JP6787751B2 - Interdental brush - Google Patents

Description

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

The interdental brush includes a handle portion including a grip portion for the user to grip, a core material joined to the handle portion, and a filament bundle flocked on the core material. As an example of a method of joining the handle portion and the core material, a method of heat-welding the caulked portion and the handle portion formed on the core material is known. Patent Document 1 discloses an example of a conventional interdental brush.

Japanese Unexamined Patent Publication No. 9-117324

If a twisting force is applied to the handle portion while the filament bundle is inserted between the teeth, the joint between the handle portion and the core material may be disengaged, and the core material may come off from the handle portion.
An object of the present invention is to provide an interdental brush in which the joint between the handle portion and the core material is hard to come off.

(1) One form of an interdental brush according to the present invention includes a handle portion made of a resin material and a brush portion joined to the handle portion so that the space between teeth can be cleaned, and the brush portion has a core. The material and the filament bundle planted on the core material are included, the core material includes a coating portion coated on the handle portion, and the coating portion is a first portion which has not been subjected to plastic working, and The core material includes a coated end portion which is an end portion included in the covering portion, and the covering portion and the covering portion with respect to the length of the covering end portion are included, including a second portion having a flat shape subjected to plastic working. The ratio of the distance to the second part is included in the range of 55% or less.
When the ratio of the distance between the covering end portion and the second portion to the length of the covering portion is included in the above range, the joint between the handle portion and the core material is disengaged when a twisting force is applied to the handle portion and the core material. The test confirmed that it was difficult.

(2) In an example of the interdental brush, the second portion is provided in a range including the covered end portion.
When the second part is provided in the range including the covered end part of the covering part, the test shows that the joint between the handle part and the core material is more difficult to come off when a twisting force is applied to the handle part and the core material. confirmed.

(3) In an example of the interdental brush, the first deformation rate, which is the ratio of the width of the second portion to the thickness of the first portion, is included in the range of 130 to 150%.
When the first deformation rate is included in the range of 130% or more, it has been confirmed by a test that the joint between the handle portion and the core material is hard to come off when a twisting force is applied to the handle portion and the core material. It was confirmed by the test that the strength of the second portion is secured when the first deformation rate is included in the range of 150% or less.

(4) In an example of the interdental brush, the second deformation rate, which is the ratio of the thickness of the first portion to the thickness of the second portion, is included in the range of 200 to 260%.
When the second deformation rate is included in the range of 200% or more, it has been confirmed by a test that the joint between the handle portion and the core material is hard to come off when a twisting force is applied to the handle portion and the core material. It was confirmed by the test that the strength of the second portion is secured when the second deformation rate is included in the range of 260% or less.

According to the above interdental brush, the joint between the handle portion and the core material is hard to come off.

The first front side perspective view of the interdental brush of an embodiment. The second front side perspective view of the interdental brush of FIG. The front view of the interdental brush of FIG. The side view of the interdental brush of FIG. An enlarged view of the neck portion of FIG. 1 and its surroundings. FIG. 3 is a cross-sectional view taken along the line D6-D6 of FIG. FIG. 4 is a cross-sectional view taken along the line D7-D7 of FIG. An enlarged view of the second part of FIG. 7. An enlarged view of the second part of FIG. The side view regarding the 1st use form of the interdental brush of FIG. The side view regarding the 2nd use form of the interdental brush of FIG. The side view regarding the 3rd use form of the interdental brush of FIG. FIG. 5 is a side view relating to the fourth usage pattern of the interdental brush of FIG. Sectional view of the molded mold. A cross-sectional view showing a state in which a resin material is injected into a mold. A table showing test conditions and measurement results related to the first test. A table showing test conditions and measurement results related to the second test. The graph which shows the relationship between the 1st deformation rate and the maximum torque of FIG. The graph which shows the relationship between the 2nd deformation rate and the maximum torque of FIG. A table showing test conditions and measurement results for the third test. A table showing test conditions and measurement results related to the fourth test.

(Embodiment)
The configuration of the interdental brush 1 will be described with reference to FIGS. 1 to 3.
The interdental brush 1 includes a handle portion 10 and a brush portion 100. The handle portion 10 constitutes the main body of the interdental brush 1. The brush portion 100 is joined to the handle portion 10 so that the space between the teeth can be cleaned. For the interdental brush 1, the axial direction, the width direction, and the thickness direction can be defined. The axial direction of the interdental brush 1 is a 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 in the front view of the interdental brush 1. The thickness direction of the interdental brush 1 is a direction orthogonal to the axial direction of the interdental brush 1 in the side view of the interdental brush 1. The structure of the interdental brush 1 is plane symmetric with respect to the central surface D (see FIG. 4) parallel to the axial direction and the width direction of the interdental brush 1. The central axis C of the interdental brush 1 is included in the central surface 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 portion 10C, and a second end portion 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 surface 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 portion 10C comes into contact with the tissue in the mouth, the impact can be softened. The shape of the second end 10D is approximately hemispherical.

The handle portion 10 further includes a neck portion 20, a grip portion 30, and a bent portion 40. The grip portion 30 is a portion configured so that the user can firmly grip it with a finger. The neck portion 20 is a portion that is relatively thinner than the grip portion 30 so as not to come into contact with the tissue in the mouth. The neck portion 20 includes the first end portion 10C of the handle portion 10. The grip portion 30 includes a second end portion 10D of the handle portion 10. The grip portion 30 is configured so that the user can grip it. The scheduled folding section 40 includes a scheduled folding section 41 and a scheduled folding section 42.

The first bending schedule portion 41 is provided in the neck portion 20. The second bending schedule portion 42 is provided in the grip portion 30. The planned bending portions 41 and 42 are configured to be bendable in order to adjust the insertability of the brush portion 100 with respect to the inter-tooth spacing. Since the neck portion 20 is provided with the first bending planned portion 41, the neck portion 20 can be easily bent. Since the grip portion 30 is provided with the second bending scheduled portion 42, the posture of the brush portion 100 can be adjusted more variously.

The brush portion 100 includes a core material 110, a filament bundle 200, and a cleaning portion 140. The core material 110 holds the filament bundle 200. The cleaning unit 140 is a portion of the brush unit 100 that is directly involved in cleaning between the teeth. The cleaning unit 140 is composed of a portion of the core material 110 in which the filament bundle 200 is flocked (hereinafter referred to as “holding unit 121”) and the filament bundle 200. The filament bundle 200 is composed of a plurality of filaments so that plaque and food residues can be removed from between the teeth. Examples of materials constituting the filament are nylon resin and polybutylene terephthalate resin. The filament bundle 200 is flocked on the core material 110 so as to project radially from the core material 110.

The interdental brush 1 can be used in a plurality of forms. In each usage pattern, the handle portion 10 has a shape corresponding to a portion between teeth to be cleaned. In one example, the plurality of uses of the interdental brush 1 includes the first to fourth uses.

FIG. 10 is a side view of the interdental brush 1 that takes the first usage pattern. The first usage form is mainly suitable for cleaning between the front teeth. In the first usage mode, the planned bending portion 40 is not bent, and the shape of the handle portion 10 is linear.

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

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

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

As shown in FIG. 3, the 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, the opening 50 includes a first opening 51 and a second opening 52 (see FIG. 2). The first opening 51 is open at the first front surface 10A. The second opening 52 is open 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 50 includes the first opening 51 and the second opening 52, the joint 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. Easy to check. Since the opening 50 is provided in the neck 20, it is difficult for the user's finger 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 efficiently manufactured. The type of resin material constituting the handle portion 10 and its physical property value are preferably determined from, for example, the relationship between the strength of the handle portion 10 against fatigue and the bendability of the handle portion 10. Physical property values of resin materials 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 use period of the interdental brush 1.

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

An example of a preferred upper limit of density is 930 kg / m ³ . An example of a more preferable upper limit of density is 928 kg / m ³ . An example of the lower limit of the preferred density is 920 kg / m ³ . An example of a more preferable lower limit of density is 923 kg / m ³ . An example of a preferred range for density is 920-930 kg / m ³ . An example of a more preferred range for density is 923-928 kg / m ³ . An example of a preferred density is 925 kg / m ³ .

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

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

The details of the neck portion 20 will be described with reference to FIGS. 3 and 4.
The 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 a flat shape. The first bending schedule portion 41 is provided in 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 the neck portion 20 are different for each portion of the 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 become narrower from the grip portion 30 side to the intermediate portion 22 side. In the cross section of the neck portion 20 orthogonal to the central axis C of the interdental brush 1, the width LA is larger than the thickness LB. The width LC and thickness LD of the intermediate portion 22 are constant. In the cross section of the neck portion 20 orthogonal to the central axis C of the interdental brush 1, the width LC is larger than the thickness LD.

As shown in FIG. 5, the first bending schedule portion 41 includes one or a plurality of first grooves 41A. In the illustrated example, the first bent portion 41 includes eight first grooves 41A. The first groove 41A is formed so that the neck portion 20 can be bent in the direction in which the protruding portion 120 of the brush portion 100 falls. Each first groove 41A is provided in each of the first front surface 10A and the second front surface 10B. The first grooves 41A are arranged in the axial direction of the interdental brush 1. Each first groove 41A is provided on substantially the entire neck portion 20 in the width direction of the interdental brush 1. Since the first scheduled bending portion 41 includes at least one first groove 41A, the first scheduled bending portion 41 can be easily bent. In the following description, in order to distinguish each first groove 41A, the numbers of the first grooves 41A are determined in order from the first groove 41A formed closest to the grip portion 30.

The width XA and depth HA of the first groove 41A (see FIG. 6) are preferably determined, for example, from the relationship between the ease of bending of the first scheduled 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, a cross section of the handle portion 10 orthogonal to the central surface D of the interdental brush 1 (see FIG. 6). ) Specified above.

The width XA1 of the first first groove 41A is the widest of the width XA of each first groove 41A. The width XA2 of the second first groove 41A is the second widest of the width XA of each first groove 41A. The width XA3 of the third first groove 41A is the third widest of the width XA of each first groove 41A. The widths XA4 of the 4th to 8th first grooves 41A are equal to each other and are the narrowest of the widths XA of the first grooves 41A.

An example of a preferred upper limit of 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 the lower limit of the preferable width XA is 0.3 mm. An example of the lower limit of the more preferable width XA is 0.4 mm. An example of a preferred range for width XA is 0.3-1.2 mm. An example of a more preferred range for width XA is 0.4-1.0 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 a preferred upper limit of 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 preferred lower limit of 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 preferred range for depth HA is 0.1-0.6 mm. An example of a preferred depth HA is 0.1 mm.

The details of the grip portion 30 will be described with reference to FIGS. 3 and 4.
The grip portion 30 includes an upper portion 31, an intermediate portion 32, and a lower portion 33. The shape of the grip portion 30 is 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 a portion between the upper portion 31 and the lower portion 33. The second bending schedule portion 42 is provided in the intermediate portion 32. The grip portion 30 is constricted so that the intermediate portion 32 is thinner than the upper portion 31 and the lower portion 33 in the front view of the interdental brush 1.

As shown in FIG. 3, the second bending schedule portion 42 includes one or more second grooves 42A. In the illustrated example, the second bending schedule 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 protruding portion 120 of the brush portion 100 falls. The second groove 42A is provided in each of the first front surface 10A and the second front surface 10B. The second grooves 42A are aligned in the axial direction of the interdental brush 1. Each second groove 42A is provided so as to make one round of the grip portion 30 around the central axis C of the interdental brush 1. Since the second scheduled bending portion 42 includes at least one second groove 42A, the second scheduled bending portion 42 can be easily bent.

The width XB and depth HB of the second groove 42A (see FIG. 6) are preferably determined, for example, from the relationship between the ease of bending of the second scheduled 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, for example, the cross section of the handle portion 10 orthogonal to the central surface D of the interdental brush 1 (see FIG. 6). ) Specified above.

The width XB of each second groove 42A is the same. An example of a preferred upper limit of 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 the lower limit of the preferable width XB is 0.3 mm. An example of the lower limit of the more preferable width XB is 0.4 mm. An example of a preferred range for width XB is 0.3-0.7 mm. An example of a more preferred range for width XB is 0.4-0.6 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 a preferred upper limit of depth HB is 1.2 mm. An example of a more preferable upper limit of the depth HB is 1.0 mm. An example of the lower limit of the preferred 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 0.2-1.2 mm. An example of a more preferred range for depth HB is 0.3-1.0 mm. An example of a preferred depth HB is 0.5 mm.

The details of the brush unit 100 will be described with reference to FIG.
The core material 110 is composed of wires. Examples of materials that make up wires are stainless steel, ferritic stainless steel, austenitic stainless steel, austenitic ferritic stainless steel, martensite stainless steel, folded-hardened stainless steel, nickel-based alloys, and 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 portion 100 is configured as follows. First, one wire which is a material of the core material 110 is bent to form a bent portion (hereinafter, "bent portion 110P of the core material 110"). As a result, the wire is divided into one portion (hereinafter, "first folded portion 110A of the core material 110") and the other portion (hereinafter, "second folded portion 110B of the core material 110") with respect to the bent portion 110P. The wire.

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

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

The core material 110 includes a protruding portion 120 and a covering portion 130. The protruding portion 120 includes a holding portion 121 and a non-holding portion 122. The holding portion 121 includes a bent portion 110P of the core material 110, and is a portion where the filament bundle 200 is flocked. 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 flocked.

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

The covering portion 130 is a portion covered with the handle portion 10, and includes a first portion 131 and a second portion 132. The first portion 131 is a portion that has not been subjected to plastic working. The second portion 132 is a portion that has been subjected to plastic working. An example of plastic working performed on the second portion 132 is press working. The second portion 132 is formed by pressing a part 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 arbitrarily changed. Other examples of the shape of the second portion 132 are a flat square, a flat circle, a flat ellipse, or a flat triangle. The second portion 132 is provided at an arbitrary position of the covering portion 130 of the core material 110. In a preferred example, the second portion 132 is provided in a range including the coated end 110D of the core material 110. A part of the covering portion 130 (hereinafter referred to as “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 of the first scheduled bending portion 41, the retention of the shape of the neck portion 20 in the bent state, and the strength of the neck portion 20 against fatigue. It is preferable to be determined from. In the illustrated example, the thickness of the first portion 131 is the same as the thickness of the core material 110.

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

The easiness of bending of the first bent portion 41 and the shape retention of the neck portion 20 are related not only to the thickness MA itself of the first portion 131 but also to the core material occupancy rate PX. The core material occupancy rate 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 (see FIG. 6) of the handle portion 10 orthogonal to the central surface D of the interdental brush 1, and the bottom surface and the first groove 41A formed on the first front surface 10A. 2 It is a distance from the bottom surface of the first groove 41A formed on the front surface 10B. The formula for obtaining the core material occupancy rate PX is “PX = MA / PM × 100 (%)”.

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

The degree of deformation of the covering portion 130 due to plastic working can be defined by, for example, 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 from the relationship between, for example, 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. An example of the upper limit of the preferred first deformation rate PA is 150%. An example of a more preferable upper limit of the first deformation rate PA is 145%. An example of the lower limit of the preferred first deformation rate PA is 130%. An example of a more preferable lower limit of the first deformation rate PA is 135%. An example of a preferable range regarding the first deformation rate PA is 130% to 150%. An example of a more preferable range for the first deformation rate PA is 135 to 145%. An example of a preferred first deformation rate PA is 140%.

When the first deformation rate PA is included in the range of 130% or more, the joint between the handle portion 10 and the covering portion 130 is unlikely to come off when a force for twisting the handle portion 10 and the protruding portion 120 is applied to the interdental brush 1. .. When the first deformation rate PA is included in the range of 150% or less, high strength is ensured with respect to the second portion 132. Further, when the interdental brush 1 is manufactured by insert molding, the position of the brush portion 100 with respect to the mold is unlikely to deviate from the specified position.

The second deformation rate PB is preferably determined from, for example, 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. An example of the upper limit of the preferred second deformation rate PB is 260%. An example of a more preferable upper limit of the second deformation rate PB is 250%. An example of the lower limit of the preferred second deformation rate PB is 200%. An example of a more preferable lower limit of the second deformation rate PB is 210%. An example of a preferable range regarding the second deformation rate PB is 200 to 260%. An example of a more preferable range for the second deformation rate PB is 210 to 250%. An example of a preferred second deformation rate PB is 240%.

When the second deformation rate PB is included in the range of 200% or more, the joint between the handle portion 10 and the covering portion 130 is unlikely to come off when a force for twisting the handle portion 10 and the protruding portion 120 is applied. When the second deformation rate PB is included in the range of 260% or less, high strength is ensured for the second portion 132. Further, when the interdental brush 1 is manufactured by insert molding, the position of the brush portion 100 with respect to the mold is unlikely to deviate from the specified position.

Factors other than the first deformation rate PA and the second deformation rate PB are also related to the joint strength between the handle portion 10 and the covering portion 130 against twisting. One example is a separation rate PC and a coverage rate PD. The separation rate PC and the coverage rate PD individually affect the joint strength, and also independently affect the joint strength from the first deformation rate PA and the second deformation rate PB.

The separation rate 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. 6 and 7. 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 coated end portion 110D of the core material 110 and the center point 132A of the second portion 132. The formula for obtaining the separation rate PC is “PC = HY / HX × 100 (%)”.

An example of a preferable range for a separation rate PC is 55% or less. An example of a more preferable range for the separation rate PC is 30% or less. An example of a preferred separation rate PC is 7%. When the separation rate PC is included in the range of 55% or less, the joint between the handle portion 10 and the covering portion 130 is unlikely to come off when a force for twisting the handle portion 10 and the protruding portion 120 is applied to the interdental brush 1.

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 material 110 is the overall dimension of the core material 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 regarding the coverage PD is 40% or more. An example of a more preferable range for coverage PD is 55% or more. An example of a preferred coverage PD is 60%. When the coverage PD is included in the range of 40% or more, the joint between the handle 10 and the cover 130 is unlikely to come off when a force for twisting the handle 10 and the protrusion 120 is applied to the interdental brush 1.

As an example of the factors related to the operability of the interdental brush 1, the protrusion rate PE can be mentioned. The protrusion rate PE is the ratio of the length NA of the neck portion 20 to the length SA of the protrusion 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 portion 20 is the dimension of the neck portion 20 in the axial direction of the interdental brush 1. The formula for obtaining 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 portion 140 into the teeth and the distance between the cleaning portion 140 and the grip portion 30 in the axial direction of the interdental brush 1.

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

When the protrusion rate PE is included in the range of 30% or more, the distance between the grip portion 30 and the cleaning portion 140 becomes long in the axial direction of the interdental brush 1, so that plaque, food residue, etc. adhering to the cleaning portion 140 are present. Hard to stick to the user's hands. Further, since the distance between the opening 50 and the cleaning portion 140 becomes long, it is difficult for plaque or the like adhering to the cleaning portion 140 to penetrate into the opening 50. When the protrusion rate PE is included in the range of 170% or less, the cleaning portion 140 can be easily inserted between the teeth.

The details of the opening 50 and the partition wall 60 will be described with reference to FIG.
The opening 50 includes a hole that opens the visible portion 133 of the covering portion 130 so that it can be visually recognized from the outside of the handle portion 10. Therefore, it can be visually confirmed through the opening 50 whether or not the partition wall 60 and the covering portion 130 are properly joined. As an example of a state in which the partition wall 60 and the covering portion 130 are not properly joined, 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 visible through the opening 50 has teeth. A state in which the interdental brush 1 is significantly biased with respect to the central axis C can be mentioned. When such a state is confirmed, the corresponding interdental brush 1 can be excluded from the shipping target. The first opening 51 includes a hole opened in the base 21 of the neck portion 20 of the first front surface 10A. The second opening 52 (see FIG. 2) includes a hole opened in the base 21 of the neck 20 of the second front surface 10B. The opening area of the holes included in the openings 51 and 52 becomes narrower from the opening of the holes toward the partition wall 60.

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

An example of the upper limit of the preferred minimum opening area is 2.0 mm ² . An example of a more preferable upper limit of the minimum opening area is 1.8 mm ² . An example of the lower limit of the preferred minimum 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 the minimum opening area is 1.0-1.2 mm ² . An example of a more preferred range for the minimum opening area is 1.2-1.8 mm ² . An example of a preferred minimum opening 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 more strongly joined. 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 with respect to 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.

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

The second to fourth usage forms of the interdental brush 1 will be described with reference to FIGS. 11 to 13.
In the second usage mode shown in FIG. 11, the first bending schedule 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 tip portion 23 than the first scheduled bending portion 41 (hereinafter, “first angle θA”) is , Greater than 0 degrees. The first angle θA is preferably included in a range in which the shape of the handle portion 10 is such that the cleaning portion 140 can be easily inserted and removed between the teeth of the molars. An example of a preferable range for the first angle θA is more than 0 degrees and 90 degrees or less. An example of a more preferred range for the first angle θA is 40-60 °. A preferred example of the first angle θA is 40 °.

In the third usage mode shown in FIG. 12, the second bending schedule 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 on the neck portion 20 side of the second scheduled bending portion 42 (hereinafter, “second angle θB”) is , Greater than 0 degrees. The second angle θB is preferably included in a range in which the shape of the handle portion 10 has a high grip and operability, for example. 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 preferred range for the second angle θB is 25-35 °. A preferred example of the second angle θB is 30 °.

In the fourth usage mode shown in FIG. 13, the planned bending portions 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 scheduled bending portion 41 (hereinafter, “third angle θC”) is , Greater than 0 degrees. The third angle θC is preferably included in a range in which, for example, the shape of the handle portion 10 has a shape that allows the cleaning portion 140 to be easily inserted and removed when cleaning between the teeth of the molars. An example of a preferable range for the third angle θC is more than 0 degrees and 80 degrees or less. An example of a more preferred range for the third angle θC is 50-60 °. A preferred example of the third angle θC is 55 °.

The angle (hereinafter referred to as “fourth angle θD”) formed by the central axis C of the handle portion 10 and the central axis CD of the portion of the grip portion 30 on the neck portion 20 side of the planned second bending portion 42 is 0 degrees. Greater than. The fourth angle θD is preferably included in a range in which the shape of the handle portion 10 has a high grip and operability, for example. An example of a preferable range for the fourth angle θD is more than 0 degrees and 30 degrees or less. An example of a more preferred range for the fourth angle θD is 10 to 20 °. A preferred 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.
In one example, the interdental brush 1 is manufactured by insert molding. In the 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 specified position in the mold 300. The mold 300 includes a holding mold 310 and a molding mold 340. The holding mold 310 is a mold for holding the brush portion 100. The molding die 340 is a die for molding the handle portion 10.

The holding type 310 includes a fixed holding type 320 and a movable holding type 330. The fixed holding type 320 includes a first holding portion 321 and a first accommodating 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 accommodating portion 322 includes a recess in which half of the brush portion 100 can be arranged with respect to the central surface D (see FIG. 4) of the interdental brush 1. The movable holding type 330 includes a second holding portion 331 and a second accommodating 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 accommodating portion 332 includes a recess in which half of the brush portion 100 can be arranged with respect to the central surface D (see FIG. 4) of the interdental brush 1.

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

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

In the second step, the brush portion 100 is specifically arranged at a specified position in the holding mold 310 as follows. First, the brush portion 100 is arranged in the open fixed holding type 320. At this time, the non-holding portion 122 of the core material 110 is arranged in the first holding portion 321. Next, the movable holding type 330 is fitted to the fixed holding type 320 so that the closed holding type 310 is constructed. When the closed holding type 310 is configured, the first holding portion 321 and the second holding portion 331 sandwich the non-holding portion 122 of the core material 110. Therefore, the position of the brush portion 100 with respect to the holding mold 310 is determined.

Next, the holding mold 310 is arranged at a position in contact with the fixed molding mold 350 so that the covering portion 130 of the brush portion 100 held by the holding mold 310 is arranged on the fixed molding mold 350. At this time, the visible portion 133 of the covering portion 130 is arranged on the first convex portion 354. Next, the movable mold 360 is fitted to the fixed mold 350 so that the closed mold 340 is constructed. The closed molding die 340 includes a molding space 341, a gate 342, and a seal portion 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 that the molten resin can be supplied to the molding space 341. The seal portion 343 is composed of a first seal portion 353 and a second seal 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 spaced apart from each other (hereinafter, "" The convex parts are opposed to each other with a TA). The convex portion spacing TA is the distance between the end surface 354A of the first convex portion 354 and the end surface 364A of the second convex portion 364 in the closed molding die 340. The end face 354A of the first convex portion 354 and the end face 364A of the second convex portion 364 are a region facing the visible portion 133 in a direction orthogonal to each end face 354A and 364A (hereinafter, "first region") and the same direction. Includes a region that does not face the visible portion 133 (hereinafter, “second region”). The partition wall 60 (see FIG. 5) is formed of resin supplied between the end faces 354A and 364A.

The states of the convex portions 354 and 364 with respect to the visible portion 133 (hereinafter, “opposing state”) are classified into the first to third facing states according to the convex portion spacing TA. By setting the height of each of the convex portions 354 and 364, one of the first to third facing states can be selected. In the first facing state, the convex portion spacing TA is substantially equal to the thickness of the visible portion 133, and the end faces 354A and 364A and the visible portion 133 are in contact with each other without crimping. In the second facing state, the convex portion spacing TA is substantially equal to the thickness of the visible portion 133, and the end faces 354A, 364A and the visible portion 133 are crimped to each other. In the third facing state, the convex portion spacing TA is wider than the thickness of the visible portion 133, and the end faces 354A, 364A and the visible portion 133 do not come into contact with each other.

In the example shown in FIG. 14, the facing states of the convex portions 354 and 364 are the second facing states. Each of the convex portions 354 and 364 holds the visible portion 133 of the covering portion 130, which is a portion 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 portion of the covering portion 130 closer to the gate 342 is held by each of the convex portions 354 and 364, the covering portion 130 becomes more difficult to bend when the resin is injected into the molding space 341.

In the third step shown in FIG. 15, the molten resin is injected into the molding space 341 (see FIG. 14) through the gate 342. The resin supplied around each of the convex portions 354 and 364 forms an opening 50 (see FIG. 5) of the handle portion 10. When the first region of each end face 354A, 364A is in contact with the visible portion 133, a resin is formed between the portion of the visible portion 133 in contact with the first region and the first region of each end face 354A, 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 region of each end face 354A and 364A is not in contact with the visible portion 133, between the visible portion 133 and the first region of each end face 354A and 364A, and between the second region of the end face 354A and the end face 364A. The resin is supplied between the second region and the resin. The resin supplied between the end faces 354A and 364A forms a partition wall 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 comes into contact with the first region. In the fourth step, the handle portion 10 is cooled until the injected resin is cured. In the fifth step, the holding die 310 and the molding die 340 are opened, the interdental brush 1 is taken out from the die 300, and the resin portion corresponding to the gate 342 is cut from the handle portion 10.

Details of the facing states of the convex portions 354 and 364 will be described.
In the first facing state, the first region of each end face 354A, 364A comes into contact with the visible portion 133 so as not to substantially deform the visible portion 133, and the second region of each end face 354A, 364A passes through the gap. Facing each other. Therefore, each of the convex portions 354 and 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 region of each end face 354A, 364A is crimped to the visible portion 133, and the second region of each end face 354A, 364A faces each other through a gap. Therefore, each of the convex portions 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, the covering portion 130, which is a portion on the gate 342 side of the brush portion 100, is held by the convex portions 354 and 364, so that when the resin is injected into the molding space 341, the coating portion 130 is held. The covering portion 130 is hard to bend. Therefore, the moldability of the handle portion 10 is improved. According to the second facing state, since the frictional force between each of the convex portions 354 and 364 and the visible portion 133 is large, the covering portion 130 is more difficult to bend and the moldability of the handle portion 10 is further improved. Further, when the first facing state or the second facing state is formed in the molding die 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 orientation of the brush portion 100 with respect to the mold 300 are stable when the resin is injected into the molding space 341. This point also contributes to improving the moldability of the handle portion 10. Further, according to the first facing state and the second facing state, the portion of the visible portion 133 that comes into contact with the first region of each end surface 354A and 364A is not covered with the partition wall 60 (see FIG. 5), so that it is covered. The visibility of the viewing unit 133 is further enhanced.

In the third facing state, the first regions of the end faces 354A and 364A face the visible portion 133 without contacting the visible portion 133, and the second regions of the end faces 354A and 364A face each other through the gap. There is. According to the third facing state, since the bending range of the covering portion 130 is limited by the end faces 354A and 364A, the covering portion 130 is suppressed from being greatly bent when the resin is injected into the molding space 341. Therefore, the moldability of the handle portion 10 is improved. The range in which the covering portion 130 bends when the resin is injected becomes narrower as the convex portion spacing TA becomes narrower. When the handle portion 10 is formed in the third facing state, the entire visible portion 133 is covered with the partition wall 60 (see FIG. 5). Even in this case, the visibility of the visible portion 133 can be improved 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 and a translucent material, a part of the visible portion 133 is not covered with the partition wall 60, and In any case where the entire visible portion 133 is 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 formed in the third facing state, the partition wall 60 is thicker than when the handle portion 10 is formed in the first facing state and the second facing state, so that the handle portion 10 and the covering portion are formed. The joint strength with 130 is increased.

As described above, the convex portion spacing 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 that the convex portion spacing TA is determined from the relationship with these factors. An example of a preferable convex portion spacing TA determined from the viewpoint of moldability is the spacing at which each end face 354A, 364A and the visible portion 133 are crimped.

(Example)
The first to fourth tests carried out to evaluate the performance of the interdental brush 1 will be described. In each test, a sample of Example and a sample of Comparative Example were used. The sample of the example is a sample regarding 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 in the production of each sample. Although a part of the configuration of the sample of the comparative example is different from that of the interdental brush 1 of the embodiment, the same name and reference numeral are used for the sample of the example and the sample of the comparative example below for convenience of explanation. There is.

The first test will be described. In the first test, the type of resin material constituting the handle portion 10 and the relationship between the physical property value thereof and the strength of the handle portion 10 with respect to fatigue were confirmed using the samples of Examples 1 to 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 material of the core material 110. FIG. 16 shows specific test conditions. The elastic modulus of the samples of Examples 1 to 5 and 7 is the flexural modulus. The elastic modulus of the samples of Examples 6 and 8 is the tensile elastic 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 scheduled portion 41 is scheduled. The number of bends when the portion 41 was broken due to fatigue (hereinafter, "maximum number of bends") was measured. The work of transforming the usage pattern of the handle portion 10 from the first usage pattern to the second usage pattern and then transforming the handle portion 10 into the first usage pattern again was counted as one bending.

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

The second test will be described. In the second test, the relationship between the degree of plastic working of the covering portion 130 and the joint strength between the handle portion 10 and the covering portion 130 with respect to twisting was confirmed using the samples of Examples 9 to 12 and the samples of Comparative Examples 1 and 2. did. The difference between the samples of Examples 5 to 8 is the first deformation rate PA and the second deformation rate PB. The difference between the samples of Examples 9 to 12 and the samples of Comparative Examples 1 and 2 is the shape of the core material 110. The core material 110 of the sample of Comparative Example 1 has a linear shape. The core material 110 of the sample of Comparative Example 2 includes a second portion 132 formed by bending. The second portion 132 is a portion in which a part of the covering portion 130 is bent so as to project 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 twisting, the torque when the joint between the handle portion 10 and the covering portion 130 is disengaged (hereinafter referred to as “maximum torque”) was measured. The method for measuring the maximum torque is as follows. First, the cleaning portion 140 of the core material 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, the torque is gradually increased, and the maximum when the handle portion 10 rotates with respect to the core material 110. The torque was measured.

As shown in FIG. 17, it was confirmed that the samples of Examples 9 to 12 and the sample of Comparative Example 2 had a higher maximum torque than the sample of Comparative Example 1. This indicates that when the second portion 132 is formed on the covering portion 130, the maximum torque is increased by joining the handle portion 10 and the second portion 132. FIG. 18 is a graph showing the relationship between the first deformation rate PA and the maximum torque for the samples of Examples 9 to 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 to 12. The maximum torque of the samples of Examples 9 to 12 is 3.1 times or more the maximum torque of the sample of Comparative Example 1. 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 included in the numerical range exemplified in the embodiment, the second portion 132 is the comparative example 2. It is shown that a high maximum torque can be obtained even if the portion is not formed by bending as in the sample.

The third test will be described. In the third test, the relationship between the degree of plastic working of the covering portion 130 and the moldability of the handle portion 10 was confirmed using the same sample as in the second test. In order to evaluate the moldability of the handle portion 10, N pieces of each sample are molded, and the number N1 of the first type samples, the number N2 of the second type samples, and the third type contained in the N samples. The number of samples N3 was measured by visual inspection. From the results, the ratio of the number of first-class samples N1 to N (hereinafter, "first molding rate P1") and the ratio of the number of second-class samples N2 to N (hereinafter, "second molding rate P2"). ), And the ratio of the number N3 of the third type of sample to N (hereinafter, “third molding rate P3”) was determined.

The first kind of sample is a sample satisfying the first evaluation condition. The first evaluation condition is that the covering portion 130 is covered with the handle portion 10 in a straight state. In the straight state of the covering portion 130, 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, it can be confirmed that the first evaluation condition is satisfied even when the grip portion 30 is composed of the opaque resin.

The second kind of sample is a sample satisfying the second evaluation condition. The second evaluation condition is that the coated end 110D of the covering 130 is offset in the direction orthogonal to the central axis C with respect to the central axis C of the interdental brush 1, and the covering 130 is bent with the non-holding portion 122 as a fulcrum. It is that you are. During molding of the handle portion 10, the visible portion 133 is disengaged from between the first convex portion 354 and the second convex portion 364 by the force of the resin supplied to the molding space 341, and the resin is cured in that state. It is believed that a second type sample is formed. When the amount of deflection of the covering portion 130 is large in the second type sample, the covering portion 130 is not exposed to the opening 50. When the amount of deflection of the covering portion 130 is small in the second type sample, a state in which a part of the covering portion 130 is curved can be observed through the opening 50.

The third kind of sample is a sample satisfying the third evaluation condition. The third evaluation condition is that the visible portion 133 is not held with the visible portion 133 of the covering portion 130 in a state where the visible portion 133 is not offset in the direction orthogonal to the central axis C with respect to the central axis C of the interdental brush 1. The part between the part 122 and the part 122 is bent. At the time of molding the handle portion 10, even when the resin is supplied to the molding space 341, the state in which the visible portion 133 is held by each of the convex portions 354 and 364 is maintained, and the non-holding portion is maintained by the force of the supplied resin. It is considered that the coating portion 130 is bent with the 122 and the visible portion 133 as fulcrums, and the resin is cured in that state to form a third type sample. In the third type of 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 the measurement result under the test condition of N = 100. The sample of Comparative Example 2 has a lower first molding ratio P1 than the samples of Examples 9 to 12 and the sample of Comparative Example 1. The reason can be considered as follows. Since the second portion 132 in the sample of Comparative Example 2 is a bent portion, a large resistance is given 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 in the direction orthogonal to the central axis of the core material 110 is strong in the force received by the second portion 132 from the resin, the visible portion 133 is disengaged from between the first convex portion 354 and the second convex portion 364, and the second A sample of the seed is formed. When the force received by the second portion 132 from the resin has a strong component in the axial direction of the core material 110, the second portion 132 is pushed toward the non-holding portion 122 and is sandwiched between the convex portions 354 and 364. The portion between the visible portion 133 and the non-holding portion 122 is bent to form a third type sample.

The samples of Examples 9 to 12 also contain the second portion 132, but the resistance given to the resin flow is smaller than that of the second portion 132 in the sample of Comparative Example 2, which is a relatively preferable result with respect to the first molding rate P1. Is considered to have been obtained. Since the sample of Comparative Example 1 does not contain the second portion 132, relatively favorable results are obtained with respect to the first molding ratio P1.

The fourth test will be described. In the fourth test, regarding the relationship between the position of the second portion 132 in the axial direction of the covering portion 130 and the joint strength between the handle portion 10 and the covering portion 130 with respect to twisting, the samples of Examples 13 to 20 and Comparative Examples 3 and 4 Confirmed using a sample. The samples of Examples 13 to 20 are samples relating to the interdental brush 1 of the embodiment. The samples of Comparative Examples 3 and 4 include a linear core material 110 as in the sample of Comparative Example 1. 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, 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, and the first. 1 deformation rate PA, 2nd deformation rate PB, and separation rate PC. FIG. 21 shows specific test conditions.

As shown in the measurement results for the samples of Examples 13 to 15 and the samples of Examples 17 to 19, it was confirmed that the smaller the separation rate PC, the higher the maximum torque. This is because the transmission distance of the force until the torque applied to the cleaning portion 140 of the core material 110 is transmitted to the second portion 132 is long, and the torque applied to the core material 110 is in a wider range of the core material 110. It is thought that being able to receive it has an effect. However, as shown in the measurement results of the sample of Example 16 and the sample of Example 20, when the length ZA of the core material 110 is equal to or more than a predetermined length, the maximum torque is not the separation rate PC but the core material 110. It was confirmed that it strongly depends on the length ZA of. It is considered that this is because the transmission distance of the force becomes long due to the long length ZA of the core material 110, and the torque applied to the core material 110 can be received in a wider range of the core material 110. Further, as shown in the measurement results of the set of Examples and Comparative 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 is. It was confirmed that the maximum torque was high. The corresponding sets of Examples and Comparative Examples are Example 13 and Example 17, Example 14 and Example 18, Example 15 and Example 19, and Example 16 and Example 20.

(Modification example)
The above-described embodiment is an example of possible forms of the interdental brush according to the present invention, and is not intended to limit the form. The interdental brush according to the present invention may take, for example, a modification of the above embodiment shown below and a combination of at least two modifications that do not contradict each other.

The configuration of the handle portion 10 can be arbitrarily changed. In the first example, the handle portion 10 does not include the first bending schedule portion 41. Even in this case, the usage pattern of the interdental brush 1 can be changed in the same manner as in the embodiment by bending the neck portion 20. 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 schedule portion 41 is omitted. In the second example, the handle portion 10 does not include the second bending schedule portion 42. Even in this case, the usage pattern of the interdental brush 1 can be changed in the same manner as in the embodiment by bending the grip portion 30. In the third example, the handle portion 10 does not include the bent portion 40. Even in this case, the usage pattern of the interdental brush 1 can be changed in the same manner as in the embodiment by bending at least one of the neck portion 20 and the grip portion 30. In the fourth example, the handle portion 10 has a structure in which the neck portion 20 and the grip portion 30 are indistinguishable. 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 orthogonal to the central axis C of the interdental brush 1.

The configuration of the opening 50 can be arbitrarily changed. In the first example, the opening 50 includes only one of the first opening 51 and the second opening 52. In the second example, in the first 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 this case, the length of the covering portion 130 is determined so that the visible portion 133 is located at 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 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 arbitrarily changed. In the first example, the core material 110 includes a plurality of second portions 132. In the second example, in the first example, the shape of at least one of the plurality of second portions 132 is different from the shape of the other second portion 132.

The manufacturing method of the interdental brush 1 can be arbitrarily changed. In one example, the interdental brush 1 is manufactured by a manufacturing method using heat welding as disclosed in JP-A-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 that state. Therefore, the handle portion 10 and the covering portion 130 are welded together.

1: Interdental brush 10: Handle part 100: Brush part 110: Core material 110D: Covered end part 130: Covered part 131: First part 132: Second part 200: Filament bundle

Claims (8)

The handle part made of resin material and
A brush part joined to the handle part is provided so that the space between teeth can be cleaned.
The brush portion includes a core material and a filament bundle planted on the core material.
The core material includes a covering portion coated on the handle portion, and the core material includes a covering portion.
The covering portion includes a first portion that has not been plastically processed and a flat second portion that has been plastically worked.
The core material includes a coated end portion which is an end portion included in the covering portion.
An interdental brush in which the ratio of the distance between the covering end portion and the center point of the second portion to the length of the covering portion is within the range of 55% or less. The interdental brush according to claim 1, wherein the second portion is provided in a range including the covered end portion. The thickness of the first portion is the maximum thickness of the core material.
The interdental brush according to claim 1 or 2, wherein the first deformation rate, which is the ratio of the width of the second portion to the thickness of the first portion, is in the range of 130 to 150%. The thickness of the first portion is the maximum thickness of the core material.
The interdental brush according to any one of claims 1 to 3, wherein the second deformation rate, which is the ratio of the thickness of the first portion to the thickness of the second portion, is in the range of 200 to 260%. .. The ratio of the distance between the covering end portion and the center point of the second portion to the length of the covering portion is included in the range of 51.8% or less.
The interdental brush according to any one of claims 1 to 4. The ratio of the distance between the covering end portion and the center point of the second portion to the length of the covering portion is included in the range of 13.9% or less.
The interdental brush according to claim 5. The ratio of the distance between the covering end portion and the center point of the second portion to the length of the covering portion is included in the range of 9.1% or less.
The interdental brush according to claim 6. The ratio of the distance between the covering end portion and the center point of the second portion to the length of the covering portion is included in the range of 7% or less.
The interdental brush according to claim 7.

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