Modified diene based polymer
View Patent ↗Provided is a modified diene based polymer in which a diene based polymer is graft modified with a polyether having a mercapto group attached via diurethane bonding. Formation of diurethane bonding is performed by allowing sequential reactions of two species of hydroxyl group-containing compounds with an diisocyanate compound. By adding the modified diene based polymer to a silica-containing rubber composition for automobile pneumatic tires, the dispersibility of silica compounded in the rubber composition can be improved, and a property inherent in silica which simultaneously allows a reduction of rolling resistance and a stability on wet road surfaces can be sufficiently effected.
1. A modified diene based polymer, wherein a diene based polymer is graft modified with a polyether having a mercapto group attached via diurethane bonding.
2. The modified diene based polymer according to claim 1 , wherein the polyether having a mercapto group attached via diurethane bonding is a polyalkylene oxide having an inert substituent at one end and a mercapto group attached via diurethane bonding at the other end.
3. The modified diene based polymer according to claim 2 , wherein the inert substituent at one end of the polyalkylene oxide is an alkyl group having 1 to 10 carbon atoms, an aryl group, or an aralkyl group.
4. The modified diene based polymer according to claim 2 , wherein the polyalkylene oxide having an inert substituent at one end and a mercapto group attached via diurethane bonding at the other end is produced via a series of steps:
(1) one monoisocyanate group of a diisocyanate compound is allowed to react with the polyalkylene oxide having an inert substituent at one end to generate a urethane bond;
(2) then, the other isocyanate group of the diisocyanate compound is allowed to react with dihydroxyalkyl disulfide or corresponding tetrasulfide to generate a urethane bond; and
(3) a sulfide bond of the resulting disulfide group or tetrasulfide group-containing compound is cleaved to generate mercapto groups.
5. The modified diene based polymer according to claim 1 , wherein the diene based polymer is natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene, chloroprene rubber, butyl rubber, styrene-butadiene rubber, nitrile rubber or EPDM.
6. The modified diene based polymer according to claim 1 , which is used to be added to a silica-containing rubber composition for automobile pneumatic tires.
7. The modified diene based polymer according to claim 3 , wherein the polyalkylene oxide having an inert substituent at one end and a mercapto group attached via diurethane bonding at the other end is produced via a series of steps:
(1) one monoisocyanate group of a diisocyanate compound is allowed to react with the polyalkylene oxide having an inert substituent at one end to generate a urethane bond;
(2) then, the other isocyanate group of the diisocyanate compound is allowed to react with dihydroxyalkyl disulfide or corresponding tetrasulfide to generate a urethane bond; and
(3) a sulfide bond of the resulting disulfide group or tetrasulfide group-containing compound is cleaved to generate mercapto groups.
8. The modified diene based polymer according to claim 5 , which is used to be added to a silica-containing rubber composition for automobile pneumatic tires.