Benzothiazyl sulfenamides as scorch retardants for mercaptosilane-coupled silica filled-rubber compounds

Claim 2

A sulfur-vulcanizable rubber compound exhibiting prlonged time-to-scorch comprising at least one sulfur-vulcanizable diene rubber, a siliceous filler, a silane coupling agent consisting of a mercaptoalkyltrialkoxysilane coupling agent represented by (OR) 3 SiR 1 SH wherein R and R 1 each represent an alkyl group of 1 to 10 carbon atoms per molecule, and a benzothiazyl sulfenamide accelerator at a level of about 2 phr and above.

Claim 3

The composition according to claim 1 wherein said sulfur-vulcanizable diene rubber is selected from the group consisting of natural rubbers, synthetic conjugated diene rubbers, and mixtures.

Claim 4

The composition according to claim 2 further employing a carbon black with said siliceous filler.

Claim 5

The composition according to claim 1 wherein said siliceous filler is an amorphous silica, finely divided clay, kaolin, hydrated aluminum silicate, magnesium silicate, calcium silicate, or mixture thereof.

Claim 6

The composition according to claim 3 employing a ratio of about 1:99 to 99:1 weight ratio of carbon black:siliceous filler.

Claim 7

The composition according to claim 5 wherein said carbon black:siliceous filler ratio is in the range of about 1:20 to 1:1.

Claim 8

The composition according to claim 6 wherein said sulfur-vulcanizable diene rubber comprises an admixture of a synthetic diene rubber and a natural rubber.

Claim 9

The composition according to claim 1 or 3 employing a weight ratio of mercaptoalkyltrialkoxysilane coupling agent:siliceous filler of about 1:100 to 1:5.

Claim 10

The composition according to claim 8 wherein said mercaptoalkyltrialkoxysilane coupling agent is selected from the group consisting of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethyoxysilane, 2-mercaptoethyltrimethyoxysilane, 2-mercaptoethyltriethoxysilane, and mixtures.

Claim 11

The composition according to claim 8 further incorporating an extender oil.

Claim 12

The composition according to claim 1 or 3 wherein said benzothiazyl sulfenamide vulcanization accelerator is represented by the general formula: ##STR2## wherein each R 2 and R 3 is individually selected from the group consisting of hydrogen, nitro, chloro, alkyl radicals having 1 to 4 carbon atoms, and alkoxy radicals having 1 to 4 carbon atoms; R 4 is selected from the group consisting of alkyl radicals having 1 to 6 carbon atoms, and aryl radicals having 6 to 13 carbon atoms; R 4 and R 5 can be joined through a member selected from the group consisting of --CH 2 --, --O--, and --S-- to constitute with the attached nitrogen group a heterocyclic radical; and R 5 is individually selected from the group consisting of R 4 and hydrogen.

Claim 13

The composition according to claim 11 wherein said benzothiazyl sulfenamide accelerator is selected from the group consisting of N-t-butyl-2-benzothiazyl sulfenamide, N-cyclohexyl-2-benzothiazyl sulfenamide, N-isopropyl-2-benzothiazyl sulfenamide, N-oxydiethylene-2-benzothiazyl sulfenamide, N,N-diisopropyl-2-benzothiazyl sulfenamide, N,N-diethyl-2-benzothiazyl sulfenamide, N,N-dicyclohexyl-2-benzothiazyl sulfenamide, 2-(4-morpholinodithio)-benzothiazole, and mixtures.

Claim 14

The composition according to claim 12 further incorporating an extender oil.

Claim 15

The composition according to claim 1 or 3, further incorporating an extender oil.

Claim 16

The composition according to claim 14 comprising: ______________________________________ Conjugated diene polymer 100 parts by weight Siliceous Filler 20-100 parts by weight Mercaptoalkyltrialkoxysilane 1-10 parts by weight Coupling Agent Benzothiazyl Sulfenamide Accelerator 2-5 parts by weight Sulfur 1-5 parts by weight Zinc Oxide 2-6 parts by weight Stearic Acid 1-5 parts by weight Carbon Black 0-30 parts by weight Extender Oil 5-60 parts by weight Antidegradants 1-4 parts by weight. ______________________________________

Claim 17

The composition according to claim 14 comprising 100 parts by weight of a diene rubber selected from natural rubber and admixtures of a natural rubber with a cis-polybutadiene, about 40 parts by weight silica, about 3 parts by weight 3-mercaptopropyl-trimethoxysilane, about 2 to 3 parts by weight benzothiazyl sulfenamide, about 2 parts by weight sulfur, about 4 parts by weight zinc oxide, about 2.5 parts by weight stearic acid, about 2.5 parts by weight amine-type antidegradant, about 10 parts by weight highly aromatic extender oil, and about 18 parts by weight carbon black N 234.

Claim 18

The composition according to claim 14 comprising about 60 parts by weight of a butadiene/styrene copolymer, about 40 parts by weight cis-polybutadiene, about 75 parts by weight silica, about 3 parts by weight 3-mercaptopropyl-trimethoxysilane, about 3 parts by weight benzothiazyl sulfenamide, about 2 parts by weight sulfur, about 3 parts by weight zinc oxide, about 2 parts by weight stearic acid, about 2.5 parts by weight of a mixture of amine and quinoline antidegradant, and about 40 parts by weight aromatic extender oil.

Claim 19

The composition according to claim 1 or 3, cured.

Claim 20

The composition according to claim 8 cured.

Claim 21

The composition according to claim 11 cured.

Claim 22

The composition according to claim 14 cured.

Claim 23

The composition according to claim 15 cured.

Claim 24

The composition according to claim 16 cured.

Claim 25

The composition according to claim 17 cured.