toothbrush

Abstract

The purpose of the present invention is to provide a toothbrush which exhibits excellent toothpaste retention properties. The toothbrush is provided with a head section having a bristle insertion region and a handle section which connects to the head section. The head section has a first bristle insertion section in which a single bristle bundle is provided to the bristle insertion region so as to form an independent sheet-like shape when seen straight on from the front surface side facing the bristle insertion region, and a second bristle insertion section in which a single bristle bundle is provided to the bristle insertion region to the outside of the first bristle insertion section with a gap interposed therebetween so as to extend around the outer circumference of the first bristle insertion section. The second bristle insertion section which is farthest from the first bristle insertion section continuously surrounds the entirety of the first bristle insertion section, or non-continuously surrounds the same with a gap interposed therebetween which has a width in the circumferential direction of 0.7-2mm, inclusive. The length in the circumferential direction of the second bristle insertion section, excluding the gap, is at least 85% of the dimensional total of the total gap width and the length of the second bristle insertion section in the circumferential direction.

Description

[Technical Field]

[0001] The present invention relates to a toothbrush. This application claims priority based on Japanese Patent Application No. 2020-214444, filed on December 24, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] Oral cleaning by brushing typically involves applying a paste-like toothpaste containing an abrasive to the tips of the bristles attached to the toothbrush head, then moving the toothbrush back and forth against the teeth to remove plaque. Immediately after starting to brush, the toothpaste transforms from a high-viscosity paste into a low-viscosity foam due to the saliva and air in the oral cavity. Brushing the tooth surface while retaining the foam on the bristles and bristles of the brush brings the abrasives contained in the foam into contact with the tooth surface, cleaning the tooth.

[0003] However, as the viscosity of the toothpaste decreases during the middle of cleaning, the abrasive drips out of the gaps between the outermost bristles of the bristle section. As a result, most of the abrasive does not remain on the bristles by the time cleaning is finished, and the abrasive may not maintain a consistent contact time with the tooth surface from the beginning to the end of cleaning.

[0004] Thus, as a toothbrush that can hold dentifrice and spread it over the teeth, one has been disclosed in which the bristles in the center are shortened to form a recess that can hold dentifrice in the recess (for example, Patent Document 1). Furthermore, as a toothbrush that excels in dentifrice retention and dispersion, one has been disclosed in which the bristles are branched at the ends and the bristle diameter and bristle density are controlled (for example, Patent Document 2). Patent Document 2 also discloses that the bristles in the center bristles are shorter than those in the outer bristles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-4905 [Patent Document 2] Japanese Patent Application Publication No. 2018-19876 Summary of the Invention [Problem to be solved by the invention]

[0006] In the prior art described above, toothpaste is held in the recess or in the central bristle bundle located between the outer bristle bundles, but because the gaps between the bristle bundles located at the outermost periphery when viewed from the front are open to the outside, toothpaste retention is insufficient.

[0007] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a toothbrush that has excellent toothpaste retention properties. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a toothbrush comprising a head portion having a bristle implantation area and a handle portion connected to the head portion, wherein the head portion has a first bristle implantation area formed of a single tuft of bristles and arranged in an independent planar form in a front view from the front side opposite the bristle implantation area, and a second bristle implantation area formed of a single tuft of bristles and arranged along the outer periphery of the first bristle implantation area and with a gap outside the first bristle implantation area, wherein the second bristle implantation area, which is furthest from the first bristle implantation area, continuously surrounds the entire first bristle implantation area or surrounds it intermittently via a circumferential gap having a width of 0.7 mm or more and 2 mm or less, and wherein the circumferential length of the second bristle implantation area excluding the gap is 85% or more of the sum of the total width of the gap and the circumferential length of the second bristle implantation area.

[0009] Furthermore, in the toothbrush according to one aspect of the present invention, the length of the first bristle implantation portion in the long axis direction of the head portion is greater than the length of the first bristle implantation portion in the short axis direction of the head portion, the maximum length of the first bristle implantation portion in the short axis direction is 3 mm or more and 8 mm or less, and when the maximum length of the first bristle implantation portion in the short axis direction is A and the width of the second bristle implantation portion is B, the relationship 1.5≦A / (2×B)≦8.0 is satisfied.

[0010] In addition, in the toothbrush according to one aspect of the present invention, the maximum length of the first bristle portion in the longitudinal direction is 6 mm or more and 20 mm or less.

[0011] Furthermore, in the toothbrush according to one aspect of the present invention, when viewed from the front, the sum of the area of ​​the first bristle-implanted portion and the area of ​​the second bristle-implanted portion is 55% or more and 95% or less of the total area enclosed by the outermost outline of the second bristle-implanted portion.

[0012] In addition, in the toothbrush according to one aspect of the present invention, the gap between the first bristle portion and the second bristle portion is not less than 0.3 mm and not more than 1.0 mm.

[0013] In addition, in the toothbrush according to one aspect of the present invention, the width of the second bristle portion is not less than 0.5 mm and not more than 1.5 mm.

[0014] Furthermore, in the toothbrush according to one aspect of the present invention, the shortest length of the bristles of the first bristle portion is less than or equal to the shortest length of the bristles of the second bristle portion adjacent to the first bristle portion.

[0015] In addition, in the toothbrush according to one aspect of the present invention, the tip surface of the first bristle portion is characterized by being concave and gradually approaching the front side as it moves outward in the short axis direction of the head portion.

[0016] Furthermore, in the toothbrush according to one aspect of the present invention, the bristle bundles of the second bristle bundle adjacent to the first bristle bundle are inclined toward the first bristle bundle as they approach the tip, and the angle at which the bristle bundles of the second bristle bundle are inclined is 15° or less relative to a direction perpendicular to the bristle implantation area.

[0017] In addition, in the toothbrush according to one aspect of the present invention, the second bristle portions are provided in plurality on the outside of the first bristle portions with gaps between them. [Effects of the Invention]

[0018] The present invention can provide a toothbrush that has excellent dentifrice retention properties. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing an embodiment of the present invention, and is a partial front view of a toothbrush 1 according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a partial front view of the toothbrush 1 according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the toothbrush of the present invention will be described with reference to FIGS. The following embodiment shows one aspect of the present invention, does not limit the present invention, and can be modified as desired within the scope of the technical concept of the present invention. In addition, in the following drawings, the scale and number of each structure are different from the actual structure to make each configuration easier to understand.

[0021] [First embodiment of toothbrush] Fig. 1 is a partial front view of a toothbrush 1 according to a first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 1.

[0022] Toothbrush 1 has a head 3 having a bristle implantation region 2, and a handle 4 connected to head 3. Head 3 has bristle implantation region 2 on the front side. Head 3 is located at the tip side of handle 4 in the longitudinal direction (left-right direction in FIG. 1).

[0023] In the following description, the normal direction of the hair-implanted region 2 (the direction perpendicular to the paper surface in Fig. 1, the vertical direction in Figs. 2 and 3) is defined as the thickness direction, and the direction perpendicular to the major axis and the thickness direction (the vertical direction in Fig. 1, the horizontal direction in Fig. 3) is defined as the minor axis direction. In addition, the side facing the hair-implanted region 2 in the thickness direction is defined as the front side, and the side opposite the front side is defined as the back side.

[0024] The head portion 3 has an oval shape extending in the longitudinal direction when viewed from the front. The head portion 3 has a first bristle-implanted portion 11 and second bristle-implanted portions 21 and 22 in the bristle-implanted region 2. The second bristle-implanted portions 21 and 22 are provided outside the first bristle-implanted portion 11 with a gap between them.

[0025] The first bristle implantation portion 11 is located in the major axis direction and the minor axis direction of the head portion 3. The first bristle implantation portion 11 has an oval shape extending in the major axis direction when viewed from the front. The first bristle implantation portion 11 is provided in an independent planar shape with a single bristle bundle. The first bristle implantation portion 11 is formed from a single bristle bundle in which multiple bristles are bundled together. The bristles of the first bristle implantation portion 11 extend in a direction perpendicular to the bristle implantation region 2. The first bristle implantation portion 11 is implanted in a recess 31 provided in the bristle implantation region 2 of the head portion 3. The recess 31 has an oval shape extending in the major axis direction when viewed from the front, which is the same as the outer diameter contour of the first bristle implantation portion 11.

[0026] The maximum length in the long axis direction of the first bristle part 11 is greater than the maximum length in the short axis direction. The maximum length in the long axis direction of the first bristle part 11 is preferably 6 mm or more and 20 mm or less. By making the maximum length in the long axis direction of the first bristle part 11 6 mm or more and 20 mm or less, it becomes easier for the first bristle part 11 to hold the dentifrice, and sufficient dentifrice effects can be obtained. By increasing the maximum length in the long axis direction of the first bristle part 11, the area for holding the dentifrice increases, improving retention and improving fit to the tooth surface.

[0027] The maximum length of the first bristle portion 11 in the short axis direction is preferably 3 mm or more and 8 mm or less, and more preferably 5 mm or more and 8 mm or less. By setting the maximum length in the short axis direction to 3.0 mm or more and 8.0 mm or less, it becomes easier for the first bristle portion 11 to hold the dentifrice, and sufficient dentifrice effects can be obtained. By increasing the maximum length in the short axis direction of the first bristle portion 11, the area for holding the dentifrice increases, improving retention and improving fit to the tooth surface. It should be noted that 3 mm is a range including 2.5 to 3.4 mm, 5 mm is a range including 4.5 to 5.4 mm, and 8 mm is a range including 7.5 to 8.4 mm.

[0028] As shown in Fig. 2, the tip surface on the front side of the first bristle-implanted portion 11 is gradually concave toward the front as it moves outward in the long axis direction. The side surface of the first bristle-implanted portion 11 is inclined around the entire circumference toward the side away from the second bristle-implanted portion 21 (toward the center in the long axis direction in Fig. 2) as it moves toward the tip. As shown in Fig. 3, the tip surface on the front side of the first bristle-implanted portion 11 is gradually concave toward the front as it moves outward in the short axis direction. The tip surface on the front side of the first bristle-implanted portion 11 may also be gradually concave toward the front as it moves outward in all directions from the center in the long axis and short axis directions.

[0029] By making the tip surface on the front side of the first bristle portion 11 concave, it becomes easier to hold toothpaste, and the contact time between the abrasive and the tooth surface can be increased.

[0030] The second bristle-implanted portion 21 is provided adjacent to the first bristle-implanted portion 11 along the outer periphery thereof with a gap 41 of a constant width therebetween. The second bristle-implanted portion 21 is provided in a ring shape of a constant width that continuously surrounds the entire circumference of the first bristle-implanted portion 11. The bristles of the bristle bundles of the second bristle-implanted portion 21 are inclined at an angle θ around the entire circumference toward the side that approaches the first bristle-implanted portion 11 as they approach the tip. The inclination angle θ of the bristle bundles of the second bristle-implanted portion 21 is the same as the inclination angle of the side surface of the first bristle-implanted portion 11. By setting the inclination angle θ of the bristle bundles of the second bristle-implanted portion 21 to the same angle as the inclination angle of the side surface of the first bristle-implanted portion 11, the width of the gap 41 can be made constant.

[0031] The bristles of the second bristle unit 21 are tilted toward the first bristle unit 11 toward the tip, which creates a larger space for retaining toothpaste on the back side of the second bristle unit 21 than on the tip of the bristle unit. This makes it easier to retain toothpaste and increases the contact time between the abrasive and the tooth surface. Also, by tilting the tip of the second bristle unit 21 toward the first bristle unit 11 in advance, the second bristle unit 21 is less likely to tip toward the periphery during brushing, preventing disruption of the annular structure and resulting in improved toothpaste retention. The angle θ at which the bristle unit 21 is tilted relative to the direction perpendicular to the bristle-implanted region 2 is preferably 15° or less. Setting the angle θ at which the bristle unit 21 is tilted to 15° or less ensures toothpaste retention while improving fit between the teeth and around the cervix. The second bristle-implanted portion 21 is implanted in a recess 32 provided in the bristle-implanted region 2 of the head portion 3. The recess 32 is an oval ring-shaped groove that extends in the longitudinal direction in a front view and has the same outer diameter contour as the second bristle-implanted portion 21.

[0032] The second bristle implantation portion 22 is provided along the outer periphery of the second bristle implantation portion 21, with a gap 42 of a fixed width provided outside the second bristle implantation portion 21. The second bristle implantation portion 22 is provided in a ring shape of a fixed width that continuously surrounds the entire circumference of the second bristle implantation portion 21. The bristles of the bristle bundle of the second bristle implantation portion 22 are inclined at the same angle θ as the inclination angle of the bristle bundle of the second bristle implantation portion 21, all around the circumference, toward the tip and closer to the second bristle implantation portion 21. The second bristle implantation portion 22 is implanted in a recess 33 provided in the bristle implantation region 2 of the head portion 3. The recess 33 is an oval ring-shaped groove extending in the longitudinal direction in a front view, which is the same as the outer diameter contour of the second bristle implantation portion 22.

[0033] The ratio of the outer periphery length (length in the circumferential direction of the outer periphery) of the second bristle-implanted portion 22, which is disposed farthest from the first bristle-implanted portion 11, to the outer periphery length of the recess 33 is 100%.

[0034] The widths of the second bristle portions 21 and 22 may be the same or different. The widths of the second bristle portions 21 and 22 are preferably 0.5 mm or more and 1.5 mm or less, and more preferably 0.8 mm or more and 1.2 mm or less. If the widths of the second bristle portions 21 and 22 are less than 0.5 mm, the contact area between the bristles of the second bristle portions 21 and the toothpaste may not be sufficient, and the second bristle portions 21 may be more likely to bend toward the periphery, potentially reducing toothpaste retention. The thicker the widths of the second bristle portions 21 and 22, the easier they are to retain toothpaste, but the width of the head portion 3 in the minor axis direction may increase, potentially reducing operability. By setting the widths of the second bristle portions 21 and 22 to 0.5 mm or more and 1.5 mm or less, toothpaste retention can be ensured while preventing a decrease in operability.

[0035] When the width of the second bristle portion 21 and the second bristle portion 22 is large, a sufficient area can be secured for contact with the toothpaste, and the second bristle portion 21 is less likely to bend outward, improving retention and a better fit to the tooth surface.

[0036] If the maximum length in the short axis direction of the first bristle-implanted section 11 is A and the width of the second bristle-implanted section 21 is B, the value expressed by A / (2×B) preferably satisfies the relationship 1.5≦A / (2×B)≦8.0, more preferably satisfies the relationship 1.7≦A / (2×B)≦8.0, and even more preferably satisfies the relationship 2.0≦A / (2×B)≦5.0. By setting the value expressed by A / (2×B) to 1.5 or more, the retention of toothpaste in the first bristle portion can be ensured. By setting the value expressed by A / (2×B) to 8.0 or less, the retention of toothpaste in the second bristle portion can be ensured.

[0037] When viewed from the front, the sum of the area of ​​the first bristle portion 11 and the area of ​​the second bristle portion 21 and the second bristle portion 22 preferably has a bristle filling rate of 55% to 95% of the total area enclosed by the outermost outline of the second bristle portion 22, and more preferably a bristle filling rate of 80% to 90%. If the bristle filling rate is less than 55%, the feeling of contact with the gums may be reduced. If the bristle filling rate exceeds 95%, there may be no space to hold the toothpaste, and toothpaste retention may be reduced. By setting the bristle filling rate to 55% to 95%, the feeling of contact with the gums is improved and toothpaste retention can be ensured.

[0038] The number of second bristle parts is preferably two or more and four or less, and more preferably two or more and three or less. If the number of second bristle parts is one or less, the toothpaste retention may be reduced. If the number of second bristle parts exceeds four, the width of the head part 3 in the short axis direction may become large, which may reduce operability. By setting the number of second bristle parts to two or more and four or less, it is possible to ensure toothpaste retention while suppressing a decrease in operability. By increasing the number of second bristle portions, the area for holding toothpaste becomes larger, improving retention and improving fit to the tooth surface.

[0039] Total area of ​​the head part 3 in front view (mm 2The ratio of the total number of bristles (pieces) of the first bristled portion 11 and the second bristled portions 21, 22 to the total number of bristles (pieces) is preferably 15 or more and 90 or less, and more preferably 25 or more and 90 or less. Total area of ​​head part 3 (mm 2 If the ratio of the total number of bristles (pieces) of the first bristled portion 11 and the second bristled portions 21, 22 to the total area (mm 2 ) exceeds 90, the bristles will be less flexible and the toothpaste dispersibility may decrease. In other words, toothpaste is required to have not only retention properties but also dispersibility to prevent excessive dilution of the toothpaste, to distribute the required amount of toothpaste to the required areas, and to prevent the toothpaste from accumulating locally within the brush. Total area (mm 2 By setting the ratio of the total number of bristles (pieces) of the first bristle portion 11 and the second bristle portion 21, 22 to the total number of bristles (pieces) at 15 or more and 90 or less, the fit to the tooth surface is improved and the dispersibility of the toothpaste can be ensured.

[0040] The widths of gaps 41 and 42 may be the same or different. The widths of gaps 41 and 42 are preferably 0.3 mm or more and 1.0 mm or less. If the widths of gaps 41 and 42 are less than 0.3 mm, it becomes difficult to form grooves corresponding to gaps 41 and 42 between the protrusions used to form recesses 31-33 in the mold used to mold head portion 3. Furthermore, if the widths of gaps 41 and 42 are less than 0.3 mm, the retained dentifrice cannot come into contact with air or saliva, even near the end of brushing, resulting in reduced dispersibility. If the widths of gaps 41 and 42 exceed 1.0 mm, dentifrice may enter gaps 41 and 42, reducing dentifrice retention. Setting the widths of gaps 41 and 42 to 0.3 mm or more and 1.0 mm or less not only improves dispersibility but also facilitates the manufacture of the mold used to mold head portion 3, facilitates dentifrice retention, and increases the contact time between the abrasive and the tooth surface.

[0041] The shortest hair length of the first bristle-implanted portion 11 is preferably equal to or shorter than the shortest hair length of the second bristle-implanted portion 21 adjacent to the first bristle-implanted portion 11. The shortest hair length of the first bristle-implanted portion 11 is preferably the same as the shortest hair length of the second bristle-implanted portion 21 adjacent to the first bristle-implanted portion 11 or has a difference of 4 mm or less, and more preferably has a difference of 2 mm or more and 3 mm or less. By making the shortest bristle length of the first bristle section 11 equal to or shorter than the shortest bristle length of the second bristle section 21 adjacent to the first bristle section 11, toothpaste can be more easily retained on the front side of the first bristle section 11 surrounded by the second bristle section 21, thereby increasing the contact time between the abrasive and the tooth surface.

[0042] If the difference in height between the shortest bristle length of the first bristle portion 11 and the shortest bristle length of the second bristle portion 21 adjacent to the first bristle portion 11 exceeds 4 mm, the first bristle portion may not reach the tooth surface, resulting in a poor fit to the tooth surface. By keeping the difference in height between the shortest bristle length of the first bristle portion 11 and the shortest bristle length of the second bristle portion 21 adjacent to the first bristle portion 11 at 4 mm or less, it is possible to ensure good toothpaste retention and good fit to the tooth surface.

[0043] The minimum bristle length of the first bristle part 11 is preferably 5.5 mm or more and 8.5 mm or less. If the minimum bristle length of the first bristle part 11 is less than 5.5 mm, the bristles may not bend easily and may not feel as good against the gums. If the minimum bristle length of the first bristle part 11 is more than 8.5 mm, the bristles may spread out too much and may not retain toothpaste as effectively. By setting the minimum length of the bristles of the first bristle portion 11 to be 5.5 mm or more and 8.5 mm or less, it is possible to ensure that the toothpaste is retained and that the bristles feel comfortable against the gums.

[0044] The bristle length of the outermost second bristle part 22 is preferably 9.5 mm or more and 12.5 mm or less. If the bristle length of the outermost second bristle part 22 is less than 9.5 mm, the bristles may not bend easily, which may reduce the fit between the teeth and at the cervical area. If the bristle length of the second bristle portion 22 located on the outermost side exceeds 12.5 mm, the operability may be reduced. By setting the bristle length of the second bristle portion 22 located on the outermost side to 9.5 mm or more and 12.5 mm or less, it is possible to ensure a good fit and operability in the interdental area and the cervical area.

[0045] Of the adjacent second bristle portions 21 and 22, the bristle length of the second bristle portion 21 located on the inner side is preferably equal to or shorter than the bristle length of the second bristle portion 22 located on the outer side. By making the bristle length of the second bristle portion 21 located on the inner side equal to or shorter than the bristle length of the second bristle portion 22 located on the outer side, it is possible to prevent the abrasive from climbing over the second bristle portion 22.

[0046] The bristles constituting the bristle bundles of the first bristle implantation section 11 and the second bristle implantation sections 21 and 22 may be straight bristles, bristles whose diameter gradually decreases toward the tip (tapered bristles, super tapered bristles (ultra-fine bristles; ST bristles)), branched bristles, spiral bristles, or bristles with irregular cross sections. In terms of cleaning the area around the orthodontic appliance and the cervical region, tapered bristles are preferred. Tapered bristles ensure sufficient scraping power while allowing the bristles to reach fine areas, improving cleaning effectiveness. Examples of the tip shape of the bristle bundle include flat cut, mountain cut, convex, and concave shapes. By making the tip shape of the bristle bundle mountain cut or hill-shaped, the bristles can reach fine areas, improving cleaning effectiveness. While ST bristles are inherently flexible, using ST bristles for the large-diameter bristle bundles of the first bristle implantation section 11 allows only the bristles near their tips to bend. This makes it difficult for the bristles to fall in the circumferential direction during brushing, thereby achieving both good toothpaste retention and a good fit to the tooth surface.

[0047] Although there are no particular limitations on the material of the bristle bundles, examples of suitable materials include synthetic resin materials such as polyamide (e.g., 6-12 nylon, 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate), polyolefin (e.g., polypropylene), elastomer (e.g., olefin-based, styrene-based), etc. A combination of these resin materials may also be used, and different resin materials may be used for the core and sheath, such as in a core-sheath structure.

[0048] The bristle diameter of the bristles constituting the bristle bundle is, for example, 4 to 8 mils (1 mil = 1 / 1000 inch = 0.025 mm). If it is 4 mils or more, the bristles have enough stiffness to clean the cervical area well, and if it is 8 mils or less, the bristles have enough flexibility to reduce irritation to the gums, etc. Note that the bristle diameter of tapered bristles is the diameter at the base.

[0049] The material of the handle portion 4 is not particularly limited, and it is preferable to use, for example, polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, or the like.

[0050] Methods for fixing the bristle bundles of the first bristle implantation section 11 and the second bristle implantation sections 21 and 22 to the bristle implantation area 2 include a thermal fusion method (pressure-temperature-time (PTt) method) in which the molten part at the bottom of the bristle bundle is pressed into molten resin that will become the head section 3 to fix it, and an in-mold method in which the bottom of the bristle bundle is heated to form a molten mass, and then the molten resin is injected into a mold to form the head section.

[0051] As described above, in the toothbrush 1 of this embodiment, the second bristle sections 21, 22 are provided as a single tuft of bristles that continuously surround the entire circumference of the first bristle section 11, thereby ensuring the retention of toothpaste.

[0052] [Second embodiment of toothbrush] Next, a second embodiment of the toothbrush 1 will be described with reference to FIG. In this figure, the same elements as those in the first embodiment shown in FIGS. 1 to 3 are given the same reference numerals, and the description thereof will be omitted.

[0053] FIG. 4 is a partial front view of the toothbrush 1 according to the second embodiment. As shown in Fig. 4, in the toothbrush 1 of this embodiment, the second bristle portion 22 has a plurality of gaps 25 (four in Fig. 4). The gaps 25 are located at the center of the second bristle portion 22 in the long axis direction and at the center of the second bristle portion 22 in the short axis direction. The gaps 25 penetrate the second bristle portion 22 in the radial direction. The gaps 25 connect the inside and outside of the second bristle portion 22.

[0054] The second bristle-implanted portion 22 discontinuously surrounds the first bristle-implanted portion 11 and the second bristle-implanted portion 21 all around via gaps 25. The circumferential length of the outer peripheral surface of the second bristle-implanted portion 22 excluding the gaps 25 is preferably 85% or more, and more preferably 90% or more, of the total dimension of the total width of the plurality of gaps 25 and the circumferential length of the outer peripheral surface of the second bristle-implanted portion 22. If the circumferential length of the outer surface of the second bristle portion 22 excluding the gaps 25 is less than 85% of the total dimension of the total width of the multiple gaps 25 and the circumferential length of the outer surface of the second bristle portion 22, the toothpaste retention ability will decrease. By making the circumferential length of the outer peripheral surface of the second bristle portion 22 excluding the gaps 25 85% or more of the total dimension of the total width of the multiple gaps 25 and the circumferential length of the outer peripheral surface of the second bristle portion 22, toothpaste can be more easily retained.

[0055] The circumferential width of the gap 25 is preferably 2 mm or less, and more preferably 1 mm or less. When the width of the gap 25 is not constant, the width of the gap 25 is the maximum width. If the circumferential width of gap 25 exceeds 2 mm, the dentifrice diluted by saliva may drip outward from gap 25, reducing the retention of the dentifrice. By setting the circumferential width of gap 25 to 2 mm or less, the dentifrice can be prevented from dripping outward from gap 25 due to surface tension. This improves the retention of the dentifrice in the bristle bundles, and increases the contact time between the abrasive and the tooth surface. It should be noted that 2 mm or less includes 1.5 to 2.4 mm, and 1 mm or less includes 0.5 to 1.4 mm.

[0056] In the toothbrush 1 of this embodiment, even if a gap 25 is provided in the second bristle-implanted portion 22, which is located farthest from the first bristle-implanted portion 11, the same action and effect as in the first embodiment can be obtained by making the circumferential width of the gap 25 2 mm or less.

[0057] In the second embodiment, a configuration in which the gaps 25 are provided in the second bristle portion 22 is exemplified, but the present invention is not limited to this configuration, and gaps may also be provided in the second bristle portion 21. Even when this configuration is adopted, the width and number of the gaps provided in the second bristle portion 21 can be the same as those of the gaps 25 provided in the second bristle portion 22. When gaps are provided in both the second bristle portion 21 and the second bristle portion 22, it is preferable to shift the circumferential positions of the gaps provided in the second bristle portion 21 from the circumferential positions of the gaps provided in the second bristle portion 22 in order to prevent toothpaste from dripping through the gaps.

[0058] [Example] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention.

[0059] (Examples 1 to 9, Comparative Examples 1 and 2) In the present example, toothbrush samples of Examples 1 to 9 and Comparative Examples 1 and 2 were produced according to the specifications shown in Table 1 and Table 2 below. The dimensions of each part of the toothbrush in each example are shown in Tables 1 and 2. PP resin was used for the handle.

[0060] The sample of Example 1 was the toothbrush described in the first embodiment above. The sample of Example 2 was the toothbrush described in the second embodiment above. The sample of Example 3 was a toothbrush with a larger number of voids than the sample of Example 2. The sample of Example 4 was a toothbrush with a larger void width than the sample of Example 2. The sample of Example 5 was a toothbrush in which the gaps between the first and second bristle implantation sections and the gaps between the second bristle implantation sections were larger than the sample of Example 1. The sample of Example 6 was a toothbrush in which the length of the first bristle implantation section in the short axis direction was smaller than the sample of Example 1. The sample of Example 7 was a toothbrush in which the width of the second bristle implantation section was smaller than the sample of Example 1. The sample of Example 8 was a toothbrush in which a larger void width was provided in the inner second bristle implantation section than the sample of Example 4. The sample of Example 9 was a toothbrush in which the length of the first bristle implantation section in the short axis direction was less than 5.0 mm compared to the sample of Example 6.

[0061] The sample of Comparative Example 1 was a toothbrush in which the width of the gaps was larger than that of the sample of Example 3, and the circumferential length of the outer peripheral surface of the second bristle-implanted portion excluding the gaps was less than 85% of the total dimension of the total width of the plurality of gaps and the circumferential length of the outer peripheral surface of the second bristle-implanted portion.The sample of Comparative Example 2 was a toothbrush in which the length of the outer peripheral surface of the second bristle-implanted portion excluding the gaps was less than 85% of the total dimension of the total width of the plurality of gaps and the circumferential length of the outer peripheral surface of the second bristle-implanted portion compared to the sample of Example 8.

[0062] [Evaluation method] (1) Toothpaste retention [Test method] The evaluation was carried out by a sensory test using a panel of 10 experts. After applying 1 g of commercially available toothpaste to the toothbrush shown in each Example and Comparative Example and brushing for 3 minutes, the amount of toothpaste remaining on the toothbrush was evaluated according to the following criteria. An average score of 4.5 or more and 5.0 or less by the 10 expert panel was marked with a "☆ (star mark)," an average score of 4.0 or more and less than 4.5 was marked with a "◎ (double circle mark)," an average score of 3.5 or more and less than 4.0 was marked with a "〇 (circle mark)," an average score of 3.0 or more and less than 3.5 was marked with a "△ (triangle mark)," and an average score of less than 3.0 was marked with an "× (cross mark)." Toothbrushes that ensured retention with a ☆, ◎, ○, or △ were judged to have good retention. <Evaluation criteria> 5 points: Toothpaste remains between the bristles of the toothbrush. 4 points: A lot of toothpaste remains between the bristles of the toothbrush. 3 points: Toothpaste remains between the bristles of the toothbrush. 2 points: There is some toothpaste remaining between the bristles of the toothbrush. 1 point: No toothpaste remains between the bristles of the toothbrush.

[0063] (2) Fit to the tooth surface [Test method] The evaluation was carried out by a sensory test using a panel of 10 experts. 1 g of commercially available dentifrice was placed on the toothbrush shown in each Example and Comparative Example, and brushing was carried out for 3 minutes. The toothbrush's fit to the tooth surface was evaluated according to the following evaluation criteria. An average score of 4.5 or more and 5.0 or less by the 10 expert panel was given a "☆", an average score of 4.0 or more and less than 4.5 was given a "◎", an average score of 3.5 or more and less than 4.0 was given a "〇", an average score of 3.0 or more and less than 3.5 was given a "△", and an average score of less than 3.0 was given an "×". Toothbrushes that were given a "☆", "◎", "○" or "△" fit to the tooth surface were judged to provide good fit to the tooth surface when brushing. <Evaluation criteria> 5 points: The "fit to the tooth surface" is very noticeable. 4 points: The "fit to the tooth surface" is quite noticeable. 3 points: Feels like it fits snugly to the tooth surface. 2 points: "Fits the tooth surface" is slightly felt 1 point: There is no sense of "fitting to the tooth surface" at all.

[0064] [Table 1]

[0065] [Table 2]

[0066] As shown in [Table 1] and [Table 2], in the samples of Examples 1 to 9, in which the second bristle portion farthest from the first bristle portion continuously surrounds the entire circumference of the first bristle portion, or surrounds it intermittently through a gap with a circumferential width of 0.7 mm or more and 2 mm or less, and in which the circumferential length of the second bristle portion excluding the gap is 85% or more of the total width of the gap and the circumferential length of the second bristle portion, good evaluations were obtained for both "dentifrice retention" and "fit to the tooth surface."

[0067] In addition, in the samples of Examples 1 to 8 in which the maximum length of the first bristle portion in the short axis direction was 3 mm or more and 8 mm or less, and the maximum length A of the first bristle portion in the short axis direction and the width B of the second bristle portion satisfied the relationship 1.5≦A / (2×B)≦8.0, good evaluations were obtained for both "dentifrice retention" and "fit to the tooth surface."

[0068] The samples of Examples 1 to 9, in which the filling rate of the bristle portion was 55% or more and 95% or less, were evaluated as good in both "dentifrice retention" and "fit to the tooth surface."

[0069] In the samples of Examples 1 to 9, in which the gap between the first and second bristle sections was 0.3 mm or more and 1.0 mm or less, good evaluations were obtained for both "dentifrice retention" and "fit to the tooth surface."

[0070] In contrast, the samples of Comparative Examples 1 and 2, which did not satisfy at least one of the following conditions: the second bristle-implanted portion, which is the farthest from the first bristle-implanted portion, is intermittently surrounded by a gap having a circumferential width of 0.7 mm or more and 2 mm or less; and the circumferential length of the second bristle-implanted portion excluding the gap is 85% or more of the total width of the gap and the circumferential length of the second bristle-implanted portion, did not receive a good evaluation for "toothpaste retention."

[0071] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention. [Industrial Applicability]

[0072] The present invention is applicable to toothbrushes. [Explanation of symbols]

[0073] 1...toothbrush, 2...bristle implantation area, 3...head portion, 4...handle portion, 11...first bristle implantation portion, 21, 22...second bristle implantation portion, 25...gap

Claims

1. a head portion having a bristle implantation region and a handle portion connected to the head portion; The head portion is a first bristle implantation portion provided in the bristle implantation region with a single bristle bundle and positioned at the center of the head portion in an independent planar shape when viewed from the front side opposite the bristle implantation region; a second bristle-implanted portion formed of a single bristle bundle and arranged along the outer periphery of the first bristle-implanted portion and spaced apart from the outer periphery of the first bristle-implanted portion, The second hair-implanted portion farthest from the first hair-implanted portion is The first bristle portion is surrounded continuously around the entire circumference, or is surrounded intermittently via a gap having a circumferential width of 0.7 mm or more and 2 mm or less, The bristle bundles of the first bristle implantation portion and the second bristle implantation portion each have a flat, continuous base end and are inclined inward toward the tip end, A toothbrush characterized in that the circumferential length of the second bristle portion excluding the gap is 85% or more of the sum of the total width of the gap and the circumferential length of the second bristle portion.

2. a length of the first bristle implantation portion in the major axis direction of the head portion is greater than a length of the first bristle implantation portion in the minor axis direction of the head portion; The maximum length of the first bristle portion in the short axis direction is 3 mm or more and 8 mm or less, When the maximum length of the first bristle implantation portion in the minor axis direction is A and the width of the second bristle implantation portion is B, The relationship 1.5≦A / (2×B)≦8.0 is satisfied. The toothbrush of claim 1.

3. The maximum length of the first bristle portion in the longitudinal direction is 6 mm or more and 20 mm or less. The toothbrush of claim 2.

4. When viewed from the front, the sum of the area of ​​the first bristle-implanted portion and the area of ​​the second bristle-implanted portion is 55% or more and 95% or less of the total area surrounded by the outermost outline of the second bristle-implanted portion.

4. The toothbrush according to claim 1.

5. The toothbrush according to claim 1 , wherein the gap between the first bristle portion and the second bristle portion is 0.3 mm or more and 1.0 mm or less.

6. The width of the second bristle portion is 0.5 mm or more and 1.5 mm or less.

6. The toothbrush of claim 5.

7. The shortest length of the hair of the first hair-implanted portion is equal to or shorter than the shortest length of the hair of the second hair-implanted portion adjacent to the first hair-implanted portion.

7. The toothbrush according to any one of claims 1 to 6.

8. The tip end surface of the first bristle portion is concave and gradually approaches the front side as it extends outward in the short axis direction of the head portion.

8. The toothbrush of claim 7.

9. The hair bundles of the second hair implantation section adjacent to the first hair implantation section are inclined toward the first hair implantation section as they approach the tip end, The angle at which the tufts of the second tufted portion are inclined is 15° or less with respect to a direction perpendicular to the tufted area.

9. The toothbrush of any one of claims 1 to 8.

10. The second bristle portions are provided in plurality at the outer sides of the first bristle portions with gaps between them.

10. The toothbrush of any one of claims 1 to 9.

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