TW202228554A - Brush molded body, and toothbrush - Google Patents

Abstract

The objective of the present invention is to provide a brush molded body which has a gentle touch feeling, and with which it is possible to improve the feel during use and the external appearance of a toothbrush. This brush molded body includes a head base portion formed from a soft resin, and a plurality of filaments which project from a supporting surface positioned on the front side in the thickness direction of the head base portion. The head base portion has an engaging hole which extends in a length direction perpendicular to the thickness direction and which opens on one side in the length direction. The brush molded body is provided with: a premolded body, at least a portion of which is molded using a first resin composition, and which comprises a filament group including at least a portion of the plurality of filaments, and a supporting base portion that supports a base portion of the filament group and that is positioned on the front side of the engaging hole to form a portion of the head base portion; and a base main body molded body which includes part of the head base portion and the plurality of filaments other than the premolded body, and which is molded using a second resin composition different from the first resin composition. The premolded body and the base main body molded body are molded bodies that are molded integrally.

Description

Bristle molding and toothbrush

The present invention relates to a bristle molded body and a toothbrush. This application claims priority based on Japanese Patent Application No. 2020-214798 for which it applied in Japan on December 24, 2020, and the content is used in this application.

There has been proposed an integrally formed toothbrush in which a toothbrush is manufactured only by an injection molding machine (for example, Patent Document 1). Since the filaments are integrally formed with the brush head base (or the brush head), the integrally formed toothbrush does not require material procurement of the filaments and a hair planting machine, and has the advantage that it can be manufactured at a lower cost than a bristle toothbrush.

As an integrally-molded toothbrush for brushing, it has been proposed to separate a brush head (molded bristle body) having a filament and an insertion hole, and a shank portion provided with an insertion portion at one end, and to fit the two together. An integrally formed toothbrush is provided (for example, Patent Document 2, Patent Document 3). Since the toothbrush described in Patent Document 2 and Patent Document 3 can be replaced by a user, the brush head is only discarded, and resource saving such as a handle that can be reused is expected.

Since the brush head is formed of a single resin material, there is a limit in improving the usability and appearance (design) of the toothbrush. Patent Document 4 discloses a technique of insert-molding filaments containing a plurality of different resin compositions by using a mold provided with a separately molded shank. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 61-207233 [Patent Document 2] Chinese Utility Model No. 204561298 Specification [Patent Document 3] Chinese Patent Application Publication No. 107041792 Specification [Patent Document 4] Chinese Utility Model No. 205214577 Specification

[The problem to be solved by the invention] However, in the toothbrush of patent document 4, since the wall which divides the filament of a plurality of colors is provided, the filament cannot be arrange|positioned in the part of a wall, and a space is formed. Therefore, there is a problem that it is difficult to arrange the filaments in a regular continuous contour, and the gentle touch of the brush head inserted into the oral cavity is impaired.

The present invention was made in consideration of the above points, and an object thereof is to provide a bristle molded body and a toothbrush which have a soft touch and can improve the usability and appearance of the toothbrush. [Means of Solving Problems]

According to a first aspect of the present invention, there is provided a bristle molded body having a brush head base portion formed of a soft resin, and a support surface protruding from a support surface located on the front side in the thickness direction of the brush head base portion a plurality of filaments, the brush head base portion has a fitting hole extending along a longitudinal direction orthogonal to the thickness direction and opening to one side of the longitudinal direction, and the brush bristle forming body includes a preform A body and a base body formed body, the preform has a filament group including at least a part of the plurality of filaments, and a base that supports the filament group and is located closer to the fitting hole than the fitting hole. A support seat part on the front side and forming a part of the brush head base part, at least a part of which is formed from a first resin composition, and the base body molded body has the brush head base part and the plurality of thin strips. A molded body in which the portion other than the preform in the yarn is molded from a second resin composition different from the first resin composition, and the preform and the base body molded body are integrally molded .

In addition, in the bristle molded body according to one aspect of the present invention, a part of the plurality of filaments constitutes the filament group formed from the first resin composition, and the plurality of filaments are characterized in that The filaments other than the filament group among the filaments constitute the base body molded body integrally molded with the brush head base portion by the second resin composition.

In addition, in the bristle molded body according to one aspect of the present invention, in a cross-section perpendicular to the longitudinal direction of the brush head base portion, when the cross-sectional area of the support seat portion is S1 is assumed, and the cross-sectional area of the region between the surface on the front side and the support surface inside the fitting hole is denoted by S, the value represented by S1/S is the value in which the fitting hole is provided. It is 0.6 or less in the whole area of a hole.

In addition, in the brush bristle molded body according to one aspect of the present invention, in a cross-section perpendicular to the longitudinal direction, the brush Assuming that the cross-sectional area of the head base portion is SW, the value represented by SV/(SW-S1) is 0.5 or less in the entire region in which the fitting hole is provided.

Moreover, in the bristle molded body of one aspect of the present invention, when the area of the brush head base portion viewed from the front side in the thickness direction is defined as P, the thickness from the When the area of the said support seat part seen from the front side of a direction is set to P1, the value represented by P1/P is 0.1 or more and 0.5 or less.

In addition, in the bristle molded body according to one aspect of the present invention, a distance from the base end of the filament to the brush head base portion on the opposite side to the front side in the thickness direction is characterized in that The maximum distance to the back is 2.0 mm or more and 4.5 mm or less.

In addition, in the bristle molded body according to one aspect of the present invention, if the maximum distance from the proximal end of the filament to the back surface of the brush head base portion is T, the Assuming that the thickness in the thickness direction of the support seat portion is t1, the value represented by t1/T is 0.5 or less.

Further, in the bristle molded body according to one aspect of the present invention, when the distance between the surface on the back side of the support seat portion and the surface on the front side inside the fitting hole is As t2, the value represented by t1/(t1+t2) is 0.2 or more and 0.8 or less.

In addition, in the bristle molded body according to one aspect of the present invention, if the number of the filaments in the filament group is FM, the support seat and the base are When the area where the seat body molded body is bonded is set to Q1 (mm ² ), the value represented by FM/Q1 is 1.0 (pieces/mm ² ) or less.

In addition, in the bristle molded body according to one aspect of the present invention, a concavo-convex structure is provided at the bonding interface between the support seat portion and the base body molded body.

In addition, in the bristle molded body according to one aspect of the present invention, if the maximum length of the brush head base portion in the longitudinal direction is L1, the fitting in the longitudinal direction is set to L1. Assuming that the maximum length of the closing hole is L2, the value represented by L2/L1 is 0.30 or more and 0.70 or less.

Moreover, in the brush bristle molding of one aspect of the present invention, the preform has all of the plurality of filaments.

In addition, in the bristle molded body according to one aspect of the present invention, the preform is characterized in that the preform has the filament group and the support seat portion, and is molded from the first resin composition; and The second support seat is formed of a third resin composition different from the first resin composition and the second resin composition, and supports the second filament group and the base of the second filament group.

Moreover, in the bristle molding of one aspect of the said invention, the said soft resin is a polyurethane, It is characterized by the above-mentioned.

According to a second aspect of the present invention, there is provided a toothbrush comprising: the bristle molded body according to the first aspect of the present invention; The handle body of the fitting protrusion.

According to a third aspect of the present invention, there is provided a toothbrush comprising: the bristle molded body of the first aspect of the present invention; The bristle forming body and the handle body are integrally formed forming bodies. [Effect of invention]

In the present invention, there is provided a bristle molded body and a toothbrush which have a soft touch and can improve the usability and appearance of the toothbrush.

Hereinafter, embodiments of the formed bristle body and the toothbrush of the present invention will be described with reference to FIGS. 1 to 18 . In this embodiment, the example of the toothbrush in which the bristle molding body is detachably provided in the handle body is demonstrated.

In addition, the following embodiment shows one form of this invention, It does not limit this invention, It can change arbitrarily within the range of the technical idea of this invention. In addition, in the following drawings, in order to make it easy to understand each structure, the scale, the number, etc. in each structure are made to differ from an actual structure.

FIG. 1 : is a front view of the bristle molding 20 and the toothbrush 1 which concern on this embodiment. FIG. 2 is a side view of the bristle molded body 20 and the toothbrush 1 . The toothbrush 1 includes a rod-shaped handle body 10 and a bristle molded body 20 . The handle body 10 and the bristle forming body 20 are separate components. The bristle molded body 20 is detachably attached (inserted) to the handle body 10 . The bristle molded body 20 is formed of soft resin. The handle body 10 is formed of hard resin.

In addition, the front surface in this embodiment means that the filament 23 mentioned later protrudes in the normal line direction of the support surface 21a (details will be described later) of the bristle molded body 20 in the thickness direction (hereinafter, simply referred to as the thickness direction). side (upper side in Figure 2). The side opposite to the front side in the thickness direction of the bristle molded body 20 is suitably called the back side. In addition, the longitudinal direction of the handle body 10 , that is, the direction in which the handle body 10 is inserted with respect to the bristle molded body 20 (hereinafter, simply referred to as the insertion direction) is orthogonal to the normal line direction. In the longitudinal direction, the side where the handle body 10 is attached to the bristle molded body 20 is referred to as a rear end side, and the side opposite to the rear end side is appropriately referred to as a front end side. In addition, the direction orthogonal to the said normal line direction and the insertion direction is the width direction (henceforth, only the width direction) of the bristle molding body 20.

[First embodiment of the bristle molded body 20] FIG. 3 is a front view of the bristle molded body 20 . FIG. 4 is an A-A sectional view in FIG. 3 . As shown in FIGS. 3 and 4 , the bristle molded body 20 includes a brush head base portion 21 having a substantially rectangular shape in front view, and a plurality of filaments 23 provided on the front surface of the brush head base portion 21 .

As the soft resin constituting the bristle molded body 20, various elastomers can be used, but polyurethane is preferred. Polyurethane tends to have higher tensile strength than other elastomers such as styrene and polyester. Therefore, by using polyurethane for soft resins, even if it is thin, Mechanical strength can also be ensured, and breakage at the time of fitting of the handle body 10 to the fitting hole 22 and the use of the toothbrush 1 can be suppressed.

In polyurethane, 0.01 wt % to 1.0 wt % (mass %) of saturated/unsaturated hydrocarbons above C10, higher alcohols, fatty acid amides, fatty acid esters, low molecular weight polyethylene, polyethylene di Any of alcohol (Polyethylene glycol, PEG), fatty acid metal salt, long-chain fatty acid, fatty acid glycerol, liquid paraffin, polysiloxane, or a combination of these, can function as a lubricant and a mold release agent.

In addition, compared with the other elastomers described above, polyurethane can select a wider range of hardness, and can be selected according to the thickness of the bristle molded body 20 in consideration of its usability (for example, the bending of the front end of the bristle molded body). ) resin hardness. The hardness of the polyurethane is preferably not less than Shore 90A and not more than Shore 70D. When the hardness of polyurethane is softer than Shore 90A, it is easy to deform when formed with a thin wall, so the fitting becomes weak, and the bristle molded body 20 becomes easy to use when the toothbrush 1 is used. fall off. In the case where the hardness of polyurethane is harder than that of Shore 70D, there is a possibility that when the back of the base 21 of the brush head has been inclined, pain occurs when the front end hits the oral tissue. . By setting the hardness of the polyurethane to be Shore 90A or more and Shore 70D or less, it is possible to suppress the occurrence of the bristle molded body 20 falling off during use of the toothbrush 1 or the front end of the brush head base portion 21 hitting against each other. pain.

In addition, as the polyurethane, it is preferable to use an ether-based polyurethane from the viewpoint of securing water resistance and antibacterial properties.

The filaments 23 have a substantially columnar shape that protrudes toward the front side from the support surface 21 a located on the front side in the thickness direction of the brush head base portion 21 . The support surface 21a of the brush head base portion 21 is a flat surface parallel to the width direction and the insertion direction. The support surface 21a is arranged at the proximal end position of the filament 23 in the thickness direction. The proximal end side of the filament 23 is a substantially triangular prism shape with a substantially triangular cross section, and the distal end side is a triangular pyramid shape extended from the substantially triangular prism and tapered at the tip. As the cross-sectional shape of the filaments 23, in addition to a substantially triangular shape, a substantially polygonal shape such as a substantially quadrangular shape, a substantially circular shape, a substantially star shape, a substantially wooden spade shape, or the like can be selected. The filament 23 may have a tapered shape in which the tip of the tip is tapered, a structure extending straightly, or a tapered shape tapered from the base end.

The rows of the filaments 23 arranged in the width direction of the bristle molded body 20 are provided in a plurality of rows along the insertion direction so that the rows adjacent to each other in the insertion direction are shifted from each other by a half pitch. That is, the filaments 23 are arranged in a zigzag shape.

FIG. 5 : is the figure which looked at the bristle molded object 20 from the rear-end side. As shown in FIG. 5 , the plurality of filaments 23 include a filament group (first filament group) F1 located at the center in the width direction, and filament groups F2 located on both sides in the width direction of the filament group F1. As an example, the filament group F1 is higher than the filament group F2. The maximum length of the filaments 23 is preferably 7 mm or more, and more preferably 9 mm or more. The maximum length of the filaments 23 is preferably 15 mm or less, and more preferably 13 mm or less. Moreover, as the maximum length of the filament 23, 7 mm or more and 15 mm or less are preferable, and 9 mm or more and 13 mm or less are more preferable. When the maximum length of the filaments 23 is less than 7 mm, there is a possibility that the cleaning performance in the oral cavity may decrease. When the maximum length of the filaments 23 exceeds 15 mm, the mold releasability at the time of molding the bristle molded body 20 is reduced by injection molding. By setting the maximum length of the filaments 23 to be 7 mm or more and 15 mm or less, the cleaning property in the oral cavity and the releasability at the time of molding can be ensured.

The cross-sectional area of the proximal end of the filament 23 is preferably 0.8 mm ² or less, and more preferably 0.6 mm ² or less. When 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 cleaning performance of the gap between the teeth or the neck of the teeth is lowered. By setting the cross-sectional area of the proximal end of the filament 23 to be 0.8 mm ² or less, the clearance between the teeth or the neck of the teeth can be ensured.

The ratio of the total cross-sectional area of the proximal ends of the plurality of filaments 23 to the area of the support surface 21a of the brush head base portion 21 is preferably 10% or more and 50% or less. When the ratio of the total cross-sectional area of the base ends of the filaments 23 is less than 10%, there is a possibility that the cleaning property in the oral cavity may decrease. When the ratio of the total cross-sectional area of the base ends of the filaments 23 exceeds 50%, the mold releasability at the time of molding the bristle molded body 20 is reduced by injection 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, the cleaning property in the oral cavity and the mold releasability at the time of molding can be ensured.

The filament group F1 constitutes a part of the plurality of filaments 23 and is formed of the first resin composition. The filament group F2 is composed of filaments 23 other than the filament group F1 among the plurality of filaments 23, and is formed of a second resin composition different from the first resin composition. In consideration of the usability and appearance (design) of the toothbrush 1 , the above-mentioned soft resins can be appropriately selected as the first resin composition and the second resin composition. For example, when the massage property and the brushing feeling are taken into consideration in consideration of the usability of the toothbrush 1, the soft resins having different hardnesses can be used. In addition, considering the appearance, the soft resin can be used as a base material, and a colorant such as a master batch can be added to make the filament group F1 and the filament group F2 different colors.

The brush head base portion 21 has a support seat portion 30 and a fitting hole 22 . The support seat part 30 supports the base end of the filament group F1 from the lower side. As shown in FIG. 3 , the support seat portion 30 is in the shape of a rectangular parallelepiped when viewed from the front and includes the size of the filament group F1 . As shown in FIG. 4 , the upper surface of the support seat 30 is coplanar with the support surface 21a. That is, the upper surface of the support seat part 30 constitutes a part of the support surface 21a. Hereinafter, the upper surface of the support seat portion 30 is also appropriately referred to as the support surface 21a.

The support seat portion 30 is located on the front side of the fitting hole 22 . A part of the brush head base portion 21 is formed. The support seat portion 30 is formed of the first resin composition. The support seat portion 30 and the filament group F1 constitute a preform 40 integrally molded from the first resin composition.

The fitting hole 22 extends in the insertion direction and opens on the end surface 21b on the rear end side (one of them). FIG. 6 is a cross-sectional view of a surface including the fitting hole 22 that is parallel to the support surface 21a. As shown in FIG. 6 , the fitting hole 22 has a first portion 33 opened on the end surface 21 b and a second portion 34 located further back than the first portion 33 . As shown in FIG. 4 , the first portion 33 and the second portion 34 are arranged separately from the back surface 21 c of the brush head base portion 21 and the back surface of the support seat portion 30 , respectively.

The brush head base portion 21 has a protrusion 35 located at the approximate center in the insertion direction of the fitting hole 22 , that is, between the first portion 33 and the second portion 34 . The protrusions 35 are provided on both sides in the width direction of the fitting hole 22 . The projections 35 are respectively provided at positions to be fitted into the recesses 15 (described later) when the fitting protrusions 12 (refer to FIG. 7 , described later) of the handle body 10 are inserted into the fitting holes 22 . The protrusion 35 has a circular arc center on the outer side in the width direction, and has a circular arc shape that protrudes inward.

The shortest distance L35 between the protrusions 35 is shorter than the width L33 of the first portion 33 and the width L34 of the second portion 34 . As an example, the protrusion amount of the protrusion 35 inward in the width direction with respect to the second portion 34 is 1 mm. The protrusion amount of the protrusion 35 with respect to the second portion 34 is the undercut amount when the mold (slide core) for forming the fitting hole 22 during injection molding of the bristle molded body 20 is pulled out to the rear end side.

In the bristle molded body 20, the brush head base portion 21 other than the support seat portion 30 is formed of the second resin composition. In the bristle molded body 20, the brush head base portion 21 other than the support seat portion 30 and the filament group F2 constitute a base body molded body 50 integrally molded with the second resin composition. The bristle molded body 20 is a molded body in which the preformed body 40 and the base body molded body 50 are integrally molded. In this case, the preform 40 formed by the primary molding of the first resin composition is placed in a cavity in the mold, and the cavity is filled with the second resin composition to perform secondary molding (insert molding). The shaped body is formed.

Returning to FIG. 5 , in the cross section perpendicular to the longitudinal direction of the brush head base portion 21 , the thickness t1 of the support seat portion 30 is selected from 0.5 mm to 2.5 mm. The thickness t2 between the back surface of the support seat portion 30 and the surface on the front side inside the fitting hole 22 is selected from 0 mm to 2.5 mm. When the back surface of the support seat 30 and the front surface inside the fitting hole 22 are coplanar, the thickness t2 of the back surface of the support seat 30 and the front surface inside the fitting hole 22 is 0 mm. That is, it is possible to select a structure in which the back surface of the support seat portion 30 is exposed to the fitting hole 22 so as to face each other. In this case, the side surfaces in the width direction of the support seat portion 30 are bonded and fixed to the base body molding 50 .

The thickness t1+t2 between the surface on the front side inside the fitting hole 22 and the support surface 21a is selected from 0.5 mm to 3.5 mm. The length t3 in the thickness direction of the fitting hole 22 is selected from 1.0 mm to 3.0 mm. The thickness t4 between the back surface side surface inside the fitting hole 22 and the back surface 21c of the brush head base part 21 is selected from 0.3 mm - 2.0 mm.

In a cross-section perpendicular to the longitudinal direction of the brush head base portion 21, if the cross-sectional area of the support seat portion 30 is S1, the thickness between the surface on the front side inside the fitting hole 22 and the support surface 21a Assuming that the cross-sectional area of the region of t1+t2 is S, the value represented by S1/S is preferably 0.1 or more in the entire region in which the fitting hole 22 is provided. The value represented by S1/S is preferably 0.6 or less, more preferably 0.5 or less, and still more preferably 0.4 or less. The value represented by S1/S is preferably 0.1 or more and 0.6 or less, more preferably 0.1 or more and 0.5 or less, and still more preferably 0.1 or more and 0.4 or less.

In the bristle molded body 20 having the fitting hole 22, the cross-sectional area S of the region defined by the thickness t1+t2 between the surface on the front side inside the fitting hole 22 and the support surface 21a, and the size of the support seat 30 The cross-sectional area S1 has a great influence on the formability of the filaments 23 . Regarding multi-color molding, after the primary side molding, the secondary side is molded by switching the movable side (or fixed side) of the mold, so molding is performed with the primary side molding remaining in the cavity. . The flowable region after the secondary side is further reduced. Therefore, unlike single-color molding, multi-color molding tends to have insufficient fluidity of resin on the secondary side and later, making it difficult to mold filaments. In this case, since sufficient filling speed and holding pressure cannot be ensured, forming defects such as sink marks and air bubbles are likely to occur. Specifically, when the value represented by the above-mentioned S1/S exceeds 0.6, forming failure of the filaments 23 is likely to occur. In the present embodiment, by setting the value represented by S1/S to be 0.6 or less, the forming defect of the filaments 23 can be suppressed. Furthermore, from the viewpoint of securing the formability of the primary side support seat 30 and the filament group F1, it is preferable to set the value represented by S1/S to 0.1 or more.

On a cross section perpendicular to the longitudinal direction of the brush head base portion 21, if the cross-sectional area of the fitting hole 22 is SV, the cross-sectional area of the brush head base portion 21 including the cross-sectional area SV of the fitting hole 22 is As SW, the value represented by SV/(SW-S1) is preferably 0.1 or more in the entire region where the fitting hole 22 is provided. The value represented by SV/(SW-S1) is preferably 0.5 or less, more preferably 0.4 or less, and still more preferably 0.3 or less. The value represented by SV/(SW-S1) is preferably 0.1 or more and 0.5 or less, more preferably 0.1 or more and 0.4 or less, and still more preferably 0.1 or more and 0.3 or less.

In the molding other than the primary side, that is, the molding of the base body molding 50, in addition to the presence of the preformed body 40 on the primary side previously molded, the presence of the sliding core for forming the fitting hole 22 also causes the resin to flow. have a big impact. When the occupancy of the sliding core is small, the resin flows easily in the cavity, and the formability of the filaments 23 is improved. On the other hand, when the value represented by SV/(SW-S1), which represents the occupancy rate of the sliding core, exceeds 0.5, there is a possibility that the flow of the resin is restricted during the molding of the base body molding 50, and the occurrence of The formation of the filaments 23 (the filament group F2 ) on the secondary side and later is defective. In the present embodiment, by setting the value represented by SV/(SW-S1) to be 0.5 or less, the forming defect of the filaments 23 can be suppressed. Furthermore, from the viewpoint of securing the strength of the sliding core, it is preferable that the value represented by the above-mentioned SV/(SW-S1) be 0.1 or more.

When the area (projected area) of the brush head base portion 21 when viewed from the front side in the thickness direction is defined as P, and the area of the support seat portion 30 when viewed from the front is defined as P1, P1/ The value represented by P is preferably 0.1 or more, more preferably 0.2 or more. The value represented by P1/P is preferably 0.5 or less, more preferably 0.4 or less. In addition, the value represented by P1/P is preferably 0.1 or more and 0.5 or less, more preferably 0.1 or more and 0.4 or less, and still more preferably 0.2 or more and 0.4 or less.

As means for improving the formability of the filaments 23 (filament group F2 ) other than the primary side, the flow of the resin flowing in the direction parallel to the support surface 21 a is also important. Especially, when a gate is located in the edge part of the longitudinal direction of the bristle molding body 20 like a side gate, it plays a significant role. Therefore, when the value represented by P1/P exceeds 0.5, there is a possibility that the flow of the resin is hindered due to the occupation of the cavity region by the preform 40 on the primary side, and the base on the secondary side and later The forming failure of the filaments 23 occurs during the forming of the seat body forming body 50 . On the other hand, when the value represented by P1/P is less than 0.1, there is a possibility that the occupancy rate of the filament group F1 is lowered and functionality (eg, cleaning properties) cannot be secured. In the present embodiment, by setting the value represented by P1/P to be 0.1 or more and 0.5 or less, it is possible to suppress the forming failure of the filaments 23 while ensuring the functionality of the filament group F1.

The maximum distance (maximum thickness) between the support surface 21a of the brush head base 21 and the back surface 21c, that is, the maximum distance T from the base end of the filament 23 to the back surface 21c is preferably 2.0 mm or more and 4.5 mm or less. When the maximum distance T is less than 2.0 mm, there may be a gap between the support surface 21 a and the surface on the support surface 21 a side of the fitting hole 22 , or the back surface 21 c and the back surface 21 c side of the fitting hole 22 . The gap between the surfaces becomes smaller, and the fluidity of the molten resin decreases during the molding of the base body molding 50, so that the resin is not filled. In addition, when the maximum distance T is less than 2.0 mm, the gap between the surface of the fitting hole 22 on the support surface 21 a side and the support seat portion 30 has to be reduced, which leads to the molding of the base body molding 50 . The fluidity of the molten resin decreases. When the maximum distance T exceeds 4.5 mm, there is a possibility that the operability at the time of inserting the bristle molded body 20 into the oral cavity may decrease. In the present embodiment, by setting the maximum distance T to be 2.0 mm or more and 4.5 mm or less, it is possible to secure the fillability of the resin and the workability when inserting the bristle molded body 20 into the oral cavity.

If the maximum distance from the base end of the filament 23 to the back surface 21c of the brush head base portion 21 is T, and the thickness of the support base portion 30 in the thickness direction is t1, the value represented by t1/T is relatively small. Preferably it is 0.5 or less, More preferably, it is 0.4 or less. When the value represented by t1/T exceeds 0.5, in order to secure the resin flow when molding the base body molded body 50 other than the primary side, the entire bristle molded body 20 becomes thick, and the intraoral operability decreases. In the present embodiment, by setting the value represented by t1/T to be 0.5 or less, it is advantageous for both the formability and usability at the time of molding the susceptor main body molded body 50 on the secondary side and later. In addition, from the viewpoint of securing the formability of the primary side and the adhesiveness of the side surface of the primary side support seat portion 30 to the brush head base portion 21, the value represented by t1/T is preferably 0.1 or more.

The thickness t1 and the thickness t2 between the thickness t1 and the surface on the front side inside the fitting hole 22 are preferably represented by t1/(t1+t2) to be 0.2 or more, and more preferably 0.3 or more. The value represented by t1/(t1+t2) is preferably 0.8 or less, more preferably 0.7 or less. In addition, the value represented by t1/(t1+t2) is preferably 0.2 or more and 0.8 or less, and more preferably 0.3 or more and 0.7 or less. When the value represented by t1/(t1+t2) exceeds 0.8, there is a possibility that sufficient resin flow cannot be ensured between the back surface of the primary side (the back surface of the support seat portion 30 ) and the sliding core. The space is therefore dependent on the flow of resin on the side surface side of the support seat portion 30 , and the moldability other than the primary side (susceptor body molded body 50 ) is degraded. Furthermore, there is a possibility that the resin adhesion between the support seat portion 30 on the primary side and the base body molded body 50 on the secondary side is unstable. When the value represented by t1/(t1+t2) is less than 0.2, there is a possibility that the formability of the support seat portion 30 on the primary side cannot be ensured. In the present embodiment, by setting the value represented by t1/(t1+t2) to 0.2 or more and 0.8 or less, the formability of the primary side support seat 30 and the secondary side base body molded body 50 can be ensured. , and the resin adhesion between the support seat 30 and the base body molding 50 can be stabilized.

In addition, if the thickness t2 is 0.3 mm or more, even if it is the specification of a wide brush head, the problem of formability is less likely to occur. As thickness t2, 0.5 mm or more is preferable, and 0.8 mm or more is more preferable.

Assuming that the number of filaments in the filament group F1 is FM, and the area where the support seat portion 30 and the base body molding 50 are bonded to be Q1 (mm ² ), the value is expressed by FM/Q1 , preferably 1.0 (strand/mm ² ) or less, more preferably 0.8 (strand/mm ² ) or less. The filaments 23 are pulled off due to the demolding resistance of the cavity surface during demolding after forming. When the value represented by FM/Q1 exceeds 1.0 (pieces/mm ² ), there is a possibility that in the multi-color molding, the preform 40 and the base body molding 50 are formed after the secondary molding. When the body is demolded, the preform 40 is peeled off from the base body formed body 50 due to the demolding resistance of the filament group F1. In the present embodiment, by setting the value represented by FM/Q1 to be 1.0 (root/mm ² ) or less, the preform 40 after secondary molding can be suppressed from peeling off from the base body molded body 50 . Furthermore, in the case where the number of the filament groups F1 cannot be sufficiently secured with respect to the occupied area of the support seat portion 30, considering the possibility that the functionality of the primary side filaments F1 may decrease, it is preferable to use FM. The value represented by /Q1 is set to 0.2 (root/mm ² ) or more.

From the viewpoint of suppressing the peeling of the preform 40 relative to the base body formed body 50 after the secondary molding, it is preferable to provide one or more unevennesses on the bonding interface between the support seat portion 30 and the base body formed body 50 structure. Since the bonding interface between the support seat 30 and the base body forming body 50 is not smooth, the concave-convex structure is provided to increase the bonding area while ensuring the formability, thereby improving the adhesion of the primary side preform 40 . As an arrangement of the concavo-convex structure, it may be arranged on the back surface or the side surface of the support seat 30 , but the height or width of the concavo-convex structure can be easily increased on the back surface compared with the side surface, so it is effective to increase the bonding area. In the case where the concavo-convex structure is arranged on the side surface of the support seat portion 30 , it is only necessary to consider the thickness of the support seat portion 30 and the undercut when molding the preform 40 . The height (highest to lowest) of the concavo-convex structure can be, for example, about 0.1 mm to 0.5 mm, and the pitch of the concavo-convex structure can be, for example, about 0.5 mm to 3.0 mm.

As shown in FIG. 4 , if the maximum length of the brush head base portion 21 in the longitudinal direction is L1 and the maximum length of the fitting hole 22 is L2, the value represented by L2/L1 is preferably 0.30 or more, More preferably, it is 0.40 or more, and still more preferably 0.45 or more. The value represented by L2/L1 is preferably 0.70 or less, more preferably 0.60 or less, and still more preferably 0.55 or less. In addition, the value represented by L2/L1 is preferably 0.30 or more and 0.70 or less, more preferably 0.40 or more and 0.60 or less, and still more preferably 0.45 or more and 0.55 or less.

When the value represented by L2/L1 is less than 0.30, there is a possibility that the area where the fitting protrusion 12 does not exist in the handle body 10 formed of the hard resin becomes larger, so that the front of the bristle molded body 20 may be easily moved. It is bent, and the usability as the toothbrush 1 is decreased. When L2/L1 exceeds 0.70, the volume occupied by the mold (sliding core) that forms the fitting hole 22 during molding increases, and the flow of the resin is restricted, thereby reducing the formability of the filaments 23 . By making the value represented by L2/L1 into 0.30 or more and 0.70 or less, the fall of the formability of the filament 23 can be suppressed, and the usability fall of the toothbrush 1 can be suppressed.

[Handle body 10] FIG. 7 is a front view of the handle body 10 . As shown in FIG. 7 , the handle body 10 includes a rod-shaped handle portion 11 , and a fitting protrusion 12 provided at the distal end of the handle portion 11 and protruding toward the distal end side in the longitudinal direction of the handle portion 11 . The fitting protrusion 12 is detachably fitted in the fitting hole 22 of the bristle molded body 20 . In the toothbrush 1 , the fitting protrusion 12 of the handle body 10 is inserted into the fitting hole 22 in the bristle molding 20 described above, and the bristle molding 20 is attached to cover the fitting protrusion 12 .

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

As shown in FIG. 2 , the side view shape of the handle portion 11 is extended with a constant width from the front end side to the rear end side, and then the width gradually becomes wider until it reaches the maximum thickness of the finger contact portion. The side view shape of the handle portion 11 is curvilinearly changed so that the width is gradually narrowed toward the rear end side from the finger contact portion having the largest thickness. The rear end portion of the side view shape of the handle portion 11 has a substantially semicircular shape.

In addition, in this invention, the shape of a handle|steering-wheel part is not limited to the shape of the said example, It can set suitably in consideration of intensity|strength, operability, designability, etc.. The size of the handle portion 11 is not particularly limited, and can be appropriately set. For example, the length of the handle portion 11 can be set to 100 mm to 200 mm.

The fitting protrusion 12 is a portion covered by the bristle molding 20 in a state where the bristle molding 20 is attached to the handle body 10 . The rear end of the fitting protrusion 12 is the rear end position of the bristle molding body 20 in a state where the bristle molding body 20 is attached to the handle body 10 .

FIG. 8 is an enlarged front view of the fitting protrusion 12 . FIG. 9 is an enlarged side view of the fitting protrusion 12 . As shown in FIG. 8 , the fitting protrusion 12 includes a base portion 13 provided on the distal end side of the shank portion 11 , and a distal end portion 14 provided at the distal end of the base portion 13 . As shown in FIG. 9 , the base portion 13 and the front end portion 14 have a level difference with respect to the handle portion 11 on both sides of the front side and the back side, and are formed with the same thickness thinner than the handle portion 11 .

The base portion 13 has a substantially rectangular shape in plan view. The base portion 13 has a level difference with respect to the shank portion 11 on both sides in the width direction, and is formed with a width L13 narrower than the maximum width L11 on the front end side of the shank portion 11 ( L13 < L11 ). The front end portion 14 has a substantially elliptical shape in which the width direction is the longitudinal direction in plan view. The distal end portion 14 has a shape in which side edges are notched on both sides of the substantially elliptical shape in the width direction with a straight line parallel to the insertion direction of the fitting protrusion 12 . The front end portion 14 has a level difference with respect to the base portion 13 on both sides in the width direction, and is formed with a width L14 narrower than the width L13 of the base portion 13 .

The fitting protrusion 12 has a recess 15 at approximately the center in the insertion direction, that is, between the base portion 13 and the front end portion 14 . The recesses 15 are provided on both sides in the width direction. The recess 15 has a circular arc center on the outside and is concave toward the inside in the width direction. The shortest distance L15 between the recesses 15 is shorter than the width L13 of the base portion 13 and the width L14 of the front end portion 14 . As an example, the recessed amount with respect to the recessed part 15 of the edge of the front-end|tip part 14 of the predetermined|prescribed width L14 is 1 mm.

The handle body 10 is formed of hard resin. As an example of the hard resin, a resin having a flexural modulus of elasticity (Japanese Industrial Standards (JIS) K7171) of 1500 MPa or more and 3000 MPa or less can be exemplified. Specifically, for example, polypropylene resin (Polypropylene, PP), polyacetal resin (Polyoxymethylene (POM)), polyester resin (poly(1,4-cyclohexylene dimethylene-p-phenylene) can be exemplified. Dicarboxylic acid) (Poly(l,4-cyclohexanedimethylene terephthalic acid), PCTA)), polyethylene terephthalate copolymer (poly(ethylene terephthalate-1,4-cyclohexadiene terephthalate) Methyl terephthalate) (Poly(ethylene terephthalateco-1,4-cylclohexylenedimethylene terephthalate), PETG)), high density polyethylene (High Density Polyethylene, HDPE). Among these resins, PP, which is a general-purpose resin, is also preferable in consideration of cost.

The maximum width L21 of the rear end side (end surface 21 b ) of the brush head base portion 21 is substantially the same as the maximum width of the front end side of the handle portion 11 . The front view shape of the fitting hole 22 is substantially the same as the front view shape of the fitting protrusion 12 . The width L33 of the first portion 33 is a length into which the base portion 13 in the fitting protrusion 12 can be inserted, and is substantially the same as the maximum width L13 of the base portion 13 . The width L34 of the second portion 34 is a length into which the front end portion 14 of the fitting protrusion 12 can be inserted, and is substantially the same as the maximum width L14 of the front end portion 14 . The shortest distance L35 between the protrusions 35 is a length in which the distal end portion 14 of the fitting protrusion 12 and the recess 15 can be inserted, and is substantially the same as the shortest distance L15 between the recesses 15 .

Next, the procedure for forming the bristle forming body 20 will be described with reference to FIGS. 10 to 12 . FIG. 10 is a cross-sectional view in the width direction schematically showing an example of a mold MD for molding the preform 40 in the bristle molded body 20 .

The mold MD includes a first mold MD1 that relatively moves in the opening and closing direction (up-down direction in FIG. 10 ), and a second mold MD2 for primary molding. The first mold MD1 and the second mold MD2 are clamped using the separation surface PL coplanar with the support surface 21a as a joint surface. As an example, the first mold MD1 is a fixed mold, and the second mold MD2 is a movable mold.

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 and closing direction relative to the first mold MD1, whereby the mold MD is opened and closed.

The first mold MD1 has a molding surface 21aM for molding the support surface 21a when it is clamped and joined to the second mold MD2, a cavity F1M for molding the filament group F1, and a cavity F2M for molding the filament group F2. The cavity F1M and the cavity F2M are opened on the separation surface PL of the first mold MD1.

The second mold MD2 has a cavity 30M in which the support seat 30 is formed when the second mold MD2 is clamped and joined to the first mold MD1. The mold cavity 30M is opened in the mold cavity F1M. The mold cavity 30M is not opened in the mold cavity F2M. The opening of the cavity F2M is blocked by the separation surface PL of the second mold MD2. A gate portion (not shown) is provided in the cavity 30M. As the gate portion, for example, a side gate method, a pin point gate method, or a tunnel gate method may be used.

In the mold MD, the molten first resin composition introduced into the cavity 30M from the gate portion G in a state in which the first mold MD1 and the second mold MD2 are clamped is filled into the cavity 30M and the mold cavity 30M. in the cavity F1M. On the other hand, the cavity 30M is not opened in the cavity F2M, and the opening of the cavity F2M is blocked by the separation surface PL of the second mold MD2, so that the first resin composition is not filled. Then, the preform 40 formed of the first resin composition having the filament group F1 and the support seat portion 30 is molded by cooling in a state where the first mold MD1 and the second mold MD2 are clamped.

FIG. 11 is a cross-sectional view in the width direction schematically showing an example of a mold MD for secondary molding for molding the base body molding 50 in the bristle molding 20 . FIG. 12 is a cross-sectional view in the longitudinal direction schematically showing an example of the mold MD for secondary molding.

The mold MD includes a first mold MD1 and a second mold MD12 that relatively move in the opening and closing direction. The 1st metal mold|die MD1 is the said 1st metal mold|die MD1 which hold|maintains the preformed body 40 which has already been molded without releasing it. In addition, a part of the 1st metal mold|die MD1 for the said primary molding containing the cavity F1M and the cavity F2M may be detached, and you may attach it to the 1st metal mold|die MD1 for secondary molding.

The second mold MD12 has a cavity 21M for forming the brush head base portion 21 when it is clamped and joined to the first mold MD1, and a gate portion G that opens at the front end side of the cavity 21M and is introduced into the cavity 21M The molten resin; and the contact surface 21eM are provided at the position of the end surface 21b in the insertion direction, and are orthogonal to the insertion direction. As shown in FIG. 11 , the cavity F2M for forming the filament group F2 is opened in the cavity 21M. As the gate portion G, for example, a side gate method can be used, but a pin gate method and a tunnel gate method can 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 brush head base portion 21 is formed in the second mold MD2.

The slide core SL is provided in the 2nd metal mold|die MD12. The slide core SL has a core portion 22M on which the fitting hole 22 is molded, and a molding surface 21bM on which the core portion 22M protrudes and is perpendicular to the insertion direction. As shown in FIG. 11 , before mold clamping, the molding surface 21bM is separated from the contact surface 21eM. When the first mold MD1 and the second mold MD12 have been clamped, as shown in FIG. 11 , a part of the molding surface 21bM of the slide core SL is in contact with the abutting surface 21eM, and the core portion 22M is positioned in the insert cavity 21M s position. Among the molding surfaces 21bM, a region facing the cavity 21M without contacting the contact surface 21eM is a region for molding the end surface 21b. In addition, when the first mold MD1 and the second mold MD12 have been opened, the sliding core SL is moved from the cavity 21M to the core portion 22M so that the core portion 22M does not hinder the release of the molded bristle body 20. Move in the direction of disengagement. In order to avoid unpredictable movement caused by its own weight, the moving direction of the sliding core SL is preferably a horizontal direction.

In the mold MD, the molten second resin composition introduced into the cavity 21M from the gate portion G in a state in which the first mold MD1 and the second mold MD12 are clamped is filled into the cavity 21M and the mold cavity 21M. Cavity F2M. The second resin composition filled into the mold cavity 21M covers the side surface and the back surface of the support seat portion 30 and is bonded to the support seat portion 30 . After that, the first mold MD1 and the second mold MD12 are cooled in a state where the molds are clamped, and the mold is released from the mold MD, thereby obtaining a molded body including a preform 40 having filaments The group F1 and the support seat portion 30 are formed of the first resin composition; and the base body molded body 50, which has the brush head base portion 21 and the portion other than the preform 40 among the plurality of filaments 23, is composed of a second The resin composition is molded, and the preform 40 and the base body molded body 50 are integrally molded.

That is, the bristle molded body 20 in which the filaments 23 including the filament group F1 formed of the first resin composition and the second resin composition are formed as a molded body is obtained as a molded body, in which the filaments 23 and the brush head base 21 are integrally molded. The filament group F2, the brush head base portion 21 includes a support seat portion 30 formed of a first resin composition and is formed of a second resin composition.

The toothbrush 1 in which the bristle molded body 20 and the handle body 10 are integrated is obtained by inserting and fitting the fitting protrusion 12 of the handle body 10 into the fitting hole 22 with respect to the formed bristle molded body 20 . In addition, by pulling out the fitting protrusion 12 of the handle body 10 from the fitting hole 22, the bristle molded body 20 can be detached from the handle body 10 and replaced.

As described above, the bristle molded body 20 of the present embodiment has the filament group F1 formed of the soft resin of the first resin composition and the filament group F2 formed of the soft resin of the second resin composition, so By appropriately selecting the first resin composition and the second resin composition according to the purpose, it is possible to obtain a bristle molded body and a toothbrush which have a soft touch and can improve the usability and appearance of the toothbrush 1 .

[Second embodiment of the bristle molded body 20] Next, a second embodiment of the bristle molded body 20 will be described with reference to FIG. 13 . In these figures, the same reference numerals are given to the same elements as the constituent elements of the first embodiment shown in FIGS. 1 to 12 , and the description thereof is omitted. In the above-described first embodiment, the structure in which the preform 40 is molded from one resin composition is exemplified, but in the second embodiment, the structure in which the preform 40 is molded from a plurality of resin compositions will be described.

FIG. 13 is a cross-sectional view in the width direction of the formed bristle body 20 according to the second embodiment. As shown in FIG. 13 , the preform 40 of the present embodiment includes a filament group (second filament group) F3 arranged in the center in the width direction, and filament groups arranged on both sides of the filament group F3 in the width direction, respectively. F1, the second support seat 31 supporting the base of the filament group F3, and the support seat 30 supporting the base of the filament group F1. The filament group F3 is formed from a third resin composition different from the first resin composition and the second resin composition. The filament group F1 and the filament group F3 are formed by a plurality of filaments 23 arranged in the longitudinal direction of the brush head base portion 21 . The third resin composition is appropriately selected from the above-mentioned soft resins.

The second support seat portion 31 is formed of the third resin composition. The side surface and the back surface of the second support seat portion 31 in the width direction are bonded to the support seat portion 30 . The surface on the front side of the second support seat portion 31 is coplanar with the support surface 21a. The preform 40 of the present embodiment is integrally formed with the filament group F3 and the second support seat portion 31 formed from the third resin composition, and the filament group F1 and the support seat portion 30 formed from the first resin composition. shaped body.

As an example, the preform 40 is formed by molding the filament group F3 and the second support seat portion 31 with the third resin composition in the primary molding, and forming the filament group F1 with the first resin composition in the secondary molding. It is obtained by two-color molding in which the support seat portion 30 is formed. Alternatively, by insert molding in which the filament group F1 and the support seat 30 are molded with the first resin composition using a mold provided with the filament group F3 and the second support seat portion 31 formed with the third resin composition get.

In addition, in the bristle molded body 20 of the present embodiment, the filament group F3 and the second support seat portion 31 are molded with the third resin composition in the primary molding, and the thin filament group F3 and the second support seat portion 31 are molded with the first resin composition in the secondary molding. The filament group F1 and the support seat portion 30 are molded and obtained by three-color molding in which the filament group F2 and the brush head base portion 21 are molded with the second resin composition in the third molding. Alternatively, it can be obtained by insert molding in which the filament group F2 and the brush head base portion 21 are molded with the second resin composition using a mold provided with a preformed preform 40 .

The bristle molded body 20 of the above-described structure can not only obtain the same functions and effects as those of the bristle molded body 20 of the first embodiment, but also can use more kinds of resin compositions according to the specifications of the toothbrush 1 to provide a variety of resin compositions. Value-added toothbrush 1.

[Third embodiment of the bristle molded body 20] Next, a third embodiment of the bristle molded body 20 will be described with reference to FIGS. 14 and 15 . In these figures, the same reference numerals are given to the same components as those of the second embodiment shown in FIG. 13 , and the description thereof is omitted. In addition, in this embodiment, the filament group is shown simply as the area|region in which the filament group is arrange|positioned.

Fig. 14 is a front view of the bristle molded body 20 according to the third embodiment. FIG. 15 is a cross-sectional view in the width direction of the bristle molded body 20 according to the third embodiment. As shown in FIG. 14 , in the present embodiment, the filament groups F1 are provided on both sides in the width direction and on both sides in the longitudinal direction of the filament groups F3, respectively. The filament group F1 is arranged in a 0-shape that surrounds the filament group F3.

As shown in FIG. 15 , the side surface of the second support seat portion 31 is adhered to the support seat portion 30 . The second support seat portion 31 penetrates the support seat portion 30 in the thickness direction. The back surface of the second support seat portion 31 is coplanar with the back surface of the support seat portion 30 . Other structures are the same as those of the second embodiment.

In the present embodiment, not only the same functions and effects as those of the second embodiment can be obtained, but also by arranging the filaments 23 two-dimensionally in addition to being linear, more kinds of resins can be used according to the specifications of the toothbrush 1 . composition to provide a toothbrush 1 with various added values.

In addition, as a structure in which the filaments 23 are arranged two-dimensionally, for example, as shown in the front view of FIG. 16 and the cross-sectional view in the longitudinal direction of FIG. 17 , the filament group F1 and the support seat portion 30 can be It is arranged in line with the filament group F3 and the second support seat portion 31 in the longitudinal direction.

[Fourth embodiment of the bristle molded body 20] Next, a fourth embodiment of the bristle molded body 20 will be described with reference to FIG. 18 . In this figure, the same reference numerals are given to the same elements as the constituent elements of the first embodiment shown in FIGS. 1 to 12 , and the description thereof is omitted.

FIG. 18 is a cross-sectional view in the width direction of the formed bristle body 20 according to the fourth embodiment. As shown in FIG. 18 , the filament group F1 in the preform 40 of the present embodiment includes all of the plurality of filaments 23 . Other structures are the same as those of the first embodiment.

In the bristle molded body 20 having the above-described structure, as in the first embodiment, the filament group F1 and the brush head base portion 21 are molded from different resin compositions, so that a toothbrush having a soft touch and improved toothbrush can be obtained. 1. The bristle molding and the toothbrush of the usability and appearance.

Since the preform 40 has all the filaments 23 in the brush formed body 20 of the above-mentioned structure, the mold release resistance of the preform 40 when the brush formed body 20 is released from the mold is increased. Therefore, as described above, it is preferable to use the relationship between the number of filaments FM and the area Q1 where the support seat 30 and the base body molding 50 are bonded, and the relationship between the support seat 30 and the base body molding 50 At least one of the concave-convex structures on the bonding interface.

[Example] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples, and can be implemented with appropriate modifications within a range that does not deviate from the gist.

(Example 1 to Example 8, Comparative Example 1) At least one different toothbrush among the items shown in [Table 1] was used as the samples of Examples 1 to 8 and Comparative Example 1. Let the resin constituting each sample be polyurethane.

[Evaluation method] For each of the samples of Examples 1 to 8 and Comparative Example 1, the formability of filaments, the ease of brushing the entire oral cavity, and the adhesiveness of the preform on the primary molding side were evaluated, respectively.

(1) Evaluation method of filament formability Five bristle molded bodies molded under the same conditions were evaluated by the following criteria. 5 points: Defects in appearance were not seen at all. 4 points: The tip of the filament was deformed at the time of demolding (because the pressure was not sufficiently applied, it was bent by the external force at the time of demolding). 3 points: The thickness of the tip of the filament is thinner than the design value. 2 points: The length of the filament is shorter than the design value (all filaments are more than half of the full length). 1 point: The length of the filament is shorter than the design value (there is a filament less than half of the full length). And the average value of five evaluation points was calculated|required, and it evaluated by the following four grades. ◎ (double circle mark): 4.5 points or more and 5.0 points or less. ○ (circle mark): 3.5 points or more and less than 4.5 points. △ (triangle mark): 2.5 points or more and less than 3.5 points. × (cross mark): less than 2.5 points.

(2) Method for evaluating the ease of brushing the entire oral cavity The sensory evaluation was performed by 10 panelists, and the ease of brushing the entire oral cavity at the time of brushing was evaluated by the following criteria (particular attention was paid to the ease of brushing of the molars). 5 points: Very easy to brush. 4 points: It is slightly easy to brush. 3 points: Neither. 2 points: Slightly difficult to brush. 1 point: Very difficult to brush. Then, the average value of the evaluation points of 10 panelists was obtained, and the evaluation was performed using the following four levels. ⊚: 4.5 points or more and 5.0 points or less. ○: 3.5 points or more and less than 4.5 points. △: 2.5 points or more and less than 3.5 points. ×: Less than 2.5 points.

(3) Method for evaluating the adhesion of the preform on the primary molding side Five bristle molded bodies molded under the same conditions were evaluated by the following criteria. 5 points: Defects in appearance were not seen at all. 4 points: The primary side base portion is deformed by the demolding resistance at the time of demolding (the state where the bristle surface is no longer smooth). 3 points: No peeling was observed in appearance, but peeling was observed at the resin boundary when an external force was applied. 2 points: At the time of mold release, a part of the primary side base part was peeled off, and a part was connected. 1 point: The entire primary side was peeled off and separated from the bristle molded body (state where the primary side remained on the mold). Then, the average value of the five evaluation points was obtained, and the evaluation was performed on the following four levels. ⊚: 4.5 points or more and 5.0 points or less. ○: 3.5 points or more and less than 4.5 points. △: 2.5 points or more and less than 3.5 points. ×: Less than 2.5 points.

[Table 1] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Brush head thickness T (mm) 4.0 4.0 4.0 4.6 4.5 4.0 4.0 4.0 4.0 Thickness t1 of the support seat (mm) 1.0 1.3 1.0 1.0 2.5 2.0 1.0 1.8 1.5 Back of the support seat - thickness t2 (mm) of the upper surface of the fitting hole 1.0 0.7 0.5 1.6 0.5 0.0 1.0 0.2 0.5 Length t3 (mm) in the thickness direction of the fitting hole 1.0 1.0 2.2 1.0 1.0 1.0 1.0 1.0 1.0 The back of the fitting hole - the back of the base of the brush head t4 (mm) 1.0 1.0 0.3 1.0 0.5 1.0 1.0 1.0 1.0 Cross-sectional area S1 of the support seat (mm ² ) 4.0 13.7 4.0 4.0 9.9 7.9 4.0 7.1 15.8 Support surface - cross-sectional area S (mm ² ) of the upper surface of the fitting hole 23.9 23.9 17.9 31.0 35.8 23.9 23.9 23.9 23.9 S1/S 0.17 0.57 0.22 0.13 0.28 0.33 0.17 0.30 0.66 Cross-sectional area SV of fitting hole (mm ² ) 8.4 8.4 25.3 8.4 8.4 8.4 8.4 8.4 8.4 Cross-sectional area SW of the base of the brush head (mm ² ) 48 48 48 55 54 48 48 48 48 SV/(SW-S1) 0.19 0.25 0.58 0.17 0.19 0.21 0.19 0.21 0.26 t1/T 0.25 0.33 0.25 0.22 0.56 0.50 0.25 0.45 0.38 t1/(t1+t2) 0.50 0.65 0.67 0.38 0.83 1.00 0.50 0.90 0.75 Number of roots FM (roots) of the first filament group 72 191 72 72 72 72 125 72 191 Bonding area Q1 of the support seat (mm ² ) 117 267 117 117 184 89 117 153 279 FM/Q1 (root/mm ² ) 0.62 0.72 0.62 0.62 0.39 0.81 1.07 0.47 0.68 Filament formability (scoring) ◎ 4.6 ○ 3.6 ○ 4.2 ◎ 4.9 ○ 4.3 ○ 3.8 ◎ 4.5 ○ 4.0 △ 3.4 Overall ease of brushing in the mouth (score) ◎ 4.6 ◎ 4.5 ◎ 4.6 ○ 3.8 ○ 4.0 ◎ 4.6 ◎ 4.6 ◎ 4.6 ◎ 4.6 Adhesion of primary side preforms (score) ◎ 4.5 ◎ 4.6 ◎ 4.5 ◎ 4.6 ◎ 5.0 ○ 3.6 ○ 3.5 ◎ 4.9 ◎ 4.7

As shown in [Table 1], the ratio of the cross-sectional area S1 of the support seat portion 30 to the cross-sectional area S of the region between the surface on the front side inside the fitting hole 22 and the support surface 21a is represented by S1/S In the samples of Examples 1 to 8 with a value of 0.6 or less, in Example 1, the moldability of filaments, the ease of brushing the entire oral cavity, and the adhesion of the preform on the primary molding side were all satisfactory. result. On the other hand, in the sample of Comparative Example 1 in which the value represented by S1/S exceeded 0.6, a favorable evaluation could not be obtained regarding the formability of the filament.

Under the conditions shown in Example 1, favorable results were obtained with respect to the formability of the filament, the ease of brushing the entire oral cavity, and the adhesiveness of the primary side preform.

When the conditions shown in Example 2 are set, the value represented by S1/S becomes larger as the primary side support seat portion expands. As a result, the flow of the resin on the secondary side and later was reduced, and as a result, the formability of the filament was inferior to that of the sample of Example 1. In addition, the number FM of the first filament group increases with the expansion of the primary side support seat, but the adhesion area Q1 of the support seat also increases, so the adhesion of the primary side preform is the same as that of Example 1. samples are equal.

When the conditions shown in Example 3 are used, the value represented by SV/(SW-S1 ) increases as the thickness of the sliding core increases. As a result, the resin flow during molding of the base body molded body was reduced, and as a result, the moldability of the filaments on the secondary side and onwards was inferior to that of the sample of Example 1.

In the samples of Examples 4 and 5, the thickness of the brush head was thickened, and as a result, the overall ease of brushing in the oral cavity was inferior to that of the sample of Example 1. In addition, the support seat portion of the sample of Example 5 also became thick at the same time, so the value represented by t1/T became larger, and the resin flow during the molding of the base body molded body was reduced compared with that of the sample of Example 4. As a result, filaments The formability is worse than that of the sample in Example 1.

Under the conditions shown in Example 6 and Example 8, the value represented by t1/(t1+t2) became large, and it was not possible to ensure sufficient resin flow between the back surface of the primary side support seat and the sliding core. space, the resin flow decreased, and as a result, the formability of the filament was inferior to that of the sample of Example 1. However, in the sample of Example 8, as compared with the sample of Example 6, the back side surface of the support seat portion is not exposed to the front side surface inside the fitting hole, so the adhesiveness of the primary side preform does not decrease. .

Under the conditions shown in Example 7, the number FM of the first filament group was increased compared with Example 1, but the adhesion area Q1 of the support seat did not change, so FM/Q1 became large, and as a result one time The adhesion of the side preforms was inferior to that of the sample of Example 1.

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

For example, in the above-described embodiment, the toothbrush 1 includes the bristle molded body 20 and the handle body 10 formed separately, and the fitting protrusion 12 of the handle body 10 is fitted to the bristle molded body 20. In the fitting hole 22, the bristle molding body 20 is attached to the handle body 10, but it is not limited to this structure. For example, it is also possible to provide a structure in which the fitting protrusion 12 of the handle body 10 is provided in the mold on which the preform is provided instead of the slide core SL, and insert-molding is performed using the second resin composition during secondary molding. By this insert molding, the toothbrush 1 as a molded body in which the fitting protrusion 12 is fitted into the fitting hole 22 and the bristle molded body 20 and the handle body 10 are integrally molded can be obtained.

In addition, in the above-mentioned 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. For example, a part of the handle body 10 (the handle portion 11 and the like) may be covered with a soft resin. structure. In the case of adopting this structure, the decorative properties and the grip properties can be improved. [Industrial Availability]

The present invention can be applied to a bristle molded body and a toothbrush.

1: toothbrush 10: Handle body 11: Handle 12: Fitting protrusions 13: Base 14: Front end 15: Recess 20: Bristle forming body 21: Brush head base 21a: Support surface 21aM: Forming surface 21b: End face 21bM: Forming Surface 21c: Back 21eM: abutment surface 21M, 30M, F1M, F2M: Mould cavity 22: Fitting hole 22M: core 23: Filament 30: Support seat 31: Second support seat 33: Part One 34: Part Two 35: Protrusions 40: Preform 50: base body forming body F1: Filament group (first filament group) F2: Filament group F3: Filament group (second filament group) G: gate part L1: Maximum length of the brush head base portion 21 in the longitudinal direction L2: Maximum length of fitting hole 22 L11: Maximum width of the front end side of the shank 11 L13: Width L13 of base 13 L14: Width L14 of front end portion 14 L15: The shortest distance between the recesses 15 L21: Maximum width of the rear end side (end surface 21b) of the brush head base portion 21 L33: The width of the first part 33 L34: The width of the second part 34 L35: The shortest distance between the protrusions 35 MD: Mold MD1: The first mold MD2: Second mold MD12: Second mold PL: separation plane SL: sliding core T: maximum distance t1: Thickness of the support seat 30 t2: The thickness of the back surface of the support seat 30 and the surface on the front side inside the fitting hole 22 t3: Length in the thickness direction of the fitting hole 22 t4: Thickness between the back side surface inside the fitting hole 22 and the back surface 21c of the brush head base portion 21

1 : is a front view of the bristle molding 20 and the toothbrush 1 which concern on embodiment of this invention. FIG. 2 is a side view of the bristle molded body 20 and the toothbrush 1 . FIG. 3 is a front view of the bristle molded body 20 . FIG. 4 is an A-A sectional view in FIG. 3 . FIG. 5 : is the figure which looked at the bristle molded object 20 from the rear-end side. FIG. 6 is a cross-sectional view of a surface including the fitting hole 22 that is parallel to the support surface 21a. FIG. 7 is a front view of the handle body 10 . FIG. 8 is an enlarged front view of the fitting protrusion 12 . FIG. 9 is an enlarged side view of the fitting protrusion 12 . FIG. 10 is a cross-sectional view in the width direction schematically showing an example of a mold MD for molding the preform 40 in the bristle molded body 20 . FIG. 11 is a cross-sectional view in the width direction schematically showing an example of the mold MD for molding the base body molded body 50 in the bristle molded body 20 . 12 is a cross-sectional view in the longitudinal direction schematically showing an example of the secondary molding die MD. FIG. 13 is a cross-sectional view in the width direction of the formed bristle body 20 according to the second embodiment. Fig. 14 is a front view of the bristle molded body 20 according to the third embodiment. FIG. 15 is a cross-sectional view in the width direction of the bristle molded body 20 according to the third embodiment. FIG. 16 is a front view showing a modification of the formed bristle body 20 according to the third embodiment. 17 is a cross-sectional view in the longitudinal direction showing a modification of the bristle molded body 20 according to the third embodiment. FIG. 18 is a cross-sectional view in the width direction of the formed bristle body 20 according to the fourth embodiment.

1: toothbrush

10: Handle body

11: Handle

20: Bristle forming body

Claims (16)

A bristle molded body having a brush head base portion formed of a soft resin, and a plurality of filaments protruding from a support surface located on the front side in the thickness direction of the brush head base portion, The brush head base portion has a fitting hole extending in a longitudinal direction orthogonal to the thickness direction and opening to one side of the longitudinal direction, The bristle shaped body includes: a preform having a filament group including at least a part of the plurality of filaments, and a support seat part, at least a part of which is formed from a first resin composition, the support seat part supporting a base of the filament group, and is located on the front side of the fitting hole and forms a part of the base of the brush head; and A base body molded body having a portion other than the preform among the brush head base portion and the plurality of filaments, and being molded from a second resin composition different from the first resin composition , The preform and the base body formed body are formed integrally. The bristle shaped body according to claim 1, wherein A part of the plurality of filaments constitutes the filament group formed from the first resin composition, The filaments other than the filament group among the plurality of filaments constitute the base body molded body integrally molded with the brush head base portion by the second resin composition. The bristle shaped body according to claim 1 or claim 2, wherein On the cross section of the brush head base part orthogonal to the longitudinal direction, If the cross-sectional area of the support seat is S1, Let S be the cross-sectional area of the region between the surface on the front side inside the fitting hole and the support surface, Then, the value represented by S1/S is 0.6 or less in the entire region where the fitting hole is provided. The bristle shaped body according to claim 3, wherein On the cross section orthogonal to the length direction, Assuming that the cross-sectional area of the fitting hole is SV, Let the cross-sectional area of the brush head base portion including the cross-sectional area of the fitting hole be SW, Then, the value represented by SV/(SW-S1) is 0.5 or less in the entire region where the fitting hole is provided. The bristle shaped body according to any one of claims 1 to 4, wherein If the area of the said brush head base part seen from the front side of the said thickness direction is made into P, Let the area of the said support seat part viewed from the front side in the said thickness direction be P1, Then, the value represented by P1/P is 0.1 or more and 0.5 or less. The bristle shaped body according to any one of Claims 1 to 5, wherein The maximum distance from the base end of the filament to the back surface of the brush head base portion on the opposite side to the front side in the thickness direction is 2.0 mm or more and 4.5 mm or less. The bristle shaped body according to claim 6, wherein If the maximum distance from the base end of the filament to the back surface of the brush head base is T, Let the thickness of the support seat portion in the thickness direction be t1, Then the value represented by t1/T is 0.5 or less. The bristle shaped body according to claim 7, wherein If the distance between the surface on the back side of the support seat portion and the surface on the front side inside the fitting hole is t2, Then, the value represented by t1/(t1+t2) is 0.2 or more and 0.8 or less. The bristle molded body according to any one of Claims 1 to 8, wherein, if the number of the filaments in the filament group is FM, the support seat and the base are When the area where the seat body molded body is bonded is set to Q1 (mm ² ), the value represented by FM/Q1 is 1.0 (pieces/mm ² ) or less. The bristle shaped body according to any one of Claims 1 to 9, wherein A concave-convex structure is arranged on the bonding interface between the support seat and the base body forming body. The bristle shaped body according to any one of claims 1 to 10, wherein Assuming that the maximum length of the brush head base in the longitudinal direction is L1, Let the maximum length of the fitting hole in the longitudinal direction be L2, Then, the value represented by L2/L1 is 0.30 or more and 0.70 or less. The bristle shaped body according to any one of Claims 1 to 11, wherein The preform has all of the plurality of filaments. The bristle shaped body according to any one of Claims 1 to 11, wherein The preform has: the filament group and the support seat are formed from the first resin composition; and The second filament group and the second support seat portion supporting the base of the second filament group are formed of a third resin composition different from the first resin composition and the second resin composition. The bristle shaped body according to any one of claims 1 to 13, wherein The soft resin is polyurethane. A toothbrush comprising: The bristle shaped body of any one of claims 1 to 14; and The handle body is formed of a hard resin, and has a fitting protrusion that is detachably attached to the fitting hole of the bristle molded body. A toothbrush comprising: The bristle shaped body of any one of claims 1 to 14; and a handle body having a fitting protrusion to be fitted into the fitting hole of the bristle molded body, The bristle forming body and the handle body are integrally formed forming bodies.

Images