Method For Forming Bilayer Patches

Abstract

A method for injection molding thin materials (sub-millimeter) having low green strength could make certain manufacturing processes significantly more efficient yet has heretofore been unavailable. Provided herein is a method that enables injection molding of thin materials by using a mold with contact surfaces having a low surface energy release agent disposed thereon. The low surface energy release agent may be applied as a coating on a conventional mold or the mold itself or just the contact surfaces thereof may be formed of a low surface energy release material. The method finds particular applicability in making special contour patches for medical and cosmetic implants and prosthetics. A preferred approach involves injection molding a thin layer of unvulcanized material on a cold mold, injection molding a thin layer of vulcanized material on a hot mold, transferring the vulcanized layer to the unvulcanized layer on the cold mold, and removing the combined layers.

What is claimed is: 
     
         1 . A method of forming a patch, comprising:
 injection molding a vulcanized polymer layer using a first mold plate;   injection molding a unvulcanized polymer layer using a second mold plate;   removing the vulcanized polymer layer from the first mold plate;   disposing the vulcanized polymer layer onto the unvulcanized layer while the unvulcanized layer is still on the second mold plate.   compressing the vulcanized polymer layer and the unvulcanized polymer layer until the vulcanized polymer layer adheres to the unvulcanized layer to form a patch; and   removing the patch from the second mold plate.   
     
     
         2 . The method of  claim 1 , wherein the second mold plate has a contact surface upon which the unvulcanized polymer layer is formed that is formed from a low surface energy material. 
     
     
         3 . The method of  claim 2 , wherein the low surface energy material is selected from the group consisting of polytetrafluoroethylene, and polyvinylidene fluoride. 
     
     
         4 . The method of  claim 1 , wherein the second mold plate has a contact surface upon which the unvulcanized polymer layer is formed, the contact surface formed from a release agent bonded to the second mold plate. 
     
     
         5 . The method of  claim 4 , wherein the release agent is a low surface energy material. 
     
     
         6 . The method of  claim 5 , wherein the release agent is a fluorinated polymer. 
     
     
         7 . The method of  claim 5 , wherein the release agent is selected from the group consisting of polyvinylidene fluoride, polyvinylidene chloride, and polyp-xylylene). 
     
     
         8 . The method of  claim 1 , further comprising applying a release coating to a contact surface of the second mold plate upon which the unvulcanized polymer layer is formed. 
     
     
         9 . The method of  claim 8 , wherein the release coating is a fluorinated polymer. 
     
     
         10 . The method of  claim 8 , wherein the release agent is selected from the group consisting of polyvinylidene fluoride, polyvinylidene chloride, and poly(p-xylylene). 
     
     
         11 . A patch formed by the process of  claim 1 . 
     
     
         12 . A method of forming a layered patch, comprising:
 injection molding an unvulcanized layer by molding the unvulcanized layer against a first mold having a low surface energy contact surface;   forming a vulcanized layer;   applying the vulcanized layer over the unvulcanized layer while the unvulcanized layer is still on the first mold;   adhering the vulcanized layer to the unvulcanized layer;   removing the adhered vulcanized and unvulcanized layers from the first mold; and   cutting the adhered vulcanized and unvulcanized layers into a desired shape for a patch.   
     
     
         13 . The method of  claim 12 , wherein forming the vulcanized layer includes injection molding. 
     
     
         14 . The method of  claim 12 , wherein forming the vulcanized layer includes calendering. 
     
     
         15 . The method of  claim 13 , wherein forming the vulcanized layer includes hot injections molding to cure and vulcanize the vulcanized layer. 
     
     
         16 . The method of  claim 12 , wherein injection molding the unvulcanized layer includes using a cold injection molding process. 
     
     
         17 . The method of  claim 12 , wherein injection molding the unvulcanized layer includes using a cold mold. 
     
     
         18 . The method of  claim 12 , wherein the low energy surface of the mold is created by coating a surface of the mold with low surface energy material. 
     
     
         19 . The method of  claim 12 , wherein the low energy surface of the mold is created by bonding a release agent to a surface of the mold. 
     
     
         20 . The method of  claim 12 , wherein the mold having a low energy surface is formed from a material having a low surface energy. 
     
     
         21 . The method of  claim 18 , wherein the low surface energy material is a fluorinated polymer. 
     
     
         22 . The method of  claim 21 , wherein the low surface energy material is polyvinylidene fluoride. 
     
     
         23 . The method of  claim 21 , wherein the low surface energy material is polyvinylidene chloride. 
     
     
         24 . The method of  claim 21 , wherein the low surface energy material is poly(p-xylylene). 
     
     
         25 . The method of  claim 21 , wherein the low surface energy material is polytetrafluoroethylene. 
     
     
         26 . The method of  claim 12 , wherein forming the vulcanized layer includes solvent casting. 
     
     
         27 . The product formed using the process of  claim 12 . 
     
     
         28 . The method of  claim 12 , wherein injection molding the unvulcanized layer includes molding a contour into the unvulcanized layer. 
     
     
         29 . The method of  claim 12 , wherein injection molding the unvulcanized layer includes molding forming means for providing an insertion point in the patch for filling an implantable silicone breast prosthesis with fluid. 
     
     
         30 . The method of  claim 29 , wherein the fluid is a silicone gel. 
     
     
         31 . An implantable silicone breast prosthesis manufactured using the process of  claim 12 .