Puncture sealing composition and tire

Claim 2

A puncture sealing composition for a tubeless pneumatic tire 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, and a crosslinking agent for the elastomers in amount effective to partially crosslink the elastomers to an extent sufficient to prevent the blend from flowing at elevated temperatures and centrifugal forces encountered in the tire in use, the blend having in the partially crosslinked state 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 (A) and (B), the said low molecular weight elastomer being a liquid rubber having a Brookfield viscosity at 150° 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° F, the said crosslinking agent being 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° F.

Claim 3

A puncture sealing composition as in claim 1 in which the liquid rubber is heat depolymerized natural rubber.

Claim 4

A puncture sealing composition as in claim 1 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid polybutadiene, liquid polybutene, liquid ethylene-propylene-non-conjugated diene terpolymer rubber, and liquid isobutylene-isoprene copolymer rubber.

Claim 5

A puncture sealing composition as in claim 1 in which the high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.

Claim 6

A puncture sealing composition as in claim 1 in which (A) is liquid heat depolymerized natural rubber in admixture with a resin prepared from the reaction of a mineral oil purification residue with formaldehyde and with nitric acid catalyst and (B) is solid cis-polyisoprene rubber.

Claim 7

A puncture sealing composition as in claim 1 in which the tackifying or plasticizing substance is selected from resin esters, aliphatic petroleum hydrocarbon resins, polyterpene resins, styrene resins, dicyclopentadiene resins, and resins prepared from the reaction of a mineral oil purification residue with formaldehyde and with a nitric acid catalyst.

Claim 8

A puncture sealing composition for a tubeless pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of low molecular weight liquid elastomer having a Brookfield viscosity at 150° 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 high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212° F, said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 20 to 50% 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° 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.

Claim 9

A puncture sealing composition for a tubeless pneumatic tire comprising a blend of A. from more than 50% to 90% by weight of low molecular weight liquid elastomer having a Brookfield viscosity at 150° 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 high molecular weight solid elastomer having a Mooney viscosity of from 20 to 160 ML-4 at 212° F, said blend being partially crosslinked to an extent sufficient to provide in the blend a gel content of from 20 to 50% 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° 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.

Claim 10

A puncture sealing composition as in claim 7 in which the said partial crosslinking is effected by subjecting the said blend to electron radiation.

Claim 11

A puncture sealing composition as in claim 7, devoid of fibrous filler, in which the said high molecular weight solid elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.

Claim 12

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° 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° 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° 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.

Claim 13

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° 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° 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° 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.

Claim 14

A puncture sealing composition as in claim 10 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 2.5 to 8 parts per 100 parts by weight of the two elastomers, and the composition is devoid of fibrous filler.

Claim 15

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° F of from 20,000 to 2,000,000 cps in admixture with a plasticizing or tackifying substance, and 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° 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° 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.

Claim 16

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° F of from 20,000 to 2,000,000 cps in admixture with a plasticizing or tackifying substance, and 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° 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° 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.

Claim 17

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° 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° 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° 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.

Claim 18

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° 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° 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° 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.

Claim 19

A puncture sealing composition as in claim 13 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetraalkyl titanate crosslinking agent is from 3 to 8 parts per 100 parts by weight of the two elastomers.

Claim 20

A puncture sealing composition as in claim 13 in which the tetraalkyl titanate ester crosslinking agent is tetra-n-butyl titanate.

Claim 21

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° 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° 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° F.

Claim 22

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° 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° 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° F.

Claim 23

A tire as in claim 16 in which the tackifying or plasticizing substance is selected from rosin esters, aliphatic petroleum hydrocarbon resins, polyterpene resins, styrene resins, dicyclopentadiene resins, and resins prepared from the reaction of a mineral oil purification residue with formaldehyde and with a nitric acid catalyst.

Claim 24

A tire as in claim 16 in which the said puncture sealing layer is disposed on the inside surface of the said liner.

Claim 25

A tire as in claim 16 in which the said sealing layer is sandwiched between the liner and the inside surface of the carcass.

Claim 26

A tire as in claim 16 in which the liquid rubber is heat depolymerized natural rubber.

Claim 27

A tire as in claim 16 in which the low molecular weight elastomer is selected from the group consisting of liquid cis-polyisoprene, liquid polybutadiene, liquid polybutene, liquid ethylene-propylene-non-conjugated diene terpolymer rubber, and liquid isobutylene-isoprene copolymer rubber.

Claim 28

A tire as in claim 16 in which the high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a monomer proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.

Claim 29

A tire as in claim 16 in which the low molecular weight elastomer is liquid heat depolymerized natural rubber and the high molecular weight elastomer is solid cis-polyisoprene rubber.

Claim 30

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° 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° 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° 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.

Claim 31

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° 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° 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° 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.

Claim 32

A tire as in claim 24, in which the said blend is devoid of fibrous filler, and in which the said high molecular weight elastomer is selected from the group consisting of conjugated diolefin homopolymer rubbers, copolymers of a major proportion of a conjugated diolefin with a minor proportion of a copolymerizable monoethylenically unsaturated monomer, copolymers of isobutylene with a small amount of isoprene, ethylene-propylene-non-conjugated diene terpolymers, and saturated elastomers.

Claim 33

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° 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° 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° 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.

Claim 34

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° 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° 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° 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.

Claim 35

A tire as in claim 26 in which the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, the amount of said titanate ester is from 2.5 to 8 parts per 100 parts by weight of the two elastomers, and the composition is devoid of fibrous filler.

Claim 36

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° 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° 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° 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.

Claim 37

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° 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° 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° 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.

Claim 38

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° 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° 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° 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.

Claim 39

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° 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° 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° 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.

Claim 40

A tire as in claim 29 in which the gel content of the blend is from 20 to 50% by weight based on the weight of the blend as measured in toluene at room temperature, the alkyl groups in the said tetraalkyl titanate ester crosslinking agent have from 3 to 8 carbon atoms, and the amount of tetraalkyl titanate crosslinking agent is from 2.5 to 8 parts per 100 parts by weight of the two elastomers.

Claim 41

A tire as in claim 30 in which the tetraalkyl titanate ester crosslinking agent is tetra-n-butyl titanate.

Claim 42

A tire as in claim 24 in which the said partial crosslinking is effected by subjecting the said blend to electron radiation.

Claim 43

A tire as in claim 30 in which the tetraalkyl titanate ester crosslinking agent is tetrapropyl titanate.