Grease-proof paper and process of making the same

Claim 1

A PROCESS OF MAKING GREASE-PROOF PAPER WHICH COMPRISES APPLYING DIRECTLY TO THE SURFACE OF PAPER IN SHEET FORM A COATING OF AN AQUEOUS DISPERSION OF A RESINOUS COPOLYMER OF STYRENE AND BUTADIENE IN PROPORTIONS RANGING FROM 80 TO 90% OF STYRENE AND CORRESPONDINGLY FROM 20 TO 10% OF BUTADIENE AND A RUBBERY COPOLYMER TO BUTADIENE AND STYRENE IN PROPORTIONS RANGING FROM 50 TO 80% OF BUTADIENE AND CORRESPONDINGLY FROM 50 TO 20% OF STYRENE, SAID COPOLYMERS BEING EMPLOYED IN RELATIVE PROPORTIONS OF FROM 30 TO 80% OF SAID RESINOUS COPOLYMER AND CORRESPONDINGLY FROM 70 TO 20% OF SAID RUBBERY COPOLYMER, DRYING SAID COATING, SUBSEQUENTLY APPLYING OVER THE DRIED COATING A COATING OF AN AQUEOUS DISPERSION OF A RESINOUS COPOLYMER OF STYRENE AND ACRYLONITRILE IN PROPORTIONS RANGING FROM 65 TO 80% OF STYRENE AND CORRESPONDINGLY FROM 35 TO 20% OF ACRYLONITRILE AND A RUBBERY COPOLYMER OF BUTADIENE AND ACRYLONITRILE IN PROPORTIONS RANGING FROM 55 TO 80% OF BUTADIENE AND CORRESPONDINGLY FROM 45 TO 20% OF ACRYLONITRILE, SAID LASTNAMED RESINOUS AND RUBBERY COPOLYMERS BEING EMPLOYED IN RELATIVE PROPORTIONS OF FROM 45 TO 70% OF SAID LAST-NAMED RESINOUS COPOLYMER AND CORRESPONDINGLY FROM 55 TO 30% OF SAID LASTNAMED RUBBERY COPOLYMER, AND DRYING SAID LASTNAMED COATING.