JPH08226539A - Rubber boots - Google Patents

Abstract

PURPOSE: To improve ozone resistance greatly by using chloroprene rubber component having chloroprene rubber and α,β-unsaturated carboxylic acid ester polymer as essential components. CONSTITUTION: Chloroprene rubber component having chloroprene rubber which is a polymer or a copolymer obtained by single 2-chloro-1,3-gutadiene or polymerizing chloroprene and more than one kind of monomer which can be copolymerized with chloroprene and α,β-unsaturated carboxylic acid ester polymer which is a copolymer obtained by copolymerizing single polymer of α,β-unsaturated carboxylic acid ester or two kinds or more of α,β-unsaturated carboxylic acid ester as essential components is used. Consequently, it is possible to realize boots which excel in ozone resistance when compared with those made of single chloroprene rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chloroprene rubber type boot having excellent ozone resistance.

[0002]

BACKGROUND OF THE INVENTION Chloroprene rubber is widely used industrially as a synthetic rubber having a good balance of physical properties such as general rubber physical properties, weather resistance, heat resistance, cold resistance and chemical resistance. In the field of the automobile industry, it is widely used for belts, hoses and the like, but in recent years, the demand as boot materials has been expanding especially. Specifically, constant velocity joint boots,
Rack and pinion boots, ball joint boots and the like can be mentioned. For these purposes, chloroprene rubber is preferably used because of its large mechanical load and chemical load. However, in recent years, as the performance of vehicles has advanced, the demands on the quality and physical properties of rubber materials have become increasingly high, and in particular, there is a strong demand for improvement in ozone resistance of chloroprene rubber boot materials.

As a means for improving the ozone resistance of chloroprene rubber, a method of adding an antioxidant is generally used and widely used. However, in this method, unvulcanized products are burnt and blooming of the antioxidant is carried out. However, there is a problem that the tensile strength of the vulcanized product is lowered, and the cost of rubber products is increased due to the need for expensive anti-aging agents, and the effect of improving ozone resistance was not sufficient. .

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a chloroprene rubber type boot having a significantly improved ozone resistance.

[0005]

As a raw material for rubber boots, the present inventors have found that a rubber composition obtained by mixing chloroprene rubber with an α, β-unsaturated carboxylic acid ester polymer is excellent in ozone resistance. The invention was completed.

That is, the present invention relates to a rubber boot using a chloroprene rubber and a chloroprene rubber composition containing an α, β-unsaturated carboxylic acid ester polymer as an essential component.

Hereinafter, the present invention will be described in more detail. The chloroprene rubber referred to in the present invention means 2-chloro-1,3
-Butadiene (hereinafter referred to as chloroprene) alone or a polymer or copolymer obtained by polymerizing one or more of chloroprene and a monomer copolymerizable with chloroprene.

Examples of the monomer copolymerizable with chloroprene of the present invention include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene,
Examples thereof include isoprene, sulfur, styrene, acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and two or more kinds may be used if necessary.

Polymerization of chloroprene alone or a monomer mixture containing chloroprene and a monomer copolymerizable therewith in the present invention can be carried out by any known method, but radical polymerization is carried out in an aqueous emulsion. The method is the most general and simple.

When carrying out the aqueous emulsion polymerization, the emulsifier is not particularly limited, and any emulsifier generally used for emulsion polymerization of chloroprene may be used. For example, anionic emulsifiers such as rosin acid salts, fatty acid salts and alkylbenzene sulfonates, nonionic emulsifiers such as alkyl polyethylene glycols and polyvinyl alcohol, and cationic emulsifiers such as quaternary ammonium salts can be used. Anionic emulsifiers such as rosin acid salts and fatty acid salts are preferred.

The polymerization temperature can be set in a wide range,
It is preferably in the range of 0 to 55 ° C. At temperatures lower than 0 ° C., water coagulation becomes a problem, and at temperatures higher than 55 ° C., pressure equipment is required due to the vapor pressure of chloroprene.

The molecular weight of chloroprene rubber can be controlled by using a chain transfer agent. Any known chain transfer agent may be used, and examples thereof include alkyl mercaptans such as dodecyl mercaptan, xanthogen disulfides such as diethylxanthogen disulfide, and halogenated hydrocarbons such as iodoform.

The polymerization initiator may be an organic or inorganic peroxide used in a usual chloroprene emulsion polymerization method, for example, benzoyl peroxide, potassium persulfate,
Examples thereof include ammonium persulfate. Further, a redox type radical initiator may be used for the purpose of controlling the reaction and completely carrying out the polymerization.

In the present invention, the α, β-unsaturated carboxylic acid ester polymer is a homopolymer of α, β-unsaturated carboxylic acid esters or two or more kinds of α, β-unsaturated carboxylic acid esters. It is a copolymer of copolymers.

Here, the α, β-unsaturated carboxylic acid ester is an ester composed of α, β-unsaturated carboxylic acid and alcohol, and the α, β-unsaturated carboxylic acid is, for example, acryl. Acids, methacrylic acid, crotonic acid, maleic acid, fumaric acid and the like can be mentioned.

As alcohols, ethyl alcohol, butyl alcohol, octyl alcohol, 2-
Alkyl alcohols such as ethylhexyl alcohol, dodecyl alcohol and octadecyl alcohol, alkenyl alcohols such as allyl alcohol, cyclic alcohols such as cyclopentyl alcohol and cyclohexyl alcohol, aralkyl alcohols such as benzyl alcohol and phenethyl alcohol, methoxyethyl alcohol and glycidyl alcohol. , Dialkylaminoethyl alcohol and the like.

Although any known method can be used for the method for polymerizing the α, β-unsaturated carboxylic acid ester polymer of the present invention, the method by emulsion radical polymerization is simple and preferable.

The α, β-unsaturated carboxylic acid ester polymer may be copolymerized with a monomer other than the α, β-unsaturated carboxylic acid ester as long as the effects of the present invention are not impaired. Monomers other than α, β-unsaturated carboxylic acid esters include acrylic acid, methacrylic acid, acrylonitrile, ethylene, propylene, styrene, vinyl acetate, vinyl chloride, isoprene, butadiene, chloroprene, 1
-Chloro-1,3-butadiene, 2,3-dichloro-
Examples include 1,3-butadiene and the like.

The emulsifier for emulsion polymerization of the α, β-unsaturated carboxylic acid ester is not particularly limited, and various emulsifiers can be used as in the case of chloroprene rubber.

The molecular weight of the α, β-unsaturated carboxylic acid ester polymer is not particularly limited, but in order to obtain more preferable general physical properties, the number average molecular weight is preferably 300,000 or more. Chain transfer agents used for molecular weight control include
Generally known chain transfer agents can be used, and examples thereof include alkyl mercaptans such as dodecyl mercaptan, xanthogen disulfides such as diethyl xanthogen disulfide, and halogenated hydrocarbons such as iodoform.

The polymerization temperature can be set within a wide range,
It is preferable to select between 0 and 90 ° C. At 0 ° C. or lower, water coagulation becomes a problem, and at 90 ° C. or higher, water evaporation becomes a problem.

The chloroprene rubber and the α, β-unsaturated carboxylic acid ester polymer may be mixed by any method, for example, the chloroprene rubber latex obtained by emulsion polymerization and the α, β-unsaturated carboxylic acid ester polymer emulsion. A method of mixing, a method of kneading solid polymers with each other, a method of blending solutions dissolved in an organic solvent, or the like can be used, but since the mixing can be performed easily and uniformly, and at a low cost, etc. The method of blending the latex and the emulsion is practical and preferable.

The rubber boot of the present invention comprises a rubber composition obtained by mixing chloroprene rubber and an α, β-unsaturated carboxylic acid ester polymer, kneading and kneading a usual rubber compounding agent, and vulcanizing after molding. Obtained.

Examples of the compounding agents include fillers such as various carbon blacks, silicas, clays, calcium carbonates, talcs, plasticizers such as dioctyl phthalate, dioctyl adipate, dioctyl azelate and dioctyl sebacate, paraffins, naphthenes, Aromatic process oil, rapeseed oil, linseed oil, castor oil and other vegetable oils, processing aids such as stearic acid and paraffin wax, metal oxides, thiourea vulcanization accelerators such as ethylenethiourea and trimethylthiouree, and various aging prevention Examples include agents. The type, combination, usage amount, etc. of these can be appropriately determined.

Regarding the rubber boot of the present invention, the ozone resistance thereof is essentially improved, but the ozone resistance can be further improved by appropriately using an antioxidant. As an anti-aging agent, phenyl-α
-Naphthylamines such as naphthylamine, 4,4'-
Diphenylamines such as dioctyl diphenylamine and reaction products of diphenylamine and diisobutylene,
N, N'-diphenyl-p-phenylenediamine, N-
Isopropyl-N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-phenyl-N '-( 3-methacryloyloxy-2-hydroxypropyl) -p-phenylenediamine, N, N'-bis (1-methylpeptyl)-
p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N '
-Bis (1-ethyl-3-methylpentyl) -p-phenylenediamine, N- (1,3-dimethylbutyl)-
N'-phenyl-p-phenylenediamine, N- (1,
3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, p-phenylenediamine system such as a mixture of diallyl-p-phenylenediamine, 6-ethoxy-
Quinoline compounds such as 2,2,4-trimethyl-1,2-dihydroquinoline, hydroquinone derivatives such as 2,5-di- (tertiary butyl) hydroquinone, phenol compounds, hindered phenol compounds, phosphite compounds. Antiaging agents, etc. can be mentioned, and these can be used alone or in combination of two or more.

The method of adding and mixing the compounding agent is not particularly limited, and methods such as open roll, kneader, Banbury mixer and the like used for ordinary rubber can be used.
The molding and vulcanization methods are also not particularly limited, and methods such as injection molding vulcanization and blow molding vulcanization that are usually applied to rubber boots are used.

[0027]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples. Hereinafter, parts and% are shown by weight.

Production of chloroprene rubber latex-1 To 3 liters of glass Kolben, under a nitrogen stream, water 1
00 parts, disproportionated rosin acid 5 parts, potassium hydroxide 1.0
Parts, 0.8 parts of sodium salt of formaldehyde naphthalene sulfonic acid condensate, and after dissolution, while stirring,
Chloroprene 100 parts and n-dodecyl mercaptan 0.
A mixture with 1 part was added. At a polymerization temperature of 40 ° C, polymerization was started using potassium persulfate, and the conversion rate of the monomer was 65%.
When the temperature reached 1, the polymerization was terminated by adding tert-butylcatechol and thiodiphenylamine, and unreacted monomers were removed under reduced pressure to obtain a chloroprene rubber latex.

Production of chloroprene rubber latex-2 The same procedure as in the production of chloroprene rubber latex-1 except that 95 parts of chloroprene and 5 parts of 2,3-dichloro-1,3-butadiene were used instead of 100 parts of chloroprene. A chloroprene rubber latex was obtained.

.Alpha. ,. Beta.-Unsaturated carboxylic acid ester polymerization
Body preparation 3 liters of glass Kolben in a nitrogen stream under water 1
00 parts and 5 parts of sodium dodecylbenzenesulfonate were charged and dissolved, and then n-dodecyl mercaptan 0.025 was added.
Parts, 100 parts of n-butyl acrylate were added with stirring. Polymerization was started using potassium persulfate at a polymerization temperature of 70 ° C., and polymerization was performed until the monomer conversion rate reached 98% to obtain an n-butyl acrylate polymer emulsion.

This n-butyl acrylate polymer emulsion was freeze-dried and subjected to gel permeation chromatography (Shimadzu Corporation) using polystyrene as a standard substance.
The number average molecular weight was measured by GPC), and the result was 500,000 (in terms of polystyrene).

The chloroprene rubber latex-1 and the n-butyl acrylate polymer emulsion thus synthesized were
A chloroprene rubber composition (A) was obtained by mixing the n-butyl acrylate polymer in an amount of 5 parts (in terms of solid content) with 100 parts of the chloroprene rubber and then freeze-drying the mixture.

Further, chloroprene rubber latex-2 and n-butyl acrylate polymer emulsion were mixed in a ratio of 5 parts (solid content) of n-butyl acrylate polymer to 100 parts of chloroprene rubber, followed by freeze-coagulation drying method. A chloroprene rubber composition (B) was obtained.

Chloroprene rubber (C) was obtained from the latex of chloroprene rubber alone by freeze coagulation and drying.

Examples 1 to 3 and Comparative Example 1 The above A, B and C were made into vulcanized products according to the formulations shown in Table 1 and subjected to physical property tests in accordance with JIS-K6301.
The results are shown in Tables 1 and 2. Examples 1 and 3 and Comparative Example 1 are comparisons with the same formulation, but the ozone resistance of the Examples is remarkably improved. Also, in Example 2 in which the anti-aging agent was omitted in the compounding formulation, the ozone resistance was obviously superior to the comparative example.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

As described above, the rubber composition of the present invention in which the α, β-unsaturated carboxylic acid ester polymer is mixed with the chloroprene rubber has remarkably excellent ozone resistance as compared with the chloroprene rubber alone. . In addition, it has a high level of ozone resistance and excellent physical properties that cannot be achieved by conventional antiaging agents. Therefore, the rubber composition of the present invention is expected to be applied to applications other than boots.

Claims (2)

[Claims] 1. A rubber boot using a chloroprene rubber composition containing chloroprene rubber and an α, β-unsaturated carboxylic acid ester polymer as essential components. 2. The rubber boot according to claim 1, wherein the α, β-unsaturated carboxylic acid ester polymer is a polymer of n-butyl acrylate.