toothbrush

Abstract

The purpose of the present invention is to provide a toothbrush that can deform over a broad range rather than locally while maintaining a stabilized grip feel. The present invention has a head part that is positioned toward the distal-end side in the long-axis direction and that has a bristle implantation surface, a gripping part that is disposed farther toward the rear end than the head part, and a neck part that is disposed between the head part and the gripping part. The neck part and the gripping part each have a hard section that is formed from a hard resin, and a soft section that is formed from a soft resin and that covers at least part of the hard section. In the neck part, the entire circumference of the hard section, in an area that spans to the position of the boundary with the gripping part and that is at least 70% of the long-axis-direction length of the neck part, is covered by the soft section. In a cross-section orthogonal to the long-axis direction, the value represented by S2 / S1 is 4.5-6.0 (inclusive), where A is the position of an end section of the neck part on the long-axis-direction distal-end side of the soft section, S1 is the cross-sectional area of the soft section at the position A, C is the position of the boundary in the long-axis direction, and S2 is the cross-sectional area of the soft section at the position C.

Description

[Technical Field]

[0001] The present invention relates to a toothbrush. This application claims priority based on Japanese Patent Application No. 2020-208534, filed on December 16, 2020, the contents of which are incorporated herein by reference. [Background technology]

[0002] When brushing your teeth, it is generally recommended to brush gently and carefully with a light brushing force, brushing each tooth carefully and gently. Therefore, it is preferable for the handle to have a moderate degree of elasticity (flexibility). On the other hand, if the toothbrush handle is too soft, it will not transmit force well and will be uncomfortable to use, so it is necessary for it to be able to be gripped firmly.

[0003] Therefore, measures have been taken to impart elasticity, such as using highly elastic hard resins and narrowing the neck.In addition, for grips, a structure has been devised that makes the neck or gripping part more flexible by combining elastomers and hard resins.

[0004] For example, Patent Document 1 discloses a toothbrush that reduces brushing pressure by combining an elastomer with the boundary cross section between the neck and grip. Patent Document 2 discloses a toothbrush that has deformability in two places by having a spherical structure at the boundary between the head and neck and a bellows structure in the neck. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-4944 [Patent Document 2] US Patent Application Publication No. 2013 / 0340189 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if deformation occurs in one or two places between the neck and the grip, the force applied to the grip is locally weakened, causing discomfort when brushing and making the toothbrush unusable.In addition, the stress is locally concentrated, which can cause problems such as insufficient strength to break or plastic deformation over long-term use.

[0007] The present invention has been made in consideration of the above points, and has as its object to provide a toothbrush that can be deformed over a wide range rather than just locally while maintaining a stable grip. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided a toothbrush comprising: a head portion located at the tip end in the longitudinal direction and having a bristle-implanted surface; a grip portion located rearward of the head portion; and a neck portion located between the head portion and the grip portion, wherein the neck portion and the grip portion each have a hard portion formed of a hard resin and a soft portion formed of a soft resin that covers at least a portion of the hard portion, and the neck portion is covered entirely by the soft portion for at least 70% of the length of the neck portion in the longitudinal direction and up to the boundary position with the grip portion, and in a cross section perpendicular to the longitudinal direction, where A is the position of the end of the soft portion in the neck portion at the tip end in the longitudinal direction, S1 is the cross-sectional area of ​​the soft portion at position A, C is the boundary position in the longitudinal direction, and S2 is the cross-sectional area of ​​the soft portion at position C, the value expressed by S2 / S1 is 4.5 or more and 6.0 or less.

[0009] Furthermore, in the toothbrush according to one aspect of the present invention, when the total cross-sectional area of ​​the neck portion perpendicular to the longitudinal axis direction at the boundary position is S3 and the cross-sectional area of ​​the hard portion is S4, the value expressed by S3 / S4 is 2.0 or more and 4.0 or less.

[0010] Furthermore, in the toothbrush according to one aspect of the present invention, the grip portion has a finger rest portion on the front side facing the bristle surface in a thickness direction perpendicular to the bristle surface, and in the cross section, the finger rest portion has a flat shape whose length in the width direction perpendicular to the longitudinal axis and the thickness direction is longer than its length in the thickness direction.

[0011] Furthermore, in the toothbrush according to one aspect of the present invention described above, when viewed from the side in the width direction, the finger rest portion has a convex apex on the front side, and a concave curved surface from the apex toward the rear end with a center of curvature on the front side, and when viewed from the front side, the width between the outer contour lines in the width direction expands from the boundary position to a position where the finger rest portion has the maximum width, and the hard portion of the finger rest portion is exposed on the front side, and the soft portion covers the hard portion on both side surfaces in the width direction sandwiching the finger rest portion, beyond the boundary position to the position where the soft portion reaches the maximum width.

[0012] Furthermore, in the toothbrush according to one aspect of the present invention described above, the soft portion is characterized in that it extends beyond the boundary position toward the rear end at least on the rear side opposite the front side in the thickness direction.

[0013] Furthermore, in the toothbrush according to one aspect of the present invention, the following are sequentially arranged from the neck portion toward the rear end of the grip portion: a first region in which the soft portion covers the entire circumference of the hard portion; a second region in which the soft portion covers the hard portion only on the side and back sides; and a third region in which the soft portion covers the hard portion only on the back side.

[0014] In addition, in the toothbrush according to one aspect of the present invention described above, the grip portion at the position of maximum width has, in the cross section, a first surface portion facing the front side and extending in the width direction, and second surface portions whose intersections with the first surface portion form ridge lines and which slope toward the back side opposite the front side in the thickness direction as they move outward in the width direction from the intersection points, and the distance between the ridge lines in the width direction gradually decreases from the position of maximum width toward the rear end, and then gradually increases until the position where the thickness of the grip portion is at its maximum.

[0015] Furthermore, in the toothbrush according to one aspect of the present invention, the intersection angle between the pair of second surface portions, which indicates the range occupied by the hard portion in the cross section, is characterized in that it gradually decreases from the position where the distance between the ridge lines in the width direction is smallest toward the position where the thickness of the grip portion is greatest.

[0016] Furthermore, in the toothbrush according to one embodiment of the present invention described above, when the thickness of the soft portion located on the back side opposite the bristle implantation surface in the thickness direction perpendicular to the bristle implantation surface in the cross section at position A is defined as A1, the thickness of the soft portion located outside the hard portion in the width direction perpendicular to the longitudinal axis and the thickness direction is defined as A2, and when the thickness of the soft portion located on the back side in the thickness direction in the cross section at position C is defined as C1, and the thickness of the soft portion located outside the hard portion in the width direction is defined as C2, the toothbrush is characterized in that the relationship (C2 / A2) / (C1 / A1)>2.5 is satisfied.

[0017] In the toothbrush according to one aspect of the present invention, the thickness C2 is 2.7 mm or more and 4.0 mm or less, and the thickness C1 is 0.7 mm or more and 1.5 mm or less.

[0018] Furthermore, in the toothbrush according to one aspect of the present invention, when the maximum thickness of the neck portion at position A is A11, the maximum thickness of the hard portion is A12, the maximum width of the neck portion at position A is A21, the maximum width of the hard portion is A22, the maximum thickness of the neck portion at position C is C11, the maximum thickness of the hard portion is C12, and the maximum width of the neck portion at position C is C21, the maximum width of the hard portion is C22, the value represented by (C12 / C11) / (A12 / A11) is 0.95 or more and 1.15 or less, and the value represented by (C22 / C21) / (A22 / A21) is 0.70 or more and 0.90 or less. [Effects of the Invention]

[0019] The present invention can provide a toothbrush that can be deformed over a wide range, rather than just locally, while maintaining a stable grip. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing an embodiment of the present invention, and is a side view showing the configuration of a toothbrush 1. FIG. [Figure 2] FIG. 2 is a front view of the toothbrush 1 as seen from the bristle surface 3a side. [Figure 3] FIG. 2 is a rear view of the toothbrush 1 as seen from the rear side. [Figure 4] 2 is a cross-sectional view taken at a position A and perpendicular to the longitudinal axis direction of the neck portion 4. FIG. [Figure 5] 2 is a cross-sectional view perpendicular to the longitudinal axis direction of neck portion 4 at position C, which indicates the boundary between neck portion 4 and grip portion 5. FIG. [Figure 6] 10 is a cross-sectional view of the grip portion 5 at a position D where the finger rest portion 50 is at its widest. [Figure 7] 10 is a cross-sectional view of the grip portion 5 at a position F where the ninth curve region E9 shows a minimum value in a front view. FIG. [Figure 8] 10 is a cross-sectional view of the grip portion 5 at a position H where the thickness of the grip portion 5 is greatest from the rear end of the portion where the pair of ridge lines 57 have a constant width. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the toothbrush of the present invention will be described with reference to FIGS. The following embodiment shows one aspect of the present invention, does not limit the present invention, and can be modified as desired within the scope of the technical concept of the present invention. In addition, in the following drawings, the scale and number of each structure are different from the actual structure to make each configuration easier to understand.

[0022] In the following description, the side of the head portion 3 on which the bristle implantation surface 3a (described later) is provided (the side opposite the bristle implantation surface) is referred to as the front side of the toothbrush 1, and the side of the head portion 3 opposite the side on which the bristle implantation surface 3a faces is referred to as the back side of the toothbrush 1. Additionally, the direction in which the brush body 2 extends is referred to as the long axis direction, the direction parallel to the bristle implantation surface 3a and perpendicular to the long axis direction is referred to as the width direction of the toothbrush 1, and the direction perpendicular to the bristle implantation surface 3a is referred to as the thickness direction of the toothbrush 1. In addition, the side on the long axis on which the head portion 3 is provided (the head portion side) is referred to as the leading end side, and the side on which the grip portion 5 is provided (the grip portion side) is referred to as the rear end side, as appropriate.

[0023] FIG. 1 is a side view showing the configuration of toothbrush 1. As shown in FIG. 2 is a front view of the toothbrush 1 as seen from the bristle implantation surface 3a side. Note that the brush 40 is not shown in FIG. Fig. 3 is a rear view of the toothbrush 1. In Fig. 2, the brush 40 is not shown.

[0024] 1 to 3, toothbrush 1 of this embodiment includes brush body 2 made of a resin molded body formed into an elongated shape as a whole, and brush 40. The total length of toothbrush 1 is, for example, 180 mm or more and 200 mm or less.

[0025] The brush body 2 has a head portion 3 located at the tip end and having a bristle-implanted surface 3a, a handle portion 5 located rearward of the head portion 3, and a neck portion 4 located between the head portion 3 and the handle portion 5. The toothbrush 1 is capable of cleaning the oral cavity with a brush 40 having multiple bristle bundles (not shown) planted on the bristle-implanted surface 3a of the head portion 3.

[0026] The brush body 2 has a hard portion 60 made of hard resin and a soft portion 70 made of soft resin. The hard portion 60 extends in the longitudinal direction. The hard portion 60 forms at least a part of the head portion 3, the neck portion 4, and the grip portion 5. The hard portion 60 includes a hard portion 63 located in the head portion 3, a hard portion 64 located in the neck portion 4, and a hard portion 65 located in the grip portion 5.

[0027] The soft portion 70 covers at least a portion of the hard portion 60 in the head portion 3, the neck portion 4, and the grip portion 5. The soft portion 70 includes a soft portion 73 located in the head portion 3, a soft portion 74 located in the neck portion 4, and a soft portion 75 located in the grip portion 5.

[0028] An example of a hard resin is a resin having a flexural modulus (JIS7171) of 1000 MPa or more and 2800 MPa or less. For example, polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, etc. are preferably used in consideration of strength.

[0029] The soft resin more preferably has a Shore hardness A of 30 or more and 80 or less. Examples of the soft resin include elastomers (for example, olefin-based elastomers, styrene-based elastomers, polyester-based elastomers, polyurethane-based thermoplastic elastomers, etc.) and silicones.

[0030] (Outline shape of the front side of the brush body) 1, when the toothbrush 1 of this embodiment is viewed from the side, the toothbrush body 2 has, on the outer contour line on the front side of the brush body 2, a first linear region L1 that extends linearly from the bristle surface 3a of the head portion 3 toward the grip portion 5 from the rear end side of the head portion 3 toward the rear end, a first curved region E1 that has a center of curvature on the front side and extends in an arc from the rear end of the first linear region L1 toward the rear end to a convex vertex 51, and a second curved region E2 that has a center of curvature on the front side and extends in an arc from the vertex 51 toward the rear end. Additionally, the toothbrush 1 has, on the front side in side view, a third curved region E3 that has a center of curvature on the rear side and extends in an arc from the rear end of the second curved region E2 toward the rear end.

[0031] (Outline shape of the back side of the brush body) When the toothbrush 1 of this embodiment is viewed from the side of the brush body 2, the outer contour line on the back side of the brush body 2 has a second straight region L2 that extends linearly from the back side of the head portion 3 toward the handle portion 5, continuing from the back side of the head portion 3 toward the rear end, a fourth curved region E4 that has a center of curvature on the front side and extends in an arc from the rear end side of the second straight region L2 toward the rear end, a fifth curved region E5 that has a center of curvature on the back side and extends in an arc from the rear end of the fourth curved region E4 to vertex 51A toward the rear end, and a sixth curved region E6 that has a center of curvature on the back side and extends in an arc from vertex 51A toward the rear end.

[0032] (Outline shape of both sides of the brush body in the width direction) As shown in Fig. 2, when the toothbrush 1 of this embodiment is viewed from the front, the outer contour lines on both sides of the brush body 2 in the width direction are formed symmetrically with respect to a center line that is located in the center of the width direction and extends in the longitudinal direction. Therefore, the following explanation will focus on the outer contour line on one side in the width direction (the lower side in Fig. 2). Furthermore, with regard to the position of the center of curvature of the curved region that extends in an arc shape, the position on the center side of the outer contour line in the width direction will be referred to as the inside, and the position on the opposite side of the center in the width direction will be referred to as the outside.

[0033] When the toothbrush 1 of this embodiment is viewed from the front, the brush body 2 has, along its widthwise contour, a third linear region L3 extending linearly from the boundary between the head portion 3 and the neck portion 4 (described in detail below) toward the rear end to position B; a seventh curved region E7 having an outer center of curvature and extending in an arc from position B toward the rear end; an eighth curved region E8 having an inner center of curvature and extending in an arc from the rear end of the seventh curved region E7 toward the rear end; a ninth curved region E9 having an outer center of curvature and extending in an arc from the rear end of the eighth curved region E8 toward the rear end; and a tenth curved region E10 having an inner center of curvature and extending in an arc from the rear end of the ninth curved region E9 toward the rear end. The neck portion 4 of the toothbrush 1 of this embodiment extends at a constant width from position J of the boundary with the head portion 3 (described in detail below) to position B. That is, position B is the end position on the rear end side where the width of the neck portion 4 is constant.

[0034] (head section) The head portion 3 is a portion that cleans the oral cavity with multiple bristle bundles, and is generally rectangular with rounded corners as shown in Fig. 2. The head portion 3 has a generally rectangular flat plate shape with four vertices that are rounded off by curved lines when viewed from the front. In this embodiment, the boundary between the head portion 3 and the neck portion 4 is the end point of the curve that forms the corner cutoff on the neck portion 4 side when viewed from the front of the head portion 3, i.e., the position where the bending direction of the curve that forms the corner cutoff changes.

[0035] The head portion 3 has a bristle implantation surface 3a on the front side. A plurality of bristle implantation holes 6 are arranged in a row on the bristle implantation surface 3a. The shape and diameter of the bristle implantation holes 6 are not particularly limited, and FIG. 2 shows, as an example, bristle implantation holes 6 that are circular in front view and have the same diameter. The bristle implantation holes 6 are arranged in a plurality of rows (2 to 4 rows in FIG. 2) spaced apart in the width direction according to the width direction length of the head portion 3, and are spaced apart in the longitudinal direction (10 rows in FIG. 2). In each of the bristle implantation holes 6, bristles that make up the brush 40 are implanted.

[0036] The bristle bundles are formed by bundling a number of bristles (filaments) together, folding them in half, and inserting a metal stopper (not shown) called a flat wire between them before driving the bristle bundle into the bristle hole 6. The shape of the head 3 is not particularly limited, and for example, the bristle implantation surface 3a on the front side and the surface on the back side form flat, parallel surfaces.

[0037] The head portion 3 may have any shape and size that allows easy brushing of the oral cavity, and is not particularly limited in shape, and may have, for example, a shape that gradually narrows from the base end toward the tip end. The head portion 3 may also have a tapered shape that gradually thins from the base end toward the tip end, or may have a rounded shape with a raised center on the back side of the head portion 3.

[0038] The width of the head portion 3 is not particularly limited, and is preferably, for example, 7 mm or more and 16 mm or less. If the width is equal to or more than the above lower limit, a sufficient area for planting tufts of hair can be secured, and if the width is equal to or less than the above upper limit, operability in the oral cavity can be further improved.

[0039] The length of the head portion 3 in the longitudinal direction is not particularly limited, and is preferably, for example, 10 mm or more and 33 mm or less. If the length of the head portion 3 is equal to or more than the above-mentioned lower limit, a sufficient area for planting tufts of hair can be secured, and if it is equal to or less than the above-mentioned upper limit, operability in the oral cavity can be further improved.

[0040] The thickness of the entire area of ​​the head portion 3 is not particularly limited, but as an example, it is preferably 3.0 mm or more and 6.0 mm or less. If the thickness of the head portion 3 is equal to or more than the above-mentioned lower limit, the strength of the head portion 3 can be further increased. If the thickness of the head portion 3 is equal to or less than the above-mentioned upper limit, it is possible to improve the reachability to the back of the molars and to improve the operability in the oral cavity.

[0041] As shown in FIGS. 1 and 3, a portion of the hard portion 63 on the rear side of the head unit 3 is covered with a soft portion 73. The soft portion 73 completely covers the area from the tip end of the head unit 3 beyond the center, and partially covers the central portion in the width direction from the tip end to the rear end. The soft portion 73 has multiple scrapers 73A and multiple scrapers 73B protruding toward the rear side. The scrapers 73A are V-shaped ribs that expand from the tip end to the rear end and are arranged at intervals in the longitudinal direction. The scrapers 73B are linear protrusions that are arranged in a scattered manner. Note that the shapes of the scrapers 73A and 73B are merely examples and are not particularly limited. Furthermore, the head unit 3 may be configured without the scrapers 73A and 73B.

[0042] (Neck) The neck portion 4 is disposed between the grip portion 5 and the head portion 3 and connects the grip portion 5 and the head portion 3. The boundary between the neck portion 4 and the grip portion 5 is position C where the seventh curved region E7 and the eighth curved region E8 intersect in a front view. In other words, this is the position where the change in the curve direction begins when the seventh curved region E7, which has a center of curvature on the outside, connects to the eighth curved region E8, which has a center of curvature on the inside. The distance in the major axis direction from the tip of the head portion 3 to position C is preferably 65 mm or more and 85 mm or less.

[0043] The neck portion 4 has a constant minimum width in the region from the boundary with the head portion 3 toward the grip portion 5 to position B, where the contour line is formed by the third linear region L3 in the front view of FIG. 2. The neck portion 4 has a minimum width in the region from position B to position C, where the contour line is formed by the seventh curved region E7, and the width gradually increases from this minimum width. From the viewpoint of usability, the minimum width of the neck portion 4 is preferably 4.5 mm or more and 6.0 mm or less. From the viewpoint of usability, the maximum width of the neck portion 4 is preferably 14.0 mm or more and 15.5 mm or less.

[0044] The neck portion 4 has a minimum thickness from the boundary with the head portion 3 toward the grip portion 5, where the contour line is formed by the first linear region L1 and the second linear region L2 in the side view of FIG. 1 , and the thickness gradually increases from the minimum thickness to a position C where the contour line is formed by the first curved region E1 and the fourth curved region E4. From the viewpoint of usability, the minimum thickness of the neck portion 4 is preferably 4.5 mm or more and 6.0 mm or less. From the viewpoint of usability, the maximum thickness of the neck portion 4 is preferably 9.0 mm or more and 12.5 mm or less.

[0045] The neck portion 4 is covered with the soft portion 74 over the entire circumference of the hard portion 64 from position A, which is closer to the head portion 3 than the center position of the neck portion 4 in the longitudinal direction, to position C, which is 70% or more of the length of the neck portion 4 in the longitudinal direction and is the boundary position with the grip portion 5. The position A in the longitudinal direction is preferably 33 to 45 mm from the tip of the head portion 3.

[0046] If the cross-sectional area of ​​the soft portion 74 at position A is S1 and the cross-sectional area of ​​the soft portion 74 at position C is S2, the value represented by S2 / S1 is preferably 4.5 or more and 6.0 or less, more preferably 4.8 or more and 5.7 or less, and particularly preferably 5.1 or more and 5.5 or less. Furthermore, it is preferably 4.5 or more, more preferably 4.8 or more, and particularly preferably 5.1 or more. Furthermore, it is preferably 6.0 or less, more preferably 5.7 or less, and particularly preferably 5.5 or less. If the value expressed by S2 / S1 is less than 4.5, the neck portion 4 may be deformed too much at a position close to the grip portion 5. If the value expressed by S2 / S1 exceeds 6.0, the neck portion 4 may be deformed too much at a position close to the grip portion 5. Also, the neck portion 4 may be deformed too much at a position close to the head portion 3. By setting the value expressed by S2 / S1 to be 4.5 or more and 6.0 or less, the center of deformation is placed at the tip side of the neck portion 4, and the soft portion 74 is used as a reinforcing material to control the ease of bending so that the degree of deformation decreases toward the grip portion 5. Also, the cross-sectional area S1 is 8 mm 2 That's it, 22mm 2 Less than 10mm is preferable 2 Over 20mm 2 Less than 12mm is preferable 2 That's it, 18mm 2 The following is even more preferred: The cross-sectional area S2 is 60 mm 2 Above, 60mm 2 Less than 65mm is preferable 2 Above, 85mm 2 Less than 70mm is preferable 2 Above, 80mm 2 The following is even more preferred:

[0047] Furthermore, if the total cross-sectional area of ​​the neck portion 4 at position C is S3 and the cross-sectional area of ​​the hard portion 64 is S4, the value represented by S3 / S4 is preferably 2.0 or more and 4.0 or less, more preferably 2.4 or more and 3.6 or less, and particularly preferably 2.7 or more and 3.3 or less. Furthermore, it is preferably 2.0 or more, more preferably 2.4 or more, and particularly preferably 2.7 or more. Furthermore, it is preferably 4.0 or less, more preferably 3.6 or less, and particularly preferably 3.3 or less. If the value expressed by S3 / S4 is less than 2.0, the deformation of the neck portion 4 at a position close to the grip portion 5 may be too small. If the value expressed by S3 / S4 exceeds 4.0, the deformation of the neck portion 4 at a position close to the grip portion 5 may become too large. In addition, the cross-sectional area S3 is 100 mm 2 Above, 130mm 2 Less than 105mm is preferable 2 Above, 125mm 2 Less than 110mm is preferable2 Above, 120mm 2 The following is even more preferred: The cross-sectional area S4 is 25 mm 2 Above, 55mm 2 Less than 30mm is preferable 2 Above 50mm 2 Less than 35mm is preferable 2 Above, 45mm 2 The following is even more preferred:

[0048] FIG. 4 is a cross-sectional view taken at position A and perpendicular to the longitudinal axis of the neck portion 4. As shown in FIG. FIG. 5 is a cross-sectional view taken at position C, perpendicular to the longitudinal axis of the neck portion 4. As shown in FIG. As shown in FIG. 4, in the cross section at position A, the thickness of the soft portion 74 located on the back side of the hard portion 64 is defined as A1, and the thickness of the soft portion 74 located on the outer side of the hard portion 64 in the width direction is defined as A2. As shown in Figure 5, in the cross section at position C, if the thickness of the soft portion 74 located on the back side of the hard portion 64 is C1 and the thickness of the soft portion 74 located on the widthwise outer side of the hard portion 64 is C2, the value expressed by (C2 / A2) / (C1 / A1) is preferably greater than 2.5, more preferably greater than 2.5 and less than 3.8, more preferably 3.0 or greater and 3.6 or less, and particularly preferably 3.2 or greater and 3.4 or less. Moreover, it is preferably more than 2.5, more preferably 3.0 or more, and particularly preferably 3.2 or more. Furthermore, it is preferably less than 3.8, more preferably 3.6 or less, and particularly preferably 3.4 or less. If the value expressed by (C2 / A2) / (C1 / A1) is 3.8 or more, the wall thickness becomes excessively thick, which may make it difficult to deform in the width direction.

[0049] When the value expressed by (C2 / A2) / (C1 / A1) is 2.5 or less, the thickness of the soft portion 74 in the width direction is thin, and the soft portion 74 is therefore prone to deformation in the width direction. When the value expressed by (C2 / A2) / (C1 / A1) exceeds 2.5, deformation in the minor axis (width) direction is suppressed. The thickness A1 is preferably 0.7 mm or more and 1.3 mm or less, more preferably 0.8 mm or more and 1.2 mm or less, and even more preferably 0.9 mm or more and 1.1 mm or less. The thickness A2 is preferably 0.7 mm or more and 1.3 mm or less, more preferably 0.8 mm or more and 1.2 mm or less, and even more preferably 0.9 mm or more and 1.1 mm or less.

[0050] The value represented by C1 / A1 is preferably 0.9 or more and 2.0 or less, and more preferably 1.1 or more and 1.15 or less. The value represented by C2 / A2 is preferably 2.0 or more and 5.0 or less, and more preferably 2.5 or more and 4.0 or less. The value represented by C1-A1 is preferably 0 mm or more and 0.6 mm or less. The value represented by C2-A2 is preferably 1.8 mm or more and 3.5 mm or less.

[0051] The thickness C1 is preferably 0.7 mm or more and 1.5 mm or less. If the thickness C1 is less than 0.7 mm, the deflection in the thickness direction will be large, which may result in a decrease in the feel when hitting the ball and poor grip. If the thickness C1 exceeds 1.5 mm, the deformability of the head portion 3 when pressure is applied to the back side may decrease. By setting the thickness C1 to 0.7 mm or more and 1.5 mm or less, it is possible to improve the feel when hitting the ball and the grip while maintaining the deformability when pressure is applied to the back side. The thickness C1 is preferably 0.7 mm or more and 1.7 mm or less, more preferably 0.8 mm or more and 1.5 mm or less, and even more preferably 0.9 mm or more and 1.3 mm or less.

[0052] The thickness C2 is preferably 2.5 mm or more and 4.5 mm or less, more preferably 2.7 mm or more and 4.0 mm or less, and even more preferably 3.0 mm or more and 3.8 mm or less. If the thickness C2 is less than 2.5 mm, the deflection in the width direction may be large, which may result in a decrease in the feel of the club and poor grip. If the thickness C2 exceeds 4.5 mm, the deformability in the width direction may decrease when pressure is applied to the back side of the head portion 3. By setting the thickness C2 to 2.5 mm or more and 4.5 mm, it is possible to improve the feel of the club and grip while maintaining the deformability in the width direction.

[0053] The minimum width of the rigid portion 64 in the neck portion 4 is preferably 3.0 mm or more and 4.0 mm or less. The maximum width of the rigid portion 64 in the neck portion 4 is preferably 7.0 mm or more and 8.5 mm or less.

[0054] The minimum thickness of the hard portion 64 in the neck portion 4 is preferably 3.0 mm or more and 4.0 mm or less. The maximum thickness of the hard portion 64 in the neck portion 4 is preferably 6.0 mm or more and 7.5 mm or less. As an example, the thickness of the neck portion 4 at a position 37 mm from the tip of the head portion 3, which is located halfway through the neck portion 4, is preferably 3.3 mm or more and 3.5 mm or less. As an example, the thickness of the neck portion 4 at a position 56 mm from the tip of the head portion 3 is preferably 4.2 mm or more and 4.5 mm or less. As an example, the thickness of the neck portion 4 at a position 77 mm from the tip of the head portion 3 is preferably 8.7 mm or more and 8.9 mm or less. By setting the thickness of the hard portion 64 in the neck portion 4 within the above range, the entire neck portion 4 from the middle becomes a tapered shape that is easy to bend.

[0055] As shown in Fig. 4, at position A, the maximum thickness of neck portion 4 is A11, the maximum thickness of rigid portion 64 is A12, the maximum width of neck portion 4 is A21, and the maximum width of rigid portion 64 is A22. As shown in Fig. 5, at position C, the maximum thickness of neck portion 4 is C11, the maximum thickness of rigid portion 64 is C12, the maximum width of neck portion 4 is C21, and the maximum width of rigid portion 64 is C22.

[0056] The value represented by (C12 / C11) / (A12 / A11) is preferably 0.95 or more and 1.15 or less, more preferably 0.97 or more and 1.10 or less, and particularly preferably 1.00 or more and 1.05 or less. Furthermore, it is preferably 0.95 or more, more preferably 0.97 or more, and particularly preferably 1.00 or more. Furthermore, it is preferably 1.15 or less, more preferably 1.10 or less, and particularly preferably 1.05 or less. If the value expressed by (C12 / C11) / (A12 / A11) is less than 0.95, the deflection will be too large, which may result in a decrease in the feel of the ball and poor grip. If the value expressed by (C12 / C11) / (A12 / A11) exceeds 1.15, the soft portion 74 becomes too thin and is less likely to bend in the width direction, which may reduce flexibility. By setting the value expressed by (C12 / C11) / (A12 / A11) to be 0.95 or more and 1.15 or less, it is possible to improve the feel and grip while suppressing a decrease in flexibility. The thickness A11 is preferably 4.8 mm or more and 5.8 mm or less, more preferably 5.0 mm or more and 5.6 mm or less, and even more preferably 5.2 mm or more and 5.4 mm or less. The thickness A12 is preferably 3.0 mm or more and 3.8 mm or less, more preferably 3.2 mm or more and 3.6 mm or less, and even more preferably 3.3 mm or more and 3.5 mm or less. The thickness C11 is preferably 10.8 mm or more and 12.2 mm or less, more preferably 11.0 mm or more and 12.0 mm or less, and even more preferably 11.2 mm or more and 11.8 mm or less. The thickness C12 is preferably 7.1 mm or more and 8.3 mm or less, more preferably 7.3 mm or more and 8.1 mm or less, and even more preferably 7.5 mm or more and 7.9 mm or less.

[0057] The value represented by (C22 / C21) / (A22 / A21) is preferably 0.70 or more and 0.90 or less, more preferably 0.74 or more and 0.86 or less, and particularly preferably 0.77 or more and 0.83 or less. Furthermore, it is preferably 0.7 or more, more preferably 0.74 or more, and particularly preferably 0.77 or more. Furthermore, it is preferably 0.90 or less, more preferably 0.86 or less, and particularly preferably 0.83 or less. If the value expressed by (C22 / C21) / (A22 / A21) is less than 0.70, the deflection will be too large, which may result in a decrease in the feel at impact and poor grip. If the value expressed by (C22 / C21) / (A22 / A21) exceeds 0.90, the change in thickness of the soft portion 74 is small, so that the entire body is rigid and difficult to bend as a single unit, and flexibility may also decrease. By setting the value expressed by (C22 / C21) / (A22 / A21) to be 0.70 or more and 0.90 or less, it is possible to improve the feel and grip while suppressing a decrease in flexibility. The width A21 is preferably 4.8 mm or more and 5.8 mm or less, more preferably 5.0 mm or more and 5.6 mm or less, and even more preferably 5.2 mm or more and 5.4 mm or less. The width A22 is preferably 3.0 mm or more and 3.8 mm or less, more preferably 3.2 mm or more and 3.6 mm or less, and even more preferably 3.3 mm or more and 3.5 mm or less. The width C21 is preferably 12.1 mm or more and 13.6 mm or less, more preferably 12.4 mm or more and 13.3 mm or less, and even more preferably 12.7 mm or more and 13.0 mm or less. The width C22 is preferably 5.8 mm or more and 7.3 mm or less, more preferably 6.1 mm or more and 7.0 mm or less, and even more preferably 6.4 mm or more and 6.7 mm or less.

[0058] The value represented by A12 / A11 is preferably 0.6 or more and 0.8 or less. The value represented by A22 / A21 is preferably 0.6 or more and 0.8 or less. The value represented by C12 / C11 is preferably 0.6 or more and 0.9 or less. The value represented by C22 / C21 is preferably 0.4 or more and 0.6 or less.

[0059] The neck portion 4 is fixed at position C, which is the boundary between the neck portion 4 and the grip portion 5, and when a 200 g weight is attached to the center of the head portion 3 in the width direction and the longitudinal direction and hung for 10 seconds, the parting line position at the tip of the head is deformed by 6 to 9 mm.

[0060] As long as the above values ​​are satisfied, the cross-sectional shape of the neck portion 4 is preferably substantially square, substantially polygonal, perfect circle, or ellipse.

[0061] (gripping part) The grip portion 5 is the portion that is gripped by the user, and is formed in a long columnar shape. The grip portion 5 gradually widens (expands) in width from position C, the boundary with the neck portion 4, toward the rear end to position D, where the outer contour line of the eighth curved region E8 indicates a maximum value in a front view. The outer contour line on the rear end side gradually narrows in width from position D, where the eighth curved region E8 indicates a maximum value in a front view, to position F, where the ninth curved region E9 indicates a minimum value. The outer contour line on the rear end side gradually widens in width from position F, where the ninth curved region E9 indicates a minimum value in a front view, to position G, where the tenth curved region E10 indicates a maximum value. The grip portion 5 of this embodiment has a maximum width at position G, where the tenth curved region E10 indicates a maximum value. The outer contour line on the rear end side gradually narrows in width from position G, where the tenth curved region E10 indicates a maximum value in a front view, to the end of the rear end.

[0062] The thickness of the grip portion 5 gradually decreases from position C at the boundary with the neck portion 4 toward the rear end in side view in Figure 1 to position E where the outer contour line in side view has a minimum value of the second curved region E2 and the grip portion 5 has a minimum thickness. Position E is preferably 70 to 90 mm from the tip of the head portion 3. The thickness of the outer contour line on the rear end side gradually increases from position E, where the second curved region E2 shows its minimum value in a side view, to position H, where the third curved region E3 and the sixth curved region E6 show their maximum values. The grip portion 5 of this embodiment has its maximum thickness at position H. The thickness of the outer contour line on the rear end side gradually decreases from position H to the end portion on the rear end side.

[0063] The grip portion 5 has, on the front side, a finger rest 50 on which the thumb rests, for example. In a side view, the finger rest 50 is formed in a second curved region E2 that is a concave curved surface that extends from the apex 51 toward the rear end to a position E toward the rear side. Providing the concave curved surface in the finger rest 50 allows the finger rest 50 to exhibit flexibility when pressure is applied to the rear side.

[0064] The finger rest portion 50 has a convex apex 51 and a flat shape, so that it can be adjusted to prevent excessive bending in the thickness direction, and can transmit appropriate flexibility to the grip portion 5 side. Furthermore, by providing the convex vertex 51, the thickness of the soft portion 75 on the front side can be increased, preventing excessive bending in the thickness direction, and by transmitting a moderate flexibility to the grip portion 5 side, the flexibility of the neck portion 4 can be gradually reduced toward the grip portion 5.

[0065] The position D is the position where the finger contact portion 50 has the widest width, and is preferably located closer to the rear end than the apex 51. The position D in the longitudinal direction is preferably 65 to 85 mm from the tip of the head portion 3.

[0066] 6 is a cross-sectional view of the finger rest 50 at position D where it is at its widest. As shown in FIG. 6, the cross section of the grip 5 at position D is a substantially hexagonal shape with a straight line on the front side. The grip 5 has an upper surface (first surface) 56 that faces the front side and extends in the width direction, and side surfaces (second surfaces) 52 that extend outward in the width direction from the intersections with the upper surface 56, with ridgelines 57, and are therefore inclined toward the rear side. The upper surface 56 is the finger rest surface of the finger rest 50.

[0067] The cross-sectional shape of the finger rest portion 50 is a flat shape in which the length in the width direction is longer than the length in the thickness direction. By making the cross-sectional shape of the finger rest portion 50 flat, the finger rest portion 50 is more likely to deform when a force is applied to the rear side. By making the cross-section of the grip portion 5 at position D a flat, approximately hexagonal shape, the finger rest portion 50 is more likely to bend in the thickness direction. The cross-sectional shape of the finger rest portion 50 may be other shapes, such as a square, as long as the front side is flat.

[0068] Position B, the rear end where the width of the neck portion 4 is constant, is preferably 45 to 65 mm from the tip of the head portion 3. The width of the neck portion 4 at position B is preferably 5.0 to 6.0 mm. The thickness of the soft portion 74 on the outer side of the hard portion 64 in the width direction at position B is preferably 0.7 to 1.1 mm.

[0069] The width of the gripping portion 5 at position D is preferably 13.5 to 16.0 mm. The thickness of the soft portion 75 on the widthwise outer side of the hard portion 65 at position D is preferably 2.1 to 2.5 mm. The thickness of the gripping portion 5 at position D is preferably 8.0 to 10.0 mm.

[0070] The ratio between the width of the neck portion 4 at position B and the width of the grip portion 5 at position D is preferably 1:2.0 to 1:3.0. Furthermore, the ratio between the thickness of the soft portion 74 located widthwise outward of the hard portion 64 in the neck portion 4 at position B and the thickness of the soft portion 75 located widthwise outward of the hard portion 65 in the grip portion 5 at position D is preferably 1:2.0 to 1:4.0.

[0071] It is preferable that the rate of increase from the width of the neck portion 4 at position B to the width of the gripping portion 5 at position D be greater than the rate of increase from the thickness of the soft portion 74 located widthwise outside the hard portion 64 at position B to the thickness of the soft portion 75 located widthwise outside the hard portion 65 in the gripping portion 5 at position D.

[0072] By providing the soft portion 75 within the above range on the flat finger rest 50, it is possible to prevent excessive bending while maintaining a moderate degree of flexibility. Furthermore, by increasing the ratio of the increase in widthwise thickness of the soft portion 74 and the soft portion 75 as the width increases from position B to position D, it is possible to impart a certain degree of deformability to the finger rest 50. Therefore, when pressure is applied to the rear side and the neck portion bends, the head portion 3, neck portion 4, and grip portion 5 can deform as a unit. The value expressed as the width of the grip portion 5 at position D divided by the thickness of the grip portion 5 at position D is preferably 1.4 or more and 1.8 or less.

[0073] The finger rest 50 has a hard portion 65 that forms the top surface 56 in the center in the width direction exposed on the front side, and soft portions 75 that are exposed on both sides in the width direction sandwiching the hard portion 65. More specifically, the soft portions 75 extend beyond the boundary position C with the neck portion 4 to the side surfaces 52 on both sides of the hard portion 65, and to a position beyond the position D where the finger rest 50 is at its widest, covering the side surfaces 52. By arranging the soft portions 75 also on the side surfaces 52 of the finger rest 50, elasticity in the width direction can be maintained.

[0074] 2, the hard portion 65 of the finger rest 50 has a generally elliptical shape that gradually widens from the center of the width at position C toward the rear end. The rear end of the finger rest 50 is position F, where the hard portion 65 widens into a generally elliptical shape toward the rear end, and then gradually narrows further rearward than the rear end of the soft portion 75 exposed on the front side, until the width becomes constant. That is, the rear end of the finger rest 50 is position F, where the forked ridgelines located on the front side are connected. As described above, position F is the position where the ninth curve region E9 exhibits a minimum value.

[0075] The start position of the finger rest 50 in the longitudinal direction is the position of the starting point where the hard portion 65 is exposed on the front side. In other words, the start position of the finger rest 50 in the longitudinal direction is the rear end position of the neck portion 4 where the soft portion 74 covers the entire circumference. The start position of the finger rest 50 in the longitudinal direction is position C, which is the same as the apex 51 in the longitudinal direction. Note that if the position where the seventh curved region E7 and the eighth curved region E8 intersect in the front view, which defines position C, is unclear, the start position of the finger rest 50 is the position closest to the neck portion 4 on the convex ridgeline extending from the grip portion 5 toward the neck portion 4 in a side view. The position of the finger rest 50 is preferably in an area 0 to 30 mm toward the rear end from the boundary position C between the neck portion 4 and the grip portion 5.

[0076] As shown in the side view of Fig. 1, finger rest 50 (see front view in Fig. 2) is formed at position E where gripping portion 5 is at its thinnest thickness, and because hard portion 65 is thin, it is gently covered with soft portion 75, thereby suppressing bending while maintaining elasticity. Since gripping portion 5 does not have soft portion 75 provided on the rear end side of finger rest 50 and does not bend toward the front, providing soft portion 75 in a linear form exposed on the back side gives gripping portion 5 more flexibility in the thickness direction than when gripping portion 5 is formed only with hard portion 65.

[0077] Position E is preferably located within a range of 7 to 20 mm from position C toward the rear end in the longitudinal direction. The value expressed as (thickness of gripping portion 5 at position E) / (thickness of gripping portion 5 at position C) is preferably 0.4 or more and 0.7 or less, and more preferably 0.5 or more and 0.6 or less. The thickness of gripping portion 5 at position C is, for example, 10.5 to 12.5 mm. The thickness of gripping portion 5 at position E is, for example, 6.0 to 7.5 mm.

[0078] 3, the grip portion 5 has, on the back side of the finger rest 50, a finger rest 55 on which the index finger rests, for example. The finger rest 55 is formed in a substantially elliptical shape. The finger rest 55 is formed of a soft portion 75 that covers the hard portion 65 and is exposed on the back side. On the back side of the grip portion 5, the soft portion 75 is sandwiched between the hard portions 65 and extends from the center in the width direction to near the end on the rear end side of the grip portion 5, exposed and flush with the hard portion 65.

[0079] Therefore, in the brush body 2, from the neck portion 4 toward the rear end of the grip portion 5, there are sequentially arranged: a first region R1 in which the soft portion 74 covers the entire periphery of the hard portion 64; a second region R2 in which the soft portion 75 covers the hard portion 65 only on the side surface 52 and rear surface; and a third region R3 in which the soft portion 75 covers the hard portion 65 only on the rear surface. By adopting this configuration, elasticity can be maintained throughout the entire longitudinal direction, as if the head portion 3, neck portion 4, and grip portion 5 were forming a continuous series of arcs.

[0080] The value expressed by (thickness of the soft portion 75 on the rear side at position E) / (thickness of the grip portion 5 at position E) is preferably 0.1 or more and 0.3 or less. If the above value is less than 0.1, flexibility may decrease. If the above value exceeds 0.3, bending toward the rear side starting from position E may become too large. By setting the above value to 0.1 or more and 0.3 or less, it is possible to impart appropriate flexibility to the force toward the rear side at position E. The thickness of the soft portion 75 at position E is, for example, 1.0 mm.

[0081] As shown in FIG. 2, a pair of ridgelines 57 where the top surface 56 and the side surface 52 intersect gradually approach each other from position D toward the rear end, and change to a constant width at position F. In the ninth curved region E9, the rigid portion 65 is constricted at position F in a plan view, showing a minimum value. By providing the ridgelines 57 on the front side of the grip portion 5, the grip portion 5 is less likely to bend, allowing the grip portion 5 to be gripped firmly. Furthermore, by having the rigid portion 65 of the grip portion 5 have a minimum value where the grip portion 5 is constricted in the width direction, the grip portion 5 can maintain flexibility. The position of the widthwise constriction (minimum value) in the long axis direction is preferably 45 to 60% of the total length of the toothbrush 1 from the tip side of the head portion 3.

[0082] The maximum width of the finger rest 55 at position D is preferably 1.3 to 1.8 times the minimum width of the constricted grip portion 5 at position F. The maximum width of the grip portion 5 at position G is preferably 1.3 to 1.8 times the minimum width of the constricted grip portion 5 at position F. The maximum width of the finger rest 55 at position D is, for example, 14.0 to 16.0 mm. The minimum width of the constricted grip portion 5 at position F is, for example, 9.0 to 11.0 mm. The maximum width of the grip portion 5 at position G is, for example, 14.0 to 16.0 mm.

[0083] The thickness of the gripping portion at position F is preferably 1.2 to 1.6 times the thickness of the gripping portion at position E. The thickness of the gripping portion at position G is preferably 1.5 to 2.3 times the thickness of the gripping portion at position E. It is also preferable that the thickness of the gripping portion at position G > the thickness of the gripping portion at position F > the thickness of the gripping portion at position E. For example, the thickness of the gripping portion at position F is 7.5 to 9.5 mm. For example, the thickness of the gripping portion at position G is 12.0 to 14.0 mm.

[0084] The tip-side end of the point where the pair of ridge lines 57 have a constant width (position F) is located 50 to 60% of the total length of the toothbrush 1 from the tip side of the head 3. For example, it is located 95 to 120 mm from the tip side of the head 3 and 5 to 10 mm from position D. The rear-side end of the point where the pair of ridge lines 57 have a constant width is located 80 to 90 mm from position F. FIG. 7 is a cross-sectional view of the grip 5 at position F. As shown in FIG. 7, the cross-section of the grip 5 at position F has a substantially pentagonal shape with the apex on the front side. The pair of ridge lines 57 preferably join together at position F. The pair of ridge lines 57 gradually widen from the rear-side end of the constant width point to position H where the thickness of the grip 5 is greatest. Position H is located 160 to 190 mm from the tip side of the head 3 and 50 to 70 mm toward the rear from position F.

[0085] The width of the side surface 52 is 3 to 7 mm at position F. The width of the side surface 52 expands from position F toward the rear end, reaching 12 to 17 mm at position H. The pair of side surfaces 52 intersect at an intersection angle θ. The intersection angle θ indicates the area occupied by the hard portion 65 in the cross section. The intersection angle θ gradually decreases from position F, where the distance (width) between the pair of ridge lines 57 is minimum, to position H, where the thickness of the grip portion 5 is maximum. The intersection angle θ preferably gradually decreases toward the rear end of the grip portion 5 in a region of 95% or less of the entire length of the grip portion 5 from the tip to the rear end of the grip portion 5. For example, if the intersection angle θ is minimum at 179 mm from the tip of the head portion 3 with respect to the total length of the toothbrush 1 being 190 mm (179 mm / 190 mm = 94.2%), the outer contour line on the front side in side view will be rounded toward the rear end from this position, and no side surface 52 will be formed.

[0086] FIG. 8 is a cross-sectional view of the grip portion 5 at position H. As shown in FIG. 8, the cross-section of the grip portion 5 at position H is approximately triangular with the apex on the front side. The cross-section of the grip portion 5 changes sequentially from approximately triangular to approximately pentagonal and approximately hexagonal from the rear end toward the finger rest portion 50. This makes the rear end thick and the middle portion thin and rigid, allowing for a firm and stable grip with the entire palm when gripped with a palm grip. The cross-section of the grip portion 5 at position H does not necessarily have to be approximately triangular.

[0087] As the crossing angle θ gradually decreases from position F to position H, the effect of suppressing elasticity increases toward the rear end of the gripping portion 5. In other words, it is possible to vary the deformability according to the approximately triangular cross section with different angles at the apex on the front side. As an example, the crossing angle θ at position F is preferably 90 to 120°, and the crossing angle θ at position H is preferably 50 to 70°.

[0088] In the toothbrush 1 having the above configuration, the neck portion 4 is covered with the soft portion 70 for 70% or more of the longitudinal length, and the entire circumference of the hard portion 60 is covered up to the boundary position with the grip portion 5. By setting the value represented by S2 / S1, which is the relationship between the cross-sectional area S1 of the soft portion 70 at position A and the cross-sectional area S2 of the soft portion 70 at position C, to 4.5 or more and 6.0 or less, it becomes possible to deform over a wide area rather than locally while maintaining a stable grip feeling.

[0089] [Example] The effects of the present invention will be made clearer by the following examples. Note that the present invention is not limited to the following examples and can be practiced with appropriate modifications within the scope of the present invention.

[0090] (Examples 1 to 7, Comparative Examples 1 to 6) In the present examples, toothbrush samples of Examples 1 to 7 and Comparative Examples 1 to 6 were produced according to the specifications shown in Tables 1, 2, 3, and 4 below. The dimensions of each part of the toothbrush in each example are shown in Tables 1 and 2. PP resin was used as the hard resin for the brush body, and thermoplastic elastomer (TPE) was used as the soft resin.

[0091] The sample of Example 2 had the same overall width at position C as the sample of Example 1, but the thickness of the elastomer in the width direction was increased. The sample of Example 3 had the same overall width at position C as the sample of Example 1, but the thickness of the elastomer in the width direction was decreased. The sample of Example 4 had the same overall thickness at position C as the sample of Example 1, but the thickness of the elastomer in the thickness direction was increased. The sample of Example 5 had the same overall thickness at position C as the sample of Example 1, but the thickness of the elastomer in the thickness direction was decreased. The sample of Example 6 was configured such that no elastomer was placed on the side of the finger rest portion, compared to the sample of Example 1. The sample of Example 7 was configured such that no ridge line was present on the front side of the grip portion, compared to the sample of Example 1.

[0092] The sample of Comparative Example 1 had a smaller longitudinal coverage of the elastomer in the neck portion than the sample of Example 1. The sample of Comparative Example 2 had the same overall width and thickness at position C as the sample of Example 1, but the widthwise and thicknesswise thicknesses of the elastomer were larger than those of the sample of Example 1. The sample of Comparative Example 3 had the same overall width and thickness at position C as the sample of Example 1, but the widthwise and thicknesswise thicknesses of the elastomer were smaller than those of the sample of Example 1. The sample of Comparative Example 4 had the same overall thickness at positions A and C as the sample of Example 1, but the widthwise thickness of the elastomer was smaller than those of the sample of Comparative Example 1. The sample of Comparative Example 5 had the same overall width at position C as the sample of Comparative Example 3, but the widthwise thickness of the elastomer was further reduced. The sample of Comparative Example 6 was configured without using elastomer compared to the sample of Example 1.

[0093] [Evaluation method] (1) Ease of controlling force [Test method] The development staff conducted a usability evaluation (n=7), and each item was evaluated on a 7-point absolute scale, with a target score of 5 or more for each item. <Judgment criteria> ◎ (double circle mark): Average score is 6.0 or above ○ (circle mark): Average score is 5.0 or more and less than 6.0 points × (cross mark): Average score is less than 5.0 points

[0094] (2) Feeling of overall tooth cleaning (feeling of pressure being transmitted to teeth) The development staff conducted a usability evaluation (n=7), and each item was evaluated on a 7-point absolute scale, with a target score of 5 or more for each item. <Judgment criteria> ◎: Average score is 6.0 or above ○: Average score is 5.0 or more and less than 6.0 points ×: Average score is less than 5.0 points

[0095] (3) Comfortable contact with the gums (good cushioning on the gums) The development staff conducted a usability evaluation (n=7), and each item was evaluated on a 7-point absolute scale, with a target score of 5 or more for each item. <Judgment criteria> ◎: Average score is 6.0 or above ○: Average score is 5.0 or more and less than 6.0 points ×: Average score is less than 5.0 points

[0096] [Table 1]

[0097] [Table 2]

[0098] [Table 3]

[0099] [Table 4]

[0100] As shown in [Table 1] and [Table 2], the samples of Examples 1 to 7, in which the circumferential coverage rate of the elastomer in the longitudinal direction of the neck portion was 70% or more, and the value expressed by S2 / S1 between the cross-sectional area S1 of the elastomer at position A and the cross-sectional area S2 of the elastomer at position C was 4.5 or more and 6.0 or less, received good ratings in all aspects of ease of force control, overall tooth cleaning sensation (feeling of force being transmitted to the teeth), and comfort on the gums (good cushioning on the gums).

[0101] Furthermore, in the samples of Examples 1 to 7, in which the value expressed as S3 / S4 of the total cross-sectional area S3 and the cross-sectional area S4 of the hard part at boundary position C was 2.0 or more and 4.0 or less, good evaluations were obtained in all aspects of ease of force control, overall tooth cleaning sensation (feeling of force being transmitted to the teeth), and comfort on the gums (good cushioning on the gums).

[0102] Furthermore, in the cross section at position A, the thickness A1 of the elastomer located on the back side in the thickness direction and the thickness A2 of the elastomer located on the widthwise outer side of the hard portion, and in the cross section at position C, the thickness 11 of the elastomer located on the back side in the thickness direction and the thickness C2 of the elastomer located on the widthwise outer side of the hard portion, satisfy the relationship (C2 / A2) / (C1 / A1)>2.5. In the samples of Examples 1 to 7, which satisfy the relationship (C2 / A2) / (C1 / A1)>2.5, good evaluations were obtained in all aspects of ease of force control, overall tooth cleaning sensation (feeling of force being transmitted to the teeth), and comfort on the gums (good cushioning on the gums).

[0103] In the samples of Examples 1 to 3 and 6 to 7, where the value expressed as (C12 / C11) / (A12 / A11) for the maximum thickness A11 of the neck portion and the maximum thickness A12 of the hard portion at position A, the maximum width A21 of the neck portion and the maximum width A22 of the hard portion at position A, the maximum thickness C11 of the neck portion and the maximum thickness C12 of the hard portion at position C, and the maximum width C21 of the neck portion and the maximum width C22 of the hard portion at position C was 0.95 or more and 1.15 or less, good ratings were obtained in all aspects of ease of force control, overall tooth cleaning sensation (feeling of force being transmitted to the teeth), and comfort on the gums (good cushioning on the gums). The samples of Examples 1 and 4 to 7, in which the value represented by (C22 / C21) / (A22 / A21) was 0.70 or more and 0.90 or less, received good ratings in all aspects of ease of force control, overall tooth cleaning sensation (feeling of force being transmitted to the teeth), and comfort on the gums (good cushioning on the gums).

[0104] In contrast, the sample of Comparative Example 1, in which the coverage rate of the elastomer in the longitudinal direction of the neck portion was less than 70%, the relationship (C2 / A2) / (C1 / A1) > 2.5 was not satisfied, and the value expressed by (C22 / C21) / (A22 / A21) was outside the range of 0.70 or more and 0.90 or less, did not receive a good evaluation in terms of ease of force control and comfort on the gums (good cushioning on the gums).

[0105] Furthermore, the sample of Comparative Example 2, in which the value represented by the cross-sectional area ratio S2 / S1 was outside the range of 4.5 or more and 6.0 or less, the value represented by the cross-sectional area ratio S3 / S4 was outside the range of 2.0 or more and 4.0 or less, the value represented by (C12 / C11) / (A12 / A11) was outside the range of 0.95 or more and 1.15 or less, and the value represented by (C22 / C21) / (A22 / A21) was outside the range of 0.70 or more and 0.90 or less, did not receive a good evaluation in any of the evaluation items.

[0106] The sample of Comparative Example 3, in which the value represented by the cross-sectional area ratio S2 / S1 was outside the range of 4.5 or more and 6.0 or less, and the value represented by (C22 / C21) / (A22 / A21) was outside the range of 0.70 or more and 0.90 or less, did not receive a good evaluation in terms of ease of force control and comfort on the gums (good cushioning on the gums).

[0107] The sample of Comparative Example 4, in which the cross-sectional area ratio S2 / S1 was outside the range of 4.5 or more and 6.0 or less, the value expressed by (C12 / C11) / (A12 / A11) was outside the range of 0.95 or more and 1.15 or less, and the value expressed by (C22 / C21) / (A22 / A21) was outside the range of 0.70 or more and 0.90 or less, did not receive good ratings in terms of ease of force control and comfort on the gums (good cushioning on the gums).

[0108] The sample of Comparative Example 5, in which the value represented by the cross-sectional area ratio S2 / S1 was outside the range of 4.5 or more and 6.0 or less, the value represented by the cross-sectional area ratio S3 / S4 was outside the range of 2.0 or more and 4.0 or less, and the value represented by (C22 / C21) / (A22 / A21) was outside the range of 0.70 or more and 0.90 or less, did not receive a good evaluation in terms of ease of force control and comfort on the gums (good cushioning on the gums).

[0109] The sample of Comparative Example 6, in which the cross section of the finger rest portion has a flat shape that is long in the thickness direction, and the sample of Comparative Example 7, which does not have an elastomer, did not receive good ratings in any of the evaluation items.

[0110] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the components shown in the above examples are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention. [Industrial Applicability]

[0111] The present invention is applicable to toothbrushes. [Explanation of symbols]

[0112] 1...Toothbrush, 2...Brush body, 3...Head part, 3a...Flocking surface, 4...Neck part, 5...Grip part, 50...Finger rest part, 51...Vertex, 52...Side surface (second surface part), 56...Top surface (first surface part), 57...Ridge line, 60, 63, 64, 65...Hard part, 70, 73, 74, 75...soft part, C...position (boundary position), E2...curved surface (second curve area), R1...first area, R2...second area, R3...third area

Claims

1. a head portion located at the tip end in the longitudinal direction and having a bristle implantation surface; a gripping portion disposed rearward of the head portion; a neck portion disposed between the head portion and the grip portion; and the neck portion and the grip portion each have a hard portion made of a hard resin and a soft portion made of a soft resin and covering at least a portion of the hard portion; The neck portion is covered with the soft portion over an entire periphery of the hard portion, covering 70% or more of the length of the neck portion in the long axis direction and extending to a boundary position with the grip portion, In a cross section perpendicular to the longitudinal direction, the position of the end portion of the soft portion in the neck portion on the tip side in the longitudinal direction is defined as A, the cross-sectional area of ​​the soft portion at the position A is defined as S1, the boundary position in the longitudinal direction is defined as C, and the cross-sectional area of ​​the soft portion at the position C is defined as S2. The value represented by S2 / S1 is 4.5 or more and 6.0 or less, the grip portion has a finger rest portion on a front side facing the flocking surface in a thickness direction perpendicular to the flocking surface, In the cross section, the finger rest portion has a flat shape in which the length in the width direction perpendicular to the major axis direction and the thickness direction is longer than the length in the thickness direction, In a side view seen in the width direction, the finger rest portion has a convex apex on the front side, a concave curved surface extending from the apex toward the rear end side and having a center of curvature on the front side; In a front view from the front side, a width between the outer contour lines in the width direction expands from the boundary position to a position where the finger rest portion has a maximum width, The finger rest portion has the hard portion exposed on the front side, The toothbrush is characterized in that the soft portion covers the hard portion on both side surfaces in the width direction, sandwiching the finger rest portion, beyond the boundary position to the position where the width is greatest.

2. If the total cross-sectional area of ​​the neck portion perpendicular to the longitudinal axis direction at the boundary position is S3 and the cross-sectional area of ​​the hard portion is S4, then: The value represented by S3 / S4 is 2.0 or more and 4.0 or less. The toothbrush of claim 1.

3. the soft portion extends beyond the boundary position toward the rear end at least on a rear side opposite to the front side in the thickness direction; The toothbrush according to claim 1 or 2.

4. A first region in which the soft portion covers the entire periphery of the hard portion, a second region in which the soft portion covers the hard portion only on the side and rear side, and a third region in which the soft portion covers the hard portion only on the rear side are sequentially arranged from the neck portion toward the rear end side of the grip portion. The toothbrush of claim 3.

5. In the cross section, the grip portion at the position of the maximum width has a first surface portion facing the front side and extending in the width direction, and second surface portions whose intersections with the first surface portion form ridgelines and which are inclined toward the back side opposite the front side in the thickness direction as they extend outward in the width direction from the intersections, the distance between the ridge lines in the width direction gradually decreases from the position where the width is maximum toward the rear end side, and then gradually increases to the position where the thickness of the grip portion is maximum; 5. The toothbrush according to any one of claims 1 to 4.

6. 6. The toothbrush of claim 5, wherein the intersection angle between the pair of second surface portions, which indicates the range occupied by the hard portion in the cross section, gradually decreases from the position where the distance between the ridge lines in the width direction is minimum toward the position where the thickness of the grip portion is maximum.

7. In the cross section at the position A, the thickness of the soft portion located on the back side opposite to the flocking surface in the thickness direction perpendicular to the flocking surface relative to the hard portion is defined as A1, and the thickness of the soft portion located outside the hard portion in the width direction perpendicular to the major axis and the thickness direction is defined as A2. In the cross section at the position C, if the thickness of the soft portion located closer to the back surface in the thickness direction than the hard portion is defined as C1 and the thickness of the soft portion located closer to the outside in the width direction than the hard portion is defined as C2, (C2 / A2) / (C1 / A1)>2.5 Satisfy the relationship between 7. The toothbrush according to any one of claims 1 to 6.

8. The thickness C2 is 2.5 mm or more and 4.5 mm or less, The thickness C1 is 0.7 mm or more and 1.5 mm or less. The toothbrush of claim 7.

9. At the position A, the maximum thickness of the neck portion is A11, and the maximum thickness of the hard portion is A12, At the position A, the maximum width of the neck portion is defined as A21, and the maximum width of the hard portion is defined as A22, At the position C, the maximum thickness of the neck portion is C11, and the maximum thickness of the hard portion is C12, If the maximum width of the neck portion at the position C is C21 and the maximum width of the hard portion is C22, The value represented by (C12 / C11) / (A12 / A11) is 0.95 or more and 1.15 or less, The value represented by (C22 / C21) / (A22 / A21) is 0.70 or more and 0.90 or less.

9. The toothbrush of any one of claims 1 to 8.

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