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Packaging Method for Hot Melt Adhesive I


Hot melt adhesive flim which are generally applied while in the molten or liquid state are solid at room temperature. Typically, these adhesives are provided in the form of blocks and because of the nature of these materials, particularly the pressure sensitive hot melts, there are problems associated with handling and packaging them. The solid adhesive blocks not only stick or adhere to hands or mechanical handling devices and to each other, but they also pick up dirt and other contaminants. As a result, the need and advantages for providing tackless or non-blocking hot melt adhesives are apparent and various ways of accomplishing this have been developed.

In order to overcome the disadvantages inherent in the methods of the prior art, applicants have found that when the hot melt adhesive is poured in its molten state into a mold or cavity lined with plastic packaging film and then allowed to solidify, the adhesive is fused to some extent into the film, resulting in a non-blocking adhesive package which will melt faster in the melt pot and will not cause a build up of undesirable plastic residue even after extended periods of time.

Thus, the intermolecular transfer of one or more of the hot melt components into the contact surface of the plastic film allows some mixing or compatibilizing of the film and the net merit thereby improving the opportunity for more complete mixing of the hot melt and film when remelting of the packaged hotmelt occurs.

The method provides an additional benefit over prior non-blocking packages in that the package itself is air-tight allowing no air to be entrapped therein. The presence of entrapped air in prior packages has been blamed for a variety of problems including incomplete melting and blending of the packaging material into the adhesive whereby the packaging material floats on the surface of the hot melt and/or adheres to the walls of the melt pot.

Since the melting point of the plastic film must be comparable to, and preferably lower than, the melting point of the hot melt adhesive, in order to provide for satisfactory melting in the melt pot which does not have a source of agitation, it is necessary that the lined mold be a heat sink or be in contact with a heat sink so as to remove excess heat from the film as quickly as possible and thereby prevent melting, burning or charring of the plastic film wrap.

Thus, the present invention is directed to a method for packaging hot melt adhesives comprising the steps of:

1. Lining a mold with a plastic film, the film should be meltable together with the adhesive composition and blendable into molten adhesive composition, and the mold should in contact with a heat sink.