Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-06-03
2000-10-17
Hampton-Hightower, P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525179, 525184, 525408, 524600, 524606, C08L 7700, C08L 1900, C08L 902, C08L 7103
Patent
active
061333751
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to vulcanized rubbers modified by thermoplastics and more particularly to vulcanized mixtures (i) of functionalized rubbers and (ii) of thermoplastics. They can be prepared by incorporation of the thermoplastic in the molten state in the rubber and then vulcanization is carried out.
In the field of rubbers, it can be advantageous in certain applications (tires, conveyor belts, and the like) to be able to increase the stress at small elongations without encountering problems of heating the vulcanized components on use and on placing under dynamic loading or of aging which are generated by conventional solutions, such as reinforcement by carbon black or by a significant degree of crosslinking.
U.S. Pat. No. 5,239,004 explains that natural, SBR (styrene-butadiene), X-NBR (carboxylated nitrile-butadiene) or EPDM (ethylene-propylene-diene) rubbers can be modified by dithiodiacids and copolymers containing polyether blocks and polyamide blocks. This modification is an increase in the modulus at 50, 100 and 300% elongation. The examples only relate to natural rubber, which was mixed with 1% by weight of dithiodipropionic acid. 4% by weight, either of various copolymers containing polyether blocks and polyamide blocks or of polyamide-12, are then added to this rubber and vulcanization is then carried out.
An increase in the moduli at 50, 100 and 300% elongation is observed; in contrast, a fall of 20 to 35% in the breaking stress is recorded.
The compositions of the present invention also have markedly increased moduli at 50, 100 and 300% but they exhibit a better breaking stress.
The present invention describes the improvement in certain properties of the rubber (reinforcement, tear strength, and the like) without using dithiodiacid, while having a very fine and homogeneous dispersion of the thermoplastic in the rubber network.
EP 40060 describes thermoplastic mixtures of polyamide-6 and polyamide-66 or polyamide-6, polyamide-66 and polyamide-610 with epichlorohydrin rubbers. These are polyamide matrices containing epichlorohydrin rubber nodules. The examples compare the mixtures with vulcanized nodules and the mixtures with non-vulcanized nodules.
The products of the invention are not thermoplastic.
The present invention relates to the modification of rubbers by one or a number of thermoplastics. The thermoplastics are chosen so that they are compatible with the rubbers. This modification makes it possible to improve certain properties of the rubber while maintaining its elastomeric properties (Compression set, Elongation at break) and its resistance to oils: green rubber, that is to say before vulcanization. reinforcing effect.
Moreover, in certain cases, in particular in that of XNBR, the incorporation of thermoplastic of the copolymer containing polyamide blocks and polyether blocks type, in addition to all the improvements mentioned above, contributes to a marked improvement in the behaviour at low temperature, such as the elongation.
The present invention is thus a vulcanized mixture: increase the modulus at small elongations but such that the breaking stress is not reduced by more than 10%.
The functionalized rubber and the thermoplastic are mixed before vulcanization. The vulcanization agent and the possible catalysts are then introduced and then vulcanization is carried out. The agents and the catalysts can be introduced even during the mixing with the thermoplastic, provided that they are not active at the temperatures reached during mixing.
Mention may be made, as examples of functionalized rubbers, of acrylic rubbers, epichlorohydrin rubbers, rubbers on which reactive groups have been grafted, such as carboxylic acid, amine or epoxy functional groups, or chlorinated rubbers or rubbers which have been chlorinated.
Use may also be made of a mixture of one of the above rubbers with a non-functionalized rubber, such as styrene-butadiene (SBR), natural rubber or ethylene-propylene-diene (EPDM).
Mention may be made, among acrylic rubbers, of nitrile-butadiene (NBR)
REFERENCES:
patent: 4297453 (1981-10-01), Coran et al.
patent: 4661563 (1987-04-01), Sasaki et al.
patent: 4866127 (1989-09-01), Jacquemin et al.
patent: 5239004 (1993-08-01), Pyke et al.
patent: 5330837 (1994-07-01), Sullivan
patent: 5556919 (1996-09-01), Oyama et al.
patent: 5683819 (1997-11-01), Mori et al.
Alex Patrick
Betremieux Isabelle
Dousson Christian
Marcq Philippe
Elf Atochem S.A.
Hampton-Hightower P.
LandOfFree
Vulcanized rubbers modified by thermoplastics does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vulcanized rubbers modified by thermoplastics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vulcanized rubbers modified by thermoplastics will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-469978