The present invention relates to toothbrushes and a toothbrush manufacturing method.
The present application, on October 28, 2016, claiming priority based on Japanese Patent Application No. 2016-211233, filed in Japan, the contents of which are incorporated here.
BACKGROUND
[0002]
　Conventionally, (specifically, the state plus toothbrush in the mouth) when using the toothbrush may extraoral wounded by tipping, particularly, when the user of the toothbrush is 1-3 years old infants , often extraoral wounded case.
[0003]
　Conventionally, the breaking defect or the head portion and the neck portion as a potential toothbrush suppression, there is a toothbrush disclosed in Patent Document 1.
　Patent Document 1, the configured base surface of a hard resin, toothbrush coating layer formed made of soft resin covering more than 70% of the total of the surface areas and the neck portion of the head portion is disclosed ing.
[0004]
　Patent Document 1, with the above arrangement, even when added excessive load to the head portion and the neck portion, and that is possible to hardly break the handle body, the head portion or neck portion is broken even if, is folded portions by coating are disclosed that can be prevented from being exposed. Toothbrushes disclosed in Patent Document 1 having the above structure, since the base which constitutes the tip of the head portion is covered with a soft resin, biting strong, or the tip of the head portion is hit strongly in the oral cavity when the above soft resin functions as a cushioning material.
　Thus, by using the toothbrush disclosed in Patent Document 1, it is possible to suppress damage to the oral cavity due to the tip of the head.
[0005]
　Further, Patent Document 2, when a predetermined compressive force in the longitudinal direction of the handle portion is applied against the toothbrush, resulting bending due to plastic deformation in the connecting portion, flocked surface of the head portion is located inside of the bent toothbrush has been disclosed. Toothbrushes disclosed in Patent Document 2, to enhance the safety by further restricting the amount of intrusion into the oral cavity of the handle portion.
CITATION
Patent Document
[0006]
Patent Document 1: JP 2013-458 JP
Patent Document 2: JP 2016-034309 JP
Summary of the Invention
Problems that the Invention is to Solve
[0007]
　However, the neck portion of the toothbrush disclosed in Patent Document 1, so as to cover the base of the surface constituting the neck portion, the coating layer is provided thickness than the base board is made of thin soft resin . Therefore, the head portion of the toothbrush disclosed in Patent Document 1, for example, (specifically, the direction toward the distal end from the rear end of the toothbrush) the extending direction of the toothbrush when the external force is applied to, the user's as the oral cavity is not damaged, so as to release the external force transmitted to the distal end of the head portion sufficiently, it is difficult to bend.
[0008]
　Further, the toothbrush described in Patent Document 2, also the amount of intrusion into the oral cavity of the handle portion is restricted, since the connecting portion which is plastically deformed remains in the oral cavity as a rigid body, in the mouth of a user damage from the point of view of avoiding it can not be said that adequate measures.
[0009]
　The present invention has been made in view of the above, and an object thereof is to provide a possible toothbrush and toothbrush manufacturing method of suppressing damage to the oral cavity of the user.
Means for Solving the Problems
[0010]
　According to a first aspect of the present invention, a head portion having a bristle face on the tip side is placed on the rear side of the head portion, a handle portion including a handle body, and the flocked surface and the handle portion and a placed neck between the rear end side of the flocked surface, having a deformable portion which stress characteristics flexural caused by an external force to the head portion is deformed shows a plane stress toothbrush is provided according to claim.
[0011]
　Further, in the toothbrush according to the above embodiment of the present invention, the flexible portion is, the direction of bending perpendicular to the longitudinal direction of the handle portion in parallel to the flocked surface, to deform shows the plane stress and features.
[0012]
　Internal Further, in the toothbrush according to one embodiment of the present invention, a hard member which is formed by being disposed over a portion from the head portion of the distal end of the handle portion hard resin, at least a portion of said rigid member housed, it includes a soft portion made of soft resin, wherein the deformable portion is characterized in that said rigid member is disposed on at least a portion of the arrangement region.
[0013]
　Further, characterized in that in a toothbrush according to one embodiment of the present invention, the hard member in the deformation portion, the bending thickness direction is 0.5mm or more and 2mm or less, flexural modulus is not less than 500MPa to.
[0014]
　Further, in the toothbrush according to the above embodiment of the present invention, the bending direction of the thickness of the hard member in the deformed portion D, of the hard member in the deformation portion, the cross section perpendicular to the longitudinal direction of the handle portion maximum cross-sectional lengths When L in, and satisfies the relation of D × √2 ≦ L.
[0015]
　Further, in the toothbrush according to the above embodiment of the present invention, the cross-section two related directionally bent moment of the hard member in the deformation section, 0.05 mm 4 or more, 5.8 mm 4 and equal to or less than.
[0016]
　Further, in the toothbrush according to the above embodiment of the present invention, the hard member in the deformation portion, the cross-sectional shape, square, rectangular, and wherein the polygons are either oval.
[0017]
　Further, in the toothbrush according to the above embodiment of the present invention, the hard resin is characterized by a polypropylene.
[0018]
　According to a second aspect of the present invention, a head portion having a bristle face on the tip side is placed on the rear side of the head portion, a handle portion including a handle body, and the flocked surface and the handle portion a step of designing a toothbrush having a arranged neck between, and a step of molding the toothbrush designed, the step of designing the toothbrush, the stress on flexural caused by an external force to the head portion the deformation portion characteristic is deformed shows a plane stress, toothbrush manufacturing method which comprises a design of placing on the rear end side of the flocked surface is provided.
Effect of the invention
[0019]
　In the present invention, it is possible to suppress damage to the oral cavity of the user.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020]
It is a side view of a toothbrush according to the embodiment of FIG. 1 the present invention.
It is a front view of the toothbrush shown in FIG. 1; FIG.
It is a rear view of the toothbrush shown in FIG. 3 FIG.
It is an enlarged side view of a rigid member shown in FIG. 4 FIG.
5 is a front view enlarging a rigid member shown in FIG.
Is a rear view enlarging a rigid member shown in FIG. 6 FIG.
It is [7] a cross-sectional view along the line A-A of the rigid member shown in FIG.
8 is a sectional view along the line B-B of the rigid members shown in FIG 4.
9 is a diagram showing the concept of plane stress.
The [10] section illustrates the maximum cross-sectional length L of the case is rectangular.
[Figure 11] is a sectional view showing a manufacturing process of a toothbrush of the present embodiment, it is a view illustrating a step of forming a rigid member with a first die.
[Figure 12] is a sectional view showing a manufacturing process of a toothbrush of the present embodiment, by using the second mold, the first soft resin, the soft portion, and illustrating a process for forming a handle body it is a diagram of.
13 is a diagram for explaining a flexural strength test for the sample.
14 is a diagram for explaining the IZOD strength test for the sample.
DESCRIPTION OF THE INVENTION
[0021]
　Hereinafter, the embodiments of the toothbrush and toothbrush manufacturing method of the present invention will be described with reference to FIGS. 1 to 14.
　Note that the following embodiments, showing an embodiment of the present invention, not intended to limit the invention, it can be arbitrarily modified within the technical scope of the present invention. In the following figures, for clarity the respective structure, at different scales and numbers in the actual structure and the structure. Here, for example, using both rigid resin and soft resin, and between the head portion and the handle portion will be described using an example of a case where the maximum width less of the neck of the head portion is disposed.
[0022]
　Figure 1 is a side view of a toothbrush 10 according to the embodiment of the present invention. Figure 2 is a front view of the toothbrush shown in Figure 1. In Figure 2, for convenience of explanation, not shown in the brush portion 12 including a plurality of bristle tufts 12-1 shown in FIG. Figure 3 is a rear view of the toothbrush shown in Figure 1.
　Figure 4 is an enlarged side view of a rigid member shown in FIG. Figure 5 is a front view enlarging a rigid member shown in FIG. Figure 6 is a rear view enlarging a rigid member shown in FIG.
[0023]
　In the structure shown in FIGS. 1-6, the same components are denoted by the same reference numerals. X direction shown in FIGS. 1 to 6 show the extending direction of the handle body 11 in a state that does not use the toothbrush 10 (extending direction of the neck portion 15). Z direction shown in FIGS. 1 and 4, in a state of not using the toothbrush 10 indicates the direction (normal direction) perpendicular to the bristle surface 21-1b. 2, FIG. 3, Y direction shown in FIG. 5, and 6 show the width direction of the toothbrush 10 (direction orthogonal to the Z direction and the X direction).
[0024]
　Toothbrush 10 includes a handle 11, a brush unit 12, a. The handle body 11 includes a head portion 14, a neck portion 15, a handle portion 16, the head portion 14, neck portion 15, and a rigid member 17 that constitutes a part of the handle portion 16, a. In this embodiment, between the flocked surface 21-1b and the handle portion 16, toothbrush 10 the width of the Y direction, the neck portion 15 is arranged smaller than the width of the head portion 14 (the maximum width in the Y-direction) It will be described.
[0025]
　Head portion 14 includes a base member 21 made of a hard resin, the first soft resin 22 covering a portion of the base member 21. The base member 21 is a part of the components of the hard member 17 made of a hard resin, includes a base member body 21-1, and two support portions 21-2 and. The base member body 21-1, so that can be arranged the first soft resin 22 in the side and bottom surfaces 21-1a of the base member body 21-1, the external shape of the head portion 14 to shrink about 1 ~ 2 mm was has a shape. The base member body 21-1 has a distal portion 21-1A, a bottom surface 21-1a, and flocked surfaces 21-1b, planting and pores 21-1B, the.
[0026]
　Tip 21-1A, of the base member body 21-1, the side where the head portion 14 and the neck portion 15 are connected is a portion located on the opposite side. Tip 21-1A is when the user is brushing using toothbrush 10, a intraoral portion facing the user. The shape of the tip portion 21-1A, for example, may be in a round shape (round shape).
[0027]
　Figure 7 is a cross-sectional view along the line A-A of the rigid member 17 shown in FIG. Bottom 21-1a of the rigid member 17 is a portion covered by the first soft resin 22 is disposed on the opposite side of the bristle surface 21-1b. Bottom 21-1a, for example, be a flat surface.
[0028]
　Flocked surface 21-1b is a flat surface. Flocked surface 21-1b is exposed a plurality of bristle holes 21-1B. It flocked surface 21-1b as a first exposure portion in the head portion 14 is exposed from the first soft resin 22. Thus, with constituting the base member body 21-1 using a hard rigid resin than the first soft resin 22, a plurality of bristle holes 21-1B and flocked surface 21-1b from the first soft resin 22 by causing exposed to a plurality of bristle holes 21-1B, using Tairasen planting method, the tufts 12-1 constituting the brush portion 12 can be flocked (implanted).
[0029]
　Flocked surfaces 21-1b, using the second die 51 shown in FIG. 12 to be described later, when the first soft resin 22, the soft portion 26, and that the handle body 31 for resin molding, the die 51 -2 is a surface in contact with the inner surface (see FIG. 12). Thus, flocking surface 21-1b is by contact with one of the inner surface of the mold 51-2 constituting the second die 51, first a plurality of bristle holes 21-1B and flocked surface 21-1b soft resin 22 can be prevented from being formed.
[0030]
　Planting pores 21-1B are provided a plurality on the side of the base member body 21-1 constituting the flocked surface 21-1b. The planting pores 21-1B, a hole tufts 12-1 constituting the brush portion 12 is flocked. The arrangement of the plurality of bristles holes 21-1B, for example, it is possible to employ an arrangement as shown in FIG. 2, not limited to this, so-called tessellated arrangement or staggered arrangement or the like, any it may also be an array pattern. The number of a plurality of bristle holes 21-1B is not limited to the number of bristle holes 21-1B shown in FIG. 2, for example, it can be appropriately set within a range of 10 to 60 holes. In other words, the arrangement of the plurality of bristles holes 21-1B, and the number of bristles holes 21-1B can be set appropriately according to the object. The shape of the planting pores 21-1B, not particularly limited, for example, can be used a true circle, ellipse circular, polygonal triangular or quadrangular, etc. and the like. The diameter of planting pores 21-1B may be determined depending on the thickness of the hair bundle 12-1, specifically, for example, can be appropriately set within a range of 1 ~ 3 mm.
[0031]
　When the thickness of the head portion 14 is 5.0mm in the Z direction (in other words, the thickness between the bottom surface 21-1a and the flocked surface 21-1b) The thickness of the Z direction of the base member body 21-1 , for example, it is 4.2 mm. In this case, the depth of the plurality of bristles holes 21-1B when relative to the flocked surface 21-1b, for example, can be set to 2.5 mm. The thickness of the head portion 14, as an example, the thickness was measured at the center portion of the X direction of the head portion 14.
[0032]
　Two support portions 21-2, (if in the state shown in FIG. 1, downward) from the bottom surface 21-1a of the base member body 21-1 Z direction is provided so as to protrude. Of the two support portions 21-2, one is arranged on the distal end side of the base member body 21-1 and the other is disposed on the rear end side of the base member body 21-1. Two support portions 21-2 are disposed so as to face in the X direction. Two support portions 21-2 has a protruding surface 21-2a which is a flat surface, respectively. Two projecting surfaces 21-2a, together are exposed from the outer surface of the first soft resin 22 are flush with the outer surface of the first soft resin 22. That is, the support portion 21-2, the second exposure portion in the head portion 14, as shown in FIG. 3, is exposed to the side opposite to the bristle surface 21-1b.
[0033]
　Projecting surface 21-2a using the first mold 41 shown in FIG. 11 to be described later, when molding the rigid member 17 including a base member body 21-1, a first mold 41 (see FIG. 11) a portion in contact with the inner surface. In this manner, the protruding surface 21-2a is in contact with the inner surface of the first mold 41 (see FIG. 11), the periphery of the two support portions 21-2 and a bottom surface 21-1a first soft resin 22 it can be formed.
[0034]
　The base member 21 of the above structure, the rear end is distal end and integrally formed of a core portion 25. The hard resin that constitutes the base member 21, using the hard resin than the first soft resin 22. Specifically, the hard resin that constitutes the base member body 21-1, in consideration of ensuring strength during brushing, for example, the flexural modulus (JIS7171) is a resin which is in the range of 500 ~ 3000 MPa can. By in this range, and at the time of insertion operability into the oral cavity, it is possible to achieve both the ensuring of plane stress deformation portion 15A.
[0035]
　Examples of such hard resin, for example, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), xylylene terephthalate to polycyclo (PCT), polyacetal (POM), polystyrene (PS) , acrylonitrile butadiene styrene resin (ABS), cellulose propionate (CP), polyarylate, polycarbonate can be exemplified acrylonitrile-styrene copolymer resin (AS) and the like. The hard resin may be used alone or may be used in combination of two or more kinds thereof.
[0036]
　First soft resin 22 are flocked surfaces 21-1b, a plurality of bristles holes 21-1B, two state of exposing the end surface 21-2a of the support portion 21-2, the side surface of the base member body 21-1 and It is provided so as to cover the bottom surface 21-1a. Accordingly, the first soft resin 22 is disposed so as to cover the tip portion 21-1A of the base member body 21-1.
[0037]
　Thus, by arranging the first soft resin 22 so as to cover the tip portion 21-1A of the base member body 21-1, when the user uses the toothbrush 10, are disposed at the distal end portion 21-1A since the first soft resin 22 functions as a cushion material, in the direction toward the front end side from the rear end side of the toothbrush 10 is applied an external force, the first soft resin 22 disposed on the tip 21-1A use was who at the time of being pressed strongly in the oral cavity, can be suppressed within the oral cavity of the user may be damaged.
[0038]
　The thickness of the first soft resin 22 disposed on a side surface and a bottom surface 21-1a of the base member body 21-1, for example, be in accordance with the intended set as appropriate within a range of 0.2 ~ 2.0 mm can be, but for example, it can be set to 0.8 mm.
[0039]
　In FIGS. 1 to 3, as an example, a case where the first soft resin 22 is provided so as to cover the side and bottom surfaces 21-1a of the base member body 21-1 has been described as an example, the first the soft resin 22 may be disposed so as to cover the tip portion 21-1A of at least the base member body 21-1.
[0040]
　The first soft resin 22, for example, its hardness, the hardness of JIS K 7215 Shore A is preferably used soft resin is 90 or less. Such a soft resin, for example, polyolefin elastomer, styrene elastomer, can be exemplified elastomer resin such as polyester elastomer, styrene-based elastomer from the viewpoint of weldability and among them polypropylene (PP) preferred . Specific examples of the styrene-based elastomer, for example, Septon (trade name) manufactured by Kuraray Co., Ltd., can be exemplified RIKEN TECHNOS Reosutoma Co., Ltd. (trade name).
[0041]
　The first soft resin 22, depending on the type of hard resin that constitutes the base member 21 may be selected as appropriate. Specifically, as a hard resin constituting the base member 21, the case of using a polypropylene (PP), as the first soft resin 22, for example, polyolefin elastomer, styrene-based elastomers are preferred, styrene elastomer is more preferable . The combination of the hard resin and the first soft resin 22 constituting the base member 21, with the above combination, to ensure sufficient adhesion between the base member 21 and the first soft resin 22 it can.
[0042]
　The length of the head portion 14 of the above structure (length in the X direction) is not particularly limited, for example, preferably in the range of 10 ~ 30 mm, more preferably in the range of 12 ~ 28mm. When the length of the head portion 14 is 10mm or more, it is possible to secure a sufficient area of ​​the implantable flocking surface 21-1b tresses 12-1. Further, the length of the head portion 14 is 30mm or less, it is possible to improve the operability of the toothbrush 10 in the oral cavity.
[0043]
　The configuration and the width of the head portion 14 (the maximum width in the Y direction of the head portion 14) is not particularly limited, for example, preferably in the range of 7 ~ 13 mm, more preferably in the range of 8 ~ 12 mm. If the width of the head portion 14 is 7mm above can tufts 12-1 to secure a sufficient area of ​​the flocked surface 21-1b to be implanted. Further, if the width of the head portion 14 is 13mm or less, it is possible to improve the operability of the toothbrush 10 in the oral cavity.
[0044]
　Referring now to FIG. 2, the position of the boundary between the tip of the rear end and the neck portion 15 of the head portion 14, and defines the position of the boundary between the tip of the rear and the handle portion 16 of the neck portion 15. In the present invention, between the flocked surface 21-1b and the handle portion 16 includes identical to the maximum width of the width in the Y direction the head portion 14, or a smaller portion than the maximum width of the head portion 14 to the neck portion.
[0045]
　In the present embodiment, in the X direction from the front end of the head portion 14 to the rear end of the handle portion 16, the width in the Y direction becomes narrow, the amount of change in the width is increased, eventually a change in Y direction the width the amount almost no position, the position of the boundary between the tip of the rear end and the neck portion 15 of the head portion 14. Further, in the X direction from the distal end of the neck portion 15 to the rear end of the handle portion 16, the width in the Y direction is widened, the amount of change in the width is increased, eliminating most amount of change in the width in the Y direction eventually located and the position of the boundary between the tip of the rear end and the handle portion 16 of the neck portion 15. In the present invention, the tip farthest position on the rear end side of the handle portion 16 of the deployed flocking holes to a position from the tip of the head portion 14 in the X direction from the head portion 14, and the rear end of the head portion 14 or as the position of the boundary between the distal end of the neck portion 15. The length of the neck portion 15 in the X direction is, for example, can be appropriately set within a range of 20 ~ 70 mm, in this case, the total length of the lengths of the neck portion of the head portion, for example, 40 it can be appropriately set within the range of ~ 85 mm.
[0046]
　The neck portion 15 is a portion for connecting the head portion 14 and the handle portion 16. Further, the neck portion 15, stress characteristics Flexural caused by an external force to the head portion 14 has a deformable portion 15A that deforms shows a plane stress. The width of the neck portion 15 in the Y direction is configured to be narrower than the width of the head portion 14 and handle portion 16. The thickness of the neck portion 15 in the Z direction, for example, can be the same thickness as the thickness of the head portion 14.
[0047]
　Neck 15 has a core 25 which is a component of the rigid member 17, a soft portion 26, a. Core 25 extends in the X direction (the extending direction of the neck portion 15), and a first portion 25-1 which passes through the neck portion 15 extends in the X direction, one end first portion 25-1 and while being integrally has a second portion 25-2 which is arranged in a part of the handle portion 16, a. Here, described for the first portion 25-1 constituting the neck portion 15, the second portion 25-2 will be described when describing the construction of the handle portion 16.
[0048]
　Figure 8 is a cross-sectional view along the line B-B of the rigid members shown in FIG 4. As shown in FIG. 8, a first portion 25-1, tip is integrally formed with the rear end of the base member 21, the rear end is formed integrally with the second portion 25-2 . The first portion 25-1 is constituted by the above-mentioned hard resin. The first portion 25-1 extends in the same thickness in the X direction.
[0049]
　The neck portion 15, when a strong external force is applied to the distal end of the head portion 14, the deformation portion 15A shown in FIG. 2 (e.g., the vicinity of the central portion of the neck portion 15) so as to be bent in (in other words, the head portion 14 so as to release the force applied to the distal end) is formed.
[0050]
　Specifically, the core portion 25 of the deformable portion 15A is at the tip of the head portion 14, for example, when applied X-axis direction of the external force (axial straight load), to bend in the XY plane, first thickness and shape of the portion 25-1 is formed. Core 25 in the modification unit 15A shown in FIG. 8, in the major axis direction is the Z-axis direction, minor axis has a substantially cross-sectional shape of an ellipse (oval) in the Y-axis direction. Core 25 in the modification unit 15A, the maximum thickness of the Y-axis direction is smaller than the maximum thickness of the Z-axis direction, than the second moment second moment about the bending of the Y-axis direction about the bending in the Z-axis direction small Therefore, when the applied axial straight load (bending in the XY plane) bend in the Y-axis direction is generated.
[0051]
　Core 25 has been formed of a hard resin, by reducing the thickness of the Y-axis direction, deformation portion 15A is stress characteristics for bending caused by an external force to the head portion 14, XZ plane perpendicular a Y-axis direction without an external force is applied the Y-axis direction about the stress component (.sigma.y) can be considered to deform shows a plane stress becomes zero. Plane stress, as shown in FIG. 9, a thin flat plate thickness negligible (e.g., film-like) in an approximate stress state of surface facing in the Y direction.
[0052]
　In the structure showing the stress state, since no force is Kakekara in the Y direction, the deformable portion 15A is assumed in the following equation (1) holds in the law of generalized hook.
　σy = τxy = τyz = 0 ... (1)
[0053]
　To deform shows a plane stress described above, as the core 25 of the Y-axis direction of the thickness W2 of the deforming portions 15A, 0.5 mm or more, preferably not more than 2.0 mm. If the Y-axis direction of the thickness W2 of the core portion 25 is less than 0.5mm in the modification unit 15A, the head portion 14 is inserted into the oral cavity becomes difficult leading to a desired tooth surface. Also, when the deformed portion of the core portion 25 in the 15A Y-axis direction of the thickness W2 exceeds 2.0 mm, not show a plane stress, possibly whitening and breakage caused by bending caused by the external force to the head portion 14 there is. Deformable portion 15A in the Y-axis direction of the thickness W2 of the core portion 25 0.5 mm or more in, by a 2.0mm or less, and operability during insertion into the oral cavity, securing plane stress deformation portion 15A it is possible to achieve both the door.
[0054]
　Further, (case deformation portion 15A is substantially elliptical shape shown in FIG. 8, D = W2) the thickness of the bending direction of the deformation portion 15A D, the longest in the cross section perpendicular to the longitudinal direction of the handle portion 16 of the deformable portion 15A (If deformation portion 15A is substantially elliptical shape shown in FIG. 8, L = W1) of the cross-sectional length L when that, in the deformation portion 15A indicates the plane stress may be satisfied the formula (2) .
　D × √2 ≦ L ... (2 )
　In addition, for example, as shown in FIG. 10, when the cross section of the deformable portion 15A is rectangular, the maximum cross-sectional length L, the length of a diagonal line rather than the long side Become.
　To indicate the plane stress is preferably satisfies D × √2 ≦ L, it is more preferable to satisfy D × √5 ≦ L.
[0055]
　Incidentally, if the length of the deformed portion 15A is short, because it does not exhibit plane stress the strength is large with respect to bending, it is preferable deformable portion 15A is longer than 3 mm. Thus, the deformation portion 15 showing a plane stress, for example, when a force is applied to the head portion 14, as shown in FIG. 5, the central portion 15M of the tip base portion 15X1 and distal base 15X2 at the neck portion 15 If is assumed to be a region between the terminal base 15X2.
[0056]
　Further, in order to deform shows a plane stress described above, the Y-axis direction of the core portion 25 in the modified portion 15A, the second moment obtained by the equation defined in accordance with the cross sectional shape of the core portion, 0 .05 ~ 5.8 mm 4 is preferably, 0.05 ~ 3.5 mm 4 particularly preferably. Second moment is 0.05mm in the Y-axis direction of the core part 25 4 is less than the head portion 14 is inserted into the oral cavity becomes difficult leading to a desired tooth surface. Further, the second moment about the Y-axis direction of the core portion 25 is 5.8 mm 4 exceeds not show plane stress, there is a possibility that the whitening and breakage caused by bending caused by the external force to the head portion 14 . The second moment about the Y-axis direction of the core portion 25 in the modified portion 15A, 0.05 ~ 5.8 mm 4 With the operability during insertion into the oral cavity, the plane stress deformation portion 15A it is possible to achieve both the ensuring.
[0057]
　The Z-axis direction of the thickness W1 of the core 25 in the modification unit 15A, when brushing teeth, from the viewpoint of applying firmly press the teeth and interdental like the tip of the brush part 12, the Y-axis direction than the thickness W2 is large, e.g., 1.5 mm ~ 4.5 mm, especially 3.5 mm ~ 4.5 mm is preferred.
[0058]
　Thus, the thickness W1 of the Z-direction in the modified portion 15A, is set to be larger than the Y-direction thickness W2, without reducing the cleaning performance of the toothbrush 10, a strong external force or weak at the distal end of the head portion 14 it is possible to bend in the Y direction in the deformable portion 15A when an external force is applied. Thereby, it becomes possible to release the force applied to the tip of the head portion 14 can be suppressed within the oral cavity of the user of the toothbrush 10 may be damaged.
[0059]
　In particular, if the user of the toothbrush 10 is 1 to 3-year-old infant, in a state plus the toothbrush 10 to the mouth, there is a case to be or running, even when the baby falls down in such a case infants intraoral it is possible to suppress the damage.
[0060]
　Soft portion 26 is composed of a first part 25-1 accommodated therein, and the core portion 25 and the second softer than the hard resin that constitutes the soft resin 27. Soft portion 26, the first portion 25-1 is a member suppresses be exposed, such deformation portion 15A of the neck portion 15 is bent when a strong force is applied to the tip of the head portion 14 a member for. As the second soft resin 27, for example, hardness at JIS K 6253 Shore A can be used soft resin which is a 90 or less. Such soft resin, may be used exemplified soft resin in describing the first soft resin 22.
[0061]
　The second soft resin 27, according to the purpose, may be composed of different types of soft resin and the first soft resin 22. In this case, for example, it may be the hardness of the soft resin to be used as the first soft resin 22 higher than the hardness of the soft resin to be used in the second soft resin 27. With such a configuration, it is possible to vary the hardness of the tip of the head portion 14, and the hardness of the neck portion 15, a. Further, as the first and second soft resin 22 and 27, it may use the same type of soft resin. Thus, it is possible to reduce the number of types of soft resin to be used in manufacturing the toothbrush 10.
[0062]
　Returning to FIGS. 5 and 6, the handle portion 16, a second portion constituting the core portion 25 25-2 (the part of the core portion 25), and a plurality of projecting portions 29 constituting the rigid member 17, the handle a Department body 31, and a ring-shaped recess 32-1 and 32-2. The second portion 25-2 is formed of a hard resin, and one end thereof is integral with the first portion 25-1. Hard resin that constitutes the second portion 25-2, for example, can be used similar to the hard resin that constitutes the first portion 25-1.
[0063]
　The second portion 25-2, in the X-direction, toward the end of the second portion 25-2 in a plurality of columnar protrusions 29, the cross-sectional shape perpendicular to the X direction is continuously expanded similarity It has a configuration in the form. That is, of the second portion 25-2, and is configured such that the diameter of the portion in which a plurality of protrusions 29 are provided is maximized. Also, as in the second portion 25-2, the rear end disposed in side portions of the handle portion 16 than the plurality of projections 29 is directed from a plurality of projecting portions 29 on the rear end side of the handle portion 16, sectional shape perpendicular to the X direction continuously diameter is similar in shape to be smaller.
[0064]
　Thus, among the second portion 25-2, the shape of the arrangement portion on the rear end side of the handle portion 16 than the plurality of protrusions 29, the rear end of the handle portion 16 by a plurality of protrusions 29 by diameter and smaller shape toward, for example, in the case of using the same soft resin as the first and second soft resin 22 and 27, as shown in FIG. 12 to be described later, the second die 51 after placing a rigid member 17 within, when obtained by introducing a soft resin from the rear end side of the second mold 51 in the second mold 51, the direction toward the distal end of the head portion 14 (X-direction) for soft resin is easily moved (flow), the entire hard member 17 (except, flocked surfaces 21-1b, and a plurality of bristle holes 21-1B) can wrap at precisely soft resin. As will be described later, when obtained by introducing the soft resin into the second mold 51, by the introduced soft resin, the position and orientation of the rigid member 17 in the second mold 51 is changed It can be suppressed.
[0065]
　The handle body 31, the user of the toothbrush 10 is a moiety grasping by hand, and a second soft resin 27. Thus, by forming the handle main body 31 in the second soft resin 27, while applying the toothbrush 10 in the mouth, a strong external force in a direction from the rear end of the toothbrush 10 at the tip of the head portion 14 when was deforms the handle body 31 (specifically, bending) it becomes possible. This not only the neck portion 15, the handle body 31 also be bent, a force directed from the rear end of the toothbrush 10 at the tip of the head portion 14, it becomes possible to escape in a direction different from this, toothbrushes 10 the user's mouth in can be prevented from being damaged. Further, by using the second soft resin 27, by forming the handle body 31, even when a strong force is applied to the handle body 31, the handle portion 16 is damaged (in other words, the handle portion 16 can be suppressed to break it) it is.
[0066]
　Brush unit 12 is composed of a tuft 12-1 planted in a plurality of bristle holes 21-1B provided in the base member 21. Hair bundle 12-1 is obtained by bundling a plurality of use hair. The length of the hair bundle 12-1 when based on the flocked surface 21-1b (Hair length) can be determined in consideration of hair stiffness and the like for determining the hair bundle 12-1. Specifically, the length of the hair bundle 12-1 (Hair length), for example, can be appropriately set within a range of 6 ~ 13 mm.
[0067]
　Tufts 12-1, for example, may be constituted by a plurality of use hair length bristles are aligned, may be composed of a plurality of different use bristle lengths of Hair length. In Figure 1, an example of a brush part 12 constituting the toothbrush 10, but the case of aligning the tips of the plurality of tufts 12-1 constituting the brush portion 12 shown as an example, but is not limited thereto. For example, by varying the length of the plurality of tufts 12-1 constituting the brush portion 12, the brush unit 12 may be provided with a step.
[0068]
　Figure 11 is a sectional view showing the manufacturing process of the toothbrush of the present embodiment, it is a view illustrating a step of forming a rigid member with a first die. Figure 12 is a sectional view showing the manufacturing process of the toothbrush of the present embodiment, by using the second mold, the first soft resin, the soft portion, and illustrating a process for forming a handle body it is a diagram of. Further, arrows shown in FIG. 11 show the direction in which the hard resin is introduced, the arrows shown in FIG. 12 shows a direction in which a soft resin (soft resin N to be described later) is introduced.
[0069]
　In the step shown in FIG. 11, it consists a pair of molds 41 - space 43 corresponding to the shape of the rigid member 17 therein, and the inlet 45 for introducing a hard resin in the space 43 providing a first mold 41 having. The mold 41 - protrusion for forming a plurality of bristle holes 21-1B (not shown) is formed. The introduction port 45 is disposed on the rear end side of the space 43. Then, through the inlet port 45, the base material become molten hard resin (flexural modulus (JIS7171) a resin in the range of 500 ~ 3000 MPa) of the rigid member 17 filling the space 43, the rigid resin There by curing, the base member 21 including a plurality of bristle holes 21-1B and the support portion 21-2, the core unit 25, and a plurality of protrusions 29 are formed is a rigid member 17 which is integrated. Then, take out the hard member 17 from the first mold 41.
[0070]
　Then, in a step shown in FIG. 12, it consists pair of molds 51-1 and 51-2, a hard resin into a space 53, and the space 53 corresponding to the shape of the toothbrush 10, except for the brush unit 12 shown in FIG. 1 preparing a second mold 55 having an inlet 55 for introducing. Joining surfaces of the pair of molds 51-1 and 51-2, for example, is set to an intermediate position in the Z direction of the soft part 26 (handle portion main body 31). The mold 51-2, protrusion for forming a plurality of bristle holes 21-1B (not shown) is formed. Also, inlet 55 is disposed on the rear end side of the space 53.
[0071]
　Then, the tip portion of the space 53 of the second die 51, thereby placing the rigid member 17. At this time, as a plurality of bristle holes 21-1B are covered, together with the contacting with the inner surface of the mold 51-2 and flocked surfaces 21-1b, the end faces of the two support portions 21-2 and the die 51-1 of contacting the inner surface, furthermore, a plurality (in this embodiment, four) contacting the projecting surface 29a of the projecting portion 29 of the inner surface of the second mold 51.
[0072]
　Then, through the inlet 55, into the space 53, a soft resin N was melted (hardness JIS K 7215 Shore A is 90 or less of the resin) is filled with. Thereafter, by curing the soft resin N, the first soft resin 22, the soft portion 26, and forms a handle body 31. Thus, the head portion 14, a handle 11 having a neck portion 15, and the handle portion 16 is formed. Then, take out the handle member 11 from inside the second mold 51.
[0073]
　According to the toothbrush of the present embodiment, since the stress characteristics Flexural caused by an external force to the head portion 14 has a deformable portion 15A that deforms shows a plane stress, the user of toothbrush 10 to the mouth in a state in which the added, when a strong external force is applied in a direction from the rear end of the toothbrush 10 at the tip of the head portion 14, by deformation portion 15A is easily deformed (specifically, the bend), the head portion it becomes possible to release the force transmitted to the tip 14, since the first soft resin 22 soft disposed at the distal end of the head portion 14 can be brought into contact with the oral cavity of a user, the toothbrush 10 it is possible to prevent the oral cavity of the user is damaged.
[0074]
　In particular, if the user of the toothbrush 10 is 1 to 3-year-old infant, in a state plus the toothbrush 10 to the mouth, there is a case to be or running, even when the baby falls down in such a case infants intraoral it is possible to suppress the damage.
[0075]
(Flat Evaluation of stress state to deformation portion 15A)
　The test was carried out to check the plane stress deformation portion 15A of the toothbrush 1 with a sample. Samples were performed on different homo PP3 kinds of melt flow rate (MFR). Samples according to the specifications listed in Table 1 for each of the grades were produced by injection molding into a rectangular parallelepiped whose thickness is different.
[0076]
[Evaluation Method]
　for each sample, flexural strength test, the IZOD strength tests were performed according to the specifications listed in Table 2. Bending strength test, as shown in FIG. 13, in a state where support span supported the sample S from below by Shijiko 111 and 112 disposed at a position which is a 64 mm, upper central portion of Shijiko 111 the pushing element 113 having a diameter of 5mm from pressed with compressed distance 30mm by changing the speed. IZOD strength test, as shown in FIG. 14, the distance from the lower end of the sample S L1 to (L1 = 50 mm) and a chuck, the chuck distance L2 (L2 = 20mm) width L3 at a position spaced a (L3 = 15 mm) and applying a load with a hammer HM.

WE claims

Yes a head portion having a bristle face on the tip side is placed on the rear side of the head portion, a handle portion including a handle body, and a neck portion disposed between the flocked surface and the handle portion and,
　wherein the rear end side of the bristle surface, toothbrush stress characteristics flexural caused by an external force to the head portion and having a deformable portion that deforms shows a plane stress.
[Requested item 2]
　The flexible portion, the the direction of the bending perpendicular to the longitudinal direction of the handle portion in parallel to the bristle surface, the toothbrush according to claim 1, wherein the deformation indicates the plane stress.
[Requested item 3]
　A rigid member formed of disposed over a portion of the distal end of the handle portion from the head portion hard resin,
　and houses at least a portion of the hard member inside, and a soft portion made of soft resin ,
　hints,
　the deformable portion, claim 1 or 2 toothbrush wherein said rigid member is disposed on at least a portion of the arrangement region.
[Requested item 4]
　The hard member in the deformation portion, the bending thickness direction is 0.5mm or more and 2mm or less, according to claim 3, wherein the toothbrush, characterized in that the flexural modulus is not less than 500 MPa.
[Requested item 5]
When the bending thickness direction of the hard member in the deformed portion D, of the hard member in the deformation portion, the maximum cross-sectional length in a cross section perpendicular to the length direction of the handle portion and L,
　　D × √ 2 ≦ L
claim 4 toothbrush according to satisfies the relationship.
[Requested item 6]
　Wherein the bending moment of inertia of about direction of said hard member at the deformed portion is, 0.05 mm 4 or more, 5.8 mm 4 toothbrush according to claim 4 or 5, wherein the or less.
[Requested item 7]
　The hard member in the deformation portion, the cross-sectional shape is square, rectangular, polygonal, toothbrush according to any one of claims 3 6, characterized in that either elliptical.
[Requested item 8]
　The hard resin may toothbrush according to any one of claims 3 7, characterized in that the polypropylene.
[Requested item 9]
　Has a head portion having a bristle face on the tip side is placed on the rear side of the head portion, a handle portion including a handle body, and a neck portion disposed between the flocked surface and the handle portion a step of designing a toothbrush,
　and a step of molding the toothbrush designed,
　the step of designing the toothbrush, deformation stress characteristics flexural caused by an external force to the head portion is deformed shows a plane stress part a toothbrush manufacturing method which comprises a design of placing on the rear end side of the flocked surface.