Microwave transparent thermosetting resin compositions, electrical laminates obtained therefrom, and process of producing these

A laminate for use in electrical applications, comprising at least one reinforcement substrate and a crossed linked layer of a thermosetting resin composition comprising

• (a) one or more terminally unsaturated urethanes selected from the group consisting of
• 1) one characterized by the formula
• where R1 is H or CH3, m is 2 or 3, and R3 is an organic residue from a diisocyanate, wherein the diisocyanate is selected from the group consisting of 2,4 toluene diisocyanate, 2,6 toluene diisocyanate, 2,4′-diphenylmethane diisocyanate and 2,6′-diphenyl methane diisocyanate or:
• 2) one characterized by the formula
• where R1, is H or CH3, m is 2 or 3, and R3 is an organic residue from a diisocyanate wherein the diisocyanate is selected from the group consisting of 2,4 toluene diisocyanate, 2,6 toluene diisocyanate, 2,4′-diphenylmethane diisocyanate and 2,6′-diphenyl methane diisocyanate, and R4 is an isocyanurate compound of the following structure
• (b) styrene monomer,
• (c) bromostyrene, characterized by the formula
• and
• (d) catalysts which induce free radical cure, polymerization, or UV initiation, in about 0.1% to about 2% by weight of the total composition,
• wherein, the ratio of the sum of components (a) to the sum of components (b) and
• (c) is less than 0.2, and the ratio of (b) to (c) is less than 1.5.