JP3186122B2 - Chloroprene rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chloroprene rubber composition excellent in light discoloration resistance and heat discoloration resistance.

[0002]

2. Description of the Related Art Chloroprene rubber is widely used as an automobile part and various other industrial articles because of its balanced properties such as oil resistance, mechanical strength and ozone resistance. Further, chloroprene rubber having high crystallinity or a graft polymer obtained by graft-polymerizing methyl methacrylate onto chloroprene rubber is widely used as a rubber adhesive in a state of being dissolved in a solvent. However, since chloroprene rubber is relatively easily colored by light or heat, it is rarely used for transparent, white or colored products. To overcome this drawback, various antioxidants and stabilizers are used. However, it is difficult to simultaneously improve light discoloration resistance and heat discoloration resistance, and stabilizers that simultaneously improve these properties have been demanded.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a chloroprene rubber composition which simultaneously improves light discoloration resistance and heat discoloration resistance.

[0004]

Means for Solving the Problems The present inventors have studied methods for improving the light discoloration resistance and the heat discoloration resistance of a chloroprene rubber composition. As a result, the chloroprene rubber has a benzotriazole compound having a specific structure and a methylene chloride. It has been found that a chloroprene rubber composition excellent in light stability and heat discoloration resistance can be obtained by blending a bis-tert-butylphenol compound, and the present invention has been achieved.

That is, the present invention relates to (A) chloroprene rubber, (B) a benzotriazole compound represented by the following general formula (I), and (C) methylene-bis represented by the following general formula (II). -A chloroprene rubber composition containing tertiary butyl phenol compounds.

[0006]

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[0007]

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Hereinafter, the present invention will be described in detail. The chloroprene rubber used in the present invention refers to a homopolymer of 2-chlorobutadiene-1,3 or a chloroprene copolymer composed of a monomer copolymerizable therewith. Here, as the copolymerizable monomer, 1-chlorobutadiene-1,3,
Examples thereof include 2,3 dichlorobutadiene-1,3, methyl methacrylate, methacrylic acid, styrene, and sulfur. The polymerization conditions are not particularly limited, but the polymerization temperature is from 0 to 50 in view of the reactivity of each monomer in the copolymer system.
° C and the polymerization rate are 5 considering the productivity and gel suppression.
0-80% is preferred.

Next, the benzotriazole compound used in the present invention is represented by the above general formula (I). Preferred examples of the benzotriazole-based compound include 2- (3 ′, 5′-di-tert-butyl-).
2'-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3'-t-butyl-5'-methyl-2 '
-Hydroxyphenyl) -5-chlorobenzotriazole and the like.

The methylene-bis-tert-butylphenol compound is represented by the above general formula (II). Among them, preferred examples of the methylene-bis-tert-butylphenol-based compound include:
2,2'-methylene-bis- (4-methyl-6-t-butylphenol) and the like can be mentioned.

Further, as a method for producing a graft polymer obtained by graft-polymerizing methyl methacrylate onto chloroprene rubber used in the present invention, a method in which methyl methacrylate monomer is added to a solution of chloroprene rubber dissolved in an organic solvent, A solution polymerization method in which graft polymerization is performed on chloroprene rubber under an initiator is generally used, but an emulsion polymerization method in which a methyl methacrylate monomer is directly added to an emulsion of chloroprene rubber and graft polymerization is performed under a radical initiator is also used. The polymerization method for obtaining is not particularly limited.

The compounding amount of the benzotriazole compound of the general formula (I) is based on 100 parts by weight of chloroprene rubber.
It is preferably at least 0.1 part by weight, more preferably at least 0.3 part by weight, and the methylene-bis-tert-butylphenol compound of the general formula (II) is preferably at least 0.1 part by weight, more preferably at least 0.1 part by weight. 0.3 parts by weight or more. Benzotriazole compounds and methylene-bis-
If the amount of the tertiary butylphenol compound is too small, sufficient light discoloration resistance and heat discoloration resistance cannot be obtained.

There are no particular restrictions on the operation methods and procedures involved in the compounding step and the vulcanizing step, and the order of addition of the compounding chemicals. But it is good.

The chloroprene rubber composition of the present invention contains, in addition to the essential components (A), (B) and (C) described in the claims, vulcanizing agents, vulcanization accelerators, fillers and softening agents which are generally used. ,
Suitable amounts of plasticizers, processing aids, antioxidants, stabilizers and the like can be included. In addition, the adhesive contains an appropriate amount of generally used resins, metal oxides, fillers, solvents, antioxidants and stabilizers in addition to the above-mentioned essential components (A), (B) and (C). Can be made.

[0015]

EXAMPLES The present invention will be described below in more detail with reference to Examples and Comparative Examples, but it is needless to say that the present invention is not limited thereto. All the ingredients used are shown on a weight basis.

Examples 1 to 6, Comparative Examples 1 to 6 and Comparative Examples 9 to 16 A chloroprene rubber toluene solution obtained by dissolving 15 parts by weight of chloroprene rubber in 85 parts by weight of toluene was added to Table 1,
After making a uniform solution with the composition shown in Tables 2 and 3, it was applied on a pure white EVA sponge and subjected to each test.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

[Table 3]

The light resistance test was performed by Shimadzu Corporation.
The color 5 hours after irradiation was evaluated using a sunshine weather meter. The evaluation was performed by visual judgment and a colorimetric colorimeter (製 80 Color Measu) manufactured by Nippon Denshoku Industries
ring System). The degree of discoloration by the colorimeter is JIS P8123 and JIS
Hunter whiteness WB and yellowing degree according to K7103
It was evaluated by YI. The heat resistance test was performed using a gear type aging tester, and the color after 5 hours at 130 ° C. was evaluated in the same manner as in the light resistance test. The results are also shown in Tables 1, 2 and 3.

Examples 7-8 and Comparative Examples 7-8 A solution of 100 parts by weight of chloroprene rubber and 100 parts by weight of methyl methacrylate (MMA) in 600 parts by weight of toluene was heated to 80 ° C. while stirring. After that, 0.5 parts by weight of benzoyl peroxide was added to initiate graft polymerization. After reacting for 5 hours, 1 part by weight of hydroquinone was added to stop the polymerization reaction. After making a uniform solution with the composition shown in Table 1 and Table 2, Examples 1 to 6 and Comparative Example 1
The composition was applied on a pure white EVA sponge in the same manner as in Examples 6 to 6, and the light discoloration resistance and heat discoloration resistance were evaluated.

Hunter whiteness WB indicates that the larger the value, the closer to pure white, and the higher the value, the higher the yellowness YI, the stronger the yellow tint. That is, for the purpose of the present invention, it is preferable that WB is large and YI is small. As is clear from the comparison between the examples and comparative examples in Tables 1, 2 and 3, the composition according to the present invention is excellent in both light discoloration resistance and heat discoloration resistance.

Description of Tables 1-3. 1. Description of Rubber Denkachloroprene M-40: manufactured by Denki Kagaku Kogyo Co., Ltd. Denkachloroprene A-90: manufactured by Denki Kagaku Kogyo Co., Ltd. Description of chemicals Benzotriazole (1): Seesorb 720 manufactured by Shiraishi Calcium Co., Ltd. Benzodriazole (2): Same as above Seesorb 703 methylene-bis-t-phenol (1): methylene-bis-t-butylphenol, same as above Seanox 224
M Thio-bis-phenol-Ni salt (1): Same as above Seasorb 612NH hydroxy-benzophenone (1): Same as above Seasorb 101 Thio-bis-hindered phenol (1): Same as above Seanox BCS Hindered phenol (2): Same as above Knox 3
26M 3. Explanation of symbols ◎: White, almost no change ○: White, slightly colored ×: Yellow to brown, clearly discolored ××: Dark brown, extremely discolored

[0024]

As is clear from the examples, according to the present invention, it is possible to provide a chloroprene rubber composition which simultaneously improves light discoloration resistance and heat discoloration resistance. The rubber-based adhesive obtained from the chloroprene rubber composition of the present invention is hardly colored by light or heat as compared with the conventional chloroprene composition, and can be used for transparent, white or colored products, and is very useful.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 11/00 C08L 51/04 C08K 5/13 C08K 5/3475

Claims (2)

(57) [Claims] 1. A chloroprene rubber composition comprising the following (A), (B) and (C) as essential components. (A) Chloroprene rubber (B) Benzotriazole compound represented by the following general formula (I) (C) Methylene-bis- represented by the following general formula (II)
Tertiary butyl phenolic compound (In the formula, R1 and R2 are a hydrogen atom or an alkyl group, and may be the same or different.) (In the formula, R3 and R4 are a hydrogen atom or an alkyl group, which may be the same or different. T-BU is a tertiary butyl group.) 2. The chloroprene rubber composition according to claim 1, wherein the chloroprene rubber (A) is a graft polymer obtained by graft-polymerizing methyl methacrylate onto chloroprene rubber.