Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1998-01-20
2000-02-22
Lipman, Bernard
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 74, 525197, 525207, C08G 6348, C08F 830, C08L 800, C08L 3500
Patent
active
060281421
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a crosslinked elastomer with thermoplastic conversion and to a process for its manufacture and to its uses.
For the manufacture of some articles such as insulating and/or leakproofing gaskets and packings and conduits, pipes, tubes or the like for the transfer of fluids like those employed, for example, by the automobile industry (in braking, cooling, power steering or air conditioning circuits, and the like), it is desirable to have available materials which, while exhibiting properties that are similar to those of elastomers and especially an ability to withstand large deformations without breaking and an ability to recover their initial geometry after stresses of the elongation or compression type, even when repeated, as well as a good behaviour towards heat, chemical agents and inclement weather, can be processed by the techniques and the equipment which are employed by the converters of thermoplastic materials, this being chiefly to permit the recycling of these articles as well as that of the waste produced in the course of their manufacture, recycling which the use of elastomers does not permit.
Accordingly, in U.S. Pat. No. 4,130,535 polyolefin-based "thermoplastic elastomers" have been proposed, which exhibit a structure consisting of an uncrosslinked polypropylene matrix and crosslinked nodules of ethylene/propylene/diene (EPDM) terpolymer, so as to exhibit at the temperature of use--which is lower than the melting temperature of polypropylene--a behaviour similar to that of elastomers after vulcanization, while heating them above this melting temperature allows them to be processed like thermoplastics.
Although these materials actually exhibit a certain number of properties which are equivalent to those of elastomers, they nevertheless show a high residual elongation set (higher than 50%) at temperatures above 100.degree. C., and this makes their use not very appropriate to the manufacture of articles intended to be employed in regions where temperatures of more than 100.degree. C. prevail, such as possibly insulating and/or leakproofing gaskets and packings or else conduits, pipes, tubes and the like, intended to ensure the transfer of fluids in the engine compartment of a motor vehicle.
It is consequently an objective of the invention to provide a material which, while being capable of being processed and converted like a thermoplastic, exhibits a mechanical behaviour similar to that of elastomers with, in particular, a low residual deformation by stresses, even when the latter are applied at very high temperatures, as well as good resistance to heat, to inclement weather and to chemical agents, so as to be able advantageously to replace these elastomers, and especially rubber, in the industrial manufactured products in which they are traditionally employed.
It is also an objective of the invention to provide such a material, the manufacture of which is simple and the cost of production of which is economically advantageous.
These objectives are attained according to the present invention by a crosslinked elastomer with thermoplastic conversion, characterized in that it includes at least one elastomer with polymerization using a metallocene catalyst and a grafted polyolefin.
Within the meaning of the present invention an elastomer with polymerization using a metallocene catalyst is intended to mean any elastomer consisting of a homopolymer, a copolymer or a terpolymer, the polymerization of which has been carried out by means of a metallocene catalyst.
According to a preferred embodiment of the invention, the elastomer with polymerization using a metallocene catalyst is chosen from octene/ethylene polymers. These copolymers, which are also called polyoctenes, are available from Du Pont Dow under the trade name Engage and exist in various grades which differ especially in their density, their viscosity and their hardness, and all of which are capable of being employed for the production of an elastomer in accordance with the invention.
According to an advantageo
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Hutchinson
Lipman Bernard
Zalukaeva Tanya
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