Patent Publication Number: US-2009217472-A1

Title: Toothbrush

Description:
This invention-relates to toothbrushes. 
     Toothbrushes are well known devices, generally comprising an elongate grip handle with at one end a head bearing oral cleaning elements such as bristles to clean such oral surfaces as the teeth and gums. Generally the handle and head of toothbrushes are made of plastics materials by a process of injection moulding. There is an ongoing problem of the need to reduce manufacturing costs, and one solution to this problem is to reduce material costs. Also, if the toothbrush handle is relatively bulky increased time needs to be allowed in the injection moulding process for the handle to cool. One solution to this problem is suggested in US-A-2003/0208870 which discloses a toothbrush in which the handle includes one or plural voids to reduce the amount of plastics material that is needed and to reduce the cooling time. In US-A-2003/0208870 the voids are shown as open on the surface of the toothbrush. 
     It is an object of the present invention to provide a further, improved, solution to these problems. 
     According to this invention a toothbrush grip handle made of a plastics material is provided, connected or connectable to a toothbrush head bearing oral cleaning elements, characterised by the handle including one or plural voids having an opening at the surface of the handle, and said void(s) being at least partly closed by a film material. 
     The toothbrush grip handle of the invention addresses the problem outlined above in that the void(s) reduce the amount of plastics material needed relative to a toothbrush handle of the same overall size. However by closing the void with a film material the entry of water, contaminants etc. into the void, which could result in mould etc. growth is thereby reduced. In the case of children&#39;s toothbrushes an additional problem is also thereby solved. Small children tend to chew the handle of their toothbrushes and if voids are open on the surface of the handle their teeth may become caught in open voids, with the possible consequence of injury to their teeth and adjacent gum tissues. By closing the voids this danger is reduced or eliminated. 
     The invention further provides a toothbrush comprising a grip handle as defined above, combined with a toothbrush head, suitably integrally made with the toothbrush head. 
     Suitably the handle and head and any neck region between the head and handle are integrally made in one piece of the plastics material, as is common in the art. 
     Suitably the oral cleaning elements are bristles, as is common in the art, and plural bristles may be made into tufts which may be fixed into the head in a conventional manner. 
     Suitably each void may comprise a cell partly bounded by walls of the plastics material of which the handle is made, and partly bounded, being at least partly closed, by the film material. Such cells may for example be substantially tetragonal, although other shapes e.g. hexagonal prismatic are also suitable. Suitably there may be plural voids in the handle. Plural voids may be arranged serially along the longitudinal direction of an elongate toothbrush grip handle. Plural voids may be in communication with each other, or may be separated from each other by bulkhead walls e.g. of the plastics material of which the handle is made. Typically a toothbrush grip handle comprises an end longitudinally distant from the head, and an end longitudinally closer to the head, and side surfaces running longitudinally between these ends. Suitably the voids are open at one or more of these side surfaces. Such bulkhead walls may extend across the grip handle perpendicular to the head-handle direction. When plural voids are in communication this may be achieved by openings in bulkhead walls between voids or bulkhead walls which only partially close the voids. 
     Typically the walls of the cells that define the outer surface of the grip handle may be 1-2 mm thick. Typically bulkhead walls between cells may also be 1-2 mm thick. 
     Suitably the void(s) may make up 30% or more, e.g. 40% or more, e.g. 50%, e.g. 60% or more of the internal volume of the grip handle of the toothbrush. 
     Plural voids may all be open on the same surface of the grip handle. The openings of plural voids may all be in a plane. 
     The plastics material may be any of the known plastics materials from which toothbrushes are normally made, e.g. polypropylene, polyamide, acrylonitrile-butadienestyrene etc., and a conventional injection moulding process may be used to manufacture the grip handle. 
     Preferably the film material completely closes the void so that the void is a closed cell bounded by the film material and the plastics material walls of the cell. 
     The film material may for example be a flexible film of a plastics material, a metal foil, a paper or paper-based material, or a laminate, e.g. of two or more of these previously mentioned materials. Preferably the film material is water resistant to withstand contact with water as might be experienced during tooth brushing. The film material may be attached to the grip handle by for example shrink-wrapping or an adhesive or by welding. Preferably the attachment of the film material to the grip handle is such that water cannot pass between the film material and the plastics material. 
     Suitably the film material may also comprise a label having textual or pictorial matter printed or otherwise displayed thereon. Advantageously this enables different graphic designs to be applied to the toothbrush by the relatively simple procedure of printing a design on the film material before this is applied to the toothbrush. 
    
    
     
       The invention will now be described by way of example only with reference to the accompanying figures of which: 
         FIG. 1  shows a plan view of a toothbrush according to this invention. 
         FIG. 2  shows a side view of the toothbrush of  FIG. 1 . 
         FIG. 3  shows an underside view of the toothbrush of  FIG. 1 . 
         FIG. 4  shows a cross sectional view of the toothbrush of  FIG. 1  at the line A-A of  FIGS. 1 and 2 . 
     
    
    
     Referring to  FIGS. 1-4  a toothbrush of this invention  10  overall is shown, comprising a grip handle  11  integrally made with a toothbrush head  12  of a plastics material typically polypropylene. The toothbrush head  12  has a surface  13  which bears conventional bristles (not shown). The handle  11  is elongate along the handle-head longitudinal direction L-L and has longitudinally spaced ends  23 ,  24  respectively distant from and closer to the head  12 . Between the handle  11  and the head  12  is a neck region  14  of which the part adjacent to handle  11  is formed into “S” shaped folds. 
     The handle includes plural, i.e. eleven (there may be more or less) voids  15 , each void  15  having an opening  16  at the surface of the handle  11 . As seen in  FIG. 4  the handle  11  is substantially rectangular in cross section cut across the longitudinal direction L-L, and the voids  15  all have their openings  16  on the same surface  25  of the grip handle  11 , being a side surface, such that as seen in  FIG. 2  the openings  16  of plural voids  15  are all substantially in the plane of the side surface  25 , i.e. a plane parallel to the paper of  FIG. 1 . Each void  15  comprises a cell partly bounded by outer walls  17  which define the outer surface of the grip handle  11 , and bulkhead walls  18  integrally made of the plastics material of which the handle is made. The voids  15  are each substantially tetragonal in shape, with the bulkhead walls  18  extending across the grip handle perpendicular to the longitudinal direction L-L, and are arranged serially longitudinally along the longitudinal direction L-L of the handle, the voids  15  being separated from each other by the bulkhead walls  18  between longitudinally adjacent voids  15 . Typically the walls  17 , 18  are 1-2 mm thick. In the embodiment illustrated the volume of the voids  15  comprise ca. 40-50% of the overall internal volume of the handle  11 . 
     The opening  16  of each of the voids  15  is closed by a film material  20 , shown in  FIG. 4 , so that the void  16  is a closed cell bounded by the film material  20  and the plastics material walls  17 , 18  of the cell. In  FIG. 4  the thickness of the film material  20  is exaggerated. 
     This film material is an water-resistant plastics film material of generally known type, backed with a water-resistant adhesive, and is adhesively attached to the outer surface of the handle  11  in a known manner to cover the openings  16  of voids Alternatively for example the film material  20  may be heat shrink wrapped around handle  11  in a generally known manner. As seen in  FIG. 3  the film  20  is shown in the form of a generally cylindrical sleeve  20  which has been applied by shrink fitting over the handle  11 , and having longitudinal ends  21 ,  22 . The outer surface of the film material  20  is marked with textual and/or pictorial matter  23  e.g. a manufacturer&#39;s or marketer&#39;s trade mark. Although shown in  FIG. 4  completely surrounding the handle  11 , the film material  20  need only cover the openings  16  of the voids  15  to achieve the invention.