Toothbrush

Abstract

A toothbrush made partly of a hard plastic material and partly of an elastomeric material, characterized in that at least part of the elastomeric material comprises an inner core ( 23 ) of a first soft elastomeric material wholly or partly enclosed within an outer flexible skin ( 24 ) of a second polymer material having different physical characteristics to the inner core polymer. Processes for making such a toothbrush are also described.

1 - 47 . (Cancelled)  
   
   
       48 . A toothbrush comprising a handle, a head on which are mounted bristles, with optionally a neck region between the head and handle, the toothbrush being made partly of a hard plastic material and having at least one part made of an elastomeric material, wherein; 
 at least part of the at least one elastomeric material part comprises an inner core of an elastomeric material wholly or partly enclosed within an outer flexible skin of the same elastomeric material comprising the same monomer units as the core but having different physical characteristics to the inner core material.    
   
   
       49 . A toothbrush according to  claim 48  wherein the core comprises a foamed elastomeric material and the skin comprises the same elastomeric material in a non-foamed state.  
   
   
       50 . A toothbrush according to  claim 48  wherein the core comprises a foamed elastomeric material and the skin comprises the same elastomeric material in a foamed state having different void characteristics to the inner core material.  
   
   
       51 . A toothbrush according to  claim 50  wherein the skin comprises the same elastomeric material in a foamed state having a lower number of gas bubbles per unit volume than the core.  
   
   
       52 . A toothbrush according to  claim 48  wherein the elastomeric material of the core comprises a foamed elastomeric material having a hardness of Shore A 5 to 30, and the outer skin comprises a non foamed elastomeric material or an elastomeric material less foamed than the material of the core having a hardness of Shore A 65±5, the thickness of the outer skin being in the range 100 microns-1.5 mm.  
   
   
       53 . A toothbrush according to  claim 52  wherein the elastomer part of the toothbrush has a thickness of 3 mm-1.5 cm.  
   
   
       54 . A toothbrush according to  claim 48  wherein the elastomeric material of the core and skin is selected from the group of compounds based on styrenic block copolymers such as styrene-ethylene-butadiene-styrene (SEBS) copolymers, polyblends based on EPDM/PP, polyacrylate/PP blends, thermoplastic polyurethanes, thermoplastic copolyesters, natural or synthetic latex type elastomers, polychloroprenes, natural rubber and polyurethane foams.  
   
   
       55 . A toothbrush according to  claim 48  when made by a process in which: 
 a hard plastic part of the toothbrush is made in a first stage by a process of injection moulding in the form of a skeleton of the hard plastic material having one or more cavity therein corresponding to the intended position(s) and dimensions of the elastomeric material part(s), then;    this skeleton is enclosed in a mould having at least one cavity therein corresponding to the intended position of an elastomer part, then    the skin material is injected into the cavity, then    the core material is injected into the cavity to form the core and to fill and inflate the skin.    
   
   
       56 . A toothbrush according to  claim 55  wherein the skin material is injected into the mould cavity in an amount comprising 20-30% of the total cavity volume then 
 the core material is injected into the cavity to form the core and to fill and inflate the skin.    
   
   
       57 . A toothbrush according to  claim 55  wherein the core comprises an elastomer material which includes a foaming agent and the quantity of such core material injected into the cavity is such that the combined volume of skin and core materials fills ca. 50-70% of the cavity and the expansion of the core material as foaming occurs then causes sufficient expansion that the core and skin materials fill the cavity.  
   
   
       58 . A toothbrush according to  claim 48  when made in a process in which: 
 a hard plastic part of the toothbrush is made in a first stage by a process of injection moulding in the form of a skeleton of the hard plastic material having one or more cavity therein corresponding to the intended position(s) and dimensions of the elastomeric material part(s), then;    this skeleton is enclosed in a mould having at least one cavity therein, bounded by a wall, corresponding to the intended position of an elastomer part, then    an elastomer material having incorporated therein a foaming agent is injected into the mould and outer parts of the elastomer material injected into the mould are arranged to cool more rapidly so as to foam less to result in an outer skin in a non foamed state or in a less foamed state than the inner core parts of the material further away from the walls of the mould cavity.