Two stage methods for processing adhesives and related compositions
Methods for forming melt processable, actinic radiation polymerizable and crosslinkable adhesives are described. In certain versions, the adhesives or pre-adhesive compositions include two initiators and are polymerized and/or crosslinked by exposure to actinic radiation such as UV light or electron beam radiation. Also described are pre-adhesive compositions including polymerizable monomers, articles including the adhesives, and various methods and systems related to the adhesives and their application. In addition, various apparatuses are described for polymerizing or crosslinking the compositions.
1. A composition comprising:
at least one monomer comprising one or more ethylenically unsaturated bonds;
a first actinic radiation initiator, the first initiator being activated at a first activation wavelength(s);
a second actinic radiation initiator, the second initiator being activated at a second activation wavelength(s); and
the second initiator being substantially non-photoactive at the first activation wavelength(s),
wherein at least one of the first and second initiators is a polymerizable monomer containing a photoinitiator moiety, and
wherein upon activation of the first initiator the at least one monomer polymerizes to form a pre-adhesive.
2. The composition of claim 1 wherein the first initiator is activated by exposure to UV radiation.
3. The composition of claim 1 wherein the first initiator is activated by exposure to electron beam radiation.
4. The composition of claim 1 wherein the second initiator is activated by exposure to UV radiation.
5. The composition of claim 1 wherein the second initiator is activated by exposure to electron beam radiation.
6. The composition of claim 1 wherein the pre-adhesive exhibits a viscosity within a range of from 1,000 cps to 80,000 cps at a temperature within a range of from 110° C. to 180° C.
7. The composition of claim 6 wherein the pre-adhesive exhibits a viscosity within a range of from 30,000 cps to 40,000 cps at a temperature within a range of from 120° C. to 140° C.
8. The composition of claim 6 wherein the pre-adhesive exhibits a viscosity within a range of from 40,000 cps to 50,000 cps at a temperature within a range of from 120° C. to 140° C.
9. The composition of claim 6 wherein the pre-adhesive exhibits a viscosity within a range of from 1,000 cps to 15,000 cps at a temperature within a range of from 110° C. to 130° C.
10. The composition of claim 1 wherein the at least one monomer is an acrylate monomer.
11. The composition of claim 1 further comprising at least one component selected from the group consisting of pigments, toddlers, plasticizers, fillers, diluents, inhibitors, and combinations thereof.
12. An article comprising the composition of claim 1 .
13. The composition of claim 1 wherein the first initiator is a polymerizable actinic radiation initiator.
14. The composition of claim 1 wherein the second initiator is a polymerizable actinic radiation initiator.
15. The composition of claim 1 wherein the second initiator is a crosslinkable actinic radiation initiator.
16. The composition of claim 1 wherein the composition is free of solvents.
17. The composition of claim 1 wherein at least one of the first and second initiators is an activatable photoinitiator moiety covalently bound to the pre-adhesive polymer backbone.
18. The composition of claim 1 wherein the first initiator is an activatable photoinitiator moiety covalently bound to the pre-adhesive polymer backbone.
19. The composition of claim 1 wherein the second initiator is an activatable photoinitiator moiety covalently bound to the pre-adhesive polymer backbone.
20. The composition of claim 1 wherein the first initiator is selected from the group consisting of acyl phosphine oxides, derivatives of acyl phosphines, thioxanthone, derivatives of thioxanthone, camphorquinone, derivatives of camphorquinone, and combinations thereof.
21. The composition of claim 1 wherein the pre-adhesive comprises at least one acrylate polymer.
22. The composition of claim 21 wherein the acrylate polymer is fully polymerized.
23. A composition comprising:
at least one monomer comprising one or more ethylenically unsaturated bonds;
a first actinic radiation initiator, the first initiator being activated at a first activation wavelength(s);
a second actinic radiation initiator, the second initiator being activated at a second activation wavelength(s); and
the second initiator being substantially non-photoactive at the first activation wavelength(s),
wherein at least one of the first and second initiators is polymerizable with the at least one monomer, and
wherein at least one of the first and second initiators is a polymerizable monomer comprising a photoinitiator moiety.
24. The composition of claim 1 wherein upon activation of the first initiator the at least one monomer polymerizes to form a pre-adhesive polymer comprising the second initiator bound to the pre-adhesive polymer backbone.
25. The composition of claim 24 wherein the second initiator bound to the pre-adhesive polymer backbone is activatable at the second activation wavelength(s).
26. The composition of claim 1 wherein the first initiator is a polymerizable monomer comprising a photoinitiator moiety.
27. The composition of claim 1 wherein the second initiator is a polymerizable monomer comprising a photoinitiator moiety.
28. The composition of claim 1 wherein both the first and second initiators are polymerizable monomers comprising a photoinitiator moiety.
29. The composition of claim 1 wherein upon activation of the second initiator the composition crosslinks to form a pressure sensitive adhesive.
30. The composition of claim 1 wherein the monomer comprising one or more ethylenically unsaturated bonds is a (meth)acrylate monomer.
31. The composition of claim 1 wherein the second initiator is a polymerizable monomer comprising acrylate and/or methacrylate monomers.
32. A composition comprising:
at least one monomer comprising one or more ethylenically unsaturated bonds;
a first actinic radiation initiator, the first initiator being activated at a first activation wavelength(s);
a second actinic radiation initiator, the second initiator being activated at a second activation wavelength(s); and
the second initiator being substantially non-photoactive at the first activation wavelength(s),
wherein at least one of the first and second initiators is a polymerizable monomer comprising a photoinitiator moiety,
wherein upon activation of the first initiator the at least one monomer polymerizes to form a pre-adhesive, and
wherein the second initiator is an activatable photoinitiator moiety covalently bound to the pre-adhesive polymer backbone.