JPS6023433A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber composition for vulcanization with sulfur, having excellent heat resistance, and suitable as industrial goods, packing, hose, etc., by adding a specific antioxidant to a specific ethylene-alpha-olefin-diene copolymer (EPDM). CONSTITUTION:The objective rubber composition is produced by mixing (A) 100pts.wt. of EPDM (preferably an EPDM rubber having an iodine value of 6- 10 and composed of propylene as alpha-olefin and ethylidene-norbornene as diene) with (B) an antioxidant consisting of (i) preferably 1-6pts.wt. of a phenolic compound of formula [R1 and R2 are 1-9C hydrocarbon group; R3 is -(CH2)n-; n is 1-5) and (ii) preferably 1-3pts.wt. of an imidazole compound (e.g. 2-mercaptoimidazoline).

Description

[Detailed Description of the Invention] The present invention relates to an ethylene-α-olefin-diene copolymer (hereinafter E]) (sometimes abbreviated as DM) having excellent heat resistance.
Regarding the composition.

Generally ethylene-propylene copolymer Komuya EI'DM
Has heat resistance, weather resistance, strong ozone resistance, and low temperature properties.

It is a polymer with excellent chemical resistance to polar solvents,
It is used in many fields such as automobile parts, building material parts, electrical parts, hoses, and industrial supplies.

However, recently there has been a trend to use rubber parts in high-temperature parts such as around automobile engines and electrical parts.

In this case, even higher heat resistance is required.

This requirement has been met by peroxide vulcanization of EPDM. However, in this case, there are problems such as limited usage and generation of odor. For this reason, EP
Currently, expensive special rubbers other than DM have no choice but to be used.

The present inventors conducted nine various studies with the aim of overcoming these drawbacks and obtaining a rubber composition with excellent heat resistance by sulfur vulcanization. It was discovered that a composition having excellent heat resistance that could not be predicted based on the knowledge of conventional sulfur vulcanization could be obtained by blending the above together, leading to the present invention.

The present invention provides ethylene-α of iodine f111i 5-12
100 parts by weight of olefin-diene copolymer.

(In the formula, R, and R2 are hydrocarbon groups having 1 to 9 carbon atoms.

■(13 represents n-1 to 5 with (CH,,).)1
] 1 to 10 phenolic compounds having the structure shown in
A rubber composition for sulfur vulcanization is provided, characterized in that it contains 1 to 4 parts by weight of an imidazole compound.

E used in the present invention I) I) M is ethylene, α
- It is a multi-component copolymer obtained by copolymerizing olefin and diene. - Generally commercially available products can be used. α
-Propylene and 1-butene are used as the olefin, with propylene being preferred.

As the diene, ethylidene, norbornene, dicyclopentadiene, 1,4-hexadiene, methylnorbornene, 4,7,8.9-tetrahydroindene, 1,7 octadiene, etc. are used, and ethylidene norbornene is preferred.

The EPDM of the present invention has an iodine value of 5 to 12. Preferably 6~
It is 10. If it is less than 5, the vulcanization rate will be low, the vulcanization will be insufficient, and the vulcanization physical properties will be poor, so it cannot be put to practical use. Moreover, if it exceeds 12, the effect of the present invention cannot be changed.

In addition, the iodine value of Ell)M was calculated by the following formula.

× (Diene component weight percent) The phenolic compound (I), which is a component of the antiaging agent used in the present invention, has the general formula of a hydrocarbon group having 1 to 9 carbon atoms, R3 is (CH2), and n=
Represents 1 to 5. ) is a phenolic compound containing 1 to 4 structures represented by the formula, specifically octadecyl 3-(3゜5-ditertiarybutyl-4-hydroxyphenyl)-propionate (CI-13) 3C゛erythrityl- Tetrakis[3-(3,5-diter-7yabutyl-4-hydroxyphenyl)propionate] 2.2'-thiodiethylbis-C3-(3,5-diter-7yabutyl-4-hydroxyphenyl)-propionate] / (CH3) Examples include 3C.

Specific examples of imidazole compounds (manufactured by Co., Ltd.) which are other components of the anti-aging agent used in the present invention include 2-mercaptobenzimidazole, 2-mercaptoimidacillin and the like.

The blending amount of the compounds (I) and (rJ) above is El) DM1
(I) is 1 to 10, preferably 1 to 10, per 00 parts by weight.
6 parts by weight, (1 to 4 parts by weight, preferably 1 to 3 parts by weight. If the amount is too low outside this range, a sufficient effect on heat resistance cannot be obtained. Also, if the amount is outside this range, There is a risk that physical properties such as a decrease in mechanical strength may be impaired.

EPDM used in the present invention may include carbon black, white filler, softener, zinc white stearic acid,
Commonly used rubber compounding chemicals such as vulcanizing agents and vulcanization accelerators can be blended.

In producing the rubber composition of the present invention, the blending ratio, blending method, and blending order of the above-mentioned compounded chemicals are not particularly limited, and they can be mixed using a conventional method such as a Banbury mixer, a roll mill, or the like. This mixture can be molded into any desired shape using conventional methods such as an extruder or a calendar roll. Furthermore, a method of vulcanization molding using a press vulcanizer, a hot air vulcanizer, a steam vulcanizer, or the like is usually employed.

By taking advantage of its properties, the rubber composition of the present invention can be suitably used in applications that are used in high-temperature atmospheres, such as industrial products, oak leaves, hoses, and the like.

The invention is further illustrated by the following non-limiting examples.

[Description of materials used in examples]

EPDM-1; ethylene-propylene-nonconjugated diene
Co-1 [Combined (Product name: JSREP93. Manufactured by Japan Synthetic Rubber) ML,..., 4 (if) OoC) 50 Non-conjugated diene Ethylidene norbornene Content (iodine value; l2No) 5 Propylene content (weight ratio) 43 EPDM -2; ethylene-propylene-nonconjugated diene
Copolymer (prototype) ML++s (120'C) 55 Non-conjugated diene Ethylidene norbornene content (1,...
NO) 6.0 Propylene content (weight ratio) 32 Oil extension amount (PI-IR) 50 EPDM-3; ethylene-propylene-nonconjugated diene
Copolymer (trade name JSR, BP96. manufactured by Japan Synthetic Rubber) MLl+8 (120°C) 53 Non-conjugated diene Ethylidenenorbornene content (12No.
) 1.9 Propylene content (wt%) ' 27 Oil extension amount (PI-IR) 50 BPDM-4; ethylene-propylene-nonconjugated diene
Copolymer (product name JSREP33. Manufactured by Japan Synthetic Rubber) ML++4 (1,OO'C) 45 Non-conjugated zoene ethylidene norbornene... Total (1
2No') 26 Propylene content (wt%) 43 Accelerator M B T ; Mercaptobenzothiazole accelerator CJ3 S ; N-cyclohexyl-2-benzothiazyl-sulfenamide accelerator 'J' M T]) ; Tetramethylthiuram disulfide Accelerator]) P T'r; dipentamethylene thiuram tetrasulfide accelerator TcE, 1-'C; chirulum ethyl dithiocarbamate AO-]; bentaexrichyl-tetrakis [3-(3
,5-di-tert-butyl-4-hydroxyphenyl)propionate] AO-2; 2-mercaptobenzimidazole A, 0-
3; Octadecyl 3-(3,5-ditertiaryifthyl-4-hydroxyphenyl)-propionate AO-4; 2,2'-thiodiethylbis-[3-(3,
5-di-tert-butyl-4-hydroxyphenyl)-propionate] AO-5; 2,6-di-tert-butyl-P-cresol AO-6; 2,2'-methylenebis(4-methyl- rotorjarifthylphenol) AO-7; styrenated phenol AO-4; di-shiuryl-thiopropionate AO-9
; N-phenyl-N'-ingrovir ~ P-phenylenediamine AO-1o; N, N'-di-β-naphthyl-P-
Phenylenediamine AO-11; Tov-(/nylated phenyl)bosphite Examples 1-5. Comparative Examples 1 to 3 The series of compositions shown in Table 1, excluding the vulcanization system, were mixed in a Banbury mixer. A vulcanization system is mixed into the mixture using a roll mill to obtain the desired rubber composition. This composition is press-vulcanized at 160° C. for 15 minutes to obtain a vulcanized sheet, which is used for testing.

The test was conducted using JIS J (, G 30 ], (],) tensile test (3) hardness test (1) aging test. However, the aging test conditions were 6 at 160 ± 1°C.
00 hours.

This was used as the evaluation standard for heat resistance. The results are shown in Table-2.

60 at 160±1°C as shown in Examples 1-5.
Even after 0 hours elapsed, the elongation remained at 100% or more, and the rubber-like properties remained. On the other hand, in Comparative Examples 1 to 4, the anti-aging agent was not used, when it was used alone, and even if it was used in combination, the amount was small, and Comparative Examples 5 and 6 were E l) D M When the iodine value exceeds 12, Comparative Examples 7 to 13 are cases where other anti-aging agents were used. The increase in hardness with no elongation is also remarkable. As described above, the present invention was able to be achieved using a very limited combination of polymer and anti-aging agent system.

Claims (1)

[Claims] (1) 3 to 100 parts by weight of 5 to 12 ethylene-α-olefin-diene copolymers. (In the formula, 1%, R2 is a hydrocarbon group tR having 1 to 9 carbon atoms.
3 represents +CH2) and n=1 to 5. ) 1 to 10 phenolic compounds having the structure shown in
A rubber composition for sulfur vulcanization, characterized in that it contains 1 to 4 parts by weight of an imidazole compound.