JP5830277B2 - toothbrush - Google Patents

Description

  The present invention relates to a toothbrush.

As a toothbrush, one having a hair bundle in which a plurality of bristles are bundled near the tip of a handle body is known. In general, the handle body includes a head portion in which a hair bundle is implanted, and a handle portion extended to the head portion via a neck portion, and has a long shape as a whole.
In consideration of operability in the oral cavity, the head portion is often formed as thin as possible. In addition, the neck portion is often shaped to have a diameter smaller than that of the head portion in consideration of operability in the oral cavity.

 In general, the handle body is made of hard resin such as polypropylene, but when cleaning the inside of the oral cavity, if the head part or neck part is strongly bitten and an excessive load is applied, the head part or neck part will break. Or part of it may be missing.

In order to increase the strength of the head portion or the neck portion, increasing the thickness of the head portion or the neck portion or increasing the diameter of the neck portion impairs operability in the oral cavity.
Or when a rib etc. are formed in a neck part and the intensity | strength of a neck part is raised, since a rib contacts in an oral cavity, a usability | use_condition will be impaired.

 For example, a toothbrush in which one surface of the head portion and the neck portion or the entire surface of the handle body is covered with a soft resin such as an elastomer resin has been proposed (for example, Patent Document 1).

Japanese Utility Model Publication No. 02-143035

However, if the head part and the neck part are simply covered with a soft resin as in the technique of Patent Document 1, the volume of the hard resin that becomes the core of the handle body is reduced and the strength is lowered.
When the volume of the hard resin is increased, the head portion and the neck portion are thickened, and the operability and usability are easily impaired.
In addition, even if only one surface of the head portion and the neck portion is covered with a soft resin, the head portion and the neck portion cannot be sufficiently prevented from being broken or broken.
In order to coat the handle body with a soft resin, the core of the handle body is molded with a hard resin (primary molding), put into a mold, and the soft resin is injected into the mold (secondary molding). For this reason, in the secondary molding, when the soft resin is injected, there is a problem that the posture of the core moves and it is difficult to cover the soft resin with a stable thickness. In particular, it is difficult to cover the entire surface of the handle body with a soft resin having a stable thickness.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a toothbrush that can prevent a head portion and a neck portion from being broken or broken and can be easily manufactured.

The toothbrush of the present invention includes a handle body including a head portion in which a plurality of hair bundles are implanted on the flocked surface, a neck portion extending to the head portion, and a handle portion extending to the neck portion. In the handle body, a toothbrush in which a coating layer made of a soft resin covering 70% or more of the total surface area of the head portion and the neck portion is formed on the surface of a base made of a hard resin. The coating layer is characterized in that at least one exposed portion where the base is exposed is formed, and no exposed portion is formed in a line-symmetric region with the axis of the neck portion as the axis of symmetry.
The hard resin is preferably polybutylene terephthalate.

  According to the toothbrush of the present invention, the head portion and the neck portion can be prevented from being broken or broken, and can be easily manufactured.

(A) It is a top view of the toothbrush concerning 1st embodiment of this invention. (B) It is a bottom view of the toothbrush concerning 1st embodiment of this invention. (C) It is CC sectional drawing of Fig.1 (a). (A) It is a top view of the toothbrush concerning 2nd embodiment of this invention. (B) It is a bottom view of the toothbrush concerning 2nd embodiment of this invention. (C) It is a side view of the toothbrush concerning 2nd embodiment of this invention. (D) It is D1-D1 sectional drawing of Fig.2 (a). (A) It is a top view of the toothbrush concerning 3rd embodiment of this invention. (B) It is a bottom view of the toothbrush concerning 3rd embodiment of this invention. (C) It is a side view of the toothbrush concerning 3rd embodiment of this invention. (D) It is D2-D2 sectional drawing of Fig.3 (a). (A) It is a top view of the toothbrush concerning 4th embodiment of this invention. (B) It is a bottom view of the toothbrush concerning 4th embodiment of this invention. (C) It is a side view of the toothbrush concerning 4th embodiment of this invention. (D) It is D3-D3 sectional drawing of Fig.4 (a). (A) It is a top view of the toothbrush used for the comparative example. (B) It is a bottom view of the toothbrush used for the comparative example. (C) It is a side view of the toothbrush used for the comparative example. (D) It is D4-D4 sectional drawing of Fig.5 (a). (A) It is a top view of the toothbrush used for the comparative example. (B) It is a bottom view of the toothbrush used for the comparative example. (C) It is a side view of the toothbrush used for the comparative example. (D) It is D5-D5 sectional drawing of Fig.6 (a). (A) It is a top view of the toothbrush used for the comparative example. (B) It is a bottom view of the toothbrush used for the comparative example. (C) It is a side view of the toothbrush used for the comparative example. (D) It is D6-D6 sectional drawing of Fig.7 (a).

(First embodiment)
The toothbrush concerning 1st embodiment of this invention is demonstrated using FIG. 1 below.
A toothbrush 1 shown in FIG. 1 includes a head body 2, a handle body 10 including a neck portion 4 extending to the head portion 2, and a handle portion 6 extending to the neck portion 4, and flocking of the head portion 2. A plurality of hair bundles 22 planted on the surface 20 are provided.

The plan view shape of the head portion 2 is a substantially rectangular shape having a direction extending from the head portion tip 21 toward the neck portion 4 as a longitudinal direction, and four corners thereof are cut off by curves. The neck portion 4 extends from the base end of the head portion to the handle portion 6 in a plan view, extends with a substantially equal width after being reduced in width, and then widens and is connected to the handle portion 6. The handle portion 6 extends from the handle portion base end with substantially the same thickness.
In the present embodiment, the base end of the head portion, that is, the boundary between the head portion 2 and the neck portion 4 is the end point of a curve that forms a corner cut in the plan view shape of the head portion 2 (that is, the bending direction of the curve forming the corner cut Is a position P1 (see FIG. 1A).
The base end of the handle portion in this embodiment, that is, the boundary between the neck portion 4 and the handle portion 6 is a position (neck end point) P2 at which the widening of the neck portion 4 ends in plan view (see FIG. 1A). ).

The width W1 of the head portion 2 can be determined in consideration of operability in the oral cavity, and is, for example, 8 to 12 mm.
The length L1 of the head portion 2 can be determined in consideration of the operability in the oral cavity, and is set to 15 to 30 mm, for example.
The thickness T1 of the head portion 2 can be determined in consideration of the operability in the oral cavity, the strength required for the handle body 10, and the like, for example, 3 to 5 mm.

The handle body 10 includes a base 11 and a coating layer 12 that covers the surface of the base 11, and the coating layer 12 is formed from the head portion tip 21 toward the tip of the handle portion 6 rather than the handle portion base end. ing. Three exposed portions 14 where the base 11 is exposed are formed on the covering layer 12, and the exposed portion 14 has a substantially perfect circle and is substantially flush with the outer surface of the covering layer 12.
In addition, the region where the base 11 is exposed is not formed in a region symmetrical to the arbitrary exposed portion 14 with the axis O1 of the neck portion 4 as the axis of symmetry. That is, in the present embodiment, the exposed portion 14 is formed only on the surface (bottom surface) opposite to the flocked surface 20 of the surface of the head portion 2.
The axis O1 is a line that connects the base end of the head part and the base end of the handle part and passes through the center of the neck part 4.

The base 11 is a member serving as a core of the handle body 10, and the head portion 2, the neck portion 4, and the portion that forms the handle portion 6 are integrally formed.
The material of the base 11 can be determined in consideration of the rigidity and mechanical characteristics required for the toothbrush 1, and examples thereof include a hard resin having a flexural modulus (JIS K7203) in the range of 500 to 3000 MPa. Examples of such a hard resin include polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), polyacetal (POM), polystyrene (PS), acrylonitrile. Examples thereof include butadiene / styrene resin (ABS), cellulose propionate (CP), polyarylate, polycarbonate, acrylonitrile / styrene copolymer resin (AS), and among them, PBT is preferable. Since the PBT has a high bending strength, the handle body 10 can be prevented from being broken or partially lost. These can be used individually by 1 type or in combination of 2 or more types.

The thickness T2 of the base 11 in the head unit 2 can be determined in consideration of the material of the base 11 and the like, and is set to 2 to 4 mm, for example.
The thickness of the base 11 in the neck portion 4 is the same as the thickness T2 of the base 11 in the head portion 11.

 The covering layer 12 covers 70% or more of the total surface area of the head part 2 and the surface area of the neck part 4 (covering ratio 70%), and preferably covers 70 to 95%, for example 80 to 90%. What covers% is more preferable. As the coverage by the coating layer 12 increases, the head portion and the neck portion can be more highly prevented from being broken or broken.

The material of the covering layer 12 may be a soft resin that can prevent the handle body from being damaged, and examples thereof include elastomer resins such as polyolefin elastomers, styrene elastomers, and polyester elastomers. From the viewpoint of more reliably preventing styrene elastomers. Examples of the styrene elastomer include Septon (trade name, manufactured by Kuraray Co., Ltd.), Rheostomer (trade name, manufactured by Riken Technos Co., Ltd.), and the like.
The material of the covering layer 12 is more preferably determined in consideration of the material of the base 11. For example, if the material of the base 11 is PBT, the material of the coating layer 12 is preferably a styrene elastomer or a polyester elastomer, and more preferably a polyester elastomer. Moreover, if the material of the base 11 is PP, a polyolefin-type elastomer and a styrene-type elastomer are preferable, and a polyolefin-type elastomer is more preferable. By making such a combination of the material of the base 11 and the material of the coating layer 12, the peeling of the coating layer 12 from the base 11 can be further reduced.

 The thickness T3 of the coating layer 12 can be determined in consideration of the material of the resin constituting the coating layer 12, and is preferably 0.5 to 2 mm, and more preferably 0.8 to 1.5 mm. If it is less than the above lower limit value, there is a possibility that damage to the handle body 10 may not be effectively prevented, and if it exceeds the above upper limit value, the thickness of the head portion 2 or the neck portion 4 becomes too thick, and the operation of the handle body 10 May be impaired.

The diameter R1 of the exposed portion 14 is not particularly limited and can be determined in consideration of the size of the head portion 2 and the like.
The exposure ratio represented by [total exposed area] / [covered area] can be determined in consideration of the coverage of the coating layer 12 and the like, preferably 0.05 to 0.3, 0.1 to 0 .2 is more preferred. If it is less than the above lower limit value, it may be difficult to fix the base in the secondary mold in the secondary molding described later, and if it exceeds the above upper limit value, the coating layer 12 may be easily peeled off. .
The covering area is the sum of the area of the covering layer 12 and the area of the exposed portion 14.

The hair bundle 22 is a bundle of a plurality of hairs.
The length (hair length) from the flocked surface 20 to the tip of the hair bundle 22 can be determined in consideration of the hair waist and the like required for the hair bundle 22, and is, for example, 6 to 13 mm.
All the hair bundles 22 may have the same hair length or may be different from each other.

 The thickness (hair bundle diameter) of the hair bundle 22 can be determined in consideration of the hair and the like required for the hair bundle 22 and is, for example, 1 to 2 mm. All the hair bundles 22 may have the same hair bundle diameter or may be different from each other.

 As the hair constituting the hair bundle 22, for example, the diameter gradually decreases toward the hair tip, the hair having a sharp hair tip (tapered hair), and the diameter from the flocked surface 20 toward the hair tip. Examples include hairs that are almost the same (straight hairs). Examples of the straight hair include those in which the hair tip is a plane substantially parallel to the flocked surface 20 and those in which the hair tip is rounded into a hemisphere.

The material of the hair is, for example, polyamide such as 6-12 nylon (6-12NY), 6-10 nylon (6-10NY), PET, PBT, polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), Examples thereof include polyesters such as polybutylene naphthalate (PBN), polyolefins such as PP, elastomer resins such as polyolefin elastomers and styrene elastomers.
These resin materials can be used singly or in combination of two or more.
Examples of the bristle include polyester bristle having a multi-core structure having a core and at least one or more sheaths provided outside the core.

  The cross-sectional shape of the hair is not particularly limited, and may be a circle such as a perfect circle or an ellipse, a polygon, a star, a three-leaf clover, a four-leaf clover, or the like. The cross-sectional shapes of all the hairs may be the same or different.

 The thickness of the hair can be determined in consideration of the material and the like. When the cross section is circular, the thickness is, for example, 6 to 9 mil. Further, in consideration of a feeling of use, a feeling of brushing, a cleaning effect, durability, and the like, a plurality of hairs having different thicknesses may be used in any combination.

 The manufacturing method of the toothbrush 1 is, for example, forming the base 11 (primary molding), forming the covering layer 12 on the obtained base 11 (secondary molding), and then forming the hair bundle 22 on the head portion 2. And a flocking step for flocking the hair.

  In the primary molding, a pair of primary molds that form a cavity corresponding to the shape of the base 11 is used, and a hard resin (sometimes referred to as a primary resin) constituting the base 11 is injected into the cavity. 11 is an operation of molding 11.

The subsequent secondary molding uses a pair of secondary molds in which cavities corresponding to the shape of the coating layer 12 are formed, and the base 11 obtained by the primary molding is loaded into the cavity of the secondary mold. This is an operation of injecting a soft resin (sometimes referred to as a secondary resin) constituting the coating layer 12 into the secondary mold to form the coating layer 12. The cavity of the secondary mold is such that when the base 11 is loaded in the cavity, the space formed between the loaded base 11 and the cavity has a shape corresponding to the coating layer 12. is there.
At the time of secondary molding, the base 11 is formed with a convex portion having a shape corresponding to the exposed portion 14, and this convex portion comes into contact with the inner surface of the secondary mold. For this reason, a gap having a shape corresponding to the coating layer 12 is stably formed inside the secondary mold. In addition, even when the secondary resin is injected, a gap having a shape corresponding to the coating layer 12 is secured, so that the coating layer 12 can be stably formed with a desired thickness.

  The flocking process is a process in which the hair bundle 22 is implanted in the head portion 2 to obtain the toothbrush 1. A known method can be used for the method of planting the hair bundle 22, for example, a hair bundle composed of a plurality of hairs is folded in half, and a retaining member (flat wire) is sandwiched therebetween, and the flat wire is planted. A flat wire flocking method in which the hair bundle is fixed by driving into the pores. A conventionally well-known thing can be used for this flat line, For example, the flat thing made from brass and aluminum is mentioned.

As described above, according to the toothbrush of the present embodiment, a coating layer made of a soft resin covering 70% or more of the total surface area of the head part and the surface area of the neck part is formed on the surface of the base made of hard resin. Since it is formed, the handle body is not easily broken even if an excessive load is applied to the head portion or the neck portion. Further, even when the handle body is folded at the head portion or the neck portion, it is possible to prevent the folded portion from being exposed, or to hold the missing member with the coating layer.
According to the toothbrush of this embodiment, since one or more exposed portions where the base is exposed are formed in the coating layer, the coating layer can be stably formed with a desired thickness.
According to the toothbrush of the present embodiment, since the exposed portion is not formed in a line-symmetric region with the axis of the neck portion as the axis of symmetry, when the head portion or the neck portion is bitten with teeth, the upper and lower teeth Any of the above does not directly contact the exposed portion. In addition, even when a load is applied to the head portion or the neck portion from any direction, the load can be reduced by the coating layer. For this reason, it is possible to prevent an excessive load from being applied to the head portion or the neck portion, and it is possible to prevent the head portion and the neck portion from being broken or broken.

(Second embodiment)
The toothbrush concerning 2nd embodiment of this invention is demonstrated using FIG. In addition, while attaching | subjecting the same code | symbol to the structure same as 1st embodiment, the description is abbreviate | omitted, and a different point from 1st embodiment is mainly demonstrated. In this embodiment, the difference from the first embodiment is the shape of the exposed portion and the position of the exposed portion.

The toothbrush 100 of the present embodiment includes a handle body 110 having a coating layer 112 formed on the surface of a base 111. On the bottom surface of the head portion 2, a substantially semicircular exposed portion 114 is formed near the head portion tip 21, and a substantially square exposed portion 116 is formed near the head portion base end. A substantially rectangular exposed portion 118 is formed on the bottom surface of the neck portion 4 so as to extend from the head portion base end to the handle portion base end in the direction of the axis O1.
As shown in FIG. 2D, the exposed portion 118 is substantially flush with the outer surface of the covering layer 112. The exposed portion 114 and the exposed portion 116 are also substantially flush with the outer surface of the coating layer 112, similar to the exposed portion 118.
In addition, a region where the base 111 is exposed is not formed in a region symmetrical to the exposed portions 114, 116, and 118 with the axis O1 as the axis of symmetry.

The length l1 of the exposed portion 114 can be determined in consideration of the length of the head portion 2 and the like, for example, 5 to 15 mm. The width w1 of the exposed portion 114 can be determined in consideration of the width of the head portion 2, and is, for example, 3 to 8 mm.
The length l2 of the exposed portion 116 can be determined in consideration of the length of the head portion 2 and the like, and is, for example, 3 to 5 mm. The width of the exposed portion 116 is the same as the width w1 of the exposed portion 114.
The width w2 of the exposed portion 118 can be determined in consideration of the width of the neck portion 4 and the like, and is, for example, 1 to 4 mm.

 According to this embodiment, since the exposed part is formed in the head part and the neck part, the base can be more stably fixed in the secondary mold.

(Third embodiment)
The toothbrush concerning 3rd embodiment of this invention is demonstrated using FIG. In addition, while attaching | subjecting the same code | symbol to the structure same as 1st embodiment, the description is abbreviate | omitted, and a different point from 1st embodiment is mainly demonstrated. In this embodiment, the difference from the first embodiment is the shape of the exposed portion and the position of the exposed portion.

The toothbrush 200 of the present embodiment includes a handle body 210 in which a coating layer 212 is formed on the surface of a base 211. The covering layer 212 is formed with a substantially rectangular exposed portion 214 extending from the head portion 2 to the neck portion 4 in the direction of the axis O1 on the bottom surface.
As shown in FIG. 3D, the exposed portion 214 is substantially flush with the outer surface of the covering layer 212.
In addition, the region where the base 211 is exposed is not formed in a region symmetrical to the exposed portion 214 with the axis O1 as the axis of symmetry.

  The width w3 of the exposed portion 214 can be determined in consideration of the width of the neck portion 4 and the like, and is, for example, 1 to 4 mm.

 According to this embodiment, since it is not necessary to form an exposed portion with a complicated shape, the base can be stably fixed in the secondary mold more easily.

(Fourth embodiment)
A toothbrush according to a fourth embodiment of the present invention will be described with reference to FIG. In addition, while attaching | subjecting the same code | symbol to the structure same as 1st embodiment, the description is abbreviate | omitted, and a different point from 1st embodiment is mainly demonstrated. This embodiment is different from the first embodiment in that a substantially rectangular exposed portion is formed on the bottom surface of the neck portion.

The toothbrush 300 of the present embodiment includes a handle body 310 having a coating layer 312 formed on the surface of a base 311. In the covering layer 312, three exposed portions 14 are formed on the bottom surface of the head portion 2, and one substantially rectangular exposed portion 316 whose longitudinal direction is the axis O 1 direction is formed on the bottom surface of the neck portion 4.
As shown in FIG. 4D, the exposed portion 316 is substantially flush with the outer surface of the covering layer 312.
In addition, a region where the base 311 is exposed is not formed in a region symmetrical to the exposed portion 316 with the axis O1 as the axis of symmetry.

  The length l3 of the exposed portion 316 can be determined in consideration of the length of the head portion 2 and the like, and is set to 1 to 5 mm, for example. The width w4 of the exposed portion 316 can be determined in consideration of the width of the neck portion 4 and the like, and is, for example, 1 to 4 mm.

 According to this embodiment, since the exposed part is formed in both the head part and the neck part, the base can be more stably fixed in the secondary mold.

(Other embodiments)
The present invention is not limited to the embodiment described above.
In the first to fourth embodiments, the exposed portion is substantially flush with the outer surface of the coating layer. However, the present invention is not limited to this, and the exposed portion protrudes from the outer surface of the coating layer. Alternatively, the exposed portion may be recessed from the outer surface of the coating layer.

 In the first to fourth embodiments, the exposed portion is formed only on the bottom surface, but the present invention is not limited to this, and the exposed portion is formed on the surface (upper surface) or the side surface facing in the same direction as the flocked surface. May be. Alternatively, the exposed portion may be formed on any two or more of the bottom surface, the top surface, and the side surface. When the exposed portion is formed on any two or more of the bottom surface, the top surface, and the side surface, the base can be more stably fixed in the secondary mold.

In the first and fourth embodiments, the substantially true circular exposed portion is formed in the head portion, but the present invention is not limited to this, and the shape of the exposed portion is elliptical, substantially polygonal, or the like. It may be. A substantially polygon is a concept including a shape in which corners are cut off by straight lines or curves.
In addition, in order to suppress peeling of a coating layer, it is preferable that the shape of the exposed part is a circle such as a perfect circle or an ellipse, or a polygon that is rounded by a curve.

 In the second to fourth embodiments, the shape of the exposed portion formed in the neck portion is substantially rectangular, but the present invention is not limited to this, and the shape of the exposed portion formed in the neck portion is circular. It may be.

 In 1st-4th embodiment, the coating layer is formed in the area | region containing a handle | steering-wheel base end from a head part front-end | tip. However, the coating layer only needs to cover 70% or more of the total surface area of the head portion and the surface area of the neck portion. For example, the coating layer is formed from the front end of the head portion to the front end of the handle portion. Alternatively, a coating layer may be formed up to the tip of the handle portion.

 In the present invention, the hair-planting pattern of the hair bundle is not particularly limited, and may be any of a so-called lattice shape, zigzag shape, or a combination thereof.

  EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated in detail, this invention is not limited by the following description.

Example 1
A base is manufactured using the base material shown in Table 1 as a primary resin, and then a coating layer is formed on the base using the coating layer material shown in Table 1 as a secondary resin, similar to the toothbrush 100 of FIG. Toothbrushes were manufactured. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.
In the materials of the coating layer in the table, “polyester” indicates a polyester elastomer, “polyolefin” indicates a polyolefin elastomer, and “styrene” indicates a styrene elastomer.

<Specifications>
Head width: 8.5mm
Head length: 22mm
Head thickness: 4.5mm
Neck width: 5mm
Neck length: 50mm
Exposed portion 114 length l1: 5 mm
Exposed portion 114 width w1: 4 mm
Length of exposed part 116: 3 mm
Exposed portion 118 width w2: 2 mm
Covering layer thickness: 0.8mm

(Example 2)
A toothbrush similar to the toothbrush 200 of FIG. 3 was manufactured in the same manner as in Example 1 except that the base material and the coating layer material were as shown in Table 1 and the exposed portion was the following specification. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.

<Specifications>
Exposed portion 214 width w3: 2 mm

(Example 3)
A toothbrush similar to the toothbrush 300 of FIG. 4 was produced in the same manner as in Example 1 except that the base material and the coating layer material were as shown in Table 1 and the exposed portion was the following specification. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.

<Specifications>
Diameter of exposed part 14: 3 mm
Exposed portion 316 length l3: 3 mm
Exposed portion 316 width w4: 2 mm

(Comparative Example 1)
A toothbrush similar to the toothbrush 700 of FIG. 5 was produced in the same manner as in Example 1 except that the base material and the coating layer material were those shown in Table 1. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.
The toothbrush 700 includes a handle body 710 in which the entire base 711 is covered with a coating layer 712. In the handle body 710, 100% of the total surface area of the head portion 2 and the neck portion 4 is covered with the coating layer 712, and no exposed portion is formed.

(Comparative Example 2)
A toothbrush similar to the toothbrush 800 of FIG. 6 was manufactured in the same manner as in Example 1 except that the base material was as shown in Table 1 and secondary molding was not performed. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.
In addition, the toothbrush 800 does not have a coating layer formed on the handle body 810, and is constituted only by a base.

(Comparative Example 3)
A toothbrush similar to the toothbrush 900 of FIG. 7 was manufactured in the same manner as in Example 1 except that the base material and the coating layer material were as shown in Table 1 and the exposed part was the following specification. About the obtained toothbrush, head part intensity | strength, neck part intensity | strength, the presence or absence of isolation | separation, and a moldability were evaluated, and the result is shown in Table 1.
The toothbrush 900 includes a handle body 910 having a coating layer 912 formed on the surface of a base 911. In the covering layer 912, a substantially rectangular exposed portion 914 is formed on the upper surface of the neck portion 4, and a substantially rectangular exposed portion 916 is formed on the bottom surface of the neck portion 4. As shown in FIG. 7D, the exposed portion 914 and the exposed portion 916 are formed in a line-symmetric region with the axis O1 as the axis of symmetry.

<Specifications>
Exposed portion 914 width w5: 2 mm
Exposed portion 916 width w6: 2 mm

(Evaluation method)
<Head strength>
A sample was prepared by cutting the bristles of the toothbrushes of each example and smoothing the flocked surface of the head part. The head end of the sample is held with a clamp, the sample is fixed to a digital impact tester (DG-1 type, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the flocked surface is weighted with 0.5 J, and the head is The absorbed energy (J) when fractured was measured (n = 10). The average value of the measured values was classified into the following evaluation criteria, and the head portion strength was evaluated.
≪Evaluation criteria≫
◎: 0.3J or more ○: 0.2J or more and less than 0.3J △: 0.1J or more and less than 0.2J ×: Less than 0.1J

<Neck strength>
The handle part base end of each example sample was clamped and fixed, weighted with 2 kg from the flocked surface side, and the breaking strength (N) when the neck part broke was measured (n = 10). The average value of the measured values was classified into the following evaluation criteria, and the head portion strength was evaluated.
≪Evaluation criteria≫
◎: 100N or more ○: 70N or more and less than 100N △: 40N or more and less than 70N ×: Less than 40N

<Presence / absence of separation>
The handle body after the head portion strength and the neck portion strength were measured was visually observed to evaluate the presence or absence of separation of the handle body.
○: Not separated.
X: Separated.

<Moldability>
The toothbrush of each example was confirmed visually, and the degree of soft resin filling failure (short shot) was evaluated according to the following evaluation criteria. The moldability was evaluated for 10 pieces in each example, and the average score was 4.0 points or more “◎”, 3.0 points or more and less than 4.0 points “◯”, 2.0 points or more and less than 3.0 points “△”, and less than 2.0 points “x”.
≪Evaluation criteria≫
5: The thickness of the coating layer is uniform, and no deformation or chipping of the coating layer is observed.
4: Deformation or chipping of the coating layer is not recognized, but an area that does not reach the predetermined thickness is recognized in an area of less than 10% of the coating layer.
3: Deformation or chipping of the coating layer is not recognized, but a region not reaching the predetermined thickness is recognized in a region of 10% or more and less than 50%.
2: Deformation or chipping of the coating layer is not recognized, but a region not reaching the predetermined thickness is recognized in a region of 50% or more.
1: Deformation and chipping are observed in the coating layer.

<Comprehensive evaluation>
Based on the evaluation results of head portion strength, neck portion strength, presence / absence of separation, and moldability, comprehensive evaluation was performed according to the following evaluation criteria.
≪Evaluation criteria≫
◎: All evaluation results are “◯” or “◎”, and two or more “◎”.
○: All evaluation results are “◯” or “◎”, and “◎” is 1 or less.
Δ: All evaluation results are “Δ”, “○” or “◎”, and one or more “Δ”.
X: One or more evaluation results are “x”.

As shown in Table 1, in each of Examples 1 to 3 to which the present invention was applied, the overall evaluation was “◯” or “い ず れ”. Moreover, as for Examples 1-3, operability and usability in the oral cavity were all good.
On the other hand, in Comparative Example 1 in which the exposed portion was not formed, the moldability was “x”, and in Comparative Example 2 in which the coating layer was not formed, separation of the handle body was observed. In Comparative Example 3 in which the axis of the neck portion was the axis of symmetry and the exposed portion was formed in a line-symmetric region, the neck portion strength was “Δ”.
From the above results, it was found that by applying the present invention, it is possible to obtain a toothbrush that can prevent the head portion and the neck portion from being broken or broken and can be easily manufactured.

1, 100, 200, 300 Toothbrush 2 Head part 4 Neck part 6 Handle part 10, 110, 210, 310 Handle body 11, 111, 211, 311 Base 12, 112, 212, 312 Coating layer 14, 114, 116, 118, 214, 316 Exposed part 20 Flocked surface 22 Hair bundle O1 Axis

Claims (2)

A handle body comprising a head portion in which a plurality of hair bundles are implanted on the hair-implanted surface, a neck portion extending to the head portion, and a handle portion extending to the neck portion, In the toothbrush in which a coating layer made of a soft resin covering 70% or more of the total surface area of the head part and the surface area of the neck part is formed on the surface of the base made of hard resin,
The covering layer is formed with one or more exposed portions where the base is exposed, and no exposed portion is formed in a line-symmetric region with the axis of the neck portion as the axis of symmetry ,
The exposed portion is not formed on the flocked surface, the exposed portion is formed on the surface of the head portion opposite to the flocked surface, and the covering is formed on the surface opposite to the flocked surface. The toothbrush characterized by the outer surface of a layer, and the said exposed part being substantially flush . The toothbrush according to claim 1, wherein the exposed portion is a polygonal shape that is circular or rounded with a curved line in bottom view .

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