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Heat-resistant rubber composition

a technology of rubber composition and heat resistance, applied in the field of heat resistance rubber composition, can solve the problems of low modulus, poor resistance to permanent set, and insufficient crosslinking performan

Inactive Publication Date: 2002-01-22
MITSUI CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

A heat-resistant rubber composition of the invention comprises the specific ethylene-.alpha.-olefin-nonconjugated polyene copolymer rubber (A) and the organic peroxide (B). Therefore, the composition has high crosslinking efficiency and a high modulus, and can provide a vulcanized rubber molded product having excellent resistance to environmental deterioration such as thermal aging resistance.The other heat-resistant rubber composition of the invention comprises the specific ethylene-.alpha.-olefin-nonconjugated polyene copolymer rubber (A), the amine type anti-aging agent (C) and / or the hindered phenol type anti-aging agent (E), the sulfur type anti-aging agent (E) and the organic peroxide (B). Therefore, the composition can provide a vulcanized rubber molded product showing not only excellent mechanical and electrical properties but also prominently high thermal aging resistance. These effects can be obtained by the use of a combination of the amine type anti-aging agent (C) and the sulfur type anti-aging agent (E), a combination of the hindered phenol type anti-aging agent (D) and the sulfur type anti-aging agent (E), or a combination of the amine type anti-aging agent (C), the hindered phenol type anti-aging agent (D) and the sulfur type anti-aging agent (E).Among the heat-resistant composition of the invention, a composition comprising ethylene-.alpha.-olefin-nonconjugated polyene copolymer rubber (A) containing a blend of specific amounts of the ethylene-.alpha.-olefin-nonconjugated polyene copolymer rubbers (A1) and (A2) having different intrinsic viscosities (i.e., having different molecular weights) particularly has extremely good fluidity (molding processability) and can provide a vulcanized rubber molded product showing not only excellent mechanical and electrical properties but also prominently high thermal aging resistance.Accordingly, the heat-resistant rubber composition which exerts such effects as mentioned above can be favorably used for automotive parts such as weatherstrip, door glass run channel, window frame, radiator hose, brake parts and wiper blade; industrial rubber parts such as rubber roll, belt, packing and hose; electrical insulating materials such as anode cap and grommet; and building materials such as building gasket.

Problems solved by technology

In these methods, however, the crosslinking is insufficiently performed, resulting in problems of low modulus and poor resistance to permanent set.
However, with respect to the ethylene-.alpha.-olefin-nonconjugated diene copolymer rubber using 1,4-hexadiene, dicyclopentadiene or 5-ethylidene-2-norbornene as the nonconjugated diene, crosslinking is still insufficiently performed, and the thermal aging resistance is low because a large number of double bonds remain after the crosslinking reaction.
In the ethylene-propylene copolymer rubbers prepared utilizing this method, however, there reside problems that the thermal aging resistance of the molded product is lowered and an oil transfer phenomenon (i.e., bleeding) takes place to markedly reduce commercial values.
In the ethylene-propylene copolymer rubbers prepared utilizing this method, however, there generally reside problems of low heat resistance and poor elastomeric properties.
However, this rubber composition does not show such high thermal aging resistance as desired.
The compositions proposed in the publication are improved in the thermal aging resistance, but the level thereof is not satisfactory in the uses for automotive parts and electrical parts, so that the thermal aging resistance should be much more improved.
The rubber composition disclosed in the publications are obviously improved in the thermal aging resistance, but the level thereof is not satisfactory in the uses for automotive parts and electrical parts, so that the thermal aging resistance should be much more improved.
Moreover, these compositions do not show such high fluidity (molding processability) as desired.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

At first, the ingredients shown in Table 1 were kneaded at 140.degree.-150.degree. C. for 5 minutes using a 1.7 liter Banbury mixer to prepare a blend (1).

TABLE 1 Amounts (Parts by Ingredient weight) EPT rubber (A component) *1 100 Zinc white *2 5 Stearic acid *3 1 HAF carbon black *4 50 Softener *5 10 Activator *6 1 Hindered phenol anti-aging agent *7 2 Sulfur anti-aging agent *8 4 *1 Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) having a molar ratio of ethylene to propylene (ethylene / propylene by mol): 68 / 32; an intrinsic viscosity [.eta.], as measured in decalin at 135.degree. C.: 2.2 dl / g; and an iodine value: 3. *2: available from Sakai Chemical Industry Co., Ltd. *3: Tsubaki (Trade Mark) available from NOF Corporation *4: Asahi #70 (Trade Mark) available from Asahi Carbon, Ltd. *5: Diana Process oil PW 380 (Trade Mark) available from Idemitu Kosan, Co., Ltd. *6: Polyethylene glycol, Molecular weight = 4000 *7: Irganox 1010 (Trade Mark), available from Ciba Geigy...

example 2

Example 1 was repeated except that Kayacumyl AD-40 (trade name) available from KAYAKUAKZO Co. was used as the organic peroxide (B).

The results are set forth in Table 3.

example 3

Example 1 was repeated except that the ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (2) described below was used in place of the ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (1) in Example 1.

Ethylene-propylene-5-vinyl-2-norbornene copolymer rubber (2):

Ethylene / propylene (by mol): 68 / 32

Intrinsic viscosity [.eta.] measured in decalin at 135.degree. C.: 2.6 dl / g

Iodide value=3

The results are set forth in Table 3.

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Abstract

A heat-resistant rubber composition of the invention is a vulcanizable composition comprising a specific ethylene-alpha-olefin-nonconjugated polyene copolymer rubber (A) and an organic peroxide (B). This heat-resistant composition has high crosslinking efficiency given by the organic peroxide and high modulus, and can provide a vulcanized rubber molded product of excellent resistance to environmental deterioration such as thermal aging resistance. The other heat-resistant rubber composition of the invention is a vulcanizable composition comprising 100 parts by weight of a specific ethylene-alpha-olefin-nonconjugated polyene copolymer rubber (A) composed of ethylene, an alpha-olefin or 3 to 20 carbon atoms and a nonconjugated polyene which is a vinyl end group-containing norbornene compound, 0.2 to 5 parts by weight of an amine type anti-aging agent (C) and / or a hindered phenol type anti-aging agent (D), 1 to 10 parts by weight of a sulfur type anti-aging agent (E) and an organic peroxide (B). This heat-resistant rubber composition can provide a vulcanized rubber molded product showing not only excellent mechanical properties and electrical properties and but also prominently high thermal aging resistance.

Description

TECHNICAL FIELDThe present invention relates to a heat-resistant rubber composition comprising an ethylene-.alpha.-olefin-nonconjugated polyene copolymer rubber. More particularly, the invention relates to a vulcanizable heat-resistant rubber composition having high crosslinking efficiency given by an organic peroxide and capable of providing a vulcanized rubber molded product showing not only excellent mechanical and electrical properties but also prominently high thermal aging resistance, specifically a vulcanizable heat-resistant rubber composition having extremely good fluidity (molding processability).BACKGROUND ARTCrosslinking of ethylene-.alpha.-olefin copolymer rubbers is carried out using not sulfur, but organic peroxides, because the copolymers have no double bond in their main chains. The rubbers have been used for automotive parts, industrial packing, electrical wires and electrical wire connecting parts, but these parts are desired to be produced at a low cost. For redu...

Claims

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Application Information

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IPC IPC(8): C08L23/00C08L23/08C08K5/00C08K5/14
CPCC08K5/0025C08K5/14C08L23/0815C08L23/16C08L2312/00C08L2666/04
Inventor HAKUTA, TAKASHITOJO, TETSUOKAWASAKI, MASAAKIHOSOYA, MIKIO
Owner MITSUI CHEM INC
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