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. An apparatus for polymerizing and/or crosslinking an adhesive or pre-adhesive composition, the apparatus comprising:
a reaction vessel defining an interior chamber and at least one sight glass incorporated in a wall of the vessel and providing visual access to the interior chamber;
at least one probe assembly adjacent the sight glass, the probe assembly comprising
(i) an emitter for emitting light that polymerizes and/or crosslinks the composition and,
(ii) a light tube disposed between the sight glass and the emitter, wherein the probe assembly is engaged with the sight glass by the light tube;
the probe assembly positioned such that light emitted from the emitter is directed to the sight glass and passes into the interior chamber of the reaction vessel;
wherein the sight glass is transparent or substantially transparent to passage of light emitted from the emitter.
2. The apparatus of claim 1 wherein the sight glass is located along a side wall of the reaction vessel.
3. The apparatus of claim 1 wherein the vessel further comprises mixing provisions.
4. The apparatus of claim 1 wherein an interior wall of the light tube provides a smooth, polished surface that promotes reflection of light emitted from the emitter.
5. The apparatus of claim 1 wherein the at least one sight glass is flush or substantially flush with an inside/interior wall of the reaction vessel.
6. The apparatus of claim 1 wherein the at least one sight glass is below an upper surface of the composition contained within the reaction vessel.
7. The apparatus of claim 3 wherein the mixing provisions comprise one or more blades or mixing elements extending from a shaft that extends into the interior chamber of the reaction vessel.
8. The apparatus of claim 3 wherein the mixing provisions comprise a blade that sweeps an inside wall of the reaction vessel.
9. The apparatus of claim 1 further comprises a heating and/or cooling jacket along an exterior region of the reaction vessel.