Rubber stock composition for bonding to textile reinforcement containing a phenol-formaldehyde precursor wherein the formaldehyde precursor consists of a linear polyoxymethylene

Claim 2

A vulcanizable rubber stock composition adapted for forming a firm bond with a textile reinforceMent, the said rubber composition comprising a natural or synthetic rubber compound or blend of such compounds, a filler, a phenol and a precursor of formaldehyde, the said phenol and formaldehyde precursor adapted to form a resin during vulcanization, and the formaldehyde precursor consisting of a linear polyoxymethylene of the formula HO . (CH2O)n . H wherein n indicates the average degree of condensation and is between 100 and 1,000, the amounts of the several components relative to 100 parts of said rubber compound or blend being as follows: 1 to 5 parts of phenol, 0.5 to 3 parts of formaldehyde precursor and 10 to 100 parts of filler.

Claim 3

The composition of claim 1, wherein n is between 200 and 500.

Claim 4

The composition of claim 1, wherein the filler is activated silicic acid.

Claim 5

The composition of claim 1, wherein the filler is activated silicic acid together with carbon black.

Claim 6

The composition of claim 1, wherein the rubber is a styrene-butadiene, a chlorosulfonated polyethylene, an ethylene-propylene-diene terpolymer, or a chloroprene synthetic elastomer.

Claim 7

The process of making the rubber stock composition of claim 1, comprising subjecting a paraformaldehyde of an average chain length in excess of 30 and up to 100 to tempering at a temperature between 60* C. and 100* C. for a time of 1 to 4 days if employing atmospheric pressure, and for a time between 2 and 3 hours if employing a partial vacuum, and mixing the thus-obtained linear polyoxymethylene having the formula defined in claim 1 with a rubber compound, a filler and the said phenol suited, together with the formaldehyde, to form the said rubber stock composition.

Claim 8

The process of claim 6, wherein the phenol is resorcinol and the filler is activated silicic acid and wherein a premix is first formed of at least part of the silicic acid with the resorcinol or of these two components and the formaldehyde precursor, whereupon the premix is intimately mixed with the remaining components of the rubber stock composition.

Claim 9

The process of claim 7, wherein solid silicic acid, resorcinol and formaldehyde precursor are ground together to form the said premix.

Claim 10

The process of claim 7, wherein the resorcinol and formaldehyde precursor are applied in the form of a solution to the silicic acid to adhere thereto by adsorption whereupon the thus-formed mass is united with the remaining components by intimate mixture.

Claim 11

The process of claim 6 wherein the paraformaldehyde is first treated with dilute H2SO4 or NaOH whereupon it is filtered and the filter residue then is subjected to said tempering treatment.

Claim 12

The process of making the rubber stock composition of claim 1, comprising mixing a paraformaldehyde of an average chain length below 30 with finely ground solid acid in an amount of 0.1 to 5 percent of the mixture thus formed and then subjecting the paraformaldehyde to tempering at a temperature between 60* C. and 100* C. for a time between 1 and 4 days if atmospheric pressure is used and for a time between 2 and 3 hours if a partial vacuum is used and mixing the thus-obtained linear polyoxymethylene having the formula defined in claim 1 with a rubber compound, a filler and a phenol suited together with the formaldehyde to form a resin during vulcanization.

Claim 13

The process of claim 11 wherein the said acid is oxalic acid.

Claim 14

The process of claim 11 wherein the amount of said acid is 0.5 percent.

Claim 15

The process of claim 11 wherein the tempering is effected at a temperature of about 100* C. for a time between 20 and 24 hours.

Claim 16

The process of forming a composite textile reinforced rubber product, wherein a natural or synthetic rubber mixture is firmly bonded to a textile, the said process comprising the steps of intimately mixing with the rubber or rubber mixture (a) a finely divided activated filler in an amount of 10 to 100 parts of filler by weight per 100 parts of rubber and (b) a minor proportion of a combination of components adapted to form a resin during subsequent vulcanization of the rubber, the said combination of components comprising a phenol and a formaldehyde precursor and the said formaldehyde precursor consisting of a linear polyoxymethylene of the formula HO . (CH2O)n . H wherein n indicates the average degree of condensation and is between 100 and 1,000; and then vulcanizing the thus-modified rubber mixture onto the textile reinforcement.

Claim 17

The process of forming a composite textile reinforced rubber product, wherein a natural or synthetic rubber mixture is firmly bonded to a textile, the said process comprising the steps of intimately mixing with the rubber or rubber mixture (a) a finely divided activated filler in an amount of 10 to 100 parts of filler by weight per 100 parts of rubber and (b) a minor proportion of a combination of components adapted to form a resin during subsequent vulcanization of the rubber, the said combination of components comprising a phenol and a formaldehyde precursor and the said formaldehyde precursor consisting of a linear polyoxymethylene of the formula HO . (CH2O)n . H wherein n indicates the average degree of condensation and is between 100 and 1,000; and then vulcanizing the thus-modified rubber mixture onto the textile reinforcement.