The Firestone Tire & Rubber Company

Gary R Hamed

Georg G Bohm

Lee E Vescelius

Donald N Schulz

Jung W Kang

Binnur Gunesin

A blend of natural and synthetic rubbers having processability and improved green strength and building tack is provided. The blend comprises from about 5 to 55 parts by weight of natural rubber, from about 30 to 50 parts by weight of a conjugated diene-containing synthetic rubber and, from about 5 to 50 parts by weight of a substituted acrylamide-containing synthetic rubber. The latter synthetic rubber comprises from about 0.3 to 10 percent by weight of an N-(alkoxymethyl)acrylamide monomer, based upon the weight of the substituted acrylamide-containing rubber.

Blends of natural and synthetic rubbers

Thermoplastic elastomer compositions of the present invention comprise a blend of from about 10 to about 50 parts by weight of a crystalline 1-olefin polymer, from about 80 to about 15 parts by weight of a styrene-butadiene rubber, and from about 5 to about 50 parts by weight of bitumen. The thermoplastic blends have unexpectant increases in properties, especially tear strength, tensile strength, high temperature (100.degree. C.) tear strength, and smooth surfaces when injection molded. Moreover, the bitumen lowers the injection molding pressure, thus enabling larger parts to be molded. The compositions, which may be partially cured, also have excellent aging properties. The compositions are a true thermoplastic in that they can be repeatedly processed and yet maintain their good physical properties.

Thermoplastic elastomer blends with bitumen

The invention disclosed herein provides a novel thermally reversible copolymer having up to about 11 percent by weight of an N-(alkoxymethyl)acrylamide, a diene-containing synthetic rubber and a metal. The thermally reversible copolymer can be blended with conventional styrene-butadiene rubbers to improve the green strength thereof. Also disclosed herein is a process for improving the green strength of styrene-butadiene rubber which includes the steps of charging a reaction vessel with water, an emulsifier, an initiator, an N-(alkoxymethyl)acrylamide monomer and a vinyl monomer where one is desired, purging the vessel with an inert gas, charging a diene monomer and an activator to the reaction vessel, polymerizing the monomers to form a colymer latex, coagulating the latex with an aqueous metal salt to form a thermally reversible polymer and compounding the thermally reversible polymer with styrene-butadiene rubber.

Thermally reversible copolymers and process for the preparation thereof

The invention disclosed herein provides a novel thermally reversible copolymer having up to about 11 percent by weight of an N-(alkoxymethyl)acrylamide, a diene-containing synthetic rubber and a metal. The thermally reversible copolymer can be blended with conventional styrene-butadiene rubbers to improve the green strength thereof. Also disclosed herein is a process for improving the green strength of styrene-butadiene rubber which includes the steps of charging a reaction vessel with water, an emulsifier, an initiator, an N-(alkoxymethyl)acrylamide monomer and a vinyl monomer where one is desired, purging the vessel with an inert gas, charging a diene monomer and an activator to the reaction vessel, polymerizing the monomers to form a copolymer latex, coagulating the latex with an aqueous metal salt to form a thermally reversible polymer and compounding the thermally reversible polymer with styrene-butadiene rubber.

The invention disclosed herein provides a novel thermally reversible copolymer having up to about 11 percent by weight of an N-(alkoxymethyl)acrylamide, a diene-containing synthetic rubber and a metal. The thermally reversible copolymer can be blended with conventional styrene-butadiene rubbers to improve the green strength thereof. Also disclosed herein is a process for improving the green strength of styrene-butadiene rubber which includes the steps of charging a reaction vessel with water, an emulsifier, an initiator, an N-(alkoxymethyl)-acrylamide monomer and a vinyl monomer where one is desired, purging the vessel with an inert gas, charging a diene monomer and an activator to the reaction vessel, polymerizing the monomers to form a copolymer latex, coagulating the latex with an aqueous metal salt to form a thermally reversible polymer and compounding the thermally reversible polymer with styrene-butadiene rubber.

Thermoplastic elastomer compositions of the present invention comprise a blend of from about 10 to about 50 parts by weight of a crystalline 1-olefin polymer, from about 80 to about 15 parts by weight of a styrene-butadiene rubber, and from about 5 to about 55 parts by weight of a highly saturated elastomer. The thermoplastic blends have very good physical properties, especially tear strength, tensile strength, elongation at break, low temperature impact resistance, minimum creep at high temperatures, and smooth surfaces when injection molded. The compositions, which may be partially cured, also have excellent aging properties, as well as paint adhesion. The compositions are a true thermoplastic in that they can be repeatedly processed and yet maintain their good physical properties.

Thermoplastic elastomer blends

Thermoplastic elastomer compositions of the present invention comprise a blend of from about 10 to about 48 parts by weight of a crystalline 1-olefin polymer, from about 90 to about 10 parts by weight of a styrene-butadiene rubber, and a triblock copolymer or a diblock copolymer in the amount of from about 0.1 to about 80 parts by weight or a polystyrene in the amount of from 0.1 to about 50 parts by weight. The thermoplastic elastomer blends have good physical properties, especially tensile strength, elongation at break, and tear strength. Moreover, the compositions can be repeatedly processed and yet maintain their good physical properties. The compositions, which may be partially cured, have excellent aging properties as well as paint adhesion.

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Akron, OH, United States of America

Gary R Hamed