Abstract:
A toothbrush including a head having an elastomeric support member is described herein. The elastomeric support member supports a plurality of upstanding projections. At least a portion of the upstanding projections include non-elastomeric projections and elastomeric projections.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation (and claims the benefit of priority under 35 U.S.C. §120) of U.S. application Ser. No. 11/809,255, filed on May 31, 2007, now abandoned; which is a continuation of pending U.S. application Ser. No. 11/248,087, filed Oct. 12, 2005, which is a continuation of U.S. application Ser. No. 10/991,911, filed Nov. 18, 2004; which is a continuation of pending U.S. application Ser. No. 10/692,916, filed Oct. 24, 2003; which is a continuation of pending U.S. application Ser. No. 10/036,022, filed Dec. 26, 2001; which is a divisional of U.S. application Ser. No. 09/660,151, filed Sep. 13, 2000, now abandoned; which is a continuation of U.S. application Ser. No. 09/351,588, filed Jul. 12, 1999, now U.S. Pat. No. 6,151,745; which is a continuation of U.S. application Ser. No. 08/730,286, filed Oct. 30, 1996, now U.S. Pat. No. 5,987,688; which is a continuation-in-part of Ser. No. 08/554,931, filed Nov. 9, 1995, now abandoned, each of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to oral brushes and bristles for use in oral brushes. 
     BACKGROUND OF THE INVENTION 
     Most humans suffer from tooth decay and/or gingivitis caused by bacteria in the mouth. As a result, decreasing the amount of plaque in the mouth has long been the target of persons working in the health care field. A common way of minimizing the plaque in the mouth is to brush the teeth regularly. 
     However, the benefits of frequent brushing can be accompanied in some instances by deleterious side effects such as irritation, abrasion and even recession of the gums. These side effects may, in part, result from excessive stiffness and/or sharpness of the toothbrush bristles. 
     Another common way of improving oral health is by massaging the gums to stimulate the gingival tissue. Conventional toothbrushes tend to have limited effectiveness for gum-massaging, and thus often a separate gum-massaging procedure, using a gum-massaging tool, is required to ensure good oral health. 
     Endeavors have been made to reduce gum irritation and/or provide a gum-massaging effect by replacing some or all of the toothbrush bristles with rubber or synthetic rubber pins. See, e.g., U.S. Pat. No. 4,288,883. 
     SUMMARY OF THE INVENTION 
     A toothbrush in accordance with the present invention provides good cleaning of the teeth of the user. In one embodiment, a toothbrush constructed in accordance with the present invention includes a body comprising a handle and a head, a spacer, a first elastomeric element and a second elastomeric element, a least one cleaning element, and a first group of cleaning elements. The head has a recess, a top surface, a proximal area and a distal area. The proximal area is closer to the handle than the distal area. The head further includes a longitudinal axis and a lateral axis which is perpendicular to the longitudinal axis. 
     The spacer is attached to a portion of the head. The spacer has a first surface and a second surface opposed to the first surface, and the spacer is disposed in the recess. The first surface of the spacer is substantially contiguous with the top surface of the head. 
     The first elastomeric element and the second elastomeric element laterally spaced apart from the first elastomeric element. The at least one cleaning element is spaced laterally inboard of the first elastomeric element or the second elastomeric element, and the at least one cleaning element extends through the spacer. The first group of cleaning elements is disposed in the distal area, and each of the first group of cleaning elements extends away from the first surface of the spacer. 
     In another embodiment, a toothbrush constructed in accordance with the present invention comprises a body having a handle and a head, a spacer, a plurality of bristle tufts, a first plurality of elastomeric elements and a second plurality of elastomeric elements. The head has a recess therein, a top surface and a longitudinal axis. 
     The spacer has a first surface and a second surface opposed to the first surface. The spacer is disposed in the recess such that the first surface of the spacer is substantially contiguous with the top surface of the head. 
     The plurality of bristle tufts extend away from the first surface of the spacer, and each of the plurality of bristle tufts extends through the spacer. The first plurality of elastomeric elements and the second plurality of elastomeric elements extend away from the first surface of the spacer. The second plurality of elastomeric elements are longitudinally spaced from the first plurality of elastomeric elements, and at least some of the plurality of bristle tufts are longitudinally spaced from the first plurality of elastomeric elements or the second plurality of elastomeric elements. 
     In another embodiment, a toothbrush constructed in accordance with the present invention includes a body having a handle and a head, a spacer, a plurality of bristle tufts and a plurality of elastomeric elements. The head has a recessed area and a top surface adjacent the recessed area. 
     The spacer has a first surface and a second surface opposite the first surface. The spacer is disposed in the recessed area such that the first surface of the spacer is substantially contiguous to the top surface of the head. 
     The plurality of bristle tufts extend away from the first surface of the spacer and extend through the spacer. The plurality of elastomeric elements including a first pair of elastomeric elements, a second pair of elastomeric elements, and a third pair of elastomeric elements. An elastomeric element of each pair is laterally spaced apart from another elastomeric element of the same pair. The first pair, second pair, and third pair of elastomeric elements are longitudinally spaced apart. 
     In yet another embodiment, a toothbrush constructed in accordance with the present invention comprises a body have a handle and a head, a spacer, a plurality of non-elastomeric cleaning elements, a first pair of elastomeric elements, and a second pair of elastomeric elements. The head has a longitudinal axis and a lateral axis and a recess. 
     The spacer has a first surface and a second surface opposite the first surface. The spacer is disposed in the recess such that the first surface of the spacer is substantially contiguous with a top surface of the head. 
     The plurality of non-elastomeric cleaning elements extend through the spacer. The first pair of elastomeric elements are longitudinally spaced from one another, and a second pair of elastomeric elements are longitudinally spaced from one another. The first pair and the second pair of elastomeric elements are laterally spaced apart. At least one of the plurality of non-elastomeric cleaning elements is disposed laterally between the first pair of elastomeric elements and the second pair of elastomeric elements. 
     In yet another embodiment, a toothbrush constructed in accordance with the present invention comprises a body having a handle and a head, a spacer, and a plurality of bristle tufts. The head has a recess therein. The head also includes a proximal area and a distal area which is disposed adjacent a farthest point from the handle. The spacer has a first surface and a second surface opposite the first surface. The spacer is disposed in the recess. The plurality of bristle tufts are disposed in the distal area and each of the plurality of bristle tufts extends away from the first surface of the spacer. 
     In yet another embodiment, a toothbrush constructed in accordance with the present invention comprises a body having a handle and a head, a spacer, and a plurality of bristle tufts. The head has a recess. The spacer has a first surface and a second surface opposite the first surface, and the first surface is the outer surface of the spacer. The plurality of bristle tufts extend away from the first surface of the spacer and all bristle tufts of the toothbrush extend away from the first surface of the spacer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a oral brush. 
         FIG. 2  is a schematic top plan view of the head of an oral brush according to one embodiment of the invention. 
         FIG. 3  is a schematic top plan view of the head of an oral brush according to another embodiment of the invention. 
         FIG. 4  is a cross-sectional top view of a co-extruded bristle according to one embodiment of the invention. 
         FIG. 5  is a schematic diagram showing a process according to one embodiment of the invention for forming a coextruded filament. 
         FIGS. 6 and 7  are perspective views of oral brushes having bristles molded. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a toothbrush  10  includes a plastic body having a handle  12  and a head  14  attached to a bristle portion  16 . 
     The body of the toothbrush is formed by conventional methods well-known in the art. The handle is shaped to be grasped by a hand, but alternatively can be shaped to fit into an electric toothbrush. The configuration of the head can vary and may be rectangular, oval, diamond-shaped, or any other shape, with bristles which are trimmed flat, serrated, v-shaped, convex curved, or any other desired topography, as is well known in the art. The shape and size of handle  12  and head  14  can vary and the axes of the handle and head may be on the same or a different plane. It may be desired to provide a larger head than is conventional, in order to provide extra room for the thermoplastic elastomer bristles, while still retaining the standard number of non-elastomeric bristles. 
     Brush portion  16  includes a number of non-elastomeric bristles  18  and a number of elastomeric bristles  20 . Preferably, as shown in  FIG. 2 , the non-elastomeric bristles extend from the central portion of the head  14  and the elastomeric bristles are disposed around the outer perimeter of the head  14 , surrounding the non-elastomeric bristles. Another possible arrangement is shown in  FIG. 3 . 
     The non-elastomeric bristles are formed of tufts of individual filaments attached to the head in manners known to the art. The elastomeric bristles are formed of tufts of one or more filaments of thermoplastic elastomer. If a single filament is used per tuft, the filament preferably has a diameter that is half that of a standard pre-cored tuft hole, e.g., 33 mil for a 66-mil pre-cored hole, so that the filament can be folded and staple tufted into the hole. 
     Alternatively, some or all of the bristles are formed of a mixture of elastomeric and non-elastomeric polymers. The elastomeric material is selected from the group consisting of thermoplastic elastomers and vulcanized rubber-type polymers. In both cases, the ratio of the elastomer to the non-elastomeric material is preferably from 10:90-90:10. Preferred bristle diameters range from 3-100 mil (tapered or untapered), depending on the mixture used and elastomer and non-elastomeric material chosen as would be understood by one skilled in the art. 
     Suitable filaments formed of a blend of elastomeric and non-elastomeric include, but are not limited to the following: 
     
       
         
               
               
               
               
               
             
           
               
                   
               
               
                   
                 Processing 
                 Drawdown 
                   
                   
               
               
                 Composition 
                 Temp 
                 Ratio 
                 Diameter 
                 Bend Recovery 
               
               
                   
               
             
             
               
                 30% Pebax 2533 
                 250° C. 
                 4:1 
                 8 mil 
                 95% 
               
               
                 70% Zytel 151L 
               
               
                 30% Pebax 2533 
                 250° C. 
                 4:1 
                 7 mil 
                 95% 
               
               
                 70% Zytel 151L 
               
               
                   
               
             
          
         
       
     
     Such a mixture can be compounded using standard processing procedures such as a single screw or twin screw extruder or dry blending. 
     Suitable thermoplastic elastomers are those which have sufficient stiffness and hardness for effective gum massage and to resist tearing and/or excessive wear during use, while being sufficiently soft to provide comfort and avoid gum irritation during gum massage. Suitable thermoplastic elastomers include polyetheramides, e.g., PEBAX polymers (ELF Atochem); polyesters, e.g., HYTREL polymers (DuPont); styrene-ethylene-butylene-styrene block copolymers, styrene-ethylene-propylene-styrene block copolymers, styrene-butadiene-styrene block copolymers, and styrene-isoprene-styrene block copolymers, e.g., KRATON rubbers (Shell); polyurethanes, e.g., PELLETHANE polyurethanes (DOW); polyolefin elastomers, e.g., SANTOPRENE elastomers (Advanced Elastomer Systems); and mixtures thereof. Poly(ether-amide) block copolymers having the general formula 
                                
where PA=polyamide segment and PE=polyether segment, commercially available under the tradename PEBAX polymers, are particularly preferred. Of these, a copolymer of nylon 12 and poly(tetramethylene glycol) commercially available under the tradename PEBAX MX-1205 polymer is particularly preferred. Another preferred thermoplastic elastomer comprises a blend of a polyamide sold under the tradename PEBAX 2533 and a block copolymer sold under the tradename KRATON G-6713, preferably containing about 90% of the polyamide and 10% of the block copolymer. This blend provides good softness without tackiness or weakness.
 
     If a relatively soft thermoplastic elastomer is used, a relatively large diameter filament may be needed to provide sufficient durability and stiffness. Such large diameter filaments preferably have a diameter less than about 200 mil, more preferably 30 to 100 mil. If a harder, stiffer thermoplastic elastomer is used, a smaller diameter filament can be used. Generally, suitable thermoplastic elastomers will have a Shore A hardness of at least 30, preferably from about 35 to 55 and a flexural modulus of from about 5 to 100 MPa. 
     Suitable vulcanized rubber type polymers include, but are not limited to, natural rubber, crosslinked polybutadiene, cross-linked polyacrylates, and blends thereof. 
     Non-elastomeric bristles  18  may be formed of any material suitable for use in toothbrush bristles. Such materials can also be used as the non-elastomeric component of elastomeric non-elastomeric blend bristles. Preferred materials include nylon 612 and other polyamides. A preferred grade of nylon is available from Whiting Co., Burlington, Vt. under the tradename WYTEX. Preferred polyamides include polythalamides sold by Amoco Performance Products, Inc., under the tradename AMODEL resins. Such polyphthalamides are described in U.S. Pat. Nos. 4,603,166, 4,476,280, and 4,617,342, the disclosures of which are incorporated herein by reference. A particularly preferred polyphthalamide is a crystalline polyphthalamide formed by polymerization of terphthalic acid, isophthalic acid and adipic acid with hexamethylene diamine. Other suitable filaments include acetal resins, polyesters, fluoropolymers, polyacrylates, polysulfones and combinations thereof. Preferred non-elastomeric filaments have a diameter of from about 3 to 10 mil. 
     In an alternate embodiment, the elastomeric bristles include a sheath  30  of thermoplastic elastomer coextruded around a core  32  of a different material, as shown in cross-section in  FIG. 4 . The sheath to core volume ratio may be from 95:5 to 5:95. 
     Preferably, the core material is a stiff polymer, allowing the outer sheath to be softer and/or allowing the bristles to have smaller diameters than would otherwise be possible (with a thermoplastic elastomer alone) due to the constraints of bristle durability and strength. If desired the coextruded filaments can have standard bristle diameters, e.g., 5-8 mil. Preferred filament diameters range from 5 to 65 mil, depending on the application in which the bristle is to be used. Suitable core materials include but are not limited to polyamides, e.g., nylons, and polyesters, e.g., PBT. 
     Preferred sheath materials include the thermoplastic elastomers discussed above. Softer grades of these elastomers can be used when a stiff core is provided, e.g., the sheath material may have a hardness as low as 3 Shore A. 
     A suitable method for forming the coextruded filaments is shown in  FIG. 5 . As shown, the two components are extruded through first and second extruders to form a filament, after which the filament is passed through a water bath, and through a series of godets. The filament is placed under light tension as it travels between two drawing godets which are rotating at different speeds. The tension applied to the filament is expressed as the “drawdown ratio”, which is the speed differential between the two drawing godets. Preferred drawdown ratios are from about 1.0 to 7.0. The filament then passes through a relaxing godet and is collected on a take-up winder. Suitable coextruded filaments include, but are not limited to, the following: 
     
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Composition 
                   
                   
                   
               
               
                 (Sheath/Core) 
                 Volume Ratio 
                 Drawdown Rat. 
                 Diameter 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 PEBAX MX1205/ 
                 10:90 
                 4:1 
                 8 
                 mil 
               
               
                 Nylon 612 
               
               
                 PEBAX MX1205/ 
                 50:50 
                 1:1 or 2:1 
                 55 
                 mil 
               
               
                 Nylon 612 
               
               
                 Blend of 90% 
                 10:90 or 50:50 
                 4:1 
                 8 
                 mil 
               
               
                 PEBAX 2533 and 
                   
                 1:1 or 2:1 
                 55 
                 mil 
               
               
                 10% DYNAFLEX 
               
               
                 G6712/Nylon 612 
               
               
                 HYTREL 3078/ 
                 10:90 or 50:50 
                 4:1 
                 8 
                 mil 
               
               
                 Nylon 612 
                   
                 1:1 or 2:1 
                 55 
                 mil 
               
               
                   
               
             
          
         
       
     
     In an alternate embodiment, head portion  14  includes bristles  20  integrally joined to spacer  40 , which is attached to the base of head portion  14 , as shown in  FIG. 6 . Spacer  40  provides good adhesion of bristles  20  to head portion  14  and provides support to bristles  18 . The additional support provided by spacer  40  stiffens bristles  18  by decreasing the effective length of the bristles, which allows the incorporation of bristles having smaller diameters that more easily penetrate the interstitial regions of the mouth into the toothbrush. Bristles  18  extend from head portion  14  through spacer  40 . Spacer  40  is formed of the elastomeric materials listed above and can be formed of the same elastomeric material as used to form the elastomeric bristles  20 . Spacer  40  and elastomeric bristles  20  at the perimeter of head portion  14  can be molded as one unit. If the bristles  20  and spacer  40  are molded as one unit, their diameter is preferably from about 4 mil to about 200 mil. Elastomeric bristles  20  can extend at angles from spacer  40  and can optionally extend from the head portion to a radiused terminal end  71 . 
     Alternatively, spacer  40  can be recessed into head  14  such that the bristle receiving surface  46  of spacer  40  is substantially contiguous with surface  44  of head portion  14 , as shown in  FIG. 7 . 
     Other embodiments are within the claims. For example, if desired, all of the bristles may be formed of thermoplastic elastomer material. The bristles may be formed of a blend of thermoplastic elastomers. Moreover, the oral brush may include elastomeric bristles having different relative compositions, e.g., some of the bristles are formed of a first thermoplastic elastomer or blend of elastomers and other bristles are formed of a different thermoplastic elastomer or blend. Further, the elastomeric bristles may include other polymers, e.g., plasticizers such as oils, waxes or resins to increase softness, or additives, e.g., fillers, antioxidants, UV stabilizers, and abrasives or polishing agents. Suitable polishing agents include particles of plastic, particles of walnut shells, particles of hardwood, particles of corn cob, particles of rubber, calcium carbonate, aragonite clay, orthorhombic clays, calcite clay, rhombohedral clays, kaolin clay, bentonite clay, dicalcium phosphate, dicalcium phosphate anhydrous, dicalcium phosphate dihydrate, tricalcium phosphate, calcium pyrophosphate, insoluble sodium metaphosphate, precipitated calcium carbonate, magnesium orthophosphate, trimagnesium phosphate, hydroxyapatites, synthetic apatites, alumina, hydrated alumina, hydrated silica xerogel, metal aluminosilicate complexes, sodium aluminum silicates, zirconium silicate, silicon dioxide, and combinations thereof.