Glass-epoxy laminates for high temperature use

Claim 1

A method of making a laminate comprising at least one layer of sheet material containing a cured resin comprising the steps of: 1. admixing at a temperature of up to about 50° C: A. a mixture consisting essentially of: a. liquid epoxy resin, selected from the group consisting of a diglycidyl ether of bisphenol A having a viscosity range of about 2,500 cps. to about 20,000 cps. at 25° C and polyglycidyl ethers of a novolac having a viscosity range of about 1,500 cps. to about 20,000 cps. at 52° C to 55° C and mixtures thereof, and b. liquid NADIC methyl anhydride, with B. solid benzophenone-tetracarboxylic dianhydride, wherein the total anhydride plus dianhydride content is within the range of from about 0.60 to about 0.95 anhydride equivalents for each epoxy equivalent and the anhydride equivalent weight ratio of NADIC methyl anhydride: benzophenone-tetracarboxylic dianhydride is from about 0.50 to 0.90:1, to provide a homogeneous, stable dispersion of the solid dianhydride particles in the liquid without gellation, the dispersion containing about 98 percent to about 100 percent undissolved benzophenone-tetracarboxylic dianhydride; 2. adding organic solvent to the dispersion to give a solvent solution, 3. applying the solvent solution of the resinous admixture to a sheet material to coat or impregnate the material, and 4. curing the resin, to provide sheet material containing a solid resin.

Claim 2

A method of making a laminate comprising at least one layer of sheet material containing a cured resin comprising the steps of: 1. admixing at a temperature of up to about 50° C: A. a mixture consisting essentially of: a. liquid epoxy resin, selected from the group consisting of a diglycidyl ether of bisphenol A having a viscosity range of about 2,500 cps. to about 20,000 cps. at 25° C and polyglycidyl ethers of a novolac having a viscosity range of about 1,500 cps. to about 20,000 cps. at 52° C to 55° C and mixtures thereof, and b. liquid NADIC methyl anhydride, with B. solid benzophenone-tetracarboxylic dianhydride, wherein the total anhydride plus dianhydride content is within the range of from about 0.60 to about 0.95 anhydride equivalents for each epoxy equivalent and the anhydride equivalent weight ratio of NADIC methyl anhydride: benzophenone-tetracarboxylic dianhydride is from about 0.50 to 0.90:1, to provide a homogeneous, stable dispersion of the solid dianhydride particles in the liquid without gellation, the dispersion containing about 98 percent to about 100 percent undissolved benzophenone-tetracarboxylic dianhydride; 2. adding organic solvent to the dispersion to give a solvent solution, 3. applying the solvent solution of the resinous admixture to a sheet material to coat or impregnate the material, and 4. curing the resin, to provide sheet material containing a solid resin.