| 摘要 |
Two major components of the brush (1) comprise differing plastics which do not bond during pressure injection molding. They are held together by friction and/or interlocking. An Independent claim is included for the method of making the toothbrush. In a first stage, a first molding is made from one plastic. Then in a second stage the other molding is injected, using a second plastic which does not bond to the first during the injection operation. Preferred features: One part holds the bristles (3), the other (2) forms a handle. Interlocking, firm connection is enhanced by a form of shrink-fitting. Inter-engaging parts interlock together. Projections and recesses interlock. The plastics have differing shrinkage. Moldings may comprise two or more plastic components not bonding with each other. In the method, the first injection is made with plastic of lower shrinkage. In a specific implementation the first injection employs styrene acrylonitrile, the second, polypropylene. |
