JPS6333437A - Thermoplastic rubber composition - Google Patents

Abstract

PURPOSE:To provide a thermoplastic rubber composition containing a specific chloroprene rubber, a carboxyl-containing vinyl chloride resin, a univalent or bivalent metal compound and a plasticizer. usable without vulcanization and having excellent high-temperature creep resistance and weather resistance. CONSTITUTION:The objective thermoplastic rubber composition can be produced by mixing (A) a chloroprene rubber containing >=10(wt)%, preferably 30-98% gel component insoluble in toluene, (B) a carboxyl-containing vinyl chloride resin (preferably having a carboxyl group content of 0.2-10%), (C) a univalent or bivalent metal compound (e.g. magnesium acetylacetonate) and (D) a plasticizer (e.g., di-2-ethylhexyl phthalate). Preferably, the ratio of A:B is 1:9-8:2, the amount of the component D is 20-300pts.(wt.) per 100pts. of the component B and that of the component C is 0.1-3mol-equivalent based on the carboxyl group of the component B.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thermoplastic rubber composition, and more particularly, to a thermoplastic rubber composition that does not require vulcanization and has excellent high-temperature creep properties and weather resistance. .

(Prior art) Chloroprene rubber has excellent weather resistance, oil resistance, heat resistance, flame retardancy, etc., and is widely used in automobile parts and other applications due to these properties, but it is of course assumed that it will be sulfurized by cams. becomes.

On the other hand, vinyl chloride resin containing a plasticizer, known as soft vinyl chloride resin, has a flexible, rubber-like feel.
Compared to vulcanized rubber, it has superior moldability, cost, weather resistance, colorability, etc., and is widely used. However, since it is inferior to vulcanized rubber in terms of creep properties at high temperatures, its use at high temperatures is limited. Therefore, attempts have been made to improve the creep characteristics by using vinyl chloride resins with a high degree of polymerization or those containing a rel content. Furthermore, a method is known in which the compression set is improved by adding a crosslinked rubber substance to a vinyl chloride resin containing a dull content (% 1987-215442, 59-51933).

However, even with these methods, it is difficult to improve the high temperature creep properties (particularly compression set and impact resilience) at temperatures of 100° C. or higher.

Therefore, there is currently a strong demand for a thermoplastic rubber that can be thermoplastically processed and has high-temperature creep properties close to those of vulcanized rubber without vulcanization.

(Problems to be Solved by the Invention) In view of the above situation, the present inventors have conducted intensive research to solve the above problems, and have found that chloroprene rubber having an r-content, a carboxyl group-containing vinyl chloride resin, We have discovered that by using a composition containing a valent metal compound and a plasticizer as essential components, thermoplastic processing is possible and the high-temperature curing property is significantly improved without vulcanization. , we have completed the present invention.

(Means for Solving the Problems) Thus, according to the present invention, the amount insoluble in toluene is reduced to 1
Provided is a thermoplastic rubber composition comprising 0% by weight or more of chlorograin, a carboxy group-containing vinyl chloride resin, a monovalent or divalent metal compound, and a plasticizer.

The chloroprene rubber in the present invention is a polymer containing chloroglene as a main component, and in order to contain a gel component in this chloroprene rubber, molecules such as divinylbenzene, diallyl phthalate, diallyl maleate, trimethylolpropane triacrylate, etc. A method such as copolymerizing a monomer having a plurality of double bonds within the monomer, or generating intermolecular crosslinks through a post-treatment reaction using peroxide or the like may be adopted as appropriate.

The gel content that is insoluble in toluene refers to the amount of gel that is insoluble in toluene after adding 0.21 dK of chloroprene rubber to toluene and dissolving it at room temperature for 3 days and nights.
0m, refers to the residue filtered through wire mesh. The gel content is required to be 10% by weight or more, preferably 30% by weight or more.

If the gel content is less than 10% by weight, compression set, which is one of the high temperature creep characteristics, will not be sufficiently improved, which is not preferable.

Note that the upper limit of the gel content is not particularly limited, but in consideration of processability, it is preferably 98 inches or less.

In addition, as a carboxyl group-containing vinyl chloride resin, u, (1
) Vinyl chloride and monocals such as acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid? acidic acids or dicarnic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, monomethyl maleate, monoethyl maleate,
Copolymerized with dicarboxylic acid monoesters such as monoethyl maleate, monomethyl itaconate, monoethyl itaconate, and motuputyl itaconate, (2)
Vinyl chloride and α, β-unsaturated power? Examples include those obtained by copolymerizing and hydrolyzing with phosphoric acid esters, and (3) those obtained by addition-reacting a carboxylic acid-containing compound after producing a normal vinyl chloride polymer. 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 temperatures will not be sufficiently improved, and if it exceeds 20% by weight, it is often pointless or undesirable due to other characteristics.

Although the average degree of polymerization of the vinyl chloride resin is not particularly limited, it is usually 500 to s, ooo, and a vinyl chloride resin containing a rr content that is insoluble in tetrahydrofuran may be used.

Monovalent or divalent metal compounds include Ll+tNa'',
+, Cs”, Mg”, Ca”, Ba”, Zn”+Cd
Metal oxides, hydroxides, acetates, propionates, octylates, caprates, stearates, etc.
Examples include calylates such as naphthenates, thiocarnates, sulfonates, phosphates, and complex salts of the above metals with acetylacetone and the like. These may be used alone or in combination of two or more. The amount of the metal compound added is preferably 0.1 molar equivalent to 3 molar equivalent relative to the amount of carboxyl groups in the vinyl chloride resin. It is presumed that this metal compound acts as a so-called ionic crosslinking agent that ionically reacts with the carboxyl group in the vinyl chloride resin and crosslinks the vinyl chloride resin.

As the plasticizer, plasticizers that are generally used for soft vinyl chloride resins can be used, such as di-2-ethylhexyl 7-talate, di-n-octyl phthalate, diindecyl 7-talate, dibutyl phthalate, diallyl phthalate, etc. phthalate ester; dioctyl adipate,
Linear dibasic acid esters such as dioctyl sepacate; trimellitic acid esters, polyester polymer plasticizers; epoxy plasticizers such as epoxidized soybean oil and epoxidized linseed oil; triphenyl phosphate, tricresyl phosphate, etc. Phosphate ester plasticizers and the like may be used alone or in combination of two or more.

Chloroprene rubber and calzexyl Ti containing chloride +:'
The mixing ratio with Nil resin is in the range of 0.5:9.5 to 9:1,
Preferably it is 1:9 to 8:2. Mixing ratio is 0.5:
If the ratio is smaller than 9.5, a sufficient effect of improving compression set will not be exhibited, and if it exceeds 9:1, the melt fluidity will decrease and processing methods will be restricted, which is undesirable.

The amount of plasticizer used in the present invention is appropriately selected depending on the hardness of the target product, but when considering soft rubber-like products, the amount of plasticizer used is 20 to 300 parts by weight per 100 parts by weight of carboxyl group-containing vinyl chloride resin. preferable.

When producing the thermoplastic rubber composition in the present invention,
As in general vinyl chloride resin, stabilizers, lubricants,
Various additives such as fillers, antioxidants, ultraviolet absorbers, processing aids, blowing agents, pigments, flame retardants, and impact resistance aids can be added as necessary. Further, other polymers may be mixed.

(Effect of the invention) Excellent high-temperature creep properties and weather resistance can be obtained by molding the obtained composition using ordinary vinyl chloride resin processing methods such as extrusion molding, compression molding, calendar molding, blow molding, and injection molding. A molded product can be obtained.

This molded product can be suitably used for automobile window seal materials, electric wire sheath materials, packing materials, etc., which require the same characteristics.

(Example) The present invention will be described in more detail with reference to Examples below. Note that parts and parts in the examples are based on weight unless otherwise specified.

Example 1 The chloropre/rubber shown in Table 1, vinyl chloride resin, magnesium acetylacetonate, 100 parts of 2-ethylhexyl phthalate, and 4 parts of dibutyltin malate were kneaded for 10 minutes with a heated roll at 160°C to form a sheet. I got it.

These sheets were heated and pressed at 175° C. for 10 minutes to produce pressed test pieces of a predetermined thickness.

The rebound resilience of this press test piece was measured using a Dunlop trigon meter, BS, 903 Part A8: 196
3, it is expressed as the impact elasticity modulus @) measured at D140°C. The compression set was expressed as the compression set rate (A) after 70 hours at 100°C under 25% compression, as measured in accordance with JIS K-6301. Further, weather resistance was evaluated by observing the discoloration state of the test piece after 500 hours using a sunshine type sederometer. The results are shown in Table 1.

Example 2 The same toluene-insoluble gel content as used in Example 1, 100 parts of chloroglene, Cal? Xyl group content 1.81
Experiments and evaluations were conducted in the same manner as in Example 1, except that 100 parts of vinyl chloride resin with an average degree of polymerization of 2,500, 4 parts of dibutyl chloride malate, and the metal compounds and plasticizers shown in Table 2 were used. The results are shown in Table 2.

Claims (1)

[Claims] A thermoplastic rubber composition comprising chloroprene rubber containing 10% by weight or more of a gel content insoluble in toluene, a carboxyl group-containing vinyl chloride resin, a monovalent or divalent metal compound, and a plasticizer.