Destructured starch derivatives and elastomer compositions containing them
This invention relates to new destructured starch derivatives and elastomer compositions containing them. In particular this invention relates to destructured starch silyl ethers in which at least one oxygen atom of the destructured starch is covalently bonded to at least one silicon atom and/or to at least one compound containing silicon.
1. A composition comprising at least one elastomer and at least one silyl ether of destructurized starch in which at least one oxygen atom of the destructurized starch is covalently linked with at least one silicon atom and/or at least one silicon-containing compound, said silyl ether being obtained by means of a process comprising the steps of:
a. preparing destructurized starch;
b. mixing said destructurized starch with at least one silicon-containing compound at temperatures between 110 and 250° C.;
in which during step a, or after step a and before step b, adding at least one crosslinking agent selected from the group consisting of aldehydes, polyaldehydes and anhydrides;
wherein:
said silicon-containing compound is selected from the group consisting of organosilanes having the general formula selected from:
(RO) 3 SiC n H 2n S m C n Si(OR) 3 tm (I)
(RO) 3 SiC n H 2n X (II)
(RO) 3 SiC n H 2n S m Y (III)
in which
“R” represents an alkyl group having from 1 to 4 carbon atoms, the three R being the same or different;
“n” represents an integer from 1 to 6,
“m” represents an integer from 1 to 6;
“X” represents a mercaptane group, an amine group, a vinyl group, a nitroso group, an imide group, a chlorine atom or an epoxy group;
“Y” represents a cyano group, an N,N-dimethyl thiocarbamoyl group, a mercaptobenzothriazole group, or a methacrylate group; and
said elastomer is selected from natural rubbers and synthetic rubbers, and said synthetic rubbers are selected from the group consisting of dienic homopolymers, block copolymers styrene-butadiene-styrene, random copolymers styrene-isoprene, block copolymers styrene-isoprene-styrene, block copolymers acrylonitrile-butadiene, and random copolymers of vinylarene-conjugated dienes.
2. The composition according to claim 1 , in which said step a. of preparing destructurized starch is performed in the presence of 1-40% by weight, with respect to the weight of starch, of one or more plasticizers selected from the group consisting of water and polyols having from 2 to 22 carbon atoms.
3. A composition according to claim 2 , and further comprising 1-20% by weight of at least one silicon-containing compound not linked to an oxygen atom of starch.
4. The composition according to claim 1 , in which said crosslinking agent is glyoxal.
5. A composition according to claim 4 , and further comprising 1-20% by weight of at least one silicon-containing compound not linked to an oxygen atom of starch.
6. The composition according to claim 5 , in which said step a. of preparing destructurized starch is performed in the presence of 1-40% by weight, with respect to the weight of starch, of one or more plasticizers selected from the group consisting of water and polyols having from 2 to 22 carbon atoms.
7. The composition according to claim 4 , in which said step a. of preparing destructurized starch is performed in the presence of 1-40% by weight, with respect to the weight of starch, of one or more plasticizers selected from the group consisting of water and polyols having from 2 to 22 carbon atoms.
8. The composition according to claim 1 , and further comprising 1-20% by weight of at least one silicon-containing compound not linked to an oxygen atom of starch.
9. The composition according to claim 8 , in which said crosslinking agent is glyoxal.
10. The composition according to claim 1 , comprising from 1 to 70 phr of said silyl ether of destructurized starch.
11. A composition according to claim 10 , and further comprising 1-20% by weight of at least one silicon-containing compound not linked to an oxygen atom of starch.
12. The composition according to claim 11 , in which said crosslinking agent is glyoxal.
13. The composition according to claim 10 , in which said step a. of preparing destructurized starch is performed in the presence of 1-40% by weight, with respect to the weight of starch, of one or more plasticizers selected from the group consisting of water and polyols having from 2 to 22 carbon atoms.
14. The composition according to claim 10 , in which said crosslinking agent is glyoxal.