Stiffeners for use in footwear
The present invention relates to a process and composition for stiffening materials for use in the manufacturing of footwear using a combination of stiffeners and adhesives.
1. A resilient footwear stiffener for retaining a shape of a heel or toe portion of footwear, the stiffener comprising a polyethylene terephthalate glycol copolyester layer and at least one low melting point plastic adhesive resin layer coextruded on at least one side of the polyethylene terephthalate glycol copolyester layer so that said low melting point plastic adhesive resin is not fully dissolved in the polyethylene terephthalate glycol copolyester, wherein said low melting point plastic adhesive resin has a melting point below 85° C. and wherein said low melting point plastic adhesive resin layer or layers is no more than 20% of the total thickness of the coextruded sheet.
2. The resilient footwear stiffener of claim 1 , wherein the low melting point plastic adhesive resin is a polycaprolactone resin.
3. The resilient footwear stiffener of claim 2 , wherein the ratio of polyethylene terephthalate glycol copolyester/polycaprolactone is from about 70/30 to about 95/5.
4. The resilient footwear stiffener of claim 1 , wherein low melting point plastic resin and said polyethylene terephthalate glycol copolyester are coextruded through either a coextrusion block or a manifold sheeting die.
5. A resilient footwear stiffener for retaining a shape of a heel or toe portion of footwear, the stiffener comprising a polyethylene terephthalate glycol copolyester layer coextruded with an outer component comprising a low melting point plastic adhesive resin layer on two sides of the polyethylene terephthalate glycol copolyester layer; wherein said low melting point plastic adhesive resin of the outer component is not fully dissolved in the polyethylene terephthalate glycol copolyester layer, wherein said low melting point plastic adhesive resin has a melting point below 85° C. and wherein said low melting point plastic adhesive resin layers are no more than 20% of the total thickness of the coextruded sheet.
6. The resilient footwear stiffener of claim 5 , wherein the low melting point adhesive resin is a polycaprolactone resin.
7. The resilient footwear stiffener of claim 6 , wherein the ratio of polyethylene terephthalate glycol copolyester/polycaprolactone is from about 70/30 to about 95/5.
8. The resilient footwear stiffener of claim 5 , wherein low melting point plastic resin and said polyethylene terephthalate glycol copolyester are coextruded through either a coextrusion block or a manifold sheeting die.
9. The resilient footwear stiffener of claim 5 , wherein the stiffener is a heel counter and further comprises a layer of lining material adhered to a first of the layers of low melting point plastic adhesive resin and a second layer adhered to a second of the layers of the low melting point plastic adhesive, wherein the second layer is leather.
10. The resilient footwear stiffener of claim 9 wherein the stiffener is molded into a desired shape for the heel counter.