MXPA99011843A - Unitarily molded toothbrush - Google Patents

Abstract

A unitarily molded toothbrush is provided including a head with bristles integrally molded therewith, the bristles being integrally anchored to a top surface of the head and having a polygonal cross section defined by at least three faces, at least one of the faces gradually transitioning outward as a slope in an area near the head top surface to minimize breakage and deformation. Preferably the bristles have a triangular cross section with slopes of two of the faces being different from one another.

Description

TOOTHBRUSH BACKGROUND OF THE INVENTION Field of the Invention The invention relates to a toothbrush molded unitarily manufacturable at low cost that provides the benefits of a toothbrush molded unitarily known and traditional toothbrushes manufactured that are not unitary.

Related technique Millions of people in the world are too poor to acquire a toothbrush. Even within industrialized countries, there is an important population for which this purchase is financially difficult. There are no superfluous items of relatively low cost products that are sold which are reminiscent of the expensive ones but without a great deal of detail in the configuration of the bristles, aesthetics of the handle and pleasant feeling of the bunches of bristles inside the oral cavity. The bristles are not sculpted in a way complementary to the teeth or the handle is provided an ergonomic feature. Although virtually all low or high price commercial brushes are produced by separately adding bristles to the head area prior to the handle. Invariably the bristles are of a different material (for example nylon), different from the material that forms the head or the handle. Two-piece construction greatly increases manufacturing costs. Special machinery is necessary to implant bristles inside the head area. Unit production is therefore also relatively slow. In a review of the prior art, it has been found that certain airlines are provided to their first-class passengers with disposable portable toothbrushes. VA IG, the Brazilian airline, distributes on board a toothbrush described in the US patent. 4,408,920 (Alther et al.). The sows and part of the handle are reportedly molded together by injection. The building materials are listed in the patents and are constituted by polyethylene, nylon, polyester or polypropylene, the latter being preferred. Disposable travel brushes represent important advances in providing low cost hygiene tools for the general public at an affordable price. However, additional technical advances are necessary to improve the functional and ergonomic aspects of these products. A low cost polyethylene toothbrush of even lower cost, developed by the University of Sao Paulo, and widely distributed in that country among school-age children, is reported in the Brazilian patent 6700603. Although it is inexpensively manufacturable, bristles have a relatively short lifespan, especially when used continuously in a highly vigorous manner against teeth. The deformation and rupture of individual bristles is a major problem. A somewhat more sophisticated approach is reported in U.S. Patent 3,302,230 (Poppelmann) which describes a unitary molded tooth brush of melting index polyethylene ranging from 1.5 to 5 g / 10 min. An improved gum massage and improved tooth retention are obtained through the use of bristles with special polygonal cross sections. Unfortunately, this patent, like others, does not solve the problem of rupture and deformation of the bristles. The ergonomics of the handle is also suboptimal. Accordingly, an object of the present invention is to provide a toothbrush at relatively low cost that can be manufactured in a single step and of a unitary construction. Another objective of the present invention is to provide a toothbrush of relatively low cost with bristles less susceptible to rupture or deformation. A further objective of the present invention is to provide a toothbrush at a relatively low cost with bristles that are soft to the gums but effective in reaching the waste. foodstuffs even in striae hardly accessible between the teeth. A further objective of the present invention is to provide a toothbrush at a relatively low cost with a neck sufficiently flexible to allow the side of the head of the bristles in relation to the handle and thus be ergonomically adjustable to the pressure of the user's hand This and other objects of the present invention will become readily apparent from the following summary and detailed discussion.

BRIEF DESCRIPTION OF THE INVENTION a toothbrush unitarily molded is provided including: a head with bristles integrally formed with the head, the bristles are anchored to an upper surface of the head and each having a polygonal cross section defined by at least three faces, at least one of the faces makes a gradual transition outwards as a slope in an area near the top surface of the head to minimize rupture and deformation; a neck with first and second ends, the first end is connected to the head; and a handle with front and rear ends, the front end is connected to the second end of the neck, where the head, neck and handle are formed, all of an identical plastic material. Among the different polygonal cross sections, the most preferred one is the triangular one. More effectively for the present invention is the use of a polyolefin as the plastic material. Preferably, the polyolefin is a low density polyethylene. This polymer is optimal due to its easy molding capacity, provides a relatively stiff handle but still allows the bristles to be flexible enough to minimize any rough interaction with the gums. Although one of the faces is provided with an inclination at its base which minimizes breakage and deformation, it is advantageous to have at least two faces that perform a gradual transition outward at an inclination. The tilt can be gently curved. However, it is particularly effective that the slopes are straight. A further refinement of the present invention is that there are two of the bristle faces with inclinations which are different from each other. Generally, the inclinations can be adjusted at angles between 5 and 70 °. When two of the faces have different slopes from each other, the first of these inclinations can be set at angles between 5 and 50 °, whereas in the second of these inclinations can be set at angles between 55 and 80 °. What is most preferred is when the first inclination is between 30 and 50 ° while the second inclination is between 55 and 65 °. The differences between the first and second inclinations advantageously can vary from 5 to 40 °. Less ruptures of the bristles occur when the attachment to the surface of the head along one face of the bristle is inclined by about 45 ° and along the other face of the bristle is inclined by about 60 °. Although it is not desired to join any theory, it is considered that during injection into a non-inclined base or one having identical inclination angles for a particular sow will result in a cold flow. In other words, the injected resin will be cooled before it passes through a relatively thin mold channel to reach a deeper part in an area that forms the bristle point. The cold flow is minimized considerably by having inclinations at different angles along an entrance of a shank mold channel. The tips of the bristles can be pointed or rounded. A gentle treatment against the gums and teeth is improved by rounding the ends of the upper part of the individual bristles.

Conventional molding and plastic injection equipment can be used for the manufacture of toothbrushes in accordance with the present invention. The formation of the bristles occurs within a mold plate by die where cavities are provided with the outline of the design of the bristles. The cavities will include slanted or curved mold sections near the areas where the design of the bristles is attached to a surface of the head. Advantageously, the cavities can be ground, especially steam-ground. Not only is the release of the mold improved, but the grinding imparts a textured effect to the resulting sow. Texturing results in better cleaning and retention of toothpaste.

BRIEF DESCRIPTION OF THE DRAWINGS The above features, advantages and objects of the present invention will be more fully appreciated through the following detailed discussion, reference being made to the drawings, in which: Figure 1 is a bottom perspective view of a toothbrush of according to the present invention; Figure 2 is a top perspective view of the toothbrush according to Figure 1; Figure 3 is a cross-sectional view of a bristle with the joint rounded smoothly radially to a surface of the brush head; Figure 4 is a front elevation view of a second embodiment of the bristle showing its attachment to a surface of the brush head with two transitions inclined differently near the base of the two faces of the bristle; Figure 5 is a rear elevational view of the bristle shown in Figure 4; Figure 6 is a cross-sectional view of the second embodiment, as shown in Figure 4; Figure 7 is a cross-sectional view taken along the line 7-7 of Figure 6; and Figure 8 is a partial cross-sectional view of the die mold plate forming the bristle.

DETAILED DESCRIPTION OF THE INVENTION It has now been found that the deformation and rupture of the bristles in a toothbrush can be minimized by providing a gradual transition inclination to the bristles in polygonal cross section in an area near the surface of the brush head.

A preferred embodiment of the present invention is illustrated in Figure 1. The toothbrush includes a head 2 having bristles 3, a neck 5 and a first and second ends 6, 8 and a handle 10 with front and rear ends 12, 14. An ornamental split pad 13 and holding corrugations 15 are shown in the preferred embodiment of Figure 2, but need not be present for the purpose of this invention. Figure 1 illustrates a recess 16 in a lower surface 18 of the toothbrush. The recess 16 along its perimeter is defined by a recess opening 20. Figure 3 illustrates a cross section along a longitudinal direction of a single bristle 103. This bristle is of triangular horizontal cross section having a flat rear face 122 and flanking side faces 124, 126. Near the base of the bristle in an area attached to the surface 128 of the brush head, is a respective rib 130, 132, each with a rounded inclination 134, 136. Figure 4 illustrates a second more preferred embodiment of the bristle attachment to the brush head. The bristle 203 is also triangular in its horizontal cross section, as seen in Figure 7. The polygonal shape includes a back face 222 and flanking side faces 224, 226. A rib 230 near the base of the bristle attached to the surface 228 of the brush head performs a gradual outward transfusion forming the faces 234, 235. FIG. 5 illustrates the back side 222 with a rib 232 that forms the junction the surface 228 of the brush head along a face 236 inclined differently. Figure 6 illustrates the inclination of the face 234 as an angle of 45 ° and the inclination of the face 236 as an angle of 60 °. Figure 8 illustrates a portion of the die mold plate where the bristles of the present invention are formed. A mold wall 30 forms the face 224 and 226 of the bristle has an inlet surface 34. A central mold wall 40 has a surface 42 which forms the face 222. Near the resin entry point of the mold, the surface 42 has an inclined surface 44 which permits the formation of the face 236 of the molded bristle 203. The resin can flow angularly along the path Rl and R2 basing the gate surfaces 34 and 44. The cold flow is minimized in this arrangement in which the surfaces are sharply inclined against each other. Although this invention has been shown and described in connection with particular preferred embodiments, various changes and modifications are readily available to those skilled in the art without departing from the basic scope and point of view of this invention.

Claims (10)

1. A unitary molded toothbrush, comprising: a head with bristles integrally formed with the head, the bristles are anchored to an upper surface of the head and each has a polygonal cross section defined by at least three faces, at least ' one of the faces makes a gradual transition outwards as a tilt in an area near the top surface of the head to minimize breakage and deformation; a neck with first and second ends, the first end is connected to the head, - and a handle with front and rear end, the front end is connected to the second end of the neck, where the head, neck and handle all are formed of an identical plastic material.

2. The toothbrush, as described in claim 1, wherein at least two of the faces perform a gradual outward transition as slopes in an area near the surface of the head.

3. The toothbrush, as described in claim 1, wherein the inclination is a straight inclination.

4. The toothbrush, as described in claim 1, wherein the inclination is a curved radius inclination.

5. The toothbrush, as described in claim 1, wherein two of at least one face makes a gradual transition outwardly forming the first and second respective inclinations, the first of the inclinations being inclined differently from the second of the inclinations

6. The toothbrush, as described in claim 5, wherein the polygonal cross section is triangular.

7. The toothbrush, as described in claim 5, wherein the first and second inclinations are set at angles between 5 and 70 °.

8. The toothbrush, as described in claim 5, wherein the first inclination is set at an angle between 5 and 50 ° and the second inclination is set at an angle between 55 and 80 °.

9. The toothbrush, as described in claim 8, wherein the first slope is set at an angle between 30 and 50 °, and the second slope is set at an angle between 55 and 65 °.

10. The toothbrush, as described in claim 5, wherein the difference in inclination between the first and second inclinations varies from 5 to 40 °.