Toothbrush

Abstract

The toothbrush comprises a grip portion having a length along its centerline, a neck extending from the front end of the grip portion, and a head disposed on the side of the neck opposite to the grip portion, and a brush head formed by multiple bristle tufts implanted in the head. The toothbrush body has a base component made of hard resin, comprising the grip portion body, the neck, and the head, and a foamed body made of soft resin disposed on the surface of the grip portion body. The foamed body has a filling portion and multiple void portions, and the storage modulus of elasticity of the foamed body is 10. 4 Pa or higher and 10 6.5 Below Pa.

Description

Technical Field

[0001] This invention relates to toothbrushes.

[0002] This application claims priority based on Japanese Patent Application No. 2020-214656, filed on December 24, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] Typically, a toothbrush has a toothbrush body comprising a rod-shaped grip, a neck extending from the front end of the grip, and a head located at the front end of the neck, and multiple bristles embedded in the head. The toothbrush body is made of hard resin to prevent excessive bending of the grip during brushing, allowing sufficient force to be applied to the teeth from the bristles.

[0004] However, in toothbrushes where the body is made solely of hard resin, the grip is rigid and difficult to bend, resulting in poor handling. Consequently, there is a risk of accidental brushing during brushing, which could damage the oral cavity.

[0005] Therefore, as a toothbrush that improves grip when held by hand, a toothbrush has been proposed that has a grip portion in which the surface of a rod-shaped core formed of hard resin is partially or entirely covered with soft resin (for example, Patent Document 1). In addition, a toothbrush with a structure in which soft resin and hard resin are exposed on the surface of the grip portion has been proposed (for example, Patent Document 2).

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] Patent Document 1: JP 2017-000407

[0009] Patent Document 2: International Publication No. 2016-208333 Summary of the Invention

[0010] [The problem the invention aims to solve]

[0011] However, in the case of a structure like that in Patent Document 1, the hardness of the soft resin used is limited, and in order to ensure sufficient grip, the soft resin needs to be designed to be relatively thick. Furthermore, in the case of a structure like that in Patent Document 2, although a resin with higher softness can be used, the design needs to consider factors such as the ratio of hard resin to soft resin in the grip area.

[0012] Therefore, a structure that is unconstrained in design and can improve grip is desired.

[0013] The present invention was made in view of the above-mentioned problems, and its object is to provide a toothbrush that is unrestricted in design and can improve grip.

[0014] [Methods used to solve problems]

[0015] According to one aspect of the present invention, a toothbrush comprises a toothbrush body and a brush portion. The toothbrush body has: a grip portion having a length along a central line; a neck extending from the front end of the grip portion; and a head disposed on the neck portion on a side opposite to the grip portion. The brush portion is formed by a plurality of bristle tufts implanted in the head. The toothbrush body also includes: a base member having a grip portion body, the neck portion, and the head portion, and formed of hard resin; and a foamed body disposed on the surface of the grip portion body and formed of soft resin. The foamed body has a filling portion and a plurality of void portions, and the storage modulus of elasticity G' of the foamed body is 10. 4 Pa or above, 10 6.5 Below Pa.

[0016] According to this structure, since a foamed molded body is provided on the surface of the gripping part, the gripping part can be appropriately deformed with normal gripping force to achieve a good gripping effect and easy brushing.

[0017] In one embodiment of the toothbrush of the present invention, the structure may be such that the loss elastic modulus G'' of the foamed molded body is 10. 4 Pa or above, 10 6.5 Below Pa.

[0018] According to this structure, when holding the toothbrush while brushing, the foamed body does not deform instantly but gradually, and can achieve a degree of change in the deformation that can be temporarily maintained after letting go.

[0019] In one embodiment of the toothbrush of the present invention, the structure may be such that the loss tangent (loss elastic modulus / storage elastic modulus) of the soft resin is 0.05 or more.

[0020] According to this structure, when holding the toothbrush, the foamed body deforms with a force that is easy to hold, and the deformation speed is also a moderate deformation speed that is neither too fast nor too slow, so it is easy for the user to hold.

[0021] In one embodiment of the toothbrush of the present invention, the structure may be as follows: the Shore A hardness of the soft resin is less than 30.

[0022] This structure provides an excellent fit when gripping the holding part with your hand.

[0023] In one embodiment of the toothbrush of the present invention, the structure may be such that the mode of the dimensions of the plurality of pores is 0.001 mm. 2 Above, 0.3mm 2 Within the following range.

[0024] Based on this structure, a moderate degree of softness can be achieved in the foamed molded body.

[0025] In one embodiment of the toothbrush of the present invention, the structure may be such that, relative to the mode of the dimensions of all the voids, 80% of the voids in the foamed body are within ±0.3 mm. 2 Within the range.

[0026] Based on this structure, a more moderate degree of softness can be achieved in the foamed molded body.

[0027] In one embodiment of the toothbrush of the present invention, the structure may be such that, in the cross section of the foamed body intersecting the center line, the average occupancy ratio of the plurality of void portions is in the range of 2% or more and 60% or less.

[0028] Based on this structure, the softness of the foamed molded body is improved, and a foamed molded body that can be moderately deformed when holding a toothbrush can be obtained.

[0029] In one embodiment of the toothbrush of the present invention, the structure may be as follows: the density of the soft resin is 0.55 g / cm³. 3 Above, 0.8g / cm 3 Within the following range.

[0030] According to this structure, it is possible to obtain softness while ensuring the strength of the foamed molded body.

[0031] In one embodiment of the toothbrush of the present invention, the structure may be as follows: the cross-section of the grip portion intersecting the center line is composed of the base component and the foamed body, and the cross-sectional area of ​​the foamed body is less than 50% relative to the total area of ​​the sum of the cross-sectional areas of the base component and the cross-sectional areas of the foamed body.

[0032] According to this structure, the sinking effect of the foamed body caused by multiple gaps can be improved, which can improve the softness of the grip. At the same time, due to the presence of the base component located inside the foamed body, the grip will not deform as a whole, thus ensuring good operability of the toothbrush.

[0033] In one embodiment of the toothbrush of the present invention, the structure may be as follows: the thickness of the foamed molded body is 2 mm or more and 5 mm or less.

[0034] Based on this structure, a moderate sinking effect can be achieved due to the multiple gaps, thus improving grip.

[0035] In one embodiment of the toothbrush of the present invention, the structure may be as follows: the grip portion has an epidermal layer forming the surface of the grip portion and a foam layer in which the filling portion and the plurality of void portions are covered by the epidermal layer, wherein the ratio of the thickness of the epidermal layer to the thickness of the foam layer in a cross section intersecting the center line is in the range of 1:1 or more and 1:10 or less.

[0036] According to this structure, there is no risk of reduced strength as a foamed molded body, and the improved softness effect brought about by the multiple voids in the foam layer can be obtained.

[0037] In one embodiment of the toothbrush of the present invention, the structure may be such that the proportion of the foamed body formed along the entire length of the grip portion is in the range of 50% or more and 100% or less.

[0038] According to this structure, when the gripping part is held by hand during brushing, a foamed molded body is provided in more than half of the area that the hand touches, making it easy to hold.

[0039] [Invention Effects]

[0040] According to the present invention, it is possible to provide a toothbrush that is unrestricted in design and can improve grip. Attached Figure Description

[0041] [ Figure 1 ] Figure 1 This is a front view of a toothbrush according to one embodiment of the present invention.

[0042] [ Figure 2 ] Figure 2 It is along Figure 1 A cross-sectional view of line II-II in the diagram.

[0043] [ Figure 3 ] Figure 3 It is a diagram showing the size distribution of the voids in a foamed molded body.

[0044] [Figure Labels]

[0045] 1…toothbrush, 2…toothbrush body, 3…brush part, 21…grip, 21A…grip body, 22…neck, 23…head, 31…bristles, 201…base component, 202…foamed body, 202b…filler, 202c…void, 202A…foamed layer, 202B…epidermal layer, G''…loss modulus of elasticity, G'…storage modulus of elasticity, O…centerline, tanδ…loss tangent Detailed Implementation

[0046] The following is for reference Figure 1 as well as Figure 2 An embodiment of the toothbrush of the present invention will be described.

[0047] It should be noted that the following embodiments illustrate one aspect of the present invention and do not limit the present invention; modifications can be made arbitrarily within the scope of the technical concept of the present invention. Furthermore, in the following drawings, to facilitate understanding of the structures, the actual structures and the scale and quantities in each structure differ.

[0048] Toothbrush

[0049] The toothbrush of the present invention will be described below with reference to the accompanying drawings.

[0050] Figure 1 This is a front view of a toothbrush 1 according to one embodiment of the present invention. Figure 2 It is along Figure 1 A cross-sectional view of line II-II in the diagram.

[0051] like Figure 1 As shown, the toothbrush 1 of this embodiment is composed of a toothbrush body 2 and a brush part 3, and is formed into a long strip shape with a length along the center line O.

[0052] The toothbrush body 2 has: a grip portion 21 having a length along a center line O; a neck 22 extending along the center line O from the front end of the grip portion 21; and a head 23 disposed on the front end side of the neck 22 and on the side opposite to the grip portion 21. It should be noted that, as a toothbrush 1, it may have the following structure: no neck 22 is provided between the grip portion 21 and the head 23.

[0053] The head 23 is roughly rectangular in shape when viewed from the front. The head 23 has a hair-planting surface 23a on the front side. Multiple hair-planting holes 23b are formed on the hair-planting surface 23a. Figure 1 In the embodiment shown, 26 hair implantation holes 23b are formed on the hair implantation surface 23a, but the number of hair implantation holes 23b is not limited to this.

[0054] In each hair-planting hole 23b, a roughly cylindrical hair bundle 31 formed by binding multiple bristles is implanted. The multiple hair bundles 31 implanted in each hair-planting hole 23b constitute the brush part 3.

[0055] Examples of bristles constituting the bristle bundle 31 include straight bristles, bristles whose diameter gradually decreases towards the front end (conical bristles), bristles with forked front ends, spiral bristles, and bristles with irregular cross sections.

[0056] The front end shape of the hair tuft 31 can be flat, mountain-shaped, convex, concave, etc.

[0057] The type of bristles used and the shape of the front end of the bristle bundle 31 can be appropriately set considering the cleaning effect required by the brush part 3 and the contact feel with the gums.

[0058] The neck 22 is disposed between the grip portion 21 and the head 23, and is the part connecting the grip portion 21 and the head 23. In this embodiment, the neck 22 is formed such that it extends from the head 23 toward the grip portion 21 with a predetermined width, and its width increases at the rear end as it moves toward the grip portion 21.

[0059] The length and width of the neck 22 can be appropriately set according to the material, etc., to ensure the necessary strength of the neck 22 while improving the operability in the oral cavity and the accessibility to the molars.

[0060] The grip portion 21, which is the part held by the user, is formed in the shape of a long column. To ensure sufficient length for the user to hold and use the grip portion 21, it is preferable to set the length from position W to the rear end of the toothbrush 1 from a frontal view to, for example, 80 mm or more and 140 mm or less. The grip portion 21 is connected to the rear end of the neck 22 in a manner that depicts a continuous, smooth curve in its shape. In this embodiment, from... Figure 1 The length from the position W1 shown to the rear end of the toothbrush 1 is the grip portion 21, but the range of the grip portion 21 is not limited to this.

[0061] For example, the length from the position W2 where the curvature changes at the rear end of the neck 22 to the rear end of the toothbrush 1 can be used as the grip 21.

[0062] In the toothbrush body 2 constructed in this way, the surface of the grip part 21 that is held by hand when brushing is made of soft resin.

[0063] The toothbrush body 2 comprises a base component 201 formed of hard resin and a foamed body 202 formed of soft resin. The foamed body 202 is provided to cover a portion of the base component 201 (corresponding to the grip portion 21). As the overall shape of the toothbrush body 2, there is no difference in height at the boundary between the base component 201 and the foamed body 202, forming a smooth shape.

[0064] The base component 201 has a head 23, a neck 22, and a gripping body 21A. The base component 201 can be manufactured by injection molding using hard resin.

[0065] As a constituent material of the basic component 201, polypropylene (PP) is preferred, for example, from the perspective of high adhesion to soft resins. Other materials that can be used include, for example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexanedimethyl terephthalate (PCT), polyacetal (POM), polyethylene naphthalate (PEN), polystyrene (PS), acrylonitrile / butadiene / styrene resin (ABS), cellulose propionate (CP), polyarylate, polycarbonate, and acrylonitrile / styrene copolymer resin (AS). Among these resin materials, POM, PBT, and PEN are preferred from the perspective of high strength and ease of thinning the head 23. Furthermore, a single resin or a combination of two or more resins can be used.

[0066] The foamed body 202 is a porous body with multiple pores inside, which covers the entire surface of the gripping part body 21A in the base component 201, further towards the rear end than the neck 22. In the direction intersecting the centerline O, the gripping part body 21A is formed into a cylindrical shape with a smaller width and thickness than the rear end of the neck 22. The gripping part body 21A extends with a certain diameter in the length direction. The foamed body 202 is formed to fill the height difference 4 at the boundary position between the neck 22 and the gripping part 21 formed in the base component 201.

[0067] In addition, the gripping body 21A of the base component 201 is not limited to a cylindrical shape and can be modified appropriately.

[0068] The foamed molded body 202 has a foamed layer 202A and a skin layer 202B formed on the outermost surface of the foamed layer 202A. The foamed layer 202A has a filling portion 202b and a plurality of void portions 202c formed within the filling portion 202b. The foamed layer 202A is formed as an independent bubble structure in which each of the plurality of void portions 202c is surrounded by the filling portion 202b, and there are no void portions 202c in the skin layer 202b. Therefore, the outer peripheral surface of the skin layer 202B (the surface of the gripping portion 21) is formed as a smooth curved surface.

[0069] As the soft resin constituting the foamed molded body 202, a resin softer than the hard resin used in the base component 201 can be used. In this embodiment, a resin with a Shore A hardness of less than 30 can be used.

[0070] Specific examples of the soft resin constituting the foamed body 202 include styrene-based and olefin-based elastomer resins with a Shore A hardness of less than 30. The Shore A hardness of the soft resin constituting the foamed body 202 is more preferably in the range of 0 to 25, and even more preferably in the range of 0 to 20. When the Shore A hardness of the soft resin is below the upper limit, an excellent feel when gripping the holding part 21 by hand can be obtained. When the Shore A hardness exceeds the upper limit and becomes high, the foamed body 202 is difficult to deform, and the feel of gripping the toothbrush 1 is reduced.

[0071] It should be noted that Shore A hardness refers to the hardness measured according to JIS K 7215 or JIS K 6253.

[0072] In addition, in this embodiment, from the perspective of ease of deformation and softness, styrene-based elastomer resin is preferred.

[0073] The soft resin constituting the foamed molded body 202 can be used alone or in combination with two or more types.

[0074] The storage modulus G' of the soft resin constituting the foamed molded body 202 (compression conditions: temperature 23°C, frequency: 1Hz) is preferably above 10. 4 Pa or above, 10 6.5 More preferably, within the range of Pa below 10 Pa. 5.5 Pa or above, 10 6.5 Within the range of Pa. Therefore, it can deform moderately with normal gripping force, resulting in a good grip and easy brushing effect for the opponent.

[0075] The storage modulus G' of the foamed molded body 202 is less than 10. 4 In the case of Pa, due to deformation under weak force, the foam molded body 202 moves during brushing, reducing grip and making brushing difficult. Conversely, when the storage modulus G' of the foam molded body 202 is greater than 10... 6.5 Under the condition of Pa, the foamed body 202 will not deform unless a strong force is applied. Therefore, the foamed body 202 is difficult to deform using normal gripping force, thus reducing the feeling of fit when holding it.

[0076] The loss modulus of elasticity G'' of the soft resin constituting the foamed molded body 202 is preferably 10. 4 Pa or above, 10 6.5 More preferably, within the range of Pa below 10 Pa. 4.5 Pa or above, 10 5.5Within the range below Pa. Therefore, when holding the toothbrush 1 during brushing, the foamed molded body 202 does not deform instantaneously but gradually, and can achieve a change in the degree to which the deformation when holding is temporarily maintained after releasing the hand.

[0077] On the other hand, the loss modulus G'' of the foamed molded body 202 is less than 10. 4 Under the condition of Pa, the deformation speed of the foamed molded body 202 increases, and it instantly deforms into a shape that the user can grip. Therefore, when gripping, the user cannot immediately obtain the rebound force of the foamed molded body 202, so it cannot be gripped well and is difficult to hold.

[0078] Conversely, the loss modulus G'' of the foamed molded body 202 is greater than 10. 6.5 In the case of Pa, the deformation speed of the foamed molded body 202 slows down, and it takes time until it deforms into a shape that the user can grip. Therefore, when changing the grip of the toothbrush, it takes time for the shape to change from the gripping state before the grip change to the ungripped shape until the grip change. Since the deformation of the foamed molded body 202 is difficult to recover, the followability of the hand is reduced, and the usability when changing the grip of the toothbrush during brushing is reduced.

[0079] The loss tangent tanδ (loss modulus G'' / storage modulus G') of the soft resin constituting the foamed body 202 is in the range of 0.05 to 0.3. Therefore, when holding the toothbrush 1 during brushing, the foamed body 202 deforms with a force that is easy to grip, and the deformation speed is also moderate, so it is easy for the user to hold.

[0080] When the loss tangent tanδ of the soft resin is less than 0.05, a force greater than that required for normal brushing is needed to deform it, and the rebound force of deformation recovery is also strong. On the other hand, because the deformation speed is also fast, the hand can follow it quickly, so if it is not pressed in by hand frequently, it will become difficult to maintain the deformed state and become difficult to hold.

[0081] Furthermore, when the loss tangent tanδ of the soft resin is greater than 0.3, although it can be deformed with a small force, the deformation rate tends to slow down. Therefore, the ability to follow the shape of the hand's grip during brushing becomes slower, making it difficult to hold.

[0082] The foamed molded body 202 is formed from a foamed resin obtained by mixing a foaming agent into a soft resin and then foaming it. There are no particular limitations on the foaming agent; known chemical or physical foaming agents can be used. Examples of base polymers include polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), and ethylene-vinyl acetate (EVA). In this embodiment, from the perspective of compatibility with the elastomer resin, polyethylene is preferably used as the foaming agent.

[0083] Examples of foaming molecules in organic systems include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT), azobisisobutyronitrile, barium azodicarbonate, and p,p'-oxobisbenzenesulfonyl hydrazine (OBSH). Examples of foaming molecules in inorganic systems include sodium bicarbonate, ammonium bicarbonate, sodium carbonate, and ammonium carbonate, which are carbonate compounds. In this embodiment, considering compatibility with the elastomer resin and foaming temperature, organic foaming molecules are preferred.

[0084] To promote the foaming of soft resins, foaming aids can be used together with foaming agents. Examples of foaming aids include urea and urea derivatives.

[0085] In addition, there is no particular limitation on the amount of foaming agent mixed with the soft resin, and it can be designed appropriately.

[0086] The foamed molded body 202 consists of a foamed layer 202A formed of foaming resin and an unfoamed skin layer 202B. The foamed layer 202A has a filling portion 202b and a plurality of void portions 202c. In a cross-section of the foamed molded body 202 in a direction intersecting the central axis, each void portion 202c exists independently within the filling portion 202b. The skin layer 202B is formed on the entire surface of the foamed layer 202A.

[0087] The mode size of the plurality of voids 202c in the foamed molded body 202 is preferably 0.001 mm. 2 Above, 0.3mm 2 Within the following range, more preferably within 0.01 mm 2 Above, 0.1mm 2 Within the following range. As a result, it is possible to obtain a moderate degree of softness in the foamed molded body 202.

[0088] The mode dimension of each gap 202c is less than 0.001 mm. 2In this case, the softness of the foamed molded body 202 cannot be obtained. That is, because the amount of deformation of each void 202c is smaller, it is difficult to obtain the sinking effect of the resin accompanying the deformation of the void 202c. Therefore, the fit of the toothbrush 1 to the hand is reduced.

[0089] On the other hand, the mode dimension of the gap 202c is greater than 0.3 mm. 2 In this situation, when holding the toothbrush 1, the sinking effect cannot be effectively obtained, so the foamed molded body 202 does not soften, and the fit to the hand is reduced. That is to say, the upper and lower surfaces of the void portion 202c (the surfaces opposite each other in the direction of the applied force) easily come into contact with each other, and the sinking effect of the resin caused by the deformation of the void portion cannot be effectively obtained. Therefore, the fit to the hand is reduced when holding the toothbrush 1.

[0090] Furthermore, the mode size of 80% of the multiple voids 202c in the foamed molded body 202 is preferably within ±0.3 mm. 2 Within the range, more preferably within ±0.2mm 2 Within this range, it is possible to obtain a more moderate degree of softness in the foamed molded body 202.

[0091] It should be noted that, within the ranges mentioned above, the desired softness of the foamed molded body 202 with uniformity cannot be obtained.

[0092] The foamed molded body 202 can be formed using injection molding methods such as short shot, full shot, or core back. In this embodiment, short shot injection molding is preferred in order to effectively foam the organic foaming molecules.

[0093] In the cross-section of the foamed body 202 intersecting the center line O, the average percentage of the occupancy of the plurality of void portions 202c is preferably in the range of 2% or more and 60% or less, and the upper limit is further preferably 50% or less. As a result, the softness of the foamed body 202 is improved, and a foamed body 202 that can be moderately deformed when holding the toothbrush 1 can be obtained.

[0094] When the proportion of multiple voids 202c in the cross-section of the foamed molded body 202 decreases to less than 2%, the deformation of the foamed molded body 202 becomes smaller, making it difficult to achieve softness. Conversely, when the proportion increases to more than 60%, the strength of the foamed molded body 202 decreases, or the independent foam of each void 202c cannot be maintained, resulting in an increase in combined foam and a reduction in the effect of improving softness.

[0095] The thickness of the foamed molded body 202 is preferably 2 mm or more and 5 mm or less.

[0096] As a result, a moderate sinking effect is achieved by the gap 202c, thus improving grip.

[0097] When the thickness of the foamed body 202 is less than 2mm, the moderate sinking effect brought about by the voids 202c cannot be obtained, and the softness of the foamed body 202 is reduced.

[0098] Conversely, when the thickness of the foamed body 202 is greater than 5 mm, the foamed body 202 sinks too much when gripping the holding part 21 and becomes too soft, making it difficult to hold.

[0099] The density of the filler portion 202b in the foamed molded body 202 is preferably 0.55 g / cm³. 3 Above, 0.8g / cm 3 Within the following range. Therefore, it is possible to achieve both strength and softness in the foamed molded body 202.

[0100] In the foamed molded body 202, the density of the filler portion 202b is less than 0.55 g / cm³. 3 In such cases, strength cannot be guaranteed. Conversely, when the density of filler 202b is greater than 0.8 g / cm³, strength cannot be guaranteed. 3 In such cases, softness cannot be guaranteed.

[0101] The foamed molded body 202 has a skin layer 202B and a foam layer 202A, and the thickness ratio of these layers is preferably 1:1 or more, 1:10 or less, and more preferably 1:5 or less. Therefore, there is no risk of reduced strength in the foamed molded body 202, and the improved softness effect resulting from the voids 202c of the foam layer 202A can be obtained.

[0102] If the skin layer 202B becomes too thick relative to the foam layer 202A, the amount of foam layer 202A with voids 202c will decrease, and the improved softness effect brought by the voids 202c cannot be obtained.

[0103] Conversely, if the skin layer 202B becomes too thin relative to the foam layer 202A, the voids 202c will be close to the skin layer 202B, thus posing a risk of the voids 202c being exposed on the surface. In this case, there is a concern about reduced strength or poor appearance of the foamed molded body 202.

[0104] Furthermore, in this embodiment, the cross-section of the grip portion 21 intersecting the center line O of the toothbrush 1 is composed of a base component 201 and a foamed body 202. The proportion of the cross-sectional area of ​​the foamed body 202 to the total area obtained by combining the cross-sectional areas of the base component 201 and the foamed body 202 is preferably less than 50%, more preferably 20% or more and 40% or less. This improves the sinking effect of the foamed body 202 caused by the gap portion 202c, enhancing the softness of the grip portion 21. Furthermore, due to the presence of the base component 201 located inside the foamed body 202, the grip portion 21 as a whole does not deform, thus ensuring good operability of the toothbrush 1.

[0105] When the cross-sectional area of ​​the foamed body 202 is less than 20%, the sinking effect of the foamed body 202 carried by the void portion 202c is reduced, and the softness is reduced.

[0106] Conversely, when the cross-sectional area of ​​the foamed molded body 202 is large, exceeding 50%, the strength of the toothbrush 1 is worrying.

[0107] The proportion of foamed material 202 formed along the entire length of the grip portion 21 is preferably 50% or more and 100% or less, with a lower limit more preferably 80% or more. As a result, when the grip portion 21 is gripped by hand during brushing, the foamed material 202 is provided in more than half of the area that is in contact with the hand, making it easier to grip.

[0108] If the proportion of the foamed body 202 formed relative to the length direction of the grip portion 21 is small, then when brushing, it is impossible to provide the foamed body 202 on the entire part that the hand touches when gripping the grip portion 21. Instead, the hand covers the boundary between the base part 201 made of hard resin and the foamed body 202, making it difficult to grip. Therefore, it is preferable that the foamed body 202 is present in approximately the entire area where the hand grips the grip portion 21 as much as possible.

[0109] As described above, in the toothbrush 1 of this embodiment, by employing a structure in which a foam-molded body 202 covers the entire axis of the grip portion main body 21A in the base component 201 formed of hard resin, the foam-molded body 202 is present around the entire axis of the grip portion 21 when the toothbrush 1 is held by hand during brushing. Therefore, regardless of the gripping method, the foam-molded body 202 deforms three-dimensionally, increasing the contact area with the hand, thus allowing the grip portion 21 to conform to the thumb, index finger, and palm. Consequently, the grip of the toothbrush 1 is improved, making brushing easier and resulting in a toothbrush 1 with a good grip feel.

[0110] Furthermore, in this embodiment, the toothbrush 1 is formed by first molding a base component 201 made of hard resin, and then by second molding with soft resin to form a foamed molded body 202 that partially covers the surface of the base component 201. In this way, it can be manufactured without design constraints, and the design flexibility of the toothbrush 1 can be improved.

[0111] [Example]

[0112] The effects of the present invention will be made clearer through the following embodiments. Furthermore, the present invention is not limited to the following embodiments and can be implemented with appropriate modifications without changing its spirit.

[0113] (Examples 1-16, Comparative Examples 1-2)

[0114] In this embodiment, according to Tables 1 and 2 below and Figure 2 The toothbrushes shown are manufactured according to the specifications of Examples 1-16 and Comparative Examples 1-2. Figure 1 and Figure 2 The toothbrush shown is the same sample.

[0115] The common specifications of Examples 1-16 and Comparative Examples 1-2 are shown below.

[0116] Grip section 21: Overall length 115mm, maximum width 14.5mm, maximum thickness 14.5mm

[0117] Basic component 201: Length 110mm, Width 8.5mm, Thickness 8.5mm

[0118] Foamed Molded Body 202: Maximum Coverage Thickness 3mm

[0119] The dividing line between the neck 22 and the grip 21 (position w): 11mm wide, 11mm thick

[0120] Neck 22: Length 45mm, minimum width 5mm, minimum thickness 5mm

[0121] Head 23: Length 25mm, Width 11mm, Thickness 4.5mm

[0122] In addition, the specifications of the toothbrushes in Examples 1 to 10 are shown in Table 1 and Table 2, and the specifications of the toothbrushes in Examples 11 to 16 and Comparative Examples 1 and 2 are shown in Table 2.

[0123] PP resin is used as the material for the handle.

[0124] The specifications for the samples in each embodiment and comparative example are: energy storage elastic modulus, loss elastic modulus, loss tangent, A hardness, mode of the void size, and void occupancy ratio. These specifications are set for each sample.

[0125] "Evaluation of Energy Storage Elastic Modulus"

[0126] As an instrument for evaluating the elastic modulus of energy storage, a dynamic viscoelastic device (E4000) manufactured by UBM was used.

[0127] As an evaluation method for energy storage elastic modulus, a test piece (a 10mm square resin plate with a thickness of 6mm) is fixed on the above-mentioned dynamic viscoelastic device. The energy storage elastic modulus and loss elastic modulus are measured under compression conditions at a frequency of 1Hz and a temperature of 23℃, and the loss tangent is calculated.

[0128] Evaluation of void dimensions

[0129] Figure 3 This is a diagram showing the size distribution of the void portion 202c in the foamed molded body 202.

[0130] exist Figure 3 In the diagram, the vertical axis represents the number of gaps 202c, and the horizontal axis represents the size of the gaps 202c.

[0131] The cross-section of the test piece was observed under a microscope, and the cross-sectional area of ​​the void portion 202c was measured (n=40).

[0132] like Figure 3 As shown, the mode of the dimension of the gap 202c is 0.01 mm. 2 ~0.1mm 2 Additionally, the average value is 0.025 mm. 2 .

[0133] [Table 1]

[0134]

[0135] [Table 2]

[0136]

[0137] [Evaluation Method]

[0138] (1) The ease of gripping the grip part 21 (the feel of the grip on the hand)

[0139] [Experimental Methods]

[0140] The "ease of gripping the grip portion 21 (feeling of the hand)" was evaluated in each embodiment of the toothbrush 1 by having 10 monitors hold the toothbrush 1 and perform brushing.

[0141] The evaluation was set as an absolute rating on a scale of 1 to 7. The average score of 10 monitors was used to classify the grip ease of the gripping part 21 according to the following judgment criteria.

[0142] <Judgment Criteria>

[0143] ☆: Average score above 6.6

[0144] ◎: Average score above 5.5 and below 6.5

[0145] ○: Average score is above 4.6 and below 5.5.

[0146] △: Average score is above 3.6 and below 4.5.

[0147] ×: Average score less than 3.5 points

[0148] (2) Deformation speed of gripping part 21

[0149] [Experimental Methods]

[0150] Ten monitors brushed their teeth with toothbrush 1, and the "deformation speed of the grip" was evaluated using toothbrushes from various embodiments.

[0151] The evaluation was set as an absolute rating on a scale of 1 to 7. The average score of 10 monitors was used as the following criteria to determine the deformation rate (deformation condition) of the grip 21.

[0152] <Judgment Criteria>

[0153] ☆: Average score above 6.6

[0154] ◎: Average score above 5.5 and below 6.5

[0155] ○: Average score is above 4.6 and below 5.5.

[0156] △: Average score is above 3.6 and below 4.5.

[0157] ×: Average score less than 3.5 points

[0158] (3) Ease of sweeping

[0159] [Experimental Methods]

[0160] Ten monitors brushed their teeth with toothbrush 1, and the "ease of brushing" was evaluated using toothbrushes from various embodiments.

[0161] The evaluation was set on a seven-point scale, from 1 to 7 points, as an absolute rating. The average score of the 10 monitors was used to classify the ease of sweeping according to the following criteria.

[0162] <Judgment Criteria>

[0163] ☆: Average score above 6.6

[0164] ◎: Average score above 5.5 and below 6.5

[0165] ○: Average score is above 4.6 and below 5.5.

[0166] △: Average score is above 3.6 and below 4.5.

[0167] ×: Average score less than 3.5 points

[0168] As shown in Tables 1 and 2, for the samples of Examples 1 to 16 with a value of "storage elastic modulus G' (Log10)" between 4.0 and 6.5, good results were obtained for all aspects of "ease of gripping the gripping part 21 (feel of contact with the hand)", "deformation of the gripping part 21" and "ease of brushing".

[0169] In contrast, for Comparative Example 1, whose "storage modulus of elasticity G' (Log10)" value is less than 4.0 and Comparative Example 2, whose value is greater than 6.5, good results were obtained regarding "ease of gripping the grip portion 21 (feel of contact with the hand)" and "ease of brushing".

[0170] In addition, as shown in [Table 1] and [Table 2], for the samples of Examples 5 to 16 with a value of "loss elastic modulus G'' (Log10)" in the range of 4.0 or higher and 6.5 or lower, good results were obtained for all aspects of "ease of gripping the gripping part 21 (feel of contact with the hand)", "deformation of the gripping part 21" and "ease of brushing".

[0171] Furthermore, as shown in [Table 1] and [Table 2], for the samples of Examples 10, 11, 15, and 16 whose energy storage elastic modulus G' (Log10), loss elastic modulus G'' (Log10), loss tangent tanδ (Log10), and hardness of the foamed molded body 202 are within the following ranges, particularly good results were obtained for all aspects of "ease of gripping the grip portion 21 (feel of contact with the hand)", "deformation of the grip portion 21", and "ease of brushing".

[0172] Furthermore, in the samples of Examples 10, 11, 15, and 16, the mode of the size of the void portion 202c in the foamed molded body 202 is 0.01 mm. 2 Above, 0.1mm 2 Within the following range, Example 15 yielded the best results.

[0173] The sample specifications of Example 15 can be considered the optimal model.

[0174] The above is with reference to the appendix. Figure 1Preferred embodiments of the present invention will be described below, but the present invention is not limited to these examples. The shapes and combinations of the constituent parts shown in the above examples are just examples, and various changes can be made according to design requirements, etc., without departing from the spirit of the present invention.

Claims

1. A toothbrush, characterized in that, The toothbrush comprises a toothbrush body and a brush head. The toothbrush body has a grip portion extending along a center line, a neck extending from the front end of the grip portion, and a head disposed on the side of the neck opposite to the grip portion. The brush head is formed by a plurality of bristles embedded in the head. The toothbrush body has: A base component made of hard resin, comprising a gripping body, the neck, and the head; and A foamed molded body formed of soft resin and disposed on the surface of the grip body. The foamed molded body has a filling portion and multiple void portions. The energy storage elastic modulus G' of the foamed molded body is 10 4 Pa or more and 10 6.5 Pa or less, The loss elastic modulus G" of the foamed molded body is 10 4 Pa or more and 10 6.5 Pa or less, The loss tangent of the soft resin, i.e., the loss elastic modulus G'' ÷ storage elastic modulus G', is greater than 0.05 and less than 0.

3.

2. The toothbrush of claim 1, wherein, The soft resin has a Shore A hardness of less than 30.

3. The toothbrush of claim 1 or 2, wherein, The mode of the size of the plurality of voids is in the range of 0.001 mm 2 Above, 0.3 mm 2 Below, in the range of 0.001 mm 4. The toothbrush of claim 1 or 2, wherein, The number of 80% of all the voids in the foamed molded body is within ±0.3 mm of the mode of the sizes of all the voids. 2 The number of 80% of all the voids in the foamed molded body is within ±0.3 mm of the mode of the sizes of all the voids.

5. The toothbrush of claim 1 or 2, wherein, In the cross-section of the foamed body intersecting the centerline, the average percentage of the plurality of void portions is between 2% and 60%.

6. The toothbrush of claim 1 or 2, wherein, The soft resin has a density of 0.55 g / cm 3 The soft resin has a density of 0.55 g / cm 3 The soft resin has a density of 0.55 g / cm 7. The toothbrush according to claim 1 or 2, wherein, The cross-section of the gripping portion intersecting the centerline is composed of the base component and the foamed molded body. The cross-sectional area of ​​the foamed body is less than 50% of the total area, which is the sum of the cross-sectional areas of the base component and the foamed body.

8. The toothbrush according to claim 5, wherein, The thickness of the foamed molded body is more than 2 mm and less than 5 mm.

9. The toothbrush according to claim 1 or 2, wherein, The gripping part has: The epidermis forming the surface of the grip portion; and The filling portion and the plurality of void portions are covered by a foamed layer with the skin layer. In the cross section intersecting the center line, the ratio of the thickness of the skin layer to the thickness of the foam layer is in the range of 1:1 or higher and 1:10 or lower.

10. The toothbrush according to claim 1 or 2, wherein, The proportion of the foamed material formed along the entire length of the grip portion is between 50% and 100%.

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