Multiacrylate cross-linking agents in pressure-sensitive photoadhesives
AssigneeMinnesota Mining and Manufacturing Company
InventorsSteven M. Heilmann, John D. Moon
Life of this patent
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Abstract
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.
Claims19
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.times.10.sup.-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.
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.times.10.sup.-5 diacrylate equivalent per gram of component (a).
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.
Dependencies are inferred from the claim text.