Ultraviolet radiation curable pressure sensitive acrylic adhesive
View Patent ↗A process for making UV curable pressure sensitive adhesive compositions by derivatizing an acrylic polymer with a derivatizing agent prepared from a hydroxy-functional acrylate monomer and a diisocyanate. The derivatizing agent typically has a ratio of hydroxy-functional acrylate monomer to diisocyanate greater than about 1:1. Also disclosed are UV curable pressure sensitive adhesives made with the derivatizing agent and methods for adhering substrates with pressure sensitive adhesive compositions.
1. An ultraviolet (“UV”) curable pressure sensitive adhesive composition made by a process comprising the step of derivatizing an acrylic polymer with about 2% to about 9% by weight solids of a derivatizing agent prepared from a hydroxy-functional acrylate monomer and a diisocyanate selected from the group consisting of isophorone diisocyanate, toluene diisocyanate and combinations thereof wherein the derivatizing agent has a ratio of hydroxy-functional acrylate monomer to diisocyanate of about 1.05:1 to about 1.5:1.
2. The UV curable pressure sensitive adhesive composition of claim 1 wherein the ratio is about 1.1:1 to about 1.2:1.
3. The UV curable pressure sensitive adhesive composition of claim 1 wherein the acrylic polymer has a molecular weight of about 40,000 to about 100,000.
4. The UV curable pressure sensitive adhesive composition of claim 1 wherein the hydroxy-functional acrylate monomer is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, caprolactone acrylate, hydroxyl acrylate and combinations thereof.
5. The UV curable pressure sensitive adhesive composition of claim 1 wherein the acrylic polymer comprises at least one backbone hydroxy-functional monomer.
6. The UV curable pressure sensitive adhesive composition of claim 5 wherein the backbone hydroxy-functional monomer is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate and combinations thereof.
7. An ultraviolet (“UV”) curable pressure sensitive adhesive composition comprising a photoinitiator and a derivatized polymer wherein the derivatized polymer comprises an acrylic polymer reacted with about 2% to about 9% by weight solids of a derivatizing agent prepared from a hydroxy-functional acrylate monomer and a diisocyanate from the group consisting of isophorone diisocyanate, toluene diisocyanate and combinations thereof and the derivatizing agent has a ratio of the hydroxy-functional acrylate monomer to diisocyanate of about 1.05:1 to about 1.5:1.
8. The UV curable pressure sensitive adhesive composition of claim 7 further comprising a component selected from the group consisting of an inhibitor, a tackifier, a crosslinking agent, a stabilizer, a filler, a solvent, a plasticizer and combinations thereof.
9. The UV curable pressure sensitive adhesive composition of claim 7 wherein the ratio is about 1.1:1 to about 1.2:1.
10. The UV curable pressure sensitive adhesive composition of claim 7 wherein the acrylic polymer has a molecular weight of about 40,000 to about 100,000.
11. The UV curable pressure sensitive adhesive composition of claim 7 wherein the acrylic polymer comprises a monomer selected from the group consisting of 2-ethylhexyl acrylate, iso-octyl acrylate, iso-decyl acrylate, lauryl acrylate, n-butyl acrylate and combinations thereof.
12. The UV curable pressure sensitive adhesive composition of claim 7 wherein the acrylic polymer comprises a monomer selected from the group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate, styrene, vinyl acetate and combinations thereof.
13. The UV curable pressure sensitive adhesive composition of claim 7 wherein the acrylic polymer comprises at least one backbone hydroxy-functional monomer.
14. The UV curable pressure sensitive adhesive composition of claim 13 wherein the backbone hydroxy-functional monomer is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate and combinations thereof.
15. The UV curable pressure sensitive adhesive composition of claim 7 wherein the acrylic polymer comprises a functional monomer selected from the group consisting of acrylic acid, methacrylic acid, maleic anhydride, glycidyl methacrylate, N-vinyl pyrrolidone, N-vinyl caprolactam, acrylamide and combinations thereof.
16. The UV curable pressure sensitive adhesive composition of claim 7 wherein the hydroxy-functional acrylate monomer is selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, caprolactone acrylate, hydroxyl acrylate and combinations thereof.
17. A method for the application of the UV curable pressure sensitive adhesive of claim 7 to one or more substrates comprising the steps of:
a. providing at least a first substrate and a second substrate each having one or more surfaces;
b. providing the pressure sensitive adhesive of claim 7 ;
c. applying the pressure sensitive adhesive to a surface of the first substrate;
d. UV curing the pressure sensitive adhesive; and
e. mating the surface of the first substrate having the pressure adhesive with a surface of the second substrate to adhere the first substrate and the second substrate.
18. The method of claim 17 wherein the pressure sensitive adhesive is applied at a thickness greater than or equal to about 2 mils.
19. Two or more substrates adhered together by the method of claim 17 .
20. A two sided transfer tape comprising a release liner wherein the release liner is coated with a material that comprises the pressure sensitive adhesive composition of claim 7 which has been cured.