to start the polymerization,
The remaining monomer mixture must be continuously added and polymerized at the beginning of the polymerization of the batch-added monomers, during the polymerization or after the completion of the polymerization. In the ABS resin obtained by adding a part of the monomer mixture and initiating the polymerization in this way, the diene rubber particles are appropriately aggregated, and the plating adhesion strength is maintained while maintaining the light transmittance. Will be improved. The monomer mixture added all at once into the diene rubber latex is
It is 10% to 90% by weight, preferably 10% to 50% by weight of the total monomer mixture. When the amount is less than 10% by weight, the diene rubber particles are not aggregated and the plating adhesion strength is not improved. On the other hand, if it exceeds 90% by weight, a silver streak is generated on the surface of the molded product, and the surface condition after plating becomes poor.

Further, the remaining monomer needs to be continuously added and polymerized at the start of the polymerization of the batch-added monomer, during the polymerization, or after the completion of the polymerization.

The light transmissive ABS resin according to the present invention can be produced by any emulsion polymerization method.

Further, a glassy resin separately polymerized can be added to the graft polymer produced by the present invention. The glassy resin can be produced by known techniques such as bulk polymerization, emulsion polymerization, suspension polymerization and solution polymerization. Here, the glassy resin and the graph copolymer do not have to have the same monomer composition. Specific examples of the glassy resin include poly (acrylonitrile-styrene), poly (acrylonitrile-methylmethacrylate styrene), poly (methacrylonitrile-styrene), poly (acrylonitrile-styrene-α-methylstyrene), poly (acrylonitrile-styrene). (Acrylonitrile-α-methylstyrene), poly (methacrylonitrile-acrylonitrile-α-methylstyrene), poly (styrene-N-phenylmaleimide-acrylonitrile), poly (styrene-N-phenylmaleimide), poly (α-methylstyrene- N-phenylmaleimide-acrylonitrile) and the like.

The light-transmitting ABS resin produced according to the present invention is not affected by the precipitation method.

Any additive known in the art can be used as the additive, and particularly by adding alcohol or phenol, the plating adhesion strength is improved.

〔Example〕

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition,
All parts and percentages mentioned herein are on a weight basis.

Example 1 280 parts of pure water in an autoclave, weight average particle diameter of 60 m
100 parts of small particle size poly (butadiene) latex of μ (as solid content), 1.0 part of potassium stearate, 0.0075 part of ferrous sulfate, tetrasodium ethylenediaminetetraacetate
0.015 parts and 0.45 parts of sodium formaldehyde sulfoxylate were added and heated to 50 ° C. with stirring. 30% of the total liquid mixture containing 45 parts of acrylonitrile, 105 parts of styrene, 1.0 part of t-dodecyl mercaptan and 0.3 part of diisopropylbenzene hydroperoxide.
Was added all at once to start the polymerization. Two hours after the initiation of the polymerization (92% polymerization rate of the batch-added monomer), the remaining mixed solution (70% of the entire mixed solution) was continuously added over 3 hours. After the addition was completed, 0.1 part of diisopropylbenzene hydroperoxide was further added, and the mixture was stirred at 70 ° C. for 2 hours to complete the polymerization. The yield was 98%.

An aqueous calcium chloride solution was added to the obtained polymer latex to recover the graft polymer.

45 parts of this graft polymer was added to an acrylonitrile-styrene suspension copolymer AS resin (acrylonitrile content 25
%) And 0.5 part of octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and mixed into an extruder to form pellets. This pellet was measured according to JIS K6870 (measurement 250
The melt flow index was measured according to a temperature of 5 ° C and a load of 5 kg) and was found to be 18.0 g / 10 minutes. The heat distortion temperature was measured according to the method according to ASTM D-648.
It was ℃.

The pellets were injection-molded at a molding temperature of 240 ° C. by an IS80CN-V injection molding machine manufactured by Toshiba Machine Co., Ltd. to obtain a flat plate-shaped molded product of 80 × 50 × 3 mm. The total light transmittance of this molded product was 63.5%. The total light transmittance was measured according to ASTM D-1003. The characters "PLAY" were screen-printed on one side of the center of this molded product with a vinyl chloride resin-based masking ink, and the vicinity of the corresponding region on the back side was widely covered with the same masking ink, and then wet plating was performed according to the following steps. The characters "PLAY" could be clearly read by the transmitted light in the obtained plated product.

"Wet plating process" Degreasing (isopropyl alcohol); room temperature x 5 seconds Etching (chromic anhydride-sulfuric acid mixture); 70 ° C x 1
5 minutes Neutralization (hydrochloric acid); room temperature x 2 minutes Catalyzing (palladium chloride-stannous chloride-
Hydrochloric acid aqueous solution); room temperature x 2 minutes Accelerating (sulfuric acid aqueous solution); 55 ° C x 2 minutes Chemical plating (nickel sulfate-sodium citrate-sodium hypophosphite-sodium acetate-ammonium chloride solution);
32 ° C x 5 minutes Electro copper plating; (20μ thickness) Electro nickel plating; (7μ thickness) Chromium plating; (0.3μ thickness) Also, a resin-plated plate that is wet-plated without masking the flat molded article is used. After being left in an environment of 85 ° C. for 2 hours, it was immediately left in an atmosphere of −20 ° C. for 2 hours.
A transparent plate having 5 mm grids written thereon was applied to the resin-plated plate after the heating / cooling cycle was performed, and the number of grids from which the plating group was peeled off was counted. The front and back of the resin-plated plate were measured, and the number of peeled grids was totaled to obtain the “plating peeling number”. The number of stripped plating of the sample was 12. Since the size of the resin-plated plate is 80 × 50 × 3 mm, the maximum peeling number is 320.

Example 2 and Comparative Example 1 Same as Example 1 except that the total weight of the monomer mixture added to 100 parts by weight of polybutadiene latex (as solid content) in Example 1 was changed as shown in Table 1. Was graft-polymerized to obtain a polymer.

The polymer was processed into pellets in the same manner as in Example 1,
A molded product was obtained. The total light transmittance of the molded product is summarized in Table 1. When the molded product was partially plated in the same manner as in Example 1, the characters "PLAY" could be clearly read by the transmitted light except for Comparative Example 1.

The number of peeled platings of the resin-plated plate obtained from the molded product was measured and summarized in Table 1.

Further, the presence or absence of the silver streak on the flat plate was visually judged and shown in Table 1.

Example 3 and Comparative Example 2 Table 2 shows the polymerization ratios of the monomer mixture liquid (collective monomer) which was added all at once and polymerization was started in Example 1 and the residual monomer (continuous monomer). The same treatments and evaluations as in Example 1 were carried out except that The results are summarized in Table 2.

Example 4 When mixing the graft polymer and the AS resin in Example 1, 2 parts of stearyl alcohol was added to 100 parts of the resin. The results are shown in Table 2.

Example 5 and Comparative Example 3 The same treatment and evaluation as in Example 1 were carried out except that the weight average particle diameter of the polybuene latex in Example 1 was changed as shown in Table 3. The results are summarized in Table 3.

Example 6 In Example 1, the addition timing of the remaining mixed solution was changed as shown in Table 4, and the addition was continued for 3 hours. Others were treated in the same manner as in Example 1 to complete the polymerization. The obtained polymer latex was treated in the same manner as in Example 1 to evaluate the physical properties, and the results are summarized in Table 4.

Example 7 Instead of the small particle size poly (butadiene) latex in Example 1, poly (styrene-) having a weight average particle size of 120 mμ was used.
(Butadiene) (styrene content 25%), except that the polymerization was conducted in the same manner as in Example 1 and the physical properties were evaluated. As a result, the total light transmittance was 68.2% and the number of stripped plating was 22.
No silver streak was observed on the surface of the molded product.

Example 8 In Example 1, the AS resin mixed with 45 parts of the graft polymer was acrylonitrile-α-methylstyrene copolymer resin obtained by emulsion polymerization (acrylonitrile content 26%).
The same treatment as in Example 1 was carried out except that the content was changed to 55 parts, and the evaluation was made. The results are summarized in Table 5. It can be seen that the heating original temperature is higher than that of the resin obtained in Example 1.

Example 9 Acrylonitrile-α-methylstyrene copolymer resin obtained by suspension polymerization of the AS resin mixed with 45 parts of the graft polymer in Example 1 (acrylonitrile content 30
%) And treated and evaluated in the same manner as in Example 1. The results are summarized in Table 5.

Example 10 Evaluation was carried out in the same manner as in Example 1 except that the mixing ratio of the acrylonitrile-styrene suspension copolymer AS resin mixed with the graft polymer in Example 1 was changed as shown in Table 6.
The results are summarized in Table 6.

Example 11 Polymerization was carried out in the same manner as in Example 1 except that t-butylperoxyacetate was used as a polymerization initiator instead of diisopropylbenzene hydroperoxide, and the physical properties were evaluated. The total light transmittance is 66%, and the number of plating strips is 10
No silver streaks were found.

Example 12 280 parts of pure water in an autoclave, weight average particle diameter of 60 m
100 parts of small particle size poly (butadiene) latex of μ (as solid content) 1.0 part of potassium stearate, ferrous sulfate
0.0075 parts, tetrasodium ethylenediaminetetraacetate
015 parts and 0.45 part of sodium formaldehyde sulfoxylate were added and heated to 50 ° C. with stirring. 20 parts of methyl methacrylate, 90 parts of styrene, 40 parts of acrylonitrile, 0.8 parts of t-dodecyl mercaptan.
Part, diisopropylbenzene hydroperoxide 0.
Polymerization was started by adding 20% of the whole of the mixed solution consisting of 3 parts at once. Two hours after the start of polymerization (polymerization rate of batch-added monomer: 97%), the remaining mixture (80% of the total mixture)
Was continuously added over 4 hours. After the addition was completed, 0.1 part of diisopropylbenzene hydroperoxide was further added, and the mixture was stirred at 70 ° C. for 2 hours to complete the polymerization. The yield was 99%. An aqueous calcium chloride solution was added to the obtained polymer latex to recover the graft polymer.

45 parts of this graft polymer and an acrylonitrile-styrene suspension copolymer AS resin (acrylonitrile content 25
%) 55 parts and mixed into an extruder to form pellets. The obtained pellets were evaluated in the same manner as in Example 1. The melt flow index was 16.4 g / 10 minutes, the heat distortion temperature was 92%, and the number of peeled platings was 84.

〔The invention's effect〕

As described above, in the present invention, the weight average particle diameter is 120 mμ.
When an ABS resin is produced by performing graft polymerization using the following small particle size diene rubber latex, a part of the monomers to be used for the graft polymerization is added all at once to the diene rubber latex to start the polymerization. By continuously adding the remaining monomer and terminating the polymerization, the diene rubber particles can be appropriately aggregated, and an ABS resin that is light-transmissive and has excellent plating adhesion can be obtained. As described above, the effect of the present invention is exerted by controlling the particle size of the diene rubber latex used for emulsion graft polymerization and the addition method of the monomer.

Claims (1)

[Claims] 1. A monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of 100 parts by weight (as a solid content) of a diene rubber latex having a weight average particle size of 120 mμ or less. When emulsion polymerization was carried out by adding 60 to 900 parts by weight, 10% by weight to 90% by weight of the monomer mixture was added all at once to the diene rubber latex to start the polymerization, and the remaining monomer was added. A method for producing a thermoplastic resin having good plating adhesion strength, characterized in that the mixture is continuously added at the start of the polymerization of the above-mentioned added monomers, during the polymerization, or after the completion of the polymerization, to perform polymerization.