Fibrous web material impregnated with lignin-containing resin

Claim 1

A METHOD OF MAKING IMPREGNATED FIBROUS WEB MATERIAL WHICH COMPRISES THE STEPS OF ADDING TO AN A STAGE RESOLE ALKALI LIGNIN IN THE FREE ACID FORM TO FORM A MUTUAL SOLUTION OF SAID RESOLE AND SAID LIGNIN IN A VOLATILE SOLVENT MEDIUM WHEREIN THE RATIO BY DRY WEIGHT OF SAID RESOLE TO SAID LIGNIN IS FROM ABOUT 2:1 TO 1:6 AND THE PH OF WHICH IS SUBSTANTIALLY LESS THAN THAT OF SAID RESOLE, IMPREGNATING FIBROUS WEB MATERIAL WITH SAID SOLUTION, THE SAID RESOLE PULSE SAID LIGNIN BEING FROM ABOUT 15% TO ABOUT 60% BY DRY WEIGHT OF THE IMPREGNATED WEB, DRYING THE IMPREGNATED WEB MATERIAL TO REMOVE SAID VOLATILE SOLVENT MEDIUM, CURING THE DRIED IMPREGNATED FIBROUS WEB MATERIAL AT A TEMPERATURE BETWEEN ABOUT 200* F. AND ABOUT 350*F. AND AT A PRESSURE OF FROM ABOUT 300 P.S.I. TO ABOUT 6000 P.S.I. UNTIL SAID IMPREGNATED FIBROUS WEB MATERIAL HAS DEVELOPED A FLEXURAL STRENGTH OF AT LEAST ABOUT 15,000 P.S.I., AND DISCONTINUING CURING WHILE SAID IMPREGNATED FIBROUS WEB MATERIAL POSSESSES SUBSTANTIAL THERMOPLASTICITY AS DEFINED HEREIN AT A POSTFORMING TEMPERATURE BETWEEN ABOUT 200* F. AND ABOUT 350* F. THEREBY PROVIDING AN IMPROVED COMBINATION OF POSTFORMABILITY AND FLEXURAL STRENGTH AS COMPARED WITH LIKE EMPLOYMENT OF A CORRESPONDING AMOUNT OF IMPREGNANT BY DRY WEIGHT USING SAID RESOLE PER SE.