Abstract: Bubble- or void-free electrical laminates such as unclad or metal clad laminates are produced by impregnating a porous fibrous substrate with a solvent-free liquid resin capable of curing to a rigid state without producing a volatile by-product, combining a plurality of impregnated substrates to form a unitary member, allowing substantially all of entrapped air bubbles retained in the combination to disappear by dissolving into the liquid resin, and then curing the combination.

Abstract: A continuous process for producing reinforced resin laminates comprising the steps of impregnating a fibrous substrate with a liquid resin which is free of volatile solvent and is capable of curing without generating liquid and gaseous byproducts, laminating a plurality of the resin-impregnated substrates into a unitary member, sandwiching the laminate between a pair of covering sheets, and curing the laminate between said pair of covering sheets without applying appreciable pressure. The improvement comprises adjusting the final resin content in said resin impregnated substrate at 10 to 90% by weight based on the total weight of said impregnated substrate.

Abstract: An electrical laminate comprising layers of a resin impregnated fibrous substrate is disclosed. The resin has a glass transition point from about 20.degree. C. to 80.degree. C. and comprises a cured product of a mixture of an unsaturated polyester polymer and a cross-linking monomer. The laminate exhibits an improved punchability at a temperature not lower but not 20.degree. C. higher than the glass transition point of the resin.

Abstract: An electrical laminate comprising layers of an unsaturated polyester resin-impregnated fibrous cellulosic substrate is disclosed. The substrate is preimpregnated with a mixture and/or a condensate of an aminoplast with a higher fatty derivative having at least one functional group capable of condensation with the methylol group of aminoplast. The laminate exhibits improved moisture resistance and punchability.

Abstract: An electrical laminate comprising layers of a polyester resin-impregnated fibrous cellulosic substrate is disclosed. The substrate is preimpregnated with a nitrogen-containing composition having (a) an N-methylol or N-lower alkoxymethyl group attached to said nitrogen atom, and (b) an unsaturated group capable of copolymerizing with a cross-linking monomer present in the polyester resin.