JP7190872B2 - toothbrush - Google Patents

Description

The present invention relates to toothbrushes.

For example, to prevent caries and periodontal disease, it is important to remove plaque from the oral cavity by brushing with a toothbrush. In addition, in order to enhance the effect of removing plaque, the toothbrush has a thin head portion and a thin neck portion. As a result, the bristles can reach the back of the back teeth (the throat side of the back teeth), which is difficult to reach with a normal toothbrush.

By the way, by constructing the head part from a high-strength resin such as polyacetal resin or polybutylene terephthalate resin, even if the head part is thin and the neck part is also thin, sufficient flocking strength of the head part and the neck part can be obtained. A toothbrush that can obtain a folding endurance of 100 kg (see Patent Documents 1 and 2, for example) has been proposed. In addition, since the brush body is made of high-strength resin, when the brush body is viewed from both the front view (perpendicular to the flocked surface) and the side view (parallel to the flocked surface) In addition, it is possible to form a straight shape from the tip of the head portion to the rear end of the handle portion.

On the other hand, in the case of a toothbrush made of polypropylene resin, which has a lower strength than the above resins, if the head part is thin and the neck part is also thin, the neck part will bend during toothbrushing, and the flocked part will not be as strong as the head part. It will be displaced to the back side (that is, away from the teeth and gums). As a result, there is a problem that the force applied to the handle portion is less likely to be transmitted to the flocked portion, and the operability of the handle portion is deteriorated.

For this reason, a toothbrush has been proposed in which the deflection of the neck portion is offset between the head portion and the neck portion (part of the brush body) by forming the brush body into a curved shape (S-shape) when viewed from the side. (See Patent Document 3, for example).

By the way, in recent years, for users who have difficulty gripping thin handles due to reasons such as weak grip strength, toothbrushes with thick handles have been developed so that they can be easily gripped with the entire palm and can be palm gripped with light force. It has been proposed (see Patent Document 4, for example). Such a toothbrush has a straight shape from the front end of the head portion to the rear end of the handle portion when viewed from the side, so that the head portion can be operated accurately when brushing teeth (see, for example, Patent Document 4).

However, in such a toothbrush, in order to improve the operability in the oral cavity, if the head part is simply thinned and the neck part is thinned while maintaining the thick straight shape of the handle part, the handle part and the neck part will be thin. The difference in stiffness becomes large, and the stress during use tends to concentrate in the boundary area between the handle and the neck. As a result, the neck portion bends too much and is displaced toward the back side (away from the teeth and gums), making it difficult for the force applied to the handle portion to be transmitted to the flocked portion, resulting in reduced operability in the oral cavity. I had a problem.

In particular, when gripping a thick handle, the gap between the handle and the palm is reduced, so the handle can be gripped with the entire palm (that is, the handle is shaped so that it can be gripped with a palm grip with a light force. Therefore, when the handle portion is thin, it is easier to apply a load to the head portion when brushing the teeth, and the problem of stress concentration described above becomes more pronounced. That is, such a problem is peculiar to a toothbrush that achieves both operability in the oral cavity with a thin head portion and a thin neck portion and a thick straight handle portion that is excellent in grip.

Japanese Patent Application Laid-Open No. 2011-4852 JP 2013-118944 A WO2017/155039 Japanese Unexamined Patent Application Publication No. 2006-202

The present invention has been proposed in view of such conventional circumstances. To provide a toothbrush having both excellent gripability of a handle part and good operability in the oral cavity.

In order to achieve the above object, the present invention provides the following means.
That is, the invention according to claim 1 comprises a brush body including a handle, a neck extending from the tip of the handle, and a head provided at the tip of the neck. A toothbrush having a plurality of tufts of bristles implanted on a bristle-implanted surface, wherein the brush body has a shape in which the thickness of the neck portion increases continuously from the head portion toward the handle portion, and The thickness D1 of the head portion is 2 to 4 mm, the minimum thickness D2 of the neck portion is 3 to 4.5 mm, the maximum thickness D3 of the handle portion is 13 to 16 mm, and the maximum thickness The ratio represented by D3/the thickness D1 is 3.5 to 7, and the ratio represented by the maximum thickness D3/the minimum thickness D2 is 3 to 5. a first substantially linear region S1 continuous with the flocked surface; and a center of curvature from the first substantially linear region S1 to the flocked surface side of the brush body via a first inflection point P1, and the minimum thickness A first curved region E1 thicker than D2, a second curved region E2 having a center of curvature on the back side of the brush body from the first curved region E1 via a second inflection point P2, When the brush body is viewed from the front, the width of the brush body spreads from the neck portion to the handle portion, and the position where the width starts to spread from the minimum width W2 of the neck portion is the neck and the first inflection point P1 is positioned closer to the head than the position where the minimum width W2 begins to widen .

Further, the invention according to claim 2 is the toothbrush according to claim 1 , wherein the radius of curvature R1 of the first curved region E1 is smaller than the radius of curvature R2 of the second curved region E2. be.

Further, the invention according to claim 3 is characterized in that the distance between the first inflection point P1 and the second inflection point P2 is 10 to 45 mm. A toothbrush as described.

Further, the invention according to claim 4 is characterized in that the distance between the second inflection point P2 and the position of the maximum thickness D3 is 45 to 65 mm. or a toothbrush according to item 1.

Further, the invention according to claim 5 is characterized in that the distance between the boundary O between the head portion and the neck portion and the position of the maximum thickness D3 is 70 to 110 mm. 5. The toothbrush according to any one of 4 .

Further, the invention according to claim 6 is characterized in that, when the brush body is viewed from the side, a second substantially linear region S2 continuous to the back surface of the head portion and a third linear region S2 extending from the second substantially linear region S2 are provided. A toothbrush according to any one of claims 1 to 5, characterized in that it has a third curved region E3 that curves through a point of inflection P3.

Further, the invention according to claim 7 is the toothbrush according to claim 6 , wherein the third inflection point P3 is located closer to the handle portion than the first inflection point P1. be.

Further, the invention according to claim 8 is characterized in that the curvature radius R3 of the third curved region E3 is larger than the curvature radius R1 of the first curved region E1. is a toothbrush.

Further, the invention according to claim 9 is the toothbrush according to any one of claims 6 to 8 , characterized in that the third curved region E3 has a center of curvature on the bristle-implanted surface side of the brush body. is.

Further, the invention according to claim 10 is characterized in that, when the brush body is viewed from the side, the extension line of the flocked surface is located at a position overlapping the brush body over the entire length of the handle portion. 10. The toothbrush according to any one of 1 to 9 .

Further, the invention according to claim 11 is the toothbrush according to any one of claims 1 to 10 , wherein the bending elastic modulus of the resin constituting the brush body is 1000 MPa or more and 2800 MPa or less. be.

Further, the invention according to claim 12 is the toothbrush according to any one of claims 1 to 11 , wherein the resin constituting the brush body is a polypropylene resin.

Further, the invention according to claim 13 is characterized in that it has a coating material for coating the surface of the handle portion, and the coating material is made of a resin softer than the resin constituting the brush body. 13. The toothbrush according to any one of 1 to 12 .

Further, the invention according to claim 14 is the toothbrush according to claim 13 , wherein the covering material is made of an elastomer resin or a silicone resin.

As described above, according to the present invention, even when the head portion is thinned and the neck portion is thinned, the bending of the neck portion can be suppressed by the entire brush body, and the handle portion is excellent in grip and good. It is possible to provide a toothbrush that achieves both excellent intraoral operability.

It is a side view showing composition of a toothbrush concerning an embodiment of the present invention. It is the front view which looked at the toothbrush shown in FIG. 1 from the hair-planting surface side. FIG. 2 is a cross-sectional view of the toothbrush along line segment AA shown in FIG. 1; FIG. 2 is a cross-sectional view of the toothbrush along line segment BB shown in FIG. 1; FIG. 2 is a cross-sectional view of the toothbrush along line segment CC shown in FIG. 1;

Hereinafter, a toothbrush to which the present invention is applied will be described in detail with reference to the drawings.
In addition, the drawings used in the following explanation may schematically show the characteristic parts for convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as the actual ones. Make it not exist. In some cases, illustration of hair tufts is omitted, and only tufting holes in which the tufts of hair are tufted are shown.

In the following description, the side of the head portion 5 on which the flocked surface 5a is provided is the front side of the toothbrush 1, and the side opposite to the flocked surface 5a of the head portion 5 is the back side of the toothbrush 1. do. In addition, the direction parallel to the flocked surface 5a and perpendicular to the length direction of the brush body 2 is defined as the width direction of the toothbrush 1, and the direction perpendicular to the flocked surface 5a is defined as the thickness direction (side surface side) of the toothbrush 1.

First, as one embodiment of the present invention, for example, a toothbrush 1 shown in FIGS. 1 to 5 will be described.
In addition, FIG. 1 is a side view which shows the structure of the toothbrush 1. As shown in FIG.
FIG. 2 is a front view of the toothbrush 1 viewed from the flocked surface 5a side.
FIG. 3 is a cross-sectional view of toothbrush 1 taken along line AA shown in FIG.
FIG. 4 is a cross-sectional view of the toothbrush 1 taken along line BB shown in FIG.
FIG. 5 is a cross-sectional view of the toothbrush 1 along line segment CC shown in FIG.

A toothbrush 1 of this embodiment includes a brush body 2 made of a resin molded body formed in an elongated shape as a whole.

The brush body 2 has a handle portion 3 , a neck portion 4 extending from the tip of the handle portion 3 , and a head portion 5 provided at the tip of the neck portion 4 . In the toothbrush 1, it is possible to clean the inside of the oral cavity with a plurality of tufts (not shown) planted on the bristle-implanted surface 5a of the head portion 5. As shown in FIG.

It is preferable to use, for example, polypropylene (PP) resin, polyacetal (POM) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, etc., as the resin constituting the brush body 2 . Among them, it is preferable to use a PP resin having a good balance between stress dispersibility and strength in the present invention.

The bending elastic modulus (JIS K 7171) of the resin forming the brush body 2 is preferably 1000 to 2800 MPa, more preferably 1200 to 2500 MPa, even more preferably 1500 to 2000 MPa.

(head part)
The head part 5 is a part for cleaning the oral cavity with a plurality of tufts of hair, and has a substantially rectangular parallelepiped shape with rounded corners. In addition, the flocked surface 5a of the head portion 5 and the rear surface on the opposite side form flat surfaces with each other.

The head portion 5 has a substantially quadrilateral plate-like shape in which four apexes are corner-cut with curved lines in a plan view. In the present embodiment, the boundary O between the head portion 5 and the neck portion 4 is the end point of the curve forming the corner cut from the neck portion 4 in the plan view shape of the head portion 5, that is, the end point of the curve forming the corner cut. This is the position where the bending direction changes. Therefore, the boundary O between the head portion 5 and the neck portion 4 changes from a curve or straight line forming both edges in which the width of the corner cut portion of the head portion 5 from the neck portion 4 in plan view becomes narrower to a curve in which the width widens. Alternatively, it is a straight line, or a position where the width changes to the same straight line.

The shape and size of the head portion 5 are not particularly limited as long as they are easy to clean the oral cavity. It is good also as a shape. Moreover, the head portion 5 may have a tapered shape in which the thickness is gradually reduced from the base end side to the tip end side, or may have a rounded shape in which the central portion of the back side of the head portion 5 rises. good.

A plurality of tufting holes 6 having the same diameter are arranged in a grid pattern on the tufting surface 5a of the head portion 5 . Each tufting hole 6 is formed by bundling a plurality of brushes (filaments) and folding them in two, inserting a metal stopper (not shown) called a flat wire between them, and driving it into each tufting hole 6. is planted in In addition, in FIG. 2, illustration of the tuft is omitted and only the tufting hole 6 is shown.

It should be noted that the tufting holes 6 are not limited to being arranged in a grid pattern, but may be arranged in a zigzag pattern. In addition, since the inner diameter of the flocking hole 6 is correlated with the number of hair bundles to be flocked, it affects the hardness of the hair bundles and the feeling of use. A range of 1.0 to 3.0 mm is generally preferred, although some adjustment is possible.

Although the material of the bristles is not particularly limited, for example, polyamide (eg, 6-12 nylon, 6-10 nylon), polyester (eg, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate), polyolefin ( Examples include synthetic resin materials such as polypropylene) and elastomers (eg, olefin-based, styrene-based). Also, a plurality of these resin materials may be used in combination, and different resin materials may be used for the core and the sheath, such as a core-sheath structure.

The cross-sectional shape of the bristles is usually circular, but is not limited to such shapes, for example oval, triangular, square, hexagonal, star-shaped, three-leaf clover, four-leaf clover. It can be of any shape, such as a clover shape.

The hair length of the hair bundle is preferably 8 mm to 13 mm for adults and 6 mm to 9 mm for children from the flocking surface 5a of the head portion 5. The thickness (maximum diameter) of the brush is preferably 0.12 mm to 0.26 mm from the viewpoint of usability and feeling in the oral cavity. In addition, a plurality of brushes having different thicknesses may be used in arbitrary combinations in consideration of usability, cleaning feeling, cleaning effect, durability, and the like.

As a method of flocking hair tufts, in addition to the above-described flat line flocking method in which the hair tufts of the brush are folded in two and are tufted in the tufting holes 6 with a flat line interposed therebetween, the lower ends of the tufts are connected to the head portion 5. Alternatively, the lower end of the hair bundle is heated to form a molten mass, and then the molten resin is filled into the cavity of the mold to be molded integrally with the head portion 5. An in-mold method or the like can be used.

The thickness D1 of the head portion 5 is preferably 2 to 4 mm, more preferably 2.5 to 3.5 mm. In the case of a tapered shape in which the thickness gradually decreases from the boundary O between the head portion 5 and the neck portion 4 toward the tip side of the head portion 5, the thickness D1 is defined as the average value of the thickness of the entire head portion 5. .

This makes it possible to reduce the thickness of the head portion 5, improve the operability in the oral cavity, and allow the hair bundles (brushes) to reach the back of the back teeth (the throat side of the back teeth). Moreover, the relationship between the minimum thickness D2 of the neck portion 4 and the thickness D1 of the head portion 5, which will be described later, is preferably D1≦D2 from the viewpoint of insertability into the oral cavity.

Moreover, the length of the head portion 5 is preferably 10 to 40 mm from the viewpoint of insertability into the oral cavity. If the width W1 of the head portion 5 is too large, the operability in the oral cavity will be deteriorated, and if it is too small, the number of hair bundles to be implanted will be too small and the cleaning power will be easily impaired, so it is 5 to 16 mm. is preferred.

(Neck part)
The neck portion 4 is a portion that connects the handle portion 3 and the head portion 5 . In this embodiment, the outer shape of the neck portion 4 and the handle portion 3 in front view and side view is a shape in which a plurality of substantially straight lines or gentle curves are connected from the boundary O toward the handle portion 3 side. In addition, although the boundary between the neck portion 4 and the handle portion 3 is an unclear shape, the length of the neck portion 4 in the present invention is determined from the boundary O as a base point in the front view from the viewpoint of insertability into the oral cavity. Defined as within 50 mm in three lateral directions.

When maintaining the minimum thickness D2 of the neck portion 4 at a constant length in the longitudinal direction (from the neck portion 4 to the rear end side of the handle portion 3), the area where the constant length is maintained extends from the boundary O to the handle portion 3. It preferably does not exceed 25 mm, more preferably does not exceed 20 mm, and even more preferably does not exceed 10 mm. Also, the minimum thickness D2 of the neck portion 4 is preferably 3 to 4.5 mm, more preferably 3.5 to 4.5 mm.

As a result, the thickness of the neck portion 4 can be continuously increased from the head portion 5 toward the handle portion 3 in a side view. can ensure the integrity of the In addition, since the stress concentration position applied to the neck portion 4 during tooth brushing is provided on the head portion 5 side, a sufficient distance for dispersing the stress in the direction of the handle portion 3 described later can be secured, and excessive bending of the neck portion 4 can be suppressed. can do.

When the minimum width W2 of the neck portion 4 is maintained at a constant length in the longitudinal direction (from the neck portion 4 to the rear end side of the handle portion 3), the area where this constant length is maintained is from the boundary O to the handle portion 3 side. The minimum width W2 of the neck portion 4 is preferably 3 to 4.5 mm, preferably 25 mm, more preferably 20 mm, and even more preferably 10 mm. It is more preferable that the thickness is 0.5 to 4.5 mm, whereby the lip opening does not become large when inserted into the oral cavity, and operability in the oral cavity can be ensured.

(Handle part)
The handle portion 3 is a portion that is gripped by the user and is formed in a long columnar shape. In addition, although the boundary between the neck portion 4 and the handle portion 3 described above is an unclear shape, in order to secure a sufficient length for gripping and using this handle portion 3, the boundary O in the front view is It is preferable that the length to the rear end of the handle portion 3 is 100 to 200 mm.

In this embodiment, when the brush body 2 is viewed from the side, the thickness of the handle portion 3 continuously increases from the tip side (the neck portion 4 side) toward the rear end side, reaching the maximum thickness D3. Later, it has a shape in which the thickness decreases toward the rear end side.

In the case where the handle portion 3 has a plurality of portions having the maximum thickness D3, the portion closest to the neck portion 4 is defined as the portion having the maximum thickness D3 of the handle portion 3 univocally.

A maximum thickness D3 of the handle portion 3 is preferably 13 to 16 mm, more preferably 13.5 to 15.5 mm. Also, the maximum width W3 of the handle portion 3 is preferably 13 to 16 mm, more preferably 14.5 to 16 mm. As a result, the grip of the handle portion 3 can be improved, and excellent operability can be obtained by a palm grip or the like.

Further, the toothbrush 1 of the present embodiment preferably satisfies the relationship of 3.5≦D3/D1≦7, and more preferably satisfies the relationship of 3.5≦D3/D1≦6.5. As a result, it is possible to obtain excellent operability in the oral cavity due to the thin head portion 5 while the handle portion 3 is excellent in gripping property.

The toothbrush 1 of the present embodiment preferably satisfies the relationship 3≦D3/D2≦5, and more preferably satisfies the relationship 3.5≦D3/D2≦5. As a result, even if the neck portion 4 is made thin, the neck portion 4 does not bend excessively, and both good intraoral operability and ease of gripping can be achieved.

With the toothbrush 1 of the present embodiment, even when the thin neck portion 4 and the thick handle portion 3 are combined, the neck portion 4 can be By avoiding the concentration of stress and bending the entire brush body 2 from the head portion 5 to the handle portion 3, the bending of the neck portion 4 can be suppressed.

Further, in the toothbrush 1 of the present embodiment, the thickness of the handle portion 3 is set to the thickness of the handle portion 3 in at least 70% or more of the length from the boundary O in the front view to the rear end of the handle portion 3, including the maximum thickness D3. (hereinafter referred to as aspect ratio) is preferably in the range of 0.8 to 1.2, more preferably in the range of 0.9 to 1.1. As a result, it is possible to suppress the deflection of the handle portion 3 only in the thickness direction or only in the width direction.

(shape of the front side of the brush body)
In the toothbrush 1 of the present embodiment, when the brush body 2 is viewed from the side, the front side of the brush body 2 is continuous with the flocked surface 5a of the head portion 5 from the tip side of the neck portion 4 toward the handle portion 3 side. a first substantially linear region S1, a first curved region E1 having a center of curvature on the flocked surface 5a side of the brush body 2 from the first substantially linear region S1 via the first inflection point P1, and a first curved region E1. It has a second curved region E2 having a center of curvature on the back side of the brush body 2 via a second inflection point P2 from one curved region E1.

(Shape on the back side of the brush body)
In the toothbrush 1 of the present embodiment, when the brush body 2 is viewed from the side, on the back side of the brush body 2 , a second tooth continuous to the back of the head part 5 from the tip side of the neck part 4 toward the handle part 3 side. 2, a third curved region E3 having a center of curvature on the flocked surface 5a side of the brush body 2 from the second substantially linear region S2 via a third inflection point P3, and a third curved region E3. It has a fourth curved region E4 having a center of curvature on the side of the flocked surface 5a of the brush body 2 via the fourth inflection point P4 from the curved region E3.

The term "substantially straight line" as used herein means a straight line parallel to the extension line L in the axial direction (major axis direction) along the flocked surface 5a when the brush body 2 is viewed from the side, or within 3°. Say that they are intersecting straight lines.

Further, in the toothbrush 1 of the present embodiment, the first inflection point P1 is positioned at the neck portion 4, and the second inflection point P2 is located on the rear end side. When viewed from the front of the brush body 2, the distance between the first inflection point P1 and the second inflection point P2 is preferably 10 to 45 mm, more preferably 25 to 40 mm. As a result, in a shape in which the thickness of the neck portion 4 continuously increases from the head portion 5 toward the handle portion 3 , the surface between the head portion 5 and the handle portion 3 is smoothly curved through the neck portion 4 . It can be connected continuously. Also, the neck portion 4 can be made thinner over its entire length.

In the case of a toothbrush with a thick, straight handle with a general size of the head and neck, simply move the head to reach the inner part of the back teeth and improve the operability in the oral cavity. When the neck portion is also thinned, the thicknesses of the first substantially linear region S1 and the first curved region E1 are reduced.

As a result, the stress concentration at the first inflection point P1 becomes excessive due to the load on the head portion during tooth brushing, and the stress distribution to the first curved region E1 and the second curved region E2 becomes insufficient. In addition, the thicker the handle, the easier it is for the stress concentration to remain in the neck region, so this tendency becomes more pronounced. When the neck portion bends too much and the flocked portion is displaced toward the back side of the head portion (that is, in the direction away from the teeth and gums), the force applied to the handle portion is less likely to be transmitted to the flocked portion. The operability of the handle portion is degraded.

Therefore, the inventors of the present invention have found that even when the head portion 5 is thinned and the neck portion 4 is thinned, in order to obtain excellent gripping property of the handle portion 3 and good intraoral operability, the neck portion 4 should be It has been found that it is effective to be able to disperse the stress concentration at the inflection point P1 of 1 over "the entire brush body 2". Specifically, the inventors have found that the size of the curvature radius of the curved region and the positional relationship of the inflection points are important factors in order to disperse the stress toward the handle portion 3 side.

The toothbrush 1 of this embodiment has a thin head portion 5, a thin neck portion 4, and a thick straight handle portion 3. Therefore, when a load is applied to the head portion 5 during tooth brushing, the toothbrush 1 first moves toward the first substantially straight line on the front side. Stress concentrates on the first inflection point P1 via the region S1. The first inflection point P1 is at a position opposite to the second substantially linear region S2 on the back side. Therefore, in the second substantially linear region S2, a resistance (repulsive force) acts in the front direction to disperse the stress received in the rear direction at the first inflection point P1.

The inventors of the present invention have found that the following measures (1) to (3) are effective in order to make use of this effect and disperse the stress "in the entire brush body 2".

(Measure (1): Stress distribution by head → S1 → P1 → S2 → E1)
When stress concentration in the back direction acts at the first inflection point P1, if the region facing the first inflection point P1 has a substantially linear shape (second substantially linear region S2), the second substantially linear region S2 is formed. In the straight region S2, a drag acts on the front side. Then, this drag is transmitted to the first curved region E1 on the front side facing the second substantially linear region S2.

In addition, when a first curved region E1 having a center of curvature is provided on the side of the flocked surface 5a of the brush body 2 via the first inflection point P1 on the front side, the stress in the back direction is generated at the first inflection point P1. Due to the nature of the curved shape, when concentration works, there is a property that resistance tends to act on the front side. In addition, the greater the radius of curvature of the first curved region E1, the more easily the drag is dispersed and transmitted.

In the present invention, it was found that stress can be dispersed over the entire brush body 2 by combining such properties. That is, when the stress in the back direction acts at the first inflection point P1, the drag force in the front direction by the second substantially linear region S2 is more likely to act, and is transmitted in the direction of the handle portion 3, causing the stress We found that dispersion is possible.

(Measure (2): Stress distribution by head → S1 → P1 → S2 → P3 → E3)
Although the above measure (1) is repeated, when the stress concentration in the back direction acts at the first inflection point P1, the region facing the first inflection point P1 has a substantially linear shape (a second substantially straight line In the region S2), a drag acts on the front side in the second substantially linear region S2. Further, the stress in the back direction received at the first inflection point P1 is transmitted in the direction of the handle portion 3 (the third curved region E3).

Further, when a third curved region E3 having a center of curvature is provided on the side of the flocked surface 5a of the brush body 2 via the third inflection point P3 on the back side, the stress in the back direction is applied to the third inflection point P3. is transmitted, resistance tends to act on the front side in the third curved region E3 due to the nature of the curved shape. In addition, the greater the radius of curvature of the third curved region E3, the more easily the drag is dispersed and transmitted.

In the present invention, it was found that stress can be dispersed over the entire brush body 2 by combining such properties. That is, when the stress concentration in the back direction acts at the first inflection point P1, the drag force in the front direction by the second substantially linear region S2 is more likely to act and is transmitted in the direction of the handle portion 3, It was found that stress can be distributed.

(Measure (3): Stress distribution by head → S1 → P1 → S2 → E1 E3 → E2)
When viewed from the side of the brush body 2, the second inflection point P2 is positioned opposite to the third curved region E3. Further, since the first curved region E1 and the third curved region E3 have the center of curvature on the flocked surface 5a side of the brush body 2, the direction of the drag force at the second inflection point P2 is the front side.

Here, if a second curved region E2 having a center of curvature is provided on the back side of the brush body 2 via the second inflection point P2 on the front side, the drag in the front direction is generated at the second inflection point P2. When it works, it has the property that the resistance tends to act on the back side due to the nature of its curved shape. In addition, the greater the radius of curvature of the second curved region E2, the more easily the drag is dispersed and transmitted.

In the present invention, it was found that stress can be dispersed over the entire brush body 2 by combining such properties. That is, when a frontal drag acts at the second inflection point P2, the rearward drag from the second curved region E2 is more likely to act and is transmitted in the direction of the handle portion 3 to disperse the stress. I found out what I can do. In addition, in the second curved region E2, since the effect in the front direction from the third curved region E3 is also transmitted, it can be expected that the acting drag forces cancel each other on the front side and the back side, and the stress can be dispersed more.

In the toothbrush 1 of the present embodiment, the characteristic shapes of the front side and the back side in the side view of the brush body 2 based on the above measures (1) to (3) avoid stress concentration on the neck portion 4, and the head Stress can be dispersed in the entire brush body 2 from the portion 5 to the handle portion 3, and bending of the neck portion 4 can be suppressed.

(Position of first inflection point P1, distance from boundary O to first inflection point P1)
In the toothbrush 1 of this embodiment, the first inflection point P1 is located at the neck portion 4 . As defined above for the neck portion 4, the length of the neck portion 4 in the present invention is defined to be within 50 mm in the side direction of the handle portion 3 with the boundary O as the base point in front view. The distance from the boundary O to the first inflection point P1 in a front view is preferably within 30 mm, more preferably within 25 mm, and even more preferably within 20 mm.

(Position of second inflection point P2)
In the toothbrush 1 of this embodiment, the second point of inflection P2 is positioned closer to the handle portion 3 than the first point of inflection P1. The second inflection point P2 may be at the neck portion 4 or at the handle portion 3 .

(Distance between first inflection point P1 and second inflection point P2 (first curve area E1))
When viewed from the front of the brush body 2, the distance between the first inflection point P1 and the second inflection point P2 is preferably 10 to 45 mm, more preferably 25 to 40 mm. As a result, a sufficient distance can be ensured to disperse the stress concentration applied to the first inflection point P1 toward the handle portion 3 via the first curved region E1 and the second curved region E2.

(Relationship between radii of curvature R1 and R2)
In the toothbrush 1 of this embodiment, it is preferable that the radius of curvature R1 of the first curved region E1 is smaller than the radius of curvature R2 of the second curved region E2. Also, the radius of curvature R1 of the first curved region E1 is preferably 50 to 300 mm, more preferably 100 to 200 mm. On the other hand, the radius of curvature R2 of the second curved region E2 is preferably 150-600 mm, more preferably 200-400 mm.

As a result, the surface can be composed of a smooth curve from the neck portion 4 toward the handle portion 3 side. As a result, the stress concentration at the first inflection point P1 of the neck portion 4 is transferred to the first curved region E1. Then, it is transmitted to the second curved region E2 having the center of curvature on the back side of the brush body 2 via the second inflection point P2, so that the stress concentration on the handle portion 3 side can be dispersed, and the neck portion 4 does not bend excessively, and good intraoral operability can be ensured. In addition, even when the handle portion 3 is made thicker, the handle portion 3 can be easily gripped.

(Second curve area E2: specific area from second inflection point P2 to rear end of handle)
It is preferable that the second curved region E2 is 70% or more of the length from the second inflection point P2 to the rearmost end of the handle portion 3 in side view. As a result, even when the handle portion 3 is thickened, the handle portion 3 can be held well. Further, by configuring the surface of the handle portion 3 with a smooth curve, stress concentration via the first curved area E1 can be dispersed to the second curved area E2.

The reason why the second curved region E2 is set to at least 70% or more of the total length of the handle portion 3 is that the surface of the handle portion 3 such as the finger rest portion 7 projecting from the front side of the handle portion 3 is discontinuous. This is to allow the provision of such a region.

In addition, in the length from the second inflection point P2 to the rearmost end of the handle portion 3 in a side view, for example, R200 and R300 are connected to form a curve, that is, a plurality of Rs are connected. Even in the case of a curve with

(Distance between the second inflection point P2 and the position of the maximum thickness D3)
In addition, when viewed from the front of the brush body 2, the distance between the second inflection point P2 and the maximum thickness D3 of the handle portion 3 is preferably 45 to 65 mm, more preferably 50 to 60 mm. is more preferred. As a result, stress concentration on the neck portion 4 via the first curved region E1 can be avoided, and a distance sufficient to disperse the stress to the second curved region E2 can be secured.

(Distance between boundary O and maximum thickness D3)
Further, the distance between the boundary O between the head portion 5 and the neck portion 4 and the position of the maximum thickness D3 of the handle portion 3 is preferably 60 to 110 mm, more preferably 70 to 110 mm. . As a result, even if the head portion 5 is thin, the neck portion 4 is thin, and the handle portion 3 is thick, the surface of the handle portion 3 can be configured with a smooth curve, and the stress concentration on the neck portion 4 can be reduced in the handle. It disperses toward the rear end side of the portion 3, and can suppress excessive deflection of the neck portion 4. - 特許庁

(Positional relationship of the third inflection point P3)
The stress concentration at the first inflection point P1 can be transmitted to the third inflection point P3 via the second substantially linear region S2, and the received stress concentration can be dispersed to the third curved region E3. It is preferable that the third inflection point P3 exists closer to the steering wheel than the first inflection point P1.

In addition, the stress can be further dispersed by transmitting the drag force in the front direction by the second substantially linear region S2 to the first curved region E1 and further transmitting it from the first curved region E1 to the second curved region E2. Therefore, it is preferable that the third inflection point P3 exists closer to the neck than the second inflection point P2.

(Relationship between radii of curvature R3 and R1)
Preferably, the radius of curvature R3 of the third curved region E3 is greater than the radius of curvature R1 of the first curved region E1. Also, the radius of curvature R3 of the third curved region E3 is preferably 100 to 1000 mm, more preferably 100 to 500 mm. As a result, the stress concentration at the first inflection point P1 of the neck portion 4 is transmitted to the third inflection point P3 via the second substantially linear region S2, and the received stress concentration is transferred to the third curved line. It is possible to disperse to the region E3, suppress excessive bending of the neck portion 4, and ensure operability in the oral cavity.

(Third curve area E3)
Further, in the toothbrush 1 of the present embodiment, at least 30% or more of the length from the third inflection point P3 to the rearmost end of the handle portion 3 in the side view of the brush body 2 is the third curved region E3. and located across the neck portion 4 and the handle portion 3 .

As a result, the stress concentration at the first inflection point P1 of the neck portion 4 during tooth brushing is transmitted to the third inflection point P3 via the second substantially linear region S2, and the third curved region E3 is formed. Due to the property of the curved shape, the drag force tends to act on the front side, and the drag force in the front direction due to the second substantially straight region S2 tends to act, and the stress concentration at the first inflection point P1 can be easily dispersed. can. As a result, excessive bending of the neck portion 4 can be suppressed, and operability in the oral cavity can be ensured.

(Relationship between radii of curvature R3 and R2)
The radius of curvature R3 of the third curved region E3 is preferably smaller than the radius of curvature R2 of the second curved region E2. As a result, the drag force in the front direction by the second substantially linear region S2, the drag force in the front direction by the first curved region E1, and the drag force in the front direction by the third curved region E are transferred from the first curved region E1 to the 2 to the curved region E2 to further distribute the stress.

(Relationship between radii of curvature R4 and R2)
Preferably, the radius of curvature R4 of the fourth curved region E4 is greater than the radius of curvature R2 of the second curved region E2. Also, the curvature radius R4 of the fourth curved region E4 is preferably 500 mm or more, more preferably 1000 mm or more.

As a result, the stress concentration transmitted to the third curved region E3 is transmitted to the fourth inflection point P4, and the received stress concentration can be dispersed to the fourth curved region E4, thereby suppressing excessive bending of the neck portion 4. At the same time, operability can be ensured. Further, in this embodiment, the fourth curved region E4 has the center of curvature on the side of the flocked surface 5a of the brush body 2, so that when the handle portion 3 is gripped, there is a slight difference between the handle portion 3 and the palm. It can be gripped with the whole palm by reducing the gap between them, and the gripability is improved.

(Fourth curve area E4)
In a side view of the brush body 2, it is preferable that at least 50% or more of the length from the fourth inflection point P4 to the rearmost end of the handle portion 3 is formed by the fourth curved region E4.

As a result, the stress concentration transmitted to the third curved region E3 is transmitted to the fourth inflection point P4, and the received stress concentration can be dispersed to the fourth curved region E4, thereby suppressing excessive bending of the neck portion 4. At the same time, operability can be ensured.

(Curving direction of the fourth curved region E4)
The curvature radius R4 of the fourth curved region E4 has the center of curvature on the side of the flocked surface 5a of the brush body 2, but may be on the back side of the head portion 5. FIG. If it is provided on the back side of the head portion 5, the rotation of the handle portion 3 is restricted when the handle portion 3 is gripped along the fourth curved region E4, so that the gripping direction can be positioned. As a result, the handle portion 3 does not rotate during toothbrushing, and the intraoral operability is improved.

Regarding the characteristic shape in the side view of the brush body 2 described above, the case where it is composed only of the resin (primary resin) that constitutes the brush body 2 has been described, but the surface is covered over the entire length of the brush body 2. In the case of the configuration provided with the coating material 8 for coating, the characteristic shape described above is uniquely defined as the outline of the brush body 2 .

When covering with the covering material 8, it is preferable that the brush body 2 is provided with a stepped portion 9 made of the primary resin. By providing the stepped portion 9, the surface of the handle portion 3 can be made flush with the surface of the handle portion 3 when covered with the covering material 8, and the appearance and touch feel are improved. It is also preferable in terms of manufacturability in two-color molding.

As the coating material 8, for example, an elastomer resin such as a polyolefin elastomer, a styrene elastomer, a polyester elastomer, a polyurethane thermoplastic elastomer, or a silicone resin can be used.

The stepped portion 9 is preferably formed to be one step lower than the neck portion 4 side by 1 to 3 mm on the handle portion 3 side. Moreover, the minimum thickness of the stepped portion 9 is preferably 3 mm or more in terms of strength.

If the stepped portion 9 is provided, the thickness and width dimensions of the handle portion 3 or the neck portion 4 are shortened, so that the amount of resin is reduced and the strength is lowered. Therefore, it is preferable that the stepped portion 9, which is formed to be one step lower, is connected from the neck portion 4 side to the handle portion 3 side with a radius of curvature in the range of 0.5 to 1.5. As a result, even if the stress applied to the head portion 5 during toothbrushing is transmitted to the stepped portion, stress concentration on the stepped portion 9 can be alleviated.

It is preferable that the covering material 8 forms a continuous surface between the handle portion 3 and the neck portion 4 by covering the surface from the stepped portion 9 . As a result, when cleaning the oral cavity, the elastic force of the covering material 8 can alleviate the concentration of stress generated at the boundary (the stepped portion 9) between the handle portion 3 and the neck portion 4. FIG.

The covering material 8 may be formed so as to cover the entire surface from the neck portion 4 to the handle portion 3, or may cover the entire circumference. From the point of view of reducing stress concentration, it is preferable to cover the whole circumference from the neck portion 4 to the handle portion 3 .

Moreover, it is preferable that at least 50% or more of the surface area of the handle portion 3 is covered with the covering material 8 . Moreover, the thickness of the covering material 8 is preferably 0.5 to 3.5 mm.

In a mode in which the coating material 8 is coated so as to cover the surroundings, the resin (primary resin) that constitutes the brush body 2 may be at the central position in the cross section of the coated portion, or at an unevenly distributed position. may Moreover, it is preferably located at the center position of the covering material 8 from the point of being able to relax the stress concentration.

Furthermore, when A1 is the cross-sectional area of the resin forming the brush body 2 and A2 is the cross-sectional area of the coating material 8 at the relevant portion, the ratio of A2/(A1+A2) is 0.45 to 0.75. preferable. Thereby, in the toothbrush 1, the feeling of grip when holding the handle portion 3 can be enhanced.

At the position where the handle portion 3 has the maximum thickness D3, the ratio of A2/(A1+A2) is preferably 0.45 to 0.75, more preferably 0.6 to 0.75. Thereby, in the toothbrush 1, the feeling of grip when holding the handle portion 3 can be enhanced. Also, stress concentration can be relaxed.

Furthermore, at the central position in the longitudinal direction of the handle portion 3, the ratio of A2/(A1+A2) is preferably 0.45 to 0.75, more preferably 0.6 to 0.75. Thereby, in the toothbrush 1, the feeling of grip when holding the handle portion 3 can be enhanced.

In the step portion 9, the ratio of A2/(A1+A2) is preferably 0.45 to 0.75, more preferably 0.45 to 0.55. Thereby, stress concentration can be relaxed.

Further, in the toothbrush 1 of the present embodiment, when the brush body 2 is viewed from the side, it is preferable that the extension line L of the flocked surface 5a overlaps the brush body 2 over the entire length of the handle portion 3 . As a result, stress concentration can be dispersed toward the rear end side of the handle portion 3 . That is, in the case of an S-shaped handle in which the extension line L of the flocked surface 5a does not overlap the brush body 2 over the entire length of the handle 3, stress concentration on the neck 4 occurs when the handle 3 is thick. becomes easier to wake up. However, the stress concentration on the neck portion 4 can be dispersed toward the rear end side of the handle portion 3 due to the above-described overlapping position, that is, the linear shape.

As described above, in the toothbrush 1 of the present embodiment, even when the head portion 5 is thinned and the neck portion 4 is thinned, the entire brush body 2 suppresses bending of the neck portion. Accordingly, it is possible to provide the toothbrush 1 that achieves both excellent gripability of the handle portion 3 and good intraoral operability.

It should be noted that the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.
For example, in the above-described embodiment, the case where the present invention is applied to the above-described toothbrush 1 for manual polishing is illustrated, but the body portion including the handle portion 3 is replaced with the neck portion 4 and the head portion 5. It is also possible to apply the present invention to an electric toothbrush to which a replacement brush is detachably attached.

Hereinafter, the effects of the present invention will be made clearer by way of examples. It should be noted that the present invention is not limited to the following examples, and can be modified as appropriate without changing the gist of the invention.

(Examples 1-8, Comparative Examples 1-2)
In this example, toothbrushes of Examples 1 to 8 and Comparative Examples 1 and 2 were produced according to the specifications shown in Table 1 below. Specifically, a PP resin was injection-molded to produce a brush body. At this time, the arrangement of the tufting holes was 3 holes×1 row, 4 holes×5 rows, and 3 holes×1 row from the tip of the head toward the handle body. The width of the head portion was 10 mm and the length was 25 mm. Thereafter, tufts of taper bristles (7.5 mil) made of PBT filaments were implanted in the tufting holes of the head portion by flat wire tufting to produce a toothbrush. For the toothbrush of Example 8, after the brush body was injection molded, the surface from the stepped portion to the rear end of the handle portion was covered with a soft member. Tables 1 to 4 below summarize the specifications of each toothbrush.

(Method for evaluating grippability)
The toothbrushes of Examples 1 to 8 and Comparative Examples 1 and 2 were evaluated for "toothbrush grip" during brushing. A summary of the evaluation results is shown in Table 4 above.

A panel of 10 experts used each toothbrush to evaluate the gripability of the toothbrush according to the following evaluation criteria. In addition, an average score of 4.5 points or more from the 10 specialized panels is indicated as "◎", an average score of 3.5 points or more and less than 4.5 points is indicated as "○", and an average score of 2.5 points or more and 3.5 points. A score less than 2.5 points was evaluated as "triangle" and an average score of less than 2.5 points as "x". Therefore, the higher the score, the better the grip of the toothbrush.

<Evaluation Criteria>
5 points: Very good.
4 points: Slightly good.
3 points: Good.
2 points: Slightly unsatisfactory.
1 point: Not good.

(Evaluation method for intraoral operability)
In addition, regarding the toothbrushes of Examples 1 to 8 and Comparative Examples 1 and 2, evaluation of "intraoral operability of the toothbrush (ease of movement in the mouth, absence of excessive bending of the neck)" during toothbrushing. did A summary of the evaluation results is shown in Table 4 above.

The operability of the toothbrushes was evaluated by a panel of 10 experts using each toothbrush according to the following evaluation criteria. In addition, an average score of 4.5 points or more from the 10 specialized panels is indicated as "◎", an average score of 3.5 points or more and less than 4.5 points is indicated as "○", and an average score of 2.5 points or more and 3.5 points. A score less than 2.5 points was evaluated as "triangle" and an average score of less than 2.5 points as "x". Therefore, the higher the score, the better the intraoral operability.

<Evaluation Criteria>
5 points: Very good.
4 points: Slightly good.
3 points: Neither can be said.
2 points: Not good.
1 point: Not good.

As shown in Table 4, the toothbrushes of Examples 1 to 8 had higher evaluation results in terms of "holdability of the toothbrush" and "operability in the oral cavity" during toothbrushing than the toothbrushes of Comparative Examples 1 and 2. was gotten.

DESCRIPTION OF SYMBOLS 1... Toothbrush 2... Brush body 3... Handle part 4... Neck part 5... Head part 5a... Flocking surface 6... Flocking hole 7... Finger rest part 8... Covering material 9... Stepped part O... Boundary S1... First approximate straight line Area S2... Second substantially linear area E1... First curve area E2... Second curve area E3... Third curve area E4... Fourth curve area P1... First inflection point P2... Second curve area Point of inflection P3... Third point of inflection P4... Fourth point of inflection L... Extension line

Claims (14)

a handle;
a neck portion extending from the tip of the handle portion;
a brush body including a head portion provided at the tip of the neck portion;
A toothbrush in which a plurality of bristle bundles are implanted on the bristle-implanted surface of the head,
The brush body has a shape in which the thickness of the neck portion increases continuously from the head portion toward the handle portion,
and,
The thickness D1 of the head portion is 2 to 4 mm,
The minimum thickness D2 at the neck portion is 3 to 4.5 mm,
The maximum thickness D3 of the handle portion is 13 to 16 mm ,
The ratio represented by the maximum thickness D3/the thickness D1 is 3.5 to 7,
The ratio represented by the maximum thickness D3 / the minimum thickness D2 is 3 to 5,
When viewed from the side, the brush body includes a first substantially linear region S1 continuous with the flocked surface, and a flocked surface side of the brush body extending from the first substantially linear region S1 through a first inflection point P1. and a first curved region E1 thicker than the minimum thickness D2, and a center of curvature extending from the first curved region E1 to the back side of the brush body via the second inflection point P2 and a second curve region E2 having
When the brush body is viewed from the front, the width of the brush body widens from the neck portion to the handle portion, and the position where the width starts to widen from the minimum width W2 of the neck portion is located at the neck portion. ,
A toothbrush , wherein the first inflection point P1 is positioned closer to the head than a position where the minimum width W2 begins to widen . The toothbrush according to claim 1 , wherein the radius of curvature R1 of the first curved region E1 is smaller than the radius of curvature R2 of the second curved region E2. 3. The toothbrush according to claim 1, wherein the distance between said first inflection point P1 and said second inflection point P2 is 10-45 mm. The toothbrush according to any one of claims 1 to 3 , wherein the distance between the second inflection point P2 and the position of the maximum thickness D3 is 45 to 65 mm. 5. The method according to any one of claims 1 to 4 , wherein a distance between a boundary O between the head portion and the neck portion and the position of the maximum thickness D3 is 70 to 110 mm. toothbrush. When the brush body is viewed from the side,
a second substantially linear region S2 continuous to the back surface of the head portion;
The toothbrush according to any one of claims 1 to 5 , further comprising a third curved region E3 that curves from the second substantially straight region S2 through a third inflection point P3. 7. The toothbrush according to claim 6 , wherein the third point of inflection P3 is positioned closer to the handle than the first point of inflection P1. The toothbrush according to claim 6 or 7 , wherein the radius of curvature R3 of the third curved region E3 is larger than the radius of curvature R1 of the first curved region E1. The toothbrush according to any one of claims 6 to 8 , wherein the third curved region E3 has a center of curvature on the bristle-implanted surface side of the brush body. 10. The brush body according to any one of claims 1 to 9 , wherein when the brush body is viewed from the side, the extension line of the flocked surface is positioned to overlap the brush body over the entire length of the handle portion. toothbrush. The toothbrush according to any one of claims 1 to 10 , wherein the bending elastic modulus of the resin constituting the brush body is 1000 MPa or more and 2800 MPa or less. The toothbrush according to any one of claims 1 to 11 , wherein the resin constituting the brush body is polypropylene resin. Having a covering material covering the surface of the handle portion,
The toothbrush according to any one of claims 1 to 12 , wherein the coating material is made of a resin that is softer than the resin that constitutes the brush body. 14. The toothbrush according to claim 13 , wherein said covering material is made of elastomer resin or silicone resin.

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