REACTIVE SILICA IN EPOXIDIZED POLYBUTADIENER
A rubber composition that is based upon a cross-linkable elastomer composition comprising, per 100 parts by weight of rubber (phr) between 70 phr and 100 phr of an epoxidized rubber component selected from an epoxidized polybutadiene rubber (eBR), an epoxidized styrene-butadiene rubber (eSBR), or combinations thereof, wherein the epoxidized rubber component has a Tg of between −80° C. and −110° C. and an epoxy-function content of between 1 mol % and 25 mol %; between 30 phr and 150 phr of a plasticizing resin; and a quickly reactive silica that provides a macro dispersion Z-value of at least 50 in a defined rubber composition; and a non-silol coupling agent.
1 . A rubber composition that is based upon a cross-linkable elastomer composition, the cross-linkable elastomer composition comprising, per 100 parts by weight of rubber (phr):
between 70 phr and 100 phr of an epoxidized rubber component selected from an epoxidized polybutadiene rubber (eBR), an epoxidized styrene-butadiene rubber (eSBR), or combinations thereof, wherein the epoxidized rubber component has a Tg of between −80° C. and −110° C. and an epoxy-function content of between 1 mol % and 25 mol %;
between 30 phr and 150 phr of a plasticizing resin;
a quickly reactive silica that provides a macro dispersion Z-value of at least 50 in a defined rubber composition; and
a coupling agent corresponding to
Z-A-S z -A-Z
wherein x is an integer between 2 and 8, A is a divalent hydrocarbon radical and Z corresponds to one of the following:
wherein R 1 radicals are the same or different and are a C 1 -C 18 alkyl, C 5 -C 18 cycloalkyl or C 6 -C 18 aryl group, R 2 radicals are the same or different and are C 1 -C 18 alkoxyl or C 5 -C 18 cycloalkoxyl group and wherein R 2 radicals are not a hydroxyl radical.
2 . The rubber composition of claim 1 , wherein the quickly reactive silica that provides a macro dispersion Z-value of at least 60.
3 . The rubber composition of claim 2 , wherein the quickly reactive silica that provides a macro dispersion Z-value of at least 65
4 . The rubber composition of claim 1 , wherein the coupling agent is selected from bis-(triethoxysilylpropyl) tetrasulfide, bis-(triethoxysilylpropyl) disulfide or combinations thereof.
5 . The rubber composition of claim 1 , wherein the epoxidized rubber component is the eBR.
6 . The rubber composition of claim 1 , wherein the epoxidized rubber component is the eSBR.
7 . The rubber composition of claim 1 , wherein the quickly reactive silica has a BET surface area of between 140 m 2 /g and 180 m 2 /g as determined by ASTM 5604.
8 . The rubber composition of claim 1 , wherein the rubber composition comprises between 40 phr and 180 phr of the quickly reactive silica.
9 . The rubber composition of claim 1 , wherein the rubber composition includes less than 15 phr of carbon black.
10 . The rubber composition of claim 1 , wherein the plasticizing resin is an efficient plasticizing resin such that when included in a mixture consisting of the epoxidized rubber component and 67 phr of the efficient plasticizing resin, causes a Tg of the mixture to be at least 14° C. higher than the Tg of the epoxidized rubber component.
11 . The rubber composition of claim 1 , wherein the plasticizing resin is a terpene phenolic resin.
12 . The rubber composition of claim 1 , wherein a Tg of the rubber composition is between 0° C. and −35° C.
13 . The rubber composition of claim 1 , wherein the rubber composition further comprises between 0 phr and 30 phr of a highly unsaturated diene elastomer.
14 . The rubber composition of claim 13 , wherein the rubber composition further comprises between 5 phr and 30 phr of the highly unsaturated diene elastomer.
15 . A tire tread, comprising the rubber composition of claim 1 .
16 . The rubber composition of claim 5 , wherein the coupling agent is selected from bis-(triethoxysilylpropyl) tetrasulfide, bis-(triethoxysilylpropyl) disulfide or combinations thereof.
17 . The rubber composition of claim 16 , wherein the plasticizing resin is a terpene phenolic resin.
18 . The rubber composition of claim 6 , wherein the coupling agent is selected from bis-(triethoxysilylpropyl) tetrasulfide, bis-(triethoxysilylpropyl) disulfide or combinations thereof.
19 . The rubber composition of 18 , wherein the plasticizing resin is a terpene phenolic resin.