JP6937693B2 - Interdental brush - Google Patents

Description

The present invention relates to an interdental brush.
The present application claims priority based on Japanese Patent Application No. 2015-146028 filed in Japan on July 23, 2015, the contents of which are incorporated herein by reference.

Interdental brushes are widely used for the purpose of efficiently cleaning the space between teeth. Interdental brushes are roughly classified into those using a metal wire as a shaft material and those using a synthetic resin as a shaft material. An interdental brush with a synthetic resin shaft is more comfortable to touch the gums and teeth than an interdental brush with a metal wire. For example, in Patent Document 1, a plurality of shaft members formed by coating a synthetic resin core portion extending from the tip of a grip portion (handle portion) with an elastomer and a plurality of shaft members radially viewed from the extending direction of the shaft member are provided. An interdental brush with a protrusion made of an elastomer has been proposed.

Japanese Unexamined Patent Publication No. 2013-192866

However, the shaft material made of synthetic resin in the conventional interdental brush has a problem that it cannot be reused because it has poor durability and breaks during use or cleaning.

An object of the present invention is an interdental brush having excellent durability to the extent that it can be reused.

[1] An interdental brush including a grip portion and a brush portion provided at the tip of the grip portion, wherein the brush portion includes a first synthetic resin core portion extending from the grip portion and the said. A shaft material formed of a coating portion formed by coating the core portion with a second synthetic resin softer than the first synthetic resin, and a plurality of projecting pieces protruding from the shaft material are provided.
The shaft material is an interdental brush satisfying the following (A) to (C).
(A) Shaft bending strength; The repulsive force when a portion 5 mm from the tip of the shaft material is flipped at a speed of 10 mm / sec is 0.56 N or more.
(B) Shaft bending strength: The base end portion of the brush portion is bent 90 degrees in the first direction orthogonal to the axis of the shaft member, returned to its original position, and 90 degrees in the second direction opposite to the first direction. In the left-right bending test of bending and returning to the original position, the number of times of bending in the same direction until the core portion breaks is 20 times or more.
(C) Repeated bending strength: In a 90-degree bending test in which the base end portion of the brush portion is bent 90 degrees in the first direction orthogonal to the axis of the shaft member and then returned to the original direction, the fifth time in the same direction. The maximum stress when bending to is 1.7 N or more.
[2] The constituent material of the core portion has a flexural modulus of 3.0 GPa or more measured in accordance with ASTM D790 and a tensile elongation at break of 7.0% or more measured in accordance with ASTM D638. , [1].
[3] The interdental brush according to [1] or [2], wherein the first synthetic resin is a composite material containing a fiber material having a fiber length of 3 μm to 300 μm and a fiber diameter of 0.1 μm to 2.0 μm. ..
[4] The interdental brush according to [3], wherein the fiber material contains potassium titanate fiber.
[5] The interdental brush according to any one of [1] to [4], wherein the first synthetic resin is polyester.
[6] An interdental brush made of synthetic resin including a grip portion and a brush portion provided at the tip of the grip portion, wherein the brush portion includes a shaft member extending from the tip of the grip portion and the shaft. A plurality of projecting pieces projecting from the material are provided, the projecting pieces project radially when viewed from the extending direction of the shaft member, and the brush portion is formed closer to the rear end than the region (B). A region (A) and a region (B) formed on the tip side of the region (A) are included, and first projecting pieces of arbitrary height are arranged in the axial direction in the region (A). An interdental brush in which only protruding pieces having a height lower than that of the first protruding piece are arranged in the axial direction in the region (B).
[7] The region (A) includes a region (A1) in which the first protruding piece and the second protruding piece having a height lower than that of the first protruding piece are alternately arranged in the axial direction [6]. ] The interdental brush described in.
[8] The region (B) includes a region on the front end side (B1) and a region (B2) on the rear end side of the region (B1), and the region (B2) includes the second protrusion. Only the fourth protruding piece having a height equal to or lower than the piece is aligned in the axial direction, and the protruding piece in the region (B1) has a height equal to or lower than the fourth protruding piece and the region (B1). ) Contains a third protruding piece having a height lower than that of the fourth protruding piece, according to the interdental brush according to [7].
[9] The interdental brush according to any one of [6] to [8], wherein in the region (A), the axial distance between the first protruding pieces increases toward the tip. ..
[10] The interdental space according to any one of [6] to [9], wherein a diameter-expanding portion that increases in diameter from the tip to the rear end is provided near the brush portion of the grip portion. brush.

Since the interdental brush of the present invention has excellent durability, it can be prevented from breaking during use and can be washed and used repeatedly.

It is a top view which showed the interdental brush 1 of the 1st Embodiment of this invention. It is an enlarged plan view of the brush part 3 of the interdental brush 1 of FIG. FIG. 2 is a cross-sectional view taken along the line II of the interdental brush 1 of FIG. It is a top view of the primary product (base) 10. It is an enlarged cross-sectional view of the tip part of another example of the interdental brush of this invention. It is an enlarged plan view of the brush part 3 of the interdental brush 1 of FIG.

The definitions of the following terms apply throughout the specification and claims.
The “soft resin” means a resin having a shore A hardness of 90 or less as measured in accordance with JIS K 7215.
The “hard resin” means a resin having a higher shore A hardness than a soft resin, that is, a resin having a shore A hardness of more than 90.

<< First aspect >>
The interdental brush according to the first aspect of the present invention is an interdental brush including a grip portion and a brush portion provided at the tip of the grip portion.
The brush portion is a shaft material composed of a core portion made of a first synthetic resin extending from the grip portion and a coating portion formed by coating the core portion with a second synthetic resin softer than the first synthetic resin. And a plurality of projecting pieces projecting from the shaft member.

Hereinafter, an example of the interdental brush according to the first aspect of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the interdental brush 1 of the first embodiment of the present invention has a grip portion 2 made of a hard resin (first synthetic resin) whose diameter gradually decreases toward the tip side, and a grip portion 2. A brush portion 3 extending from the tip of the portion 2 is provided.
As shown in FIG. 2, the brush portion 3 includes a shaft member 4 extending from the tip of the grip portion 2 and a plurality of projecting pieces 5a to 5d (5) forming a brush member projecting from the shaft member 4. Be prepared.
As shown in FIG. 3, the shaft member 4 has a core portion 4a whose main material is a hard resin (first synthetic resin) extending from the tip of the grip portion 2, and a soft resin (second) that covers the core portion 4a. A coating portion 4b made of a synthetic resin) is provided. The projecting pieces 5 projecting radially from the axis of the shaft member 4 are made of a soft resin and are integrally formed with the covering portion 4b.

<Grip part>
The grip portion 2 is a member for gripping with a finger. The shape of the grip portion 2 of the present embodiment is not particularly limited as long as it can be gripped by a finger, and examples thereof include a plate shape, a columnar shape, a triangular columnar shape, and a square columnar shape.
For the purpose of making the grip portion 2 easy to hold with fingers, for example, the grip portion 2 may be formed with irregularities, holes, through holes, curves, or the like.

The grip portion 2 is formed with a reduced diameter portion 2a whose diameter is reduced toward the tip side, and a brush portion 3 is provided at the tip of the reduced diameter portion 2a.
When the reduced diameter portion 2a is provided, when the interdental brush 1 is used while checking with a mirror, the state of the brush portion 3 in the interdental portion can be easily visually recognized. Further, since the diameter-reduced portion 2a is gradually expanded toward the hand, the insertion into the interdental portion is likely to stop at the reduced-diameter portion 2a, and the interdental brush 1 can be prevented from being excessively inserted.

The range of the minimum diameter to the maximum diameter of the reduced diameter portion 2a is not particularly limited, and for example, 1 mm to 5 mm is preferable, 1.5 mm to 5 mm is more preferable, and 1.5 mm to 4 mm is further preferable.
When the minimum diameter is equal to or greater than the lower limit of the above range, the structural strength can be increased.
When the maximum diameter is equal to or less than the upper limit of the above range, handling in the mouth becomes easy.
The diameter of the reduced diameter portion 2a is the diameter of the cross section orthogonal to the reduced diameter direction (longitudinal direction of the brush portion). If the cross section is not circular, for example, rectangular, elliptical, or other polygonal, the diameter of the smallest circle including the cross-sectional shape is defined as the diameter of the reduced diameter portion 2a.

In the example of FIG. 1, the minimum diameter of the reduced diameter portion 2a is the diameter at the position indicated by the reference numeral “3a”. The position is the boundary between the brush portion 3 and the reduced diameter portion 2a. Here, the reference numeral "3a" is used as a reference numeral indicating the base end of the brush portion 3 for convenience. Further, the maximum diameter of the reduced diameter portion 2a is the same as the diameter R1 of the grip portion 2. The minimum diameter and the maximum diameter of the reduced diameter portion 2a do not include the thickness of the soft resin layer 6.

The width or diameter (thickness) R1 of the grip portion 2 is not particularly limited, and is preferably 5 mm to 10 mm, for example.
When the width or diameter is equal to or greater than the lower limit of the above range, the structural strength can be increased.
When the width or diameter is equal to or less than the upper limit of the above range, it becomes easy to handle when cleaning the mouth.

The constituent material of the grip portion 2 is not particularly limited, and a known material constituting the grip portion of the conventional interdental brush can be applied. The constituent material of the grip portion 2 is preferably a synthetic resin, and from the viewpoint of enhancing the integrity with the shaft member 4 extending from the tip of the grip portion 2, the constituent material of the core portion 4a of the shaft member 4 described in detail later It is preferable that they are the same. In the present embodiment, it is preferable that the grip portion and the shaft member are integrally formed.
The constituent material of the grip portion 2 may be one type or a composite material containing two or more types.

<Brush part>
As shown in FIG. 2, the brush portion 3 includes a shaft member 4 extending from the tip of the reduced diameter portion 2a of the grip portion 2 (the base end 3a of the brush portion 3). A plurality of first projecting pieces 5a to 4th projecting pieces 5d having various lengths are projected radially perpendicular to the axis of the shaft member 4. Each protruding piece is formed by a part of the soft resin forming the covering portion 4b of the shaft member 4 protruding from the surface of the covering portion 4b on the core portion 4a.

The soft resin covering the shaft member 4 extends from the base end 3a of the brush portion 3 onto the reduced diameter portion 2a to form the soft resin layer 6 covering a part of the reduced diameter portion 2a.

The shape of the shaft member 4 is not particularly limited as long as a plurality of projecting pieces 5 can be installed and can be inserted between teeth. Shapes such as shapes can be mentioned.
In the example of the present embodiment, the shape of the shaft member 4 is a columnar shape (that is, a truncated cone) whose diameter decreases toward the tip end. This makes it easier to insert the brush portion 3 between the teeth.

The length of the shaft member 4 is preferably 10 mm or more, more preferably 12 mm or more, and further preferably 13 mm or more in order to improve the cleaning efficiency between the teeth.
The upper limit of the length of the shaft member 4 is not particularly limited, and for example, when it is 20 mm or less, the operability in the mouth is improved, which is preferable. Therefore, the length of the shaft member 4 is preferably 10 to 20 mm, more preferably 12 to 20 mm, and even more preferably 13 to 20 mm.

The thickness of the shaft member 4 is not particularly limited, and for example, the area of the cross section orthogonal to the longitudinal direction of the portion 0.1 mm from the tip of the shaft member 4 is preferably 0.010 mm ^{2 to} 1.500 mm ² , more preferably. The thickness is preferably ^{0.030 mm 2 to} 1.200 mm ² , more preferably 0.060 mm ^{2 to} 0.800 mm ^2. Further, the area of the cross section orthogonal to the longitudinal direction of the base end portion of the shaft member 4 is preferably 0.200 mm ^{2 to} 3.140 mm ² , more preferably 0.380 mm ^{2 to} 2.540 mm ² , and further preferably 0. 500mm ² ~1.770mm ^2, become such thickness is preferable.
When the area of the cross section is equal to or larger than the above lower limit value, the rigidity of the shaft member 4 can be further increased.
When the area of the cross section is equal to or less than the above upper limit value, it becomes easier to insert the shaft member 4 into the narrow space between teeth, and the cleaning power can be enhanced.

The thickness of the shaft member 4 from the base end to the tip may be constant, or may be a tapered shape in which the diameter is reduced or increased toward the tip. In the case of the tapered shape, the angle (tapered angle) formed by the surface of the shaft member 4 with respect to the axis of the shaft member 4 is not particularly limited and may be constant, or may be changed gradually or stepwise.

[Strength of shaft material]
The shaft member 4 of the interdental brush 1 satisfies the following (A) to (C).
(A) Shaft bending strength; The repulsive force when the grip portion 2 is fixed and the portion 5 mm from the tip of the shaft member 4 is flipped at a speed of 10 mm / sec is 0.56 N or more.
(B) Shaft bending strength: The base end portion of the brush portion 3 is bent 90 degrees in the first direction orthogonal to the axis of the shaft member, returned to its original position, and 90 degrees in the second direction opposite to the first direction. In the left-right bending test of bending and returning to the original position, the number of times of bending in the same direction until the core portion 4a breaks is 20 times or more.
(C) Repeated bending strength: In a 90-degree bending test in which the base end portion of the brush portion 3 is bent 90 degrees in the first direction orthogonal to the axis of the shaft member and then returned to the original direction, the fifth time in the same direction. The maximum stress when bending to is 1.7 N or more.

(A) Axial bending strength is measured by the following test.
The center of the grip portion 2 of the interdental brush 1 is fixed by an arbitrary means, for example, a jig, and a grinder that moves at 10 mm / sec is slid on a portion 5 mm from the tip of the brush portion 3 of the interdental brush 1. , The resistance value (unit: N) when played is measured using the device used for the ISO 8627 method (interdental brush hardness standard). At this time, the measurement is performed so that the brush does not hit the region on the grip portion 2 side of the position 5 mm from the tip of the brush portion 3.

(B) Shaft bending strength is measured by the following left-right bending test.
First, the entire brush portion 3 excluding the base end 3a of the brush portion 3 of the interdental brush 1 is fixed by an arbitrary means, for example, a jig, and the grip portion 2 side is chucked at a distance of 5 mm from the fixed portion. I pinched it. As a result, there is an unfixed area (exposed area) of 5 mm between the jig and the chuck.
This unfixed region is a portion including the base end 3a of the brush portion 3 (base end portion of the brush portion 3). Here, the base end 3a of the brush portion 3 is the hem of the protruding piece 5 provided on the brush portion 3 on the grip portion 2 side closest to the grip portion 2 side, that is, the hairline of the protruding pieces 5 arranged in a row. ..
The base end portion of the brush portion 3 is bent 90 degrees in the first direction orthogonal to the axis of the shaft member 4 and returned to its original position. (That is, the brush portion 3 is bent 90 degrees at the base end portion and returned to the original position.) Here, the first direction is viewed in the axial direction in which the shaft member 4 extends, for example, in the depth direction of the paper surface of FIG. Can be a direction.
Subsequently, the base end portion is bent 90 degrees in the second direction opposite to the first direction and returned to its original position.
Here, the second direction is the direction opposite to the first direction and is orthogonal to the axis of the shaft member 4, for example, the right direction when viewed in the depth direction (axis direction) of the paper surface of FIG. Can be. This pair of left and right bends is counted as the number of times of one bend in this test.

The above pair of left and right bends are repeated in the same direction (in the same first direction and second direction) at 30 rpm (speed of 30 times per minute) until the core portion 4a of the shaft member 4 breaks. investigate. It is visually determined that the core portion 4a of the shaft member 4 is broken. After the core portion 4a of the shaft member 4 is broken, the broken tip end side and the base end side (grip portion 2 side) of the brush portion 3 may still be connected by the covering portion 4b. In this case, it can be seen that the fracture occurs because the force required for bending is extremely reduced. Further, by visually confirming that the coating portion 4b is peeled off and the core portion 4a is broken, it can be confirmed that the above judgment is correct.
It is assumed that the interdental brush that broke during the 20th bending before the completion of the 20th bending broke in less than 20 times.

(C) The repeated bending strength is measured by the following 90-degree bending test.
First, the center of the grip portion 2 of the interdental brush 1 is fixed by an arbitrary means, for example, a jig, and a pusher is applied to the base end 3a of the brush portion 3 of the interdental brush 1. Here, the position of the base end 3a of the brush portion 3 is the same position as in the case of (B) shaft bending strength. Subsequently, the tip side of the brush portion 3 from the base end 3a is bent 90 degrees in the first direction orthogonal to the axis of the shaft member 4 by a pusher, and then returned to the original position. Here, the first direction can be leftward when viewed in the axial direction in which the shaft member 4 extends, for example, in the depth direction of the paper surface of FIG. This 90-degree bend is counted as the number of times of one bend in this test.
The above left-right bending is repeated four times in the same direction (in the same first direction), and the maximum stress at the time of bending the fifth time in the same direction is measured by a push-pull gauge. Each bending is performed at a pressing speed of 80 mm / sec. The push-pull gauge is performed by using, for example, a popular digital force gauge D2D manufactured by Imada.

(A) The axial bending strength is 0.56 N or more, preferably 0.60 N or more, more preferably 0.65 N or more, and further preferably 0.70 N or more.
When it is at least the above lower limit value, the brush portion 3 of the interdental brush 1 has an appropriate rigidity, so that the interdental brush 1 can be easily inserted and removed. The upper limit is not particularly limited, and examples thereof include 1.00 N or less. Therefore, the axial bending strength is, for example, preferably 0.56 to 1.00N, more preferably 0.60 to 1.00N, further preferably 0.65 to 1.00N, and 0.70 to 1.00N. Is particularly preferable.
The shaft bending strength is adjusted by a combination of the type of synthetic resin constituting the shaft material 4, the type and amount of the fiber material, the thickness of the base end of the shaft material 4 (the base end 3a of the brush portion 3), and the like. ..

(B) The shaft bending strength is 20 times or more, preferably 100 times or more, more preferably 150 times or more, and further preferably 200 times or more.
When it is at least the above lower limit value, even if the brush portion 3 is temporarily bent during use or cleaning of the brush, it is difficult to break and the durability is excellent. The upper limit is not particularly limited, but for example, less than 10,000 times is appropriate.
The shaft bending strength is adjusted by a combination of the type of synthetic resin constituting the shaft material 4, the type and amount of the fiber material, the thickness of the base end of the shaft material 4 (the base end 3a of the brush portion 3), and the like.

(C) The repeated bending strength is 1.70 N or more, preferably 1.75 N or more, more preferably 1.80 N or more, and further preferably 1.85 N or more.
When it is at least the above lower limit value, after the brush portion 3 is bent during use or cleaning of the brush, it can be returned to the original state and used again, and the durability is excellent. The upper limit is not particularly limited, and examples thereof include 2.50 N or less. Therefore, the repeated bending strength is preferably 1.70 to 2.50 N, more preferably 1.75 to 2.50 N, further preferably 1.80 to 2.50 N, and 1.85 to 2.50 N. Especially preferable.
The repeated bending strength is adjusted by a combination of the type of synthetic resin constituting the shaft material 4, the type and amount of the fiber material, the thickness of the base end of the shaft material 4 (the base end 3a of the brush portion 3), and the like.

[Core of shaft material]
The constituent material of the core portion 4a of the shaft member 4 is not particularly limited, and it is preferable to include a synthetic resin as a main material from the viewpoint of realizing the strengths (A) to (C) above.
The synthetic resin is preferably at least one of a hard resin and a soft resin, and more preferably a hard resin.

The content of the synthetic resin is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, based on the total mass of the core portion 4a of the shaft member 4.
The content of the hard resin is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, based on the total mass of the core portion 4a of the shaft member 4.
The synthetic resin may be one kind or two or more kinds.

The type of the hard resin is not particularly limited, and a known hard resin can be applied. For example, a resin having a flexural modulus (JIS K7203) in the range of 500 to 3000 MPa can be used.
Examples of such a hard resin include polypropylene (PP), polytrimethylene terephthalate (PTT), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexylene methylene terephthalate (PCT), and polyacetal (POM). , Polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), cellulose propionate (CP), polyarylate, polycarbonate, acrylonitrile-styrene copolymer resin (AS) and the like. Among these, polyester having good adhesiveness to the soft resin constituting the covering portion 4b is preferable, and PTT and PBT are more preferable.

Any component other than the synthetic resin used as the main material may be added to the constituent material of the core portion 4a of the shaft member 4. Suitable optional components include, for example, fillers made of inorganic and / or organic materials. By adding the filler to the synthetic resin as a constituent material of the core portion 4a, the strengths of the core portions 4a (A) to (C) can be improved.

The constituent materials of the filler are not particularly limited, and examples thereof include inorganic materials such as glass, ceramics, minerals and carbon materials, and organic materials such as synthetic resins.
The synthetic resin constituting the filler may be the same as or different from the synthetic resin constituting the core portion 4a of the shaft member 4. Suitable synthetic resins include, for example, polyamides such as aramid and nylon.
Examples of the carbon material constituting the filler include carbon particles such as carbon black, carbon nanotubes, fullerenes, graphene and the like.
Examples of minerals and ceramics constituting the filler include mica, talc, silicon carbide, and titanium acid compounds.

The shape of the filler is not particularly limited, and may be any shape such as a fibrous shape, a particle shape, and a plate shape, and the fibrous shape is preferable because the strength of the above (A) to (C) can be easily improved.

The fiber length of the fibrous filler is not particularly limited, and for example, 3 μm to 300 μm is preferable, 6 μm to 100 μm is more preferable, and 9 μm to 50 μm is further preferable.
When the fiber length is at least the above lower limit value, the rigidity of the core portion 4a of the shaft member 4 can be further increased.
When the fiber length is not more than the above upper limit value, the toughness of the core portion 4a of the shaft member 4 can be further increased.
Here, the fiber length is an arithmetic mean of the fiber lengths (lengths from the front end to the rear end in the longitudinal direction of the fibers) of the 100 fibrous fillers. Therefore, the above fiber length can be read as the average fiber length. The fiber length of the fibrous filler is measured by electron microscopy.

The fiber diameter of the fibrous filler is not particularly limited, and for example, 0.1 μm to 2.0 μm is preferable, 0.2 μm to 1.0 μm is more preferable, and 0.3 μm to 0.8 μm is further preferable.
When the fiber diameter is at least the above lower limit value, the rigidity of the core portion 4a of the shaft member 4 can be further increased.
When the fiber diameter is not more than the above upper limit value, the toughness of the core portion 4a of the shaft member 4 can be further increased.
Here, the fiber diameter is an arithmetic mean of the fiber diameters of 100 fibrous fillers (the longest length in the direction orthogonal to the longitudinal direction of the fibers). Therefore, the above fiber diameter can be read as the average fiber diameter. The fiber diameter of the fibrous filler is measured by electron microscopy.

The content of the filler with respect to the total mass of the core portion 4a of the shaft member 4 is not particularly limited, and for example, 5 to 29% by mass is preferable, 10 to 25% by mass is more preferable, and 15 to 20% by mass is further preferable.
When the content is at least the above lower limit value, the rigidity of the core portion 4a of the shaft member 4 can be further increased.
When the content is not more than the upper limit value, the toughness of the core portion 4a of the shaft member 4 can be further enhanced.

The core portion 4a of the shaft material 4 may contain a synthetic resin as the main material and a fiber material having a fiber length of 3 μm to 300 μm and a fiber diameter of 0.1 μm to 2.0 μm as a filler of an optional component. preferable.

As the fiber material, potassium titanate fiber represented by _{the chemical formula K 2} Ti ₈ O ₁₇ or K ₂ Ti ₆ O _{13 is particularly suitable.} Such potassium titanate fibers are commercially available, and examples thereof include TISMO (registered trademark) manufactured by Otsuka Chemical Co., Ltd.

The flexural modulus measured in accordance with ASTM D790 (3-point load, method A), which is a constituent material of the core portion 4a, is 3.0 GPa or more from the viewpoint of realizing the strengths (A) to (C) above. Preferably, 4.0 GPa or more is more preferable, and 5.0 GPa or more is further preferable. The upper limit is not particularly limited, and for example, 20 GPa or less is appropriate.

The tensile elongation at break measured in accordance with ASTM D638 of the constituent material of the core portion 4a is preferably 7.0% or more, preferably 8.0% or more, from the viewpoint of realizing the strengths (A) to (C) above. Is more preferable, and 10.0% or more is further preferable. The upper limit is not particularly limited, and for example, 30% or less is appropriate.

As a preferable combination of the flexural modulus of the constituent material of the core portion 4a and the tensile elongation at break, any combination in the suitable range exemplified above can be mentioned. Specifically, for example, in the form of (numerical value of bending elasticity) and (numerical value of tensile elongation at break), 3.0 GPa or more and 7.0% or more, 3.0 GPa or more and 8.0% or more, 3.0 GPa or more and 10.0% or more, 4.0 GPa or more and 7.0% or more, 4.0 GPa or more and 8.0% or more, 4.0 GPa or more and 10.0% or more, 5.0 GPa or more and 7 Examples thereof include combinations of 0.0% or more, 5.0 GPa or more and 8.0% or more, 5.0 GPa or more and 10.0% or more. Among these, the strengths (A) to (C) above can be easily realized by using a constituent material having a flexural modulus of 3.0 GPa or more and a tensile elongation at break of 7.0% or more.

The constituent material of the core portion 4a is preferably a composite material containing a filler and a synthetic resin from the viewpoint of more easily realizing the strengths (A) to (C).

[Coating part of shaft material]
The constituent material of the covering portion 4b of the shaft member 4 is not particularly limited, and a soft resin is preferable. When the covering portion 4b is formed of a soft resin, the gingiva and teeth are less likely to be damaged when the brush portion 3 is inserted between the teeth, and the contact comfort is improved.
The shore hardness A (shore A hardness) of the soft resin constituting the covering portion 4b is preferably A90 or less, and more preferably A30 to A80. Suitable soft resins include known elastomer resins such as polyolefin-based elastomers, styrene-based elastomers, and polyester-based elastomers.
The soft resin constituting the covering portion 4b may be of one type or two or more types.
The covering portion 4b may cover the entire brush portion 3 or only a part thereof.

The thickness of the covering portion 4b is not particularly limited, and for example, 0.1 mm to 1.0 mm is preferable, 0.1 mm to 0.5 mm is more preferable, and 0.1 mm to 0.3 mm is further preferable.
When the thickness of the covering portion 4b is at least the lower limit value, it is possible to prevent the protruding piece 5 from falling off from the covering portion 4b and increase the structural strength of the brush portion 3.
When the thickness of the covering portion 4b is not more than the upper limit value, it is possible to prevent the entire diameter of the brush portion 3 from becoming too large, and to improve the insertability into narrow teeth.
As a method for measuring the thickness of the covering portion 4b, for example, in the brush portion 3, three or more locations are arbitrarily selected between the two adjacent protruding pieces 5, and the thickness of the soft resin at each location is measured with a microscope or a magnifying glass. A method of obtaining the measured value as an arithmetic mean can be mentioned.

[Protruding piece]
The shape and size of the protruding pieces 5 that project radially from the shaft member 4 when viewed from the axial direction in which the shaft member 4 extends are not particularly limited. As shown in FIG. 2, the brush portion 3 of the interdental brush 1 of the present embodiment is provided with a plurality of first protruding pieces 5a to fourth protruding pieces 5d having different heights from the surface of the shaft member 4. There is. These protruding pieces 5 are responsible for cleaning between the teeth and function as a brush material for scraping plaque.

The height of the protruding piece 5 is not particularly limited, and for example, 0.1 mm to 2.5 mm is preferable, 0.3 mm to 1.8 mm is more preferable, and 0.6 mm to 1.2 mm is further preferable. Here, the height of the protruding piece 5 means the length from the base end to the tip end on the surface side of the covering portion 4b.
When the height of the protruding piece 5 is at least the lower limit value, a high sweeping force can be easily obtained.
When the height of the protruding piece 5 is not more than the upper limit value, the brush portion 3 can be easily inserted between the teeth.
The relative heights of the plurality of projecting pieces 5 are not particularly limited, and may be the same as or different from each other.

The thickness (thickness) of the protruding piece 5 is not particularly limited, and for example, 0.1 mm to 1.5 mm is preferable, 0.1 mm to 0.5 mm is more preferable, and 0.1 mm to 0.2 mm is further preferable. Here, the thickness of the protruding piece 5 means the maximum diameter of the cross section orthogonal to the direction in which the protruding piece 5 is protruding.
When the thickness of the protruding piece 5 is at least the lower limit value, it can be easily molded by injection molding, and the rigidity required for scraping plaque can be easily obtained.
When the thickness of the protruding piece 5 is not more than the upper limit value, the brush portion 3 can be easily inserted between the teeth.
The relative thicknesses of the plurality of projecting pieces 5 are not particularly limited and may be the same or different from each other.

In the interdental brush 1 shown in FIG. 3, the projecting pieces 5 are provided so as to project radially in four directions at equal intervals of 90 ° around the axis of the shaft member 4.
The number of projecting pieces 5 projecting radially when viewed from the extending direction of the shaft member 4 is not particularly limited, and for example, it is preferable that 2 to 6 projecting pieces radially around the axis at equal intervals.

The front view shape of the protruding piece 5 when viewed from the extending direction of the shaft member 4 is not particularly limited. For example, as shown in FIG. 3, the height direction from the shaft member 4 is a rectangle longer than the width direction, and the protrusion piece 5 is rectangular. A shape in which both corners on the tip side are rounded can be mentioned. Other examples of the front view shape include a trapezoidal shape, a square shape, a rectangular shape, and a substantially elliptical shape whose width becomes narrower toward the tip.

The distance between the protruding pieces 5 adjacent to each other when viewed in the axial direction in which the shaft member 4 constituting the brush portion 3 extends is not particularly limited, and is preferably 0.3 mm to 0.8 mm, for example.
When the distance is equal to or greater than the lower limit value, it becomes easy for each protruding piece 5 to function independently.
When the distance is not more than the upper limit value, plaque is easily held between the protruding pieces, and a high sweeping force is easily obtained.

The total number of projecting pieces 5 arranged in a row in the axial direction in which the shaft member 4 extends in the brush portion 3 is not particularly limited, and for example, 10 to 100 pieces are preferable, and 20 to 50 pieces are more preferable.
When the total number is equal to or greater than the lower limit, a sufficient sweeping force can be easily obtained.
When the total number is not more than the upper limit value, both insertion and removal into and out of the teeth are facilitated, and the workability for cleaning the teeth is improved.

<Manufacturing method>
The method for producing the interdental brush of the present invention is not particularly limited, and a known production method can be applied. For example, by injection molding using a mold, first, a primary product (base) 10 in which the core portion 4a of the shaft member 4 and the grip portion 2 are integrally molded is obtained (see FIG. 4). Subsequently, a part of the core portion 4a and the reduced diameter portion 2a is covered with a soft resin to form a brush portion 3 in which the covering portion 4b and the protruding piece 5 are integrally molded, and a part of the reduced diameter portion 2a is formed. Is coated with the soft resin layer 6 (see FIG. 1). The interdental brush 1 can be manufactured by such known injection molding.

In the preparation of the composite material constituting the shaft member 4, when an arbitrary component such as a filler is mixed with the synthetic resin, the mixing method is not particularly limited, and for example, a stirrer, a stirrer, a ball mill, a rotation mixer, an ultrasonic dispersion. A known method using a machine or the like is applied.

<Effect>
The interdental brush of the present invention has excellent durability because the shaft material constituting the brush portion satisfies the above-mentioned (A) to (C), is prevented from breaking during use, and is washed and used repeatedly. can do.
Since at least the brush portion of the interdental brush of the present invention is made of synthetic resin, it is less likely to feel pain when it hits the gums or the like as compared with a conventional interdental brush provided with a metal wire, and the hitting comfort is good. be.

<Other Embodiments>
The interdental brush of the present invention is not limited to the interdental brush 1 of the first embodiment described above.
For example, as shown in FIG. 5, an interdental brush in which the tip portion 4c of the shaft member 4 is spherical can be mentioned. According to the interdental brush, the pain when the tip portion 4c of the shaft member 4 hits the gingiva is further reduced, and a more comfortable hitting feeling can be obtained. The spherical tip portion 4c is preferably made of a soft resin.

<< Second aspect >>
The interdental brush of the second aspect of the present invention is an interdental brush made of synthetic resin including a grip portion and a brush portion provided at the tip of the grip portion. Hereinafter, an example of the interdental brush of the present invention will be described in detail with reference to the drawings.
The shape of the interdental brush of the second aspect can be described with reference to FIGS. 1 to 5 used in the description of the interdental brush of the first aspect. Therefore, in the following description, the same reference numerals are given to the members common to the first aspect with reference to FIGS. 1 to 6.
The interdental brush 1 of the second aspect is made of synthetic resin and includes a grip portion 2 and a brush portion 3 provided at the tip of the grip portion 2 as shown in FIG.

(Grip part)
The grip portion 2 is a columnar member for gripping with a finger.
In this example, the shape of the grip portion 2 is a flat plate shape.
The shape of the grip portion 2 may be any shape that can be gripped by a finger, and a columnar shape, a columnar shape (triangular columnar shape, a square columnar shape, etc.) or the like may be adopted in addition to the flat plate shape described above.

The grip portion 2 of this example is provided with a diameter-expanding portion 2a that increases in diameter from the front end to the rear end toward the brush portion 3. As a result, even if the interdental brush 1 is erroneously pushed strongly in the axial direction while the brush portion 3 is inserted between the teeth, the insertion into the interdental portion is stopped at the enlarged diameter portion 2a. It is easy to suppress damage to the oral cavity.

The material for forming the grip portion 2 is not particularly limited, and a known material for forming the grip portion of the interdental brush can be used, and examples thereof include the same materials as those mentioned in the shaft member 4 described later.
The material forming the grip portion 2 may be one type or two or more types.

(Brush part)
The brush portion 3 includes a shaft member 4 extending from the tip of the grip portion 2 and a first protruding piece 5a to a fourth protruding piece 5d protruding from the shaft member 4. The first protruding piece 5a to the fourth protruding piece 5d are integrally formed with the covering portion 4b of the shaft member 4 described later.

The shaft member 4 is a columnar member extending from the tip of the grip portion 2. As the shaft member 4, a columnar shape, a triangular columnar shape, a square columnar shape, or the like may be adopted. Further, the shaft member 4 may have a reduced diameter toward the tip, and may form, for example, a truncated cone. This makes it easier to insert the brush portion 3 between the teeth.
As shown in FIG. 3, the shaft member 4 includes a core portion 4a extending from the tip of the grip portion 2 and a covering portion 4b covering the surface of the core portion 4a.

As the material for forming the shaft member 4, a hard resin is preferable, and among them, a resin having a flexural modulus of 500 to 3000 MPa measured in accordance with JIS K7203 is preferable. Specific examples are the same as described above.

A soft resin is preferable as the material for forming the covering portion 4b. By forming the covering portion 4b with a soft resin, the gingiva and the like are less likely to be damaged when the brush portion 3 is inserted between the teeth, and the contact comfort is improved.
Examples of the soft resin include elastomer resins such as polyolefin-based elastomers, styrene-based elastomers, and polyester-based elastomers.

The thickness of the covering portion 4b is preferably 0.1 to 0.5 mm, more preferably 0.1 to 0.3 mm. When the thickness of the covering portion 4b is at least the lower limit value, it is easy to fill the soft resin up to the tip of the protruding piece. When the thickness of the covering portion 4b is not more than the upper limit value, the insertability into the inter-teeth can be improved. The method for measuring the thickness of the covering portion 4b is as described above.

As shown in FIG. 6, the brush portion 3 has a region (A) 14 formed closer to the rear end than the region (B) 17 and a region (B) formed closer to the tip side than the region (A) 14. 17 and is included. The region (A) 14 includes a region (A1) 12 on the distal end side and a region (A2) 13 on the posterior end side of the region (A1) 12. The region (B) 17 includes a region (B1) 15 on the distal end side and a region (B2) 16 on the posterior end side of the region (B1) 15. As described above, the brush portion 3 is formed with the region (B1) 15, the region (B2) 16, the region (A1) 12, and the region (A2) 13 in this order from the front end to the rear end.

[Area (A)]
The region (A) 14 is a region in the brush portion 3 that greatly contributes to the development of the sweeping force between the teeth.
In the region (A) 14, a plurality of first projecting pieces 5a having an arbitrary height are arranged in the axial direction. In the region (A1) 12 on the distal end side of the region (A) 14, the first protruding piece 5a having an arbitrary height and the second protruding piece 5b having a height lower than that of the first protruding piece 5a are axially arranged. They are lined up alternately. In the rear end side region (A2) 13, only the first protruding pieces 5a having an arbitrary height are aligned in the axial direction.
When the region (A) consists of the region (A1) and the region (A2), the boundary between the region (A1) and the region (A2) in the axial direction of the shaft member is determined so that the region (A2) is the widest. Shall be. Specifically, in this example, the region (A1) 12 is a region from the second protruding piece 5b on the rearmost end side to the first protruding piece 5a on the most advanced side. The region (A2) 13 is a region from the first protruding piece 5a located adjacent to the rear end side of the second protruding piece 5b on the rearmost end side to the first protruding piece 5a on the rearmost end side.

<First protruding piece>
The first protruding piece 5a is a plate-shaped member for scraping plaque or the like existing between teeth. The plate-shaped projecting piece has a high effect of scraping plaque and the like.

As shown in FIG. 3, the first protruding piece 5a is viewed from the extending direction of the shaft member 4 so that the flat surface portion of the first protruding piece 5a (protruding piece 5) is orthogonal to the axial direction of the shaft member 4. It is provided so as to project radially. In the example of FIG. 3, when viewed from the extending direction, the shaft member 4 is provided with the first protruding pieces 5a around the shaft of the shaft member 4 at intervals of 90 ° in each of the four directions. That is, four first projecting pieces 5a are provided so as to project in the x-axis direction and the y-axis direction orthogonal to the x-axis direction in the plane orthogonal to the shaft member 4. It is preferable that the first protruding pieces 5a are provided around the shaft of the shaft member 4 at equal intervals in this way.

The number of the first projecting pieces 5a projecting radially when viewed from the extending direction of the shaft member 4 is four in the example of FIG. 3, but is not limited to four, and may be three or less. Often, there may be five or more. It is preferable that at least two first projecting pieces 5a project radially when viewed from the extending direction of the shaft member 4.
The plurality of first protruding pieces 5a projecting radially when viewed from the extending direction of the shaft member 4 are formed at equal intervals with each other, and are formed with a line connecting the center line of each first protruding piece 5a and the center of the shaft member 4. It is preferable that all the angles formed by the eggplants are formed equally. On the other hand, the plurality of first protruding pieces 5a are formed at non-equal intervals with each other, and the angles formed by the center of each first protruding piece 5a and the line connecting the center of the shaft member 4 are formed so as to be different from each other. It doesn't matter.

The front view shape of the first protruding piece 5a in the example of FIG. 3 is a rectangle whose height direction from the shaft member 4 is longer than the width direction, and both corners on the tip side thereof are rounded. ing. The front view shape of the first protruding piece 5a is not limited to the shape of the present embodiment, and is, for example, a trapezoidal shape, a square shape, a rectangular shape, a substantially elliptical shape whose width becomes narrower toward the tip, and the like. May be good.

The height of the first protruding piece 5a from the shaft member 4 is the highest among the protruding pieces provided in the brush portion 3. The first protruding piece 5a provided in the region (A) 14 provides a high sweeping force.
The height of the first protruding piece 5a is preferably 0.7 to 1.5 mm, more preferably 0.7 to 1.2 mm. When the height of the first protruding piece 5a is at least the lower limit value, a high sweeping force can be easily obtained. When the height of the first protruding piece 5a is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.
It is preferable that the heights of the individual first protruding pieces 5a of the brush portion 3 are all the same, but the heights may be non-uniform due to manufacturing reasons. This degree of non-uniformity is acceptable if it is ± 0.05 mm or less, and is considered to be the same height.
The height of each protruding piece (protruding piece 5a to 5d) formed on the brush portion 3 is viewed from the shaft member 4 in the extending direction (axis direction) of the shaft member 4 using a microscope or a magnifying glass. Obtained by measuring the height.

The thickness of the first protruding piece 5a is preferably 0.1 to 0.2 mm, more preferably 0.10 to 0.15 mm. If the thickness of the first protruding piece 5a is at least the lower limit, it can be easily molded by injection molding. When the thickness of the first protruding piece 5a is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.
It is preferable that the thicknesses of the individual first protruding pieces 5a of the brush portion 3 are all the same, but the thickness may be non-uniform due to manufacturing reasons. This non-uniformity is acceptable as long as it is ± 0.05 mm or less.
The thickness of each protruding piece (protruding pieces 5a to 5d) formed on the brush portion 3 is orthogonal to the extending direction (center line direction) of each protruding piece using a microscope or a magnifying glass. It is obtained by measuring the diameter of the smallest circle including the cross section.

<Second protruding piece>
The second protruding piece 5b is a plate-shaped member for scraping plaque and the like existing between the teeth, and the height from the shaft member 4 is 0.1 mm or more lower than the height of the first protruding piece 5a. It is a thing.
It is preferable that the heights of the individual second protruding pieces 5b of the brush portion 3 are all the same, but the heights may be non-uniform due to manufacturing reasons. This degree of non-uniformity is acceptable if it is ± 0.05 mm or less, and is considered to be the same height.
The mode in which the second protruding piece 5b is provided on the shaft member 4 is the same as in the case of the first protruding piece 5a, and the preferred mode is also the same. The number of the second protruding pieces 5b protruding radially from the extending direction of the shaft member 4 is the same as the number of the first protruding pieces 5a protruding radially from the extending direction of the shaft member 4. It may be different.

The front view shape of the second protruding piece 5b in this example is the same as that of the first protruding piece 5a except that the height from the shaft member 4 is 0.1 mm or more lower than that of the first protruding piece 5a, and the tip side of the rectangle. Both corners of are rounded.
The front view shape of the second protruding piece 5b may be trapezoidal, square, rectangular, substantially elliptical in width toward the tip, or the like.

The height of the second protruding piece 5b is preferably 0.3 to 0.7 mm, more preferably 0.3 to 0.5 mm, in a range of 0.1 mm or more lower than the height of the first protruding piece 5a. When the height of the second protruding piece 5b is equal to or greater than the lower limit value, a high sweeping force can be easily obtained. When the height of the second protruding piece 5b is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.

The thickness of the second protruding piece 5b is preferably 0.1 to 0.2 mm, more preferably 0.10 to 0.15 mm. If the thickness of the second protruding piece 5b is at least the lower limit, it can be easily molded by injection molding. When the thickness of the second protruding piece 5b is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.

<Area (A1)>
In the region (A1) 12, the first protruding piece 5a and the second protruding piece 5b having a height lower than that of the first protruding piece 5a are alternately arranged in the axial direction, so that when the first protruding piece 5a is inserted between the teeth. Even if the first protruding piece 5a falls down, the overlap between the first protruding pieces 5a becomes small because the second protruding piece 5b having a low height is adjacent to the first protruding piece 5a. As a result, the thickness of the outer periphery of the brush portion 3 including the first protruding piece 5a when the state in which the first protruding piece 5a is tilted in the region (A1) 12 is viewed from the extending direction of the shaft member 4 is the first. It is thinner than the case where only the protruding pieces 5a are lined up at the same interval. Therefore, since the region (A1) 12 is provided, it becomes easy to insert the brush portion 3 between the teeth.
As described above, the region (A1) 12 has a sufficient cleaning force due to the first protruding piece 5a, and the insertability into the inter-teeth is enhanced.

In the region (A1) 12 of the example of FIG. 6, in the mode in which the first protruding piece 5a and the second protruding piece 5b are arranged side by side, the first protruding piece 5a and the second protruding piece 5b are alternately arranged in the axial direction. For example, the arrangement of the shaft members 4 around the shaft is not particularly limited. That is, if the first protruding piece 5a and the second protruding piece 5b alternate in the axial direction, all the protruding pieces arranged around the axis of the shaft member 4 are the first protruding piece 5a or the second protruding piece 5b. The first protruding piece 5a and the second protruding piece 5b may be mixed.
In the examples of FIGS. A set in which four second projecting pieces 5b project in the direction are arranged alternately in the axial direction. In addition to these aspects, for example, a set in which two first projecting pieces 5a project in the x-axis direction around the axis of the shaft member 4 and two second projecting pieces 5b project in the y-axis direction, and a shaft member. A set in which two second projecting pieces 5b project in the x-axis direction around the axis of 4 and two first projecting pieces 5a project in the y-axis direction are arranged alternately in the axial direction. May be good.
The state in which the two projecting pieces are alternately arranged in the axial direction means a state in which the projecting piece on the front side appears to overlap with at least a part of the projecting piece on the back side when viewed in the axial direction.

The axial distance between the adjacent first protruding piece 5a and the second protruding piece 5b in the region (A1) 12 is preferably 0.3 to 0.8 mm, which is the same length as the height of the second protruding piece 5b. Is more preferable. When the distance is not less than the lower limit value, the overlap between the first protruding piece 5a and the second protruding piece 5b is relatively relaxed, and the insertability into the teeth is likely to be enhanced. When the distance is not more than the upper limit value, it becomes easy to hold the plaque between the first protruding piece 5a and the second protruding piece 5b, and it is easy to obtain a high sweeping force.

The total number of the first protruding pieces 5a and the second protruding pieces 5b arranged in the axial direction in the region (A1) 12 is 16 in the example of FIG. The total number is preferably 4 to 30, more preferably 10 to 20. When the total number of the first projecting piece 5a and the second projecting piece 5b is within the above range, the function of both the insertability of the region (A1) 12 and the sweeping force can be sufficiently exhibited.

<Area (A2)>
In the region (A2) 13, since only the first protruding piece 5a is aligned in the axial direction, the force for scraping plaque and the like is strong, and a high sweeping force can be obtained.

The axial distance between the adjacent first protruding pieces 5a in the region (A2) 13 is preferably 0.3 to 1.5 mm, more preferably 0.5 to 0.8 mm. When the distance is at least the lower limit value, the overlap between the first protruding pieces 5a is relatively relaxed, and the insertability into the teeth is likely to be enhanced. When the distance is not more than the upper limit value, it is easy to hold the plaque between the first protruding pieces 5a, and it is easy to obtain a high sweeping force.

The number of the first projecting pieces 5a arranged in the axial direction in the region (A2) 13 is 8 in this example.
The number of the first projecting pieces 5a arranged in the axial direction in the region (A2) 13 is preferably 3 to 30, more preferably 5 to 20. When the number of the first protruding pieces 5a is within the above range, the high sweeping force of the region (A2) 13 is likely to be sufficiently exerted.

In the present invention, in the region (A), it is preferable that the axial distance between the protruding pieces of an arbitrary height (for example, 0.5 to 2.0 mm) increases toward the tip. As a result, the tip end side of the region (A) is easily inserted between the teeth.
For example, in the example of FIG. 6, the axial distance between the first protruding pieces 5a in the region (A1) 12 is 0.1 mm or more than the axial distance between the first protruding pieces 5a in the region (A2) 13. It's getting bigger. As a result, even if the first protruding piece 5a falls down when the region (A) 14 of the brush portion 3 is inserted between the teeth, the region (A1) 12 on the tip side has the first region (A2) 13 as compared with the region (A2) 13. The protruding pieces 5a do not easily overlap.
Therefore, when viewed from the extending direction of the shaft member 4, the thickness of the region (A1) 12 where the distance between the first protruding pieces 5a is large is smaller than that of the region (A2) 13, and the first protruding pieces 5a are inserted into the teeth. Sex improves.

[Area (B)]
The region (B) 17 is a region that has a sweeping force and contributes to the improvement of insertability when the brush portion 3 is inserted between the teeth.
In the region (B1) 15 on the distal end side of the region (B) 17, only the third protruding piece 5c whose height from the shaft member 4 is 0.1 mm or more lower than that of the first protruding piece 5a is aligned in the axial direction. .. In the rear end side region (B2) 16 of the region (B) 17, only the fourth protruding piece 5d whose height from the shaft member 4 is 0.1 mm or more lower than that of the first protruding piece 5a is arranged in the axial direction. There is. That is, in the region (B) 17, only the protruding pieces whose height is 0.1 mm or more lower than that of the first protruding piece 5a are lined up in the axial direction. Further, the height of the fourth protruding piece 5d of the region (B2) 16 from the shaft member 4 is equal to or less than the height of the second protruding piece 5b in the region (A1) 12. The height of the third protruding piece 5c of the region (B1) 15 from the shaft member 4 is 0.1 mm or more lower than the height of the fourth protruding piece 5d of the region (B2) 16.
As described above, the area (B1) 15, the area (B2) 16, the area (A1) 12 and the area (A2) 13 in the brush portion 3 are gradually expanded in diameter as a whole.
When the region (B) 17 is composed of the region (B1) 15 and the region (B2) 16, the region (B2) 16 is the most boundary between the region (B1) 15 and the region (B2) 16 in the axial direction of the shaft member. It shall be decided to be wide. Specifically, in this example, the region (B1) 15 is a region from the third protruding piece 5c on the rearmost end side to the third protruding piece 5c on the most distal end side. The region (B2) 16 is a region from the fourth protruding piece 5d on the most distal end side to the fourth protruding piece 5d on the rearmost end side.

<Third protruding piece, fourth protruding piece>
The third protruding piece 5c and the fourth protruding piece 5d are plate-shaped members for scraping plaque and the like existing between the teeth, and the height from the shaft member 4 is higher than the height of the first protruding piece 5a. Is also lower than 0.1 mm. The height of the third protruding piece 5c from the shaft member 4 is 0.1 mm or more lower than the height of the fourth protruding piece 5d.
It is preferable that the heights of the individual third protruding pieces 5c of the brush portion 3 are all the same, but the heights may be non-uniform due to manufacturing reasons. This degree of non-uniformity is acceptable if it is ± 0.05 mm or less, and is considered to be the same height.
It is preferable that the heights of the individual fourth protruding pieces 5d of the brush portion 3 are all the same, but the heights may be non-uniform due to manufacturing reasons. This degree of non-uniformity is acceptable if it is ± 0.05 mm or less, and is considered to be the same height.

The mode in which the third protruding piece 5c and the fourth protruding piece 5d are provided on the shaft member 4 is the same as in the case of the first protruding piece 5a, and the preferred mode is also the same. The number of the third protruding pieces 5c protruding radially from the extending direction of the shaft member 4 is the same as the number of the fourth protruding pieces 5d protruding radially from the extending direction of the shaft member 4. It may be different.

The front view shape of the third protruding piece 5c and the fourth protruding piece 5d in this example is the same as that of the first protruding piece 5a except that the height from the shaft member 4 is 0.1 mm or more lower than that of the first protruding piece 5a. Yes, both corners on the tip side of the rectangle have a rounded shape.
The front view shape of the third protruding piece 5c and the fourth protruding piece 5d may be a trapezoidal shape, a square shape, a rectangular shape, a substantially elliptical shape whose width becomes narrower toward the tip, or the like.

The height of the third protruding piece 5c is preferably 0.1 to 0.5 mm, more preferably 0.1 to 0.3 mm, in a range of 0.1 mm or more lower than the height of the fourth protruding piece 5d. When the height of the third protruding piece 5c is at least the lower limit value, it is easy to obtain a feeling of actual printing by the protruding piece. When the height of the third protruding piece 5c is equal to or less than the upper limit value, the insertability of the brush portion 3 between the teeth becomes higher.

The thickness of the third protruding piece 5c may be the same as that of the first protruding piece 5a or the second protruding piece 5b, or may be thicker than that. However, the upper limit is preferably 1.5 mm. When the thickness of the third protruding piece 5c is not more than the upper limit value, a high sweeping force can be easily obtained.

The height of the fourth protruding piece 5d is 0.3 to 0.7 mm in a range of 0.1 mm or more lower than the height of the first protruding piece 5a and 0.1 mm or more higher than the height of the third protruding piece 5c. Is preferable, and 0.3 to 0.5 mm is more preferable. If the fourth projecting piece 5 d height than the lower limit of a high printing掃力is easily obtained. When the height of the fourth protruding piece 5 d is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.

The thickness of the second protruding piece 5b is preferably 0.1 to 0.2 mm, more preferably 0.10 to 0.15 mm. If the thickness of the second protruding piece 5b is at least the lower limit, it can be easily molded by injection molding. When the thickness of the second protruding piece 5b is equal to or less than the upper limit value, the brush portion 3 can be easily inserted between the teeth.

<Region (B1), Region (B2)>
Since the region (B) 17 includes only the protruding pieces that are 0.1 mm or more lower than the first protruding piece 5a, the region (B) 17 is compared to the region (A) 14 when viewed from the extending direction of the shaft member 4. B) The thickness of 17 becomes thinner. Therefore, the region (B) 17 is easier to insert between the teeth than the region (A) 14. Since the region (B) 17 on the tip end side of the brush portion 3 is easily inserted between the teeth, the subsequent region (A) 14 can be stably inserted between the teeth.
Further, in the region (B2) 16, only the fourth protruding piece 5d, which is 0.1 mm or more lower in height than the first protruding piece 5a of the region (A) 14, is aligned in the axial direction. The height of the third protruding piece 5c arranged in the region (B1) 15 is 0.1 mm or more lower than the height of the fourth protruding piece 5d arranged in the region (B2) 16. As a result, the tip of the brush portion 3 is thinner, so that the region (B) 17 can be inserted into the teeth as compared with the embodiment in which only the fourth protruding piece 5d is lined up in the entire region (B) 17. Is even higher.

The number of the third projecting pieces 5c arranged in the axial direction in the region (B1) 15 is 3 in the example of FIG. The number of the third projecting pieces 5c arranged in the axial direction in the region (B1) 15 is preferably 1 to 15, and more preferably 1 to 10. When the number of the third protruding pieces 5c is within the above range, the function of assisting the interdental insertability of the region (B1) 15 is likely to be sufficiently exhibited.

The number of the fourth projecting pieces 5d arranged in the axial direction in the region (B2) 16 is 5 in this example. The number of the fourth projecting pieces 5d arranged in the axial direction in the region (B2) 16 is preferably 1 to 20, more preferably 3 to 10. When the number of the fourth protruding pieces 5d is within the above range, the function of enhancing the interdental insertability of the region (B2) 16 is likely to be sufficiently exhibited.

From the viewpoint of enhancing the interdental insertability and the sweeping force of the interdental brush 1, the following can be exemplified as suitable lengths of each region of the brush portion 3.
The length from the tip of the brush portion 3 to the last protruding piece 5 on the rear end side is preferably 10 to 20 mm, for example.
The total length of the region (A) 14 and the region (B) 17 is preferably 10 to 20 mm, and the length ratio represented by the region (A) 14 / region (B) 17 is 1/10 to 5/10. Is preferable.
The length ratio represented by the region (A1) 12 / region (A2) 13 in the region (A) 14 is preferably 3/1 to 1/3.
The length ratio represented by the region (B1) 15 / region (B2) 16 in the region (B) 17 is preferably 1/1 to 1/3.

(Production method)
As the method for manufacturing the interdental brush according to the second aspect of the present invention, a known manufacturing method can be adopted except that the height relationship of the protruding pieces arranged in the axial direction is adjusted as described above. In the case of the interdental brush 1, for example, the gold such that the first protruding piece 5a to the fourth protruding piece 5d form the above-mentioned region (A1), region (A2), region (B1) and region (B2). An example is a method of performing injection molding using a mold.

(Action effect)
In the interdental brush of the second aspect of the present invention described above, since the region (B) is provided on the tip end side of the brush portion and the region (A) is provided on the rear end side, a high sweeping force is obtained. It is possible to achieve both insertability between teeth. Further, since the interdental brush of the second aspect of the present invention is made of synthetic resin, it is less likely to feel pain even when it hits the gingiva or the like as compared with an interdental brush provided with a wire, and the hitting comfort is good.

The interdental brush of the second aspect of the present invention is not limited to the above-mentioned interdental brush 1. For example, the interdental brush of the second aspect of the present invention may be an interdental brush in which the region (A) is composed of only the region (A1), or the interdental brush in which the region (A) is composed of only the region (A2). It may be. Further, the interdental brush according to the second aspect of the present invention may be an interdental brush in which the region (B) is composed of only the region (B1), and the interdental brush in which the region (B) is composed of only the region (B2). It may be.
When the region (B) consists of the region (B1) and the region (B2), the protruding piece of the region (B1) has a height equal to or less than the fourth protruding piece of the region (B2), and the region (B1) has a third. 4 It suffices to include a third protruding piece having a height lower than that of the protruding piece. For example, the region (B1) may include both a third protruding piece and a fourth protruding piece. Specifically, in the region (B1), protrusions having the same height as the protrusions of the region (B2) and protrusions having a height lower than that of the protrusions of the region (B2) are alternately arranged in the axial direction. It may be an area.

Further, as shown in FIG. 5, the interdental brush of the present invention may be an interdental brush in which the tip portion 4c of the shaft member 4 is spherical. The interdental brush is less likely to feel pain even when the tip portion 4c of the shaft member 4 hits the gingiva, and the hitting comfort is better. In this case, the spherical tip portion 4c is preferably made of a soft resin.

The configuration of the interdental brush of the second aspect described above can be applied as the configuration of the interdental brush of the first aspect described above.

[Example 1]
The interdental brush 1 of the first embodiment was manufactured as follows.
Using a material obtained by mixing 85 parts by mass of polybutylene terephthalate (PBT) and 15 parts by mass of potassium titanate fiber (manufactured by Otsuka Chemical Co., Ltd., TISMO (registered trademark)), the core portion 4a of the shaft member 4 and the diameter reduction The grip portion 2 including the portion 2a was integrally injection-molded using a mold having a corresponding shape.
The length from the tip 4p to the base end 4q of the core portion 4a of the shaft member 4 that decreases in diameter toward the tip is 12.0 mm, and the thickness of 0.1 mm from the tip is φ0.32 mm (0.080 mm ² ). The thickness of 12.0 mm from the tip was φ0.92 mm (0.664 mm ² ).
Next, by injection molding using a mold, a part of the surface of the core portion 4a and the reduced diameter portion 2a is coated with a thickness of 0.15 mm, and the covering portion 4b and the soft resin layer 6 are covered. Formed. At this time, a plurality of protruding pieces 5 were integrally formed with the covering portion 4b to obtain an interdental brush 1.
The length of the brush portion 3 of the manufactured interdental brush 1 was 12.0 mm from the tip (tip 4c of the shaft member 4) to the base end 3a.

Table 1 shows the results of measuring the flexural modulus and tensile elongation at break of the materials constituting the core portion 4a of the shaft member 4 of this embodiment in accordance with ASTM D790 and ASTM D638, respectively.
Table 1 shows the results of measuring the intensities of (A) to (C) for the interdental brush 1 of this example by the test method described above.
The results shown in Table 1 are average values of the results of measuring and testing the five interdental brushes 1.

[Example 2]
An interdental brush was manufactured in the same manner as in Example 1 except that a material obtained by mixing 80 parts by mass of PBT and 20 parts by mass of TISMO was used.
[Comparative Example 1]
An interdental brush was manufactured in the same manner as in Example 1 except that a material obtained by mixing 70 parts by mass of PBT and 30 parts by mass of TISMO was used.
[Comparative Example 2]
An interdental brush was manufactured in the same manner as in Example 1 except that 100 parts by mass of PBT was used and a material not mixed with TISMO was used.
[Comparative Example 3]
An interdental brush was produced in the same manner as in Example 1 except that a material obtained by mixing 92.5 parts by mass of PBT and 7.5 parts by mass of glass fiber was used.
Table 1 shows the results of each physical property measured in the same manner as in Example 1 for the above Examples and Comparative Examples.

Details of the raw materials used to manufacture each interdental brush are as follows.
The fiber length of TISMO is 10 to 20 μm, and the fiber diameter is 0.3 to 0.6 μm.
The fiber length of the glass fiber is 200 to 300 μm, and the fiber diameter is 10 to 20 μm.

[Evaluation of durability]
Each of the interdental brushes produced in the above Examples and Comparative Examples was used by 10 panels for one week, and their durability was evaluated. When 6 or more panels damage the brush part of the interdental brush after 1 week of use, the durability is evaluated as low (x), and when 6 or more panels can continue to use the brush without damaging it. Was evaluated as having high durability (○). The results are shown in Table 1.

From the results shown in Table 1, the interdental brushes of Examples 1 and 2 satisfying the strength criteria of (A) to (C), having a flexural modulus of 3.0 GPa or more and a tensile elongation at break of 7.0% or more. Is clearly excellent in durability.

1 Interdental brush 2 Grip part 2a Diameter reduction part (diameter expansion part)
3 Brush part 3a Base end of brush part 4 Shaft material 4a Core part 4b Covering part 4c Tip part 4p Tip of core part 4q Base end of core part 5 Protruding piece 5a First protruding piece (first protruding piece)
5b Second protruding piece (second protruding piece)
5c Third protruding piece (third protruding piece)
5d 4th protruding piece (4th protruding piece)
6 Soft resin layer coated on the reduced diameter part 10 Primary product (base)
14 areas (A)
17 area (B)
12 areas (A1)
13 areas (A2)
15 areas (B1)
16 areas (B2)

Claims (4)

An interdental brush including a grip portion and a brush portion provided at the tip of the grip portion.
The brush portion is a shaft material composed of a core portion made of a first synthetic resin extending from the grip portion and a coating portion formed by coating the core portion with a second synthetic resin softer than the first synthetic resin. And a plurality of projecting pieces projecting from the shaft member.
The first synthetic resin contains a fibrous filler having a fiber length of 9 μm to 300 μm and a fiber diameter of 0.1 μm to 2.0 μm.
The fibrous filler is at least one of an inorganic material fiber and an organic material fiber.
The content of the fibrous filler is 5 to 29% by mass with respect to the total mass of the core portion.
The shaft material is an interdental brush satisfying the following (A) to (C).
(A) Shaft bending strength; The repulsive force when a portion 5 mm from the tip of the shaft material is flipped at a speed of 10 mm / sec is 0.56 N or more.
(B) Shaft bending strength: The base end portion of the brush portion is bent 90 degrees in the first direction orthogonal to the axis of the shaft member, returned to its original position, and 90 degrees in the second direction opposite to the first direction. In the left-right bending test of bending and returning to the original position, the number of times of bending in the same direction until the core portion breaks is 20 times or more.
(C) Repeated bending strength: In a 90-degree bending test in which the base end portion of the brush portion is bent 90 degrees in the first direction orthogonal to the axis of the shaft member and then returned to the original direction, the fifth time in the same direction. The maximum stress when bending to is 1.7 N or more. Claims that the constituent material of the core portion has a flexural modulus of 3.0 GPa or more measured according to ASTM D790 and a tensile elongation at break of 7.0% or more measured according to ASTM D638. The interdental brush according to 1. The interdental brush according to claim 1 or 2, wherein the fibrous filler contains potassium titanate fibers. The interdental brush according to any one of claims 1 to 3, wherein the first synthetic resin contains polyester.

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