To obtain an adhesive which can give a metal-clad laminate improved in electrical insulating properties by using an acid catalyst in the acetalization step in a process for producing the same.

An org. acid is used as the acid catalyst in the process for producing an adhesive for a metal-clad laminate by acetalizing PVA with an aldehyde in an org. solvent in the presence of an acid catalyst, neutralizing the reaction product, and mixing the resultant polyvinyl acetal resin soln. with a thermosetting resin. A method has already been proposed whereby the step of washing with water is eliminated by producing a polyvinyl acetal resin soln. by using an acid catalyst and the amt. of the solvent used is reduced by producing without removing a soln. used for the acetalization; however, when a metal foil coated with an adhesive obtd. by the proposed method is used for producing a metal-clad laminate, the electrical insulating properties are sometimes degraded. Using an org. acid as the catalyst improves the properties.