Silica masterbatch made with emulsion and solution rubber
First Claim
1. A process for making a silica masterbatch, comprising the steps of:
- (a) hydrophobating silica by;
(i) dissolving a trimethoxy silane coupling agent in a mixture of alcohol, acid and water to provide a trimethoxy silane coupling agent solution that contains at least about 75% water by weight, and(ii) mixing the trimethoxy silane coupling agent solution with silica and adding a base to increase the pH to form a compatibilized silica slurry, wherein the trimethoxy silane coupling agent is 3-mercaptopropyl trimethoxy silane, bis-(3-trimethoxysilylpropyl)-disulfide, bis-(3-trimethoxysilylpropyl)-tetrasulfide or a trimethoxy silane represented by the formula;
[(CH3O)3Si-(Alk)m-(Ar)p]q[B], whereB is —
SCN, R—
C(═
O)S, (if q=1) or Sx (if q=2);
Alk is a straight chained or branched bivalent hydrocarbon radical;
R is an alkyl group containing 1 to 18 carbons;
m is 0 or 1;
p is 0 or 1;
m+p=1;
q is 1 or 2;
Ar is an arylene radical having from 6 to 12 carbon atoms; and
x is a number from 2 to 8;
(b) making a polymer latex using a process for making an emulsion-made rubber;
(c) mixing the compatibilized silica slurry into the polymer latex;
(d) coagulating the polymer latex from step (c); and
(e) recovering a first silica-filled rubber, wherein either(i) solution-made rubber crumb particles are mixed into the polymer latex with the compatibilized silica slurry, wherein the solution-made rubber crumb particles are made in a solution process in which one or more monomers are polymerized in an organic solvent and coagulated to form the solution-made rubber crumb particles, and wherein the first silica-filled rubber is the silica masterbatch, or(ii) the first silica-filled rubber is added into a process for making a solution-rubber to make a second silica-filled rubber, wherein the second silica-filled rubber is the silica masterbatch, andwherein the silica masterbatch comprises a mixture of silica, emulsion-made rubber and solution-made rubber.
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Abstract
The present invention provides a process for making a silica masterbatch that contains hydrophobated silica, solution-made rubber and emulsion-made rubber. Hydrophobated silica is mixed into a latex emulsion. Solution-rubber crumb in an aqueous suspension is mixed into the latex emulsion, which is coagulated, and a crumb is recovered, further homogenized, dried and baled to yield the silica masterbatch. A well-dispersed mixture of hydrophobated silica and emulsion-made rubber is added into a steam distillation step of a solution-rubber process from which a silica masterbatch is recovered. The emulsion-made rubber can be omitted to make a silica masterbatch of solution rubber and silica without emulsion rubber. The silica masterbatch has physical properties similar to those found in a comparable dry-mixed composition, but the silica masterbatch can be incorporated more easily and less expensively into tires and other rubber products than the dry-mixed composition.
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Citations
17 Claims
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1. A process for making a silica masterbatch, comprising the steps of:
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(a) hydrophobating silica by; (i) dissolving a trimethoxy silane coupling agent in a mixture of alcohol, acid and water to provide a trimethoxy silane coupling agent solution that contains at least about 75% water by weight, and (ii) mixing the trimethoxy silane coupling agent solution with silica and adding a base to increase the pH to form a compatibilized silica slurry, wherein the trimethoxy silane coupling agent is 3-mercaptopropyl trimethoxy silane, bis-(3-trimethoxysilylpropyl)-disulfide, bis-(3-trimethoxysilylpropyl)-tetrasulfide or a trimethoxy silane represented by the formula;
[(CH3O)3Si-(Alk)m-(Ar)p]q[B], whereB is —
SCN, R—
C(═
O)S, (if q=1) or Sx (if q=2);Alk is a straight chained or branched bivalent hydrocarbon radical; R is an alkyl group containing 1 to 18 carbons; m is 0 or 1; p is 0 or 1; m+p=1; q is 1 or 2; Ar is an arylene radical having from 6 to 12 carbon atoms; and x is a number from 2 to 8; (b) making a polymer latex using a process for making an emulsion-made rubber; (c) mixing the compatibilized silica slurry into the polymer latex; (d) coagulating the polymer latex from step (c); and (e) recovering a first silica-filled rubber, wherein either (i) solution-made rubber crumb particles are mixed into the polymer latex with the compatibilized silica slurry, wherein the solution-made rubber crumb particles are made in a solution process in which one or more monomers are polymerized in an organic solvent and coagulated to form the solution-made rubber crumb particles, and wherein the first silica-filled rubber is the silica masterbatch, or (ii) the first silica-filled rubber is added into a process for making a solution-rubber to make a second silica-filled rubber, wherein the second silica-filled rubber is the silica masterbatch, and wherein the silica masterbatch comprises a mixture of silica, emulsion-made rubber and solution-made rubber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification