WO2022138650A1 - 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

Brush moldings and toothbrushes

The present invention relates to a brush molded body and a toothbrush.
This application claims priority based on Japanese Patent Application No. 2020-214798 filed in Japan on December 24, 2020, the contents of which are incorporated herein by reference.

An integrally molded toothbrush that manufactures a toothbrush only with an injection molding machine has been proposed (for example, Patent Document 1). Since the integrally molded toothbrush integrally molds the filament and the head base (or head), there is no need for filament material procurement and a flocking machine, and it has the advantage that it can be manufactured at a lower cost than a flocking toothbrush. ..

As an integrally molded toothbrush for brushing, a head portion (brush molded body) having a filament and an insertion hole and a handle portion having an insertion portion at one end are separately molded and integrally molded by fitting them. It has been proposed to provide a toothbrush (eg, Patent Documents 2 and 3). In the toothbrushes described in Patent Documents 2 and 3, since the head portion can be replaced by the user, it is expected to save resources such that only the head portion can be discarded and the handle can be used repeatedly.

Since the head portion is made of a single resin material, there is a limit to improving the usability and appearance (design) of the toothbrush.
Patent Document 4 discloses a technique for insert molding a filament made of a plurality of different types of resin compositions by using a mold in which a separately molded handle portion is arranged.

Jitsukaisho 61-207233 China Utility Model No. 204561298 Chinese Patent Application Publication No. 1070417992 China Utility Model No. 205214577

However, in the toothbrush described in Patent Document 4, since the wall for partitioning the multicolored filaments is provided, the filaments cannot be arranged on the wall portion and a space is formed. Therefore, it is difficult to arrange the filaments in a regularly continuous profile, and there is a problem that the gentle touch feeling of the head portion inserted into the oral cavity is impaired.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a brush molded body and a toothbrush that have a gentle touch feeling and can improve the usability and appearance of the toothbrush.

According to the first aspect of the present invention, it has a head base portion made 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 head base portion. The head base portion has a fitting hole extending in a length direction orthogonal to the thickness direction and opening on one side in the length direction, and the filament group including at least a part of the plurality of filaments. A support base portion that supports the base portion of the filament group and is located on the front side of the fitting hole to form a part of the head base base portion, and at least a part thereof is the first resin. A second resin composition having a preformed body molded from the composition, a head base portion, and a portion of the plurality of filaments other than the preformed body, which is different from the first resin composition. Provided is a brush molded body comprising a base body molded body molded from an object, wherein the preformed body and the base body molded body are integrally molded bodies. To.

Further, in the brush-molded body according to one aspect of the present invention, a part of the plurality of filaments constitutes the filament group molded from the first resin composition, and among the plurality of filaments, the said The filament other than the filament group is characterized by constituting the base body molded body integrally molded with the head base portion with the second resin composition.

Further, in the brush molded body according to one aspect of the present invention, the cross-sectional area of the support base portion is set to S1 in the cross section orthogonal to the length direction of the head base portion, and the inside of the fitting hole is described. Assuming that the cross-sectional area of the region located between the front surface and the support surface is S, the value represented by S1 / S is 0.6 or less in all the regions where the fitting holes are provided. It is characterized by that.

Further, in the brush molded body according to one aspect of the present invention, if the cross-sectional area of the fitting hole is SV and the cross-sectional area of the head base portion is SW in the cross section orthogonal to the length direction, SV. The value represented by / (SW-S1) is characterized by being 0.5 or less in all the regions where the fitting holes are provided.

Further, in the brush molded body according to one aspect of the present invention, the area of the head base portion seen from the front side in the thickness direction is P, and the support base portion seen from the front side in the thickness direction. Assuming that the area of P1 is P1, the value represented by P1 / P is 0.1 or more and 0.5 or less.

Further, in the brush molded body according to one aspect of the present invention, the maximum distance from the base end of the filament to the back surface of the head base portion on the opposite side to the front side in the thickness direction is 2.0 mm or more. , 4.5 mm or less.

Further, in the brush molded body according to one aspect of the present invention, the maximum distance from the base end of the filament to the back surface of the head base portion is T, and the thickness of the support base portion in the thickness direction is t1. Then, the value represented by t1 / T is characterized by being 0.5 or less.

Further, in the brush molded body according to one aspect of the present invention, where t2 is the distance between the back surface side surface of the support base portion and the front surface side surface inside the fitting hole, t1 / (t1 + t2). ) Is 0.2 or more and 0.8 or less.

Further, in the brush molded body according to one aspect of the present invention, the number of the filaments in the filament group is FM, and the area where the support base portion adheres to the base body molded body is Q1 (mm ² ). , The value represented by FM / Q1 is 1.0 (line / mm ² ) or less.

Further, the brush molded body according to one aspect of the present invention is characterized in that a concavo-convex structure is provided at the adhesive interface between the support base portion and the base main body molded body.

Further, in the brush molded body according to one aspect of the present invention, the maximum length of the head base portion in the length direction is L1, and the maximum length of the fitting hole in the length direction is L2. , L2 / L1 is characterized by being 0.30 or more and 0.70 or less.

Further, in the brush molded body according to one aspect of the present invention, the preformed body is characterized by having all of the plurality of filaments.

Further, in the brush molded body according to one aspect of the present invention, the preformed body includes the filament group and the support base portion molded from the first resin composition, the first resin composition, and the first resin composition. It is characterized by having a second filament group and a second support base portion that supports the base of the second filament group, which is formed of a third resin composition different from the second resin composition. ..

Further, in the brush molded body according to the above aspect of the present invention, the soft resin is characterized by being polyurethane.

According to the second aspect of the present invention, the brush molded body of the first aspect of the present invention and a handle formed of a hard resin and having a removable fitting protrusion in the fitting hole of the brush molded body. A toothbrush characterized by having a body is provided.

According to the third aspect of the present invention, the brush-molded body of the first aspect of the present invention and the handle body having a fitting protrusion that fits into the fitting hole of the brush-molded body are provided. Provided is a toothbrush characterized in that the brush molded body and the handle body are integrally molded molded bodies.

The present invention can provide a brush molded body and a toothbrush that have a gentle touch feeling and can improve the usability and appearance of the toothbrush.

It is a front view of the brush molded body 20 and the toothbrush 1 which concerns on embodiment of this invention. It is a side view of the brush molded body 20 and the toothbrush 1. It is a front view of the brush molded body 20. FIG. 3 is a cross-sectional view taken along the line AA in FIG. It is a figure which looked at the brush molded body 20 from the rear end side. It is sectional drawing in the plane parallel to the support surface 21a including a fitting hole 22. It is a front view of the handle body 10. It is an enlarged front view of the fitting protrusion 12. It is an enlarged side view of the fitting protrusion 12. It is sectional drawing in the width direction which showed the example of the mold MD which forms the preformed body 40 among the brush molded body 20 simply. It is sectional drawing in the width direction which showed the example of the mold MD which forms the base main body molded body 50 among the brush molded body 20 simply. It is sectional drawing in the length direction which showed the example of the mold MD for secondary molding simply. It is sectional drawing in the width direction of the brush molded body 20 which concerns on 2nd Embodiment. It is a front view of the brush molded body 20 which concerns on 3rd Embodiment. It is sectional drawing in the width direction of the brush molded body 20 which concerns on 3rd Embodiment. It is a front view which shows the modification of the brush molded body 20 which concerns on 3rd Embodiment. It is sectional drawing in the length direction which shows the modification of the brush molded body 20 which concerns on 3rd Embodiment. It is sectional drawing in the width direction of the brush molded body 20 which concerns on 4th Embodiment.

Hereinafter, embodiments of the brush molded body and the toothbrush of the present invention will be described with reference to FIGS. 1 to 18. In this embodiment, an example of a toothbrush in which a brush molded body is detachably provided on a handle body will be described.

Note that 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. Further, in the following drawings, in order to make each configuration easy to understand, the scale and number of each structure are different from the actual structure.

FIG. 1 is a front view of the brush molded body 20 and the toothbrush 1 according to the present embodiment. FIG. 2 is a side view of the brush molded body 20 and the toothbrush 1. The toothbrush 1 includes a rod-shaped handle body 10 and a brush molded body 20. 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 molded body 20 is made of a soft resin. The handle body 10 is made of a hard resin.

The front surface in the present embodiment refers to the filament 23 described later 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. The protruding side (upper side in FIG. 2). In the thickness direction of the brush molded body 20, the side opposite to the front side is appropriately referred to as a back side. Further, the length direction of the handle body 10 and the direction in which the handle body 10 is inserted into the brush molded body 20 (hereinafter, simply referred to as the insertion direction) is orthogonal to the normal direction. In the length direction, the side on which the handle body 10 is mounted is referred to as the rear end side with respect to the brush molded body 20, and the side opposite to the rear end side is appropriately referred to as the tip end side. Further, 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).

[First Embodiment of Brush Molded Body 20]
FIG. 3 is a front view of the brush molded body 20. FIG. 4 is a cross-sectional view taken along the line AA in FIG. As shown in FIGS. 3 and 4, the brush molded body 20 includes a head base portion 21 having a substantially rectangular front view shape, and a plurality of filaments 23 provided on the front surface of the head base portion 21. There is.

As the soft resin constituting the brush molded body 20, various elastomers can be used, but polyurethane is preferable.
Polyurethane tends to have higher tensile strength than other elastomers such as styrene and polyester. Therefore, by using polyurethane as the soft resin, mechanical strength can be secured even if the thickness is thin, and the handle body 10 It is possible to suppress damage when the toothbrush and the toothbrush 1 are fitted to the fitting hole 22 and when the toothbrush 1 is used.

In polyurethane, 0.01-1.0 wt% (% by mass) of saturated / unsaturated hydrocarbons of C10 or more, higher alcohols, fatty acid amides, fatty acid esters, low molecular weight polyethylenes, polyethylene glycols (PEG), fatty acid metal salts , Long-chain fatty acid, fatty acid glycerin, liquid paraffin, silicone, or a combination thereof, and functions as a lubricant and a mold release agent.

Further, polyurethane has a wider range of hardness that can be selected as compared with the above-mentioned other elastomers, and the resin hardness can be selected in consideration of its usability (for example, bending of the tip of the brush molded body) according to the thickness of the brush molded body 20. It is possible. The hardness of the polyurethane is preferably shore 90A or more and 70D or less.
When the hardness of the polyurethane is softer than that of the shore 90A, it is easily deformed when it is formed of a thin wall, so that the fitting is weakened and the brush molded body 20 is easily dropped when the toothbrush 1 is used. If the hardness of the polyurethane is harder than the shore 70D, pain may occur when the tip of the head base 21 hits the oral tissue when the back surface of the head base 21 is tilted. By setting the hardness of the polyurethane to 90A or more and 70D or less, it is possible to prevent the brush molded body 20 from falling off when the toothbrush 1 is used and the pain when the tip of the head base portion 21 hits.

Further, 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 is a substantially columnar shape protruding from the support surface 21a located on the front side in the thickness direction of the head base portion 21 toward the front side. The support surface 21a of the head base portion 21 is a plane 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 filament 23 has a substantially triangular prism shape having a substantially triangular cross section on the base end side, and a triangular pyramid shape having a tip end side extending from the substantially triangular prism shape and tapering. As the cross-sectional shape of the filament 23, in addition to a substantially triangular shape, a substantially polygonal shape such as a substantially quadrangle, a substantially circular shape, a substantially star shape, a substantially spatula shape, or the like can be selected. The filament 23 may have a tapered shape in which the tip is tapered, a structure in which the filament 23 extends straight, or a tapered shape in which the filament 23 is tapered from the base end.

The filament 23 is provided with a plurality of rows along the insertion direction so that the rows arranged along the width direction of the brush molded body 20 are offset by half a pitch from the adjacent rows in the insertion direction. That is, the filaments 23 are arranged in a staggered pattern.

FIG. 5 is a view of the brush molded body 20 as viewed from the rear end side.
As shown in FIG. 5, the plurality of filaments 23 have a filament group (first filament group) F1 located in the center in the width direction and a filament group 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 filament 23 is preferably 7 mm or more, and more preferably 9 mm or more.
The maximum length of the filament 23 is preferably 15 mm or less, more preferably 13 mm or less.
The maximum length of the filament 23 is preferably 7 mm or more and 15 mm or less, and more preferably 9 mm or more and 13 mm or less.
If the maximum length of the filament 23 is less than 7 mm, the cleanability in the oral cavity may be deteriorated. If the maximum length of the filament 23 exceeds 15 mm, the releasability when the brush molded body 20 is molded by injection molding is deteriorated. 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 cleanability in the oral cavity and the releasability at the time of molding.

The cross-sectional area of the base 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 base end of the filament 23 exceeds 0.8 mm ² , the filament 23 is less likely to bend, and there is a possibility that the cleanability of gaps between teeth and the cervical region is reduced. 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 the cleanability of gaps between teeth and the cervical region.

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 and 50% or less. If the ratio of the total cross-sectional area of the proximal end of the filament 23 is less than 10%, the cleanability in the oral cavity may be deteriorated. If the ratio of the total cross-sectional area of the base end of the filament 23 exceeds 50%, the releasability when the brush molded body 20 is molded by injection molding is lowered. By setting the ratio of the total cross-sectional area of the base end of the filament 23 to 10% or more and 50% or less, it is possible to secure the cleanability in the oral cavity and the releasability at the time of molding.

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.
As the first resin composition and the second resin composition, the above-mentioned soft resin can be appropriately selected in consideration of the usability and appearance (design) of the toothbrush 1. For example, in the case of achieving both a massage property and a brushing feeling in consideration of the feeling of use of the toothbrush 1, the above-mentioned soft resins having different hardness can be used. Further, when the appearance is taken into consideration, it is also possible to use the above-mentioned soft resin as a base material and add a colorant such as a masterbatch to make the filament group F1 and the filament group F2 different colors.

The head base portion 21 has a support base portion 30 and a fitting hole 22.
The support base portion 30 supports the base end of the filament group F1 from below. As shown in FIG. 3, the support base portion 30 has a size including the filament group F1 and has a rectangular parallelepiped shape in a front view. As shown in FIG. 4, the upper surface of the support base portion 30 is flush with the support surface 21a. That is, the upper surface of the support base portion 30 constitutes a part of the support surface 21a. Hereinafter, the upper surface of the support base portion 30 is also appropriately referred to as a support surface 21a.

The support base portion 30 is located on the front side of the fitting hole 22. A part of the head base portion 21 is formed. The support base portion 30 is formed of the first resin composition. The support base portion 30 and the filament group F1 form a preformed body 40 integrally molded by the first resin composition.

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

The head base portion 21 has a protrusion 35 located substantially in the center of the fitting hole 22 in the insertion direction and located between the first portion 33 and the second portion 34. The protrusions 35 are provided on both sides of the fitting hole 22 in the width direction. The protrusion 35 is provided at a position where the fitting protrusion 12 (see FIG. 7; described later) of the handle body 10 is fitted into the recess 15 (described later) when the fitting protrusion 12 (see FIG. 7; described later) is inserted into the fitting hole 22. The protrusion 35 has an arc shape having an arc center on the outside in the width direction and being convex 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. The amount of protrusion of the protrusion 35 inward in the width direction with respect to the second portion 34 is, for example, 1 mm. The amount of protrusion of the protrusion 35 with respect to the second portion 34 is the amount of undercut when the mold (slide core) for forming the fitting hole 22 is pulled out to the rear end side during injection molding of the brush molded body 20.

Of the brush molded body 20, the head base portion 21 other than the support base portion 30 is formed of the second resin composition. Of the brush molded body 20, the head base portion 21 other than the support base portion 30 and the filament group F2 constitute a base body molded body 50 integrally molded by the second resin composition. The brush 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 preformed body 40 primaryly molded by the first resin composition is placed in a cavity in the mold, and the cavity is filled with the second resin composition for secondary molding (insert molding). Molds the molded product.

Returning to FIG. 5, in the cross section orthogonal to the length direction of the head base portion 21, the thickness t1 of the support base portion 30 is selected from 0.5 mm to 2.5 mm. The thickness t2 between the back surface of the support base portion 30 and the front surface side surface inside the fitting hole 22 is selected from 0 mm to 2.5 mm. Thickness of the back surface of the support base 30 and the front surface inside the fitting hole 22 when the back surface of the support base 30 and the front surface inside the fitting hole 22 are flush with each other. t2 is 0 mm. That is, it is possible to select a configuration in which the back surface of the support base portion 30 is exposed to the fitting hole 22 and faces the fitting hole 22. In this case, the side surface of the support base portion 30 in the width direction is adhered to and fixed to the base main body molded body 50.

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

In the cross section orthogonal to the length direction of the head base portion 21, the cross-sectional area of the support base portion 30 is S1, and the thickness t1 + t2 located between the front surface side surface and the support surface 21a inside the fitting hole 22. Assuming that the cross-sectional area of the region is S, the value represented by S1 / S is preferably 0.1 or more in all the regions where the fitting holes 22 are provided.
The value represented by S1 / S is preferably 0.6 or less, more preferably 0.5 or less, and further preferably 0.4 or less.
The values represented by S1 / S are preferably 0.1 or more and 0.6 or less, more preferably 0.1 or more and 0.5 or less, and 0.1 or more and 0.4 or less. Is more preferable.

In the brush molded body 20 having the fitting hole 22, the cross-sectional area S of the region defined by the thickness t1 + t2 between the front surface side surface and the support surface 21a inside the fitting hole 22 and the support base portion 30. The cross-sectional area S1 of the above has a great influence on the formability of the filament 23. In multicolor molding, after molding on the primary side, the movable side (or fixed side) of the mold is switched to mold the secondary side and subsequent sides, so that molding proceeds while the molded body on the primary side remains in the cavity. The flowable region after the secondary side becomes smaller. Therefore, unlike monochromatic molding, multicolor molding tends to lack resin fluidity from the secondary side onward, making filament molding difficult. In this case, since a sufficient filling speed and holding pressure cannot be secured, molding defects such as short circuits and sink marks are likely to occur. Specifically, when the value represented by S1 / S exceeds 0.6, molding defects of the filament 23 are likely to occur. In the present embodiment, by setting the value represented by S1 / S to 0.6 or less, molding defects of the filament 23 can be suppressed. From the viewpoint of ensuring the moldability of the support base portion 30 and the filament group F1 on the primary side, the value represented by S1 / S is preferably 0.1 or more.

In the cross section orthogonal to the length direction of the head base portion 21, the cross-sectional area of the fitting hole 22 is SV, and the cross-sectional area of the head base portion 21 including the cross-sectional area SV of the fitting hole 22 is SW. The value represented by / (SW-S1) is preferably 0.1 or more in all the regions where the fitting holes 22 are provided. The value represented by SV / (SW-S1) is preferably 0.5 or less, more preferably 0.4 or less, and further 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 0.1 or more, It is more preferably 0.3 or less.

In molding other than the primary side, that is, in the molding of the base body molded body 50, in addition to the presence of the preformed body 40 on the primary side previously molded, the presence of the slide core for forming the fitting hole 22 is present in the resin flow. Has a great impact on. If the occupancy of the slide core is small, the resin tends to flow in the cavity, and the moldability of the filament 23 is improved. On the contrary, when the value represented by SV / (SW-S1) indicating the occupancy rate of the slide core exceeds 0.5, the resin flow is restricted during the molding of the base body molded body 50, and the secondary side is used. Subsequent molding defects of the filament 23 (filament group F2) may occur. In the present embodiment, by setting the value represented by SV / (SW-S1) to 0.5 or less, molding defects of the filament 23 can be suppressed. From the viewpoint of ensuring the strength of the slide core, the value represented by SV / (SW-S1) is preferably 0.1 or more.

Assuming that the area (projected area) of the head base portion 21 in the front view seen from the front side in the thickness direction is P and the area of the support base portion 30 in the same front view is P1, it is represented by P1 / P. The value is preferably 0.1 or more, and more preferably 0.2 or more. The value represented by P1 / P is preferably 0.5 or less, and more preferably 0.4 or less. The values represented by P1 / P are preferably 0.1 or more and 0.5 or less, more preferably 0.1 or more and 0.4 or less, and 0.2 or more and 0. It is more preferably 4 or less.

As a means for improving the moldability of the filament 23 (filament group F2) other than the primary side, the resin flow flowing in the direction parallel to the support surface 21a is also important. In particular, when the gate is located at the end portion of the brush molded body 20 in the length direction, such as a side gate, it contributes significantly. Therefore, when the value represented by P1 / P exceeds 0.5, the resin flow is hindered by the occupation of the cavity region by the preformed body 40 on the primary side, and the base body molded body 50 on the secondary side and thereafter. There is a possibility that molding defects of the filament 23 may occur during molding. On the other hand, when the value represented by P1 / P is less than 0.1, the occupancy rate of the filament group F1 becomes low and the functionality (for example, cleanability) may not be ensured. In the present embodiment, by setting the values represented by P1 / P to 0.1 or more and 0.5 or less, it is possible to suppress molding defects of the filament 23 while ensuring the functionality of the filament group F1.

The maximum distance (maximum thickness) between the support surface 21a of the head base portion 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 2.0 mm or more and 4.5 mm or less. Is preferable. When the maximum distance T is less than 2.0 mm, the gap between the support surface 21a and the surface of the fitting hole 22 on the support surface 21a side, or the back surface 21c and the surface of the fitting hole 22 on the back surface 21c side. Since the gap between the two is reduced and the fluidity of the molten resin is reduced during molding of the base body molded body 50, the resin may not be filled. Further, 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 21a side and the support base portion 30 must be reduced, and the base main body molded body 50 must be reduced. The fluidity of the molten resin decreases during molding. If the maximum distance T exceeds 4.5 mm, the operability when the brush molded body 20 is inserted into the oral cavity may be deteriorated. In the present embodiment, by setting the maximum distance T to 2.0 mm or more and 4.5 mm or less, the filling property of the resin and the operability when the brush molded body 20 is inserted into the oral cavity can be ensured.

Assuming that the maximum distance from the base end of the filament 23 to the back surface 21c of the 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 0. It is preferably 5 or less, and more preferably 0.4 or less. When the value represented by t1 / T exceeds 0.5, the entire brush molded body 20 becomes thicker in the oral cavity in order to secure the resin flow when molding the base body molded body 50 other than the primary side. This leads to a decrease in operability. In the present embodiment, by setting the value represented by t1 / T to 0.5 or less, it is advantageous for both the moldability and the usability of the base main body molded body 50 on the secondary side and thereafter at the time of molding. From the viewpoint of formability on the primary side and ensuring the adhesiveness of the side surface of the primary side support base portion 30 to the head base portion 21, the value represented by t1 / T is preferably 0.1 or more.

Further, the thickness t2 between the thickness t1 and the front surface inside the fitting hole 22 is preferably a value represented by t1 / (t1 + t2) of 0.2 or more. , 0.3 or more is more preferable. The value represented by t1 / (t1 + t2) is preferably 0.8 or less, and more preferably 0.7 or less. 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, it is not possible to secure a sufficient space for the resin to flow between the back surface of the primary side (the back surface of the support base 30) and the slide core, so that the support is supported. It depends on the resin flow on the side surface side of the base portion 30, and there is a possibility that the moldability of other than the primary side (base main body molded body 50) may decrease. Further, the resin adhesiveness between the support base portion 30 on the primary side and the base body molded body 50 on the secondary side may not be stable. If the value represented by t1 / (t1 + t2) is less than 0.2, the formability of the support base portion 30 on the primary side may not 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 support base portion 30 on the primary side and the base main body molded body 50 on the secondary side are molded. It is possible to secure the property and stabilize the resin adhesiveness between the support base portion 30 and the base main body molded body 50.

If the thickness t2 is 0.3 mm or more, it is unlikely that a problem will occur in moldability even if the head has a wide head specification. The thickness t2 is preferably 0.5 mm or more, and more preferably 0.8 mm or more.

Assuming that the number of filaments in the filament group F1 is FM and the area where the support base portion 30 adheres to the base body molded body 50 is Q1 (mm ² ), the value expressed by FM / Q1 is 1.0 ( It is preferably 1 / mm ² ) or less, and more preferably 0.8 (/ mm ² ) or less. The filament 23 is pulled out by the mold release resistance on the cavity surface at the time of mold release after molding. When the value represented by FM / Q1 exceeds 1.0 (book / mm ² ), in multicolor molding, the preformed body 40 and the base body molded body 50 are separated after the secondary molding. At the time of molding, the preformed body 40 may be peeled off from the base body molded body 50 due to the mold release resistance of the filament group F1. In the present embodiment, by setting the value represented by FM / Q1 to 1.0 (book / mm ² ) or less, the preformed body 40 is peeled off from the base body molded body 50 after the secondary molding. Can be suppressed. If the number of filament group F1s cannot be sufficiently secured with respect to the occupied area of the support base portion 30, the value represented by FM / Q1 is set to 0 in consideration of the possibility that the functionality of the primary side filament F1 is deteriorated. It is preferably .2 (lines / mm ² ) or more.

From the viewpoint of suppressing the preformed body 40 from peeling off from the base body molded body 50 after the secondary molding, there is one or more uneven structures at the adhesive interface between the support base portion 30 and the base body molded body 50. It is preferable to be provided. The bonding interface between the support base portion 30 and the base body molded body 50 is not smooth, and an uneven structure is provided to increase the bonding area while ensuring moldability, and to bond the preformed body 40 on the primary side. It is possible to improve the sex. The uneven structure may be arranged on either the back surface or the side surface of the support base portion 30, but the arrangement on the back surface is effective in increasing the adhesive area because the height and width of the unevenness are likely to be larger than those on the side surface. When the uneven structure is arranged on the side surface of the support base portion 30, the thickness of the support base portion 30 and the undercut when molding the preformed body 40 may be taken into consideration. For example, the height (highest to lowest) of the uneven structure may be about 0.1 to 0.5 mm, and the pitch of the uneven structure may be about 0.5 to 3.0 mm.

As shown in FIG. 4, assuming that the maximum length of the head base portion 21 in the length direction is L1 and the maximum length of the fitting hole 22 is L2, the value represented by L2 / L1 is 0.30. The above is preferable, 0.40 or more is more preferable, and 0.45 or more is further preferable. The value represented by L2 / L1 is preferably 0.70 or less, more preferably 0.60 or less, and further preferably 0.55 or less. The values represented by L2 / L1 are preferably 0.30 or more and 0.70 or less, more preferably 0.40 or more and 0.60 or less, and 0.45 or more and 0. It is more preferably 55 or less.

When the value represented by L2 / L1 is less than 0.30, the region where the fitting protrusion 12 of the handle body 10 made of the hard resin does not exist becomes large, so that the front surface of the brush molded body 20 tends to bend. , The usability as a toothbrush 1 may decrease. When L2 / L1 exceeds 0.70, the volume occupied by the mold (slide core) forming the fitting hole 22 during molding becomes large, and the resin flow is restricted, so that the moldability of the filament 23 deteriorates. Resulting in. By setting the values represented by L2 / L1 to 0.30 or more and 0.70 or less, it is possible to suppress the deterioration of the moldability of the filament 23 and the deterioration of the usability of the toothbrush 1.

[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 tip of the handle portion 11 and projecting toward the tip end side of the handle portion 11 in the length direction. ing. The fitting protrusion 12 is detachably fitted into the fitting hole 22 of the brush 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 brush molding 20 described above, so that the fitting protrusion 12 is covered with the brush molding 20 and attached. ..

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 and then extends at a constant width, and then gradually widens and then narrows. It changes in a curve. The front view shape of the handle portion 11 has a substantially semicircular shape at the rear end portion.

As shown in FIG. 2, the side view shape of the handle portion 11 extends from the front end side to the rear end side with a certain width, and then 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 pad portion having the maximum thickness toward the rear end side. The side view shape of the handle portion 11 has a substantially semicircular shape at the rear end portion.

In the present invention, the shape of the handle portion is not limited to the shape of this example, and can be appropriately set in consideration of strength, operability, design, 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 to 200 mm.

The fitting protrusion 12 is a portion covered with the brush molded body 20 in a state where the brush molded body 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 in a state where the brush molded 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 has a base portion 13 provided on the tip end side of the handle portion 11 and a tip portion 14 provided at the tip end of the base portion 13. As shown in FIG. 9, the base portion 13 and the tip portion 14 have steps on both sides of the front side and the back surface side with respect to the handle portion 11 and are formed to have the same thickness thinner than the handle portion 11.

The base 13 has a substantially rectangular shape in a plan view. The base portion 13 has a step with respect to the handle portion 11 on both sides in the width direction, and is formed with a width L13 narrower than the maximum width L11 on the tip end side of the handle portion 11 (L13 <L11). The tip portion 14 has a substantially elliptical shape in a plan view with the width direction as the major axis direction. The tip portion 14 has a substantially elliptical shape on both sides in the width direction, with side edges cut out in a straight line parallel to the insertion direction of the fitting protrusion 12. The tip portion 14 has a step 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 is substantially in the center in the insertion direction, and has a recess 15 between the base portion 13 and the tip portion 14. The recesses 15 are provided on both sides in the width direction. The recess 15 has an arc shape having an arc center on the outside and a concave on the inside in the width direction. The shortest distance L15 between the recesses 15 is shorter than the width L13 of the base 13 and the width L14 of the tip 14. The amount of the dent 15 in the tip portion 14 with respect to the edge defining the width L14 is, for example, 1 mm.

The handle body 10 is made of a 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. Specifically, for example, polypropylene resin (PP), polyacetal resin (POM), polyester resin (PCTA), polyethylene terephthalate copolymer (PETG), and high density polyethylene (HDPE) can be exemplified. Among these, PP, which is a general-purpose resin, is preferable in consideration of cost.

The maximum width L21 on the rear end side (end surface 21b) of the head base portion 21 is substantially the same as the maximum width on the tip 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 tip portion 14 of the fitting protrusion 12 can be inserted, and is substantially the same as the maximum width L14 of the tip portion 14. The shortest distance L35 between the protrusions 35 is a length into which the tip portion 14 and the recess 15 in the fitting protrusion 12 can be inserted, and is substantially the same as the shortest distance L15 between the recesses 15.

Subsequently, the procedure for molding the brush molded body 20 will be described with reference to FIGS. 10 to 12. FIG. 10 is a cross-sectional view in the width direction which simply shows an example of the mold MD for molding the preformed body 40 among the brush molded bodies 20.

The mold MD includes a first mold MD1 that moves relative to the opening / closing direction (vertical direction in FIG. 10) and a second mold MD2 for primary molding. The first mold MD1 and the second mold MD2 are molded with the parting surface PL flush 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 an injection molding machine, and the molten resin is filled 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 with respect to the first mold MD1 to open / close the mold MD.

When the first mold MD1 is molded and joined to the second mold MD2, the molding surface 21aM on which the support surface 21a is formed, the cavity F1M in which the filament group F1 is formed, and the filament group F2 are formed. It has a cavity F2M to be formed. The cavity F1M and the cavity F2M are open to the parting surface PL of the first mold MD1.

The second mold MD2 has a cavity 30M in which the support base portion 30 is formed when the mold is compacted and joined to the first mold MD1. The cavity 30M is open to the cavity F1M. The cavity 30M is not open to the cavity F2M. The opening of the cavity F2M is closed by the parting surface PL of the second mold MD2. The cavity 30M is provided with a gate portion (not shown). As the gate portion, for example, a side gate method is used, but a pinpoint gate method or a tunnel gate method may be used.

In the above mold MD, the melted first resin composition introduced into the cavity 30M from the gate portion G in a state where the first mold MD1 and the second mold MD2 are molded is the cavity 30M and the cavity. It is filled in F1M. On the other hand, the cavity 30M does not open into the cavity F2M, and the opening of the cavity F2M is not filled in the first resin composition because it is closed by the parting surface PL of the second mold MD2. After that, the first mold MD1 and the second mold MD2 are cooled in a molded state, so that the premolding is formed of the first resin composition having the filament group F1 and the support base portion 30. The body 40 is molded.

FIG. 11 is a cross-sectional view in the width direction which simply shows an example of a mold MD for secondary molding for molding the base body molded body 50 among the brush molded bodies 20. FIG. 12 is a cross-sectional view in the length direction which briefly shows an example of a mold MD for secondary molding.

The mold MD includes a first mold MD1 and a second mold MD12 that move relative to each other in the opening / closing direction. The first mold MD1 is the first mold MD1 that holds the molded preformed body 40 without releasing the mold. In addition, a part of the first mold MD1 for primary molding including the cavity F1M and the cavity F2M may be detached and mounted on the first mold MD1 for secondary molding.

The second mold MD12 has a cavity 21M in which the head base portion 21 is formed when the mold is compacted and joined to the first mold MD1, and the cavity 21M is opened to the tip end side, and molten resin is introduced into the cavity 21M. It has a gate portion G to be formed and a contact surface 21eM provided at a position of an end surface 21b in the insertion direction and orthogonal to the insertion direction. As shown in FIG. 11, the cavity F2M in which the filament group F2 is formed is open to the cavity 21M. As the gate portion G, for example, a side gate method is used, but a pinpoint gate method or a tunnel gate method may be used. The contact surface 21eM extends in a direction away from the PL surface from the position where the back surface of the head base portion 21 is formed in the second mold MD2.

The second mold MD12 is provided with a slide core SL. The slide core SL has a core portion 22M in which the fitting hole 22 is formed, and a forming surface 21bM in which the core portion 22M projects and is orthogonal to the insertion direction. As shown in FIG. 11, the molding surface 21bM is separated from the contact surface 21eM before mold clamping. In the slide core SL, when the first mold MD1 and the second mold MD12 are molded, a part of the molded surface 21bM comes into contact with the contact surface 21eM and the core portion 22M is formed. Is positioned at the position where it is inserted into the cavity 21M. Of the molding surface 21bM, the region facing the cavity 21M without contacting the contact surface 21eM is a region for molding the end surface 21b. Further, the slide core SL has a core so that the core portion 22M does not interfere with the mold release of the molded brush molded body 20 when the first mold MD1 and the second mold MD12 are opened. The portion 22M moves in a direction away from the cavity 21M. The movement direction of the slide core SL is preferably horizontal in order to avoid unexpected movement due to its own weight.

In the above-mentioned mold MD, the molten second resin composition introduced into the cavity 21M from the gate portion G in a state where the first mold MD1 and the second mold MD12 are molded is the cavity 21M and the cavity. It is filled in F2M. The second resin composition filled in the cavity 21M covers the side surface and the back surface of the support base portion 30 and is adhered to the support base portion 30. After that, the first mold MD1 and the second mold MD12 are cooled in a molded state and separated from the mold MD to have the filament group F1 and the support base portion 30. A base body having a preformed body 40 formed of a resin composition, a head base portion 21 and a plurality of filaments 23 other than the preformed body 40, and molded with a second resin composition. A molded body including the molded body 50, and the preformed body 40 and the base body molded body 50 are integrally molded can be obtained.

That is, the filament 23 having the filament group F1 formed of the first resin composition and the filament group F2 formed of the second resin composition, and the support base portion 30 formed of the first resin composition. A brush molded body 20 is obtained in which the head base portion 21 formed of the second resin composition is integrally molded as a molded body.

Regarding the molded brush molded body 20, the toothbrush 1 in which the brush molded body 20 and the handle body 10 are integrated is obtained by inserting the fitting protrusion 12 of the handle body 10 into the fitting hole 22 and fitting the brush molded body 20. can get. Further, by pulling out the fitting protrusion 12 of the handle body 10 from the fitting hole 22, the brush molded body 20 can be separated from the handle body 10 and replaced.

As described above, in the brush molded body 20 of the present embodiment, 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 Therefore, by appropriately selecting the first resin composition and the second resin composition according to the purpose, the brush has a gentle touch feeling and can improve the usability and appearance of the toothbrush 1. Molds and toothbrushes can be obtained.

[Second Embodiment of Brush Molded Body 20]
Next, a second embodiment of the brush molded body 20 will be described with reference to FIG. In these figures, the same components as the components of the first embodiment shown in FIGS. 1 to 12 are designated by the same reference numerals, and the description thereof will be omitted.
In the first embodiment, the configuration in which the preformed body 40 is molded with one type of resin composition is exemplified, but in the second embodiment, a configuration in which the preformed body 40 is molded with a plurality of types of resin compositions will be described.

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

The second support base portion 31 is molded from the third resin composition. The side surface and the back surface of the second support base portion 31 in the width direction are adhered to the support base portion 30. The front surface of the second support base 31 is flush with the support surface 21a. The preformed body 40 of the present embodiment has a filament group F3 and a second support base portion 31 molded from the third resin composition, and a filament group F1 and a support base portion 30 molded from the first resin composition. Is an integrally molded body.

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

In the brush molded body 20 of the present embodiment, the filament group F3 and the second support base portion 31 are formed by the third resin composition in the primary molding, and the filament group F1 is formed by the first resin composition in the secondary molding. And the support base portion 30 is formed, and the filament group F2 and the head base portion 21 are formed by the second resin composition in the tertiary molding, which is obtained by three-color molding. Alternatively, it can be obtained by insert molding in which the filament group F2 and the head base portion 21 are molded by the second resin composition using a mold on which the preformed body 40 molded in advance is installed.

The brush molded body 20 having the above configuration can obtain the same action and effect as the brush molded body 20 of the first embodiment, and also uses more kinds of resin compositions according to the specifications of the toothbrush 1. It is possible to provide a toothbrush 1 having various added values.

[Third Embodiment of the brush molded body 20]
Next, a third embodiment of the brush molded body 20 will be described with reference to FIGS. 14 and 15. In these figures, the same elements as the components of the second embodiment shown in FIG. 13 are designated by the same reference numerals, and the description thereof will be omitted.
In this embodiment, the filament group is simply shown as a region in which the filament group is arranged.

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

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

In this embodiment, in addition to obtaining the same actions and effects as those in the second embodiment, the filament 23 is arranged two-dimensionally in addition to the linear shape, so that the filament 23 can be further arranged according to the specifications of the toothbrush 1. It is possible to provide a toothbrush 1 having various added values by using many kinds of resin compositions.

As a configuration in which the filament 23 is arranged two-dimensionally, for example, as shown in the front view of FIG. 16 and the sectional view in the length direction of FIG. 17, the filament group F1 and the support base portion 30 and the filament group F3 are arranged. And the second support base portion 31 may be arranged side by side in the length direction.

[Fourth Embodiment of Brush Molded Body 20]
Subsequently, a fourth embodiment of the brush molded body 20 will be described with reference to FIG. In this figure, the same components as the components of the first embodiment shown in FIGS. 1 to 12 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 18 is a cross-sectional view of the brush molded body 20 according to the fourth embodiment in the width direction.
As shown in FIG. 18, the filament group F1 in the preformed body 40 of the present embodiment has all of the plurality of filaments 23.
Other configurations are the same as those in the first embodiment.

In the brush molded body 20 having the above configuration, as in the first embodiment, the filament group F1 and the head base portion 21 are molded with different resin compositions, so that the toothbrush 1 has a gentle touch feeling and a feeling of use of the toothbrush 1. It is possible to obtain a brush molded body and a toothbrush that can improve the appearance.

In the brush molded body 20 having the above configuration, since the preformed body 40 has all of the filaments 23, the mold release resistance of the preformed body 40 when the brush molded body 20 is removed from the mold becomes large. Therefore, as described above, the relationship between the number of filaments FM and the area Q1 where the support base portion 30 adheres to the base body molded body 50 and the bonding interface between the support base portion 30 and the base body molded body 50 are provided. It is preferable to adopt at least one with an uneven structure.

[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 appropriately modified and carried out without departing from the gist thereof.

(Examples 1 to 8, Comparative Example 1)
Toothbrushes having different at least one of the items shown in [Table 1] were used as samples of Examples 1 to 8 and Comparative Example 1. The resin constituting each sample was polyurethane.

[Evaluation method]
Each of the samples of Examples 1 to 8 and Comparative Example 1 was evaluated by the formability of the filament, the ease of polishing the entire oral cavity, and the adhesiveness of the preformed body on the primary molding side.

(1) Method for evaluating filament formability Five brush-molded bodies molded under the same conditions were evaluated according to the following criteria.
5 points: No deterioration in appearance is observed.
4 points: The tip of the filament is deformed at the time of mold release (because the pressure was not sufficiently applied, it bends due to the external force at the time of mold release).
3 points: The thickness of the filament tip 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 total length).
1 point: The length of the filament is shorter than the design value (there is a filament less than half of the total length).
Then, the average value of the five evaluation points was obtained, and the evaluation was performed according to the following four stages.
◎ (double circle mark): 4.5 or more, 5.0 points or less.
○ (circle mark): 3.5 or more, less than 4.5 points.
△ (triangle mark): 2.5 or more, less than 3.5 points.
× (cross mark): Less than 2.5 points.

(2) Evaluation method of the ease of brushing the entire oral cavity A sensory evaluation is performed by 10 specialized panelists, and the ease of brushing the entire oral cavity at the time of brushing (especially the ease of brushing the back teeth is emphasized) is the following criteria. Evaluated in.
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, the average value of the evaluation points by 10 specialized panelists was calculated, and the evaluation was performed according to the following four stages.
⊚: 4.5 or more, 5.0 points or less.
◯: 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.

(3) Method for evaluating the adhesiveness of the preformed body on the primary molding side Five brush-molded bodies molded under the same conditions were evaluated according to the following criteria.
5 points: No deterioration in appearance is observed.
4 points: The primary side base is deformed due to the mold release resistance at the time of mold release (the brush surface is no longer smooth).
3 points: No peeling is observed on the outside, but peeling is confirmed at the resin boundary when an external force is applied.
2 points: At the time of mold release, the base part on the primary side is partially peeled off and partially connected.
1 point: The entire primary side is peeled off and separated from the brush molded body (the primary side remains in the mold).
Then, the average value of the five evaluation points was obtained, and the evaluation was performed according to the following four stages.
⊚: 4.5 or more, 5.0 points or less.
◯: 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], it is a ratio of the cross-sectional area S1 of the support base portion 30 to the cross-sectional area S of the region located between the front surface and the support surface 21a inside the fitting hole 22. , Samples of Examples 1 to 8 in which the value represented by S1 / S is 0.6 or less For Example 1, the moldability of the filament, the ease of polishing the entire oral cavity, and the preformed body on the primary molding side. Good results were obtained in all of the adhesiveness. On the other hand, in the sample of Comparative Example 1 in which the value represented by S1 / S exceeded 0.6, good evaluation was not obtained in the formability of the filament.

Under the conditions shown in Example 1, good results were obtained for the moldability of the filament, the ease of polishing the entire oral cavity, and the adhesiveness of the primary preformed body.

Under the conditions shown in Example 2, the value represented by S1 / S increased with the expansion of the primary side support base. As a result, the resin flow from the secondary side onward decreased, and the formability of the filament was inferior to that of the sample of Example 1. Further, the number FM of the first filament group increased with the expansion of the primary side support base portion, but the adhesive area Q1 of the support base portion also increased, so that the adhesiveness of the primary side preformed body was the same as that of the sample of Example 1. It became.

Under the conditions shown in Example 3, the value represented by SV / (SW-S1) became larger as the slide core became thicker. As a result, the resin flow during molding of the base body molded body decreased, and the moldability of the filaments on the secondary side and thereafter was inferior to that of the sample of Example 1.

In both the samples of Example 4 and Example 5, the head thickness was increased, so that the ease of polishing the entire oral cavity was inferior to that of the sample of Example 1. Further, in the sample of Example 5, since the support base portion was also thickened at the same time, the value represented by t1 / T became large, and the resin flow when molding the base body molded body was higher than that of the sample of Example 4. The result was that the formability of the filament was inferior to that of the sample of Example 1.

Under the conditions shown in Examples 6 and 8, the value represented by t1 / (t1 + t2) becomes large, and sufficient space for resin to flow is secured between the back surface of the primary support base and the slide core. However, the resin flow decreased, and the formability of the filament was inferior to that of the sample of Example 1. However, as compared with the sample of Example 6, the back surface of the support base was not exposed to the front surface inside the fitting hole in the sample of Example 8, so that the adhesiveness of the primary preformed body was improved. It did not decrease.

Under the conditions shown in Example 7, the number FM of the first filament group increased as compared with Example 1, but the adhesive area Q1 of the support base did not change, so that FM / Q1 became large and the primary side prediction. The result was that the adhesiveness of the molded product was inferior to that of the sample of Example 1.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an example. The various shapes and combinations of the constituent members shown in the above-mentioned example are examples, and can be variously changed based on design requirements and the like within a range not deviating from the gist of the present invention.

For example, in the above embodiment, the toothbrush 1 is composed of a brush molded body 20 and a handle body 10 separately molded, and the fitting protrusion 12 of the handle body 10 is fitted into the fitting hole 22 of the brush molded body 20. By doing so, the configuration in which the brush molded body 20 is attached to the handle body 10 is illustrated, but the configuration is not limited to this configuration. For example, the fitting protrusion 12 of the handle body 10 may be installed in the mold on which the preformed body is installed instead of the slide core SL, and insert molding may be performed with the second resin composition at the time of secondary molding. .. By this insert molding, it is possible to obtain a toothbrush 1 as a molded body in which the fitting protrusion 12 is fitted into the fitting hole 22 and the brush molded body 20 and the handle body 10 are integrally molded.

Further, in the above embodiment, the configuration in which the handle body 10 is formed of a hard resin is exemplified, but the configuration is not limited to this, and for example, a part of the handle body 10 (handle portion 11 or the like) is coated with a soft resin. It may have a different configuration. When this configuration is adopted, decorativeness and grip can be improved.

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

1 ... toothbrush, 10 ... handle body, 12 ... fitting protrusion, 20 ... brush molded body, 21 ... head base, 21a ... support surface, 21c ... back surface, 22 ... fitting hole, 23 ... filament, 30 ... Support base, 31 ... 2nd support, 40 ... Preformed body, 50 ... Base body molded body, F1 ... Filament group (1st filament group), F3 ... Filament group (2nd filament group)

Claims (16)

1. It has a head base portion made 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 head base portion.
   The head base portion has a fitting hole extending in a length direction orthogonal to the thickness direction and opening on one side in the length direction.
   A support base portion that supports the filament group including at least a part of the plurality of filaments and the base portion of the filament group, and is located on the front side of the fitting hole to form a part of the head base portion. And, at least a part of the preformed body molded with the first resin composition, and
   A base body molded body having a portion other than the preformed body among the head base portion and the plurality of filaments and molded with a second resin composition different from the first resin composition. ,
   Equipped with
   The pre-molded body and the base body molded body are brush-molded bodies characterized in that they are integrally molded.
2. A part of the plurality of filaments constitutes the filament group formed of the first resin composition.
   Among the plurality of filaments, the filaments other than the filament group constitute the base body molded body integrally molded with the head base portion by the second resin composition.
   The brush molded body according to claim 1.
3. In a cross section orthogonal to the length direction of the head base portion,
   The cross-sectional area of the support base is S1.
   Let S be the cross-sectional area of the region located between the front surface and the support surface inside the fitting hole.
   The value represented by S1 / S is 0.6 or less in all the regions where the fitting holes are provided.
   The brush molded body according to claim 1 or 2.
4. In the cross section orthogonal to the length direction
   The cross-sectional area of the fitting hole is SV.
   Assuming that the cross-sectional area of the head base portion including the cross-sectional area of the fitting hole is SW,
   The value represented by SV / (SW-S1) is 0.5 or less in all the regions where the fitting holes are provided.
   The brush molded body according to claim 3.
5. Let P be the area of the head base portion viewed from the front side in the thickness direction.
   Assuming that the area of the support base portion seen from the front side in the thickness direction is P1.
   The values represented by P1 / P are 0.1 or more and 0.5 or less.
   The brush molded product according to any one of claims 1 to 4.
6. The maximum distance from the base end of the filament to the back surface of the 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 brush molded product according to any one of claims 1 to 5.
7. Let T be the maximum distance from the base end of the filament to the back surface of the head base portion.
   Assuming that the thickness of the support base portion in the thickness direction is t1,
   The value represented by t1 / T is 0.5 or less.
   The brush molded body according to claim 6.
8. Assuming that the distance between the back surface of the support base and the front surface inside the fitting hole is t2.
   The value represented by t1 / (t1 + t2) is 0.2 or more and 0.8 or less.
   The brush molded body according to claim 7.
9. Let FM be the number of the filaments in the filament group.
   Assuming that the area where the support base portion adheres to the base body molded body is Q1 (mm ² ),
   The value represented by FM / Q1 is 1.0 (lines / mm ² ) or less.
   The brush molded product according to any one of claims 1 to 8.
10. An uneven structure is provided at the adhesive interface between the support base portion and the base body molded body.
    The brush molded product according to any one of claims 1 to 9.
11. The maximum length of the head base portion in the length direction is L1.
    Assuming that the maximum length of the fitting hole in the length direction is L2,
    The values represented by L2 / L1 are 0.30 or more and 0.70 or less.
    The brush molded product according to any one of claims 1 to 10.
12. The preformed body has all of the plurality of filaments.
    The brush molded body according to any one of claims 1 to 11.
13. The preformed body is
    The filament group and the support base portion molded from the first resin composition,
    A second support base portion that supports the base of the second filament group and the second filament group, which is formed of the first resin composition and a third resin composition different from the second resin composition. , Have,
    The brush molded body according to any one of claims 1 to 11.
14. The soft resin is polyurethane.
    The brush molded product according to any one of claims 1 to 13.
15. The brush molded product according to any one of claims 1 to 14.
    A toothbrush formed of a hard resin and provided with a handle body having a removable fitting protrusion in the fitting hole of the brush molded body.
16. The brush molded product according to any one of claims 1 to 14.
    A handle body having a fitting protrusion that fits into the fitting hole of the brush molded body is provided.
    A toothbrush characterized in that the brush molded body and the handle body are integrally molded molded bodies.

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