Toothbrush

Abstract

The present invention relates to a toothbrush in which a plurality of filament bundles, which comprise 16-branched filaments of which the distal end is branched into 16 strands, are implanted in a first region on the left and right outer sides of a filament-implantation surface of a head part of the toothbrush, and a plurality of filament bundles, which comprise 3-branched filaments of which the distal end is branched into 3 strands, are implanted in a second region further to the inner side of the filament-implantation surface than the first region. The first region may include a region where the filament bundles of the outermost row at both left and right edges are erected. The 16-branched filaments each have a core-sheath structure comprising 16 core parts and a sheath part surrounding the core parts, and have, at the distal end thereof, a branched portion formed from the 16 core parts being exposed from the sheath part. The outer diameter of each core part of the core-sheath structure may be 15-22 μm.

Description

toothbrush

[0001] This invention relates to a toothbrush having branched bristles at the tip.

[0002] Conventionally, toothbrushes in which filaments with multiple branched and tapered tips are embedded in the brush portion are known to have excellent interdental penetration, a high cleaning sensation, and to be less likely to cause gingival irritation because the branched tips become softer (Patent Documents 1 and 2).

[0003] Japanese Patent Publication No. 2001-169827 Japanese Patent Publication No. 2003-199626

[0004] In particular, filaments with three branched tips (trifugal bristles) are considered to be superior in cleaning tooth surfaces and interdental spaces because they allow for easier application of pressure to the cleaning surface. However, during their research, the inventors discovered that when brushing teeth with a toothbrush equipped only with trifugal bristles, the tips of the bristle bundles, when they touch the gums, tend to feel less soft, and some people experience pain, for reasons unknown.

[0005] Therefore, in view of the above-mentioned circumstances, the present invention aims to provide a toothbrush that is gentle on the gums and has excellent cleaning properties.

[0006] In view of the current situation, the inventors of the present invention have conducted diligent studies and found that the above problem can be solved by implanting multiple hair bundles consisting of 16-branched hairs, each with a tip branched into 16, in a first region on the left and right outer sides of the hair implantation surface of the head portion where multiple hair bundles are implanted, and by implanting multiple hair bundles consisting of 3-branched hairs, each with a tip branched into 3, in a second region inside the first region, thus completing the present invention.

[0007] In other words, the present invention encompasses the following inventions: (1) A toothbrush in which a plurality of bristle bundles of the head portion are planted, and a first region on the left and right outer sides of the bristle surface on which a plurality of bristle bundles of the head portion are planted, in which a plurality of bristle bundles consisting of 16-branched bristles with 16 branches at the tip are planted, and a second region on the bristle surface inward from the first region is planted, in which a plurality of bristle bundles consisting of 3-branched bristles with 3 branches at the tip are planted. (2) The toothbrush according to (1), wherein the first region includes the region in which the outermost rows of bristle bundles at both the left and right ends are planted. (3) The toothbrush according to (1) or (2), wherein the 16-branched bristles have a core-sheath structure consisting of 16 cores and a sheath surrounding them, and have branched portions at the tip that are exposed from the sheath and consist of the 16 cores, and the outer diameter of each core in the core-sheath structure is 15 to 22 μm. (4) When the entire bundle of hair in the head section is pressed at a constant speed of 0.1 mm / min along the direction of the protrusion of the hair bundle, from the tip to the base, until the amount of indentation is 1 mm, the maximum value of the average pressure is 400 g / cm². ２ The toothbrush described in any of (1) to (3) above, which is as follows: (5) When the entire bundle of bristles in the head is pressed at a constant speed of 0.1 mm / min along the direction of protrusion of the bristles, from the tip to the base, until the amount of indentation is 1 mm, the maximum value of the average pressure is defined as P1, and when the same pressure is applied to all of the bristles in the multiple bundles of bristles planted in the head, the maximum value of the average pressure is defined as P0, and the value of P1 is 60 g / cm² higher than the value of P0. ２ The toothbrush described in any of (1) to (4) above, which results in the following increase.

[0008] The toothbrush of this invention has a soft texture against the gums, so even when brushing in a position where the tips of the bristles touch the gums, it is less likely to cause pain. Furthermore, it has excellent cleaning properties, so it can efficiently remove plaque from the tooth surface, between teeth, and around the gums.

[0009] Figure 1(a) is an explanatory diagram showing a toothbrush according to a typical embodiment of the present invention, and Figure 1(b) is an enlarged view of the tip portion of the filament constituting the bristle bundle. Cross-sectional view of 16-branched bristles. Enlarged view of the tip portion of 16-branched bristles. Cross-sectional view of 3-branched bristles. Explanatory diagrams showing the structure of each part of the toothbrushes of Examples 1 to 3 and Comparative Examples 1 to 4, and the results of the softness test of Test Example 1. Explanatory diagram of the embodiment of the softness test of Test Example 1. Explanatory diagram of the pressing surface of the toothbrush. Schematic diagram of an image showing the measurement results of the softness test obtained in Test Example 1. Explanatory diagram of the embodiment of the durability (slipperiness) test of Test Example 2. Graph showing the results of the durability (slipperiness) test in Test Example 2. Explanatory diagram of the embodiment of the durability (bristle tip splitting) test in Test Example 3. Figures 12(a) and 12(b) are explanatory diagrams showing other embodiments of the present invention.

[0010] Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0011] As shown in Figure 1(a), a toothbrush 1 according to a representative embodiment of the present invention comprises a head portion 2 having a bristle base 20 on which a plurality of bristle bundles 10 are planted, and a handle body 3. As shown in Figure 1(b), on the bristle surface 20a of the bristle base 20, a plurality of bristle bundles 10a consisting of 16-branched bristles 4 with 16 branches at the tip are planted in the first regions R11 and R12 on the left and right outer sides, and a plurality of bristle bundles 10b consisting of 3-branched bristles 5 with 3 branches at the tip are planted in the second region R2 inside the first regions R11 and R12.

[0012] In this invention, "left-right direction" refers to the direction that intersects approximately perpendicularly with the axial direction X of the toothbrush 1. When the implantation surface 20a is facing outwards, the right side is referred to as "right" and the left side as "left" with respect to the axial direction X. The tip side of the toothbrush 1 is also referred to as "up," and the rear end side of the toothbrush 1 is also referred to as "down."

[0013] According to the toothbrush 1 of the present invention, as shown in Figures 2 and 3, the core portion 6a constituting the tip of the 16-branched bristles 4 is thin in diameter and soft, so the pressure applied when the surface of the bristle bundles 10a and 10b is pressed against the tooth surface is dispersed. Since these 16-branched bristles 4 are arranged in the first regions R11 and R12 located on the left and right outer sides of the bristle surface 20a, when brushing teeth, the feeling is softer even when the tip of the brush touches the gums, which has the advantage of making it less likely to cause pain. Furthermore, in the toothbrush 1 of the present invention, as shown in Figure 4, three-branched bristles 5 with a larger diameter of core portion 6b than the 16-branched bristles 4 are arranged in the second region R2 located inside the first regions R11 and R12, thus exhibiting higher cleaning power than the 16-branched bristles 4. For this reason, for example, it is easier to make contact with dirt on the tooth surface, between teeth, and on the gums, and dirt on the tooth surface, between teeth, and on the gums can be removed efficiently.

[0014] In the present invention, the head portion 2 is molded together with the handle body 3 from a rigid synthetic resin such as polyacetal resin (POM), polybutylene terephthalate resin (PBT), or polyamide resin.

[0015] Furthermore, the body of the toothbrush 1 may be integrally molded using two types of resin materials and may include a base material made of a first resin material having a head portion 2 equipped with a bristle base, a neck portion, and a handle base material portion, and a covering portion made of a second resin material covering a part of the handle base material portion. The first resin material constituting the base material portion is not particularly limited as long as it is a hard thermoplastic resin that can withstand the external force acting during brushing, but a hard resin mainly composed of a resin selected from polybutylene terephthalate resin, polypropylene terephthalate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyester resin, polyacetal resin, polycarbonate resin, and polyamide resin is used. Here, "main component" means a resin that is included in a proportion of 50% by weight or more in a blend or alloy used with other resins, or a copolymer with other resins in a proportion of 50% by weight or more of the polymer repeating units of the resin. In particular, it is preferable to use a polyacetal resin or polyamide resin, which has excellent mechanical strength, to improve the cleaning performance of hard-to-reach areas such as the back surface of molars by making the bristle base 20 of the head portion 2 thin-walled. The coating portion is made of a second resin material which is different in material from the first resin material which constitutes the base portion. As the second resin material which constitutes the coating portion, a hard thermoplastic resin such as polybutylene terephthalate resin or polyethylene terephthalate resin (polypropylene terephthalate resin) can be used, but a soft thermoplastic resin such as a thermoplastic elastomer can be suitably used to obtain an anti-slip function from the coating portion. Specifically, thermoplastic elastomers such as polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, 1,2-polybutadiene-based thermoplastic elastomers, ethylene-vinyl acetate-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers, natural rubber-based thermoplastic elastomers, fluororubber-based thermoplastic elastomers, trans-polyisoprene-based thermoplastic elastomers, and chlorinated polyethylene-based thermoplastic elastomers can be used.

[0016] The size, shape, thickness, etc. of the head portion 2 and the shape, structure, etc. of the handle body 3 can be the same as those of a known toothbrush, and there are no particular limitations. For example, the shape of the head portion 2 may be such that the tip is tapered from the rear end, as shown in the examples 1 and 2 of Figure 1(b) and Figure 5, or the width of the implanting surface 20a may be substantially the same from the tip to the rear end, as shown in the example 3 of Figure 5.

[0017] The thickness of the bristle base 20, the diameter and depth of the bristle holes provided on the bristle surface 20a, the number of bristle holes, and their arrangement are appropriately set according to the target user. For example, the thickness of the bristle base 20 can be appropriately determined to be around 2.5 to 5.0 mm. The diameter of the bristle holes can be appropriately determined to be around 1.0 to 2.5 mm. The depth of the bristle holes can be determined to be in the range of 1.5 to 3.5 mm.

[0018] In the present invention, the first region R11 of the bristled surface 20a refers to the region including the bristles 10 erected in the outermost row in the vertical direction on the left end side of the bristled surface 20a. The first region R12 of the bristled surface 20a refers to the region including the bristles 10 erected in the outermost row in the vertical direction on the right end side of the bristled surface 20a.

[0019] The 16 branched hairs 4 planted in the first regions R11 and R12 have a core-sheath structure 8a consisting of 16 core portions 6a and a sheath portion 7a surrounding them, as shown in Figure 2, and have branched portions 9a made up of the 16 core portions 6a exposed from the sheath portion 7a at the tip of the hair, as shown in Figure 3.

[0020] At the branching portion 9a of the 16-branched bristles 4, 16 thin core portions 6a are exposed. When the bristles are pressed against teeth or gums, the exposed core portions 6a at the tip of the branching portion 9a flexibly deform, thereby providing a soft touch. The spaces between each core portion 6a of the branching portion 9a may be fixed by the resin constituting the sheath portion 7a, or each or part of each core portion 6a may be separated.

[0021] The outer diameter L1 (also called the bristle diameter) of the 16-branched bristles 4 can be in the range of 160 to 210 μm. The outer diameter L2 of the core portion 6a is 15 to 22 μm, which reduces the pressing force and allows for a soft texture while also achieving excellent durability even after repeated brushing. The minimum wall thickness L3 of the sheath portion 7a constituting the core-sheath structure 8a is adjusted to 26 μm or more, which suppresses wear and tear of the sheath portion 7a due to repeated brushing and maintains the durability of the 16-branched bristles 4. In Figures 1(a), 1(b), 2, etc., the outer shapes of the core portion 6a, sheath portion 7a, and 16-branched bristles 4 are all shown to be circular, but this is not the only way to go. Various shapes can be used, such as elliptical or polygonal shapes, as long as there are no recesses where dirt may adhere.

[0022] The tip shape of the core portion 6a exposed at the branching portion 9a can be any shape, such as a tapered shape, a substantially flat shape, or a shape with fine irregularities. The tips of each core portion 6a may be aligned or not, or they may be inclined, for example, as shown in Figure 3, with the length of each core portion 6a varying toward one end. The length L4 of the core portion 6a exposed from the tip at the branching portion 9a should be adjusted to a range of at least 0.01 to 1.2 mm or 0.05 to 1.0 mm during use. The length of the 16 branched bristles 4 erected on the surface of the bristle base 20 should be within the same range as commercially available toothbrushes, and there are no particular limitations. The length of the bristles in the bristle bundles 10a planted in the multiple planting holes of the bristle base 20 may be aligned or there may be differences in length. The difference in bristle length between the bristle bundles 10a should be adjusted to a range of 0 to 2.0 mm.

[0023] In the bristle surface 20a, a three-branched bristle 5 is implanted in the second region R2 located inside the first regions R11 and R12. As shown in Figure 4, the three-branched bristle 5 has a core-sheath structure 8b consisting of three cores 6b and a sheath 7b surrounding them, and has a branched portion (not shown) at the tip of the bristle that is exposed from the sheath 7b. The diameter of the three cores 6b exposed at the branched portion of the three-branched bristle 5 is larger than that of the core 6a of the sixteen-branched bristle 4, so by arranging the three-branched bristle 5 in the second region R2, it can exert pressing force when pressed against teeth or gums, resulting in excellent cleaning performance. The spaces between each core 6b at the branched portion of the three-branched bristle 5 may be fixed by the resin constituting the sheath 8b, or each or part of each core 6b may be separated.

[0024] The outer diameter L1 (also called the hair diameter) of the three-branched hair 5 may be in the range of 160 to 210 μm. The outer diameter L2 of the core portion 6b may be in the range of 30 to 50 μm.

[0025] The tip shape of the core portion 6b exposed at the branching point of the three-branched bristles 5 may be any shape, such as a tapered shape, a substantially flat shape, or a shape with fine irregularities. The tips of each core portion 6b may or may not be aligned. The length of the core portion 6b exposed from the tip at the branching point should be adjusted to a range of at least 0.1 to 1.0 mm during use. The length of the three-branched bristles 5 erected on the surface of the bristle base 20 may be within the same range as commercially available toothbrushes, and there are no particular limitations. The length of the bristles in the bristle bundles 10b planted in the multiple planting holes of the bristle base 20 may be uniform or there may be differences in length. The difference in length between the bristles in the bristle bundles 10b should be adjusted to a range of 0 to 2.0 mm.

[0026] Furthermore, the lengths of the hair bundles 10a and 10b planted in the multiple planting holes of the hair implantation base 20 may be the same or there may be differences in length. The difference in hair length between hair bundles 10a and 10b should be adjusted to within the range of 0 to 2.0 mm.

[0027] The 16-branched bristles 4 and 3-branched bristles 5 used in the present invention can be manufactured by known methods. For example, as described in Japanese Patent Application Publication No. 2010-82094, the core portions 6a and 6b and the sheath portions 7a and 7b are both made of chemically soluble synthetic resins, the synthetic resin of the core portions 6a and 6b is a resin that dissolves more slowly in chemical solution than the synthetic resin of the sheath portions 7a and 7b, and a branched portion is formed at at least one end, consisting of the core portions 6a and 6b exposed from the sheath portions 7a and 7b by a chemical dissolution treatment. However, there are no particular limitations on the manufacturing method.

[0028] The synthetic resins constituting the core portions 6a, 6b and sheath portions 7a, 7b can be polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyester elastomer, or mixtures thereof, which can be used in appropriate combinations depending on their solubility in the chemical solution. For example, in the case of polyester resin, an alkaline dissolving solution such as an aqueous solution of caustic soda can be used. Alternatively, the core portions 6a, 6b and sheath portions 7a, 7b can be made from a combination of polyamide resins, and the branched portion can be created using an acidic dissolving solution. It is also possible to use combinations of other chemically soluble resins.

[0029] In the hair implantation holes of the first regions R11 and R12, hair bundles 10a consisting of 16-branched hairs 4 are implanted. However, if the effects of the present invention can be achieved, hair bundles consisting of branched hairs other than the 16-branched hairs 4 may be implanted in a portion of the hair implantation holes of the first regions R11 and R12. In this case, it is preferable to adjust the proportion of hair bundles 10a consisting of 16-branched hairs 4 implanted in the hair implantation holes of the first regions R11 and R12 to be 80% or more. There are no particular limitations on the branched hairs other than the 16-branched hairs, but from the viewpoint of maintaining a soft texture, branched hairs with more than three core strands may also be used.

[0030] In the hair implantation holes of the second region R2, hair bundles 10b consisting of three-branched hairs 5 are implanted. However, hair bundles consisting of branched hairs other than three-branched hairs 5 may be implanted if the effects of the present invention can be achieved. In this case, the proportion of hair bundles 10b consisting of three-branched hairs 5 implanted in the hair implantation holes of the second region R2 is preferably adjusted to 50% or more, and more preferably to 55% or more. There are no particular limitations on the branched hairs other than three-branched hairs; they may be sixteen-branched hairs 4, or, for example, branched hairs with 10 or fewer core strands.

[0031] Regarding the method of implanting filaments such as 16-branched hairs 4 and 3-branched hairs 5, conventional methods can be widely used. For example, a method can be used in which 10 to 40 filaments are bundled together, a flat wire is pressed against the center, and the filament bundle is driven into the implantation hole while deforming it into a U-shape. Alternatively, a method can be used in which the base end of the filament is melted and embedded and joined into the implantation hole without using such a flat wire.

[0032] The toothbrush 1 according to the present invention, having the above configuration, achieves both softness of the bristle tips against the gums and excellent cleaning performance.

[0033] The softness of the brush against the gums can be evaluated, for example, as shown in Figure 6, by the maximum value of the average pressure when the entire bristle bundle 10 of the head portion 2 is pressed at a constant speed of 0.1 mm / min along the protruding direction of the bristle bundle 10, from the tip to the base, until the amount of indentation is 1 mm. In the toothbrush 1 according to the present invention, from the viewpoint of easily achieving the effects of the present invention, the maximum value of the pressure is 400 g / cm². ２ Preferably, the following applies: In the toothbrush 1 according to the present invention, the maximum value of the pressure is 400 g / cm². ２ Because it is adjusted as described below, it has the advantage that even if the tip of the bristle bundle touches the gums during brushing, it is less likely to cause pain. The method for measuring the average pressure value and its maximum value can be carried out in accordance with the method described in the examples below.

[0034] Furthermore, in order to better achieve the effects of the present invention, when the entire bristle bundle 10 of the head portion 2 is pressed at a constant speed of 0.1 mm / min along the protruding direction of the bristle bundle 10, from the tip to the base, until the indentation is 1 mm, the maximum value of the average pressure is defined as P1, and when the same pressing is applied when all the bristles of the multiple bristle bundles planted in the head portion are 16-branched bristles, the maximum value of the average pressure is defined as P0, and the value of P1 is 60 g / cm² higher than the value of P0. ２ It is preferable that the following increases be made.

[0035] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these examples of implementation, and can be implemented in various forms without departing from the spirit of the invention. For example, the shape of the toothbrush 1 shown in Figures 1(a) and 1(b) is just one example and is not limited to this, and may take various forms. Also, although Figures 1(a) and 1(b) show a manual toothbrush, the present invention is not limited to a manual toothbrush, and may be an electric toothbrush in which a toothbrush cleaning body having the head portion described above is connected to the tip of the main body which serves as a gripping portion containing a drive mechanism, or it may take other forms as well. Furthermore, various arrangements of the bristle holes on the bristle surface 20a can also be adopted. In addition, there are no particular limitations on the number of filaments constituting the bristle bundle 10, the number of bristle holes, or the arrangement state of the bristle bundle 10.

[0036] For example, other embodiments of the arrangement of hair bundles 10 on the hair implantation surface 20a are shown in Figures 12(a) and 12(b). In Figure 12(a), the hair bundles 10 are arranged in eight rows in the vertical direction, with a total of 33 hair bundles 10 implanted: 2 in the first row, 3 in the second row, 4 in the third row, 5 in the fourth to seventh rows, and 4 in the eighth row. In the first regions R11 and R12, located on the left and right outer sides of the first to eighth rows, 8 hair bundles 10a, each consisting of 16 hairs 4, are implanted, for a total of 16 bundles. In the second region R2, located inside the first regions R11 and R12, a total of 13 hair bundles 10b, each consisting of three-branched hairs 5, are placed in the second to sixth rows and in the center of the seventh row, while a total of 4 hair bundles 10a, each consisting of 16 hairs, are placed on the left and right outer sides of the seventh row and in the center of the eighth row, which constitute the second region R2. Furthermore, as shown in Figure 12(b), the bristle bundles 10 are arranged in eight rows vertically and six rows horizontally, with a total of 44 bristle bundles 10 planted: four in the first row vertically, six in the second to seventh rows, and four in the eighth row. In the first, second, fifth, and sixth rows horizontally, including the first regions R11 and 12 from the left and right outer edges, a total of 28 bristle bundles 10a, each consisting of 16 branched bristles 4, are arranged, and in the third and fourth rows horizontally, a total of 16 bristle bundles 10b, each consisting of 3 branched bristles 5, are arranged. With the toothbrush shown in Figures 12(a) and 12(b), the texture against the gums is soft, so even when brushing with the tips of the bristle bundles 10 touching the gums, pain is unlikely to be felt. In addition, because of its excellent cleaning properties, it can efficiently remove plaque from the tooth surface, between teeth, and around the gums.

[0037] As brush filaments (hair diameter (L1): 170 μm), 16-branched hair filaments, 3-branched hair filaments, and saturated polyester hairs were prepared. The composition of each filament is as follows. - 16-branched hair filament (16 hairs) Core part 6a: made of polyamide resin (nylon), Sheath part 7a: made of polyester resin (polybutylene terephthalate), Outer diameter (L2) of core part 6a: 11 μm, 15 μm, 18 μm, 22 μm, 26 μm, Total cross-sectional area ratio of core part 6a: 6.7%, 12.5%, 17.9%, 26.8%, 37.4% Thickness (L3) of the sheath part: 42.5 μm, 37 μm, 32 μm, 27 μm, 21 μm Length (L4) of the branching part 9a (hair length): 0.4 mm - 3-branched hair filament (3 hairs) Core part 6b: made of polyamide resin (nylon), Sheath part 7b: made of polyester resin (polybutylene terephthalate), Outer diameter (L2) of core part 6b: 34 μm, Total cross-sectional area ratio of core part 6b: 12.0% Thickness (L3) of the sheath part: 42.5 μm Length of the branching part (hair length): 0.5 mm When the 16-branched hair filament and the 3-branched hair filament are planted on the hair-planting table 20, both ends of each filament are chemically dissolved to form a branched part where the core part is exposed.

[0038] The outer diameters (L2) of the core parts 6a and 6b, the cross-sectional areas (L2) of the core parts 6a and 6b, and the thicknesses (L3) of the sheath parts 7a and 7b are the average values measured by observing the cross-sectional states of 10 arbitrarily selected filaments of each type after cutting them perpendicular to the axial direction using a digital microscope VHX6000 manufactured by Keyence Corporation. The results are shown in Table 1.

[0039]

[0040] (Example 1) As shown in FIGS. 1(a), 1(b), and 5, a toothbrush 1A having a head portion 2 with a tapered shape of the tufted surface 20a was manufactured by a known method. As the filament material for the brush bristles, the 16-branched hair (core outer diameter (L2) 18 μm) and the 3-branched hair were used. Also, as shown in FIG. 5, a tufting base 20 having 35 tufting holes with a diameter of 1.4 mm was used. A large number of the above filament materials were bundled, and after exposing the core portions at both ends by chemical dissolution, they were folded in half and tufted into each tufting hole using a flat wire. The configuration of each part of the toothbrush 1A is as follows. Length of the head portion: 26.2 mm Length of the handle body: 180 mm Length of the tuft 10: 11.2 mm Thickness (base thickness) of the tufting base 20 of the head portion 2: 3.5 mm Diameter of the tufting hole (hole diameter): 1.4 mm Pitch between the tufting holes (pitch between holes): 1.05 mm Number of tufting holes: 35 Hair diameter: 170 μm for both the 16-branched hair filament and the 3-branched hair filament. Note that the conditions of each part are shown in FIG. 5.

[0041] In the toothbrush 1A, tuft 10a composed of 16-branched hair 4 is implanted in 8 tufting holes in the first region R11 on the left outer side and 8 tufting holes in the first region R12 on the right outer side of the tufted surface 20a. In 11 tufting holes on the tip side of the second region R2 inside the first regions R11 and R12 of the tufted surface 20a, tuft 10b composed of 3-branched hair 5 is implanted, and in 8 tufting holes on the rear end side of the second region R2, tuft 10a composed of 16-branched hair 4 is implanted.

[0042] (Example 2) As shown in FIG. 5, a toothbrush 1B was manufactured in the same manner as in Example 1, except that tuft 10b composed of 3-branched hair 5 was implanted in all 19 tufting holes in the second region R2.

[0043] (Example 3) As shown in FIG. 5, a toothbrush 1C was manufactured in the same manner as in Example 1, except that it has a head portion 2 with a shape such that the width of the tufting surface 20a is substantially the same from the tip side to the rear end side. The configuration of the head portion 2 of the toothbrush 1C different from the toothbrush 1A is as follows. Thickness (base thickness) of the tufting base 20: 4.0 mm Diameter of the tufting hole (hole diameter): 1.5 mm Pitch between the tufting holes (pitch between holes): 1.15 mm Number of tufting holes: 30

[0044] In toothbrush 1C, bristle bundles 10 are arranged in four rows from the tip to the rear end, and bristle bundles 10a consisting of 16-branched bristles 4 are planted in seven bristle holes in the first region R11 on the left outer side of the bristle surface 20a and in seven bristle holes in the first region R12 on the right outer side. In the second region R2 on the bristle surface 20a, which is inward from the first regions R11 and R12, bristle bundles 10b consisting of 3-branched bristles 5 are planted in 16 bristle holes arranged in two rows.

[0045] (Comparative Example 1) As shown in Figure 5, a toothbrush 1D was manufactured in the same manner as in Example 1, except that a bundle of bristles 10b consisting of three-branched bristles 5 was implanted in all of the bristle implantation holes (35 holes).

[0046] (Comparative Example 2) As shown in Figure 5, a toothbrush 1E was manufactured in the same manner as in Example 1, except that a bundle of bristles 10a consisting of 16 branched bristles 4 was implanted in all of the bristles (35) holes.

[0047] (Comparative Example 3) As shown in Figure 5, a toothbrush 1F was manufactured in the same manner as in Example 3, except that a bundle of bristles 10a consisting of 16 branched bristles 4 was implanted in all (30) of the bristle implantation holes.

[0048] (Comparative Example 4) As shown in Figure 5, a toothbrush 1G was manufactured in the same manner as in Example 3, except that bundles of saturated polyester bristles were planted in 16 bristle holes in the second region R2, which is inside the first regions R11 and R12 of the bristle surface 20a.

[0049] (Test Example 1: Softness Test) As shown in Figure 6, a sheet-type surface pressure gauge 12a (manufactured by Nitta Corporation, approximately 5.0 cm x 5.0 cm) was placed on the upper surface of a roughly cubic metal base 11 (length: approximately 10 cm, width: approximately 10 cm, height: approximately 10 cm).

[0050] Next, the entire bundle of bristles 10 of the head portion 2 of the toothbrush 1A to 1G was brought into contact with the surface of the sheet-like surface pressure gauge 12a, and the maximum value of the pressure P (g) was measured when pressure was applied at a constant speed of 0.1 mm / min along the protruding direction of the bristles 10, from the tip to the base, until the indentation amount was 1 mm.

[0051] To determine the pressure value, the area of ​​the pressing surface of the head part 2 (cm²)２ was calculated as follows. That is, as shown in FIG. 7, the area of the pressing surface 16 formed so as to contact the outer edge of the implanting hole was measured so that all the implanting holes of the tufts 10 implanted in the head portion 20 of the toothbrush 1A were included. The area of the pressing surface 16 of the head portion 2 having the shape of Examples 1 and 2 and Comparative Examples 1 and 2 was 1.62 cm ２ , and the area of the pressing surface 16 of the head portion 2 having the shape of Example 3 and Comparative Examples 3 and 4 was 1.65 cm ２ . After measuring multiple times, the maximum value (g / cm ２ ) of the pressure value per pressing surface 16 was calculated. The results are shown in FIG. 5.

[0052] Further, the difference (=P0 - P1) between the maximum value (P0) of the average pressure value of Comparative Example 2 in which all the hairs of the tuft 10 of the head portion 2 are 16-branched hairs 4 and the maximum value (P1) of the average pressure value of Examples 1 and 2 was described in FIG. 5 as the relative value of the pressure. Similarly, the difference (=P0 - P1) between the maximum value (P0) of the average pressure value of Comparative Example 3 in which all the hairs of the tuft 10 of the head portion 2 are 16-branched hairs 4 and the maximum value (P1) of the average pressure value of Examples 3 and Comparative Example 4 was described in FIG. 5 as the relative value of the pressure.

[0053] Further, FIG. 8 shows a schematic diagram of an image showing the pressurized state measured by the sheet-like surface pressure gauge 12a.

[0054] From the results shown in FIG. 5, for the toothbrushes 1A, 1B, and 1C of Examples 1 to 3, the maximum value of the average pressure value per pressing surface was 400 g / cm ２ or less. On the other hand, for the toothbrush 1D of Comparative Example 1 composed only of the tuft 10b made of 3-branched hairs 5 and the toothbrush 1G of Comparative Example 4 in which the second region R2 was made of saturated polyester hairs, the maximum value of the average pressure value per pressing surface exceeded 400 g / cm ２ .

[0055] Further, the relative value of the maximum value of the average pressure value of the toothbrushes 1A, 1B, and 1C of Examples 1, 2, and 3 with respect to the toothbrush 1E of Comparative Example 2 and the toothbrush 1F of Comparative Example 3 composed only of the tuft 10a made of 16-branched hairs 4 was 60 g / cm ２As follows, while it possesses a softness similar to a toothbrush composed solely of 16-branched bristles 4, the relative values ​​for toothbrush 1D of Comparative Example 1, which is composed solely of bristle bundles 10b consisting of 3-branched bristles 5, and toothbrush 1G of Comparative Example 4, in which the second region R2 is composed of saturated polyester bristles, are 90 g / cm³. ２ It exceeded [a certain limit] and had a hard texture.

[0056] In fact, the image results shown in Figure 8 show that in Comparative Example 4, a large pressure is generated near the second region R2 where saturated polyester fibers are arranged.

[0057] When brushing was performed in the mouth using toothbrushes 1A to 1C from Examples 1 to 3 and toothbrushes 1E and 1F from Comparative Examples 2 and 3, it was confirmed that in all cases, the tips of the bristle bundles 10 felt soft when they touched the gums, and pain to the gums was less likely to be felt. On the other hand, when brushing was performed similarly using toothbrush 1D from Comparative Example 1 and toothbrush 1G from Comparative Example 4, the tips of the bristle bundles 10 felt hard when they touched the gums. Therefore, with toothbrush 1 of the present invention, the maximum value of the average pressure measured by the method described in Test Example 1 was 400 g / cm². ２ The following adjustments have been made, and the value of P1 is 60 g / cm³ higher than the value of P0. ２ It can be seen that the soft texture is achieved by adjusting the following increases.

[0058] (Test Example 2: Durability (Slipperiness) Test) Five types of toothbrushes 1 were prepared in the same manner as in Example 3, except that the 16-branched bristles 4 used had core outer diameters (L2) of 11 μm, 15 μm, 18 μm, 22 μm, and 26 μm, as shown in Table 1.

[0059] The handle 3 of the toothbrush 1 was fixed at the finger rest (not shown), and as shown in Figure 9, the entire bundle of bristles 10 of the head 2 of the toothbrush 1 was brought into contact with the surface of the measuring instrument 13 (tribogear tactile meter TYPE 33, Shinto Kagaku Kagaku Co., Ltd.). The vertical load applied along the protruding direction of the bristles 10, from the tip to the base, was adjusted to 0.5, 1.0, 1.5, 2.0, and 3.0 N, and the toothbrush 1 was moved back and forth to measure the frictional force and coefficient of friction (μ). The frictional force and coefficient of friction were measured according to the manual attached to the measuring instrument 13. The above experiment shows that a larger coefficient of friction indicates less slipperiness, and a smaller coefficient of friction indicates easier slipperiness. The obtained results are shown in the graph in Figure 10. From the graph in Figure 10, in a toothbrush 1 in which a bristle bundle 10a consisting of 16 branched bristles 4 is planted in the first regions R11 and R12 of the bristle surface 20a of the head portion 2, and a bristle bundle 10b consisting of 3 branched bristles 5 is planted in the second region R2 of the bristle surface 20a, the coefficient of friction at low load was greatest when the outer diameter of the core portion was 11 μm. Therefore, it was inferred that when the outer diameter of the core portion of the 16 branched bristles is 11 μm, the tip portion becomes too soft, and the sheath portion, which has a larger outer diameter and is harder than the core portion, is more likely to come into contact with the teeth and gums. Accordingly, in the toothbrush 1 according to the present invention, by making the outer diameter of the core portion of the 16 branched bristles 4 15 μm or more, it is possible to make the softness when the tip of the bristle bundle 10 comes into contact with the teeth and gums more easily felt.

[0060] (Test Example 3: Durability (bristle splitting) test) Five types of toothbrushes 1, prepared in Test Example 2, were used, each having 16 branched bristles with core outer diameters (L2) of 11 μm, 15 μm, 18 μm, 22 μm, and 26 μm.

[0061] As shown in Figure 11, a predetermined-sized water tank 14 filled with water at 37±1℃ was prepared, and a corrugated sheet 15 (made of polyacetal (POM) resin) was submerged in the tank. Next, a toothbrush 1 was placed in the water of the water tank 14, and the entire bundle of bristles 10 of the head portion 2 of the toothbrush 1 was brought into contact with the surface of the corrugated sheet 15. The load applied vertically from the tip to the base of the bundle of bristles 10 along the protruding direction of the bundle of bristles 10 was adjusted to 300g, and the toothbrush 1 was moved back and forth 1000 times at a speed of 30 rpm. Next, the condition of the area around the branching portion 9a of the 16 branched bristles 4 after 1000 sliding cycles was observed, and the length (L4) of the branching portion 9a was measured before and after sliding and the difference in length (= (L4 after sliding) - (L4 before sliding)). The obtained results are shown in Table 2.

[0062]

[0063] As shown in Table 2, when the outer diameter of the core was 26 μm, the sheath portion 7a split and each core separated, resulting in a significantly longer branching portion 9a. Therefore, it can be seen that the durability of the toothbrush 1 according to the present invention can be further improved by adjusting the outer diameter of the core of the 16 branched bristles 4 to 22 μm or less.

[0064] (Test Example 4: Cleanability Evaluation Test) Cleanability evaluation tests were conducted on toothbrushes 1A, 1B, 1D, and 1E obtained in Examples 1 and 2 and Comparative Examples 1 and 2. For the cleanability evaluation test, artificial plaque was applied to a jaw model, and a robot was equipped with toothbrush 1 (1A, 1B, 1D, 1E) to brush five tooth surfaces from #3 to #7 of the jaw model (gingival recession model) for 3 seconds per tooth, with an average brushing pressure of 150g, a stroke of 20mm, and a speed equivalent to 150rpm. After brushing, the percentage of artificial plaque removed in the interdental spaces, tooth surfaces, and cervical areas was calculated. The results are shown in Table 3.

[0065]

[0066] As shown in Table 3, the toothbrushes 1A and 1B of Examples 1 and 2 demonstrated excellent cleaning performance, with a removal rate on the tooth surface, interdental spaces, and gingival margins similar to that of toothbrush 1D (Comparative Example 1), which was composed solely of three-branched bristles 5. In particular, toothbrushes 1A and 1B of Examples 1 and 2 showed superior cleaning performance on the tooth surface. On the other hand, toothbrush 1E, as in Comparative Example 2, which was composed solely of sixteen-branched bristles 4, had a low removal rate and inferior cleaning performance on all areas, including the tooth surface, interdental spaces, and gingival margins.

[0067] (Comparative Example 5) A toothbrush was prepared in the same manner as in Example 2, except that the diameter of the bristle implantation hole was changed to 1.5 mm and saturated polyester bristles were implanted in the second region R2 instead of the three-branched bristles 5.

[0068] Using toothbrush 1 obtained in Comparative Example 5, a cleaning power evaluation test was conducted according to Test Example 4. The results are shown in Table 4.

[0069]

[0070] As shown in Table 4, in Comparative Example 5, saturated polyester bristles were implanted in the second region R2, resulting in increased pressure and improved cleaning performance. However, when brushing was performed with a predetermined force, the tips of the bristle bundles felt hard when they touched the gums, and sometimes strong pain was felt in the gums during brushing.

[0071] 1 Toothbrush 2 Head 3 Handle 4 16-branched bristles 5 3-branched bristles 6a, 6b Core 7a, 7b Sheath 8a, 8b Core-sheath structure 9a Branching part 10, 10a, 10b Bristle bundle 11 Base 12a Sheet-type surface pressure gauge 13 Measuring instrument 14 Water tank 15 Corrugated sheet 16 Pressing surface 20 Bristle base 20a Bristle surface R11, R12 First region R2 Second region

Claims

1. A toothbrush in which, in a first region on the left and right outer sides of the bristle surface of the head portion where multiple bristle bundles are planted, multiple bristle bundles consisting of 16-branched bristles with 16 branches at the tip are planted, and in a second region on the bristle surface inside the first region, multiple bristle bundles consisting of 3-branched bristles with 3 branches at the tip are planted.

2. The toothbrush according to claim 1, wherein the first region includes regions where the outermost rows of bristles at both the left and right ends are erected.

3. The toothbrush according to claim 1, wherein the 16 branched bristles have a core-sheath structure consisting of 16 cores and a sheath surrounding them, and the tip has a branched portion consisting of the 16 cores exposed from the sheath, and the outer diameter of each core in the core-sheath structure is 15 to 22 μm.

4. When the entire bundle of bristles in the head section is pressed at a constant speed of 0.1 mm / min along the direction of protrusion of the bristles, from the tip to the base, until the amount of indentation is 1 mm, the maximum value of the average pressure is 400 g / cm². ２ The toothbrush according to claim 1, which is as follows:

5. When the entire bundle of hair in the head section is pressed at a constant speed of 0.1 mm / min along the direction of the protrusion of the hair bundle, from the tip to the base, until the indentation is 1 mm, the maximum value of the average pressure is defined as P1. When all the hairs in the multiple bundles of hair implanted in the head section are 16-branched hairs, and the same pressing is applied, the maximum value of the average pressure is defined as P0. When the value of P1 is 60 g / cm² higher than the value of P0, ２ The toothbrush according to claim 1, which has the following increase.

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