JP2013126494A - Toothbrush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toothbrush having a handle formed of a primary molded portion and a secondary molded portion which are formed by two-color molding, and preventing the secondary molded portion from separating from the primary molded portion.SOLUTION: The toothbrush includes a head, a neck extended to the head, a handle extended to the neck. The handle has the primary molded portion 30 formed of a first resin and having a polygonal pillar shape, and the secondary molded portion 32 formed of a second resin different from the first resin, and formed on at least one side surface of the primary molded portion 30 in a manner to be substantially flush with the side surface. In the primary molded portion 30, an interior angle θ between a first side surface 30a formed with the secondary molded portion 32 and a second side surface 30b adjacent to the first side surface 30a is not smaller than 90° and not larger than 150°, and the edge width L from the intersection point P of a tangential line Textending in a width direction of the first side surface 30a and a tangential line Textending in a width direction of the second side surface 30b to the secondary molded portion 32 is not shorter than 0.5 mm and not longer than 1.5 mm.

Description

  The present invention relates to a toothbrush.

As toothbrushes, those produced by two-color molding are known for the purpose of improving usability, operability and designability during oral cleaning. For example, it is known that at least the handle part includes a primary molded part made of a hard resin and a secondary molded part such as a grip part made of a soft resin (Patent Documents 1 to 3).
As the hard resin, from the viewpoint of strength and appearance, polyolefin resins such as polypropylene and polyester resins such as polyethylene terephthalate are widely used. Moreover, as a soft resin, the olefin-type elastomer and the polyester-type elastomer are used from the point of adhesiveness with the said hard resin. However, in a conventional toothbrush produced by two-color molding, the secondary molded part may peel from the primary molded part during use.

  In recent years, polyoxymethylene (polyacetal), polybutylene terephthalate are used as hard resins in order to further improve the strength of toothbrushes, or to ensure sufficient strength even if the head is thin and the neck is thin. Engineering plastics such as polytrimethylene terephthalate may be used. However, since the engineering plastic has low adhesion to the soft resin, in the two-color molded toothbrush made of the engineering plastic and the soft resin, the portion made of the soft resin sometimes peels off during use.

JP-A-1-300905 Japanese Utility Model Publication No. 3-21607 JP 2001-299450 A

In a two-color molded toothbrush, if the secondary molded part peels from the primary molded part, the designability may be impaired, and the usability and operability may decrease. Furthermore, dirt and wrinkles are likely to adhere, and hygiene may be reduced.
An object of the present invention is to provide a toothbrush in which a primary molded part and a secondary molded part are formed by two-color molding, and the handle part is produced, but the secondary molded part is difficult to peel off from the primary molded part. To do.

The present invention has the following aspects.
[1] A head portion, a neck portion extended to the head portion, and a handle portion extended to the neck portion, the handle portion being a polygonal columnar primary molded portion made of a first resin; And a secondary molded part formed of a second resin different from the first resin, and formed on at least one side surface of the primary molded part so as to be substantially flush with the side surface. The inner angle θ formed by the first side surface on which the secondary molded portion is formed and the second side surface adjacent to the first side surface is 90 ° or more and 150 ° or less, and the width direction with respect to the first side surface A toothbrush characterized in that an edge width L from an intersection of a tangent extending to the second side and a tangent extending in the width direction of the second side surface to the secondary molded portion is 0.5 mm or more and 1.5 mm or less.

[2] The toothbrush according to [1], wherein the first resin is any one of polyoxymethylene, polybutylene terephthalate, and polytrimethylene terephthalate, and the second resin is an elastomer.

  In the toothbrush of the present invention, although the primary molded part and the secondary molded part are formed by two-color molding to produce the handle part, the secondary molded part is difficult to peel from the primary molded part. Moreover, the toothbrush of this invention is excellent also in the moldability of two-color molding.

It is a top view which shows one Embodiment of the toothbrush of this invention. It is a side view which shows one Embodiment of the toothbrush of this invention. It is I-I 'sectional drawing of FIG.

An embodiment of the toothbrush of the present invention will be described with reference to FIGS. 1, 2, and 3.
The toothbrush 1 of the present embodiment includes a head portion 10, a neck portion 20 that extends to the head portion 10, and a handle portion 30 that extends to the neck portion 20.

(Handle part)
The handle portion 30 in this embodiment includes a primary molding portion 31 and a secondary molding portion 32. Here, the primary molding portion 31 is a rod-like body having a hexagonal cross section (that is, a hexagonal column shape) perpendicular to the longitudinal direction, and the secondary molding portion 32 includes two primary molding portions 31 parallel to each other. It is formed on the side surface (first side surface 30a). Each of the two first side surfaces 30a is parallel to the flocked surface 11a of the head portion 10 on which the hair bundle 12 is implanted. In addition, the primary molding portion 31 in the present embodiment has a curved corner cut at a corner portion in a cross section perpendicular to the longitudinal direction.
In the first side face 30a, the primary molding part 31 and the secondary molding part 32 are substantially flush with each other. Although there may be a step between the primary molding part 31 and the secondary molding part 32, the step is preferably as small as possible because the peel prevention property of the secondary molding part 32 becomes higher.

The internal angle θ between the first side surface 30a and the second side surface 30b adjacent to the first side surface 30a is 90 ° or more and 150 ° or less, and more preferably 90 ° or more and 125 ° or less. When the internal angle θ is less than the lower limit value, it becomes difficult to grip the handle portion 30, so that the practicality is impaired, and when the upper limit value is exceeded, peeling of the secondary molded portion 32 cannot be prevented when the toothbrush 1 is used. There is.
Further, the edge width L from the intersection P between the tangent line _{T 2} which relative to the first side surface 30a and the tangent _{T 1} extending in the width direction extending in the width direction of the second side surface 30b to a secondary molding portion 32 is 0.5mm or more 1. It is 5 mm or less, and more preferably 0.7 mm or more and 1.1 mm or less. When the edge width L is less than the lower limit value, the moldability of two-color molding is lowered, and when the upper limit value is exceeded, peeling of the secondary molded part 32 may not be prevented when the toothbrush 1 is used.

The primary molding portion 31 is a member that becomes the core of the handle portion 30. In the primary molding portion 31 in the present embodiment, a concave portion 31 a that is recessed from the first side surface 30 a to the inside of the handle portion 30 is formed in a groove shape along the longitudinal direction of the primary molding portion 31. The recess 31a in the present embodiment has a rectangular opening, and the opening width increases as the surface of the handle portion 30 is approached.
Further, the primary molding portion 31 has a rectangular opening and two through holes 31b communicating with both the recesses 31a extending in the longitudinal direction of the handle portion 30 and arranged in the width direction.

Moreover, the primary molding part 31 is comprised from 1st resin. The first resin can be determined in consideration of the rigidity and mechanical characteristics required for the toothbrush 1, and examples thereof include a hard resin having a flexural modulus (JIS K7203) in the range of 500 to 3000 MPa.
Specific examples of the hard resin include, for example, polypropylene (PP), polyoxymethylene (POM), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polycyclohexylene dimethylene terephthalate ( PCT), polystyrene (PS), acrylonitrile / butadiene / styrene resin (ABS), cellulose propionate (CP), polyarylate, polycarbonate, acrylonitrile / styrene copolymer resin (AS), and the like. These hard resins can be used alone or in combination of two or more.
Among the above hard resins, any of POM, PBT, and PTT is preferable because of its high strength and rigidity. Furthermore, in terms of particularly exerting the effects of the present invention, POM is particularly preferable because it has a very high crystallization rate and does not contain a highly reactive functional group in the molecule, and therefore has low adhesion to other resins.
In addition, since the primary molding part 31, the head part 10, and the neck part 20 are normally shape | molded integrally, these are comprised with the same material.

The secondary molding part 32 is formed by filling the recess 31 a and the through hole 31 b of the primary molding part 31, and is fixed to the primary molding part 31. Since the opening part of the recessed part 31a is rectangular shape, in the secondary shaping | molding part 32 with which the recessed part 31a was filled, the part exposed to the surface of the handle | steering-wheel part 30 is also rectangular shape.
Moreover, the secondary shaping | molding part 32 is comprised from 2nd resin different from 1st resin. The second resin is preferably a soft resin that can be deformed by the pressing force of a finger because grip properties are improved. The shore hardness A of the soft resin is preferably 90 or less, and more preferably 50-80.
Specific examples of the soft resin include elastomers (for example, olefin elastomers, styrene elastomers, polyester elastomers, polyurethane thermoplastic elastomers, etc.) and silicones. In the case where any one of POM, PBT, and PTT is used as the hard resin, the effect of the present invention is particularly exhibited when an elastomer is used as the soft resin.
The soft resin may contain an adhesive modifier, a plasticizer, and the like as necessary.

(Head)
The head unit 10 according to the present embodiment includes a resin-made substantially elliptical head unit main body 11 and a plurality of hair bundles 12 planted on the flocked surface 11 a of the head unit main body 11.

The maximum thickness of the head portion 10 is not particularly limited and can be appropriately determined in consideration of the material and the like. However, when it is desired to improve the operability in the oral cavity, the thickness is preferably 4 mm or less, and 2-3 mm. It is more preferable. If the maximum thickness of the head part 10 is less than or equal to the upper limit value, the operability in the oral cavity of the toothbrush 1 can be improved, and if it is greater than or equal to the lower limit value, strength reduction of the head part 10 can be prevented.
When the maximum thickness of the head portion 10 is 4 mm or less, the head portion 10 is preferably formed of any one of POM, PBT, and PTT.

The hair bundle 12 is a bundle of a plurality of hairs.
The length (hair length) from the flocked surface 11a to the tip of the hair bundle 12 can be determined in consideration of the hair and the like required for the hair bundle 12, and is, for example, 6 to 13 mm. Further, the hair length of the hair bundle 12 may be the same for all the hair bundles or may be different from each other.

  The thickness (hair bundle diameter) of the hair bundle 12 can be determined in consideration of the waist and the like required for the hair bundle 12, and is, for example, 1 to 2 mm. All the hair bundles 12 may have the same hair bundle diameter or may be different from each other.

  As the hair constituting the hair bundle 12, for example, the diameter gradually decreases toward the hair tip, the hair having a sharp hair tip (tapered hair), and the diameter from the flocked surface 11a toward the hair tip. Examples include hairs that are almost the same (straight hairs). Examples of the straight hair include those having a hair tip which is a plane substantially parallel to the flocked surface 11a and those having a hair tip rounded into a hemisphere.

The material of the hair is, for example, polyamide such as 6-12 nylon (6-12NY), 6-10 nylon (6-10NY), PET, PBT, polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), Examples thereof include polyesters such as polybutylene naphthalate (PBN), polyolefins such as PP, elastomer resins such as olefin elastomers and styrene elastomers. These resin materials can be used singly or in combination of two or more.
Examples of the bristle include polyester bristle having a multi-core structure having a core and at least one or more sheaths provided outside the core.

  The cross-sectional shape of the hair is not particularly limited, and may be a circle such as a perfect circle or an ellipse, a polygon, a star, a three-leaf clover, a four-leaf clover, or the like. The cross-sectional shapes of all the hairs may be the same or different.

  The thickness of the hair can be determined in consideration of the material and the like. When the cross section is circular, the thickness is, for example, 6 to 9 mil. Further, in consideration of a feeling of use, a feeling of brushing, a cleaning effect, durability, and the like, a plurality of hairs having different thicknesses may be used in any combination.

(Neck part)
The neck portion 20 in the present embodiment has a rod shape, and a cross section perpendicular to the longitudinal direction has a substantially circular shape.
The minimum diameter of the neck portion 20 is not particularly limited and can be appropriately determined in consideration of the material and the like. However, when it is desired to improve the operability in the oral cavity, it is preferably 4 mm or less, and 2 to 4 mm. It is more preferable. If the minimum diameter of the neck part 20 is less than or equal to the upper limit value, the operability in the oral cavity of the toothbrush 1 can be improved, and if it is greater than or equal to the lower limit value, a decrease in strength of the neck part 20 can be prevented.
When the minimum diameter of the neck portion 20 is 4 mm or less, the neck portion 20 is preferably formed of any one of POM, PBT, and PTT.

(Production method)
The toothbrush 1 is manufactured according to a conventionally known two-color molding method.
For example, the first resin is injected into the primary mold, and the head portion 10, the neck portion 20, and the primary molding portion 31 are molded. Next, the primary molding part 31 is mounted in the secondary mold, and the second resin is injected in this state, and the second resin is filled in the concave portions 31a and the through holes 31b of the primary molding part 31 to form the secondary molding part 32. Form. Next, the toothbrush 1 is obtained by implanting the bristle bundle 12 on the flocked surface 11 a of the head portion 10.
As a method for planting the hair bundle 12, for example, the hair bundle 12 is folded in two, and a flat wire sandwiched between them is driven into a flock hole so that the hair bundle 12 is implanted. A heat-sealing method in which the lower end is press-fitted into a molten resin that becomes a flocked portion, and the lower end of the hair bundle 12 is heated to form a molten mass, and then the molten resin is injected into the mold to mold the flocked portion. In-mold method and the like can be mentioned.

(Function and effect)
The toothbrush 1, in the handle portion 30, the interior angle θ between the first side surface 30a and the second side surface 30b, and a rim width L from the intersection P between the tangent line T ₁ and the tangent line T ₂ to a secondary molding section 32 the Since it is in the specific range, even when the nail or the abdomen of the finger contacts the first side surface 30a during use, it is difficult to get caught at the boundary between the primary molded part 31 and the secondary molded part 32. Therefore, the secondary molded part 32 is difficult to peel from the primary molded part 31 despite being produced by two-color molding. Thereby, the fall of design property, usability, and operativity can be prevented, and since dirt and wrinkles do not adhere easily, hygiene can be maintained.
Moreover, since the moldability of the two-color molding is enhanced by setting the edge width L within the specific range, the handle portion 30 including the primary molding portion 31 and the secondary molding portion 32 can be easily formed.

(Other embodiments)
In addition, this invention is not limited to the said embodiment.
For example, the primary molded portion may not be a hexagonal column shape, but may be a polygonal column shape other than a triangular column shape such as a pentagonal column shape, a heptagonal column shape, or an octagonal column shape.
The side surface on which the secondary molded part is formed may not be two, but may be one, or three or more. Moreover, the secondary shaping | molding part may be divided | segmented into plurality.
The opening part of the recessed part of a primary shaping | molding part does not need to be rectangular shape, for example, elliptical shape and another shape may be sufficient.
The number of through holes formed in the primary molded portion may not be two, but may be one, or may be three or more. Moreover, the through hole may not be formed. The shape of the through hole is not limited to that of the above embodiment, and may be, for example, a circular or elliptical opening.
Moreover, there is no restriction | limiting in particular about the shape of a head part and a neck part, A conventionally well-known shape is applicable.

The toothbrush 1 shown in FIG.1, FIG2 and FIG.3 was produced with the following method.
The POM was injected into the primary mold, and the head part 10, the neck part 20, and the primary molding part 31 were molded. Next, the primary molding part 31 is mounted in the secondary mold, and in that state, a styrene elastomer (Cryburg, Thermolast K) is injected, and the styrene elastomer is injected into the recess 31a and the through hole 31b of the primary molding part 31. To form a secondary molded part 32. Next, a hair bundle was implanted on the flocked surface 11 a of the head portion 10 to obtain the toothbrush 1.
In this example, the inner angle θ and the edge width L in FIG.

(Evaluation)
About the obtained toothbrush, the peeling prevention property and moldability of the secondary molding part were evaluated by the following methods.
[Peeling prevention of secondary molded part]
When five panelists scratched the secondary molding part of the handle part with the nail, the number of the secondary molding part peeled off was counted and evaluated according to the following criteria. The evaluation results are shown in Table 1.
A: 50 out of 50, 0: 1-2 out of 50, Δ: 3-5 out of 50 ×: 6 or more out of 50 [formability]
The number of molding defects in which molding defects such as burrs were observed was counted and evaluated according to the following criteria. The evaluation results are shown in Table 2. The evaluation results are shown in Table 2.
A: 50 out of 50, 0: 1-2 out of 50, Δ: 3-5 out of 50 ×: 6 or more out of 50 [overall evaluation]
Comprehensive evaluation was performed according to the criteria in Table 3. The evaluation results are shown in Table 4.

  When the inner angle θ and the edge width L are within the scope of the invention according to claim 1 of the present application, the peeling prevention property and the moldability of the secondary molded part were excellent.

1 a toothbrush 10 head portion 11 the head portion body 11a flocked surface 12 bristle bundles 20 neck portion 30 the handle portion 30a first side surface 30b second side 31 primary molded portion 31a recess 31b through holes 32 secondary molding section T _{1, T 2} tangential P Intersection L Edge width θ Interior angle

Claims (2)

A head portion, a neck portion extending to the head portion, and a handle portion extending to the neck portion,
The handle portion is formed of a polygonal columnar primary molded portion made of a first resin and a second resin different from the first resin, and is substantially flush with the side surface on at least one side surface of the primary molded portion. A secondary molded part formed as follows,
The primary molded portion has an inner angle θ formed by the first side surface on which the secondary molded portion is formed and the second side surface adjacent to the first side surface in a range of 90 ° to 150 °, A toothbrush characterized in that the edge width L from the intersection of the tangent extending in the width direction and the tangent extending in the width direction of the second side surface to the secondary molded part is 0.5 mm or more and 1.5 mm or less.   The toothbrush according to claim 1, wherein the first resin is any one of polyoxymethylene, polybutylene terephthalate, and polytrimethylene terephthalate, and the second resin is an elastomer.

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