JPWO2017018340A1 - toothbrush - Google Patents

Abstract

  An object of the present invention is to provide a toothbrush that can efficiently remove dental plaque, has excellent cleaning feeling, and can ensure excellent breakage durability even when the open endurance is improved. A toothbrush having a plurality of bristle bundles (112) planted on the flocked surface (118a) of the head part (118), wherein the bristle bundle (112) has a taper part (121) that decreases in diameter toward the tip. ) And a tapered tooth (120) having a ratio B1 / A1 of the maximum stress B1 to the maximum stress A1 calculated by a predetermined stress calculation method of 1.0 to 1.9.

Description

The present invention relates to a toothbrush.
This application claims priority based on Japanese Patent Application No. 2015-147011 filed in Japan on July 24, 2015 and Japanese Patent Application No. 2015-150844 filed in Japan on July 30, 2015. The contents are incorporated herein.

  In particular, since it is difficult to remove plaque accumulated in gaps such as interdental portions and tooth neck portions, toothbrushes are required to have excellent plaque removability. The arrangement of the hair bundle and the specifications of each hair forming the hair bundle influence the plaque removability of the toothbrush. As the hair that can effectively remove the plaque accumulated in the gaps between the interdental part and the neck part, and has excellent cleaning feeling, a tapered part with a tapered part that decreases in diameter toward the tip is known. It has been.

  In addition, the toothbrush is required to have sufficient opening resistance in addition to plaque removability. By using a toothbrush having sufficient opening resistance, it can be used continuously for a certain period of time, so that it is possible to suppress an excessive increase in the frequency of replacement of the toothbrush. In particular, the processing technique for producing tapered bristles is complex and expensive, and toothbrushes with tapered bristles are expensive, so that sufficient open-end durability is required so that the frequency of toothbrush replacement does not increase excessively. .

  In addition to the arrangement of the hair bundles and the specifications of the hair, the material of the hair also affects the opening resistance of the toothbrush. For example, a hair made of polytrimethylene terephthalate (PTT) is known as a hair having excellent hair opening durability (for example, Patent Document 1).

International Publication No. 2005/039355

  However, when the hair used for improving the openness of the hair formed of PTT or the like is used continuously, the hair may be broken in the vicinity of the hair base (the portion where the opening surface of the flock hole is located). Even if the opening of the hair is suppressed, it becomes difficult to sufficiently enhance the durability as a toothbrush if the bristles are easily broken. As described above, in the toothbrush, in addition to being able to efficiently remove plaque and being excellent in cleaning feeling, it is important to be able to ensure excellent breakage durability even when the open endurance is increased. .

The first object of the present invention is to provide a toothbrush that can effectively remove dental plaque, has an excellent cleaning feeling, and can ensure excellent breaking durability even when the flocking durability is enhanced.
The second object of the present invention is to provide a toothbrush that can ensure excellent breakage durability even when the open endurance is increased.

The first aspect of the present invention has the following configuration.
[1] A toothbrush provided with a brush portion formed by implanting a plurality of hair bundles on the hair-planting surface of the head portion, wherein the hair bundle is provided with a tapered portion whose diameter decreases toward the tip at the tip portion. And a taper hair whose ratio B1 / A1 of the maximum stress B1 to the maximum stress A1 calculated by the stress calculation method having the following step (a1) and the following step (b1) is 1.0 to 1.9. ,toothbrush.
(A1) Displacement x1 (mm) of the tip with respect to the base of the tapered hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B1) An engineering simulation of a state in which the tip of the taper hair is displaced by the displacement amount x1 (mm) in a direction perpendicular to the axial direction of the taper hair, and the maximum stress generated closer to the base than the taper portion of the taper hair A1 and the maximum stress B1 generated at the tapered portion are calculated.
[2] The length of the tapered portion is 3 to 11.5 mm, and the position of the boundary between the base portion and the tapered portion of the tapered hair is equal to the position of the flocked surface, or the base portion is outside the flocked surface. The toothbrush according to [1], which is located.
[3] The toothbrush according to [1] or [2], wherein a diameter of a portion 0.1 mm from a tip of the tapered portion is 0.07 mm or less.
[4] The toothbrush according to any one of [1] to [3], wherein the tapered bristles are formed of polytrimethylene terephthalate.

The second aspect of the present invention has the following configuration.
[5] A toothbrush comprising a brush portion formed by implanting a plurality of hair bundles on the hair-planting surface of the head portion, wherein the hair bundle is at a position closer to the base by 0.1 mm or more from the hair tip. Toothbrush comprising a bristle having a region having a cross-sectional area equal to or less than 14% of the cross-sectional area of the base and extending from the base toward the tip and having a region having a larger cross-sectional area than the thin-diameter .
[6] With respect to the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following step (a2) and the following step (b2) in the above hair, A2> 0 and B2> 0, [5] The toothbrush described.
(A2) Displacement amount x2 (mm) of the tip with respect to the base of the hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B2) Engineering simulation of a state in which the tip of the bristles is displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the bristles, and the maximum stress concentration portion that occurs closest to the base in the bristles The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side from the stress A2 are calculated.
[7] The maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following step (a2) and the following step (b2) in the hair, B2 ≧ A2> 0, toothbrush.
(A2) Displacement amount x2 (mm) of the tip with respect to the base of the hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B2) Engineering simulation of a state in which the tip of the bristles is displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the bristles, and the maximum stress concentration portion that occurs closest to the base in the bristles The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side from the stress A2 are calculated.
[8] The hair according to any one of [5] to [7], wherein the hair is a tapered hair provided with a tapered portion that is reduced in diameter toward the tip, and the tapered portion has the thin diameter portion. toothbrush.
[9] The toothbrush according to any one of [5] to [8], wherein the bristles are formed of polytrimethylene terephthalate.
[10] The toothbrush according to [8] or [9], comprising a tapered bristle having a ratio B2 / A2 of the maximum stress B2 to the maximum stress A2 of 1.0 to 1.9.
In the second aspect, when the hair is a tapered hair, the maximum stress A2 and the maximum stress B2 are the same as the maximum stress A1 and the maximum stress B1 of the first aspect.

In the toothbrush according to the first aspect of the present invention, plaque can be efficiently removed and the cleaning feeling is excellent, and excellent breakage durability is ensured even when the flocking durability is increased.
In the toothbrush according to the second aspect of the present invention, it is possible to ensure excellent breakage durability even when the hair opening durability is increased.

It is the side view which showed an example of the toothbrush of the 1st aspect of this invention. It is the top view to which the head part of the toothbrush of FIG. 1 was expanded. It is sectional drawing to which one bristle bundle vicinity in the head part of the toothbrush of FIG. 1 was expanded. It is a schematic diagram explaining the process (a1) of the stress calculation method in the 1st aspect of this invention. It is the side view which showed an example of the toothbrush of the 2nd aspect of this invention. It is the top view to which the head part of the toothbrush of FIG. 5 was expanded. It is sectional drawing to which the one hair | bristle bundle vicinity in the head part of the toothbrush of FIG. 5 was expanded. It is a schematic diagram explaining the process (a2) of the stress calculation method in the 2nd aspect of this invention. It is the side view which showed the other example of the bristle in the toothbrush of the 2nd aspect of this invention. It is the side view which showed the other example of the bristle in the toothbrush of the 2nd aspect of this invention. It is the side view which showed the other example of the bristle in the toothbrush of the 2nd aspect of this invention.

[First embodiment]
Hereinafter, an example of the toothbrush of the 1st aspect of this invention is shown and demonstrated.
The toothbrush 11 of this embodiment is provided with the brush body 122 formed with the handle body 110 and the several hair | bristle bundle 112 planted by the handle body 110, as shown in FIGS. 1-3. The handle body 110 includes a rod-shaped handle portion 114, a neck portion 116 that extends from the tip of the handle portion 114 and is thinner than the handle portion 114, and a head portion 118 provided at the tip of the neck portion 116. Yes. The plurality of hair bundles 112 are implanted on the flocked surface 118 a of the head portion 118.

A well-known aspect can be employ | adopted for the handle body in a 1st aspect.
In the handle body 110, the handle portion 114, the neck portion 116, and the head portion 118 are integrally formed.

The handle portion 114 is a portion that is gripped by a hand during brushing and has a rod shape.
The cross-sectional shape perpendicular to the axial direction (length direction) in the handle portion is not particularly limited, and examples thereof include a shape in which a rectangular corner is notched in a round shape, a rectangular shape, and a circular shape.
The thickness and length of the handle portion can be appropriately designed according to the subject who uses the toothbrush.

The neck portion 116 has a bar shape thinner than the handle portion 114 in plan view.
The length, width, and thickness of the neck portion are not particularly limited, and can be appropriately designed according to the subject who uses the toothbrush.

The head portion 118 is a portion where a plurality of hair bundles 112 are implanted at the tip of the neck portion 116. An upper surface of the head portion 118 is a flocking surface 118 a for planting the hair bundle 112. The shape of the head portion 118 is a plate shape in which a rectangular corner portion that is long in the axial direction in a plan view is cut out.
The length, width, and thickness of the head portion are not particularly limited, and can be appropriately designed according to the subject who uses the toothbrush.

  The material for forming the handle body is selected in consideration of the rigidity and mechanical characteristics required of the toothbrush, and for example, a high-hardness resin having a flexural modulus (JIS K7203) of 500 MPa to 3000 MPa can be used. . Examples of the high-hardness resin include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), polystyrene (PS), acrylonitrile butadiene styrene resin (ABS). ), Cellulose propionate (CP), polyarylate, polycarbonate, acrylonitrile / styrene copolymer resin (AS), polyacetal resin (POM), and the like. One of these resins may be used alone, or two or more thereof may be used in appropriate combination. In addition, the head portion, the neck portion, and the handle portion may be partially or wholly covered with a flexible resin such as an elastomer.

The brush portion 122 is formed by a plurality of hair bundles 112 planted on the hair transplantation surface 118 a of the head portion 118.
In the toothbrush of a 1st aspect, the aspect which implants a hair | bristle bundle in the flock surface of a head part is not specifically limited. In the toothbrush 11 of this example, three hair bundles 112 are implanted in the width direction near the front end and the rear end of the flocked surface 118a, respectively, and the four hair bundles 112 are arranged in the width direction in an area between them. In addition, 24 hair bundles 112 are implanted so that six hair bundles 112 are arranged in the axial direction.

The hair bundle 112 is formed by bundling a plurality of tapered hairs 120.
The shape of the hair bundle 112 is not particularly limited, and may be columnar or prismatic.
The hair length and thickness of the hair bundle 112 can be determined in consideration of the hair and waist required for the hair bundle 112.

The hair bundle 112 of this example is planted on the flocked surface 118a by the flat wire type flocking method. Specifically, as shown in FIG. 3, a plurality of taper hairs 120 having taper parts 121 at both ends are bundled and folded in two along a flat line 124, and formed on the flocked surface 118 a of the head part 118. The hair bundle 112 is implanted by being driven into the flocked hole 123.
In addition, the method of planting a hair | bristle bundle on the hair transplantation surface of a head part is not limited to a flat wire type hair transplantation method, A heat welding type | system | group planting method, an in-mold method, etc. may be sufficient.

The taper bristles 120 are calculated by a stress calculation method in which a taper portion 121 having a diameter reduced toward the tip is provided in a portion closer to the tip than the straight portion 119, and has a step (a1) and a step (b1) described later. It is a taper hair (henceforth taper hair (X1)) whose ratio B1 / A1 of maximum stress B1 to maximum stress A1 is 1.0-1.9. In addition, a taper part means the part from the position where the diameter in a taper hair begins to become small to a front-end | tip.
The toothbrush of the 1st aspect has a hair bundle provided with taper hair (X1), can remove plaque efficiently, is excellent in cleaning feeling, and has excellent breakage even when it has improved open-end durability. Durability is ensured.

The tapered hairs 120 forming the hair bundle 112 in this example are all tapered hairs (X1). In addition, you may use for the hair | bristle bundle in the toothbrush of the 1st aspect of this invention combining taper hair (X1), and hairs other than taper hair (X1), such as straight hair.
The ratio of the number of tapered hairs (X1) to the total number of hairs forming the hair bundle is preferably 50% or more, more preferably 75% or more, and particularly preferably 100%.

The ratio B1 / A1 in the tapered hair is obtained by calculating the maximum stress A1 and the maximum stress B1 by a stress calculation method having the following step (a1) and the following step (b1).
(A1) The displacement x1 (mm) of the tip relative to the base of the tapered hair in the surface direction of the flocked surface when the brush portion is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush portion. To do.
(B1) An engineering simulation of a state in which the tip of the taper hair is displaced by the displacement amount x1 (mm) in a direction perpendicular to the axial direction of the taper hair, and the maximum stress generated closer to the base than the taper portion of the taper hair A1 and the maximum stress B1 generated at the tapered portion are calculated.

(Step (a1))
For example, in the case of the toothbrush 11, as shown in FIG. 4, the brush portion 122 is pressed against the spherical surface 1100 having a radius of 85 mm, and moved and rubbed in the axial direction of the handle body 110. Then, in a state where a load of 200 g is applied to the brush portion tip 122a by rubbing the hair bundle 112, the displacement amount x1 (mm) of the tip 120a relative to the base portion 120b of the tapered hair 120 in the surface direction of the flocked surface 118a of the head portion 118. ), That is, the amount of bending of the tapered hair 120 is measured.

“A load of 200 g is applied to the tip of the brush portion” means that the reaction force applied to the tip of the brush portion is 200 g in a state where the brush portion of the toothbrush is rubbed against the spherical surface. That is, for example, when the brush portion of the toothbrush is rubbed against the balance, it means that a force that makes the scale of the balance become 200 g is applied to the tip of the brush portion.
The “taper base” is a portion of the taper hair that is not tapered, and means a portion corresponding to the position of the flocked surface of the head portion of the portion having the brush shape before the taper processing. In the case of a tapered bristle whose both ends are tapered, a portion corresponding to the position of the flocked surface of the head portion is the base portion of the straight portion of the intermediate portion in the longitudinal direction of the tapered bristle.

  The material of the member having a spherical surface that rubs the brush portion is not particularly limited, and examples thereof include a material having rigidity equivalent to gums.

(Step (b1))
If the displacement x1 (mm) of the taper hair 120 in the toothbrush 11 is measured in the step (a1), the position corresponding to the base of the taper hair is fixed with respect to the taper hair having the same shape and material as the taper hair 120. Then, an engineering simulation is performed in which the tip of the tapered hair is displaced by a displacement amount x1 (mm) in a direction perpendicular to the axial direction of the tapered hair. At this time, in the tapered hair in the engineering simulation, stress concentration is seen in the tapered portion and the straight portion closer to the base than the tapered portion. In the engineering simulation, the maximum stress generated nearer the base than the tapered portion of the tapered hair is calculated as the maximum stress A1, and the maximum stress generated in the tapered portion is calculated as the maximum stress B1.

  As the engineering simulation, for example, a three-dimensional finite element method (FEM) analysis using LS-DYNA (analysis software, manufactured by LSTC) can be used. The engineering simulation can be performed by inputting, as conditions for the tapered hair, the shape of the tapered hair (hair length, length of the tapered portion, tip diameter, etc.) and the Young's modulus of the material used for the tapered hair.

The ratio B1 / A1 of the tapered hair (X1) is 1.0 to 1.9, preferably 1.0 to 1.7, and more preferably 1.5 to 1.7. When the ratio B1 / A1 is within the above range, it is possible to efficiently remove the plaque in the narrow portion, and it is excellent in cleaning feeling, and excellent breakage durability can be ensured even when the hair opening durability is enhanced.
The ratio B1 / A1 of the taper hair (X1) can be adjusted by, for example, the length and material of the taper portion.

The axial length L1 (FIG. 3) of the tapered portion of the tapered hair (X1) is preferably 3 to 11.5 mm, and more preferably 4 to 7 mm. If the length of the taper portion is within the above range, it becomes easy to ensure excellent breakage resistance. If the length of the taper portion is equal to or greater than the lower limit value, the taper portion easily enters a gap such as an interdental portion or a tooth neck portion, and the plaque accumulated in the gap is easily scraped off. If the length of the tapered portion is equal to or less than the upper limit value, it becomes easy to write down the plaque in the narrow portion due to the appropriate rigidity of the hair.
5-100% is preferable and, as for the ratio of the axial direction length L1 of the taper part with respect to the bristle length of taper hair (X1), 20-100% is more preferable.
The average length in the axial direction of the tapered portion of the tapered hair (X1) forming the hair bundle is preferably 3 to 11.5 mm, and more preferably 4 to 7 mm.

  In the tapered hair (X1), it is preferable that the position of the boundary between the straight portion and the tapered portion is equal to the position of the flocked surface of the head portion, or the straight portion is located outside the flocked surface. That is, it is preferable that the taper hair (X1) is hidden by the straight part being accommodated in the flock hole of the head part, or the straight part is exposed from the head part.

In the taper hair (X1), the diameter of the portion 0.1 mm away from the tip of the taper portion to the base side (hereinafter also referred to as the tip diameter) is preferably 0.07 mm or less, more preferably 0.02 mm or less, and More preferably, the thickness is 01 to 0.02 mm. If the tip diameter of the taper hair (X1) is 0.02 mm or less, the taper part is likely to enter a gap such as an interdental part or a tooth neck part, and it becomes easy to scrape the plaque accumulated in the gap. It is easy to obtain excellent feeling of brushing.
In the first aspect, it is preferable that the average value of the tip diameters of the tapered hairs (X1) forming the hair bundle is 0.07 mm or less.

  The average diameter of the straight portion of the taper hair (X1) can be determined in consideration of the material and the like. When the cross section of the straight portion is circular, for example, 4 to 10 mil (1 mil = 1/1000 inch = 0.0254 mm) ). The cross-sectional shape of the tapered hair may be any shape.

  The average length H1 (FIG. 3) of the taper hair (X1), that is, the average length from the position corresponding to the flocked surface to the tip of the taper hair (X1) is not particularly limited and is, for example, 5 to 15 mm. Can do.

  The material for forming the tapered hair is not particularly limited, and polyester such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN); 612 nylon, 610 nylon Polyamides such as polyethylene; polyolefins such as polyethylene (PE) and polypropylene (PP). Among these, PTT is preferable in terms of excellent hair opening resistance. In the first aspect of the present invention, even when the taper hair is PTT hair, it is possible to ensure excellent breakage resistance.

(Production method)
The manufacturing method of the toothbrush of the 1st aspect of this invention is not specifically limited, A well-known method is employable.
Examples of the method for manufacturing the handle body include injection molding. As a method for producing the tapered hair (X1), for example, both ends of the hair obtained by spinning are dipped in a solution such as an acid or an alkali solution for a predetermined time, and are pulled up to neutralize, wash with water, etc. The method of performing etc. are mentioned. Examples of the method for planting the hair bundle include a flat wire type flocking method, a heat welding type flocking method, an in-mold method, and the like.

  In the toothbrush according to the first aspect of the present invention described above, the tapered hair (X1) is provided as the hair for forming the hair bundle. It can be removed efficiently and has an excellent cleaning feeling. Further, the hair is provided with a tapered hair (X1) having a ratio B1 / A1 of 1.0 to 1.9, and the stress concentration portion at the time of brushing is at two locations near the base of the tapered hair and the tapered portion. Therefore, it is possible to suppress the stress from concentrating only in the vicinity of the base of the hair and locally accumulating fatigue in that portion. Therefore, in the 1st aspect of this invention, even when the taper hair (X1) is formed with PTT etc. and the hair opening durability is improved, the outstanding fracture durability can be ensured. In particular, when the tapered hair (X1) is formed of PTT, it is possible to achieve both excellent opening resistance and breakage durability.

[Second embodiment]
The toothbrush of the 2nd aspect of this invention is equipped with the brush part formed by planting several hair | bristle bundles on the flocking surface of a head part. The bristle bundle in the toothbrush according to the second aspect of the present invention is provided with a small-diameter portion having a cross-sectional area of 14% or less of the cross-sectional area of the base at a position near the base by 0.1 mm or more from the tip of the bristle. The hair is provided with a region extending from the base portion toward the tip and having a region having a larger cross-sectional area than the narrow-diameter portion.
In the hair having such a small diameter portion, when a force is applied in a direction perpendicular to the axial direction with respect to the hair tip, a stress concentration portion is generated in the vicinity of the base and on the tip side. Thereby, it is suppressed that stress concentrates only in the vicinity of the base part of the hair, and fatigue accumulates locally in that part. Therefore, even when the hair is made of PTT or the like and the hair opening durability is enhanced, excellent breaking durability can be ensured.

Hereinafter, an example of the toothbrush of the 2nd aspect of this invention is shown and demonstrated.
As shown in FIGS. 5 to 7, the toothbrush 21 of the present embodiment includes a handle body 210 and a brush portion 224 formed of a plurality of hair bundles 212 implanted in the handle body 210. The handle body 210 includes a rod-shaped handle portion 214, a neck portion 216 that extends from the tip of the handle portion 214, and is thinner than the handle portion 214, and a head portion 218 provided at the tip of the neck portion 216. Yes. The plurality of hair bundles 212 are implanted on the flocked surface 218a of the head portion 218.

A well-known aspect can be employ | adopted for the handle body in a 2nd aspect.
In the handle body 210, the handle portion 214, the neck portion 216, and the head portion 218 are integrally formed.

The handle portion 214 is a portion that is gripped by a hand during brushing and has a rod shape.
The cross-sectional shape perpendicular to the axial direction (length direction) in the handle portion is not particularly limited, and examples thereof include a shape in which a rectangular corner is notched in a round shape, a rectangular shape, and a circular shape.
The thickness and length of the handle portion can be appropriately designed according to the subject who uses the toothbrush.

The neck portion 216 has a bar shape thinner than the handle portion 214 in plan view.
The length, width, and thickness of the neck portion are not particularly limited, and can be appropriately designed according to the subject who uses the toothbrush.

The head portion 218 is a portion where a plurality of hair bundles 212 are provided at the tip of the neck portion 216. An upper surface of the head portion 218 is a flocking surface 218 a for planting the hair bundle 212. The shape of the head portion 218 is a plate shape with rounded corners that are long in the axial direction in plan view.
The length, width, and thickness of the head portion are not particularly limited, and can be appropriately designed according to the subject who uses the toothbrush.

  The material for forming the handle body in the second aspect is selected in consideration of the rigidity and mechanical characteristics required for the toothbrush, and for example, a high-hardness resin having a flexural modulus (JIS K7203) of 500 MPa to 3000 MPa. Can be used. Examples of the high-hardness resin include the high-altitude resins mentioned in the first embodiment. Polybutylene terephthalate (PBT) may also be used. One of these resins may be used alone, or two or more thereof may be used in appropriate combination. In addition, the head portion, the neck portion, and the handle portion may be partially or wholly covered with a flexible resin such as an elastomer.

The brush portion 224 is formed of a plurality of hair bundles 212 planted on the hair transplant surface 218a of the head portion 218.
In the toothbrush of a 2nd aspect, the aspect which implants a hair | bristle bundle in the flock surface of a head part is not specifically limited. In the toothbrush 21 of this example, three hair bundles 212 are implanted in the width direction near the leading end and the rear end of the flocked surface 218a, respectively, and four hair bundles 212 are arranged in the width direction in an area between them. In addition, 24 hair bundles 212 are implanted so that six hair bundles 212 are arranged in the axial direction.

The hair bundle 212 is formed by bundling a plurality of hairs 220.
The shape of the hair bundle 212 is not particularly limited, and may be cylindrical or prismatic.
The hair length and thickness of the hair bundle 212 can be determined in consideration of the hair and waist required for the hair bundle 212.

The hair bundle 212 of this example is planted on the flocked surface 218a by the flat wire type flocking method. Specifically, as shown in FIG. 7, a plurality of bristles 220 are bundled and folded in half with a flat wire 226 and driven into a flocked hole 228 formed on a flocked surface 218a of the head portion 218. A hair bundle 212 is implanted.
In addition, the method of planting a hair | bristle bundle on the hair-planting surface of a head part is not limited to a flat wire-type hair transplanting method, A heat welding type | formula hair-planting method, an in-mold method, etc. may be sufficient.

In the second aspect, it is preferable that the hair having a small diameter portion is a tapered hair.
The bristles 220 are tapered bristles provided with tapered portions 221 that are reduced in diameter toward the tip at both ends of the straight portion 219. The tapered portion 221 of the bristles 220 is provided with a small-diameter portion 222 having a cross section of 14% or less of the cross-sectional area of the base portion 220b at a position closer to the base portion 220b by 0.1 mm or more from the tip 220a. Moreover, since the hair | bristle 220 is provided with the straight part 219, it has the area | region where a cross-sectional area is larger than the thin diameter part 222 extended toward the front-end | tip 220a from the base 220b.
In the second aspect, the cross-sectional area of the base means a cross-sectional area of a cross section when the base of the hair is cut in a direction perpendicular to the axial direction. The same applies to the cross-sectional area of the small-diameter portion.

  In a tapered hair having a small diameter portion in the tapered portion, when the ratio of the cross-sectional area at a position of 0.1 mm in the axial direction from the front end of the hair to the cross-sectional area of the base is 14%, the front end of the hair in the tapered portion The position of 0.1 mm in the axial direction is the small diameter portion. Further, when the ratio of the cross-sectional area at the position of 0.1 mm in the axial direction from the front end of the hair to the cross-sectional area of the base is less than 14%, from the position of 0.1 mm in the axial direction from the front end of the hair at the tapered portion. The portion up to the position where the ratio is 14% is the small diameter portion.

  In the case of tapered hair having a small diameter portion in the tapered portion, the ratio of the cross-sectional area at a position of 0.1 mm in the axial direction from the front end of the hair to the cross-sectional area of the base is 14% or less, 0.1 to 14% Is preferred.

  The aspect of the small diameter portion is not particularly limited, and for example, the diameter decreases toward the hair tip, such as the narrow diameter portion 222 provided in the taper portion 221 of the hair 220, and the outer peripheral surface is seen in a side view. The aspect which has become the linear form inclined with respect to the axial direction is mentioned. Moreover, in the narrow diameter part 222 in the hair 220, it inclines so that both sides of an outer peripheral surface may mutually approach in a side view. However, the aspect of the small diameter portion is not limited to this aspect, and may be an aspect in which only one side of the outer peripheral surface is inclined in a side view.

Moreover, as an aspect of a thin diameter part, it is not limited to the aspect provided in the taper part in a taper hair. For example, the narrow-diameter portion is formed by denting the outer peripheral surface of the bristle over the entire circumference in the circumferential direction so that both sides of the outer circumferential surface of the bristle are recessed in an arc shape when viewed from the side. It may be. Moreover, the aspect formed by denting the outer peripheral surface of the bristle may be sufficient as it may become the shape where the one side of the outer peripheral surface of the bristle was dented in circular arc shape in side view. When the thin-diameter portion has such an aspect, the thin-diameter portion can be positioned closer to the base than the position of 0.1 mm from the tip of the hair.
Moreover, in the case of the narrow diameter part of these aspects, the ratio of the cross-sectional area of the small diameter part with respect to the cross-sectional area perpendicular | vertical to the axial direction of a base is 14% or less, and 0.1-14% is preferable.

  The number of small diameter portions in one hair is one in the hair 220, but may be two or more. As the number of small-diameter portions in one hair increases, the number of stress concentration portions when a force is applied to the tip of the hair in the direction perpendicular to the axial direction increases. For example, when one hair has two small diameter portions, when a force is applied to the tip of the hair in the direction perpendicular to the axial direction, the vicinity of the base and the two small diameter portions or the vicinity thereof, respectively Stress concentration parts occur in a total of three locations.

In the second aspect, the hair having a small diameter portion may be any hair having a small diameter portion, and is not limited to a tapered hair. The bristle bundle in the toothbrush of the second aspect may be used in combination with a bristle having a small diameter portion and a bristle having no small diameter portion such as straight hair.
The ratio of the number of hairs having a small diameter portion to the total number of hairs forming the hair bundle is preferably 50% or more, more preferably 75% or more, and particularly preferably 100%.

  In the hair having a small diameter portion in the second aspect, when the maximum stress A2 and the maximum stress B2 are calculated by the stress calculation method including the step (a2) and the following step (b2) described later, A2> 0 and B2 > 0 and preferably B2 ≧ A2> 0.

Hereinafter, the stress calculation method will be described. The stress calculation method in the second aspect includes the following step (a2) and step (b2).
(A2) Displacement x2 (mm) of the tip with respect to the base of the bristles in the surface direction of the flocked surface of the toothbrush when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush Measure.
(B2) Engineering simulation of a state in which the tip of the bristles is displaced by a displacement amount x2 (mm) in a direction perpendicular to the axial direction of the bristles, and the maximum stress of the stress concentration portion that occurs closest to the base in the bristles A2 and the maximum stress B2 of the stress concentration portion generated on the tip side than that are calculated.

(Step (a2))
For example, in the case of the toothbrush 21, as shown in FIG. 8, the brush portion 224 is pressed against a spherical surface 2100 having a radius of 85 mm, and moved and rubbed in the axial direction of the handle body 210. Then, in a state in which a load of 200 g is applied to the brush portion tip 224a by rubbing the hair bundle 212, the displacement amount x2 (mm) of the tip 220a relative to the base portion 220b of the bristle 220 in the surface direction of the flocked surface 218a of the head portion 218. ), That is, the amount of bending of the bristle 220 is measured.

“A load of 200 g is applied to the tip of the brush portion” means that the reaction force applied to the tip of the brush portion is 200 g in a state where the brush portion of the toothbrush is rubbed against the spherical surface. That is, for example, when the brush portion of the toothbrush is rubbed against the balance, it means that a force that makes the scale of the balance become 200 g is applied to the tip of the brush portion.
The “base part of the hair” means a part corresponding to the position of the flocked surface of the head part in the part where the diameter of the hair is not maximized without being tapered.

  The material of the member having a spherical surface that rubs the brush portion is not particularly limited, and examples thereof include a material having rigidity equivalent to gums.

(Step (b2))
If the displacement x2 (mm) of the bristle 220 in the toothbrush 21 is measured in the step (a2), the position corresponding to the base of the bristle is fixed for the bristle having the same shape and material as the bristle 220. Then, an engineering simulation is performed in which the tip of the hair is displaced by a displacement amount x2 (mm) in a direction perpendicular to the axial direction of the hair. At this time, stress concentration is observed in the hair in the engineering simulation in the vicinity of the base portion and the narrow diameter portion or the vicinity of the narrow diameter portion on the tip side. In the engineering simulation, the maximum stress at the stress concentration portion that is closest to the base portion, that is, the maximum stress at the stress concentration portion near the base portion is defined as the maximum stress A2, and the maximum stress at the stress concentration portion that is generated on the tip side is set as the maximum stress B2. Calculate each. When two or more small-diameter portions are provided in the hair and two or more stress concentration portions are seen in addition to the stress concentration portion in the vicinity of the base portion, each stress concentration portion other than the stress concentration portion in the vicinity of the base portion The maximum stress B2 is calculated.

  As the engineering simulation, the same one as mentioned in the first aspect can be used.

The relationship between the maximum stress A2 and the maximum stress B2 can be adjusted, for example, by adjusting the ratio of the cross-sectional area of the small diameter portion to the cross-sectional area of the base portion in the hair. If the hair is tapered, it can be adjusted by adjusting the tip diameter of the tapered hair, the length of the tapered portion, and the like.
In the second embodiment, the tip diameter of the tapered hair means a diameter at a position 0.1 mm away from the tip of the tapered hair toward the base side.

When the hair is a tapered hair, the length L2 (FIG. 7) in the axial direction of the tapered portion is preferably 1 to 15 mm, and more preferably 3 to 7 mm. If the length of the taper portion is within the above range, it becomes easy to ensure excellent breakage resistance. If the length of the taper portion is equal to or greater than the lower limit value, the taper portion easily enters a gap such as an interdental portion or a tooth neck portion, and the plaque accumulated in the gap is easily scraped off. If the length of the taper portion is equal to or less than the upper limit value, the rigidity (stiffness) of the hair is ensured and it becomes easy to scrape plaque. In addition, the hair tips can be prevented from opening easily by repeated use.
When the bristles are tapered hairs, the ratio of the length L2 in the axial direction of the tapered portion to the bristles of the tapered hair is preferably 5 to 100%, and more preferably 20 to 100%.
When the hair is a tapered hair, the average length in the axial direction of the tapered portion of the tapered hair forming the hair bundle is preferably 1 to 15 mm, and more preferably 3 to 7 mm.

When the hair is a tapered hair, the tapered hair preferably has a tip diameter of 0.01 mm to 0.07 mm. If the tip diameter of the taper hair is within the above range, a stress concentration part is generated in the narrow diameter part located on the tip side of the taper part when a force is applied to the tip of the taper hair in the direction perpendicular to the axial direction. Since the stress of the base portion is dispersed in the narrow diameter portion or the vicinity thereof, sufficient breakage durability is easily secured.
When the hair is a tapered hair and the relationship between the maximum stress A2 and the maximum stress B2 is B2 ≧ A2> 0, the tip diameter of the tapered hair is more preferably 0.01 to 0.03 mm.
In the second aspect, when the bristles are tapered hairs, the average value of the tip diameters of the tapered hairs forming the hair bundle is preferably 0.01 mm to 0.07 mm.

  The diameter of the base in the hair can be determined in consideration of the material and the like. When the cross section of the base is circular, for example, 4 to 10 mil (1 mil = 1/1000 inch = 0.0254 mm), more preferably 5 -8 mils. In addition, the cross section of the hair may be a polygon and is not limited to a circle.

  The average hair length H2 of the hair (FIG. 7), that is, the average length from the position corresponding to the flocked surface of the hair to the tip is not particularly limited, and can be, for example, 5 to 15 mm.

  The material for forming the hair is not particularly limited, and examples thereof include the same materials as those mentioned in the first embodiment. Among these, PTT is preferable in terms of excellent hair opening resistance. In the second aspect, even if the hair is PTT hair, it is possible to ensure excellent breakage resistance.

(Production method)
The manufacturing method of the toothbrush of a 2nd aspect is not specifically limited, A well-known method is employable.
Examples of the method for manufacturing the handle body include injection molding. Examples of the method for producing tapered hair as the hair for use include the same methods as those described in the first embodiment. As a method of planting the hair bundle, a flat wire type planting method, a heat welding type planting method, an in-mold method, and the like can be used as in the first embodiment.

In the toothbrush according to the second aspect of the present invention described above, the bristle bundle has a small-diameter portion having a cross-sectional area of 14% or less of the cross-sectional area of the base portion at a position closer to the base portion by 0.1 mm or more from the hair tip. Has hair for having. Moreover, the said hair has an area | region with a larger cross-sectional area than a thin diameter part extended toward a front-end | tip from a base. As a result, in the toothbrush of the second aspect, a plurality of stress concentrating portions are generated near the base portion and the tip end side of the bristles at the time of brushing, so that stress concentrates only on the vicinity of the base portion of the bristles. Accumulation of repeated local fatigue is suppressed. Therefore, in the 2nd aspect, even when the hair is formed with PTT etc. and the hair opening durability is improved, the outstanding fracture durability can be ensured. In particular, when the hair is made of PTT, it is possible to achieve both excellent hair opening durability and broken hair durability.
In addition, in the second aspect of the present invention, if taper hair is used as the hair having a small-diameter portion in particular, it is possible to efficiently remove plaque deposited in the gaps between the interdental portion and the cervical portion and the like. A toothbrush that provides a clean feeling.

The toothbrush according to the second aspect of the present invention is not limited to the toothbrush 21 described above. For example, the toothbrush of the 2nd aspect may be a toothbrush provided with the bristle 220A illustrated in FIG.
The bristles 220A are tapered bristles provided with a taper portion 221A whose diameter decreases toward the tip so that one side of the outer peripheral surface approaches the other side in a side view when viewed from the side. The taper portion 221A of the bristles 220A has a small-diameter portion 222A having a cross-sectional area of 14% or less of the cross-sectional area of the base at a position closer to the base by 0.1 mm or more from the tip 220a, like the bristles 220.

  In the toothbrush provided with the bristles 220A, the stress concentration portion of the bristles 220A is generated in the vicinity of the narrow diameter portion 222A and the front end side of the bristles 220A at the time of brushing, and the repeated repeated accumulation of fatigue near the base portion is suppressed. Therefore, even when the hair opening durability is increased, excellent breakage durability can be ensured.

Moreover, the toothbrush provided with the bristle 220B illustrated in FIG. 10 may be sufficient as the toothbrush of a 2nd aspect.
The bristle 220B is provided with a small-diameter portion 222B formed by denting the outer circumferential surface of the bristle over the entire circumference in the circumferential direction so that both sides of the outer circumferential surface are recessed in an arc shape in a side view. It has been. The small diameter portion 222B can be provided closer to the base portion by 0.1 mm or more from the tip 220a of the bristles 220B.

  Even in the toothbrush provided with the bristles 220B, at the time of brushing, stress concentration portions are generated in the bristles 220B in the vicinity of the narrow-diameter portion 222B and the front end side thereof, and the repeated accumulation of fatigue locally in the vicinity of the base is suppressed. Therefore, even when the hair opening durability is increased, excellent breakage durability can be ensured.

Moreover, the toothbrush provided with the bristle 220C illustrated in FIG. 11 may be sufficient as the toothbrush of a 2nd aspect.
The bristles 220C are tapered bristles provided with a tapered portion 221C including a small diameter portion 222C that decreases in diameter toward the distal end on the distal end side portion, and the small diameter portion 222D is closer to the base side than the tapered portion 221C. Is provided. The small-diameter portion 222C is provided closer to the base by 0.1 mm or more from the tip 220a in the tapered portion 221C of the bristles 220, and has a cross-sectional area of 14% or less of the cross-sectional area of the base. The small-diameter portion 222D has the outer peripheral surface of the bristles 220C in the circumferential direction so that both sides of the outer peripheral surface of the bristles 220C are recessed in a circular arc shape in a side view, closer to the base side than the tapered portion 221C. It is provided by being recessed over the circumference. The small-diameter portion 222D has a cross-sectional area of 14% or less of the cross-sectional area of the base in the bristle 220C.
Thus, the hair 220C has a shape that combines the hair 220 and the hair 220B.

  In the toothbrush provided with the bristles 220C, the stress concentration portion is generated in the vicinity of the base and the tip side of the bristles 220C at the time of cleaning, and it is suppressed that repeated fatigue is accumulated locally in the vicinity of the base. Even when the hair opening durability is increased, excellent breaking durability can be ensured.

In the toothbrush of a 2nd aspect, you may use combining multiple types of the bristle which has a small diameter part.
The toothbrush of the 2nd aspect may combine the bristle bundle formed with the bristle which has a thin diameter part, and the bristle bundle formed with the bristle which does not have a thin diameter part. In this case, it is preferable that the length of the hair bundle formed with the hair having the small diameter portion is higher than the height of the hair bundle formed with the hair having no small diameter portion. Thereby, the force added to the hair which does not have a small diameter part at the time of brushing by the hair | bristle bundle formed with the hair which has a thin diameter part is reduced. Therefore, compared with the case where the hair | bristle bundle formed with the hair which has a thin diameter part is not combined, the hair breakage of the hair which does not have a thin diameter part is also suppressed.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Example 1]
The toothbrush 11 illustrated in FIGS.
On the flocked surface 118a of the head portion 118, three flocked holes 123 are formed in the width direction near the front end and the rear end, respectively, and four in the width direction and six in the axial direction are formed between these holes. Twenty-four flock holes 123 were formed to line up. The diameter of the flock hole 123 was 1.5 mm.
As the taper hair 120, a PTT taper hair having a taper portion formed at both end portions was used. The 21 bristles were bundled and folded in two along a flat wire 124, and the hair bundles 112 were planted by being driven into the flock holes 123 to form the brush portion 122. The hair length H1 of the tapered hair (tapered hair 120) in the hair bundle 112 was 11.5 mm. In the taper hair, the average value of the tip diameter (the diameter of the portion 0.1 mm away from the tip to the base side) is 0.02 mm, the length L1 of the taper portion is 3.0 mm, and the diameter of the straight portion Was 7.5 mil (0.19 mm).

Step (a1):
As shown in FIG. 4, with the brush portion 122 pressed against a spherical surface 1100 having a radius of 85 mm, the handle body 110 was moved back and forth in the axial direction and rubbed. The displacement x1 (mm) of the tip 120a relative to the base 120b of the tapered bristle 120 in the surface direction of the flocked surface 118a of the head portion 118 was measured with a load of 200 g applied to the brush tip 122a. Met.

Step (b1):
For a taped hair made of PTT (Young's modulus = 245 kg / mm ² ) having the same shape as the taper hair 120, a position 11.5 mm from the tip (position corresponding to the base) is fixed and the tip is in the axial direction of the taper hair An engineering simulation was performed with a 4.20 mm displacement in the vertical direction. For the engineering simulation, a three-dimensional finite element method (FEM) analysis using LS-DYNA (analysis software, manufactured by LSTC) was used. In the engineering simulation, it was found that the stress was concentrated at the taper portion of the taper hair and at two locations closer to the base portion than the taper portion. The distance from the tip of the maximum stress generation position near the base was 11.33 mm, and the maximum stress A1 was 1.58 kg / mm ² . The distance from the tip of the maximum stress generation position of the taper part was 0.070 mm, and the maximum stress B1 was 2.09 kg / mm ² . The ratio B1 / A1 was 1.32.

[Examples 2 to 6]
A toothbrush was prepared in the same manner as in Example 1 except that the length L1 of the tapered portion was changed as shown in Table 1, and the stress calculation method was performed to obtain the ratio B1 / A1.

[Comparative Example 1]
A toothbrush was produced in the same manner as in Example 1 except that PTT straight hair (tip diameter: 0.19 mm) was used instead of PTT tapered hair. Next, when the stress calculation method was performed on the produced toothbrush in the same manner as in Example 1, stress concentration was not observed at the tip portion of the straight hair in the engineering simulation, and stress was concentrated only in the vicinity of the base portion. It was recognized that The distance from the tip of the maximum stress generation position near the base was 11.35 mm, and the maximum stress A1 was 1.59 kg / mm ² .

  Each dimension of the hair in each example, displacement amount (deflection amount) x1 in step (a1), maximum stress A1, distance from tip of generation position of maximum stress A1, maximum stress B1, maximum stress B1 generation position Table 1 shows the distance from the tip and the ratio B1 / A1.

In the toothbrush of the comparative example 1, it is easy to bend in the vicinity of the base part of the straight hair when it is continuously used. As recognized in the engineering simulation, it is considered that the stress is concentrated only in the vicinity of the base portion of each straight hair at the time of brushing, and fatigue is accumulated locally.
On the other hand, in the toothbrushes of Examples 1 to 6, when the brush is brushed, the stress concentration points on each taper bristles are two locations closer to the base than the taper portion. Therefore, in the toothbrushes of Examples 1 to 6, since the stress is continuously concentrated only in the vicinity of the base portion of each tapered hair at the time of brushing and fatigue is locally accumulated, the toothbrush of Comparative Example 1 Compared to excellent durability against broken hair.

[Example 7]
The toothbrush 21 illustrated in FIGS.
On the flocked surface 218a of the head portion 218, three flocked holes 228 are formed in the width direction near the front end and the rear end, respectively, and four in the width direction and six in the axial direction are formed between these holes. Twenty-four flock holes 228 were formed so as to line up. The diameter of the flocking hole 228 was 1.5 mm.
As the bristles 220, PTT taper hairs having taper portions formed at both ends were used. 21 taper hairs were bundled and folded in two along a flat wire 226, and the hair bundles 212 were implanted by being driven into the respective flocking holes 228 to form brush portions 224. The hair length H2 of the tapered hair (the hair 220) in the hair bundle 212 was 11.5 mm. In the taper hair, the average value of the tip diameter (the diameter of the portion 0.1 mm away from the tip to the base side) is 0.01 mm, the length L2 of the taper portion is 7.0 mm, and the straight portion 219 The diameter of the base was 7.5 mil (0.1905 mm). The ratio of the cross-sectional area at a position 0.1 mm away from the base end to the base side with respect to the cross-sectional area perpendicular to the axial direction of the base of the tapered hair (hair for hair 220) was 0.28%. That is, the taper hair (the hair 220) is a taper hair in which a small diameter portion is provided in the taper portion.

Step (a2):
As shown in FIG. 7, with the brush portion 224 pressed against a spherical surface 2100 having a radius of 85 mm, the handle body 210 was moved back and forth in the axial direction and rubbed. When a load of 200 g is applied to the brush tip 224a, the displacement amount x2 (mm) of the tip 220a with respect to the base 220b of the tapered hair (hair 220) in the surface direction of the flocked surface 218a of the head 218 is measured. It was 4.63 mm.

Step (b2):
For a taped hair made of PTT (Young's modulus = 245 kg / mm ² ) having the same shape as the taper hair (hair for hair 220), a position 11.5 mm from the tip (position corresponding to the base) is fixed and the tip is said taper hair An engineering simulation was conducted with a displacement of 4.33 mm in the direction perpendicular to the axial direction of For the engineering simulation, a three-dimensional finite element method (FEM) analysis using LS-DYNA (analysis software, manufactured by LSTC) was used. In the engineering simulation, it was confirmed that stress was concentrated at two locations near the narrow portion and the base portion of the tapered hair. The distance from the tip of the maximum stress generation position near the base was 11.35 mm, and the maximum stress A2 was 1.499 kg / mm ² . The distance from the tip of the maximum stress generation position in the vicinity of the small diameter portion was 0.275 mm, and the maximum stress B2 was 2.740 kg / mm ² .

[Examples 8 to 13]
A toothbrush was produced in the same manner as in Example 7 except that the tip diameter of the tapered bristles was changed as shown in Table 2, and the stress calculation method was performed to obtain the maximum stress A2 and the maximum stress B2.

[Comparative Examples 2 and 3]
A toothbrush was produced in the same manner as in Example 7 except that the tip diameter of the tapered bristles was changed as shown in Table 2, and the stress calculation method was performed. However, in both Comparative Examples 2 and 3, in the engineering simulation, it was recognized that no stress concentration was observed in the tapered portion of the tapered hair, and the stress was concentrated only in the vicinity of the base portion.

[Comparative Example 4]
A toothbrush was produced in the same manner as in Example 7, except that PTT straight hair (tip diameter: 0.1905 mm) was used instead of PTT tapered hair. Next, when the stress calculation method was performed on the produced toothbrush in the same manner as in Example 7, no stress concentration was observed at the tip portion of the straight hair in the engineering simulation, and the stress was concentrated only in the vicinity of the base portion. It was recognized that

  Each size of the hair in each example, displacement amount (deflection amount) x2 in step (a2), maximum stress A2, distance from tip of generation position of maximum stress A2, maximum stress B2, maximum stress B2 generation position Table 2 shows the distance from the tip and the ratio B2 / A2.

In the toothbrushes of Comparative Examples 2 to 4, breakage tends to occur near the base of the bristle when continuously used. As recognized in the engineering simulation, it is considered that the stress is concentrated only in the vicinity of the base portion of each hair at the time of brushing, and fatigue is accumulated locally.
On the other hand, in the toothbrushes of Examples 7 to 13, when the brush is brushed, there are two stress concentrated portions in the vicinity of the narrow portion and the vicinity of the base portion. Therefore, in the toothbrushes of Examples 7 to 13, since stress is continuously concentrated only in the vicinity of the base portion of each tapered hair at the time of brushing and fatigue is locally accumulated, Compared to toothbrushes, it has excellent durability against broken hair.

11, 21 Toothbrush 110, 210 Handle body 112, 212 Hair bundle 114, 214 Handle portion 116, 216 Neck portion 118, 218 Head portion 118a, 218a Flocked surface 119, 219 Straight portion 120 Taper hair 120a, 220a Tip 120b, 220b Base 121, 221 Tapered portion 122 Brush portion 122a Brush portion tip 123, 228 Flocking hole 124, 226 Flat wire 220 Hair 222 Small diameter portion 224 Brush portion 224a Brush portion tip

Claims (9)

A toothbrush provided with a brush portion formed by implanting a plurality of hair bundles on the hair-implanted surface of the head portion,
The hair bundle is provided with a taper portion which is reduced in diameter toward the tip at the tip portion, and the ratio of the maximum stress B1 to the maximum stress A1 calculated by the stress calculation method having the following step (a1) and the following step (b1). A toothbrush having tapered bristles with B1 / A1 of 1.0 to 1.9.
(A1) Displacement x1 (mm) of the tip with respect to the base of the tapered hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B1) An engineering simulation of a state in which the tip of the taper hair is displaced by the displacement amount x1 (mm) in a direction perpendicular to the axial direction of the taper hair, and the maximum stress generated closer to the base than the taper portion of the taper hair A1 and the maximum stress B1 generated at the tapered portion are calculated. The length of the tapered portion is 3 to 11.5 mm,
The toothbrush according to claim 1, wherein a position of a boundary between the base portion and the tapered portion of the tapered bristles is equal to a position of the flocked surface, or the base portion is located outside the flocked surface.   The toothbrush according to claim 1 or 2, wherein a diameter of a portion 0.1 mm from a tip of the tapered portion is 0.07 mm or less.   The toothbrush according to any one of claims 1 to 3, wherein the tapered bristles are formed of polytrimethylene terephthalate. A toothbrush provided with a brush portion formed by implanting a plurality of hair bundles on the hair-implanted surface of the head portion,
The hair bundle is provided with a small-diameter portion having a cross-sectional area of 14% or less of the cross-sectional area of the base at a position near the base by 0.1 mm or more from the hair tip, and extends from the base toward the tip. A toothbrush comprising bristles having a region having a larger cross-sectional area than a narrow-diameter portion. The toothbrush according to claim 5, wherein the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following step (a2) and the following step (b2) in the bristles satisfy A2> 0 and B2> 0. .
(A2) Displacement amount x2 (mm) of the tip with respect to the base of the hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B2) Engineering simulation of a state in which the tip of the bristles is displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the bristles, and the maximum stress concentration portion that occurs closest to the base in the bristles The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side from the stress A2 are calculated. The toothbrush according to claim 5, wherein B2 ≧ A2> 0 with respect to the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following step (a2) and the following step (b2).
(A2) Displacement amount x2 (mm) of the tip with respect to the base of the hair in the surface direction of the flocked surface when the brush is rubbed against a spherical surface having a radius of 85 mm so that a load of 200 g is applied to the tip of the brush ).
(B2) Engineering simulation of a state in which the tip of the bristles is displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the bristles, and the maximum stress concentration portion that occurs closest to the base in the bristles The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side from the stress A2 are calculated.   The toothbrush as described in any one of Claims 5-7 which is a taper hair provided with the taper part which diameter-reduces as the said hair | bristle goes to a front-end | tip, and has the said small diameter part in the said taper part.   The toothbrush according to any one of claims 5 to 8, wherein the bristles are formed of polytrimethylene terephthalate.

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