Toothbrush

Abstract

The present invention provides a non-anchored toothbrush having sufficient bristle planting strength. The toothbrush is provided with: a bristle bundle in which a plurality of bristles are bundled; and a head part which has, on the hair planting surface located on the front surface side in the thickness direction, hair planting holes which are formed so as to be recessed toward the back surface side and into which a hair bundle is planted, and which is characterized in that: when one or more of the hair planting holes having the same shape and the same size when viewed from the front side are set as one group; the bristle bundles in at least one group have, on one end side in the longitudinal direction, a solidified part in which a plurality of bristles are melted and solidified, and the head part has a fixed part that protrudes from the inner surface of the bristle implanting hole and is positioned on the front surface side of the solidified part. In the direction in which the distance in the long-axis direction of the bristle planting hole at the center position of the range in which the bristle planting hole has the maximum size in the short-axis direction parallel to the bristle planting surface and orthogonal to the long-axis direction is shorter than the distance in the short-axis direction of the bristle planting hole at the center position of the range in which the bristle planting hole has the maximum size in the long-axis direction In a cross-section in the width direction, the cured portion has a flat shape in which the maximum dimension in the width direction is larger than the maximum dimension in the thickness direction.

Description

toothbrush Technical Field

[0001] This invention relates to a toothbrush.

[0002] This application claims priority based on Japanese Patent Application No. 2023-206816 filed in Japan on December 7, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] In recent years, instead of using flat wires to attach folded bristles to the head, non-anchored toothbrushes without flat wires have emerged, offering a wide variety of sizes. These toothbrushes aim to differentiate themselves by utilizing the unique bristle shape and brush shape of non-anchored brushes, resulting in superior feel and appearance, thus securing a competitive advantage.

[0004] As a non-anchored toothbrush, there is a known PTt (Pressure Temperature Time) type toothbrush, which uses heat to melt one side of the bristle bundle along its length to create a heated ball. After inserting the heated ball into the bristle implantation hole formed in the head, the bristle bundle is fixed to the head by applying heat and pressure (e.g., Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2018 / 177594 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In the toothbrush disclosed in Patent Document 1, since the heating ball is spherical, the cross-sectional shape of the heating ball inserted into the hair implantation hole near the inner wall of the hair implantation hole is close to the vertical direction of the tangent at the contact point with the upper wall that prevents the hair bundle from falling out. Therefore, it is difficult to ensure sufficient hair implantation strength.

[0010] The present invention was made with regard to the aspects described above, and its object is to provide a non-anchored toothbrush with sufficient bristle strength.

[0011] Solution for solving the problem

[0012] The present invention has the following aspects.

[0013] [1] A toothbrush comprising: a bristle bundle consisting of a plurality of bristles; and a head disposed at the front end of a handle portion extending in the longitudinal axis direction, wherein the bristle-implanting surface on the front side in the thickness direction has bristle-implanting holes recessed towards the back side for implanting the bristle bundles, wherein when one or more bristle-implanting holes of the same shape and size are grouped together when viewed from the front, at least one of the bristle bundles in the group has a solidified portion formed by melting and solidifying a plurality of bristles at one end in the longitudinal direction, and the head has an inner surface of the bristle-implanting holes. The fixing portion, which protrudes and is located on the front side of the curing portion, has a cross-section in which the shorter of the distance in the direction of the long axis of the hair-planting hole at the center of the range where the hair-planting hole is at its maximum size in the short axis direction (parallel to the hair-planting surface and orthogonal to the long axis direction) and the distance in the direction of the short axis of the hair-planting hole at the center of the range where the hair-planting hole is at its maximum size in the long axis direction is set in the width direction. In this cross-section, the curing portion is a flat shape in which the maximum size in the width direction is larger than the maximum size in the thickness direction.

[0014] [2] According to the toothbrush described in [1], the cross-sectional shape of the curing part is a roughly semi-circular shape that bulges out toward the back side.

[0015] [3] According to the toothbrush of [1] or [2], the toothbrush has a protrusion disposed on the front side of the fixing part, extending toward the front side toward the inside of the bristle hole, and the tip of the protrusion contacts the bristles at a position closer to the front side than the bristle surface.

[0016] [4] According to any one of [1] to [3], the distance from the position of the solidified portion, which is the largest in the width direction, to the bristle-planting surface is shorter than the distance from the position of the solidified portion, which is the largest in the width direction, to the side of the head opposite to the bristle-planting surface in the thickness direction.

[0017] [5] The toothbrush according to any one of [1] to [4], wherein the position of the bottom of the bristle hole in the thickness direction varies depending on the maximum dimension of the width direction of the solidified portion.

[0018] [6] The toothbrush according to any one of [1] to [5], wherein the maximum dimension of the head in the thickness direction is more than 1.4 mm and less than 3.0 mm.

[0019] [7] The toothbrush according to any one of [1] to [6], wherein the total area of ​​the bristle pores is 55% or more relative to the head area from the front end of the head to the position of the edge of the bristle pores located on the rear end side in the long axis direction.

[0020] The effects of the invention

[0021] In this invention, a non-anchored toothbrush with sufficient bristle strength can be provided. Attached Figure Description

[0022] Figure 1 is a diagram illustrating an embodiment of the present invention, and is a partial front view of the toothbrush 1 of the first embodiment.

[0023] Figure 2 is a sectional view along line II-II of Figure 1.

[0024] Figure 3 is a cross-sectional view of the head 3 before the heat compression treatment along the width direction.

[0025] Figure 4 is a partial cross-sectional view of the head 3, which has a spherical cross-section representing the cured section.

[0026] Figure 5 is a partial cross-sectional view of the head 3, which has a flat cross-section of the cured section.

[0027] Figure 6 is a partial cross-sectional view along the width direction showing the head 3 after heat compression treatment.

[0028] Figure 7 is a cross-sectional view of the head 3 of the toothbrush 1 according to the second embodiment. Detailed Implementation

[0029] Hereinafter, embodiments of the toothbrush of the present invention will be described with reference to Figures 1 to 7.

[0030] Furthermore, the following embodiments illustrate one aspect of the present invention and do not limit the invention; modifications can be made freely within the scope of the technical concept of the present invention. Additionally, in the following drawings, the scale, quantity, etc., of each structure are different from the actual structure for ease of understanding.

[0031] [First Implementation Method]

[0032] Figure 1 is a partial front view of the toothbrush 1 according to the first embodiment. Figure 2 is a cross-sectional view along line II-II of Figure 1.

[0033] As shown in Figure 1, the toothbrush 1 has a head 3 and a handle 4 connected to the head 3. The head 3 is located at the front end of the handle 4, which extends along its long axis (left-right direction in Figure 1). The head 3 is provided with bristle bundles 12 and 22.

[0034] The materials of the head 3 and the handle 4 are not particularly limited, but polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, etc. are preferred.

[0035] In the following description, the normal direction of the flocked surface 2 (the direction orthogonal to the paper in Figure 1, and the up-down direction in Figures 2 and 3) will be referred to as the thickness direction, and the direction parallel to the flocked surface 2 and orthogonal to the major axis (the up-down direction in Figure 1, and the left-right direction in Figure 3) will be referred to as the minor axis direction. Furthermore, the side in the thickness direction opposite to the flocked surface 2 will be referred to as the front side, and the side opposite the front side will be referred to as the back side.

[0036] When viewed from the front, the head 3 is a rectangular shape extending along its long axis. The head 3 has a hair-planting surface 2, hair-planting holes 3A and 3B, and fixing parts 5A and 5B. The head 3 has a first hair-planting part 11 and a second hair-planting part 21.

[0037] Hair implantation hole 3A is located in the first hair implantation portion 11. Hair implantation hole 3A is formed by recessing from the hair implantation surface 2 towards the back side in the thickness direction. Hair implantation hole 3A is formed with a shape corresponding to the main view shape of the first hair implantation portion 11. Hair implantation hole 3B is located in the second hair implantation portion 21. Hair implantation hole 3B is formed by recessing from the hair implantation surface 2 towards the back side in the thickness direction. Hair implantation hole 3B is formed with a shape corresponding to the main view shape of the second hair implantation portion 21.

[0038] The main view shape of the first hair implantation part 11 and the second hair implantation part 21 is not particularly limited. For example, one or more shapes such as circle, ellipse, arc, ring, straight line, polygon, and polygonal frame can be provided.

[0039] As shown in Figure 1, since the main view shape of the first hair implantation part 11 and the second hair implantation part 21 is circular, the main view shape of the hair implantation holes 3A and 3B is also circular.

[0040] In the non-anchored toothbrush 1, the bristle implantation holes 3A and 3B can be irregularly shaped in the cross-section along the long axis and the cross-section along the short axis, and the way they are affected by the force of brushing, etc., varies depending on the location of the cross-section.

[0041] Therefore, in head 3, for the hair implantation hole 3A for implanting hair tufts, the shorter of the two distances (the shorter distance) between the distance along the major axis and the distance along the minor axis of the hair implantation hole 3A at the center of the range where the hair implantation hole 3A is at its maximum size in the minor axis direction, will be described as the width direction. The same consideration applies to hair implantation hole 3B. Furthermore, when the main view shape of hair implantation holes 3A and 3B is a perfect circle and the distance along the major axis is the same as the distance along the minor axis, the minor axis direction will be used as the width direction.

[0042] In this case, the direction with the shorter distance in the width direction (the direction with a small distance) is easily affected by forces generated by brushing, etc., so this is important when considering the riveting structure. Furthermore, the curing portions 14 and 24, described later as part of the heat-forming ball, tend to have their thickness and width maximized at the central portion in the width direction of the pores 3A and 3B. Therefore, the setting of the width direction is important when considering the riveting structure.

[0043] In this embodiment, the main view shape of the hair implantation holes 3A and 3B is circular, so the maximum distance in the cross section along the long axis is the same as the maximum distance in the cross section along the short axis.

[0044] Figure 3 is a cross-sectional view of the head 3 along its width. The head 3 shown in Figure 3 is a preform before the heat compression treatment described later. That is, as shown in Figure 3, the head 3 is formed in advance, for example, by injection molding. The tufting holes 3A in the head 3 of the preform extend toward the back side with a certain diameter. In addition, the second tufting part 21 differs from the first tufting part 11 only in size, but has the same cross-sectional shape. Therefore, only appropriate reference numerals are shown in the figures, and the description of the second tufting part 21 is sometimes omitted or simplified.

[0045] The first hair-embedded parts 11 are arranged on both outer sides in the short axis direction. The first hair-embedded parts 11 adjacent to each other in the long axis direction are at the same position in the short axis direction, and multiple of them are arranged at intervals in the long axis direction (4 in each column in Figure 1).

[0046] The second hair-planting part 21 is arranged on the central side in the short axis direction compared to the first hair-planting part 11.

[0047] Multiple second hair-embedded sections 21 are arranged at intervals along the long axis (14 in Figure 1). In each row of second hair-embedded sections 21, two sections that are in the same position along the long axis and are spaced apart along the short axis, and one section that is adjacent along the long axis and is in a different position along the short axis, are arranged alternately along the long axis.

[0048] In addition, in this embodiment, when one or more hair-implanting holes 3A and 3B that are the same shape and size when viewed from the front are grouped together, the hair tufts in at least one group will be described.

[0049] As shown in Figure 2, the first bristle-planting section 11 has bristle bundles 12. The bristle bundles 12 have a plurality of bundled bristles 13 and a curing section 14. The plurality of bristles 13 are bundled into a predetermined shape in the front view. In this embodiment, the plurality of bristles 13 are bundled into a circular shape in the front view.

[0050] The second bristle-planting section 21 has bristle bundles 22. The bristle bundles 22 have a plurality of bundled bristles 23 and a curing section 24. The plurality of bristles 23 are bundled into a predetermined shape in the front view. In this embodiment, the plurality of bristles 23 are bundled into a circular shape in the front view.

[0051] There are no specific limitations on the materials of brush bristles 13 and 23. Examples include polyamide (e.g., 6-12 nylon, 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate), and polyolefin (e.g., polypropylene).

[0052] A curing portion 14 is provided on the back side of one end of the hair tuft 12 along its length. The curing portion 14 is melted and solidified by heating the back side portion of the hair tuft 12 along its length using a heater or the like, forming a spherical shape. The end of the curing portion 14 on the back side contacts the bottom 3C of the hair implantation hole 3A. As shown in FIG3, the curing portion 14 is a flat shape with a maximum dimension L11 in the width direction larger than the maximum dimension L12 in the thickness direction. The cross-sectional shape of the curing portion 14 in the width direction is a roughly semi-circular shape bulging towards the back side. The above-described shape of the curing portion 14 is maintained after the heat compression treatment described later.

[0053] The approximate semicircle is defined as follows: if the distance from the position in the thickness direction where the distance in the width direction of the cured part 14 is the maximum dimension L11 to the end of the back side where the distance in the width direction of the back side is the minimum is set as L1, and the distance from the position in the thickness direction where the distance in the width direction of the width direction is the maximum dimension L11 to the end of the front side where the distance in the width direction of the front side is the minimum is set as L2, then the value represented by L2 / L1 is 0.5 or less.

[0054] As shown in Figure 3, the maximum dimension L11 in the width direction of the curing part 14 is smaller than the diameter D1 of the tufting hole 3A in the head 3 of the preform. The ends of the curing part 14 and the plurality of bristles 13 on the back side are inserted into the tufting hole 3A in the head 3 of the preform from the front side and contact the bottom 3C.

[0055] A curing portion 24 is provided on the back side of one end of the hair tuft 22 along its length. The curing portion 24 is melted and solidified by heating the back side portion of the hair tuft 22 along its length using a heater or the like, forming a spherical shape. The end of the curing portion 24 on the back side contacts the bottom 3D of the hair implantation hole 3B. The curing portion 24 is a flat shape with a maximum dimension L21 in the width direction larger than the maximum dimension L22 in the thickness direction. The cross-sectional shape of the curing portion 24 in the width direction is a roughly semi-circular shape bulging towards the back side. The above-described shape of the curing portion 24 is maintained after the heat compression treatment described later.

[0056] The maximum dimension L21 of the curing part 24 in the width direction is smaller than the diameter D2 of the tufting hole 3A of the head 3 of the preform. The ends of the curing part 24 and the plurality of bristles 23 on the back side are inserted from the front side into the tufting hole 3B of the head 3 of the preform and contact the bottom 3D.

[0057] Furthermore, by making the cured portions 14 and 24 into approximately semi-circular shapes bulging towards the back side in cross-section, compared to the case where the cured portions 14 and 24 are approximately circular, the cured portions 14 and 24 can be made thinner in the thickness direction, thus contributing to the thinning of the head 3. Moreover, by making the head 3 thinner, riveting can be performed near the flocking surface 2 during the heat compression process described later, effectively ensuring the flocking strength.

[0058] Furthermore, by making the cross-sectional shape of the curing part 14 and the curing part 24 into a roughly semi-circular shape that bulges outward toward the back side, the protrusion of the curing part 14 and the curing part 24 that protrude outward in the width direction from the bristles 13 and 23 can be increased, which can make the bristle bundles 12 and 22 fixed by the fixing parts 5A and 5B more secure.

[0059] Furthermore, from the viewpoint of hair removal during brushing, the diameter of the hair implantation holes 3A and 3B is preferably 1.5 mm or more, because this results in a larger contact area with the curing portions 14 and 24. Additionally, from the viewpoint of ensuring the hair implantation strength of the curing portions 14 and 24, the aforementioned distance L1 is preferably 0.5 mm or more and 1.8 mm or less.

[0060] In addition, in the head 3, since the outermost hair bundles 12 and 22 have a large physical load related to hair removal during brushing, it is preferable that the cross-sectional shape of the curing part 14 and 24 in the outermost hair implantation holes 3A and 3B satisfies the approximately semi-circular shape bulging towards the back side.

[0061] The fixing part 5A protrudes from the inner surface of the hair implantation hole 3A and is located on the front side of the curing part 14. The fixing part 5A protrudes from the inner surface along the entire circumference of the hair implantation hole 3A and is located on the front side of the curing part 14. By positioning the fixing part 5A on the front side of the curing part 14, the curing part 14 can be kept in contact with the bottom 3C of the hair implantation hole 3A in the thickness direction. Therefore, unwanted movement of the hair tuft 12 in the thickness direction can be suppressed, which helps to ensure hair implantation strength and stabilization.

[0062] The fixing part 5B protrudes from the inner surface of the hair implantation hole 3B and is located on the front side of the curing part 24. The fixing part 5B protrudes from the inner surface along the entire circumference of the hair implantation hole 3B and is located on the front side of the curing part 24. By positioning the fixing part 5B on the front side of the curing part 24, the curing part 24 can be kept in contact with the bottom 3D of the hair implantation hole 3B in the thickness direction. Therefore, unwanted movement of the hair tuft 22 in the thickness direction can be suppressed, which helps to ensure hair implantation strength and stabilization.

[0063] As shown in Figure 3, the toothbrush 1 with the above structure is manufactured by heating and compressing the head 3 of the preform in the thickness direction using stamping members P1 and P2, which are heated by a heater, for example, metal.

[0064] A stamping member P1 is disposed on the front side of the head 3 of the preform. The stamping member P1 engages with the front-facing surface of the head 3 of the preform from the front side. The stamping member P1 has retaining holes 91 and 92 that extend through the thickness direction. When the stamping member P1 is disposed on the front side of the head 3 of the preform, the retaining hole 91 is formed at a position opposite to the bristle implantation hole 3A in the thickness direction. The retaining hole 91 allows a plurality of bundled brush filaments 13 to pass through from the back side. The retaining hole 91 holds the plurality of bundled brush filaments 13 from the radially outward side. When the stamping member P1 is disposed on the front side of the head 3 of the preform, the retaining hole 92 is formed at a position opposite to the bristle implantation hole 3B in the thickness direction. The retaining hole 92 allows a plurality of bundled brush filaments 23 to pass through from the back side. The retaining hole 92 holds the plurality of bundled brush filaments 23 from the radially outward side.

[0065] The stamping component P2 is disposed on the back side of the head 3 of the preform. The stamping component P2 engages with the back side face of the head 3 of the preform from the back side.

[0066] When the head 3 of the preform is heated and compressed along the thickness direction, the head 3, stamping member P1, and stamping member P2 of the preform are arranged with the front side as the lower side and the back side as the upper side. The stamping member P1 is joined to the front-facing surface of the head 3 of the preform from the front side with multiple bundled brush filaments 13 penetrating through the holding holes 91, so that the curing part 14 is inserted into the tufting hole 3A and the curing part 24 is inserted into the tufting hole 3B.

[0067] Then, by pressing the heated stamping components P1 and P2 towards each other while they are heated, the resin that is heated, compressed and melted in the head 3 of the preform flows into the tufting holes 3A and 3B with lower flow pressure to perform riveting.

[0068] Therefore, as shown in Figure 2, a fixing part 5A is formed on the front side of the curing part 14 in the hair implantation hole 3A. Similarly, a fixing part 5B is formed on the front side of the curing part 24 in the hair implantation hole 3B. By forming the fixing part 5A in the hair implantation hole 3A and the fixing part 5B in the hair implantation hole 3B, a toothbrush 1 with bristle bundles 12 and 22 fixed to the brush head 3 is manufactured.

[0069] Figure 4 (Comparative Example) is a partial cross-sectional view of the head 3, which has a spherical cross-section, showing the curing sections 14 and 24.

[0070] Figure 5 is a partial cross-sectional view of the head 3, where the curing portions 14 and 24 have a flat cross-section. As shown in Figure 4, when the cross-sections of the curing portions 14 and 24 are spherical, the tangents at the positions where the front ends of the curing portions 14 and 24 contact the fixing portions 5A and 5B intersect the inner surfaces of the fixing portions 5A and 5B at an angle θ1. On the other hand, as shown in Figure 5, when the cross-sections of the curing portions 14 and 24 are flat, the tangents at the positions where the front ends of the curing portions 14 and 24 contact the fixing portions 5A and 5B intersect the inner surfaces of the fixing portions 5A and 5B at an angle θ2.

[0071] When the cross-sections of the curing parts 14 and 24 are spherical, the angle θ1 is smaller than the angle θ2. Therefore, when a force is applied to the hair bundles 12 and 22 on the front side, it is possible for the interface between the back side of the fixing parts 5A and 5B and the surface of the curing parts 14 and 24 to slip, resulting in a decrease in the hair implantation strength.

[0072] In contrast, when the cross-section is flat, the angle θ2 is larger than the angle θ1. Therefore, when the force on the front side is applied to the hair bundles 12 and 22, it is difficult for the interface between the back side of the fixing part 5A and 5B and the surface of the curing part 14 and 24 to slip, making it easy to ensure the hair implantation strength.

[0073] Figure 6 is a partial cross-sectional view along the width direction showing the head 3 after heat compression treatment.

[0074] As shown in Figure 6, the cured part 14 after heat compression treatment is as shown in Figure 3. It is a flat shape with the maximum dimension L11 in the width direction being larger than the maximum dimension L12 in the thickness direction. The cross-sectional shape in the width direction is a roughly semi-circular shape bulging outwards towards the back side.

[0075] In the curing section 14, the distance from the position in the thickness direction where the width distance is the maximum size L11 to the hair-planting surface 2 is defined as L31, and the distance from the position in the thickness direction where the maximum size L11 is obtained to the surface 6 of the head 3 on the side opposite to the hair-planting surface 2 in the thickness direction is defined as L32. When the distance L31 is longer than the distance L32, the curing section 14 contacts the inner surface of the hair-planting hole 3A at a position on the back side near the center position in the thickness direction of the head 3. In this case, the distance from the position of the hair bundle 12 in the thickness direction where the maximum size L11 is obtained to the fixing section 5A is relatively long, and the fixing of the curing section 14 may be unstable.

[0076] Therefore, by making the distance L31 shorter than the distance L32, the distance from the position of the hair bundle 12 in the thickness direction where it becomes the maximum size L11 to the fixing part 5A is shorter, which can stabilize the fixing of the curing part 14.

[0077] Similarly, as shown in Figure 3, the cured part 24 after heat compression treatment is a flat shape with the maximum dimension L21 in the width direction being larger than the maximum dimension L22 in the thickness direction, and the cross-sectional shape in the width direction is a roughly semi-circular shape bulging outwards towards the back side.

[0078] In the curing section 24, the distance from the position in the thickness direction where the distance in the width direction is the maximum dimension L21 to the bristle-planting surface 2 is set as L41, and the distance from the position in the thickness direction where this distance L41 is the distance to the back side surface 6 of the brush head 3 is set as L42.

[0079] By making the distance L41 shorter than the distance L42, the distance from the position of the hair bundle 22 in the thickness direction, which becomes the maximum size L21, to the fixing part 5B is shorter, thereby stabilizing the fixing of the curing part 24.

[0080] Furthermore, in the thickness direction of the cured portion 14, when the distance from the position with the maximum dimension L11 in the width direction to the position of the end of the front side of the cured portion 14 is set to L51, and the distance from the end of the front side of the cured portion 14 to the flocking surface 2 is set to L52, it is preferable that the distance L52 is longer than the distance L51.

[0081] By making the distance L52 longer than the distance L51, the position of the maximum dimension L11 of the distance in the width direction of the hair bundle 12 is closer to the fixing part 5A, and the resin riveted during the heat compression treatment can easily come into contact with the curing part 14 from the front side.

[0082] Therefore, the stability of the solidified part 14 inside the hair implantation hole 3A is improved, which can further stabilize the hair implantation strength.

[0083] Similarly, in the thickness direction of the cured portion 24, when the distance from the position with the maximum dimension L21 in the width direction to the position of the end of the front side of the cured portion 24 is set to L61, and the distance from the end of the front side of the cured portion 24 to the flocking surface 2 is set to L62, it is preferable that the distance L62 is longer than the distance L61.

[0084] By making the distance L62 longer than the distance L61, the position of the maximum dimension L21 of the distance in the width direction of the hair bundle 22 is closer to the fixing part 5B, and the resin riveted during the heat compression treatment can easily come into contact with the curing part 24 from the front side.

[0085] Therefore, the stability of the solidified part 24 inside the hair implantation hole 3B is improved, which can further stabilize the hair implantation strength.

[0086] Furthermore, in the curing section 14, if the distance from the end position on the back side to the surface 6 in the thickness direction is set to L71, it is preferable that the distance L71 is longer than the distance L52.

[0087] 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 is the maximum dimension L11 closer to the fixing part 5A.

[0088] Similarly, in the curing section 24, if the distance from the end position on the back side to the surface 6 in the thickness direction is set to L81, it is preferable that the distance L81 is longer than the distance L62.

[0089] By making the distance L81 longer than the distance L62, the hair bundle 22 can bring the position of the maximum dimension L21 in the width direction closer to the fixing part 5B.

[0090] The distances L51 and L61 are preferably 0 mm or more and 1.0 mm or less.

[0091] The distances L32 and L42 are preferably 0.6 mm or more and 2.6 mm or less. The distances L52 and L62 are preferably 0.2 mm or more and 1.0 mm or less.

[0092] To ensure the position of the cured portions 14 and 24 in the thickness direction, as shown in FIG2, it is preferable that the position of the bottom 3C and 3D of the tufting holes 3A and 3B in the thickness direction varies according to the maximum dimensions L11 and L21 in the width direction of the cured portions 14 and 24.

[0093] Specifically, the curing part 24, which has a smaller maximum dimension L21 in the width direction than the curing part 14, may have a smaller dimension in the thickness direction. Therefore, it is preferable to set the position of the bottom 3D in the thickness direction to be closer to the front side than the position of the bottom 3C in the thickness direction, based on the ratio or difference of the maximum dimensions L11 and L21.

[0094] By setting the position of the bottom 3C and 3D in the thickness direction according to the maximum dimensions L11 and L21 in the width direction, the position of the thickness direction of the curing parts 14 and 24, which is the maximum dimension L11 and L21, and the position of the fixing parts 5A and 5B can be optimized.

[0095] The maximum dimension of the head 3 in the thickness direction is preferably 1.4 mm or more and 3.0 mm or less, more preferably 1.6 mm or more and 2.7 mm or less.

[0096] By ensuring that the maximum thickness dimension of the head 3 is between 1.4 mm and 3.0 mm, sufficient hair implantation strength can be ensured.

[0097] The ratio of the total area of ​​the hair implantation holes 3A and 3B to the head area along the long axis from the front end of the head 3 to the edge of the hole indicated by the double-dotted line in the hair implantation hole 3B located at the rear end is preferably 55% or more.

[0098] When the total area of ​​the hair graft holes 3A and 3B is more than 55% of the head area, the amount of resin on the surface of the head 3 used for riveting is small, but even in this case, sufficient hair graft strength can be ensured.

[0099] As explained above, in the toothbrush 1 of this embodiment, fixing parts 5A and 5B are provided on the front side of the fixing parts 14 and 24 of the bristle bundles 12 and 22 inserted into the bristle holes 3A and 3B. The fixing parts 14 and 24 are flat in cross-section in the width direction, so it is not easy for them to slip at the interface with the fixing parts 5A and 5B, thus ensuring sufficient bristle strength.

[0100] [Second Implementation]

[0101] Next, the second embodiment of the toothbrush 1 will be described with reference to FIG7.

[0102] In this figure, elements that are the same as the constituent elements of the first embodiment shown in Figures 1 to 6 are labeled with the same reference numerals, and their descriptions are omitted.

[0103] Figure 7 is a cross-sectional view of the head 3 of the toothbrush 1 according to the second embodiment.

[0104] As shown in Figure 7, the head 3 has a protrusion 7 and a protrusion 8.

[0105] A protrusion 7 is provided on the front side of the fixing part 5A. The protrusion 7 is inclined in a direction that extends towards the front side as it moves inward toward the hair implantation hole 3A. The tip of the protrusion 7 contacts the bristles 13 radially outward at a position closer to the front side than the hair implantation surface 2.

[0106] A protrusion 8 is provided on the front side of the fixing part 5B. The protrusion 8 is inclined in a direction that extends towards the front side as it moves inward toward the hair implantation hole 3B. The tip of the protrusion 8 contacts the bristles 23 radially outward at a position closer to the front side than the hair implantation surface 2.

[0107] The other structures are the same as those in the first embodiment described above.

[0108] The protrusions 7 and 8 described above can be formed, for example, by making the diameters of the retaining holes 91 and 92 of the stamping member P1 larger than the diameter of the brush filaments 13 after being bundled together and the diameter of the brush filaments 23 after being bundled together, or by providing recesses (e.g., chamfered shapes) corresponding to the shapes of the protrusions 7 and 8 at the ends of the back side of the retaining holes 91 and 92.

[0109] In this embodiment, since the protrusion 7 is provided on the front side of the fixing part 5A, the contact area between the brush bristles 13 and the protrusion 7 is increased, thus increasing the friction and making it difficult for the bristle bundle 12 to move in the thickness direction. In addition, even when the end of the front side of the curing part 14 is close to the bristle-planting surface 2, the resin thickness during riveting can be ensured, thereby ensuring the bristle-planting strength.

[0110] Similarly, in this embodiment, since the protrusion 8 is provided on the front side of the fixing part 5B, the contact area between the brush bristles 23 and the protrusion 8 is increased, thus increasing the friction and making it difficult for the bristle bundle 22 to move in the thickness direction. In addition, even when the end of the front side of the curing part 24 is close to the bristle-planting surface 2, the resin thickness during riveting can be ensured, thereby ensuring the bristle-planting strength.

[0111] When the amount of protrusion of the protrusions 7 and 8 towards the front side is large, the movement of the hair bundles 12 and 22 in the brushing direction is suppressed, which affects the user experience. Therefore, the distance from the hair-planting surface 2 to the end of the protrusions 7 and 8 on the front side is preferably 0.1 mm or more and 1.0 mm or less, more preferably 0.2 mm or more and 0.5 mm or less.

[0112] Furthermore, since a significant amount of resin flows towards the protrusions 7 and 8 formed during the riveting process under heat compression, the contact between the back side of the fixing portions 5A and 5B and the curing portions 14 and 24 may be insufficient at the back side of the flocked surface 2. Therefore, the ratio of the cross-sectional area of ​​each protrusion 7 and 8 to the cross-sectional area of ​​the resin at the back side of the flocked surface 2 relative to the width of the top of the fixing portions 5A and 5B extending towards the inside of the vertical line of the flocked surface 2 is preferably 0.5:9.5 to 5:5.

[0113] In the toothbrush 1 of this embodiment, in addition to achieving the same function and effect as the first embodiment described above, the presence of protrusions 7 and 8 increases the contact area and friction, thereby further ensuring the strength of the bristle implantation.

[0114] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to these examples. The shapes, combinations, etc. of the constituent components shown in the above examples are just examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

[0115] Industrial availability

[0116] This invention can be applied to toothbrushes.

[0117] Explanation of reference numerals in the attached figures

[0118] 1. Toothbrush; 2. Bristle-embedded surface; 3. Head; 3A, 3B. Bristle-embedded holes; 4. Handle; 5A, 5B. Fixing part; 6. Surface; 7, 8. Protrusions; 12, 22. Bristle bundles; 13, 23. Brush bristles; 14, 24. Curing part.

Claims

1. A toothbrush, wherein, The toothbrush comprises: bristle bundles, which are formed by a bundle of multiple bristles; and a head, which is disposed at the front end of a handle portion extending in the long axis direction. The head has bristle implantation holes on the front side of the bristle implantation surface in the thickness direction, recessed towards the back side for implanting the bristle bundles. When one or more bristle implantation holes of the same shape and size are grouped together when viewed from the front, at least one bristle bundle in the group has a solidified portion formed by melting and solidifying multiple bristles at one end in the length direction. The head has a fixing portion protruding from the inner surface of the bristle implantation hole and located on the front side of the solidified portion. In a cross-section where the shorter of the distance in the long axis direction of the bristle implantation hole at the center of the range where the bristle implantation hole is at its maximum size in the short axis direction (parallel to the bristle implantation surface and orthogonal to the long axis direction) and the distance in the short axis direction of the bristle implantation hole at the center of the range where the bristle implantation hole is at its maximum size in the long axis direction is taken as the width direction, the solidified portion is a flat shape whose maximum size in the width direction is larger than its maximum size in the thickness direction.

2. The toothbrush according to claim 1, wherein, The cross-sectional shape of the cured part is a roughly semi-circular shape that bulges out toward the back side.

3. The toothbrush according to claim 1 or 2, wherein, The toothbrush has a protrusion disposed on the front side of the fixing part, extending toward the front side towards the inside of the bristle hole, and the tip of the protrusion contacts the bristles at a position closer to the front side than the bristle surface.

4. The toothbrush according to claim 1 or 2, wherein, The distance from the position of the cured portion, which is the largest in the width direction, in the thickness direction, to the hair-planting surface is shorter than the distance from the position of the cured portion, which is the largest in the width direction, in the thickness direction, to the side of the head opposite to the hair-planting surface in the thickness direction.

5. The toothbrush according to claim 1 or 2, wherein, The position of the bottom of the pore in the thickness direction varies depending on the maximum dimension of the cured portion in the width direction.

6. The toothbrush according to claim 1 or 2, wherein, The maximum dimension of the head in the thickness direction is more than 1.4 mm and less than 3.0 mm.

7. The toothbrush according to claim 1 or 2, wherein, The total area of ​​the hair implantation holes is more than 55% of the head area along the long axis from the front end of the head to the edge of the hair implantation holes located at the rear end.

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