MXPA00000302A - Toothbrush having head with peel-resistant joint - Google Patents

Abstract

A toothbrush having a bristle-bearing head divided into at least two sections (14, 16) is disclosed. The free end section (16), when unstressed, is normally biased to assume an angle of about 15°with respect to the other, to thereby define an articulated head. The two sections of the head have facing ends joined by a thin bridge (30) or hinge section integral with the two head sections, the bridge or hinge forming a groove between adjacent head sections. The upper surface of the bridge section is substantially flush with the upper surface of the head (opposite to the bristle-bearing surface). The space between the two facing ends is filled with a soft elastomer of about 5 to about 30, preferably about 13 to about 30 Shore A hardness. This hinge construction defines an articulated head of limited flex motion, wherein, when utilized by the average adult brusher, who applies an average brushing force of 0.5 pounds, flexes to a substantially flattened position. According to a second aspect of the invention, each end of the groove terminates in a flange at its extreme outer edge, and the groove, including the flange (32), is filled with an elastomer, which, due to the presence of the flange, is resistant to peel stresses caused by flexing of the hinge or joint.

Description

TOOTHBRUSH THAT HAS A HEAD WITH A GLAZING RESISTANT GASKET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a toothbrush comprising a handle made of a relatively rigid plastic material and a multi-component toothbrush head, one component of the head being made of the same material as the handle, the other being composed of an elastomer. The head is elastic and flexible by virtue of being divided into two or more segments. Each segment is linked to an adjacent segment by means of a flexible joint, which comprises a relatively thin integral hinge or bridge, oriented transversely to the longitudinal axis of the brush, made of the same material as the handle and a slot or slit running from the upper or lower surface of the bridge to the upper surface of the bridge to the upper or lower surface of the brush, respectively, depending on the placement of the bridge.

According to one aspect of the invention, each end of the transversely oriented slot ends in a flange at its outer edge end, and the slot and the flange are filled with a soft elastomer. Due to the presence of the flange filled with elastomer, the multi-component joint is resistant to peel stresses, which are caused by the hinge flexing in such direction so that the flanges are cut one outward from the other. Stretching the head of the brush either due to brushing or by force to assume a convex shape due to the exercise of excessive brushing pressure. In another aspect, the front half to one third of the head is predisposed to what has been determined to be a desirable angle, such as 15_, with respect to the rear end of the head, where the degree of flexion is limited first by placing the bridge so that the top surface of the bridge is even with the top surface of the head and the groove runs to the bottom or bristle support surface, and secondly it is limited by the selection of elastomers that They fall within a certain range of Shore A hardness that fill the slot. 2. Description of Previous Art Toothbrushes with angled or arched bristle tip configurations that offer improved access to hard-to-reach areas such as the lingual surfaces of the front teeth, and behind the posterior molars, the placement of more bristles in contact with the teeth. External surfaces of the front teeth is well known in the art. However, many current brushes which have rigidly mounted bristles and an arched or rigidly angled bristle surface exhibit an inherent disadvantage when brushing both surfaces of flat teeth as well as concave ones because the placement of the surface of curved bristles or An angle on the surfaces of flat teeth results in fewer bristles making contact with the teeth. These few bristles must support the brushing forces applied through the handle, which will result in premature spreading of the bristles. Some toothbrushes have a "force tip" configuration (rigidly mounted and elongated tip bristles) which are claimed to have improved access benefits. Such bristles are illustrated in patent WO 94/09678; GB 304,459; Patents of the United States of America numbers 1,639,880 4,800,608, the teachings of which are hereby incorporated in their entirety.

Therefore, even when the fixed angle heads offer improved access to hard-to-reach areas, due to their disadvantages, it would be desirable to have an angled or arched brush head that will flex back to a flattened position when the brush It undergoes typical brushing force.

Toothbrushes that include heads having pivotal or hinged bends joined together in a variety of constructions, such as hinged and hinged sections are well known in the art.

For example, WO 92/17093, the teachings of which are incorporated herein in their entirety, discloses a toothbrush in which the head is divided by one or more slots forming a hinge on the side of the head opposite the side of the head. support of the bristles in at least two segments that are flexible and elastically linked to each other and / or to the handle of the toothbrush. An elastomeric material fills each such slot.

Patent WO 96/02165, the teachings of which are incorporated herein in their entirety, discloses toothbrushes with flexible and elastic heads certain embodiments of which are similar to those shown in WO 92/17093. One embodiment has an arched head and is formed by a thin elastomer-covered extension of the handle. A second embodiment is flexible due to the hinge-forming grooves on both surfaces of the head, with an elastomeric material filling such grooves, but with the bristle tips ending in a concave profile in the tension-free configuration. This head can also conform flexibly to a convex profile during brushing.

WO 97 / '07707, the teachings of which are incorporated herein in their entirety, discloses a toothbrush in which the flexibility of the head is concentrated at the tip of the head. The head comprises an essentially rigid base region adjacent to the handle on one side and a link region on the opposite side which is linked to the elastically flexible tip end. The bonding region may comprise an opening, a space or spacing in the head material, which has an elastomeric material completely or partially filling the opening, space or slit. The tip region may be angled to form a "point of force" construction.

The co-pending application of the United States of America series number 08 / 762,783, the teachings of which are hereby incorporated in its entirety, discloses a toothbrush having a flexible head divided into two separate segments, in some embodiments, by a groove in the shape of T generally, which in the longitudinal cross section, extends transversely through the upper surface of the head.

Although the above-mentioned publications illustrate toothbrushes with heads of varying degrees of flexibility, each of these fails to provide means to limit the degree of flexibility of the head.

It has also been found that certain segmented brush heads have multiple component joints that have both soft elastomer and hard plastic elements, with a hinge filled with elastomer creating a groove between the segments, there is a considerable amount of tension placed on the joint when it is forced to flex in such a way that adjacent segments are forced to flex one outward from the other. This tension can cause delamination of the elastomer, starting at the outer end edge of the groove and continuing along the entire surface of the groove leading to joint failure. None of the prior art brushes provide means for improving the adhesion of the elastomer to the groove walls.

OBJECTS OF THE INVENTION It is an object of this invention to provide a toothbrush with a flexible, elastic, segmented brush head, at least one segment of which is designed to flex, under average brushing pressure, to a predetermined extent. to result in a flattened position when the brush is subjected to an average brushing force by a typical adult consumer.

It is another object of this invention to provide a toothbrush with an articulated, flexible, elastic, flexible brush head, divided into segments by means of one or more grooves filled with elastomer, which includes means to ensure that the elastomer which fills each groove is not unduly subjected to tensile forces that cause peeling of the elastomer starting at the outer edge of the groove and continuing into the groove to thereby separate the elastomer from the hard plastic side walls of the groove.

SYNTHESIS OF THE INVENTION According to the invention, a multi-component injection-molded toothbrush comprises a bristle support head made of a first component, namely a relatively rigid plastic material which is divided into two or more sections, which, when they are not stressed, they are normally pressed to assume an angle one with respect to the other, in order to define an articulated head. The two sections of the head have opposite ends joined by a thin bridge or a hinge section oriented transversely to the longitudinal axis of the brush, the bridge is integrated with the two head sections. The upper surface of the bridge section is as close as possible, and preferably is even with the upper surface of the head (opposite the bristle support surface). The space between the two facing ends is filled with a second component, such as a soft elastomer of about 5 to about 30, preferably about 13 to about 30 shore hardness. This construction defines an articulated head of a movement of limited flexion, which, when used by the average adult brushing, who has been determined to apply an average brushing force of 0.5 pounds, flexes it to an essentially flattened position. The segmented and flexible head of this invention, in all cases, is elastic, so that when an applied force is removed, such as by brushing, the flexible head returns to its original configuration.

Thus, the aforementioned configuration provides a head having a free end segment which flexes during normal use of an initial angle of what has been determined to be from about 15_ to a flat position when brushing areas of flat teeth. This configuration also greatly resists bending beyond the initial angle of 15_ to one. Increasingly concave configuration, which is highly desirable because it prevents the bristles of the front and rear parts of the head from engaging with each other. However, the brush head will flex to a convex configuration in the event that a person who brushes aggressively exerts more than the average pressure while brushing to help both avoid or minimize gum injury.

The bridge is made of the same resin from which the toothbrush is conventionally formed by injection molding, to produce an integral construction. Typically, polypropylene resins are used to mold rigid toothbrush bodies, although certain kinds of nylon can also be used. The thin bridge allows limited bending between the two head sections, the head being injection molded in such a manner as to result, in a finished multi-component product, at an angle of about 15_ between the two head sections. That part of the head between the two head sections is in the form of a groove running from the bristle support surface of the head closely to the opposite side of the head, the hinge being as thin as possible consistent with the allow a flexibility of the head without breaking during the life of the brush. Preferably, the hinge is even or collinear with the upper surface of the hard plastic skeleton which forms the body and head of the brush. The slot is also filled by means of a conventional two-component injection molding process, with a soft elastomer to limit the degree of flexing. The construction is such that the head section furthest from the handle, in its final configuration, is inclined at an angle of about 15_ with respect to the head section closest to the handle. The rear head section located at one end of the handle.

There are considerable manufacturing efficiencies to have the elastomeric material of this invention used in the flexure area being of the same elastomeric material as that which can be used as a grip material in the handle area. Therefore, a configuration which would allow bending under loads typically encountered during brushing with materials which are suitable for use as a handle would be desirable.

To achieve the desired ranges of motion indicated above, it has been found desirable to place the plastic resin bridge between the handle and spike portions of the head as far away from the support surface of the head bristles as possible. . The top surface of the bridge is collinear or is even with the upper surface of the hard plastic skeleton of the rest of the brush.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an illustration of a raised and side view of the head of the toothbrush of this invention according to a first embodiment, the outer surface of a part of the head is provided with an elastomeric coating.

Figure 2 is a bottom plane view of the toothbrush head shown in Figure 1.

Figure 3 is a top plan view of the toothbrush head shown in Figure 1.

Figure 4A is a side elevational view of the head of the toothbrush shown in Figure 1 without the elastomeric material.

Figure 4B is a side elevational view of a second embodiment of the head of the toothbrush of this invention, similar to that of Figure 4A without the elastomeric material, but wherein the tips of the bristles in the head segment end in the same plane.

Figure 4C is a bottom plan view of the toothbrush head shown in Figures 1-3 without the elastomer coating.

Figure 5A is a side elevational view of a third embodiment of the head of the toothbrush of this invention, similar to that of Figure 4A without the elastomeric material, but with the flanges only at the edges of the ranur on the surface of bristle support Figure 5B is a bottom plan view of the head of the toothbrush shown in Figure 5A without the elastomer coating. Figure 6A is a bottom plane view of a fourth embodiment of the head of the toothbrush of this invention, similar to that of Figure 5A without the elastomeric material, but with extra-large flanges only on the edges of the groove on the surface of support of the bristles.

Figure 6B is a cross-sectional view taken along line 6B-6B of Figure 6A of the toothbrush head shown in Figure 6A.

Figure 6C is a side and outer elevated view of the toothbrush head shown in Figures 6A and 6B without the elastomeric material.

Figure 7 is an elevated side and outer view of the head of the toothbrush shown in Figures 6A-6C with the elastomeric material.

Figure 8 is an outer side elevational view of another toothbrush head, without the elastomeric coating, designed to easily flex to a convex or concave configuration, wherein the bridge between the head segments is halved between the surfaces of the toothbrush. upper and lower head, with the flanges at each outer end edge of each of the upper and lower grooves for filling with elastomer during the injection molding process.

DETAILED DESCRIPTION OF THE INVENTION The hinge configuration of an angled flexible head toothbrush according to this invention uses information which has been developed through the test indicating that the average adult who brushes his teeth exerts approximately 0.5 pounds of force. Using this information, a brush having a segmented head has been developed, flexible and angled, the segments created by hinges that form thin grooves that bridge the gap between the adjacent segments, so that the one third to one front half of this head at rest, is configured to be at an angle of 15_ from its back adjacent to the handle. Flexible head toothbrushes that have segments elastically linked to this angle have been found to offer improved access to hard-to-reach areas behind the posterior molars and behind the front teeth and to limit brush flexibility in a manner desirable.

Even though a fixed-angle head will offer improved access to the above-mentioned areas, this will offer less contact of bristles with the flat regions of the teeth (for example, the upper surfaces). It is desirable to have the brush bent back to its flattened position when the brush is subjected to the average brushing force of 0.5 lbs.

Even though the flexing action allows the angled part to move to 15_ to a flattened position under the forces indicated above, for the people brushing aggressively, the head can be allowed to continue to flex back beyond the flat position , thus reducing the negative effects of excessive brushing on the teeth and gums. In addition, the head should allow a little flexing in the opposite direction (eg, the bristle support surfaces towards each other) as this would tend to cause the front and rear bristles to inter-engage, which does not offer a benefit functional.

It has now been determined that to achieve the ranges of motion indicated above, the optimal bending joint should consist of a hinge or bridge placed as far away from the bristle surface as possible, whose hinge or bridge should be as thin as possible. Polypropylene hinges are known in the art and these are generally recommended as being .005 inches - .025 inches thick. By filling the area below the hinge with a soft elastomer of about 5 to about 30, preferably about 13 to about 30, of Shore A hardness, the desired ranges of flexibility can be achieved. With the hinge placed opposite the bristle surface, when one pushes the tip of the brush down (undesirable), the elastomer is subjected to compression forces. When the elastomers resist compression, however, this configuration prevents undesirable downward movement. At the same time, this configuration allows flexing in the opposite direction, since no elastomer is being subjected to compression as a result of the flattening of the brush head.

Therefore, the configuration claimed here provides a head which flexes during normal use from an initial angle of approximately 15_ to a flat position when an adult brushes flat tooth areas and exerts an average brushing force of 0.5 lbs. . This configuration also strongly resists flexing beyond the initial 15, which is highly desirable to prevent the bristles on the front and back of the head from snagging together.

Referring now to Figure 1, there is shown a side elevational view of a toothbrush including the features and construction of this invention in a vertical position, with a part of the handle designated with the number 12. Even though it is not completely shown, it will be understood that the handle extends horizontally and has a longitudinal axis. That part of the head closest to the handle is designated as section 14 (rear) and is collinear with the handle, while that part of the head furthest from the handle is designated as section 16 (front). An elastomer section together between the front ends of sections 14 and 16 is generally denoted by the number 18. However, as Figures 1-3 illustrate an embodiment wherein the elastomer also covers much of the top surfaces (18a), lateral (18b), lower peripheral edge (18c), and lower groove (18d) brush to act therefore as an elastomeric bumper around such surfaces of the free end of the brush in a known manner, the joint construction will be discussed down in more detail. A plurality of tufts of long bristles 20a and short bristles 20b extend at generally right angles to the section 14, while a similar plurality of tufts of long bristles 22a and short bristles 22b extend at right angles to section 16. The tufts of bristles 22a and 22b are therefore at generally right angles to the lower surface 24 of the section. of head 16, while the tufts of bristles 20a and 20b are generally perpendicular to the bottom or bottom surface 26 of the head section 14. It will be recognized by those skilled in the art, that the bristles do not need to be perpendicular to the plane of the head. bottom of the head but can assume other angles with respect to it.

As best seen in Figures 1-3, half of the elastomer-coated gasket section 18 includes an integral elastomer rim 36 and a groove 40 on either side thereof. As best seen in Figure 3, a portion of the upper surface of the hard plastic skeleton 16 is designated with the number 16a and is even with the level of the elastomer coating 18 on the upper surface of the brush. As best seen in Figure 2, the elastomer coating extends around the sides of the brush and down to the bottom surface along the edges 18c. It will be understood by those skilled in the art that such an extension of the elastomer coating to form a bumper is an unnecessary feature for the practice of this invention and is well known in the art, as demonstrated by the German patent DE 36 28 722 and the European application 0 310 482.

Referring now to Figure 4a, the brush of Figures 1-3 is shown without the elastomeric coating 18. The relatively hard plastic skeleton or brush body (as compared to the elastomer) is composed of the front section 16 having a first top surface 16a and a second top surface 16b, the surface 16b is less than the surface 16a; the rear section 14 has a first top surface 14a and a second top surface 14b, the surface 14b is less than the surface 14a; and the bridge 30, the upper surface of which, 30a, is collinear with the upper surfaces 14b and 16b. The upper surfaces 14a and 16a and the generally inverted T-shaped groove 38, in the longitudinal cross-section, start at the bottom surface of the bridge 30 and are therefore located between the sections 14 and 16 and extend down to the surfaces bottoms 24 and 26 where they end at their extreme outer edge at the flanges 32. The bridge or zone 30 is typically of a thickness between 20 and 30 thousandths of an inch. The handle 12, the head sections 14 and 16, and the bridge 30 are typically molded from a plastic or resin such as polypropylene, although certain kinds of nylon polymers may also be used. Preferred polypropylene resins include Huntsman general purpose homopolymer number 5520 and Hostalen polypropylene copolymer PPR 1042.

It has been found that there is a significant amount of tension on the joint between the rubber and the plastic wall of the groove in the hinge area. The joint rests on the fusion between the elastomer and the toughest polypropylene plastic toothbrush body material. This fusion occurs as a result of the injection under pressure of the elastomer, at a temperature higher than that of the melting point of the elastomer, on the plastic body part. Ideally, a chemical bond is formed where the two materials meet because a thin surface layer of polypropylene, for example, melts and fuses with the melted elastomer.

While it is possible to produce toothbrushes with good surface fusion between the rigid plastic and the elastomer by means of the use of a significant amount of process control, primarily controlling the temperature of the rigid plastic and the incoming molten elastomer. Even in acceptable samples, areas where the union was not as strong as in other areas have been found. It will be obvious to a person skilled in the art, which is critical to ensure a good junt for the operation and long-term safety of a flexible two-component toothbrush.

We have now found that this junt can be improved by using a mechanical configuration that is going to be discussed below.

Typically, when delamination occurs, it begins along the outer edge of the groove end at the point where the elastomer and rigid plastic meet. Under extreme stress, this delamination then extends upwards along the entire face of the slot, leading to the failure of the fusion junction. By providing a relief flange on each end of the outer edge of the groove, which is the point that suffers the most tension, we have found that the tension can be redirected along the leading or outside edge, to be therefore in an improved meeting.

The generally inverted T-shaped groove is filled with a flexible and soft thermoplastic elastomer. The inverted T-shaped groove has two symmetrical flange portions 32, each extending towards the respective groups of bristle tufts 20 and 22. The thermoplastic elastomer which forms the elastomeric sections 18-18e may be a thermoplastic vulcanite (TPV) consisting of a mixture of polypropylene and EPDM (ethylene propylene diene monomers) (Santoprene brand), or Vyram (brand), another thermoplastic vulcanite consisting of a mixture of polypropylene and natural rubber, both Santoprene and Vyram (brand) They are elastomers marketed by Advanced Elastomer Systems. A preferred elastomer includes Kraton, a brand of styrene block copolymer (SBC) marketed by Shell, and Dynaflex G 2706 (brand), a thermoplastic elastomer marketed by GLS Corporation which has been made with Kraton (brand) polymer.

These and other suitable elastomers typically have a shore A hardness of from about 5 to about 30, with about 20 being a preferred hardness. However, it should be kept in mind that the dyes used to impart color to the elastomers have an effect on their hardness, since the dyes consist of polypropylene pellets which are generally of a higher hardness than the elastomers preferred herein. Therefore, shore hardness A must be determined for the colored elastomers desired for use. The slots 40, on the upper surface of the composite head, extend on both sides of the protruding rib or flange 36, and the boundary sections 32. Figure 3 further illustrates the construction. It is seen that the elastomer section 18 extends to the width of the head sections and extends at the point 18e in the head section 14.

It should be noted that the brushes illustrated in Figures 1-4B comprise the integral head and handle parts forming a "skeleton" which is made by means of a conventional injection molding process, wherein the skeleton can be made of a plastic material relatively rigid, compared to the elastomer, such as nylon or polypropylene, wherein the relief areas are provided to allow the injection molding of the elastomer, by injection molding processes of two conventional components, used to form not only the joint, but Soft bumper cover parts of the upper surface, sides and bottom of the free end of the brush. The result is the formation of a two-component head which has a relatively smooth outer surface to prevent entrapment of food particles while brushing, to reduce or eliminate trauma and injury to the gums, to avoid undesirable mouthfeel, and to present an aesthetically pleasing visual effect. However, the objects of the invention can be filled by a brush, as shown in Figure 7, in which the elastomer is limited to the joint area.

Referring now to Figure 5A, the brush is shown without the elastomeric coating 18 and without the relief areas illustrated in Figures 4A and 4B, the brush body and the head being of a comparatively rigid plastic and only the shape slot of inverted T 38 was provided for the elastomeric material. Again, the segment 16 is at an angle of about 15_ to the segment 14. The generally inverted T-shaped slot 38, in the longitudinal cross section, begins at the bottom surface of the bridge 30 and extends downward to the surfaces lower 24 and 26 where it terminates at its outer outer edge at the flanges 32. As before, the inverted T-shaped slot 38 is filled with a soft elastic elastic thermoplastic elastomer. Figure 5B illustrates a bottom plane view of the brush of Figures 1-3 without the elastomeric coating, wherein the bridge 30 is provided with a hole 42 through which the molten elastomer 18 can flow into the slot 38, including, the lower peripheral edge area 44 wherein the elastomeric bumper extends to the lower surface 24 of the section 16.

Referring now to Figure 6A, an alternate embodiment is illustrated in which the lower flanges 32 are oversized to redirect the cutting stresses over an even larger area to thereby improve the adhesion between the elastomer and the rigid plastic walls of the groove. , and Figure 6B is a cross-sectional view of the brush of Figure 6A taken along the line 6B-6B, which clearly illustrates the enlarged flange area. Figure 6C is a side elevational view of the brush of Figures 6A and 6B.

Referring now to Figure 7, another embodiment of the brush is shown in which the elastomeric material is present only in the hinge area, including the flanges 32. The hinge 30 is collinear with the upper surfaces 16B and 14B, and the front head 16 is at an angle of 15_ with respect to the rear head section 14.

In the normal configuration of the head, it is seen that the head section 16 is inclined with respect to the head section 14 at an angle determined by the use to be about 15 optimally. Therefore, a force exerted on the brush during brushing is required to tilt the section 16 if it will be more closely or completely aligned with the section 14 along the longitudinal axis of the brush. The two head sections are molded in their angled configuration as shown in Figure 1, with the elastomer then being added during a second phase in a conventional dual component injection molding process. It will be appreciated, however, that the skeleton can be molded at an angle slightly greater than 15_ or slightly less than 15_ because of the tendency of the elastomer to shrink after molding. This shrinkage can alter the angle of the pressure point, the amount of which is controlled by the configuration of the elastomer around the hinged area. Therefore, the flexible tip segment of the skeleton can be molded at an angle of 18_ in order to achieve a final angle of 15_ in the composite two-component brush.

Referring now to Figure 8, another toothbrush head is shown, without the elastomeric coating. By virtue of placing the bridge 30 in the middle between the upper and lower head surfaces, the head segment 16 can be more easily flexed to either a convex or concave configuration, and the relief flanges 32a and 32b are provided at each outer end edge of each of the upper slots 38a and lower 38b to be filled with elastomer during the injection molding process. In this embodiment, as the lower surfaces of the head segments flex to each other, and the upper surfaces of the head segments flex outward from each other, the upper relief flanges 32b help to provide resistance to the peel stresses that they tend to cause delamination of the elastomer from the rigid brush skeleton. Similarly, as the lower surfaces of the head segments flex outwardly from each other, and the upper surfaces of the head segments flex towards each other, the lower relief flanges 32a help to provide resistance to the peeling stresses that tend to cause a similar delamination.

Many toothbrushes available in the current market are of "dual component" by which is meant that an elastomeric material is used to a greater or lesser extent, particularly in the finger grip portion of the brush. The method of manufacturing such dual component brushes by injection molding is therefore well known in the art today. The toothbrushes according to the present invention can be made by the use of conventional dual component technology. For example, according to a first method of manufacturing brushes according to the present invention, the elastomeric material can be introduced into the head area from the grip area by hand through a molded channel (assuming a hand grip area is present). Alternatively, according to known technology, the elastomer may be introduced into the head area through a second injection point or gate located in the head, thereby eliminating the need for a molded channel. A means and a method for achieving this are found in the application of the Patent Cooperation Treaty WO 94/05183 assigned to Jordan AS of Norway. The head can then be provided with tufts using conventional staple technology.

According to another method of manufacturing brushes according to the present invention, the handle and the elastomer for the grip and the head areas are molded using a three-shot molding technique. The elastomer is introduced into the head area separated from the hand grip area. This process is especially useful if the elastomer for the head section of the brush and the grip section for the hand are different elastomeric materials such as elastomers having two different Shore hardness values. For example, in some circumstances it may be desirable to use a softer elastomer for the head area than for the hand grip part of the brush. As indicated above, the head can then be provided with tufts of bristles using conventional staple technology. A complete description of the methods and machines for placing the elastically flexible bristle tufts described here and then curling and rounding the ends of the bristles will be found in copending application No. 08 / 881,335 filed on this same date and bearing the number of lawyer subject IR 5992.

The term "toothbrush", as used herein, includes the brush heads for use in either disposable head hand brushes or battery operated brushes are electric, in which cases, the stem portions thereof are equivalent to the toothbrush handles mentioned here.

While the particular embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that they are not limited thereto and that variations and modifications can be made without departing from the scope of the present invention and that appended claims are intended to cover all such modifications within the scope and spirit of the invention.

Claims (12)

R E I V I N D I C A C I O N S

1. An injection-molded toothbrush of limited flexibility having a rigid handle and an articulated head positioned along a longitudinal axis of the toothbrush, said head having a rear end adjacent to the handle and a free-tipped head remote from the end After said head is divided into at least two sections, the section in said free tip end is able to flex elastically with respect to the other of said sections, another one of said sections being attached to said handle at the rear end of said section. said head, said section at the free tip end being positioned at a preselected angle relative to the other of said head sections so that under a normal brushing pressure said head is flexed so that said at least two sections of head are bent one in relation to another towards the alignment with each other, said head has an upper surface and a surface bottom, said at least two sections have the respective longitudinally spaced ends facing each other, said spaced apart ends being joined by a thin bridge formed integrally with said two sections, said thin bridge having an upper surface and a lower surface, said surface The upper part of said thin bridge is located collinear with the upper surface of said head, a groove created between said spaced ends, the upper part of said groove ends in the lower surface of said thin bridge, each of said head sections has a plurality of tufts of bristles extending from said bottom surface thereof, an elastomer section located between said spaced apart ends to thereby form a composite head, said elastomer having a Shore A hardness of about 0.5 to about 30, preferably from around 13 to around 30, said section of elastomer extends at least from the lower surface of said thin bridge to the bottom of said slot, whereby said elastomer section is deformed during brushing under the normal brushing pressure of 0.5 pounds so that said head section in The angle is bent relative to said other head sections toward alignment with each other along said longitudinal axis.

2. The toothbrush as claimed in clause 1, characterized in that at least a part of the upper surfaces of said second head section and said thin bridge are lower than a part of the upper surface of said first head section and said handle, wherein said elastomer extends from said slot and fills said bottom portions of said top surface of said second head section and said bridge to result in a composite brush head having a rigid plastic and an elastomer essentially at the same height.

3. The toothbrush as claimed in clause 2, characterized in that said elastomer section is generally inverted in the longitudinal cross-section.

4. The toothbrush as claimed in clause 3, characterized in that the elastomer covering the upper surface of said thin bridge includes the transversely oriented parallel grooves and an integral ridge between said parallel grooves.

5. The toothbrush as claimed in clause 1, characterized in that said pre-selected angle is around 15_.

6. The toothbrush as claimed in clause 1, characterized in that said normal brushing pressure is about 0.5 pounds.

7. An injection-molded toothbrush with limited flexibility that has a rigid handle and an articulated head positioned along a longitudinal axis of the toothbrushsaid head has a rear end adjacent to said handle and a head of free tip remote from the rear end, said head being divided into at least two sections, the section in said free tip end being capable of flexing elastically with respect to the another of said sections, another one of said sections being attached to said handle at the rear end of said head, said section at said free tip end being placed at a preselected angle relative to said other said head sections so that under a normal 0.3 pound planing pressure said head is flexed so that said at least two head sections are bent one in relation to the other towards the alignment with each other, said head having a top surface and a bottom surface, said at least two head sections have the respective longitudinally spaced ends facing each other, said spaced apart ends are joined by a thin bridge integrally formed with said two sections, said bridge section has an upper surface and a lower surface, said upper surface of said thin bridge is located collinear with the upper surface of said head, a groove created between said ends spaced apart, the upper part of said groove ends in the lower surface of said thin bridge, the lower part of said groove ends in a flanged area extending to the lower surface of each of the head sections, each of said sections The head has a plurality of tufts of bristles extending from said bottom surface thereof, a section of peel-resistant elastomer located between said spaced ends to thereby form a composite head, said elastomer having a Shore A hardness of about 5 to about 30, preferably from about 13 to about 30, said The elastomer section extends at least from the lower surface of said thin bridge to the flanged area of said groove extending into the lower surface of each of the head sections, whereby said section of elastomer is deformed during brushing when said at least two head sections are bent in relation to one another towards alignment with each other.

8. The toothbrush as claimed in clause 7, characterized in that at least a part of the upper surfaces of said second head section and said thin bridge are lower than a part of the lower surface of said first section of head and said handle, wherein said elastomer extends from said groove and fills said lower portions of said upper surface of said second head section and said bridge to result in a composite brush head having a rigid plastic and an elastomer of essentially at the same height.

9. The toothbrush as claimed in clause 8, characterized in that said elastomer section is generally inverted in the longitudinal cross-section.

10. The toothbrush as claimed in clause 9, characterized in that the elastomer covering the upper surface of said thin bridge includes the transversely oriented parallel grooves and an integral rim between said parallel grooves.

11. The toothbrush as claimed in clause 7, characterized in that said pre-selected angle is around 15_.

12. An injection-molded toothbrush of limited flexibility having a rigid handle and an articulated head positioned along a longitudinal axis of the toothbrush, said head having a trailing end adjacent said handle and a head with a free tip remote from the toothbrush. rear end, said head is divided into at least two sections, the sections are able to flex elastically one with respect to another under a normal brushing pressure, said head has a top surface and a bottom surface, said at least two sections have the respective longitudinally spaced ends facing each other, said spaced apart ends being joined by a thin bridge formed integrally with said two sections, said thin bridge having an upper surface and a lower surface, a groove created by said bridge between said spaced apart ends which end in the upper or lower surface of said sections s, the end portions of said groove end in a flanged area extending to said upper or lower surface of each of said head sections, each of said head sections having a plurality of tufts of bristles extending from the lower surface thereof, a section of peel-resistant elastomer located between said spaced apart ends to thereby form a composite head, said elastomer section extends at least from the surface of said thin bridge to the flange area of said groove extending to the upper or lower surface of each of said head sections, whereby said elastomer section is deformed during brushing when said two head sections are bent one in relation to the other. SUMMARY A toothbrush having a bristle support head divided into at least two sections is described. The free end section, when not stressed, is normally pressed to assume an angle of about 15 ° with respect to the other, to thereby define an articulated head. The two sections of the head have front ends joined by a thin bridge or an integral hinge section with the two head sections, the bridge or hinge forming a slot between the two adjacent head sections. The upper surface of the bridge section is essentially even with the upper surface of the head (opposite the bristle support surface). The space between the two ends is filled with a soft elastomer of a Shore A hardness of about 5 to about 30, preferably about 13 to about 30. This hinge construction defines an articulated head of limited bending motion, where, when used by an average adult who brushes, who applies an average brushing force of 0.5 pounds, he flexes to an essentially flattened position. According to a second aspect of the invention, each end of the groove ends in a flange at its outer end edge, and the groove, including the flange, is filled with an elastomer, which due to the presence of the flange, is resistant to peeling stresses caused by bending of the hinge or joint.