toothbrush

Abstract

To provide a toothbrush that can demonstrate a high impact relaxation effect, can maintain excellent operability and cleanability in normal use, can be molded easily, and can be efficiently manufactured.SOLUTION: There is provided a toothbrush in which a handle part 4 includes a core material part 5 made of a first rigid resin integrally formed with a neck part 3 and a coating body 6 formed so as to coat the core material part with a second rigid resin having low adhesion properties to the first rigid resin. There is a protrusion part 65 at a base end part of the coating body, which protrudes more to a base end side than a base end of the core material part, and has an excess space s1 where the core material part 5 does not exist inside. The core material part and the coating body are provided with an engaging protrusion part 7a and an engaged part 7b which engage with each other for inhibiting the core material part 5 from relatively moving to the excess space side inside the protrusion part side of the coating body. When force exceeding predetermined force is applied, the engagement state between the engaging protrusion part and the engaged part is released when the engaging protrusion part and the engaged part are separated from each other or the engagement protrusion part is broken, thereby permitting the relative movement to the excess space side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a toothbrush having a head portion with tufts of bristles planted therein, a neck portion connected to the base end of the head portion, and a handle portion connected to the base end of the neck portion as a handle, and particularly to a toothbrush that can absorb shock when poked against the throat. [Background technology]

[0002] One such toothbrush proposed so far is for infants, which has a cushioning section molded from a thermoplastic elastomer at the base end of the handle to cushion the impact when it hits the throat (see, for example, Patent Document 1).

[0003] However, conventional products absorb impacts by bending a material called elastomer. If the elastomer is too hard, it will not absorb the impact well when poked in the throat, and if it is too soft, it will be significantly less easy to operate and clean during normal use. It is difficult to achieve both, and there are issues such as the material being expensive and difficult to mold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-202004 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above-mentioned circumstances, the present invention aims to solve the problem of providing a toothbrush that has a high impact absorption effect, maintains good operability and cleaning properties during normal use, and is easy to mold and can be manufactured efficiently. [Means for solving the problem]

[0006] The present invention includes the following inventions. (1) A toothbrush comprising a head portion having tufts of bristles implanted therein, a neck portion connected to the base end of the head portion, and a handle portion connected to the base end of the neck portion as a handle, wherein the handle portion has a core portion made of a first hard resin formed integrally with the neck portion, and a covering body formed to cover the core portion with a second hard resin having low adhesion to the first hard resin, the outer surface of the covering body functioning as a grip, wherein the base end of the covering body has a protruding portion that protrudes further toward the base end than the base end of the core portion and has an excess space inside where the core portion is not present, and the core portion and the covering body are provided with engaging protrusions or engaged portions that engage with each other to prevent the core portion from moving relatively toward the excess space inside the protruding portion of the covering, and the engaging protrusions and engaged portions are configured to separate from each other or the engaging protrusions break when a force exceeding a predetermined force is applied, thereby disengaging and allowing relative movement toward the excess space.

[0007] (2) The toothbrush according to (1), wherein at least a portion of the boundary surface between the core portion and the covering body is an inclined surface whose perimeter increases toward the base end.

[0008] (3) The toothbrush according to (2), wherein the inclined surface is a tapered surface with an inclination angle of 5° or less. (4) The toothbrush according to any one of (1) to (3), which is manufactured using a mold with an upper and lower split structure. [Effects of the Invention]

[0009] The toothbrush of the present invention as described above is configured so that when a force exceeding a predetermined value is applied, the engaging protrusion and the engaged portion separate from each other or the engaging protrusion breaks, thereby releasing the engagement and allowing relative movement. This provides a high impact absorption effect and makes it easy to maintain good operability and cleanability during normal use.

[0010] That is, unlike conventional methods of cushioning impact by deforming an elastomer material, the impact is cushioned by releasing the engagement between the engaging protrusion and the engaged part, which causes the core part and the covering part that forms the grip to move relative to each other in the axial direction, making it easy to set the force at which the engagement is released to a desired predetermined value by structural design of the engaging protrusion and the engaged part.As a result, it is easy to achieve both the impact cushioning effect and ease of operability and cleaning during normal use.

[0011] In addition, there is no need to use expensive specific elastomers, and a relatively wide range of materials can be selected, which allows for cost reduction.Furthermore, production can be easily and efficiently performed by two-color molding, etc., rather than assembling multiple parts.

[0012] In addition, the base end of the covering body is provided with a protruding portion that protrudes further toward the base end than the base end of the core material portion and has a surplus space inside where the core material portion is not present, and is configured to allow relative movement toward the surplus space.As a result, the overall length of the toothbrush is shortened by the amount of time it retracts into the surplus space, and even if the toothbrush is held in the hand so that the base end is blocked, or if the toothbrush falls while in use and the base end hits the floor or wall, relative movement is reliably ensured along the length of the surplus space, and impact can be reliably absorbed.

[0013] Furthermore, if at least a portion of the boundary surface between the core part and the cover is an inclined surface whose perimeter increases toward the base end, a gap will form between the core part and the cover as soon as the engagement between the engaging protrusion and the engaged part is released, preventing a situation in which friction impedes relative movement. Also, even if the engagement is made obliquely with respect to the axial direction, the engagement state will be released, and impact will be mitigated.

[0014] When the inclined surface is a tapered surface with an inclination angle of 5° or less, the inclination or outer diameter of the gripping portion does not become too large, and good gripping properties can be maintained. Furthermore, when manufacturing using a mold with a vertically split structure, the molded product can be removed by opening it in only one direction, which allows for efficient manufacturing. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view showing a toothbrush according to a representative embodiment of the present invention. [Figure 2] This is a longitudinal cross section of a toothbrush. [Figure 3] FIG. [Figure 4] (a) and (b) are explanatory diagrams showing the operation of a toothbrush that also absorbs shock. [Figure 5] This is an explanatory diagram showing how a toothbrush absorbs shock. [Figure 6] 10A and 10B are explanatory diagrams showing modified examples of an engaging protrusion and an engaged portion. [Figure 7] 10A and 10B are explanatory views showing other modified examples of the engaging protrusion and the engaged portion. [Figure 8] FIG. 10 is an explanatory view showing still another modified example of the engaging protrusion and the engaged portion. [Figure 9] FIG. 10 is an explanatory diagram showing a modified example of the toothbrush of the present invention. [Figure 10] FIG. 10 is a longitudinal cross-sectional view of the toothbrush according to the same modified example. [Figure 11] AA and BB cross-sectional views of the same modified toothbrush. [Figure 12] 10 is an explanatory diagram showing another modified example of the toothbrush of the present invention. [Figure 13] 10(a) and 10(b) are explanatory views showing still another modified example of the toothbrush of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0017] 1 and 2, the toothbrush 1 of the present invention comprises a head portion 2 having bristle bundles 20 implanted therein, a generally rod-shaped neck portion 3 connected to the base end (rear end) of the head portion 2, and a handle portion 4 connected to the base end (rear end) of the neck portion and serving as a handle. The handle portion 4 comprises a core portion 5 formed integrally with the neck portion 3 from a first hard resin such as polyacetal resin (POM), and a covering 6 formed to cover the core portion 5 with a second hard resin having low weldability with the first hard resin, i.e., a hard resin having the property of not mixing with the first hard resin during molding and remaining separate from the first hard resin after molding, and the outer surface of the covering 6 functions as a grip.

[0018] For example, crystallized resins such as polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate (PBT), or polypropylene resin (PP) have low adhesion properties when used with other crystallized resins (excluding PP-PP combinations) or non-crystallized resins.

[0019] Therefore, by making either the first hard resin constituting the core material portion 5 or the second hard resin constituting the coating 6 a crystalline resin such as polyacetal resin (POM), and the other a non-crystalline resin such as acrylonitrile butadiene styrene resin (ABS), polycarbonate (PC), or acrylic resin (PMMA), the first hard resin and the second hardened resin do not mix during molding, and the core material portion 5 and the coating 6 can be separated from each other after molding.

[0020] Furthermore, among the above-mentioned crystallized resins, polypropylene resin (PP) has a high weldability to itself, so even if both the first hard resin and the second hard resin are crystallized resins, except for those in which both the first hard resin and the second hard resin are formed from polypropylene resin (PP), it is possible to prevent the core material part 5 and the covering body 6 from fusing together.

[0021] Therefore, for example, by making one of the first hard resin constituting the core material portion 5 and the second hard resin constituting the coating 6 a crystallizable resin such as polyacetal resin (POM), and the other a crystallizable resin made of polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate (PBT), polypropylene resin (PP), or the like, it is possible to prevent the first hard resin and the second hardened resin from mixing during molding, and to keep the core material portion 5 and the coating 6 separated from each other after molding, as in the above case.

[0022] 1 to 3, the core part 5 and the covering body 6 are provided with engaging protrusions 7a or engaged parts 7b that engage with each other to inhibit the core part 5 from moving relatively toward the base end side of the covering body 6. In this embodiment, as the engaged parts 7b, two recesses 50 are formed on the outer periphery near the base end (outer periphery near the rear end) of the core part 5 at angular positions that are symmetrical about the axis, and at two positions on the inner circumferential wall of the covering body 6 that correspond to the recesses 50, protruding pieces 61 are formed as engaging protrusions 7a that are engaged with (fitted into) the recesses 50.

[0023] In the region of the base end (rear end) of the covering body 6, a protruding portion 65 is provided that protrudes further toward the base end than the base end 5d of the core portion 5 and has an excess space s1 inside which the core portion 5 is not present. The base end 65b (rear end) of the protruding portion 65 may be open, or may be configured to be closed as in the example shown in Fig. 12 described later.

[0024] When a force exceeding a predetermined value (which can be set to an appropriate magnitude, such as 2 kgf) is applied, such as when the user places the toothbrush too far back in their mouth and pokes their throat, the protruding piece 61 (engaging protruding portion 7a) of the core portion 5 breaks, disengaging from the recessed portion 50 (engaged portion 7b), and the main body including the core portion 5 moves relatively toward the surplus space s1 inside the protruding portion 65 of the gripped cover 6, thereby absorbing the impact force, as shown in Figures 4 and 5. Reference numeral 610 denotes a broken piece formed when the protruding piece 61 breaks off.

[0025] Figure 4(a) shows that even when the base end 1d hits a floor or wall, the main body moves relative to the base end by the axial length of the excess space s1, shortening the overall length of the toothbrush and allowing the toothbrush to absorb the impact. Figure 4(b) shows that when the toothbrush is farther away from the floor or wall, the main body moves further relative to the base end, allowing the toothbrush to absorb the impact.

[0026] In this embodiment, as shown in Figures 1 to 3, at least a portion of the boundary surface 40 between the core material portion 5 and the covering body 6 (area R1) is an inclined surface whose circumference increases toward the base end, thereby preventing the covering body 6 from slipping off toward the base end during normal tooth brushing, for example.

[0027] Providing an inclined surface on the boundary surface 40 in this manner has another effect. That is, due to the presence of such an inclined surface, as shown in Fig. 4, a gap 41 is formed between the core portion 5 and the cover 6 as soon as the engagement between the protrusions and recesses is released and the main body side including the core portion 5 begins to move relative to the base end side of the cover 6. Therefore, it is possible to avoid a situation where friction occurs between the core portion 5 and the cover 6 even after the engagement between the protrusions and recesses is released, which reduces movement and reduces the impact absorbing effect.

[0028] Furthermore, even if the engaging protrusion 7a is thrust in an oblique direction relative to the axis, if a tapered surface like that of this example is formed, a force acts on at least one of the engaging protrusions 7a in a direction perpendicular to the protrusion direction, making it prone to breakage as expected, and when one of them breaks, a force acts on the others, making them prone to breakage. However, if the inclination angle of the inclined surface is too large, the inclination or outer diameter of the gripping portion becomes large, deteriorating gripping properties, so it is preferable to have a tapered surface with an inclination angle of 5° or less.

[0029] In this example, the region R1 of the boundary surface 40 that is distal to the positions of the engaging protrusion 7a and the engaged portion 7b is configured as a tapered surface that is inclined at a substantially constant angle, while the region R2 that is proximal to these positions is configured as a straight surface with no inclination. That is, the region of the outer peripheral surface of the core portion 5 that is distal to the recess 50 is a tapered surface, and the region on the proximal side is a straight surface, and the region of the inner peripheral surface of the covering body 6 that is distal to the protrusion 61 is a tapered surface, and the region on the proximal side is a straight surface.

[0030] The region on the base end side of the covering body 6 is the region through which the recess 50 with the broken protrusion 61 stored inside passes during the relative movement; if this portion were a tapered surface, the broken fragments 610 of the broken protrusion 61 would come out of the recess 50 and become caught in the resulting gap, which could impede the relative movement. However, by making this a straight surface (or a tapered surface with a relatively small inclination angle) as in this example, the occurrence of a gap is eliminated (or suppressed), and the broken fragments 610 are prevented from becoming caught.

[0031] The engaging protrusion 7a and the engaged portion 7b may be a combination other than the above-mentioned protrusion 61 on the cover 6 side and the recess 50 on the core portion 5 side. As shown in Fig. 6, the engaging protrusion 7a may be provided with a protrusion 51 on the core portion 5 side, and the engaged portion 7b may be provided with a recess 60 on the cover 6 side. Reference numeral 510 denotes a broken piece formed when the protrusion 51 is broken off.

[0032] 1 to 4, the protrusion 61 and recess 50 are formed in the middle of the cover 6 and the core 5, respectively, but it is also preferable to provide the engaging protrusion 7a or engaged portion 7b on the core 5 at the base end 5d as shown in FIG. 7. By providing them at the base end 5d, the broken pieces of the protrusion 61 described above will not get caught. FIG. 7(a) shows an example in which a notch groove 54 is provided at the base end of the core 5 to engage with the protrusion 61 on the cover 6 side.

[0033] 7(b) shows an example in which the engaged portion 7b for the protruding piece 61 on the cover 6 side does not have a recess, but is structured to engage with the outer peripheral edge portion 52 of the base end surface (rear end surface) of the core portion 5. However, in this case, it is preferable to separately form a concave-convex engaging structure at the boundary surface between the core portion 5 and the cover 6 that engages in the circumferential direction while allowing relative movement in the axial direction so that the core portion 5 and the cover 6 do not rotate relative to each other in the circumferential direction around the axis.

[0034] The engaging protrusion 7a and the engaged portion 7b illustrated above are examples in which the engaging protrusion 7a bends to release the concave-convex engagement, but they may also be configured so that the engaging protrusion 7a or the engaged portion 7b separate from each other to release the concave-convex engagement. For example, in Figure 8(a), a protruding piece 61 formed on the cover 6 as the engaging protrusion 7a has an L-shaped structure formed between a pair of axial through grooves 62 that open on the base end face of the cover 6.

[0035] With this structure, when a force exceeding a predetermined value is applied, such as a poke to the throat, as shown in Figure 8(c), the protrusion 61 (engaging protrusion 7a) of the cover 6 bends and deforms outward and moves away from the notched groove 54 (engaged portion 7b) of the core portion 5, releasing the engagement state, and the main body side including the core portion 5 moves relative to the surplus space s1 on the base end side of the cover 6 held by the user's hand, thereby absorbing the impact force.

[0036] Furthermore, as shown in Figure 8(b), one or more axial through grooves 63 that open to the base end surface of the cover 6 may be provided at a position different from the protrusion 61, so that when a force exceeding a predetermined value is applied, such as when the throat is poked, the entire base end of the cover 6 including the protrusion 61 deforms and bulges outward, and similarly the protrusion 61 (engaging protrusion 7a) moves away from the recess 50 (engaged portion 7b) of the core portion 5, the engagement state is released, and the main body side including the core portion 5 moves relatively to the surplus space s1 on the base end side of the cover 6 held by hand, thereby absorbing the impact force.

[0037] 9 to 11, it is also preferable to provide alternate circumferential through-grooves 66, 67 that allow for removal of the secondary mold portion for forming the excess space s1 at the top and bottom of the protrusion 65, which has the excess space s1 on the base end side of the covering 6, for easier molding. This structure allows for efficient molding using a mold with a split upper and lower structure having a plate-like core portion that can be retracted vertically through the through-grooves 66 / 67, and also improves the breathability of the excess space s1. Furthermore, by providing the through-grooves 66, 67 through which the plate-like core portion can be removed, a covering 6 having the excess space s1 and a blocking wall 68 at the base end can also be easily molded using the above-mentioned split upper and lower structure mold, as shown in FIG. 12.

[0038] 13, it is also preferable to further provide a narrow diameter section 53 at the tip of the handle 4 that allows the neck 3 to swing relatively in a direction perpendicular to the axial direction. This allows the head 2 to swing together with the neck 3 when stabbing the throat, further mitigating the impact. In addition, since this is a structural movable mechanism using hard resin, as opposed to conventional elastomers that move due to the bending of the material itself, there is a high degree of freedom in design without compromising ease of cleaning or operability.

[0039] In this example, the tip portion of the core is configured to be bendable and deformable as a thin-diameter portion 53 whose cross-sectional area is relatively smaller than that of the front and rear, and a through groove 64 that is open on the tip side is provided to allow bending of the neck portion 3 at the tip portion of the corresponding cover 6 in the desired direction of swing without interfering with the bent thin-diameter portion. In this example, through grooves 64 are provided on the protruding direction (ventral side) and back side (dorsal side) of the bristle bundle 20 of the head portion 2, respectively, so that the neck portion 3 can swing in these two directions.

[0040] A gap s2 is formed between the small diameter portion 53 and the portion of the covering body 6 other than the through groove 64, but because of the presence of the through groove 64, such gap s2 can be formed without any problems using a secondary mold with an upper and lower split structure during two-color molding. The small diameter portion 53 is formed in a straight cylindrical shape, but is not limited to this and various structures are possible.

[0041] Next, a manufacturing procedure for the toothbrush of the representative embodiment shown in FIGS. 1 to 3 will be described.

[0042] First, a primary mold for molding a primary molded product 11 (see FIG. 3) in which the toothbrush head portion 2, neck portion 3, and core portion 5 of the handle portion 4 are integrally connected is clamped, and a first hard resin made of a crystallizable resin such as polyacetal resin (POM) is injected into the primary mold to mold the primary molded product 11. A mold with an efficient upper and lower split structure can be used as the primary mold.

[0043] Next, after the primary mold is opened, a secondary mold for molding the secondary molded article 12 made of the covering body 6 is clamped, and a second hard resin made of a cured resin having low adhesion to the first hard resin, such as an amorphous resin made of acrylonitrile butadiene styrene resin (ABS), polycarbonate (PC), or acrylic resin (PMMA), or a crystallizable resin such as polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate (PBT), or polypropylene resin (PP), is injected into the secondary mold to mold the secondary molded article 12. Here, the secondary mold can be a slide mold having upper and lower split molds and a generally columnar slide core that can be retracted in the axial direction to form the surplus space s1 at the base end.

[0044] In this way, a toothbrush can be molded in which the core 5 of the primary molded product 11 made of a first hard resin is covered with the covering 6 made of a second hard resin. Note that a transparent material may be used as the second cured resin that constitutes the covering 6. "Transparent" here means that it can transmit visible light. Furthermore, even if a resin contains a small amount of a substance that does not transmit visible light (e.g., glitter, pigment, etc.), it can still be considered transparent as long as it can transmit visible light.

[0045] It is particularly preferable to use a transparent synthetic resin having a transparency of 80% or more as measured by the test method of JIS K 7105. If the covering 6 is made of such a transparent second cured resin, the pattern provided on the outer surface of the core portion 5 can be seen through the covering 6, thereby improving the design of the toothbrush.

[0046] In this way, a toothbrush can be easily and inexpensively manufactured by two-color molding, which includes a head portion 2 having bristle bundles 20 implanted therein, a neck portion 3 connected to the head portion 2, and a handle portion 4 serving as a handle, with the handle portion 4 being composed of a core portion 5 made of a first hard resin formed integrally with the neck portion 3, and a covering 6 made of a second hard resin that has low weldability with respect to the first hard resin. Because the core portion 5 of the primary molded product 11 and the covering 6 of the secondary molded product 12 that make up the handle portion 4 of the toothbrush are made of hard resins that have low weldability with each other, even though the toothbrush, which combines the primary molded product 11 and the secondary molded product 12, is formed by two-color molding, the core portion 5 and the covering 6 are prevented from fusing to each other.

[0047] The toothbrush user can brush their teeth by firmly gripping the cover 6 located on the outer periphery of the handle 4 and bringing the bristle bundles 20 of the head 2 into contact with their teeth. Furthermore, by selecting two types of hard resin that are less expensive than elastomers, rather than using soft resins such as expensive elastomers as in the past, the toothbrush can be manufactured inexpensively.

[0048] In place of the above-described embodiment in which the toothbrush is formed by two-color molding, consisting of the primary molded product 11 and the secondary molded product 12, it is also possible to form a molded product in which the toothbrush head 2, neck 3, and core 5 are integrally connected using a first cured resin, and a molded product in which the cover 6 is formed using a second cured resin, separately by injection molding or other means, and then join these together using the concave-convex engagement structure. However, in this case, the manufacturing process becomes complicated and the manufacturing costs inevitably increase, so it is preferable to inexpensively manufacture a toothbrush in which the core 5 and cover 6 are integrally formed using the above-described two-color molding method.

[0049] Although the embodiments of the present invention have been described above, the present invention is not limited to these examples, and it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention. [Explanation of symbols]

[0050] 1 toothbrush 1d proximal end 2 Head 3 Neck 4 Handle 5 Core part 5d proximal end 6 Covering 7a Engagement protrusion 7b Engaged part 11 Primary molded product 12 Secondary molded product 20 hair bundles 40 Boundary 41 Gap 50 recess 51 Projection piece 52 outer edge 53 Thin section 54 Notched groove 60 recess 61 Projection piece 62 Through groove 63 Through groove 64 Through groove 65 Protrusion 65b proximal end 66, 67 Through groove 68 Blocking wall 510, 610 fragments R1, R2 area s1 surplus space s2 gap

Claims

1. A head portion having hair bundles implanted therein; a neck portion connected to a base end side of the head portion; a handle portion that serves as a handle and is connected to the base end side of the neck portion, The handle portion is a core portion made of a first hard resin formed integrally with the neck portion; a covering body formed so as to cover the outer peripheral surface of the core portion with a second hard resin having low adhesion to the first hard resin in a facing state without leaving any excess space; A toothbrush in which the outer surface of the covering body functions as a grip, At least a part of the boundary surface between the core portion and the covering body is an inclined surface whose circumferential length increases toward the base end, a protruding portion at a base end of the covering body, the protruding portion protruding further toward the base end side than the base end of the core portion and having an excess space inside where the core portion is not present; The core portion and the covering body are provided with an engaging protrusion or an engaged portion that engages with each other to inhibit the core portion from moving relatively toward the excess space inside the protrusion of the covering body, This toothbrush is characterized in that, when a force exceeding a predetermined force is applied, the engaging protrusion and the engaged portion separate from each other or the engaging protrusion breaks, thereby disengaging the engagement and allowing relative movement toward the excess space.

2. 2. The toothbrush according to claim 1, wherein the inclined surface is a tapered surface with an inclination angle of 5 degrees or less.

3. 3. The toothbrush according to claim 1, which is manufactured using a mold having an upper and lower split structure.

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