Patent ID: 6239248
Filing Date: 2001-05-29
Classification: B32B,C08G,C08L,H05K,Y10T

Abstract:
In a laminate comprising superimposed porous substrates impregnated with a resinous matrix comprising an epoxy resin and a curing agent for the epoxy resin; the improvement which comprises said resinous matrix containing from about 1 to 35 parts by weight of a fluorescent polyphenol, said polyphenol being a member selected from the group consisting of a fluorescent phenol-glyoxal condensate, a fluorescent residue of a phenol-glyoxal condensate and mixtures thereof wherein the condensate is produced from a monohydric phenol and glyoxal by a method comprising(a) charging phenol to a reaction vessel and incrementally charging a total of about 0.15 to 0.22 moles of glyoxal for each mole of the phenol charged to the reaction vessel to form a reaction mixture at a temperature of about 80.degree. C. to 100.degree. C. in the presence of about 1% to 6%, based on the weight of phenol charged, of an acid catalyst which can be removed from the reaction mixture by heating and distilling the reaction mixture at a temperature below about 170.degree. C., said catalyst selected from the group consisting of oxalic acid, trichloroacetic acid and trifluoroacetic acid;(b) incrementally removing water from the reaction mixture;(c) maintaining the aldehyde equivalents in the reaction mixture at less than about 70% of the aldehyde equivalents in the total quantity of glyoxal to be charged for making the condensation product;(d) distilling the reaction mixture at a temperature of less than about 170.degree. C. to remove the acid catalyst when at least 85% of the aldehyde egivalents in the total quantity of glyoxal to be charged for making the condensation product have reacted, provided that prior to such distillation, a basic material is added to the reaction mixture in an amount sufficient to neutralize hydrochloric acid when the catalyst is trichloroacetic acid;(e) heating the reaction mixture at a temperature of about 175.degree. C. to 200.degree. C. for about 0.25 hours to 3 hours after step (d) above; and(f) removing unreacted phenol from the reaction mixture to obtain a phenol-glyoxal condensation product containing less than about 5% by weight of phenol.