JP6858123B2 - toothbrush - Google Patents

Description

The present invention relates to a toothbrush.
The present application claims priority based on Japanese Patent Application No. 2015-147511 filed in Japan on July 24, 2015 and Japanese Patent Application No. 2015-150844 filed in Japan on July 30, 2015. The contents are used here.

In particular, since it is difficult to remove plaque accumulated in the gaps between the teeth and the cervical region, the toothbrush is required to have excellent plaque removing property. The plaque removal property of a toothbrush is affected by the arrangement of hair bundles and the specifications of each hair that forms the hair bundles. As a hair that can efficiently remove plaque accumulated in the gaps such as the interdental part and the cervical part and has an excellent feeling of cleaning, tapered hair having a tapered part that shrinks in diameter toward the tip is known. Has been done.

In addition to the plaque removing property, the toothbrush is also required to have sufficient hair opening durability. By using a toothbrush having sufficient bristling durability, 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 toothbrush replacement. In particular, the processing technology for producing tapered bristles is complicated and costly, and toothbrushes with tapered bristles are expensive. Therefore, sufficient bristling durability is required so that the frequency of toothbrush replacement does not increase excessively. ..

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

International Publication No. 2005/0393555

However, when the hair is formed by PTT or the like and has improved hair opening durability, the hair may break near the hair base (the portion where the opening surface of the hair follicle hole is located) when the hair is continuously used. Even if the bristles are suppressed, it is difficult to sufficiently increase the durability of the toothbrush if the bristles are easily broken. In this way, in a toothbrush, it is important to be able to efficiently remove plaque and have an excellent feeling of cleaning, as well as to ensure excellent hair breakage durability even when the hair opening durability is improved. ..

A first object of the present invention is to provide a toothbrush that can efficiently remove plaque, has an excellent cleaning feeling, and can secure excellent hair breakage durability even when the hair opening durability is enhanced.
A second object of the present invention is to provide a toothbrush that can secure excellent hair breakage durability even when the hair opening durability is enhanced.

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 flocked surface of the head portion, and the hair bundle is provided with a tapered portion at the tip portion that shrinks in diameter toward the tip. The hair is tapered so that the 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) 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, the amount of displacement of the tip with respect to the base of the tapered bristles in the surface direction of the flocked surface x 1 (mm). ) Is measured.
(B1) An engineering simulation is performed in which the tip of the tapered hair is displaced by the displacement amount x 1 (mm) in a direction perpendicular to the axial direction of the tapered hair, and the maximum stress generated closer to the base than the tapered portion of the tapered hair. A1 and the maximum stress B1 generated in 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 in 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 the diameter of the portion 0.1 mm from the 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 having a brush portion formed by implanting a plurality of hair bundles on the flocked surface of the head portion, and the hair bundle is located at a position closer to the base by 0.1 mm or more from the tip of the bristles. A toothbrush having a small diameter portion having a cross-sectional area of 14% or less of the cross-sectional area of the base and having a bristles having a region larger than the small diameter portion extending from the base toward the tip. ..
[6] Regarding the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following steps (a2) and the following steps (b2) in the hair, A2> 0 and B2> 0, in [5]. The listed toothbrush.
(A2) 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, the amount of displacement of the tip with respect to the base portion of the hair in the surface direction of the flocked surface x 2 (mm). ) Is measured.
(B2) An engineering simulation was performed in which the tip of the hair was displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the hair, and the maximum stress concentration portion generated closest to the base of the hair was performed. The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side of the stress A2 are calculated.
[7] The maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following steps (a2) and the following steps (b2) in the hair, and B2 ≧ A2> 0, according to [5]. toothbrush.
(A2) 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, the amount of displacement of the tip with respect to the base portion of the hair in the surface direction of the flocked surface x 2 (mm). ) Is measured.
(B2) An engineering simulation was performed in which the tip of the hair was displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the hair, and the maximum stress concentration portion generated closest to the base of the hair was performed. The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side of the stress A2 are calculated.
[8] The method according to any one of [5] to [7], wherein the bristles are tapered bristles provided with a tapered portion whose diameter decreases toward the tip, and the tapered portion has the small 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 tapered bristles having a ratio B2 / A2 of the maximum stress B2 to the maximum stress A2 of 1.0 to 1.9.
When the hair is tapered in the second aspect, the maximum stress A2 and the maximum stress B2 are the same as the maximum stress A1 and the maximum stress B1 in the first aspect.

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

It is a side view which showed an example of the toothbrush of the 1st aspect of this invention. It is an enlarged plan view of the head part of the toothbrush of FIG. FIG. 5 is an enlarged cross-sectional view of the vicinity of one hair bundle in the head portion of the toothbrush of FIG. It is a schematic diagram explaining the step (a1) of the stress calculation method in the 1st aspect of this invention. It is a side view which showed an example of the toothbrush of the 2nd aspect of this invention. It is an enlarged plan view of the head part of the toothbrush of FIG. FIG. 5 is an enlarged cross-sectional view of the vicinity of one hair bundle in the head portion of the toothbrush of FIG. It is a schematic diagram explaining the step (a2) of the stress calculation method in the 2nd aspect of this invention. It is a side view which showed the other example of the bristles in the toothbrush of the 2nd aspect of this invention. It is a side view which showed the other example of the bristles in the toothbrush of the 2nd aspect of this invention. It is a side view which showed the other example of the bristles in the toothbrush of the 2nd aspect of this invention.

[First aspect]
Hereinafter, an example of the toothbrush according to the first aspect of the present invention will be described.
As shown in FIGS. 1 to 3, the toothbrush 11 of the present embodiment includes a handle body 110 and a brush portion 122 formed of a plurality of hair bundles 112 planted in the handle body 110. The handle body 110 includes a rod-shaped handle portion 114, a neck portion 116 extending from the tip of the handle portion 114 and thinner than the handle portion 114, and a head portion 118 provided at the tip of the neck portion 116. There is. The plurality of hair bundles 112 are planted on the flocked surface 118a of the head portion 118.

As the handle body in the first aspect, a known aspect can be adopted.
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 of the handle portion perpendicular to the axial direction (length direction) is not particularly limited, and examples thereof include a shape in which the corners of the rectangle are rounded out, a rectangular shape, and a circular shape.
The thickness and length of the handle portion can be appropriately designed according to the target person who uses the toothbrush.

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

The head portion 118 is a portion provided at the tip of the neck portion 116 for implanting a plurality of hair bundles 112. The upper surface of the head portion 118 is a flocked surface 118a on which the hair bundle 112 is planted. The shape of the head portion 118 is a plate shape in which rectangular corners long in the axial direction are rounded out in a plan view.
The length, width and thickness of the head portion are not particularly limited, and can be appropriately designed according to the target person who uses the toothbrush.

As the material for forming the handle body, a high hardness resin having a flexural modulus (JIS K7203) of 500 MPa or more and 3000 MPa or less can be used, which is selected in consideration of the rigidity and mechanical properties required for the toothbrush. .. Examples of the high hardness resin include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexylene methylene terephthalate (PCT), polystyrene (PS), and 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 of these resins may be used in combination as appropriate. Further, 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 of a plurality of hair bundles 112 planted on the flocked surface 118a of the head portion 118.
In the toothbrush of the first aspect, the aspect of implanting the hair bundle on the flocked surface of the head portion is not particularly limited. In the toothbrush 11 of this example, three hair bundles 112 are planted in the width direction near the tip and the rear end of the flocked surface 118a, and four hair bundles 112 are arranged in the area between them in the width direction. In addition, 24 hair bundles 112 are planted so that 6 hair bundles 112 are lined up 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 waist and the like required for the hair bundle 112.

The hair bundle 112 of this example is planted on the flocked surface 118a by the flat line flocking method. Specifically, as shown in FIG. 3, a plurality of tapered bristles 120 provided with tapered portions 121 at both ends are bundled and folded in half along a flat line 124 to be formed on the flocked surface 118a of the head portion 118. The hair bundle 112 is planted by being driven into the hair transplant hole 123.
The method of implanting the hair bundle on the flocked surface of the head portion is not limited to the flat wire flocking method, and may be a heat welding type flocking method, an in-mold method or the like.

The tapered bristles 120 were calculated by a stress calculation method in which a tapered portion 121 having a diameter reduced toward the tip is provided on a portion closer to the tip side than the straight portion 119 and has steps (a1) and (b1) described later. It is a tapered hair (hereinafter, referred to as a tapered hair (X1)) in which the ratio B1 / A1 of the maximum stress B1 to the maximum stress A1 is 1.0 to 1.9. The tapered portion means a portion of the tapered hair from a position where the diameter starts to decrease to the tip.
In the toothbrush of the first aspect, since the bristles are provided with tapered bristles (X1), plaque can be efficiently removed, the cleaning feeling is excellent, and the bristles are excellent even when the bristles opening durability is improved. Durability is ensured.

The tapered hairs 120 forming the hair bundle 112 in this example are all tapered hairs (X1). The bristles in the toothbrush according to the first aspect of the present invention may be a combination of tapered bristles (X1) and bristles other than tapered bristles (X1) such as straight bristles.
The ratio of the number of tapered hairs (X1) to the total number of hairs for forming hair bundles 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 steps (a1) and the following steps (b1).
(A1) Measure the displacement amount x1 (mm) of the tip of the tapered hair with respect to the base 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. To do.
(B1) An engineering simulation is performed in which the tip of the tapered hair is displaced by the displacement amount x 1 (mm) in a direction perpendicular to the axial direction of the tapered hair, and the maximum stress generated closer to the base than the tapered portion of the tapered hair. A1 and the maximum stress B1 generated in 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 the handle body 110 is moved back and forth in the axial direction and rubbed. Then, in a state where the hair bundle 112 is rubbed and a load of 200 g is applied to the tip 122a of the brush portion, the displacement amount x1 (mm) of the tip 120a with respect to the base 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 deflection of the tapered bristles 120 is measured.

The phrase "a load of 200 g is applied to the tip of the brush portion" means that the reaction force value applied to the tip of the brush portion while the brush portion of the toothbrush is rubbed against the spherical surface is 200 g. That is, for example, when the brush portion of the toothbrush is rubbed against the scale, a force that makes the scale of the scale 200 g is applied to the tip of the brush portion.
The "base portion of the tapered bristles" is a portion of the tapered bristles that has not been tapered, and means a portion of the portion having a brush shape before the taper processing that corresponds to the position of the flocked surface of the head portion. In the case of tapered hair having both ends tapered, the portion corresponding to the position of the flocked surface of the head portion is the base portion of the straight portion of the middle portion in the length direction of the tapered hair.

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

(Step (b1))
When the displacement amount x1 (mm) of the tapered bristles 120 in the toothbrush 11 is measured in the step (a1), the position corresponding to the base of the tapered bristles is fixed for the tapered bristles having the same shape and material as the tapered bristles 120. The tip of the tapered hair is displaced by a displacement amount x 1 (mm) in a direction perpendicular to the axial direction of the tapered hair, and an engineering simulation is performed. At this time, in the tapered bristles in the engineering simulation, stress concentration is observed in the tapered portion and the straight portion closer to the base than the tapered portion. Then, in the engineering simulation, the maximum stress generated at the base portion of the tapered hair is defined as the maximum stress A1, and the maximum stress generated at 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 the shape of the tapered hair (hair length, length of the tapered portion, tip diameter, etc.) and Young's modulus of the material used for the tapered hair as the conditions 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, plaque in a narrow portion can be efficiently removed, the feeling of cleaning is excellent, and excellent hair breakage durability can be ensured even when the hair opening durability is enhanced.
The ratio B1 / A1 of the tapered bristles (X1) can be adjusted by, for example, the length of the tapered portion, the material, and the like.

The axial length L1 (FIG. 3) of the tapered portion of the tapered bristles (X1) is preferably 3 to 11.5 mm, more preferably 4 to 7 mm. When the length of the tapered portion is within the above range, it becomes easy to secure excellent hair breakage resistance. When the length of the tapered portion is at least the lower limit value, the tapered portion easily enters the gap between the interdental portion and the cervical portion, and the plaque accumulated in the gap is easily scraped off. When the length of the tapered portion is not more 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.
The ratio of the axial length L1 of the tapered portion to the hair length of the tapered hair (X1) is preferably 5 to 100%, more preferably 20 to 100%.
The average axial length of the tapered portion of the tapered hair (X1) forming the hair bundle is preferably 3 to 11.5 mm, more preferably 4 to 7 mm.

For the tapered bristles (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 straight portion of the tapered bristles (X1) is just accommodated and hidden in the flocked holes of the head portion, or the straight portion is exposed from the head portion.

The diameter of the portion of the tapered bristles (X1) 0.1 mm away from the tip of the tapered portion (hereinafter, also referred to as the tip diameter) is preferably 0.07 mm or less, more preferably 0.02 mm or less, and 0. 01 to 0.02 mm is more preferable. If the tip diameter of the tapered bristles (X1) is 0.02 mm or less, the tapered portion easily enters the gap between the interdental portion and the cervical portion, and the plaque accumulated in the gap can be easily scraped off. , It is easy to obtain an excellent feeling of sweeping.
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 tapered bristles (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 hair length H1 (FIG. 3) of the tapered hair (X1), that is, the average length from the position corresponding to the flocked surface of the tapered hair (X1) to the tip is not particularly limited, and is, for example, 5 to 15 mm. Can be done.

The material for forming the tapered hair is not particularly limited, and polyesters such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); 612 nylon and 610 nylon. Polyamides such as, and polyolefins such as polyethylene (PE) and polypropylene (PP). Among them, PTT is preferable in terms of excellent hair opening resistance. In the first aspect of the present invention, even if the tapered hair is used as PTT hair, excellent hair breakage resistance can be ensured.

(Production method)
The method for producing the toothbrush according to the first aspect of the present invention is not particularly limited, and a known method can be adopted.
Examples of the method for manufacturing the handle body include injection molding and the like. As a method for producing tapered hair (X1), for example, both ends of the hair obtained by spinning are immersed in a solution such as an acid or alkaline solution for a predetermined time, pulled up, neutralized, washed with water, or the like. The method of doing this can be mentioned. Examples of the method for planting the hair bundle include a flat wire type hair transplantation method, a heat welding type hair transplantation method, and an in-mold method.

Since the toothbrush of the first aspect of the present invention described above includes tapered bristles (X1) as bristles for forming bristles, plaque accumulated in gaps such as interdental portions and cervical regions can be removed. It can be removed efficiently and has an excellent feeling of cleaning. Further, the tapered hair (X1) having a ratio B1 / A1 of 1.0 to 1.9 is provided as the hair for use, and the stress concentration portion at the time of brushing is located near the base of the tapered hair and the tapered portion. Therefore, it is possible to prevent the stress from being concentrated only in the vicinity of the base of the hair and the accumulation of repeated fatigue locally in that portion. Therefore, in the first aspect of the present invention, excellent hair breakage durability can be ensured even when the tapered hair (X1) is formed by PTT or the like to enhance the hair opening durability. In particular, when the tapered hair (X1) is formed by PTT, both excellent hair opening durability and hair breaking durability can be achieved at the same time.

[Second aspect]
The toothbrush according to the second aspect of the present invention includes a brush portion formed by implanting a plurality of hair bundles on the flocked surface of the head portion. The bristles in the toothbrush according to the second aspect of the present invention are 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 closer to the base by 0.1 mm or more from the tip of the bristles and described above. The hair has a region extending from the base toward the tip and having a cross-sectional area larger than that of the small diameter portion.
In a hair having such a small diameter portion, when a force is applied in a direction perpendicular to the axial direction with respect to the tip of the hair, a stress concentration portion is generated in the vicinity of the base and on the tip side of the base. As a result, stress is concentrated only in the vicinity of the base of the hair, and repeated local fatigue is suppressed from accumulating in that portion. Therefore, even when the hair is formed of PTT or the like to improve the hair opening durability, excellent hair breaking durability can be ensured.

Hereinafter, an example of the toothbrush according to the second aspect of the present invention will be described.
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 planted in the handle body 210. The handle body 210 includes a rod-shaped handle portion 214, a neck portion 216 extending from the tip of the handle portion 214 and thinner than the handle portion 214, and a head portion 218 provided at the tip of the neck portion 216. There is. The plurality of hair bundles 212 are planted on the flocked surface 218a of the head portion 218.

As the handle body in the second aspect, a known aspect can be adopted.
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 of the handle portion perpendicular to the axial direction (length direction) is not particularly limited, and examples thereof include a shape in which the corners of the rectangle are rounded out, a rectangular shape, and a circular shape.
The thickness and length of the handle portion can be appropriately designed according to the target person who uses the toothbrush.

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

The head portion 218 is a portion provided at the tip of the neck portion 216 for planting a plurality of hair bundles 212. The upper surface of the head portion 218 is a flocked surface 218a on which the hair bundle 212 is planted. The shape of the head portion 218 is a plate shape in which rectangular corners long in the axial direction are rounded in a plan view.
The length, width and thickness of the head portion are not particularly limited, and can be appropriately designed according to the target person who uses the toothbrush.

The material for forming the handle body in the second aspect is selected in consideration of the rigidity and mechanical properties required for the toothbrush. For example, a high hardness resin having a flexural modulus (JIS K7203) of 500 MPa or more and 3000 MPa or less is used. Can be used. Examples of the high-hardness resin include the high-altitude resin mentioned in the first aspect. Alternatively, polybutylene terephthalate (PBT) may be used. One of these resins may be used alone, or two or more of these resins may be used in combination as appropriate. Further, 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 flocked surface 218a of the head portion 218.
In the toothbrush of the second aspect, the aspect of implanting the hair bundle on the flocked surface of the head portion is not particularly limited. In the toothbrush 21 of this example, three hair bundles 212 are planted in the width direction near the tip and the rear end of the flocked surface 218a, respectively, and four hair bundles 212 are arranged in the width direction in the area between them. In addition, 24 hair bundles 212 are planted so that 6 hair bundles 212 are lined up 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 columnar or prismatic.
The hair length and thickness of the hair bundle 212 can be determined in consideration of the hair waist and the like required for the hair bundle 212.

The hair bundle 212 of this example is planted on the flocked surface 218a by the flat line flocking method. Specifically, as shown in FIG. 7, a plurality of hair follicles 220 are bundled, folded in half along a flat line 226, and driven into a flocked hole 228 formed on a flocked surface 218a of the head portion 218. Hair follicles 212 are planted.
The method of implanting the hair bundle on the flocked surface of the head portion is not limited to the flat wire flocking method, and may be a heat welding type flocking method, an in-mold method or the like.

In the second aspect, the hair having a small diameter portion is preferably tapered hair.
The bristles 220 are tapered bristles provided with tapered portions 221 at both ends of the straight portion 219, which reduce in diameter toward the tip. The tapered portion 221 of the hair 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 0.1 mm or more closer to the base portion 220b from the tip 220a. Further, since the hair 220 includes the straight portion 219, it has a region extending from the base portion 220b toward the tip 220a and having a larger cross-sectional area than the narrow diameter portion 222.
In the second aspect, the cross-sectional area of the base means the cross-sectional area of the cross section when the base of the hair is cut in the direction perpendicular to the axial direction. The same applies to the cross-sectional area of the small diameter portion.

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

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

The mode of the small diameter portion is not particularly limited, and the diameter is reduced toward the tip of the hair, such as the small diameter portion 222 provided on the tapered portion 221 of the hair 220, and the outer peripheral surface is viewed from the side. An example is an embodiment in which the shape is a straight line inclined with respect to the axial direction. Further, the small diameter portion 222 of the hair 220 is inclined so that both sides of the outer peripheral surface approach each other in the side view. However, the mode of the small diameter portion is not limited to this mode, and may be a mode in which only one side of the outer peripheral surface is inclined in the side view.

Further, the mode of the small diameter portion is not limited to the mode provided in the tapered portion of the tapered hair. For example, the small-diameter portion is formed by denting the outer peripheral surface of the hair over the entire circumference in the circumferential direction so that both sides of the outer peripheral surface of the hair are recessed in an arc shape in a side view. It may be. Further, the small diameter portion may be formed by denting the outer peripheral surface of the hair so that one side of the outer peripheral surface of the hair is recessed in an arc shape in a side view. When the small diameter portion has such an embodiment, the small diameter portion can be positioned closer to the base than the position 0.1 mm from the tip of the hair.
Further, in the case of the small-diameter portion of these embodiments, the ratio of the cross-sectional area of the small-diameter portion to the cross-sectional area perpendicular to the axial direction of the base portion is 14% or less, preferably 0.1 to 14%.

The number of small diameter portions in one hair is one in the hair 220, but it 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 a direction perpendicular to the axial direction, the vicinity of the base and the two small diameter portions or their vicinity respectively. Stress concentration portions are generated at 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 the tapered hair. For the bristles in the toothbrush of the second aspect, a bristles having a small diameter portion and a bristles having no small diameter portion such as straight bristles may be used in combination.
The ratio of the number of hairs having a small diameter portion to the total number of hairs forming a 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 having the step (a2) and the following step (b2) described later, A2> 0 and B2. > 0, preferably B2 ≧ A2> 0.

Hereinafter, the stress calculation method will be described. The stress calculation method in the second aspect includes the following steps (a2) and (b2).
(A2) Displacement amount x 2 (mm) of the tip of the toothbrush 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. To measure.
(B2) An engineering simulation was performed in which the tip of the hair was displaced by a displacement amount x 2 (mm) in a direction perpendicular to the axial direction of the hair, and the maximum stress of the stress concentration portion generated closest to the base of the hair was performed. A2 and the maximum stress B2 of the stress concentration portion generated on the tip side of the A2 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 the spherical surface 2100 having a radius of 85 mm, and the handle body 210 is moved back and forth in the axial direction and rubbed. Then, in a state where the hair bundle 212 is rubbed and a load of 200 g is applied to the tip 224a of the brush portion, the displacement amount x2 (mm) of the tip 220a with respect to the base 220b of the hair 220 in the surface direction of the flocked surface 218a of the head portion 218. ), That is, the amount of bending of the hair 220 is measured.

The phrase "a load of 200 g is applied to the tip of the brush portion" means that the reaction force value applied to the tip of the brush portion while the brush portion of the toothbrush is rubbed against the spherical surface is 200 g. That is, for example, when the brush portion of the toothbrush is rubbed against the scale, a force that makes the scale of the scale 200 g is applied to the tip of the brush portion.
The “base of the hair” means a portion of the hair that has the maximum diameter without being tapered or the like and that corresponds to the position of the flocked surface of the head portion.

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

(Step (b2))
When the displacement amount x2 (mm) of the hair 220 on the toothbrush 21 is measured in the step (a2), the position corresponding to the base of the hair is fixed for the hair having the same shape and material as the hair 220. An engineering simulation is performed in which the tip of the hair is displaced by a displacement amount x 2 (mm) in a direction perpendicular to the axial direction of the hair. At this time, in the hair in the engineering simulation, stress concentration is observed in the vicinity of the base portion and in the vicinity of the small diameter portion or the small diameter portion on the tip side thereof. Then, in the engineering simulation, the maximum stress of the stress concentration portion generated closest to the base, that is, the stress concentration portion near the base is defined as the maximum stress A2, and the maximum stress of the stress concentration portion generated on the tip side thereof is defined as the maximum stress B2. Calculate each. If the hair is provided with two or more small diameter parts and two or more stress concentration parts are found in addition to the stress concentration part near the base, each stress concentration part other than the stress concentration part near the base Calculate the maximum stress B2.

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 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 aspect, 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 tapered, the axial length L2 (FIG. 7) of the tapered portion is preferably 1 to 15 mm, more preferably 3 to 7 mm. When the length of the tapered portion is within the above range, it becomes easy to secure excellent hair breakage resistance. When the length of the tapered portion is at least the lower limit value, the tapered portion easily enters the gap between the interdental portion and the cervical portion, and the plaque accumulated in the gap is easily scraped off. If the length of the tapered portion is not more than the upper limit value, the rigidity (stiffness) of the hair is ensured and plaque can be easily scraped off. In addition, repeated use can prevent the tips of the hair from opening easily.
When the hair is tapered, the ratio of the axial length L2 of the tapered portion to the hair length of the tapered hair is preferably 5 to 100%, more preferably 20 to 100%.
When the hair is tapered, the average axial length of the tapered portion of the tapered hair forming the hair bundle is preferably 1 to 15 mm, more preferably 3 to 7 mm.

When the hair is tapered, the tip diameter of the tapered hair is preferably 0.01 mm to 0.07 mm. If the tip diameter of the tapered bristles is within the above range, when a force is applied to the tip of the tapered bristles in a direction perpendicular to the axial direction, a stress concentration portion is generated in the small diameter portion located on the tip side portion of the tapered portion. It becomes easy to do so, and the stress of the base is dispersed in or in the vicinity of the small diameter portion, so that sufficient durability against breakage is easily ensured.
When 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 hair is tapered, 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 of the hair can be determined in consideration of the material and the like, and 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. It is said to be ~ 8 mil. The cross section of the hair may be polygonal and is not limited to a circular shape.

The average hair length H2 (FIG. 7) of the hair, that is, the average length from the position corresponding to the flocked surface to the tip of the hair 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 aspect. Among them, PTT is preferable in terms of excellent hair opening resistance. In the second aspect, even if the hair is used as PTT hair, excellent hair breakage resistance can be ensured.

(Production method)
The method for producing the toothbrush according to the second aspect is not particularly limited, and a known method can be adopted.
Examples of the method for manufacturing the handle body include injection molding and the like. As a method for producing tapered hair as hair for use, for example, the same method as the method described in the first aspect can be mentioned. Examples of the method for planting the hair bundle include a flat wire type hair transplantation method, a heat welding type hair transplantation method, an in-mold method, and the like, as in the first aspect.

In the toothbrush of the second aspect of the present invention described above, the bristles have a small diameter portion 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 of the bristles. It has hair to have. Further, the hair has a region extending from the base toward the tip and having a larger cross-sectional area than the small diameter portion. As a result, in the toothbrush of the second aspect, since a plurality of stress concentration portions are generated in the vicinity of the base and the tip side of the bristle during brushing, the stress is concentrated only in the vicinity of the base of the bristle and in that portion. Locally repeated accumulation of fatigue is suppressed. Therefore, in the second aspect, excellent hair breakage durability can be ensured even when the hair is formed of PTT or the like to enhance the hair opening durability. In particular, when the hair is formed of PTT, both excellent hair opening durability and hair breaking durability can be achieved.
Further, in the second aspect of the present invention, if tapered hair is used as the hair having a small diameter portion, plaque accumulated in the gaps such as the interdental portion and the cervical portion can be efficiently removed, which is more excellent. It is a toothbrush that gives you a feeling of cleaning.

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 second aspect may be a toothbrush provided with the bristles 220A illustrated in FIG.
The hair 220A is a tapered hair provided with a tapered portion 221A on the tip end side of the straight portion 219 so that one side of the outer peripheral surface approaches the other side in a side view, and the diameter is reduced toward the tip end. Similar to the hair 220, the tapered portion 221A of the hair 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.

Even in the toothbrush provided with the bristles 220A, the stress concentration portion is generated in the vicinity of the small diameter portion 222A and the tip side of the small diameter portion 222A in the bristles 220A at the time of brushing, and it is suppressed that repeated fatigue is locally accumulated in the vicinity of the base portion. Therefore, even when the hair opening durability is increased, excellent hair breaking durability can be ensured.

Further, the toothbrush of the second aspect may be a toothbrush provided with the bristles 220B illustrated in FIG.
The hair 220B is provided with a small diameter portion 222B formed by denting the outer peripheral surface of the hair over the entire circumference in the circumferential direction so that both sides of the outer peripheral surface are recessed in an arc shape in a side view. Has been done. The small diameter portion 222B can be provided closer to the base by 0.1 mm or more from the tip 220a of the hair 220B.

Even in the toothbrush provided with the bristles 220B, the stress concentration portion is generated in the vicinity of the small diameter portion 222B and the tip side of the small diameter portion 222B in the bristles 220B at the time of brushing, and the accumulation of repeated fatigue locally in the vicinity of the base portion is suppressed. Therefore, even when the hair opening durability is increased, excellent hair breaking durability can be ensured.

Further, the toothbrush of the second aspect may be a toothbrush provided with the bristles 220C illustrated in FIG.
The hair 220C is a tapered hair provided with a tapered portion 221C including a tapered portion 222C whose diameter is reduced toward the tip on the distal end side portion, and the tapered portion 222D is provided on the base side of the tapered portion 221C. It is provided. The small diameter portion 222C is provided in the tapered portion 221C of the hair 220 closer to the base by 0.1 mm or more from the tip 220a, and has a cross-sectional area of 14% or less of the cross-sectional area of the base. The small diameter portion 222D has a shape in which both sides of the outer peripheral surface of the hair 220C are recessed in an arc shape from each other on the base side of the tapered portion 221C in the side view. It is provided by denting it 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 portion of the hair 220C.
As described above, the hair 220C has a shape as if the hair 220 and the hair 220B are combined.

Even in a toothbrush provided with a bristles 220C, a stress concentration portion is generated near the base and on the tip side of the bristles 220C at the time of brushing, and repeated local accumulation of fatigue is suppressed in the vicinity of the base. Even when the hair opening durability is increased, excellent hair breaking durability can be ensured.

In the toothbrush of the second aspect, a plurality of types of bristles having a small diameter portion may be used in combination.
The toothbrush of the second aspect may be a combination of a bristles formed of bristles having a small diameter portion and a bristles formed of bristles having no small diameter portion. In this case, it is preferable that the hair length of the hair bundle formed of the hair having a small diameter portion is higher than the hair length of the hair bundle formed of the hair having a small diameter portion. As a result, the bristles formed of the hairs having a small diameter portion reduce the force applied to the hairs having no small diameter portion at the time of brushing. Therefore, as compared with the case where the hair bundle formed of the hair having a small diameter portion is not combined, the hair breakage of the hair having no small diameter portion is also suppressed.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following description.
[Example 1]
The toothbrush 11 illustrated in FIGS. 1 to 3 was produced.
On the flocked surface 118a of the head portion 118, three flocked holes 123 are formed in the width direction near the tip and the rear end, respectively, and four in the width direction and six in the axial direction are formed in the area between them. Twenty-four flocked holes 123 were formed so as to line up. The diameter of the hair follicle hole 123 was 1.5 mm.
As the tapered bristles 120, PTT tapered bristles having tapered portions formed at both ends were used. Twenty-one bundles of the tapered hairs were bundled and folded in half along a flat line 124, and the hair bundles 112 were planted by driving them into the respective hair-planting holes 123 to form a brush portion 122. The hair length H1 of the tapered hair (tapered hair 120) in the hair bundle 112 was set to 11.5 mm. In the tapered bristles, 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 tapered 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 the spherical surface 1100 having a radius of 85 mm, the handle body 110 was moved back and forth in the axial direction and rubbed. With a load of 200 g applied to the tip 122a of the brush portion, the displacement amount x1 (mm) of the tip 120a with respect to the base 120b of the tapered bristles 120 in the surface direction of the flocked surface 118a of the head portion 118 was measured and found to be 4.20 mm. Met.

Step (b1):
For a tapered hair made of PTT (Young's modulus = 245 kg / mm ² ) having the same shape as the tapered hair 120, a position 11.5 mm from the tip (a position corresponding to the base) is fixed and the tip is oriented in the axial direction of the tapered hair. An engineering simulation was performed with a displacement of 4.20 mm 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 on the tapered portion of the tapered hair and at two locations closer to the base than the tapered 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 tapered portion 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 produced 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 carried out to obtain the ratio B1 / A1.

[Comparative Example 1]
A toothbrush was produced in the same manner as in Example 1 except that straight bristles made of PTT (tip diameter: 0.19 mm) were used instead of tapered bristles made of PTT. Next, when the stress calculation method was carried out for the produced toothbrush in the same manner as in Example 1, in the engineering simulation, no stress concentration was observed at the tip of the straight bristles, and the stress was concentrated only near the base. Was recognized. 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, the amount of displacement (deflection) x1 in the step (a1), the maximum stress A1, the distance from the tip of the position where the maximum stress A1 is generated, the maximum stress B1 and the position where the maximum stress B1 is generated. The distance from the tip and the ratio B1 / A1 are shown in Table 1.

In the toothbrush of Comparative Example 1, hair breakage is likely to occur near the base of straight hair when continuously used. It is considered that this is because the stress is concentrated only in the vicinity of the base of each straight hair at the time of wiping and the fatigue is accumulated locally repeatedly as observed in the engineering simulation.
On the other hand, in the toothbrushes of Examples 1 to 6, the stress concentration points in each tapered bristles are two points, one is a tapered part and the other is closer to the base than the tapered part at the time of wiping. Therefore, in the toothbrushes of Examples 1 to 6, stress is continuously concentrated only in the vicinity of the base of each tapered bristles during brushing, and fatigue is suppressed from locally accumulating. Compared to it, it has excellent hair breakage durability.

[Example 7]
The toothbrush 21 illustrated in FIGS. 5 to 7 was produced.
On the flocked surface 218a of the head portion 218, three flocked holes 228 are formed in the width direction near the tip and the rear end, respectively, and four in the width direction and six in the axial direction are formed in the area between them. Twenty-four flocked holes 228 were formed side by side. The diameter of the hair follicle hole 228 was 1.5 mm.
As the hair 220, taper hair made of PTT having tapered portions formed at both ends was used. Twenty-one bundles of the tapered hairs were bundled and folded in half along a flat line 226, and the hair bundles 212 were planted by driving them into the respective hair-planting holes 228 to form a brush portion 224. The hair length H2 of the tapered hair (hair 220) in the hair bundle 212 was set to 11.5 mm. In the tapered bristles, 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 tapered 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 of the tapered bristles (hair 220) to the cross-sectional area perpendicular to the axial direction of the base at a position 0.1 mm away from the tip of the base toward the base was 0.28%. That is, the tapered hair (hair 220) is a tapered hair in which a small diameter portion is provided in the tapered portion.

Step (a2):
As shown in FIG. 7, with the brush portion 224 pressed against the spherical surface 2100 having a radius of 85 mm, the handle body 210 was moved back and forth in the axial direction and rubbed. A displacement amount x 2 (mm) of the tip 220a with respect to the base 220b of the tapered bristles (hair 220) in the surface direction of the flocked surface 218a of the head portion 218 was measured with a load of 200 g applied to the tip 224a of the brush portion. It was 4.63 mm.

Step (b2):
^{For tapered hair made of PTT (Young rate = 245 kg / mm 2} ), which has the same shape as the tapered hair (hair 220), the position 11.5 mm from the tip (the position corresponding to the base) is fixed and the tip is the tapered hair. An engineering simulation was performed on the state of being displaced by 4.63 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 found that stress was concentrated in two places in the tapered hair, near the small diameter part and near the base part. 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 near 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 carried out 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 carried out. However, in all of Comparative Examples 2 and 3, in the engineering simulation, it was found that the stress concentration was not 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 straight bristles made of PTT (tip diameter: 0.1905 mm) were used instead of the tapered bristles made of PTT. Next, when the stress calculation method was carried out for the produced toothbrush in the same manner as in Example 7, in the engineering simulation, no stress concentration was observed at the tip of the straight bristles, and the stress was concentrated only near the base. Was recognized.

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

In the toothbrushes of Comparative Examples 2 to 4, hair breakage is likely to occur near the base of the hair when continuously used. It is considered that this is because the stress is concentrated only in the vicinity of the base of each hair during wiping and the fatigue is accumulated locally repeatedly, as recognized in the engineering simulation.
On the other hand, in the toothbrushes of Examples 7 to 13, the stress concentration points in each tapered bristles are two places, one in the vicinity of the small diameter portion and the vicinity in the vicinity of the base portion, at the time of wiping. Therefore, in the toothbrushes of Examples 7 to 13, stress is continuously concentrated only in the vicinity of the base of each tapered bristles during brushing, and fatigue is suppressed from locally accumulating. Excellent durability against hair breakage compared to toothbrushes.

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

Claims (6)

A toothbrush having a brush portion formed by implanting a plurality of hair bundles on the flocked surface of the head portion.
The tuft, the maximum stress to the maximum stress A1 taper portion is provided, or One Engineering as (a1) was calculated by the stress calculation method having及beauty Engineering as the (b1) to diameter toward the distal end to the distal end portion B1 It has tapered hair with a ratio B1 / A1 of 1.0 to 1.9.
In the step (a1) , the displacement of the tip of the tapered hair with respect to the base 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. the amount x1 (mm) of measured,
In the step (b1) , an engineering simulation is performed in which the tip of the tapered hair is displaced by the displacement amount x 1 (mm) in the direction perpendicular to the axial direction of the tapered hair, and the tip of the tapered hair is closer to the base than the tapered portion of the tapered hair. The maximum stress A1 generated in the taper portion and the maximum stress B1 generated in the tapered portion are calculated .
The tapered hair is formed of polytrimethylene terephthalate, and the tapered hair is formed of polytrimethylene terephthalate.
The tapered bristles are toothbrushes having stress concentration in the tapered portion and two locations closer to the base than the tapered portion in the step (b1). The length of the tapered portion is 3 to 11.5 mm, and the taper portion has a length of 3 to 11.5 mm.
The toothbrush according to claim 1, wherein the position of the boundary between the base and the tapered portion of the tapered bristles is equal to the position of the flocked surface, or the base is located outside the flocked surface. The toothbrush according to claim 1 or 2, wherein the diameter of the portion 0.1 mm from the tip of the tapered portion is 0.07 mm or less. A toothbrush having a brush portion formed by implanting a plurality of hair bundles on the flocked surface of the head portion.
The tuft is in Ri base preferred than the position of 0.1mm from Yoke tip small-diameter portion is provided with a cross sectional area of 14% or less of the cross-sectional area of the base portion, and extends toward the distal end from the base , It is provided with hair having a region having a larger cross-sectional area than the small diameter portion.
The bristles are tapered bristles provided with a tapered portion whose diameter decreases toward the tip, and the tapered portion has the small diameter portion.
The tapered hair is formed of polytrimethylene terephthalate, and the tapered hair is formed of polytrimethylene terephthalate.
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, the displacement amount x 2 (mm) of the tip with respect to the base portion of the hair in the surface direction of the hair-planted surface is measured. Then, when an engineering simulation was performed in which the tip of the hair was displaced by the displacement amount x2 (mm) in the direction perpendicular to the axial direction of the hair, the hair was near the base and on the tip side of the base. A toothbrush having stress concentration in the small-diameter portion or in the vicinity of the small-diameter portion. The toothbrush according to claim 4 , wherein A2> 0 and B2> 0 for the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following steps (a2) and the following steps (b2) in the hair. ..
(A2) 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, the amount of displacement of the tip with respect to the base portion of the hair in the surface direction of the flocked surface x 2 (mm). ) Is measured.
(B2) An engineering simulation was performed in which the tip of the hair was displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the hair, and the maximum stress concentration portion generated closest to the base of the hair was performed. The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side of the stress A2 are calculated. The toothbrush according to claim 4 , wherein B2 ≧ A2> 0 for the maximum stress A2 and the maximum stress B2 calculated by the stress calculation method having the following steps (a2) and the following steps (b2) in the hair.
(A2) 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, the amount of displacement of the tip with respect to the base portion of the hair in the surface direction of the flocked surface x 2 (mm). ) Is measured.
(B2) An engineering simulation was performed in which the tip of the hair was displaced by the displacement amount x2 (mm) in a direction perpendicular to the axial direction of the hair, and the maximum stress concentration portion generated closest to the base of the hair was performed. The stress A2 and the maximum stress B2 of the stress concentration portion generated on the tip side of the stress A2 are calculated.

Images