WO2000015077A2

WO2000015077A2 - Toothbrush head with an elastomeric bumper

Info

Publication number: WO2000015077A2
Application number: PCT/US1999/020773
Authority: WO
Inventors: Joseph Edward Fattori; Douglas J. Hohlbein; Alan Vincent Sorrentino
Original assignee: Colgate-Palmolive Company
Priority date: 1998-09-10
Filing date: 1999-09-09
Publication date: 2000-03-23
Also published as: AR020414A1; WO2000015077A9; WO2000015077A3; AU6385899A; CO5011026A1; TW467734B

Abstract

The present invention relates to a toothbrush with an elastomeric bumper and a method of production thereof to avoid injection molding flashing of the elastomer.

Description

TOOTHBR USH HEAD WITH AN ELASTOMERIC BUMPER

Field of the Invention

The present invention relates to toothbrushes and a method of production thereof, and more particularly to toothbrushes having a soft elastomeric bumper about the forward portions of a hard bristle implanting head.

Background of the Invention

As well known to those skilled in the art, a typical toothbrush is manufactured by implanting a plurality of bristle bases into the stick- shaped or hexahedral hard head of the toothbrush preform. In the typical toothbrush, the hard bristle base implanting head may scratch, bruise, and irritate the soft periodontal tissue surfaces in the oral cavity when brushing the teeth. In this regard, such a hard toothbrush head may have a bad effect on oral hygiene.

Toothbrushes such as that disclosed in U.S. Patent 5,630,244, having rim rubber infills about the side of the head in part address the above problem. However, there remains a strip of hard bristle base between the rubber infills, as well as, the hard material on the back of the typical bristle implanting head which may adversely impact the soft periodontal tissue when brushing the teeth.

Toothbrushes today are typically produced by injection molding, including "dual component" toothbrushes many containing a non-slip grippable rubbery insert within a typically hard and smooth plastic handle. In such dual component toothbrushes the rubbery insert is injected under high pressure into a steel mold about the preformed handle. With injection molding pressure as high as 140 MPa (20,000 psi), if the preformed handle is not firmly seated against the mold, the rubbery insert or other second component will be forced between the preform and the mold, a condition known as flashing. Such flashing affects the bonding of the dual components and distorts the desired appearance of the "dual component" toothbrush, effecting the consumer acceptability of the toothbrush.

There is a need for a consumer acceptable "dual component" toothbrush, wherein the front and side edges, as well as, the hard material on the back of the bristle implanting head are enclosed in a soft elastic, or rubbery material to minimize any injury to sensitive oral surfaces.

Summary of the Invention

The present invention encompasses an injection molded toothbrush gentle to soft periodontal tissue comprising, an elongated handle having a longitudinal axis; a hard bristle implanting brush head connected to the handle, the brush head composed of the following elements: a back end proximate to the handle and a front end distal from the handle, a top bristle implanting face and a back face, with side edges between the faces, said elements having an elastomeric coating applied thereon; and a portion of the brush head protruding through the coating, forming a footing, the footing being about the longitudinal axis, and providing means by which an upper section of an injection mold is enabled to hold the bristle implanting face of the head securely against a lower section of the mold, whereby flashing of the elastomeric coating is avoided.

In accordance with a another embodiment, sections of the hard bristle implanting head may be connected by one or more thin bridges integral with the hard bristle implanting head, the sections being normally biased to assume an acute angle with respect to each other; wherein, the slot(s) defined by the thin bridge and the adjacent sections of the hard bristle head are filled with the same elastomeric material which covers the front, the forward side edges and the forward portion of the back of the bristle implanting head forming a bumper thereabout. As in the first embodiment described above, there is an extended portion of the hard bristle implanting head which is integral and contiguous to the face of the hard bristle implanting head, providing a footing for the upper half of the mold to securely hold the face of the hard bristle implanting head against the lower half of the mold during the injection molding of the elastomeric material about the preformed hard bristle implanting head.

Brief Description of the Drawings

Figure 1 is a front plan view illustrating the face of the hard bristle implanting head, the bristles not shown, of this invention according to a first embodiment.

Figure 2 is a side elevation view of the toothbrush head shown at Figure 1.

Figure 3 is a back plan view of the toothbrush head shown in Figure 1. Figure 4 is a first alternate back plan view of the toothbrush head shown in Figure 1.

Figure 5 is a sectional view of the toothbrush of Figure 1, having the alternate back view of Figure 4, cut along section A-A of Figure 4.

Figure 6 is a front plan view illustrating the face of the hard bristle implanting head, the bristles not shown, of a second embodiment of this invention.

Figure 7 is a side elevation view of the toothbrush head shown at Figure 6.

Figure 8 is a back plan view of the toothbrush head shown in

Figure 6.

Figure 9 is a second alternate back plan view of a toothbrush of either the first or second embodiments.

Figure 10 is a third alternate back plan view of a toothbrush of either the first or second embodiments.

Detailed Description of the Invention

Referring now to Figure 1, a front plan view of a toothbrush bristle implanting head, 10, having a face, 14, embodying the features and construction of this invention, is shown with a portion of a handle extending therefrom designated as 12. While not completely shown, the reader will understand that the handle extends further and has a longitudinal axis. Transverse to the longitudinal axis are rows of tufting holes, 16, provided for insertion of a plurality of tufts of bristles, the bristles when inserted therein will extend at right angles from the face of the head, 14. The forward end of the hard bristle implanting head, 10, farthest from the handle, 12, is coated with an elastomeric, rubbery material, 18, which defines a bumper about the front end thereof. To provide a consumer acceptable bumper, the thickness of the elastomeric material, 18, should be from at least 0.3 to 3mm, preferably at least about 0.5 and most preferably about 1.5mm.

Figure 2, a side elevation of the toothbrush bristle implanting head of Figure 1, illustrating that the elastomeric coating extends fully over the side, from the top edge, 20, to the bottom edge, 22, thereof. Figure 3, a back plan view of the toothbrush bristle implanting head of Figure 1, illustrates that the elastomeric coating extends from the front, 24, toward the handle, 12, of the toothbrush, covering at least 10 and preferably 30 or more percent of the surface of the back of the brush, the covered area being designated 26. Within the elastomeric covered area, 26, a portion of the hard implanting head, located along and about the longitudinal axis extends through the elastomeric material, this exposed portion, 28, defines a footing which provides means when elastomeric material is injection molded about the brush head, 10, using a typical two section mold, for the upper section of the mold to force and hold the face of the hard bristle implanting head against the lower section of the mold, thus eliminating any flashing of the elastomer on the face of the bristle implanting head, i.e. an unsightly amount of extra elastomer on the face of the bristle head, 14. The elimination of the flash provides for a consumer acceptable appearance and promotes the elastomers bonding to the bristle head, 10, avoiding elastomer separation from the hard bristle head, 10. The area of exposed footing, 28, should be at least about 1mm² and preferably at least about 2mm².

Figs. 4, 9 and 10 are alternative back plan views of the toothbrush head shown in Figure 1, wherein in Figs. 9 and 10 different configuration single footings are shown, while in Figure 4 a grouping of separate footings, 30, 32 and 34, are shown. The longitudinal axis runs through the middle of the various alternative configuration footings; such uniform spacing about the longitudinal axis is helpful during injection molding to evenly distribute the closing force of the upper section of the mold onto the footings and transmitting the force through the bristle head, 10, to evenly hold the face of the bristle head, 14, against the lower section of the mold, thereby avoiding any flashing of the elastomer.

Figure 5 is a sectional view of the toothbrush of Figure 1, having the alternate back view of Figure 4, cut along section A-A of Figure 4, to illustrate the elastomer filled sections, 36, 38, and 40, within the bristle head and the footings extending through the elastomer, 42 and 44. As shown in Figure 5, the elastomer extending onto the face of the bristle head rests within a notch in the face edge of the bristle head, 46, so that the elastomer is more securely bonded to the brush head, 10. As shown in Figure 5, the notch has a depth, x, of from 0.2mm to about 0.5mm, preferably about 0.5mm.

Figs. 6, 7 and 8 illustrate another embodiment of the invention, similar to that within Figs. 1, 2 and 3, except the hard bristle head of this embodiment contains one or more thin bridges of the hard bristle implanting head material separating sections of the hard bristle head, the sections being normally biased to assume an acute angle with respect to each other; such that the sections will flex one in relation to the other as an articulated toothbrush head. The slot(s) defined by the thin bridges and the adjacent sections of the hard bristle head are filled with the same elastomeric material as that within the bumper about the front, edges and back of the hard bristle implanting head. Such an articulated toothbrush is more fully described in U.S. Patent 5,758,383, the disclosure of which is incorporated herein by reference. As in the first embodiment, this second embodiment as shown in Figure 8, provides footings to avoid flashing of the elastomeric material when it is injected to from the bumper and to fill the slot.

The hard bristle implanting head and its integral handle is preferably of molded using polypropylene, or if a clear appearance is desired of polyester, such as polyethylene terephthalate. With a preferred polypropylene hard bristle head, the elastomeric material used for the bumper about the brush head, 10, and for filling any slot therein may be a thermoplastic elastomer or combination thereof, including a thermoplastic vulcanate (TPV) which consists of a mixture of polyproplyene and EPDM (ethylene propylene diene monomers) which is available as Santoprene (brand), described in U.S. Patent 5,393,796; or Vyram (brand), another TPV consisting of a mixture of polypropylene and natural rubber, both Santoprene and Vyram being elastomers marketed by Advanced Elastomer Systems LP, Akron, Ohio 44311. Another, and preferred elastomer is Dynaflex G6713 (brand), a thermoplastic elastomer marketed by GLS Corp., Cary, Illinois 60013. These and other suitable elastomers have, typically, a Shore A hardness of from about 13 to 94, with about 29 being a preferred hardness.

Many toothbrushes available in the marketplace today are "dual component", by which is meant that an elastomeric material is filled to a greater or lesser extent within a hard plastic toothbrush, particularly in the finger gripping portion of the toothbrush. The method of manufacture of such dual component toothbrushes by injection molding is well known in the art. The toothbrushes according to the present invention may be made by use of such conventional dual component technology. For example, in accordance with the present invention, the elastomeric material may be introduced into the head area by a second injection step, after that used for the injection molding of the hard bristle implanting head and handle. In this second injection step the semi-finished toothbrush is positioned in a second mold into which the elastomer is injected about the hard bristle implanting head forming a bumper about the forward portions of the side edges, back and portions of the face thereof. As stated above, portions of the back of the hard bristle head extend to the surface of the second mold, providing footings within the elastomer filled area thereon, such footings forcing the face of the hard bristle implanting head against the second mold to avoid any flashing of the elastomer. In such a two step injection molding, the toothbrush can be molded using a two component mold, such as available from Machines Boucherie N.V., Izegem, Belgium; which mold can be mounted in a typical injection molding machine for such a two step injection process, such as the 300 ton, two component injection molding machine available from Engel Canada, Inc., Guelph, Ontario. After the molding process the toothbrush bristle implanting head may then by tufted using conventional stap le -technolo gy .

Claims

ClaimsWhat is claimed is:

1. An injection molded toothbrush gentle to soft periodontal tissue comprising:

an elongated handle having a longitudinal axis;

a hard bristle implanting brush head connected to the handle, the brush head composed of the following elements: a back end proximate to the handle and a front end distal from the handle, a top bristle implanting face and a back face, with side edges between the faces, said elements having an elastomeric coating applied thereon; and

a portion of the brush head protruding through the coating, forming a footing, the footing being about the longitudinal axis, and providing means by which an upper section of an injection mold is enabled to hold the bristle implanting face of the head securely against a lower section of the mold, whereby flashing of the elastomeric coating is avoided.

2. The toothbrush of claim 1, wherein a plurality of brush head portions protrude through the coating and form footings, the footings being spaced equally about the longitudinal axis.

3. The toothbrush of claim 1, wherein the elastomeric coating is at least 0.3 to 3 mm in thickness.

4. The toothbrush of claim 1, wherein the elastomeric coating has a Shore A hardness from 13 to 94.

5. The toothbrush of claim 4, wherein the Shore A hardness of the elastomeric coating is about 29.

6. A method of injection molding a toothbrush which is gentle to soft periodontal tissue, comprising the steps of:

(a) injection molding a hard bristle implanting head and handle, wherein the back side of the hard bristle implanting head has one or more projections extending therefrom; and

(b) injection molding about the head, an elastomeric coating material, wherein one or more projections extend as a footing through the coating on the back face of the head; so that the footing seats firmly against one face of the mold section, forcing the head firmly against the opposite face of the mold whereby flashing of the elastomeric coating is avoided.

7. The method of claim 6, wherein the elastomeric coating is at least 0.3 to 3 mm in thickness.

8. The method of claim 6, wherein the Shore A hardness of the elastomeric coating is from 13 to 94.

9. The method of claim 8, wherein the Shore A hardness of the elastomeric coating is about 29.

10. An injection molded toothbrush gentle to soft periodontal tissue comprising:

an elongated handle having a longitudinal axis;

a hard bristle implanting brush head connected to the handle, the brush head composed of the following elements: a back end proximate to the handle and a front end distal from the handle, a top bristle implanting face and a back face, with side edges between the faces, said elements having an elastomeric coating applied thereon;

a portion of the brush head protruding through the coating, forming a footing, the footing being about the longitudinal axis, and providing means by which an upper section of an injection mold is enabled to hold the bristle implanting face of the head securely against a lower section of the mold, whereby flashing of the elastomeric coating is avoided; and

the hard bristle implanting brush head having one or more thin bridges integral therein and separating sections thereof, the sections being normally biased at an acute angle with respect to each other, the thin bridges and adjacent sections forming slots, which slots are filled with the elastomeric coating.

11. The toothbrush of claim 10, wherein a plurality of brush head portions protrude through the coating and form footings, the footings being spaced equally about the longitudinal axis.

12. The toothbrush of claim 10, wherein the elastomeric coating is at least 0.3 to 3 mm in thickness.

13. The toothbrush of claim 10, wherein the elastomeric coating has a Shore A hardness from 13 to 94.

14. The toothbrush of claim 13, wherein the Shore A hardness of the elastomeric coating is about 29.