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
1995-01-09
1998-03-17
Jagannathan, Vasu
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...
4234491, 423445R, 525236, 525237, 525240, 525242, 523215, 523468, C08L 2316, C08K 304
Patent
active
057287660
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to vulcanizable olefinic elastomers and to specific applications of compositions comprising them. In particular the invention relates to elastomeric compositions having improved properties of processability, compound strength and elasticity before and after vulcanization, and long-term heat resistance of the vulcanized compounds.
BACKGROUND ART
The use of vulcanized rubber in many applications is well documented in public literature. Due to the inherent properties of the essentially elastic olefinic polymers many enduse applications require the use of modifying and reinforcing materials to bring out desired properties. Thus a rubber compounder will strive to arrive at a formulation that will give the best balance of processing behaviour, vulcanization (cure) rate, vulcanizate physical properties and cost. The olefin-based elastomers of this invention are well-known to be some of the cheapest polymers currently available and yet still capable of achieving excellent properties in many of the otherwise most adverse applications.
Olefinic rubbers find many uses in the automotive industry because of their relatively low cost and as well because of their properties with respect to moldability and extrudability, or ability to be readily shaped as desired, and their ability to withstand oxidative attack. In particular the rubber compounds based upon ethylene-propylene monomer ("EPM") and ethylene-propylene-diene monomer ("EPDM") elastomeric polymers are playing an ever-expanding role both for underhood and body sealing parts. In particular it is known that certain EPDM grades have shown excellent promise as automotive coolant hose polymers and as seals and gaskets for both the automotive and building industries where large temperature extremes test the ability to maintain an elastic seal.
In these applications it is known that the preferred compounds can typically have 120-170 parts per hundred parts rubber ("phr") of industry-used carbon blacks as reinforcing fillers that serve to both strengthen and further reduce the overall cost of the compounds. The typically used and recommended carbon blacks are those furnace blacks meeting ASTM designations (ASTM D 1765-1979) and falling into the following classes: N550 FEF, N650 GPF, N762 SRF and N683 APF. Among these, N650/683 and N762 are closely defined as standard blacks in ISO/DIN 6809.
The usefulness of EPDM polymers in these compounds depends on the cure rate and cure state as well as the ease of fabrication. Thus it is known that improved properties of faster cure and better processing properties can be achieved where the polymers have selected molecular weight distribution ("MWD") and intermolecular compositional distribution. Means of preparing the preferred broad MWD polymers meeting these criteria are disclosed in the patent literature. Representative recent patents addressing the preparation of such polymers are U.S. Pat. Nos. 4,722,971, 4,789,714, 4,792,595, 4,874,820, and 5,013,801. Earlier patents that similarly address the preparation of specially tailored grades of EPM and EPDM polymers include GB 1 339 061, U.S. Pat. No. 3,468,979, U.S. Pat. No. 3,884,993, GB 1 543 821, and GB 2 023 443.
Several of the documents above disclose the use of specific carbon black fillers. In U.S. Pat. No. 4,722,971 carbon black N650 is used in an amount of 140 phr. In U.S. Pat. No. 4,792,595 the use of 80 phr of "high abrasion furnace black" is disclosed. U.S. Pat. No. 3,884,993 teaches that 10-200 phr of carbon black, as a conventional filler, can be used with improved processability rubber. GB 1 543 821 exemplifies the use of 70 parts "FEF black". GB 2 032 443 teaches that up to 300% by weight of fillers, including carbon black, can be used in improved processability rubbery copolymers and exemplifies the use of a carbon black SEAST H.RTM. (TOKAI Carbon Co., Japan) in the amount of 67 parts by weight.
Additionally, automotive hose compounds utilizing carbon blacks a) N650 GPF-HS (115 parts) with N762 SRF-LM (115 parts) with 137.5
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Mills Timothy Arthur
Schauder Jean-Roch Hector
Asinovsky Olga
Exxon Chemical Co.
Jagannathan Vasu
Miller Douglas W.
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