JP7511402B2 - Interdental Cleaning Tools - Google Patents

Description

The present invention relates to an interdental cleaning tool for cleaning between teeth.

Interdental cleaners suitable for cleaning between molars are known (see, for example, Patent Documents 1 and 2). These interdental cleaners include a main body having a base with a gripping portion at one end that can be held with the fingers and a shaft extending from the other end of the base, and a cleaning portion made of an elastic material with a hardness lower than that of the main body, covering at least a portion of the outer surface of the shaft.

The interdental cleaning tool described in Patent Document 1 has a base (called the handle substrate body in the document) that has a handle body and a tapered substrate portion, and the tip of the tapered substrate portion is curved. In addition, a non-slip portion made of an elastic material (called an elastomer in the document) is formed around the entire circumference of the middle part of the tapered substrate portion, and a long, thin elastic material is formed extending from the center of the surface of the tapered substrate portion to connect this non-slip portion and the cleaning portion. With this configuration, the base is exposed at the dorsal portion located on the dorsal side, which is the outer side of the curve of the tip of the tapered substrate portion, and the ventral portion located on the ventral side, which is the inner side of the curve of the tip of the tapered substrate portion.

The interdental cleaner described in Patent Document 2 has a base having a connecting portion that connects the grip portion and the shaft portion, and this connecting portion has a bent portion (called a support portion in the document) that is bent from the end opposite the grip portion. In addition, the connecting portion is formed with a ventral deformation portion and a dorsal deformation portion that are separately formed, and is configured so that the ventral deformation portion and the dorsal deformation portion are elastically deformed when the cleaning portion is inserted between the teeth and moved back and forth.

JP 2016-104382 A JP 2017-86774 A

In an interdental cleaner suitable for cleaning between molars, when the cleaning part (shaft) is inserted between the teeth and moved back and forth while an external force is applied to the grip, stress in the direction of reciprocation and in a direction intersecting the direction of reciprocation is transmitted from the shaft to the base due to friction and contact between the teeth and the cleaning part covering the shaft. In this case, if the base is exposed at the dorsal part on the outer curve of the tip of the tapered base material and the ventral part on the inner curve, as in the interdental cleaner described in Patent Document 1, the boundary between the shaft and the curved part may be excessively deformed, or excessive stress may be concentrated at the curved part, causing breakage.

On the other hand, the interdental cleaner described in Patent Document 2 is capable of preventing damage to the boundary between the shaft and the bent portion and to the bent portion by using the ventral deformation portion and the posterior deformation portion. However, since the ventral deformation portion and the posterior deformation portion are formed separately in the connecting portion, the rigidity is lower than in a shape in which the connecting portion is integrated, and there is room for improvement.

Therefore, there is a demand for highly durable interdental cleaners suitable for cleaning between back teeth.

An interdental cleaning tool according to one aspect of the present invention comprises a main body made of resin integrally having a base having a grip portion that can be gripped with fingers and an extension portion extending from the grip portion in a first direction, a bent portion that extends from an end of the extension portion opposite the grip portion and is bent from the first direction toward a second direction intersecting the first direction, and a shaft portion that extends from an end of the bent portion opposite the extension portion along the second direction, and a soft member made of an elastic material having a hardness lower than that of the main body, covering at least a part of the outer surface of the shaft portion and configured with an outer shape that allows insertion between teeth, and the extension portion and the bent portion are entirely filled with the resin with no internal space, and the soft member has at least a dorsal bent portion located on the dorsal side, which is the outer bent side of the bent portion, and a cleaning portion that is connected to the dorsal bent portion and is on the dorsal side of the extension portion. The soft member covers the dorsal extension portion and the ventral extension portion opposite the dorsal extension portion of the bending portion, and the ventral extension portion opposite the dorsal extension portion of the extending portion is not covered with the soft member and the resin is exposed, and the distance between the bending convex portion protruding to the dorsal side of the dorsal bending portion and the surface located on the dorsal side of the soft member covering the dorsal bending portion is greater than or equal to one-tenth and less than one-half of the planar distance perpendicular to the second direction of the bending portion including the soft member on a plane including the first direction and the second direction, and the distance between the extending convex portion protruding to the dorsal side of the dorsal extension portion and the surface located on the dorsal side of the soft member covering the dorsal extension portion is greater than or equal to one-tenth and less than one-half of the planar distance perpendicular to the first direction of the extending portion including the soft member on a plane including the first direction and the second direction .

In the case of an interdental cleaner that has a bent portion, such as this interdental cleaner, when the cleaning portion (shaft portion) is inserted between the teeth and moved back and forth while an external force is applied to the grip portion, friction and contact between the cleaning portion that covers the shaft portion and the teeth transmits stress in the direction of reciprocating movement and in a direction that intersects the direction of reciprocating movement from the shaft portion to the extension portion via the bent portion.

In this interdental cleaner, a flexible soft member with a lower hardness than the main body made of resin of the shaft, bending portion, and base (gripping portion and extending portion) covers at least the dorsal bending portion of the bending portion and the dorsal extending portion of the extending portion. Therefore, the body has a high rigidity and has an extending portion and bending portion that are filled with resin without any internal space, and while maintaining a moderate strength, the soft member can absorb the stress transmitted to the extending portion via the bending portion and exhibit a buffering function. Moreover, since the soft member is continuous with the dorsal bending portion and dorsal extending portion, the deformation of the bending portion can be absorbed by the soft member, and the stress load acting on the shaft (especially the boundary between the shaft and bending portion) can also be reduced. As a result, even if the cleaning portion (shaft) is inserted between the teeth and repeatedly moved back and forth, the bending portion flexibly deforms dorsally, and the shaft is not likely to break.

In this way, we have been able to provide a highly durable interdental cleaner suitable for cleaning between molars.

As another configuration, it is preferable that the cleaning part is configured such that the elastic material covers the entire shaft portion, and the soft member extends continuously from the cleaning part to the back bend portion.

In this way, when the soft member covering the entire cleaning part is continuous with the dorsal bending part, the stress load acting on the boundary part between the shaft part and the bending part can be further alleviated. As a result, the stress load acting on the shaft part can be further alleviated while dispersing the stress concentrated on the boundary part. In addition, even when the boundary part comes into contact with the inner wall of the oral cavity when cleaning the back teeth, damage to the oral cavity can be suppressed.

As another configuration, it is preferable that the most dorsal portion of the dorsal bending portion and the dorsal extension portion is made only of the elastic material.

In this way, if the most dorsal part of the dorsal bending part and the dorsal extension part are made only of elastic material, even if the resin part that makes up the main body is damaged, the damaged resin part is held in place by the elastic material, preventing the inconvenience of the resin part being swallowed.

As another configuration, it is preferable that the ventral bending portion and the ventral extending portion, and the dorsal bending portion and the dorsal extending portion covered with the soft member have generally substantially the same dimensions in the width direction perpendicular to both the first direction and the second direction.

In this way, if the widths of the ventral bent portion and ventral extending portion and the dorsal bent portion and dorsal extending portion covered with the soft member are configured to be generally approximately the same overall, that is, if the widths are generally approximately the same overall, when the cleaning part (shaft part) is inserted between the teeth and repeatedly moved back and forth, the stress acting on the bent portion and extending portion is evenly distributed, making the interdental cleaner less likely to break.

As another configuration, it is preferable that the area ratio on a plane including the first direction and the second direction between the dorsal bending portion and the dorsal extension portion and the ventral bending portion and the ventral extension portion is 2:8 to 8:2.

In this way, by configuring the ratio between the dorsal bent portion and dorsal extending portion covered with the soft material and the ventral bent portion and ventral extending portion with exposed resin, the body has a high rigidity and maintains a moderate strength, while the stress transmitted to the extending portion via the bent portion is received by the soft material, effectively providing a cushioning function.

FIG. 1 is a perspective view showing an interdental cleaning tool according to an embodiment of the present invention. FIG. 2 is a perspective view showing a main body according to the embodiment. FIG. 2 is a perspective view of the main body according to the embodiment, seen from the rear side. FIG. 13 is a diagram showing an example of use of the interdental cleaner.

Below, an embodiment of the interdental cleaning tool according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications are possible without departing from the spirit of the present invention.

As shown in FIG. 1, the interdental cleaner D in this embodiment has a flat inverted S-shape when viewed perpendicular to the paper surface, allowing it to be stably placed on the support surface H. Below, the view perpendicular to the paper surface, looking toward the support surface H on which the interdental cleaner D is placed, will be described as a plan view.

As shown in Figures 1 and 2, the interdental cleaner D comprises a base 1 having a grip 11 and an extension 12, a bent portion 2, and a shaft 3 integrally molded, a main body A made of resin, and a soft member B made of an elastic material having a hardness lower than that of the main body A and having a cleaning portion 4. In this embodiment, the extension 12 and the bent portion 2 are filled with resin with no space inside. Below, the interdental cleaner D will be described with the outer side of the bent portion 2 (the right side of the paper in Figure 2) as the dorsal side, and the inner side of the bent portion 2 (the left side of the paper in Figure 2) as the ventral side.

The main body A is made of one or a combination of two or more synthetic resins (examples of resins) such as polypropylene, ABS, polybutylene terephthalate, polycarbonate, polyethylene terephthalate, polystyrene, and polyacetal. In this embodiment, the main body A is made of polypropylene. In addition, the synthetic resin constituting the main body A preferably contains a reinforcing agent that increases rigidity. Examples of reinforcing agents include fibrous reinforcing agents such as glass fiber, nanocellulose fiber, aramid fiber, and carbon fiber, plate-shaped reinforcing agents such as mica and glass frames, powdered reinforcing agents such as talc, and needle-shaped reinforcing agents such as wollastonite. The content of the reinforcing agent is 5% by weight or more and 50% by weight or less, preferably 10% by weight or more and 40% by weight or less, and more preferably 15% by weight or more and 40% by weight or less.

The soft member B is made of an elastomer (an example of an elastic material) that has a hardness lower than that of the main body A. As this elastomer, a styrene-based elastomer is preferable, but silicone, olefin-based elastomer, polyester-based elastomer, etc. may also be used.

As shown in FIG. 2, in the main body A, the extension portion 12 is configured in a flat rod shape extending from the grip portion 11 in the first direction Xa. The extension portion 12 is composed of a dorsal extension portion 12b located on the dorsal side, an extension ventral surface 12c located on the ventral side, and two parallel side surfaces 12d, 12d formed between the dorsal extension portion 12b and the extension ventral surface 12c. The dorsal extension portion 12b is composed of an extension back surface 12b2 that is a surface perpendicular to the side surface 12d, and an extension convex portion 12b1 that protrudes perpendicularly and outwardly from the extension back surface 12b2. The thickness of the extension convex portion 12b1 in a direction perpendicular to the protruding direction is thinner than the thickness between the two side surfaces 12d, 12d, and the extension back surface 12b2 is formed on both sides of the base end of the extension convex portion 12b1. The extending back surface 12b2 and the extending protruding portion 12b1 extend along the first direction Xa over the entire area of the dorsal extending portion 12b. The entire extending ventral surface 12c is composed of a flat surface. At the boundary portion on the dorsal side between the extending portion 12 and the gripping portion 11 in the extending protruding portion 12b1, a recessed portion 12a is formed that is recessed on the ventral side.

As shown in FIG. 1, the back extension portion 12b of the extension portion 12 is covered by the soft member B in a state of being in close contact with the extension convex portion 12b1 and the extension back surface 12b2. The pair of outer surfaces covered by the soft member B are both flush with the two side surfaces 12d, 12d. Hereinafter, when the main body A is covered by the soft member B, the outer surfaces of the soft member B flush with the two side surfaces 12d, 12d of the main body A will be referred to as the two side surfaces 12d, 12d. As a result, in the outer shape formed by the extension portion 12 and the soft member B, the soft extension back surface 12b3 located on the back side on a plane perpendicular to the placement surface H and the back half of the two side surfaces 12d, 12d of the extension portion 12 parallel to the placement surface H can be seen by the soft member B in the back region. On the other hand, the extended ventral surface 12c of the extended portion 12, which is located on the ventral side on a plane perpendicular to the placement surface H, is not covered with the soft member B, and the synthetic resin that constitutes the extended portion 12 is exposed. In addition, the ventral halves of the two side surfaces 12d, 12d of the extended portion 12 that are parallel to the placement surface H are also not covered with the soft member B, and the synthetic resin that constitutes the extended portion 12 is exposed. In other words, the extended ventral surface 12c and the two side surfaces 12d, 12d that are not covered with the soft member B are located on the opposite side to the dorsal extended portion 12b of the extended portion 12, and form the ventral extended portion 12e where the synthetic resin is exposed.

Of the external shape formed by the extension 12 and the soft member B, the portion of the soft extension back surface 12b3 on the side of the bent portion 2 is configured as a convex arc shape with a center of curvature on the ventral side. Of the external shape formed by the extension 12 and the soft member B, the portion of the soft extension back surface 12b3 on the side of the grip portion 11 is configured as a concave arc shape with a center of curvature on the dorsal side, forming a smoothly continuous arc flush with the back surface of the grip portion 11. As a result, the back surface of the interdental cleaning tool D is an inverted S-shaped curve, and the external shape formed by the extension 12 and the soft member B gradually narrows in width in a plan view from the grip portion 11 toward the bent portion 2.

2, in the main body A, the bending portion 2 extends from the end of the extension portion 12 opposite to the grip portion 11 and is configured in a flat shape bent from the first direction Xa toward the second direction Xb that intersects with the first direction Xa (in the embodiment of FIG. 1, the inner bending angle is 120 degrees). That is, the dorsal bending portion 21 located on the dorsal side of the bending portion 2 is configured in an arc shape having a center of curvature on the ventral side, and the ventral bending portion 22 located on the ventral side of the bending portion 2 is also configured in an arc shape having a center of curvature on the ventral side. In this embodiment, the radius of curvature of the dorsal bending portion 21 is configured to be larger than the radius of curvature of the ventral bending portion 22. That is, the dorsal bending portion 21 has a smaller and gentler curvature than the ventral bending portion 22. The intersection angle between the first direction Xa and the second direction Xb (the inner bending angle of the bending portion 2) is preferably configured to be 30 degrees or more and 150 degrees or less, preferably 80 degrees or more and 140 degrees or less, and more preferably 100 degrees or more and 130 degrees or less.

In addition, the entire area of the dorsal bent portion 21 is formed with a bent convex portion 21b that is flush and continuous with the extended convex portion 12b1 of the extension portion 12, and a bent back surface 21a that is flush and continuous with the extended back surface 12b2. The bent convex portion 21b protrudes outward from the bent back surface 21a and gradually bends and extends from the first direction Xa toward the second direction Xb. The bent ventral surface 22a of the ventral bent portion 22 is flush and continuous with the extended ventral surface 12c, and the entire area of the bent ventral surface 22a is composed of an arc-shaped flat surface.

A protrusion 23 is formed on the bent convex portion 21b of the bent portion 2 of the main body A so as to protrude in a direction parallel to the second direction Xb (see also FIG. 3). This protrusion 23 is configured so as to be able to come into contact with a molding die that forms the soft member B on the main body A, and the contact surface of the protrusion 23 with the molding die is formed as a flat surface.

1 and 2, the back side bending portion 21 of the bending portion 2 is covered by the soft member B in a state of being in close contact with the bending convex portion 21b and the bending back surface 21a. The pair of outer surfaces covered by the soft member B are both flush with the two side surfaces 25, 25. Hereinafter, in a state in which the main body A is covered by the soft member B, the outer surfaces of the soft member B flush with the two side surfaces 25, 25 of the main body A are also referred to as the two side surfaces 25, 25. As a result, the soft member B can be seen in the back side region formed by the soft bending back surface 21c located on the back side and the back half of the two side surfaces 25, 25 parallel to the placement surface H in the bending portion 2, among the external shape formed by the bending portion 2 and the soft member B. In addition, the soft bending back surface 21c located on the back side of the external shape formed by the bending portion 2 and the soft member B is formed in an arc shape having a center of curvature on the ventral side. On the other hand, the bent ventral surface 22a located on the ventral side of the bent portion 2 is not covered with the soft member B, and the synthetic resin that constitutes the bent portion 2 is exposed. In addition, the ventral halves of the two side surfaces 25, 25 of the bent portion 2 that are parallel to the placement surface H are also not covered with the soft member B, and the synthetic resin that constitutes the bent portion 2 is exposed. In other words, the bent ventral surface 22a and the two side surfaces 25, 25 that are not covered with the soft member B are located on the opposite side of the dorsal bent portion 21 of the bent portion 2, and form the ventral bent portion 22 where the synthetic resin is exposed.

With this configuration, the soft member B covers the dorsal bending portion 21 of the bending portion 2 of the main body A, and further covers the dorsal extension portion 12b of the extension portion 12 in connection with the dorsal bending portion 21. Furthermore, the widthwise dimension W1 perpendicular to the first direction Xa and the second direction Xb of the dorsal bending portion 21 and the dorsal extension portion 12b is generally configured to be substantially the same (see FIG. 3). Furthermore, as described above, since the two side surfaces 12d, 12d of the extension portion 12 and the two side surfaces 25, 25 of the bending portion 2 are flush with each other, the widthwise dimension W2 perpendicular to the first direction Xa and the second direction Xb of the ventral bending portion 22 and the ventral extension portion 12e and the dorsal bending portion 21 and the dorsal extension portion 12b covered with the soft member B is generally configured to be substantially the same (see FIG. 1). This makes it difficult for the interdental cleaner D to break because the stress acting on the bent portion 2 and the extended portion 12 is evenly distributed when the cleaning portion 4 (shaft portion 3) is inserted between the teeth and repeatedly moved back and forth.

1 and 2, the most dorsal part of the dorsal bending part 21 and the dorsal extension part 12b in this embodiment is composed only of elastomer. In other words, the most dorsal protruding part of the bending convex part 21b and the extension convex part 12b1 is spaced further ventrally than the soft extension back surface 12b3. This separation distance L1 is preferably 1/10 to 1/2, and more preferably 1/5 to 1/3, of the planar distance L perpendicular to the first direction Xa or the second direction Xb of the bending part 2 and the extension part 12 on a plane including the first direction Xa and the second direction Xb. Note that the planar distance L changes so as to become larger from the bending part 2 toward the grip part 11, so it is the ratio of the separation distance L1 to the planar distance L measured on the same line perpendicular to the first direction Xa or the second direction Xb, but is displayed at a different position in FIG. 1 to make it easier to see. If the separation distance L1 is set within this range, and the rearmost part of the rear bend portion 21 and the rear extension portion 12b are made only of elastomer, even if the resin part that makes up the main body A is damaged, the damaged resin part will be held in place by the elastomer, preventing the inconvenience of the resin part being swallowed up.

In addition, the area ratio on a plane including the first direction Xa and the second direction Xb between the dorsal bending portion 21 and the dorsal extending portion 12b covered with the soft member B and the ventral bending portion 22 and the ventral extending portion 12e where the synthetic resin is exposed is preferably 2:8 to 8:2, more preferably 4:6 to 6:4. In other words, on a plane including the first direction Xa and the second direction Xb, the planar distance L2 perpendicular to the first direction Xa or the second direction Xb of the soft member B is preferably 1/5 to 4/5, more preferably 2/5 to 3/5, of the planar distance L perpendicular to the first direction Xa or the second direction Xb of the bending portion 2 and the extending portion 12. Note that this planar distance L2 changes so as to become larger from the bending portion 2 toward the gripping portion 11, and is therefore the ratio to the planar distance L measured on the same line perpendicular to the first direction Xa or the second direction Xb, but is shown at different positions in FIG. 1 to make it easier to see. With such a ratio, the main body A with high rigidity maintains a moderate strength, while the soft member B can receive the stress transmitted to the extension portion 12 through the bent portion 2, thereby providing a cushioning function. In addition, it is preferable that the ratio of the planar distance L2 to the planar distance L is approximately the same 1/2 across the first direction Xa or the second direction Xb. In other words, it is preferable that the planar distance perpendicular to the first direction Xa or the second direction Xb on a plane including the first direction Xa and the second direction Xb is approximately the same overall between the dorsal bent portion 21 and the dorsal extension portion 12b covered with the soft member B and the ventral bent portion 22 and the ventral extension portion 12e where the synthetic resin is exposed. This eliminates the inflection point at which the portion covered with the soft member B changes significantly, and there is no inconvenience that stress is concentrated at this inflection point, making it prone to breaking.

As shown in FIG. 2, the shaft portion 3 is formed in a truncated cone rod shape that gradually tapers in the second direction Xb from the end opposite the extension portion 12 relative to the bent portion 2. The outer shape of the shaft portion 3 has a linear taper such that the diameter decreases from the connection portion (base end) with the bent portion 2 toward the tip.

As shown in FIG. 1, the cleaning part 4, which constitutes a part of the soft member B, covers at least a part of the outer surface of the shaft part 3 and has an outer shape that allows it to be inserted between teeth. In this embodiment, the cleaning part 4 has a covering part 41 that adheres to the entire shaft part 3, and a brush part 42 that has multiple (many) bristles protruding outward from the covering part 41. The covering part 41 is configured with a thickness smaller than the diameter of the shaft part 3. The brush part 42 is formed in a cone shape that tapers as it moves away from the covering part 41. In the interdental cleaning tool D according to this embodiment, when the cleaning part 4 is inserted between teeth, the bristles of the brush part 42 flexibly deform, and the covering part 41 and the brush part 42 come into contact with the teeth, removing foreign matter (food debris, etc.) present between the teeth and foreign matter (plaque, etc.) attached to the teeth.

In this embodiment, the soft member B extends continuously from the cleaning part 4 to the dorsal bent portion 21. When the soft member B covering the entire cleaning part 4 is continuous with the dorsal bent portion 21 in this way, the stress load acting on the boundary part between the shaft part 3 and the bent portion 2 can be further alleviated. As a result, the stress concentrated on the boundary part can be dispersed, while the stress load acting on the shaft part 3 can be further alleviated. As a result, even if the cleaning part 4 is inserted between the teeth and repeatedly moved back and forth, the bent portion 2 flexibly deforms toward the dorsal side, and the shaft part 3 is unlikely to break. In addition, even when the boundary part comes into contact with the inner wall of the oral cavity during cleaning of the back teeth, damage to the oral cavity can be suppressed.

Next, a method for manufacturing the interdental cleaner D according to this embodiment will be described. The interdental cleaner D is manufactured by a two-color molding method in which the cleaning part 4 (soft member B) is molded onto the shaft part 3 of the main body A made of synthetic resin by a known method such as injection molding. Specifically, the main body A is first integrally formed by a known method such as injection molding. Next, the formed main body A is placed in a two-color molding mold, and molten elastomer is injected into the mold from a gate provided near the tip of the shaft part 3 of the main body A to fill it. The filled molten elastomer solidifies and becomes the soft member B. In this manner, the interdental cleaner D is manufactured.

4 shows a method of using the interdental cleaner D. The interdental cleaner D having the bent portion 2 can be held in roughly the following three ways.
(1) A first gripping method in which the grip portion 11 is pinched between the thumb and index finger. (2) A second gripping method in which the grip portion 11 is pinched between the thumb and middle finger and the index finger is placed along the soft extending back surface 12b3 of the extending portion 12. (3) A third gripping method in which the grip portion 11 and the extending portion 12 are gripped in their entirety.

The user holds the interdental cleaner D by any gripping method and inserts the cleaning part 4 from the tip to the base end into the oral cavity so that the cleaning part 4 is inserted between the molars. The user then operates the interdental cleaner D to move the cleaning part 4 back and forth between the teeth. When the cleaning part 4 (shaft part 3) is inserted between the teeth and moved back and forth while an external force is applied to the grip part 11, stress in the direction of the reciprocating movement and in a direction intersecting the reciprocating movement direction is transmitted from the shaft part 3 to the extension part 12 via the bent part 2 due to friction and contact between the cleaning part 4 covering the shaft part 3 and the teeth.

As described above, in this embodiment, the soft member B, which is less hard and more flexible than the main body A consisting of the shaft portion 3, the bending portion 2, and the base portion 1 (the gripping portion 11 and the extension portion 12), covers the dorsal bending portion 21 of the bending portion 2. Therefore, while the main body A, which has high rigidity, maintains an appropriate strength, the soft member B can receive the stress concentrated in the bending portion 2 and exert a cushioning function. Moreover, since the bending portion 2 deforms appropriately, the stress load acting on the shaft portion 3 (particularly the boundary portion between the shaft portion 3 and the bending portion 2) can also be alleviated.

In addition, by covering the back extension portion 12b of the extension portion 12 with the soft member B as in this embodiment, it is possible to appropriately deform the base 1, and the stress load acting on the shaft portion 3 can be further alleviated while dispersing the stress concentrated on the bending portion 2. Furthermore, the ventral side of the bending portion 2 and the extension portion 12 that is not covered with the soft member B is less likely to elastically deform than the back side. Therefore, while ensuring an appropriate strength, the bending portion 2 can be deformed toward the back side to effectively alleviate the stress load acting on the shaft portion 3 (particularly the boundary portion between the shaft portion 3 and the bending portion 2) and the bending portion 2. Moreover, since the soft member B is continuous from the cleaning portion 4 to the back bending portion 21 and the back extension portion 12b, the deformation of the bending portion 2 can be absorbed by the soft member B, and the stress load acting on the shaft portion 3 (particularly the boundary portion between the shaft portion 3 and the bending portion 2) can also be alleviated. As a result, even if the cleaning part 4 (shaft part 3) is inserted between the teeth and repeatedly moved back and forth, the bent part 2 flexibly deforms toward the back side, making the shaft part 3 less likely to break.

In addition, if a protrusion 23 is provided on the bending portion 2 as in this embodiment, the soft member B adheres closely to this protrusion 23, so that even if the soft member B expands or contracts, it is difficult for it to peel off from the main body A. Moreover, the protrusion 23 can compensate for the reduction in strength caused by the soft member B.

[Other embodiments]
(a) The soft member B may be configured to cover only a portion of the back-side extending portion 12b of the extending portion 12 on the bent portion 2 side.

(b) The protrusion 23 in the above-described embodiment may be omitted, or the widthwise dimension W1 of the dorsal bending portion 21 and the dorsal extending portion 12b may be partially changed. In addition, the widthwise dimension W2 of the ventral bending portion 22 and the ventral extending portion 12e and the dorsal bending portion 21 and the dorsal extending portion 12b covered with the soft member B may be partially changed.
(c) In the above-described embodiment, the rearmost portions of the rear bending portion 21 and the rearmost extension portion 12b are made of only elastomer (elastic material). However, it is also possible to expose the resin of the portions that protrude most rearward of the bending convex portion 21b and the extending convex portion 12b1 and omit the portions made of only elastic material.

The present invention can be used in an interdental cleaning tool suitable for cleaning between back teeth.

1: Base 2: Bending portion 3: Shaft 4: Cleaning portion 11: Grip 12: Extension 12b: Dorsal extension portion 12e: Ventral extension portion 21: Dorsal bending portion 22: Ventral bending portion A: Main body B: Soft member D: Interdental cleaning tool W2: Width dimension Xa: First direction Xb: Second direction

Claims (6)

a main body made of resin integrally having a base having a grip portion that can be gripped with fingers and an extension portion that extends from the grip portion in a first direction, a bent portion that extends from an end of the extension portion opposite the grip portion and is bent from the first direction toward a second direction that intersects with the first direction, and a shaft portion that extends from an end of the bent portion opposite the extension portion along the second direction;
a soft member made of an elastic material having a hardness lower than that of the main body, covering at least a part of the outer surface of the shaft portion and having a cleaning portion configured with an outer shape that can be inserted between teeth;
The resin is filled throughout the entire extension portion and the entire bent portion without creating any space therein,
The soft member covers at least a dorsal bending portion located on the dorsal side, which is the bending outer side of the bending portion, and a dorsal extension portion connected to the dorsal bending portion and located on the dorsal side of the extension portion,
a ventral bending portion opposite to the dorsal bending portion of the bending portion and a ventral extending portion opposite to the dorsal extending portion of the extending portion are not covered with the soft member and the resin is exposed ;
A distance between the bending convex portion protruding toward the back side of the back bending portion and a surface located on the back side of the soft member covering the back bending portion is greater than or equal to 1/10 and less than or equal to 1/2 of a planar distance perpendicular to the second direction of the bending portion including the soft member on a plane including the first direction and the second direction,
An interdental cleaning tool in which the distance between the extending convex portion protruding toward the rear side of the rear extension portion and the surface located on the rear side of the soft member covering the rear extension portion is greater than or equal to one-tenth and less than one-half of the planar distance perpendicular to the first direction of the extending portion including the soft member on a plane including the first direction and the second direction . a main body made of resin integrally having a base having a grip portion that can be gripped with fingers and an extension portion that extends from the grip portion in a first direction, a bent portion that extends from an end of the extension portion opposite the grip portion and is bent from the first direction toward a second direction that intersects with the first direction, and a shaft portion that extends along the second direction from an end of the bent portion opposite the extension portion;
a soft member made of an elastic material having a hardness lower than that of the main body, covering at least a part of the outer surface of the shaft portion and having a cleaning portion configured with an outer shape that can be inserted between teeth;
The resin is filled throughout the entire extension portion and the entire bent portion without creating any space therein,
The soft member covers at least a dorsal bending portion located on the dorsal side, which is the outer side of the bending portion, and a dorsal extension portion connected to the dorsal bending portion and located on the dorsal side of the extension portion,
a ventral bending portion opposite to the dorsal bending portion of the bending portion and a ventral extending portion opposite to the dorsal extending portion of the extending portion are not covered with the soft member and the resin is exposed;
An interdental cleaning tool, wherein the grip portion widens from the extension portion in a direction opposite to the second direction. The cleaning portion is configured such that the elastic material covers the entire shaft portion,
The interdental cleaning tool according to claim 1 or 2 , wherein the soft member extends continuously from the cleaning portion to the dorsal curved portion. The interdental cleaner according to claim 1 , wherein the most dorsal portion of the dorsal curved portion and the dorsal extended portion is made of only the elastic material. The interdental cleaning tool according to any one of claims 1 to 4, wherein the ventral curved portion and the ventral extending portion, and the dorsal curved portion and the dorsal extending portion covered with the soft member have widthwise dimensions perpendicular to both the first direction and the second direction that are generally approximately the same. The interdental cleaning tool according to any one of claims 1 to 5, wherein an area ratio of the dorsal bending portion and the dorsal extending portion to the ventral bending portion and the ventral extending portion on a plane including the first direction and the second direction is 2:8 to 8 :2.

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