JP7307142B2 - interdental brush - Google Patents

Description

The present invention relates to interdental brushes used for cleaning between teeth.

The interdental brush includes a handle portion including a grip portion for gripping by a user, a core joined to the handle, and filament bundles implanted in the core. The core material and the handle are joined by insert molding, for example. Patent Literature 1 discloses an example of a conventional interdental brush.

JP 2016-104382 A

In the insert molding of interdental brushes, for example, the position of the core material placed in the mold may be displaced from the specified position due to the force applied to the core material when the resin material is supplied into the mold. In an interdental brush manufactured with such a deviation, for example, the handle portion and the core material may not be joined with sufficient strength.
SUMMARY OF THE INVENTION An object of the present invention is to provide an interdental brush in which it is possible to easily visually recognize whether the handle portion and the core material are properly joined by insert molding.

One form of the interdental brush according to the present invention comprises a handle portion made of resin, and a brush portion joined to the handle portion so as to clean between the teeth, the brush portion comprising a core material, and The core material includes a filament bundle provided on the core material, the core material includes a coating portion coated on the handle portion, and the handle portion has an opening that allows a portion of the coating portion to be visually recognized. include.
Since the handle portion includes the opening, it is easy to visually recognize that the core material and the handle portion are properly joined through the opening.

In one example of the interdental brush, the handle portion extends in the longitudinal direction of the handle portion and includes a first front surface and a second front surface provided to sandwich a central axis along the longitudinal direction of the handle portion, and the opening. The section includes a first opening that opens at the first front surface and a second opening that opens at the second front surface.
It can be easily visually recognized from both the first front and the second front that the core and the handle are properly joined.

In one example of the interdental brush, the handle portion further includes a partition wall formed to partition the first opening and the second opening, and the covering portion comprises the partition wall and are spliced.
Therefore, the handle portion and the core material are joined more strongly.

In one example of the interdental brush, the partition wall has a thickness in the range of 0.3 to 0.7 mm.
It was confirmed by tests that when the thickness of the partition wall is in the range of 0.3 mm or more, the handle portion and the core material are joined more strongly. It was confirmed by tests that the visibility of the covering portion through the opening is enhanced when the thickness of the partition wall is in the range of 0.7 mm or less.

According to one example of the interdental brush, the handle portion includes a grip portion and a neck portion, the covering portion covers at least the neck portion, and the opening is provided in the neck portion.
Since the opening is provided in the neck portion, the user's fingers are less likely to get caught in the opening when using the interdental brush.

According to one example of the interdental brush, the opening is provided at the end of the neck on the side of the grip.
Since the opening is provided at a position away from the filament bundle, it is difficult for plaque or the like adhering to the filament bundle to enter the opening.

According to the above interdental brush, it can be easily visually recognized that the handle portion and the core material are appropriately joined by insert molding.

The perspective view of the 1st front side of the interdental brush of embodiment. 2 is a perspective view of the second front side of the interdental brush of FIG. 1; FIG. 2 is a front view of the interdental brush of FIG. 1; FIG. 2 is a side view of the interdental brush of FIG. 1; FIG. FIG. 2 is an enlarged view of the neck portion of FIG. 1 and its surroundings; FIG. 4 is a cross-sectional view taken along line D6-D6 in FIG. 3; FIG. 5 is a cross-sectional view taken along line D7-D7 in FIG. 4; FIG. 8 is an enlarged view of the second portion of FIG. 7; FIG. 7 is an enlarged view of the second portion of FIG. 6; FIG. 2 is a side view of the interdental brush of FIG. 1 relating to the first mode of use; The side view regarding the 2nd usage form of the interdental brush of FIG. The side view regarding the 3rd usage form of the interdental brush of FIG. The side view regarding the 4th usage form of the interdental brush of FIG. Sectional drawing of the clamped mold. FIG. 4 is a cross-sectional view showing a state in which a resin material is injected into a mold; The table|surface which shows the test conditions and the measurement result regarding a 1st test. Table showing test conditions and measurement results for the second test. The graph which shows the relationship between the 1st deformation|transformation rate of FIG. 17, and the maximum torque. The graph which shows the relationship between the 2nd deformation|transformation rate of FIG. 17, and the maximum torque. Table showing test conditions and measurement results for the third test. Table showing test conditions and measurement results for the fourth test.

(embodiment)
The configuration of the interdental brush 1 will be described with reference to FIGS. 1 to 3. FIG.
The interdental brush 1 comprises a handle portion 10 and a brush portion 100. As shown in FIG. The handle portion 10 constitutes the body of the interdental brush 1 . The brush portion 100 is joined to the handle portion 10 for cleaning between the teeth. An axial direction, a width direction and a thickness direction can be defined for the interdental brush 1 . The axial direction of the interdental brush 1 is the direction along the central axis C of the interdental brush 1 . The width direction of the interdental brush 1 is a direction orthogonal to the axial direction of the interdental brush 1 when the interdental brush 1 is viewed from the front. The thickness direction of the interdental brush 1 is a direction orthogonal to the axial direction of the interdental brush 1 in a side view of the interdental brush 1 . The structure of the interdental brush 1 is symmetrical with respect to a central plane D (see FIG. 4) parallel to the axial and width directions of the interdental brush 1 . The central axis C of the interdental brush 1 is contained in the central plane D.

The handle portion 10 includes a first front surface 10A (see FIG. 1), a second front surface 10B (see FIG. 2), a first end 10C and a second end 10D. The first front surface 10A and the second front surface 10B are surfaces provided so as to sandwich the central axis C and the central plane D (see FIG. 4) of the interdental brush 1 . The first end portion 10C is one end portion of the handle portion 10 in the axial direction of the interdental brush 1 . The second end portion 10D is the other end portion of the handle portion 10 in the axial direction of the interdental brush 1 . The shape of the first end portion 10C is approximately spherical. Therefore, when the first end 10C comes into contact with tissue in the mouth, the impact can be softened. The shape of the second end portion 10D is approximately hemispherical.

The handle portion 10 further includes a neck portion 20 , a grip portion 30 and a portion to be bent 40 . The grip part 30 is a part configured so that the user can firmly grip it with his or her fingers. The neck portion 20 is a portion configured to be relatively thinner than the grip portion 30 so as to be less likely to come into contact with tissue in the mouth. Neck portion 20 includes first end portion 10C of handle portion 10 . Grip portion 30 includes second end portion 10</b>D of handle portion 10 . The grip portion 30 is configured to be grippable by the user. The portion to be bent 40 includes a first portion to be bent 41 and a second portion to be bent 42 .

The first bending portion 41 is provided in the neck portion 20 . The second bending portion 42 is provided on the grip portion 30 . Each of the bendable portions 41 and 42 is configured to be bendable in order to adjust the insertability of the brush portion 100 between teeth. Since the neck portion 20 is provided with the first bending portion 41, the neck portion 20 can be easily bent. Since the grip portion 30 is provided with the second bendable portion 42, the posture of the brush portion 100 can be adjusted in various ways.

Brush section 100 includes core material 110 , filament bundle 200 , and cleaning section 140 . The core material 110 holds the filament bundle 200 . The cleaning part 140 is a part of the brush part 100 that directly participates in cleaning between teeth. The cleaning portion 140 is composed of a portion of the core material 110 where the filament bundles 200 are planted (hereinafter “holding portion 121”) and the filament bundles 200 . Filament bundle 200 is comprised of a plurality of filaments to remove plaque and food debris from between the teeth. Examples of materials that make up the filaments are nylon resin and polybutylene terephthalate resin. The filament bundle 200 is implanted in the core material 110 so as to protrude radially from the core material 110 .

The interdental brush 1 can take multiple forms of use. In each usage pattern, the handle portion 10 has a shape corresponding to the portion between the teeth to be cleaned. In one example, the multiple usage patterns of the interdental brush 1 include first to fourth usage patterns.

FIG. 10 is a side view of the interdental brush 1 in the first mode of use. The first form of use is a form suitable mainly for cleaning between front teeth. In the first usage pattern, the intended folding portion 40 is not folded, and the shape of the handle portion 10 is linear.

FIG. 11 is an example of a side view of the interdental brush 1 in the second usage pattern. The second form of use is a form suitable mainly for cleaning between the teeth of premolars. In the second usage pattern, the handle portion 10 is bent at the first bendable portion 41 so that the brush portion 100 falls down.

FIG. 12 is an example of a side view of the interdental brush 1 in the third usage pattern. The third form of use is a form suitable mainly for cleaning between molar teeth. In the third usage pattern, the handle portion 10 is bent at the second bendable portion 42 so that the brush portion 100 falls down.

FIG. 13 is an example of a side view of the interdental brush 1 in the fourth usage pattern. The fourth usage form is a form suitable mainly for cleaning between molar teeth. In the fourth usage pattern, the handle portion 10 is bent at the bending portions 41 and 42 so that the brush portion 100 falls down.

As shown in FIG. 3, handle portion 10 further includes an opening 50 and a partition wall 60 . The opening 50 and the partition wall 60 are provided in the neck portion 20 . The opening 50 is a portion including a hole formed in the handle portion 10 and a resin portion of the handle portion 10 forming the hole. In one example, openings 50 include a first opening 51 and a second opening 52 (see FIG. 2). The first opening 51 opens at the first front surface 10A. The second opening 52 opens at the second front surface 10B. The partition wall 60 partitions the first opening 51 and the second opening 52 .

Since the handle portion 10 includes the opening 50, it can be easily confirmed that the handle portion 10 and the core material 110 are properly joined. Since the opening portion 50 includes the first opening portion 51 and the second opening portion 52, the joined state between the handle portion 10 and the core material 110 can be seen from both the first front surface 10A side and the second front surface 10B side of the handle portion 10. can be easily verified. Since the opening 50 is provided in the neck portion 20 , the user's fingers are less likely to get caught in the opening 50 when using the interdental brush 1 .

The handle portion 10 is made of a resin material. Therefore, the entire handle portion 10 can be integrally molded, and the interdental brush 1 can be manufactured efficiently. The type and physical properties of the resin material forming the handle portion 10 are preferably determined, for example, from the relationship between the strength of the handle portion 10 against fatigue and the ease with which the handle portion 10 can be bent. Physical properties of the resin material that affect these factors include at least density, melting point, and elastic modulus. The strength of the handle portion 10 against fatigue is preferably determined so that fatigue does not occur during the general period of use of the interdental brush 1 .

An example of a preferable resin material is a crystalline resin material. An example of a preferred crystalline resin material is polyolefin resin. An example of a preferred polyolefin resin is polyethylene resin or polypropylene resin (PP). An example of a preferred polyethylene resin is linear low density polyethylene resin (LLDPE), high density polyethylene resin (HDPE) or branched low density polyethylene resin (LDPE). Preferred physical properties when the handle portion 10 is made of polyolefin resin are shown below.

An example of a preferred upper density limit is 930 kg/m3. An example of a more preferable upper limit of density is 928 kg/m3. An example of a preferred lower density limit is 920 kg/m3. An example of a more preferable lower limit of density is 923 kg/m3. An example of a preferred range for density is 920-930 kg/m3. An example of a more preferred range for density is 923-928 kg/m3. An example of a preferred density is 925 kg/m3.

An example of a preferred upper melting point is 126°C. An example of a more preferable upper limit of the melting point is 124°C. An example of a preferable lower limit of the melting point is 120°C. An example of a more preferable lower limit of the melting point is 121°C. An example of a preferred range for the melting point is 120-126°C. An example of a more preferred range for the melting point is 121-124°C. An example of a preferred melting point is 123°C.

An example of a preferable upper limit of the elastic modulus is 300 MPa. An example of a more preferable upper limit of the elastic modulus is 230 MPa. An example of a preferable lower limit of elastic modulus is 200 MPa. An example of a more preferable lower limit of the elastic modulus is 210 MPa. An example of a preferred range for elastic modulus is 200-300 MPa. An example of a more preferred range for elastic modulus is 210-230 MPa. An example of a preferred elastic modulus is 230 MPa.

Details of the neck portion 20 will be described with reference to FIGS. 3 and 4. FIG.
Neck portion 20 includes a base portion 21 , an intermediate portion 22 and a tip portion 23 . The base portion 21 is a portion connected to the grip portion 30 . The opening 50 is provided in the base 21 . The shape of the intermediate portion 22 is flat. The first bending portion 41 is provided on the base portion 21 and the intermediate portion 22 . The tip portion 23 is a portion including the first end portion 10C of the handle portion 10 .

As shown in FIGS. 3 and 4, the width and thickness of neck portion 20 are different for each portion of neck portion 20 . The width of the neck portion 20 is the dimension of the neck portion 20 in the width direction of the interdental brush 1 . The thickness of the neck portion 20 is the dimension of the neck portion 20 in the thickness direction of the interdental brush 1 . The width LA and thickness LB of the base portion 21 narrow from the grip portion 30 side toward the intermediate portion 22 side. In a cross section of the neck portion 20 perpendicular to the central axis C of the interdental brush 1, the width LA is greater than the thickness LB. The width LC and thickness LD of the intermediate portion 22 are constant. In a cross section of the neck portion 20 perpendicular to the central axis C of the interdental brush 1, the width LC is greater than the thickness LD.

As shown in FIG. 5, the first bending portion 41 includes one or more first grooves 41A. In the illustrated example, the first bending portion 41 includes eight first grooves 41A. 41 A of 1st groove|channels are formed so that the neck part 20 can be bent in the direction in which the protrusion part 120 of the brush part 100 falls down. Each first groove 41A is provided in each of the first front face 10A and the second front face 10B. 41 A of each 1st groove|channel is located in a line with the axial direction of the interdental brush 1. As shown in FIG. 41 A of each 1st groove|channel is provided in the width direction of the interdental brush 1 in the substantially whole neck part 20. As shown in FIG. Since the first portion to be bent 41 includes at least one first groove 41A, the first portion to be bent 41 can be easily bent. In the following description, in order to distinguish between the first grooves 41A, the numbers of the first grooves 41A are determined in order from the first groove 41A formed closest to the grip portion 30. As shown in FIG.

The width XA and depth HA (see FIG. 6) of the first groove 41A are preferably determined based on, for example, the relationship between the ease of bending the first bending portion 41 and the strength of the neck portion 20 against bending. . The width XA of the first groove 41A is the dimension of the first groove 41A in the axial direction of the interdental brush 1 . The depth HA of the first groove 41A is the dimension of the first groove 41A in the thickness direction of the interdental brush 1. For example, the cross section of the handle portion 10 orthogonal to the central plane D of the interdental brush 1 (see FIG. 6) ) as defined above.

The width XA1 of the first groove 41A is the widest among the widths XA of the first grooves 41A. The width XA2 of the second first groove 41A is the second widest among the widths XA of the respective first grooves 41A. The width XA3 of the third first groove 41A is the third widest among the widths XA of the respective first grooves 41A. The widths XA4 of the fourth to eighth first grooves 41A are equal to each other and are the narrowest among the widths XA of the respective first grooves 41A.

An example of the upper limit of the preferred width XA is 1.2 mm. An example of a more preferable upper limit of the width XA is 1.0 mm. An example of a preferable lower limit of width XA is 0.3 mm. An example of a more preferable lower limit of width XA is 0.4 mm. An example of a preferred range for width XA is 0.3 to 1.2 mm. An example of a more preferable range for width XA is 0.4 to 1.0 mm. An example of a preferred width XA1 is 1.01 mm. An example of a preferred width XA2 is 0.8 mm. An example of a preferred width XA3 is 0.6 mm. An example of a preferred width XA4 is 0.4 mm.

The depth HA of each first groove 41A is the same. An example of the upper limit of the preferable depth HA is 0.7 mm. An example of a more preferable upper limit of the depth HA is 0.6 mm. An example of a preferable lower limit of the depth HA is 0.05 mm. An example of a more preferable lower limit of the depth HA is 0.1 mm. An example of a preferred range for depth HA is 0.05-0.7 mm. An example of a more preferable range for depth HA is 0.1 to 0.6 mm. An example of a preferred depth HA is 0.1 mm.

Details of the grip portion 30 will be described with reference to FIGS. 3 and 4. FIG.
Grip portion 30 includes an upper portion 31 , a middle portion 32 and a lower portion 33 . The grip portion 30 has a flat shape. The upper portion 31 is a portion connected to the base portion 21 of the neck portion 20 . The lower portion 33 is a portion including the second end portion 10D of the handle portion 10 . The intermediate portion 32 is the portion between the upper portion 31 and the lower portion 33 . The second bending portion 42 is provided in the intermediate portion 32 . The grip part 30 is constricted so that the intermediate part 32 is narrower than the upper part 31 and the lower part 33 when the interdental brush 1 is viewed from the front.

As shown in FIG. 3, the second bending portion 42 includes one or more second grooves 42A. In the illustrated example, the second bending portion 42 includes six second grooves 42A. The second groove 42A is formed so that the grip portion 30 can be bent in the direction in which the projecting portion 120 of the brush portion 100 falls. The second groove 42A is provided on each of the first front face 10A and the second front face 10B. 42 A of each 2nd groove|channel is located in a line with the axial direction of the interdental brush 1. As shown in FIG. Each second groove 42A is provided so as to make one turn around the grip portion 30 around the central axis C of the interdental brush 1 . Since the second portion to be bent 42 includes at least one second groove 42A, the second portion to be bent 42 can be easily bent.

The width XB and depth HB (see FIG. 6) of the second groove 42A are preferably determined based on, for example, the relationship between the ease of bending the second bending portion 42 and the strength of the grip portion 30 against bending. . The width XB of the second groove 42A is the dimension of the second groove 42A in the axial direction of the interdental brush 1 . The depth HB of the second groove 42A is the dimension of the second groove 42A in the thickness direction of the interdental brush 1. ) as defined above.

The width XB of each second groove 42A is the same. An example of the upper limit of the preferred width XB is 0.7 mm. An example of a more preferable upper limit of the width XB is 0.6 mm. An example of a preferable lower limit of width XB is 0.3 mm. An example of a more preferable lower limit of width XB is 0.4 mm. An example of a preferred range for width XB is 0.3 to 0.7 mm. An example of a more preferable range for width XB is 0.4 to 0.6 mm. An example of a preferred width XB is 0.5 mm.

The depth HB of each second groove 42A is the same. An example of the upper limit of the preferred depth HB is 1.2 mm. An example of the upper limit of the more preferable depth HB is 1.0 mm. An example of a preferable lower limit of the depth HB is 0.2 mm. An example of a more preferable lower limit of the depth HB is 0.3 mm. An example of a preferred range for depth HB is 0.2 to 1.2 mm. An example of a more preferable range for depth HB is 0.3 to 1.0 mm. An example of a preferred depth HB is 0.5 mm.

Details of the brush unit 100 will be described with reference to FIG.
The core material 110 is composed of a wire. Examples of materials constituting the wire include stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic/ferritic stainless steel, martensitic stainless steel, precipitation hardening stainless steel, nickel-based alloys, cobalt-based alloys, Alternatively, it is a titanium-nickel alloy.

The core material 110 is twisted so as to hold the filament bundle 200 . In one example, the brush section 100 is configured as follows. First, one wire, which is the material of the core material 110, is bent to form a bent portion of the wire (hereinafter, “a bent portion 110P of the core material 110”). As a result, the wire is divided into one portion (hereinafter referred to as "first folded portion 110A of core material 110") and the other portion (hereinafter referred to as "second folded portion 110B of core material 110") relative to folded portion 110P. be.

Next, the first folded portion 110A and the second folded portion 110B of the core material 110 are overlapped so as to be parallel to each other. Next, the filament bundle 200 is inserted between the first folded portion 110A and the second folded portion 110B so as to be sandwiched between the first folded portion 110A and the second folded portion 110B. Next, the first folded portion 110A and the second folded portion 110B are twisted together so that the filament bundle 200 is strongly held by the first folded portion 110A and the second folded portion 110B.

After the first folded portion 110A and the second folded portion 110B are twisted, the filament bundle 200 is cut into, for example, a conical shape to form the brush portion 100. As shown in FIG. The twisted first folded portion 110A and the second folded portion 110B constitute one wire. Tip portion 110C of core material 110 includes bent portion 110P. A covered end portion 110D, which is the end portion of the core material 110 opposite to the tip portion 110C, includes the tip of the first folded portion 110A and the tip of the second folded portion 110B. The thickness of core material 110 varies in the direction along the central axis of core material 110 . In one example, the maximum thickness of core material 110 represents the thickness of core material 110 . The maximum thickness of core 110 is approximately twice the diameter of the wire.

Core material 110 includes protruding portion 120 and covering portion 130 . Protruding portion 120 includes holding portion 121 and non-holding portion 122 . The holding portion 121 is a portion including the bent portion 110P of the core material 110 and implanted with the filament bundle 200 . The non-holding portion 122 is a portion between the holding portion 121 and the tip portion 23 of the neck portion 20, and is a portion where the filament bundle 200 is not implanted.

The thickness of the projecting portion 120 is preferably determined, for example, from the relationship with the strength of the projecting portion 120 against bending. The thickness of the projecting portion 120 is, for example, the same as the thickness of the core material 110 . A preferred example of the upper limit of the thickness of the projecting portion 120 is 0.7 mm. A more preferable example of the upper limit of the thickness of the projecting portion 120 is 0.6 mm. A preferred example of the lower limit of the thickness of the projecting portion 120 is 0.3 mm. A more preferable example of the lower limit of the thickness of the projecting portion 120 is 0.4 mm. A preferred range for the thickness of the projecting portion 120 is 0.3 to 0.7 mm. An example of a more preferable range for the thickness of the projecting portion 120 is 0.4 to 0.6 mm. An example of the preferable thickness of the protrusion 120 is 0.4 mm.

The covering portion 130 is a portion covering the handle portion 10 and includes a first portion 131 and a second portion 132 . The first portion 131 is a portion that is not plastically worked. The second portion 132 is a portion subjected to plastic working. An example of plastic working applied to the second portion 132 is press working. The second portion 132 is formed by pressing a portion of the core material 110 in which the first folded portion 110A and the second folded portion 110B are twisted. The shape of the second portion 132 is a flat, substantially rectangular shape. The shape of the second portion 132 can be changed arbitrarily. Other examples of the shape of the second portion 132 are a flat substantially square shape, a flat substantially circular shape, a flat substantially oval shape, or a flat substantially triangular shape. The second portion 132 is provided at an arbitrary position on the covering portion 130 of the core material 110 . In a preferred example, the second portion 132 is provided in a range including the covered end portion 110D of the core material 110 . A portion of the covering portion 130 (hereinafter “visible portion 133 ”) is visible through the opening 50 . In one example, the visible portion 133 is included in the first portion 131 .

The thickness MA of the first portion 131 is related to, for example, the ease of bending the first bending portion 41, the ability to retain the shape of the neck portion 20 in a bent state, and the strength of the neck portion 20 against fatigue. is preferably determined from In the illustrated example, the thickness of the first portion 131 is the same as the thickness of the core material 110 .

A preferred example of the upper limit of the thickness of the first portion 131 is 0.7 mm. A more preferable example of the upper limit of the thickness of the first portion 131 is 0.6 mm. A preferable example of the lower limit of the thickness of the first portion 131 is 0.3 mm. A more preferable example of the lower limit of the thickness of the first portion 131 is 0.4 mm. A preferred range for the thickness MA of the first portion 131 is 0.3 to 0.7 mm. An example of a more preferable range for the thickness MA of the first portion 131 is 0.4 to 0.6 mm. An example of a preferable thickness MA of the first portion 131 is 0.4 mm. The thickness MA of the first portion 131 is preferably greater than the thickness of the partition wall 60 .

The easiness of bending the first portion to be bent 41 and the ability to maintain the shape of the neck portion 20 are related not only to the thickness MA of the first portion 131 itself but also to the core material occupation ratio PX. The core material occupancy PX is the ratio of the thickness MA of the first portion 131 to the thickness of the thinnest portion of the neck portion 20 (hereinafter “minimum dimension PM”). In one example, the minimum dimension PM is defined on the cross section of the handle portion 10 perpendicular to the center plane D of the interdental brush 1 (see FIG. 6), and the bottom surface of the first groove 41A formed in the first front surface 10A and the first groove 41A formed in the first front surface 10A. It is the distance from the bottom surface of the first groove 41A formed in the second front surface 10B. The formula for obtaining the core material occupancy PX is "PX=MA/PM×100 (%)".

A preferable example of the upper limit of the core material occupancy PX is 45%. An example of a more preferable upper limit of the core material occupancy PX is 40%. A preferable example of the lower limit of the core material occupancy PX is 15%. An example of a more preferable lower limit of the core material occupancy PX is 20%. An example of a preferable range for the core material occupancy PX is 15 to 45%. An example of a more preferable range for the core material occupancy PX is 20 to 40%. An example of a preferable core material occupancy PX is 20%. When the core material occupancy PX is in the range of 20% or more, the bent state of the neck portion 20 is likely to be maintained. When the core material occupancy PX is in the range of 40% or less, the first bending portion 41 is easily bent.

The degree of deformation of the covering portion 130 by plastic working can be defined, for example, by at least one of the first deformation rate PA and the second deformation rate PB. The first deformation rate PA is the ratio of the maximum width MB (see FIG. 9) of the second portion 132 to the thickness MA of the first portion 131 . The maximum width MB of the second portion 132 is the dimension of the second portion 132 in the width direction of the interdental brush 1 . The formula for obtaining the first deformation rate PA is "PA=MB/MA×100(%)". The second deformation rate PB is the ratio of the thickness MA of the first portion 131 to the thickness MC of the second portion 132 (see FIG. 8). The thickness MC of the second portion 132 is the dimension of the second portion 132 in the thickness direction of the interdental brush 1 . The formula for obtaining the second deformation rate PB is "PB=MA/MC×100(%)".

The first deformation rate PA is preferably determined, for example, from the relationship between the joint strength between the handle portion 10 and the covering portion 130 against twisting and the strength of the second portion 132 of the covering portion 130 . A preferred example of the upper limit of the first deformation rate PA is 150%. An example of a more preferable upper limit of the first deformation rate PA is 145%. A preferable example of the lower limit of the first deformation rate PA is 130%. An example of a more preferable lower limit of the first deformation rate PA is 135%. A preferred range for the first deformation rate PA is 130% to 150%. An example of a more preferable range for the first deformation rate PA is 135-145%. An example of a preferable first deformation rate PA is 140%.

When the first deformation rate PA is in the range of 130% or more, the joint between the handle portion 10 and the covering portion 130 is less likely to come off when a force is applied to the interdental brush 1 to twist the handle portion 10 and the projection portion 120. . When the first deformation rate PA is within the range of 150% or less, high strength is ensured for the second portion 132 . Moreover, when the interdental brush 1 is manufactured by insert molding, the position of the brush part 100 with respect to the mold is less likely to shift from the prescribed position.

The second deformation rate PB is preferably determined, for example, from the relationship between the joint strength between the handle portion 10 and the covering portion 130 against twisting and the strength of the second portion 132 . A preferable example of the upper limit of the second deformation rate PB is 260%. An example of a more preferable upper limit of the second deformation rate PB is 250%. A preferable example of the lower limit of the second deformation rate PB is 200%. An example of a more preferable lower limit of the second deformation rate PB is 210%. A preferred range for the second deformation rate PB is 200 to 260%. An example of a more preferable range for the second deformation rate PB is 210-250%. An example of a preferable second deformation rate PB is 240%.

When the second deformation rate PB is in the range of 200% or more, the joint between the handle portion 10 and the cover portion 130 is less likely to come off when a twisting force is applied to the handle portion 10 and the projecting portion 120 . When the second deformation rate PB is within the range of 260% or less, high strength is ensured for the second portion 132 . Moreover, when the interdental brush 1 is manufactured by insert molding, the position of the brush part 100 with respect to the mold is less likely to shift from the prescribed position.

A factor other than the first deformation rate PA and the second deformation rate PB is also related to the joint strength between the handle portion 10 and the covering portion 130 against torsion. One example is the spacing ratio PC and the coverage ratio PD. The separation rate PC and the coverage rate PD individually affect the joint strength, and also independently of the first deformation rate PA and the second deformation rate PB.

The separation ratio PC is the ratio of the separation distance HY of the second portion 132 to the length HX of the covering portion 130 shown in FIGS. The length HX of the covering portion 130 is the dimension of the covering portion 130 in the axial direction of the interdental brush 1 . The separation distance HY of the second portion 132 is the distance between the covered end portion 110D of the core material 110 and the center point 132A of the second portion 132 . The formula for calculating the spacing ratio PC is "PC=HY/HX×100(%)".

An example of a preferable range for the spacing ratio PC is 55% or less. An example of a more preferable range for the spacing rate PC is 30% or less. An example of a preferable spacing ratio PC is 7%. When the spacing ratio PC is within the range of 55% or less, the joint between the handle portion 10 and the cover portion 130 is less likely to come off when a force is applied to the interdental brush 1 to twist the handle portion 10 and the projection portion 120 .

The coverage PD is the ratio of the length HX of the covering portion 130 to the length ZA of the core material 110 . The length ZA of the core 110 is the overall dimension of the core 110 in the axial direction of the interdental brush 1 . The length HX of the covering portion 130 is the overall dimension of the covering portion 130 in the axial direction of the interdental brush 1 . The formula for obtaining the coverage PD is "PD=HX/ZA×100(%)".

An example of a preferable range for the coverage PD is 40% or more. An example of a more preferable range for the coverage PD is 55% or more. An example of a preferred coverage PD is 60%. When the coverage PD is in the range of 40% or more, the joint between the handle portion 10 and the cover portion 130 is less likely to come off when a force is applied to the interdental brush 1 to twist the handle portion 10 and the projection portion 120 .

An example of a factor related to the operability of the interdental brush 1 is the protrusion rate PE. The projection ratio PE is the ratio of the length NA of the neck portion 20 to the length SA of the projection portion 120 . The length SA of the protrusion 120 is the dimension of the protrusion 120 in the axial direction of the interdental brush 1 . The length NA of the neck 20 is the dimension of the neck 20 in the axial direction of the interdental brush 1 . The formula for calculating the protrusion rate PE is "PE=NA/SA×100(%)". The protrusion rate PE is preferably determined from the relationship between the insertability of the cleaning part 140 between teeth and the distance between the cleaning part 140 and the grip part 30 in the axial direction of the interdental brush 1 .

An example of the upper limit of the preferable protrusion rate PE is 150%. An example of a more preferable upper limit of the protrusion rate PE is 140%. An example of the lower limit of the preferable protrusion rate PE is 30%. An example of a more preferable lower limit of the protrusion rate PE is 40%. An example of a preferred range for the protrusion rate PE is 30-150%. An example of a more preferable range for the protrusion rate PE is 40-140%. An example of a preferable protrusion rate PE is 125%.

When the protrusion rate PE is in the range of 30% or more, the distance between the grip portion 30 and the cleaning portion 140 in the axial direction of the interdental brush 1 is long, so plaque and food residue adhering to the cleaning portion 140 are removed. It is hard to stick to the user's hand. Further, since the distance between the opening 50 and the cleaning portion 140 is increased, it is difficult for dental plaque and the like adhering to the cleaning portion 140 to enter the opening 50 . When the protrusion rate PE is within the range of 170% or less, it is easy to insert the cleaning part 140 between the teeth.

Details of the opening 50 and the partition wall 60 will be described with reference to FIG.
The opening 50 includes a hole that allows the visible portion 133 of the covering portion 130 to be visible from the outside of the handle portion 10 . Therefore, it is possible to visually confirm through the opening 50 whether or not the partition wall 60 and the covering portion 130 are properly joined. Examples of a state in which the partition wall 60 and the covering portion 130 are not properly bonded include a state in which the core material 110 cannot be visually recognized through the opening 50, and a state in which the core material 110 is visually recognized through the opening 50. A state in which the center brush 1 is remarkably biased with respect to the central axis C can be mentioned. If such a condition is confirmed, the corresponding interdental brush 1 can be removed from the shipment. The first opening 51 includes a hole opened at the base 21 of the neck portion 20 of the first front face 10A. The second opening 52 (see FIG. 2) includes a hole opened at the base 21 of the neck 20 of the second front face 10B. The opening area of the hole included in each of the openings 51 and 52 becomes narrower from the opening of the hole toward the partition wall 60 .

It is preferable that the minimum opening area of the opening 50 is determined in relation to the visibility of the cover 130, for example. In one example, the portion of the first opening 51 that is closest to the partition wall 60 (hereinafter “bottom portion 51A of the first opening 51”) has the smallest opening area. The shape of the bottom portion 51A of the first opening portion 51 is rectangular. The minimum opening area is determined by the dimension YA of the bottom portion 51A in the axial direction of the interdental brush 1 and the dimension YB of the bottom portion 51A in the width direction of the interdental brush 1 .

An example of the upper limit of the minimum preferred opening area is 2.0 mm ² . An example of the upper limit of a more preferable minimum opening area is 1.8 mm ² . An example of the lower limit of the minimum preferred opening area is 1.0 mm ² . An example of the lower limit of the more preferable minimum opening area is 1.2 mm ² . An example of a preferred range for minimum open area is 1.0-1.2 mm ² . An example of a more preferred range for the minimum open area is 1.2-1.8 mm ² . An example of a preferred minimum open area is 1.8 mm ² . The minimum opening area of the second opening 52 is also determined in the same manner as the first opening 51 .

The partition wall 60 is joined to the covering portion 130 . Therefore, the handle portion 10 and the covering portion 130 are joined more strongly. The thickness of the partition wall 60 is preferably determined, for example, from the relationship between the visibility of the covering portion 130 through the opening 50 and the joint strength between the handle portion 10 and the covering portion 130 against twisting. The thickness of the partition wall 60 is the dimension of the partition wall 60 in the thickness direction of the interdental brush 1 .

A preferred example of the upper limit of the thickness of the partition wall 60 is 0.7 mm. A more preferable example of the upper limit of the thickness of the partition wall 60 is 0.6 mm. A preferred example of the lower limit of the thickness of the partition wall 60 is 0.3 mm. An example of a more preferable lower limit of the thickness of the partition wall 60 is 0.4 mm. A preferred range for the thickness of the partition wall 60 is 0.3 to 0.7 mm. An example of a more preferable range for the thickness of the partition wall 60 is 0.4 to 0.6 mm. An example of a preferred partition wall 60 thickness is 0.4 mm. When the partition wall 60 has a thickness of 0.3 mm or more, the handle portion 10 and the covering portion 130 are joined more strongly. When the partition wall 60 has a thickness of 0.7 mm or less, the visibility of the cover 130 through the opening 50 is enhanced.

Second to fourth usage patterns of the interdental brush 1 will be described with reference to FIGS. 11 to 13. FIG.
In the second type of usage shown in FIG. 11, the first bending portion 41 is bent. Therefore, the angle formed by the central axis C of the handle portion 10 and the central axis CA of the portion of the neck portion 20 closer to the distal end portion 23 than the first bending portion 41 (hereinafter referred to as "first angle θA") is , greater than 0 degrees. For example, the first angle θA is preferably within a range in which the shape of the handle portion 10 allows the cleaning portion 140 to be easily inserted and removed between molar teeth. An example of a preferable range for the first angle θA is over 0 degrees and 90 degrees or less. An example of a more preferable range for the first angle θA is 40-60°. A preferred example of the first angle θA is 40°.

In the third usage pattern shown in FIG. 12, the second bendable portion 42 is bent. Therefore, the angle formed by the central axis C of the handle portion 10 and the central axis CB of the portion of the grip portion 30 closer to the neck portion 20 than the second bending portion 42 (hereinafter referred to as the "second angle θB") is , greater than 0 degrees. For example, the second angle θB is preferably included in a range in which the shape of the handle portion 10 is highly grippable and operable. An example of a preferable range for the second angle θB is more than 0 degrees and 40 degrees or less. An example of a more preferable range for the second angle θB is 25 to 35°. A preferred example of the second angle θB is 30°.

In the fourth usage pattern shown in FIG. 13, the portions to be bent 41 and 42 are bent. Therefore, the angle formed by the central axis C of the handle portion 10 and the central axis CC of the portion of the neck portion 20 closer to the tip portion 23 than the first bending portion 41 (hereinafter referred to as the "third angle θC") is , greater than 0 degrees. For example, the third angle θC is preferably within a range in which the shape of the handle portion 10 is such that the cleaning portion 140 can be easily inserted and removed during cleaning between molar teeth. An example of a preferable range for the third angle θC is over 0 degrees and 80 degrees or less. An example of a more preferable range for the third angle θC is 50-60°. A preferred example of the third angle θC is 55°.

The angle formed by the central axis C of the handle portion 10 and the central axis CD of the portion of the grip portion 30 closer to the neck portion 20 than the second bendable portion 42 (hereinafter referred to as the "fourth angle θD") is 0 degrees. bigger than For example, the fourth angle θD is preferably included in a range in which the shape of the handle portion 10 is highly grippable and operable. An example of a preferable range for the fourth angle θD is over 0 degrees and 30 degrees or less. An example of a more preferable range for the fourth angle θD is 10 to 20 degrees. A preferable example of the fourth angle θD is 15°.

A method for manufacturing the interdental brush 1 will be described with reference to FIGS. 14 and 15. FIG.
In one example, the interdental brush 1 is manufactured by insert molding. In a first step, the brush portion 100 is manufactured. In the second step, as shown in FIG. 14, the brush portion 100 is arranged at a prescribed position within the mold 300 . Mold 300 includes a holding mold 310 and a mold 340 . The holding mold 310 is a mold for holding the brush part 100 . Mold 340 is a mold for molding handle portion 10 .

The holding mold 310 includes a fixed holding mold 320 and a movable holding mold 330 . The fixed holding mold 320 includes a first holding portion 321 and a first receiving portion 322 . The first holding portion 321 includes a groove in which the non-holding portion 122 of the core material 110 can be arranged. The first housing portion 322 includes a recess in which half of the brush portion 100 can be placed with respect to the center plane D of the interdental brush 1 (see FIG. 4). The movable holding mold 330 includes a second holding portion 331 and a second receiving portion 332 . The second holding portion 331 includes a groove in which the non-holding portion 122 of the core material 110 can be arranged. The second housing portion 332 includes a recess in which half of the brush portion 100 can be placed with respect to the center plane D of the interdental brush 1 (see FIG. 4).

Mold 340 includes stationary mold 350 and movable mold 360 . The stationary mold 350 includes a first molding portion 351 , a first gate portion 352 , a first seal portion 353 and a first convex portion 354 . The first molding portion 351 is for molding one of the portion on the first front surface 10A side and the portion on the second front surface 10B side of the handle portion 10 divided by the central plane D (see FIG. 4) of the interdental brush 1. Including recesses. First gate portion 352 includes a groove forming part of gate 342 of mold 340 . The first seal portion 353 forms part of the seal portion 343 of the mold 340 . The first convex portion 354 is a convex portion for forming one of the first opening portion 51 and the second opening portion 52 in the handle portion 10 .

The movable mold 360 includes a second molding portion 361 , a second gate portion 362 , a second sealing portion 363 and a second convex portion 364 . The second molding portion 361 is for molding the other of the portion on the first front face 10A side and the portion on the second front face 10B side of the handle portion 10, which is divided by the central plane D (see FIG. 4) of the interdental brush 1. Including recesses. The second gate portion 362 includes a groove forming part of the gate 342 of the mold 340 . The second seal portion 363 forms part of the seal portion 343 of the mold 340 . The second convex portion 364 is a convex portion for forming the other of the first opening portion 51 and the second opening portion 52 in the handle portion 10 .

In the second step, the brush portion 100 is specifically arranged at a prescribed position within the holding mold 310 as follows. First, the brush part 100 is placed in the opened stationary holding mold 320 . At this time, the non-holding portion 122 of the core material 110 is arranged on the first holding portion 321 . Next, the movable retainer mold 330 is aligned with the fixed retainer mold 320 such that a closed retainer mold 310 is formed. When the closed holding mold 310 is configured, the non-holding portion 122 of the core material 110 is sandwiched between the first holding portion 321 and the second holding portion 331 . Therefore, the position of the brush part 100 with respect to the holding mold 310 is determined.

Next, the holding mold 310 is placed in contact with the fixed mold 350 so that the covering part 130 of the brush part 100 held by the holding mold 310 is arranged on the fixed mold 350 . At this time, the visible portion 133 of the covering portion 130 is arranged on the first convex portion 354 . The movable mold 360 is then aligned with the stationary mold 350 so that the closed mold 340 is formed. Closed mold 340 includes mold space 341 , gate 342 and seal 343 . The molding space 341 is composed of a first molding portion 351 and a second molding portion 361 . The gate 342 is composed of a first gate portion 352 and a second gate portion 362 so as to supply molten resin to the molding space 341 . The sealing portion 343 is composed of a first sealing portion 353 and a second sealing portion 363 so that the resin supplied to the molding space 341 does not flow into the holding mold 310 .

When the closed molding die 340 is configured, the second convex portion 364 is arranged on the visible portion 133 of the covering portion 130, and the first convex portion 354 and the second convex portion 364 are separated by a predetermined distance (hereinafter " They are opposed to each other with a convex portion interval TA”). The protrusion interval TA is the distance between the end face 354A of the first protrusion 354 and the end face 364A of the second protrusion 364 in the closed mold 340 . An end face 354A of the first convex portion 354 and an end face 364A of the second convex portion 364 have a region facing the visually recognized portion 133 in a direction perpendicular to the end faces 354A and 364A (hereinafter referred to as a "first region") and includes a region (hereinafter referred to as a “second region”) that does not face the visually recognized portion 133 . The partition wall 60 (see FIG. 5) is formed by resin supplied between the end faces 354A, 364A.

The states of the projections 354 and 364 with respect to the visually recognized portion 133 (hereinafter referred to as "facing states") are classified into first to third facing states according to the spacing TA between the projections. By setting the height of each projection 354, 364, one of the first to third facing states can be selected. The first facing state is a state in which the projection interval TA is substantially equal to the thickness of the visually recognized portion 133, and the end surfaces 354A and 364A and the visually recognized portion 133 are in contact with each other without crimping. The second facing state is a state in which the projection interval TA is substantially equal to the thickness of the visible portion 133, and the end surfaces 354A and 364A and the visible portion 133 are crimped. The third facing state is a state in which the convex portion interval TA is wider than the thickness of the visible portion 133 and the end surfaces 354A and 364A and the visible portion 133 do not come into contact with each other.

In the example shown in FIG. 14, the facing state of the convex portions 354 and 364 is the second facing state. Each convex portion 354 , 364 holds the visually recognized portion 133 of the covering portion 130 that is closer to the second portion 132 than the center of the covering portion 130 in the axial direction of the interdental brush 1 . In this way, when the portions of the covering portion 130 closer to the gate 342 are held by the projections 354 and 364 , the covering portion 130 is less likely to bend when the resin is injected into the molding space 341 .

In the third step shown in FIG. 15, molten resin is injected into molding space 341 (see FIG. 14) through gate 342 . The resin dispensed around each projection 354, 364 forms the opening 50 (see FIG. 5) of the handle portion 10. As shown in FIG. When the first regions of the end surfaces 354A and 364A are in contact with the visible portion 133, the resin is placed between the portions of the visible portion 133 that contact the first regions and the first regions of the end surfaces 354A and 364A. is not supplied, and resin is supplied between the second region of the end face 354A and the second region of the end face 364A. When the first regions of the end faces 354A and 364A are not in contact with the visible portion 133, the distance between the visible portion 133 and the first regions of the end faces 354A and 364A and the second regions of the end face 354A and the end face 364A resin is supplied between the second region of the The resin supplied between the end faces 354A, 364A forms the partition walls 60 (see FIG. 5). The partition wall 60 (see FIG. 5) formed in the example shown in FIG. 15 does not cover the portion of the visible portion 133 that contacts the first region. In the fourth step, the handle portion 10 is cooled until the injected resin hardens. In the fifth step, the holding mold 310 and the forming mold 340 are opened, the interdental brush 1 is removed from the mold 300, and the resin portion corresponding to the gate 342 is cut from the handle portion 10. FIG.

The details of the opposing state of the projections 354 and 364 will be described.
In the first facing state, the first regions of the end surfaces 354A and 364A are in contact with the visible portion 133 so as not to substantially deform the visible portion 133, and the second regions of the end surfaces 354A and 364A are in contact with each other with a gap therebetween. facing each other. Therefore, each convex portion 354 , 364 holds the covering portion 130 by the frictional force between the first region and the visible portion 133 . In the second facing state, the first regions of the end faces 354A and 364A are pressed against the visible portion 133, and the second regions of the end faces 354A and 364A face each other with a gap therebetween. Therefore, each of the projections 354 and 364 holds the covering portion 130 with a stronger frictional force than in the first facing state.

According to the first facing state and the second facing state, since the covering portion 130, which is the portion of the brush portion 100 on the side of the gate 342, is held by the convex portions 354 and 364, the resin is injected into the molding space 341. The covering portion 130 is hard to bend. Therefore, the moldability of the handle portion 10 is enhanced. According to the second facing state, since the frictional force between the protrusions 354 and 364 and the visually recognized portion 133 is large, the covering portion 130 is more difficult to bend, and the handle portion 10 can be formed more easily. Further, when the first facing state or the second facing state is formed in the mold 340, the non-holding portion 122 is held by the holding portions 321 and 331, and the visible portion 133 is held by the convex portions 354 and 364. Therefore, the position and posture of the brush portion 100 with respect to the mold 300 are stabilized when the resin is injected into the molding space 341 . This point also contributes to enhancing the moldability of the handle portion 10 . Further, according to the first facing state and the second facing state, portions of the visible portion 133 that contact the first regions of the end surfaces 354A and 364A are not covered with the partition wall 60 (see FIG. 5). The visibility of the visual recognition portion 133 is further enhanced.

In the third facing state, the first regions of the end surfaces 354A and 364A face the visible portion 133 without contacting the visible portion 133, and the second regions of the end surfaces 354A and 364A face the visible portion 133 with a gap therebetween. there is According to the third facing state, the range in which covering portion 130 bends is restricted by end surfaces 354A and 364A, so large bending of covering portion 130 during injection of resin into molding space 341 is suppressed. Therefore, the moldability of the handle portion 10 is enhanced. The range in which the covering portion 130 bends when the resin is injected becomes narrower as the convex interval TA becomes narrower. When the handle portion 10 is molded in the third opposed state, the visually recognized portion 133 is entirely covered with the partition wall 60 (see FIG. 5). Even in this case, the visibility of the visible portion 133 can be enhanced by reducing the thickness of the partition wall 60 . When the resin material forming the partition wall 60 is a resin material having a high transmittance such as a transparent material or a translucent material, a part of the visible portion 133 is not covered with the partition wall 60, and In any case where the visible portion 133 is entirely covered with the partition wall 60 , substantially the same degree of visibility is ensured for the visible portion 133 . Further, when the handle portion 10 is molded in the third facing state, the dividing wall 60 becomes thicker than when the handle portion 10 is molded in the first facing state and the second facing state. The bonding strength with 130 is increased.

As described above, the protrusion interval TA is related to the moldability of the handle portion 10, the visibility of the visible portion 133, and the joint strength between the handle portion 10 and the covering portion 130 against twisting. Therefore, it is preferable to determine the convex interval TA from the relationship with these factors. An example of the preferable protrusion interval TA determined from the viewpoint of moldability is the interval at which the end surfaces 354A and 364A and the visually recognized portion 133 are crimped.

(Example)
First to fourth tests conducted to evaluate the performance of the interdental brush 1 will be described. A sample of the example was used in each test. The sample of the example is a sample relating to the interdental brush 1 of the embodiment. The molding method of the handle portion 10 of each sample is the same as the molding method exemplified in the embodiment. In order to visually inspect the state of the covering portion 130 in the third test, a transparent resin material was used to manufacture each sample.

The first test will be explained. In the first test, the relationship between the type of resin material constituting the handle portion 10, its physical properties, and the strength of the handle portion 10 against fatigue was confirmed using the samples of Examples 1-8. The test conditions are the type of resin material, the density of the resin material, the melting point of the resin material, the elastic modulus of the resin material, and the diameter of the raw material of the core material 110 . FIG. 16 shows specific test conditions. The modulus of elasticity of the samples of Examples 1 to 5 and 7 is the flexural modulus. The modulus of elasticity of the samples of Examples 6 and 8 is the tensile modulus.

In the first test, in order to evaluate the strength of the neck portion 20 against fatigue, the first bending planned portion 41 is repeatedly bent so that the first angle θA (see FIG. 11) is about 90°, and the first bending planned The number of times of bending (hereinafter, "maximum number of times of bending") when the portion 41 was fractured due to fatigue was measured. The operation of changing the usage pattern of the handle portion 10 from the first usage pattern to the second usage pattern and then to the first usage pattern again was counted as one bending.

As shown in FIG. 16, it was confirmed that the samples of Examples 1-4 had more maximum bending times than the samples of Examples 5-8. This indicates that the strength of the neck portion 20 against fatigue increases when the type of resin material and its physical property values are included in the conditions exemplified in the embodiment.

A second test will be described. In the second test, the relationship between the degree of plastic working of the covering portion 130 and the bonding strength between the handle portion 10 and the covering portion 130 against twisting was confirmed using the samples of Examples 9-14. The difference between the samples of Examples 9-12 is the first deformation rate PA and the second deformation rate PB. The difference between the samples of Examples 9-12 and the samples of Examples 13 and 14 is the shape of the core material 110 . The core material 110 of the sample of Example 13 has a linear shape. The core material 110 of the sample of Example 14 includes a second portion 132 formed by bending. The second portion 132 is a portion of the covering portion 130 bent so as to protrude in the radial direction of the covering portion 130 . FIG. 17 shows specific test conditions.

In the second test, in order to evaluate the joint strength between the handle portion 10 and the covering portion 130 against torsion, the torque at which the joint between the handle portion 10 and the covering portion 130 is broken (hereinafter "maximum torque") was measured. The method for measuring the maximum torque is as follows. First, the cleaning portion 140 of the core member 110 is fixed to the torque gauge. Next, a torque for rotating the handle portion 10 around the central axis C of the interdental brush 1 is applied to the handle portion 10, and the torque is gradually increased. Torque was measured.

As shown in FIG. 17, it was confirmed that the samples of Examples 9 to 12 and the sample of Example 14 had higher maximum torque than the sample of Example 13. This indicates that when the second portion 132 is formed on the covering portion 130, the joint between the handle portion 10 and the second portion 132 increases the maximum torque. FIG. 18 is a graph showing the relationship between the first deformation rate PA and the maximum torque for the samples of Examples 9-12. FIG. 19 is a graph showing the relationship between the second deformation rate PB and the maximum torque for the samples of Examples 9-12. The maximum torque of the samples of Examples 9-12 is 3.1 times or more that of the sample of Example 13. This is because when the second portion 132 is formed so that at least one of the first deformation rate PA and the second deformation rate PB is within the numerical range exemplified in the embodiment, the second portion 132 is the It shows that a high maximum torque can be obtained even if the portion is not formed by bending like the sample.

A third test will be described. In the third test, the same sample as in the second test was used to confirm the relationship between the degree of plastic working of the covering portion 130 and the moldability of the handle portion 10 . In order to evaluate the moldability of the handle portion 10, N samples of each sample were molded, and the number N1 of the first type samples, the number N2 of the second type samples, and the number N2 of the second type samples included in the N samples were determined. was determined by visual inspection. From the results, the ratio of the number N1 of the first type samples to N (hereinafter "first molding rate P1"), the ratio of the number N2 of the second type samples to N (hereinafter "second molding rate P2" ), and the ratio of the number N3 of the third type samples to N (hereinafter referred to as “third molding rate P3”).

A first-type sample is a sample that satisfies the first evaluation condition. The first evaluation condition is that the covering portion 130 covers the handle portion 10 in a straight state. When the covering portion 130 is straight, the central axis C of the interdental brush 1 and the entire central axis of the covering portion 130 are substantially coaxial. In the first type sample, a straight visible portion 133 can be observed through the opening 50 . Therefore, even when the grip portion 30 is made of opaque resin, it can be confirmed that the first evaluation condition is satisfied.

A second type sample is a sample that satisfies the second evaluation condition. The second evaluation condition is that the covering end portion 110D of the covering portion 130 is offset with respect to the central axis C of the interdental brush 1 in a direction orthogonal to the central axis C, and the covering portion 130 bends with the non-holding portion 122 as a fulcrum. It is that you are. When the handle portion 10 is molded, the force of the resin supplied to the molding space 341 removes the visible portion 133 from between the first convex portion 354 and the second convex portion 364, and the resin hardens in this state. It is believed that a sample of the second type is formed. In the case of the second type sample, when the cover portion 130 has a large deflection amount, the cover portion 130 is not exposed to the opening 50 . In the case of the second type sample, when the amount of deflection of the covering portion 130 is small, a state in which the covering portion 130 is partially curved can be observed through the opening 50 .

A third type sample is a sample that satisfies the third evaluation condition. The third evaluation condition is that the visible portion 133 of the covering portion 130 and the non-holding portion 133 are not offset with respect to the central axis C of the interdental brush 1 in the direction orthogonal to the central axis C. That is, the portion between the portion 122 is bent. Even when resin is supplied to the molding space 341 during molding of the handle portion 10, the visually recognized portion 133 is maintained in a state of being held by the convex portions 354 and 364, and the force of the supplied resin causes the non-holding portion to be held. It is considered that the third type sample is formed by bending the covering portion 130 around the fulcrum 122 and the visible portion 133 and curing the resin in this state. In the third type sample, the visible portion 133 tilted with respect to the central axis C of the interdental brush 1 can be observed through the opening 50 .

FIG. 20 is an example of measurement results under test conditions of N=100. The sample of Example 14 has a lower first molding rate P1 than the samples of Examples 9-13. The reason is considered as follows. Since the second portion 132 in the sample of Example 14 is a bent portion, it gives a large resistance to the flow of the resin supplied to the molding space 341, and the second portion 132 receives a large force from the resin. When the component of the force that the second portion 132 receives from the resin in the direction orthogonal to the central axis of the core material 110 is strong, the visible portion 133 is removed from between the first convex portion 354 and the second convex portion 364, and the second portion 132 A seed sample is formed. When the component of the force that the second portion 132 receives from the resin in the direction along the axial direction of the core material 110 is strong, the second portion 132 is pushed toward the non-holding portion 122 , and the second portion 132 is pushed toward the non-holding portion 122 . A portion between the visual recognition portion 133 and the non-holding portion 122 is bent to form a third type sample.

Although the samples of Examples 9 to 12 also include the second portion 132, the resistance to resin flow is lower than that of the second portion 132 in the sample of Example 14, so relatively favorable results are obtained with respect to the first molding rate P1. is considered to have been obtained. Since the sample of Example 13 does not include the second portion 132, relatively favorable results are obtained with respect to the first molding rate P1.

A fourth test will be described. In the fourth test, the relationship between the position of the second portion 132 in the axial direction of the covering portion 130 and the bonding strength between the handle portion 10 and the covering portion 130 with respect to twisting was confirmed using the samples of Examples 15-24. Samples of Examples 15 to 22 are samples relating to the interdental brush 1 of the embodiment. The samples of Examples 23 and 24, like the sample of Example 13, contain a linear core material 110 . The test conditions are the kind of resin material, the density of the resin material, the melting point of the resin material, the elastic modulus of the resin material, the diameter of the material of the core material 110, the length ZA of the core material 110, the length HX of the covering portion 130, the They are the first deformation rate PA, the second deformation rate PB, and the separation rate PC. FIG. 21 shows specific test conditions.

As shown in the measurement results for the samples of Examples 15-17 and the samples of Examples 19-21, it was confirmed that the smaller the spacing ratio PC, the higher the maximum torque. This is because the torque applied to the cleaning portion 140 of the core member 110 has a long force transmission distance until it is transmitted to the second portion 132, and the torque applied to the core member 110 spreads over a wider range of the core member 110. It is thought that receiving is influenced. However, as shown in the measurement results of the sample of Example 18 and the sample of Example 22, when the length ZA of the core material 110 is equal to or greater than a predetermined length, the maximum torque is not the spacing ratio PC but the core material 110 It was confirmed that it strongly depends on the length ZA of . This is probably because the length ZA of the core member 110 is long, so that the force transmission distance is increased, and the torque applied to the core member 110 is received in a wider range of the core member 110 . In addition, as shown in the measurement results of a set of examples in which the type, density, melting point, and elastic modulus of the resin material are different and the other test conditions are the same, the higher the elastic modulus of the resin material, the higher the maximum torque. confirmed to be higher. The corresponding sets of examples are Examples 15 and 19, Examples 16 and 20, Examples 17 and 21, and Examples 18 and 22.

(Modification)
The above embodiments are examples of forms that the interdental brush according to the present invention can take, and are not intended to limit the forms. The interdental brush according to the present invention can take the form of, for example, the modifications of the above-described embodiments shown below, and combinations of at least two mutually consistent modifications.

The structure of the handle portion 10 can be changed arbitrarily. In the first example, the handle portion 10 does not include the first bendable portion 41 . Even in this case, by bending the neck portion 20, the usage pattern of the interdental brush 1 can be changed in the same manner as in the embodiment. Since the neck portion 20 includes the flat intermediate portion 22, the neck portion 20 can be easily bent even in the handle portion 10 in which the first bending portion 41 is omitted. In the second example, the handle portion 10 does not include the second bendable portion 42 . Even in this case, by bending the grip part 30, the mode of use of the interdental brush 1 can be changed in the same manner as in the embodiment. In the third example, the handle portion 10 does not include the portion to be bent 40 . Even in this case, by bending at least one of the neck portion 20 and the grip portion 30, the mode of use of the interdental brush 1 can be changed as in the embodiment. In the fourth example, the handle portion 10 has a structure in which the neck portion 20 and the grip portion 30 are not distinguished. An example of the structure is a structure in which the shape of the grip portion 30 is uniform or similar in the axial direction of the interdental brush 1 in each cross section of the grip portion 30 perpendicular to the central axis C of the interdental brush 1 .

The configuration of the opening 50 can be changed arbitrarily. In the first example, opening 50 includes only one of first opening 51 and second opening 52 . In the second example, one of the first opening 51 and the second opening 52 included in the opening 50 is provided in the grip portion 30 in the first example. In this case, the length of the covering portion 130 is determined so that the visually recognized portion 133 is positioned on the grip portion 30 . In the third example, at least one of the first opening 51 and the second opening 52 is provided in the grip portion 30 . In this case, the length of the covering portion 130 is determined in the same manner as in the second example. In the fourth example, the shape of the hole formed in the opening 50 is a shape other than a rectangle. Examples are squares, circles, ovals and triangles.

The configuration of the core material 110 can be changed arbitrarily. In a first example, core 110 includes a plurality of second portions 132 . In the second example, the shape of at least one of the plurality of second portions 132 differs from the shape of the other second portions 132 in the first example.

The manufacturing method of the interdental brush 1 can be changed arbitrarily. In one example, the interdental brush 1 is manufactured by a manufacturing method using heat welding as disclosed in Japanese Patent Application Laid-Open No. 9-117324. According to this manufacturing method, first, the handle portion 10 and the brush portion 100 are individually formed. Next, the covering portion 130 of the core material 110 is heated, and the covering portion 130 is inserted into the handle portion 10 in this state. Therefore, the handle portion 10 and the covering portion 130 are welded together.

Reference Signs List 1: interdental brush 10: handle portion 10A: first front face 10B: second front face 20: neck portion 30: grip portion 50: opening 51: first opening 52: second opening 60: partition wall 100: brush Part 110: Core material 200: Filament bundle

Claims (7)

a handle made of a resin material;
a brush portion joined to the handle portion for cleaning between teeth;
The brush part includes a core material and a filament bundle provided on the core material,
The core material includes a covering portion covering the handle portion,
The handle portion includes an opening that allows a portion of the covering portion to be visually recognized, a first handle-constituting portion positioned on the brush portion side with respect to the opening with respect to the axial direction of the interdental brush, and teeth. a second handle-constituting portion located on the side opposite to the brush portion side with respect to the opening with respect to the axial direction of the intermediate brush;
The interdental brush, wherein the first handle component and the second handle component cover the covering portion. a handle made of a resin material;
a brush portion joined to the handle portion for cleaning between teeth;
The brush part includes a core material and a filament bundle provided on the core material,
The core material includes a covering portion covering the handle portion,
The handle portion includes an opening that opens so that a portion of the covering portion can be seen,
The covering portion includes a visible portion visible through the opening, a first covering portion forming portion located on the brush portion side with respect to the visible portion with respect to the axial direction of the interdental brush, and an interdental space. including a second covering portion constituting portion located on the side opposite to the brush portion side with respect to the visible portion with respect to the axial direction of the brush;
The first covering part-constituting part and the second covering part-constituting part are covered by the handle part. The interdental brush. the handle portion includes a first front surface and a second front surface that extend in the longitudinal direction of the handle portion and are provided so as to sandwich a central axis along the longitudinal direction of the handle portion;
The openings include a first opening opening at the first front surface and a second opening opening at the second front surface.
An interdental brush according to claim 1 or 2 . the handle further includes a partition wall formed to partition the first opening and the second opening;
The covering portion is joined to the partition wall
An interdental brush according to claim 3 . The thickness of the partition wall is included in the range of 0.3 to 0.7 mm
An interdental brush according to claim 4 . the handle portion includes a grip portion and a neck portion;
The covering portion covers at least the neck portion,
The opening is provided in the neck
An interdental brush according to any one of claims 1-5 . The opening is provided at an end of the neck portion on the side of the grip portion.
An interdental brush according to claim 6 .

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