CN110113963B

CN110113963B - Tooth brush

Info

Publication number: CN110113963B
Application number: CN201780079816.XA
Authority: CN
Inventors: 野泽纱弥; 金丸直史
Original assignee: Lion Corp
Current assignee: Lion Corp
Priority date: 2017-01-17
Filing date: 2017-11-30
Publication date: 2021-10-22
Anticipated expiration: 2037-11-30
Also published as: WO2018135150A1; KR20190102171A; KR20230027311A; CN110113963A; JP6906313B2; MY194816A; JP2018114063A

Abstract

The invention provides a toothbrush which does not generate warpage, whitening and cracking of resin in a head part of a flat line type hair planting method, ensures enough hair planting strength and has excellent oral cavity operability. The toothbrush (1) is provided with a head (10) provided with a plurality of planting holes (13) on a planting surface (12), the hair bundle bundled with a plurality of bristles is folded into two by a flat wire (15) and planted in the planting holes (13), wherein the thickness of the head (10) is more than 2.0mm and less than 4.0 mm; the density of the hair planting holes (13) is 25 holes/cm²The above; when the inner diameter of the hair planting hole is X, the thickness of the flat wire is d, and the X is more than 0.9mm and less than 1.3mm, the relation of (X-d)/2 which is more than or equal to 0.37mm and less than or equal to 0.55mm is satisfied.

Description

Tooth brush

Technical Field

The present invention relates to toothbrushes.

The present application claims priority from japanese patent application No. 2017-005804 filed in japan on 17/1/2017, and the contents of which are incorporated herein by reference.

Background

In order to prevent periodontal disease, it is important to remove tartar from narrow gaps such as the cervical region and the interdental region. Therefore, the following studies have been conducted: in order to improve the entering property of the front end of the toothbrush hair into the narrow gap, the front end ultra-fine bristle is used; making the holes smaller in order to impart a moderate deflection to the tufts; and expanding the arrangement interval of the implanted pores.

The small holes for implanting the bristles make the bristles easily flexible, which is very effective as a means for improving the penetration of the tips of the bristles, but the small holes reduce the amount of bristles, resulting in a decrease in brush-wiping feeling. Therefore, a hair-planted portion means has been studied which combines the penetration of the tip of the hair and the brush-solid feeling by increasing the number of holes.

In the case of the flat-wire type hair-planting method, if the number of holes is large, the number of flat wires to be driven into the head portion is large, and the resin pushed away by the flat wires is also large, so that warpage of the head portion, cracking of the resin, and whitening may easily occur, but patent document 1 discloses the following toothbrush: the head of the small-hole-multiple-hole simultaneous flat-line tufting method is free from warpage, whitening of resin and cracking, and can ensure sufficient tufting strength.

This toothbrush prevents the head from warping by setting the volume of resin destroyed by the flat wire (resin destruction volume) within a predetermined range.

Documents of the prior art

Patent document

Patent document 1: JP 2005-177377A

Disclosure of Invention

Problems to be solved by the invention

In addition, in some toothbrushes, the head may be thinned in order to improve the operability and to enable brushing at various corners in the oral cavity. However, when the head is thinned, the ratio of the flat wire to the head resin is relatively increased, and thus the head is likely to be warped, whitened, or cracked. In particular, in the case of "small hole × porous", the number of flat wires to be driven into the head portion increases, and warpage, whitening, and cracks are more likely to occur, and therefore, it is impossible to realize a hair-planted portion means having a small hole × porous structure in which the head portion is made thin.

Therefore, the inventors further conducted experiments and studies and found that: the warpage of the head is closely related to the inner diameter of the implanted hole, the density of the implanted hole, the driving depth of the flat wire into the implanted hole, and the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a toothbrush which ensures sufficient bristle-implanting strength without causing warpage, whitening of resin, or cracking in a head portion of a flat-line bristle-implanting method, and which is excellent in oral operability.

Means for solving the problems

To achieve the above objects, one embodiment of the present inventionA toothbrush of the type having a head portion with a plurality of implanted holes formed in an implanted surface thereof, the implanted holes being implanted by folding a tuft of a plurality of bristles in two by a flat wire (flat plate), wherein the head portion has a thickness of 2.0mm to 4.0mm, and the area of a portion where the outer sides of the implanted holes are connected by a straight line is set to an implanted area (cm)²) In time, the total number of implanted holes (holes)/implanted area (cm)²) The indicated hole density of the flocking was 25 holes/cm²When the inner diameter of the implanted pore is X, the thickness of the flat wire is d, and X is more than 0.9mm and less than 1.3mm, the relationship of (X-d)/2 is more than or equal to 0.37mm and less than or equal to 0.55mm is satisfied.

In the toothbrush according to the embodiment of the present invention, a volume of the flat wire to be embedded in the implantation hole (a volume of a pair of embedded portions of the flat wire to be embedded in the head at a radially outer side of the implantation hole) may be 0.06mm³Above 0.20mm³The following.

Here, the buried volume of the flat wire corresponds to the volume of a pair of buried portions of the flat wire buried in the head portion radially outside the bristle implanting hole.

The toothbrush according to an embodiment of the present invention may have the following configuration: the flat wire has a plurality of grooves on both sides.

The toothbrush according to an embodiment of the present invention may have the following configuration: the head is formed of a resin having a flexural modulus of elasticity of 1000MPa to 2800 MPa.

Effects of the invention

The toothbrush of the present invention ensures sufficient bristle-implanting strength without causing warpage, whitening and cracking of the resin in the head of the flat-wire bristle-implanting method, has excellent oral operability, and can sufficiently brush the neck of the posterior teeth.

Drawings

Fig. 1A is a plan view showing a toothbrush according to an embodiment of the present invention.

Fig. 1B is a side view showing a toothbrush according to an embodiment of the present invention.

Fig. 2A is a view showing implanted holes, which is a cross-sectional view along the longitudinal and lateral directions.

Fig. 2B is a view showing a implanted hole, which is a sectional view along the height direction.

FIG. 3 is a side view showing a flat wire.

FIG. 4 is a diagram showing specifications of examples and comparative examples and evaluations thereof.

[ description of symbols ]

1 … toothbrush; 10 … a head; 11 … tufts; 11a … bristles; 12 … flocking surface; 13 … implanting pores; 15 … flat wire; 15a … side; 16 … grooves; 20 … neck; 30 … handle portion; 35 … finger rest projections; t … thickness; x … inside diameter of implanted pores.

Detailed Description

Hereinafter, an embodiment of the toothbrush of the present invention will be described with reference to fig. 1A, 1B to 4.

Fig. 1A and 1B are views showing a toothbrush 1 according to the present embodiment, and are (a) plan views and (B) side views.

The toothbrush 1 includes: a head portion 10 of the bundle 11 implanted with the brush staples 11a, a neck portion 20 extended from a rear end side of the head portion 10, and a handle portion 30 extended from a rear end side of the neck portion 20.

Hereinafter, the head 10, the neck 20, and the handle 30 are collectively referred to as a handle body 40.

As shown in fig. 1A and 1B, the head 10 is a portion of the handle body 40 on the distal side.

The neck portion 20 is a portion of the handle body 40 that is continuous with the rear end side of the head portion 10.

As shown in fig. 1A and 1B, the handle portion 30 is a portion of the handle body 40 opposite to the head portion 10 and up to the finger-touch portion 35.

The structure of each part will be described in detail below.

Hereinafter, the longitudinal direction of the head 10 (the left-right direction in fig. 1A and 1B) is referred to as the longitudinal direction. The width direction (vertical direction in fig. 1A) of the head 10 is referred to as a lateral direction. The thickness direction (vertical direction in fig. 1B) of the head 10 is referred to as height or thickness.

The handle body 40 is integrally formed in a long shape as a whole, and may be obtained by injection molding using resin as a material, for example.

Examples of the material of the integrally molded handle body 40 include resins having a flexural modulus of elasticity (JIS7171) of 1000MPa or more and 2800MPa or less, and examples thereof include polypropylene resins (PP), polyacetal resins (POM), saturated polyester resins (PCTA), polystyrene resins (PS), polyethylene terephthalate resins (PET), polybutylene terephthalate resins (PBT), acrylonitrile butadiene styrene resins (ABS), polyarylate resins, polycarbonate resins, and acrylonitrile styrene resins (AS).

Among these, polypropylene resins are preferable from the viewpoint that the cost can be controlled. On the other hand, since the polypropylene resin has a flexural modulus of 1500MPa or more and 2000MPa or less, warpage and the like are likely to occur when the head portion 10 is thinned. However, by adopting the shape of the toothbrush 1 of the present embodiment described later, a resin having a low flexural modulus of elasticity such as polypropylene may be used.

The resin can be used alone in 1, or can be combined with more than 2.

In order to improve the gripping performance, the handle body 40 may be partially or entirely covered with a soft resin such as an elastomer.

The flexural modulus of the handle body 40 (JIS7171), that is, the flexural modulus of the resin used as the material of the handle body 40, is preferably 1000MPa or more and 2800MPa or less, more preferably 1200MPa or more and 2500MPa or less, and still more preferably 1500MPa or more and 2000MPa or less.

In the present embodiment, the handle body 40 is integrally formed as a single piece, but is not limited to the structure in which the head 10, the neck 20, and the handle 30 are integrally formed. For example, the following configuration is possible: at least one of the head 10, the neck 20, and the handle 30 is made of different materials and joined together.

When the head section 10, the neck section 20, and the handle section 30 are made of different materials, at least the head section 10 is made of the above-mentioned material. At this time, the flexural modulus (JIS7171) of at least the head 10 is preferably 1000MPa or more and 2800MPa or less, more preferably 1200MPa or more and 2500MPa or less, and still more preferably 1500MPa or more and 2000MPa or less.

The overall length of the handle body 40 can be determined according to operability and the like. The overall length of the handle body 40 is, for example, about 150 to 200 mm.

The head 10 has a flat plate shape of an approximate quadrangle whose top is cut off in a curved line in a plan view. The size of the head 10 can be determined in consideration of characteristics such as intraoral operability.

If the width of the head 10 is too large, the operability in the oral cavity is deteriorated, and if the width is too small, the number of implanted tufts 11 becomes too small, and the cleaning effect is easily impaired. Therefore, the maximum width of the lateral width of the head 10 can be set to, for example, about 5mm to 16mm, and is preferably 11mm or less from the viewpoint of insertability into the insertion port cavity.

If the length of the head 10 is too long, the operability in the oral cavity is easily impaired, and if the length is too short, the number of implanted tufts 11 becomes too small, and the cleaning effect is easily impaired. Therefore, the length of the head 10 can be set in the range of 10mm to 33mm, for example.

The thickness (height) t of the head 10 is preferably in the range of 2.0mm to 4.0mm, more preferably 2.5mm to 3.5 mm. As shown in fig. 1B, when the thickness t of the head 10 is equal to or less than the upper limit, the oral cavity operability of the toothbrush 1 can be improved. When the minimum thickness of the head 10 is equal to or greater than the lower limit, the strength of the head 10 can be prevented from being reduced.

As shown in fig. 1A, a plurality of implantation holes 13 are formed in the surface of the head 10, i.e., the implantation surface 12. The inner diameter X of the implantation hole 13 is preferably in the range of 0.9mm to 1.3 mm. Within this range, the implanted holes 13 become small holes, and the outer diameter of the bundle 11 becomes small. The inner diameter X of the implantation hole 13 is more preferably in the range of 1.0mm to 1.3mm, and still more preferably 1.1mm to 1.3 mm. In each implanted hole 13, a bundle of bristles 11 is implanted.

As the bristles 11a constituting the tuft 11, there can be used: bristles (tapered bristles) having a gradually decreasing diameter toward the bristle tip, bristles (straight bristles) having substantially the same outer diameter except for the circular portion of the bristle tip, and bristles having flat, spherical, or bifurcated tip shapes.

Examples of the material of the brush bristles 11a include: polyamide (e.g., 6-12 nylon and 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate), polyolefin (e.g., polypropylene), and elastomer (e.g., olefin-based or styrene-based). These resin materials may be used alone in 1 kind or in combination of 2 or more kinds.

In particular, the bristles 11a are preferably made of polyester and have a multiple-core sheath structure (double-core sheath structure) including a core and at least 1 or more sheath portions provided outside the core. When the core-sheath structure has a multiple core-sheath structure (double core-sheath structure), different polyesters can be used for the core and the sheath, and thus adjustment of mechanical properties becomes easy. Therefore, bristles having high rigidity and high tartar removal performance can be easily obtained. As a combination of different polyesters that can be used in the bristles of the core and the sheath, polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) are preferable, for example.

Therefore, in the present embodiment, as the bristles 11a, bristles having a double core-sheath structure (double core-sheath ST bristles) in which a core portion is formed of polybutylene terephthalate resin (PBT) and a sheath portion is formed of polyethylene terephthalate resin (PET) are used. Therefore, bristles having high rigidity and high tartar removal performance can be easily obtained.

The cross-sectional shape of the bristles 11a is preferably circular, but is not necessarily limited to circular, and may be set to any shape according to the intended use of the toothbrush 1. For example, it may be set to an oval shape, a polygonal shape (e.g., a triangle, a quadrangle, a pentagon, a hexagon, etc.), an irregular shape (e.g., a star shape, a three-leaf clover shape of three leaves, a four-leaf clover shape of four leaves, etc.), or the like.

The bristles 11a constituting the tuft 11 may all be the same thickness, or 2 or more different thicknesses of the bristles 11a may be combined. In view of usability and feeling of use in the oral cavity, it is preferable that the smaller the diameter of the selected bristle 11a is, the shorter the bristle length of the bristle 11a is. Further, a plurality of bristles 11a having different thicknesses may be used in combination for the purpose of a feeling of use, a brushing feeling, a cleaning effect, durability, and the like.

The length of the neck 20 is preferably 25 to 70mm, for example, so that the neck 20 contacts the lips when the head 10 is inserted into the oral cavity.

The neck portion 20 in the present embodiment is formed as follows: the width gradually increases from the position 21 of the minimum value toward the rear end side. The width of the neck portion 20 may be determined in consideration of material, etc., and for example, the minimum width of the neck portion 20 is preferably 3.5mm or more and 4.5mm or less, and more preferably 3.7mm or more and 4.3mm or less. When the lower limit value is not less than the lower limit value, the strength of the neck portion 20 can be further improved, and when the upper limit value is not more than the upper limit value, the lips are easily closed, and the accessibility to posterior teeth can be improved, and the oral cavity operability can be further improved.

Fig. 2A is a view showing the implant hole 13, which is a cross-sectional view along the longitudinal and lateral directions. Fig. 2B is a sectional view along the height direction. Fig. 3 is a side view showing the flat wire 15.

Hereinafter, the longitudinal direction (the left-right direction in fig. 2A and 3) of the flat wire 15 is referred to as the longitudinal direction. The width direction (vertical direction in fig. 2A) of the flat wire 15 is referred to as a lateral direction or a thickness direction. The thickness direction of the flat wire 15 (vertical direction in fig. 2B and 3) is referred to as "height".

The tufting method of tuft 11 was according to the following flat-line tufting method: a flat-wire type hair-planting method in which a bundle of bristles 11a is cut into two, and a flat wire 15 is driven into a hair-planting hole 13, thereby planting the bundle of bristles 11 into the hair-planting hole 13. The flocking strength is preferably 8N or more, more preferably 10N or more, and particularly preferably 15N or more.

The flat wire 15 is driven into the implantation hole 13 so as to pass through the center of the implantation hole 13 and to cross the implantation hole 13. Examples of the material of the flat wire 15 include metal pieces such as brass and stainless steel, and hard plastics and biodegradable plastics.

As shown in FIG. 3, the thickness d of the flat wire 15 is preferably 0.15mm to 0.30mm, more preferably 0.18mm to 0.25mm, and still more preferably 0.18mm to 0.22 mm.

The height H of the flat wire 15 is preferably 1.0mm to 1.5mm, more preferably 1.0mm to 1.3 mm.

The length L1 of the flat wire 15 is preferably 1.4mm to 1.8 mm.

Preferably, the flat wire 15 is formed with a plurality of grooves 16 on each

side surface

15a, 15 a. The width w1 of the groove 16 is 0.1-0.3 mm, and the height h1 is 0.03-0.075 mm.

In addition, the shape, number, and the like of the grooves 16 are not limited to those shown in the drawings. In addition, the grooved wire is preferable in view of difficulty in detachment of the flat wire 15, but the grooved wire is not limited thereto. A flat wire in the form of a flat plate without grooves may be used.

The hair-planted surface 12 of the head 10 has a plurality of hair-planted holes 13 formed therein, but the arrangement pattern thereof is not particularly limited. For example, as shown in FIG. 1A, the implanted holes 13 may be formed in an array of 3 to 5 rows in the width direction of the

head

10 and 10 to 12 rows in the length direction of the head 10, or may be in a U-shaped array such as an unworn region surrounding a part thereof.

In any pore arrangement, the area of the implanted range 13A in which the outer side (tangent line) of the implanted pore 13 is linearly connected is set as the implanted area (cm)²) The total number (holes)/area (cm) of implanted holes 13 is measured²) The density of the hair-planting holes (the number of hair-planting holes per unit area) is preferably 25 holes/cm²Above, more preferably 28 holes/cm²Above, more preferably 30 pores/cm²The above. In addition, it is preferably 40 holes/cm²Hereinafter, more preferably 37 holes/cm². Within this range, the bristle hole density is increased (the number of holes is increased, the amount of bristles is increased), and a high brush-brushing feeling can be maintained even in the case of fine bristle bundles.

As shown in fig. 2A, the toothbrush 1 of the present embodiment is set to: when the inner diameter of the hair-planting hole 13 is X, the thickness of the flat wire 15 is d, and X is 0.9mm to 1.3mm, the following formula (1) is satisfied.

0.37mm≤(X－d)/2≤0.55mm···(1)

As shown in FIG. 2B, the depth M of the implanted hole 13 is preferably in the range of 2.2 to 3.5 mm. In order to secure the depth of the implanted hole 13, the back surface thickness of the head 10 (the thickness N from the bottom 13b of the implanted hole 13 to the back surface 14 of the head 10) is preferably 0.7mm or less. The pitch of the flocking holes (the distance between the centers of the adjacent 2 flocking holes 13) is preferably 1.2 to 2.4 mm.

Here, the ratio of the total bristle area B to the actual total bristle area a obtained by subtracting the area of the flat wire 15 from the area of one implanted hole 13 is set as a packing factor (B/a × 100%).

In the flat-wire type hair-planting method, since the bundle of bristles 11 is folded and fixed to the head 10 by the flat wire 15, when the hair is planted at a filling factor of a predetermined value or more, as shown in fig. 2A and 2B, the value of (X-d)/2 of the expression (1) is related to the thickness of the bundle of bristles 11, which becomes an index indicating the distance from the hole bottom 13B of the hair-planting hole 13 to the bottom surface 15c of the flat wire 15 and also becomes an index indicating the driving depth of the flat wire 15.

In the toothbrush 1, as shown in fig. 1B, the thickness t of the head 10 is small, and when the hole density of the implanted holes 13 is high, the head 10 is likely to warp. In the toothbrush 1 with the thin head 10, when the flat wire 15 is driven into the implantation hole 13 to be shallow, the head 10 is warped. The reason is considered to be that: the resin near the opening of the flocked hole 13 is pushed away to expand the hole diameter, whereby the flocked face 12 is expanded. Therefore, as the density of implanted holes in the implanted holes 13 increases, the number of flat wires 15 driven increases, and the head 10 is likely to be significantly warped.

On the other hand, when the flat wire 15 is driven deeply into the implantation hole 13, the head 10 is less likely to warp. Although the reason is not clear, it is considered that the reason is: by driving the flat wire 15 deeper than the implantation hole 13, the resin is pushed to the bottom side of the implantation hole 13, and thus the diameter of the implantation hole 13 on the opening side is less likely to change. From this it is assumed that: the flocked surface 12 is not expanded, and the head 10 is less likely to warp.

Therefore, in the toothbrush 1 having the head 10 thinned as in the present embodiment, the conditions are set so as to fall within the range of the formula (1), whereby the warpage of the head 10, whitening of the resin, and the occurrence of cracks can be prevented. From the viewpoint of the formula (1), it is preferable that the depth of penetration of the flat wire 15 into the implantation hole 13 is 0.45mm or more because good implantation strength can be obtained. From the viewpoint of expression (1), it is preferable that the depth of penetration of the flat wire 15 into the implantation hole 13 is 0.55mm or less because the strength of the head 10 can be further maintained. When the driving depth of the flat wire 15 into the implantation hole 13 is within the above range, the implantation hole 13 becomes small and the tuft diameter becomes small, so that the penetration ability into narrow gaps of teeth can be improved.

In addition, in the toothbrush 1, the volume of the flat wire 15 embedded in the implantation hole 13 is 0.06mm³Above, 0.20mm³Below (particularly preferably at 0.08 mm)³Above, 0.13mm³Below), even if the head 10 has small holes and the density of the flocked holes is high, the head can be prevented from warping, whitening, and cracking.

The inner diameter X of the implanted hole 13 is 0.9 mm-1.3 mm. Therefore, the flat wire 15 is embedded in the resin of the head 10 in a range of 0.2mm to 0.25mm from both ends in the longitudinal direction. The volume of the flat wire 15 to be buried corresponds to the volume of the pair of buried

portions

15b, 15b of the flat wire 15 buried in the head 10 radially outside the bristle-implanting hole 13.

In the toothbrush 1, since the volume of the flat wire 15 embedded in the implantation hole 13 is set to be small, the amount of resin pushed away by the flat wire 15 is small. Thus, warpage of the head 10 can be prevented.

In the case of a grooved flat wire having a plurality of grooves 16 on both

side surfaces

15a, 15a of the flat wire 15, resin enters these grooves 16, whereby the amount of resin pushed aside by the flat wire 15 can be suppressed, and warping of the head portion 10 can be further prevented. Further, the resin enters the grooves 16 of the flat wire 15, and the flat wire 15 is thereby less likely to fall out of the bristle-implanting hole 13. Therefore, in order to further obtain the above-described separation prevention effect, the grooved flat wire 15 is more preferable than the non-grooved flat wire.

As described above, the head 10 of the present embodiment is formed of a resin having a flexural modulus of elasticity of 1000MPa to 2800 MPa. That is, by using a general-purpose resin such as a polypropylene resin, the cost of the toothbrush 1 can be controlled.

Further, as described above, since the head portion 10 takes measures against warpage, even if the thinned head portion 10 is formed of a general-purpose resin, warpage or the like is less likely to occur.

As shown in fig. 2B, the back thickness N of the head 10 is set to 0.7mm or less in order to secure the depth M of the implanted holes 13, so that the head 10 is less likely to warp even if the flat wire 15 is pushed down to the bottom of the implanted holes 13, and sufficient implanted strength can be secured.

The value of the fill factor (B/A x 100%) is preferably 70 to 90%, more preferably 75 to 85%. When the distance from the hole bottom 13b of the bristle-implanted hole 13 to the bottom surface 15c of the flat wire 15 is set within the range of the above formula (1) with a filling factor within this range, the above-described excellent bristle-implanted strength can be obtained, and moreover, whitening of the resin or the like does not occur in the head 10, which is more preferable.

The pattern of the row of the hair-planting holes 13 is not limited to the above pattern, and may be a so-called lattice pattern, a staggered pattern, or the like. The density of implanted pores is 25 pores/cm²Above 40 holes/cm²Hereinafter, the pattern may be any arrangement pattern.

[ examples ]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and can be modified and implemented as appropriate within a range not departing from the gist thereof.

(materials used)

< example 1 to example 3, comparative example 1 to comparative example 2 >

The handle body 40: polypropylene resin

Bristles 11 a: double core sheath ST wool (core: PBT, sheath: PET)

(examples 1 to 3 and comparative examples 1 to 2)

The handle body 40 shown in fig. 1A and 1B is manufactured by injection molding, the bundle 11 of bristles 11A is folded into two, and the flat wire 15 is driven into the implantation hole 13. In this way, the hair bundle 11 is implanted into the implantation hole 13.

The toothbrush 1 was evaluated for the cleaning effect of the neck of the posterior teeth, the warpage of the head 10, the occurrence of whitening and cracking of the resin, and the implantation strength, which are intraoral operability.

(evaluation method of cleaning Effect of the cervical part of posterior teeth)

10 panelists cleaned the oral cavity with the toothbrushes of examples 1 to 3 and comparative examples 1 to 2, and evaluated the cleaning effect of the cervical region of the posterior teeth at that time according to the following evaluation criteria.

The cleaning feeling of the tooth neck portion was evaluated by 5 grades by the above-mentioned examiner. Specifically, "the cleaning feeling is highly felt" is denoted by 5 points, "the cleaning feeling is slightly felt" is denoted by 4 points, "the cleaning feeling is felt" is denoted by 3 points, "the cleaning feeling is less felt" is denoted by 2 points, "and the cleaning feeling is not felt" is denoted by 1 point.

The average of 10 panelists was rated very good at 4.0 or more, rated good at 3.0 or more and less than 4.0, rated delta at 2.0 or more and less than 3.0, and rated x at less than 2.0.

(method of evaluating warpage of head)

The implanted bristle tufts handle was photographed from the side by means of a microscope (Keyence, Inc.: VHX-100). The image of the evaluation toothbrush and the image of the non-implanted handle in which the tufts were not implanted were superimposed, and the deviation of the parting line (parting line) at the tip of the head was measured by a digital caliper, and the warpage of the head 10 was described as (n ═ 6). The warpage was evaluated according to the following 3-point evaluation.

Very good: less than 0.5mm

And (delta): 0.5mm or more and less than 0.7mm

X: 0.7mm or more

(evaluation method of occurrence of whitening and cracking of resin)

The occurrence of cracks and whitening in the toothbrush was evaluated by visual observation (n is 1000). Specifically, the occurrence rate of cracking and whitening was evaluated as "very good" when 0%, as "good" when less than 20%, and as "poor" when 20% or more.

(evaluation method of Hair-planting Strength)

The maximum tensile stress (N) (tensile rate 20mm/min) (N20) until the tufts are removed from the bristle-implanted holes was measured by an Autograph manufactured by shimadzu corporation, and the evaluation was performed based on the value. Specifically, the average value was evaluated as "o" when the value was 15N or more, as "Δ" when the value was 8N or more and less than 15N, and as "x" when the value was less than 8N.

As shown in fig. 4, it has been confirmed that: in examples 1 to 3 of the toothbrush 1, the thickness t of the head 10 was in the range of 2.0mm to 4.0mm, and the bristle hole density was 25 holes/cm²As described above, X is 0.9mm to 1.3mm, and satisfies formula (1), and therefore, favorable results were obtained in the respective evaluations of oral operability, warpage of head 10, whitening of the resin, occurrence of cracks, and hair-planting strength.

In examples 1 to 3 of the toothbrush 1, the embedded volume of the flat wire 15 in the implantation hole 13 was 0.06mm³Above, 0.20mm³The following.

In examples 1 to 3 of the toothbrush 1, the distance from the bottom 13b of the bristle-implanting hole 13 to the bottom surface 15c of the flat wire 15 was 0.5mm or less. At a thickness of 0.5mm or less, the flat wire 15 is driven deeply, so that the head 10 is less likely to warp.

On the other hand, it has been confirmed that: in comparative examples 1 to 2 of the toothbrush 1, satisfactory results were not obtained in any of the evaluation items of oral cavity operability, warpage of the head 10, whitening of the resin, occurrence of cracks, and hair-planting strength.

While preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It should be understood that: it is obvious that various modifications and alterations can be made by those skilled in the art within the scope of the technical idea described in the patent claims, and such modifications naturally fall within the technical scope of the present invention.

Claims

1. A toothbrush is provided with a head part having a plurality of implanting holes on a bristle implanting surface, and a bristle bundle having a plurality of bristles is folded into two by a flat wire and implanted in the implanting holes,

the thickness of the head part is more than 2.0mm and less than 3.5mm,

the thickness from the bottom of the hair planting hole to the back of the head, namely the back thickness, is less than 0.7mm,

the density of the hair planting holes is 25 holes/cm²In the above-mentioned manner,

when the inner diameter of the implanted pore is X, the thickness of the flat wire is d, and X is more than 0.9mm and less than 1.3mm, the following relation is satisfied:

0.37mm≤(X－d)/2≤0.55mm，

the embedded volume of the flat wire relative to the implantation hole is 0.06mm³Above, 0.13mm³The following.

2. The toothbrush of claim 1, wherein the flat wire has a height H of 1.0-1.5 mm.

3. The toothbrush of claim 1 or 2, wherein both sides of the flat wire have a plurality of grooves.

4. The toothbrush according to claim 1 or 2, wherein the head is formed of a resin having a flexural modulus of elasticity of 1000MPa or more and 2800MPa or less.

5. The toothbrush of claim 1, wherein the head is comprised of a polypropylene resin.