Method of preparing a phenolic aldehyde resin and resin composition for an adhesive system to be applied to glass fibers

Abstract

A method of preparing a thermoplastic, long-chain water-soluble, phenolic formaldehyde resin and the composition are provided to enhance the flexibility and resistance to compression fatigue breakage of glass fibers to which the resin has been applied. The method involves two steps. In the first step, the phenolic compound and the formaldehyde are reacted to less than 100 percent completion in an amount so that the formaldehyde to resorcinol ratio is in the range of about 0.6 to about 2.0 and at an acidic pH and for a period of time equivalent to about 1 hour to about 20 hours when the temperature is in the range of about 30.degree. F.(-31 1.1.degree. C.) to about 122.degree. F. (50.degree. C.) to produce a resinous mixture having a predominant amount of trimer polymer along with minor amounts of dimer and higher oligomer polymers and along with unreacted phenolic compound and aldehyde. In the second stage the pH of the reaction is adjusted within the range above of about 7.0 to about 7.5 and the reaction is continued between the unreacted phenolic compound and aldehyde and resinous mixture to produce a resinous mixture composition that is thermoplastic, and water soluble and has a predominant amount of trimer polymer with slight cross-linkage and a minor amount of dimer and higher oligomer polymers. The composition of the phenolic aldehyde resin prepared according to this method is a mixture of polymer forms, containing predominantly the trimer polymer.

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