JPH1025396A - Production of molded article of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded article of a thermoplastic rubber-reinforced resin having excellent appearance and mechanical properties, especially impact resistance, and allowing the decrease in the addition amount of thermal stabilizer and antioxidant. SOLUTION: The objective molded article is produced by mixing (A) 10-90 pts.wt. of a graft copolymer containing 20-60wt.% of a rubbery polymer with (B) 90-10 pts.wt. of a copolymer produced by copolymerizing an aromatic vinyl compound with a vinyl cyanide compound and/or an α,β-unsaturated carboxylic acid alkyl ester to obtain a resin composition containing 5-30wt.% of the rubbery polymer, melting and kneading the composition in an injection molding machine, injecting the molten mixture into a mold and cooling in the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to molding of a thermoplastic rubber reinforced resin which can reduce the amount of a heat stabilizer and an antioxidant and which is excellent in appearance, mechanical properties and especially impact resistance. Offer goods.

[0002]

2. Description of the Related Art A resin composition obtained by graft copolymerizing a vinyl cyanide compound and an aromatic vinyl compound onto a rubbery polymer is known as an acrylonitrile / butadiene / styrene resin (hereinafter referred to as ABS resin). It is used in various fields because of its balance between mechanical properties and moldability. In order to respond to various needs, an ABS resin product with a high concentration of a rubbery polymer is produced and a method of diluting the ABS resin with an acrylonitrile-styrene copolymer at various compounding ratios in order to obtain an ABS resin product. Widely used. First, ABS with high concentration of rubbery polymer
The resin and the acrylonitrile-styrene copolymer were melt-kneaded with an extruder to obtain pellets, which were molded using an injection molding machine or the like.

However, oxidation or thermal decomposition occurs due to these thermal histories over several degrees, and the color tone and the physical properties are deteriorated. Therefore, it is necessary to add a heat stabilizer, which is disadvantageous in cost. However, it was not possible to completely prevent a decrease in physical properties, particularly impact resistance. Furthermore, as a result of pre-kneading by an extruder, various grades can be produced depending on the combination of the graft copolymer and the copolymer and the compounding ratio, so that the management was very complicated.

[0004]

As described above, when the pre-kneading is performed by the extruder, the grade control becomes very complicated, and the molded product obtained by injection-molding the pre-kneaded product is heat-resistant. Due to the history, the appearance and mechanical properties, particularly the impact resistance, were inferior, so that a certain amount of the heat stabilizer had to be used, and the effect was insufficient.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a graft copolymer having a rubbery polymer content within a specific range and a copolymer are blended in a certain ratio and extruded. Thus, a method for obtaining a molded article having excellent impact resistance and appearance by directly obtaining a molded article by an injection molding machine without performing preliminary kneading by a machine has been invented.

That is, according to the present invention, an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester are graft-polymerized to a rubbery polymer. Graft copolymer (A) 10 to 90 characterized by containing
90 parts by weight of a copolymer (B) obtained by copolymerizing an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester with the rubber in the entire resin After mixing so that the content of the polymer is 5 to 30% by weight, the mixture is melt-kneaded in an injection molding machine, and the melt is injected into a mold and cooled to obtain a molded product. The present invention relates to a method for producing a molded article of a thermoplastic rubber reinforced resin.

The rubbery polymers used in the present invention include polybutadienes, butadiene-styrene copolymers, butadiene-acrylonitrile copolymers, diene rubbers such as polyisoprene, butyl acrylate, methyl methacrylate, and (meth) acrylate. An acrylic rubber such as a polymer, a saturated rubber such as a hydrogenated polybutadiene, an ethylene-propylene copolymer rubber, a fluorine rubber, and a silicone rubber can be used. As the aromatic vinyl compound,
Styrene, α-methylstyrene, chlorinated styrene, halogenated styrene such as brominated styrene, vinyltoluene, alkylated styrene such as dimethylstyrene, vinylnaphthalene and the like, among which preferred monomers are, Styrene and α-methylstyrene.

Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.

As the α, β-unsaturated carboxylic acid alkyl ester, an alkyl (meth) acrylate having an alkyl group having 1 to 10 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) Acrylate, butyl (meth) acrylate, 2-
Examples include ethylhexyl (meth) acrylate, hydroxyethyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, and benzyl (meth) acrylate. Of these, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, phenyl acrylate, phenyl methacrylate, and cyclohexyl acrylate are preferred.

The content of the rubbery polymer in the graft copolymer (A) is from 20 to 60% by weight, preferably from 20 to 60% by weight.
It is 50% by weight, more preferably 20 to 40% by weight.
If the content is less than 20% by weight, the impact resistance of the ABS resin after mixing becomes insufficient, and if it exceeds 60% by weight, a uniform composition cannot be obtained. Further, the content of the rubbery polymer in the entire resin composed of the graft copolymer (A) and the copolymer (B) is 5 to 30% by weight. If this is less than 5% by weight, sufficient impact resistance cannot be obtained,
If the content exceeds 30% by weight, the appearance of the molded product becomes inferior due to the decrease in molding processability.

When the graft copolymer (A) and the copolymer (B) are mixed and injection-molded, a flame retardant, a flame retardant auxiliary, a pigment, a dye, a lubricant, an antioxidant, an ultraviolet ray, if necessary. Various additives such as an absorbent, an antistatic agent, a reinforcing agent, a filler, and an antibacterial agent can be added to such an extent that their physical properties are not impaired. After mixing the graft copolymer (A), the copolymer (B), and other additives as necessary, mixing them with a tumbler or the like, supply them to an injection molding machine,
Preferably, injection molding is performed. By this operation, it is possible to obtain a molded article having more excellent uniformity.

Although there is no particular limitation on the molding machine used for injection molding, mixing nozzles, dalmage type, pin type, pineapple mixing type, cavity transfer type, throttled screw type,
It is preferable to use a molding machine provided with a screw having a mixing unit such as a static mixer type, a varistoring type, or a union carbide mixing type.

The molding conditions for molding the molded article of the present invention are as follows: the injection molding temperature is from 180 ° C. to 290 ° C., preferably from 200 ° C. to 280 ° C. If it is lower than 180 ° C, injection molding is difficult because the fluidity of the resin is insufficient, and if it exceeds 290 ° C, thermal deterioration of the resin becomes severe, resulting in poor mechanical properties and appearance of the molded product. Becomes

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically below with reference to examples and the like, but the scope of the present invention is not limited by these examples.

[0015]

[Reference Example 1] Production of graft copolymer (A-1) Polybutadiene rubber latex 1 (CN WOOD)
(Weight average particle diameter measured by MODL-6000 type manufactured by Co., Ltd .: 250 nm, rubber solid content: 45% by weight),
To precipitate a rubber component with isopropyl alcohol. This was vacuum-dried at 40 ° C. for 12 hours, and a mixed solution of methyl ethyl ketone: cyclohexane = 1: 4 was added thereto.
Let stand for 24 hours and swell sufficiently with the mixed solution. Then, the gel was filtered off with a 200 mesh wire mesh, and 13
The weight of the gel component dried at 0 ° C. for 30 minutes was precisely weighed to determine the gel content. As a result, the gel content was 75% by weight.

When the measurement of polybutadiene rubber latex 2 was carried out in the same manner, the weight average particle diameter was 170 nm, the rubber solid content was 45% by weight, and the gel content was 85% by weight.

750 parts by weight of the rubber latex 1, 250 parts by weight of the rubber latex 2 and 2 parts by weight of potassium alkenyl succinate (alkenyl group is C13 to C15) are placed in a polymerization vessel equipped with a ring cooler. 70 ° C while replacing
The temperature rose. A mixed solution of 165 parts by weight of acrylonitrile, 385 parts by weight of styrene, 2 parts by weight of cumene hydroperoxide, 0.7 parts by weight of t-dodecyl mercaptan;
And 1.0 part by weight of sodium formaldehyde sulfoxylate in 500 parts by weight of deionized water, 0.01 part of ferrous sulfate
Parts by weight, sodium ethylenediaminetetraacetate 0.4
A solution in which parts by weight were dissolved was continuously added over 6 hours to cause a reaction. During this time, the temperature of the polymerization system was controlled at 70 ° C., and after the addition was completed, the state was further maintained for one hour to complete the polymerization. After coagulation and salting out the obtained copolymer latex, 2.85 parts by weight of butylidenebis (methylbutylphenol) and 1,1,3-tris (2-methyl-4-ditridecylphosphate-5-) were used as heat stabilizers. t
0.95 parts by weight of (-butylphenyl) butane was added, the slurry was dewatered and molded by a screw press, and the ABS resin obtained by drying was pulverized by a pulverizer.

As a result of quantification by the FT-IR calibration curve method, the rubber content was 45.2% by weight.

[0019]

[Reference Example 2] Production of graft copolymer (A-2) Polybutadiene rubber latex (CN WOOD)
Using a weight average particle diameter of 170 nm, a rubber solid content of 40% by weight, a gel content of 87% by weight), 1000 parts by weight of acrylonitrile and 396 parts by weight of styrene, as measured by MODL-6000 manufactured by K.K. After salting out, 2.52 parts by weight of butylidenebis (methylbutylphenol) and 1,1,3-tris (2-methyl-4-ditridecylphosphate-5-t) were used as heat stabilizers.
Production and evaluation were performed in the same manner as in Reference Example 1 except that 0.84 part by weight of (-butylphenyl) butane was added. As a result, the rubber content was 40.2% by weight.

[0020]

Reference Example 3 Production of Copolymer (B-1) Using acrylonitrile, styrene, n-butyl acrylate, and ethylbenzene as a solvent, the mixed solution was continuously fed to a complete mixing type polymerization reactor,
The polymerization reaction was performed while controlling the temperature of the polymerization system at 120 to 130 ° C. Thereafter, the mixed solution containing the polymer was taken out of the polymerization reactor, and the unreacted monomer and the solvent were removed under vacuum to obtain a solid powder of a copolymer. As a result of quantification by FT-IR, the contents of acrylonitrile and n-butyl acrylate were 27.0% by weight and 10.0% by weight, respectively. The weight-average molecular weight was 12.4 × 10 ^{4 as} measured by GPC. In addition, FT-IR and GPC measurement conditions are as follows.

(FT-IR measurement conditions) Measuring equipment: FT / IR 7000 manufactured by JASCO Sample preparation: 30 μm thick by compression molding
The quantification was determined by the calibration curve method.

(GPC measurement conditions) Measuring equipment: Tosoh Corporation Column: Tosoh Corporation G3000HXL, G40
00HXL, G5000HXL, and G6000HXL
Are connected in series. Developing solvent: tetrahydrofuran The molecular weight measurement results were obtained by a calibration curve method using polystyrene as a standard substance.

[0023]

Reference Example 4 Production of Copolymer (B-2) A copolymer was produced in the same manner as in Reference Example 3, except that acrylonitrile and styrene were copolymerized. As a result of quantification by FT-IR, the content of acrylonitrile was 28.0% by weight, and the average molecular weight was 13.7 × 10 ⁴ .

[0024]

Example 1 After mixing 41.5 parts by weight of the graft copolymer (A-1) and 58.5 parts by weight of the copolymer (B-1) with a tumbler, a screw having a union carbide mixing unit was provided. It was put into the supply hopper of the injection molding machine to perform injection molding. The rubbery polymer in all resins was 18.8% by weight. Specimens for measuring physical properties were prepared at a cylinder temperature of 240 ° C. and a mold temperature of 45 ° C., and were used as a starting product, an intermediate product, and a final product over time from the start of preparation.
In addition, physical properties were evaluated by the following methods. Table 1 shows the results.

(1) Impact resistance (IZOD impact strength) Measured according to the method of ASTM D-256.

(Notched, specimen thickness 1/4 inch) (2) Flexural modulus Measured according to the method of ASTM D-790.

(3) Yellowness Measured according to the method of JIS K7103.

[0028]

Example 2 50 parts by weight of the graft copolymer (A-2)
A sample was prepared and evaluated in the same manner as in Example 1 except that the copolymer (B-2) and 50 parts by weight of the copolymer (B-2) were used. The rubbery polymer in all resins was 20.1% by weight. Table 1 shows the results.

[0029]

Comparative Example 1 After mixing 41.5 parts by weight of the graft copolymer (A-1) and 58.5 parts by weight of the copolymer (B-1), a PCM30 extruder (2) manufactured by Ikegai Co., Ltd. The mixture was melt-kneaded at 240 ° C. with a coaxial extruder (φ = 30 mm, L / D = 33) to obtain pellets. This was injection molded in the same manner as in Example 1 to prepare and evaluate a sample. Table 1 shows the evaluation results.
Shown in

[0030]

Comparative Example 2 50 parts by weight of a graft copolymer (A-2)
A sample was prepared and evaluated in the same manner as in Comparative Example 1, except that 50 parts by weight of the copolymer (B-2) and the copolymer (B-2) were mixed. Table 1 shows the evaluation results.

[0031]

[Table 1]

Tables 2 and 3 show evaluations for examining the utility of the molded article.

[0033]

[Table 2]

[0034]

[Table 3]

As is clear from Tables 2 and 3, according to the present invention, a molded article having excellent impact resistance and appearance and having a uniform composition can be obtained with one heat history.

[0036]

According to the present invention, the amounts of heat stabilizers and antioxidants can be reduced, and the appearance, mechanical properties,
Particularly, a molded article of a thermoplastic rubber reinforced resin having excellent impact resistance is provided.

Claims (1)

[Claims] 1. A rubbery polymer obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester, and containing 20 to 60% by weight of the rubbery polymer. 10 to 90 parts by weight of a graft copolymer (A), and a copolymer obtained by copolymerizing an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester. After mixing 90 to 10 parts by weight of the combined (B) so that the content of the rubbery polymer in the whole resin is 5 to 30% by weight, the mixture is melt-kneaded in an injection molding machine, and the melt is molded into a mold. A method for producing a molded article of a thermoplastic rubber-reinforced resin, wherein the molded article is obtained by injecting and cooling the molded article.