Curable pressure sensitive adhesive compositions
Curable pressure sensitive adhesive compositions comprising an acrylate copolymer, a mono-acrylate oligomer, a multi-acrylate oligomer having from 2 to 5 acrylate functional groups per molecule, and a photoinitiator, the adhesive exhibiting pressure sensitive adhesive characteristics and forms at least a semi-interpenetrating polymer network when cured; wherein the semi-IPN has an average molecular weight between crosslinks (M c ) greater than about 3000, and the cured adhesive has a peel strength greater than about 40 N/dm. Embodiments of the adhesive compositions, when cured, are optically clear and resistant to heat and moisture.
1. An optical construction comprising
an optical film having a major surface;
an adhesive applied to at least a portion of said major surface, wherein said adhesive comprises an acrylate copolymer;
a mono-acrylate oligomer;
a multi-acrylate oligomer having 2 to 5 acrylate functionalities; and
a photoinitiator that initiates free radical polymerization;
wherein said mono-acrylate oligomer is present in an amount greater than the amount of said multi-acrylate oligomer, and wherein said mono-acrylate oligomer, multi-acrylate oligomer and photoinitiator, when blended with said acrylate copolymer, forms a pressure sensitive adhesive, and when cured, forms a cured adhesive comprising at least a semi-interpenetrating polymer network having an average molecular weight between crosslinks (M c ) greater than about 3000, said cured adhesive having a peel strength greater than about 40 N/dm; and
a substrate bonded to said optical film, having said adhesive cured therebetween.
2. The construction of claim 1 , wherein said optical film is capable of reflecting infra-red light.
3. The construction of claim 1 , wherein at least one of said optical film and said substrate is an outgassing material.
4. The construction of claim 1 , wherein said substrate comprises a material selected from a group consisting of glass, polycarbonate, polyethylene, polyurethane and polyacrylates, and combinations thereof.
5. The construction of claim 1 , wherein said optical film is selected from a group consisting of multi-layer optical film, polycarbonate, polyester, polyurethane, polyacrylate, polyvinyl alcohol, polyethylene, polyvinyl chloride, cellulose triacetate and combinations thereof.
6. The construction of claim 1 , wherein said adhesive composition further comprises a UV absorber.
7. A method of making an optical construction comprising
a) providing an optical substrate;
b) applying onto a major surface of said optical substrate, an adhesive composition comprising
an acrylate copolymer;
a mono-acrylate oligomer;
a multi-acrylate oligomer having from 2 to 5 acrylate functionalities; and
a photoinitiator that initiates free radical polymerization;
wherein said mono-acrylate oligomer is present in an amount greater than the amount of said multi-acrylate oligomer, and wherein said mono-acrylate oligomer, multi-acrylate oligomer and photoinitiator, when blended with said acrylate copolymer, forms a pressure sensitive adhesive, and when cured, forms a cured adhesive comprising at least a semi-interpenetrating polymer network having an average molecular weight between crosslinks (M c ) greater than about 3000, said cured adhesive having a peel strength greater than about 40 N/dm;
c) positioning a major surface of a second substrate adjacent said major surface of said optical substrate, with said adhesive therebetween; and
d) actinically curing said adhesive.
8. The method according to claim 7 , wherein said steps a) thru d) are performed sequentially.
9. The method according to claim 7 , wherein said actinically curing said adhesive is conducted using UV irradiation.
10. The method according to claim 7 , wherein said adhesive composition is applied onto said major surface of said optical substrate as a tape.
11. The method according to claim 7 , wherein said optical substrate is a film selected from a group consisting of multi-layer optical film, polycarbonate, polyester, polyurethane, polyacrylate, polyvinyl alcohol, polyethylene, polyvinyl chloride, cellulose triacetate and combinations thereof.