JP3167829B2 - Prevention of early vulcanization of rubber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for suppressing early vulcanization in crosslinking organic rubber with an organic peroxide. The method of crosslinking rubber with an organic peroxide has long been adopted since a vulcanized rubber having heat resistance and low compression set can be obtained.
Since the crosslinked structure of the organic peroxide is a carbon-carbon crosslinked, it is said that the tensile strength and the tear strength are low and the dynamic characteristics are inferior to those of the sulfur crosslinked which is a general vulcanization method of rubber. ing. Therefore, in practice, a co-crosslinking agent is often used in combination for the purpose of improving the physical properties of the crosslinked product of the organic peroxide.

[0002] Co-crosslinking agents include sulfur, polyfunctional monomers, metal salts of methacrylic acid or acrylic acid, and dioximes. When other co-crosslinking agents except sulfur are used in combination, vulcanization starts. Faster, premature vulcanization of rubber is often a problem. Even in the absence of a co-crosslinking agent, early vulcanization is still a problem. Preventing premature vulcanization of rubber is an important issue from the viewpoint of preventing material loss due to burning (scorch) in the processing step and reducing product defects.

[0003]

2. Description of the Related Art As a method for suppressing premature vulcanization in organic peroxide crosslinking of rubber, 2,2'-methylenebis (4
It is generally known to add a small amount of an antioxidant such as -methyl-6-tert-butylphenol). However, although this method has the effect of suppressing early vulcanization,
Undesirable and useful scorch inhibitors have not yet been developed because they significantly reduce the degree of crosslinking and adversely affect the compression set.

[0004]

An object of the present invention is to provide a method for suppressing premature vulcanization without impairing the physical properties of the vulcanized rubber when the rubber is crosslinked with an organic peroxide. Aim.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for suppressing the early vulcanization of rubber, in which a sulfurized phenol resin and / or an alkyl sulfide resin coexist when the rubber is crosslinked with an organic peroxide. By adding this resin, early vulcanization can be prevented without impairing the physical properties of the vulcanized rubber.

[0006] Sulfurized phenolic resins and sulfurized alkylphenol resins are synthesized by the reaction of phenol or alkylphenol with sulfur. Examples of the sulfurized alkylphenol resin include a sulfurized-p-tert-butylphenol resin. The addition amount of the sulfurized phenolic resin and / or the sulfurized alkylphenolic resin according to the present invention is 0.1 to 5.0 parts by weight, preferably 0.5 to 2.0 parts by weight, based on 100 parts by weight of rubber. It is.

[0007] The sulfurized phenolic resin according to the present invention and / or
Alternatively, as a crosslinking agent for an organic peroxide which can be used when a sulfurized alkylphenol resin is used, for example, dicumyl peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, di- ( tert
-Butylperoxyisopropyl) benzene, 2,5-
Dimethyl-2,5-di (tert-butylperoxy) hexane, benzoyl peroxide and the like.

In this compounding system, as a co-crosslinking agent, for example, polyfunctional monomers such as trimethylolpropane trimethacrylate and ethylene dimethacrylate, metal salts of methacrylic acid or acrylic acid, and functional groups of 1,2-polybutadiene And a polyfunctional polymer or a sulfur-containing compound.

Further, in this compounding system, compounding agents known in the ordinary rubber industry, for example, metal oxides such as zinc oxide and magnesium oxide, fillers such as calcium carbonate, silica and carbon black, and the like. Softeners such as reinforcing agents, paraffinic, naphthenic or aromatic processing oils,
Various blending agents such as stearic acid and other higher fatty acids, coloring agents and pigments, antioxidants, ultraviolet absorbers and the like can be blended as required.

The compounding of various compounding agents according to the present invention into rubber is prepared by mixing with a conventional mixer such as an open roll for rubber kneading, a Banbury mixer, or a pressure kneader.

[0011]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 According to the formulation shown in Table 1, mixed by a conventional method,
A rubber composition was obtained. The compounded rubber was subjected to a Mooney scorch test in accordance with JIS K6300, and the vulcanization behavior was measured using a rheometer. The vulcanized sample of the compounded rubber composition was subjected to a tensile test, a heat aging test, a compression set test, and a tear test in accordance with JIS K6301. Of the results, Examples are shown in Table 3 and Comparative Examples are shown in Table 2.

In Table 1, Mitsui EPT3045 is a trade name of EPDM manufactured by Mitsui Petrochemical Co., Ltd.
-40 is a trade name of dicumyl peroxide manufactured by NOF Corporation, Sunester TMP is a tradename of trimethylolpropane trimethacrylate manufactured by Sanshin Chemical Industry Co., Ltd., and Sunester SK-30 is a methacryl manufactured by Sanshin Chemical Industry Co., Ltd. A trade name of zinc acid, Sandant 2246 is 2,2'-methylenebis (4-methyl-6) manufactured by Sanshin Chemical Industry Co., Ltd.
-Tert-butylphenol).

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

Example 2 According to the compounding formulations shown in Tables 4 and 5, mixing was carried out by a conventional method to obtain a rubber composition. The vulcanization behavior of the compounded rubber was measured using a rheometer, and the results are shown in Tables 4 and 5. In Table 4, Zetpol 2020 is a trade name of H-NBR manufactured by Zeon Corporation and in Table 5, Skyprene B-
30 is a trade name of non-sulfur-modified chloroprene rubber manufactured by Tosoh Corporation.

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

According to the method of the present invention, when the rubber is crosslinked with an organic peroxide, the early vulcanization can be suppressed without lowering the physical properties of the vulcanized rubber.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-271478 (JP, A) JP-A-47-3135 (JP, A) JP-A-4-318043 (JP, A) JP-A 57- 151632 (JP, A) JP-A-56-43338 (JP, A) JP-A-59-18729 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 21/00 C08J 3 / 24 C08K 5/36

Claims (1)

(57) [Claims] 1. A method for suppressing the early vulcanization of rubber, wherein a sulfurized phenol resin and / or a sulfurized alkylphenol resin coexist when crosslinking the rubber with an organic peroxide.