Brush-shaped body and toothbrush
By combining soft resin with multiple filaments, the problem of impaired contact feel caused by irregular filament configuration in toothbrushes is solved, achieving a gentle touch and improved appearance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LION CORP
- Filing Date
- 2021-12-21
- Publication Date
- 2026-05-26
Smart Images
Figure CN116648169B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to brush-shaped articles and toothbrushes.
[0002] This application claims priority based on Japanese Patent Application No. 2020-214798, filed on December 24, 2020, the contents of which are incorporated herein by reference. Background Technology
[0003] A proposed solution is to manufacture a one-piece toothbrush using only an injection molding machine (e.g., Patent Document 1). Since the one-piece toothbrush integrally molds the filaments and the head base (or head), it eliminates the need for filament material supply and a bristle implantation machine, and has the advantage of being able to be manufactured more cheaply than bristle-implanted toothbrushes.
[0004] As for one-piece molded toothbrushes for brushing, some have proposed solutions to provide one-piece molded toothbrushes by separately molding a head (brush body) having filaments and an insertion hole and a handle having an insertion part at one end, and then fitting them together (for example, Patent Documents 2 and 3). In the toothbrushes described in Patent Documents 2 and 3, since the head can be replaced by the user, it is expected that only the head will be discarded and the handle can be reused, thus saving resources.
[0005] Because the head is made of a single resin material, there are limits to improving the user experience and appearance (design) of the toothbrush.
[0006] Patent document 4 discloses a technique for insert molding filaments formed from various resin compositions using a mold configured with an additional shaped shank.
[0007] [Existing Technical Documents]
[0008] [Patent Literature]
[0009] Patent Document 1: JP 61-207233
[0010] Patent Document 2: Chinese Utility Model No. 204561298
[0011] Patent Document 3: Description of Chinese Patent Application Publication No. 107041792
[0012] Patent Document 4: Chinese Utility Model No. 205214577 Summary of the Invention
[0013] [The problem the invention aims to solve]
[0014] However, in the toothbrush described in Patent Document 4, because it has a wall that divides the multi-colored filaments, there are spaces in the wall where the filaments cannot be arranged. Therefore, there are problems such as difficulty in arranging the filaments in a regular and continuous outline, and impaired gentle contact with the head inserted into the mouth.
[0015] The present invention was made in view of the above-mentioned problems, and its object is to provide a brush-shaped body and a toothbrush that have a gentle touch and can improve the user experience and appearance of the toothbrush.
[0016] [Methods used to solve problems]
[0017] According to a first aspect of the present invention, a brush-shaped article is provided, characterized in that,
[0018] The brush-shaped body has a head base portion 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 portion.
[0019] The head base portion has a fitting hole that extends in a length direction orthogonal to the thickness direction and opens to one side in that length direction.
[0020] The brush-shaped body comprises:
[0021] A preform having a filament assembly comprising at least a portion of the plurality of filaments and a base supporting the filament assembly and located further toward the front side than the fitting hole, forming part of the head base portion, and at least a portion of the preform being formed from a first resin composition; and
[0022] A base body molding body having the head base portion and portions of the plurality of filaments excluding the preform, and the base body molding body is formed from a second resin composition different from the first resin composition.
[0023] The brush-shaped body is a shaped body integrally formed from the pre-shaped body and the base body.
[0024] Furthermore, in the brush-shaped body according to one aspect of the present invention described above, a portion of the plurality of filaments constitutes the filament group formed by the first resin composition, and the filaments other than the filament group constitute the base body formed integrally with the head base portion by the second resin composition.
[0025] Furthermore, in the brush-shaped body according to one aspect of the present invention, it is characterized in that, in the cross section of the head base portion orthogonal to the length direction, when the cross-sectional area of the support base portion is S1 and the cross-sectional area of the region between the front side surface and the support surface located inside the fitting hole is S, the value represented by S1 / S is 0.6 or less in the entire region where the fitting hole is provided.
[0026] Furthermore, in the brush-shaped body according to one aspect of the present invention, it is characterized in that, in a cross section orthogonal to the length direction, 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 represented by SV / (SW-S1) in the entire region where the fitting hole is provided is 0.5 or less.
[0027] Furthermore, in the brush-shaped body according to one aspect of the present invention described above, it is characterized in that when 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 expressed by P1 / P is 0.1 or more and 0.5 or less.
[0028] Furthermore, in the brush-shaped body according to one aspect of the present invention described above, the maximum distance from the base end of the filament to the back side of the head base portion on the side opposite to the front side in the thickness direction is 2.0 mm or more and 4.5 mm or less.
[0029] Furthermore, in the brush-shaped body according to one aspect of the present invention, the maximum distance from the base end of the filament to the back side of the head base portion is T, and when the thickness of the support base portion in the thickness direction is t1, the value expressed by t1 / T is 0.5 or less.
[0030] Furthermore, in the brush-shaped body according to one aspect of the present invention described above, it is characterized in that when the distance between the back side surface of the support platform and the front side surface inside the fitting hole is t2, the value represented by t1 / (t1+t2) is 0.2 or more and 0.8 or less.
[0031] Furthermore, in the brush-formed body according to one aspect of the present invention, the number of filaments in the filament group is FM, and the area of bonding between the support platform and the base body is Q1 (mm²). 2 When FM / Q1 is used, the value is 1.0 (roots / mm). 2 )the following.
[0032] Furthermore, in the brush-shaped body according to one aspect of the present invention, the characteristic feature is that a concave-convex structure is provided at the bonding interface between the support platform portion and the base body molded body.
[0033] Furthermore, in the brush-shaped body according to one aspect of the present invention, when the maximum length of the head base portion in the length direction is L1 and the maximum length of the fitting hole in the length direction is L2, the value represented by L2 / L1 is 0.30 or more and 0.70 or less.
[0034] Furthermore, in the brush-formed body according to one aspect of the present invention, the preformed body is characterized in that it has all of the plurality of filaments.
[0035] Furthermore, in the brush-formed body according to one aspect of the present invention described above, the preformed body is characterized by having:
[0036] The filament assembly and the support platform formed from the first resin composition, and
[0037] A second filament assembly formed from a third resin composition different from the first resin composition and the second resin composition, and a second support platform supporting the base of the second filament assembly.
[0038] Furthermore, in the brush-formed article of one aspect of the present invention described above, the soft resin is characterized in that it is polyurethane.
[0039] According to a second aspect of the present invention, a toothbrush is provided, characterized in that it comprises:
[0040] The brush-shaped body of the first aspect of the present invention, and
[0041] A handle made of hard resin, having a fitting protrusion that can be easily inserted and removed from the fitting hole of the brush body.
[0042] According to a third aspect of the present invention, a toothbrush is provided, characterized in that...
[0043] The toothbrush has the following features:
[0044] The brush-shaped body of the first aspect of the present invention, and
[0045] A handle having a fitting protrusion that fits into the fitting hole of the brush-shaped body.
[0046] The toothbrush is a molded body in which the brush body and the handle body are integrally formed.
[0047] [The effects of the invention]
[0048] The present invention can provide a brush-shaped body and a toothbrush that have a gentle touch and can improve the user experience and appearance of the toothbrush. Attached Figure Description
[0049] [ Figure 1 [Image 1] is a front view of the brush-shaped body 20 and the toothbrush 1 according to an embodiment of the present invention.
[0050] [ Figure 2 [This is a side view of the same brush-shaped body 20 and toothbrush 1.]
[0051] [ Figure 3 [This is a front view of the brush-shaped body 20.]
[0052] [ Figure 4 ]yes Figure 3 AA section view.
[0053] [ Figure 5 [Image showing the brushed body 20 viewed from the rear side]
[0054] [ Figure 6 [ ] is a cross-sectional view of the surface parallel to the support surface 21a, including the fitting hole 22.
[0055] [ Figure 7 [This is a front view of the handle 10.]
[0056] [ Figure 8 [This is an enlarged front view of the fitting protrusion 12.]
[0057] [ Figure 9 [This is an enlarged side view of the fitting protrusion 12.]
[0058] [ Figure 10 [Illustrated] is a cross-sectional view in the width direction of an example of a mold MD used to form a preform 40 in a brush forming body 20.
[0059] [ Figure 11 [Illustrated] is a simplified cross-sectional view in the width direction of an example of the mold MD used to form the base body 50 in the brush forming body 20.
[0060] [ Figure 12 [ ] is a simplified cross-sectional view along the length of an example of a mold MD used for secondary forming.
[0061] [ Figure 13 [ ] is a cross-sectional view of the brush-shaped body 20 in the width direction according to the second embodiment.
[0062] [ Figure 14 [This is a front view of the brush-shaped body 20 according to the third embodiment.]
[0063] [ Figure 15 [ ] is a cross-sectional view of the brush-shaped body 20 in the width direction according to the third embodiment.
[0064] [ Figure 16 [ ] is a front view showing a modified example of the brush-shaped body 20 according to the third embodiment.
[0065] [ Figure 17[ ] is a cross-sectional view along the length of a modified example of the brush-shaped body 20 according to the third embodiment.
[0066] [ Figure 18 [ ] is a cross-sectional view of the brush-shaped body 20 in the width direction according to the fourth embodiment.
[0067] [Figure Labels]
[0068] 1…toothbrush; 10…handle; 12…fitting protrusion; 20…brush forming body; 21…head base; 21a…support surface; 21c…back side; 22…fitting hole; 23…filament; 30…support platform; 31…second support platform; 40…preform; 50…base body forming body; F1…filament group (first filament group); F3…filament group (second filament group) Detailed Implementation
[0069] The following is for reference Figures 1 to 18 Embodiments of the brush-shaped body and toothbrush of the present invention will be described. In this embodiment, an example of a toothbrush in which the brush-shaped body is detachably mounted on the handle will be described.
[0070] It should be noted that the following embodiments represent one aspect of the present invention and do not limit the present invention; any modifications can be made within the scope of the technical concept of the present invention. Furthermore, for ease of understanding of the structures, the actual structures and the scale and quantities in each structure will differ in the following drawings.
[0071] Figure 1 This is a front view of the brush-shaped body 20 and the toothbrush 1 of this embodiment. Figure 2 This is a side view of the brush-shaped body 20 and the toothbrush 1. The toothbrush 1 has a rod-shaped handle 10 and a brush-shaped body 20. The handle 10 and the brush-shaped body 20 are separate parts. The brush-shaped body 20 is detachably installed (inserted) into the handle 10. The brush-shaped body 20 is made of soft resin. The handle 10 is made of hard resin.
[0072] It should be noted that, in this embodiment, the front side refers to the side where the filament 23 protrudes in the normal direction of the support surface 21a of the brush-formed body 20 (details as described below), i.e., the thickness direction (hereinafter referred to as the thickness direction). Figure 2(The upper side of the brush forming body 20). In the thickness direction of the brush forming body 20, the side opposite to the front side is appropriately referred to as the back side. Furthermore, the length direction of the handle 10 and the direction in which the handle 10 is inserted relative to the brush forming body 20 (hereinafter simply referred to as the insertion direction) are orthogonal to the aforementioned normal direction. In the length direction, the side of the handle 10 mounted relative to the brush forming 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. Furthermore, the direction orthogonal to the aforementioned normal direction and insertion direction is the width direction of the brush forming body 20 (hereinafter simply referred to as the width direction).
[0073] [First Embodiment of Brush-Shaped Body 20]
[0074] Figure 3 This is a front view of the brush-formed body 20. Figure 4 yes Figure 3 Cross-sectional view of section AA. (See diagram below.) Figure 3 and Figure 4 As shown, the brush-shaped body 20 includes: a head base portion 21 with a generally rectangular shape in a front view and a plurality of filaments 23 disposed on the front side of the head base portion 21.
[0075] Various elastomers can be used as the soft resin constituting the brush-shaped body 20, but polyurethane is preferred.
[0076] Compared to other elastomers such as styrene-based or polyester-based elastomers, polyurethane tends to have high tensile strength. Therefore, by using polyurethane in a soft resin, mechanical strength can be ensured even when thin walls are formed, which can suppress breakage when the handle 10 is fitted into the fitting hole 22 and during the use of the toothbrush 1.
[0077] Polyurethane can be mixed with 0.01 to 1.0 wt% (mass %) of any one of the following: saturated / unsaturated hydrocarbons with C10 or higher, 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 glycerides, liquid paraffin, and silicone, or these can be compounded and mixed together to function as a lubricant or release agent.
[0078] Furthermore, compared to the other elastomers mentioned above, polyurethane offers a wider range of selectable hardness. Depending on the thickness of the brush-formed body 20, a resin hardness that takes into account its usability (e.g., buckling at the tip of the brush-formed body) can be selected. Preferably, the hardness of the polyurethane is 90A or higher and 70D or lower on the Shore A scale.
[0079] When the hardness of polyurethane is softer than Shore 90A, it is prone to deformation when formed in a thin-walled manner, resulting in weaker interlocking and making the brush-shaped body 20 more likely to detach during use of the toothbrush 1. When the hardness of polyurethane is harder than Shore 70D, pain may occur when the tip of the head base 21 contacts oral tissues due to the tilted back surface. By making the hardness of polyurethane between Shore 90A and 70D, it is possible to prevent the brush-shaped body 20 from detaching during use of the toothbrush 1 or to suppress pain when the tip of the head base 21 contacts the toothbrush.
[0080] In addition, from the perspective of ensuring water resistance and antibacterial properties, ether-based polyurethanes are preferred as polyurethanes.
[0081] The filament 23 is a generally columnar shape protruding from the support surface 21a on the front side in the thickness direction of the head base portion 21. 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 positioned at the base end of the filament 23 in the thickness direction. Regarding the filament 23, its base end side is a generally triangular prism with a generally triangular cross-section, and its front end side is a triangular pyramid extending from the generally triangular prism and tapering to a point. As for the cross-sectional shape of the filament 23, in addition to a generally triangular shape, it can also be a generally polygonal shape such as a generally quadrilateral shape, a generally circular shape, a generally star shape, a generally scraper shape, etc. In addition to the front end being a tapered shape that tapers to a point, the filament 23 can also be a structure extending in a straight cylinder or a tapered shape that tapers to a point from the base end.
[0082] The filaments 23 are arranged along the width direction of the brush-formed body 20, with multiple columns arranged in the insertion direction such that adjacent columns are staggered by half a spacing. That is, the filaments 23 are arranged in a staggered pattern.
[0083] Figure 5 This is a view of the brushed body 20 from the rear side.
[0084] like Figure 5 As shown, the plurality of filaments 23 have a filament group (first filament group) F1 located in the center of the width direction and filament groups F2 located on both sides of the width direction of the filament group F1. As an example, the filament group F1 is higher than the filament group F2.
[0085] The maximum length of the filament 23 is preferably 7 mm or more, and more preferably 9 mm or more.
[0086] The maximum length of the filament 23 is preferably 15 mm or less, and more preferably 13 mm or less.
[0087] In addition, the maximum length of the filament 23 is preferably 7 mm or more and 15 mm or less, and more preferably 9 mm or more and 13 mm or less.
[0088] When the maximum length of filament 23 is less than 7 mm, there is a possibility of reduced cleanliness within the injection chamber. When the maximum length of filament 23 is greater than 15 mm, the release properties during injection molding of the brush molded body 20 will decrease. By ensuring that the maximum length of filament 23 is between 7 mm and 15 mm, both cleanliness within the injection chamber and release properties during molding can be guaranteed.
[0089] The cross-sectional area of the base end of filament 23 is preferably 0.8 mm. 2 Below, 0.6mm is preferred. 2 Below, the cross-sectional area at the base of filament 23 is greater than 0.8 mm². 2 At this time, the filament 23 is difficult to bend, and there is a possibility of reduced cleaning performance in the gaps between teeth, tooth necks, etc. This is addressed by making the cross-sectional area of the base end of the filament 23 0.8 mm². 2 The following ensures the cleanliness of gaps between teeth, at the neck of teeth, etc.
[0090] The ratio of the total cross-sectional area of the base ends of the plurality of filaments 23 to the area of the support surface 21a of the head base portion 21 is preferably 10% or more and 50% or less. 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 of reduced cleaning performance within the oral cavity. When the ratio of the total cross-sectional area of the base ends of the filaments 23 is greater than 50%, the demolding performance when the brush molded body 20 is formed by injection molding will be reduced. By keeping the ratio of the total cross-sectional area of the base ends of the filaments 23 to 10% or more and 50% or less, both cleaning performance within the oral cavity and demolding performance during molding can be ensured.
[0091] Filament group F1 constitutes part of a plurality of filaments 23 and is formed of a first resin composition. Filament group F2 consists of filaments 23 other than those in filament group F1 and is formed of a second resin composition different from the first resin composition.
[0092] As for the first and second resin compositions, the aforementioned soft resins can be appropriately selected considering the user experience and appearance (design) of the toothbrush 1. For example, considering both the user experience and the massage and brushing sensation of the toothbrush 1, soft resins with different hardness can be used. Furthermore, considering appearance, the aforementioned soft resin can be used as a base material, and colorants such as masterbatch can be added to make the filament group F1 and the filament group F2 different colors.
[0093] The head base portion 21 has a support platform portion 30 and a fitting hole 22.
[0094] The support platform 30 supports the base end of the filament assembly F1 from below. For example... Figure 3 As shown, the support platform 30 is a cuboid containing the filament group F1 and is rectangular in shape when viewed from the front. Figure 4As shown, the upper surface of the support platform 30 is coplanar with the support surface 21a. That is, the upper surface of the support platform 30 constitutes a part of the support surface 21a. Hereinafter, the upper surface of the support platform 30 will also be appropriately referred to as the support surface 21a.
[0095] The support platform 30 is located further towards the front side than the fitting hole 22. It forms part of the head base 21. The support platform 30 is formed of the first resin composition. The support platform 30 and the filament assembly F1 constitute a preform 40 integrally formed from the first resin composition.
[0096] The fitting hole 22 extends in the insertion direction and opens toward the end face 21b on the rear end side (one side). Figure 6 It is a cross-sectional view of the surface parallel to the support surface 21a, including the fitting hole 22. For example... Figure 6 As shown, the fitting hole 22 has: a first portion 33 opening towards the end face 21b and a second portion 34 located further inward than the first portion 33. Figure 4 As shown, the first part 33 and the second part 34 are respectively disposed separately from the back surface 21c of the head base part 21 and the back surface of the support platform part 30.
[0097] The head base portion 21 has a protrusion 35 located approximately at the center of the insertion direction in the fitting hole 22, between the first portion 33 and the second portion 34. The protrusion 35 is provided on both sides of the fitting hole 22 in the width direction. (Refer to the fitting protrusion 12 of the handle 10...) Figure 7 When inserted into the fitting hole 22 (described later), the protrusions 35 are respectively positioned to fit into the recess 15 (described later). The protrusion 35 is an arc shape with an arc center on the outer side and protruding inward in the width direction.
[0098] The shortest distance L35 between the protrusions 35 is shorter than the width L33 of the first part 33 and the width L34 of the second part 34. The amount by which the protrusion 35 protrudes inward in the width direction relative to the second part 34 is, for example, 1 mm. The amount by which the protrusion 35 protrudes relative to the second part 34 is the amount of downward cutting when the mold (slide core) of the molding fitting hole 22 is pulled out to the rear end side during the injection molding of the brush molded body 20.
[0099] In the brush-formed body 20, the head base portion 21, excluding the support platform portion 30, is formed from the second resin composition. The head base portion 21, excluding the support platform portion 30, and the filament assembly F2 constitute a base body molded body 50 integrally formed from the second resin composition. The brush-formed body 20 is a molded body integrally formed from the preformed body 40 and the base body molded body 50. In this case, by placing the preformed body 40, which is formed in one step from the first resin composition, in the mold cavity, and filling the mold cavity with the second resin composition, a secondary molding process (insert molding) is performed, thereby forming the molded body.
[0100] Return to Figure 5 In the cross-section of the head base portion 21 orthogonal to the length direction, the thickness t1 of the support platform portion 30 can be selected from 0.5 mm to 2.5 mm. The thickness t2 between the back surface of the support platform portion 30 and the front surface inside the fitting hole 22 can be selected from 0 mm to 2.5 mm. When the back surface of the support platform portion 30 and the front surface inside the fitting hole 22 are on the same horizontal plane, the thickness t2 between the back surface of the support platform portion 30 and the front surface inside the fitting hole 22 is 0 mm. That is, a structure in which the back surface of the support platform portion 30 exposes the fitting hole 22 can be selected. In this case, the side surface of the support platform portion 30 in the width direction is bonded and fixed to the base body molding body 50.
[0101] The thickness t1+t2 between the front side surface and the support surface 21a inside the fitting hole 22 can be selected from 0.5mm to 3.5mm. The length t3 in the thickness direction of the fitting hole 22 can be selected from 1.0mm to 3.0mm. The thickness t4 between the back side surface and the back surface 21c of the head base portion 21 inside the fitting hole 22 can be selected from 0.3mm to 2.0mm.
[0102] In the cross section of the head base portion 21 orthogonal to the length direction, when the cross-sectional area of the support portion 30 is S1 and the cross-sectional area of the region with thickness t1+t2 between the front side surface and the support surface 21a inside the fitting hole 22 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.
[0103] The value represented by S1 / S is preferably 0.6 or less, more preferably 0.5 or less, and even more preferably 0.4 or less.
[0104] 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 even more preferably 0.1 or more and 0.4 or less.
[0105] In the brush-formed body 20 with the fitting hole 22, the cross-sectional area S of the region defined by the thickness t1+t2 between the front side surface and the support surface 21a inside the fitting hole 22, and the cross-sectional area S1 of the support platform 30, have a significant impact on the formability of the filament 23. In multi-color molding, after the primary side is formed, the secondary side is formed by switching the movable side (or fixed side) of the mold, and thus molding is performed in the state where the primary side remains in the mold cavity. The flowable area after the secondary side becomes even smaller. Therefore, in multi-color molding, unlike single-color molding, there is a tendency for insufficient resin flow after the secondary side, making filament molding difficult. In this case, since sufficient filling speed and pressure cannot be ensured, molding defects such as underfilling or shrinkage marks are likely to occur. Specifically, when the value represented by S1 / S is greater than 0.6, molding defects of the filament 23 are likely to occur. In this embodiment, by setting the value represented by S1 / S to 0.6 or less, molding defects of the filament 23 can be suppressed. Furthermore, from the perspective of ensuring the formability of the primary support platform 30 and the filament group F1, it is preferable to set the value represented by S1 / S to 0.1 or more.
[0106] In the cross-section of the head base portion 21 orthogonal to the length direction, when the cross-sectional area of the fitting hole 22 is SV, and the cross-sectional area of the head base portion 21 including the cross-sectional area SV of the fitting hole 22 is SW, the value expressed by SV / (SW-S1) is preferably 0.1 or more in the entire area 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 even more preferably 0.3 or less. The value expressed 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 even more preferably 0.1 or more and 0.3 or less.
[0107] In molding other than the primary side, i.e., molding of the base body molded body 50, the presence of the sliding core used to form the fitting hole 22 has a significant impact on resin flow, in addition to the presence of the preformed body 40 of the previously molded primary side. If the sliding core occupies a small area, the resin flows easily within the mold cavity, and the formability of the filament 23 is improved. Conversely, if the value represented by SV / (SW-S1), which indicates the occupancy rate of the sliding core, is greater than 0.5, the resin flow is restricted during molding of the base body molded body 50, and there is a possibility of poor molding of the filament 23 (filament group F2) after the secondary side. In this embodiment, by setting the value represented by SV / (SW-S1) to 0.5 or less, poor molding of the filament 23 can be suppressed. Furthermore, from the perspective of ensuring the strength of the sliding core, it is preferable to set the value represented by SV / (SW-S1) to 0.1 or more.
[0108] When the area (projected area) of the head base portion 21 viewed from the frontal side in the thickness direction is P, and the area of the support platform portion 30 viewed from the same frontal side is P1, the value expressed by P1 / P is preferably 0.1 or more, more preferably 0.2 or more. The value expressed by P1 / P is preferably 0.5 or less, more preferably 0.4 or less. Furthermore, the value expressed 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 even more preferably 0.2 or more and 0.4 or less.
[0109] As a means to improve the formability of the filaments 23 (filament group F2) other than the primary side, the resin flow in the direction parallel to the support surface 21a is also important. In particular, the effect is significant when the gate, such as a side gate, is located at the end of the brush molded body 20 in the longitudinal direction. Therefore, when the value represented by P1 / P is greater than 0.5, the resin flow is hindered due to the occupation of the mold cavity area based on the primary side preform 40, and there is a possibility of poor forming of the filaments 23 during the forming of the base body molded body 50 after the secondary side. On the other hand, when the value represented by P1 / P is less than 0.1, there is a possibility that the occupancy rate of the filament group F1 is reduced and functionality (e.g., cleanability) cannot be ensured. In this 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, while poor forming of the filaments 23 can be suppressed.
[0110] The maximum distance (maximum thickness) between the support surface 21a and the back surface 21c of the head base portion 21, i.e., the maximum distance T from the base end of the filament 23 to the back surface 21c, is preferably 2.0 mm or more and 4.5 mm or less. When the maximum distance T is less than 2.0 mm, the gap between the support surface 21a and the support surface 21a side of the fitting hole 22, or the gap between the back surface 21c and the back surface 21c side of the fitting hole 22, becomes smaller. This reduces the fluidity of the molten resin during the molding of the base body 50, thus potentially leading to unfilled resin. Furthermore, when the maximum distance T is less than 2.0 mm, it becomes necessary to reduce the gap between the support surface 21a side of the fitting hole 22 and the support base portion 30, further reducing the fluidity of the molten resin during the molding of the base body 50. When the maximum distance T is greater than 4.5 mm, there is a possibility of reduced operability when inserting the brush shape 20 into the oral cavity. In this embodiment, by setting the maximum distance T to 2.0 mm or more and 4.5 mm or less, the filling properties of the resin and the operability when inserting the brush-shaped body 20 into the oral cavity can be ensured.
[0111] 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 in the thickness direction of the support base portion 30 is t1, the value expressed by t1 / T is preferably 0.5 or less, more preferably 0.4 or less. When the value expressed by t1 / T is greater than 0.5, in order to ensure resin flow when molding the base body molding 50 other than the primary side, the brush molding 20 becomes thicker overall, resulting in a decrease in intraoral operability. In this embodiment, by setting the value expressed by t1 / T to 0.5 or less, it has an advantageous effect on both moldability and usability when molding the base body molding 50 after the secondary side. In addition, from the perspective of ensuring the moldability of the primary side and ensuring the adhesion of the primary side support base portion 30 to the side surface of the head base portion 21, it is preferable to set the value expressed by t1 / T to 0.1 or more.
[0112] Furthermore, regarding the thickness t1 and the thickness t2 between the front side surface inside the fitting hole 22, the value expressed by t1 / (t1+t2) is preferably 0.2 or more, more preferably 0.3 or more. The value expressed by t1 / (t1+t2) is preferably 0.8 or less, more preferably 0.7 or less. Additionally, the value expressed by t1 / (t1+t2) is preferably 0.2 or more and 0.8 or less, more preferably 0.3 or more and 0.7 or less. When the value expressed by t1 / (t1+t2) is greater than 0.8, sufficient space cannot be ensured for resin flow between the back side of the primary side (the back side of the support platform 30) and the sliding core. Therefore, the resin flow becomes dependent on the side side of the support platform 30, and there is a possibility of reduced formability outside the primary side (base body molding 50). Furthermore, there is a possibility of unstable resin adhesion between the primary side support platform 30 and the secondary side base body molding 50. When the value represented by t1 / (t1+t2) is less than 0.2, there is a possibility that the formability of the primary side support platform 30 cannot be guaranteed. In this embodiment, by setting the value represented by t1 / (t1+t2) to 0.2 or more and 0.8 or less, the formability of both the primary side support platform 30 and the secondary side base body molded body 50 can be guaranteed, while the resin adhesion between the support platform 30 and the base body molded body 50 can be stabilized.
[0113] Furthermore, if the thickness t2 is 0.3 mm or more, even for specifications with a wide head, there are less likely to be problems with formability. The thickness t2 is preferably 0.5 mm or more, and more preferably 0.8 mm or more.
[0114] The number of filaments in filament group F1 is FM, and the area bonded between the support platform 30 and the base body molding body 50 is Q1 (mm²). 2 When FM / Q1 is used, the preferred value is 1.0 (pieces / mm).2 ) or less, preferably 0.8 (pieces / mm) 2 Below that. During demolding after forming, the filament 23 is stretched and detached simultaneously due to the demolding resistance on the mold cavity surface. When the value expressed by FM / Q1 is greater than 1.0 (filaments / mm) 2 In the case of multi-color molding, when the preform 40 is demolded from the base body molding body 50 after secondary molding, there is a possibility that the preform 40 may peel off from the base body molding body 50 due to the demolding resistance of the filament group F1. In this embodiment, the value represented by FM / Q1 is set to 1.0 (filaments / mm). 2 The following measures can suppress the peeling of the preform 40 from the base body 50 after secondary molding. Furthermore, if the area occupied by the support platform 30 is insufficient to adequately ensure the number of filaments F1, and considering the possibility of reduced functionality of the primary filaments F1, it is preferable to set the value represented by FM / Q1 to 0.2 (filaments / mm). 2 )above.
[0115] From the perspective of suppressing the peeling of the preform 40 from the base body molded body 50 after secondary molding, it is preferable to provide one or more uneven structures at the bonding interface between the support platform 30 and the base body molded body 50. By providing an uneven structure at the bonding interface between the support platform 30 and the base body molded body 50, it is possible to increase the bonding area and improve the adhesion of the preform 40 on the primary side while ensuring formability. The uneven structure can be configured on either the back or side of the support platform 30, but since the height and width of the uneven structure are more easily increased when configured on the back compared to the side, it is effective in increasing the bonding area. When the uneven structure is configured on the side of the support platform 30, the thickness of the support platform 30 and the undercut during molding of the preform 40 can be considered. The height (highest to lowest) of the uneven structure can be, for example, about 0.1 to 0.5 mm, and the spacing of the uneven structure can be, for example, about 0.5 to 3.0 mm.
[0116] like Figure 4 As shown, 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 expressed 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 expressed by L2 / L1 is preferably 0.70 or less, more preferably 0.60 or less, and even more preferably 0.55 or less. In addition, the value expressed 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 even more preferably 0.45 or more and 0.55 or less.
[0117] When the value represented by L2 / L1 is less than 0.30, the area of the handle 10 formed of hard resin without the interlocking protrusion 12 becomes larger, making the front of the brush-shaped body 20 more prone to bending, which may reduce its usability as a toothbrush 1. When L2 / L1 is greater than 0.70, the volume occupied by the mold (sliding core) that forms the interlocking hole 22 during molding becomes larger, and the resin flow is restricted, thus reducing the formability of the filament 23. By setting the value represented by L2 / L1 to 0.30 or more and 0.70 or less, the reduction in the formability of the filament 23 can be suppressed, and the reduction in the usability of the toothbrush 1 can also be suppressed.
[0118] [Handle 10]
[0119] Figure 7 This is a front view of the handle 10.
[0120] like Figure 7 As shown, the handle 10 includes a rod-shaped handle portion 11 and a fitting protrusion 12 located at the front end of the handle portion 11 and protruding towards the front end of the handle portion 11 in the longitudinal direction. The fitting protrusion 12 is detachably fitted into the fitting hole 22 of the brush-shaped body 20. In the toothbrush 1, the brush-shaped body 20 is covered and mounted on the fitting protrusion 12 by inserting the fitting protrusion 12 of the handle 10 into the fitting hole 22 in the brush-shaped body 20.
[0121] In this embodiment, the shape of the handle 11 changes in a curved manner from a frontal view, such that the width gradually narrows from the front end to the rear end, then extends with a constant width, and then gradually widens and narrows again. Regarding the shape of the handle 11 from a frontal view, the rear end is approximately semi-circular.
[0122] Regarding the shape of the handle 11 from a side view, as follows: Figure 2 As shown, the handle 11 extends with a constant width from the front end to the rear end, gradually widening until it reaches its maximum thickness at the finger contact area. The shape of the handle 11 in a side view varies in curve, with the width gradually narrowing towards the rear end from the finger contact area at its maximum thickness. Regarding the shape of the handle 11 in a side view, the rear end is approximately semi-circular.
[0123] Furthermore, in this invention, the shape of the handle is not limited to the shape in this example, and can be appropriately set considering factors such as strength, operability, and appearance design.
[0124] The size of the handle 11 is not particularly limited and can be set appropriately. For example, the length of the handle 11 can be set to 100-200mm.
[0125] The fitting protrusion 12 is the portion covered by the brush forming body 20 in the state where the brush forming body 20 is mounted on the handle body 10. The rear end of the fitting protrusion 12 is the position of the rear end of the brush forming body 20 in the state where the brush forming body 20 is mounted on the handle body 10.
[0126] Figure 8 is a front view magnifying the fitting protrusion 12. Figure 9 is a side view magnifying the fitting protrusion 12.
[0127] As Figure 8 shown, the fitting protrusion 12 has: a base portion 13 provided on the front end side of the handle portion 11 and a front end portion 14 provided at the front end of the base portion 13. As Figure 9 shown, the base portion 13 and the front end portion 14 have steps on both the front side and the back side with respect to the handle portion 11 and are formed with the same thickness thinner than the handle portion 11.
[0128] The base portion 13 is substantially rectangular in a plan view. The base portion 13 has steps 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 of the front end side of the handle portion 11 (L13 < L11). The front end portion 14 is substantially elliptical in a plan view with the width direction as the major axis direction. The front end portion 14 has a shape in which the side edges are cut off by straight lines parallel to the insertion direction of the fitting protrusion 12 on both sides in the width direction. The front end portion 14 has steps 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.
[0129] The fitting protrusion 12 has a recess 15 between the base portion 13 and the front end portion 14 at approximately the center in the insertion direction. The recesses 15 are provided on both sides in the width direction. The recess 15 has an arc shape that is recessed inward with the center of the arc on the outside in the width direction. The shortest distance L15 between the recesses 15 is shorter than the width L13 of the base portion 13 and the width L14 of the front end portion 14. As an example of the recess amount of the recess 15 with respect to the end edge defining the width L14 in the front end portion 14, it is 1 mm.
[0130] The handle body 10 is formed of a hard resin.
[0131] As the hard resin, as an example, resins having a flexural modulus (JIS K7171) of 1500 MPa or more and 3000 MPa or less can be exemplified. Specifically, for example, polypropylene resin (PP), polyacetal resin (POM), polyester resin (PCTA), polyethylene terephthalate copolymer (PETG), and high-density polyethylene (HDPE) can be exemplified. Among them, considering cost, PP which is a general-purpose resin is preferred.
[0132] The maximum width L21 of the rear end side (end face 21b) of the head base portion 21 is approximately the same as the maximum width of the front end side of the handle portion 11.
[0133] The shape of the fitting hole 22 in a frontal view is approximately the same as the shape of the fitting protrusion 12 in a frontal view. The width L33 of the first part 33 is the length into which the base 13 of the fitting protrusion 12 can be inserted, and is approximately the same as the maximum width L13 of the base 13. The width L34 of the second part 34 is the length into which the front end 14 of the fitting protrusion 12 can be inserted, and is approximately the same as the maximum width L14 of the front end 14. The shortest distance L35 between the protrusions 35 is the length into which the front end 14 of the fitting protrusion 12 and the recess 15 can be inserted, and is approximately the same as the shortest distance L15 between the recesses 15.
[0134] Next, refer to Figures 10-12 The sequence of forming the brush-shaped body 20 described above is explained. Figure 10 This is a cross-sectional view in the width direction of an example of the mold MD of the preform 40 in the forming brush forming body 20.
[0135] Mold MD features: can be used in the opening and closing directions ( Figure 10 The mold consists of a first mold MD1 that moves relative to each other in the vertical direction and a second mold MD2 for one-time forming. The first mold MD1 and the second mold MD2 are joined together by a parting surface PL that is on the same horizontal plane as the support surface 21a. As an example, the first mold MD1 is a fixed mold and the second mold MD2 is a movable mold.
[0136] The first mold MD1 is installed on, for example, the fixed side of the injection molding machine, and molten resin is filled from the injection molding machine. The second mold MD2 is installed on, for example, the movable side of the injection molding machine, and the mold MD is opened and closed by moving relative to the first mold MD1 in the aforementioned opening and closing direction.
[0137] The first mold MD1 has a forming surface 21aM that forms a supporting surface 21a when it is closed and engaged with the second mold MD2, a mold cavity F1M that forms filament group F1, and a mold cavity F2M that forms filament group F2. Mold cavities F1M and F2M open to the parting surface PL of the first mold MD1.
[0138] The second mold MD2 has a cavity 30M that forms a support platform 30 when the mold is closed and engaged with the first mold MD1. Cavity 30M opens into cavity F1M. Cavity 30M does not open into cavity F2M. The opening of cavity F2M is closed by the parting surface PL of the second mold MD2. A gate (not shown) is provided in cavity 30M. For example, a side gate may be used, but a pin gate or a tunnel gate may also be used.
[0139] In the aforementioned mold MD, with the first mold MD1 and the second mold MD2 closed, molten first resin composition introduced from the gate G into the mold cavity 30M and the mold cavity F1M. On the other hand, the mold cavity 30M does not open into the mold cavity F2M, and the opening of the mold cavity F2M is closed by the parting surface PL of the second mold MD2, so it is not filled with the first resin composition. Then, by cooling with the first mold MD1 and the second mold MD2 closed, a preform 40 formed of the first resin composition is formed, having a filament group F1 and a support platform portion 30.
[0140] Figure 11 This is a cross-sectional view in the width direction of an example of a mold MD used for secondary forming of the base body 50 in the forming brush forming body 20. Figure 12 This is a simplified cross-sectional view along the length of an example of a mold MD used for secondary forming.
[0141] The mold MD includes a first mold MD1 and a second mold MD12 that can move relative to each other in the opening and closing direction. The first mold MD1 is the first mold MD1 that is held in place without demolding the preform 40. It should be noted that a portion of the first mold MD1 for primary forming, which includes mold cavities F1M and F2M, can be detached and mounted on the first mold MD1 for secondary forming.
[0142] The second mold MD12 has: a mold cavity 21M of the forming head base portion 21 when the mold is closed and engaged with the first mold MD1; a gate portion G that opens to the front end of the mold cavity 21M and introduces molten resin into the mold cavity 21M; and an abutment surface 21eM that is provided at a position on the end face 21b in the insertion direction and is orthogonal to the insertion direction. Figure 11 As shown, the mold cavity F2M of the forming filament group F2 opens into the mold cavity 21M. The gate section G can be a side gate, for example, but a pin gate or tunnel gate can also be used. The abutment surface 21eM in the second mold MD2 extends from the back side of the forming head base section 21 in a direction separating from the PL surface.
[0143] In the second mold MD12, a sliding core SL is provided. The sliding core SL has: a core portion 22M for forming the fitting hole 22, and a forming surface 21bM orthogonal to the protruding insertion direction of the core portion 22M. For example... Figure 11 As shown, before mold closing, the forming surface 21bM separates from the abutment surface 21eM. Regarding the sliding core SL, when the first mold MD1 and the second mold MD12 are closed, as... Figure 11As shown, the sliding core SL is positioned such that a portion of the forming surface 21bM abuts against the abutment surface 21eM, and the core 22M is inserted into the mold cavity 21M. The area of the forming surface 21bM that does not abut against the abutment surface 21eM but faces the mold cavity 21M is the area of the forming end face 21b. Furthermore, when the first mold MD1 and the second mold MD12 open, the sliding core SL moves in the direction of disengaging from the mold cavity 21M, so that the core 22M does not obstruct the demolding of the formed brush molded body 20. The direction of movement of the sliding core SL is preferably horizontal to avoid accidental movement due to its own weight.
[0144] In the aforementioned mold MD, molten second resin composition introduced from the gate G into mold cavity 21M while the first mold MD1 and the second mold MD12 are closed fill mold cavities 21M and F2M. The second resin composition filled in mold cavity 21M covers the side and back of support platform 30 and adheres to support platform 30. Then, by cooling while the first mold MD1 and the second mold MD12 are closed, it is demolded from mold MD, thereby obtaining a molded body having a preform 40 and a base body molded body 50, and the preform 40 and the base body molded body 50 are integrally formed. The preform 40 has a filament group F1 and a support platform 30 and is formed of the first resin composition. The base body molded body 50 has a head base portion 21 and portions of a plurality of filaments 23 other than the preform 40 and is formed of the second resin composition.
[0145] That is, a brush forming body 20 is obtained by integrally forming the filament 23 and the head base portion 21 as a forming body. The filament 23 has a filament group F1 formed by a first resin composition and a filament group F2 formed by a second resin composition. The head base portion 21 includes a support platform portion 30 formed by the first resin composition and is formed by the second resin composition.
[0146] Regarding the formed brush body 20, by inserting the fitting protrusion 12 of the handle 10 into the fitting hole 22 and fitting it in place, a toothbrush 1 integrating the brush body 20 and the handle 10 can be obtained. Alternatively, by pulling the fitting protrusion 12 of the handle 10 out of the fitting hole 22, the brush body 20 can be detached from the handle 10 for replacement.
[0147] As described above, in the brush-shaped body 20 of this embodiment, since it has a filament group F1 formed by a soft resin of the first resin composition and a filament group F2 formed by a soft resin of the second resin composition, by appropriately selecting the first resin composition and the second resin composition according to the purpose, a brush-shaped body and a toothbrush that have a gentle touch and can improve the usability and appearance of the toothbrush 1 can be obtained.
[0148] [Second Embodiment of Brush-Shaped Body 20]
[0149] Next, refer to Figure 13 A second embodiment of the brush-formed body 20 will be described. In these figures, for... Figures 1-12 The same elements of the first embodiment shown are given the same symbols, and their descriptions are omitted.
[0150] In the first embodiment described above, a structure in which the preform 40 is formed from a single resin composition was illustrated. However, in the second embodiment, a structure in which multiple resin compositions are formed will be described.
[0151] Figure 13 This is a cross-sectional view of the brush-shaped body 20 in the width direction according to the second embodiment.
[0152] like Figure 13 As shown, the preform 40 of this embodiment includes: a filament group (second filament group) F3 disposed at the center in the width direction, filament groups F1 disposed on both sides of the filament group F3 in the width direction, a second support platform 31 supporting the base of the filament group F3, and a support platform 30 supporting the base of the filament group F1. The filament group F3 is formed from a third resin composition different from the first resin composition and the second resin composition. The filament groups F1 and F3 are formed from a plurality of filaments 23 arranged along the length direction of the head base 21. The third resin composition can be appropriately selected from the above-mentioned soft resins.
[0153] The second support platform 31 is formed from the third resin composition. The side and back sides of the second support platform 31 in the width direction are bonded to the support platform 30. The front side of the second support platform 31 is coplanar with the support surface 21a. The preform 40 of this embodiment is a molded body integrally formed with the filament group F3 formed from the third resin composition, the second support platform 31, the filament group F1 formed from the first resin composition, and the support platform 30.
[0154] As an example, the preform 40 can be obtained by two-color molding, in which the filament group F3 and the second support platform 31 are formed by the third resin composition in the first molding, and the filament group F1 and the support platform 30 are formed by the first resin composition in the second molding. Alternatively, it can be obtained by insert molding, in which the filament group F3 and the second support platform 31, which are provided with the third resin composition, are formed by the first resin composition.
[0155] Furthermore, the brush-shaped body 20 of this embodiment can be obtained by three-color molding. In three-color molding, the filament group F3 and the second support platform 31 are formed by the third resin composition in the first molding, the filament group F1 and the support platform 30 are formed by the first resin composition in the second molding, and the filament group F2 and the head base 21 are formed by the second resin composition in the third molding. Alternatively, it can be obtained by insert molding. In insert molding, the filament group F2 and the head base 21 are formed by the second resin composition using a mold provided with a pre-formed pre-shaped body 40.
[0156] In addition to achieving the same function / effect as the brush-shaped body 20 of the first embodiment described above, the brush-shaped body 20 with the above structure can also provide a toothbrush 1 with a variety of added value by using more types of resin compositions according to the specifications of the toothbrush 1.
[0157] [Third Embodiment of Brush-Shaped Body 20]
[0158] Next, refer to Figure 14 and Figure 15 A third embodiment of the brush-shaped body 20 will be described. In these figures, for... Figure 13 The same elements in the second embodiment shown are given the same symbols, and their descriptions are omitted.
[0159] In addition, in this embodiment, the filament group is simply referred to as the area where the filament group is disposed.
[0160] Figure 14 This is a front view of the brush-shaped body 20 according to the third embodiment. Figure 15 This is a cross-sectional view of the brush-shaped body 20 in the width direction according to the third embodiment.
[0161] like Figure 14 As shown, in this embodiment, filament groups F1 are respectively disposed on both sides of the filament group F3 in the width direction and on both sides in the length direction. The filament groups F1 are configured in an O-shape surrounding the filament group F3.
[0162] like Figure 15 As shown, the side of the second support platform 31 is bonded to the support platform 30. The second support platform 31 extends through the support platform 30 in the thickness direction. The back surface of the second support platform 31 is on the same horizontal plane as the back surface of the support platform 30.
[0163] The other structures are the same as those in the second embodiment described above.
[0164] In this embodiment, in addition to achieving the same effects as in the second embodiment described above, a toothbrush 1 with multiple added values can be provided by arranging the filaments 23 in a two-dimensional manner other than in a straight line, and by using a wider variety of resin compositions according to the specifications of the toothbrush 1.
[0165] Furthermore, the structure for the two-dimensional configuration of the filament 23 can be, for example, the following structure: Figure 16 Front view and Figure 17 The cross-sectional view along the length direction shows a structure in which the filament group F1 and the support platform 30 are arranged side by side with the filament group F3 and the second support platform 31 along the length direction.
[0166] [Fourth Embodiment of Brush-Shaped Body 20]
[0167] Next, refer to Figure 18 The fourth embodiment of the brush-shaped body 20 will be described. In this figure, for... Figures 1-12 The same elements of the first embodiment shown are given the same symbols, and their descriptions are omitted.
[0168] Figure 18 This is a cross-sectional view of the brush-shaped body 20 in the width direction according to the fourth embodiment.
[0169] like Figure 18 As shown, the filament group F1 in the preform 40 of this embodiment has all of the plurality of filaments 23.
[0170] The other structures are the same as those in the first embodiment described above.
[0171] In the brush-shaped body 20 with the above structure, similar to the first embodiment, the filament group F1 and the head base portion 21 are formed from different resin compositions, so that a brush-shaped body and a toothbrush with a soft touch can be obtained, which can improve the usability and appearance of the toothbrush 1.
[0172] In the brush-formed body 20 with the above-described structure, since the preformed body 40 has all the filaments 23, the demolding resistance of the preformed body 40 when the brush-formed body 20 is demolded from the mold is increased. Therefore, as described above, it is preferable to use at least one of the following: the relationship between the number of filaments FM and the bonding area Q1 between the support platform portion 30 and the base body forming body 50; and the uneven structure provided on the bonding interface between the support platform portion 30 and the base body forming body 50.
[0173] [Example]
[0174] The present invention is illustrated below with examples, but the present invention is not limited to the following examples and may be implemented with appropriate modifications without departing from its spirit.
[0175] (Examples 1-8, Comparative Example 1)
[0176] At least one different toothbrush from the items shown in [Table 1] was used as a sample for Examples 1 to 8 and Comparative Example 1. The resin constituting each sample was polyurethane.
[0177] [Evaluation Method]
[0178] For each sample of Examples 1-8 and Comparative Example 1, the formability of the filament, the overall brushing difficulty in the oral cavity, and the adhesion of the preform on the one-time forming side were evaluated.
[0179] (1) Evaluation method for the formability of filaments
[0180] Five brush-formed bodies formed under the same conditions were evaluated according to the following benchmarks.
[0181] 5 points: No visible defects.
[0182] 4 points: The tip of the filament deforms during demolding (due to insufficient load pressure, it bends under the action of external force during demolding).
[0183] 3 points: The thickness of the filament tip is finer than the design value.
[0184] 2 points: The length of the filament is shorter than the design value (the total length of all filaments is more than half of the total length).
[0185] 1 point: The length of the filament is shorter than the design value (there are filaments that are less than half the total length).
[0186] Then, calculate the average of the five evaluation scores and conduct an evaluation based on the following four levels.
[0187] ◎(Double circle mark): 4.5 points or above, 5.0 points or below.
[0188] ○ (circle mark): 3.5 points or higher, less than 4.5 points.
[0189] △ (triangle mark): 2.5 points or more, less than 3.5 points.
[0190] × (cross mark): less than 2.5 points.
[0191] (2) Evaluation method for the overall difficulty of oral cavity cleaning
[0192] Sensory evaluations were conducted by 10 professional judges, assessing the overall ease of brushing within the oral cavity according to the following criteria (with particular emphasis on the ease of brushing the molars).
[0193] 5 stars: Very easy to clean.
[0194] 4 points: Slightly easy to clean.
[0195] 3 points: Neither easy nor difficult.
[0196] 2 points: Slightly difficult to clean.
[0197] 1 point: Very difficult to clean.
[0198] Then, the average score from 10 professional judges is calculated, and an evaluation is conducted based on the following four levels.
[0199] ◎: 4.5 points or above, 5.0 points or below.
[0200] ○: 3.5 points or above, less than 4.5 points.
[0201] △: 2.5 points or above, less than 3.5 points.
[0202] ×: Less than 2.5 points.
[0203] (3) Evaluation method for the adhesiveness of preforms formed in one step
[0204] Five brush-formed bodies formed under the same conditions were evaluated according to the following benchmarks.
[0205] 5 points: No visible defects.
[0206] 4 points: Due to the demolding resistance during demolding, the primary side base deforms (the brush surface is no longer smooth).
[0207] 3 points: Although the peeling is not visible, it can be confirmed at the resin boundary if external force is applied.
[0208] 2 points: During demolding, part of the side base is peeled off and part is connected.
[0209] 1 point: The primary side is completely peeled off and separated from the brush-formed body (the primary side remains in the mold).
[0210] Then, calculate the average of the five evaluation scores and conduct an evaluation based on the following four levels.
[0211] ◎: 4.5 points or above, below 5.0 points.
[0212] ○: 3.5 points or above, less than 4.5 points.
[0213] △: 2.5 points or above, less than 3.5 points.
[0214] ×: Less than 2.5 points.
[0215] [Table 1]
[0216]
[0217] As shown in [Table 1], for the samples of Examples 1 to 8, where the ratio of the cross-sectional area S1 of the support platform 30 to the cross-sectional area S of the area between the front side surface and the support surface 21a located inside the fitting hole 22 (i.e., the value expressed as S1 / S) is 0.6 or less, good results were obtained in terms of filament formability, overall brushing difficulty in the oral cavity, and adhesion of the preform on the one-time forming side. In contrast, in the sample of Comparative Example 1, where the value expressed as S1 / S is greater than 0.6, a good evaluation was not obtained in terms of filament formability.
[0218] When the conditions shown in Example 1 were set, good results were obtained in terms of filament formability, overall brushing difficulty in the oral cavity, and adhesion of the primary preform.
[0219] When the conditions shown in Example 2 are set, the value represented by S1 / S increases as the primary side support platform expands. As a result, the resin flow from the secondary side onwards decreases, and the filament formability is worse than that of the sample in Example 1. In addition, the number of filaments FM in the first filament group increases with the expansion of the primary side support platform, but the bonding area Q1 of the support platform also increases. Therefore, the adhesion of the primary side preform is the same as that of the sample in Example 1.
[0220] When the conditions shown in Example 3 are set, the value represented by SV / (SW-S1) increases as the sliding core becomes thicker. As a result, the resin flow during the molding of the base body is reduced, and consequently the formability of the filaments after the secondary side is worse than that of the sample in Example 1.
[0221] In both Examples 4 and 5, the increased head thickness resulted in a lower overall brushing difficulty within the oral cavity compared to the sample in Example 1. Furthermore, because the support platform portion of the sample in Example 5 was also thicker, the value of t1 / T increased, leading to reduced resin flow during the molding of the base body compared to the sample in Example 4, resulting in poorer filament formability compared to the sample in Example 1.
[0222] Under the conditions shown in Examples 6 and 8, the increased value of t1 / (t1+t2) prevented sufficient space for resin flow between the back side of the primary support platform and the sliding core, resulting in reduced resin flow and consequently, poorer filament formability compared to the sample of Example 1. However, compared to the sample of Example 6, the sample of Example 8 did not exhibit reduced adhesion of the primary preform because the back side of the support platform did not expose the front side of the fitting hole.
[0223] When the conditions shown in Example 7 are set, the number of filaments FM in the first filament group increases compared to Example 1. However, since the bonding area Q1 of the support platform remains unchanged, FM / Q1 increases, resulting in poorer adhesion of the primary side preform compared to the sample of Example 1.
[0224] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to these examples. The various shapes and combinations of the constituent components shown in the above examples are merely examples, and various modifications can be made according to design requirements, etc., without departing from the spirit of the present invention.
[0225] For example, in the above embodiment, the toothbrush 1 is illustrated as being composed of a brush-shaped body 20 and a handle 10, which are respectively formed. The brush-shaped body 20 is mounted on the handle 10 by fitting the fitting protrusion 12 of the handle 10 into the fitting hole 22 of the brush-shaped body 20, but this structure is not limited to this one. For example, it may also be a structure in which the fitting protrusion 12 of the handle 10 is provided on a mold on which a preform is provided instead of a sliding core SL, and insert molding is performed by a second resin composition during secondary molding. Through this insert molding, a toothbrush 1 can be obtained in which the fitting protrusion 12 fits into the fitting hole 22 and the brush-shaped body 20 and the handle 10 are integrally formed.
[0226] Furthermore, in the above embodiment, a structure in which the handle 10 is formed of hard resin is illustrated, but the embodiment is not limited to this structure. For example, a structure in which a portion of the handle 10 (handle 11, etc.) is covered with soft resin may also be used. Using this structure can improve both aesthetics and grip.
[0227] [Industry availability]
[0228] This invention can be applied to brush-shaped objects and toothbrushes.
Claims
1. A brush-shaped body, characterized in that, The brush-shaped body has: a head base 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. The head base portion has a fitting hole that extends in a length direction orthogonal to the thickness direction and opens to one side in the length direction. The brush-shaped body comprises: A preform comprising: a filament assembly including at least a portion of the plurality of filaments and a support platform portion supporting the filament assembly and located further toward the front side than the fitting hole, forming part of the head base portion, and at least a portion of the preform is formed from a first resin composition. as well as A base body molded body, the base body molded body having: the head base portion and portions of the plurality of filaments excluding the preform, and the base body molded body being formed from a second resin composition different from the first resin composition. The brush-shaped body is a shaped body integrally formed from the preform and the base body. A portion of the plurality of filaments is integrally formed from the first resin composition and the support platform portion. In the cross section of the head base portion orthogonal to the length direction, when the cross-sectional area of the support platform portion is S1, and the cross-sectional area of the region between the front side surface and the support surface located inside the fitting hole is S, the value represented by S1 / S in the entire region where the fitting hole is provided is 0.1 or more and 0.6 or less.
2. The brush-formed article according to claim 1, wherein, A portion of the plurality of filaments constitutes the filament assembly formed from the first resin composition. The filaments other than the filament group among the plurality of filaments constitute the base body molded body integrally formed by the second resin composition and the head base portion.
3. The brush-formed article according to claim 1, wherein, In a cross section orthogonal to the length direction, The cross-sectional area of the fitting 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 hole is provided, the value represented by SV / (SW-S1) is 0.5 or less.
4. The brush-formed article according to claim 1 or 2, 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 platform portion viewed from the front side in the thickness direction is P1, The value represented by P1 / P is above 0.1 and below 0.
5.
5. The brush-formed article according to claim 1 or 2, wherein, The maximum distance from the base end of the filament to the back of the head base portion on the side opposite to the front side in the thickness direction is more than 2.0 mm and less than 4.5 mm.
6. The brush-formed article according to claim 5, wherein, The maximum distance from the base end of the filament to the back side of the head base portion is T. When the thickness of the support platform in the thickness direction is t1, The value represented by t1 / T is below 0.
5.
7. The brush-formed article according to claim 6, wherein, When the distance between the back side surface of the support platform and the front side surface inside the fitting hole is t2, The value represented by t1 / (t1+t2) is above 0.2 and below 0.
8.
8. The brush-formed article according to claim 1 or 2, wherein, The number of filaments in the filament group is FM. The area where the support platform is bonded to the main body of the base is Q1 (mm²). 2 )hour, The value represented by FM / Q1 is below 1.0, and the unit is roots / mm. 2 .
9. The brush-formed article according to claim 1 or 2, wherein, The bonding interface between the support platform and the base body is provided with a concave-convex structure.
10. The brush-formed article according to claim 1 or 2, 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 above 0.30 and below 0.
70.
11. The brush-formed article according to claim 1 or 2, wherein, The preform has all of the plurality of filaments.
12. The brush-formed article according to claim 1 or 2, wherein, The preform has: The filament assembly and the support platform formed from the first resin composition; and A second filament assembly formed from a third resin composition different from the first resin composition and the second resin composition, and a second support platform supporting the base of the second filament assembly.
13. The brush-formed article according to claim 1 or 2, wherein, The soft resin is polyurethane.
14. A toothbrush, characterized in that, have: The brush-formed article according to any one of claims 1 to 13, and A handle made of hard resin, having a fitting protrusion that can be easily inserted and removed from the fitting hole of the brush body.
15. A toothbrush, characterized in that, The toothbrush has the following features: The brush-formed article according to any one of claims 1 to 13, and A handle having a fitting protrusion that fits into the fitting hole of the brush-shaped body. The toothbrush is a molded body in which the brush body and the handle are integrally formed.