CN116648169A - Brush forming body and toothbrush - Google Patents

Abstract

The application aims to provide a brush forming body which has a soft contact feeling and can improve the use feeling and the appearance of a toothbrush. The brush molded body has a head base portion formed of a soft resin and a plurality of filaments protruding from a support surface located on the front side in the thickness direction of the head base portion. The head base part is provided with a jogged hole which extends in the length direction orthogonal to the thickness direction and is opened to one side of the length direction; the preform is formed at least in part from a 1 st resin composition, and has a filament group including at least a part of a plurality of filaments and a support base portion for supporting the base portion of the filament group and located on the front side of the fitting hole, and forms a part of a head base portion, and a base body formed from a 2 nd resin composition different from the 1 st resin composition and having a head base portion and a portion of the plurality of filaments other than the preform. The preform and the base body are integrally molded.

Description

Brush forming body and toothbrush

Technical Field

The present application relates to a brush molded body and a toothbrush.

The present application claims priority based on japanese patent application No. 2020-214798 filed on 12/24/2020, the contents of which are incorporated herein by reference.

Background

An integrally molded toothbrush has been proposed in which a toothbrush is manufactured only by an injection molding machine (for example, patent document 1). Since the integrally molded toothbrush integrally molds the filaments and the head base portion (or head portion), there is no need for a filament material supply and a bristle setting machine, and there is an advantage in that it can be manufactured more inexpensively than a bristle setting toothbrush.

As an integrally molded toothbrush for brushing, there has been proposed a toothbrush which is integrally molded by molding a head portion (brush molded body) having filaments and an insertion hole and a handle portion having an insertion portion at one end, respectively, and fitting them (for example, patent documents 2 and 3). In the toothbrushes described in patent documents 2 and 3, since the head can be replaced by a user, it is expected that only the head is discarded and the handle can be reused, thereby saving resources.

Since the head is formed of a single resin material, there is a limit in improving the feeling of use and the appearance (design) of the toothbrush.

Patent document 4 discloses a technique of insert molding (insert molding) filaments formed from different plural kinds of resin compositions using a die provided with a separately molded shank.

[ Prior Art literature ]

[ patent literature ]

Patent document 1: JP-A61-207233

Patent document 2: chinese utility model No. 204561298 specification

Patent document 3: chinese patent application publication No. 107041792 specification

Patent document 4: chinese utility model No. 205214577 specification

Disclosure of Invention

[ problem to be solved by the utility model ]

However, in the toothbrush described in patent document 4, since a wall for dividing the multicolor filaments is provided, a space in which the filaments cannot be arranged is formed in a portion of the wall. Therefore, there is a problem that it is difficult to arrange filaments in a regular continuous contour and a gentle contact feeling of the head inserted into the oral cavity is impaired.

The present utility model has been made in view of the above-described problems, and an object thereof is to provide a brush molded body and a toothbrush which have a soft touch feeling and can improve the feeling of use and the appearance of the toothbrush.

[ means for solving the problems ]

According to claim 1 of the present utility model, there is provided a brush molded body, characterized in that,

the brush forming body is provided with a head base part formed by soft resin and a plurality of filaments protruding from a supporting surface positioned on the front side of the head base part in the thickness direction,

the head base part has a fitting hole extending in a longitudinal direction orthogonal to the thickness direction and opening to one side of the longitudinal direction,

The brush molded body is provided with:

a preform having a filament group including at least a part of the plurality of filaments and a support stage portion that supports a base portion of the filament group and is located further toward the front side than the fitting hole, forming a part of the head stage portion, and at least a part of the preform being molded from a 1 st resin composition; and

a base body molded body having the head base portion and a portion other than the preform among the plurality of filaments, and molded from a 2 nd resin composition different from the 1 st resin composition,

the brush molded body is a molded body in which the preform and the base body molded body are integrally molded.

In the brush molded body according to the aspect of the present invention, a part of the plurality of filaments forms the filament group formed from the 1 st resin composition, and the filaments other than the filament group form the base body molded body integrally formed with the head base portion by the 2 nd resin composition.

In the brush molded body according to the aspect of the present invention, when the cross-sectional area of the support base portion is S1 in the cross-section orthogonal to the longitudinal direction, and the cross-sectional area of the region between the front surface side surface and the support surface in the interior of the fitting hole is S, the value expressed by S1/S is 0.6 or less in all the regions where the fitting hole is provided.

In the brush molded body according to the aspect 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, the value expressed by SV/(SW-S1) is 0.5 or less in all the areas where the fitting hole is provided.

In the brush molded body according to the aspect of the present invention, when the area of the head base portion as viewed from the front side in the thickness direction is P and the area of the support base portion as viewed from the front side in the thickness direction is P1, the value represented by P1/P is 0.1 to 0.5.

In the brush molded body according to the aspect of the present invention, a 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 surface side in the thickness direction is 2.0mm or more and 4.5mm or less.

In the brush molded body according to the aspect of the present invention, a maximum distance from the base end of the filament to the back surface of the head base portion is T, and when the thickness of the support base portion in the thickness direction is T1, a value represented by T1/T is 0.5 or less.

In the brush molded body according to the aspect of the present invention, when a distance between the back surface side surface of the support base portion and the front surface side surface of the inside of the fitting hole is t2, a value represented by t 1/(t1+t2) is 0.2 or more and 0.8 or less.

In the brush molded body according to the aspect of the present invention, the number of filaments in the filament group is FM, and the bonding area between the support base portion and the base body molded body is Q1 (mm) ² ) When FM/Q1 represents a value of 1.0 (root/mm ² ) The following is given.

In the brush molded body according to the aspect of the present invention, the adhesion interface between the support base portion and the base body molded body is provided with a concave-convex structure.

In the brush molded body according to the aspect of the present invention, when 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, a value represented by L2/L1 is 0.30 to 0.70.

In the brush molded body according to the aspect of the present invention, the preform may have all of the plurality of filaments.

In the brush molded body according to the aspect of the present invention, the preform includes:

the filament group and the supporting stage formed from the 1 st resin composition, and

a 2 nd filament group formed from a 3 rd resin composition different from the 1 st resin composition and the 2 nd resin composition, and a 2 nd support stage portion supporting a base portion of the 2 nd filament group.

In the brush molded body according to the aspect of the present invention, the soft resin is polyurethane.

According to claim 2 of the present invention, there is provided a toothbrush comprising:

the brush molded body according to embodiment 1 of the present invention, and

a handle body formed by hard resin and provided with a fitting protrusion which can be assembled and disassembled in the fitting hole of the brush forming body.

According to claim 3 of the present invention, there is provided a toothbrush characterized in that,

the toothbrush is provided with:

the brush molded body according to embodiment 1 of the present invention, and

a handle body having a fitting protrusion fitted into the fitting hole of the brush forming body,

the toothbrush is a molded body in which the brush molded body and the handle are integrally molded.

[ Effect of the invention ]

The invention provides a brush forming body and a toothbrush which have a soft touch feeling and can improve the use feeling and appearance of the toothbrush.

Drawings

Fig. 1 is a front view of a brush formed body 20 and a toothbrush 1 according to an embodiment of the present invention.

Fig. 2 is a side view of the same brush body 20 and toothbrush 1.

Fig. 3 is a front view of the brush formed body 20.

FIG. 4 is a cross-sectional view A-A of FIG. 3.

Fig. 5 is a view of the brush formed body 20 from the rear end side.

Fig. 6 is a cross-sectional view of a surface parallel to the support surface 21a including the fitting hole 22.

Fig. 7 is a front view of the shank 10.

Fig. 8 is a front view of the enlarged fitting projection 12.

Fig. 9 is a side view of the enlarged fitting protrusion 12.

Fig. 10 is a cross-sectional view schematically showing a width direction of an example of a die MD for molding the preform 40 in the brush molding body 20.

Fig. 11 is a cross-sectional view schematically showing an example of a mold MD for molding the base body molded body 50 in the brush molded body 20 in the width direction.

Fig. 12 is a longitudinal cross-sectional view schematically showing an example of the mold MD for secondary molding.

Fig. 13 is a cross-sectional view of the brush formed body 20 of embodiment 2 in the width direction.

Fig. 14 is a front view of brush formed body 20 according to embodiment 3.

Fig. 15 is a cross-sectional view of brush formed body 20 according to embodiment 3 in the width direction.

Fig. 16 is a front view showing a modification of brush formed body 20 according to embodiment 3.

Fig. 17 is a longitudinal cross-sectional view showing a modification of the brush formed body 20 according to embodiment 3.

Fig. 18 is a cross-sectional view of the brush formed body 20 according to embodiment 4 in the width direction.

[ reference numerals ]

1 … toothbrush; 10 … handle; 12 … fitting tab; 20 … brush shaped body; 21 … head base portion; 21a … support surface; 21c … back; 22 … fitting hole; 23 … filaments; 30 … support stands; 31 … support table portion 2; 40 … preform; 50 … base body molded body; f1 … filament group (1 st filament group); f3 … filament group (filament group 2)

Detailed Description

Embodiments of the brush molded body and the toothbrush according to the present invention will be described below with reference to fig. 1 to 18. In this embodiment, a toothbrush in which a brush molded body is detachably provided to a handle is described as an example.

The following embodiments are illustrative of one embodiment of the present invention, and the present invention is not limited to the embodiment, and may be arbitrarily changed within the scope of the technical idea of the present invention. In order to facilitate understanding of the respective structures, the actual structures, the scale and the number of the structures, and the like are different from each other in the following drawings.

Fig. 1 is a front view of a brush formed body 20 and a toothbrush 1 according to the present embodiment. Fig. 2 is a side view of the brush formed body 20 and the toothbrush 1. The toothbrush 1 includes a rod-shaped handle 10 and a brush body 20. The handle body 10 and the brush formed body 20 are different components. The brush formed body 20 is detachably attached to (inserted into) the handle 10. The brush formed body 20 is formed of a soft resin. The shank 10 is formed of a hard resin.

The front surface in the present embodiment is a side (upper side in fig. 2) on which the filaments 23 protrude in a thickness direction (hereinafter, simply referred to as a thickness direction) which is a normal direction of a support surface 21a (described in detail later) of the brush formed body 20. The side of the brush formed body 20 opposite to the front side in the thickness direction is appropriately referred to as the back side. The longitudinal direction of the handle 10 and the direction in which the handle 10 is inserted into the brush body 20 (hereinafter, simply referred to as the insertion direction) are orthogonal to the normal direction. In the longitudinal direction, the side on which the handle body 10 is attached to the brush formed 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. The direction perpendicular to the normal direction and the insertion direction is a width direction (hereinafter, simply referred to as a width direction) of the brush formed body 20.

[ embodiment 1 of brush molded body 20 ]

Fig. 3 is a front view of the brush formed body 20. Fig. 4 is a sectional view A-A in fig. 3. As shown in fig. 3 and 4, the brush formed body 20 includes: a head base portion 21 having a substantially rectangular shape in front view, and a plurality of filaments 23 provided on the front surface of the head base portion 21.

As the soft resin constituting the brush formed body 20, various elastomers can be used, but polyurethane is preferable.

Since polyurethane tends to have a higher tensile strength than other elastomers such as styrene-based and polyester-based, the use of polyurethane as the soft resin can ensure mechanical strength even if the soft resin is thin, and can suppress breakage when the handle 10 is fitted into the fitting hole 22 and when the toothbrush 1 is used.

The polyurethane may be mixed with 0.01 to 1.0wt% (mass%) of any one of saturated/unsaturated hydrocarbon having 10 or more carbon atoms, higher alcohol, fatty acid amide, fatty acid ester, low molecular weight polyethylene, polyethylene glycol (PEG), fatty acid metal salt, long chain fatty acid, fatty acid glyceride, liquid paraffin, and silicone, or may be mixed after compounding these, and functions as a lubricant and a release agent.

Further, polyurethane has a wide range of selectable hardness as compared with the other elastic bodies, and resin hardness considering usability (for example, buckling of the brush molding tip) can be selected depending on the thickness of the brush molding 20. The hardness of the polyurethane is preferably from 90 to 70 Shore A.

When the hardness of polyurethane is softer than shore 90A, the polyurethane is easily deformed when formed in a thin wall, and therefore the fitting becomes weak, and the brush formed body 20 is easily detached when the toothbrush 1 is used. In the case where the hardness of polyurethane is harder than 70D, pain may occur when the tip comes into contact with oral tissue when the back surface of the head base portion 21 is inclined. By setting the hardness of the polyurethane to be not less than 90 shore a and not more than 70D, it is possible to suppress the brush formed body 20 from falling off during use of the toothbrush 1 or the occurrence of pain when the tip of the head base part 21 is brought into contact.

In addition, as the polyurethane, an ether polyurethane is preferably used from the viewpoint of securing water resistance and antibacterial property.

The filaments 23 are substantially columnar 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 base end position of the filament 23 in the thickness direction. The filaments 23 have a substantially triangular prism shape in cross section on the base end side thereof, and a triangular cone shape in which the tip end side thereof is tapered while extending from the substantially triangular prism. The cross-sectional shape of the filament 23 may be a substantially polygonal shape such as a substantially quadrangular shape, a substantially circular shape, a substantially star shape, a substantially doctor shape, or the like, in addition to a substantially triangular shape. The filaments 23 may have a straight tubular structure or a tapered shape tapering from the base end, in addition to the tapered shape tapering from the tip end.

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

Fig. 5 is a view of the brush formed body 20 from the rear end side.

As shown in fig. 5, the plurality of filaments 23 have a filament group (1 st filament group) F1 located at the center in the width direction and filament groups F2 located on both sides in the width direction of the filament group F1. As an example, filament group F1 is higher than filament group F2.

The maximum length of the filaments 23 is preferably 7mm or more, more preferably 9mm or more.

The maximum length of the filaments 23 is preferably 15mm or less, more preferably 13mm or less.

The maximum length of the filaments 23 is preferably 7mm to 15mm, more preferably 9mm to 13 mm.

When the maximum length of the filament 23 is less than 7mm, there is a possibility that the cleaning property in the oral cavity is lowered. When the maximum length of the filaments 23 is greater than 15mm, the mold release property is lowered when the brush formed body 20 is formed by injection molding. By setting the maximum length of the filaments 23 to 7mm or more and 15mm or less, cleaning property in the oral cavity and mold release property at the time of molding can be ensured.

As the cross-sectional area of the base end of the filament 23, 0.8mm is preferable ² Hereinafter, more preferably 0.6mm ² The following is given. The cross-sectional area at the base end of the filaments 23 is greater than 0.8mm ² If the filaments 23 are hard to flex, there is a possibility that clearance cleanability between teeth, tooth necks, and the like may be lowered. By making the cross-sectional area of the base end of the filament 23 0.8mm ² Hereinafter, clearance cleaning properties such as interdental space and cervical part can be ensured.

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% to 50%. When the ratio of the total cross-sectional area of the base ends of the filaments 23 is less than 10%, there is a possibility that the cleaning property in the oral cavity may be lowered. When the proportion of the total cross-sectional area of the base ends of the filaments 23 is more than 50%, the releasability is lowered when the brush formed body 20 is formed by injection molding. 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, cleaning property in the oral cavity and mold release property at the time of molding can be ensured.

The filament group F1 constitutes a part of the plurality of filaments 23 and is formed of the 1 st 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 2 nd resin composition different from the 1 st resin composition.

The 1 st resin composition and the 2 nd resin composition may be appropriately selected from the soft resins described above in consideration of the feel and appearance (design) of the toothbrush 1. For example, when considering the feeling of use of the toothbrush 1 and combining both the massaging property and the brushing property, the soft resin having different hardness may be used. In consideration of the appearance, the soft resin may be used as a base material, and a colorant such as a masterbatch may be added to make the filament group F1 and the filament group F2 have different colors.

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

The support base 30 supports the base ends of the filament group F1 from the lower side. As shown in fig. 3, the support base 30 has a rectangular parallelepiped shape including the size of the filament group F1 and having a rectangular shape in a front view. As shown in fig. 4, the upper surface of the support table portion 30 is coplanar with the support surface 21a. That is, the upper surface of the support base 30 constitutes a part of the support surface 21a. Hereinafter, the upper surface of the support base 30 is also appropriately referred to as a support surface 21a.

The support base 30 is located on the front side of the fitting hole 22. Forming part of the head base portion 21. The support stand 30 is formed of the 1 st resin composition. The support base 30 and the filament group F1 constitute a preform 40 integrally molded from the 1 st 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 1 st portion 33 open to the end face 21b, and a 2 nd portion 34 located further inward than the 1 st portion 33. As shown in fig. 4, the 1 st part 33 and the 2 nd part 34 are disposed separately 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 projection 35 located at the substantially center of the insertion direction in the fitting hole 22 and between the 1 st part 33 and the 2 nd part 34. The projections 35 are provided on both sides in the width direction of the fitting hole 22. When the fitting protrusions 12 (see fig. 7; described later) of the shank 10 are inserted into the fitting holes 22, the protrusions 35 are provided at positions to be fitted into the recesses 15 (described later), respectively. The protrusion 35 is a circular arc shape having a circular arc center on the outer side in the width direction and protruding inward.

The shortest distance L35 between the protrusions 35 is shorter than the width L33 of the 1 st portion 33 and the width L34 of the 2 nd portion 34. The protruding amount of the protrusion 35 protruding inward in the width direction with respect to the 2 nd portion 34 is, for example, 1mm. The protrusion amount of the protrusion 35 with respect to the 2 nd portion 34 is a undercut amount when a mold (slide core) for molding the fitting hole 22 is pulled out to the rear end side at the time of injection molding of the brush molded body 20.

The head base stage 21 of the brush formed body 20 excluding the support stage 30 is formed of the 2 nd resin composition. The head base portion 21 and the filament group F2 of the brush molded body 20 excluding the support base portion 30 constitute a base body molded body 50 integrally molded from the 2 nd 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 formed of the 1 st resin composition is set in a cavity in a mold, and the 2 nd resin composition is filled into the cavity, and then the molded article is formed by performing secondary molding (insert molding).

Referring back to fig. 5, in a cross section of the head base portion 21 perpendicular to the longitudinal direction, the thickness t1 of the support base portion 30 may be selected from 0.5mm to 2.5 mm. The thickness t2 between the back surface of the support base 30 and the front surface side surface in the fitting hole 22 may be selected from 0mm to 2.5 mm. When the back surface of the support base 30 and the surface on the front side in the interior of the fitting hole 22 are on the same horizontal plane, the thickness t2 between the back surface of the support base 30 and the surface on the front side in the interior of the fitting hole 22 is 0mm. That is, the structure in which the fitting hole 22 is exposed from the back surface of the support base 30 can be selected. In this case, the lateral sides of the support base 30 in the width direction are adhesively fixed to the base body molded body 50.

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

In the cross section orthogonal to the longitudinal direction of the head base portion 21, when the cross section of the support base portion 30 is S1 and the cross section of the region of the thickness t1+t2 between the front surface side surface of the inside of the fitting hole 22 and the support surface 21a is S, the value expressed as S1/S is preferably 0.1 or more in the entire region where the fitting hole 22 is provided.

The value represented by S1/S is preferably 0.6 or less, more preferably 0.5 or less, and still more preferably 0.4 or less.

The value represented by S1/S is preferably 0.1 to 0.6, more preferably 0.1 to 0.5, still more preferably 0.1 to 0.4.

In the brush formed body 20 having the fitting hole 22, the sectional area S of the region defined by the thickness t1+t2 between the front surface side surface of the inside of the fitting hole 22 and the supporting surface 21a and the sectional area S1 of the supporting base portion 30 have a great influence on the formability of the filaments 23. In multicolor molding, after molding of the primary side, the secondary side is molded by switching the movable side (or the fixed side) of the mold, and thus molding is performed in a state where the molded body of the primary side remains in the cavity. The flowable region after the secondary side becomes further smaller. Therefore, in multicolor molding, unlike single-color molding, resin fluidity tends to be insufficient on the secondary side and thereafter, and filament molding becomes difficult. In this case, since a sufficient filling speed and holding pressure cannot be ensured, a molding failure such as a shortage or shrinkage mark is likely to occur. Specifically, when the value represented by S1/S is greater than 0.6, the filament 23 is liable to be formed poorly. In the present embodiment, by setting the value represented by S1/S to 0.6 or less, defective formation of the filaments 23 can be suppressed. In order to ensure the formability of the primary support base 30 and the filament group F1, the value indicated by S1/S is preferably set to 0.1 or more.

In the cross section orthogonal to the longitudinal direction of the head base portion 21, the cross section of the fitting hole 22 is SV, and when the cross section of the head base portion 21 including the cross section SV of the fitting hole 22 is SW, the value expressed by SV/(SW-S1) is preferably 0.1 or more in all the areas where the fitting hole 22 is provided. The value expressed 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 to 0.5, more preferably 0.1 to 0.4, still more preferably 0.1 to 0.3.

In the molding other than the primary side, that is, in the molding of the base body molded body 50, the presence of the slide core for forming the fitting hole 22 in addition to the presence of the preform 40 on the primary side previously molded has a great influence on the resin flow. If the occupation of the slide core is small, the resin easily flows in the cavity, and the moldability of the filaments 23 is improved. In contrast, when the value denoted by SV/(SW-S1) representing the occupancy of the slide core is larger than 0.5, the resin flow is restricted during molding of the base body molded body 50, and there is a possibility that molding failure of the filaments 23 (filament group F2) on the secondary side and thereafter may occur. In the present embodiment, by setting the value represented by SV/(SW-S1) to 0.5 or less, the defective formation of the filaments 23 can be suppressed. In order to ensure the strength of the slide core, the value denoted by SV/(SW-S1) is preferably set to 0.1 or more.

When the area (projection area) of the head base portion 21 at the front view angle viewed from the front side in the thickness direction is P and the area of the support base portion 30 at the same front view angle is P1, the value represented by P1/P is preferably 0.1 or more, more preferably 0.2 or more. The value represented by P1/P is preferably 0.5 or less, more preferably 0.4 or less. The value represented by P1/P is preferably 0.1 to 0.5, more preferably 0.1 to 0.4, and still more preferably 0.2 to 0.4.

Resin flow in a direction parallel to the support surface 21a is also important as a means for improving the formability of the filaments 23 (filament group F2) other than the primary side. In particular, when the gate is located at the end in the longitudinal direction of the brush formed body 20 like a side gate, the effect is remarkable. Therefore, when the value represented by P1/P is greater than 0.5, the occupation of the cavity area of the preform 40 on the primary side prevents the resin flow, and there is a possibility that the molding failure of the filaments 23 may occur during the molding of the base body molded body 50 on the secondary side and thereafter. On the other hand, if the value represented by P1/P is smaller than 0.1, the occupancy of the filament group F1 may be reduced, and the functionality (e.g., cleaning performance) may not be ensured. In the present embodiment, by setting the value represented by P1/P to 0.1 or more and 0.5 or less, the functionality of the filament group F1 can be ensured, and the defective formation of the filaments 23 can be suppressed.

The maximum distance (maximum thickness) between the support surface 21a and the back surface 21c of the head base portion 21, that is, the maximum distance T from the base end of the filament 23 to the back surface 21c is preferably 2.0mm or more and 4.5mm or less. When the maximum distance T is less than 2.0mm, the gap between the support surface 21a and the surface on the support surface 21a side of the fitting hole 22 or the gap between the back surface 21c and the surface on the back surface 21c side of the fitting hole 22 becomes smaller, and the fluidity of the molten resin decreases at the time of molding the base body molded body 50, so that there is a possibility that the resin may not be filled. In addition, when the maximum distance T is less than 2.0mm, the gap between the support surface 21a side surface of the fitting hole 22 and the support base portion 30 has to be reduced, and the fluidity of the molten resin is lowered at the time of molding the base body molded body 50. If the maximum distance T is greater than 4.5mm, the operability of the brush formed body 20 when inserted into the oral cavity may be lowered. In the present embodiment, the maximum distance T is set to 2.0mm or more and 4.5mm or less, whereby the filling property of the resin and the operability when the brush formed body 20 is inserted into the oral cavity can be ensured.

When 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 preferably 0.5 or less, more preferably 0.4 or less. When the value represented by T1/T is larger than 0.5, the entire brush molded body 20 becomes thicker to secure resin flow at the time of molding the base body molded body 50 other than the primary side, resulting in a decrease in the intraoral operability. In the present embodiment, by setting the value represented by T1/T to 0.5 or less, the present embodiment advantageously functions to have both moldability and usability in molding the base body molded body 50 on the secondary side and thereafter. In addition, from the viewpoints of the formability of the primary side and ensuring the adhesiveness of the primary side support stand portion 30 to the side surface of the head base stand portion 21, the value denoted by T1/T is preferably set to 0.1 or more.

The value represented by t 1/(t1+t2) is preferably 0.2 or more, more preferably 0.3 or more, with respect to the thickness t1 and the thickness t2 between the front surfaces in the fitting hole 22. The value represented by t 1/(t1+t2) is preferably 0.8 or less, more preferably 0.7 or less. The value represented by t 1/(t1+t2) is preferably 0.2 or more and 0.8 or less, more preferably 0.3 or more and 0.7 or less. If the value represented by t 1/(t1+t2) is greater than 0.8, there is a possibility that the resin flow on the side surface of the support table portion 30 becomes dependent because a sufficient space for the resin to flow between the back surface of the primary side (back surface of the support table portion 30) and the slide core cannot be ensured, and the moldability other than the primary side (base body molded body 50) may be lowered. Further, there is a possibility that the resin adhesion between the primary-side support base 30 and the secondary-side base body molded body 50 is unstable. If the value represented by t 1/(t1+t2) is smaller than 0.2, the formability of the primary support base 30 may not be ensured. In the present embodiment, by setting the value represented by t 1/(t1+t2) to 0.2 or more and 0.8 or less, the resin adhesion between the support base portion 30 and the base body molded body 50 can be stabilized while ensuring the moldability of the primary side support base portion 30 and the secondary side base body molded body 50.

In addition, if the thickness t2 is 0.3mm or more, problems in formability are less likely to occur even in the wide head specification. The thickness t2 is preferably 0.5mm or more, more preferably 0.8mm or more.

The number of filaments in the filament group F1 was FM, and the bonding area between the support base 30 and the base body molded body 50 was Q1 (mm) ² ) In this case, the value represented by FM/Q1 is preferably 1.0 (root/mm ² ) Hereinafter, it is more preferably 0.8 (root/mm ² ) The following is given. At the time of demolding after molding, the filaments 23 are pulled and peeled off due to the demolding resistance of the cavity surface. In the case where the value represented by FM/Q1 is greater than 1.0 (root/mm ² ) In the case of (a), in multicolor molding, when the preform 40 is released from the molded body of the base body molded body 50 after secondary molding, there is a problem that the preform 40 is separated from the base body molded body due to the release resistance of the filament group F150 possibility of peeling. In the present embodiment, the value represented by FM/Q1 is set to 1.0 (root/mm) ² ) Hereinafter, peeling of the preform 40 from the base body molded body 50 after the secondary molding can be suppressed. In addition, in the case where the number of filament groups F1 cannot be sufficiently ensured with respect to the occupied area of the support base portion 30, if the possibility of the functionality of the primary side filaments F1 being lowered is considered, it is preferable to set the value represented by FM/Q1 to 0.2 (root/mm ² ) The above.

In order to suppress the peeling of the preform 40 from the base body molded body 50 after the secondary molding, it is preferable to provide one or more concave-convex structures at the adhesion interface between the support base portion 30 and the base body molded body 50. By providing the uneven structure at the bonding interface between the support base portion 30 and the base body molded body 50, the bonding area can be increased while securing the moldability, and the adhesiveness of the primary-side preform 40 can be improved. The concave-convex structure may be arranged on either the back surface or the side surface of the support base 30, but the arrangement on the back surface is effective for increasing the bonding area because the height and width of the concave-convex structure are easily increased as compared with the side surface. When the concave-convex structure is arranged on the side surface of the support base 30, the thickness of the support base 30 and barbs (undercut) at the time of molding the preform 40 may be considered. The height (highest to lowest) of the concave-convex structure may be, for example, about 0.1 to 0.5mm, and the pitch of the concave-convex structure may be about 0.5 to 3.0 mm.

As shown in fig. 4, when the maximum length of the head base portion 21 in the longitudinal direction is L1 and the maximum length of the fitting hole 22 is L2, the value represented by L2/L1 is preferably 0.30 or more, more preferably 0.40 or more, and still more preferably 0.45 or more. The value represented by L2/L1 is preferably 0.70 or less, more preferably 0.60 or less, and still more preferably 0.55 or less. 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 smaller than 0.30, the region of the handle body 10 formed of the hard resin where the fitting protrusion 12 is not present becomes large, and therefore the brush formed body 20 tends to flex in front, and the usability as the toothbrush 1 may be lowered. When L2/L1 is greater than 0.70, the volume occupied by the mold (slide core) for forming the fitting hole 22 at the time of molding becomes large, and the resin flow is restricted, so that the moldability of the filament 23 is lowered. By setting the value represented by L2/L1 to 0.30 or more and 0.70 or less, it is possible to suppress the decrease in formability of the filaments 23 and also suppress the decrease in usability of the toothbrush 1.

[ handle 10]

Fig. 7 is a front view of the shank 10.

As shown in fig. 7, the handle body 10 includes: a rod-shaped shank 11 and a fitting projection 12 provided at the front end of the shank 11 and projecting toward the front end side in the longitudinal direction of the shank 11. The fitting protrusion 12 is detachably fitted into the fitting hole 22 of the brush body 20. In the toothbrush 1, the brush-shaped body 20 is mounted to the fitting protrusion 12 by inserting the fitting protrusion 12 of the handle body 10 into the fitting hole 22 in the brush-shaped body 20.

The shape of the shank 11 of the present embodiment in the front view is changed in a curved manner so that the width gradually narrows from the front end side toward the rear end side, then extends with a constant width, and then gradually widens and then narrows. Regarding the shape of the shank 11 in front view, the rear end portion has a substantially semicircular shape.

As shown in fig. 2, the shape of the handle 11 in a side view extends from the front end side to the rear end side with a constant width, and then gradually widens to a maximum thickness that becomes a finger contact portion. The shape of the shank 11 in a side view changes in a curve such that the width gradually becomes narrower toward the rear end side at the finger contact portion of the maximum thickness. Regarding the shape of the shank 11 in a side view, the rear end portion has a substantially semicircular shape.

In the present invention, the shape of the shank is not limited to the shape of this example, and may be appropriately set in consideration of strength, operability, design property, and the like.

The size of the shank 11 is not particularly limited and may be appropriately set. For example, the length of the shank 11 may be set to 100 to 200mm.

The fitting protrusion 12 is a portion covered by the brush body 20 in a state where the brush body 20 is attached to the handle body 10. The rear end of the fitting protrusion 12 is a rear end position of the brush formed body 20 in a state where the brush formed body 20 is mounted on the grip body 10.

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

As shown in fig. 8, the fitting projection 12 includes: a base 13 provided on the front end side of the handle 11, and a front end 14 provided on the front end of the base 13. As shown in fig. 9, the base portion 13 and the tip portion 14 are formed to have a level difference with respect to the shank portion 11 on both sides of the front surface side and the rear surface side, and to be thinner than the shank portion 11 by the same thickness.

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

The fitting projection 12 has a recess 15 substantially at the center in the insertion direction between the base 13 and the distal end 14. The recesses 15 are provided on both sides in the width direction. The recess 15 has an arc shape with an arc center on the outer side in the width direction and a recess toward the inner side. 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 portion 14. An example of the recess amount of the recess 15 with respect to the end edge of the predetermined width L14 in the front end portion 14 is 1mm.

The shank 10 is formed of a hard resin.

As an example of the hard resin, a resin having a flexural modulus of elasticity (JIS K7171) of 1500MPa to 3000MPa is exemplified. Specifically, for example, polypropylene resin (PP), polyacetal resin (POM), polyester resin (PCTA), polyethylene terephthalate copolymer (PETG), high Density Polyethylene (HDPE) may be exemplified. Among them, PP of general-purpose resin is preferable in view of cost.

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

The shape of the fitting hole 22 in the front view is substantially the same as the shape of the fitting protrusion 12 in the front view. The width L33 of the 1 st portion 33 is a length of the fitting protrusion 12 into which the base portion 13 can be inserted, and is substantially the same as the maximum width L13 of the base portion 13. The width L34 of the 2 nd portion 34 is a length of the fitting protrusion 12 into which the tip portion 14 can be inserted, and is substantially the same as the maximum width L14 of the tip portion 14. The shortest distance L35 between the projections 35 is a length in which the tip portion 14 and the recess 15 of the fitting projection 12 can be inserted, and is substantially the same as the shortest distance L15 between the recesses 15.

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

The mold MD includes: a 1 st die MD1 and a 2 nd die MD2 for one-time molding, which are relatively movable in the opening and closing direction (up and down direction in fig. 10). The 1 st die MD1 and the 2 nd die MD2 are clamped with a parting plane PL on the same horizontal plane as the support surface 21a as a joint surface. As an example, the 1 st die MD1 is a fixed die, and the 2 nd die MD2 is a movable die.

The 1 st die MD1 is mounted on, for example, a stationary side of an injection molding machine, and is filled with a molten resin from the injection molding machine. The 2 nd die MD2 is attached to, for example, a movable side of the injection molding machine, and is moved in the opening and closing direction with respect to the 1 st die MD1 to open and close the die MD.

The 1 st die MD1 has a molding surface 21aM for molding the support surface 21a when the 2 nd die MD2 is joined to the mold, a cavity F1M for molding the filament group F1, and a cavity F2M for molding the filament group F2. The cavity F1M and the cavity F2M are open to the parting plane PL of the first mold MD 1.

The 2 nd die MD2 has a cavity 30M that forms the support base 30 when the 1 st die MD1 is joined by closing. The cavity 30M opens into the cavity F1M. The cavity 30M is not open to the cavity F2M. The opening of the cavity F2M is closed by the parting plane PL of the 2 nd die MD 2. The cavity 30M is provided with a gate portion, not shown. As the gate portion, for example, a side gate method is adopted, but a pin gate method or a tunnel gate method may be adopted.

In the mold MD, the molten 1 st resin composition introduced into the cavity 30M from the gate portion G fills the cavity 30M and the cavity F1M in a state where the 1 st mold MD1 and the 2 nd mold MD2 are clamped. On the other hand, the cavity 30M is not opened to the cavity F2M, and the opening of the cavity F2M is closed by the parting plane PL of the 2 nd mold MD2, and thus is not filled with the 1 st resin composition. Then, the preform 40 formed of the 1 st resin composition having the filament group F1 and the support base 30 is formed by cooling in a state where the 1 st mold MD1 and the 2 nd mold MD2 are clamped.

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

The mold MD includes: the 1 st die MD1 and the 2 nd die MD12 are relatively movable in the opening and closing direction. The 1 st die MD1 is the above-mentioned 1 st die MD1 which is held without releasing the molded preform 40. A part of the 1 st mold MD1 for the primary molding including the cavity F1M and the cavity F2M may be detached and attached to the 1 st mold MD1 for the secondary molding.

The 2 nd die MD12 has: the mold cavity 21M of the head base portion 21 is formed when the mold is clamped and joined to the 1 st mold MD1, the gate portion G which opens to the front end side of the mold cavity 21M and introduces the molten resin into the mold cavity 21M, and the contact surface 21eM which is provided at the position of the end surface 21b in the insertion direction and is orthogonal to the insertion direction. As shown in fig. 11, a cavity F2M for forming the filament group F2 is opened to the cavity 21M. As the gate portion G, for example, a side gate method is adopted, but a pin gate method or a tunnel gate method may be adopted. The contact surface 21eM extends in the direction away from the PL surface from the position of the back surface in the molding head base portion 21 in the 2 nd die MD 2.

In the 2 nd die MD12, a slide core SL is provided. The slide core SL has: a core 22M for forming the fitting hole 22, and a forming surface 21bM orthogonal to the protruding insertion direction of the core 22M. As shown in fig. 11, the molding surface 21bM is separated from the contact surface 21eM before the mold is closed. As for the slide core SL, when the first mold MD1 and the second mold MD12 are clamped, as shown in fig. 11, the slide core SL is positioned at the following positions: a part of the molding surface 21bM is in contact with the contact surface 21eM, and the core 22M is inserted into the cavity 21M. The region of the molding surface 21bM that faces the cavity 21M without abutting the abutment surface 21eM is a region of the molding end surface 21 b. In addition, the slide core SL moves in a direction of releasing the core 22M from the cavity 21M when the 1 st die MD1 and the 2 nd die MD12 are opened, so that the core 22M does not hinder the release of the molded brush formed body 20. The moving direction of the slide core SL is preferably a horizontal direction to avoid unexpected movement due to self weight.

In the above mold MD, the molten 2 nd resin composition introduced into the cavity 21M from the gate portion G in a state where the 1 st mold MD1 and the 2 nd mold MD12 are clamped fills the cavity 21M and the cavity F2M. The 2 nd resin composition filled in the cavity 21M covers the side surface and the back surface of the support base 30, and adheres to the support base 30. Then, the 1 st mold MD1 and the 2 nd mold MD12 are cooled in a state of being clamped, and released from the mold MD, whereby a molded body is obtained which is provided with the preform 40 and the base body molded body 50, and in which the preform 40 and the base body molded body 50 are integrally molded, the preform 40 having the filament group F1 and the support table portion 30 and being formed of the 1 st resin composition, and the base body molded body 50 having the head base portion 21 and a portion other than the preform 40 among the plurality of filaments 23 and being molded of the 2 nd resin composition.

That is, the brush molded body 20 in which the filaments 23 and the head base portion 21 are integrally molded as a molded body is obtained, the filaments 23 having the filament group F1 formed of the 1 st resin composition and the filament group F2 formed of the 2 nd resin composition, and the head base portion 21 including the support base portion 30 formed of the 1 st resin composition and being formed of the 2 nd resin composition.

The brush molded body 20 is molded, and the fitting protrusion 12 of the handle 10 is inserted into the fitting hole 22 and fitted, whereby the toothbrush 1 in which the brush molded body 20 and the handle 10 are integrated can be obtained. Further, by pulling out the fitting protrusion 12 of the handle body 10 from the fitting hole 22, the brush formed body 20 can be detached from the handle body 10 and replaced.

As described above, in the brush formed body 20 of the present embodiment, since the filament group F1 formed of the soft resin of the 1 st resin composition and the filament group F2 formed of the soft resin of the 2 nd resin composition are provided, by appropriately selecting the 1 st resin composition and the 2 nd resin composition according to the purpose, a brush formed body and a toothbrush which have a soft touch feeling and can improve the feel and appearance of the toothbrush 1 can be obtained.

[ embodiment 2 of brush molded body 20 ]

Next, embodiment 2 of the brush formed body 20 will be described with reference to fig. 13. In these drawings, the same reference numerals are given to the same components as those of embodiment 1 shown in fig. 1 to 12, and the description thereof will be omitted.

In embodiment 1, the preform 40 is formed of 1 resin composition, but in embodiment 2, a description is given of a structure formed of a plurality of resin compositions.

Fig. 13 is a cross-sectional view of the brush formed body 20 of embodiment 2 in the width direction.

As shown in fig. 13, the preform 40 of the present embodiment includes: a filament group (2 nd filament group) F3 arranged at the center in the width direction, filament groups F1 arranged on both sides in the width direction of the filament group F3, a 2 nd support stage 31 supporting the base of the filament group F3, and a support stage 30 supporting the base of the filament group F1. The filament group F3 is formed of a 3 rd resin composition different from the 1 st resin composition and the 2 nd resin composition. The filament groups F1 and F3 are formed of a plurality of filaments 23 arranged and aligned in the longitudinal direction of the head base portion 21. The 3 rd resin composition may be appropriately selected from the above soft resins.

The 2 nd support land 31 is formed of the 3 rd resin composition. The side surfaces and the back surface of the 2 nd support table portion 31 in the width direction are bonded to the support table portion 30. The surface on the front side of the 2 nd support table portion 31 is coplanar with the support surface 21 a. The preform 40 of the present embodiment is a molded body in which the group of filaments F3 and the 2 nd support base 31 molded from the 3 rd resin composition and the group of filaments F1 and the support base 30 molded from the 1 st resin composition are integrally molded.

As an example, the preform 40 can be obtained by two-color molding in which the 3 rd resin composition forms the filament group F3 and the 2 nd support base 31 in the first molding and the 1 st resin composition forms the filament group F1 and the support base 30 in the second molding. Alternatively, the molding may be performed by insert molding, in which the filament group F1 and the support base 30 are molded from the 1 st resin composition using a die provided with the filament group F3 molded from the 3 rd resin composition and the 2 nd support base 31.

The brush molded body 20 of the present embodiment can be obtained by three-color molding, in which the 3 rd resin composition forms the filament group F3 and the 2 nd support base portion 31 in the first molding, the 1 st resin composition forms the filament group F1 and the support base portion 30 in the second molding, and the 2 nd resin composition forms the filament group F2 and the head base portion 21 in the third molding. Alternatively, the filament group F2 and the head base part 21 may be molded from the 2 nd resin composition by insert molding using a mold provided with a preformed preform 40.

The brush molded body 20 having the above-described structure can provide a toothbrush 1 having various added values by using a larger variety of resin compositions according to the specifications of the toothbrush 1, in addition to the same operations and effects as those of the brush molded body 20 of embodiment 1.

[ embodiment 3 of brush molded body 20 ]

Next, embodiment 3 of the brush formed body 20 will be described with reference to fig. 14 and 15. In these drawings, the same reference numerals are given to the same components as those of embodiment 2 shown in fig. 13, and the description thereof will be omitted.

In the present embodiment, the filament group is schematically represented as a region in which the filament group is arranged.

Fig. 14 is a front view of brush formed body 20 according to embodiment 3. Fig. 15 is a cross-sectional view of brush formed body 20 according to embodiment 3 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 2 nd support base 31 is bonded to the support base 30. The 2 nd support stand portion 31 penetrates the support stand portion 30 in the thickness direction. The back surface of the 2 nd support table portion 31 is on the same horizontal plane as the back surface of the support table portion 30.

Other structures are the same as those of embodiment 2.

In the present embodiment, in addition to the same operation and effects as those of embodiment 2 described above, it is also possible to provide a toothbrush 1 having various added values by arranging filaments 23 two-dimensionally in addition to straight lines and using a larger variety of resin compositions according to the specifications of the toothbrush 1.

The two-dimensional arrangement of filaments 23 may be, for example, the following: as shown in the front view of fig. 16 and the longitudinal cross-sectional view of fig. 17, the filament group F1 and the support base 30 are arranged in parallel with the filament group F3 and the 2 nd support base 31 in the longitudinal direction.

[ embodiment 4 of brush molded body 20 ]

Next, embodiment 4 of the brush formed body 20 will be described with reference to fig. 18. In the drawings, the same components as those of embodiment 1 shown in fig. 1 to 12 are given the same reference numerals, and the description thereof is omitted.

Fig. 18 is a cross-sectional view of the brush formed body 20 according to embodiment 4 in the width direction.

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

Other structures are the same as those of embodiment 1.

In the brush molded body 20 having the above-described structure, as in embodiment 1, since the filament group F1 and the head base portion 21 are molded from different resin compositions, a brush molded body and a toothbrush having a soft touch feeling and capable of improving the feel and appearance of the toothbrush 1 in use can be obtained.

In the brush molded body 20 having the above-described structure, since the preform 40 has all filaments 23, the mold release resistance of the preform 40 when the brush molded body 20 is released from the mold becomes large. Therefore, as described above, at least one of the relationship between the number of filaments FM and the area Q1 where the support base portion 30 and the base body molded body 50 are bonded, and the concave-convex structure provided at the bonding interface between the support base portion 30 and the base body molded body 50 is preferably employed.

Examples (example)

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples and can be implemented with appropriate modifications within the scope of not departing from the gist thereof.

Examples 1 to 8 and comparative example 1

At least one different toothbrush among the items shown in Table 1 was used as the sample of examples 1 to 8 and comparative example 1. The resin constituting each sample was polyurethane.

[ evaluation method ]

For each of the samples of examples 1 to 8 and comparative example 1, filament formability, ease of brushing of the entire oral cavity, and adhesiveness of the preform on the primary forming side were evaluated, respectively.

(1) Method for evaluating formability of filaments

The 5 brush molded bodies molded under the same conditions were evaluated according to the following criteria.

5, the method comprises the following steps: no appearance failure was observed at all.

4, the following steps: the front end of the filament is deformed at the time of demolding (bent by an external force at the time of demolding because of insufficient load pressure).

3, the method comprises the following steps: the thickness of the front end of the filament is smaller than the design value.

2, the method comprises the following steps: the length of the filaments is shorter than the design value (the total filaments are more than half of the total length).

1, the method comprises the following steps: the length of the filaments is shorter than the design value (less than half of the full length filaments are present).

Then, an average value of 5 evaluation scores was obtained, and evaluation was performed based on the following 4 grades.

Very good (double circle label (double circle mark)): 4.5 minutes or more and 5.0 minutes or less.

Circle mark: 3.5 minutes or more and less than 4.5 minutes.

Delta (triangle mark)): more than 2.5 minutes and less than 3.5 minutes.

X (cross mark): less than 2.5 minutes.

(2) Method for evaluating integral grinding and sweeping difficulty in oral cavity

Sensory evaluation by 10 panelists was performed, and the overall ease of brushing in the oral cavity at the time of brushing (the ease of brushing of molar teeth was particularly emphasized) was evaluated according to the following criteria.

5, the method comprises the following steps: the brush is very easy.

4, the following steps: slightly easier to brush.

3, the method comprises the following steps: i.e. not easy nor difficult.

2, the method comprises the following steps: it is slightly difficult to brush.

1, the method comprises the following steps: it is very difficult to brush.

Then, the average value of the evaluation scores by 10 panelists was obtained, and the following 4-level evaluation was performed.

And (3) the following materials: 4.5 minutes or more and 5.0 minutes or less.

O: 3.5 min or more, less than 4.5 min.

Delta: more than 2.5 minutes and less than 3.5 minutes.

X: less than 2.5 minutes.

(3) Method for evaluating adhesiveness of preform on primary molding side

The 5 brush molded bodies molded under the same conditions were evaluated according to the following criteria.

5, the method comprises the following steps: no appearance failure was observed at all.

4, the following steps: due to the mold release resistance at the time of mold release, the primary side base portion deforms (the state in which the brush surface is no longer smooth).

3, the method comprises the following steps: although peeling was not observed in appearance, peeling was confirmed on the resin boundary if an external force was applied.

2, the method comprises the following steps: and when demolding, a part of the primary side base part is peeled off and a part of the primary side base part is connected.

1, the method comprises the following steps: the entire primary side is peeled off and separated from the brush formed body (the state where the primary side remains in the mold).

Then, an average value of 5 evaluation scores was obtained, and evaluation was performed based on the following 4 grades.

And (3) the following materials: 4.5 minutes or more and 5.0 minutes or less.

O: 3.5 min or more, less than 4.5 min.

Delta: more than 2.5 minutes and less than 3.5 minutes.

X: less than 2.5 minutes.

TABLE 1

As shown in table 1, the ratio of the cross-sectional area S1 of the support base 30 to the cross-sectional area S of the region between the front surface side surface and the support surface 21a in the interior of the fitting hole 22, that is, the sample example 1 of examples 1 to 8 having a value of 0.6 or less expressed by S1/S, gave good results in all of the filament formability, the intra-oral cavity sweeping difficulty, and the adhesiveness of the preform on the primary forming side. In contrast, in the sample of comparative example 1 in which the value represented by S1/S was greater than 0.6, the filament formability was not well evaluated.

When the conditions shown in example 1 were set, good results were obtained for the filament moldability, the ease of brushing the entire oral cavity, and the adhesiveness of the primary preform.

When the conditions shown in example 2 are set, the value indicated by S1/S increases as the primary support base portion expands. Thus, the resin flow on the secondary side and later was reduced, and as a result, the filament moldability was inferior to that of the sample of example 1. The number FM of the 1 st filament group increases with the expansion of the primary support base portion, but the bonding area Q1 of the support base portion also increases, so that the adhesiveness of the primary preform is the same as that of the sample of example 1.

When the conditions shown in example 3 are set, the value denoted by SV/(SW-S1) increases as the sliding core increases in thickness. Thus, the resin flow during molding of the base body molded article was reduced, and as a result, the moldability of the secondary and subsequent filaments 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, and as a result, the cleaning difficulty of the entire oral cavity was inferior to that of the sample of example 1. In addition, since the support base portion of the sample of example 5 also became thicker, the value indicated by T1/T became larger, and the resin flow at the time of molding the base body molded body was reduced as compared with the sample of example 4, and as a result, the moldability of the filament was inferior to that of the sample of example 1.

Under the conditions shown in examples 6 and 8, the values indicated by t 1/(t1+t2) were increased, and a sufficient space for the resin to flow between the back surface of the primary support table portion and the slide core was not ensured, and the resin flow was lowered, resulting in inferior filament formability than that of the sample of example 1. However, in the sample of example 8, the surface on the back side of the support base portion was not exposed to the surface on the front side in the interior of the fitting hole, and therefore the adhesiveness of the primary-side preform was not lowered, as compared with the sample of example 6.

When the conditions shown in example 7 were set, the number FM of the 1 st filament group was increased as compared with example 1, but since the bonding area Q1 of the support base portion was not changed, FM/Q1 was increased, and as a result, the adhesiveness of the primary-side preform was inferior to that of the sample of example 1.

The preferred embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited to these examples. The various shapes, combinations, and the like of the respective constituent members shown in the above examples are merely examples, and various modifications can be made according to design requirements and the like within a range not departing from the gist of the present invention.

For example, in the above-described embodiment, the toothbrush 1 is exemplified as the structure in which the brush body 20 is attached to the handle body 10 by the brush body 20 and the handle body 10 being formed separately, and the fitting protrusion 12 of the handle body 10 being fitted into the fitting hole 22 of the brush body 20. For example, the following structure is also possible: in place of the slide core SL, the fitting protrusion 12 of the shank 10 is provided on the mold provided with the preform, and insert molding is performed by the 2 nd resin composition at the time of secondary molding. By this insert molding, the toothbrush 1 can be obtained as a molded body in which the brush molded body 20 and the handle 10 are integrally molded by fitting the fitting protrusion 12 into the fitting hole 22.

In the above embodiment, the structure in which the shank 10 is made of a hard resin has been described, but the structure is not limited to this, and for example, a structure in which a part of the shank 10 (the shank 11 and the like) is covered with a soft resin may be used. With this structure, decorativeness and gripping property can be improved.

[ Industrial applicability ]

The present invention is applicable to a brush molded body and a toothbrush.

Claims (16)

1. A brush molded body is characterized in that,

the brush molded body has: a head base part formed by soft resin, and a plurality of filaments protruding from a supporting surface positioned on the front side of the head base part in the thickness direction,

the head base part has a fitting hole extending in a longitudinal direction orthogonal to the thickness direction and opening to one side in the longitudinal direction,

the brush molded body is provided with:

a preform having: a support stand portion that includes a filament group of at least a part of the plurality of filaments and a base portion that supports the filament group and is located further to the front side than the fitting hole, forms a part of the head stand portion, and at least a part of the preform is molded from a 1 st resin composition; and

A base body molded body having: the head base portion and a portion of the plurality of filaments other than the preform, and the base body molded body is molded from a 2 nd resin composition different from the 1 st resin composition,

the brush molded body is a molded body in which the preform and the base body molded body are integrally molded.

2. The brush-formed body according to claim 1, wherein,

a part of the plurality of filaments constitutes the filament group formed from the 1 st resin composition,

the filaments other than the filament group among the plurality of filaments constitute the base body molded body integrally molded with the head base portion by the 2 nd resin composition.

3. The brush formed body according to claim 1 or 2, wherein,

in a cross section of the head base portion orthogonal to the longitudinal direction,

the cross section area of the supporting table part is S1,

when the sectional area of the region between the front surface side surface and the support surface in the interior of the fitting hole is S,

the value expressed by S1/S is 0.6 or less in all regions where the fitting holes are provided.

4. The brush-shaped body according to claim 3, wherein,

In a cross section orthogonal to the longitudinal direction,

the cross-sectional area of the jogged hole is SV,

when the cross-sectional area of the head base portion including the cross-sectional area of the fitting hole is SW,

in all regions where the fitting holes are provided, the value expressed by SV/(SW-S1) is 0.5 or less.

5. The brush formed body according to any one of claims 1 to 4, wherein,

the area of the head base portion as viewed from the front side in the thickness direction is P,

when 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 to 0.5.

6. The brush formed body according to any one of claims 1 to 5, wherein,

the maximum distance from the base end of the filament to the back surface of the head base portion on the opposite side to the front surface side in the thickness direction is 2.0mm or more and 4.5mm or less.

7. The brush-formed body according to claim 6, wherein,

the maximum distance from the base end of the filament to the back surface of the head base part is T,

when the thickness of the supporting table portion in the thickness direction is t1,

the value represented by T1/T is 0.5 or less.

8. The brush-formed body according to claim 7, wherein,

When the distance between the surface on the back side of the support base and the surface on the front side in the interior of the fitting hole is t2,

the value represented by t 1/(t1+t2) is 0.2 or more and 0.8 or less.

9. The brush formed body according to any one of claims 1 to 8, wherein,

the number of filaments in the filament set is FM,

the bonding area between the support base and the base body molded body is Q1 (mm) ² ) In the time-course of which the first and second contact surfaces,

the value expressed by FM/Q1 is 1.0 or less in root/mm ² 。

10. The brush formed body according to any one of claims 1 to 9, wherein,

an uneven structure is provided at an adhesion interface between the support base portion and the base body molded body.

11. The brush formed body according to any one of claims 1 to 10, wherein,

the maximum length of the head base portion in the longitudinal direction is L1,

when the maximum length of the fitting hole in the longitudinal direction is L2,

the value represented by L2/L1 is 0.30 to 0.70.

12. The brush formed body according to any one of claims 1 to 11, wherein,

the preform has all of the plurality of filaments.

13. The brush formed body according to any one of claims 1 to 11, wherein,

The preform has:

the filament group formed from the 1 st resin composition and the support stage; and

a 2 nd filament group formed from a 3 rd resin composition different from the 1 st resin composition and the 2 nd resin composition, and a 2 nd support land portion supporting a base portion of the 2 nd filament group.

14. The brush formed body according to any one of claims 1 to 13, wherein,

the soft resin is polyurethane.

15. A toothbrush is characterized in that,

the device is provided with:

the brush formed body according to any one of claims 1 to 14, and

a handle body formed by hard resin and provided with a fitting protrusion which can be assembled and disassembled in the fitting hole of the brush forming body.

16. A toothbrush is characterized in that,

the toothbrush is provided with:

the brush formed body according to any one of claims 1 to 14, and

a handle body having a fitting protrusion fitted into the fitting hole of the brush forming body,

the toothbrush is a molded body in which the brush molded body and the handle body are integrally molded.