JP4246745B2 - Monofilament for brush and method for producing monofilament for brush - Google Patents

Description

  The present invention relates generally to monofilaments that may be used, for example, as bristles for toothbrushes, and in particular to monofilaments having broken ends.

  Thermoplastic polymers have long been used to form brush bristles in a wide variety of shapes. To increase the effectiveness of these brushes, the ends of such brushes are cracked or “feathered” to provide a soft bristle tip. Previously, however, there were various difficulties in breaking the bristle tips.

  In particular, various techniques have been used to break the bristles of paint brushes to improve paint performance. Such a method is particularly suitable for the bristles of paint brushes. The reason is that long cracks extending along most (up to 1 inch) are particularly desirable. However, for some brushes, only a crack at the tip is desirable. For example, the bristle length of a typical toothbrush is about half an inch (or less). If the crack is to occur along most of the bristles of the toothbrush, the bristles are not stiff enough to clean the teeth sufficiently. Thus, current possible splitting techniques are not fully addressed with the difficulties associated with breaking the tips of toothbrush bristles and other bristles where long cracks are undesirable.

U.S. Pat. No. 2,418,492 U.S. Pat. No. 3,595,952 US Pat. No. 5,128,208 U.S. Pat. No. 4,279,053

  The present invention relates to a monofilament having a plurality of internal fusion lines and a portion having at least four voids, the voids accounting for 5-20% of the cross-sectional area of the monofilament.

  The present invention also relates to a monofilament having a diameter in the range of 0.0025 to 0.012 inches, which monofilament has a six vesicle, eight vesicle, or substantially circular shape.

  In addition, the present invention relates to a method for producing extruded monofilaments with broken ends, extruding a plurality of thermoplastic polymer streams to form a plurality of monofilaments, and rotating a plurality of blades above 1000 rpm. And a step of arranging a plurality of blades in contact with the end portion of the monofilament to form a cracked end. In one embodiment of the invention, the plurality of blades are rotated at or near the natural frequency of the monofilament.

  Hereinafter, the present invention will be described in more detail with reference to the drawings, some embodiments of the present invention, and manufacturing methods corresponding thereto. Referring to FIGS. 1A, 2A, 3A, 4A, and 5A, an example of a monofilament having the shape of a six vesicle is shown. Such a shape was obtained by an extrusion method using the spinneret capillaries of FIGS. 1B, 2B, 3B, 4B, and 5B, respectively. Such monofilaments were produced by the fusion of 6 polymer streams. Each of these monofilaments 10 includes a plurality of voids 20 and a plurality of fused or fused lines. The voids are obtained with a void content of 5-20% of the cross-sectional area of the monofilament.

  The brush bristles of the present invention are made from a wide range of thermoplastic polymer materials including polyamides, polyesters, and polyolefins.

  Polyamides used to make the brush include nylon 6,6, nylon 610 (polyhexamethylene sebacamide), and nylon 612 (hexamethylene dodecanoamide). Polyesters known to be particularly well suited for the production of bristles include polybutylene terephthalate and polyethylene terephthalate. A polyolefin known to be particularly well suited for the production of bristle is polypropylene.

  The overall diameter of the brush bristles of the present invention, or the overall maximum cross-sectional dimension, is in the range of 0.0025 to 0.012 inch (0.064 to 0.3 mm).

  Preferably, six or more individual streams of polymeric material are extruded from the spinneret including the spinneret capillaries shown in FIGS. 1B, 2B, 3B, 4B, and 5B, and the streams are combined to form a single stream. By forming a single filament, the bristles of the present invention are formed. The spinneret as shown in FIGS. 6A and 6B includes a plurality of spinneret capillaries. With reference to FIGS. 1B, 2B, 3B, and 5B, in extrusion of the thermoplastic polymer stream, the polymer is extruded through openings 40. Flow fusion results in fusion lines at the boundaries of the individual flows and results in the formation of vertical voids along the fusion line. The general shape of the void can vary widely.

  Commonly described in US Pat. No. 6,057,056, after extrusion of a thermoplastic polymer stream into a single filament at an elevated temperature, the monofilament is quenched and then, for example, incorporated herein by reference. Stretch as described in.

  After the monofilament is extruded and quenched, the filament is oriented by stretching to improve the longitudinal strength. In addition, the filament is subjected to other treatments to improve the physical properties. Other processes include a process using a saturated flow as described in US Pat. No. 6,057,056, which is hereby incorporated by reference.

  The filaments may be heat set after stretching for good bend recovery. Heat setting is performed either in a gas, such as by blowing hot air over the filament, or in a liquid bath, such as by passing the filament through an oil bath. The filament is then cut to a length suitable for brush manufacture. The individual bristles are then collected into a bundle, the bundle is shaped into a tuft and brushed, and the brush is trimmed and flagged in the manner described below.

  Referring to FIG. 7A, a front view of a blade used to break the ends of the bristles of the present invention is shown. FIGS. 7B and 7C show an arrangement of three such blades separated by spacers on a common shaft about every 3/16 inch and rotating approximately one another by 120 ° C. FIG. It has been found that by rotating such a blade in excess of 1000 rpm and placing such blade in contact with the bristles, a fine tapering effect is achieved. In one embodiment of the invention, the blade is rotated at 30,000 rpm by a router motor. The interference between the bristles and the blade has been found to be preferably 1/8 to 1/4 inch, but can be varied depending on the desired crack depth. In essence, by rotating the blade at high speed and placing the blade in contact with the tip of the bristle, a fast and intense bristle cutting action is reached, thereby producing optimal bristle cracking.

  It is known that optimum bristle cracking can be obtained by rotating the blade at or near the natural frequency of the monofilament. The natural frequency of a single beam is

ここで片持ちばりに対してＡ＝３．５２であり。

Here, A = 3.52 for a cantilever.

Ｅはヤング率であり、μは単位長さ当たりの質量であり、ｌは長さである。自然な振動数は通常、秒当たりのラジアンで表され、または２πで割られ、そして分当たり６０秒をかけることによって分当たりの回転で表される。

E is Young's modulus, μ is the mass per unit length, and l is the length. Natural frequency is usually expressed in radians per second or divided by 2π and expressed in revolutions per minute by multiplying by 60 seconds per minute.

  Referring to FIG. 8, a graph of the natural frequency of 612 monofilament bristles with 550,000 psi modulus and various lengths and diameters is shown.

  The monofilament bristles of the present invention produce a number of smaller ends ("cracked tips") than previously known monofilament bristles of the same diameter. The bristles exhibit excellent durability and cleanliness, are particularly useful as bristles for toothbrushes, and produce extremely soft and fine tips. By using such a technique, the bristles of the present invention provide a plurality of smaller ends that are broken rather than rounded ends and more effectively rub the gingival area. The denser area achieved by the cracked ends of the hair in this way keeps the toothpaste in contact with the tooth surface, as well as a softer feel when contact with the soft tissue occurs in the mouth. By achieving better rub the main tooth area.

  Referring to FIG. 9, a perspective view of a toothbrush having a plurality of tapered bristles is shown. Referring to FIG. 10, there is shown a plurality of bristles having cracked ends that create a plurality of soft and fine tips. These tapered filaments spread out on the tooth surface and provide a plurality of contacts, unlike conventional solid tips that provide only one contact. FIG. 11 shows a comparison of these multiple contacts with a single contact with a solid tip. The finely cut filaments of the present invention are also adapted to penetrate wider and deeper at the gingival line so as to clean the patient's gingival line without damaging it. FIG. 12 shows such deeper insertion at the gingival line. Therefore, the tips of these soft filaments advantageously clean the interdental and gingival lines and provide a sweeping force effect. In fact, such a tapered tip will reach deeper between the teeth and increase the contact surface, resulting in a better cleaning range than conventional soft filament tips, thus reducing contact between the teeth and the toothpaste. It is known to keep. Such an arrangement provides a unique cushioning effect at the tip with extra softness added to the brush. Such softness reduces gingival bleeding during brushing. Furthermore, such bristles have proven to be as hygienic as round filaments.

  Although the present invention has been described with reference to a six vesicle bristle structure with six voids, it has also been found that an eight vesicle bristle structure (with eight voids) provides a number of advantageous effects. . FIG. 13 shows such bristles of an eight vesicle. Although 6 and 8 streams are used to obtain 6 and 8 vesicle structures, respectively, more structures with a corresponding larger number of voids may be produced using a larger number of streams. The outer shape of such six vesicles, eight vesicles, or other structures may be manufactured to have a circular or near-circular shape. FIG. 13 shows an outer shape close to such a circle.

  The percentage of cross-sectional area occupied by the voids in the monofilament is determined by the size, position, symmetry and shape of the voids. It has been found that a particular level of hollow (void) results in optimal cracking of a brush having a relatively short length, such as a toothbrush. It has been found that the voids are optimally generated with a void content of 5-20% of the cross-sectional area of the monofilament. With such a brush, if the gap is too small, such as the gap described in Patent Document 3, the effect of tapering will result in the ends of the bristle being broken rather than achieving tapering. Let's go. If the gap is too large, such as the gap described in Patent Document 4, the bristles are more easily tapered, but cracks appear to spread to the bristles during use. For use as toothbrush bristles, it is important that the tips of the bristles are cracked during manufacturing or during use by the patient without cracks spreading to the filaments. This is also true for other types of brushes, depending on the specific application of the brush and / or the length of the bristles.

  With respect to the location of the void within the monofilament, the void is located approximately half way between the center and outer edges. Longer and thinner voids have been found to achieve a greater effect of tipping than round voids.

  It is noted that the asymmetrical gap may have a natural curvature that is often undesirable for certain applications such as toothbrushes, but the gap may be symmetric or asymmetric. Preferably, the spinneret capillary opening 40 as shown in FIGS. 1B, 2B, and 3B has a radius of curvature r in the range of 5 to 12 mils. The spinneret capillary opening 40 of FIG. 2B has an inner radius (or radius of curvature) of 9 mils, while the spinneret capillary opening of FIG. 3B has a radius of 8 mils. Interestingly, using the spinneret capillary of FIG. 2B results in the asymmetric monofilament of FIG. 2A, and using the spinneret capillary of FIG. 3B results in the symmetric monofilament of FIG. 3A. Although the asymmetric monofilament of FIG. 2A appears to have no problem with design symmetry, it is important to recognize that it has a large size lobe. Having a large lobe pulls its center so that the flows are not joined together. In this way, improper space is left in the monofilaments for the two streams.

  The void content is determined by the following formula based on the weight of the hollow bristles and the weight of the virtual solid bristles having the same outer shape.

本発明は特定の好ましい具体例に関して記載されているが、当業者に明らかである他の具体例は、本発明の範囲内である。したがって、本発明の範囲は、本明細書に添付された請求の範囲にのみ限定される。

Although the invention has been described with reference to certain preferred embodiments, other embodiments that will be apparent to those skilled in the art are within the scope of the invention. Accordingly, the scope of the invention is limited only by the claims appended hereto.

Preferred embodiments of the present invention are as follows.
1. A brush monofilament having a plurality of internal fusion lines and a portion having at least four voids, wherein the voids occupy 5 to 20% of the cross-sectional area of the monofilament.
2. The monofilament is toothbrush bristles. A monofilament for a brush as described in 1.
3. The monofilament is formed from a thermoplastic polymer material. A monofilament for a brush as described in 1.
4). 2. The thermoplastic polymer material is selected from the group consisting of nylon 610, nylon 612, polyamide, and polybutylene terephthalate. A monofilament for a brush as described in 1.
5. The brush monofilament has six voids. A monofilament for a brush as described in 1.
6). The brush monofilament has eight voids. A monofilament for a brush as described in 1.
7). The brush monofilament has an outer shape close to a circle. A monofilament for a brush as described in 1.
8). The brush monofilament has an outer diameter in the range of 0.0064 to 0.030 cm. A monofilament for a brush as described in 1.
9. A monofilament for a brush having a diameter in the range of 0.0064 to 0.030 cm and having a shape close to six vesicles, eight vesicles, or a circle.
10. 8. The monofilament is a bristle for a toothbrush. A monofilament for a brush as described in 1.
11. 8. The monofilament is formed from a thermoplastic polymer material. A monofilament for a brush as described in 1.
12 8. The thermoplastic polymer material is selected from the group consisting of nylon 610, nylon 612, polyamide, and polybutylene terephthalate. A monofilament for a brush as described in 1.
13. 8. It further comprises a portion having a plurality of internal fusion lines and at least four voids, wherein the voids occupy 5-20% of the cross-sectional area of the monofilament. A monofilament for a brush as described in 1.
14 A process for producing an extruded brush monofilament having a cracked end, comprising:
Extruding a plurality of thermoplastic polymer streams to form a plurality of brush monofilaments;
Rotating a plurality of blades over 1000 rpm;
Arranging a plurality of blades in contact with the end portion of the brush monofilament to form a broken end;
The manufacturing method characterized by comprising.
15. 13. The extruding comprises the step of extruding the thermoplastic polymer stream through a spinneret. The manufacturing method as described in.
16. The extruding comprises extruding the thermoplastic polymer stream through a spinneret having a plurality of spinneret capillaries, each spinneret capillary having a curved portion having a radius of curvature in the range of 5-12 mils. 13. It has a plurality of openings. The manufacturing method as described in.
17. 13. Extrusion comprises extruding a plurality of thermoplastic polymer streams to form six or eight vesicle brush monofilaments. The manufacturing method as described in.
18. 15. The rotation occurs at a natural frequency or substantially at a natural frequency of the extruded brush monofilament. The manufacturing method as described in.
19. 15. The end portion has a length of less than 0.64 cm. The manufacturing method as described in.
20. 15. The plurality of blades are disposed in contact with only the end portion of the brush monofilament so that each of the brush monofilament has an unbroken portion and a broken portion. The manufacturing method as described in.
21. 21. The end portion has a length of less than 0.64 cm. The manufacturing method as described in.
22. A plurality of bristles having a tapered end portion and a non-tapered shaft portion, wherein the non-tapered shaft portion is a toothbrush having a six or eight vesicle shape, Each of the tapered portions has a length of less than 0.64 cm.
23. The non-tapered shaft portion is a toothbrush having a plurality of voids, and the voids occupy 5 to 20% of the cross-sectional area of the bristles. Toothbrush as described in.
24. 22. The plurality of bristles are brush monofilaments. Toothbrush as described in.
25. 22. The plurality of bristles are formed from a thermoplastic polymer material. Toothbrush as described in.
26. 22. The thermoplastic polymer is selected from the group consisting of polyhexamethylene sacacamide, polyhexamethylene decanoamide, polyamide, and polybutylene terephthalate. Toothbrush as described in.
27. Each of the non-tapered shaft portions has an outer diameter in the range of 0.0064 to 0.030 cm. Toothbrush as described in.
28. 22. Each of the tapered portions has a length of less than 0.64 cm. Toothbrush as described in.
29. A spinneret used for coextrusion of brush monofilaments, wherein the spinneret includes a plurality of spinneret capillaries, each of the spinneret capillaries being at least six for receiving at least six filament streams. A spinneret characterized by having a single hole.
30. Each of the at least six holes has a curved portion having a radius of curvature in the range of 5-12 mils 29. Spinneret described in 1.
31. The spinneret capillaries are arranged so as to extrude brush monofilaments having the shape of six or eight vesicles29. Spinneret described in 1.
32. Multiple 1. A toothbrush comprising the monofilament for a brush described in 1.
33. A plurality of bristles having a tapered end portion and a non-tapered shaft portion, wherein the non-tapered shaft portion is a toothbrush having a six or eight vesicle shape, A toothbrush characterized in that at least substantially all of the tapered portion has a length of less than 0.64 cm.
34. A plurality of bristles having a tapered end portion and a non-tapered shaft portion, wherein the non-tapered shaft portion is a toothbrush having a six or eight vesicle shape, The toothbrush characterized in that the tapered portion has a length of less than 0.64 cm.
35. A plurality of bristles having a tapered end portion and a non-tapered shaft portion, the non-tapered shaft portion having a plurality of internal fusion lines and at least four voids; , Wherein the gap occupies 5-20% of the cross-sectional area of the bristles, and the plurality of tapered end portions are less than 0.64 cm in length. The plurality of bristles are brush monofilaments, 35. Toothbrush as described in.
37. 35. The plurality of bristles are formed of a thermoplastic polymer material. Toothbrush as described in.
38. 36. The thermoplastic polymer is selected from the group consisting of polyhexamethylene sacacamide, polyhexamethylene decanoamide, polyamide, and polybutylene terephthalate. Toothbrush as described in.
39. 35. Each of the non-tapered shaft portions has an outer diameter in the range of 0.0064 to 0.030 cm. Toothbrush as described in.

It is sectional drawing of the 6 vesicle monofilament of this invention. 1B is a cross-sectional view of a spinneret capillary used to extrude the monofilament of FIG. 1A. FIG. It is sectional drawing of the other 6 vesicle monofilament of this invention. 2B is a cross-sectional view of a spinneret capillary used to extrude the monofilament of FIG. 2A. FIG. It is sectional drawing of the other 6 vesicle monofilament of this invention. 3B is a cross-sectional view of a spinneret capillary used to extrude the monofilament of FIG. 3A. FIG. It is sectional drawing of the other 6 vesicle monofilament of this invention. 4B is a cross-sectional view of a spinneret capillary used to extrude the monofilament of FIG. 4A. FIG. It is sectional drawing of the other 6 vesicle monofilament of this invention. 5B is a cross-sectional view of a spinneret capillary used to extrude the monofilament of FIG. 5A. FIG. It is a front view of a spinneret having an arrangement of a plurality of spinneret capillaries. FIG. 6B is a side view of the spinneret of FIG. 6A. It is a top view of the blade used for manufacture of the monofilament which has a broken end. It is a front view of the structure which has three blades attached to the common shaft used for breaking the terminal of the monofilament of this invention. FIG. 7B is a side view of the structure of FIG. 7B. FIG. 4 is a graph of natural frequency for a 612 monofilament having a modulus of 550,000 psi and various lengths and diameters. FIG. 5 is a perspective view of a toothbrush having a plurality of tapered bristles. FIG. 6 is a side view of a plurality of bristles with cracked ends creating a plurality of soft fine tips. FIG. 6 is a side view of a comparison between a tapered bristles bristles spread on the tooth surface and a conventional solid tip that provides only one point of contact. FIG. 6 is a view of a tapered toothbrush bristles that penetrates deeper at the gingival line to make it clearer without damaging the patient's gingiva. It is sectional drawing of the eight vesicle monofilament by this invention.

Claims (2)

A method for producing an extruded brush monofilament, comprising:
Extruding individual streams of six or more polymeric materials from the spinneret;
Combining the flows to form monofilaments having a diameter in the range of 0.0064-0.030 cm and in the shape of six or eight vesicles;
The manufacturing method characterized by comprising.   A plurality of bristles having a tapered end portion and a non-tapered shaft portion, wherein the non-tapered shaft portion is a toothbrush having a six or eight vesicle shape, The toothbrush characterized in that the tapered part has a length of less than 0.64 cm, and the bristles are monofilaments manufactured by the manufacturing method according to claim 1.

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