toothbrush

Abstract

The objective of the present invention is to provide a toothbrush with which there is no restriction to the direction in which filaments flex during brushing, and with which the feeling of contact with the gums and the sense of cleaning can be improved. This toothbrush is provided with a brush portion comprising a plurality of filaments, a head portion having the brush portion on one surface side, a handle portion disposed at the rear end side of the head portion, and a neck portion connecting the head portion and the handle portion, wherein: the filaments have at least two branched bristles on the tip end side; the cross-sectional area of each filament in a width direction intersecting the length direction thereof decreases continuously from the root toward the tip end; and the tip ends of the at least two branched bristles are positioned inward, in the width direction, of the outer peripheral edge of the root of the filament.

Description

[Technical field]

[0001] The present invention relates to a toothbrush. This application claims priority based on Japanese Patent Application No. 2019-237281, filed on December 26, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, one-piece toothbrushes use a mold to create the filaments, which means that each filament is thicker than the bristles used in regular toothbrushes, and there is a limit to the number of filaments that can be placed in the head. This results in sparse bristles, making it difficult to ensure a sufficient cleaning experience.

[0003] In response to this issue, it is possible to improve the cleaning experience by hardening the resin and increasing the rigidity of the filament; however, this makes it difficult to improve the cleaning experience in gaps such as between the teeth and around the neck of the teeth, as the filament itself becomes less flexible, and there is also the problem that the comfort on the gums is reduced.

[0004] To solve these problems, a filament with a tip branched into two has been proposed. For example, in Patent Document 1, the filament is shaped so that the tips of the two branched bristles are positioned on the outer periphery of the base side in the head surface direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 090795 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of the filament shape of Patent Document 1, a part of the outer peripheral surface is a surface perpendicular to the bristle implantation surface, and the cross-sectional shape in the width direction intersecting the length direction of each branched hair is triangular, and further, the positions of the tips of the two branched hairs are on the outer peripheral position on the root side in the head surface direction. Therefore, there is a problem that anisotropy occurs in the bending state of the filament during brushing, and the bending direction is limited. As a result, the bending state of the filament becomes uneven, and it is not possible to sufficiently improve the contact feeling on the gums and the cleaning feeling.

[0007] One aspect of the present invention has been developed in consideration of the problems with the prior art described above, and aims to provide a toothbrush that is not limited in the direction in which the filaments bend when brushing, and that can improve the comfort of the filaments against the gums and the cleaning experience. [Means for solving the problem]

[0008] In one form of toothbrush of the present invention, the toothbrush comprises a brush portion consisting of a plurality of filaments, a head portion having the brush portion on one side, a handle portion arranged rearward of the head portion, and a neck portion connecting the head portion and the handle portion, wherein the filament has two or more branched bristles on the tip side, the cross-sectional area in the width direction intersecting the longitudinal direction of the filament decreases continuously from the base to the tip, and each tip of the two or more branched bristles is located inside in the width direction relative to the outer peripheral edge of the base of the filament.

[0009] In the toothbrush according to one aspect of the present invention, the cross-sectional shape of the filament may be configured to be symmetrical with respect to a minor axis and a major axis that intersect with each other.

[0010] In the toothbrush according to one aspect of the present invention, the cross-sectional shape of the base of the filament may be configured to have one or more recesses.

[0011] In the toothbrush of one aspect of the present invention, the filament may have, on a side surface thereof, one or more grooves that continue in the length direction from the base to a branch start point.

[0012] In the toothbrush of one aspect of the present invention, the distance between the tips of two branched bristles of one filament may be within a range of 51 to 99% of the maximum major axis width W1 of the base.

[0013] In one embodiment of the toothbrush of the present invention, the toothbrush may have a plurality of outer filaments arranged on the outermost circumference of the brush portion, and a plurality of inner filaments having shorter bristles than the outer filaments and arranged more inward than the outer filaments, and may be configured to have a step of at least 1 mm between the tip of the outer filaments and the tip of the inner filaments.

[0014] In one form of the toothbrush of the present invention, the toothbrush may have a plurality of central filaments arranged in a width direction intersecting the length direction of the head portion, dividing the arrangement area of ​​the inner filament into multiple parts in the length direction, and the bristle length of the central filaments may be equal to the bristle length of the outer filaments. Effect of the Invention

[0015] According to the present invention, it is possible to provide a toothbrush that has no restriction on the direction in which the filaments bend during brushing, and that can sufficiently improve the comfort against the gums and the cleaning sensation. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a perspective view showing the overall shape of a toothbrush according to a first embodiment. [Diagram 2] FIG. 2 is a top view showing the shape of the head portion of the toothbrush according to the first embodiment. [Diagram 3] FIG. 3 is a side view showing the shape of the head portion of the toothbrush of the first embodiment. [Figure 4]FIG. 4 is a front view showing the shape of the head portion of the toothbrush according to the first embodiment. [Diagram 5] FIG. 5 is a perspective view showing the shape of a filament in the first embodiment. [Figure 6] FIG. 6 is a side view showing the shape of the filament in the first embodiment. [Figure 7] FIG. 7 is a top view showing the shape of the filament according to the first embodiment, as viewed from the implanted surface side. [Figure 8] FIG. 8 is a cross-sectional view showing the shape of the base of the filament in the first embodiment. [Figure 9] FIG. 9 is a perspective view showing the configuration of a brush head of a toothbrush according to the second embodiment. [Figure 10] FIG. 10 is a top view of the brush part of the toothbrush of the second embodiment, seen from the bristles side. [Figure 11] FIG. 11 is a cross-sectional view of the toothbrush shown in FIG. 10 taken along the line BB. [Figure 12] FIG. 12 is a diagram showing an example of an arrangement of filaments constituting the brush portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [First embodiment] The toothbrush according to the first embodiment of the present invention will now be described. In the drawings, the dimensions of different components may be shown on different scales in order to make the components easier to see.

[0018] 1, toothbrush 10 of this embodiment includes a brush section 16 and a handle body 14 having a head section 11, a neck section 12, and a handle section 13. Toothbrush 10 of this embodiment includes brush section 16 that is integrally molded with head section 11 by injection molding handle body 14.

[0019] (Handle body) The handle body 14 comprises a head portion 11 having a brush portion 16 on one side, a handle portion 13 disposed rearward of the head portion 11, and a neck portion 12 connecting the head portion 11 and the handle portion 13, and the entire body including the head portion 11, the neck portion 12 and the handle portion 13 are integrally molded in a long shape. The handle body 14 is obtained, for example, by injection molding using a resin as a material.

[0020] Examples of materials for the handle body 14 include polypropylene resin (PP), polyacetal resin (POM), polystyrene resin (PS), polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), acrylonitrile butadiene styrene resin (ABS), polyarylate resin, polycarbonate resin, acrylonitrile styrene resin (AS), polyester resin (PCTA), etc. Among these, PP, POM, and PBT are preferred, and PP and POM are more preferred, in terms of high strength and excellent moldability. Furthermore, PP is particularly preferred as the material for the handle body, in terms of being able to obtain the effects of the present invention at a lower cost.

[0021] The above resins may be used alone or in combination of two or more.

[0022] The flexural modulus of the material of the handle body 14 is preferably 1200 to 3000 MPa, and more preferably 1500 to 3000 MPa. When the flexural modulus of the material of the handle body 14 is within the above range, the amount of deflection of the head portion 11 can be set to an appropriate value, leading to improved oral cavity cleaning power, operability, and improved usability for the user. The flexural modulus of the material of the handle body is measured in accordance with JIS K7171.

[0023] The overall length of the handle body 14 can be determined taking into consideration the operability in the user's oral cavity, and is, for example, 150 to 200 mm.

[0024] (Head section) The head portion 11 is a portion to be inserted into the oral cavity, and has a substantially rectangular shape with rounded corners. The shape and size of the head portion 11 may be such that it is easy to brush the oral cavity, and the shape is not particularly limited. For example, the head portion 11 may have a shape that gradually narrows from the base end to the tip end.

[0025] (Brush part) The brush portion 16 is provided on one surface (hereinafter, bristle surface) 11a of the head portion 11 of the handle body 14, and has a plurality of bristles (hereinafter, filaments 15) of the same shape. The brush portion 16 is molded by injection molding integrally with the head portion 11 of the handle body 14, which is separately prepared. Note that the present embodiment is not limited to this, and a cap-type embodiment in which a separately molded brush portion is fitted to the handle portion for use may also be used.

[0026] As shown in FIG. 2, the filaments 15 constituting the brush part 16 are arranged in a lattice arrangement in which they are arranged linearly in the width direction (Y direction) and the length direction (X direction) of the head part 11. As shown in FIG. 2, the first region R1 located at the center in the width direction of the head part 11 has 22 rows in the length direction and 6 rows in the width direction, totaling 132 filaments. In addition, a pair of second regions R2 located on both sides of the first region R1 in the width direction have 18 rows in the length direction and 2 rows in the width direction, totaling 36 filaments 15. The first region R1 has two more rows of filaments 15 on each side in the length direction than the second region R2, and by reducing the number of filaments 15 in the width direction at the front and rear ends of the head part 11, the brushing performance in the oral cavity is improved.

[0027] In this embodiment, the brush profile of the brush portion 16 is flat. In this embodiment, all the filaments 15 constituting the brush portion 16 have the same shape, the same bristle length (height in the Z direction from the bristle implantation surface 11a), and the bristle tips are uniform. Therefore, the bristle tips of each branched bristle 15A are uniform, forming a flat brush shape.

[0028] In this embodiment, in the plurality of filaments 15 arranged in a lattice pattern, the gap between the roots 15b of adjacent filaments 15 on the implanted surface 11a side in the length direction and width direction (the minimum distance between filaments) is preferably 0.1 mm or more, more preferably 0.15 mm or more. Also, it is preferably 0.5 mm or less, more preferably 0.3 mm or less, and particularly preferably 0.25 mm or less. It is preferably 0.1 to 0.5 mm, more preferably 0.15 to 0.3 mm, and particularly preferably 0.15 to 0.25 mm. Regarding the aforementioned "gaps A between the roots 15b of the filaments 15 on the implanted surface 11a side (FIGS. 2 and 3)", it is preferable that the portions having gaps A of 0.1 mm or more account for 50 to 100%, and more preferably 75 to 100% or more, of the total number of gaps A in all filaments 15 provided on the implanted surface 11a.

[0029] The brush portion 16 is made of a soft resin, and for example, a soft resin having a JIS K 6253 Shore A hardness of 90 or more can be used. Specifically, a soft resin having a Shore hardness A of 90 or more and a Shore hardness D of 75 or less is preferable, and a soft resin having a Shore hardness D of 66 is more preferable. As the soft resin constituting the brush molded body, various elastomers can be used, but polyurethane is preferable.

[0030] In this embodiment, the filaments 15 are not limited to being arranged in a lattice pattern, but may be arranged in a staggered pattern.

[0031] (filament) Next, the shape of the filament 15 will be described in detail.

[0032] 5, the filament 15 of this embodiment is integrally molded with the head portion 11 by injection molding, and has two branched hairs 15A at the tip side. The cross-sectional area of ​​the filament 15 in the XY plane intersecting the longitudinal direction (Z direction) continuously decreases from the base 15b toward each of the tips 15a of the two branched hairs 15A, and the filament 15 is tapered.

[0033] In this embodiment, since the tip of the filament is split into two, the thickness of each branched bristle 15A is half or less of the thickness of the base 15J (see FIG. 6) side. Therefore, the tip of the branched bristle 15A can easily enter narrow gaps such as interdental areas and cervical areas of teeth compared to the tip of a non-branched filament. The thickness of the base 15J is preferably 0.4 to 1.3 mm, more preferably 0.6 to 1.2 mm, and even more preferably 0.7 to 1.1 mm. The "thickness of base 15J" is defined as the diameter of the circumscribed circle of the outer periphery of root 15b.

[0034] As shown in FIG. 6, the filament 15 of this embodiment has a two-stage tapered surface, with a slightly different angle between the gradient of the side 15j of the base 15J from the root 15b to the branching start position P and the gradient of the side 15k of the branched hair 15A from the branching start position P to the tip. The thickness at the branch start position P is preferably 0.3 to 1.2 mm, more preferably 0.5 to 1.1 mm, and even more preferably 0.6 to 1.0 mm. The "thickness of the branch start position P" is defined as the diameter of the circumscribing circle of the outer periphery of the branch start position P. The "thickness at branch start position P" is smaller than the "thickness at base 15J", forming a two-stage tapered surface. The ratio of the thickness at branch start position P to the thickness at base 15J is preferably 60 to 99%, more preferably 70 to 95%, even more preferably 75 to 90%, and particularly preferably 75 to 85%.

[0035] 6, the branch start position P is located at approximately the center in the length direction of the filament 15. Although it depends on the number of branch hairs 15A that one filament 15 has, if the length of the branch hair 15A (hereinafter referred to as the branch length) is too long, it will bend too much and interfere with other branch hairs 15A, so the branch length L2 is preferably set within a range of 20 to 80% of the total hair length (hereinafter referred to as the filament length) L1 of the filament 15, more preferably 30 to 70%, and even more preferably 40 to 60%. Here, the branch length L2 is the dimension from the branch start position P to the tip 15a.

[0036] In the filament 15 having two branch hairs 15A, the length L2 of the branch hair 15A is most preferably 50% of the filament length L1. The length L2 of the branch hair 15A is preferably 2.5 to 8.5 mm, more preferably 3.5 to 7.5 mm, and further preferably 4.5 to 6.5 mm. The filament length L1 is preferably from 6 to 14 mm, more preferably from 7 to 13 mm, and further preferably from 8 to 12 mm.

[0037] 7, the shape of the filament 15 is linearly symmetrical with respect to a minor axis X and a major axis Y that intersect with each other. The minor axis X of the filament 15 is parallel to the X direction, and the major axis Y of the filament 15 is parallel to the Y direction.

[0038] As shown in FIG. 8, the cross-sectional shape of the base 15b side of the filament 15 in the XY plane is such that the minimum minor axis width W2 at the center of the maximum major axis width W1 is narrowest, and the width in the minor axis direction continuously increases from the branch start position P to both ends in the Y direction.

[0039] In this embodiment, the maximum major axis width W1 at the base 15b is, for example, preferably in the range of 0.4 to 1.2 mm, more preferably in the range of 0.5 to 1.1 mm, further preferably in the range of 0.6 to 1.0 mm, and particularly preferably in the range of 0.7 to 0.9 mm. The minimum minor axis width W2 is, for example, preferably within the range of 0.2 to 0.6 mm, more preferably 0.2 to 0.5 mm, and particularly preferably 0.25 to 0.4 mm. The maximum minor axis width W3 is, for example, preferably within the range of 0.6 to 1.0 mm, more preferably 0.6 to 0.9 mm, and particularly preferably 0.7 to 0.9 mm.

[0040] As shown in Fig. 8, apexes Q, Q are present near the center of a pair of short-axis side surfaces 15f, 15f of the base 15J. The cross-sectional shape of the filament 15 is formed by a pair of grooves 19, 19 and a pair of tapered surfaces 19d, 19d each of which is inclined inward in the Y direction from each apex Q on the short-axis side surface 15f, 15f of the base 15J to a pair of corners 15g, 15g on both sides of each groove 19, 19. Here, each short-axis side surface 15f of the base 15J is composed of a pair of tapered surfaces 19d that are symmetrical in the X direction.

[0041] Furthermore, the distance W4 (FIG. 8) between a pair of corners 15g located on both sides of each groove 19 is preferably in the range of 0.5 to 1.1 mm, more preferably in the range of 0.5 to 0.9 mm, and even more preferably in the range of 0.55 to 0.65 mm.

[0042] 8, in the XY cross section of the base 15b, a pair of long-axis side surfaces 15e along the long axis Y of the filament 15 are recessed inward so that the central portions of the width W1 along the long axis (hereinafter referred to as the long-axis width) approach each other. The filament 15 has a pair of grooves 19 each formed in a recessed shape by the pair of long-axis side surfaces 15e.

[0043] The cross-sectional shape of groove 19, i.e., the transverse cross-sectional shape of groove 19 along the XY plane of filament 15, is substantially triangular. Groove 19 has a pair of faces 19c that taper from bottom 19b toward both outer sides in the Y direction relative to the X direction. As shown in Fig. 7, the pair of grooves 19 have bottoms 19b that are deepest in cross-sectional view facing each other at the center of the major axis width, and each widens toward the outside in the minor axis direction.

[0044] The pair of grooves 19 are continuously formed in the Z direction from the base 15b to the branch start position P. At a given position in the height direction of the filament 15, the cross-sectional areas of the grooves 19 in the XY plane may be equal to each other. As shown in Figures 7 and 8, the XY cross-sectional areas of the pair of grooves 19 each continuously decrease from the base 15b toward the branch start position P, and the groove 19 on the base 15b side may be the deepest.

[0045] The depth G of each groove 19 at the base 15b (for example, the depth G of one groove 19 in the +X direction in Figure 8) can be expressed by the following formula (1) and is preferably 10 to 45%, more preferably 20 to 40%, and even more preferably 25 to 35%. 100x{(W3-W2) / W3} / 2…(1)

[0046] The length of the depth G of each groove portion 19 at the base 15b can be expressed as (W3-W2) / 2, and is preferably 0.1 to 0.5 mm, more preferably 0.15 to 0.4 mm, and further preferably 0.2 to 0.3 mm.

[0047] The extent of the depth G and the length of the other groove portion 19 located in the -X direction can also be calculated in a similar manner. In this embodiment, it is preferable that the extent of the depth G and the length of each groove portion 19 existing in the +X direction and the -X direction are equal to each other.

[0048] The bottoms 19b of the pair of grooves 19 gradually approach each other from the base 15b side toward the branch start position P, and communicate with each other in the minor axis direction on the tip side of the branch start position P. As a result, two branched hairs 15A are formed at the tip side of the filament 15.

[0049] As described above, the shape of the filament 15 is linearly symmetrical with respect to the major axis Y passing through the center of W3. Therefore, when the filament 15 is viewed from the side as shown in FIG. 6, the position of the tip 15a of each branched hair 15A is located approximately in the center of the minimum minor axis width W2 of the filament 15.

[0050] On the other hand, as shown in FIG. 7, when the filament 15 is viewed from above, the position of each tip 15a of each branched hair 15A is located inside in the X direction and Y direction from the outer circumferential edge 15b1 of the base 15b of the filament 15, and is further located inside in the X direction and Y direction from the outer circumferential edge 15b2 of the branch start position P.

[0051] The spacing (distance) W5 (FIG. 7) between the tips 15a of two branched hairs 15A in one filament 15 is preferably within the range of 51 to 99% of the widthwise length W1 along the major axis Y of the base 15b (hereinafter referred to as the major axis width), more preferably 55 to 80%, and particularly preferably 60 to 70%.

[0052] The distance W5 between the tips 15a of two branched hairs 15A in one filament is preferably 0.3 to 1.0 mm, more preferably 0.4 to 0.8 mm, and particularly preferably 0.45 to 0.6 mm. The same applies when there are two or more branched hairs. As shown in Fig. 5, the branching starts when the minimum minor axis width W2 is 0 mm at the branching start position P. Here, the branching start positions P of the two branched hairs 15A are aligned, and their roots are connected at a point. In this case, the distance between the roots of the two branched hairs 15A at the branching start position P is 0 mm. For example, the branching may start without the minimum minor axis width W2 being 0 mm. In this case, the distance between the roots of the two branched hairs 15A at the branching start position P is preferably greater than 0 mm and less than 0.3 mm. In this way, the distance between the two branched hairs 15A at the branch start position P is preferably 0 to 0.3 mm.

[0053] The tip diameter at a distance of 0.1 mm from the tip of the branched hair 15A is preferably within a range of 0.02 to 0.5 mm, more preferably 0.02 to 0.4 mm, further preferably 0.02 to 0.3 mm, and particularly preferably 0.02 to 0.2 mm.

[0054] When the branched hair 15A has an irregular shape, the tip diameter at a distance of 0.1 mm from the tip is defined as the diameter of a circumscribing circle of the outer periphery of the cross-sectional shape in an XY plane intersecting the longitudinal direction (Z direction) of the branched hair 15A.

[0055] Furthermore, the hair lengths of the two branched hairs 15A in one filament 15 (hereinafter referred to as branch lengths) may be equal to each other or may be different.

[0056] If the branch length L2 is too long relative to the filament length, it will bend too much when brushing, making it difficult to obtain a sufficient brushing feel (cleaning sensation). Conversely, if the branch length L2 is too short, it will be difficult to bend when brushing, reducing the ability to penetrate between teeth and the comfort of the brush. Therefore, by setting the branch length within the above range, the brushing feel, interdental insertion, and comfort of the brush against the gums will be improved.

[0057] A parting line L extending in the Z direction is present at the center of the minimum minor axis width W2 on the minor axis side surface 15f of the filament 15. The maximum major axis width W1 on the base 15b side of the filament 15 is greatest at the parting line L.

[0058] In the toothbrush 10 of the present embodiment, the head portion 11 and the brush portion 16 are integrally formed by injection molding the brush portion 16, and the toothbrush 10 has a plurality of filaments 15 made of soft resin. The tip side of all the filaments 15 constituting the brush portion 16 is branched into two, and when viewed from the upper side (the bristle-implanted surface 11a) of the brush portion 16, the tip 15a of each branched bristle 15A is located inside the outer circumferential edge 15b1 of the base 15b, and the shape is linearly symmetrical with respect to both the short axis X and the long axis Y. That is, all the side peripheral surfaces of the filament 15 are inclined with respect to the bristle-implanted surface 11a, and there is no part perpendicular to the bristle-implanted surface 11a. Therefore, there is no restriction on the bending direction of each branched bristle 15A during brushing, and the anisotropy of the bending direction due to the shape can be mitigated, so that the penetration into the interdental area and the cervical area is improved, and a sufficient cleaning feeling can be obtained.

[0059] In addition, all filaments 15 constituting brush section 16 each have thin branched bristles, and each branched bristles 15A flexes to provide cushioning properties. Because each branched bristles 15A flexes isotropically, it has appropriate cushioning properties regardless of the brushing direction, and is unlikely to cause pain when it comes into contact with the gums.

[0060] Furthermore, the filament 15 of this embodiment has a pair of grooves 19 formed from the root 15b to the branch start position P, which allows the entire filament to bend easily from the root 15b while ensuring the maximum long axis width W1 of the filament 15 on the root 15b side. As a result, during brushing, the interdental areas and the cervical area can be efficiently cleaned by the branched bristles 15A with an expanded range of motion, and plaque on the tooth surface can be simultaneously scraped off by the edge of the base 15J (hair belly) where the root 15b is moderately bent.

[0061] In this embodiment, one filament 15 has a pair of grooves 19, but it is sufficient that the filament 15 has at least one groove 19, and may have three or more grooves 19. The grooves 19 are preferably provided continuously from the root 15b to the branch start position P, but may be provided partially. The grooves 19 are preferably provided at least in the root 15b or in a portion close to the root 15b. In this embodiment, the pair of grooves 19 are provided on both sides of the root 15b in the short axis direction, but may be provided on both sides of the long axis direction. When the number of grooves 19 is three or more, they may be provided in both the short axis direction and the long axis direction.

[0062] In addition, in this embodiment, as shown in FIG. 7, the distance W5 between the tips 15a of the two branched bristles 15A within one filament is within a range of 51 to 99% of the maximum long axis width W1 of the base 15b. Therefore, when the tips of the two branched bristles within one filament 15 are bent, they do not interfere with each other and are easy to move, improving the ease of penetration into the interdental and cervical areas, the cleaning feel, and the comfort of the brush.

[0063] In addition, the filaments 15 that make up the brush section 16 are arranged at a distance of 0.1 mm or more from the adjacent filaments 15, which prevents the filaments 15 from interfering with each other during brushing. This allows the movement of each filament 15 to be unrestricted, improving the penetration of the bristles into the interdental spaces and the cervical area of ​​the teeth, and providing a more effective cleaning experience.

[0064] [Second embodiment] Next, a toothbrush 20 according to a second embodiment of the present invention will be described. The basic configuration of the toothbrush 20 of this embodiment described below is substantially the same as that of the first embodiment described above, but the shape of the brush part 26 is different. In the previous embodiment, the bristles have a flat brush profile, but in this embodiment, the bristles are not flat but have a stepped brush profile. Therefore, in the following description, the shape of the brush portion 26 will be described in detail, and a description of the common parts will be omitted. In addition, in each drawing used in the description, the same reference numerals will be used to designate the same components as those in Figs. 1 to 8.

[0065] 9 and 10, the toothbrush 20 of this embodiment is composed of a plurality of outer filaments 151 arranged on the outermost periphery of the bristle implantation surface 11a, a plurality of inner filaments 152 arranged inside the plurality of outer filaments 151, and a plurality of central filaments 153 located in the center of the length direction of the head portion 11 and arranged in the width direction. The outer filaments 151 and the central filaments 153 have the same bristle length, and the inner filaments 152 have a shorter bristle length than the outer filaments 151 and the central filaments 153. Therefore, the brush portion 26 of this embodiment has a brush profile with a step on the bristle tip side, as shown in FIG.

[0066] In this embodiment, the arrangement region of the inner filaments 152 is divided into two in the longitudinal direction of the head portion 11 by the central filament group 153A, and the inner filament group 152A is present in each of the two regions surrounded by the outer filament group 151A and the central filament group 153A. As shown in Fig. 10, the outer filaments 151 and the central filaments 153 are arranged in two rows around the inner filament group 152A.

[0067] As described above, the overall hair length (filament length) of the inner filament 152 is shorter than the filament lengths of the surrounding outer filaments 151 and central filament 153. In this embodiment, for example, when the (filament length) of the outer filaments 151 and central filament 153 is 11 mm, the filament length of the inner filament 152 is 9 mm, and there is a hair length difference (step) of 2 mm between the outer filaments 151 and central filaments 153 and the inner filament 152. It is preferable that there is a step of at least 1 mm, preferably 1 to 4 mm, more preferably 1 to 3 mm, and even more preferably 1 to 2 mm.

[0068] Therefore, the tip side of the brush part 26 in this embodiment has a concave shape with the bristles partially lowered only at the two inner filament groups 152A. That is, at the tip side of the brush part 26, there are two concave shapes in the length direction of the head part 11, which are formed by steps generated between the multiple outer filaments 151 and multiple central filaments 153 and the arranged inner filament group 152A.

[0069] The number of recessed shapes in the brush part 26 is not limited to two. For example, the central filament group 153A may be arranged in two locations spaced apart in the longitudinal direction of the head part 11. This divides the arrangement area of ​​the inner filament group 152A into three, and three recessed shapes are formed.

[0070] In addition, by providing a difference in bristle length among the multiple inner filament groups 152A, concave shapes with different depths may be formed, resulting in a brush profile having multiple steps.

[0071] It is also possible to configure the brush without providing the central filament 153. In this case, the step between the outer filament 151 and the inner filament 152, which has a shorter bristle length, results in a brush profile with a concave shape at the tip side of the brush portion 26.

[0072] Furthermore, the depth of the recessed shape, that is, the difference in hair length (step) between the outer filament 151 and the central filament 153 and the inner filament 152 is not limited to 2 mm.

[0073] [Example] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples and can be modified appropriately without departing from the gist of the present invention. Table 1 shows the differences in configuration between Examples 1 to 3, which are configurations of the present invention, and a comparative example, which is a conventional configuration.

[0074] [Table 1]

[0075] According to the specifications shown in Table 1, toothbrush samples of Examples 1 to 3 and Comparative Example were each produced. (1. Position of the tip of the split hair) Specifically, in regard to the position of each tip of the two branched hairs as viewed from the tip side of the filament, in Examples 1 to 3, it was located inside the outer peripheral edge 15b1 of the base 15b, while in the comparative example, it was located on the outer peripheral edge of the base (at a position overlapping with the outer peripheral edge).

[0076] (2. Presence or absence of groove on the base side) Regarding the presence or absence of grooves on the base side of the filament, in Example 1, a shape without grooves was used, in Examples 2 and 3, a shape with grooves (two grooves) was used, and in the comparative example, a shape without grooves was used.

[0077] (3. Presence or absence of a continuous groove from the base to the branch start position P) Regarding the presence or absence of a continuous groove from the base of the filament to the branch start position, Example 1 and the comparative example have a shape without a continuous groove, while Example 2 and Example 3 have two grooves that are continuous from the base to the branch start position.

[0078] (4. Distance between the tips of split hairs) The distance between the tips of the two branched hairs in one filament was 0.18 mm in Example 1, 0.5 mm in Examples 2 and 3, and 0.4 mm in the comparative example.

[0079] (5. Minimum distance between filaments) The minimum distance between the multiple filaments in the brush portion was 0.2 mm in Examples 1 to 3, and 0 mm in the comparative example.

[0080] (6. Brush Profile) The shape of the tip end of the brush part, the brush profile, was flat in Examples 1 and 2 and the Comparative Example. In Example 3, in order to create a shape having two or more concave shapes with a step of 1 mm or more, in the arrangement of Figures 9 to 11, the hair length of the multiple outer filaments 151 and the multiple central filaments 153 is 11 mm, the hair length of the inner filament 152 is 9 mm, and a step of 2 mm is provided between the outer filaments 151 and the central filament 153 and the inner filament 152.

[0081] [Evaluation items] Examples 1 to 3 and the Comparative Example were evaluated with respect to the cleaning feel of the brush part on the interdental and cervical areas, and the comfort of the brush part on the gums. [Evaluation method] <Evaluation of cleaning experience> A panel of 10 experts cleaned the oral cavity with each toothbrush and evaluated the cleaning sensation in the interdental and cervical areas and the comfort on the gums using the following criteria. Here, the evaluation was made on a 7-point scale based on the average score of the 10 expert panelists.

[0082] Specifically, an average score of 6 or more by the 10-member expert panel was designated as "◎ (Very Good)," an average score of 4 to less than 6 was designated as "○ (Good)," an average score of 3 to less than 4 was designated as "△ (Not Bad)," and an average score of less than 3 was designated as "× (Bad)."

[0083] <Evaluation criteria> 7 points: Very good. 6 points: Quite good. 5 points: Fairly good. 4 points: Neither. 3 points: Somewhat poor. 2 points: Very bad. 1 point: Very bad.

[0084] As shown in Figure 10, the toothbrushes of Examples 1 to 3, in which the tips of the two branched bristles on the filament are positioned inside the outer periphery of the base, were rated as having a good cleaning experience in the interdental and cervical areas. In particular, the sample of Example 3, which has a bristle profile with two or more concave shapes with a step of 1 mm or more, received a higher rating than the samples of Examples 1 and 2, which had a flat brushing profile.

[0085] In addition, the samples of Example 2 and Example 3, which have two continuous grooves from the base to the bifurcation start position, received a better evaluation for the comfort of contact with the gums than the sample of Example 1, which does not have grooves. In particular, the sample of Example 2, which has a flat brushing profile, received a high evaluation.

[0086] On the other hand, the samples of Example 1 and Comparative Example, which do not have grooves, were rated low for comfort on the gums. In particular, the sample of Comparative Example, which not only does not have grooves but also has the tips of the branched bristles located on the outer periphery of the base, was rated very low for comfort on the gums. In addition, the sample of Example 1, which does not have grooves but has the tips of the two branched bristles located inside the outer periphery of the base, was rated slightly better than the sample of Comparative Example.

[0087] In addition, as in Examples 2 and 3, when the tips of the two branched bristles in the filament are spaced apart to a certain extent, the cleaning feel and the comfort of the brush were evaluated as being good. For example, it is better for the tips of the two branched bristles to be spaced apart by about 0.5 mm. On the other hand, even if the tips of the branched bristles were 0.4 mm apart as in the comparative example, when the tips of the branched bristles were located on the outer periphery, the evaluation was generally lower than that of Example 1 in which the distance between the tips of the branched bristles was 0.18 mm, which was narrower than the comparative example. That is, Example 1 in which the tips of the branched bristles were located inside the outer periphery of the base was rated better than the comparative example in terms of cleaning feel and touch comfort.

[0088] In addition, the samples of Examples 1 to 3, in which the filaments were arranged with a minimum distance between them, generally rated higher in terms of cleaning feel and comfort than the samples of the comparison example, in which there was no distance between the filaments and the filaments were arranged closely together.

[0089] Thus, even though the filament has branched bristles at the tips, Examples 1 to 3, which satisfy the conditions such as the position of the branched bristles tips, the presence or absence of (continuous) grooves, the distance between the tips, the distance between the filaments, and the brushing profile, were generally rated higher than the comparative examples in terms of the cleaning feel in the interdental and cervical areas and the comfort on the gums.

[0090] Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0091] For example, in each of the above embodiments, one filament 15 has two branched hairs 15A, but it may have three or more branched hairs 15A. In addition, among the multiple branched hairs 15A in one filament 15, some or all of the branched hairs 15A may have different hair lengths. In addition, branched hairs 15A of different thicknesses may exist in one filament 15. In addition, at least the tip side of the branched hair 15A may be further branched.

[0092] Also, for example, the plurality of filaments 15 constituting the brush portion 16 may be arranged in a lattice pattern and a staggered pattern as shown in FIG. [Explanation of symbols]

[0093] 10, 20...toothbrush, 11...head portion, 12...neck portion, 13...handle portion, 15...filament, 15a...tip, 15b...base, 15j, 15k...side, 15A...branched hair, 16, 26...brush portion, 151...outer filament, 15b1, 15d1, 15d2...outer edge, 152...inner filament, 153...central filament, L1...length of filament, L2...length of branched hair, X...minor axis in cross-sectional shape of filament 15, Y...major axis in cross-sectional shape of filament 15

Claims

1. A brush portion made of a plurality of filaments; A head portion having the brush portion on one side thereof; A handle portion disposed rearward of the head portion; a neck portion connecting the head portion and the handle portion, the filament and the head portion are integrally molded, The filament has a base and two or more branched hairs located on a tip side of the base, a cross-sectional area in a width direction intersecting a length direction of the filament continuously decreases from a base to a tip, and each tip of the two or more branched hairs is located inside an outer peripheral edge of the base of the filament in the width direction; The cross-sectional shape of each of the filaments at the base portion has a minor axis and a major axis that are perpendicular to the longitudinal direction and intersect with each other, Each of the filaments has a first side surface along the major axis formed concavely and a pair of grooves extending continuously from the base in the longitudinal direction, The cross-sectional shapes of the pair of grooves are such that bottoms face each other at a central position in the long axis direction along the long axis, and each extends at an incline toward the outside in the short axis direction along the short axis as it moves toward the outside in the long axis direction, and has a pair of tapered surfaces toward a corner portion with the second side surface along the short axis, The bottom portions gradually approach each other from the base toward the tip and communicate with each other in the minor axis direction, The branched hairs are formed in a region in the length direction where at least the bases communicate with each other in the minor axis direction, A parting line is present on a second side of the filament along the minor axis at a center of a minimum minor axis width and extending in the length direction; A toothbrush, wherein the filaments aligned in the head portion are arranged such that the parting lines are positioned on the same straight line along the one surface.

2. The cross-sectional shape of the filament is symmetrical with respect to the minor axis and the major axis which intersect with each other.

2. The toothbrush of claim 1.

3. The distance between the tips of the two branched hairs in one filament is within a range of 51 to 99% of the maximum major axis width W1 of the base.

3. The toothbrush of claim 2.

4. A plurality of outer filaments arranged at the outermost periphery of the brush portion; a plurality of inner filaments having a shorter hair length than the outer filaments and disposed inside the outer filaments; A step of at least 1 mm is provided between the tip of the outer filament and the tip of the inner filament.

2. The toothbrush of claim 1.

5. The head portion has a plurality of central filaments arranged in a width direction intersecting with a length direction of the head portion, the central filaments dividing an arrangement region of the inner filaments into a plurality of regions in a length direction, The hair length of the central filament is equal to the hair length of the outer filaments.

5. The toothbrush of claim 4.

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