JPH08269276A - Styrene resin composition - Google Patents

Abstract

PURPOSE: To obtain a styrene resin compsn. excellent in impact resistance by compounding a thermoplastic styrene resin, a specific ethylene-unsatd. carboxylic acid copolymer ionomer, and an epoxidized ethylene copolymer. CONSTITUTION: At least 60mol% of carboxyl groups of an ethylene-unsatd. carboxylic acid copolymer is neutralized to give an ethylene-unsatd. carboxylilc acid copolymer ionomer having an alkali metal (e.g. potassium) content of 0.4-4mol/kg. Then, 77.9-98.9 pts.wt. thermoplastic styrene resin (e.g. a diene- rubber-reinforced ABS resin), 25-1 pt.wt. ethylene-unsatd. carboxylic acid copolymer ionomer. 0.1-10 pts.wt. epoxidized ethylene copolymer [e.g. an ethylene- glycidyl (meth)acrylate copolymer], and if necessary a polyhydroxy compd. (e.g. glycerin) in an amt. of 0.1-20wt.% of the copolymer ionomer are mixed and melt kneaded on a twin-screw extruder, giving a thermoplastic resin compsn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a styrene resin composition having excellent impact resistance and semipermanently antistatic property.

[0002]

2. Description of the Related Art Generally, polystyrene has good moldability and dimensional accuracy, and has a beautiful appearance.
Used for household items. In addition, impact-resistant polystyrene and ABS resin are excellent in impact resistance, rigidity, molding processability, and have a good molding appearance. Therefore, automobile interior / exterior parts, home appliances, OA equipment, housing equipment, leisure, miscellaneous goods, etc. Widely used in. However, these polystyrene resins generally have a large electric resistance and are easily charged by friction, so during the manufacturing process and products, electric shock, spark discharge, adhesion of dust to the molding surface, electrostatic damage to IC parts, etc. It is known to cause various disorders.

Therefore, in order to compensate for these drawbacks in recent years,
Attempts are being made to develop polystyrene resins having semi-permanent antistatic properties by using other hydrophilic polymers as electrostatic materials. As an example of such a proposal, the present inventors have found a method of blending a polystyrene-based resin with a potassium ionomer of an ethylene / unsaturated carboxylic acid copolymer containing a considerable amount of potassium ions.
No. 26008 and Japanese Patent Application No. 6-281624.

[0004]

However, in the formulation examples specifically disclosed therein, the compatibility of the composition may not always be sufficient, and the impact strength may be insufficient due to the use and the layered structure may not be obtained. There is a risk that problems such as peeling may become apparent. Therefore, the inventors of the present invention have conducted extensive studies to find a modifier having a sufficiently large impact resistance improving effect and a good compatibility with a polystyrene resin. As a result, they have found that the object can be achieved by using the epoxy group-containing ethylene copolymer described below. Incidentally, JP-A-63-137944 and JP-A-64-5676.
No. 2 publication proposes a method of blending an epoxy-containing olefin copolymer with a polymer having a functional group such as a carboxyl group, a hydroxyl group or a nitrogen-containing base for the purpose of matting an ABS resin. An ionomer is exemplified as an example of the latter polymer, but no description is given of its properties. As is clear from the Examples and Comparative Examples, the above-mentioned blended polymers are ABS.
It does not impair or improve the impact resistance of the system resin, the epoxy-containing olefin copolymer is used only for the purpose of matting, and the latter polymer is added for the purpose of preventing the deterioration of flowability. However, since the problem to be solved is completely different, the present invention is not suggested. Further, the ionomer used in the present invention does not have the matting effect of the ABS resin.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an alkali metal ion source containing 74.9 to 98.9 parts by weight of a thermoplastic styrene resin and 0.4 to 4 mol / kg ionomer of an alkali metal as an ion source. The thermoplastic resin composition comprises 25 to 1 part by weight of an ionomer of an ethylene / unsaturated carboxylic acid copolymer and 0.1 to 10 parts by weight of an epoxy group-containing ethylene copolymer.

The thermoplastic styrene resin which can be used in the present invention is a homopolymer or copolymer of styrene, and ABS resin and polystyrene are typical examples thereof. Here, the ABS resin is a generic term for rubber-reinforced styrene polymers synthesized by various manufacturing methods such as a blending method, a grafting method, or a graft-blending method, and includes polybutadiene, styrene-butadiene rubber, and ethylene. Representative examples include those obtained by graft-polymerizing styrene and other monomers such as acrylonitrile, methyl methacrylate, α-methylstyrene, ethylene bismaleimide, and maleimide to a rubber component such as propylene / diene rubber.

Further, polystyrene is not only general-purpose polystyrene synthesized by a production method such as suspension polymerization method or continuous polymerization method, but also impact-resistant polystyrene obtained by graft-polymerizing styrene with a rubber component such as butadiene rubber. Etc. are collectively referred to. Among these thermoplastic styrene resins, it is particularly preferable to use a diene rubber reinforced ABS resin.

The ionomer which can be used in the present invention has a structure in which a part or all of the carboxyl groups of the ethylene / unsaturated carboxylic acid random copolymer are neutralized with an alkali metal. Examples of the unsaturated carboxylic acid component in the copolymer include acrylic acid, methacrylic acid, fumaric acid, maleic acid monomethyl ester, maleic acid monoethyl ester, and maleic anhydride. Further, the above-mentioned ethylene / unsaturated carboxylic acid random copolymer contains other unsaturated monomer components such as (meth)
Acrylic ester or methacrylic acid ester such as methyl acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, or unsaturated ester such as vinyl acetate is copolymerized. It may have been done. Further, two or more kinds having different unsaturated carboxylic acid component units may be used. Such a copolymer can be obtained by randomly copolymerizing each polymerization component under high temperature and high pressure.

As an ion source for neutralizing the carboxyl group of the above copolymer to form an ionomer, alkali metals, that is, lithium, sodium, potassium, rubidium and cesium are used, and potassium is particularly preferable.

The ionomer of the present invention thus obtained has an ethylene component of 60 to 95% by weight, particularly 70 to 9%.
0% by weight, unsaturated carboxylic acid component, that is, 5 to 40% by weight of unsaturated carboxylic acid and unsaturated carboxylic acid salt component,
Particularly, 10 to 30% by weight, and other unsaturated monomer components are 0
It is preferable that they are copolymerized in a proportion of from -30% by weight, particularly from 0 to 20% by weight.

The content of the alkali metal cation in the ionomer component is 1 kg of the ionomer from the viewpoint of antistatic property.
It is desirable that the amount is in the range of 0.4 to 4 mol, preferably 0.6 to 2 mol. Further, it is preferable to use the ionomer having a neutralization degree (average neutralization degree when two or more kinds of ionomers are used) of 60 mol% or more, particularly 70 mol% or more.

In the ionomer component of the present invention, a plasticizer for improving antistatic performance and processability, such as polyoxyalkylene polyol, polyhydric hydroxy compounds such as glycerin and trimethylolpropane, and the like are contaminated by bleeding and the like. May be added in a range which does not cause, for example, 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of the ionomer component.

Typical examples of the epoxy group-containing ethylene copolymer that can be used in the present invention include random copolymers of ethylene and glycidyl (meth) acrylate such as glycidyl acrylate and glycidyl methacrylate. it can. Here, other unsaturated monomer components, for example, acrylic acid ester such as methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate or methacrylic acid. An acid ester or an unsaturated ester such as vinyl acetate may be copolymerized.

The epoxy group-containing ethylene copolymer of the present invention has an ethylene component of 60 to 98% by weight, especially 70 to
88% by weight, 2% of glycidyl (meth) acrylate component
20% by weight, particularly 3 to 15% by weight, and ethylene / glycidyl (meth) acrylate copolymerization in which other unsaturated monomer components are copolymerized at a rate of 0 to 40% by weight, particularly 0 to 30% by weight. Preference is given to coalescing. Such a copolymer can be obtained by randomly copolymerizing each polymerization component under high temperature and high pressure.

Styrene resin component (A component), ionomer component (B component) of ethylene / unsaturated carboxylic acid copolymer having an alkali metal as an ion source, and epoxy group-containing ethylene copolymer component (C component) The mixing ratio of A is
74.9-98.9% by weight of component, preferably 80-96
The component B is 1 to 25% by weight, preferably 3 to 100% by weight.
It is 20% by weight, and the C component is 0.1 to 10% by weight, preferably 0.2 to 5% by weight. If the amount of B component is less than the above range, the antistatic effect is not sufficient, and if the amount of B component is more than the above range, the properties such as rigidity and molding processability originally possessed by the styrene resin are impaired, and the hygroscopicity is increased. The foaming phenomenon is likely to appear. If the amount of the C component is less than the above range, the impact resistance improving effect is not sufficient, and if the amount of the C component is more than the above range, properties such as rigidity and molding processability originally possessed by the styrene resin are impaired.

The thermoplastic resin composition of the present invention contains optional additives such as an antioxidant, a weather resistance stabilizer, and the like depending on the purpose.
An ultraviolet absorber, a slip agent, a pigment, a cross-linking agent, a foaming agent, a tackifier, an inorganic filler and the like can be added. The thermoplastic resin composition of the present invention may be blended with another thermoplastic resin in a small amount.

[0017]

EFFECT OF THE INVENTION The polystyrene resin composition according to the present invention has remarkably improved impact resistance without substantially impairing the desirable properties of the semi-permanent non-chargeable polystyrene resin. Therefore, it can be widely used in various fields where various antistatic properties are required, such as automobile parts, OA equipment, home appliance parts, storage / storage cases thereof, stationery and daily necessities.

[0018]

EXAMPLES The present invention will be specifically described with reference to the following examples. The composition and physical properties of the raw material resins used for blending the compositions of Examples and Comparative Examples, and the methods for measuring the physical properties of the obtained resin compositions are as follows.

1. Raw material resin (1) ABS resin: ABS resin N manufactured by Nippon Synthetic Rubber Co., Ltd.
P10 (2) Ionomer resin composition: Composition: 82% of ethylene / methacrylic acid copolymer (methacrylic acid 12.5% by weight) Neutralized potassium salt (metal cation content 1.2 mol / Kg ionomer) ・ ・ ・ 91% by weight % Glycerin ... 9% by weight MFR: 6 g / 10 min (190 ° C.) (3) Ethylene / n-butyl acrylate / glycidyl methacrylate random copolymer: Copolymerization composition: Ethylene 67% by weight n-butyl acrylate 28 % By weight Glycidyl methacrylate 5% by weight MFR: 12 g / 10 min (190 ° C.) (4) Ethylene / glycidyl methacrylate random copolymer: Copolymer composition: 88% by weight ethylene 12% by weight glycidyl methacrylate MFR: 3 g / 10 min ( 190 ° C)

2. Measurement method (1) Surface resistivity A 2 mm thick test piece prepared by injection molding was aged at 23 ° C and relative humidity of 30% and 50% for 24 hours, and then the surface resistivity under each relative humidity was measured by Mitsubishi Oil. It was measured with a chemical resistance meter (HIRESTA-IP). Moreover, the durability of the antistatic effect was evaluated by wiping a test piece aged at 50% relative humidity for 24 hours with a dry cloth (cotton) 60 times and then measuring the surface resistivity under the same humidity.

(2) DuPont Impact Strength A 2 mm-thick test piece prepared by injection molding was aged at 23 ° C. and 50% relative humidity for 24 hours, and then a 1 kg load weight with a 1/4 R punch at the tip was placed on the test piece. After dropping from a predetermined height, the impacted portion was observed from the back side to check the presence or absence of fracture, and the impact resistance energy (kg.cm) was calculated from the maximum height at which fracture did not occur.

(3) Bending Fracture Test A 2 mm-thick test piece prepared by injection molding was repeatedly folded in two, and the number of times until peeling was observed at the bent portion was measured.

(4) MFR 220 ° C., 2160 g load, weight of molten polymer flowing out from melt indexer in 10 minutes (g / 10 mi)
n) was measured.

(5) Heat Deformation Temperature Using a 2 mm thick test piece prepared by injection molding, 1
The heat distortion temperature was measured according to JIS K7207 under a load of 8.6 kg.

[Examples 1 to 4] ABS resin, ionomer resin composition, and ethylene / n-butyl acrylate / glycidyl methacrylate copolymer (EBAGMA) or ethylene / glycidyl methacrylate copolymer (EGM)
A) was mixed in the composition shown in Table 1 and then twin-screw extruder (3
It was melt-kneaded at 230 ° C. using a 0 mm diameter, coaxial rotation). The obtained ABS resin composition was injection-molded at a molding temperature of 240 ° C. and a mold temperature of 50 ° C. to prepare a test piece having a shape defined by each test method. Various physical property values were measured for this test piece, and the results are shown in Table 1. As is clear from Table 1, the compositions of Examples 1 to 4 have good semi-permanent antistatic properties, and also have significantly improved impact resistance and flex fracture resistance.

Comparative Example 1 Example 1 using ABS resin alone
In the same manner as above, injection molding was carried out at a molding temperature of 240 ° C. and a mold temperature of 50 ° C. to prepare test pieces having a shape defined by each test method. Various physical property values were measured for this test piece, and the results are shown in Table 1. As is clear from Table 1, this system containing no ionomer resin composition has a large electric resistance and is easily charged.

[Comparative Example 2] ABS resin and ionomer resin composition were mixed in the composition shown in Table 1, melt-kneading and injection molding were carried out in the same manner as in Example 1, and a test piece having a shape defined by each test method was used. Was produced. Various physical property values were measured for this test piece, and the results are shown in Table 1. As is clear from Table 1, this composition containing no ethylene / n-butyl acrylate / glycidyl methacrylate copolymer was
Shows good semi-permanent antistatic performance, but is extremely inferior in impact resistance and flex fracture resistance.

[0028]

[Table 1]

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Claims (6)

[Claims] 1. A thermoplastic styrene resin 74.9-9.
8.9 parts by weight, 25 to 1 parts by weight of an ethylene / unsaturated carboxylic acid copolymer ionomer containing an alkali metal as an ion source, which contains an alkali metal in a proportion of 0.4 to 4 mol / kg ionomer, and an epoxy group A thermoplastic resin composition comprising 0.1 to 10 parts by weight of a contained ethylene copolymer. 2. The composition according to claim 1, wherein the degree of neutralization of the ionomer with an alkali metal is 60 mol% or more. 3. The alkali metal is potassium.
Or the composition according to 2. 4. The composition according to claim 1, wherein the thermoplastic styrene resin component is a diene rubber reinforced ABS resin. 5. The composition according to any one of claims 1 to 4, wherein the epoxy group-containing ethylene copolymer is an ethylene / glycidyl (meth) acrylate copolymer. 6. Per 100 parts by weight of the ionomer component,
The composition according to claims 1 to 5, which comprises a polyhydric hydroxy compound in a proportion of 0.1 to 20 parts by weight.