JPH05320462A - Thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic resin compsn. having an improved vacuum- formability while retaining high resistances to chemicals and chlorofluorocarbons by compounding a specific graft copolymer with a specific copolymer. CONSTITUTION:This compsn. is prepd. by compounding 5-80 pts.wt. graft copolymer and 20-95 pts.wt. copolymer. The graft copolymer is prepd. by grafting 5-70wt.% graft component comprising 35-80wt.% vinyl cyanide compd. and the rest being an arom. vinyl compd. and/or a (meth)acrylic ester compd. onto 95-30wt.% rubberlike polymer. The copolymer is prepd. from a monomer mixture comprising 35-80wt.% vinyl cyanide compd., 0-63wt.% arom. vinyl compd., and 2-20wt.% (meth)acrylic ester compd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent chemical resistance and vacuum formability, and more particularly to a resin composition suitable for applications such as interior lining sheets for electric refrigerators and door lining sheets.

[0002]

2. Description of the Related Art A resin material used as a lining material for an electric refrigerator is required to have a relatively excellent chemical resistance and a sufficient strength, such as an ABS resin, and an excellent vacuum formability. The electric refrigerator has a structure in which a space between the outer box and the inner lining is filled with a foamed polyurethane heat insulating layer, and the resin material used for the inner lining is required to have a property that is not affected by CFCs which are a foaming agent for urethane foaming.

As a method for satisfying such properties, as in the technique disclosed in JP-A-2-284906, in order to improve chemical resistance, the content of acrylonitrile in the resin is higher than that of ordinary ABS resin. The method of increasing it is taken. Combined with such a method, for this purpose, a method of forming an inner box without wall thickness unevenness by improving the vacuum formability of the resin by adding a plasticizer is usually used. Acid ester plasticizers increase the acrylonitrile content in the resin,
Its poor compatibility results in bleeding out of the resin,
There was a problem that the effect could not be exhibited sufficiently.

[0004]

By reducing the molecular weight of the resin, the fluidity during processing can be increased and the vacuum formability can be improved, but the drawback is that the CFC resistance is greatly reduced. there were. Therefore, it is necessary to improve the vacuum formability while maintaining the compatibility and the CFC resistance.

[0005]

Means for Solving the Problems As a result of intensive investigations by the present inventors on a method of improving vacuum formability while maintaining chemical resistance and freon resistance at high levels, the content of vinyl cyanide compound was It has been found that a resin composition comprising a graft copolymer in a specific range and a copolymer containing a (meth) acrylic acid ester compound and having a vinyl cyanide compound content in a specific range achieves the above object. The present invention has been completed.

That is, the present invention is a graft copolymer obtained by grafting (A) a vinyl cyanide compound and an aromatic vinyl compound and / or a (meth) acrylic acid ester compound onto a rubber polymer, which is a rubber polymer. Is 30
To 95% by weight, the graft component is 5 to 70% by weight, and the vinyl cyanide compound / (vinyl cyanide compound and / or aromatic vinyl compound and / or (meth))
Acrylic ester compound) weight ratio is 0.35
A copolymer containing (B) a vinyl cyanide compound, an aromatic vinyl compound and a (meth) acrylic acid ester compound. Acid ester compound is 2 to 20% by weight, and vinyl cyanide compound /
A thermoplastic resin composition comprising 20 to 95 parts by weight of a copolymer having a weight ratio of (vinyl cyanide compound, aromatic vinyl compound and (meth) acrylic acid ester compound) of 0.35 to 0.8. ..

The present invention will be described in detail below. Examples of the vinyl cyanide compound used in the present invention include acrylonitrile and methacrylonitrile. Acrylonitrile is particularly preferred. As the aromatic vinyl compound,
Examples thereof include styrene, α-methylstyrene, paramethylstyrene and the like. Particularly preferred is styrene.

Examples of the (meth) acrylic acid ester compound include methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl acrylate, octyl acrylate, propyl acrylate and hexyl acrylate.

A particularly preferred (meth) acrylic acid ester compound used in the graft copolymer (A) together with or instead of the aromatic vinyl compound is methyl methacrylate. The preferred (meth) acrylic acid ester compound in the copolymer (B) is
A monomer having a copolymerization plasticizing effect such as butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, propyl acrylate, and hexyl acrylate is preferable, and butyl acrylate is particularly preferable.

The rubbery polymer has a glass transition temperature of 0 ° C or lower, preferably -20 ° C or lower. Specifically, polybutadiene, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber and other diene rubbers, polybutyl acrylate and other acrylic rubbers, polyisoprene, polychloroprene, ethylene-propylene rubber, ethylene-propylene. Block copolymers such as a diene terpolymer rubber, a styrene-butadiene block copolymer rubber, a styrene-isoprene block copolymer rubber, and hydrogenated products thereof can be used. Preferred are polybutadiene, styrene-butadiene copolymer rubber, and acrylonitrile-butadiene copolymer rubber.

The proportion of the rubber-like polymer in the graft copolymer is used in the range of 30 to 95% by weight, but it is preferably 50 to 90 from the viewpoint of the balance between impact resistance and working fluidity.
It is in the range of% by weight. The ratio of the graft component is 5
It is necessary to be 70% by weight. If it is less than 5% by weight, the compatibility with the matrix resin is lowered, the rubbery polymer is aggregated, and the surface gloss of the resin is lowered, which is not preferable. On the other hand, if it exceeds 70% by weight, the impact resistance of the resin decreases, which is not preferable. More preferable range is 1
It is 5 to 50% by weight.

The ratio of the rubbery polymer to the graft component in the graft copolymer is specifically measured by dissolving the polymer produced by the polymerization in acetone and separating and removing the insoluble matter by a centrifuge. I can do things.
The component that dissolves in acetone is the component that did not undergo graft reaction in the copolymerized polymer (non-graft polymer), and the value obtained by subtracting the amount of rubber polymer from the acetone insoluble content is defined as the value of the graft component. To be done.

The weight ratio of the copolymerization component in the graft copolymer is such that the value of vinyl cyanide compound / (vinyl cyanide compound and aromatic vinyl compound and / or (meth) acrylic acid ester compound) is 0.35. It is necessary to be 0.8. If it is less than 0.35, sufficient chemical resistance cannot be obtained. On the other hand, when it exceeds 0.8, the cyclization reaction and the crosslinking reaction of the vinyl cyanide compounds proceed during high temperature processing, which is not preferable. More preferably 0.
It is in the range of 35 to 0.6. More preferably 0.4-
It is in the range of 0.5.

The graft copolymer is obtained by polymerizing the vinyl monomer by a known method in the presence of a rubbery polymer, for example, an emulsion polymerization method, a bulk polymerization method or a suspension polymerization method. can get. Copolymer (B) used in the present invention
As a (meth) acrylic acid ester compound 2 to 2
It is necessary to contain 0% by weight. If it is less than 2% by weight, the effects of fluidity and vacuum formability are not sufficient. If it exceeds 20% by weight, the chemical resistance is lowered, which is not preferable. The preferred content is in the range of 5 to 15% by weight.

The weight ratio of vinyl cyanide compound / (vinyl cyanide compound and aromatic vinyl compound and (meth) acrylic acid ester compound) in the copolymer (B) is 0.35 to 0.8. It is necessary. 0.4
If it is less than the above, sufficient chemical resistance (especially CFC resistance) cannot be obtained. If it exceeds 0.8, the cyclization reaction and the crosslinking reaction of vinyl cyanide compounds proceed during high temperature processing, which is not preferable. The range is more preferably 0.35 to 0.6. More preferably, it is 0.4 to 0.5.

The copolymer (B) may contain a non-graft polymer component produced during the production of the graft copolymer (A). However, the composition and the content of the non-graft polymer component derived from the graft copolymer (A) are within the range of the copolymer (B) described above as a whole even when it is contained in the copolymer (B). It is necessary to be inside.

The copolymer (B) can be produced by a known method such as an emulsion polymerization method, a bulk polymerization method or a suspension polymerization method. At this time, a method of separately polymerizing the graft copolymer (A) and the copolymer (B), and a method of simultaneously producing the copolymer in the step of polymerizing the graft copolymer (A) can be used. However, the manufacturing method is not particularly limited.

The preferred molecular weight of the copolymer (B) is in the range of 8 to 20 centipoise when the viscosity at 25 ° C. is measured at a polymer concentration of 10% by weight using a methyl ethyl ketone solvent. The blending ratio of the polymers (A) and (B) is 5 to 80 parts by weight of the (A) graft copolymer and 20 to 95 parts by weight of the (B) copolymer when the total amount is 100 parts by weight. is necessary.

When the amount of the graft copolymer (A) is less than 5 parts by weight, the required mechanical strength, particularly impact resistance cannot be obtained. When it exceeds 80 parts by weight, the balance between chemical resistance and process fluidity is deteriorated. When the amount of the copolymer (B) is less than 20 parts by weight, the required vacuum moldability cannot be obtained. 95
If it exceeds the weight part, it cannot be used because the chemical resistance is significantly lowered.

In the graft copolymer (A) and the copolymer (B) in the present invention, a vinyl monomer such as those listed below is added, if necessary, within a range not impairing the object of the present invention. It is possible to polymerize and use. That is, maleimide, maleimide-based monomers such as N-phenylmaleimide, α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic anhydride, and glycidyl group-containing monomers such as glycidyl methacrylate. In the resin composition of the present invention, if necessary, a usual antistatic agent, antioxidant, ultraviolet absorber, flame retardant, pigment, dye, lubricant,
It is possible to add additives such as.

[0021]

EXAMPLES In order to explain the present invention more specifically, examples and comparative examples will be described below, but these do not limit the present invention. (Hereinafter, "part" means "part by weight".

Preparation of Graft Copolymer; A-1: Polybutadiene latex (weight average particle diameter 3
A monomer mixture consisting of 29 parts of acrylonitrile and 31 parts of styrene was emulsion-polymerized with respect to 40 parts (solid content) of 000 angstrom and gel content of 87% to obtain a graft copolymer A-1. The results of measuring the composition of the obtained resin with an infrared spectrophotometer are shown in Table 1.

A-2: A-2 was prepared in the same manner as A-1 except that 15 parts of acrylonitrile and 45 parts of styrene were used.
Got Table 1 shows the results of the same measurement as in A-1. A-3: A-3 was obtained in the same manner as A-1 except that 36 parts of acrylonitrile and 24 parts of styrene were used. A-
Table 1 shows the results of measurement performed in the same manner as 1. A-4: 29 parts of acrylonitrile and 20 parts of styrene
Part, A-1 except that 11 parts of methyl methacrylate were used
A-4 was obtained by a method similar to. Table 1 shows the results of the same measurement as in A-1.

[0024]

[Table 1]

Preparation of Copolymer (B); Composition B-1 shown in Table 2 prepared by solution polymerization method
~ B-7 were used as the copolymer (B).

[0026]

[Table 2]

Examples 1 to 7 and Comparative Examples 1 to 4 The polymers A-1 to 4 and the copolymer (B) containing the graft copolymer (A) were blended at the composition ratios shown in Table 3, and the set temperature was set. The mixture was melt-kneaded with a twin-screw extruder at 260 ° C. to obtain pellets. Then, flat plates having a thickness of 1 mm and 3 mm were produced at a mold temperature of 220 ° C. by a compression molding machine. Thickness 1m
A flat plate of m was cut out and used as a sample for measuring CFC resistance. A flat plate having a thickness of 3 mm was cut out to prepare a sample for high temperature creep. Table 3 shows the results obtained by measuring the melt flow rate (MFR), the CFC resistance, and the high temperature creep using these samples by the following methods. From Table 3, it is clear that the resin composition according to the present invention is excellent in fluidity, CFC resistance and high temperature creep.

Measuring method 1. Melt flow rate (MFR) Based on JIS K-7210. (220 ℃, 10kg
Load) 2. Freon resistance The center of the compression-molded and annealed test piece (width 12.7 mm, thickness 1.0 mm) was covered with gauze, and the outside was covered with Saran wrap, and a load of 0.75% strain was applied to the test piece. After the application, Freon 123 was injected with a syringe to perform a creep test, and the time from the injection to the break of the test piece was measured. During testing, Freon 123 was injected from time to time to prevent the gauze from drying, and the time (sec) until fracture occurred.
Was measured.

3. High temperature creep compression molded and annealed dumbbell specimens (ASTM D
638, Type 1), a load corresponding to a stress of 5 g / mm ² is applied, and the time at which an elongation of 50% occurs at a predetermined temperature is measured, and the elongation rate R (% / min) is measured by the log R The temperature gradient (% / min.
The value of (° C.) Was taken as the value of high temperature creep. The smaller this value, the smaller the temperature dependence of the elongation rate,
It is possible to obtain a good molded product with little thickness variation during vacuum molding.

[0030]

[Table 3]

[0031]

EFFECT OF THE INVENTION The thermoplastic resin composition of the present invention has the effects of high chemical resistance and freon resistance and excellent vacuum formability. It is extremely useful as an inner box of a refrigerator.

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Claims (3)

[Claims] 1. A graft copolymer obtained by grafting (A) a vinyl cyanide compound and an aromatic vinyl compound and / or a (meth) acrylic acid ester compound onto a rubber-like polymer, wherein the rubber-like polymer is 30 to 30. 95% by weight, the graft component is 5 to 70% by weight, and the weight ratio of vinyl cyanide compound / (vinyl cyanide compound and aromatic vinyl compound and / or (meth) acrylic acid ester compound) is 0. 5 to 80 parts by weight of a graft copolymer of 35 to 0.8 and (B) a vinyl cyanide compound, an aromatic vinyl compound and a (meth) acrylic acid ester compound, )
The acrylic acid ester compound is 2 to 20% by weight, and the weight ratio of vinyl cyanide compound / (vinyl cyanide compound and aromatic vinyl compound and (meth) acrylic acid ester compound) is 0.35 to 0. A thermoplastic resin composition comprising 20 to 95 parts by weight of the copolymer of No. 8. 2. A sheet molded product comprising the thermoplastic resin composition according to claim 1, wherein (A) in claim 1 is 5 to 60 parts by weight and (B) is 40 to 95 parts by weight. 3. An inner box for an electric refrigerator, comprising the sheet molded product according to claim 2.