Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1991-06-04
1993-09-07
Seccuro, Jr., Carman J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
525193, 525194, 525211, 525237, 525240, 525315, 524482, 524491, C08L 2316, C08L 700, C08L 900, C08L 2326
Patent
active
052429717
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to ethylene-propylene-diene rubbers, elastomer compositions and vulcanized rubbers thereof. More particularly, it relates to ethylene-propylene-diene rubbers which are excellent in co-vulcanizability with conjugated diene rubbers and are capable of imparting excellent weather resistance, ozone resistance and thermal aging resistance without deterioating the excellent mechanical characteristics, wear resistance and dynamic fatigue resistance which conjugated diene rubbers such as natural rubber (NR), styrene-butadiene rubber (SRR), isoprene rubber (IR) and butadiene rubber (BR) possess, elastomer compositions containing such ethylene-propylene-diene rubber as mentioned above and vulcanized rubbers composed of the elastomer compositions.
TECHNICAL BACKGROUND
Ethylene-propylene-diene rubbers (EPDM) are rubbers excellent in weather resistance, ozone resistance and thermal aging resistance and widely used for the static sections of automobile parts, such as weather stripping, door glass run channel, radiator hose, etc.
On the other hand, most of parts such as tires, rubber vibration insulators, etc. which require mechanical strength against dynamic fatigue are prepared by using conjugated diene rubbers such as NR, SBR and BR or blends thereof.
It is necessary to improve the thermal aging resistance and weather resistance of automobile parts to cope with the improved performance of automobiles in recent years.
However, though EPDM is excellent in weather resistance, ozone resistance and thermal aging resistance, dynamic fatigue resistance thereof is so poor that EPDM alone cannot be used for the preparation of tires and rubber vibration insulators.
Accordingly, there have been made many studies on the blends of EPDM and the conjugated diene rubber to utilize the advantageous characteristics of each of EPDM and conjugated diene rubber. However, EPDM-conjugated diene rubber blends excellent in co-vulcanizability could not be obtained and hence they could not be put to practical use.
Conventional techniques related to the blends of EPDM and conjugated diene rubber in the above studies are described in Journal of the Society of Rubber industry, Japan, 51,685 (1978) written by Yasuhiro Oda and Masashi Aoshima. As the blending techniques, there are disclosed (1) vulcanization with polysulfides, (2) vulcanization with peroxides, (3) application of prevulcanized EPDM, (4) application of prevulcanized EPDM having a high iodine value, (5) application of halogenated EPDM, (6) utilization of accelerators having a long-chain alkyl group, etc.
According to the disclosures of the aforesaid literature, EPDM having an intrinsic viscosity of at least 3.0 dl/g as measured in xylene at 70.degree. C., a propylene content of not higher than 35% and a high iodine value is found to be good.
Though these descriptions are directed to improve the co-vulcanizability of EPDM with conjugated diene rubber, however, there is described nothing about the items of quality practically required for the quality of goods, particularly about dynamic strength. EPDM-conjugated diene rubber having excellent dynamic fatigue resistance could not be obtained by the above-described techniques.
The purpose of blending EPDM with conjugated diene rubber is to impart excellent thermal aging resistance and weather resistance to the resulting blends without reducing practically excellent crack growth resistance, dynamic fatigue resistance and wear resistance which conjugated diene rubbers possess. Accordingly, it is necessary that dynamic fatigue resistance is imparted to EPDM to be blended with conjugated diene rubbers.
As an example of requiring dynamic fatigue resistance most, there is described in Rubber Chemistry Technology, Vol. 44, page 1043 (October 1971) that the desired characteristics can be obtained by using EPDM having a high Mooney viscosity for All-EPDM as a rubber vibration insulator.
However, the use of high-molecular-weight EPDM is considered to be a matter which is easily conceived by those skilled in t
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patent: 3884993 (1975-05-01), Gros
patent: 4843128 (1989-06-01), Ceasare
patent: 4882387 (1989-11-01), Tobing
patent: 4960829 (1990-10-01), Allen et al.
Mishima Takashi
Nakahama Hidenari
Mitsui Petrochemical Industries Ltd.
Seccuro, Jr. Carman J.
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