Toothbrush

Abstract

To provide a toothbrush capable of more surely preventing throat poking than a conventional one.SOLUTION: In a toothbrush, a handle portion 4 has a core portion 5 made of a first hard resin integrally formed with a neck portion 3, and a covering body 6 formed to cover the core portion 5 with a second hard resin having a property of low adhesion to the first hard resin, and the outer surface of the covering body 6 functions as a grip portion, the second hard resin forming the covering body 6 is a hard resin having a shrinkage rate of 1.0% or less, and the core portion 5 and the covering body 6 are configured to be separated from each other to allow the relative movement when force exceeding predetermined force is applied.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a toothbrush including a head portion in which tufts are implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion. In particular, the present invention relates to a toothbrush capable of reducing an impact when hitting the throat.

Background Art

[0002] Conventionally, as this type of toothbrush, a toothbrush for infants has been proposed in which a buffer portion formed of a thermoplastic elastomer is provided on the proximal end side of the handle portion to reduce the impact when hitting the throat (see, for example, Patent Document 1). However, since the conventional one reduces the impact by bending of the material of the elastomer, if the elastomer is hard, the cushioning effect when hitting the throat is low, and if it is too soft, the operability and cleanability during normal operation are significantly reduced, making it difficult to achieve both, and there are problems that the material is expensive and molding is difficult.

[0003] On the other hand, the present inventor has already proposed a toothbrush in which a handle portion is composed of a core material portion made of a first hard resin integrally formed with a neck portion and a covering body formed so as to cover the core material portion with a second hard resin having a low adhesion property to the first hard resin, and the outer surface of the covering body functions as a gripping portion. The core material portion and the covering body are provided with an engaging protrusion or an engaged portion that engage with each other to prevent the core material portion from moving relative to the proximal end side of the covering body. The engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts, the engaging state is released by separating from each other or the engaging protrusion breaking, and relative movement is allowed (Patent Document 2).

[0004] According to such a toothbrush, it is possible to easily achieve both a cushioning effect of impact and operability and cleanability during normal use as compared with those made of elastomer, and it is not necessary to use an expensive specific elastomer, and since the range of material selection is relatively wide, cost reduction is possible. Further, there is an advantage that it can be easily and efficiently manufactured by two-color molding or the like instead of assembling a plurality of parts.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when attempting to hold the covering and relatively move the core material part and the covering using a toothbrush having the structure described in Patent Document 2, the force at which the core material part and the covering start to relatively move varies. In the worst - case scenario, there are cases where the two do not relatively move, and it has been found that the throat - poking prevention mechanism may not function properly. Therefore, when earnestly examining the factors, the following situations were observed. After inserting the core material part and second - molding the covering, although the core material part and the covering are not joined, there are cases where the covering tightly clamps the core material part and it is difficult to relatively move the two even when a predetermined force is applied. When a predetermined force is applied to the tip of the toothbrush while holding the covering, it has been observed that depending on the magnitude of the gripping force and the gripping position, etc., it may become difficult to separate the engaging protrusion and the engaged part.

[0007] Also, in the case of a toothbrush having a protruding part described in Patent Document 2, when a substantially annular base end part is formed around the central axis in the longitudinal direction of the toothbrush at the base end of the protruding part of the toothbrush, when the base end of the toothbrush collides with a desk or the floor, if the tip of the toothbrush hits the throat, although the impact can be mitigated to some extent, there is a limit to that extent, and it has also been found that it is desirable to reduce the possibility of hitting the throat.

[0008] Therefore, in view of the above - mentioned situation, what the present invention aims to solve is to provide a toothbrush that can more reliably prevent throat - poking than conventional ones.

Means for Solving the Problem

[0009] As a result of intensive studies in view of such a situation, the present inventor has found that: (i) by using a hard resin having a shrinkage rate of 1.0% or less as the second hard resin forming the covering body, the covering body does not strongly clamp the core material portion, and it is possible to separate the two by applying a predetermined force; (ii) when the engaging protrusion and the engaged portion are configured to disengage from each other when a force exceeding a predetermined force acts, thereby allowing relative movement between the core material portion and the covering body, by providing the engaging protrusion within a region on the base end side from the position where the width of the covering body is the largest, when the user grips the covering body, the engaging portion between the engaging protrusion and the engaged portion is not gripped, or even if the hand touches the engaging portion, the gripping force applied to the portion is small, and it is possible to prevent the separation between the engaging protrusion and the engaged portion from being hindered; (iii) by projecting the protruding portion of the covering body only from a predetermined range of a part of the entire circumference of the base end edge of the core material portion, when the base end of the toothbrush collides with a desk, a floor, etc., the axial direction of the toothbrush is likely to tilt, and it becomes easier to avoid the tip of the toothbrush from going straight in the direction of the throat. Based on these findings, the present invention has been completed.

[0010] That is, the present invention includes the following inventions. (1) A toothbrush comprising a head portion in which a tuft of bristles is implanted, a neck portion continuously provided on the base end side of the head portion, and a handle portion serving as a grip continuously provided on the base end side of the neck portion, wherein the handle portion has a core material portion made of a first hard resin integrally formed with the neck portion, and a covering body formed to cover the core material portion with a second hard resin having a property of low adhesion to the first hard resin, and the outer surface of the covering body functions as a gripping portion. The second hard resin forming the covering body is a hard resin having a shrinkage rate of 1.0% or less. The core material portion and the covering body are configured to separate from each other when a force exceeding a predetermined force acts, thereby allowing the relative movement. (2) The core material part and the covering body are provided with an engaging protrusion or an engaged part that engage with each other to prevent the core material part from moving relative to the surplus space side inside the protruding part of the covering body. The engaging protrusion and the engaged part are configured such that when a force exceeding a predetermined force acts, the engaging state is disengaged by the engaging protrusion and the engaged part moving apart from each other or the engaging protrusion breaking, allowing relative movement to the surplus space side. The toothbrush according to the preceding item (1).

[0011] (3) It includes a head part where the tufts of bristles are implanted, a neck part continuously provided on the proximal end side of the head part, and a handle part serving as a grip continuously provided on the proximal end side of the neck part. The handle part has a core material part made of a first hard resin integrally formed with the neck part, and a covering body formed to cover the core material part with a second hard resin having a property of low adhesion to the first hard resin. The outer surface of the covering body functions as a gripping part. The toothbrush is The core material part and the covering body are provided with an engaging protrusion or an engaged part that engage with each other to prevent the core material part from moving relative to the proximal end side of the covering body. The engaging protrusion is provided in a region on the proximal end side from the position where the width of the covering body is the largest. The engaging protrusion and the engaged part are configured such that when a force exceeding a predetermined force acts, the engaging state is disengaged by moving apart from each other, allowing the relative movement. The toothbrush is characterized by this. (4) The outer shape of the cross-section orthogonal to the axial direction of the covering body is a horizontally long shape where the length in the width direction is larger than the length in the front-rear direction orthogonal to the width direction. The engaging protrusion is formed on the front-rear direction surface of the peripheral wall of the covering body. The toothbrush according to the preceding item (3). (5) The engaging protrusion is formed at the tip of an engaging piece having a shape formed by cutting out the peripheral wall in the region of the covering body into a substantially U-shaped inner remaining part. The toothbrush according to the preceding item (3). (6) The engaging piece is a cantilever piece with a thickness of 1 to 3 mm extending to the proximal end side in the axial direction of the covering body. The toothbrush according to the preceding item (5). (7) The toothbrush according to the preceding item (3), wherein a concave groove portion with a depth of 0.5 to 1.5 mm for engaging the engaging protrusion is provided on the outer peripheral surface of the core material portion as the engaged portion. (8) The toothbrush according to the preceding item (7), wherein the concave groove portion is a groove having a substantially triangular prism shape with inclined surfaces on the tip side and the base end side in the axial direction of the core material portion.

[0012] (9) A toothbrush comprising a head portion in which a tuft of bristles is implanted, a neck portion continuously provided on the base end side of the head portion, and a handle portion serving as a grip continuously provided on the base end side of the neck portion, wherein the handle portion includes a core material portion made of a first hard resin integrally formed with the neck portion, and a covering formed to cover the core material portion with a second hard resin having a property of low adhesion to the first hard resin, and an outer surface of the covering functions as a gripping portion. A protruding portion that protrudes further toward the base end side than the base end of the core material portion and has a surplus space inside where the core material portion does not exist is provided at the base end portion of the covering. The protruding portion protrudes only from a predetermined range of a part of the entire circumference of the base end edge of the core material portion. The pre-core material portion and the covering are configured to separate from each other when a force exceeding a predetermined force acts, and allow relative movement toward the surplus space side. (10) An engaging protrusion or an engaged portion that engages with each other and inhibits the core material portion from relatively moving toward the surplus space side inside the protruding portion of the covering is provided on the core material portion and the covering. The engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts, the engaging state is disengaged by separating from each other or the engaging protrusion breaking, and relative movement toward the surplus space side is allowed. The toothbrush according to the preceding item (9). (11) The toothbrush according to the preceding item (9) or (10), wherein the protruding portion protrudes from a predetermined range exceeding 180° of the entire circumference of the base end edge of the core material portion. (12) The toothbrush according to the preceding item (9) or (10), wherein only one point of the tip side of the protruding portion is the position that protrudes the longest in the axial direction.

Effects of the Invention

[0013] The toothbrush according to the present invention configured as described above can provide a toothbrush that can more reliably prevent gagging than conventional ones.

[0014] That is, (1) it includes a head portion where the tuft is implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion. The handle portion is composed of a core material portion made of a first hard resin integrally formed with the neck portion, and a covering formed to cover the core material portion with a second hard resin having a property of low adhesion to the first hard resin. In the toothbrush where the outer surface of the covering functions as a gripping portion, by using a hard resin having a shrinkage rate of 1.0% or less as the second hard resin forming the covering, it is possible to avoid the dimensions in the thickness direction and width direction of the covering after molding becoming smaller than the dimensions in the corresponding directions of the core material portion. Therefore, the core material portion is not strongly clamped by the covering. As a result, the relative movement between the two becomes easier. As a result, when a force exceeding a predetermined force acts on the core material portion and the covering, they separate from each other, and the core material portion and the covering can move relative to each other reliably, making it possible to more reliably prevent gagging than conventional ones.

[0015] Further, the core material portion and the covering are provided with an engaging protrusion or an engaged portion that engage with each other to inhibit the core material portion from moving relative to the surplus space side inside the protruding portion of the covering. The engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts, they separate from each other or the engaging protrusion breaks, disengaging the engaged state, and allowing relative movement to the surplus space side. In this case, since a slight gap can be formed between the outer peripheral surface of the core material portion and the inner peripheral surface of the covering, it becomes easy to adjust the force when the engaged state between the engaging protrusion and the engaged portion is disengaged without considering the influence of the frictional force between the two.

[0016] Further, it includes a head portion where the tufts are implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion. The handle portion includes a core member portion made of a first rigid resin integrally formed with the neck portion, and a covering formed to cover the core member portion with a second rigid resin having a property of low adhesion to the first rigid resin. The outer surface of the covering functions as a gripping portion, and the core member portion and the covering are provided with an engaging protrusion or an engaged portion that engage with each other to prevent the core member portion from relatively moving toward the proximal end side of the covering. The engaging protrusion and the engaged portion are configured to disengage from each other when a force exceeding a predetermined force acts, allowing the relative movement. In the toothbrush, the engaging protrusion is provided in a region on the proximal end side from the position where the width of the covering is the largest, so that when the user grips the covering, the engaging portion between the engaging protrusion and the engaged portion is not gripped, or even if the hand touches the engaging portion, the gripping force applied to the portion is small, preventing the separation between the engaging protrusion and the engaged portion from being hindered. As a result, when a force exceeding a predetermined force acts, the engaging protrusion and the engaged portion disengage from each other, and the core member portion and the covering move relative to each other reliably, making it possible to prevent gagging more reliably than before.

[0017] Further, the outer shape of the cross-section orthogonal to the axial direction of the covering is a horizontally long shape where the length in the width direction is larger than the length in the front-rear direction orthogonal to the width direction. When the engaging protrusion is formed on the front-rear direction surface of the peripheral wall of the covering, since the outer shape of the covering is horizontally long at the position where the width is the largest, when the user grips the covering, the user grips the covering on both sides in the width direction, and it is difficult for the hand to touch the covering in the front-rear direction. Therefore, even if the hand touches the engaging portion, the gripping force applied to the portion becomes smaller, making it more difficult to hinder the movement in the front-rear direction of the engaging protrusion formed on the front-rear direction surface of the peripheral wall of the covering. As a result, it is possible to further prevent the separation between the engaging protrusion and the engaged portion from being hindered.

[0018] Further, when the engaging projection is formed at the tip of an engaging piece having a shape formed from the inner remaining portion obtained by cutting out the peripheral wall within the region of the covering body in a substantially U shape, it is possible to form the engaging projection and the engaged portion on the more proximal side of the covering body in a predetermined region, that is, at a position where it is difficult for a hand to touch.

[0019] Furthermore, the engaging piece may be a cantilever piece having a thickness of 1 to 3 mm extending toward the proximal end side in the axial direction of the covering body, or a concave groove portion with a depth of 0.5 to 1.5 mm where the engaging projection engages with the outer peripheral surface of the core material portion may be provided as the engaged portion, or the concave groove portion may be a substantially triangular prism-shaped groove having inclined surfaces on the tip side and the proximal end side in the axial direction of the core material portion, respectively. By doing so, the engaging projection and the engaged portion can be easily adjusted so that the engaged state is disengaged when a force exceeding a predetermined force acts, and it becomes possible to more reliably prevent choking than before.

[0020] Also, a toothbrush comprising: a head portion in which a tuft of bristles is implanted; a neck portion continuously provided on the proximal end side of the head portion; and a handle portion serving as a handle continuously provided on the proximal end side of the neck portion, wherein the handle portion has a core material portion made of a first rigid resin integrally formed with the neck portion, and a covering body formed to cover the core material portion with a second rigid resin having a property of low adhesion to the first rigid resin, and the outer surface of the covering body functions as a gripping portion. In the toothbrush, a protruding portion is provided at the proximal end portion of the covering body, protruding further toward the proximal end side than the proximal end of the core material portion and having a surplus space where the core material portion does not exist inside. The core material portion and the covering body are configured to separate from each other when a force exceeding a predetermined force acts and allow relative movement toward the surplus space side. In this toothbrush, the protruding portion protrudes only from a predetermined range of a part of the entire circumference of the proximal end edge of the core material portion, so that when the proximal end portion of the toothbrush collides with the floor or the like due to a fall or the like, the central axis of the main body side including the core material portion is likely to tilt, and the tip of the head portion of the toothbrush is likely to face in a direction different from the direction of the throat, such as the cheek, in the oral cavity, thereby further improving the choking prevention effect.

[0021] Further, by causing the protruding portion to protrude from a predetermined range exceeding 180° of the entire circumference of the base end edge of the core material portion, or by making only one point of the leading edge side of the protruding portion the position where it protrudes the longest in the axial direction, when the base end portion of the toothbrush collides with the floor or the like, the central axis on the main body side including the core material portion is more likely to tilt reliably, and the effect of preventing throat jabbing is further improved.

[0022] In addition, the core material portion and the covering body are provided with an engaging protrusion or an engaged portion that engage with each other and inhibit the core material portion from relatively moving to the surplus space side inside the protruding portion of the covering body. When the engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts, they are separated from each other or the engaging protrusion breaks, and the engaging state is released to allow relative movement to the surplus space side, the force at the time of release of the engaging state between the engaging protrusion and the engaged portion can be easily adjusted. Combined with the fact that the tip of the head portion of the toothbrush is likely to face a direction different from the direction of the throat, such as the cheek, in the oral cavity, the effect of preventing throat jabbing is further improved.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0024] Hereinafter, the toothbrush according to the embodiment of the present invention will be described based on the accompanying drawings.

[0025] As shown in FIGS. 1 and 2, the toothbrush 1 according to the embodiment of the present invention includes a head portion 2 in which a tuft 20 is implanted, a substantially rod-shaped neck portion 3 connected to the proximal end side (rear end portion) of the head portion 2, and a handle portion 4 serving as a grip connected to the proximal end side (rear end portion) of the neck portion 3. The handle portion 4 includes a core material portion 5 integrally formed with the neck portion 3 by a first hard resin, and a hard resin having a low welding property with respect to the first hard resin, that is, a property of being separated from each other after molding without being mixed with the first hard resin during molding. And a covering body 6 formed to cover the core material portion 5 with a second hard resin, and the outer surface of the covering body 6 functions as a gripping portion.

[0026] As the first hard resin constituting the core material portion 5 and the second hard resin constituting the covering body 6, those having low weldability with each other are selected. As an index in this case, the crystallinity of the resin can be adopted. For example, crystalline resins such as polyacetal resin (POM), polyamide resin (PA), polybutylene terephthalate (PBT), and polypropylene resin (PP) are used when the other party is a crystalline resin (except for the combination of PP), or acrylonitrile-butadiene-styrene resin (ABS), polycarbonate (PC), polymethyl methacrylate resin (PMMA), etc. In the case of non-crystalline resins, they have the property of low welding to each other.

[0027] Therefore, by making either one of the first hard resin constituting the core material portion 5 and the second hard resin constituting the covering body 6 a crystalline resin and the other a crystalline resin (except for the combination of PP) or a non-crystalline resin, the first hard resin and the second cured resin do not mix during molding, and after molding, the core material portion 5 and the covering body 6 can be in a separated state from each other. It is preferable to use a crystalline resin as the first hard resin.

[0028] Note that since polypropylene resin (PP) has high weldability, it is usually difficult to make both the first and second hard resins PP even if it is a crystalline resin. When one of the first and second hard resins is PP, the other may be a crystalline resin or a non-crystalline resin other than PP.

[0029] In the combination of the first rigid resin that constitutes the core material part 5 and the second rigid resin that constitutes the coating body 6, it is appropriate to further select in consideration of the shrinkage rates of both after molding. That is, by making the shrinkage rate of the coating body 6 after molding smaller than the shrinkage rate of the core material part 5 after molding, it is possible to suppress the coating body 6 from strongly clamping the core material part 5 after molding. As a result, the force with which the coating body 6 clamps the core material part 5 is within a controllable range, the frictional force between the core material part 5 and the coating body 6 decreases, and when a force exceeding a predetermined force acts, the core material part 5 and the coating body 6 can surely move relative to each other. Further, by setting such shrinkage rates, a gap can be formed between the outer peripheral surface of the core material part 5 and the inner peripheral surface of the coating body 6 in a normal use state. When such a gap is formed, particularly when the frictional force is low, as will be described later, it is effective to provide the core material part 5 and the coating body 6 with a predetermined engaging protrusion 4a or engaged part 4b. By configuring the engaging protrusion 4a and the engaged part 4b such that their engaging state is disengaged and relative movement to the surplus space side is allowed when a force exceeding a predetermined force acts, it is possible to easily adjust the force at which the core material part 5 and the coating body 6 start relative movement. And when a force exceeding a predetermined force acts, it is possible to surely move the core material part 5 and the coating body 6 relative to each other. From the viewpoint of more surely moving the core material part 5 and the coating body 6 relative to each other, it is preferable to use a rigid resin having a shrinkage rate of 1.0% or less, more preferably 0.8% or less, for the second rigid resin that forms the coating body 6. As this shrinkage rate, a value calculated by a method based on JIS K7152-4 can be used. Further, as such a combination of the first and second rigid resins, for example, the first rigid resin is PBT and the second rigid resin is PC (shrinkage rate 0.4 to 0.6%), the first rigid resin is PBT and the second rigid resin is ABS (shrinkage rate 0.4 to 0.6%), and the like can be mentioned.

[0030] As the second curable resin constituting the covering body 6, a transparent material may be used. This "transparent" means that visible light can be transmitted. Also, even a resin in which a small amount of a substance that does not transmit visible light (for example, lame, pigment, etc.) is mixed is regarded as transparent as long as it can transmit visible light. As the transparent synthetic resin, in particular, it is preferable to use a resin whose value measured by the test method of JIS K7105 is 80% or more. If the covering body 6 is constituted of the second curable resin made of such a transparent material, the pattern provided on the outer peripheral surface of the core material portion 5 can be visually recognized through the covering body 6, and thereby the design property of the toothbrush can be improved.

[0031] As shown in FIGS. 2 to 4 and FIG. 5, the core material portion 5 and the covering body 6 are provided with an engaging protrusion 4a or an engaged portion 4b that engage with each other and inhibit the core material portion 5 from relatively moving to the proximal end side of the covering body 6. In the present embodiment, the engaging protrusion 4a or the engaged portion 4b has a structure in which they are separated from each other and the concavo-convex engagement is released. In the embodiment shown in FIGS. 1 to 4 and FIG. 5, as the engaged portion 4b, one concave groove portion 52 is formed in the outer peripheral portion near the proximal end of the core material portion 5, and at a position corresponding to the concave groove portion 52 on the inner peripheral wall of the covering body 6, a protruding piece 71 in a state of being concavo-convexly engaged (concavo-convexly fitted) with the concave groove portion 52 is formed as the engaging protrusion 4a.

[0032] When a force exceeding a predetermined force acts, such as when the user inserts the toothbrush too deep into the mouth and hits the throat, as shown in FIG. 5(b), the engaging piece 72 of the covering body 6 bends and deforms outward, and the protruding piece 71 (engaging protrusion 4a) separates from the concave groove portion 52 (engaged portion 4b) of the core material portion 5, and the engaged state is released. The main body side including the core material portion 5 relatively moves to the surplus space S1 on the proximal end side of the covering body 6 held by the user's hand, and the impact force can be mitigated.

[0033] In the present embodiment, as shown in FIG. 6(a), the axial installation position of the protruding piece 71 (engaging protrusion 4a) in the covering 6 is in a region X on the proximal end side of the position A where the width of the covering 6 is the largest in the width direction orthogonal to the axial direction, as viewed in plan from the rear side (bottom surface side), which is the side opposite to the side (front side) where the hair bundle 20 of the covering 6 is implanted. When the protruding piece 71 (engaging protrusion 4a) is provided in the region X, the widest part will be held by hand, making it difficult for the hand to reach the region X. Therefore, the engaging portion between the protruding piece 71 (engaging protrusion 4a) and the concave groove portion 52 (engaged portion 4b) is not gripped, or even if the hand touches the engaging portion, the gripping force applied to the portion is reduced. As a result, the protruding piece 71 (engaging protrusion 4a) separates from the concave groove portion 52 (engaged portion 4b) of the core member portion 5, and the engaged state is surely released.

[0034] Further, the installation position of the engaging protrusion 4a in the cross-sectional direction orthogonal to the axial direction of the covering 6 is provided on the front-rear direction plane orthogonal to the width direction of the peripheral wall of the covering 6. In the present embodiment, as shown in FIG. 6(b), the protruding piece 71 (engaging protrusion 4a) is provided on the inner surface of the rear side (bottom surface side) of the peripheral wall of the covering 6. Further, the protruding piece 71 (engaging protrusion 4a) is provided so as to protrude toward the side where the core member portion 5 exists. In the present embodiment, the protruding piece 71 is provided on the rear side surface of the peripheral wall of the covering 6, but in a modified example, it may be provided on the inner surface of the front side.

[0035] As shown in FIG. 6(c), the outer shape of the covering 6 preferably has a horizontally long shape in which the outer shape of the cross-section orthogonal to the axial direction has a length W in the width direction that is larger than the length T in the front-rear direction orthogonal to the width direction. In particular, it is preferable to have a horizontally long shape in the region Y on the tip side of the position A in the axial direction of the covering 6. By adopting such a horizontally long shape, when the user grips the covering, the covering is supported on both sides in the width direction, and it is more difficult for the fingers to touch the covering in the front-rear direction.

[0036] And since the protruding piece 71 (engaging protrusion 4a) is provided on the front-rear direction surface orthogonal to the width direction of the peripheral wall of the covering body 6, even if there is an impact on the engaging portion, the gripping force to be loaded becomes smaller, and the movement in the front-rear direction of the engaging protrusion formed on the front-rear direction surface of the peripheral wall of the covering body is more difficult to be hindered.

[0037] When the outer shape of the covering body 6 is horizontally long, in addition to the above-described action, during normal use, it is easy for the user to firmly hold the covering body 6, and also when performing a child's finishing toothbrushing and holding it with a pengrip, the neck portion 3 is thin and the handle portion 4 is thick and easy to hold as in the embodiments shown in FIGS. 1 to 4, and it can be firmly and stably polished. Further, when placed on a washstand or the like so that the front side or the rear side of the toothbrush 1 is in contact, it can be stably placed.

[0038] As shown in FIG. 6, in the present embodiment, the protruding piece 71 as the engaging protrusion 4a is formed at the tip of an engaging piece 72 having a notch shape formed from the inner remaining part obtained by cutting out the peripheral wall within the region X of the covering body 6 in a substantially U shape. Further, the engaging piece 72 is surrounded by a substantially U-shaped through groove 73 formed in the peripheral wall of the covering body 6, is continuous with the peripheral wall on the tip side in the axial direction, and is a cantilever piece extending toward the base end side in the axial direction. By making the engaging piece 72 have such a shape, the protruding piece 71 (engaging protrusion 4a) can be provided on the more base end side of the region X where the hand is less likely to touch during use. Further, since the engaging piece 72 has a cantilever structure, when a force exceeding a predetermined force acts on the protruding piece 71 provided at its tip, the engaging piece 72 bends and deforms and separates from the groove portion 52 (engaged portion 4b) of the core material portion 5, and the engagement state is released. The main body side including the core material portion 5 moves relatively to the base end side of the covering body 6 held by the user's hand. After use, the main body side including the core material portion 5 is relatively moved to the tip side of the covering body 6, the concave groove portion 52 and the protruding piece 71 are engaged with each other in a concave-convex manner, and the bent and deformed engaging piece 72 returns to its original state and can be reused. That is, since the engaged state and the non-engaged state between the protruding piece 71 and the groove portion 52 can be repeatedly formed, repeated use is possible. In the embodiments shown in FIGS. 1 to 4, since the cross-sectional shape perpendicular to the axial direction of the core material portion 5 has a substantially square shape, the core material portion 5 is prevented from relatively rotating with the central axis in the axial direction of the covering portion 7 as the rotation axis. Therefore, alignment between the protruding piece 71 and the groove portion 52 can be achieved only by relatively moving in the axial direction, and the engaged state and the non-engaged state can be easily repeatedly formed. Further, since it is also possible to intentionally form a non-engaged state, even if water droplets enter between the core material portion 5 and the covering body 6 due to washing of the toothbrush, a non-engaged state can be formed to ensure air permeability. Air permeability can also be expected due to the substantially U-shaped through groove 73 provided in the peripheral wall of the covering body 6. Further, the through groove 73 and the engaging piece 72 can also be utilized as part of the design. For example, by utilizing them as part of a design suitable for children's preferences, it is also possible to improve children's toothbrushing habits.

[0039] The thickness t of the engaging piece 72, which is a cantilever piece of the present embodiment (see Fig. 6(b)), can be set in consideration of the stress for releasing the engagement state between the engaging protrusion 4a and the engaged portion 4b. However, since it is easy to adjust so that the engagement state is disengaged when a force exceeding a predetermined force acts, it is preferably 1 to 3 mm. Also, from the same viewpoint, the axial length of the engaging piece 72 is preferably 15 to 25 mm, and the width is preferably 2 to 5 mm. It is more preferable that the product of the axial length and the width of the engaging piece 72 is 30 to 125 mm 2 is even more preferable.

[0040] The protruding piece 71 is formed into a shape corresponding to the structure of the concave groove portion 52 of the core material portion 5 included in the primary molded product during secondary molding. That is, the shape of the protruding piece 71 is determined by the structure of the concave groove portion 52 of the core material portion 5. In the present embodiment, as shown in Figs. 4 and 7, the concave groove portion 52 of the core material portion 5 is formed on the outer peripheral surface on the bottom surface side (rear side) of the base end side of the base end portion 51 of the core material portion 5. Also, the concave groove portion 52 is a groove having a substantially triangular prism shape having an inclined surface 53 on the tip side in the axial direction of the core material portion 5 and an inclined surface 54 on the base end side. Therefore, as shown in Fig. 3, the shape of the protruding piece 71 has an inclined surface on the tip side in the axial direction and an inclined surface on the base end side corresponding to the inclined surface 53 on the tip side in the axial direction and the inclined surface 54 on the base end side, respectively, and has a substantially triangular prism shape.

[0041] In the concave groove portion 52 which is the engaged portion 4b of the core material portion 5, the depth H (see Fig. 7(b)) at which the protruding piece 71 which is the engaging protrusion 4a engages can be set in consideration of the stress for releasing the engagement state between the engaging protrusion 4a and the engaged portion 4b. However, since it is easy to adjust so that the engagement state is disengaged when a force exceeding a predetermined force acts, it is preferably 0.5 to 1.5 mm. Also, as for the size of the opening portion 55 of the concave groove portion 52, the width is preferably 2 to 4 mm, and the axial length is preferably 1 to 3 mm. Further, it is preferable that the volume of the concave groove portion 52 is 1.0 to 18.0 mm 3 is preferable.

[0042] As the engaging projection 4a, in addition to the case where the projecting piece 71 formed on the covering body 6 is provided at the tip of the engaging piece 72 having a notch shape formed by cutting out the peripheral wall of the covering portion 7 in a substantially U shape, as shown in FIG. 8, as the engaging projection 4a, the engaging piece 72 formed on the covering body 6 may be provided with the projecting piece 71 at the tip portion of the engaging piece 72 having a notch shape formed between a pair of through grooves 73 along the axial direction released to the base end surface of the covering portion 7. Even in this case, the configurations of the engaging projection 4a and the engaged portion 4b can be the same as those in the embodiment shown in FIGS. 1 to 4.

[0043] In addition to the structure in which the engaging projection 4a and the engaged portion 4b are separated from each other and the concavo-convex engagement is released as described above, the engaging projection 4a may be broken and the concavo-convex engagement may be released. For example, in the modification shown in FIG. 9, as the engaged portion 4b, two concave portions 52a are formed at angular positions symmetric about the axis on the outer peripheral portion near the base end of the core material portion 5, and at two positions corresponding to the concave portion 52a on the inner peripheral wall of the covering body 6, projecting pieces 71a in a state of being concavo-convexly engaged (concavo-convexly fitted) with the concave portion 52a are formed as the engaging projection 4a.

[0044] And in such a structure, in the normal use state shown in FIG. 9(a), when a force exceeding a predetermined force such as thrusting the throat acts, as shown in FIG. 9(b), the projecting piece 71a (engaging projection 4a) of the core material portion 5 is broken, and the engagement state with the concave portion 52a (engaged portion 4b) is released, and the main body side including the core material portion 5 relatively moves to the surplus space S1 side inside the projecting portion 8 of the covering body 6 being held, and is designed to be able to relieve the impact force. The reference numeral 710 indicates a broken piece obtained by breaking the projecting piece 71a. The shape, dimensions, etc. of the engaging projection 4a and the engaged portion 4b can be set in consideration of the stress for releasing the engagement state between the engaging projection 4a and the engaged portion 4b.

[0045] In the present embodiment, as shown in FIGS. 1 to 4, the covering body 6 includes a covering portion 7 that covers the core material portion 5, and a projecting portion 8 that projects further to the base end side than the base end 5a of the core material portion 5 at the base end 7a of the covering portion 7. The projecting portion 8 has a surplus space S1 in which the core material portion 5 does not exist inside.

[0046] As shown in FIG. 2, the protruding portion 8 protrudes only from a predetermined range of a part of the entire circumference of the base end edge, which is the edge of the base end 5a of the core material portion 5. In other words, as shown in FIGS. 4 and 6, it protrudes only from a predetermined range of a part of the entire circumference of the base end edge, which is the edge of the base end 7a of the covering portion 7 of the covering body 6. Since the protruding portion 8 protrudes only from a predetermined range of a part of the entire circumference of the base end edge of the core material portion 5, when the base end portion of the toothbrush is pushed against the floor or the like as shown in FIG. 5(b), the central axis on the main body side including the core material portion 5 is more likely to tilt compared to the case where it protrudes from the entire circumference, and the tip of the head portion 2 of the toothbrush 1 is more likely to face a direction such as the cheek, which is different from the direction of the throat, inside the oral cavity.

[0047] The range where the protruding portion 8 is provided at the base end 7a of the covering portion 7 can be determined in consideration of the ease of tilting of the central axis on the main body side including the core material portion 5. However, as shown in FIGS. 2, 4, and 6, it is preferably protruded from a predetermined range exceeding 180° of the entire circumference of the base end edge (the base end edge of the covering portion 7) of the core material portion 5. By providing the protruding portion 8 in a range exceeding 180°, even when it collides with the floor or the like, damage to the protruding portion 8 can be prevented, and the central axis on the main body side including the core material portion 5 can be made more likely to tilt. Further, as the shape of the protruding portion 8, as shown in FIG. 6, among the tip sides 83 of the protruding portion 8, a shape is preferable in which only one point becomes the position B that protrudes the longest in the axial direction. By providing such a position B, the contact point with the floor or the like can be made to be one point on the tip side 83 of the protruding portion 8, so that the central axis on the main body side including the core material portion 5 can be made more likely to tilt.

[0048] In the present embodiment, at least a part of the boundary surface between the core material portion 5 and the covering body 6 is an inclined surface whose circumferential length increases toward the base end side. Thereby, when using a normal toothbrush, the covering body 6 is prevented from coming off toward the base end side.

[0049] In the embodiments shown in FIGS. 1 to 4, at least the cross-section orthogonal to the axial direction of the core member portion 5 has a substantially square shape along the axial direction, and the four corners have a predetermined R shape (see, for example, FIG. 7(c) etc.). At the base end portion 51 of the core member portion 5, the R of the two corners on the back side is small and the R of the two corners on the front side is large. On the tip side from the base end portion 51, the four corners have an R shape with substantially equal size with the size of the R on the front side of the base end portion 51. And, on the back side of the base end side 51, a portion that is substantially flat is formed. On the other hand, in the modified examples shown in FIGS. 10 and 11, at least the core member portion 5 has a substantially circular cross-section over the entire axial length in the axial direction. By making the cross-section substantially circular in this way, the area between the outer surface of the core member portion 5 and the inner surface of the covering portion 7 facing this is minimized, and in particular, the frictional force when the two are in surface contact can be reduced. Therefore, it becomes easier to adjust the magnitude of the stress at which the core member portion 5 and the covering body 6 start relative movement to the surplus space side.

[0050] Also in the modified examples shown in FIGS. 10 and 11, similar to the embodiments shown in FIGS. 1 to 4, the core member portion 5 and the covering body 6 are provided with an engaging protrusion 4a or an engaged portion 4b that engage with each other and inhibit the core member portion 5 from relatively moving to the base end side of the covering body 6. Also in the modified examples shown in FIGS. 10 and 11, as the engaged portion 4b, one recess is formed in the outer peripheral portion near the base end of the core member portion 5, and as the engaging protrusion 4a, a protruding piece 71 formed on the covering body 6 is formed at the tip of an engaging piece 72 having a notch shape formed by the inner remaining portion of a through groove 73 that cuts out the peripheral wall of the base end portion of the covering portion 7 in a substantially U shape. However, in this modified example, since the cross-section of the core member portion 5 is substantially circular, as shown in FIG. 11(b), the inner surface side of the engaging piece 72 has a curved surface corresponding to the shape of the core member portion 5. However, from the viewpoint of making it easy to adjust the force for releasing the engagement between the two, in the portion where the engaging piece 72 is formed, a plane may be formed along the axial direction on the outer peripheral surface of the core member portion 5 so that the inner surface side of the engaging piece 72 becomes a plane. In particular, in the vicinity of the portion continuous with the peripheral wall on the tip side of the engaging piece 72, it is preferable that the outer surface of the core member portion 5 and the inner surface of the corresponding engaging piece 72 are planes.

[0051] The modified examples shown in FIGS. 10 and 11 have the same configuration as the embodiments shown in FIGS. 1 to 4 except for the above points, and the description of the configuration with corresponding reference numerals in the drawings shall be referred to for the said configuration.

[0052] In the toothbrush 1 according to the embodiments shown in FIGS. 1 to 4, a primary molded product in which the head portion 2, the neck portion 3, and the core material portion 5 of the handle portion 4 of the toothbrush 1 are integrally connected is mounted on a secondary mold, and a covering body 6 which is a secondary molded product is molded. In the secondary mold, in order to enable relative movement between the core material portion 5 and the covering body 6, it is necessary to support and fix the primary molded product at two points at both ends, namely, the neck portion 3 on the tip side of the core material portion 5 and the base end side of the core material portion 5. In this case, when the second hard resin is filled into the secondary mold, warping may occur in the primary molded product due to the resin pressure. When this warping occurs, relative movement between the core material portion 5 and the covering body 6 becomes difficult. And as the length of the core material portion 5 becomes longer, the tendency for such warping to occur becomes greater. Therefore, there is a design constraint that the length of the core material portion 5 constituting the handle portion 4 which is the handle of the toothbrush 1 cannot be made longer than necessary. In such a situation with such a constraint, in the embodiment of the present invention, as described above, by setting the position where the engaging protrusion is provided as the region X, the length of the core material portion 5 is made the minimum necessary length to suppress the influence of the warping, and at the same time, the effect of preventing throat poking is improved. However, by further suppressing the influence of this warping, it becomes possible to further improve the effect of preventing throat poking. Hereinafter, in the embodiments shown in FIGS. 1 to 4, an outline of the configuration for further suppressing the influence of this warping will be described.

[0053] As shown in FIGS. 1 and 3, a concave portion 81 is provided on the outer surface on the front side (plane side) of the protruding portion 8 of the covering body 6. This concave portion 81 is formed as a result of providing an injection gate and an ejector pin in the secondary mold. By providing the injection gate of the secondary mold at a position where the core material portion 5 does not exist, the resin pressure filled around the core material portion 5 is likely to be uniform, and warping and displacement of the core material portion 5 which tend to deflect to the opposite side of the injection gate can be more suppressed.

[0054] As shown in Fig. 2, an extension portion 9 is provided on the more proximal side than the proximal end of the proximal end portion 51 of the core material portion 5, extending into the surplus space S1 without contacting the covering portion 7. The extension portion 9 is provided so as to be continuous with the proximal end portion 51 of the core material portion 5 so as to be in surface contact with the protruding portion 8 of the covering body 6 at a part of the front side (plane side). When the extension portion 9 is provided, in addition to facilitating the alignment of the core material portion 5 (primary molded product) in the secondary mold, the core material portion 5 can be more reliably supported in the secondary mold from the bottom surface side (rear side) via the extension portion 9. Also, it can be supported from the side opposite to the position of the injection gate. Thereby, since the core material portion 5 can be supported from the direction in which it is easily bent, it is effective in suppressing the warping of the core material portion 5. In the embodiments shown in Figs. 1 to 4, the front surface of the extension portion 9 is in surface contact with the inner surface facing the surplus space S1 of the protruding portion 8 of the covering body 6. That is, on the inner peripheral surface of the protruding portion 8, a stepped portion 75 having an inner peripheral surface corresponding to the shape of the front side of the extension portion 9 that continuously extends from the proximal end 7a of the covering portion 7 toward the proximal end side is formed.

[0055] Also, in the embodiments shown in Figs. 1 to 4, as described above, a U-shaped through groove 73 is formed on the bottom surface side (rear side) of the covering body 6. In order to form this through groove 73, it is necessary to provide a corresponding protrusion on the secondary mold. This protrusion will be provided on the side opposite to the position of the injection gate. Therefore, since the proximal end portion 51 of the core material portion 5 can be supported during secondary molding from the direction in which the core material portion 5 is easily bent, it is also effective in suppressing the warping of the core material portion 5.

[0056] Next, the manufacturing procedure of the toothbrush of the representative embodiment shown in Figs. 1 to 4 will be described.

[0057] First, with the primary mold for molding a primary molded product in which the core material portion 5 of the head portion 2, the neck portion 3, and the handle portion 4 of the toothbrush are integrally connected, for example, a first hard resin made of the crystallization resin as described above is filled into this primary mold to mold the primary molded product. The primary mold can adopt an efficient upper and lower split structure mold.

[0058] The injection gate of the first mold is preferably provided to open at a position other than the position that comes into contact with the covering body 6, that is, at a position other than the position corresponding to the outer peripheral surface of the core member portion 5. When the extension portion 9 is provided to protrude from the base end 5a of the core member portion 5, it is preferable to provide the injection gate to open at a position other than the position corresponding to the contact surface with the protruding portion 8 of the extension portion 9. The position of the ejector pin for demolding the first molded product from the first mold provided as necessary is also preferably provided at a position other than the position that comes into contact with the covering body 6 as described above.

[0059] In the first mold used for molding the embodiment having the extension portion 9 shown in FIGS. 1 to 4, the injection gate and the ejector pin are provided on the back side, which is the side opposite to the front side that comes into contact with the protruding portion 8 of the covering body 6 of the extension portion 9. The reference numeral 92 in FIGS. 2 and 4 is a recess formed to suppress the gate mark formed in the case of, for example, defective gate cut processing from protruding outside the outer peripheral surface of the core member portion 5 and coming into contact with a finger.

[0060] Next, after opening the first mold, with the second mold for molding the secondary molded product made of the covering body 6 clamped, the above-described second hard resin made of a cured resin having a low welding property with respect to the first hard resin is injected into this second mold to mold the secondary molded product. Here, as the second mold, in addition to the upper and lower split molds, a slide mold provided with a slide core for forming all or part of the surplus space S1 at the base end so as to be retractable in the axial direction can be used as necessary.

[0061] In this way, a toothbrush including the head portion 2 in which the tuft 20 is implanted, the neck portion 3 continuously provided with the head portion 2, and the handle portion 4 serving as a handle, and composed of a core member portion 5 made of a first hard resin integrally formed with the neck portion 3 and a covering body 6 made of a second hard resin having a low welding property with respect to the first hard resin can be easily and inexpensively manufactured by two-color molding.

[0062] By using the toothbrush as described above, the user can firmly brush the back teeth by bringing the tuft 20 of the head portion 2 into contact with the teeth while stably gripping the covering 6 located on the outer peripheral portion of the handle portion 4. Further, even when the base end of the covering 6 abuts against a desk or the floor for some reason during toothbrush use and the tip portion of the toothbrush jabs the throat, when a force exceeding a predetermined force acts, the core member portion 5 and the covering 6 surely move relative to each other, so that the impact can be surely mitigated. In particular, when the protruding portion 8 of the covering 6 protrudes only from a predetermined range of a part of the entire circumference of the base end edge of the core member portion 5, it is also possible to reduce the possibility of jabbing the throat itself. Thus, the toothbrush of the present invention can firmly brush the back teeth, and at the same time, can surely mitigate the impact when jabbing the throat or the like, and can also reduce the possibility of jabbing the throat itself, and is suitable as a toothbrush to be used, for example, when a child brushes their teeth by themselves.

[0063] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to such examples at all, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Explanation of Reference Numerals

[0064] 1 Toothbrush 2 Head portion 3 Neck portion 4 Handle portion 4a Engaging protrusion 4b Engaged portion 5 Core member portion 5a Base end 6 Covering 7 Covered portion 7a Base end 8 Protruding portion 9 Extending portion 20 Tuft 51 Base end portion 52 Concave groove portion 52a Concave portion 53, 54 Inclined surfaces 55 Opening 71, 71a Projection pieces 72 Engaging piece 73 Through groove 75 - segment part 81 - recess 83 - leading edge 92 - recess 710 - broken piece S1 - surplus space A, B positions X, Y regions Length in the W - width direction Length in the T - front - rear direction t - thickness

Claims

1. A toothbrush comprising a head portion in which tufts are implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion, wherein the handle portion has a core member portion made of a first rigid resin integrally formed with the neck portion, and a covering formed so as to cover the core member portion with a second rigid resin having a property of low adhesion to the first rigid resin, and the outer surface of the covering functions as a gripping portion, the second rigid resin forming the covering is a rigid resin having a shrinkage rate of 1.0% or less, the core member portion and the covering are configured to be separated from each other when a force exceeding a predetermined force acts thereon, and to allow the relative movement, and is characterized by a toothbrush.

2. The core member portion and the covering are provided with an engaging protrusion or an engaged portion that engage with each other and inhibit the core member portion from relatively moving to the surplus space side inside the protrusion of the covering, the engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts thereon, they are separated from each other or the engaging protrusion breaks, thereby disengaging the engaged state and allowing the relative movement to the surplus space side, according to the toothbrush of Claim 1.

3. A toothbrush comprising a head portion in which tufts are implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion, wherein the handle portion has a core member portion made of a first rigid resin integrally formed with the neck portion, and a covering formed so as to cover the core member portion with a second rigid resin having a property of low adhesion to the first rigid resin, and the outer surface of the covering functions as a gripping portion, the core member portion and the covering are provided with an engaging protrusion or an engaged portion that engage with each other and inhibit the core member portion from relatively moving to the proximal end side of the covering, the engaging protrusion is provided in a region on the proximal end side from the position where the width of the covering is the largest, the engaging protrusion and the engaged portion are configured such that when a force exceeding a predetermined force acts thereon, they are separated from each other, thereby disengaging the engaged state and allowing the relative movement, and is characterized by a toothbrush.

4. The outer shape of a cross section orthogonal to the axial direction of the covering is a horizontally long shape in which the length in the width direction is larger than the length in the front-rear direction orthogonal to the width direction, the engaging protrusion is formed on the front-rear direction surface of the peripheral wall of the covering, according to the toothbrush of Claim 3.

5. The engaging projection is formed at the tip of an engaging piece having a shape formed from the inner remaining portion obtained by cutting out the peripheral wall within the region of the covering body in a substantially U shape. The toothbrush according to claim 3.

6. The engaging piece is a cantilever piece having a thickness of 1 to 3 mm extending toward the proximal end side in the axial direction of the covering body. The toothbrush according to claim 5.

7. As the engaged portion, a concave groove portion having a depth of 0.5 to 1.5 mm with which the engaging projection engages is provided on the outer peripheral surface of the core material portion. The toothbrush according to claim 3.

8. The concave groove portion is a groove having a substantially triangular prism shape having inclined surfaces on the tip end side and the proximal end side in the axial direction of the core material portion, respectively. The toothbrush according to claim 7.

9. A toothbrush comprising a head portion in which a tuft of bristles is implanted, a neck portion connected to the proximal end side of the head portion, and a handle portion serving as a grip connected to the proximal end side of the neck portion, wherein the handle portion includes a core material portion made of a first hard resin integrally formed with the neck portion, and a covering body formed to cover the core material portion with a second hard resin having a property of low adhesion to the first hard resin, and the outer surface of the covering body functions as a gripping portion. At the proximal end portion of the covering body, a protruding portion is provided that protrudes further toward the proximal end side than the proximal end of the core material portion and has an excess space in which the core material portion does not exist inside. The protruding portion protrudes only from a predetermined range of a part of the entire circumference of the proximal end edge of the core material portion. The core material portion and the covering body are configured to separate from each other and allow relative movement toward the excess space side when a force exceeding a predetermined force acts.

10. An engaging projection or an engaged portion that engages with each other and inhibits the core material portion from relatively moving toward the excess space side inside the protruding portion of the covering body is provided on the core material portion and the covering body. The toothbrush according to claim 9, wherein the engaging projection and the engaged portion are configured such that when a force exceeding a predetermined force acts, they separate from each other or the engaging projection breaks, disengaging the engaged state, and allowing relative movement toward the excess space side.

11. The toothbrush according to claim 9 or 10, wherein the protruding portion protrudes from a predetermined range exceeding 180° of the entire circumference of the proximal end edge of the core material portion.

12. The toothbrush according to claim 89 or 10, wherein only one point on the leading edge of the protruding portion is the position that protrudes the longest in the axial direction.

Images