Adhesive blends, articles, and methods
Described are adhesive compositions containing a mixture of a pressure sensitive adhesive, a high Tg polymer, and a crosslinker to form a compatibilized blend that is optically clear. Methods of using the adhesive compositions, and multilayer assemblies such as optical elements prepared using the adhesives, are also provided.
1. An adhesive composition comprising a blend of:
a majority of a pressure sensitive adhesive component comprising at least one polymer with an acid functionality, wherein the pressure sensitive adhesive is formed from alkyl (meth)acrylate monomers having an alkyl group comprising from 4 to 12 carbon atoms,
a high Tg polymer with a glass transition temperature greater than 20° C. and a weight average molecular weight greater than 100,000 wherein the high Tg polymer is a basic copolymer, and wherein the high Tg polymer comprises a copolymer formed from methyl methacrylate, butyl methacrylate, and dimethylamino ethylmethacrylate; and
a crosslinker;
wherein the functionality of the pressure sensitive adhesive component and the functionality of the high Tg polymer form an acid-base interaction when mixed, and after aging at 80° C. and 90% relative humidity for 500 hours, the composition is optically clear on visual observation so that the composition exhibits a luminous transmission of at least about 90% and a haze of less than about 2% when measured according to ASTM-D 1003-95.
2. The adhesive composition of claim 1 , wherein the high Tg polymer has a glass transition temperature greater than 50° C.
3. The adhesive composition of claim 2 wherein the pressure sensitive adhesive component is present in an amount ranging from about 70 to 90 percent by weight, and the high Tg polymer is present in an amount ranging from about 10 to 30 percent by weight based on a total weight of the pressure sensitive adhesive component and the high Tg polymer.
4. The adhesive composition of claim 3 comprising an activatable crosslinker, said activatable crosslinker being capable of being activated by heat or light and being selected from the group consisting of multifunctional aziridine, benzophenones, triazines, monoethylenically unsaturated mono-, di-, and trialkoxy silane compounds, diacrylates, triacrylates, and tetraacrylates, isocyanates, epoxies, and mixtures thereof.
5. The adhesive composition of claim 4 comprising a multifunctional aziridine crosslinker.
6. The adhesive composition of claim 5 wherein the multifunctional aziridine crosslinker comprises 1,1′-(1,3-phenylene dicarboxyl)-bis-(2-methylaziridine).
7. The adhesive composition of claim 6 wherein the pressure sensitive adhesive component comprises a copolymer with an weight average molecular weight less than 800,000.
8. The adhesive composition of claim 1 wherein the adhesive composition is a pressure sensitive adhesive.
9. An article comprising the adhesive composition of claim 1 coated on at least one surface of a substrate.
10. The article of claim 9 wherein the substrate is selected from the group consisting of a release liner, a film, and a rigid material.
11. A multi-layer assembly comprising the adhesive composition of claim 1 ;
wherein the adhesive composition is optically clear, and wherein the adhesive composition bonds at least two layers together comprising a low moisture vapor transfer layer and an outgassing layer, said outgassing layer comprising a material selected from the group consisting of a polycarbonate and a poly(methyl methacrylate), and said low moisture vapor transfer layer being selected from the group consisting of a metallized polymeric film, an infrared reflecting film, a multilayer optical film, and a polymeric film layer coated with a conductive layer, and
wherein after aging at 80° C. and 90% relative humidity for 500 hours, the bond between the outgassing layer and the low moisture vapor transfer layer does not delaminate or bubble, and the composition remains optically clear so that the composition exhibits a luminous transmission of at least about 90% and a haze of less than about 2% when measured according to ASTM-D 1003-95.
12. The multilayer assembly of claim 11 wherein the assembly comprises a conductive optical element comprising a rigid polycarbonate layer adhered with the adhesive to a surface of a polymeric film layer, an opposite surface of the polymeric film layer being coated with a conductive layer.
13. The multi-layer assembly of claim 11 comprising an activatable crosslinker, said activatable crosslinker being capable of being activated by heat or light and being selected from the group consisting of multifunctional aziridine, benzophenones, triazines, monoethylenically unsaturated mono-, di-, and trialkoxy silane compounds, diacrylates, triacrylates, and tetraacrylates, isocyanates, epoxies, and mixtures thereof.
14. The adhesive composition of claim 1 wherein the pressure sensitive adhesive component is present in an amount ranging from about 70 to 90 percent by weight, and the high Tg polymer is present in an amount ranging from about 10 to 30 percent by weight based on a total weight of the pressure sensitive adhesive component and the high Tg polymer.
15. The adhesive composition of claim 14 wherein the pressure sensitive adhesive component is formed from (i) isooctyl acrylate monomer and acrylic acid monomer.
16. The adhesive composition of claim 15 wherein the crosslinker comprises 1,1′-(1,3-phenylene dicarboxyl)-bis-(2-methylaziridine).
17. The adhesive composition of claim 14 wherein the pressure sensitive adhesive component comprises a copolymer with an weight average molecular weight less than 800,000.
18. The adhesive composition of claim 17 wherein the pressure sensitive adhesive component comprises a copolymer with an weight average molecular weight less than 600,000.