Method and apparatus for injection molding a plastic monolith

Abstract

A brush is injection molded in a multipart mold. The bristles of the brush are sequentially molded integrally with the base or handle. The bristles are extremely small and are injection molded in a unique molds. The bristle portion of the mold consists of a series a plates or semi-sphere cups, each of which is drilled with a diminutive drill bit. The plates and cups are then assembled so that the bores of the plates and cups are aligned to form the bristle containing portion of the mold. The mold portion for the bristles is injection molded with a first resin material. Then base or handle producing portion of the mold is injected with a second resin material. The selection of applicable resins, seize of bristles, spacing of bristles, viscosity of the to-be-dispensed fluid all considered in the defining of the amount of liquid to be carried and dispensed by the brush.

What is claimed is:  
     
         1 . A brush which has a first resin handle portion and an integral second resin bristle portion which has been sequentionally injection model in a multi-part mold, said mold having a cavity bristle molding portion, said cavity having a plurality of bristle defining elongated recess said recesses resulting from mechanical drilling a series of plates with progressively smaller bores whereby when said plates are assembled and aligned, said bores are in alignment resulting in said recesses being tapered, said resultant injected molded brush comprises bristles which are approximately 0.009 inches in diameter at a base portion and approximately 0.004 inches diameter at their distal end.  
     
     
         2 . The brush according to  claim 1  wherein the resulting bristles are between 0.050 to 0.500 in length.  
     
     
         3 . The brush according to  claim 1  wherein the first resin is selected from the group consisting of polypropylene, polyethylene, santopreme and polyvinylchloride.  
     
     
         4 . The brush according to  claim 1  wherein the second resin is selected from the group consisting of styrene, polycarbonate, acetyl and polyvinylchloride.  
     
     
         5 . The brush according to  claim 1  wherein the resulting bristles at the confluence of said handle portion are spaced from one another.  
     
     
         6 . The brush according to  claim 1  wherein the said plates have a thickness of approximately 0.05 inches.