Forming an integral closure for a thermoplastic container
AssigneeThe Dow Chemical Company
InventorsThomas A. Sutrina, R. Douglas Behr
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Abstract
An improved high speed cast process for fusing fasteners, with strips of film at their base, to separately extruded film or sheet stock for making containers with integral closure means. The process makes available multiple sets of male and female fastener elements, with variable spacing, in a single extrusion operation. The apparatus is configured so that adhesion between the fastener elements and the film or sheet occurs very closely to the die lips before significant cooling of the extrudate occurs. Containers with improved profiles are obtained because the base permits the profiles to remain relatively rigid during closing and opening.
Claims8
An apparatus for forming an integral thermoplastic fastening means on a cast film or sheet, said apparatus comprising an extrusion die having an extrusion channel ending in extrusion die lips, said die lips presenting a surface defining a plane, a side of said die presenting a face angularly disposed towards said extrusion channel and die lips, an extrusion die block located adjacent said face, a die plate secured to the die block, said die plate having a leading edge, said leading edge located out of the plane of the die lips, said die block having an extrusion channel disposed angularly adjacent the exit of said die block so as to increase the acuteness of the angularity of the extrudate issuing from the die plate with respect to the extrudate issuing from said die lips, and cooling means located below said extrusion die and die plate.
Dependencies are inferred from the claim text.