Heat treated profile extruded hook
First Claim
1. A method of forming a unitary fastener comprising the steps ofextruding a thermoplastic resin in a machine direction through a die plate having a continuous base portion cavity and one or more ridge cavities extending from the base portion cavity, the extrusion being sufficient to induce melt flow molecular orientation in the polymer flowing through at least the ridge cavities forming a base portion with ridges,forming projections from the thermoplastic resin extruded through the ridge cavities, andsubsequently heat treating at least a portion of the solidified projections at a temperature, near or above the thermoplastic resin melt temperature, and time sufficient to reduce the thickness of at least an upper portion of the projections by from 5 to 90 percent.
1 Assignment
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Accused Products
Abstract
A method for forming a unitary polymeric projection or fastener comprising a thin, strong flexible backing, and a multiplicity of thin spaced hook members projecting from the upper surface of the unitary backing the method generally including extruding a thermoplastic resin through a die plate which die plate is shaped to form a base layer and spaced ridges, ribs or hook elements projecting above a surface of the base layer. When the die forms the spaced ridges or ribs the cross sectional shape of the hook members are formed by the die plate while the initial hook member thickness is formed by transversely cutting the ridges at spaced locations along their lengths to form discrete cut portions of the ridges. Subsequently longitudinal stretching of the backing layer (in the direction of the ridges on the machine direction) separates these cut portions of the ridges, which cut portion then form spaced apart hook members. The extruded hook members or cut rib hook members are then heat treated resulting in shrinkage of at least a portion of at least the hook head portion thickness by from 5 to 90 percent, preferably 30 to 90 percent.
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Citations
11 Claims
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1. A method of forming a unitary fastener comprising the steps of
extruding a thermoplastic resin in a machine direction through a die plate having a continuous base portion cavity and one or more ridge cavities extending from the base portion cavity, the extrusion being sufficient to induce melt flow molecular orientation in the polymer flowing through at least the ridge cavities forming a base portion with ridges, forming projections from the thermoplastic resin extruded through the ridge cavities, and subsequently heat treating at least a portion of the solidified projections at a temperature, near or above the thermoplastic resin melt temperature, and time sufficient to reduce the thickness of at least an upper portion of the projections by from 5 to 90 percent.
Specification