JPH1025398A - Production of molded article of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for the production of a molded article of a thermoplastic 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 produced by the graft polymerization of an aromatic vinyl compound and a vinyl cyanide compound and/or an α,β-unsaturated carboxylic acid alkyl ester to a rubbery polymer and containing 10-60wt.% of the rubbery polymer with (B) 90-10 pts.wt. of a copolymer of an aromatic vinyl compound and a vinyl cyanide compound and/or an α,β-unsaturated carboxylic acid alkyl ester to obtain a resin mixture containing 5-30wt.% of the rubbery polymer, melting and kneading the resin mixture in a molding machine, injecting the molten resin into a mold and cooling in the mold. A ηA/ηB ratio is adjusted within the range of 0.5-4.5 during the above kneading process wherein ηA is the melt viscosity of the graft copolymer A and ηB is the melt viscosity of the copolymer B at a shear rate of 600sec<-1> at the kneading temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a molded article of a thermoplastic resin which is capable of reducing the amount of a heat stabilizer and an antioxidant and which is excellent in appearance, mechanical properties and especially impact resistance. Provide the law.

[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 rubber-reinforced thermoplastic resin having a melt viscosity ratio at a molding temperature within a certain range and a copolymer are blended in a certain ratio, and the mixture is extruded by an extruder. By directly obtaining a molded article by an injection molding machine without performing preliminary kneading, a method for obtaining a molded article having excellent impact resistance and appearance has been invented.

That is, the present invention provides a graft copolymer obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester onto a rubbery polymer. (A) and 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. 10 to 90 parts by weight of one or more rubber-reinforced thermoplastic resins (C) characterized by containing 10 to 60% by weight of the coalesced product, and an aromatic vinyl compound and a vinyl cyanide compound and / or α, β-
One or more copolymers (D) 9 obtained by copolymerizing an unsaturated carboxylic acid alkyl ester
After mixing 0 to 10 parts by weight so that the content of the rubbery polymer in the whole resin is 5 to 30% by weight, these are melt-kneaded in a molding machine, and the melt is injected into a mold. A method of obtaining a molded product by cooling, wherein the rubber-reinforced thermoplastic resin (C) at a shear rate of 600 sec- ¹ at the kneading temperature
Where η _{C is} the melt viscosity of η _C and η _D is the melt viscosity of the copolymer (D), the value of η _C / η _D is in the range of 0.3 to 4.5. The present invention relates to a method for producing a molded article of a plastic 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 method for producing the rubber-reinforced thermoplastic resin (C) comprising the graft copolymer (A) and the copolymer (B) is not particularly limited. After the polymer latex and the copolymer latex are blended, a method of salting out and a method of melt-kneading the graft copolymer and the copolymer can be used.

The melt viscosities of the rubber-reinforced thermoplastic resin (C) and the copolymer (D) at the molding temperature are measured by a capillograph, and the viscosities at shear rates of 600 sec- ¹ are determined.

[0012] The melt viscosity of the rubber-reinforced thermoplastic resin in the molding temperature (C) eta _C, when the melt viscosity of the copolymer (D) and eta _D, the value of η _C / η _D is 0.3 to 4 0.5, preferably 0.5-4.3, more preferably 0.5-4.
0. If it is less than 0.3 or exceeds 4.5, it becomes difficult to obtain a molded article having a uniform composition. When two or more rubber-reinforced thermoplastic resins (C) are used, the melt viscosity means the melt viscosity after blending these. 2
The same applies to the case where at least one kind of copolymer (D) is used.

When the rubber-reinforced thermoplastic resin (C) and the copolymer (D) are mixed and injection molded, a flame retardant, a flame retardant auxiliary, a pigment, a dye, a lubricant, an antioxidant, Various additives such as an ultraviolet absorber, 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. It is preferable to mix a rubber-reinforced thermoplastic resin, a copolymer, and other additives as necessary, perform mixing by a tumbler or the like, and then supply the mixture to an injection molding machine to perform injection molding. By this operation, it is possible to obtain a molded article having more excellent uniformity.

There are no particular restrictions on the molding machine used for injection molding, but there are 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

[0016]

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.

[0017]

[Reference Example 1] Production of rubber-reinforced thermoplastic resin (C-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: 40% 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 80% by weight.
Met. Similarly, the gel content of polybutadiene rubber latex 2 (weight average particle diameter 170 nm, rubber solids 40% by weight) was measured to be 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 put into a polymerization vessel equipped with a ring cooler. 7 while replacing with nitrogen
The temperature was raised to 0 ° C. Acrylonitrile 180 parts by weight, styrene 420 parts by weight, cumene hydroperoxide 2
Part, a mixture of 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) as a heat stabilizer and 1,1,3-tris (2-methyl-4-ditridecyl phosphate) are used. −5-t
-Butylphenyl) butane (0.95 parts by weight) was added, the slurry was dewatered and molded by a screw press, dried, and the resulting ABS resin was pulverized by a pulverizer to obtain a plate-shaped graft copolymer. A coalescence was obtained. In addition, as a result of quantification by the FT-IR calibration curve method, the rubber content was 40.1% by weight. The melt viscosity at a shear rate of 600 s to ^{1 at} 240 ° C. was 6.5 × 10 ³ poise.

(Rubber Content Measuring Conditions) Measuring device: FT / IR 7000 manufactured by JASCO Sample: 30 μm prepared by compression molding
m was determined by a film calibration curve method.

(Melt Viscosity Measurement Conditions) Measuring apparatus: Capillograph 1B manufactured by Toyo Seiki Co., Ltd. Measurement temperature: 240 ° C. Barrel: 9.55 mm Measurement die φ: 1 mm

[0022]

Reference Example 2 Production of Copolymer (D-1) Using acrylonitrile, styrene and ethylbenzene as a solvent, the above mixture was continuously fed to a complete mixing type polymerization reactor, and the temperature of the polymerization system was adjusted to 120 to 100%. 130
The polymerization reaction was carried out by controlling the temperature to ° 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. The melt viscosity at 240 ° C. and a shear rate of 600 s- ¹ was 2.7 × 10 ³ . The content of acrylonitrile was 27.8% by weight as a result of quantification using a calibration curve method by FT-IR. The weight average molecular weight measured by GPC was 12.0 × 10 ³ . The GPC measurement conditions are as follows.

(GPC measurement conditions) Measurement equipment: Tosoh Corporation Column: Tosoh Corporation G3000HXL, G40
00HXL, G5000HXL, and G6000HXL
Developed solvent: tetrahydrofuran The molecular weight measurement results were determined by a calibration curve method using polystyrene as a standard substance.

[0024]

Reference Example 3 Production of Copolymer (D-2) A copolymer was produced in the same manner as in Reference Example 2 to obtain a powder of the copolymer. The melt viscosity at 240 ° C. and a shear rate of 600 sec- ¹ was 5.7 × 10 ³ poise. The acrylonitrile content was 27.6% by weight, and the weight average molecular weight was 19.4 × 10 ⁴ .

[0025]

Reference Example 4 Production of Copolymer (D-3) A copolymer powder was obtained in the same manner as in Reference Example 2, except that acrylonitrile, styrene, and n-butyl acrylate were continuously added. . 240 ° C, shear rate 600
The melt viscosity at s ~ ¹ was 1.2 × 10 ³ . As a result of quantification using the calibration curve method by FT-IR, the contents of acrylonitrile and n-butyl acrylate were 27.9% by weight and 7.1% by weight, respectively, and the weight average molecular weight was 9.4 × 10 ^4. Met.

[0026]

Reference Example 5 Production of Copolymer (D-4) 50 parts by weight of the copolymer (D-2) and 50 parts by weight of the copolymer (D-3) obtained in Reference Examples 3 and 4 were extruded. The mixture was melt-kneaded in a mixer to obtain copolymer pellets. 240 ° C,
The melt viscosity at a shear rate of 600 sec- ¹ is 3.2 × 1
It was 0 ³ poise.

[0027]

Example 1 50 parts by weight of a rubber-reinforced thermoplastic resin (C-1) and 50 parts by weight of a copolymer (D-1) were mixed by a tumbler and then injection-molded with a screw having a union carbide mixing unit. It was put into a supply hopper to the machine, and injection molding was performed. η _C / η _D = 2.4.
Test pieces for measuring physical properties were prepared at a cylinder temperature of 240 ° C and a mold temperature of 45 ° C.
Intermediate and final products. 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.

[0031]

Example 2 A sample was prepared and evaluated in the same manner as in Example 1 except that 50 parts by weight of the rubber-reinforced thermoplastic resin (C-1) and 50 parts by weight of the copolymer (D-2) were used. η _C / η _D ＝
1.1. Table 1 shows the results.

[0032]

Example 3 A sample was prepared and evaluated in the same manner as in Example 1 except that 50 parts by weight of the rubber-reinforced thermoplastic resin (C-1) and 50 parts by weight of the copolymer (D-4) were used. η _C / η _D ＝
2.0. Table 1 shows the results.

[0033]

Comparative Example 1 A sample was prepared and evaluated in the same manner as in Example 1 except that 50 parts by weight of the rubber-reinforced thermoplastic resin (C-1) and 50 parts by weight of the copolymer (D-3) were used. η _C / η _D ＝
5.4. Table 1 shows the results.

[0034]

Comparative Example 2 After mixing 50 parts by weight of a rubber-reinforced thermoplastic resin (C-1) and 50 parts by weight of a copolymer (D-1),
PCM30 extruder manufactured by Ikegai Co., Ltd.
φ = 30 mm, L / D = 33) and melt-kneaded at 240 ° C. 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.

[0035]

[Table 1]

Table 2 shows the evaluation for examining the practicality of the molded article.
Shown in

[0037]

[Table 2]

As is clear from Table 2, according to the present invention, 1
A molded article having excellent impact resistance and appearance and a uniform composition can be obtained by the heat history of each time.

[0039]

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.

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Claims (1)

[Claims] 1. A graft copolymer (A) obtained by graft-polymerizing an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester onto a rubbery polymer. And an aromatic vinyl compound and a vinyl cyanide compound and / or α, β-
One or two or more copolymers (B) comprising copolymerized unsaturated carboxylic acid alkyl esters, characterized by containing 10 to 60% by weight of a rubbery polymer. One kind obtained by copolymerizing 10 to 90 parts by weight of a rubber-reinforced thermoplastic resin (C), and an aromatic vinyl compound and a vinyl cyanide compound and / or an α, β-unsaturated carboxylic acid alkyl ester. Alternatively, after mixing 90 to 10 parts by weight of two or more copolymers (D) so that the content of the rubbery polymer in the whole resin is 5 to 30% by weight, these are melted in a molding machine. This is a method of obtaining a molded product by kneading, injecting a melt into a mold, and cooling, wherein the melt viscosity of the rubber-reinforced thermoplastic resin (C) at a shearing speed of 600 sec- ¹ at the kneading temperature is η _C , The melt viscosity of the copolymer (D) is η _D Wherein the value of η _C / η _D is in the range of 0.3 to 4.5.