JP3265634B2 - High strength, high specific gravity 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 rubber composition having a high strength and a high specific gravity. More specifically, the present invention relates to an ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-non-conjugated diene copolymer rubber having both high strength and high specific gravity characteristics.

[0002]

2. Description of the Related Art Conventionally, ethylene-propylene rubber (EP)
M) or ethylene-propylene-non-conjugated diene rubber (E
It is known that an ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-non-conjugated diene copolymer rubber represented by PDM) is excellent in heat aging resistance, ozone resistance, polar solvent resistance and the like. . By the way, it is known that the specific gravity of rubber is related to the vibration damping characteristics and the X-ray shielding characteristics, and the higher the specific gravity is, the more excellent the characteristics are. Also, from a practical viewpoint, one of the indispensable requirements for rubber is to have a sufficiently high strength. Under such circumstances, there is no known technique for simultaneously imparting high specific gravity and high strength to ethylene-α-olefin copolymer rubber or ethylene-α-olefin-non-conjugated diene copolymer rubber.

[0003]

In view of this situation, an object of the present invention is to provide an ethylene-α-olefin copolymer rubber or ethylene-α-olefin-non-polymer having both high strength and high specific gravity characteristics. It is to provide a conjugated diene copolymer rubber.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention relates to an ethylene-α-olefin copolymer rubber and / or an ethylene-α-olefin-non-conjugated diene copolymer rubber, lead oxide and at least one zinc acrylate compound represented by the following chemical formula (1). The present invention relates to a high-strength, high-specific-gravity rubber composition to be contained.

[0005] (In the formula, R represents a hydrogen atom or an alkyl having 1 to 8 carbon atoms, m represents an integer of 1 to 2, and k represents an integer of 0 to 1.)

The details will be described below. Examples of the α-olefin in the ethylene-α-olefin copolymer rubber and the ethylene-α-olefin-non-conjugated diene copolymer rubber of the present invention include propylene, 1-butene, 1-pentene, 1-hexene and 4-methyl-1 -Pentene, 1-octene, 1-decene, etc., among which propylene is preferred. Examples of the non-conjugated diene include 1,4-hexadiene, 1.6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene. Chain non-conjugated dienes such as: cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5
Cyclic non-conjugated dienes such as methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropylenyl-2-norbornene;
2,3-diisopropylidene-5-norbornene, 2-
Ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, 1.
Trienes such as 3,7-octatriene and 1,4,9-decatriene are mentioned, among which 1,4-hexadiene, dicyclopentadiene and 5-ethylidene-2-
Norbornene is preferred.

[0007] As the lead oxide used in the present invention, lead oxide such as lead monoxide usually called litharge and trilead tetroxide called lead tan is used. The amount of the lead oxide to be used may be an ethylene-α-olefin copolymer rubber and / or an ethylene-α-olefin-non-conjugated diene copolymer rubber (hereinafter, referred to as “ethylene-α-olefin copolymer rubber”).
Sometimes referred to as "rubber component". ) Usually, 5 to 3000 parts by weight, preferably 100 to 1500 parts per 100 parts by weight.
Parts by weight. When the amount of lead oxide is too small, the specific gravity is inferior. On the other hand, when the amount of lead oxide is too large, the rubber properties as an elastomer and the mechanical properties may be reduced.

The zinc acrylate compound of the present invention is a compound represented by the above formula (1), and specific examples include zinc acrylate, zinc hydroxide acrylate, zinc methacrylate and the like. In addition, as the zinc acrylate-based compound, one kind thereof may be used alone, or two or more kinds thereof may be used in combination. The amount of the zinc acrylate compound used is usually 0.1 parts by weight per 100 parts by weight of the rubber component.
-100 parts by weight, preferably 1-30 parts by weight. When the amount of the zinc acrylate-based compound is too small, the strength is inferior. On the other hand, when the amount of the zinc acrylate-based compound is too large, the effect of increasing the strength obtained by increasing the use amount is saturated, and Economy and high specific gravity may decrease.

In order to obtain a rubber product using the rubber composition of the present invention, for example, in addition to a rubber component, lead oxide and a zinc acrylate compound, if necessary, carbon black, an organic peroxide, an oxidized Vulcanizable by mixing inhibitor, vulcanization accelerator, processing aid, stearic acid, reinforcing agent, filler, plasticizer, softener, etc. using a usual kneading machine such as roll, Banbury etc. By vulcanizing the rubber composition at a temperature of usually 120 ° C. or higher, preferably 150 to 220 ° C. for about 1 to 30 minutes, a rubber product as a vulcanized rubber composition can be obtained. The vulcanization can be applied to any of press vulcanization, steam vulcanization, hot air vulcanization and the like.

[0010] The rubber composition of the present invention includes a ferrite for imparting magnetism; aluminum hydroxide or magnesium hydroxide for imparting flame retardancy; and a conductive metal (for imparting electromagnetic wave shielding properties). Powders or fibers of stainless steel, copper, silver, etc.) alone or in combination of two or more.

The vulcanized rubber composition obtained from the rubber composition of the present invention maintains the excellent properties of the ethylene-α-olefin copolymer rubber or the ethylene-α-olefin-non-conjugated diene copolymer rubber, and It has high specific gravity and high strength at the same time, and uses its excellent features in a wide range of fields, for example, rubber damping parts for automobiles, rubber damping parts for electric products, X-ray shielding gloves, X-ray shielding Applicable to apron, sound insulation material, etc.

[0012]

Next, the present invention will be described with reference to Examples and Comparative Examples. Examples 1 to 4 and Comparative Example 1 Formulations shown in Table 1 (excluding peroxides)
Was kneaded for 5 minutes at a rotor rotation speed of 60 rpm using a 1500 ml Banbury mixer adjusted to 90 ° C. Thereafter, peroxide was added and kneaded using an 8-inch open roll to obtain a rubber composition. next,
The rubber composition was press-vulcanized at 170 ° C. for 15 minutes to obtain a vulcanized rubber composition. Evaluation of vulcanized rubber composition is based on JIS
Performed according to K6301. The results are shown in Table 1.

The following can be understood from the results. Compared to Comparative Example 1 in which the zinc acrylate compound of the present invention was not used,
In all the examples using the zinc acrylate compound, the tensile strength was remarkably improved while maintaining the specific gravity at a satisfactory height.

[0014]

[Table 1] ------------------------ Rubber component: 2 100 100 100 100 100 Lead oxide * 3 500 500 500 500 500 Zinc acrylate compound * 4 0 5 10 30 50 Evaluation Vulcanizate properties * 5 Tensile strength Kgf / cm ² 32 65 80 116 122 Elongation% 160 110 80 60 50 Hardness JIS-A 74 78 82 91 95 Specific gravity 3.47 3.44 3.41 3.30 3.20 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

* 1 Formulation: In addition to those shown in Table 1, as common formulas, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, antioxidant MB (antioxidant manufactured by Sumitomo Chemical Co., Ltd.)
One part by weight, 7 parts by weight of DCP (40% dicumyl peroxide, manufactured by NOF Corporation) and 2 parts by weight of TAYK were used.

* 2 Rubber component: ethylene-propylene-
Ethylidene norbornene copolymer rubber (E501A manufactured by Sumitomo Chemical Co., Ltd., Mooney viscosity ML _{1 + 4} 100 ° C 43,
Ethylene content 50% by weight, iodine value 11) * 3 Lead oxide: lead monoxide (Shinagawa Kako, specific gravity 9.2 to 2.0)
9.5) * 4 Zinc acrylate compound: A compound (zinc acrylate) in chemical formula (1) where R = hydrogen atom, m = 2, and k = 0 was used. * 5 Vulcanized physical properties: physical properties of vulcanized product at 170 ° C for 15 minutes

[0017]

As described above, the present invention provides an ethylene-α-olefin copolymer rubber or an ethylene-α-olefin-non-conjugated diene copolymer rubber having both high strength and high specific gravity. Was completed.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-158258 (JP, A) JP-A-52-103451 (JP, A) JP-A-60-92237 (JP, A) JP-A-4- 246448 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08

Claims (1)

(57) [Claims] An ethylene-α-olefin copolymer rubber and / or an ethylene-α-olefin-non-conjugated diene copolymer rubber, lead oxide and at least one zinc acrylate compound represented by the following chemical formula (1): High strength and high specific gravity rubber composition. (In the formula, R represents a hydrogen atom or an alkyl having 1 to 8 carbon atoms, m represents an integer of 1 to 2, and k represents an integer of 0 to 1.)