Pressure-sensitive adhesive tape

Claim 1

A PRESSURE-SENSITIVE ADHESIVE TAPE WHICH IS SUITABLE FOR MASKING IN CHEMICAL MILLING OPERATIONS CARRIED OUT AT TEMPERATURES AS HIGH AS 190*F., WHICH CAN BE READILY REMOVED AFTER THE MILLING OPERATION IS COMPLETED AND THEREAFTER RE-APPLIED AS A PROTECTIVE COVER, SAID TAPE COMPRISING IN COMBINATION: A SMOOTH, HYDROPHOBIC, NON-ABSORBENT ACID- AND BASE-RESISTANT SHEET BACKING MATERIAL HAVING ADHERED TO ONE SURFACE THEREOF A NORMALLY TACKY AND PRESSURE-SENSITIVE ADHESIVE, SAID ADHESIVE COMPRISING A RUBBERY BUTADIENE:STYRENE COPOLYMER CROSSLINKED WITH AN OILSOLUBLE HEAT-REACTIVE PHENOLIC RESIN, A TACKIFIER FOR SAID COPOLYMER, AND A CROSSLINKED ACID- AND BASE-RESISTANT CHLOROSULFONATED POLYETHYLENE POLYMER, SAID POLYMER BEING COMPATIBLE WITH BOTH SAID COPOLYMER AND SAID TACKIFIER, THE EXPOSED SURFACE OF SAID PRESSURE-SENSITIVE ADHESIVE BEING SUBSTANTIALLY FREE FROM IRREGULARITIES, THEREBY PERMITTING SAID TAPE TO BE APPLIED TO A METAL SURFACE IN SUCH A MANNER THAT SAID ADHESIVE ESTABLISHES UNIFORM INTIMATE CONTACT WITH SAID METAL.