JP2023091379A - Brush molded body and toothbrush - Google Patents

Abstract

To provide a brush molded body with a high flexibility in design.SOLUTION: A brush molded body includes a head base part formed of a soft resin and a plurality of filaments extending from a supporting surface positioned on a front side in a thickness direction of the head base part to the front side. The head base part includes a fitting hole which extends in a length direction perpendicular to the thickness direction and opens on one side in the length direction, a base which has a holding surface that is positioned on a front side of the fitting hole and faces the fitting hole and the supporting surface, and at least one structure protruding from the holding surface of the base to a back surface side on the opposite side of the front side in the thickness direction.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to brush moldings and toothbrushes.

An integrally molded toothbrush is proposed that is manufactured using only an injection molding machine (for example, Patent Document 1). Since the integrally molded toothbrush integrally molds the filament and the head base (or head), it does not require filament material procurement and a flocking machine, and has the advantage of being cheaper to manufacture than a flocked toothbrush. .

As for integrally molded toothbrushes, a toothbrush is proposed in which a head portion (brush molding) having filaments and fitting holes and a handle portion provided with a fitting portion at one end are separately molded and then fitted together. (For example, Patent Document 2). Since the brush molding can be attached and detached by the user, it is expected to save resources by replacing it with a new one and reusing the handle portion when the bristles are degraded due to repeated use.

The integrally molded toothbrush has a large contact area between the filament group and the mold during molding. Further, the integrally molded toothbrush strongly adheres to the mold when polyurethane is used as the molding material. For this reason, in the integrally molded toothbrush, the filament group is difficult to release from the mold during molding, and the brush portion tends to be defective in quality due to deformation. In particular, since the cap-type integrally molded toothbrush has a fitting hole, the base supporting the filament group (the area from the filament proximal end to the fitting hole upper surface) has to be made thin at a certain level. Deformation of the brush portion was more likely to occur.

Therefore, Patent Literature 2 discloses that the release resistance applied to the brush portion is uniformed by making the bristle lengths of the filament groups all the same. Deformation of the brush portion is suppressed even when all the bristle lengths arranged in the minor axis direction of the head portion are made to be the same length, instead of making all the bristle lengths of the filament groups the same length.

Further, if the thickness of the base supporting the brush (the area from the base end of the filament to the upper surface of the fitting hole) is less than 2 to 3 mm, deformation of the brush is likely to occur. By increasing the thickness, it is possible to resist mold release resistance. Furthermore, when the gate is disposed on the front end side of the brush molded body and molded, the rear end side of the brush molded body is preferentially filled with the resin, so that pressure is likely to be applied to that portion. In this case, the rear end side of the brush molding tends to be overpacked (overfilled). Therefore, in Patent Document 2, in order to suppress the bad releasability due to the filaments on the rear end side of the brush from affecting the entire brush, a margin is provided without arranging the filaments on the rear end side of the brush molded body. It adopts a configuration to provide

Furthermore, in Patent Document 2, by providing a step on the base, it is possible to release the molded brush from the mold while pressing the outer edge of the base when the molded brush is separated from the mold. In that case, the mold is provided with a pressing mechanism. Deformation of the brush is suppressed by releasing the mold while pressing the outer edge of the base.

On the other hand, in Patent Document 2, the filament shape is a triangular pyramid shape. When the filament has a triangular pyramidal shape, one of the side surfaces is in a positional relationship parallel to the release direction from the standpoint of mold processing. Therefore, there is a method of improving releasability by forming the filament in a pyramidal shape with a draft angle on the entire side surface of the filament, such as a quadrangular pyramidal shape.

Japanese Utility Model Laid-Open No. 61-207233 Chinese Utility Model No. 204561298

The measures to improve the releasability described above have a large impact on the appearance and feeling of use, leading to a decrease in the degree of freedom in design, and have often been a constraint in product development. Therefore, there has been a demand for a solution that enables more flexible design.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a brush molding and a toothbrush having a high degree of freedom in design.

According to the first aspect of the present invention, the head base portion is formed of a soft resin, and the plurality of filaments extends from a support surface located on the front side in the thickness direction of the head base portion toward the front side. , wherein the head base portion includes a fitting hole extending in a length direction perpendicular to the thickness direction and opening on one side of the length direction, and a fitting hole located on the front side of the fitting hole. a base having a holding surface facing the fitting hole and the support surface; A molded brush is provided, characterized by having a structure.

According to a second aspect of the present invention, the brush molded body of the first aspect and a handle body formed of a hard resin and having fitting protrusions detachably attached to the fitting holes of the brush molded body. A toothbrush is provided comprising:

According to a third aspect of the present invention, the molded brush includes the molded brush according to the first aspect, and a handle body having a fitting protrusion that fits into the fitting hole of the molded brush. and the handle body are formed integrally with each other to provide a toothbrush.

The present invention can provide a molded brush and a toothbrush with a high degree of freedom in design.

1 is a front view of a molded brush 20 and a toothbrush 1 according to an embodiment of the present invention; FIG. Fig. 2 is a side view of the molded brush 20 and the toothbrush 1; 3 is a front view of the handle body 10; FIG. FIG. 4 is an enlarged front view of a fitting protrusion 12; 1 is a front view of a brush molding 20 according to a first embodiment; FIG. FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5; FIG. 6 is a cross-sectional view taken along the line BB in FIG. 5; FIG. 8 is a cross-sectional view taken along line CC in FIG. 7; FIG. 3 is a cross-sectional view schematically showing an example of a mold MD for molding the brush molded body 20. FIG. It is an external appearance perspective view of core block SL2. FIG. 4 is a cross-sectional view showing an initial state of mold opening when the brush molded body 20 does not have a structure 31; 3 is a cross-sectional view of a head base portion 21; FIG. FIG. 5 is a cross-sectional view of a brush molded body 20 according to a second embodiment; It is a sectional view of head base part 21 concerning a 2nd embodiment. FIG. 11 is a cross-sectional view orthogonal to the thickness direction of a head base portion 21 according to a third embodiment at a position including a structure 31; It is sectional drawing orthogonal to the width direction in the head base part 21 which concerns on 4th Embodiment. FIG. 11 is a cross-sectional view perpendicular to the width direction of a head base portion 21 according to a fifth embodiment; FIG. 14 is a cross-sectional view perpendicular to the length direction of the head base portion 21 according to the sixth embodiment. FIG. 21 is a cross-sectional view perpendicular to the length direction of the head base portion 21 according to the seventh embodiment; FIG. 21 is an external perspective view of a core block SL2 according to a seventh embodiment; FIG. 21 is a cross-sectional view showing a modification of the structure 31B according to the seventh embodiment; FIG. 21 is a cross-sectional view showing a modification of the structure 31B according to the seventh embodiment; FIG. 21 is a cross-sectional view showing a modification of the structure 31B according to the seventh embodiment;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of brush moldings and toothbrushes of the present invention will be described below with reference to FIGS. 1 to 23. FIG. In this embodiment, an example of a toothbrush in which a brush molded body is detachably provided on a handle body will be described.

The following embodiments show one aspect of the present invention, do not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. In addition, in the drawings below, the actual structure and each structure are different in scale, number, etc., in order to make each structure easier to understand.

FIG. 1 is a front view of a molded brush 20 and a toothbrush 1 according to this embodiment. FIG. 2 is a side view of the brush molding 20 and the toothbrush 1. FIG. The toothbrush 1 includes a rod-shaped handle body 10 and a brush molded body 20. - 特許庁The handle body 10 and the brush molded body 20 are separate members. The brush molded body 20 can be detachably attached (inserted) to the handle body 10 . The brush molding 20 is made of soft resin. The handle body 10 is made of hard resin.

The front surface in this embodiment means that the filament 23 described later is positioned in the thickness direction (hereinafter simply referred to as the thickness direction) which is the normal direction of the support surface 21a (details will be described later) of the brush molded body 20. This is the protruding side (the upper side in FIG. 2). The side opposite to the front side in the thickness direction of the brush molded body 20 is appropriately referred to as the back side. Further, the length direction of the handle body 10 (hereinafter simply referred to as the length direction), and the direction in which the handle body 10 is inserted into the brush molding 20 (hereinafter simply referred to as the insertion direction) is determined by the above method. perpendicular to the line direction. In the length direction, the side on which the handle body 10 is attached to the brush molded body 20 is the rear end side (one side in the length direction), and the side opposite to the rear end side is the tip side (the other side in the length direction). side). The direction orthogonal to the normal direction and the insertion direction is the width direction of the brush molded body 20 (hereinafter simply referred to as the width direction). The longitudinal direction in this embodiment is the direction in which the filaments 23 extend, and is parallel to the normal direction.

FIG. 3 is a front view of the handle body 10. FIG.
As shown in FIG. 3, the handle body 10 includes a bar-shaped handle portion 11 and a fitting protrusion 12 that protrudes toward the distal end side of the handle portion 11 in the longitudinal direction. In the toothbrush 1, by inserting the fitting projection 12 of the handle body 10 into the brush molding 20 described later, the fitting projection 12 is covered with the brush molding 20 and attached.

The handle body 10 is made of hard resin. As an example of the hard resin, a resin having a flexural modulus (JIS K7171) of 1500 MPa or more and 3000 MPa or less can be exemplified. Specific examples include polypropylene resin (PP), polyacetal resin (POM), polyester resin (PCTA), polyethylene terephthalate copolymer (PETG), and high density polyethylene (HDPE). Among these, PP, which is a general-purpose resin, is preferable in consideration of cost, and POM is more preferable in order to secure the strength of the fitting protrusion 12 .

The front view shape of the handle portion 11 of the present embodiment is such that the width gradually narrows from the front end side to the rear end side, then extends with a constant width, and then the width gradually widens and then narrows. It changes curvilinearly. The rear end of the handle portion 11 has a substantially semicircular shape when viewed from the front.

As shown in FIG. 2, the shape of the handle portion 11 when viewed from the side extends from the front end side to the rear end side with a constant width, and then the width gradually widens to the maximum thickness of the finger rest portion. The side view shape of the handle portion 11 changes curvilinearly so that the width gradually narrows from the finger rest portion having the maximum thickness toward the rear end side. As for the side view shape of the handle portion 11, the rear end portion thereof has a substantially semicircular shape.

In addition, in the present invention, the shape of the handle portion 11 is not limited to the shape of this example, and can be appropriately set in consideration of strength, operability, designability, and the like.
The dimensions of the handle portion 11 are not particularly limited and can be set as appropriate. For example, the length of the handle portion 11 can be 100 mm or longer. For example, the length of the handle portion 11 can be 200 mm or less.

The fitting protrusion 12 is a portion that is covered with the brush molding 20 when the brush molding 20 is attached to the handle body 10 . The rear end of the fitting protrusion 12 is the rear end position of the brush molded body 20 when the brush molded body 20 is attached to the handle body 10 .

FIG. 4 is an enlarged front view of the fitting protrusion 12. As shown in FIG. As shown in FIG. 4, the fitting protrusion 12 has a base portion 13 provided on the distal end side of the handle portion 11, a distal end portion 14 provided on the distal end of the base portion 13, a recess 15, and a groove portion 16. are doing. Although illustration is omitted, the base portion 13 and the tip portion 14 have a step in the thickness direction with respect to the handle portion 11 on both the front side and the back side, and are formed with the same thickness that is thinner than the handle portion 11. there is The depressions 15 are provided on both sides in the width direction. The depression 15 has an arcuate shape with an arcuate center on the outside in the width direction and a concave on the inside. The groove 16 is provided on the front side of the fitting protrusion 12 . The groove 16 is arranged in the center of the fitting projection 12 in the width direction and extends in the length direction.

[First embodiment of brush molded body 20]
FIG. 5 is a front view of the brush molding 20 according to the first embodiment. FIG. 6 is a cross-sectional view along line AA in FIG. 7 is a cross-sectional view taken along the line BB in FIG. 5. FIG.
As shown in FIGS. 5 to 7, the brush molded body 20 includes a head base portion 21 having a substantially rectangular shape in front view, and a plurality of filaments 23 provided in front of the head base portion 21. ing.

Various elastomers can be used as the soft resin that constitutes the brush molded body 20, but polyurethane is preferable.
Polyurethane tends to have a higher tensile strength than other elastomers such as styrene and polyester. and the fitting hole 22, and damage during use of the toothbrush 1 can be suppressed.

Polyurethane contains 0.01 to 1.0 wt% (mass%) of C10 or higher saturated/unsaturated hydrocarbons, higher alcohols, fatty acid amides, fatty acid esters, low molecular weight polyethylene, polyethylene glycol (PEG), and fatty acid metal salts. , long-chain fatty acid, fatty acid glycerin, liquid paraffin, or silicone, or a combination thereof, which functions as a lubricant and a release agent.

In addition, polyurethane has a wider selection of hardness than the other elastomers described above, and the resin hardness should be selected according to the thickness of the brush molded body 20 in consideration of its usability (for example, bending of the tip of the brush molded body). It is possible. The hardness of the polyurethane is preferably Shore 90A or more and 70D or less.
If the polyurethane has a hardness lower than Shore 90A, it is likely to be deformed when it is formed with a thin wall. If the hardness of the polyurethane is higher than Shore 70D, pain may occur when the back of the head base portion 21 is tilted and the tip hits the oral tissue. By setting the hardness of the polyurethane to Shore 90A or more and 70D or less, it is possible to prevent the brush molded body 20 from falling off during use of the toothbrush 1 or to prevent pain from being hit by the tip of the head base portion 21 .

As the polyurethane, it is preferable to use an ether-based polyurethane from the viewpoint of ensuring water resistance and antibacterial properties.

The filament 23 has a substantially columnar shape protruding from the support surface 21a of the head base portion 21 toward the front side. The filament 23 has a substantially triangular prism shape with a substantially triangular cross section on the base end side, and a triangular pyramid shape extending from the substantially triangular prism and tapering off on the distal end side. The filaments 23 are arranged in a plurality of rows along the inserting direction so that the rows aligned along the width direction of the brush molded body 20 are shifted by half a pitch in the inserting direction from each other. That is, the filaments 23 are arranged in a zigzag pattern.

As shown in FIG. 7, the filament 23 has a high bristle length in the widthwise center group and a short bristle length in the widthwise outer group. The maximum hair length of the filament 23 is preferably 7 mm or longer, more preferably 9 mm or longer. The maximum hair length of the filament 23 is preferably 15 mm or less, more preferably 13 mm or less. If the maximum length of the filament 23 is less than 7 mm, the ease of cleaning the oral cavity may deteriorate. If the maximum length of the filaments 23 exceeds 15 mm, the releasability of the brush molded body 20 by injection molding is deteriorated.
By setting the maximum length of the filament 23 to 7 mm or more, it is possible to ensure the cleaning performance in the oral cavity. By setting the maximum length of the filament 23 to 15 mm or less, it is possible to secure the releasability during molding.
By setting the maximum length of the filament 23 to 7 mm or more and 15 mm or less, it is possible to secure the cleaning property in the oral cavity and the releasability at the time of molding.

The cross-sectional area of the proximal end of the filament 23 is preferably 0.8 mm ² or less, more preferably 0.6 mm ² or less. If the cross-sectional area of the proximal end of the filament 23 exceeds 0.8 mm ² , the filament 23 becomes difficult to bend, and there is a possibility that the ability to clean gaps between the teeth, the neck, and the like will deteriorate. By setting the cross-sectional area of the base end of the filament 23 to 0.8 mm ² or less, it is possible to ensure cleanability of gaps between teeth, tooth necks, and the like.

The ratio of the total cross-sectional area of the base ends of the plurality of filaments 23 to the area of the support surface 21a of the head base portion 21 is preferably 10% or more. The ratio of the total cross-sectional area of the base ends of the plurality of filaments 23 to the area of the support surface 21a of the head base portion 21 is preferably 50% or less, more preferably 30% or less.
If the ratio of the total cross-sectional area of the proximal ends of the filaments 23 is less than 10%, the cleaning performance in the oral cavity may deteriorate. If the ratio of the total cross-sectional area of the base ends of the filaments 23 exceeds 50%, the releasability of the molded brush 20 by injection molding will be deteriorated.
By setting the ratio of the total cross-sectional area of the base ends of the filaments 23 to 50% or less, it is possible to secure mold releasability during molding.
By setting the ratio of the total cross-sectional area of the proximal ends of the filaments 23 to 10% or more and 50% or less, it is possible to secure the cleaning property in the oral cavity and the releasability during molding.

As the cross-sectional shape of the filament 23, in addition to a substantially triangular shape, a substantially polygonal shape such as a substantially square shape, a substantially circular shape, a substantially star shape, a substantially spatula shape, and the like can be selected. The filament 23 may have a tapered shape with a tapered distal end, or may have a configuration extending straight or a tapered shape tapered from the proximal end. The triangular pyramid has a shape in which one side surface is parallel to the release direction (thickness direction) and the apex is away from the center of the base end. By adopting this shape, it is possible to reduce the number of man-hours required for cutting the mold, thereby reducing the manufacturing cost.

The head base portion 21 has a fitting hole 22 , a base 24 , side walls 25 , a bottom wall 26 , a tip wall 27 and a structure 31 .
The fitting hole 22 extends in the insertion direction and opens at an end face 21b on the rear end side (one side). 8 is a cross-sectional view taken along line CC in FIG. 7. FIG. As shown in FIG. 8 , the fitting hole 22 has a first portion 33 that opens to the end surface 21 b and a second portion 34 that is located on the far side of the first portion 33 . As shown in FIG. 6, the first portion 33 and the second portion 34 are arranged apart from the support surface 21a and the back surface 21c of the head base portion 21, respectively.

The head base portion 21 has a protrusion 35 positioned between a first portion 33 and a second portion 34 in the insertion direction of the fitting hole 22 . The protrusions 35 are provided on both sides of the fitting hole 22 in the width direction. The protrusions 35 are provided at positions where they fit into the recesses 15 when the fitting protrusion 12 of the handle body 10 is inserted into the fitting hole 22 . The projection 35 has an arcuate shape with the center of the arc extending outward in the width direction and protruding inward.

When the fitting projection 12 of the handle body 10 is inserted into the fitting hole 22 of the head base portion 21, the base portion 13 fits into the first portion 33 and the tip portion 14 fits into the second portion 34. , the projection 35 fits into the recess 15 . Thereby, the handle body 10 and the head base portion 21 are integrated.

As shown in FIG. 7 , the base 24 is located on the front side of the fitting hole 22 . The base 24 has a support surface 21a and a holding surface 24a. The holding surface 24 a is located on the back side of the base 24 and faces the fitting hole 22 . The support surface 21a and the holding surface 24a are flat and perpendicular to the thickness direction. The side walls 25 are positioned on both widthwise sides of the fitting hole 22 . The side walls 25 extend from both ends of the base 24 in the width direction toward the rear side.

The bottom wall 26 is located on the back side of the fitting hole 22 . The bottom wall 26 connects the ends of the side walls 25 on the back side. As shown in FIG. 6, the bottom wall 26 gradually extends toward the front side toward the tip side. It is preferable that the distance between the proximal end of the filament 23 positioned most distally and the back surface 21c is 1.5 mm or more. It is preferable that the distance between the proximal end of the filament 23 positioned most distally and the back surface 21c is 3.0 mm or less.
The smaller the distance between the base end of the filament 23 and the back surface 21c, the better the intraoral operability. On the other hand, when the distance between the proximal end of the filament 23 and the back surface 21c is large, the operability is deteriorated.

The tip wall 27 is located on the tip side of the fitting hole 22 . The tip wall 27 connects the tip of the base 24 and the tip of the bottom wall 26 . The fitting hole 22 is formed surrounded by a base 24 , a side wall 25 , a bottom wall 26 and a tip wall 27 .

The structure 31 protrudes from the holding surface 24a of the base 24 toward the rear side. The structure 31 protrudes toward the rear side with a constant width dimension. The widthwise distance of the structure 31 is, for example, 0.5 mm or more. The widthwise distance of the structure 31 is, for example, 5.0 mm or less. As shown in FIGS. 5 and 6, the structure 31 is positioned at the center in the width direction and extends in the length direction with a constant width dimension. The structure 31 has a rectangular parallelepiped shape. The tip side of the structure 31 is connected to the bottom wall 26 and the tip wall 27 . The rear end of the structure 31 is connected to the bottom wall 26 . That is, the structure 31 is connected to the base 24 and the bottom wall 26 in the thickness direction. In this embodiment, a configuration in which one structure 31 is provided is exemplified, but a configuration in which two or more structures 31 are provided at intervals in the width direction may be employed.

FIG. 9 is a cross-sectional view schematically showing an example of a mold MD for molding the brush molded body 20. As shown in FIG.
The mold MD includes a first mold MD1 and a second mold MD2 that move relative to each other in the opening/closing direction (vertical direction in FIG. 9). The first mold MD1 and the second mold MD2 are clamped using the parting surface PL flush with the support surface 21a as a joining surface.

The first mold MD1 is attached to, for example, the fixed side of the injection molding machine, and is filled with molten resin from the injection molding machine. The second mold MD2 is attached to, for example, the movable side of the injection molding machine, and moves in the opening/closing direction (thickness direction of the brush molded body 20) with respect to the first mold MD1, thereby moving the mold MD2. opening and closing is performed.

The first mold MD1 has a molding surface 21aM on which the support surface 21a is molded and a cavity 23M on which the filament 23 is molded when clamped and joined to the second mold MD2.

The second mold MD2 has a cavity 21M in which the head base portion 21 is molded when it is clamped and joined to the first mold MD1, and opens at the tip side of the cavity 21M, and molten resin is introduced into the cavity 21M. and a contact surface 21eM provided at the position of the end surface 21b in the insertion direction and orthogonal to the insertion direction. As the gate portion G, for example, a side gate system is used, but a pinpoint gate system or a tunnel gate system may also be used. The contact surface 21eM extends in the direction away from the PL surface from the position where the back surface of the head base portion 21 is molded in the second mold MD2.

A slide core SL is provided in the second mold MD2. The slide core SL has a main body SL1 and a core block SL2. The core block SL2 is fixed to the parting surface PL side of the main body SL1. The core block SL2 has a core portion 22M in which the fitting hole 22 is formed, and a molding surface 21bM where the core portion 22M protrudes and is orthogonal to the insertion direction. A region of the main body portion SL1 that faces the cavity 21M without contacting the contact surface 21eM constitutes a molding surface 21bM. The molding surface 21bM is separated from the contact surface 21eM before mold clamping.

FIG. 10 is an external perspective view of the core block SL2.
As shown in FIG. 10, the core portion 22M includes a first core portion 33M forming the first portion 33, a second core portion 34M forming the second portion 34, and a third core portion 35M forming the projection 35. and a through groove 31M for forming the structure 31. As shown in FIG. The through groove 31M penetrates the core portion 22M in the opening/closing direction of the mold MD. The through groove 31M is open at the tip in the insertion direction.

In the slide core SL, when the first mold MD1 and the second mold MD2 are clamped, as shown in FIG. 9, part of the molding surface 21bM contacts the contact surface 21eM, and the core portion 22M is positioned to be inserted into cavity 21M. A region of the molding surface 21bM that faces the cavity 21M without coming into contact with the contact surface 21eM is a region for molding the end surface 21b. Further, the slide core SL is designed so that the core portion 22M does not hinder the release of the molded brush molding 20 when the first mold MD1 and the second mold MD2 are opened. The portion 22M moves in the direction (right side in FIG. 9) away from the cavity 21M. The moving direction of the slide core SL is preferably horizontal in order to avoid accidental movement due to its own weight.

In the mold MD described above, the molten resin introduced into the cavity 21M from the gate portion G in a state where the first mold MD1 and the second mold MD2 are clamped together fills the cavity 21M and also fills the cavity 23M. is filled to The molten resin filled in the cavity 21M and the cavity 23M is cooled for a predetermined period of time inside the mold MD to be solidified and the brush molded body 20 is molded.

After that, the mold is opened by moving the second mold MD2 relative to the first mold MD1. At the initial stage of mold opening, the first mold MD1 and the second mold MD2 are separated from each other while the slide core SL does not move. When the first mold MD1 and the second mold MD2 are separated while the slide core SL does not move, the filament 23 is released from the first mold MD1.

The release resistance when the filament 23 is released from the first mold MD1 acts as a pulling force toward the front side on the base 24 of the brush molded body 20 held in the second mold MD2. .

FIG. 11 is a cross-sectional view showing the initial state of mold opening when the brush molding 20 does not have the structure 31. FIG.
As shown in FIG. 11, since the core portion 22M is fitted into the fitting hole 22 in the molded brush molded body 20, the core portion 22M of the head base portion 21 is in contact with the front side. The wall 26, the side wall 25 connected to the bottom wall 26, and the tip wall 27 are held by the core portion 22M of the second mold MD2.

On the other hand, in the head base portion 21, the base 24 is provided with the filament 23, and the inner side of the side wall 25 in the width direction is not held by the core portion 22M. Furthermore, the aggregate of filaments 23 has a large surface area, and the polyurethane used as the molding material has the property of being easily adhered to the mold. Therefore, the central region in the width direction where the filament 23 has a large surface area and the long hair length has a higher release resistance than the outer region in the width direction where the hair length of the filament 23 is short. From the above two points, as shown in FIG. 7, when the filaments 23 are arranged with a dome profile in which the bristle length is high in the group in the center in the width direction and the bristle length is low in the group on the outer side in the width direction, the release resistance is reduced to the brush. It tends to be non-uniform as a whole, and the difference between regions tends to be large. Therefore, if the release resistance of the filament 23 is large relative to the bending strength of the base 24, the tensile force caused by the release resistance may deform the base 24 into a curved surface that bulges toward the front side.

Since the filament 23 is formed along the normal direction of the support surface 21a of the base 24, when the support surface 21a is curved and deformed, the base end of the filament 23 is opened as indicated by the arrow in FIG. A force is applied in a direction that intersects the direction. If the mold opening between the first mold MD1 and the second mold MD2 progresses in this state, the filament 23 may be released from the mold while being handled by the first mold MD1 and may be deformed.

On the other hand, as shown in FIG. 7, in the brush molding 20 of this embodiment, the structure 31 connects the base 24 and the bottom wall 26 . Therefore, the base 24 is held by the core portion 22</b>M via the bottom wall 26 and the structure 31 . In the center of the width direction where the structure 31 is located, the base 24 is prevented from being deformed to expand toward the front side. Therefore, deformation of the filament 23 at the time of mold release is suppressed.

FIG. 12 is a cross-sectional view of the head base portion 21. As shown in FIG. In FIG. 12, illustration of the filament 23 is omitted.
As shown in FIG. 12, the distance in the thickness direction between the support surface 21a and the holding surface 24a (thickness of the base 24) is t1 (mm), and the maximum width of the head base portion 21 is W1 (mm). , the maximum width of the fitting hole 22 is W2 (mm), the maximum distance of the structure 31 in the width direction (width dimension of the structure 31) is V, and the structure 31 and the side wall of the head base portion 21 are separated in the width direction. 25 and the width facing the fitting hole 22 is W3 (mm). Assume that the tensile force caused by the release resistance acts as a uniformly distributed load P on the base 24 supported at both ends by the side walls 25, E is the Young's modulus of the head base 21, and I is the geometrical moment of inertia.

In the head base portion 21 without the structure 31 shown in FIG. 11, if the side wall 25 and the bottom wall 26 held by the core portion 22M are made rigid, the base 24 is deformed with the maximum width W2. The maximum deflection δ1 is represented by the following formula (1).
δ1=(5×P×W2 ⁴ )/(384×E×I) (1).

On the other hand, in the head base portion 21 having the structure 31 shown in FIG. 7, when the side wall 25, the bottom wall 26 and the structure 31 held by the core portion 22M are made rigid, the base 24 is deformed with the maximum width W3. Therefore, the maximum deflection δ2 is expressed by the following equation (2).
δ2=(5×P×W3 ⁴ )/(384×E×I) (2).
Therefore, the ratio of the maximum deflection δ2 of the head base portion 21 having the structural body 31 to the maximum deflection δ1 of the head base portion 21 not having the structural body 31 can be obtained using equations (1) and (2) as follows. (3).
δ2/δ1=(W3/W2) ⁴ (3)

For example, if the distance t1 is 0.4 mm, the maximum width W2 is 8.4 mm, and the width dimension V of the structure 31 is 0.3 mm, the maximum width W3 is 4.05 mm and δ2/δ1 is approximately 0.3 mm. 05. That is, the head base portion 21 having the structure 31 can reduce the deformation caused by the release resistance to about 1/20.

A preferable maximum thickness T of the head base portion 21 is 2.0 mm or more. A preferable maximum thickness T of the head base portion 21 is 5.5 mm or less, and more preferably 4.5 mm or less. By setting the preferable maximum thickness T of the head base portion 21 within the above range, the operability in the oral cavity can be enhanced.
The maximum thickness t2 of the fitting hole 22 (that is, the maximum height t4 of the structure 31) (mm) is preferably 1.0 mm or more. The maximum thickness t2 (mm) is preferably 2.5 mm or less.
The maximum thickness t3 (mm) of the bottom wall 26 is preferably 0.5 mm or more. The maximum thickness t3 (mm) of the bottom wall 26 is preferably 2.0 mm or less.

The distance t1 is preferably 0.4 mm or more, more preferably 0.5 mm or more, and even more preferably 0.8 mm or more. The distance t1 is preferably 2.0 mm or less, more preferably 1.5 mm or less, and even more preferably 1.2 mm or less.
If the distance t1 is less than 0.4 mm, the fluidity of the resin is lowered, and there is a possibility that the filament 23 may be defective in molding due to unfilled filaments. If the distance t1 exceeds 2.0 mm, the size of the head base portion 21 is increased and the intraoral operability is deteriorated.
By setting the distance t1 to 0.4 mm or more, molding defects in the filament 23 can be suppressed. Good intraoral operability can be ensured by setting the distance t1 to 2.0 mm or less.
By setting the distance t1 to be 0.4 mm or more and 2.0 mm or less, it is possible to ensure good intraoral operability while suppressing molding defects in the filament 23 .

As described above, in the brush molded body 20 of the present embodiment, the deformation of the base 24 can be reduced by providing the structure 31 protruding from the holding surface 24a of the base 24 toward the rear side. Therefore, in the brush molded body 20 of the present embodiment, it is not necessary to take a specification measure that greatly affects the appearance and feeling of use in order to suppress the deformation of the filaments 23, and it is possible to design with a high degree of freedom. .

[Second embodiment of brush molded body 20]
Next, a second embodiment of the brush molding 20 will be described with reference to FIGS. 13 and 14. FIG.
In these figures, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

FIG. 13 is a cross-sectional view of the brush molding 20 according to the second embodiment.
As shown in FIG. 13, the brush molding 20 of this embodiment has a structure 31A.
31 A of structures protrude toward the back side from the holding surface 24a of the base 24. As shown in FIG. 31 A of structures protrude toward a back side by a fixed width dimension. The structural body 31A is positioned in the center in the width direction and extends in the length direction with a constant width dimension. The back side end of the structure 31A is separated from the bottom wall 26 . In the core portion 22M of the core block SL2, a groove extending in the insertion direction and recessed from the front side to the back side is provided for forming the structure 31A.
Other configurations are the same as those of the first embodiment.

In the brush molded body 20 of the present embodiment, the structure 31A functions as a beam connected to the bottom wall 26 and the tip wall 27 on the tip side of the base 24, and compared with the case without the structure 31A. , the deformation of the base 24 due to the tensile force caused by the release resistance of the filament 23 can be suppressed, and the deformation of the filament 23 can be suppressed. Therefore, in the brush molded body 20 of the present embodiment, functions and effects similar to those of the first embodiment can be obtained.

In the brush molded body 20 of this embodiment, the cross section of the structure 31A is added to the cross section of the base 24. As shown in FIG. Therefore, the geometrical moment of inertia corresponding to the T-shaped cross section of the base 24 and the structure 31A with the structure 31A is larger than the rectangular cross section of the base 24 without the structure 31A. .

FIG. 14 is a cross-sectional view of the head base portion 21 according to the second embodiment. In FIG. 14, illustration of the filament 23 is omitted.
As shown in FIG. 14, for example, the distance t1 between the base 24 and the base 24 is set to 0.4 mm, the maximum width W2 is set to 8.4 mm, the width dimension V of the structure 31A is set to 3.0 mm, and the structure 31A (the amount of protrusion from the holding surface 24a to the back side) t4 is 0.3 mm, the geometrical moment of inertia in the base 24 is I1, and the geometrical moment of inertia in the base 24 and the structure 31A is I2. . In this case, the geometrical moment of inertia I1 of the rectangular cross section is about 0.0448, and the geometrical moment of inertia I2 of the T-shaped cross section is about 0.1385. Therefore, the ratio (I2/I1) of the geometrical moment of inertia I2 of the head base portion 21 having the structural body 31 to the geometrical moment of inertia I1 of the head base portion 21 not having the structural body 31 is approximately 3.5. 1. That is, the head base portion 21 can reduce the deformation caused by the mold release resistance to approximately ⅓ by having the structure 31A.

S1 (mm ² ) is the area of the structure 31A on the same surface as the holding surface 24a, and S2 (mm ² ) is the area of the fitting hole 22 including the intersection with the structure 31A. The value represented by 100(%) is preferably 10% or more. The value represented by (S1/S2)×100(%) is preferably 40% or less, more preferably 30% or less, and even more preferably 20% or less.

If the value represented by (S1/S2)×100(%) is less than 10%, the width dimension or length dimension of the structure 31A is shortened. There is a possibility that the force to suppress is not sufficient. If the value represented by (S1/S2)×100(%) exceeds 40%, the cooling and solidification of the resin becomes nonuniform between the portion of the base 24 that intersects the structure 31A and the portion that does not intersect. , a molding defect called a sink mark is likely to occur at a portion of the base 24 intersecting with the structure 31A.
By setting the value represented by (S1/S2)×100(%) to 10% or more, a sufficient force for suppressing deformation of the base 24 can be secured. By setting the value represented by (S1/S2)×100(%) to 40% or less, molding defects can be suppressed.
By setting the value represented by (S1/S2)×100(%) to 10% or more and 40% or less, it is possible to suppress molding defects while sufficiently securing the force to suppress deformation of the base 24. become.

The area S1 of the structure 31A is preferably 10 mm ² or more. The area S1 of the structure 31A is preferably 70 mm ² or less.
The area S2 of the holding surface 24a is preferably 60 mm ² or more. The area S2 of the holding surface 24a is preferably 200 mm ² or less. Further, when the area of the support surface 21a is S5 (mm ² ), the value represented by (S1/S5)×100(%) is preferably 5% or more. The value represented by (S1/S5)×100(%) is preferably 30% or less, more preferably 20% or less, and even more preferably 15% or less.

Assuming that the cross-sectional area of the structure 31A perpendicular to the length direction is S3 (mm ² ) and the cross-sectional area of the fitting hole 22 perpendicular to the length direction is S4 (mm ² ), (S3/S4)×100 ( %) is preferably 5% or more. The value represented by (S3/S4)×100(%) is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less.
However, when the structure 31A in the length direction is tapered in the width direction and tapers toward the tip side, (S3/S4) × 100 (% ) should be within the above range.

If the value represented by (S3/S4)×100(%) is less than 5%, the width dimension or height dimension of the structure 31A is shortened. There is a possibility that the force to suppress is not sufficient. When the value represented by (S3/S4)×100(%) exceeds 30%, the cross-sectional area of the core portion 22M in the slide core SL is greatly reduced, so it is difficult to ensure the strength of the steel material forming the core portion 22M. become difficult. Further, when the value represented by (S3/S4)×100(%) exceeds 30% and the width dimension of the structure 31A is long, the difference between the portion of the base 24 that intersects the structure 31A and the portion that does not intersect with the structure 31A. The cooling and solidification of the resin becomes non-uniform between them, and a molding defect called a sink mark is likely to occur at a portion of the base 24 intersecting the structure 31A.
By setting the value represented by (S3/S4)×100(%) to 5% or more, it is possible to secure a sufficient force for suppressing deformation of the base 24 . By setting the value represented by (S3/S4)×100(%) to 30% or less, it is possible to suppress molding defects while sufficiently ensuring the strength of the steel material forming the core portion 22M.
By setting the value represented by (S3/S4)×100(%) to 5% or more and 30% or less, the force to suppress the deformation of the base 24 and the strength of the steel material forming the core portion 22M are sufficiently secured. At the same time, it becomes possible to suppress molding defects.

The cross-sectional area S3 of the structure 31A is preferably 0.5 mm ² or more. The cross-sectional area S3 of the structure 31A is preferably 10 mm ² or less.
The cross-sectional area S4 of the fitting hole 22 is preferably 8 mm ² or more. The cross-sectional area S4 of the fitting hole 22 is preferably 24 mm ² or less.
The height of the structure 31A is preferably 0.5 mm or more. The height of the structure 31A is preferably 2.5 mm or less.

In the above-described first and second embodiments, the structures 31 and 31A have a constant width dimension in the length direction, but the structure is not limited to this. The width dimension of the structures 31 and 31A may be configured to gradually increase toward the distal end side in the length direction.
In the case of adopting this configuration, the groove portion of the core portion 22M in the slide core SL for molding the structures 31 and 31A is inclined as a draft with respect to the sliding direction of the slide core SL, so that the slide core SL slides. Improves mobility.

Furthermore, in the case of adopting this configuration, the opening on the tip side where the gate portion G is arranged becomes large, and the filling property of the resin introduced from the tip side through the gate portion G can be improved. By improving the filling property of the resin, molding conditions can be relaxed, and overfilling of the resin can be suppressed, which contributes to improving the releasability of the filament 23 .

[Third embodiment of brush molded body 20]
Next, a third embodiment of the brush molding 20 will be described with reference to FIG.
In this figure, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

15 is a cross-sectional view in the thickness direction at a position including the structure 31. FIG.
As shown in FIG. 15 , the width of the head base portion 21 located outside the fitting hole 22 in the width direction gradually increases from the rear end side to the front end side.
Other configurations are similar to those of the first embodiment.

In this embodiment, in addition to obtaining the same actions and effects as in the first embodiment, in the cavity 21M in which the head base portion 21 is molded, the volume of the space on the front end side is reduced to that of the space on the rear end side. Since it can be made larger than the volume, the fluidity of the resin is improved when the gate portion G is arranged on the tip side, so that it becomes possible to perform molding by filling the resin at low speed and low pressure. As a result, in the brush molded body 20, deformation of the filaments 23 can be suppressed particularly on the rear end side where overfilling tends to occur.

[Fourth Embodiment of Brush Molded Body 20]
Next, a fourth embodiment of the brush molding 20 will be described with reference to FIG.
In this figure, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

FIG. 16 is a cross-sectional view perpendicular to the width direction of the head base portion 21 according to the fourth embodiment. As shown in FIG. 16, the thickness dimension of the base 24 gradually increases from the front end side to the rear end side.
Other configurations are similar to those of the first embodiment.

When the gate portion G is arranged on the front end side, the resin is introduced into the cavity 21M from the front end side during molding. Easy to concentrate pressure. As a result, overfilling tends to be induced at the end on the rear end side, and the releasability of the filament 23 tends to deteriorate. In this embodiment, in addition to obtaining the same functions and effects as in the first embodiment, the thickness dimension of the base 24 gradually increases from the front end side to the rear end side. Releasability of the filament 23 can be improved by reducing the pressure at the ends.

On the other hand, if the thickness dimension of the head base portion 21 is increased, the operability in the oral cavity is deteriorated when the toothbrush is used as a toothbrush to reach a narrow space such as a back tooth. Therefore, by gradually increasing the thickness dimension of the base 24 from the front end side to the rear end side, deformation of the filament 23 can be suppressed while suppressing deterioration of intraoral operability.

[Fifth embodiment of brush molded body 20]
Next, a fifth embodiment of the brush molding 20 will be described with reference to FIG.
In this figure, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

FIG. 17 is a cross-sectional view perpendicular to the width direction of the head base portion 21 according to the fifth embodiment. As shown in FIG. 17 , the head base portion 21 has a second structure 32 . The second structure 32 protrudes from the support surface 21a to the front side. The height of the second structure 32 is preferably 0.5 mm or more. The height of the second structure 32 is preferably 3.0 mm or less. The second structure 32 is arranged on the rear end side of the plurality of filaments 23 . The shape of the second structure 32 when viewed from the rear end side is not particularly limited, and a rectangular shape, a trapezoidal shape, a semicircular shape, or the like can be selected. The shape of the second structure 32 when viewed in the width direction is not limited to the rectangular shape shown in FIG.

In this embodiment, since the second structure 32 is arranged on the rear end side of the plurality of filaments 23, by increasing the thickness of the head base portion 21 only at the rear end portion where deformation is likely to occur, In addition, it is possible to resist the tensile force at the deformation-prone site and prevent the deformation of the brush part without affecting the operability in the oral cavity.

[Sixth embodiment of brush molded body 20]
Next, a sixth embodiment of the brush molded body 20 will be described with reference to FIG.
In this figure, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

FIG. 18 is a cross-sectional view perpendicular to the longitudinal direction of the head base portion 21 according to the sixth embodiment. As shown in FIG. 18, the holding surface 24a facing the fitting hole 22 gradually curves toward the rear side and extends outward in the width direction from the structure 31. As shown in FIG.

In the present embodiment, since the thickness dimension of the base 24 in the head base portion 21 increases toward the outer side in the width direction from the structure 31, the cross section of the base 24 at the outer side of the structure 31 in the width direction The next moment increases. Therefore, in the present embodiment, the deformation of the base 24 due to the tensile force caused by the release resistance can be reduced without increasing the thickness of the head base 21 . As a result, in the present embodiment, it is possible to improve the releasability of the filament 23 while suppressing deterioration of intraoral operability.

[Seventh embodiment of brush molded body 20]
Next, a seventh embodiment of the brush molding 20 will be described with reference to FIG.
In this figure, the same reference numerals are assigned to the same elements as those of the first embodiment shown in FIGS. 1 to 12, and the description thereof will be omitted.

FIG. 19 is a cross-sectional view perpendicular to the longitudinal direction of the head base portion 21 according to the seventh embodiment. As shown in FIG. 19, the brush molding 20 of this embodiment has a structure 31B. The structure 31B protrudes from the holding surface 24a of the base 24 toward the rear side. The rear end of the structure 31B is separated from the bottom wall 26 .

Regarding the cross-sectional area perpendicular to the thickness direction, the structural body 31B includes a first region 31C having a first cross-sectional area and a second cross-sectional area located on the back side of the first region 31C and having a larger cross-sectional area than the first region 31C. and a second region 31D having a cross-sectional area of . The width dimension of the structure 31B gradually increases toward the back side. The cross-sectional shape of the structure 31B is a trapezoid having an inclined surface 30 extending outward in the width direction toward the rear side.

Assuming that the width dimension of the structural body 31B on the same surface as the holding surface 24a is V1 (mm) and the width dimension of the structural body 31B at the end on the back side is V2 (mm), the second region 31D having the width dimension V2 is , located on the back side of the first region 31C having the width dimension V1.

Therefore, in the structure 31B, if an arbitrary position located on the front side of the rear end portion is the first area 31C, the area located on the back side of the first area 31C is the second area 31D. For example, in the structural body 31B, if the position of the holding surface 24a in the thickness direction is the first area 31C, the area located on the back side of the holding surface 24a in the thickness direction is the second area 31D.

FIG. 20 is an external perspective view of a core block SL2 according to the seventh embodiment.
As shown in FIG. 20, the core portion 22M has through grooves 31BM forming the structure 31B.
In the core portion 22M of the core block SL2, a groove portion 31BM extending in the insertion direction and recessed from the front side to the back side is provided for forming the structure 31B. The core portion 22M has inclined surfaces 30M facing the groove portion 31BM on both sides in the width direction. The inclined surface 30M forms the inclined surface 30. As shown in FIG. The inclined surface 30M extends outward in the width direction toward the rear side.

In this embodiment, immediately after the molded brush 20 is molded, the inclined surface 30M of the core portion 22M comes into contact with the inclined surface 30 from the front side, as shown in FIG. At the time of mold opening, a tensile force is applied to the base 24 due to release resistance when the filament 23 is released from the first mold MD1. At this time, the inclined surface 30 of the structure 31B projecting from the base 24 to the rear side is restricted from moving to the front side by being in contact with the inclined surface 30M of the core portion 22M from the front side. Therefore, the structure 31B is considered rigid against tensile forces due to mold release resistance.

Therefore, the base 24 is restrained from deforming at the portion crossing the structure 31B in the width direction, and is positioned between the structure 31B and the side wall 25 in the width direction similarly to the base 24 shown in FIG. The deformation occurs at the maximum width W3 that the fitting hole 22 faces. Therefore, in this embodiment, compared to the case where the base 24 is deformed by the maximum width W1 in the width direction, the maximum deflection against the tensile force caused by the release resistance can be greatly reduced. Therefore, in the brush molded body 20 of the present embodiment, it is not necessary to take a specification measure that greatly affects the appearance and feeling of use in order to suppress the deformation of the filaments 23, and it is possible to design with a high degree of freedom. .

Furthermore, in the brush molded body 20 of the present embodiment, since the position in the thickness direction where the structure 31B contacts the core portion 22M is close to the base 24, the structure 31B itself is affected by the tensile force caused by the release resistance. elongation is also minimized. As a result, in the brush molded body 20 of the present embodiment, there is no need to take measures for specifications that greatly affect the appearance and feeling of use in order to more effectively suppress the deformation of the filaments 23, and the brush molded body 20 has a higher degree of freedom. design becomes possible.

The configuration of the structure 31B having a second region having a second cross-sectional area larger than the first cross-sectional area in the first region is not limited to the trapezoidal cross-sectional shape described above.
For example, as shown in FIG. 21 , a structure 31</b>E having a rear end connected to the bottom wall 26 may be used.
In this configuration, even at the end of the structure 31E on the back side, the core portion 22M via the bottom wall 26 can restrict the movement to the front side due to the tensile force caused by the release resistance.

Further, for example, as shown in FIG. 22, a first region 31C having a constant width dimension is arranged on the front side, and a second region 31D having a width dimension that increases toward the back side is arranged on the back side. A structure 31</b>F may be provided in which the end of the region 31</b>D is connected to the bottom wall 26 .
Also in this configuration, the same functions and effects as those of the structure 31E shown in FIG. 21 can be obtained.

Further, for example, as shown in FIG. 23, a first region 31C whose width dimension linearly increases toward the back side is arranged on the front side, and a curved surface whose width dimension increases curvilinearly toward the back side. A structure 31G may be provided in which the second region 31D forming the .
In this configuration, the direction of the normal force on the curved surface of the second region 31D is closer to the direction opposite to the direction in which the tensile force due to the mold release resistance applied to the structure 31G acts, so the structure is stronger. can hold the position of the structure 31G in the thickness direction.

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples, and can be carried out with appropriate modifications within the scope of the invention.

(Examples 1 to 6, Comparative Example 1)
Samples of toothbrushes having brush moldings were produced according to the specifications shown in [Table 1]. As shown in the cross-sectional shape items in Table 1, a toothbrush having the structure of the seventh embodiment shown in FIG. 21 was used as a sample of Example 1. Toothbrushes having the structure of the first embodiment shown in FIG. 7 were used as samples of Examples 2 and 4-6. A toothbrush having the structure of the second embodiment shown in FIG. 13 was used as a sample of Example 3. A toothbrush without a structure was used as a sample of Comparative Example 1. In each sample, the maximum length dimension of the head base portion was set to 20.3 mm, and the maximum length dimension of the fitting hole was set to 18.3 mm. Among the resins constituting each sample, thermoplastic polyurethane (TPU) was used as the resin for the molded brush, and polyacetal resin (POM) was used as the handle portion.

[Evaluation method]
The samples of Examples 1 to 6 and Comparative Example 1 were evaluated in terms of "filament deformation due to release resistance" and "intraoral operability".

(1) Method for evaluating filament deformation due to release resistance Ten brush molded articles molded under the same conditions were visually evaluated according to the following criteria.
5 points: No defects in appearance are observed.
4 points: Deformed in the range of 0.5 to 3 mm from the filament tip.
3 points: The entire filament is deformed, but the base is not deformed.
2 points: The entire filament and the base are deformed.
1 point: The entire brush portion and the base are greatly deformed, and some filaments are broken at the base end.
Then, the average value of the 10 evaluation points was obtained, and evaluation was performed according to the following four stages.
A (double circle mark): 4.5 or more and 5.0 or less points.
○ (circle mark): 3.5 or more and less than 4.5 points.
Δ (triangle mark): 2.5 or more and less than 3.5 points.
x (cross mark): less than 2.5 points.

(2) Evaluation method of intraoral operability A sensory evaluation was performed by 10 expert panelists, and the ease of polishing the entire oral cavity during brushing (especially the ease of polishing the back teeth) was evaluated according to the following criteria. .
5 points: Very easy to polish.
4 points: Slightly easy to polish.
3 points: Neither.
2 points: Slightly difficult to polish.
1 point: Very difficult to polish.
Then, an average value of evaluation points by 10 expert panelists was obtained, and evaluation was performed according to the following four grades.
A: 4.5 or more and 5.0 or less points.
○: 3.5 or more and less than 4.5 points.
Δ: 2.5 or more and less than 3.5 points.
×: Less than 2.5 points.

As shown in Table 1, the samples of Examples 1 to 6 having structures were evaluated favorably in both "filament deformation due to release resistance" and "intraoral operability." The samples of Examples 1 to 5, in which the maximum thickness T of the head base portion was 4.0 mm or less, were evaluated particularly well for "intraoral operability." In addition, in the samples of Examples 1 and 5 to 6, in which the distance (thickness of the base) t1 from the filament proximal end to the fitting hole holding surface is 1.0 mm or more, the "deformation of the filament due to the release resistance" A particularly good evaluation was obtained. The sample of Example 1, in which the position in the thickness direction where the structure is in contact with the core portion is closest to the base, obtained the highest score for the evaluation of "filament deformation due to release resistance."

On the other hand, the sample of Comparative Example 1, which does not have a structure, did not give a good evaluation of "filament deformation due to release resistance".

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. The various shapes, combinations, etc., of the constituent members shown in the above examples are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, the toothbrush 1 is composed of the separately molded brush molding 20 and the handle body 10, and the fitting projection 12 of the handle body 10 is fitted into the fitting hole 22 of the brush molding 20. Although the configuration in which the brush molded body 20 is attached to the handle body 10 is illustrated, it is not limited to this configuration. For example, after the handle body 10 is formed by primary molding using a first mold, the brush molded body 20 is formed by secondary molding using a second mold in which the fitting protrusion 12 of the handle body 10 is installed. may be configured to be insert-molded. By this insert molding, it is possible to obtain the toothbrush 1 as a molding in which the fitting protrusion 12 is fitted in the fitting hole 22 and the brush molding 20 and the handle body 10 are integrally molded.

In addition, in the above-described embodiment, the structure in which the handle body 10 is formed of a hard resin is exemplified, but the structure is not limited to this structure. configuration may be used. When this configuration is adopted, it is possible to improve decorativeness and grip.

DESCRIPTION OF SYMBOLS 1... Toothbrush 10... Handle body 20... Brush molding 21... Head base part 21a... Support surface 21b... End surface 22... Fitting hole 23... Filament 24... Base 24a... Holding surface , 31, 31A, 31B, 31E, 31F, 31G... structure, 31C... first area, 31D... second area

Claims (11)

a head base made of soft resin;
a plurality of filaments extending toward the front side from a support surface located on the front side in the thickness direction of the head base;
has
The head base portion
a fitting hole extending in a length direction orthogonal to the thickness direction and opening on one side of the length direction;
a base having a holding surface positioned on the front side of the fitting hole and facing the fitting hole and the supporting surface;
A brush molded body, comprising one or more structures protruding from the holding surface of the base toward the back side opposite to the front side in the thickness direction. S1 is the area of the structure on the same plane as the holding surface,
Assuming that the area of the holding surface is S2,
The value represented by (S1/S2) × 100 (%) is 10% or more and 40% or less.
The brush molding according to claim 1. S3 is the cross-sectional area of the structure perpendicular to the length direction,
Assuming that the cross-sectional area of the fitting hole perpendicular to the length direction is S4,
The value represented by (S3/S4) × 100 (%) is 5% or more and 30% or less.
The molded brush according to claim 1 or 2. The distance from the base end of the filament to the holding surface is 0.4 mm or more and 2.0 mm or less.
The molded brush according to any one of claims 1 to 3. The structure is
a first region having a first cross-sectional area with respect to a cross-sectional area of the structure perpendicular to the thickness direction;
a second region positioned closer to the back side than the first region and having a second cross-sectional area larger than the first cross-sectional area;
having
The molded brush according to any one of claims 1 to 4. The width dimension of the head base portion located outside the fitting hole in the width direction orthogonal to the thickness direction and the length direction is from the one side to the other side in the length direction. gradually increases with
The molded brush according to any one of claims 1 to 5. The thickness dimension of the base in the thickness direction gradually increases from the other side in the length direction toward the one side.
The molded brush according to any one of claims 1 to 6. Having a second structure disposed on the one side in the length direction of the plurality of filaments and protruding from the support surface to the front side,
The brush molding according to any one of claims 1 to 7. The holding surface facing the fitting hole extends gradually toward the back side as it goes outward from the structure in a width direction orthogonal to the thickness direction and the length direction.
The molded brush according to any one of claims 1 to 8. a brush molding according to any one of claims 1 to 9;
A toothbrush, comprising: a handle body made of a hard resin and having a fitting protrusion detachably attached to the fitting hole of the brush molded body. a brush molding according to any one of claims 1 to 9;
a handle body having a fitting protrusion that fits into the fitting hole of the brush molding,
A toothbrush, wherein the brush molding and the handle are integrally molded.

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