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 5 with a second rigid resin having low adhesion properties low in weldability to the first rigid resin, an external surface of the coating body 6 functioning as a grip part. The core material part 5 and the coating body 6 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 a base end side of the coating body 6. When force exceeding predetermined force is applied, the engagement state between the engaging protrusion part 7a and the engaged part 7b is released when the engaging protrusion part and the engaged part are separated from each other or the engaging protrusion part is broken, thereby permitting the relative movement.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 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 relative to the base end of the covering body, and wherein 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 the relative movement.

[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] Furthermore, if at least a portion of the boundary surface between the core and the cover is an inclined surface whose perimeter increases toward the base end, a gap will form between the core and the cover as soon as the engaging protrusion and the engaged portion disengage, preventing friction from impeding relative movement. Even if the protrusion is thrust obliquely toward the axial direction, the engagement will be released, mitigating the impact. Furthermore, since such an inclined surface prevents reverse movement, even if the core protrudes toward the base end of the cover, if the core is pushed against the floor or wall during a fall and attempts to move toward the tip, the movement will be prevented, more reliably preventing throat thrusts.

[0013] 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]

[0014] [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] 10(a) and 10(b) are explanatory views showing modified examples of the toothbrush of the present invention. [Figure 10] 10A and 10B are explanatory diagrams showing the operation of cushioning the impact of the toothbrush according to the modified example. [Figure 11] 10(a) and 10(b) are explanatory views showing another modified example of the toothbrush of the present invention. [Figure 12] 10A and 10B are explanatory diagrams showing the operation of cushioning the impact of the toothbrush according to another modified example. [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

[0015] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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 relative movement of the core part 5 toward the base end side of the covering body 6. In this embodiment, as the engaged parts 7b, two notched grooves 50 that are open to the base end side are formed in the outer periphery of the base end (outer periphery of the rear end) of the core part 5 at angular positions that are symmetrical about the axis, and protruding pieces 61 that are engaged with (fit into) the notched grooves 50 as engaging protrusions 7a are formed at two positions corresponding to the notched grooves 50 in the inner periphery of the base end (inner periphery of the rear end) of the covering body 6.

[0022] 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 notched groove 50 (engaged portion 7b), and the main body side including the core portion 5 moves relatively toward the base end side 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.

[0023] In this embodiment, as shown in Figures 1 to 3, at least a portion of the interface 40 between the core part 5 and the covering body 6 is an inclined surface whose perimeter increases toward the base end, thereby preventing the covering body 6 from slipping off toward the base end during normal tooth brushing, etc. In this example, the entire interface 40 is configured as a tapered surface that is inclined at a substantially constant angle. In other words, the outer peripheral surface of the core part 5 and the inner peripheral surface of the covering body 6 are tapered surfaces.

[0024] 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.

[0025] 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.

[0026] The engaging protrusion 7a and the engaged portion 7b may be a combination other than the above-described protrusion 61 on the cover 6 side and the notch groove 50 on the core portion 5 side. In this example, the protrusion 61 and the notch groove 50 are formed on the edge portions of the base end (rear end) of the cover 6 and the core portion 5, respectively, but although not shown, the protrusion 61 and the recessed portion may be provided at a position recessed into the tip side (front side). In this case, however, there is a possibility that the broken protrusion 61 may get caught between the cover 6 and the core portion 5, causing resistance between them, so it is preferable to form the protrusion 61 on the edge portion of the base end as in the above example.

[0027] 6, a protrusion 51 may be provided on the core portion 5 side as the engaging protrusion 7a, and a recess 60 may be provided on the sheath 6 side as the engaged portion 7b. Reference numeral 510 denotes a broken piece formed when the protrusion 51 is broken off. Furthermore, the engaged portion 7b for the protrusion 61 on the sheath 6 side may be structured to engage with the outer peripheral edge portion 52 of the base end surface (rear end surface) of the core portion 5, as shown in FIG. 7, without providing a recess. In this case, however, it is preferable to separately form a concave-convex engaging structure at the boundary between the core portion 5 and the sheath 6, which engages in the circumferential direction while allowing relative movement in the axial direction, so as to prevent relative rotation of the core portion 5 and the sheath 6 in the circumferential direction around the axis.

[0028] 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.

[0029] 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 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 relative to the base end side of the cover 6 held by the user's hand, thereby absorbing the impact force.

[0030] Furthermore, as shown in Figure 8(b), one or more axial through grooves 63 that open on 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 notched groove 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 toward the base end side of the cover 6 being held by hand, thereby absorbing the impact force.

[0031] In the above example, the base end surface (rear end surface) of the core portion 5 and the base end surface (rear end surface) of the cover 6 are configured to be substantially flush with each other, but the present invention is not limited to this. For example, as shown in Fig. 9, the base end of the core portion 5 may be configured to protrude from the base end of the cover 6 in a normal state. In this case, as in the above example, when a force exceeding a predetermined force is applied, such as a poke to the throat, the protruding piece 61 (engaging protrusion 7a) breaks as shown in Fig. 10, and the engagement with the notched groove 50 (engaged portion 7b) is released, and the main body side including the core portion 5 moves relatively toward the base end side of the cover 6 being held by hand, thereby absorbing the impact force.

[0032] In this example, the boundary surface also has the above-mentioned inclined surface (tapered surface), which similarly prevents reverse movement. Therefore, in the case of a structure in which the core portion 5 protrudes toward the base end of the covering body 6 as in this example, even if the user falls and the base end of the core portion 5 is pushed against the floor or wall, causing it to move toward the tip end, this movement is prevented, preventing it from being thrust into the throat.

[0033] Furthermore, in a structure in which the core material portion 5 protrudes toward the base end of the covering body 6 as in this example, the outer diameter of the covering body 6 becomes small, which may make it difficult to grip. However, as shown in Figures 11 and 12, the thickness of the covering body 6 and the shape of the outer surface can be freely set, and therefore, the thickness and shape can be appropriately set to make it easy to grip, without being affected by the inclined surface of the boundary surface.

[0034] 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.

[0035] 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.

[0036] A gap s1 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 s1 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.

[0037] Next, a manufacturing procedure for the toothbrush of the representative embodiment shown in FIGS. 1 to 3 will be described.

[0038] 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.

[0039] 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 hardened 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 crystalline resin such as polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate (PBT), or polypropylene resin (PP), is injected into the secondary mold to form the secondary molded article 12. A mold with an equally efficient upper and lower split structure can also be used for the secondary mold.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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]

[0046] 1 toothbrush 2 Head 3 Neck 4 Handle 5 Core part 6 Covering 7a Engagement protrusion 7b Engaged part 11 Primary molded product 12 Secondary molded product 20 hair bundles 40 Boundary 41 Gap 50 Notched groove 51 Projection piece 52 outer edge 53 Thin section 60 recess 61 Projection piece 62 Through groove 63 Through groove 64 Through groove 510, 610 fragments s1 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, 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 base end side 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 and allowing the relative movement.

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.

Images