toothbrush

Abstract

The present invention provides a transparent toothbrush that ensures fatigue resistance. The brush body is formed of a transparent saturated polyester resin. With respect to the first direction, the thickness of the head is greater than 2 mm and less than 3.8 mm over the entire area. With respect to the second direction, the minimum width of the neck is less than 5.3 mm, the position in the long axis direction with the neck as the minimum width is W, the cross-sectional secondary wheelbase in the first direction at position W is W1, the cross-sectional secondary wheelbase in the first direction at the center S of the long axis direction, the first direction and the second direction in the head is S1, and the cross-sectional secondary wheelbase in the first direction at the center T of the long axis direction, the first direction and the second direction in the grip is T1, and the cross-sectional secondary wheelbase W1 is 20 mm. 4 Above, 50mm 4 Hereinafter, the value represented by W1 / S1 is 0.9 or more and 1.9 or less, and the value represented by T1 / W1 is 6 or more and 26 or less.

Description

Technical Field

[0001] The present invention relates to a toothbrush.

[0002] This application claims priority based on Japanese Patent Application No. 2020-148309 filed in Japan on September 3, 2020, the contents of which are incorporated herein by reference. Background Art

[0003] Plaque control is important for preventing dental caries and periodontal disease. Conventionally, toothbrushes with thinner heads and narrower necks have been developed to improve molar reach in order to remove plaque deep within molars, a common site for dental caries.

[0004] When developing toothbrushes with thin heads, using general-purpose resins such as PP (polypropylene) requires careful consideration. Since PP is a relatively soft resin, it is necessary to ensure ease of use in the mouth while suppressing neck flexing during use. Therefore, as a solution to this problem, methods have been reported to optimize the "flexing behavior," "width and thickness transitions," and "curved shape" of the neck region (e.g., see Patent Documents 1 to 3).

[0005] [Prior Art Document]

[0006] [Patent Document]

[0007] [Patent Document 1] International Publication No. WO 2017 / 155033

[0008] [Patent Document 2] International Publication No. WO 2018 / 079114

[0009] [Patent Document 3] International Publication No. WO 2018 / 079115 Summary of the Invention

[0010] [Problems to be solved by the invention]

[0011] Currently, most toothbrushes with thin heads on the market are made of opaque resins such as PP or POM (polyacetal). Therefore, for visual differentiation, thinner heads made of transparent (transparent or translucent) resins are desired. Traditionally, polyesters have been the primary transparent resin used for toothbrushes, but these resins often have issues with fatigue resistance.

[0012] Specifically, while polyester resins are strong against instantaneous impact, they tend to break when subjected to relatively light forces, a characteristic not found in PP (PP itself deforms plastically and is therefore less prone to breaking). Therefore, thinning the head section using polyester resins is technically difficult.

[0013] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a transparent toothbrush having ensured fatigue resistance.

[0014] [Methods used to solve the problem]

[0015] Fatigue fracture typically occurs in the neck region, so to ensure fatigue resistance, it is important to prevent load energy from accumulating in the neck region. Therefore, the present inventors conducted extensive research to address this issue and discovered that, rather than specifically shifting the cross-sectional shape of the neck (i.e., strengthening the neck itself), as a conventional thinning measure, this energy can be dispersed over a wide range by optimizing the balance of the cross-sectional secondary wheelbase at various locations within the head, neck, and grip, thereby solving the aforementioned problem. This led to the completion of the present invention.

[0016] Specifically, according to the first embodiment of the present invention, there is provided a toothbrush, characterized in that the toothbrush comprises a brush body, the brush body comprising: a head located on the front end side and having a hair-planted surface, a gripping portion arranged closer to the rear end side than the head, and a neck arranged between the head and the gripping portion, the brush body being formed of a transparent saturated polyester resin, with respect to a first direction perpendicular to the hair-planted surface, the thickness of the head being greater than 2 mm and less than 3.8 mm in the entire region, and with respect to a second direction perpendicular to the long axis direction extending from the brush body and the first direction, the minimum width of the neck being less than 5.3 mm. The position of the neck with the minimum width in the long axis direction is set as W, the cross-sectional secondary wheelbase related to the bending in the first direction at the position W is set as W1, the center of the head in the long axis direction, the first direction and the second direction is set as S, the cross-sectional secondary wheelbase related to the bending in the first direction at the center S is set as S1, the center of the gripping part in the long axis direction, the first direction and the second direction is set as T, the cross-sectional secondary wheelbase related to the bending in the first direction at the center T is set as T1, and the cross-sectional secondary wheelbase W1 is 20 mm at this time. 4 Above, 50mm 4 Hereinafter, the value represented by W1 / S1 is 0.9 or more and 1.9 or less, and the value represented by T1 / W1 is 6 or more and 26 or less.

[0017] In addition, in a toothbrush according to one embodiment of the present invention, it is characterized in that when the position in the middle of the length of the long axis direction of the flexure area of ​​the neck in the first direction from the front perspective as the front side of the hair-planting surface is set to H, and the cross-sectional secondary wheelbase related to the bending in the first direction at position H is set to H1, the width in the second direction at position H is less than 5.5 mm, and the cross-sectional secondary wheelbase H1 is 28 mm4 Above, 70mm 4 In the following, taking the position H as the starting point, the position 15 mm away from it on the head side is set as Q, the position 10 mm away from it on the grip side is set as R, the secondary wheelbase of the cross section related to the bending in the first direction at position Q is set as Q1, and the secondary wheelbase of the cross section related to the bending in the first direction at position R is set as R1, the value represented by H1 / Q1 is greater than 1.0 and less than 2.0, and the value represented by R1 / H1 is greater than 1.7 and less than 3.0.

[0018] In addition, in a toothbrush according to one embodiment of the present invention, it is characterized in that the end of the front side of the bending area in the longitudinal direction under the front view is: the edge of the rear end side of the hair planting hole closest to the rear end side among the multiple hair planting holes arranged on the hair planting surface, the end of the rear end side of the bending area in the longitudinal direction under the front view is the end of the front end side of the gripping part, and when the end of the rear end side of the bending area in the longitudinal direction is set to position I, in the outer contour line of the second direction under the front view between the position H and the position I, the straight line connecting the end point of the front end side and the end point of the rear end side has an inclination of more than 1.9° and less than 6.5° relative to the longitudinal direction, and in the outer contour line of the back side on the opposite side of the front side in the first direction between the position H and the position I under the side view observed from one side of the second direction, the straight line connecting the end point of the front end side and the end point of the rear end side has an inclination of more than 3.0° and less than 5.3° relative to the longitudinal direction.

[0019] In addition, in a toothbrush according to one embodiment of the present invention, it is characterized in that when the position 20 mm away from the position I on the rear end side is set to U, the center S and the positions H, I and U in the outer contour line on the front side are on a roughly straight line in the side view, the center S and the positions H, I and U in the outer contour line on the back side are on a roughly straight line in the side view, and the distance between the positions H, I and U in the outer contour line and the straight line extending in the long axis direction with the center S as the starting point in the side view is all less than 5 mm.

[0020] In addition, in a toothbrush according to one embodiment of the present invention, it is characterized in that, between the center S and the position U, the outer contour lines of the side view are all formed by lines selected from arcs and straight lines with a radius of 45 mm or more, and between the center S and the position U, the straight line connecting any two points in the outer contour line of the side view has an intersection angle of less than 8° with the straight line extending in the direction of the long axis starting from the center S.

[0021] Furthermore, in the toothbrush according to one embodiment of the present invention, the transparent saturated polyester resin is a PCTA resin.

[0022] [Effects of the Invention]

[0023] The present invention can provide a transparent toothbrush having ensured fatigue resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] [ Figure 1 ] is a diagram showing an embodiment of the present invention, and is a side view showing the structure of the toothbrush 1.

[0025] [ Figure 2 ] is a front view of the toothbrush 1 as viewed from the bristle-planted surface 3a.

[0026] [reference numerals]

[0027] 1…toothbrush; 2…brush body; 3…head; 3a…bristle surface; 4…neck; 4A…flexing area; 5…grip; 6, 6a…bristle pores; S, T…center DETAILED DESCRIPTION

[0028] Below, refer to Figure 1 and Figure 2 An embodiment of the toothbrush of the present invention will be described.

[0029] In addition, the following embodiments represent one mode of the present invention and do not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of ​​the present invention. In addition, in the following drawings, in order to easily understand each structure, the scale and quantity etc. in the actual structure and each structure are different.

[0030] In addition, in the following description, the side (the hair-implanted surface side) on which the hair-implanted surface 3a of the head 3 is provided is referred to as the front side of the toothbrush 1, and the side opposite to the side facing the hair-implanted surface 3a of the head 3 is referred to as the back side of the toothbrush 1. In addition, the direction in which the brush body 2 extends is referred to as the long axis direction, the direction parallel to the hair-implanted surface 3a and perpendicular to the long axis direction is referred to as the width direction (the second direction) of the toothbrush 1, and the direction perpendicular to the hair-implanted surface 3a is referred to as the thickness direction (the first direction) of the toothbrush 1. In addition, the side (the head side) on which the head 3 is provided is referred to as the front end side, and the side (the gripping portion side) on which the gripping portion 5 is provided is referred to as the rear end side.

[0031] Figure 1 It is a side view showing the structure of the toothbrush 1. Figure 2 This is a front view of the toothbrush 1 as viewed from the bristle-planting surface 3a. Figure 2 In the figure, the brush 40 is omitted.

[0032] like Figure 1 and Figure 2 As shown, the toothbrush 1 of this embodiment includes a brush body 2 formed of a resin molded body formed in an elongated shape as a whole, and a brush 40 .

[0033] The brush body 2 includes a head 3 located at the front end and having a bristle-implanted surface 3a, a grip 5 located further back than the head 3, and a neck 4 disposed between the head 3 and the grip 5. In the toothbrush 1, a brush 40 having a plurality of bristle bundles (not shown) implanted on the bristle-implanted surface 3a of the head 3 can clean the oral cavity.

[0034] The resin constituting the brush body 2 is formed of a transparent or translucent amorphous hard resin. In the brush body 2 of this embodiment, a polyester resin is used as the amorphous hard resin. As an example of an amorphous polyester resin, there can be mentioned PCTA resin composed of a dicarboxylic acid component mainly composed of terephthalic acid (TA) and isophthalic acid (IPA) and a diol component mainly composed of 1,4-cyclohexanedimethanol (CHDM), or polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and polyarylate resin. In addition, as amorphous resins other than polyester resins, there can be mentioned polystyrene resin, polyarylate resin, polycarbonate resin, and acrylonitrile-styrene resin.

[0035] (Outline shape of the front side of the brush body)

[0036] The toothbrush 1 of this embodiment, when the brush body 2 is viewed from the side, has, in the outline of the front side of the brush body 2, a first straight region L1 extending linearly continuously from the rear end of the head 3 toward the grip 5 and from the hair-planted surface 3a of the head 3 to the rear end, a first curved region E1 having a center of curvature on the front side and extending in an arc shape from the rear end of the first straight region L1 to the rear end, and a second curved region E2 having a center of curvature on the back side and extending in an arc shape from the rear end of the first curved region E1 to the rear end. Furthermore, the toothbrush 1 has, on the front side when viewed from the side, a third curved region E3 having a center of curvature on the front side and extending in an arc shape from the rear end of the second curved region E2 to the rear end, and a fourth curved region E4 having a center of curvature on the back side and extending in an arc shape from the rear end of the third curved region E3 to the rear end. Furthermore, the toothbrush 1 has, on the front side when viewed from the side, a fifth curved area E5 having a center of curvature on the front side and extending in an arc shape from the rear end of the fourth curved area E4 to the rear end side, and a sixth curved area E6 having a center of curvature on the back side and extending in an arc shape from the rear end of the fifth curved area E5 to the rear end side.

[0037] (Outline shape of the back side of the brush body)

[0038] The toothbrush 1 of this embodiment, when viewing the brush body 2 from a side view, has, within its back side outline, a second straight region L2 extending linearly from the back side of the head 3 toward the grip 5, continuously from the back side of the head 3 to the back side; a seventh curved region E7 having a center of curvature on the back side and extending arcuately from midway along the back side of the second straight region L2 to the back side; and a third straight region L3 extending linearly parallel to the longitudinal axis from the back end of the seventh curved region E7 to the back side. Furthermore, the toothbrush 1 has, from a side view, an eighth curved region E8 having a center of curvature on the back side and extending arcuately from the back end of the third straight region L3 to the back side; a ninth curved region E9 having a center of curvature on the back side and extending arcuately from the back end of the eighth curved region E8 to the back side; and a tenth curved region E10 having a center of curvature on the front side and extending arcuately from the back end of the ninth curved region E9 to the back side. Furthermore, the toothbrush 1 has, on the back side as viewed from the side, an 11th curved area E11 having a center of curvature on the back side and extending in an arc shape from the rear end of the 10th curved area E10 to the rear end side, a 12th curved area E12 having a center of curvature on the front side and extending in an arc shape from the rear end of the 11th curved area E11 to the rear end side, and a 4th straight line area L4 extending in a straight line parallel to the long axis direction from the rear end of the 12th curved area E12 to the rear end side.

[0039] (Outline shape of both sides of the brush body in the width direction)

[0040] The toothbrush 1 of this embodiment, when the brush body 2 is viewed from the front, the outer contour lines of the brush body 2 on both sides in the width direction are formed in line symmetry with respect to the center line extending in the long axis direction from the center in the width direction. Therefore, in the following description, one side in the width direction ( Figure 2 In addition, regarding the position of the center of curvature of the curved area extending in an arc shape, the position on the center side in the width direction relative to the outer contour line is called the inner side, and the position on the side opposite to the center in the width direction is called the outer side.

[0041] The toothbrush 1 of this embodiment, when the brush body 2 is viewed from the front, has, within its widthwise outline, a fifth straight region L5 extending linearly from the boundary between the head 3 and neck 4 (described in detail later) toward the rear end; a thirteenth curved region E13 having a center of curvature on the outside and extending arcuately from midway toward the rear end of the fifth straight region L5; and a fourteenth curved region E14 having a center of curvature on the inside and extending arcuately from the rear end of the 13th curved region E13 toward the rear end. Furthermore, the toothbrush 1 of this embodiment, when viewed from the front, has a fifteenth curved region E15 having a center of curvature on the outside and extending arcuately from the rear end of the fourteenth curved region E14 toward the rear end; and a sixteenth curved region E16 having a center of curvature on the inside and extending arcuately from the rear end of the fifteenth curved region E15 toward the rear end. Furthermore, the toothbrush 1, when viewed from the front of the brush body 2, has: a 17th curved area E17 having a center of curvature on the outside and extending in a circular arc from the rear end of the 16th curved area E16 to the rear end side, and an 18th curved area E18 having a center of curvature on the inside and extending in a circular arc from the rear end of the 17th curved area E17 to the rear end side.

[0042] (head)

[0043] The head 3, which uses multiple bristles to brush the inside of the mouth, is roughly rectangular with rounded corners. From the front, the head 3 has a roughly quadrilateral, flat plate shape with four corners cut off at the top. In this embodiment, the boundary between the head 3 and the neck 4 from the front is the endpoint of the curve forming the corner cut on the neck 4 side, that is, the location where the curvature of the curve changes direction.

[0044] The head 3 has a hair planting surface 3a on the front side. On the hair planting surface 3a, a plurality of hair planting holes 6 of the same diameter are arranged side by side. Regarding the hair planting holes 6, a plurality of ( Figure 2 In the middle, 2 to 4 rows of implant holes 6 are arranged at intervals in the long axis direction. Figure 2 In the hair implantation holes 6, hair bundles constituting the brush 40 are implanted.

[0045] The hair bundles are implanted in the respective implantation holes 6 by bundling a plurality of bristles (filaments) and folding them in half, sandwiching a metal anti-shedding tool (not shown) called a flat wire between the bundles, and driving the flat wire into the implantation holes 6. The implantation surface 3a on the front side of the head 3 and the surface on the back side are flat and parallel to each other.

[0046] The shape of the head 3 is not particularly limited as long as it is a shape or size that facilitates brushing the oral cavity. For example, the head 3 may have a shape in which the width gradually narrows from the base end toward the front end. Alternatively, the head 3 may have a tapered shape in which the thickness gradually decreases from the base end toward the front end, or the back side of the head 3 may have a shape with a raised center portion and rounded corners.

[0047] The thickness of the entire head 3 is preferably 2 mm or more and 3.8 mm or less, more preferably 3.0 to 3.7 mm, and even more preferably 3.1 to 3.5 mm. It should be noted that when the thickness of the head 3 is not constant, the thickness of the head 3 is defined as the maximum thickness of the head 3.

[0048] If the thickness of the head 3 is less than 2 mm, durability may be reduced. If the thickness of the head 3 is greater than 3.8 mm, insertion and operability into the molars may be reduced. By setting the thickness of the head 3 to be between 2 mm and 3.8 mm, insertion and operability into the molars can be improved without reducing durability.

[0049] (neck)

[0050] The neck 4 is a portion that is disposed between the grip 5 and the head 3 and connects the grip 5 and the head 3. In this embodiment, the contour lines of the neck 4 and the grip 5 in the front view and the side view are a shape that connects a plurality of straight lines and gentle curves from the boundary between the head 3 and the neck 4 toward the grip 5 side. Figure 2 The intersection of the fourteenth curved area E14 and the fifteenth curved area E15, and the position I where the curvature changes, are used as the boundary between the neck portion 4 and the grip portion 5. It should be noted that when the curvature change is unclear or when there is no position where the curvature changes, the position 42.2% of the total length of the brush body 2 (head 3) from the front end of the brush body 2 (for example, when the total length of the brush body 2 is 180 mm, the position 76.0 mm from the front end of the brush body 2) is used as the boundary.

[0051] The length of the neck 4 in the long axis direction is defined as the shortest distance between position W (described in detail later) and position I in a frontal view. The length of the neck 4 is preferably 25 to 45 mm, more preferably 25 to 40 mm.

[0052] By setting the length of the neck portion 4 within the above range, the insertability into the molars and the operability during cleaning of the molars can be improved.

[0053] Regarding the neck 4, from the boundary with the head 3 toward the grip 5, the area of ​​the outer contour defined by the fifth straight line region L5 has a constant minimum width when viewed from the front. The area of ​​the outer contour defined by the 13th and 14th curved regions E13 and E14 gradually widens from this minimum width. The minimum width of the neck 4 is preferably 5.3 mm or less, more preferably 5.0 mm or less, and even more preferably 4.8 mm or less. By limiting the minimum width of the neck 4 to 5.3 mm or less, insertion and manipulation into the molars can be improved. For strength considerations, the minimum width of the neck 4 is preferably 3.5 mm or greater.

[0054] Regarding the neck 4, from the boundary with the head 3 toward the grip 5, the area where the outer contour line is formed by the first straight area L1 and the third straight area L3 in a side view has a constant minimum thickness, and the area where the outer contour line is formed by the curved areas E1, E2 and the curved areas E8, E9 gradually becomes thicker from the minimum thickness. The minimum thickness of the neck 4 at position W (described in detail later) is preferably 5.3 mm or less, more preferably 5.0 mm or less, and even more preferably 4.8 mm or less. When the minimum thickness of the neck 4 is greater than 5.3 mm, there is a possibility that the insertion and operability of the molars may be reduced. From the perspective of strength, the minimum thickness of the neck 4 is preferably 3.5 mm or more.

[0055] The position in the long axis direction where the minimum width is achieved in the neck 4 is W. The cross-sectional secondary distance (width×thickness) associated with the bending in the thickness direction at position W is 3 / 12) is W1, the cross-section secondary wheelbase W1 is preferably 20mm 4 Above, 50mm 4 Below, more preferably 25mm 4 Above, 50mm 4 Below, more preferably 30mm 4 Above, 45mm 4 the following.

[0056] The secondary wheelbase W1 of the section is greater than 50mm 4 In the case of brushing the buccal side of the molars, the neck 4 is clamped in the width direction with the lips, so resistance is felt and the operability in the oral cavity is reduced. 4In the case of , it is difficult to obtain sufficient fatigue resistance. By making the cross-section secondary wheelbase W1 20mm 4 Above, 50mm 4 Below, good operability in the oral cavity and sufficient fatigue resistance can be obtained.

[0057] In addition, when the center that is the center in the long axis direction, thickness direction and width direction of the head 3 is S, and the secondary wheelbase of the cross section related to the bending in the thickness direction at the center S is S1, the value represented by W1 / S1 is preferably greater than 0.9 and less than 1.9, more preferably greater than 0.9 and less than 1.8, and further preferably greater than 1.0 and less than 1.8.

[0058] When the value represented by W1 / S1 is less than 0.9, the head 3 is less likely to bend than the neck 4. In this case, stress concentration caused by bending in the thickness direction is likely to occur on the front end side of the neck 4, fatigue resistance becomes unfavorable, and it is difficult to transfer the load energy to the grip 5 side. When the value represented by W1 / S1 is greater than 1.9, the neck 4 is less likely to bend than the head 3. In this case, the neck 4 moves in conjunction with the head 3 without bending, and the deviation of the bending behavior becomes larger, making it difficult to transfer the load energy to the grip 5 side, and the load is applied only in the neck 4 area.

[0059] The neck 4 has a flexure region 4A that flexes when a load is applied to the head 3. The front end of the flexure region 4A is at position G on the rear end of the head 3, and the rear end is at position I, which is the boundary between the neck 4 and the grip 5 (i.e., the front end of the grip 5). Position G on the front end of the flexure region 4A is, as shown in FIG. Figure 2 As shown, the edge of the rear end side of the hair implantation hole 6a located at the rear end side among the plurality of hair implantation holes 6 provided in the hair implantation surface 3a is located.

[0060] When the longitudinal position that is midway between the longitudinal lengths of the flexure region 4A and the secondary axial distance of the cross section associated with the thickness-direction bending at position H is H1, the width of the neck portion 4 at position H is preferably 5.5 mm or less. By setting the width of the neck portion 4 at position H to 5.5 mm or less, good insertion and operability into the molars can be achieved even at the midpoint of the neck portion 4.

[0061] In addition, the cross-section secondary wheelbase H1 is preferably 28 mm 4 Above, 70mm 4 Below, more preferably 35mm 4 Above, 63mm 4 Below, more preferably 37mm 4 Above, 60mm 4Below. The secondary wheelbase H1 of the section is greater than 70mm 4 In the case of brushing the buccal side of the molars, the lips are used to clamp the neck 4 in the width direction, so resistance is felt, which reduces the operability in the oral cavity. 4 In the case of , it is difficult to obtain sufficient fatigue resistance. By making the cross-section secondary wheelbase H1 28mm 4 Above, 70mm 4 Below, good operability in the oral cavity and sufficient fatigue resistance can be obtained.

[0062] In the neck portion 4, with position H as the starting point and position Q at a distance of 15 mm on the side of the head portion 3, and the secondary centerline distance of the cross section related to the curvature in the thickness direction at position Q as Q1, the value represented by H1 / Q1 is preferably 1.0 or more and 2.0 or less, and more preferably 1.1 or more and 1.5 or less. Furthermore, with position R as the starting point and position R at a distance of 10 mm on the side of the grip portion 5, and the secondary centerline distance of the cross section related to the curvature in the thickness direction at position R as R1, the value represented by R1 / H1 is preferably 1.7 or more and 3.0 or less, and more preferably 1.9 or more and 2.8 or less.

[0063] By setting the value represented by H1 / Q1 and the value represented by R1 / H1 within the above range, the stress concentration accompanying bending in the thickness direction can be moved to the rear end side where the secondary wheelbase of the cross section is large and the bending strength is large, without increasing the width of position H and reducing the operability in the oral cavity, thereby ensuring fatigue resistance.

[0064] like Figure 2 As shown, in the outline of the width direction between position H and position I in the front view, the straight line connecting the end point P1 on the front side and the end point P2 on the rear side preferably intersects obliquely at an angle of 1.9° or more and 6.5° or less (hereinafter referred to as angle θ12) relative to the long axis direction. Figure 1 As shown, in the outer contour line of the back side between position H and position I in a side view, preferably, the straight line connecting the endpoint P4 on the front end side and the endpoint P5 on the rear end side crosses at an angle greater than 3.0° and less than 5.3° relative to the long axis direction (hereinafter referred to as angle θ45).

[0065] In addition, if Figure 2 As shown, in the outline of the width direction between position W and position I in the front view, the straight line connecting the end point P3 on the front side and the end point P2 on the rear side preferably intersects obliquely at an angle of 1.9° or more and 4.5° or less, preferably 2.5° or more and 4.0° or less (hereinafter referred to as angle θ32) relative to the long axis direction. Figure 1As shown, in the outer contour line of the back side between position W and position I in a side view, preferably, the straight line connecting the endpoint P6 on the front end side and the endpoint P5 on the rear end side is inclined and intersects at an angle of greater than 2.0° and less than 3.5°, preferably greater than 2.0° and less than 3.0° (hereinafter referred to as angle θ65) relative to the long axis direction.

[0066] In addition, when there are one or more positions in the longitudinal direction where the minimum width is achieved, the position W is the position on the most distal side where the minimum width is achieved.

[0067] Furthermore, in the widthwise outline of the outer shape between positions W and H in a frontal view, a straight line connecting the front end point P3 and the rear end point P1 preferably intersects obliquely at an angle of 3° or less, preferably 1° or less, relative to the long axis (hereinafter referred to as angle θ31). In the backside outline of the outer shape between positions W and H in a side view, a straight line connecting the front end point P6 and the rear end point P4 preferably intersects obliquely at an angle of 3° or less, preferably 1° or less, relative to the long axis (hereinafter referred to as angle θ64).

[0068] Between positions W and H, where the neck 4 has its minimum width, it is preferable that the angle of inclination of the outer contour line relative to the long axis be small from the perspective of brushing comfort and intraoral operability. On the other hand, if the angle increases sharply between positions H and I, which are closer to the rear end than position H, there is a possibility that the brushing comfort and intraoral operability between positions W and H will be impaired. Therefore, by setting the angle θ12 between positions H and I in the front view and the angle θ45 in the side view within the above ranges, and setting the angle θ32 between positions W and I in the front view and the angle θ65 in the side view within the above ranges, the width and thickness gradually increase toward the rear end, thereby ensuring brushing comfort and intraoral operability throughout the entire neck 4.

[0069] If the above-mentioned cross-sectional quadratic wheelbase is satisfied, the cross-sectional shape of the neck portion 4 is preferably a substantially quadrilateral, a substantially polygonal, a true circle, or an ellipse.

[0070] (Grip)

[0071] The grip 5 is a portion held by the user and is formed in a long columnar shape. In order to ensure sufficient length for gripping and using the grip 5, the length from position W to the rear end of the grip 5 in a front view is preferably 100 to 200 mm.

[0072] Regarding the grip portion 5, the width gradually widens from position I of the boundary with the neck 4 toward the rear end side until the position where the 16th curve area E16 shows a maximum value in the front view. The width gradually narrows from the position where the 16th curve area E16 shows a maximum value in the front view until the position where the 17th curve area E17 shows a minimum value in the front view. The width gradually widens from the position where the 17th curve area E17 shows a minimum value in the front view until the position where the 18th curve area E18 shows a maximum value in the front view. The grip portion 5 of this embodiment reaches its maximum width at the position where the 18th curve area E18 shows a maximum value. The width gradually narrows from the position where the 18th curve area E18 shows a maximum value in the front view until the end of the rear end side.

[0073] Regarding the grip portion 5, the thickness gradually decreases from position I of the boundary with the neck 4 toward the rear end side until the position where the third curved area E3 shows a minimum value when viewed from the side. The thickness gradually increases from the position where the third curved area E3 shows a minimum value when viewed from the side until the position where the fourth curved area E4 shows a maximum value when viewed from the side. The thickness gradually decreases from the position where the fourth curved area E4 shows a maximum value when viewed from the side until the position where the fifth curved area E5 shows a minimum value when viewed from the side. The thickness gradually increases from the position where the fifth curved area E5 shows a minimum value when viewed from the side until the position where the sixth curved area E6 shows a maximum value when viewed from the side.

[0074] like Figure 1 as well as Figure 2 As shown, when the center in the long axis direction, thickness direction and width direction of the gripping portion 5 is T, and the secondary wheelbase of the cross section at the center T related to the bending in the thickness direction is T1, the value represented by T1 / W1 is preferably greater than 6 and less than 26, more preferably greater than 7 and less than 20, and further preferably greater than 7 and less than 14.

[0075] If the value represented by T1 / W1 is less than 6, the neck 4 is less flexible than the grip 5, and stress concentration associated with bending in the thickness direction is likely to occur on the front end of the neck 4, resulting in a disadvantage in terms of strength. On the other hand, if the value represented by T1 / W1 is greater than 26, the bending of the grip 5 is excessively suppressed relative to the bending of the neck 4, and stress concentration is likely to occur near the boundary between the neck 4 and the grip 5, which may cause problems in terms of strength.

[0076] Therefore, as described above, by making the cross-section secondary wheelbase W1 20 mm 4 Above, 50mm 4By setting the value represented by W1 / S1 to be greater than 0.9 and less than 1.9, and the value represented by T1 / W1 to be greater than 6 and less than 26, the flexural behavior between the center S, the position W, and the center T can be controlled. That is, by setting the cross-sectional secondary wheelbase to the above, the cross-sectional secondary wheelbase increases smoothly from the front end of the head 3 toward the grip 5, thereby slowly changing the cross-sectional secondary wheelbase. Thus, in the toothbrush 1 of this embodiment, the front end side is always easy to flex and the rear end side is difficult to flex. Even when a transparent saturated polyester resin is used in the brush body 2, the load energy will not be locally retained and can be smoothly transferred from the front end side to the rear end side, which is advantageous for fatigue resistance.

[0077] In addition, when the position in the long axis direction where the maximum thickness is achieved in the gripping portion 5 is Ta, and the secondary axis distance of the cross section at position Ta related to the bending in the thickness direction is Ta1, the value represented by Ta1 / W1 is preferably greater than 7 and less than 35. In the present embodiment, position Ta is the same position as position I. When the value represented by Ta1 / W1 is less than 7, the neck 4 is difficult to bend compared with the gripping portion 5, and stress concentration accompanying bending in the thickness direction is likely to occur on the front end side of the neck 4, which becomes disadvantageous in terms of strength. On the other hand, when the value represented by Ta1 / W1 is greater than 35, the bending of the gripping portion 5 is excessively suppressed relative to the bending of the neck 4, and stress concentration is likely to occur near the boundary between the neck 4 and the gripping portion 5, which may cause problems in terms of strength.

[0078] like Figure 1 As shown, when the position 20 mm away from the rear end of the grip portion 5 at position U is designated as U, and the point on the outer contour line of the back side at position U in side view is designated as P7, the center S, the endpoint P4 of the above-mentioned position H, the endpoint P5 of position I, and the point P7 of position U are on a substantially straight line. Similarly, when the point of position H on the outer contour line of the front side in side view is designated as P8, the point of position I is designated as P9, and the point of position U is designated as P10, the center S, the point P8 of position H, the point P9 of position I, and the point P10 of position U are on a substantially straight line. Here, “substantially on a straight line” means that when the straight line extending in the long axis direction from the center S is designated as SL, the distances between the endpoint P4, the endpoint P5, the point P7, the point P8, the point P9, and the point P10 and the straight line SL are all less than 5 mm. By locating the endpoints P4, P5, P7, P8, P9, and P10 as described above, there is no significant curvature in the thickness direction from the front end to the rear end of the toothbrush 1. Therefore, in the toothbrush 1, stress loads are prevented from being locally retained and are smoothly transferred to the grip 5 side, which has a greater bending strength.

[0079] Preferably, between the center S and the position U, the outer contour line in side view is entirely formed by lines selected from arcs and straight lines with a radius of 45 mm or greater. Preferably, between the center S and the position U, the intersection angle of a straight line connecting any two points in the outer contour line in side view with a straight line SL extending in the long axis direction from the center S is 8° or less.

[0080] Between the center S and the position U, the outer contour line when viewed from the side is made as specified above, so that in the toothbrush 1, no large concave and convex parts are set on the outer contour line when viewed from the side, and the stress load can be prevented from being locally retained and smoothly transferred to the side of the gripping part 5 with high bending strength.

[0081] When the secondary axis distance of the cross section at position U, which is related to bending in the thickness direction, is U1, the value represented by U1 / W1 is preferably greater than 6 and less than 25, and more preferably greater than 7 and less than 20. If the value represented by U1 / W1 is less than 6, the neck 4 is less likely to flex than the grip 5, and stress concentration associated with bending in the thickness direction is likely to occur on the front end of the neck 4, which is disadvantageous in terms of strength. On the other hand, if the value represented by U1 / W1 is greater than 25, the bending of the grip 5 is excessively suppressed relative to the bending of the neck 4, and stress concentration is likely to occur near the boundary between the neck 4 and the grip 5, which may cause strength problems.

[0082] like Figure 1 As shown, in the grip portion 5, a position 10 mm away from position I on the front end side is designated J, the secondary wheelbase of the cross section at position J related to the bend in the thickness direction is designated J1, and when the secondary wheelbase of the cross section at position I related to the bend in the thickness direction is designated I1, the value represented by I1 / J1 is preferably 2.0 or more and 6.0 or less, more preferably 2.5 or more and 4.0 or less. Furthermore, the value represented by U1 / I1 is preferably 0.5 or more and 1.1 or less.

[0083] When the values ​​represented by I1 / J1 and U1 / I1 are within the above ranges, the stress load can be prevented (suppressed) from being locally retained near the boundary between the neck 4 and the grip 5 and smoothly transferred to the grip 5 side having greater bending strength.

[0084] Between the above-mentioned position Q and position R, the outer contour line is preferably formed by an arc-shaped curve with a radius of greater than 100 mm and less than 500 mm, or a straight line intersecting a straight line extending in the long axis direction at an angle of greater than 1.7° and less than 4°, and more preferably by a straight line intersecting at an angle of greater than 1.8° and less than 3°, from a frontal perspective.

[0085] In addition, between the above-mentioned positions Q and R, the outer contour line is preferably formed by an arc-shaped curve with a radius of 200 mm or more, or a straight line intersecting a straight line extending in the long axis direction at an angle of 1.0° or more and 1.4° or less when viewed from the side.

[0086] Between position Q and position R of the neck 4, by setting the outer contour lines in the front view and the side view as specified above, the cross-sectional area of ​​the neck 4 slowly increases between position Q and position R, and the stress load can be more smoothly transferred to the side of the gripping portion 5 with greater bending strength.

[0087] As described above, in the toothbrush 1 of this embodiment, by making the cross-sectional secondary wheelbase ratio in each part of the head 3, neck 4 and grip 5 appropriate, the load energy will not be locally retained, but can be transferred to the rear end side which is advantageous in fatigue resistance, thereby providing a transparent toothbrush 1 with ensured fatigue resistance.

[0088] [Example]

[0089] The effects of the present invention will be described more clearly below by way of examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications within the scope of the present invention.

[0090] (Examples 1 to 7, Comparative Examples 1 to 6)

[0091] In this embodiment, the toothbrushes of Examples 1 to 7 and Comparative Examples 1 to 6 were made into the same Figure 1 and Figure 2 Same sample of toothbrush shown.

[0092] The handle of each toothbrush example had a total length of 180 mm, and the dimensions of each part were as shown in Table 1. PCTA resin was used for the brush body.

[0093] [Evaluation method]

[0094] (1) Fatigue durability

[0095] [Test method] Regarding fatigue durability, a portion of the grip portion 60 mm from the rear end was fixed, and a load of 50 mm displacement was repeatedly applied to the head at a speed of 240 rpm (number of samples; n=5).

[0096] The case where none of the wires broke and none of the cracks occurred when the above-mentioned load was repeatedly applied 1 million times was set as "A", the case where none of the wires broke and a crack smaller than 0.5 mm was confirmed in one wire when the above-mentioned load was applied 1 million times was set as "B", the case where none of the wires broke and a crack larger than 0.5 mm was confirmed in one wire when the load was applied 1 million times was set as "C", the case where no more than one wire broke between 900,000 and 1,000,000 times was set as "D", the case where no more than one wire broke between 800,000 and 900,000 times was set as "E", the case where one wire broke when the load was applied 500,000 to 800,000 times was set as "F", and the case where one wire broke when the load was applied less than 500,000 times was set as "G".

[0097] (2) Oral operability

[0098] [Test Method] Ten monitors cleaned the oral cavity and evaluated the operability of each toothbrush.

[0099] The operability was evaluated on a 7-point scale from 1 to 7 points, with the better the operability, the higher the score. The average scores of the 10 monitors were classified according to the following criteria to evaluate the operability in the oral cavity.

[0100] <Judgment Criteria>

[0101] A: Average score is 6.0 or above

[0102] B: Average score is 5.5 or higher but less than 6.0

[0103] C: Average score is 5.0 or higher but less than 5.5

[0104] D: Average score is 4.5 or higher but less than 5.0

[0105] E: Average score is 4.0 or higher but less than 4.5

[0106] F: Average score is 3.5 or higher but less than 4.0

[0107] G: Average score less than 3.5

[0108] [Table 1A]

[0109]

[0110] [Table 1B]

[0111]

[0112] As shown in [Table 1A] and [Table 1B], the thickness of the head is 2 mm or more and 3.8 mm or less in the entire region, the minimum width of the neck is 5.3 mm or less, and the cross-section secondary wheelbase W1 is 20 mm.4 Above, 50mm 4 In the samples of Examples 1 to 7, in which the value represented by W1 / S1 was 0.9 or more and 1.9 or less and the value represented by T1 / W1 was 6 or more and 26 or less, good results were obtained in all of fatigue durability, oral operability, and impact durability.

[0113] On the other hand, the sample of Comparative Example 1, in which the value of the cross-sectional secondary wheelbase (W1 / S1) deviated from the range of 0.9 or more and 1.9 or less, did not receive a favorable evaluation of fatigue durability. The sample of Comparative Example 2, in which the head thickness, minimum neck width, and cross-sectional secondary wheelbase (W1) deviated from the preferred range, did not receive a favorable evaluation of intraoral operability. The sample of Comparative Example 3, in which the head thickness, minimum neck width, cross-sectional secondary wheelbase (W1), and the value of T1 / W1 deviated from the preferred range, did not receive a favorable evaluation of intraoral operability.

[0114] In the sample of Comparative Example 4, where the minimum width of the neck and the value represented by W1 / S1 deviated from the preferred range, good evaluation of intraoral operability was not achieved. In the sample of Comparative Example 5, where the value represented by W1 / S1 deviated from the preferred range, good evaluation of fatigue durability was not achieved. In the sample of Comparative Example 6, where the cross-sectional secondary wheelbase W1 and the value represented by T1 / W1 deviated from the preferred range, good evaluation of fatigue durability was not achieved.

[0115] The above description is of preferred embodiments of the present invention with reference to the accompanying drawings. However, it should be understood that the present invention is not limited to the examples shown. The various shapes and combinations of components shown in the above examples are merely examples, and various modifications may be made based on design requirements, etc., without departing from the spirit of the present invention.

[0116] [Industrial Applicability]

[0117] The present invention can be applied to toothbrushes.

Claims

1. A toothbrush, characterized in that: The toothbrush comprises a brush body having a head portion located at the front end and having a hair-planted surface, a grip portion located at the rear end relative to the head portion, and a neck portion disposed between the head portion and the grip portion. The brush body is made of transparent saturated polyester resin. In the first direction perpendicular to the hair-planting surface, the thickness of the head is greater than or equal to 2 mm and less than or equal to 3.8 mm in the entire region. In a second direction perpendicular to the long axis direction of the brush body and the first direction, the minimum width of the neck is 5.3 mm or less. The position where the neck has the minimum width in the longitudinal direction is defined as W, and the secondary axis distance of the cross section at the position W related to the bending in the first direction is defined as W1. The center of the head in the longitudinal direction, the first direction, and the second direction is set as S, and the secondary axis distance of the cross section related to the bending in the first direction at the center S is set as S1. The center of the gripping portion in the longitudinal direction, the first direction, and the second direction is set as T, and the secondary wheelbase of the cross section at the center T related to the bending in the first direction is set as T1. The secondary wheelbase W1 of the cross section is 20 mm 4 Above, 50mm 4 the following, The value represented by W1 / S1 is 0.9 or more and 1.9 or less, The value represented by T1 / W1 is 6 or more and 26 or less.

2. The toothbrush according to claim 1, wherein When the position in the middle of the length of the long axis direction of the bending area of ​​the neck relative to the front side as the hair-implanted surface in the first direction is H, and the secondary wheelbase of the cross section related to the bending in the first direction at position H is H1, The width of the second direction at the position H is 5.5 mm or less, and the cross-section secondary wheelbase H1 is 28 mm. 4 Above, 70mm 4 the following, Taking the position H as the starting point, the position 15 mm away from the head side is set as Q, the position 10 mm away from the grip side is set as R, the secondary wheelbase of the cross section related to the bending in the first direction at the position Q is set as Q1, and the secondary wheelbase of the cross section related to the bending in the first direction at the position R is set as R1, The value represented by H1 / Q1 is 1.0 or more and 2.0 or less. The value represented by R1 / H1 is 1.7 or more and 3.0 or less.

3. The toothbrush according to claim 2, characterized in that The end of the front end side of the long axis direction of the bending area in the front view is: the edge of the rear end side of the hair implantation hole that is closest to the rear end side among the multiple hair implantation holes provided on the hair implantation surface, The end portion of the flexure region on the rear end side in the longitudinal direction in the front view is the end portion on the front end side of the grip portion. When the end portion of the bending region on the rear end side in the longitudinal direction is set to position I, In the outer contour line in the second direction in the front view between the position H and the position I, a straight line connecting the end point on the front side and the end point on the rear side has an inclination of 1.9° or more and 6.5° or less with respect to the long axis direction, From a side perspective observed from one side in the second direction, in the outer contour line of the back side on the opposite side of the front side in the first direction between the position H and the position I, the straight line connecting the endpoint of the front end side and the endpoint of the rear end side has an inclination of more than 3.0° and less than 5.3° relative to the long axis direction.

4. The toothbrush according to claim 3, wherein When the position 20 mm from the rear end side of the position I is set as U, The center S in the side view and the position H, position I, and position U in the outer contour line on the front side are substantially on a straight line, The center S and the position H, position I, and position U of the outer contour line on the back side are substantially on a straight line in the side view. The distances between position H, position I, and position U in the outer contour line in the side view and a straight line extending in the long axis direction starting from the center S are all less than 5 mm.

5. The toothbrush according to claim 4, characterized in that Between the center S and the position U, the outer contour lines of the side view are all formed by lines selected from arcs and straight lines with a radius of more than 45 mm, Between the center S and the position U, a straight line connecting any two points in the outer contour line of the side view has an intersection angle of 8° or less with a straight line extending in the long axis direction starting from the center S.

6. The toothbrush according to any one of claims 1 to 5, characterized in that The transparent saturated polyester resin is PCTA resin.

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