JPH0515411A - Tooth brush - Google Patents

Abstract

PURPOSE:To provide a tooth brush having improved static strength and impact strength while having improved safety including improved fatigue strength. CONSTITUTION:The length from the tip of a bristle planting part 2 to a neck part 3 is formed straight an set to 60mm or more. The connection part between the neck part 3 and a grip 4 is tapered, while the remaining neck part 3 has the uniform diameter. The material mainly complies a polymer blend of polycarbonate and polyethylenetere phthalate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toothbrush capable of cleaning every corner of the oral cavity, having high operability and having practically sufficient neck strength.

[0002]

2. Description of the Related Art In recent years, toothbrushes have been redesigned so that the neck portion is elongated and the bristle portion is made smaller. As a material for the toothbrush, polypropylene (Acrylonitrile-styrene) resin, which does not break only by yielding, has become the mainstream. It was However, polypropylene becomes brittle and fractures easily at low temperatures, and it may be fractured even at room temperature when a sudden force is applied. Other than polypropylene, nylon, polycarbonate, PET (polyethylene terephthalate) and PBT (polybutylene terephthalate) are used.

[0003]

However, the material of the above toothbrush has a problem in practical strength. That is,
When formed into a slender shape, nylon, PET, and PBT have a problem that plastic deformation gradually occurs due to insufficient strength, and although polycarbonate has a high strength, it has a problem that it is easily attacked by a fragrance component in a dentifrice. Generally, the fatigue strength of plastics has not been studied so much,
Furthermore, there is nothing that considers the fatigue strength of the neck of the toothbrush. In recent years, it has been required to satisfy the tendency to make the neck portion elongated and the flocked portion small, to pursue usability, and at the same time, to determine the limit points of material physical properties and ensure safety. Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a toothbrush that enhances static strength and impact strength, and at the same time improves safety including fatigue strength. It is in.

[0004]

In order to achieve the above object, in the toothbrush according to the present invention, a straight line is formed from the tip of the bristle to the neck, and the length is set to 60 mm or more. The connecting portion between the neck portion and the grip portion is formed in a tapered shape, the remaining neck portion has a uniform diameter, and the material is a polymer blend of polycarbonate and polyethylene terephthalate as a main component. Further, it is preferable that the cross-sectional shape of the smallest diameter portion of the neck portion is a substantially quadrangle with chamfered corners. The material can also include a heat stabilizer.

[0005]

In the present invention having the above structure, since the connecting portion between the neck portion and the grip portion is formed in a tapered shape, stress concentration is less likely to occur when a force is applied to the bristle portion. Further, since the length from the tip of the bristle implant to the neck is set to 60 mm or more, it is possible to brush up to the second molar without inserting a part of the grip into the oral cavity. Further, since the material is mainly composed of a polymer blend of polycarbonate and polyethylene terephthalate, brittle fracture becomes difficult. In this case, if the material contains a heat stabilizer, the deterioration of physical properties due to the heat history of molding does not occur. Since the cross-sectional shape of the smallest diameter portion of the neck portion is a substantially square shape with chamfered corners, the second moment of area becomes large even if the neck portion has the same diameter.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the toothbrush according to the present invention. As shown in the figure, the toothbrush main body 1 is formed of a tufted portion 2, a neck portion 3 and a grip portion 4, and the tip of the tufted portion 2 to the neck portion 3 is linearly formed. And
The connecting portion between the neck portion 3 and the grip portion 4 is formed into a tapered shape to form a tapered portion 5. By the way, when pressure is applied to the flocked portion 2 during brushing, bending stress is generated in the neck portion 3, and breakage (static, impact, fatigue) and yielding are likely to occur at the portion where the maximum stress occurs. In order to avoid this, the shape of the neck portion 3 where stress concentration does not occur, that is, it is designed as a “beam of equal strength”. But in the neck of a real toothbrush,
From the viewpoint of usability, it is required to make the thin portion as long as possible, and the designability as a product must be taken into consideration. Therefore, in this embodiment, a taper portion 5 is provided at the connecting portion between the neck portion 3 and the grip portion 4 where stress concentration is most likely to occur, so as to avoid an abrupt change in cross section.

Further, it is desirable that the diameter of the neck portion 3 excluding the taper portion 6 is as thin and uniform as possible in terms of usability. In FIGS. 1 and 2, the minimum diameter of the neck portion 3 is 4.5 mm or less. . Then, as shown in FIG. 3B, the neck portion 3 is formed by chamfering the corners of the quadrangular cross section. This is because if the diameter is the same, it is more advantageous in terms of strength to make a quadrangle having a larger second moment of inertia than a circular cross section. . In recent years, the scrubbing method is becoming the mainstream of the cleaning method from the rolling method. Considering the cleaning of the occlusal surface, in order to avoid stress concentration in the thickness direction rather than the width direction of the neck portion 3, It is desirable that the ratio of the tapered portions 5 in the thickness direction is equal to or larger than that in the width direction.

Further, in this embodiment, the length from the tip of the bristle portion 2 to the neck portion 3 including the taper portion 5 is set to 60 mm or more. That is, referring to the average size of the Japanese permanent dental arch, the upper jaw is larger than the lower jaw, and the distance between the distal surface of the second molar of the upper jaw and the midline (between the first incisors) is about 60 mm. Is. Therefore, in order to brush up to the second molar without inserting part of the gripper 4 into the oral cavity,
From the viewpoint of usability, it is preferable that the length a from the tip of the flocked portion 2 to the neck portion 3 including the tapered portion 5 is 60 mm or more. Then, it has been found that the length a is preferably 70 to 75 mm or more in consideration of the back and forth movement for brushing, the thickness of the lip, and the third molar (so-called wisdom tooth).

Further, in this embodiment, the main component is a polymer blend of polycarbonate and polyethylene terephthalate. That is, although polycarbonate has excellent mechanical strength, it has problems such as long material drying time, high molding temperature, and high injection pressure among molding conditions, and it is treated as a material for consumer toothbrushes. There is a difficult side. Further, since polycarbonate is apt to crack due to the fragrance in the dentifrice, the advantage in strength cannot be fully utilized. Therefore, a polymer blend of polycarbonate and polyethylene terephthalate, which is a material that has a high mechanical strength to some extent and is not easily attacked by a fragrance in a dentifrice, is used. In fact, complementary blending performance is not enough with polymer blends that are merely mixed,
By adding a heat stabilizer, it is possible to prevent deterioration of physical properties due to heat during molding. Tables 1 and 2 below show a comparison of molding conditions and a comparison of physical property values between polycarbonate and a polymer blend of polyethylene terephthalate and polycarbonate. Further, Table 3 shows the ratio of the number of flocked holes in which cracks have occurred when the flocked part having been flocked with a flat line is immersed in a dentifrice or alcohol. Table 4
Shows the amount of deflection and the number of times of fatigue resistance in the case where the neck portion is elongated while keeping the general shape, and in the present embodiment.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

Therefore, in this embodiment, by using the material whose main component is the polymer blend of polycarbonate and polyethylene terephthalate as described above,
It has become possible to specifically form the elongated neck portion 3. In this case, at least polycarbonate and polyethylene terephthalate may be the main components, and a reinforcing material such as a filler may be added.

[0015]

As described above, according to the toothbrush of the present invention, not only the static strength of the neck but also the impact strength,
While ensuring the safety of the neck including fatigue strength, the neck is specifically elongated to improve usability. Further, since the cross-sectional shape of the minimum diameter portion of the neck portion is formed into a substantially quadrangular shape with chamfered corners, each of the above strengths can be further enhanced. Furthermore, by adding a heat stabilizer to the material, it is possible to prevent deterioration of the physical properties due to heat during molding.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a toothbrush according to the present invention.

FIG. 2 is a partial cross-sectional side view of FIG.

3 (A), (B), (C), (D) and (E)
Are lines A-A, B-B and C-C in FIG. 2, respectively.
It is an expanded sectional end view of a line, a D-D line, and an E-E line.

[Explanation of symbols]

1 toothbrush body 2 Flocking part 3 neck 4 grip 5 Tapered part

Claims (3)

[Claims] 1. A straight line is formed from the tip of the flocked part to the neck, the length is set to 60 mm or more, the connecting part between the neck and the gripping part is tapered, and the remaining neck is uniform. A toothbrush having a diameter and a main component being a polymer blend of polycarbonate and polyethylene terephthalate. 2. The toothbrush according to claim 1, wherein a cross-sectional shape of the smallest diameter portion of the neck portion is a substantially square shape with chamfered corners. 3. The toothbrush according to claim 1 or 2, wherein the material contains a heat stabilizer.