WO2008035713A1

WO2008035713A1 - Toothbrush

Info

Publication number: WO2008035713A1
Application number: PCT/JP2007/068190
Authority: WO
Inventors: Yusuke Hakamata; Toshiaki Kobayashi; Takao Kato
Original assignee: Lion Corporation
Priority date: 2006-09-19
Filing date: 2007-09-19
Publication date: 2008-03-27
Also published as: JPWO2008035713A1; JP5066527B2; CN101516232B; KR101320827B1; KR20090057013A; CN101516232A

Abstract

A toothbrush in which the bristles are less likely to have mechanical damage such as cracks and bends and that clearly indicates the time of toothbrush replacement by the degree of spread of the bristles. The toothbrush (10) has tufts (15) inserted into a tuft insertion surface, and the tufts (15) are each formed by binding bristles (1) made of a polytrimethylene terephthalate resin. Recesses (2) are formed in the surface of a bristle (1). The minimum cross-sectional area (S1) of the bristle (1) at the position where a recess (2) is formed is 40 to 80% of the maximum cross-sectional area (S2) of the bristle (1).

Description

Technical field

[0001] The present invention relates to a toothbrush using hair made of polytrimethylene terephthalate (PTT) resin.

In this application (September 2006, Japanese Patent Application No. 2006-252676 filed on September 19, 2006 (in which priority is claimed and the contents of which are incorporated herein by reference).

Background art

[0002] Toothbrush bristles generally use synthetic resin such as nylon resin (6-12 nylon, 6-10 nylon) polybutylene terephthalate (ΡΒΤ) resin, some of which are pork hair Natural hair such as! Is also used!

In recent years, toothbrushes using monofilaments made of polyester resin, polytrimethylene terephthalate (樹脂 ΡΤ) resin (for example, see Patent Document 1, Patent Document 2, and Patent Document 3), and transparency and flexibility Toothbrushes made of polytrimethylene terephthalate monofilaments having both durability and durability have been proposed (see, for example, Patent Document 4 and Patent Document 5). Toothbrushes using cocoon resin as bristles are superior in bending recovery and flexibility, and therefore maintain a high cleaning power for a long period of time, compared to the case of using nylon resin or cocoon resin. it can.

[0003] However, toothbrushes using hair made of cocoon resin are used for a long period of time because the hair is difficult to spread and the time for replacement of the toothbrush is unclear, and repeated force is continuously applied to the hair. Therefore, mechanical breakage such as tearing or breaking of the hair may occur.

[0004] In order to provide a toothbrush in which the bristle made of cocoon resin does not break, a toothbrush using synthetic resin monofilament made of coconut resin and polyester resin has been proposed! / (For example, see Patent Document 6).

In addition, in order to display the deterioration state of the toothbrush using the hair made of cocoon resin, the eyelash used for the hair has a double core-sheath structure, and the color of the hair or the color of the hair by wear is changed. The thing whose density changes has been proposed (see Patent Document 7). Technology described in Patent Document 7 Now, you can tell when to replace the toothbrush without depending on how the bristles open.

[0005] On the other hand, there is a toothbrush bristle that forms irregularities around the bristle and the entire cut end surface to improve tooth cleaning and gum massage (see Patent Document 8). In addition, as a toothbrush using a PTT resin, there is a toothbrush in which a string bristle in which a fine thread is knitted by a string string karoe is implanted around a core made of PTT fiber (see Patent Document 9). Patent Document 1: JP-A-8-173244

Patent Document 2: International Publication 01/75200 Pamphlet

Patent Document 3: Japanese Patent Publication No. 2001-511379

Patent Document 4: Japanese Unexamined Patent Publication No. 2006-2256

Patent Document 5: Japanese Unexamined Patent Publication No. 2006-37273

Patent Document 6: Japanese Unexamined Patent Application Publication No. 2005-270366

Patent Document 7: JP-A-2005-103184

Patent Document 8: Japanese Utility Model Publication No. 61-177027

Patent Document 9: JP-A-2004-81647

Disclosure of the invention

Problems to be solved by the invention

[0006] However, any conventional toothbrushes with bristle made of PTT resin may be used for a long time because the bristle is difficult to spread, and mechanical breakage such as tearing or breaking of the bristle is sufficient. Could not be prevented.

[0007] The present invention has been made in view of the above points, and provides a toothbrush in which the replacement time of a toothbrush is clarified depending on the extent of the bristle that is difficult to cause mechanical breakage such as tearing or breaking of the bristle. The purpose is to provide.

Means for solving the problem

[0008] The present inventor studied the mechanical breakage of PTT bristle as described below and arrived at the toothbrush of the present invention.

In other words, when PTT bristle is implanted in a toothbrush, it is difficult to open the hair due to high bend recovery, so it is used for a longer period of time than when nylon resin or PBT resin is used. For this reason, the load on the hair for brushing will also last for a long time. Normally, the toothbrush bristles are straight, and the force applied to the bristles during brushing is concentrated on the roots of the bristles (the roots planted on the flocking table), resulting in a heavy load on the roots of the bristles. It takes. For this reason, mechanical breakage such as tearing or breaking of the hair occurs at the root of the hair.

[0009] In addition, in order to prevent mechanical breakage of the PTT bristle, it is necessary to clarify the timing for replacing the toothbrush, encourage the toothbrush to be replaced, and replace the toothbrush before mechanical breakage occurs in the PTT bristle. Conceivable. In order to clarify the replacement timing of the toothbrush, it is conceivable to make the hair diameter narrower so that the hair becomes easier to spread and allow visual judgment. However, if the hair diameter is simply reduced, the hair becomes soft and the brushing force may be reduced, or the strength of the hair may be lowered and the hair may be broken.

[0010] Therefore, the present inventor has conducted extensive research, and the shape of the PTT hair is not concentrated only on the root of the hair by brushing the tooth, and the extent of the hair spread (flocked portion) The toothbrush according to the present invention is capable of preventing the mechanical breakage of the PTT hair by clarifying the replacement time of the toothbrush while ensuring sufficient durability by making the shape corresponding to the deterioration state of the hair. I found.

[0011] The toothbrush of the present invention is a toothbrush in which a bunch of bristles made of PTT resin is bundled on a flocked surface, and a plurality of recesses are formed on the surface of the bristles. The minimum cross-sectional area of the hair at the position where the recess is formed is 40% or more and 80% or less of the maximum cross-sectional area of the hair.

As described above, when a plurality of recesses are formed on the surface of the hair, the stress applied to the hair during the brushing is distributed to the plurality of recesses, so that the stress during the brushing is concentrated on the root of the hair. Therefore, the stress applied to the root of the hair is reduced as compared with the case where the concave portion is not formed on the surface of the hair.

In addition, if a concave portion is formed on the surface of the bristle, the bristle is likely to spread due to the stress applied to the concave portion that is applied at the time of brushing, so it is possible to visually clarify the replacement time of the toothbrush. It is possible to prompt the user to replace the toothbrush before the bristle breaks mechanically. Therefore, according to the present invention, it is possible to realize a toothbrush with a clear replacement timing that is difficult to cause tearing or breaking of the bristle. [0012] In the toothbrush of the present invention, the recess has a pitch in the extension direction of the bristle of 0.3 mm to 1.2 mm, and a length in the extension direction of 0.1 mm to 0.8 mm. The depth can be not less than 0.1 times and not more than 0.5 times the hair diameter.

By setting the pitch of the recesses, the length in the extension direction, and the depth in the above ranges, the opening ratio of the planted part of the PTT hair is improved, and high mechanical strength can be ensured.

The hair diameter here means the diameter when the hair cross-sectional shape is circular, and the length of one side when the hair cross-sectional shape is a regular polygon such as a regular triangle or a square.

The invention's effect

[0013] According to the present invention, it is possible to prevent tearing or breaking of the hair by reducing the force and stress concentration on the root of the hair. It is also possible to clarify the replacement period visually.

Brief Description of Drawings

FIG. 1 is a side view showing an example of a toothbrush of the present invention.

FIG. 2 is an enlarged perspective view showing one of the bristles constituting the toothbrush shown in FIG. 1 in an enlarged manner.

FIG. 3 is a side view of the hair shown in FIG. 2.

FIG. 4 is a cross-sectional view of the hair shown in FIG. 2, and is a cross-sectional view of a portion where a recess is formed.

Explanation of symbols

[0015] 1 bristles, 2 recesses, 10 toothbrushes, 11 heads, 12 flocked surfaces, 13 handle parts, 15 hair bundles, 21 and 22 recess units, A pitch, B length in extension direction (width), C Depth, D hair diameter (thickness), E center axis, S 1 minimum cross-sectional area, S2 maximum cross-sectional area Best Mode for Carrying Out the Invention

Next, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below. FIG. 1 is a side view showing an example of the toothbrush of the present invention. FIG. 2 is an enlarged perspective view showing one of the bristles constituting the toothbrush shown in FIG. 1 in an enlarged manner. FIG. 3 is a side view of the hair shown in FIG. 2, and FIG. 4 is a cross-sectional view of a portion where the concave portion of the hair shown in FIG. 2 is formed.

A toothbrush 10 shown in FIG. 1 includes a head portion 11 having a flocked surface 12 and a handle portion 13 extending from the rear end of the head portion 11. The handle portion 13 is for gripping the toothbrush 10, and can have any shape suitable for the brushing operation using the toothbrush 10.

Yes

The head portion 11 and the handle portion 13 can be formed by integral molding with a resin such as a hard resin. For the resin constituting the handle portion 13, a flexible resin such as an elastomer may be used at least in part for easy gripping.

[0018] Specific examples of materials for the head part 11 and the handle part 13 include polystyrene resin (PS), polypropylene resin (PP), polyethylene terephthalate resin (PET), acrylonitrile butadiene styrene resin (ABS), and cellulose. Propionate resin (CP), Polyarylate resin, Saturated polyester resin (PCTA, PCTG), Polycarbonate resin (PC), Atari port Nitryl styrene resin (AS), Polyacetal resin (POM), Polybutylene terephthalate (PBT) In addition, materials such as biodegradable resins can be used alone or in combination. It is also preferable to use a multi-color molded handle in which these resins are combined with thermoplastic elastomers, silicone resins, or the like. The material of the head part 11 and the handle part 13 is not limited by the above description.

A plurality of hair bundles 15 in which the hairs are bundled are planted on the hair transplant surface 12 of the head portion 11. As a method of flocking the hair bundle 15 to the head portion 11, it is possible to fix the hair bundle by a conventional method. For example, a flat wire (metal such as brass, stainless steel, biodegradable plastic, hard Flat wire flocking in which the hair bundle 15 is folded in two with a retaining member such as plastic), and the head portion 1 1 with one end of the hair bundle 15 joined by means of heat or the like and the joint portion is in the mold 1 1 In-mold flocking (for example, JP-A-61-268208, JP-A-9 512724) for filling and fixing the resin to be used, heat fusion flocking for fusing one end of the hair bundle 15 and the head portion 11 by means of heat or the like ( For example, it can be carried out by a method such as JP-A-60-241404). [0020] The shape of the flocked hole formed on the flocked surface 12 may be a normal circle, a square hole, a substantially elliptical shape, a substantially oval shape, a substantially rectangular shape, or the like having different major and minor diameters. The flock holes are usually arranged in a lattice or zigzag pattern, but a combination of flock hole shapes or a combination of the flock holes can be appropriately selected according to the intended function. In addition, the head part 11 is not subject to any restrictions on the shape and size design.For example, the minimum thickness of the head part 11 may be slightly different depending on the hair transplanting method using Hiraizumi or the flat wire! The thickness can be about 2 mm to 6 mm.

The hair 1 constituting the hair bundle 15 of the toothbrush 10 shown in FIG. 1 is made of polytrimethylene terephthalate (PTT) resin. The monofilament that becomes the hair 1 can be modified within a range that does not significantly impair the properties of the hair 1. Specifically, for example, PTT resin used as monofilament, heat and light stabilizers, flame retardants, fillers, surface lubricants, antistatic agents, modifiers such as bactericidal materials (antibacterial materials), other One or more hard resins or elastomers may be appropriately blended or applied to a monofilament.

[0022] In addition, the hair 1 can be used as it is as transparent hair, or it can be used as hair for transparent coloring with pigments or dyes, or hair for opaque coloring (including white). The toothbrush 10 is appropriately selected in consideration of the merchantability of the appearance. For transparent hair, transparent coloring hair, opaque coloring (including white) hair, two or more of them may be used in combination in the hair bundle unit or hair bundle, if necessary. .

Coloring hair, such as transparent coloring hair and opaque coloring (including white) hair, is generally attached to the method of coloring the resin itself during spinning, after spinning, or to the spinning process. Thus, it can be manufactured by a method of coloring from the surface. In addition, in the cut piece state (a bundle of hair length of about 25 to 35 mm) before planting the toothbrush 10, or after planting, only the tip of the hair 1 or all of the hair 1 is colored. You can also

[0023] When the concave portion 2 is provided on the surface of the hair 1, since the stress applied to the hair during the brushing is concentrated on the concave portion 2, the stress applied to the root of the hair 1 is reduced and the hair 1 Becomes easier to spread. However, in order to sufficiently prevent the hair 1 from being torn or broken, it is not necessary to provide the recess 2 on the surface of the hair 1. Minimum cross section S1 It must be 40% or more and 80% or less of the maximum cross-sectional area S2 of force hair 1.

Here,! /, The minimum cross-sectional area S 1 is the hair cross-sectional area that becomes the minimum when cut perpendicularly to the longitudinal direction of the hair! The shaded area in the figure). The maximum cross-sectional area S2 is a hair cross-sectional area obtained by wrapping a line obtained by connecting the outermost sides before and after the recess formed in the hair.

[0024] If the minimum cross-sectional area S1 is less than 40% of the maximum cross-sectional area S2 of the bristle 1 ((S1 / S2) X 100 to 40 (%)), the mechanical strength of the portion where the recess 2 is formed is remarkably high. As a result, the original strength of the hair 1 cannot be exhibited, and the bending strength is significantly reduced. In addition, the spread of the hair 1 due to brushing is comparable to that of general nylon hair, and the bending durability of the PTT hair is lost. On the other hand, when the minimum cross-sectional area S1 exceeds 80% of the maximum cross-sectional area S2 of the hair 1, ((S 1 / S2) X 100> 80 (%)), As a result, the opening of the hair 1 becomes inadequate, the replacement time becomes unclear, and the hair 1 may break due to continued use.

Further, the pitch A of the recesses 2 shown in FIG. 3 is preferably 0.3 mm or more and 1.2 mm or less, more preferably 0.5 mm or more and 1.0 mm or less. Here, the pitch A of the recesses 2 means a distance between the recesses 2 adjacent to each other in the extending direction of the hair 1. Further, the distance between adjacent recesses 2 refers to the distance between the center positions of the hairs 1 in the recess 2 in the extending direction. The length B (width) of the recess 2 in the extending direction is preferably 0.1 mm or more and 0.8 mm or less, and more preferably 0.2 mm or more and 0.5 mm or less.

The depth C, which is the distance from the line obtained by connecting the outermost sides of the recess 3 shown in FIGS. 3 and 4 to the valley bottom of the recess 2, is 0.1 to 0.5 times the bristle diameter D. It is preferable that the ratio is 0.1 times or more and 0.3 times or less.

[0026] Further, the thickness of the hair 1 is preferably 3 to 10 mil (0.076—0.254 mm), preferably 5 to 8 mil (0.125-0.203 mm). In consideration of brushing feeling, cleaning effect, durability, etc., a plurality of bristles having different thicknesses may be used in combination as bristles constituting one toothbrush. In particular, in the specification in which a large number of flock holes are arranged on the flocked surface 12, the strength of the hair can be increased or changed (thickness, material, length, color, cross-sectional shape) from the outside toward the center. Also preferred in terms of usability and appearance discrimination! [0027] In addition, the cross-sectional shape of the hair can be a straight line, a curved line, a curved line, a curved line, or a polygonal shape such as a circle, an ellipse, a triangle, or a rectangle, a star shape, a three-leaf or a four-leaf clover. It may be a combined irregular shape.

[0028] The method for producing such a monofilament to be used as the hair 1 is not particularly limited. For example, the monofilament can be produced by using an ordinary method for producing a coextruded monofilament. Further, the method for forming the recess 2 provided on the surface of the hair 1 is not particularly limited. 1S For example, before or after the stretching step or annealing step in manufacturing the monofilament, for example, the shape of the recess 2 A roller having a U-shaped convex section corresponding to the above can be formed so as to face up and down or left and right, and the monofilament pass between the opposed rollers. The recess 2 can also be formed by passing the monofilament between the rollers arranged opposite to each other while performing heat treatment when the monofilament is passed between the rollers arranged opposite to each other.

[0029] The formation position of the recess 2 is not limited to the above embodiment. For example, in the above embodiment, the surface of the bristle 1 is provided with the two rows of the recessed units 21 and 22, but the recessed unit may be a single row. Further, in the above embodiment, the force of the recesses of the recess unit 21 in the extending direction of the force bristles 1 in which the two rows of recess units 21 and 22 are arranged symmetrically with respect to the central axis E of the hair 1 The unit 22 may be arranged so as to be in the center of the adjacent recesses.

[0030] The shape of the concave portion 2 of the hair 1 may be a U-shape, a V-shape, a U-shape, or a C-shape in a sectional view of the hair 1 in the extending direction. Further, all the concave portions of the hair 1 may have the same shape, or some or all of them may be different. Further, the concave portion of the bristle may be a groove provided over the entire circumference of the bristle. Further, the concave portion of the hair is preferably applied over the entire length of the hair, but may be appropriately selected depending on the size of the concave portion, the cross-sectional shape of the hair, the diameter of the hair.

When forming a recess having such a shape, it corresponds to the shape of the recess to be formed, such as a hemisphere, a substantially polygon (rectangle, triangle), a substantially oval, etc. By using a roller having a convex portion, the hair of the above embodiment

It can be formed in the same way as 1. [0031] Further, as another example of the bristle 1 having the concave portion 2 on the surface, for example, when spinning the bristle 1, an inorganic material is previously placed in a master batch and used for spinning using this. Hair surface The hair obtained by dissolving random precipitates on the surface obtained by dissolving the precipitate is referred to by force S.

Further, the tip of the hair may be tapered by a chemical method in which the hair is dissolved in an acid or an alkaline agent, or a polishing method in which the hair tip is mechanically polished after being implanted into a toothbrush. As a polishing method, for example, the brush pruning surface and the planting surface are planted by a polishing body that rotates along a first rotation axis and a bearing that supports the first rotation axis rotates along the second rotation axis. It is possible to cite a method using a manufacturing device that processes the surface between the installation surfaces into a smooth taper.

The depth of the recess when the hair tip is tapered refers to the distance from the line obtained by connecting the outermost front and back of the recess formed in the tapered portion to the valley bottom of the recess.

[0032] Further, depending on the manufacturing method of the toothbrush 10, the spun hair after spinning may be bundled in a predetermined number and wound on a spool, or cut to a certain length and straight from several centimeters to 10cm. In order to further reduce the residual strain of hair after being bundled to a certain diameter and wound with paper or film, for example, an offline heat treatment at 60 ° C to 160 ° C for several minutes to several days is performed. It can also be done.

[0033] In addition, the hair cutting (or profile) shape and hair length of the end portion of the toothbrush 10 can be arbitrarily set, for example, a single flat shape, a mountain shape, or an uneven shape. Alternatively, the outer side and the inner side, the front end part and the rear end part may have different shapes.

[0034] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

"Example 1 to Example 10, Comparative Example 1 to Comparative Example 3"

A bunch of bristles made of PTT resin shown in Table 1 or Table 2 is planted on a flocked surface with 23 flock holes, and a headbrush and a needle part are made of PCTA resin. Shipu.

Comparative Example 4

Example 1 to Example 10 and Comparative Example 1 except that hair made of nylon resin was used A toothbrush was manufactured in the same manner as in Comparative Example 3.

[0035] Table 1 or Table 2 shows a side view of the hair used in the toothbrushes of Examples 1 to 10 and Comparative Examples 1 to 4, a cross-sectional view at the position of the arrow shown in the side view, and a minimum section. Indicates the ratio of the maximum cross-sectional area S2 to the area S1 ((S1 / S2) X 100 (%)), hair dimensions (pitch, depth, width), and hair diameter. In the cross-sectional views of Tables 1 and 2, the area indicated by the diagonal lines is the minimum cross-sectional area S1, and the area surrounded by the dotted line is the maximum cross-sectional area S2.

[0036] [Table 1]

[0037] [Table 2]

[0038] Using the toothbrushes of Examples 1 to 10 and Comparative Examples 1 to 4, the following (1) bristle durability test and (2) sensory evaluation were performed. The results are shown in Table 3.

[0039] [Table 3] Durability for hair sensory evaluation Overall evaluation

Example 1 ○ ○ ○ ○ Example 2 ○ ○ ○ ○ Example 3 ○ ○ ○ ○ Example 4 Δ ○ Δ Δ Example 5 Δ ○ ○ Δ Example 6 Δ ○ Δ Δ Example 7 Δ ○ Δ Δ Example 8 △ ○ ○ Δ Example 9 ○ ○ ○ ○ Example 1 0 ○ ○ ○ ○ Comparative Example 1 XXXX Comparative Example 2 XXXX Comparative Example 3 X ○ ○ X Comparative Example 4 X ○ ○ X [0040] (1) Hair durability test

The toothbrushes of Examples 1 to 10 and Comparative Examples 1 to 4 were set in a model durability tester, and the flocking part opening rate and the broken hair test were performed as shown below. In the test method, the head portion of the toothbrush is placed on a metal corrugated plate and placed in parallel with the corrugated plate so that the tip of the bristle contacts the corrugated plate surface. Immerse the whole in hot water of 35 ° C. Then, with a 400g load applied to the head of the toothbrush, the head was reciprocated 10 million times at a reciprocating speed of 150 times / min and a brushing stroke of 40 mm in a direction perpendicular to the wave of the corrugated plate. The toothbrush was opened and evaluated for openness and broken hair.

[0041] <Flocking area opening ratio>

Before brushing (before hair durability test), measure the width of the flocked portion of the flocks that have been flocked to the head (full width at the tip of the flocks in the direction perpendicular to the longitudinal direction of the hand nore). Durability After the specified number of times (100,000 times) was wiped with a testing machine, the width of the flocked portion was measured again, and the difference was divided by the width of the flocked portion before the brushing and multiplied by 100 and displayed as a percentage. The width of the flocked part was measured at a position including the hair bundle facing outward. In addition, the flocked area opening rate was evaluated according to the following criteria.

Flocking area opening ratio (%) = ((Flocked part width after brushing) Flocked part width before brushing) / (Flocked part width before brushing)) X 100

○: 30% or more and less than 60%

Δ: 20% or more but less than 30% or 60% or more and less than 80%

X: Less than 20% or 80% or more

[0042] <Broken hair>

After the predetermined number of times of wiping, the occurrence of breakage at the root of the hair was visually observed and evaluated according to the following criteria.

○: No breakage

X: For broken hair

[0043] (2) Sensory evaluation

Test whether the toothbrush open state and the replacement time are linked. A seven-step sensory evaluation was conducted by 20 expert panelists using the toothbrush after the test was completed, and the following criteria were used.

1: Linked at all! /, Na! / ヽ 2: Linked with power, na!

3: Not very linked 4: Neither

5: Somewhat linked 6: Very linked

7: Very linked

〇: Average score is 6 or more

Δ: The average score is more than 4 and less than 6

X: 4 points or less

[0044] The overall evaluation was made based on the results of flocked portion opening rate, broken hair, and sensory evaluation.

〇: All are 〇

△: Evaluation power S “○” or “△” means “X” is! / ヽ

X: "X" in either

[0045] As shown in Tables 1 to 3, a plurality of recesses are formed on the surface of the hair, and the minimum cross-sectional area S1 of the hair is 40% or more and 80% or less of the maximum cross-sectional area S2 of the hair In Examples 1 to 10 which are the above, all evaluations for broken hair were ◯, and the overall evaluation was ◯ or Δ.

On the other hand, in Comparative Example 1 in which the concave portion is not formed in the hair, and in Comparative Example 2 in which the ratio of the maximum cross-sectional area S2 to the minimum cross-sectional area S1 in which the depth of the concave portion is shallower than the preferred range exceeds 80% The evaluation of the opening ratio of the flocked part with an extremely low flocking part opening ratio was X. In Comparative Example 1 and Comparative Example 2, the sensory evaluation was also X, and it was found that the extent of the bristles (the rate of flocking of the flocks) did not correspond to the timing of toothbrush replacement. Further, in Comparative Example 1 and Comparative Example 2, the evaluation of broken hair was X, and the overall evaluation was X.

In Comparative Example 3 in which the ratio of the maximum cross-sectional area S2 to the minimum cross-sectional area S1 is less than 40% and Comparative Example 4 in which the hair made of nylon resin was used, the hair was not broken, but the flocked portion was opened. The evaluation of the opening ratio of the flocked part with a very high rate was X.

Next, another example of the present invention will be shown.

`` Example 11 to Example 18 ''

Except for using hair made of PTT resin shown in Table 3, Example 1 to Example 10, ratio Toothbrushes were manufactured in the same manner as Comparative Examples 1 to 4.

[0047] Table 4 shows a side view of the hair used in the toothbrushes of Examples 11 to 18, a cross-sectional view at the position of the arrow shown in the side view, and a ratio of the maximum cross-sectional area S2 to the minimum cross-sectional area S1 (( S 1 / S2) X 100 (%)), hair dimensions (pitch, depth, width), hair diameter. In the cross-sectional view of Table 4, the area of the hatched portion is the minimum cross-sectional area S1, and the portion surrounded by the dotted line is the maximum cross-sectional area S2.

[0048] [Table 4]

[0049] (1) Hair durability test and (2) Sensory evaluation in the same manner as in Examples 1 to 10 and Comparative Examples 1 to 4, using the toothbrushes of Examples 11 to 18. And performed. The results are shown in Table 5.

[0050] [Table 5] Hair durability Sensory evaluation Overall evaluation

Flocking rate for flocking part

Example 1 1 Δ ○ Δ Δ Example 1 2 ○ ○ ○ ○ Example 1 3 Δ ○ Δ Δ Example 1 4 ○ ○ ○ ○ Example 1 5 ○ ○ ○ ○ Example 1 6 Δ ○ Δ Δ Example 1 7 ○ ○ ○ ○ Example 1 8 ○ ○ ○ ○

[0051] As shown in Table 4 and Table 5, a plurality of recesses are formed on the surface of the hair, and the minimum cross-sectional area S1 of the hair is 40% or more and 80% or less of the maximum cross-sectional area S2 of the hair In Examples 11 to 18, the evaluations for broken hair were all ◯, and the overall evaluation was ◯ or Δ. Industrial applicability

[0052] The toothbrush of the present invention can prevent tearing or breaking of the bristle by reducing stress concentration on the root of the bristle. Further, according to the present invention, it is possible to provide a toothbrush that can clearly identify the replacement time.

Claims

The scope of the claims

[1] A toothbrush in which a bunch of bristles made of polytrimethylene terephthalate resin is planted on a flocked surface,

A plurality of recesses are formed on the surface of the hair, and the minimum cross-sectional area of the hair at the position where the recess is formed is 40% or more and 80% or less of the maximum cross-sectional area of the hair. A toothbrush characterized by having

[2] The recess has a pitch in the extension direction of the hair of 0.3 mm to 1.2 mm, a length in the extension direction of 0.1 mm to 0.8 mm, and a depth of the hair diameter of 0 mm. The toothbrush according to claim 1, wherein the toothbrush is at least 1 time and at most 0.5 time.