JP7229017B2 - Interdental brush and method for manufacturing interdental brush - Google Patents

Description

The present invention relates to a non-wire interdental brush and a method for manufacturing the interdental brush.

Conventionally, an interdental brush is mainly used as an auxiliary cleaning tool for cleaning gaps between teeth that are difficult to clean with a toothbrush. It has a brush portion that is sandwiched, and is composed of a base portion of a metal wire that is fixed to the tip side of a resin handle portion.

In recent years, the increasing number of implant wearers is considered to be the background behind the annual increase in the production and import of dental implants. Daily maintenance is important for artificial teeth such as implants and prostheses, but there is a concern that the metal parts of wire-type interdental brushes may damage the implants. Therefore, wire-free interdental brushes (Patent Documents 1 to 3) that are gentle on the teeth and gums are widely known. do not have.

JP 2013-192866 A International Publication No. 2016-076373 WO2013-176297

The head portion has a shaft core made of hard resin and a brush portion made of soft resin that partially covers the shaft core, and a large number of cleaning portions are formed in the brush portion.
In the case of a cleaning tool such as an interdental brush, which is used by inserting the brush part into narrow gaps between teeth, considering usability, the length of the brush part is required to some extent, and the shaft core must be thin. be. However, if the elongated shaft core is made of a hard resin and a covering soft resin, the flexibility of the brush portion is too high, making it difficult to insert between the teeth, which is inconvenient. Therefore, existing non-wire interdental brushes are made by adding talc, filler, etc. to hard resin to give strength to the elongated shaft core.

However, there is a concern that the addition of talc, filler, or the like lowers the strength of the core and makes it brittle. Furthermore, in a normal non-wired interdental brush, a part of the shaft core constituting the head portion is exposed without being covered with the soft resin, and the end interface of the soft resin is also exposed. . As a result, stress is applied to this portion during use, and repeated use may cause the shaft to break, the portion of the head portion that borders the handle portion to break, or the soft resin that makes up the brush portion to peel off from the shaft core. There were risks, too.

Therefore, in the case of a non-wire interdental brush, it is necessary to ensure the durability of the shaft made of hard resin and to suppress the risk of peeling of the brush portion made of soft resin.

One aspect of the present invention has been made in view of the above-described problems of the prior art, and is excellent in durability, does not break or bend even after repeated use, and does not decrease insertability between teeth. An object of the present invention is to provide an interdental brush and a method for manufacturing the interdental brush.

An interdental brush according to one aspect of the present invention includes a head portion having a length in the axial direction and having a brush portion around the axis, and a handle portion connected to one end side of the head portion in the axial direction. the head portion includes a hard resin member having a first portion and a second portion arranged in the axial direction; and a soft resin member covering the first portion of the hard resin member around the axis; an insert portion composed of the second portion of the resin member and an edge portion of at least a part of the soft resin member on the side of the second portion; A head holding portion that covers the entire insert portion from the outside in the radial direction is provided, and the structure of the connecting portion between the head portion and the handle portion is composed of the hard resin member in the insert portion of the head portion, and the It has a three-layer structure composed of a soft resin member and the head holding portion in the handle portion.

In one aspect of the present invention, in the interdental brush, the ratio of the half size of the thickness of the second portion of the hard resin member to the thickness of the soft resin member in the lateral direction is in the range of 2 to 5. It may be configured to be inside.

In one aspect of the present invention, the interdental brush may be configured such that the ratio of the radial thickness of the head holding portion to the radial thickness of the soft resin member is in the range of 2 to 5.

In one aspect of the present invention, in the interdental brush, the diameter of the insert portion is in the range of 0.4 mm to 2.0 mm, and the diameter of the second portion of the insert portion is in the range of 0.3 mm to 2.0 mm. The radial thickness of the soft resin member is within the range of 1.4 mm, the radial thickness of the soft resin member is within the range of 0.05 mm to 0.3 mm, and the radial thickness of the holding portion is 0.3 mm or more. It is good also as a structure with.

In one aspect of the present invention, the interdental brush may be configured such that the ratio of the length of the insert portion in the axial direction to the length of the head portion is within the range of 0.1 to 0.35.

In one aspect of the present invention, in the interdental brush, the length of the insert portion in the axial direction is 2.0 mm to 5.0 mm, and the soft resin member of the insert portion has a length of 0.5 mm. As described above, the length of the second portion may be 0.5 mm or more.

The interdental brush according to one aspect of the present invention may have a structure in which the head portion and the handle portion are integrally formed by insert molding.

A method for manufacturing an interdental brush according to one aspect of the present invention includes the steps of forming a head portion by covering at least a portion of a hard resin member having a length in an axial direction with a soft resin member; a step of insert-molding a handle portion on one end side, wherein in the insert-molding step, the insert portion provided on the one axial end side of the head portion is inserted into a cavity of a mold and closed. By pouring a resin into the cavity of the mold, the handle portion having the holding portion that covers the entire insert portion from the outside in the radial direction is molded, so that the connecting portion between the head portion and the handle portion is formed. , the hard resin member in the insert portion of the head portion, the soft resin member, and the holding portion in the handle portion.

ADVANTAGE OF THE INVENTION According to this invention, the interdental brush which is excellent in durability and can obtain sufficient cleaning effect even after repeated use can be provided.

FIG. 1 is a perspective view showing the configuration of an interdental brush in one embodiment. FIG. 2 is a perspective view showing the configuration of the head section in one embodiment. Fig. 3(a) is a side view of the head part in one embodiment, Fig. 3(b) is a plan view of the head part in one embodiment when viewed from the tip side, Fig. 3(c) [Fig. 2] is a plan view seen from the rear end side of the head part in one embodiment. FIG. 4 is a cross-sectional view showing the configuration of the head section in one embodiment. FIG. 5 is a cross-sectional view showing the configuration of the connecting portion between the head portion and the handle portion in one embodiment. FIG. 6 is a cross-sectional view along line A-A' in FIG.

[One embodiment]
An interdental brush according to one embodiment of the present invention will be described below.
In addition, in each drawing below, in order to make each component easy to see, the scale of the dimensions may be changed depending on the component.

FIG. 1 is a perspective view showing the configuration of an interdental brush 100 according to one embodiment. FIG. 2 is a perspective view showing the configuration of the head section 12 in one embodiment. FIG. 3(a) is a side view of the head portion 12 in one embodiment. FIG.3(b) is a top view when the head part 12 in one Embodiment is seen from the front end side. FIG.3(c) is the top view seen from the rear-end side of the head part 12 in one Embodiment. FIG. 4 is a cross-sectional view showing the configuration of the head section 12 in one embodiment. FIG. 5 is a cross-sectional view showing the configuration of the connecting portion between the head portion 12 and the handle portion 13 in one embodiment. FIG. 6 is a cross-sectional view along line A-A' in FIG.

As shown in FIG. 1, the interdental brush 100 of this embodiment includes a head portion 12 having a brush portion 11 for cleaning the gaps between teeth, and a handle portion 13 that serves as a handle during use. configured as follows. The brush portion 11 of the head portion 12 is a portion to be inserted into the gap between the teeth, extends in the axial direction for a predetermined length, and the brush portion 11 is formed around the axis. One axial end side of the head portion 12 is connected substantially perpendicularly to the handle portion 13, and the interdental brush 100 has a substantially L shape as a whole. The interdental brush 100 of this embodiment is manufactured using insert molding, and the head portion 12 and the handle portion 13 are welded together to form an integral structure.

(head part)
As shown in FIGS. 2 and 3A, the head portion 12 includes a primary-side hard resin member 14 and a secondary-side soft resin member 15 covering at least a portion of the hard resin member 14. configured as follows. The hard resin member 14 has a cylindrical shape as a whole and has a tapered shape that is slightly tapered toward the distal end side.

Examples of the hard resin member 14 include polypropylene resin. In this embodiment, talc, filler, etc. are not mixed.

Examples of the material of the soft resin member 15 include elastomer resin. Materials for the hard resin member 14 and the soft resin member 15 are not limited to those described above.

As shown in FIG. 4, the hard resin member 14 has a first portion R1 and a second portion R2 which are arranged axially in order from the tip 12a side of the head portion 12. As shown in FIG. The soft resin member 15 is formed integrally with the hard resin member 14 while covering the first portion R1 of the hard resin member 14 around the entire axis. That is, in this embodiment, the first portion R1 of the hard resin member 14 is covered with the soft resin member 15, whereas the second portion R2 is not provided with the soft resin member 15. As shown in FIG.

The head portion 12 has a brush portion 11 that is inserted between teeth. The brush portion 11 is a portion constituted by the soft resin member 15 covered with the first portion R1 of the hard resin member 14, and is formed with a large number of flexible cleaning portions 11A. Specifically, there are four cleaning part rows G1 and G2 each having an equal number of cleaning parts 11A arranged in a row at equal intervals in the axial direction, and each cleaning part row G1 and G2 has a head portion. The brush portions 11 are arranged alternately around the axis O of 12. As shown in FIG.

As shown in FIG. 3A, the cleaning section rows G1 and G2 are arranged with their positions shifted in the axial direction so that the cleaning sections 11A and 11B are not adjacent to each other around the axis. As a result, dental plaque or the like can enter and be scraped out of the gap 18 surrounded by the pair of cleaning portions 11A, 11A and 11B, 11B adjacent in the axial direction and around the axis.

The diameter of the head portion 12 can be appropriately changed in order to insert the brush portion 11 between narrow teeth. For example, it may be configured to be within the range of 0.3 to 1.5 mm. Moreover, in order to avoid damaging the gums, the tip 12a of the head portion 12 is preferably formed into a hemispherical shape by the soft resin member 15. As shown in FIG. As a result, even if the tip 12a of the head portion 12 hits the gums during interdental insertion, there is no pain and the gums are less likely to be damaged.

The proximal end 12 b side of the head portion 12 is an insert portion 16 connected to the handle portion 13 . The insert portion 16 is a portion to be inserted into the handle portion 13 shown in FIG. and an edge portion 15b on the R2 side. In this embodiment, with the head portion 12 attached to the handle portion 13 as shown in FIG. and the second portion R2 exposed from the soft resin member 15 are covered with the handle portion 13. As shown in FIG.

As shown in FIGS. 3(a) and 3(c), the insert portion 16 is provided with a plurality of groove portions 17 for enhancing the weldability with the handle portion 13 during insert molding. The groove portion 17 is provided at the base end portion 14b exposed from the soft resin member 15 of the hard resin member 14 constituting the insert portion 16, and extends axially from the end surface 12c of the head portion 12 toward the tip end 12a. extending along.

As shown in FIG. 3C, at least two grooves 17 are formed around the axis of the hard resin member 14, and four grooves 17 are formed in this embodiment. These four grooves 17 are arranged at equal intervals around the axis of the hard resin member 14 , and one longitudinal end side of each groove 17 opens to the end surface 14 c of the hard resin member 14 . As shown in FIG. 3C, the cross-sectional shape of the groove 17 perpendicular to the axial direction is substantially semicircular, but is not limited to this, and may be, for example, triangular, square or rectangular.

The number of grooves 17 is preferably two or more and eight or less, and a symmetrical arrangement with respect to the axis O is preferable. By providing a plurality of grooves 17 , the hard resin for forming the handle portion 13 enters each groove portion 17 during insert molding, and the head portion 12 is less likely to come off from the handle portion 13 . Moreover, if the arrangement of the plurality of grooves 17 is not symmetrical, the flow of the hard resin during insert molding may become anisotropic, and the position of the head portion 12 may be bent in the mold. Therefore, it is preferable that the arrangement of the grooves 17 be symmetrical when viewed in the axial direction.

The number of grooves 17, the length in the axial direction, the width dimension, the depth, the shape in cross section, the shape in plan view, etc. can be changed as appropriate.

The shape of the insert portion 16 of the head portion 12 is not limited to a cylindrical shape, and may be, for example, a triangular prism or a square prism. However, if the rear end portion of the insert portion 16 has a barb or protrusion, the flow of resin during insert molding becomes anisotropic, and the position of the head portion 12 may be bent in the mold. Therefore, it is preferable to use a columnar shape as in the present embodiment. The cylindrical shape makes it easier for the resin to flow around the insert portion 16 during insert molding, so that the head portion 12 does not bend in the mold, and an improvement in yield can be expected.

(Handle part)
As shown in FIG. 1, the handle portion 13 includes a grip portion 13A having a length in one direction, an extension portion 13B extending from one end side of the grip portion 13A, and a grip portion 13A of the extension portion 13B. It has a head holding portion 13C extending in a substantially vertical direction from the opposite end, and a curved portion 13D formed at the connecting portion between the head holding portion 13C and the grip portion 13A.

The grip portion 13A is a portion that has a cylindrical shape and extends in one direction for a predetermined length. Since the grip portion 13A is a portion to be gripped by the user, it has a length about the width of the user's hand and is formed with a diameter that is easy to grip. In this embodiment, the cylindrical shape is used, but the shape is not limited to this, and can be changed as appropriate.

A gripping portion 13A of the handle portion 13 is provided with an uneven non-slip portion 13E in a predetermined region including at least the central portion in the extending direction. The non-slip portion 13E is formed around the entire axis of the grip portion 13A. It should be noted that the formation range and uneven shape of the non-slip portion 13E can be changed as appropriate.

The extending portion 13B extends in a slightly inclined state in a direction intersecting the extending direction of the grip portion 13A, and is formed gradually narrower from the grip portion 13A side to the head holding portion 13C. The cross-sectional shape of the extending portion 13B is not particularly limited.

The head holding portion 13C is a portion that extends from the tip end side of the extension portion 13B substantially perpendicularly to the extension portion 13B, and the head portion 12 is inserted into the insertion hole portion 13a formed inside the tip end. A portion 16 is inserted and held. The head holding portion 13C has a tapered portion 13c1 tapered from the proximal end of the extending portion 13B toward the distal end, and an annular cylindrical portion 13c2 formed at the distal end thereof. The insertion hole portion 13a described above penetrates the cylindrical portion 13c2 and is formed over a portion of the tapered portion 13c1.

Here, when the head holding portion 13C side of the extension portion 13B of the interdental brush 100 is defined as the front surface 100a, and the side opposite to the head holding portion 13C is defined as the rear surface 100b, the extension portion 13B of the handle portion 13 described above is assumed to be the front surface 100a. Since the head holding portion 13C side is inclined toward the rear surface 100b side more than the grip portion 13A side, a curved portion 13D is formed between the extending portion 13B and the grip portion 13A. Since the curved portion 13D is provided in the middle of the handle portion 13, the head portion 12 can be easily inserted into the gap between the teeth, and the operability of the head portion 12 side is improved when the interdental brush 100 is inserted into the oral cavity. can be enhanced.

As shown in FIGS. 5 and 6, in the interdental brush 100 of the present embodiment, the structure of the joint portion 19 between the head portion 12 and the handle portion 13 is composed of a hard resin member 14, a soft resin member 15, and a hard resin member 15 in order from the inside. It has a three-layer structure including the head holding portion 13C of the handle portion 13. As shown in FIG.

Next, the three-layer structure of the joint portion 19 of the interdental brush 100 will be described in detail.
As shown in FIGS. 5 and 6, the radius r14 of the second portion R2 of the hard resin member 14 constituting the head portion 12 of the joint portion 19 has a ratio to the radial thickness T15 of the soft resin member 15. It is preferably in the range of 2 to 5, more preferably in the range of 2.5 to 3.5.

When the ratio of the radius r14 of the second portion R2 to the radial thickness T15 of the soft resin member 15 is 2 or less, that is, when the diameter of the second portion R2 becomes too small, the surface area of the insert portion 16 becomes small. As a result, the welding force in the insert molding becomes weak, and there is a possibility that the head portion 12 may come off from the head holding portion 13C of the handle portion 13 . Moreover, the strength of the hard resin member 14, that is, the strength of the shaft core of the brush portion 11 is lowered, and the durability is also lowered.

Further, if the thickness of the soft resin member 15 is too thick with respect to the thickness of the second portion R2, the insert portion 16 of the joint portion 19 is fitted with too much cushioning property, and the brush portion 11 is damaged during use. It is easy to bend from the root, making it difficult to insert between teeth. In addition, since the strength of the core cannot be maintained, it becomes difficult to insert the brush portion 11 between the teeth.

On the other hand, when the ratio of the radius r14 of the second portion R2 to the radial thickness T15 of the soft resin member 15 is 5 or more, that is, when the shaft core becomes too thick, the joint portion 19 is fitted with a cushioning property. is not obtained, stress is concentrated at the boundary between the brush portion 11 and the joint portion 19, and the durability of the shaft core is lowered. In other words, the shaft core of the brush part 11 is likely to break at the base of the boundary with the handle part 13 when it is inserted between the teeth.

Further, if the thickness of the soft resin member 15 is too small with respect to the thickness of the shaft core, the cushioning property of the soft resin member 15 cannot be obtained. Effects such as resistance to damage are reduced. Moreover, durability will also fall.

Therefore, by setting the ratio of the radius r14 of the second portion R2 to the radial thickness T15 of the soft resin member 15 within the above range, the durability of the shaft core of the brush portion 11 is improved and the soft resin member 15 can be secured, and the insertability between the teeth of the head portion 12 can be improved without damaging the gums or the like.

Further, the ratio of the radial thickness T13 of the head holding portion 13C to the radial thickness T15 of the soft resin member 15 is preferably in the range of 2 to 5, more preferably in the range of 2.5 to 3.5. Inside is more preferred.

When the ratio of the radial thickness T13 of the head holding portion 13C to the radial thickness T15 of the soft resin member 15 is 2 or less, that is, when the thickness of the head holding portion 13C becomes too small, the head portion 12 is The holding strength is weakened, and the adhesive strength in insert molding is also lowered. Therefore, the head portion 12 cannot be held firmly, and the head portion 12 may come off from the head holding portion 13C of the handle portion 13 . On the other hand, if the radial thickness T15 of the soft resin member 15 is too thick, the cushioning property is too great, and the brush portion 11 tends to bend from the root during use, making it difficult to insert between the teeth.

On the other hand, when the ratio of the radial thickness T13 of the head holding portion 13C to the radial thickness T15 of the soft resin member 15 is 5 or more, that is, the radial thickness T13 of the head holding portion 13C If the thickness T15 of the soft resin member 15 is too small, cushioning properties cannot be obtained when the joint portion 19 is fitted, stress is concentrated at the boundary between the brush portion 11 and the joint portion 19, and durability is reduced. .

Therefore, by setting the ratio of the radial thickness T13 of the head holding portion 13C to the radial thickness T15 of the soft resin member 15 within the above range, the holding strength of the head portion 12 in the head holding portion 13C is ensured. can be used to increase durability.

In the present embodiment, the maximum radius r14 of the second portion R2 of the hard resin member 14 is within the range of 2 to 5, and the ratio to the radial thickness T15 of the soft resin member 15 is 2.5 to 3.5. 5 is more preferred. Specifically, the maximum diameter D1 of the hard resin member 14 is preferably within the range of 0.3 mm to 1.4 mm, more preferably within the range of 0.7 mm to 1.2 mm. In this embodiment, the diameter of the second portion R2 of the hard resin member 14 is 0.89 mm.

A thickness T15 of the soft resin member 15 in the radial direction is preferably in the range of 0.05 mm to 0.3 mm, more preferably 0.1 mm to 0.2 mm. The thickness T15 of the soft resin member in this embodiment is 0.15 mm.

The ratio of the radial thickness T13 of the head holding portion 13C to the radial thickness T15 of the soft resin member 15 is preferably within a range of 2 to 5, more preferably 2.5 to 3.5. Specifically, the radial thickness T13 of the head holding portion 13C is preferably in the range of 0.3 mm to 1.5 mm, more preferably in the range of 0.4 mm to 1.0 mm. In this embodiment, the thickness T13 of the head holding portion 13C is 0.40 mm.

The maximum diameter of the insert portion 16 of the head portion 12, that is, the diameter D2 including the hard resin member 14 and the soft resin member 15 is preferably within the range of 0.4 mm to 2.0 mm. By setting it within the above range, when the diameter of the brush portion 11 is tapered toward the tip of the head portion 12, it is possible to further improve the resistance, durability, and interdental insertability of the head portion 12. can.

As shown in FIG. 4, the ratio of the axial length L16 of the insert portion 16 to the total length L12 of the head portion 12 is preferably in the range of 0.1 to 0.35, more preferably 0.15 to 0.15. 3.

If the ratio of the axial length L16 of the insert portion 16 to the total length L12 of the head portion 12 is less than 0.1, that is, if the length of the insert portion 16 inserted into the handle portion 13 is too short, When stress is applied, it is difficult to be held by the head holding portion 13C and is likely to come off. In addition, if the length of the brush part 11 is too long, it becomes difficult to insert the brush part 11 between the teeth, resulting in a decrease in usability.

On the other hand, when the ratio of the axial length L16 of the insert portion 16 to the total length L12 of the head portion 12 is greater than 0.35, the length of the brush portion 11 is shortened and the length of the insert portion 16 is increased. Although it becomes difficult to pull out from the handle portion 13, the soft resin member 15 cannot sufficiently provide cushioning properties when stress is applied to the shaft core, and the effect of providing the soft resin member 15 is lost.

Therefore, by setting the ratio of the axial length L16 of the insert portion 16 to the total length L12 of the head portion 12 within the range of 0.1 to 0.35, the head portion 12 can be reliably held by the handle portion 13. It becomes hard to come off, and the length of the brush part 11 becomes the length which can be easily inserted between teeth, and the usability is improved. In addition, sufficient cushioning properties of the brush portion 11 made of the soft resin member 15 can be obtained.

Next, the length dimension of the head portion 12 will be described in detail.
The total length L12 of the head portion 12 is preferably within the range of 10 mm to 30 mm, more preferably within the range of 12 mm to 20 mm.

The insert portion 16 is composed of the second portion R2 of the hard resin member 14 and the edge portion 15b of the soft resin member 15, as described above. The axial length L16 of the insert portion 16 is preferably in the range of 2.0 mm to 10.0 mm, more preferably in the range of 3.0 mm to 6.0 mm. In this embodiment, the length L16 of the insert portion 16 is 3.5 mm.

Even if the axial length L16 of the insert portion 16 in the head portion 12 is shorter than 2.0 mm or longer than 10.0 mm, the position of the head portion 12 in the mold may shift due to resin pressure during insert molding. deviate. By setting the length L16 of the insert portion 16 within the range of 2.0 mm to 10.0 mm, the bending of the head portion 12 during insert molding is eliminated and the yield is improved.

Of the insert portion 16, the length L15 of the edge portion 15b of the soft resin member 15 is preferably within the range of 0.5 mm to 5.0 mm, more preferably within the range of 1.0 mm to 3.0 mm. is more preferred. If the length L15 of the soft resin member 15 in the insert portion 16 is shorter than 0.5 mm, the interface between the head holding portion 13C on the side of the handle portion 13 and the soft resin member 15 on the side of the insert portion 16 inserted therein may When stress is concentrated, the head portion 12 tends to come off from the handle portion 13, or the soft resin member 15 tends to peel off. Therefore, by inserting a length within the range of 0.5 mm to 5.0 mm from the edge portion 15b of the soft resin member 15 into the handle portion 13 and sufficiently covering the edge portion 15b with the head holding portion 13C, , detachment of the head portion 12 and peeling of the soft resin member 15 can be suppressed.

Further, the length L14 of the second portion R2 of the hard resin member 14 exposed from the soft resin member 15 in the insert portion 16 is also preferably within the range of 0.5 mm to 5.0 mm, more preferably 1.0 mm to 1.0 mm. A range of 3.0 mm is more preferable. In this embodiment, it is 2.5 mm. If the length of the second portion R2 is shorter than 0.5 mm, the adhesiveness to the handle portion 13 during insert molding is reduced, and the second portion R2 is likely to come off. Therefore, by setting the length L14 of the second portion R2 of the hard resin member 14 within the range of 0.5 mm to 5.0 mm, it is possible to prevent the head portion 12 from coming off the handle portion 13. FIG.

The depth t of the groove portion 17 provided in the insert portion 16 is preferably within the range of 0.1 mm to 0.3 mm, more preferably 0.15 to 0.25 mm. Moreover, the width of the groove portion 17 is preferably in the range of 0.2 mm to 0.5 mm, more preferably 0.30 to 0.40 mm. By setting the depth and width of the grooves 17 within the above ranges, the handle 13 is formed in a state in which the resin enters the grooves 17 during insert molding, so the contact area with the head 12 increases. It is possible to prevent the head portion 12 from falling off from the handle portion 13 .

<Manufacturing method of interdental brush>
Next, a method for manufacturing the interdental brush 100 will be described.
First, the head portion 12 is molded.
A hard resin member 14 that serves as the axis of the head portion 12 is produced by injection molding.
Next, the hard resin member 14, which is a primary molded product, is placed in a mold, and a soft resin material is injected to produce the soft resin member 15 covering the first portion R1 by two-color molding. Thus, the head portion 12 is obtained.

Next, the rear end side of the head portion 12 prepared in advance is inserted into the mold. At this time, the insert portion 16 of the head portion 12 is inserted into the mold. In this state, the handle portion 13 is formed by injecting the heated and melted hard resin material of the head portion 12 into the closed mold cavity. The hard resin material poured into the mold wraps around the insert portion 16 and is thermally welded to the outer peripheral surface of the insert portion 16 . By such insert molding, the head portion 12 and the handle portion 13 are integrally molded to obtain the interdental brush 100 of the present embodiment.

By integrally molding the head portion 12 and the handle portion 13 using insert molding in this manner, the head portion 12 can be reliably fixed to the handle portion 13 .
In this embodiment, the hard resin member 14 and the handle portion 13 are both made of the same material. Therefore, by exposing a part of the hard resin member 14 in the insert portion 16 of the head portion 12 from the soft resin member 15, the weldability between the head portion 12 and the handle portion 13 is improved during insert molding. Both are securely connected and integrated.

Also, by changing the mold, the shape of the handle portion 13 can be freely manufactured.

By insert molding, the head holding portion 13C of the handle portion 13 is thermally welded to the insert portion 16 so as to cover the entire insert portion 16 including the edge portion 15b of the soft resin member 15 of the head portion 12 from the outside in the radial direction. Therefore, the joint portion 19 between the head portion 12 and the handle portion 13 has the three-layer structure described above. Therefore, when the interdental brush 100 is repeatedly used, it is possible to suppress peeling of the interface between the soft resin member 15 and the hard resin member 14 in the head portion 12 .

Conventional wire-free interdental brushes are disposable and therefore have low durability and are not suitable for repeated use. The elastomer does not come off during use and has excellent durability. Furthermore, since the head portion 12 is hard to break and hard to get peculiar, it can be used for a certain period of time like a toothbrush instead of being disposable. Furthermore, since a good cleaning effect between the teeth can be obtained for a long period of time, the interdental brush 100 is as easy to use as a wire-type interdental brush.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited by the following description.

Tables 1 and 2 show details of the structure and evaluation of Examples 1 to 14 and Comparative Example 1 of the interdental brushes used as samples.

<Durability>
First, an evaluation test was conducted on the durability of the head portion.
Among the head portions of the interdental brushes of Examples 1 to 14 and Comparative Example 1, at least the end portion of the brush portion having the cleaning portion was vertically chucked, and the handle portion was positioned downward. A weight of 100 g is hung downward about 6 mm from the tip. Next, around the center of the chucking area, the brush portion, which is the chucking part, is rotated left and right at 30 rpm by 90°, and the handle portion is moved in a pendulum motion. In this state, the number of reciprocations until the head section was completely broken was counted (up to 300 times). Each sample of Examples 1 to 14 and Comparative Example 1 was repeatedly tested five times, and the average values are shown in Table 1 or Table 2.

<Pull-out strength>
Next, an evaluation test was conducted on the pull-out strength of the head portion from the handle portion.
The interdental brushes of Examples 1 to 14 and Comparative Example 1 were fixed in a posture with the respective head portions facing up and the handle portions facing the vertical direction, and the head portion was about 5 mm from the boundary between the handle portion and the head portion. Chuck the area above the . In this state, the head portion was pulled vertically at 20 mm/min, and the strength when the head portion was pulled out from the handle portion was measured. Each sample of Examples 1 to 14 and Comparative Example 1 was repeatedly subjected to five evaluation tests, and the average values are shown in Table 1 or Table 2.

<Peelability of soft resin member>
The toothbrushes of Examples 1 to 14 and Comparative Example 1 were fixed in a posture in which the head portion was facing upward and the handle portion was oriented vertically, and about 5 mm from the boundary between the handle portion and the head portion, above the head portion. Chuck the area of . In this state, the head portion was pulled vertically at 20 mm/min until a load of 10 N was applied, and the degree of peeling of the soft resin member was examined. Each sample of Examples 1 to 14 and Comparative Example 1 was repeatedly subjected to five evaluation tests, and Table 1 or Table 2 shows the worst results among the five tests.

<Usability between the teeth of the interdental brush>
A panel of 10 experts performed sensory testing for 30 days of use (once a day) for evaluation.
Usability between the teeth of the interdental brush, that is, insertability was evaluated according to the following criteria.
Here, the evaluation results of 10 persons were averaged and shown in Table 1 or Table 2.
5 points: Very easy to insert into interdental areas 4 points: Somewhat easy to insert into interdental areas 3 points: Neither 2 points: Somewhat difficult to insert into interdental areas 1 point: Very easy to insert into interdental areas hard to insert

<Bending condition of the axis of the head part>
Each sample of the interdental brushes of Examples 1 to 14 and Comparative Example 1 before use was subjected to image analysis with a microscope. The degree of deviation of the tip of the shaft from the line was calculated by the following formula.

Deviation of the tip of the shaft (%)={(deviation in the width direction of the tip of the shaft from the center line of the shaft)/(base width of the shaft)}×100

The deviation of the tip of the shaft center was calculated by assuming deviation to one side in the width direction as (+) and deviation to the other side in the width direction as (-). Each sample of Examples 1 to 14 and Comparative Example 1 was repeatedly subjected to evaluation tests five times.

As shown in Tables 1 and 2, the above evaluation results showed that Examples 1 to 14 were significantly superior to Comparative Example 1 in durability. As for the peeling of the soft resin member, the structure of Comparative Example 1 was largely peeled, while the structures of Examples 1 to 14 were not peeled at all, or if peeled, were only slightly peeled. stayed in In addition, as compared with Comparative Example 1, Examples 1 to 14 gave significantly better evaluations of usability by the testers.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope of the technical idea described in the claims, and these are also within the technical scope of the present invention. be understood to belong to

DESCRIPTION OF SYMBOLS 11... Brush part 12... Head part 13... Handle part 13C... Head holding part 14... Hard resin member 15... Soft resin member 15b... Edge part 16... Insert part 100... Interdental brush, D2: maximum diameter of the insert portion, L14: length of the second portion (base end portion 14b), L15: length of the edge portion 15b, L16: length of the insert portion 16, O: shaft, R1: first Part R2... second part r14... radius of hard resin member 14 T13... radial thickness of head holding portion 13C T15... radial thickness of soft resin member 15

Claims (9)

a head portion having a length in the axial direction and having a brush portion around the axis;
a handle portion connected to one end side of the head portion in the axial direction,
The head section
a hard resin member having a first portion and a second portion arranged in the axial direction;
a soft resin member that axially covers the first portion of the hard resin member;
an insert portion comprising the second portion of the hard resin member and an edge portion of at least a portion of the soft resin member on the side of the second portion;
The handle portion has a head holding portion that covers at least the entire insert portion of the head portion from the radially outer side,
in the axial direction,
a region where the insert portion and the head holding portion overlap is only a tip end side of the handle portion;
The insert portion has a length of 2 mm to 15 mm,
The second portion has a length of 0.4 mm to 6.0 mm, and
the length of the second portion is in the range of 0.08 to 0.2 times the total length of the head portion;
The structure of the connecting portion between the head portion and the handle portion is composed of the hard resin member in the insert portion of the head portion, the edge portion of the soft resin member, and the head holding portion in the handle portion. It has a three-layer structure ,
The interdental brush, wherein the length of the edge in the axial direction is 0.4 to 2.0 times the length of the second portion. When the thickness of the soft resin member in the transverse direction is 1, the half dimension of the thickness of the second portion of the hard resin member is a ratio to the thickness of the soft resin member in the transverse direction. is in the range of 2 to 5,
An interdental brush according to claim 1. When the radial thickness of the soft resin member is 1, the ratio of the radial thickness of the head holding portion to the radial thickness of the soft resin member is in the range of 2 to 5. ,
An interdental brush according to claim 1 or 2. The insert portion has a diameter in the range of 0.4 mm to 2.0 mm,
Among the insert parts,
the diameter of the second portion is in the range of 0.3 mm to 1.4 mm;
The soft resin member has a radial thickness in the range of 0.05 mm to 0.3 mm,
The radial thickness of the head holding portion is in the range of 0.3 mm to 1.5 mm ,
An interdental brush according to any one of claims 1-3. The ratio of the length of the insert portion in the axial direction to the length of the brush portion is in the range of 0.1 to 0.35.
An interdental brush according to any one of claims 1-4. The length of the insert portion in the axial direction is 2.0 mm to 5.0 mm,
In the insert portion, the length of the soft resin member is 0.5 mm to 5.0 mm , and the length of the second portion is 0.5 mm to 5.0 mm .
An interdental brush according to claim 5. The head portion and the handle portion are integrally constructed by insert molding,
An interdental brush according to any one of claims 1-6. the entire radially inward facing surface of the edge portion is in contact with the radially outward facing surface of the hard resin member;
the entire radially outwardly facing surface of the insert portion is in contact with the radially inwardly facing surface of the head holding portion;
An interdental brush according to any one of claims 1-7. forming a head portion by covering at least part of a hard resin member having a length in an axial direction with a soft resin member;
at least a step of insert-molding a handle portion on one axial end side of the head portion;
In the step of insert molding,
By inserting the insert provided at one end in the axial direction of the head portion into the cavity of the mold and pouring resin into the cavity of the closed mold, the entire insert is moved radially outward. By molding the handle portion having a holding portion covering from
A connecting portion between the head portion and the handle portion is formed with a three-layer structure including a hard resin member in the insert portion of the head portion, the soft resin member, and the holding portion in the handle portion. A method for manufacturing an interdental brush according to any one of claims 1 to 8 .

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