Puncture sealing composition and tire

A puncture sealing composition for a tubeless pneumatic tire comprising a blend of

• A. from more than 50% to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps in admixture with a plasticizing or tackifying substance, and
• B. correspondingly from less than 50% to 10% by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms,
• said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20% to 50% by weight based on the weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.

A puncture sealing composition for a tubeless pneumatic tire comprising a blend of

• A. from more than 50% to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst with
• B. correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms,
• said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.

A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a fiber-free blend of

• A. a major proportion by weight of a low molecular weight liquid elastomer in admixture with a tackifying or plasticizing substance, and
• B. a minor proportion by weight of a high molecular weight solid elastomer,
• said blend being partially crosslinked to an extent sufficient to prevent the blend from flowing at elevated temperatures and centrifugal forces encountered in the tire in use, the partially crosslinked blend having sufficient adhesion and conformability to function as a sealant in the tire, the amount of (A) being from more than 50% to 90% by weight and the amount of (B) being correspondingly from less than 50% to 10% by weight, based on the combined weights of the two elastomers, the said low molecular weight elastomer being a liquid rubber having a Brookfield viscosity at 150.degree. F of from 20,000 to 2,000,000 cps and the said high molecular weight elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F, the said composition containing a crosslinking agent selected from the following, present in the amounts recited:
• from more than 0.5 to 2.0 parts of sulfur or sulfur-yielding curative;
• from more than 0.5 to 2.0 parts of quinoid curative;
• from 0.1 to 1.0 part of radical generating curative;
• from 2 to 10 parts of polyisocyanate curative;
• and
• from 2 to 10 parts of tetrahydrocarbyl titanate ester curative,
• the said parts of crosslinking agent being by weight based on 100 parts of the combined weight of the two elastomers, the gel content of the blend in the partially crosslinked state being from 15 to 60% by weight of the blend, as measured in toluene at room temperature, and the peak Mooney viscosity of the blend in the partially crosslinked state being from 30 to 55 ML at 150.degree. F.

A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of

• A. from more than 50 to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps and a tackifying or plasticizing substance with
• B. correspondingly from less than 50 to 10% by weight of a high molecular solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.

A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with a filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of

• A. from more than 50 to 90% by weight of a low molecular weight liquid elastomer having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps in admixture with a tackifying or plasticizing substance, and
• B. correspondingly from less than 50 to 10% by weight of a high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• and from 2.5 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms,
• said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encounterd in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.

A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, and a puncture sealing layer inside the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of

• A. from more than 50 to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst with
• B. correspondingly from less than 50 to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 15 to 60% by weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 30 to 55 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperature and centrifugal forces encountered in the tire in use and the blend has sufficient adhesion and conformability to function as a sealant in the tire.

A puncture sealing tubeless pneumatic tire having a vulcanized rubber tread portion surmounting a vulcanized rubber carcass portion reinforced with filamentary material, said carcass portion having a crown area underlying the tread, and having sidewall portions extending from shoulder areas at the edges of the crown area to bead areas containing inextensible circumferential reinforcement, the interior surface of the tire being covered with an air-impervious liner, and a puncture sealing layer inside the tire disposed across the crown area of the tire and extending at least from one shoulder area to the other, said puncture sealing layer comprising a blend of

• A. from more than 50 to 90% by weight of liquid heat depolymerized natural rubber having a Brookfield viscosity at 150.degree. F of from 20,000 to 1,000,000 cps and a resin prepared from the reaction of a mineral oil purification product with formaldehyde and with nitric acid catalyst with
• B. correspondingly from less than 50% to 10% by weight of cis-polyisoprene elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212.degree. F,
• and from 2 to 10 parts, per 100 parts by weight of the two elastomers, of a tetraalkyl titanate ester crosslinking agent in which the alkyl groups have from 1 to 12 carbon atoms,
• said blend being partially crosslinked by the said crosslinking agent to provide in the blend a gel content of from 15 to 60% by weight based on the weight of the blend as measured in toluene at room temperature and a peak Mooney viscosity of from 40 to 50 ML at 150.degree. F, whereby the blend is prevented from flowing at elevated temperatures and centrifugal forces encountered in the tire in use and the blend has suffficient adhesion and conformability to function as a sealant in the tire.