TITLE VARIABLE DIAMETER FILAMENTS

This application claims the benefit of U.S. Application No. 11/219,414, filed September 2, 2005.

FIELD OF THE INVENTION

The present invention relates to a filament that can be used in a toothbrush. More particularly, the present invention relates to a toothbrush having a filament with a varying diameter along its length.

BACKGROUND OF THE INVENTION

Filaments or bristles for toothbrushes have conventionally been manufactured from constant diameter filaments that are prepared from a thermoplastic polymer. The constant diameter filament has a consistent diameter and cross sectional area along the length of the filament varying not more than 5 - 10%. There is a continuing need to improve the cleaning performance of such a toothbrush made with these filaments. Cleaning performance is a combination of interproximal cleaning between adjoining teeth and between teeth and gums and the scrubbing action to clean the surface of the teeth and gums. It is known that small diameter filaments tend to improve interproximal cleaning while larger diameter and stiffer filaments provide better scrubbing action and plaque removal.

The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:

There are numerous patents covering the use of tipped, constant diameter, filaments in toothbrushes. The following patents were identified that may be relevant: US6090488, US5500975, US5533227, and JP2000279230. However, all of these patents pertain to constant diameter filaments that are chemically tipped or mechanically tipped. This type of tipping is achieved by a secondary operation after the constant diameter filaments are produced. Because these filaments are tipped i

before being inserted into the toothbrush tuft holes, special care must be taken to insert the tufts at the proper height. This is important because any trimming done to the toothbrushes after tufting will result in the tips being modified which will lead to a decrease in cleaning effectiveness. In some cases special tufting machines and or processes are required to produce the desired brushes. In addition, although these tipped filaments provide excellent interproximal cleaning, they lack scrubbing effectiveness because the tips are very small in diameter. If the tip diameters are increased to improve scrubbing, the interproximal efficiency will be decreased.

Therefore, it is desirable to have a filament that can provide interproximal cleaning of smaller diameter filaments and the scrubbing action and plaque removal of the larger diameter and stiffer filaments.

SUMMARY OF THE INVENTION

Briefly stated, and in accordance with one aspect of the present invention, there is provided a toothbrush comprising: a handle; a toothbrush head distal to the handle; and a plurality of synthetic monofilaments with varying diameter along their length are bundled together forming tufts that are adhered to the toothbrush head, each of said synthetic monofilaments differ in varying diameter along its length from one or more synthetic monofilaments in a tuft.

Pursuant to another aspect of the present invention, there is provided a tuft for use in a toothbrush comprising a plurality of synthetic monofilaments with varying diameter along their length are bundled together forming said tuft, each of said synthetic monofilaments may differ in varying diameter along its length from one or more synthetic monofilaments in said tuft.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detailed description, taken in connection with the accompanying drawings, in which: Figure 1 shows a cross-sectional photographic view, at a magnification of 2OX, of the variable diameters of the present invention in a cut surface piece.

Figure 2 shows a cross-sectional photographic view, at a magnification of 5OX, of the filament variable diameters of the present invention in a cut surface piece.

Figure 3 shows a cross-sectional photographic view, at a magnification of 5OX, of the filaments of the present invention used to form tufts in a toothbrush having variable diameters ranging from 0.005 -0.009 inches. Figure 4 shows a cross-sectional photographic view, at a magnification of 5OX, of filaments of the present invention used in a toothbrush with tip diameters varying from 0.004 - 0.007 inches.

These figures show the varying tip diameter achieved with using the filaments of this invention. While the present invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

The filaments of the present invention are unique because they provide a variety of different diameters in the same tufts. The filaments are not constant diameter filaments that have been tipped on the ends, but filaments whose diameter varies along their length. The filaments of the current invention provide several benefits over existing constant diameter

filaments because they produce a toothbrush that has improved cleaning. The filaments of the current invention provide benefits over existing tipped filaments because they are easier to process and do not require a secondary operation, after manufacturing but prior to tufting, to produce varying diameter tips. The filaments are packaged in a similar manner to current constant diameter filaments and the variable diameter filaments can also be tufted with standard manufacturing processes. Furthermore, the filaments of the present invention provide a combination of diameters in the tuft to provide both excellent interproximal cleaning and surface cleaning of the teeth and gums. The filaments in the assembled toothbrush can also be tipped or end-rounded as part of the normal toothbrush (TB) manufacturing process. An example of end rounding the variable diameter filaments of the present invention is shown in Figures 3 - 4. These filaments were developed for toothbrush applications and improve the cleaning performance of the brush when substituted for constant diameter filaments. The filaments of present invention, when assembled into a toothbrush tuft provide filaments of varying diameters to improve both the interproximal cleaning and the scrubbing effectiveness of the toothbrush.

An embodiment of the present invention is a varying diameter synthetic monofilament produced with thermoplastic polymer. Preferred polymers have molecular weights (MW) exceeding 10,000 and most likely consist of polyamides (nylon 612, 610, 6, 1010, 66, blends and copolymers thereof), polyesters (polybutylene terephthalate, polyethylene terephthalate, and blends of the two) and polyolefins (polypropylene).

The varying diameter filaments have minimum diameters of 0.003" to 0.015" and maximum diameters from 0.005" to 0.020" and are produced using a typical monofilament production process for filaments. This process includes melting a polymer or combination of polymers from the list above using a single or twin screw extruder, extruding the molten polymer blend through a spinnerette plate to produce filaments, quenching

the filaments, drawing the filaments, annealing the filaments, and assembling the filaments into a hank (e.g. bundle of filaments approximately two (2) inches in diameter). The filaments are drawn at a draw ratio of 3.75 - 4.25, which produces a filament with a flex modulus of 400,000 to 700,000 psi depending on the polymer used. Filaments can be produced in any color by blending in different colorants or color concentrates. Also, different cross-sectional shapes such as hollow, trilocular, tetralocular and quadrilobal can be produced by extruding through different capillary shapes. In addition, filaments of the present invention can be produced containing a variety of additives such as, but not limited to, clays, Teflon® micropowders, metal powders, abrasive grits, metal particles, and antimicrobial ingredients.

Reference is now made to the drawings for a detailed description of the present invention. After the filaments are packaged into hanks, the hanks are cut into cut pieces of certain lengths. The cut pieces are then assembled into toothbrushes using the standard tufting process. Because the filaments within the hanks vary in diameters along their length, the cut piece cutting process will produce variable filament tip diameters at the surface of the cut pieces. Reference is now made to Figure 1 , which shows this varied filament tip diameter.

Reference is now made to Figure 2, which shows another embodiment of the variability in the diameter of the filaments. The tip diameters can range in size from 0.003 inches to 0.020 inches. When the filaments are tufted into a toothbrush using the standard tufting machines the tips of the filaments in the tufts will also vary in size from 0.003 to 0.020 inches before final processing.

EXAMPLE 1

A blend of nylon 612 (manufactured as Zytel® by DuPont) was loaded into the hopper of a single screw extruder. A spinneret plate with round capillaries was installed into the die head and the polymer was extruded at 240°C and quenched in 25°C water located approximately 1"

below the spinnerette plate. The diameters of the resulting filaments were varied using rubber pinch rolls that were operated at a cyclically varying surface speed as described in U.S. Patent 2,418,492 which resulted in a correspondingly varying strand caliper from 10 to 18 mils. The minimum- to-minimum diameter repeated in increments of 4". The filaments were oriented by a draw ratio of 3.75:1 to result in varying strand diameters of about 5 to 9 mils. The filaments were heat set by passing through a 17O ⁰ C - 180 ⁰ C oven. After spinning, drawing, and heat setting, the filaments were wound onto a large spool and produced into approximately 98" long hanks with an average diameter of 2". The hanks were then wrapped with paper and cut to a final length of about 96 inches. The 96- inch hanks were then cut into 34mm long cut pieces. The surface of the cut pieces contained filaments of varying diameters from 0.005 inches to 0.009inches and resembled Figures 1 and 2. The cut pieces were assembled into toothbrushes using a typical toothbrush tufting machine. The tufts of the toothbrushes were then examined and showed the same variable diameter at the tips. Reference is now made to Figure 3, which shows a typical tuft produced with this product. Figure 3 shows a tuft having a variable diameter ranging between 0.005 inches to 0.009 inches.

EXAMPLE 2

Using the same process as described in Example 1 , filament cut pieces with tip diameters varying from 0.004" to 0.007" were produced. The 0.004" to 0.007" variable diameter material was produced by the extrusion process described in Example 1. The resulting extruded filaments had a varying diameter of 0.008 to 0.014 inches. These were drawn at 3.75:1 and heat set to produce a filament with varying diameters of 0.004 to 0.007 inches. The repeat cycle for the minimum-to-minimum diameter was 4 inches. The filaments were assembled into hanks, wrapped in paper, and cut to 34mm cut pieces. The cut pieces were assembled into toothbrushes which results in the tufts having filaments

with tip diameters varying from 0.004 inches - 0.007 inches. The photograph of Figure 4 shows the actual tufts.

The toothbrushes with the 0.004 - 0.007 inch variable diameter filaments were sent to the University of Pennsylvania for testing in their dental laboratories. The brushes were tested for subgingival access, gingival margin, interproximal access efficacy (IAE), and depth of deposit removal (DDR) and compared with toothbrushes made with 0.005", 0.006", and 0.007" constant diameter filaments. The results of the testing are shown in Table 1. As can be seen, the about 0.004 - 0.007 inches of variable diameter filaments had good interproximal access, like a 0.005 inch constant diameter filament, but have a higher DDR, like a 0.006 inch filament.

With continuing reference to Figure 4, the toothbrush stiffness was also measured on brushes produced with about 0.004 - 0.007 inches of variable diameter filaments and about 0.006 inch and about 0.007 inch constant diameter filament. The results are shown in Table 2. As can be seen, the stiffness of the variable diameter brushes is lower than 0.006 inch filament, which translates to gentler treatment on the gums and a softer feel for the user while still providing the DDR that a stiffer 0.006 mil brush would produce.

Table 1 : Cleaning Properties Of Toothbrushes

Table 2: Brush Stiffness

It is therefore, apparent that there has been provided in accordance with the present invention, a filament having a variable diameter that fully satisfies the aims and advantages hereinbefore set forth. While this invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.