Patent ID: 7059760

Claim:
A method of post-mixing a pigment or dye with a hot melt adhesive, comprising the steps of: providing a source of molten hot melt adhesive; providing a first pigment or dye in solution or liquid dispersion for said hot melt adhesive; providing a flushing agent compatible with said hot melt adhesive; feeding said molten hot melt adhesive from the hot melt adhesive source to a mixer at a flow rate; simultaneously feeding the pigment or dye for said hot melt adhesive to said mixer such that the first pigment or dye is introduced downstream of the source of molten hot melt adhesive; mixing the first pigment or dye and the molten hot melt adhesive in said mixer to form a homogenous mixture; recovering said homogeneous mixture; and subsequently flushing said mixer prior to feeding and mixing another pigment or dye in said mixer; wherein the step of flushing said mixer comprises preventing the first pigment or dye from being fed to said mixer and feeding the flushing agent to said mixer for a sufficient amount of time to substantially completely purge said mixer of the first pigment or dye.