toothbrush

Abstract

This toothbrush harmonizes the textures of soft bristles and rigid bristle bundles to provide a toothbrush that allows for comfortable brushing without any discomfort. [Solution] The brush comprises soft bristles formed in a filament shape from a soft resin, stiff bristle bundles that are more rigid than the soft bristles, and a head portion on the front side in the thickness direction, with the soft bristles and stiff bristle bundles arranged in a planar direction perpendicular to the thickness direction. Of the planar directions, the brush has at least one soft bristle group in which multiple soft bristles are arranged continuously in the longitudinal axis direction or the width direction perpendicular to the longitudinal axis direction of the head portion. The soft bristle groups and stiff bristle bundles are arranged according to a specification based on the texture resulting from the interaction of adjacent soft bristle groups and stiff bristle bundles during brushing.

Description

Technical Field

[0001] The present invention relates to a toothbrush.

Background Art

[0002] In a toothbrush, soft bristles formed of a soft resin and a rigid bristle bundle having a greater rigidity than the soft bristles have greatly different physical properties, and thus may be used in combination within one head for different purposes. For example, Patent Document 1 discloses using a rigid bristle bundle for a cleaning purpose of scraping off dirt and using soft bristles for a cleaning purpose of wiping off dirt.

[0003] Both the soft bristles and the rigid bristle bundle are used for cleaning purposes. However, due to the large difference in physical properties, for example, by making the occupied volume of the soft bristles larger than that of the rigid bristle bundle, they are designed with specifications to perform different movements and roles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above specifications, substantially only the rigid bristle bundle plays a cleaning role, and it is difficult for the soft bristles with a large occupied volume to clean every corner of the mouth such as the gaps between teeth due to their shape. Also, due to the physical property that the rigid bristle bundle is difficult to bend while the soft bristles bend too much and the bristle tips do not work, a problem occurs in that a foreign body sensation is felt in either the rigid bristle bundle or the soft bristles, and the usability deteriorates. Therefore, there has been a demand for a toothbrush that can be brushed without discomfort by harmonizing the texture while taking advantage of the characteristics of the soft bristles and the rigid bristle bundle.

[0006] This invention was made with the above points in mind, and aims to provide a toothbrush that allows for comfortable brushing by harmonizing the texture of soft bristles and rigid bristle bundles. [Means for solving the problem]

[0007] The present invention has the following aspects. [1] Soft bristles formed in a filament shape from soft resin, A bundle of stiff hairs having greater rigidity than the aforementioned soft hairs, The head portion is arranged such that the soft bristles and the rigid bristle bundles are arranged on the front side in the thickness direction, in a plane direction perpendicular to the thickness direction, Equipped with, The head portion has at least one group of soft bristles arranged in a continuous manner in the longitudinal axis direction or in the width direction perpendicular to the longitudinal axis direction, A toothbrush in which the soft bristles and rigid bristles are arranged according to a specification based on the texture resulting from the interaction between the soft bristles and rigid bristles during brushing, arranged in adjacent combinations. [2] The rigid hair bundles adjacent to and facing the soft hair bundles are designated as opposing hair bundles, and the rigid hair bundles that are not adjacent to each other are designated as non-opposing hair bundles. Among the soft group and the opposing bundle of hairs, the line segment extending in the width direction starting from the position closest to the tip in the long axis direction on the head portion is defined as line segment A. Among the soft group and the opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the rear end in the longitudinal axis direction on the head portion is defined as line segment B. Among the soft group and the opposing bundle of hair, the line segment C is defined as the line segment extending in the longitudinal direction starting from the position on one side in the width direction of the head portion. Among the soft group and the opposing bundle of hair, the line segment D is defined as the line segment extending in the longitudinal direction starting from the position furthest to the other side in the width direction on the head portion. When the region enclosed by line segment A, line segment B, line segment C, and line segment D is defined as region E, In the region E, at least one of the following conditions is met: the non-opposing hair bundle is not provided; the non-opposing hair bundle is sandwiched between the opposing hair bundle in at least one direction of the longitudinal axis and the width direction; and the non-opposing hair bundle is positioned at the outermost edge while facing the opposing hair bundle in at least one direction of the longitudinal axis and the width direction. The sum of the areas of the holes in the non-opposing hair bundles in the head portion is less than or equal to the sum of the areas of the holes in the opposing hair bundles. The toothbrush described in [1] above. [3] The aforementioned soft group is provided in two or more locations, where they are not adjacent to each other. The toothbrush described in [2] above. [4] Between each of the soft groups arranged in a manner that is not adjacent in the longitudinal direction, at least one rigid bundle, including the opposing bundle, is arranged. Of the rigid hair bundles arranged in the region sandwiched between the two soft groups in the longitudinal direction, let H be the total area of ​​the holes in the rigid hair bundles that overlap with the soft groups in the longitudinal direction. If G is the total area of ​​the two soft groups that sandwich the rigid hair bundle in the longitudinal direction, G>H Satisfying the relationship, The toothbrush described in [3] above. [5] Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the tip in the longitudinal direction on the head portion is defined as line segment a. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the rear end in the longitudinal axis direction on the head portion is defined as line segment b. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment c is defined as the line segment extending in the longitudinal direction starting from the position on the far side in the width direction of the head portion. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment d is defined as the line segment extending in the longitudinal direction starting from the position furthest to the other side in the width direction on the head portion. When the region surrounded by the line segment a, the line segment b, the line segment c, and the line segment d is defined as region e, the area of the region E is 60% or more of the area of the region e, The toothbrush according to any one of [2] to [4]. [6] Let the total area of the base portion surrounding the proximal end in the soft group of the region E be F, When the total area of the holes of the rigid tufts in the region E is J, F > J satisfying the relationship of, The toothbrush according to any one of [2] to [5]. [7] The outer shape of the soft group extends in the width direction and is arranged in plurality in the long axis direction, Between the soft groups arranged in plurality in the long axis direction, they are partitioned by at least the opposing tufts arranged side by side in the width direction. The toothbrush according to any one of [2] to [6]. [8] The outer region forming the outer contour has the soft group extending in the width direction, The distance in the long axis direction between the line segment K on the tip side and the line segment L on the rear end side in the outer region having the highest occupancy with respect to the width of the head portion is 1 time or more and less than 4 times the diameter of the proximal end of the opposing tuft that faces adjacent to the soft group having the outer region. The toothbrush according to any one of [2] to [7]. [9] The non-opposing tufts are not arranged in the region E, The toothbrush according to any one of [2] to [8].

Advantages of the Invention

[0008] In the present invention, it becomes possible to provide a toothbrush that harmonizes the textures of the soft bristles and the rigid tufts and enables brushing without a sense of discomfort.

Brief Description of the Drawings

[0009] [Figure 1] This figure shows an embodiment of the present invention, and is a front view showing the head portion of a toothbrush. [Figure 2] This figure shows an example of how rigid bristle bundles and soft bristle bundles are indicated separately based on regulation (2). [Figure 3] This figure shows an example of arrangement of rigid and soft hair bundles based on the standard (2-1). [Figure 4] This figure shows an example of arrangement of rigid bristle bundles and soft bristle bundles based on regulations (2-2) and (2-3). [Figure 5] This figure shows an example of how rigid bristles and soft bristles are arranged based on the longitudinal dimension of the outer region of the soft bristles and the diameter of the base end of the opposing bristles. [Figure 6] This is a magnified section of Figure 5. [Figure 7] This is a partially enlarged view showing a modified shape of the outer region of the soft tissue group. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments of the toothbrush of the present invention will be described with reference to Figures 1 to 4. The following embodiments represent one aspect of the present invention and are not intended to limit it. They can be modified at will within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components in each structure differ from the actual structure in order to make the components easier to understand.

[0011] Figure 1 is a front view showing the head portion of a toothbrush 1 according to one embodiment of the present invention. As shown in Figure 1, the toothbrush 1 is equipped with a handle body 2, and the handle body 2 is generally composed of a long gripping portion (not shown) and a head portion 4 provided at the tip of the gripping portion.

[0012] The head portion 4 has a roughly rectangular shape in plan view, with the vertical direction in Figure 1 as the long axis and the horizontal direction as the width. The head portion 4 has a flocked surface 5. The flocked surface 5 is located on the front side of the head portion 4 in the thickness direction (hereinafter simply referred to as the "thickness direction"). The thickness direction of the head portion 4 is perpendicular to the plane of the paper in Figure 1, and the front side is the side facing the viewer relative to the plane of the paper. The flocked surface 5 is parallel to the plane direction perpendicular to the thickness direction.

[0013] In the explanation, an XYZ coordinate system may be set up, and the positional relationships of each component may be explained while referring to this XYZ coordinate system. In this case, the thickness direction is defined as the Z-axis direction, the longitudinal direction of the toothbrush 1 which is perpendicular to the thickness direction is defined as the Y-axis direction, and the width direction which is perpendicular to both the thickness direction and the longitudinal direction is defined as the X-axis direction in the diagram. For the head part 4, the side that moves away from the handle body 2 in the Y-axis direction is called the "tip side," and the side that moves closer to the handle body 2 is called the "rear end side."

[0014] The handle body 2, including the head portion 4, is made of a hard resin. Examples of hard resins used to form the handle body 10 include resins with a flexural modulus (JIS K7171) of 1500 MPa or more and 3000 MPa or less. Specifically, examples include polypropylene resin (PP), polybutylene terephthalate resin (PBT), polyacetal resin (POM), polyester resin (PCTA), polyethylene terephthalate copolymer (PETG), and high-density polyethylene (HDPE). Among these, polypropylene resin is preferred when considering manufacturing costs as it is a general-purpose resin, while polybutylene terephthalate resin and polyacetal resin are preferred when considering strength.

[0015] On the front side of the bristle surface 5 of the head portion 4, soft bristles 10 and rigid bristle bundles 20 are arranged. The soft bristles 10 are formed in a filament shape from soft resin. The soft bristles 10 are formed in a cylindrical, prismatic, or conical (tapered) shape, for example, in a straight line toward the front. In Figure 1, the soft bristles 10 are triangular in a front view.

[0016] The soft bristles 10 in the shape of filaments include those in which adjacent soft resin filaments share a base (of a certain height), and the filaments are formed upward from the base. The filament shape also includes those in which adjacent soft resin filaments share a base (of a certain height) protruding from the head portion 4, and the filaments are formed by extending upward (towards the front) from the base. The "certain height" is a height that does not hinder the movement of the rigid bristle bundle 20 and the soft bristles 10 when they move in a similar manner, and is preferably 2.0 mm or less.

[0017] The base is formed from the same material as the soft bristles 10 and is the part to which the base end of the soft bristles 10 is connected. The base can be configured to be flush with the bristle surface 5, or, as described above, to be provided with a step between it and the bristle surface 5. Alternatively, there may be no base, and the base end of the soft bristles 10 may be connected to a head portion 4 made of, for example, a hard resin. More preferably, there is no base with a step between it and the flocked surface 5, and each filament is formed independently upward from the flocked surface 5 which serves as the base.

[0018] The soft bristles 10, which are filament-shaped and made of soft resin, preferably have a cross-sectional area of ​​1.5 mm² at the base end on the bristle surface 5. 2 The following applies: There is no particular limit to the cross-sectional area of ​​the base, but it is 0.1 mm. 2 That concludes the explanation. Within the above scope, by combining it with other inventive configurations, the rigid bristle bundle 20 and the soft bristles 10 will achieve similar movement, and the following effects will be improved.

[0019] Various elastomers can be used as the soft resin constituting the soft bristles 10, but polyurethane is preferred. Polyurethane tends to have higher tensile strength than other elastomers such as styrene-based and polyester-based elastomers, so by using polyurethane as the soft resin, mechanical strength can be ensured even with thin walls. The polyurethane contains 0.01 to 1.0 wt% (mass%) of one or a combination of saturated / unsaturated hydrocarbons of C10 or higher, higher alcohols, fatty acid amides, fatty acid esters, low molecular weight polyethylene, polyethylene glycol (PEG), fatty acid metal salts, long-chain fatty acids, fatty acid glycerin, liquid paraffin, or silicone, and functions as a lubricant and mold release agent. The hardness of the polyurethane is preferably such that the Shore hardness is A90 or higher and A100 or lower, or the Shore hardness is D40 or higher and D70 or lower.

[0020] If the polyurethane hardness is softer than Shore 90A, it becomes more prone to deformation when formed in a thin wall, resulting in a weaker fit and making the brush body 20 more likely to detach during use of the toothbrush 1. If the polyurethane hardness is harder than Shore 70D, pain may occur when the tip touches oral tissue if the back surface of the head base 21 is sloped. By setting the polyurethane hardness to a Shore hardness of A90 or higher and A100 or lower, or a Shore hardness of D40 or higher and D70 or lower, pain during use of the toothbrush 1 can be suppressed. Furthermore, from the viewpoint of ensuring water resistance and antibacterial properties, it is preferable to use ether-based polyurethane.

[0021] The soft bristles 10 are, for example, molded by injection molding. If the head portion 4 is made of hard resin, the soft bristles 10 are molded, for example, by insert molding using a mold in which the head portion 4 is installed.

[0022] The rigid bristle bundles 20 are more rigid than the soft bristles 10 as a whole. The rigid bristle bundles 20 are planted in circular holes (bristle holes) 6 that are recessed on the front side and the back side opposite the bristle surface 5 in the thickness direction. While there are no particular limitations on the material of the brush, examples include synthetic resin materials such as polyamide (e.g., 6-12 nylon, 6-10 nylon), polyester (e.g., polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate), polyolefin (e.g., polypropylene), and elastomer (e.g., olefin-based, styrene-based). Furthermore, multiple resin materials may be used in combination; for example, different resin materials can be used for the core and sheath sections, as in a core-sheath structure.

[0023] The diameter of the bristles constituting the rigid bristle bundle 20 is, for example, 4 to 9 mil (1 mil = 1 / 1000 inch = 0.025 mm). If it is 4 mil or more, sufficient bristle stiffness is ensured to effectively clean the gingival margin, and if it is 9 mil or less, sufficient flexibility is ensured to mitigate irritation to the gums, etc. In the case of tapered bristles, the bristle diameter is the diameter of the base end on the bristle implantation surface 5.

[0024] Methods for fixing the rigid bristle bundle 20 to the head portion 4 (hole 6) include a heat fusion method (pressure-temperature-time (PTt) method) in which the molten portion of the lower end of the bristle bundle is pressed into the molten resin that will become the head portion 4 to fix it, and an in-mold method in which the lower end of the bristle bundle is heated to form a molten mass, and then the molten resin is injected into a mold to form the head portion.

[0025] In Figure 1, the soft bristles 10 and rigid bristle bundles 20 (holes 6) of this embodiment are arranged in multiple rows (3, 5, or 6 in Figure 1) spaced apart in the width direction at the same position in the longitudinal direction, and these rows are spaced apart in the longitudinal direction (9 rows in Figure 1), arranged in a plane direction parallel to the bristle surface 5. Furthermore, in the central region in the longitudinal direction where the width dimension is maximum in the head portion 4, the rigid bristle bundles 20 (holes 6) are arranged at the same position in the width direction, spaced apart in the longitudinal direction.

[0026] In this embodiment, for convenience, the rigid bristle bundles 20 (holes 6) are of the same diameter when viewed from the front, and the soft bristles 10 are of the same shape and size when viewed from the front. However, a configuration in which rigid bristle bundles 20 (holes 6) of different diameters and soft bristles 10 of different shapes and sizes are mixed is also possible.

[0027] The inventors have found that by controlling how many areas on the head portion 4 are provided where soft bristles 10 and rigid bristle bundles 20, formed in a filament shape, are arranged adjacent to each other, the texture can be improved by the interaction between the soft bristles 10 and rigid bristle bundles 20 during brushing.

[0028] Therefore, in this embodiment, there is at least one soft group 11 in which multiple filament-shaped soft bristles 10 are arranged in a continuous line in the longitudinal axis direction or width direction, and the soft bristles 10 and rigid bristle bundles 20 are arranged according to the texture determined by the interaction between adjacent soft group 11 and rigid bristle bundles 20 during brushing.

[0029] The following describes in detail the arrangement rules based on texture resulting from interactions during brushing. The arrangement rules have rules (1)-(3). Provision (1) is that the brush has at least one soft group 11 in which multiple soft bristles 10 are arranged continuously in the longitudinal direction or in the width direction. As shown in Figure 1, the head portion 4 has two soft groups 11 in which 15 soft bristles 10 are arranged in the width direction, separated in the longitudinal direction and not adjacent to each other, via rows of rigid bristle bundles 20 arranged in the width direction.

[0030] When only one soft bristle group 11 is provided, the areas where the rigid bristle bundle 20 and the soft bristles 10 interact with each other are reduced. However, when two soft bristle groups 11 are provided, separated in the longitudinal direction and not adjacent to each other, the areas where they interact with each other increase. This brings the amount of flexure and the position of flexure in the bristle length direction of the rigid bristle bundle and the soft resin bristles closer together, as described later. This allows the bristles to accurately contact the area to be polished, and the ability of each bristle to work more effectively improves the overall cleaning performance of the oral cavity. As a result, harmonious flexure is achieved, which will be explained in more detail later.

[0031] Provision (2) states that rigid bristle bundles 20 adjacent to and facing the soft group 11 are designated as opposing bristle bundles 21, and rigid bristle bundles 20 that are not adjacent are designated as non-opposing bristle bundles 22, and in region E described later, at least one of the following conditions is met: provision (2-1) "Non-opposing bristle bundles 22 are not provided", provision (2-2) "Non-opposing bristle bundles 22 are sandwiched between opposing bristle bundles 21 in at least one direction in the longitudinal axis direction and the width direction", and provision (2-3) "Non-opposing bristle bundles 22 are positioned at the outermost edge while facing opposing bristle bundles 21 in at least one direction in the longitudinal axis direction and the width direction". Other forms according to each provision will be described in the embodiments described later.

[0032] Here, "adjacent to and facing the soft group 11" means a rigid bristle bundle 20 that at least partially overlaps with the soft group 11 when the soft group 11 is moved in at least one direction (long axis direction or width direction), and is defined as a rigid bristle bundle 20 whose distance from the soft bristles 10 constituting the soft group 11 is 1.5 mm or less. Even if a rigid bristle bundle 20 faces the soft group 11, it is excluded from the opposing bristle bundle 21 if it does not interact with the soft bristles 10 when they bend.

[0033] Figure 2 shows an example of how the rigid bristle bundles 20 (opposing bristle bundles 21 and non-opposing bristle bundles 22) and the soft group 11 are distinguished according to regulation (2). In Figure 2, the opposing bristle bundles 21 are shown in white. Also in Figure 2, the soft group 11 is shown enclosed by a dashed line and with hatching. The above display method is also adopted in Figure 2 and subsequent figures.

[0034] Opposing bristle bundles 21 include stiff bristle bundles 20 (the third row of stiff bristle bundles 20 from the very front) that are positioned opposite the soft group 11 located at the front and aligned in the width direction from the front. Opposing bristle bundles 21 include stiff bristle bundles 20 that are positioned between two soft groups 11 and are opposite the soft group 11, aligned in the width direction. Opposing bristle bundles 21 include stiff bristle bundles 20 (the third row of stiff bristle bundles 20 from the very back) that are positioned opposite the soft group 11 located at the rear end and aligned in the width direction from the rear end. The non-opposing bristle bundles 22 consist of the first and second rows of rigid bristle bundles 20 from the frontmost end, and the first and second rows of rigid bristle bundles 20 from the rearmost end.

[0035] In regulation (2), among the soft group 11 and the opposing bristle bundles 21, line segment A is defined as the line segment extending in the width direction starting from the furthest forward position in the head portion 4 (defined by the edge of the hole in the opposing bristle bundles 21), and line segment B is defined as the line segment extending in the width direction starting from the furthest rear end position in the head portion 4 (defined by the edge of the hole in the opposing bristle bundles 21). Line segment A is the line segment that extends in the width direction, touching the tip side of the hole 6 of the third row of rigid bristle bundles 20 from the furthest forward side. Line segment B is the line segment that extends in the width direction, touching the rear end side of the hole 6 of the third row of rigid bristle bundles 20 from the rearmost side.

[0036] Similarly, among the soft group 11 and the opposing bristle bundle 21, let line segment C be the line segment extending in the long axis direction starting from the position on the farthest widthwise side (+X side) of the head portion 4, and let line segment D be the line segment extending in the long axis direction starting from the position on the farthest widthwise side (-X side) of the head portion 4. Line segment C is the line segment extending in the long axis direction at the position on the farthest +X side of the two soft groups 11. Line segment D is the line segment extending in the long axis direction at the position on the farthest -X side of the two soft groups 11. Region E (shown by a dashed line in Figure 2) is a rectangular area enclosed by line segments A, B, C, and D. Region E is the region in which either the soft group 11 or the opposing hair bundle 21 is involved.

[0037] Figure 3 shows an example in which the rigid hair bundle 20 and the soft hair group 11 are arranged according to the standard (2-1). As shown in Figure 3, rigid bristle bundles 20 aligned in the width direction and soft bristle bundles 11 extending in the width direction are arranged alternately in an adjacent, opposing state along the long axis. Therefore, in the arrangement shown in Figure 3, the condition "no non-opposing bristle bundles 22 are provided" applies to region E.

[0038] Furthermore, the provision (2-2) that "the non-opposing hair bundle 22 is sandwiched between opposing hair bundles 21 in at least one direction, both in the longitudinal axis direction and the width direction" is defined as follows: First, for each of the multiple opposing hair bundles 21, a straight line is drawn connecting the non-opposing hair bundle 22 to each adjacent opposing rigid hair bundle 20, and the combination with the largest intersection angle between the intersecting lines is selected. When the intersection angle of the selected combination exceeds 90 degrees and is 180 degrees or less, the non-opposing hair bundle 22 is defined as being sandwiched between the opposing hair bundles 21 connected by the straight line with the largest intersection angle. In this case, the movement of the non-opposing hair bundle 22 can be canceled out by the harmonious bending of the opposing hair bundles 21. The intersection angle is preferably 180 degrees.

[0039] The provision (2-3) that "the non-opposing hair bundle 22 is positioned at the outermost edge while facing the opposing hair bundle 21 in at least one direction in the longitudinal axis direction and the width direction" means that in the region close to the outermost edge of the head part 4, by deliberately positioning the non-opposing hair bundle 22, the harmonious bending of the soft group 11 and the opposing hair bundle 21 does not exceed the outermost edge excessively, thereby blocking excessive bending and further enhancing the harmony of the textures of the soft group 11 and the opposing hair bundle 21.

[0040] Figure 4 shows an example in which the rigid hair bundles 20 and the soft hair group 11 are arranged according to the specifications (2-2) and (2-3). As shown in Figure 4, the two rigid bristles 20 located between the two soft groups 11 in the center of the long axis direction in region E and positioned at both ends in the width direction are non-opposing bristles 22 because they do not face the soft groups 11. These non-opposing bristles 22 face the two opposing bristles 21 in the long axis direction and are adjacent to and face one opposing bristles 21 in the width direction. Starting from the non-opposing bristles 22, a straight line is drawn connecting each of the three adjacent and opposing rigid bristles 20, and the combination with the largest intersection angle between the intersecting lines is selected. In this case, the tolerance angles are 90° and 180°, so these non-opposing bristles 22 are sandwiched between the two opposing bristles 21 that face each other in the long axis direction and intersect at the largest intersection angle of 180°. At this time, the intersection angle of 180° satisfies the requirement (2-2).

[0041] Furthermore, as shown in Figure 4, the two rigid bristle bundles 20 located at the rear end corner of region E are non-opposing bristle bundles 22 because they do not face the soft group 11. These non-opposing bristle bundles 22 are positioned at the outermost edge while facing the opposing bristle bundles 21 in the width direction, thus satisfying requirement (2-3). Therefore, the arrangement of the rigid hair bundles 20 and the soft hair group 11 shown in Figure 4 satisfies requirement (2).

[0042] Rule (3) states that the sum of the areas of the holes 6 of the non-opposing hair bundles 22 in the head portion 4 is less than or equal to the sum of the areas of the holes 6 of the opposing hair bundles 21.

[0043] For example, if there is a large group within region E in which either rigid bristle bundles 20 or soft bristles 10 are locally provided, the properties of one or the other will become more prominent, and the overall cleaning performance of the oral cavity will not be improved, nor will the feeling of a foreign object be eliminated. For example, if only soft bristles 10 are used, they will bend significantly from the base. On the other hand, if only rigid bristle bundles 20 are used, the amount of bending at the tip of the bristles will be small due to the rebound from the surrounding bristle bundles.

[0044] According to regulation (2), the amount of deflection and the position of deflection in the direction of the hair length of the rigid bristle bundle 20 and the soft bristle bundle 10 within region E become closer, stabilizing the brushing surface. As a result, the tips of the rigid bristle bundle 20 and the soft bristle bundle 10 make precise contact with the area to be polished, eliminating the feeling of foreign matter (regulation effect 1). In order to effectively exhibit the above-mentioned prescribed effect 1, it is preferable that no non-opposing hair bundles 22 are placed within region E.

[0045] Within region E, if the rigid hair bundle 20 is composed of opposing hair bundles 21, the rigid hair bundle 20 will always flex in conjunction with the adjacent soft hair 10, resulting in harmonious flexing. Furthermore, even if a non-opposing hair bundle 22 exists, if it is sandwiched between opposing hair bundles 21 in at least one direction (long axis direction or width direction), the flexing behavior of the non-opposing hair bundle 22 will blend in with the flexing behavior of the opposing hair bundles 21 and the soft hair 10, making it less likely to be perceived as unusual. Moreover, if the non-opposing hair bundle 22 is adjacent to the opposing hair bundle 21 but located at the outermost edge, there are no hair bundles further outside, so the flexing of the non-opposing hair bundle 22 will easily synchronize with its surroundings and less likely to be perceived as unusual (predefined effect 2).

[0046] Furthermore, the interaction between the rigid bristle bundles 20 and the soft bristles 10 within region E makes it easier for each bristle tip to work, thereby improving the overall cleaning performance of the oral cavity. Specifically, the appropriate arrangement of the rigid bristle bundles 20 limits the amount of bending of the soft bristles 10 when brushing or when the toothbrush 1 is pressed against the teeth, causing only the bristle tips to deform and buckle, thereby increasing the resistance of the bristle tips and their ability to reach between teeth. On the other hand, the rigid bristle bundle 20, with its appropriately arranged soft bristles 10, exhibits increased flexibility when brushing or when the toothbrush 1 is pressed against the teeth, thereby enhancing the resilience of the bristle tips and their ability to reach between teeth (standard effect 3).

[0047] Provision (2) is a provision for area E, but area E may include the entire hair implantation area of ​​head portion 4.

[0048] Furthermore, according to provision (3), the condition that the sum of the areas of the holes 6 in the non-opposing hair bundles 22 is less than or equal to the sum of the areas of the holes 6 in the opposing hair bundles 21 is met. As a result, the non-opposing hair bundles 22 within region E occupy an area that does not disrupt harmony, and the "unharmonious bending region" in the outermost region of the head part 4 outside region E can also be limited to an area that allows the harmony within region E to be felt.

[0049] Furthermore, among the soft group 11, opposing bristle bundles 21, and non-opposing bristle bundles 22, a line segment extending in the width direction starting from the furthest forward position in the head portion 4 (defined by the hole edge in the rigid bristle bundle 20) is defined as line segment a, and a line segment extending in the width direction starting from the furthest rear end position in the head portion 4 (defined by the hole edge in the rigid bristle bundle 20) is defined as line segment b. Similarly, among the soft group 11, opposing bristle bundles 21, and non-opposing bristle bundles 22, a line segment extending in the long axis direction starting from the furthest width direction (+X side) in the head portion 4 is defined as line segment c, and a line segment extending in the long axis direction starting from the furthest width direction (-X side) in the head portion 4 is defined as line segment d. The line segment c shown in Figure 2 is a line segment extending in the long axis direction at the furthest +X side position of the two soft groups 11. Line segment d is the line segment that extends in the direction of the major axis at the position furthest to the -X side of the two soft groups 11.

[0050] The line segment c shown in Figure 2 lies collinear with the line segment C. Similarly, the line segment d lies collinear with the line segment D. The line segment a shown in Figure 2 is located closer to the front end than the line segment A. The line segment b is located closer to the rear end than the line segment B. Region e (shown by a dashed line in Figure 2) is a rectangular area enclosed by line segments a, b, c, and d. Region e has a larger area than region E.

[0051] The area of ​​region E described above is preferably 60% or more of the area of ​​region e, more preferably 70% or more, and even more preferably 80% or more. If the area of ​​region E is less than 60% of the area of ​​region e, a large area will exist that is composed solely of rigid bristle bundles 20. As a result, the aforementioned effects of eliminating the feeling of a foreign object (Effect 1), making the discomfort less noticeable (Effect 2), and improving the resilience of the bristle tips and their ability to reach between teeth (Effect 3) will be weakened. By making the area of ​​region E 60% or more of the area of ​​region e, the above specified effects 1-3 become easier to obtain.

[0052] If F is the total area of ​​the base end of the soft group 11 within region E (or each region of the base if there is a base), and J is the total area of ​​the holes 6 of the rigid hair bundle 20 within region E, then it is preferable that the relationship F > J is satisfied, more preferably that F > (1.1 × J) is satisfied, and even more preferably that F > (1.2 × J) is satisfied. The above-mentioned base applies to both configurations where the base is flush with the flocked surface 5 and configurations where the base is provided at a step from the flocked surface 5. When calculating the total area F, the base area is calculated using the area of ​​the base at the base end of the soft group 11, even when the base is provided at a step from the flocked surface 5. When the total area satisfies the relationship F ≤ J, the deflection of the rigid hair bundle 20 becomes dominant, and the effect of interaction with the soft group 11 is weakened. By satisfying the relationship F > J in total area, the above-mentioned specified effects 1-3 due to the interaction between the rigid hair bundle 20 and the soft hair group 11 become easier to obtain.

[0053] Furthermore, considering the actual use in which the rigid hair bundles 20 and soft hairs 10 interact within region E, the number of rigid hair bundles 20 is important, so the total area of ​​the holes 6 is used. On the other hand, while rigid hair bundles 20 are recognized as individual bundles, in the case of soft hairs 10, they are not recognized individually, and the number of soft hair groups 11 is important. Since they are recognized as a somewhat cohesive group, the total area of ​​the base portion surrounding the base end of the soft hair group 11 (the region enclosed by the dashed line in Figure 2) is used.

[0054] When two or more soft groups 11 are arranged in a manner that they are not adjacent in the longitudinal direction, and a rigid hair bundle 20 containing at least one opposing hair bundle 21 is placed between each of them, let H be the total area of ​​the holes 6 of the rigid hair bundle 20 that overlaps with the soft groups 11 in the longitudinal direction, among the rigid hair bundle 20 that is placed in the region sandwiched between the two soft groups 11 in the longitudinal direction. If G is the total area of ​​the two soft groups 11 that sandwich the rigid hair bundle 20 in the longitudinal direction, it is preferable that the relationship G > H is satisfied, and it is more preferable that the relationship G > H > (0.5 × G) is satisfied. When the total area satisfies the relationship G ≤ H, the deflection of the rigid hair bundle 20 becomes dominant, and the effect due to interaction with the soft group 11 is weakened. When the total area satisfies the relationship G > H, the above-mentioned specified effects 1-3 due to the interaction between the rigid hair bundle 20 and the soft group 11 are more easily obtained. Since the rigid bristle bundles 20 and the soft bristle group 11 tend to bend preferentially in the brushing direction (especially in the longitudinal direction), the main effect can be enhanced when the rigid bristle bundles and soft resin bristles are continuous in the longitudinal direction. Therefore, the effect may be weakened if there is only one soft bristle group in the longitudinal direction.

[0055] Furthermore, if the width dimensions of the two soft groups 11 that sandwich the rigid bristle bundle 20 in the longitudinal direction are different, the hole 6 of the rigid bristle bundle 20 that overlaps with the soft group 11 in the longitudinal direction is defined as the soft group 11 with the larger width dimension and the rigid bristle bundle 20 that overlaps with the soft group 11 in the longitudinal direction.

[0056] The soft group 11 has a flat outer shape extending in the width direction and is arranged in multiples along the long axis direction. Preferably, the spaces between the multiple soft groups 11 arranged along the long axis direction are separated by at least opposing bundles of hair 21 aligned in the width direction. For the flattened portion extending in the width direction, it is preferable that the width dimension of the soft group 11 is 60% or more of the maximum width dimension of the head portion 4, more preferably 70% or more, and even more preferably 80% or more.

[0057] The group of soft materials 11 with a flattened outer shape extending in the width direction is not limited to those in which the front and rear ends of the outer shape lie on the same straight line extending in the width direction. For example, it may be a configuration in which multiple straight lines extending in the width direction are arranged in an uneven shape with sequentially different positions in the width direction and longitudinal axis direction (see Figure 5 described later), or a configuration in which two line segments of different lengths in the width direction located at the front and rear ends of the outer shape are arranged in a trapezoidal shape by two line segments connecting the ends of the two line segments (see Figure 7 described later), or a configuration in which two line segments of the width direction are located at the front and rear ends of the outer shape and have the same length but different positions in the width direction, and two line segments connecting the ends of the two line segments are arranged in a parallelogram shape.

[0058] If the outer shape of the soft bristle group 11 is flat and elongated in the direction of the long axis of the head, the brushing direction tends to be along the long axis, which can make the brushing surface unstable and potentially weaken the above-mentioned specified effect 1. Also, if the rigid bristle bundle 20 is located at the same position as the soft bristle group 11 along the long axis, the bending characteristics of the rigid bristle bundle 20 become more pronounced, which may weaken the above-mentioned effect. By making the outer shape of the soft group 11 flat and extending in the width direction, the above-mentioned specified effect 1 is more easily obtained. Furthermore, by making the width dimension of the soft group 11 60% or more of the maximum width dimension of the head portion 4, the above-mentioned specified effect 1 can be maintained. Furthermore, from the viewpoint of the above-mentioned specified effect 3, the aspect ratio (dimension in the width direction:dimension in the long axis direction) of the soft group 11 is preferably 2:1 or greater, and more preferably 3:1 or greater.

[0059] Figure 5 shows an example of arrangement of rigid bristles and soft bristles based on the longitudinal dimension of the outer region of the soft bristles 11 and the diameter of the base end of the opposing bristles 21. As shown in Figure 5, the soft group 11 has a flattened outer shape that extends in the width direction. Two soft groups 11 are arranged separately in the longitudinal direction. Figure 6 is an enlarged partial view of the soft group 11 located at the tip side in Figure 5.

[0060] As shown in Figure 6, the outer region 12 forming the outer casing of the soft group 11 has a first portion 12A and a second portion 12B. The first portion 12A is located on the rear end side of the outer region 12 and is formed with a length that defines the positions of both ends in the width direction of region E. The second portion 12B is located on the front end side of the outer region 12 and is positioned in the center in the width direction with a shorter length than the first portion 12A. In other words, the outer region 12 having the first portion 12A and the second portion 12B is formed in a convex shape.

[0061] If the outer contour region 12 is formed only by the first part 12A, the leading-side line segment in the outer contour region 12 with the highest occupancy ratio with respect to the width of the head part 4 is the leading-side line segment K of the first part 12A. Also, the trailing-side line segment in the outer contour region 12 with the highest occupancy ratio with respect to the width of the head part 4 is the trailing-side line segment L of the first part 12A.

[0062] On the other hand, when the outer contour region 12 has the first part 12A and the second part 12B, the leading-side line segment in the outer contour region 12 is the line segment K1 formed by combining the line segments of lengths b and c in the first part 12A and the line segment K2 of length a in the second part 12B. In this case, the line segment K is set by comparing the occupancy ratios of the line segment K1 of lengths b and c with the same position in the major axis direction and the line segment K2 of length a with different positions in the major axis direction with respect to the width of the head part 4. Specifically, when (b + c) > a and the occupancy ratio of the line segment K1 is high, the line segment K1 is taken as the line segment K. When (b + c) < a and the occupancy ratio of the line segment K2 is high, the line segment K2 is taken as the line segment K. Note that the soft bristles 10 of the second part 12B also bend in the direction toward the leading side in the width direction of the head part 4 and in the diagonal direction intersecting both the width direction and the major axis direction. Since this is larger than the influence when the soft bristles 10 of the first part 12A bend respectively, when (b + c) = a, the line segment K2 is taken as the line segment K.

[0063] The distance in the major axis direction between the line segment K and the line segment L is preferably 1 time or more and less than 4 times the diameter of the base end of the opposing bristle bundle 21 that faces the line segment K and the line segment L of the outer contour region 12 adjacent to each other. When the diameters of the base ends of the plurality of opposing bristle bundles 21 are not the same, the diameter of the opposing bristle bundle 21 is taken as the average value. When the distance in the major axis direction between the line segment K and the line segment L is 4 times or more the diameter of the base end of the opposing bristle bundle 21, the bending of the soft bristles 10 becomes dominant, and there is a possibility that the above-described defined effects 1 - 3 are weakened. By setting the distance in the major axis direction between the line segment K and the line segment L to be 1 time or more and less than 4 times the diameter of the base end of the opposing bristle bundle 21, the above-described defined effects 1 - 3 are likely to be obtained.

[0064] FIG. 7 is a partially enlarged view showing a modified example of the outer contour region 12 of the soft group 11. As shown in Figure 7, the outer region 12 may be configured in a trapezoidal shape by two line segments K and L, which are located at the front and rear ends of the outer shape and have different lengths in the width direction, and two line segments that connect the ends of these two line segments. Even if the outer region 12 has such a trapezoidal shape, the above-mentioned specified effects 1-3 can be more easily obtained by setting the distance along the long axis of line segment K and line segment L to be at least 1 and less than 4 times the diameter of the base end of the opposing hair bundle 21 adjacent to and facing line segment K and line segment L of the outer region 12.

[0065] The proportion of the total area where the soft hair group 11 exists in region e of the bristled surface 5 is preferably 50% or less. The proportion of the total area where the soft hair group 11 exists in region E is preferably 50% or less. The total area where the soft hair group 11 exists is 150 mm². 2 The following is preferable: The area of ​​each of the soft group 11 is 10 mm². 2 It is preferable that the above conditions are met.

[0066] The number of rows in the soft hair group 11 is preferably 2 to 5 columns. The number of rows in the soft hair 10 is preferably 4 to 15 rows.

[0067] As explained above, in the toothbrush 1 of this embodiment, the soft bristles 10 and rigid bristle bundles 20 are arranged according to a specification based on the texture resulting from the interaction between the adjacent soft bristles 10 and rigid bristle bundles 20 during brushing. Therefore, the textures of the soft bristles 10 and rigid bristle bundles 20, which have significantly different physical properties, are harmonized, making it possible to brush without any discomfort.

[0068] [Examples] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples and can be implemented with appropriate modifications without departing from its essence.

[0069] (Examples 1-13, Comparative Examples 1-9) Samples for Examples 1-13 and Comparative Examples 1-9 were prepared according to the specifications shown in Table 1-5.

[0070] The sample in Example 1 has the same configuration as described using Figure 3, and the area of ​​region E and the area of ​​region e are the same, making it a sample that is less likely to cause any sense of incongruity. The sample of Example 2 has the same configuration as described using Figure 2, and since there are no non-opposing hair bundles in region E, it is less likely to cause discomfort. However, because region E is small and non-opposing hair bundles are concentrated in the tip and rear end regions, this sample is more likely to cause discomfort. The sample in Example 3 does not have non-opposing hair bundles within region E, making it less likely to cause discomfort. However, because region E is small, there is only one soft hair bundle, and non-opposing hair bundles are concentrated in the left and right regions, this sample is more likely to cause discomfort. The sample in Example 4 has non-opposing hair bundles within region E, but because they are located on the outermost edge, it is a sample that is less likely to cause discomfort. The sample in Example 5 has non-opposing hair bundles within region E, but because they are sandwiched between opposing hair bundles, it is a sample that is less likely to cause discomfort. The sample in Example 6 has non-opposing hair bundles within region E, but because they are positioned on the outermost edge, they are less likely to cause discomfort. Furthermore, even if the soft group is convex, the outermost hair bundles easily harmonize with the surroundings, resulting in a harmonious curvature. The sample in Example 7 has non-opposing hair bundles within region E, but because they are sandwiched between opposing hair bundles, it is less likely to cause discomfort. Furthermore, even if the soft group is concave, the sandwiched hair bundles tend to harmonize with the surroundings, resulting in a harmonious flex. The sample in Example 8 is a compact head that does not have any non-opposing hair bundles within region E, has multiple soft hair bundles, and region E is sufficiently large, making it a sample that is less likely to cause discomfort. The sample in Example 9, while having non-opposing hair bundles within region E in a compact head, is positioned on the outermost edge, making it less likely to cause discomfort. By deliberately positioning it this way, the harmonious flexion is prevented from escaping outwards, further enhancing the overall harmony. The sample in Example 10, despite having a compact head and a convex shape for the soft hair bundles, does not contain any non-opposing hair bundles within region E, has multiple soft hair bundles, and region E is sufficiently large, making it a sample that is less likely to cause discomfort. The sample in Example 11 is an ultra-compact head that does not have any non-opposing hair bundles within region E, has multiple soft hair bundles, and region E is sufficiently large, making it a sample that is less likely to cause discomfort. The sample in Example 12 is an ultra-compact head with non-opposing hair bundles within region E, but because they are positioned on the outermost edge, it is a sample that does not easily cause discomfort. By deliberately positioning them this way, the harmonious flexion does not escape outwards, resulting in a sample that further enhances harmony. The sample in Example 13, despite having an ultra-compact head and a convex shape for the soft hair group, does not have any non-opposing hair bundles, has multiple soft hair groups, and the areas of region E and region e are the same, making it a sample that is less likely to cause discomfort. The samples in Examples 1, 2, 3, 8, 10, 11, and 13 are formed with patterns that satisfy only the requirement (2-1). Example 7 is formed with a pattern that satisfies only the requirement (2-2). Example 6 is formed with a pattern that satisfies only the requirements (2-3). Examples 4, 5, 9, and 12 are formed with patterns that satisfy the requirements (2-2) and (2-3).

[0071] The sample in Comparative Example 1 has non-opposing hair bundles within region E and is not sandwiched between opposing hair bundles, making it a sample that is prone to causing discomfort. The sample in Comparative Example 2 does not have non-opposing hair bundles within region E, but because region E is small and there is only one soft group, and non-opposing hair bundles are concentrated in the tip and posterior regions, the number of non-opposing hair bundles is large, making it a sample that is likely to cause discomfort. The samples in Comparative Examples 3-6 and Comparative Example 8 have non-opposing hair bundles within region E and are not sandwiched between opposing hair bundles, making them samples that are prone to causing discomfort. The sample in Comparative Example 7 does not have non-opposing hair bundles within region E, but because region E is small and there is only one soft group, and non-opposing hair bundles are concentrated in the tip and posterior regions, the number of non-opposing hair bundles is large, making it a sample that is likely to cause discomfort. The sample in Comparative Example 9 has a small region E and only one soft group. Because non-opposing hair bundles are concentrated in the tip and posterior regions, the number of non-opposing hair bundles is large, making it a sample that is likely to cause discomfort.

[0072] In the arrangement specifications shown in Table 1-5, opposing bristles of rigid bristles that satisfy specification (2) are shown as white circles, and opposing bristles that do not satisfy specification (2) are shown as hatched circles. Non-opposing bristles of rigid bristles are shown as black circles. In addition, region E is shown as an enclosed area with a solid line. Three types of heads were used: a wide head, a compact head, and an ultra-compact head.

[0073] Each sample followed the following common specifications. Maximum thickness of the head: 3.0 mm. The rigid resin that makes up the head: polypropylene resin (PP). Soft bristles, length: 10mm. Base shape of soft bristles: triangular. Base cross-sectional area of ​​soft hair: 0.3mm 2 . Side view shape of soft bristles: Tapered shape, becoming narrower from the base to the tip. Density of soft hairs in the soft hair group: 1 hair / mm 2 . The soft resin that makes up the soft bristles is polyurethane resin (PU). Hardness of the soft resin: Shore A hardness 98. Method for manufacturing soft bristles: Insert molding. Rigid bristle bundle length: 10mm. Base shape of a single hair constituting a rigid hair bundle: circular. Cross-sectional area of ​​the base of a single hair constituting a rigid hair bundle: 0.025 mm² 2 . Side view shape of a single hair constituting a rigid hair bundle: tapered shape, becoming thinner from the base to the tip. Hole diameter into which the rigid bristle bundles are implanted: 1.5 mm. The flexible resin constituting the rigid bristle bundle is polybutylene terephthalate (PBT).

[0074] [evaluation] We evaluated the "feel of being able to brush without any discomfort from using both soft bristles and stiff bristles." The evaluation involved a sensory assessment by 10 expert panelists, who assessed how smoothly the soft bristles and stiff bristles could be used for brushing, based on the following criteria. 5 points: Very much so. 4 points: Slightly noticeable 3 points: Neither agree nor disagree 2 points: I barely feel it. 1 point: I don't feel it at all. Then, the average of the evaluation scores from the 10 expert panelists was calculated, and the following five-point scale was used for evaluation. A score of ☆, ◎, or ○ was considered a pass (OK), while a score of △ or × was considered a fail (NG). ☆(star mark): 4.5 points or more, 5.0 points or less. ◎ (double circle mark): 4.0 points or higher, but less than 4.5 points. ○ (circle mark): 3.5 points or higher, but less than 4.0 points. △ (triangle mark): 3.0 points or higher, but less than 3.5 points. × (cross mark): Less than 3.0 points.

[0075] [Table 1]

[0076] [Table 2]

[0077] [Table 3]

[0078] [Table 4]

[0079] [Table 5]

[0080] As shown in Table 1-5, the samples from Examples 1-13, which satisfy all of the criteria (1)-(3) based on the texture resulting from the interaction of adjacent soft bristles and rigid bristle bundles during brushing, all received good evaluations for "the feeling that both soft bristles and rigid bristle bundles can be used to brush without discomfort." In particular, the samples from Example 1 and Example 13, which do not have non-opposing bristle bundles, received the highest evaluation results, confirming the effectiveness of having all rigid bristle bundles adjacent to and opposing the soft bristles.

[0081] Furthermore, compared to the sample of Example 3, which had one soft component, the samples of Examples 1-2 and 4-13, which had multiple soft components, received better evaluations. Furthermore, in Examples 1 and 4-13, where the area of ​​region E was 60% or more of the area of ​​region e, it was confirmed that all samples received a high rating of 4.0 or higher.

[0082] On the other hand, comparative examples 1 and 3-6, which did not satisfy provision (2) among provisions (1)-(3), and comparative examples 2 and 7-9, which did not satisfy provision (3), did not receive favorable evaluations.

[0083] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. The shapes and combinations of the constituent members shown in the above examples are merely examples, and can be modified in various ways based on design requirements, etc., without departing from the spirit of the present invention. [Explanation of Symbols]

[0084] 1...Toothbrush, 4...Head, 5...Bristle surface, 6...Hole (Bristle hole), 10...Soft bristles, 11...Soft bristle group, 12...Outer area, 20...Rigid bristle bundle, 21...Opposite bristle bundle, 22...Non-opposite bristle bundle

Claims

1. Soft bristles formed in a filament shape from soft resin, A bundle of stiff hairs having greater rigidity than the aforementioned soft hairs, The head portion is arranged such that the soft bristles and the rigid bristle bundles are arranged on the front side in the thickness direction, in a plane direction perpendicular to the thickness direction, Equipped with, The head portion has at least one group of soft bristles arranged in a continuous manner in the longitudinal axis direction or in the width direction perpendicular to the longitudinal axis direction, A toothbrush in which the soft bristles and rigid bristles are arranged according to a specification based on the texture resulting from the interaction between the soft bristles and rigid bristles during brushing, arranged in adjacent combinations.

2. The rigid hair bundles adjacent to and facing the soft hair bundles are designated as opposing hair bundles, and the rigid hair bundles that are not adjacent to each other are designated as non-opposing hair bundles. Among the soft group and the opposing bundle of hairs, the line segment extending in the width direction starting from the position closest to the tip in the longitudinal direction on the head portion is defined as line segment A. Among the soft group and the opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the rear end in the longitudinal axis direction on the head portion is defined as line segment B. Among the soft group and the opposing bundle of hair, the line segment C is defined as the line segment extending in the longitudinal direction starting from the position on the farthest side in the width direction in the head portion. Among the soft group and the opposing bundle of hair, the line segment D is defined as the line segment extending in the longitudinal direction starting from the position furthest to the other side in the width direction on the head portion. When the region enclosed by line segment A, line segment B, line segment C, and line segment D is defined as region E, In the region E, at least one of the following conditions is met: the non-opposing hair bundle is not provided; the non-opposing hair bundle is sandwiched between the opposing hair bundle in at least one direction of the longitudinal axis and the width direction; and the non-opposing hair bundle is positioned at the outermost edge while facing the opposing hair bundle in at least one direction of the longitudinal axis and the width direction. The sum of the areas of the holes in the non-opposing hair bundles in the head portion is less than or equal to the sum of the areas of the holes in the opposing hair bundles. The toothbrush according to claim 1.

3. The aforementioned soft group is provided in two or more configurations, where they are not adjacent to each other. The toothbrush according to claim 2.

4. Between each of the soft groups arranged in a manner that is not adjacent in the longitudinal direction, at least one rigid bundle, including the opposing bundle, is arranged. Of the rigid hair bundles arranged in the region sandwiched between the two soft groups in the longitudinal direction, let H be the total area of ​​the holes in the rigid hair bundles that overlap with the soft groups in the longitudinal direction. If G is the total area of ​​the two soft groups that sandwich the rigid hair bundle in the longitudinal direction, G > H Satisfying the relationship, The toothbrush according to claim 3.

5. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the tip in the longitudinal direction on the head portion is defined as line segment a. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment extending in the width direction starting from the position closest to the rear end in the longitudinal axis direction on the head portion is defined as line segment b. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment c is defined as the line segment extending in the longitudinal direction starting from the position on the far side in the width direction of the head portion. Among the soft group, the opposing bundle of hair, and the non-opposing bundle of hair, the line segment d is defined as the line segment extending in the longitudinal direction starting from the position furthest to the other side in the width direction on the head portion. When the region enclosed by line segment a, line segment b, line segment c, and line segment d is defined as region e, The area of ​​region E is 60% or more of the area of ​​region e. The toothbrush according to any one of claims 2 to 4.

6. Let F be the total area of ​​the base portion surrounding the base end in the soft group of region E. If J is the total area of ​​the holes in the rigid hair bundle in the region E, F>J Satisfying the relationship, The toothbrush according to any one of claims 2 to 4.

7. The outer shape of the soft group is flattened and extends in the width direction, and multiple units are arranged in the longitudinal direction. The spaces between the multiple soft groups arranged in the longitudinal direction are separated at least by the opposing bundles of hair arranged in the width direction. The toothbrush according to any one of claims 2 to 4.

8. The outer region forming the outer shell has the soft group extending in the width direction, The distance in the longitudinal direction between the line segment K at the tip end and the line segment L at the rear end in the outer region that occupies the greatest degree relative to the width of the head portion is 1 or more and less than 4 times the diameter of the base end of the opposing bristle bundle adjacent to and facing the soft group having the outer region. The toothbrush according to any one of claims 2 to 4.

9. In the region E, the non-opposing hair bundles are not arranged. The toothbrush according to any one of claims 2 to 4.

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