Toothbrush

Abstract

To provide an anchorless toothbrush that has sufficient bristle planting strength.SOLUTION: A toothbrush comprises: a tuft of bristles formed by bundling multiple filaments; and a head portion having tufting holes which are formed on a tufting surface located on the front side in the thickness direction in a manner of being recessed toward the back side and into which the bristle tufts are implanted. When one or more tufting holes having the same shape and same size in a front view are defined as one group, the bristle tuft in at least one group includes a solidified portion in which the multiple filaments are melt-solidified on one end side in the longitudinal direction. The head portion includes a fixed section that projects from the inner surface of the tufting hole and is located on the front side of the solidified portion. In a cross section in which a direction with a shorter distance is the width direction in a distance in the long axis direction of the tufting hole at the center position in the range where the tufting hole has its maximum dimension in the short axis direction parallel to the tufting surface and orthogonal to the long axis direction and a distance in the short axis direction of the tufting hole at the center position in the range where the tufting hole has its maximum dimension in the long axis direction, the solidified portion has a flat shape in which the maximum dimension in the width direction is greater than the maximum dimension in the thickness direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a toothbrush.

Background Art

[0002] In recent years, instead of the method of implanting a tuft of bifurcated bristles into the head part by a flat wire, various types of toothbrushes have been provided with the appearance of an anchorless toothbrush that does not use a flat wire. This type of toothbrush attempts to create differentiation and ensure competitive superiority through the feel and appearance that take advantage of the tuft shape and brush shape unique to anchorless.

[0003] As an anchorless toothbrush, there is known a PTt (Pressure Temperature time) type toothbrush in which one side in the longitudinal direction of a tuft is melted by heat to form a sintered ball, the sintered ball is inserted into a bristle implantation hole formed in the head part, and then heat and pressure are applied to the head part to fix the tuft to the head part (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the toothbrush disclosed in Patent Document 1, since the sintered ball is spherical, the tangent direction of the sintered ball inserted into the bristle implantation hole in contact with the upper wall that prevents the tuft from coming out in the cross-sectional shape near the inner wall of the bristle implantation hole approaches the vertical direction, so there is a problem that it is difficult to ensure sufficient bristle implanting strength.

[0006] The present invention has been made in consideration of the above points, and an object thereof is to provide an anchorless toothbrush having sufficient bristle implanting strength.

Means for Solving the Problems

[0007] The present invention has the following aspects. [1] A tuft of filaments bundled together, provided on the tip side of a handle portion extending in the longitudinal axis direction, having a tufting surface located on the front side in the thickness direction and recessed on the back side, and having a tufting hole in which the tuft of filaments is implanted; and a head portion. When one or more of the tufting holes having the same shape and the same size in a front view are grouped as one group, at least one tuft of filaments in the at least one group has a solidified portion in which a plurality of the filaments are melted and solidified on one end side in the length direction. The head portion has a fixing portion protruding from the inner surface of the tufting hole and located on the front side of the solidified portion. In a cross-section in which the shorter of the distance in the longitudinal axis direction of the tufting hole at the central position within the range where the tufting hole has the maximum dimension in the short axis direction parallel to the tufting surface and orthogonal to the longitudinal axis direction and the distance in the short axis direction of the tufting hole at the central position within the range where the tufting hole has the maximum dimension in the longitudinal axis direction is defined as the width direction, the solidified portion has a flat shape in which the maximum dimension in the width direction is larger than the maximum dimension in the thickness direction. A toothbrush. [2] The cross-sectional shape of the solidified portion is a substantially semi-circular shape bulging toward the back side. The toothbrush according to [1]. [3] Provided on the front side of the fixing portion, having a protruding portion that extends toward the front side as it goes toward the inside of the tufting hole and whose tip contacts the filament at a position on the front side of the tufting surface. The toothbrush according to [1] or [2]. [4] The distance from the position in the thickness direction of the solidified portion having the maximum dimension in the width direction to the tufting surface is shorter than the distance from the position in the thickness direction of the solidified portion having the maximum dimension in the width direction to the surface on the opposite side of the tufting surface in the thickness direction of the head portion. The toothbrush according to any one of [1] to [3]. [5] The position in the thickness direction of the bottom of the tufting hole varies according to the maximum dimension in the width direction of the solidified portion. The toothbrush according to any one of [1] to [4]. [6] The head part of the toothbrush according to any one of [1] to [5] above has a maximum dimension in the thickness direction of 1.4 mm or more and 3.0 mm or less. [7] In the major axis direction, the ratio of the total area of the implanting holes to the head area from the tip of the head part to the position of the hole edge in the implanting hole located on the most rear end side is 55% or more. The toothbrush according to any one of [1] to [6] above.

Effect of the Invention

[0008] In the present invention, an anchorless toothbrush having sufficient implanting strength can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the toothbrush of the present invention will be described with reference to FIGS. 1 to 7. Note that the following embodiments show one aspect of the present invention, do not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. In the following drawings, in order to make each configuration easier to understand, the actual structure, the scale, the number, etc. in each structure are made different.

[0011] [First Embodiment] FIG. 1 is a partial front view of a toothbrush 1 according to the first embodiment. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.

[0012] As shown in FIG. 1, the toothbrush 1 has a head portion 3 and a handle portion 4 connected to the head portion 3. The head portion 3 is located on the tip side of the handle portion 4 extending in the major axis direction (the left-right direction in FIG. 1). The head portion 3 has tufts of bristles 12 and 22 implanted therein.

[0013] The materials of the head portion 3 and the handle portion 4 are not particularly limited, and for example, it is preferable to use polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, or the like.

[0014] In the following description, the normal direction of the bristle planting surface 2 (the direction perpendicular to the paper surface in FIG. 1, the up-down direction in FIGS. 2 and 3) is defined as the thickness direction, and the direction parallel to the bristle planting surface 2 and perpendicular to the major axis direction (the up-down direction in FIG. 1, the left-right direction in FIG. 3) is defined as the minor axis direction. Also, the side facing the bristle planting surface 2 in the thickness direction is defined as the front side, and the side opposite to the front side is defined as the back side.

[0015] The head portion 3 is rectangular in shape extending in the major axis direction when viewed from the front. The head portion 3 has a bristle planting surface 2, bristle planting holes 3A and 3B, and fixing portions 5A and 5B. The head portion 3 has a first bristle planting portion 11 and a second bristle planting portion 21.

[0016] The hair implanting holes 3A are located in the first hair implanting part 11. The hair implanting holes 3A are formed by being recessed on the back side in the thickness direction from the hair implanting surface 2. The hair implanting holes 3A are formed in a shape corresponding to the front view shape of the first hair implanting part 11. The hair implanting holes 3B are located in the second hair implanting part 21. The hair implanting holes 3B are formed by being recessed on the back side in the thickness direction from the hair implanting surface 2. The hair implanting holes 3B are formed in a shape corresponding to the front view shape of the second hair implanting part 21.

[0017] The front view shapes of the first hair implanting part 11 and the second hair implanting part 21 are not particularly limited, and for example, one or more and one or more types are provided in shapes such as circular shape, elliptical shape, arc shape, ring shape, linear shape, polygonal shape, polygonal frame shape, etc.

[0018] As shown in FIG. 1, since the front view shapes of the first hair implanting part 11 and the second hair implanting part 21 are circular, the front view shapes of the hair implanting holes 3A and 3B are circular.

[0019] In the anchorless toothbrush 1, it is possible to make the hair implanting holes 3A and 3B have different shapes in the cross section along the major axis direction and the cross section along the minor axis direction, and depending on the cross section position, for example, the way of being affected by the force such as brushing is different.

[0020] Therefore, regarding the hair implanting hole 3A in the head part 3 where the hair bundle is implanted, among the distance in the major axis direction of the hair implanting hole 3A at the central position in the range where the hair implanting hole 3A has the maximum dimension in the minor axis direction and the distance in the minor axis direction of the hair implanting hole 3A at the central position in the range where the hair implanting hole 3A has the maximum dimension in the major axis direction, the direction with the shorter distance (the direction where the distance is not long) is described as the width direction. The same consideration applies to the hair implanting hole 3B. Also, when the front view shapes of the hair implanting holes 3A and 3B are perfect circles or the like and the distance in the major axis direction is the same as the distance in the minor axis direction, the minor axis direction is taken as the width direction.

[0021] In this case, since the direction with a shorter distance set in the width direction (the direction where the distance is not long) is more susceptible to the influence of the force by brushing or the like, it becomes important when considering the caulking structure. Further, the solidified portions 14 and 24, which are the caulking balls described later, tend to have the largest thickness and width at the central portion in the width direction of the hair implanting holes 3A and 3B. Therefore, the setting in the width direction is important when considering the caulking structure.

[0022] Since the hair implanting holes 3A and 3B of the present embodiment are circular in the front view shape, the maximum distance in the cross section along the major axis direction and the maximum distance in the cross section along the minor axis direction are the same.

[0023] FIG. 3 is a cross-sectional view of the head portion 3 along the width direction. The head portion 3 shown in FIG. 3 is a preformed body before the heat compression treatment described later. That is, as shown in FIG. 3, the head portion 3 is preformed, for example, by injection molding. The hair implanting hole 3A in the head portion 3 of the preformed body extends to the back side with a certain diameter. Note that the second hair implanting portion 21 is only different in size from the first hair implanting portion 11, and since the cross-sectional shape is the same, only the reference numerals are appropriately shown in the drawing, and the description of the second hair implanting portion 21 may be omitted or simplified.

[0024] The first hair implanting portions 11 are arranged on both outer sides in the minor axis direction. The first hair implanting portions 11 adjacent to each other in the major axis direction of each row have the same position in the minor axis direction, and are arranged at intervals in the major axis direction (in FIG. 1, four in each row).

[0025] The second hair implanting portions 21 are arranged closer to the center in the minor axis direction than the first hair implanting portions 11. A plurality of second hair implanting portions 21 (14 in FIG. 1) are arranged at intervals in the major axis direction. The rows of the second hair implanting portions 21 are arranged alternately along the major axis direction with two having the same position in the major axis direction and spaced apart in the minor axis direction and one adjacent in the major axis direction and different in position in the minor axis direction.

[0026] In addition, in the present embodiment, when one or more implanting holes 3A and 3B having the same shape and the same size in a front view are regarded as one group, the tuft of hair in at least one group will be described.

[0027] As shown in FIG. 2, the first implanting portion 11 has a tuft of hair 12. The tuft of hair 12 has a plurality of bundled filaments 13 and a solidified portion 14. The plurality of filaments 13 are bundled into a predetermined shape in a front view. In the present embodiment, the plurality of filaments 13 are bundled into a circular shape in a front view.

[0028] The second implanting portion 21 has a tuft of hair 22. The tuft of hair 22 has a plurality of bundled filaments 23 and a solidified portion 24. The plurality of filaments 23 are bundled into a predetermined shape in a front view. In the present embodiment, the plurality of filaments 23 are bundled into a circular shape in a front view.

[0029] Although the materials of the filament 13 and the filament 23 are not particularly limited, for example, polyamide (e.g., 6-12 nylon, 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate), polyolefin (e.g., polypropylene), etc. can be mentioned.

[0030] The solidified portion 14 is provided on the back side, which is one end side in the length direction of the tuft of hair 12. The solidified portion 14 is formed into a ball shape by being melted and solidified by heat-treating the back side in the length direction of the tuft of hair 12 with a heater or the like. The solidified portion 14 contacts the bottom 3C of the implanting hole 3A at the end on the back side. As shown in FIG. 3, the solidified portion 14 has a flat shape in which the maximum dimension L11 in the width direction is larger than the maximum dimension L12 in the thickness direction. The cross-sectional shape of the solidified portion 14 in the width direction is a substantially semi-circular shape that bulges toward the back side. The above shape of the solidified portion 14 is maintained even after the heat compression treatment described later.

[0031] The substantially semi-circular shape is defined such that, with respect to the solidified portion 14, the distance L1 is from the position in the thickness direction where the widthwise distance is the maximum dimension L11 to the end portion on the back side where the widthwise distance is the minimum on the back side, and the distance L2 is from the position in the thickness direction where the widthwise distance is the maximum dimension L11 to the end portion on the front side where the widthwise distance is the minimum on the front side, and the value represented by L2 / L1 is 0.5 or less.

[0032] As shown in FIG. 3, the maximum dimension L11 in the width direction in the solidified portion 14 is smaller than the diameter D1 of the hair implanting hole 3A in the head portion 3 of the preform. The end portions on the back side of the solidified portion 14 and the plurality of filaments 13 are inserted into the hair implanting hole 3A in the head portion 3 of the preform from the front side and contact the bottom portion 3C.

[0033] The solidified portion 24 is provided on the back side which is one end side in the length direction of the hair bundle 22. The solidified portion 24 is formed in a spherical shape by being melted and solidified when the back side in the length direction of the hair bundle 22 is heat-treated with a heater or the like. The solidified portion 24 contacts the bottom portion 3D of the hair implanting hole 3B at the end portion on the back side. The solidified portion 24 has a flat shape in which the maximum dimension L21 in the width direction is larger than the maximum dimension L22 in the thickness direction. The solidified portion 24 has a substantially semi-circular cross-sectional shape in the width direction that bulges toward the back side. The above shape of the solidified portion 24 is maintained even after the heat compression treatment described later.

[0034] The maximum dimension L21 in the width direction in the solidified portion 24 is smaller than the diameter D2 of the hair implanting hole 3A in the head portion 3 of the preform. The end portions on the back side of the solidified portion 24 and the plurality of filaments 23 are inserted into the hair implanting hole 3B in the head portion 3 of the preform from the front side and contact the bottom portion 3D.

[0035] In addition, since the solidified portions 14 and 24 are substantially semi-circular shapes that bulge toward the back side in cross-section, compared to the case where the solidified portions 14 and 24 are substantially circular shapes, it becomes possible to make the solidified portions 14 and 24 thinner in the thickness direction. As a result, it can contribute to thinning of the head portion 3. Furthermore, by thinning the head portion 3, caulking can be performed at a position close to the hair implanting surface 2 in the heat compression process described later, and ensuring the hair implanting strength can be effectively implemented.

[0036] Furthermore, since the cross-sectional shapes of the solidified portions 14 and 24 are substantially semi-circular shapes that bulge toward the back side, the protruding amounts of the solidified portions 14 and 24 protruding outward in the width direction from the filaments 13 and 23 tend to increase, and the fixing of the hair bundles 12 and 22 by the fixing portions 5A and 5B can be strengthened.

[0037] From the viewpoint of hair loss during brushing, it is preferable that the diameters of the hair implanting holes 3A and 3B are 1.5 mm or more because the contact area with the solidified portions 14 and 24 becomes large. Also, the above distance L1 is preferably 0.5 mm or more and 1.8 mm or less from the viewpoint of ensuring the hair implanting strength of the solidified portions 14 and 24. Also, in the head portion 3, since the hair bundles 12 and 22 located on the outermost periphery are subject to a relatively large physical load regarding hair loss during brushing, it is preferable that the cross-sectional shapes of the solidified portions 14 and 24 satisfy a substantially semi-circular shape that bulges toward the back side in the outermost hair implanting holes 3A and 3B.

[0038] The fixing portion 5A protrudes from the inner surface of the hair implanting hole 3A and is located on the front side of the solidified portion 14. The fixing portion 5A protrudes from the inner surface over the entire circumference of the hair implanting hole 3A and is located on the front side of the solidified portion 14. Since the fixing portion 5A is located on the front side of the solidified portion 14, the solidified portion 14 whose end portion on the back side contacts the bottom portion 3C of the hair implanting hole 3A can be held in the thickness direction, so that unnecessary movement of the hair bundle 12 in the thickness direction can be suppressed, contributing to ensuring and stabilizing the hair implanting strength.

[0039] The fixing part 5B protrudes from the inner surface of the hair implanting hole 3B and is located on the front side of the solidifying part 24. The fixing part 5B protrudes from the inner surface over the entire circumference of the hair implanting hole 3B and is located on the front side of the solidifying part 24. Since the fixing part 5B is located on the front side of the solidifying part 24, the solidifying part 24 whose end on the back side contacts the bottom 3D of the hair implanting hole 3B can be held in the thickness direction, so that unnecessary movement of the tuft 22 in the thickness direction is suppressed, contributing to ensuring and stabilizing the hair implanting strength.

[0040] As shown in FIG. 3, the toothbrush 1 having the above configuration is manufactured by subjecting the head portion 3 of the preform to heat compression treatment in the thickness direction using, for example, a metal press member P1 and a press member P2 that are heated by a heater.

[0041] The press member P1 is disposed on the front side of the head portion 3 of the preform. The press member P1 is joined from the front side to the surface facing the front side in the head portion 3 of the preform. The press member P1 has holding holes 91 and 92 penetrating in the thickness direction. The holding hole 91 is formed at a position facing the hair implanting hole 3A in the thickness direction when the press member P1 is disposed on the front side of the head portion 3 of the preform. The holding hole 91 has a plurality of bundled filaments 13 pierced therethrough from the back side. The holding hole 91 holds the plurality of bundled filaments 13 from the radially outer side. The holding hole 92 is formed at a position facing the hair implanting hole 3B in the thickness direction when the press member P1 is disposed on the front side of the head portion 3 of the preform. The holding hole 92 has a plurality of bundled filaments 23 pierced therethrough from the back side. The holding hole 92 holds the plurality of bundled filaments 23 from the radially outer side.

[0042] The press member P2 is disposed on the back side of the head portion 3 of the preform. The press member P2 is joined from the back side to the surface facing the back side in the head portion 3 of the preform.

[0043] When heat-compressing the head portion 3 of the preform in the thickness direction, the head portion 3 of the preform, the press member P1, and the press member P2 are arranged with the front side on the lower side and the back side on the upper side. The press member P1 is joined to the surface facing the front side of the head portion 3 of the preform with a plurality of bundled filaments 13 pierced through the holding holes 91 from the front side, so that the solidified portion 14 is inserted into the hair implanting hole 3A and the solidified portion 24 is inserted into the hair implanting hole 3B.

[0044] Then, by pressing the heated press member P1 and the press member P2 toward each other in the heated state, the resin melted by heat compression in the head portion 3 of the preform flows into the hair implanting holes 3A and 3B where the flow pressure is low and is caulked.

[0045] As a result, as shown in FIG. 2, a fixing portion 5A is formed on the front side of the solidified portion 14 in the hair implanting hole 3A. Also, in the hair implanting hole 3B, a fixing portion 5B is formed on the front side of the solidified portion 24. By forming the fixing portion 5A in the hair implanting hole 3A and the fixing portion 5B in the hair implanting hole 3B, the toothbrush 1 with the tufts 12 and 22 fixed to the head portion 3 is manufactured.

[0046] FIG. 4 (Comparative Example) is a partial cross-sectional view showing the head portion 3 in which the cross-sections of the solidified portions 14 and 24 are spherical. FIG. 5 is a partial cross-sectional view showing the head portion 3 in which the cross-sections of the solidified portions 14 and 24 are flat. As shown in FIG. 4, when the cross-sections of the solidified portions 14 and 24 are spherical, the tangent line at the position where it contacts the fixing portions 5A and 5B at the front end of the front side of the solidified portions 14 and 24 and the inner surfaces of the fixing portions 5A and 5B intersect at an angle θ1. On the other hand, as shown in FIG. 5, when the cross-sections of the solidified portions 14 and 24 are flat, the tangent line at the position where it contacts the fixing portions 5A and 5B at the front end of the front side of the solidified portions 14 and 24 and the inner surfaces of the fixing portions 5A and 5B intersect at an angle θ2.

[0047] When the cross-section of the curing parts 14 and 24 is spherical, the angle θ1 is smaller than the angle θ2. Therefore, when a force acting in the front direction is applied to the hair bundles 12 and 22, slippage may occur at the interface between the back surface of the fixing parts 5A and 5B and the surface of the curing parts 14 and 24, and the hair implanting strength may decrease.

[0048] On the other hand, when the cross-section is flat, the angle θ2 is larger than the angle θ1. Therefore, when a force acting in the front direction is applied to the hair bundles 12 and 22, slippage hardly occurs at the interface between the back surface of the fixing parts 5A and 5B and the surface of the curing parts 14 and 24, and it has a configuration in which it is easy to ensure the hair implanting strength.

[0049] FIG. 6 is a partial cross-sectional view showing the head part 3 after the heat compression treatment along the width direction. As shown in FIG. 6, the cured part 14 after the heat compression treatment has a flat shape in which the maximum dimension L11 in the width direction is larger than the maximum dimension L12 in the thickness direction, as shown in FIG. 3, and the cross-sectional shape in the width direction is a substantially semi-circular shape that bulges toward the back side.

[0050] In the cured part 14, let the distance from the position in the thickness direction where the distance in the width direction is the maximum dimension L11 to the hair implanting surface 2 be L31, and the distance from the position in the thickness direction where the maximum dimension L11 is obtained to the surface 6 on the side opposite to the hair implanting surface 2 in the thickness direction of the head part 3 be L32. When the distance L31 is longer than the distance L32, the cured part 14 contacts the inner surface of the hair implanting hole 3A on the back side rather than the central position in the thickness direction of the head part 3. In this case, the distance from the position in the thickness direction where the maximum dimension L11 is obtained to the fixing part 5A becomes long for the hair bundle 12, and the fixing in the cured part 14 may become unstable.

[0051] Therefore, by making the distance L31 shorter than the distance L32, the distance from the position in the thickness direction where the maximum dimension L11 is obtained to the fixing part 5A becomes short for the hair bundle 12, and the stabilization of the fixing in the cured part 14 can be achieved.

[0052] Similarly, as shown in FIG. 3, the solidified portion 24 after the heat compression treatment has a flat shape in which the maximum dimension L21 in the width direction is larger than the maximum dimension L22 in the thickness direction, and the cross-sectional shape in the width direction is a substantially semi-circular shape that bulges toward the back side.

[0053] In the solidified portion 24, the distance from the position in the thickness direction where the distance in the width direction becomes the maximum dimension L21 to the flocked surface 2 is defined as L41, and the distance from the position in the thickness direction where the distance becomes L41 to the back side surface 6 of the head portion 3 is defined as L42. By making the distance L41 shorter than the distance L42, the distance from the position in the thickness direction where the maximum dimension L21 is reached to the fixing portion 5B of the tuft 22 becomes shorter, and the fixing in the solidified portion 24 can be stabilized.

[0054] Also, at the position in the thickness direction of the solidified portion 14, the distance from the position where the distance in the width direction becomes the maximum dimension L11 to the position of the front side end portion of the solidified portion 14 is defined as L51, and the distance from the position of the front side end portion of the solidified portion 14 to the flocked surface 2 is defined as L52. Then, it is preferable that the distance L52 is longer than the distance L51. By making the distance L52 longer than the distance L51, the position where the distance in the width direction becomes the maximum dimension L11 of the tuft 12 comes closer to the fixing portion 5A, and the resin caulked by the heat compression treatment easily contacts the solidified portion 14 from the front side. Therefore, the stability of the solidified portion 14 inside the flocking hole 3A is enhanced, and the flocking strength can be further stabilized.

[0055] Similarly, at the position in the thickness direction of the solidified portion 24, the distance from the position where the distance in the width direction becomes the maximum dimension L21 to the position of the front side end portion of the solidified portion 24 is defined as L61, and the distance from the position of the front side end portion of the solidified portion 24 to the flocked surface 2 is defined as L62. Then, it is preferable that the distance L62 is longer than the distance L61. By making the distance L62 longer than the distance L61, the position where the distance in the width direction becomes the maximum dimension L21 of the tuft 22 comes closer to the fixing portion 5B, and the resin caulked by the heat compression treatment easily contacts the solidified portion 24 from the front side. Therefore, the stability of the solidified portion 24 inside the hair implanting hole 3B is enhanced, and the hair implanting strength can be further stabilized.

[0056] Also, in the solidified portion 14, when the distance from the position of the end portion on the back side in the thickness direction to the surface 6 is L71, it is preferable that the distance L71 is longer than the distance L52. By making the distance L71 longer than the distance L52, the hair bundle 12 can bring the position where the distance in the width direction becomes the maximum dimension L11 closer to the fixing portion 5A.

[0057] Similarly, in the solidified portion 24, when the distance from the position of the end portion on the back side in the thickness direction to the surface 6 is L81, it is preferable that the distance L81 is longer than the distance L62. By making the distance L81 longer than the distance L62, the hair bundle 22 can bring the position where the distance in the width direction becomes the maximum dimension L21 closer to the fixing portion 5B.

[0058] As the distances L51 and L61, it is preferable that they are 0 mm or more and 1.0 mm or less. As the distances L32 and L42, it is preferable that they are 0.6 mm or more and 2.6 mm or less. As the distances L52 and L62, it is preferable that they are 0.2 mm or more and 1.0 mm or less.

[0059] In order to ensure the positions in the thickness direction of the solidified portions 14 and 24 described above, as shown in FIG. 2, it is preferable that the positions in the thickness direction of the bottoms 3C and 3D in the hair implanting holes 3A and 3B are different according to the maximum dimensions L11 and L21 in the width direction of the solidified portions 14 and 24. Specifically, since the solidified portion 24 with a smaller maximum dimension L21 in the width direction may have a smaller dimension in the thickness direction than the solidified portion 14, depending on the ratio or difference of the maximum dimensions L11 and L21, it is preferable that the position of the bottom 3D in the thickness direction is set closer to the front side than the position of the bottom 3C in the thickness direction. By setting the positions in the thickness direction of the bottoms 3C and 3D according to the maximum dimensions L11 and L21 in the width direction, it is possible to optimize the positions in the thickness direction where the distances in the width direction in the solidified portions 14 and 24 become the maximum dimensions L11 and L21 and the positions of the fixing portions 5A and 5B.

[0060] The maximum dimension in the thickness direction of the head portion 3 is preferably 1.4 mm or more and 3.0 mm or less, and more preferably 1.6 mm or more and 2.7 mm or less. When the maximum dimension in the thickness direction of the head portion 3 is 1.4 mm or more and 3.0 mm or less, sufficient hair implanting strength can be ensured.

[0061] In the major axis direction, the ratio of the total area of the hair implanting holes 3A and 3B to the head area up to the position of the hole edge indicated by the two-dot chain line in the hair implanting hole 3B located on the most rear end side from the tip of the head portion 3 is preferably 55% or more. When the total area of the hair implanting holes 3A and 3B is 55% or more with respect to the head area, the amount of the surface resin of the head portion 3 that can be used for caulking is reduced, but sufficient hair implanting strength can still be ensured in that case.

[0062] As described above, in the toothbrush 1 of the present embodiment, the fixing portions 5A and 5B are provided on the front side of the solidified portions 14 and 24 of the tufts 12 and 22 inserted into the hair implanting holes 3A and 3B. Since the solidified portions 14 and 24 are flat in the cross section in the width direction, it is difficult for slippage to occur at the interface with the fixing portions 5A and 5B, and sufficient hair implanting strength can be ensured.

[0063] [Second Embodiment] Subsequently, a second embodiment of the toothbrush 1 will be described with reference to FIG. 7. In this figure, the same elements as those in the first embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals, and the description thereof is omitted.

[0064] FIG. 7 is a cross-sectional view showing the head portion 3 of the toothbrush 1 according to the second embodiment. As shown in FIG. 7, the head portion 3 has a protrusion 7 and a protrusion 8. The protrusion 7 is provided on the front side of the fixing portion 5A. The protrusion 7 is inclined in a direction extending toward the front side as it goes toward the inside of the hair implanting hole 3A. The tip of the protrusion 7 contacts the filament 13 from the outside in the radial direction at a position on the front side of the hair implanting surface 2.

[0065] The protrusion 8 is provided on the front side of the fixing portion 5B. The protrusion 8 is inclined in a direction extending toward the front side as it goes toward the inside of the hair implanting hole 3B. The tip of the protrusion 8 contacts the filament 23 from the outside in the radial direction at a position on the front side of the hair implanting surface 2. Other configurations are the same as those in the first embodiment.

[0066] The above protrusions 7 and 8 can be formed, for example, by making the diameters of the holding holes 91 and 92 in the pressing member P1 larger than the diameter of the bundled filaments 13 and the diameter of the bundled filaments 23, or by providing recesses (for example, chamfered shapes) corresponding to the shapes of the protrusions 7 and 8 at the end portions on the back side of the holding holes 91 and 92.

[0067] In this embodiment, since the protrusion 7 is provided on the front side of the fixing portion 5A, the frictional force increases due to the increase in the contact area between the filament 13 and the protrusion 7, making it difficult for the hair bundle 12 to move in the thickness direction. Also, even when the end portion on the front side in the solidifying portion 14 is close to the hair implanting surface 2, the resin thickness during caulking can be ensured, so that the hair implanting strength can be ensured.

[0068] Similarly, in this embodiment, since the protrusion 8 is provided on the front side of the fixing portion 5B, the frictional force increases due to the increase in the contact area between the filament 23 and the protrusion 8, making it difficult for the hair bundle 22 to move in the thickness direction. Also, even when the end portion on the front side in the solidifying portion 24 is close to the hair implanting surface 2, the resin thickness during caulking can be ensured, so that the hair implanting strength can be ensured.

[0069] When the protrusions 7 and 8 protrude significantly towards the front side, the movement of the tufts 12 and 22 in the brushing direction is suppressed, which affects the usability. Therefore, the distance from the implanting surface 2 to the front-side ends of the protrusions 7 and 8 is preferably 0.1 mm or more and 1.0 mm or less, and more preferably 0.2 mm or more and 0.5 mm or less.

[0070] Also, when a large amount of resin flows into the protrusions 7 and 8 formed during the caulking of the heat compression treatment, there is a possibility that the contact between the back sides of the fixing parts 5A and 5B and the solidified parts 14 and 24 becomes insufficient on the back side of the implanting surface 2. Therefore, among the cross-sectional areas of the respective protrusions 7 and 8 and the resin existing inside the width direction from the top of the width of the fixing parts 5A and 5B on the back side of the implanting surface 2 towards the implanting surface 2, the ratio of the cross-sectional area of the resin on the back side of the implanting surface 2 is preferably 0.5:9.5 to 5:5.

[0071] In the toothbrush 1 of the present embodiment, in addition to obtaining the same operations and effects as those of the first embodiment, since the protrusions 7 and the protrusions 8 are provided, the contact area increases, so that the frictional force increases and the implanting strength can be more ensured.

[0072] As described above, the preferred embodiments of the present invention have been described with reference to the accompanying drawings. Needless to say, the present invention is not limited to such examples. The various shapes and combinations of the constituent members shown in the above examples are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

Explanation of Reference Numerals

[0073] 1... Toothbrush, 2... Implanting surface, 3... Head part, 3A, 3B... Implanting holes, 4... Handle part, 5A, 5B... Fixing parts, 6... Surface, 7, 8... Protrusions, 12, 22... Tufts, 13, 23... Filaments, 14, 24... Solidified parts

Claims

1. A tuft of filaments bundled together, provided at the tip side of a handle portion extending in the major axis direction, having a tufting surface located on the front side in the thickness direction and recessed on the back side to form a tufting hole in which the tuft of filaments is implanted, a head portion; comprising: When one or more of the tufting holes having the same shape and the same size in a front view are regarded as one group, the tuft of filaments in at least one of the groups has a solidified portion in which a plurality of the filaments are melted and solidified on one end side in the length direction, The head portion has a fixing portion protruding from the inner surface of the tufting hole and located on the front side of the solidified portion, In a cross-section with the direction in which the distance is shorter among the distance in the major axis direction of the tufting hole at the central position in the range where the tufting hole has the maximum dimension in the minor axis direction parallel to the tufting surface and orthogonal to the major axis direction and the distance in the minor axis direction of the tufting hole at the central position in the range where the tufting hole has the maximum dimension in the major axis direction as the width direction, the solidified portion has a flat shape in which the maximum dimension in the width direction is larger than the maximum dimension in the thickness direction, a toothbrush.

2. The cross-sectional shape of the solidified portion is a substantially semi-circular shape bulging toward the back side, The toothbrush according to claim 1.

3. provided on the front side of the fixing portion, having a protruding portion that extends toward the front side as it goes toward the inside of the tufting hole and the tip of which contacts the filament at a position on the front side of the tufting surface, The toothbrush according to claim 1 or 2.

4. The distance from the position in the thickness direction of the solidified portion having the maximum dimension in the width direction to the tufting surface is shorter than the distance from the position in the thickness direction of the solidified portion having the maximum dimension in the width direction to the surface on the opposite side of the tufting surface in the thickness direction in the head portion, The toothbrush according to claim 1 or 2.

5. The position of the bottom in the thickness direction in the hair implanting hole varies according to the maximum dimension in the width direction in the solidified part. The toothbrush according to claim 1 or 2.

6. The head part has a maximum dimension in the thickness direction of 1.4 mm or more and 3.0 mm or less. The toothbrush according to claim 1 or 2.

7. In the major axis direction, the ratio of the total area of the hair implanting holes to the head area from the tip of the head part to the position of the hole edge in the hair implanting hole located on the most rear end side is 55% or more. The toothbrush according to claim 1 or 2.

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