Blocked mercaptosilane coupling agent
View Patent ↗The invention relates to a blocked mercaptosilane of general formula I below: (HO) 2 R 1 —Si—Z—S—C(═O)-A in which: R 1 represents a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms; A represents hydrogen or a monovalent hydrocarbon-based group chosen from alkyls, which are linear or branched, cycloalkyls or aryls, having from 1 to 18 carbon atoms; Z represents a divalent bonding group comprising from 1 to 18 carbon atoms.
1. A blocked mercaptosilane of formula 1 below:
(HO) 2 R 1 —Si—Z—S—C( ══ O)-A
wherein:
R 1 represents a monovalent hydrocarbon-based group selected from the group consisting of alkyls, which are linear or branched, having from 1 to 18 carbon atoms, and cycloalkyls and aryls having fewer than 18 carbon atoms;
A represents hydrogen or a monovalent hydrocarbon-based group selected from the group consisting of alkyls, which are linear or branched, having from 1 to 18 carbon atoms, and cycloalkyls and aryls having fewer than 18 carbon atoms;
Z represents a divalent bonding group comprising from 1 to 18 carbon atoms.
2. The blocked mercaptosilane according to claim 1 , wherein Z contains one or more heteroatoms selected from the group consisting of O, S and N.
3. The blocked mercaptosilane according to claim 1 , wherein:
R 1 is selected from the group consisting of methyl, ethyl, n-propyl and isopropyl;
A is selected from the group consisting of alkyls having from 1 to 18 carbon atoms and the phenyl radical;
Z is selected from the group consisting of C 1 -C 18 alkylenes and C 6 -C 12 arylenes.
4. The blocked mercaptosilane according to claim 3 , wherein Z is selected from the group consisting of C 1 -C 10 alkylenes.
5. The blocked mercaptosilane according to claim 4 , wherein Z is selected from the group consisting of C 1 -C 4 alkylenes.
6. The blocked mercaptosilane according to claim 3 , wherein R 1 is methyl.
7. The blocked mercaptosilane according to claim 3 , wherein A is selected from the group consisting of alkyls having from 1 to 7 carbon atoms and the phenyl radical.
8. The blocked mercaptosilane according to claim 3 , wherein R 1 is methyl, Z is a propylene, and A is a heptyl.
9. A process for preparing a blocked mercaptosilane according to claim 1 , comprising:
starting from a blocked mercaptosilane (hereinbelow product B) of formula (B):
(R 2 O) 2 R 1 —Si—Z—S—C( ══ O)-A
wherein:
R 1 , A and Z have the same meaning as in formula (I);
R 2 , which are identical or different, represent a monovalent hydrocarbon-based group selected from the group consisting of alkyls having from 1 to 6 carbon atoms;
hydrolyzing product B in an acid medium to form the targeted blocked mercaptosilane of formula (I).
10. A method of coupling an inorganic filler with a diene elastomer comprising introducing a blocked mercaptosilane according to claim 1 into a mixture comprising inorganic filler and diene elastomer.
11. The method of coupling according to claim 10 , wherein the mixture is in a rubber composition.
12. The process according to claim 9 , wherein R 2 is selected from the group consisting of alkyls having from 1 to 3 carbon atoms.
13. The blocked mercaptosilane according to claim 3 , wherein R 1 is selected from the group consisting of methyl and ethyl.