JPH0781059B2 - Thermoplastic elastomer composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermoplastic elastomer composition, and more particularly to a thermoplastic elastomer composition which does not require vulcanization and has excellent high temperature creep properties and weather resistance. .

(Prior Art) Acrylate-based elastomers have excellent heat resistance and weather resistance, and are widely used for automobile parts including their properties. Become.

On the other hand, vinyl chloride resin containing a plasticizer known as soft vinyl chloride resin has a soft rubber-like feel,
Compared with vulcanized rubber, it has excellent moldability, cost, weather resistance, colorability, etc. and is widely used. However, the creep property at high temperature is inferior to that of vulcanized rubber, so that use at high temperature is limited. Therefore, attempts have been made to improve the creep characteristics by using a vinyl chloride resin having a high degree of polymerization or containing a gel component. Further, a method of improving compression set by adding a cross-linked nitrile rubber to a vinyl chloride resin containing a gel component is also known (JP-A-58-215442, 59-51933). However, even by these methods, it is difficult to simultaneously improve the high temperature creep properties (particularly compression set, impact resilience) and weather resistance at 100 ° C. or higher.

Therefore, under the present circumstances, there is a strong demand for the appearance of a thermoplastic elastomer which can be thermoplastically processed and has high-temperature creep properties close to those of vulcanized rubber even without vulcanization.

(Problems to be Solved by the Invention) In view of such circumstances, the present inventor has conducted earnest research to solve the above-mentioned problems, and as a result, acrylate elastomer containing a specific amount of gel component, carboxyl group-containing vinyl chloride resin, By using a composition containing a divalent or divalent metal compound and a plasticizer as an essential component, thermoplastic processing is possible, and found that the high temperature creep properties are significantly improved even without vulcanization, The present invention has been completed.

(Means for Solving the Problems) Thus, according to the present invention, an acrylate elastomer having a gel content insoluble in methyl ethyl ketone of 10% by weight or more, a vinyl chloride resin containing a carboxyl group, a monovalent or divalent metal compound and a plastic compound. A thermoplastic elastomer composition comprising an agent is provided.

The acrylate-based elastomer used in the present invention is an acrylate homopolymer elastomer, ethylene-
Acrylate copolymer elastomer, ethylene-vinyl acetate-acrylate copolymer elastomer, acrylate-acrylonitrile copolymer elastomer, acrylate-vinyl acetate-acrylonitrile copolymer elastomer, acrylate-butadiene-acrylonitrile copolymer elastomer and the like. However, it is not particularly limited to these elastomers.

To add a gel component to this acrylate elastomer, divinylbenzene, diallyl phthalate, diallyl malate, trimethylolpropane tri (meth)
A method such as copolymerizing monomers having multiple double bonds in the molecule such as acrylate and triallyl trimellitate, or generating intermolecular crosslinks by post-treatment reaction using peroxide etc. is appropriately adopted. do it.

The gel component insoluble in methyl ethyl ketone means a residue which was obtained by adding 0.2 g of an acrylate elastomer kneaded with a water-cooled roll for 10 minutes to 100 ml of methyl ethyl ketone, dissolving at room temperature for 24 hours, and passing through an 80-mesh wire net. Gel content
It is required to be 10% by weight or more, preferably 30% by weight or more. When the gel content is less than 10% by weight, the compression set, which is one of the high temperature creep characteristics, is not sufficiently improved, which is not preferable.

Further, as the carboxyl group-containing vinyl chloride resin,
(1) Vinyl chloride and monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid and cinnamic acid, or dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid, and monomethylmalate and monoethylmalate Copolymerized with monoesters of dicarboxylic acid such as monobutyl maleate, monomethyl itaconate, monoethyl itaconate and monobutyl itaconate,
(2) Vinyl chloride and α, β-unsaturated carboxylic acid ester copolymerized and then hydrolyzed, and (3) ordinary vinyl chloride copolymer production, followed by addition reaction with a carboxylic acid-containing compound The thing etc. are mentioned. The carboxyl group content in this resin is usually 0.05 to 20% by weight, preferably 0.2.
~ 10% by weight. If it is less than 0.05% by weight, the impact resilience at high temperature is not sufficiently improved, and if it is contained in an amount exceeding 20% by weight, it is meaningless and in many cases it is not preferable because of other characteristics.
The average degree of polymerization of the vinyl chloride resin is not particularly limited, but is usually 500 to 5,000.

As the monovalent or divalent metal compound, Li ⁺ , Na ⁺ , K ⁺ , Cs ⁺ , M
g ⁺⁺ , Ca ⁺⁺ , Ba ⁺⁺ , Zn ⁺⁺ , Cd ⁺⁺ etc. Metal oxides, hydroxides, acetates, propionates, octylates, caprates, stearates, naphthenes Examples thereof include carboxylates such as acid salts, thiocarboxylates, sulfonates, phosphates, and complex salts of the above metals with acetylacetone.
These may be used alone or in admixture of two or more. The addition amount of the metal compound is preferably 0.1 mol to 3 mol with respect to the carboxyl group amount of the vinyl chloride resin. It is presumed that this metal compound acts as a so-called ionic cross-linking agent that ionically reacts with the carboxyl group in the vinyl chloride resin to cross-link the vinyl chloride resin.

As the plasticizer, a plasticizer generally used for soft applications of vinyl chloride resins can be used, and phthalic acid such as di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisodecyl phthalate, dibutyl phthalate and dihexyl phthalate can be used. Ester; linear dibasic acid ester such as dioctyl adipate, dioctyl sebacate;
Trimellitic acid ester, polyester-based polymer plasticizer; Epoxidized soybean oil, epoxidized linseed oil and other epoxy-based plasticizers; Triphenyl phosphate, tricresyl phosphate, and other phosphate ester-based plasticizers, either alone or in combination. A mixture of the above is used.

The mixing ratio of the acrylate elastomer and the carboxyl group-containing vinyl chloride resin is in the range of 0.5: 9.5 to 9: 1, preferably 1: 9 to 8: 2. If the mixing ratio is less than 0.5: 9.5, a sufficient effect of improving the compression set will not be exhibited, and if it exceeds 9: 1, the melt fluidity will be reduced, and the processing method will be restricted, such being undesirable.

The amount of the plasticizer used in the present invention is appropriately selected depending on the hardness of the intended product, but in order to obtain a soft rubber-like product, 20 to 300 parts by weight with respect to 100 parts by weight of the carboxyl group-containing vinyl chloride resin. Parts are preferred.

In the production of the thermoplastic elastomer composition of the present invention, as in general vinyl chloride resins, stabilizers, lubricants, fillers, antioxidants, ultraviolet absorbers, processing aids, foaming agents, pigments, flame retardants, Various additives such as impact resistance assistants can be added as necessary. Also, other polymers may be mixed.

(Effect of the invention) By molding the obtained composition by a usual vinyl chloride resin processing method such as extrusion molding, compression molding, calender component, blow molding, injection molding, a molded article excellent in high temperature creep property and weather resistance can be obtained. can get. This molded product can be suitably used for automobile wind seal materials, electric wire sheath materials, packings, etc., which are required to have such characteristics.

(Example) Hereinafter, the present invention will be described more specifically with reference to Examples. Parts and% in the examples are based on weight unless otherwise specified.

Example 1 Acrylate elastomer shown in Table 1, vinyl chloride resin, magnesium acetylacetonate and di-2-
100 parts of ethylhexyl phthalate and 4 parts of dibutyl tin malate were kneaded with a hot roll at 160 ° C. for 10 minutes to obtain a sheet. These sheets were hot-pressed at 175 ° C. for 10 minutes to prepare pressed test pieces with a predetermined thickness.

The impact resilience of this pressed test piece was expressed as the impact resilience (%) measured at 140 ° C. by BS 903 Part A8: 1963 using a Dunlop trypsometer. Compression set is JISK
It was expressed as the compression set (%) after 70 hours at 100 ° C. at 25% compression measured by −6301. The weather resistance was evaluated by observing the discolored state of the test piece after 500 hours with a sunshine weatherometer. The results are shown in Table 1.

Example 2 Methyl ethyl ketone insoluble gel 90% butyl acrylate-acrylonitrile copolymer (butyl acrylate:
Acrylonitrile weight ratio 75:25) 100 parts, carboxyl group content 1.8%, vinyl chloride resin 100 parts with an average degree of polymerization of 2,500,
4 parts of dibutyltin malate and the metal compounds shown in Table 2,
The same experiment and evaluation as in Example 1 were carried out except that a plasticizer was used. The results are shown in Table 2.

Claims (1)

[Claims] 1. A heat comprising an acrylate elastomer having a gel content of 10% by weight or more insoluble in methyl ethyl ketone, a vinyl chloride resin containing a carboxyl group, a monovalent or divalent metal compound and a plasticizer. Plastic elastomer composition.