KR20230125166A - Brush molding and toothbrush - Google Patents

Abstract

An object of the present invention is to provide a brush molded body capable of improving the usability and appearance of a toothbrush with excellent touch. It has a head base part formed of 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 part. The head base portion extends in a longitudinal direction orthogonal to the thickness direction and has a fitting hole opened on one side of the longitudinal direction. A filament group containing at least a part of a plurality of filaments, and a support part which supports a base of the filament group and is located on the front side of the fitting hole and forms a part of the head base part, at least a part of which is a first resin composition A base body molded body having a head base portion and a location other than the preform among the plurality of filaments and molded from a second resin composition different from the first resin composition. The preliminary molded body and the base body molded body are integrally formed molded bodies.

Description

Brush molding and toothbrush

The present invention relates to a brush molding and a toothbrush.

This application claims priority based on Japanese Patent Application No. 2020-214798 for which it applied to Japan on December 24, 2020, and uses the content here.

An integrally molded toothbrush that manufactures a toothbrush only by injection molding has been proposed (for example, Patent Document 1). Since the integrally molded toothbrush integrally molds the filament and the head base (or head), it does not require filament material procurement and a hair transplanter, and has the advantage of being cheaper than a hair-planting toothbrush.

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

Since the head portion is molded from a single resin material, there is a limit to improving the usability and appearance (design) of the toothbrush.

Patent Literature 4 discloses a technique of insert-molding filaments made of a plurality of different types of resin compositions using a mold in which individually molded handle parts are disposed.

Japanese Utility Model Publication No. 61-207233 Specification of Chinese Utility Model No. 204561298 Specification of Chinese Patent Application Publication No. 107041792 Specification of Chinese Utility Model No. 205214577

However, in the toothbrush described in Patent Literature 4, since a wall partitioning multi-colored filaments is formed, the filaments cannot be disposed on the wall portion, and space is formed. Therefore, it is difficult to arrange the filament in a regular continuous profile, and there is a problem that the excellent touch feeling of the head part 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 can have an excellent touch and improve the usability and appearance of the toothbrush.

According to the first aspect of the present invention, there is provided a head base portion formed of a soft resin, and a plurality of filaments protruding from a support surface located on a front side in a thickness direction of the head base portion, wherein the head base portion is orthogonal to the thickness direction. It has a fitting hole extending in the longitudinal direction and opening on one side of the longitudinal direction, and supports a filament group including at least a part of the plurality of filaments, and a base portion of the filament group, and is larger than the fitting hole. A preform located on the front side and having a support portion forming a part of the head base portion, at least partially molded from the first resin composition, and a portion other than the preform body among the head base portion and the plurality of filaments and a base body molded body molded of a second resin composition different from the first resin composition, wherein the preform and the base body molded body are integrally molded.

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

Further, in the brush molded body according to one aspect of the present invention, in a cross section orthogonal to the longitudinal direction of the head base portion, the cross-sectional area of the support portion is S1, and the front side inside the fitting hole is When S is the cross-sectional area of a region located between the surface of and the support surface, a value represented by S1/S is 0.6 or less in all regions where the fitting holes are formed.

Further, in the brush molded body according to one embodiment of the present invention, when 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 longitudinal direction, SV/(SW- The value represented by S1) is characterized in that it is 0.5 or less in all regions where the fitting holes are formed.

Further, in the brush molded body according to one embodiment of the present invention, if the area of the head base portion viewed from the front side in the thickness direction is P, and the area of the support base portion viewed from the front side in the thickness direction 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 embodiment of the present invention, the maximum distance from the base end of the filament to the rear surface of the head base part opposite to the front side in the thickness direction is 2.0 mm or more and 4.5 mm or less.

Further, in the brush molded body according to one embodiment of the present invention, assuming that T is the maximum distance from the base end of the filament to the rear surface of the head base portion and that the thickness of the support portion in the thickness direction is t1, t1/ The value represented by T is characterized in that it is 0.5 or less.

Further, in the brush molded body according to one aspect of the present invention, when the distance between the rear face of the support portion and the front face inside the fitting hole is t2, t1/(t1+ The value represented by t2) is characterized in that it is 0.2 or more and 0.8 or less.

Further, in the brush molded body according to one embodiment of the present invention, if the number of filaments in the filament group is FM, and the area where the support unit adheres to the base body molded body is Q1 (mm 2 ), then FM The value represented by /Q1 is characterized in that it is 1.0 (piece/mm 2 ) or less.

Further, in the brush molded body according to one embodiment of the present invention, a concavo-convex structure is formed at an adhesive interface between the support base and the base body molded body.

Further, in the brush molded body according to one aspect of the present invention, if the maximum length of the head base portion in the longitudinal direction is L1 and the maximum length of the fitting hole in the longitudinal direction is L2, it is represented by L2/L1 The losing value is characterized in that it is 0.30 or more and 0.70 or less.

Further, in the brush molded body according to one embodiment of the present invention, the preform has all of the plurality of filaments.

Further, in the brush molded body according to one embodiment of the present invention, the preform is different from the filament group and the support portion molded from the first resin composition, and from the first resin composition and the second resin composition. It is characterized in that it has a second filament group molded from a third resin composition and a second support part supporting the base of the second filament group.

Further, in the brush molded body according to one embodiment of the present invention, the soft resin is polyurethane.

According to a second aspect of the present invention, a toothbrush characterized by comprising a brush molded body of the first aspect of the present invention and a handle body formed of a hard resin and having a fitting projection attachable to and detachable from the fitting hole of the brush molded 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 a handle body having a fitting protrusion that fits into the fitting hole of the brush molded body, wherein the brush molded body and the handle body are integrally formed. There is provided a toothbrush, characterized in that the molded body.

In the present invention, it is possible to provide a brush molded body and a toothbrush that have an excellent touch and can improve the usability or appearance of the toothbrush.

1 is a front view of a brush molded body 20 and a toothbrush 1 according to an embodiment of the present invention.
Fig. 2 is a side view of the brush molded body 20 and the toothbrush 1.
3 is a front view of the brush molded body 20.
4 is a AA sectional view in FIG. 3 .
5 : is the figure which looked at the brush molded body 20 from the rear end side.
6 is a sectional view in a plane parallel to the support surface 21a including the fitting hole 22 .
7 is a front view of the handle body 10.
8 is an enlarged front view of the fitting protrusion 12 .
9 is an enlarged side view of the fitting protrusion 12 .
10 is a cross-sectional view in the width direction schematically showing an example of a mold MD for molding the preform 40 among the brush molded bodies 20. As shown in FIG.
FIG. 11 is a cross-sectional view in the width direction schematically illustrating an example of a mold MD for molding the base body molded body 50 among the brush molded bodies 20. As shown in FIG.
12 is a longitudinal cross-sectional view schematically showing an example of a mold MD for secondary molding.
Fig. 13 is a cross-sectional view in the width direction of the brush molded body 20 according to the second embodiment.
Fig. 14 is a front view of the brush molded body 20 according to the third embodiment.
Fig. 15 is a cross-sectional view in the width direction of the brush molded body 20 according to the third embodiment.
Fig. 16 is a front view showing a modified example of the brush molded body 20 according to the third embodiment.
Fig. 17 is a longitudinal cross-sectional view showing a modified example of the brush molded body 20 according to the third embodiment.
Fig. 18 is a cross-sectional view in the width direction of the brush molded body 20 according to the fourth embodiment.

Hereinafter, embodiments of the brush molded body and toothbrush of the present invention will be described with reference to FIGS. 1 to 18 . In this embodiment, it demonstrates using the example of the toothbrush in which the brush molded body is attached to the handle body detachably.

In addition, the following embodiment shows one aspect of this invention, and this invention is not limited, It can change arbitrarily within the range of the technical idea of this invention. In the following drawings, the actual structure and the scale, number, etc. of each structure are different in order to make each structure easy to understand.

1 is a front view of a brush molded body 20 and a toothbrush 1 according to this 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 attached (inserted) to the handle body 10 in a detachable manner. The brush molded body 20 is formed of a soft resin. The handle body 10 is formed of hard resin.

In addition, the front surface in this embodiment is the thickness direction (hereinafter, simply referred to as the thickness direction), which is the normal direction of the support surface 21a (details described later) of the brush molded body 20, the filament 23 described later It is 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 the back side. In addition, it is the longitudinal 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 longitudinal direction, the side on which the handle body 10 is mounted with respect to the brush molded body 20 is referred to as the rear end side, and the side opposite to the rear end side is appropriately referred to as the front 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]

3 is a front view of the brush molded body 20. Fig. 4 is an A-A sectional view in Fig. 3; As shown in FIGS. 3 and 4 , the brush molded body 20 includes a head base part 21 having a substantially rectangular shape when viewed from the front, and a plurality of filaments 23 installed in front of the head base part 21. is provided.

Although various elastomers can be used as the soft resin constituting the brush molded body 20, it is preferably polyurethane.

Since polyurethane tends to have a higher tensile strength than other elastomers such as styrene and polyster, by using polyurethane for a soft resin, mechanical strength can be secured even when thin, and the handle body (10 ) and the fitting hole 22, and breakage during use of the toothbrush 1 can be suppressed.

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

In addition, polyurethane has a wider range of selectable hardness compared to elastomers other than the above, and depending on the thickness of the brush molded body 20, the resin hardness in consideration of its usability (for example, bending of the tip of the brush molded body) choice is possible As hardness of polyurethane, it is preferable that they are Shore 90A or more and 70D or less.

If the hardness of polyurethane is softer than Shore 90A, since it becomes easy to deform when it is formed into a thin wall, the fitting becomes weak and the brush molded body 20 becomes easy to fall off during use of the toothbrush 1. When the hardness of polyurethane is harder than Shore 70D, when the back surface of the head base part 21 is inclined, pain may occur when the tip contacts the oral tissue. By setting the hardness of polyurethane to Shore 90A or more and 70D or less, it is possible to suppress the occurrence of pain when the brush molded body 20 falls off or the tip of the head base part 21 touches during use of the toothbrush 1. .

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

The filament 23 has a substantially columnar shape protruding toward the front side from the support surface 21a located on the front side of the head base part 21 in the thickness direction. The support surface 21a of the head base 21 is a plane parallel to the width direction and insertion direction. The support surface 21a is arranged at the proximal end of the filament 23 in the thickness direction. The filament 23 has a substantially triangular prism shape with a substantially triangular cross section at the base end side, and a triangular pyramid shape with a tip side extending from the substantially triangular prism and tapering at the tip end. As the cross-sectional shape of the filament 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 hera shape, and the like can be selected. The filament 23 may have a tapered shape in which the tip is tapered, or a structure extending in a straight shape or a tapered shape in which the tip is tapered from the base end.

The filaments 23 are formed in plural rows along the insertion direction so that adjacent rows in the insertion direction deviate from each other by half a pitch. That is, the filaments 23 are arranged in a zigzag shape.

5 : is the figure which looked at the brush molded body 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 a filament group F2 located on both sides of the filament group F1 in the width direction. ) has 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, and more preferably 13 mm or less.

Moreover, as a maximum diameter of the filament 23, it is preferable that they are 7 mm or more and 15 mm or less, and it is more preferable that they are 9 mm or more and 13 mm or less.

When the maximum length of the filament 23 is less than 7 mm, there is a possibility that cleaning performance in the oral cavity decreases. When the maximum length of the filament 23 exceeds 15 mm, releasability at the time of molding the brush molded body 20 by injection molding is reduced. By setting the maximum length of the filament 23 to 7 mm or more and 15 mm or less, cleaning in the oral cavity and releasability at the time of molding can be ensured.

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 becomes difficult to bend, and there is a possibility that clearance cleaning properties such as interdental and cervical regions are reduced. By setting the cross-sectional area of the base end of the filament 23 to 0.8 mm 2 or less, clearance cleaning properties such as interdental and cervical regions can be ensured.

The ratio of the total cross-sectional area of the base end of the plurality of filaments 23 to the area of the support surface 21a of the head base part 21 is preferably 10% or more and 50% or less. When the ratio of the total cross-sectional area of the base end of the filament 23 is less than 10%, there is a possibility that the cleaning performance in the oral cavity is lowered. When the ratio of the total cross-sectional area of the base end of the filament 23 exceeds 50%, the releasability at the time of molding the brush molded body 20 by injection molding is reduced. 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, the cleaning property in the oral cavity and the releasability at the time of molding can be secured.

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 1st resin composition and the 2nd resin composition, the above-mentioned soft resin can be selected suitably considering the usability of the toothbrush 1 and external appearance (design property). For example, when the feeling of use of the toothbrush 1 is considered and the massaging property and the scrubbing feeling are compatible, the above-mentioned soft resin having different hardness can be used. In addition, when appearance is considered, it is also possible to use the above-mentioned soft resin as a base material and add a coloring agent such as master batch to make the filament group F1 and the filament group F2 different colors.

The head base part 21 has a support part 30 and a fitting hole 22.

The support unit 30 supports the base end of the filament group F1 from the lower side. As shown in Fig. 3, the support unit 30 has a size including the filament group F1 and has a rectangular parallelepiped shape when viewed from the front. As shown in FIG. 4, the upper surface of the support base part 30 is the same height as the support surface 21a. That is, the upper surface of the support part 30 constitutes a part of the support surface 21a. Below, also the upper surface of the support base part 30 is called the support surface 21a suitably.

The support portion 30 is located on the front side of the fitting hole 22 . It forms part of the head base 21. The support base part 30 is formed of the 1st resin composition. The support member 30 and the filament group F1 constitute the preform 40 integrally molded with the first resin composition.

The fitting hole 22 extends in the insertion direction and opens to the end face 21b on the rear end side (one side). 6 is a sectional view in a plane 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 opening to the end face 21b and a second portion 34 positioned inside the first portion 33 . As shown in FIG. 4, the 1st part 33 and the 2nd part 34 are arrange|positioned separately from the back surface 21c of the head base part 21, and the back surface of the support base part 30, respectively.

The head base portion 21 has a protrusion 35 positioned between the first portion 33 and the second portion 34 at approximately the center of the fitting hole 22 in the insertion direction. The protrusions 35 are formed on both sides of the fitting hole 22 in the width direction. The protrusions 35 are formed at positions where they fit with the concave portions 15 (described later) when the fitting protrusions 12 (see FIG. 7; described later) of the handle body 10 are inserted into the fitting holes 22. . The protrusion 35 has a circular 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 . As an example, the protruding amount of the protrusion 35 toward the inner side in the width direction of the second portion 34 is 1 mm. The protruding amount of the protrusion 35 relative to the second portion 34 is the amount of undercut when the mold (slide core) 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 the base body molded body 50 integrally molded with the second resin composition. The brush molded body 20 is a molded body in which the preform 40 and the base body molded body 50 are integrally molded. In this case, the preform 40, which has been primarily molded with the first resin composition, is placed in a cavity in the mold, filled with the second resin composition in the cavity, and secondary molded (insert molding) to form the molded body.

Returning to FIG. 5 , in a cross section orthogonal to the longitudinal 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 rear face of the support base portion 30 and the face on the front side inside the fitting hole 22 is selected from 0 mm to 2.5 mm. When the rear surface of the support unit 30 and the front surface inside the fitting hole 22 are of the same height, the rear surface of the support unit 30 and the front side inside the fitting hole 22 are of the same height. The thickness (t2) of the surface of is 0 mm. That is, a structure in which the rear surface of the support unit 30 is exposed to and faces the fitting hole 22 can be selected. In this case, the support member 30 is fixed by bonding the side surface in the width direction to the base body molded body 50 .

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

In the cross section orthogonal to the longitudinal direction of the head base portion 21, the cross-sectional area of the support base portion 30 is S1, and between the front side surface in the inside of the fitting hole 22 and the support surface 21a. If S is the cross-sectional area of a region having a thickness (t1+t2) to be located, the value represented by S1/S is preferably 0.1 or more in all regions where the fitting hole 22 is formed.

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 brush molded body 20 having the fitting hole 22, the cross-sectional area of the region defined by the thickness (t1 + t2) between the surface on the front side and the support surface 21a in the inside of the fitting hole 22 (S ) and the cross-sectional area S1 of the support unit 30 have a great influence on the moldability of the filament 23. In multicolor molding, after molding the primary side, switching the movable side (or stationary side) of the mold to mold the secondary side and beyond, so the molding proceeds with the primary side molded body left in the cavity. The flowable area after the secondary side becomes smaller. For this reason, multi-color molding is different from single-color molding, and the flowability of the resin on the secondary side and thereafter tends to be insufficient, making filament molding difficult. In this case, since sufficient filling speed and holding pressure cannot be secured, molding defects such as short circuits and sinks tend to occur. Specifically, when the value represented by S1/S exceeds 0.6, molding defects of the filament 23 tend to occur. In this embodiment, molding defects of the filament 23 can be suppressed by setting the value represented by S1/S to 0.6 or less. In addition, from the viewpoint of securing the moldability of the primary side support unit 30 and the filament group F1, it is preferable to set the value represented by S1/S to 0.1 or more.

In the cross section perpendicular to the longitudinal 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 Speaking of SW, it is preferable that the value represented by SV/(SW-S1) is 0.1 or more in all areas where the fitting hole 22 is formed. 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 molding other than the primary side, that is, in the molding of the base body molded body 50, the existence of the slide core for forming the fitting hole 22, in addition to the existence of the preform 40 on the primary side that has been previously molded, has a great influence on the resin flow. give When the occupancy of the slide core is small, the resin flows easily in the cavity, and the moldability of the filament 23 is improved. Conversely, when the value represented by SV/(SW-S1) representing the occupancy rate of the slide core exceeds 0.5, the resin flow is restricted during molding of the base body molded body 50, and the filaments 23 on the secondary side and beyond There is a possibility that molding defects of (filament group F2) may occur. In this embodiment, molding defects of the filament 23 can be suppressed by setting the value represented by SV/(SW-S1) to 0.5 or less. Further, from the viewpoint of securing the strength of the slide core, it is preferable to set the value represented by the above SV/(SW-S1) to 0.1 or more.

If the area (projected area) of the head base part 21 when viewed from the front side in the thickness direction as seen from the front is P and the area of the support base part 30 as viewed from the front is P1, then P1/P It is preferable that it is 0.1 or more, and, as for the value represented by, it is more preferable that it is 0.2 or more. It is preferable that it is 0.5 or less, and, as for the value represented by P1/P, it is more preferable that it is 0.4 or less. 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 a means for improving the moldability of the filaments 23 (filament group F2) other than the primary side, the resin flow flowing in a direction parallel to the support surface 21a is also important. In particular, when the gate is located at the end of the brush molded body 20 in the longitudinal direction, such as a side gate, it significantly contributes. Therefore, when the value represented by P1/P exceeds 0.5, the resin flow is inhibited by the occupation of the cavity area by the preform 40 on the primary side, and the base body 50 on the secondary side and beyond There is a possibility that molding defects of the filament 23 may occur during molding. In addition, when the value represented by P1/P is less than 0.1, the occupancy rate of the filament group F1 is low, and there is a possibility that functionality (eg, cleanability) cannot be secured. In the present embodiment, molding defects of the filaments 23 can be suppressed while ensuring the functionality of the filament group F1 by setting the value represented by P1/P to 0.1 or more and 0.5 or less.

The maximum distance (maximum thickness) between the support surface 21a and the rear surface 21c of the head base unit 21, that is, the maximum distance T from the base end of the filament 23 to the rear surface 21c is 2.0 mm or more and 4.5 mm. It is preferable that it is below. When the maximum distance T is less than 2.0 mm, the gap between the support surface 21a and the surface on the support surface 21a side of the fitting hole 22 or the back surface 21c and the back surface of the fitting hole 22 Since the gap between the surfaces on the side (21c) becomes small and the fluidity of the molten resin decreases during molding of the base body molded body 50, there is a possibility that the resin becomes unfilled. 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 21a side and the support base 30 must be made small, and the base body molded body 50 The fluidity of the molten resin is lowered during molding. When the maximum distance T exceeds 4.5 mm, the operability when the brush molded body 20 is inserted into the oral cavity may deteriorate. 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.

If T is the maximum distance from the base end of the filament 23 to the rear surface 21c of the head base 21, and the thickness of the support base 30 in the thickness direction is t1, the value represented by t1/T is It is preferably 0.5 or less, and more preferably 0.4 or less. When the value represented by t1/T exceeds 0.5, the flow of the resin during molding of the base body molded body 50 other than the primary side is secured, so that the entire brush molded body 20 becomes thick, resulting in improved intraoral maneuverability. leads to degradation In the present embodiment, by setting the value expressed by t1/T to 0.5 or less, it is advantageous in terms of both formability and usability during molding of the base body molded body 50 on the secondary side and beyond. In addition, from the viewpoint of moldability on the primary side and securing the adhesiveness of the side surface of the primary side support base portion 30 to the head base portion 21, it is preferable to set the value represented by t1/T to 0.1 or more.

Further, the thickness t2 between the thickness t1 and the surface on the front side inside the fitting hole 22 is preferably a value represented by t1/(t1 + t2) of 0.2 or more, and is 0.3 or more it is more preferable It is preferable that it is 0.8 or less, and, as for the value represented by t1/(t1+t2), it is more preferable that it is 0.7 or less. Moreover, it is preferable that they are 0.2 or more and 0.8 or less, and, as for the value represented by t1/(t1+t2), it is more preferable that they are 0.3 or more and 0.7 or less. When the value expressed by t1/(t1+t2) exceeds 0.8, sufficient space for the resin to flow cannot be secured between the back surface of the primary side (the back surface of the support base part 30) and the slide core, so the support base part Depending on the flow of the resin on the side surface side of (30), there is a possibility that the moldability of other than the primary side (base body molded body 50) is reduced. In addition, there is a possibility that the resin adhesion between the primary side support base portion 30 and the secondary side base body molded body 50 is not stable. When the value represented by t1/(t1+t2) is less than 0.2, there is a possibility that the formability of the support base portion 30 on the primary side cannot be secured. In the present embodiment, by setting the value represented by t1 / (t1 + t2) to 0.2 or more and 0.8 or less, while securing the moldability of the primary side support unit 30 and the secondary side base body molded body 50, The resin adhesiveness between the support base 30 and the base body molded body 50 can be stabilized.

In addition, if the thickness t2 is 0.3 mm or more, even if it is a specification of a wide head, problems in moldability are unlikely to occur. As thickness t2, it is preferable that it is 0.5 mm or more, and it is more preferable that it is 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 represented by FM/Q1 is 1.0 ( It is preferably 0.8 (piece/mm 2 ) or less, and more preferably 0.8 (piece/mm 2 ) or less. The filament 23 is pulled out while being pulled by the release resistance of the surface of the cavity during release after molding. When the value represented by FM/Q1 exceeds 1.0 (piece/mm 2 ), in multicolor molding, when releasing the molded bodies of the preform 40 and base body molded body 50 after the secondary molding, the filament group (F1 ), there is a possibility that the preform 40 peels off from the base body molded object 50 due to the mold release resistance of ). In this embodiment, by setting the value represented by FM/Q1 to 1.0 (piece/mm 2 ) or less, peeling of the preform 40 from the base body molded body 50 after secondary shaping can be suppressed. In addition, when the number of filament groups F1 cannot be sufficiently secured with respect to the area occupied by the support unit 30, considering the possibility that the functionality of the primary side filament F1 is reduced, the value represented by FM / Q1 It is preferable to make 0.2 (pcs/mm 2 ) or more.

From the viewpoint of suppressing peeling of the preform 40 from the base body molded body 50 after the secondary molding, one or more concave-convex structures are formed at the bonding interface between the support base portion 30 and the base body molded body 50. it is desirable to be Since the bonding interface between the support unit 30 and the base body molded body 50 is not smooth and a concave-convex structure is formed, the bonding area is increased while securing moldability, and the adhesiveness of the preform 40 on the primary side is improved. can As the arrangement of the concavo-convex structure, either the back surface or the side surface of the support base 30 may be used, but arrangement on the back surface is effective for increasing the bonding area because the height and width of the concavo-convex structure are easily increased compared to the side surface. In the case of arranging the concave-convex structure on the side surface of the support member 30, the thickness of the support member 30 or the undercut when forming the preform 40 may be considered. The height (maximum to minimum) of the concavo-convex structure is, for example, about 0.1 to 0.5 mm, and the pitch of the concavo-convex structure is about 0.5 to 3.0 mm.

As shown in Fig. 4, if the maximum length of the head base part 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 0.40 or more, and even 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. 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, the area where the fitting protrusion 12 of the handle body 10 formed of hard resin does not exist becomes large, so the front of the brush molded body 20 is easily bent, and the toothbrush ( There is a possibility that usability as 1) may deteriorate. When L2/L1 exceeds 0.70, the volume occupied by the mold (slide core) forming the fitting hole 22 increases during molding, and the flow of the resin is restricted, so the moldability of the filament 23 deteriorates. throw away By setting the value represented by L2/L1 to 0.30 or more and 0.70 or less, a decrease in usability of the toothbrush 1 can be suppressed while a decrease in moldability of the filament 23 is suppressed.

[Handle body (10)]

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 formed at the tip of the handle portion 11 and protruding toward the distal end side in the longitudinal direction of the handle portion 11. there is. 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 molded body 20 described above, and the brush molded body 20 is covered and attached to the fitting protrusion 12. .

The shape of the handle portion 11 of the present embodiment when viewed from the front changes curvilinearly, such that the width gradually narrows from the front end side toward the rear end side, then extends to a constant width, and then gradually widens and then narrows. do. As for the shape of the handle part 11 when viewed from the front, the rear end has a substantially semicircular shape.

As shown in Fig. 2, the shape of the handle portion 11 when viewed from the side extends at a constant width from the front end toward the rear end, and then gradually widens to the maximum thickness used as the finger contact portion. The shape of the handle portion 11 when viewed from the side changes curvilinearly so that the width gradually narrows from the finger contact portion having the maximum thickness toward the rear end side. As for the shape at the time of seeing from the side of handle part 11, the rear end part becomes a substantially semicircular shape.

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 appropriately. For example, the length of the handle part 11 can be 100-200 mm.

The fitting protrusion 12 is a portion covered by 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 .

8 is an enlarged front view of the fitting protrusion 12 . 9 is an enlarged side view of the fitting protrusion 12 .

As shown in FIG. 8 , the fitting protruding portion 12 has a base portion 13 provided on the distal end side of the handle portion 11 and a distal end portion 14 formed 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 steps with respect to the handle portion 11 on both sides of the front side and the rear side, and are formed with the same thickness thinner than the handle portion 11 .

The base 13 has a substantially rectangular shape in 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 distal end side of the handle portion 11 (L13 < L11). The distal end portion 14 has a substantially elliptical shape when viewed in a plane with the transverse direction being the major axis direction. The distal end 14 has a shape in which side edges are cut in a straight line parallel to the insertion direction of the fitting protrusion 12 on both sides in the substantially elliptical width direction. The front end 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 centered in the insertion direction, and has a concave portion 15 between the base portion 13 and the distal end portion 14. The recesses 15 are formed on both sides in the width direction. The concave portion 15 is an arc shape having an arc center on the outside in the width direction and concave inward. The shortest distance (L15) between the concave portions (15) is shorter than the width (L13) of the base portion (13) and the width (L14) of the tip portion (14). As an example, the recessed amount of the concave portion 15 relative to the edge defining the width L14 in the tip portion 14 is 1 mm.

The handle body 10 is formed of hard resin.

As hard resin, as an example, resin whose flexural modulus (JIS K7171) is 1500 Mpa or more and 3000 Mpa or less can be illustrated. Specifically, 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 view of cost.

The maximum width L21 of the rear end side (end surface 21b) of the head base part 21 is substantially the same as the maximum width of the front end side of the handle part 11.

The shape of the fitting hole 22 when viewed from the front is substantially the same as the shape of the fitting projection 12 when viewed from the front. The width L33 of the first portion 33 is a length in which the base portion 13 in the fitting projection 12 can be inserted, and is substantially equal to the maximum width L13 of the base portion 13 . The width L34 of the second part 34 is a length in which the distal end 14 of the fitting projection 12 can be inserted, and is substantially equal to the maximum width L14 of the distal end 14. The shortest distance L35 between the protrusions 35 is a length at which the distal end 14 and the concave portion 15 of the fitting protrusion 12 can be inserted, and is roughly equivalent to the shortest distance L15 between the concave portions 15. same.

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

The mold MD includes a first mold MD1 that relatively moves in 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 clamped with the parting surface (PL), which is the same height as the support surface (21a), as a bonding surface. As an example, the first mold (MD1) is a fixed mold, and 2 The mold (MD2) is a movable type.

The first mold MD1 is attached to, for example, a fixed side of an injection molding machine, and is filled with molten resin from the injection molding machine. The second mold MD2 is mounted on the movable side of the injection molding machine, and the mold MD is opened and closed by moving in the opening and closing direction relative to the first mold MD1.

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

The second mold MD2 has a cavity 30M in which the support member 30 is molded when the second mold MD2 is clamped and bonded 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 blocked by the parting surface PL of the second mold MD2. A gate portion (not shown) is formed in the cavity 30M. As the gate portion, for example, a side gate method is used, but a pinpoint gate method and 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 molded is molded into the cavity 30M ) and filled in the cavity F1M. On the other hand, the cavity 30M does not open to the cavity F2M, and since the opening of the cavity F2M is blocked by the parting surface PL of the second mold MD2, it is not filled with the first resin composition. Thereafter, the preform 40 formed of the first resin composition having the filament group F1 and the support member 30 is cooled while the first mold MD1 and the second mold MD2 are clamped. is molded

Fig. 11 is a cross-sectional view in the width direction schematically showing an example of a mold MD for secondary shaping for shaping the base body molded body 50 among the brush molded bodies 20. 12 is a longitudinal cross-sectional view schematically showing an example of a mold for secondary molding (MD).

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 holding the molded preform 40 without releasing it. In addition, a part of the first mold MD1 for primary molding including the cavity F1M and the cavity F2M may be removed and attached to the first mold MD1 for secondary molding.

When the second mold MD12 is clamped and bonded to the first mold MD1, the head base part 21 is molded, and is opened at the front end side of the cavity 21M, and the cavity 21M It has a gate portion G into which molten resin is introduced, and a contact surface 21eM formed at the position of the end face 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 molded is opened to the cavity 21M. As the gate portion G, a side gate method is used, for example, 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 a position where the back surface of the head base part 21 is molded in the second mold MD2.

A slide core SL is formed in the second mold 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 orthogonal to the insertion direction. As shown in FIG. 11, before mold clamping, the molding surface 21bM is separated from the contact surface 21eM. In the slide core SL, when the first mold MD1 and the second mold MD12 are clamped, as shown in Fig. 11, a part of the molding surface 21bM is in contact with the contact surface 21eM, and the core part 22M is positioned at a position where it is inserted into the cavity 21M. Of the molding surfaces 21bM, regions that do not contact the contact surfaces 21eM and face the cavity 21M are regions in which the end surfaces 21b are molded. In addition, the slide core SL is designed 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 moving direction of the slide core SL is preferably a horizontal direction in order to avoid unexpected movement due to its own weight.

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 molded is molded into the cavity 21M ) and filled in the cavity (F2M). The second resin composition filled in the cavity 21M covers the side and rear surfaces of the support member 30 and adheres to the support member 30 . Thereafter, the first mold (MD1) and the second mold (MD12) are cooled in a clamped state, and released from the mold (MD) to form a first resin composition having a filament group (F1) and a support member (30). A preformed body 40 formed of, a base main body molded body 50 having a location other than the preform 40 among the head base portion 21 and the plurality of filaments 23, and molded with a second resin composition. Then, a molded body in which the preform 40 and the base body molded body 50 are integrally molded is obtained.

That is, the second resin including 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 unit 30 formed of the first resin composition. A brush molded body 20 in which the head base portion 21 formed of the composition is integrally molded as a molded body is obtained.

With respect to the molded brush molded body 20, the fitting protrusion 12 of the handle body 10 is inserted into the fitting hole 22 and fitted, thereby forming a toothbrush 1 in which the brush molded body 20 and the handle body 10 are integrated. ) is obtained. Further, by pulling the fitting protrusion 12 of the handle body 10 out of the fitting hole 22, the brush molded body 20 can be detached from the handle body 10 and replaced.

As described above, since the brush 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, By appropriately selecting the first resin composition and the second resin composition according to the above, it is possible to obtain a molded brush body and a toothbrush having excellent touch and improving the usability and appearance of the toothbrush 1.

[Second Embodiment of Brush Molded Body 20]

Next, a second embodiment of the brush molded body 20 will be described with reference to FIG. 13 . In these figures, the same reference numerals are attached to the same elements as those of the first embodiment shown in Figs. 1 to 12, and the description thereof is omitted.

In the first embodiment, a configuration in which the preform 40 is molded from one type of resin composition has been exemplified, but in the second embodiment, a configuration in which a plurality of types of resin compositions are molded will be described.

Fig. 13 is a cross-sectional view in the width direction of the brush molded body 20 according to the second embodiment.

As shown in Fig. 13, the preform 40 of this embodiment has a filament group (second filament group) F3 disposed at the center in the width direction and a filament group F3 disposed on both sides in the width direction, respectively. It has a 2nd support base part 31 which supports the filament group F1 and the base part of the filament group F3, and the support part 30 which supports the base part of the filament group F1. The filament group F3 is molded from a third resin composition different from the first and second resin compositions. The filament groups F1 and F3 are formed of a plurality of filaments 23 arranged in the longitudinal direction of the head base part 21 . The 3rd resin composition is suitably selected from the above-mentioned soft resin.

The 2nd support base part 31 is molded with the 3rd resin composition. The side surface and the back surface of the second support member 31 in the width direction are bonded to the support member 30 . The surface of the front side of the 2nd support base part 31 is the same height as the support surface 21a. The preform 40 of the present embodiment includes a filament group F3 and the second support part 31 molded from the third resin composition, and a filament group F1 and the support part 30 molded from the first resin composition. is an integrally molded molded body.

In the preform 40, as an example, the filament group F3 and the second support member 31 are molded by the third resin composition in the first molding, and the filament group F1 by the first resin composition in the second molding. ) and the two-color molding in which the support member 30 is molded. Alternatively, the filament group F1 and the support member 30 are molded with the first resin composition using a mold provided with the filament group F3 molded with the third resin composition and the second support member 31. obtained by insert molding.

And, in the brush molded body 20 of this embodiment, the filament group F3 and the second support member 31 are molded by the third resin composition in the first molding, and the filaments are formed by the first resin composition in the second molding. It is obtained by three-color molding in which the group F1 and the support portion 30 are molded, and in the third molding, the filament group F2 and the head base part 21 are molded with the second resin composition. Alternatively, it is obtained by insert molding in which the filament group F2 and the head base part 21 are molded with the second resin composition using a mold having a preformed body 40 formed in advance.

In the brush molded body 20 of the above configuration, in addition to obtaining the same actions and effects as the brush molded body 20 of the first embodiment, various types of resin compositions are used according to the specifications of the toothbrush 1. A toothbrush 1 with added value can be provided.

[Third Embodiment of 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 drawings, the same reference numerals are given to the same elements as those of the second embodiment shown in Fig. 13, and the description thereof is omitted.

In this embodiment, the filament group is simply shown as a region in which the filament group is disposed.

Fig. 14 is a front view of the brush molded body 20 according to the third embodiment. Fig. 15 is a cross-sectional view in the width direction of the brush molded body 20 according to the third embodiment.

As shown in Fig. 14, in this embodiment, the filament group F1 is provided on both sides in the width direction and both sides in the longitudinal direction of the filament group F3, respectively. The filament group F1 is arranged in a zero shape surrounding the filament group F3.

As shown in FIG. 15 , the side surface of the second support member 31 is adhered to the support member 30 . The second support member 31 penetrates the support member 30 in the thickness direction. The rear surface of the second support unit 31 is flush with the rear surface of the support unit 30 .

Other configurations are the same as those of the second embodiment.

In this embodiment, in addition to obtaining the same action and effect as in the second embodiment, by arranging the filament 23 two-dimensionally other than the linear shape, according to the specifications of the toothbrush 1, more types of A toothbrush 1 having various added values can be provided by using the resin composition.

In addition, as a configuration in which the filaments 23 are arranged two-dimensionally, as shown in the front view of FIG. 16 and the cross-sectional view in the longitudinal direction of FIG. 17, for example, the filament group F1 and the support unit 30, A structure in which the filament group F3 and the second support member 31 are aligned in the longitudinal direction may be arranged.

[Fourth Embodiment of Brush Molded Body 20]

Subsequently, a fourth embodiment of the brush 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 those 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 brush molded body 20 according to the fourth embodiment.

As shown in Fig. 18, the filament group F1 in the preform 40 of this embodiment has all of the plurality of filaments 23.

Other configurations are the same as those of the first embodiment.

In the brush molded body 20 having the above structure, as in the first embodiment, since the filament group F1 and the head base part 21 are molded with different resin compositions, it has an excellent touch feeling and the usability and appearance of the toothbrush 1 are improved. It is possible to obtain a brush molded body and a toothbrush capable of improving.

In the brush molded body 20 having the above configuration, since the preform 40 has all of the filaments 23, the release resistance of the preform 40 when releasing the brush mold 20 from the mold increases. 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 relationship between the support base portion 30 and the base body molded body 50 It is preferable to employ at least one of the concavo-convex structures formed on the bonding interface.

[Example]

Hereinafter, the present invention will be described in detail by showing examples, but the present invention is not limited to the following examples, and can be implemented with appropriate changes without departing from the gist of the present invention.

(Examples 1 to 8, Comparative Example 1)

Toothbrushes different in at least one of the items shown in Table 1 were taken as samples of Examples 1 to 8 and Comparative Example 1. The resin constituting each sample was called polyurethane.

[Assessment Methods]

For each sample of Examples 1 to 8 and Comparative Example 1, filament moldability, ease of wiping of the entire oral cavity, and adhesiveness of the preform on the primary molding side were evaluated.

(1) Evaluation method of moldability of filament

Five brush molded bodies molded under the same conditions were evaluated according to the following criteria.

5 points|pieces: The defect of appearance is not confirmed at all.

4 points: The tip of the filament is deformed during release (because the pressure is not sufficiently applied, it is bent by an external force during release).

3 points: The thickness of the tip of the filament is thinner than the design value.

2 points: The filament length 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 (a filament of less than half of the total length exists).

And the average value of 5 evaluation points was calculated|required, and evaluation by the following 4 stages was performed.

◎ (double circle mark): 4.5 or more and 5.0 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) Evaluating ease of wiping of the entire oral cavity

Sensory evaluation was performed by 10 expert panelists, and the ease of cleaning of the entire oral cavity during cleaning (especially the ease of cleaning of the molars was emphasized) was evaluated according to the following criteria.

5 points: Very easy to clean.

4 points: It is slightly easy to wipe.

3 points: Neither.

2 points: It is slightly difficult to wipe.

1 point: Very difficult to wipe off.

And, the average value of the evaluation points by 10 professional panelists was calculated|required, and evaluation was performed by the following 4 steps.

◎: 4.5 or more and 5.0 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 adhesiveness of the preform on the primary molding side

Five brush molded bodies molded under the same conditions were evaluated according to the following criteria.

5 points|pieces: The defect of appearance is not recognized at all.

4 points: The base part on the primary side is deformed due to the release resistance at the time of release (a state in which the brush surface is free of pus).

Score 3: Peeling was not confirmed from the external appearance, but peeling was confirmed at the resin boundary when an external force was applied.

2 points: During mold release, part of the base part on the primary side is peeled off and part is connected.

1 point: The entire primary side peeled off and separated from the brush molded body (state where the primary side remained as a mold).

And the average value of 5 evaluation points was calculated|required, and evaluation by the following 4 steps was performed.

◎: 4.5 or more and 5.0 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]

As shown in [Table 1], the cross-sectional area S1 of the support base portion 30 and the cross-sectional area S of the region located between the surface on the front side and the support surface 21a inside the fitting hole 22 ) Samples of Examples 1 to 8 in which the value represented by S1/S, which is the ratio of 0.6 or less, is 0.6 or less. Example 1 has good filament moldability, ease of wiping of the entire oral cavity, and adhesiveness of the preform on the primary molding side. Results were obtained. On the other hand, in the sample of Comparative Example 1 in which the value represented by S1/S exceeded 0.6, good evaluation of filament moldability was obtained.

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

Under the conditions shown in Example 2, the value represented by S1/S increased with the expansion of the primary side support member. As a result, the flow of the resin after the secondary side was reduced, and the moldability of the filament was inferior to that of the sample in Example 1. In addition, although the number FM of the first filament group increased with the expansion of the primary side support member, since the adhesion area Q1 of the support member also increased, the adhesion of the primary side preform was equivalent to that of the sample in Example 1. I did.

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

The samples of Example 4 and Example 5 both had thick heads, resulting in a result inferior to the sample of Example 1 in the ease of wiping the entire oral cavity. Further, in the sample of Example 5, since the support part was also thicker at the same time, the value expressed by t1/T was increased, the resin flow during molding of the base body molded body was reduced compared to the sample of Example 4, and the filament molding The results were inferior to those of the sample in Example 1.

Under the conditions shown in Example 6 and Example 8, the value represented by t1/(t1 + t2) becomes large, and sufficient space for resin to flow is not secured between the back surface of the primary side supporter and the slide core, and the resin flow decreases. As a result, the moldability of the filament was inferior to that of the sample of Example 1. However, in the sample of Example 8, compared to the sample in Example 6, since the surface on the rear side of the support portion was not exposed to the surface on the front side in the inside of the fitting hole, the adhesiveness of the primary side preform was lowered. It didn't work.

Under the conditions shown in Example 7, the number FM of the first filament group increased compared to Example 1, but the bonding area Q1 of the support portion did not change, so FM/Q1 increased, and the primary side As a result, the adhesion of the preform was inferior to that of the sample in Example 1.

As mentioned above, although preferred embodiment by this invention was described referring an accompanying drawing, it goes without saying that this invention is not limited to these examples. The various shapes, combinations, etc. of each constituent member shown in the above examples are examples, and various changes are possible based on design requirements and the like within a range not departing from the gist of the present invention.

For example, in the above embodiment, the toothbrush 1 is constituted by the individually molded brush molded body 20 and the handle body 10, and the fitting protrusion 12 of the handle body 10 is connected to the brush molded body 20. Although a configuration in which the brush molded body 20 is attached to the handle body 10 by fitting into the fitting hole 22 is illustrated, it is not limited to this configuration. For example, a structure in which the fitting protrusion 12 of the handle body 10 is provided instead of the slide core SL in the mold in which the preform is installed, and insert molding is performed with the second resin composition during secondary molding may be employed. . By this insert molding, it is possible to obtain a toothbrush 1 as a molded body in which the fitting protrusion 12 is molded integrally with the brush molded body 20 and the handle body 10 fitted into the fitting hole 22 .

In the above embodiment, a configuration in which the handle body 10 is made of a hard resin has been exemplified, but it is not limited to this configuration, and a part of the handle body 10 (such as the handle portion 11) is made of a soft resin, for example. A covered structure may be sufficient. When this structure is adopted, decorativeness and gripping properties can be improved.

The present invention can be applied to brush moldings and toothbrushes.

One… toothbrush 10... handle body
12... fitting protrusion 20 . . . brush molding
21... Head base 21a... support surface
21c... Back 22... fitting hole
23... filament 30... support loan
31... 2nd support member 40... preform
50... Expected main body molded body F1... Filament group (first filament group)
F3... Filament group (2nd filament group)

Claims (16)

A head base portion formed of a soft resin and a plurality of filaments protruding from a support surface located on a front side in a thickness direction of the head base portion,
The head base part has a fitting hole extending in a longitudinal direction orthogonal to the thickness direction and opening on one side of the longitudinal direction;
a filament group including at least a part of the plurality of filaments, and a support part which supports a base of the filament group and is located on the front side of the fitting hole and forms a part of the head base part; A preform molded from the first resin composition;
A base body molded body having a location other than the preform among the head base portion and the plurality of filaments and molded with a second resin composition different from the first resin composition,
The brush molded body, characterized in that the preform and the base body molded body are integrally molded bodies. According to claim 1,
Some of the plurality of filaments constitute the filament group molded from 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 with the second resin composition. According to claim 1 or 2,
In the cross section orthogonal to the longitudinal direction of the head base portion,
Let the cross-sectional area of the support part be S1,
If S is the cross-sectional area of a region located between the front side surface and the support surface in the inside of the fitting hole,
A value represented by S1/S is 0.6 or less in all regions where the fitting holes are formed. According to claim 3,
In the cross section orthogonal to the longitudinal direction,
Let the cross-sectional area of the fitting hole be SV,
When the cross-sectional area of the head base portion including the cross-sectional area of the fitting hole is SW,
A value represented by SV/(SW-S1) is 0.5 or less in all regions where the fitting holes are formed. According to any one of claims 1 to 4,
The area of the head base portion viewed from the front side in the thickness direction is P,
If the area of the support portion viewed from the front side in the thickness direction is P1,
A brush molded body in which the value represented by P1/P is 0.1 or more and 0.5 or less. According to any one of claims 1 to 5,
The brush molded body of claim 1 , wherein the maximum distance from the base end of the filament to the rear surface of the head base part opposite to the front side in the thickness direction is 2.0 mm or more and 4.5 mm or less. According to claim 6,
Let T be the maximum distance from the base end of the filament to the rear surface of the head base part,
If the thickness in the thickness direction of the support portion is t1,
A brush molded body in which the value expressed by t1/T is 0.5 or less. According to claim 7,
If the distance between the rear face of the support portion and the front face inside the fitting hole is t2,
A brush molded body in which the value represented by t1/(t1+t2) is 0.2 or more and 0.8 or less. According to any one of claims 1 to 8,
Let the number of filaments in the filament group be FM,
If the area where the support portion adheres to the base body molded body is Q1 (mm 2 ),
A brush molded body in which the value expressed by FM/Q1 is 1.0 (piece/mm 2 ) or less. According to any one of claims 1 to 9,
A brush molded body in which a concavo-convex structure is formed at an adhesive interface between the support base and the base body molded body. According to any one of claims 1 to 10,
Let the maximum length of the head base part in the longitudinal direction be L1,
If the maximum length of the fitting hole in the longitudinal direction is L2,
A brush molded body in which the value represented by L2/L1 is 0.30 or more and 0.70 or less. According to any one of claims 1 to 11,
The preform is a brush molded body having all of the plurality of filaments. According to any one of claims 1 to 11,
The preform,
The filament group and the support portion molded from the first resin composition;
A brush molded body having a second filament group molded of a third resin composition different from the first resin composition and the second resin composition, and a second support member supporting a base of the second filament group. According to any one of claims 1 to 13,
The soft resin is a brush molded body of polyurethane. The brush molded body according to any one of claims 1 to 14;
A toothbrush characterized by comprising a handle body made of a hard resin and having a fitting protrusion attachable to and detachable from the fitting hole of the brush molded body. The brush molded body 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,
The toothbrush molded body and the handle body are integrally molded molded bodies.