Patent GB-1515068-A (GB)
Title: Hardenable boron-containing reinforcing resins for rubber
IPC: C08L23/00
Filed: 1976-12-16
Abstract: 1515068 Boron-containing reinforcing resins for rubber BAYER AG 16 Dec 1976 [20 Dec 1975] 52526/76 Headings C3R and C3M A process for the production of a hardenable boron-containing reinforcing resin for rubber comprises reacting together (a) a diphenylol alkane novolak having an average molecular weight of from 400 to 1600 which is a reaction product of at least one aldehyde with at least one diphenylol alkane of the general formula in which R is C1-C8-alkyl or C5-C12-cycloalkyl, R' is H or R, or R and R<1> is C4-C7-alkylene, whereby R and R<1> form a carbocyclic ring with the carbon atom by which they are joined, and R" is H or C1-C4-alkyl, or with a mixture of at least one diphenylol alkane of the above formula and at least one hydroxy phenyl hydroxy indane of the general formula (b) from 20 to 100 p.b.w. of a boric acid trialkyl ester containing 1 to 4 carbon atoms per alkyl group, or from 18 to 90 p.b.w. of boric acid in the presence of a C1-C4-alcohol, or from 10 to 50 p.b.w. of boron trioxide in the presence of a C1-C4 alcohol, and (c) from 15 to 35 p.b.w. of an unsaturated fatty acid or ester thereof, the p.b.w. being based on 100 p.b.w. of the diphenylol alkane. A boron-containing resin obtainable by the above process is generally soluble in methanol, ethanol, propanol, isopropanol, butanol, isobutanol, dioxane, tetrahydrofuran, acetone, methylethylketone, ethyl and butyl acetates, methyl and ethyl glycol acetate, and has an iodine number of 80 to 200, an OH number of 200 to 500 and a boron content of up to 7% wt. The preferred diphenylolalkane is bisphenol A. The aldehyde may be chloral, furfural, propionaldehyde, butyraldehyde, acetaldehyde or formaldehyde and is preferably an aqueous formalin solution, trioxane or paraformaldehyde. Suitable unsaturated fatty acids contain 24-41 carbon atoms, and the esters thereof preferably contain 1-4 carbon atoms in the alcohol moiety. Mono-, di- or tri-glycerides may also be used. Examples of such acids and esters are linseed oil-, soya oil-, tall oil-, peanut oil-, and commercialgrade conjugated unsaturated-fatty acids, castor oil, ricinoleic acid, ricinene fatty acid, and glycerides or methyl esters thereof. The boroncontaining resin can be incorporated as a reinforcing resin in a natural and/or synthetic rubber, preferably in an amount of from 5-100 p.b.w. per 100 p.b.w. of rubber, in the presence of a formaldehyde donor, such as hexamethylenetetramine, paraformaldehyde, trioxy- or tetraoxymethylene. Suitable rubbers are styrene - butadiene rubber, chloroprene rubber nitrile rubber, isoprene rubber, butadiene rubber, EPDM, butyl rubber and trans-polypentenamer rubber. Fillers, e.g. active silicas, carbon black, kaolin and chalk; anti-agers, crosslinkers, vulcanization accelerators and other standard additives may be added to the rubbers. In Example 1 a boron-containing resin prepared as above from a bisphenol-A-formaldehyde novolak, prepared using first oxalic acid and then phosphoric acid as catalysts; boron trioxide, ethanol and castor oil using toluene as solvent is used to reinforce a standard rubber mixture based on styrene-butadiene rubber or acrylonitrile-butadiene rubber, containing hexamethylenetetramine and conventional additives and the resulting mixtures are vulcanized.