초록

Pressure-sensitive adhesive tape having a photopolymerized acrylate polymer adhesive which has been crosslinked by a polyacrylic-functional crosslinking monomer such as trimethyol-propane triacrylate.

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1. Method of making pressure-sensitive adhesive tape using a coatable mixture which is polymerizable by ultraviolet radiation to a pressure-sensitive adhesive state, which mixture comprises (a) partially polymerized acrylic acid ester of non-tertiary alcohol, the alkyl groups of which have an averag

1. Method of making pressure-sensitive adhesive tape using a coatable mixture which is polymerizable by ultraviolet radiation to a pressure-sensitive adhesive state, which mixture comprises (a) partially polymerized acrylic acid ester of non-tertiary alcohol, the alkyl groups of which have an average of about 4 to 14 carbon atoms, said acrylic acid ester being per se polymerizable to a sticky, stretchable, elastic adhesive mass and (b) a photoinitiator, which coatable mixture is (1) coated onto a backing member and (2) exposed to ultraviolet radiation to polymerize the mixture to a pressure-sensitive adhesive state, wherein the improvement comprises: dissolved in the mixture is polyacrylic-functional crosslinking monomer having less than 10 atoms in the chain between polymerizable vinyl groups and being present in an amount providing about 0.5 to 5×10 -5 diacrylate equivalent per gram of component (a), thus providing a crosslinked adhesive coating affording an Adhesion Value of at least 83 N/dm and a Shear Value of at least 1250 minutes. 2. Method as defined in claim 1 wherein component (a) includes at least one copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, an N-acryloylamino acid, and N-vinyl-2-pyrrolidone in an amount providing up to about 12% by weight of component (a). 3. Method as defined in claims 1 or 2, wherein component (a) is partially polymerized by virtue of a portion of the acrylic acid ester being fully polymerized and dissolved in an unpolymerized or incompletely polymerized portion. 4. Method as defined in claim 1 wherein the polyacrylic-functional crosslinking monomer is ethylene glycol diacrylate. 5. Method as defined in claim 1 wherein the polyacrylic-functional crosslinking monomer is trimethyolpropane diacrylate. 6. Method as defined in claim 1 wherein the polyacrylic-functional crosslinking monomer is pentaerythritol triacrylate. 7. Method as defined in claim 1 wherein the polyacrylic-functional crosslinking monomer is pentaerythritol tetracrylate. 8. A photoactive mixture having a coatable viscosity of 300 to 20,000 centipoises at ordinary room temperature and comprising (a) a partially polymerized acrylic acid ester of non-tertiary alcohol, the alkyl groups of which have an average of about 4 to 14 carbon atoms, said acrylic acid ester being per se polymerizable to a sticky, stretchable, elastic adhesive mass, and (b) a photoinitiator wherein the improvement comprises dissolved in the mixture is polyacrylic-functional crosslinking monomer having less than 10 atoms in the chain between polymerizable vinyl groups and being present in an amount providing about 0.5 to 5×10 -5 diacrylate equivalent per gram of component (a). 9. A photoactive mixture as defined in claim 8, wherein component (a) includes at least one copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, an N-acryloylamino acid, and N-vinyl-2-pyrrolidone in an amount providing up to about 12% by weight of component (a). 10. A photoactive mixture as defined in claims 8 or 9 wherein component (a) is partially polymerized by virtue of a portion of the acrylic acid ester being fully polymerized and dissolved in an unpolymerized or incompletely polymerized portion. 11. A photoactive mixture as defined in claims 8 or 9, wherein the polyacrylic-functional crosslinking monomer is ethylene glycol diacrylate. 12. A photoactive mixture as defined in claims 8 or 9, wherein the polyacrylic-functional crosslinking monomer is trimethyolpropane diacrylate. 13. A photoactive mixture as defined in claims 8 or 9, wherein the polyacrylic-functional crosslinking monomer is pentaerythritol triacrylate. 14. A photoactive mixture as defined in claims 8 or 9, wherein the polyacrylic-functional crosslinking monomer is pentaerythritol tetracrylate. 15. Pressure-sensitive adhesive tape comprising a flexible backing member and a pressure-sensitive adhesive coating comprising a copolymer of (a) a partially polymerized acrylic acid ester of non-tertiary alcohol, the alkyl groups of which have an average of about 4 to 14 carbon atoms, said acrylic acid ester being per se polymerizable to a sticky, stretchable, elastic adhesive mass, and (b) at least one copolymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, an N-acryloylamino acid, and N-vinyl-2-pyrrolidone in an amount providing up to about 12% by weight of component (a), which adhesive coating is free from chlorine and other corrosive material, wherein the improvement comprises, the tape has an Adhesion Value as herein defined of at least 83 N/dm and a Shear Value of at least 1250 minutes. 16. Pressure-sensitive adhesive tape as defined in claim 15 wherein said copolymer has been crosslinked by a polyacrylic-functional crosslinking monomer having less than 10 atoms in the chain between polymerizable vinyl groups in an amount providing about 0.5 to 5×10 -5 diacrylate equivalent per gram of component (a). 17. Pressure-sensitive adhesive tape as defined in claim 16 wherein said polyacrylic-functional crosslinking monomer was trimethyolpropane triacrylate. 18. Pressure-sensitive adhesive tape as defined in claim 16 wherein said polyacrylic-functional crosslinking monomer was pentaerythritol tetracrylate. 19. Pressure-sensitive adhesive tape as defined in claim 16 wherein said polyacrylic-functional crosslinking monomer was 1,2-ethylene glycol diacrylate.