JP2006141676A - Brush handle and molding method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality brush handle which has not only a soft gripping part showing excellent fit feeling but also a soft material showing excellent adhesiveness to a rigid core part. <P>SOLUTION: In the brush handle having the gripping part formed by covering the rigid core part with the soft material, a blended resin of a polystyrene elastomer and an olefinic elastomer is used as the soft material. The polystyrene elastomer with a rubber hardness degree of 15-25 and the olefinic elastomer with a rubber hardness degree of 60-80 are used. The ratio of blending the elastomers (the polystyrene elastomer:the olefinic elastomer) is 95:5-75:25, and the rubber hardness degree is 20-25 after blending. When the blended resin is molded around the rigid core part by covering, the polystyrene elastomer is used as a natural base resin, and the olefinic elastomer is used as a masterbatch resin with a toning material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brush handle having a grip portion formed by coating a hard core portion with a soft material and a molding method thereof.

  For example, in a toothbrush handle, in order to improve the fit of the grip portion, a hard core portion made of a hard resin such as polypropylene is covered with a soft elastomer. However, styrene elastomers, which are representative of soft elastomers, are not compatible with polypropylene and the like used for hard core parts, so that they are difficult to adhere firmly to each other, and the soft elastomers may be peeled off during use. there were.

  For these reasons, styrene-based elastomers are often combined with a hard core portion using uneven fitting, and the fitting structure of the hard core portion tends to be complicated. Therefore, in general, an olefin-based elastomer having a rubber hardness of around 60 and having a slightly high hardness and excellent adhesiveness has been used even at the expense of fit.

Hereinafter, some examples of the handle structure in the conventional toothbrush will be shown.
1. Patent Document 1 (Japanese Utility Model Publication No. 60-13025)
A toothbrush is shown in which the handle is made elastic by covering the handle with rubber. The toothbrush handle has a structure close to that of a general two-color molded handle, but no consideration has been given to the softness of grips, specific rubber materials, and physical properties.

2. Patent Document 2 (Japanese Patent Laid-Open No. 7-327737)
The toothbrush which gave the anti-slip | slip effect by comprising a handle | base part with the handle base part made from a synthetic resin material and the rubber part made from a synthetic rubber material is shown. In the case of this toothbrush, there are descriptions of polystyrene-based elastomers, polyolefin-based elastomers, etc. as the material of the rubber part, but no examination has been made on adhesiveness or soft feeling, and olefin-based elastomers should be used from the viewpoint of compatibility. Is desirable.

3. Patent Document 3 (Japanese Patent Laid-Open No. 2000-4944)
A toothbrush is shown in which the gripping portion is made of a thermoplastic resin and a thermoplastic elastomer. In the case of this toothbrush, there are descriptions of polystyrene-based elastomers, polyolefin-based elastomers and the like as thermoplastic elastomers, but as with the toothbrush described in Patent Document 2, no specific study has been made on adhesiveness and soft feeling. In view of compatibility, it is desirable to use an olefin elastomer.

4). Patent Document 4 (Japanese Patent Publication No. 2000-504609)
A toothbrush is shown in which a flange is formed on the back side of the gripping portion and the periphery of the flange is covered with a gripping element made of a thermoplastic elastic material, thereby providing rigidity to the elongated gripping portion and realizing a soft gripping feeling. . In the case of this toothbrush, as the thermoplastic elastic material covering the periphery of the flange, the Shore A hardness is only specified as 5 to 30, and the specific material and physical properties are not shown and the adhesiveness is also shown. No consideration has been given to softness or softness.

5. Patent Document 5 (Japanese Patent Laid-Open No. 2002-542854)
A toothbrush having a gripping portion having an elastic elastomer portion having a Shore A hardness in the range of 1 to 94 on a skeleton portion having an overall S shape is shown. In the case of this toothbrush, no study has been made on the adhesiveness and softness of the elastomer.

Japanese Utility Model Publication No. 60-13025 (full text, all figures) Japanese Patent Laid-Open No. 7-327737 (full text, full figure) Japanese Unexamined Patent Publication No. 2000-4944 (full text, full figure) Special Table 2000-504609 (full text, all figures) JP 2002-542854 A (the whole sentence, all figures)

  The conventional brush handle including the toothbrush handle has the following problems.

(1) In the case of using a styrene-based elastomer that is a soft elastomer in order to enhance the soft feeling of the gripping part, there is a problem that the compatibility with the core material is poor and it is easy to peel off.

(2) As a technique for improving the adhesion between a soft elastomer such as a styrene-based elastomer and a hard core such as polypropylene, polypropylene or polyethylene may be blended with the elastomer. There was a problem that the fit was impaired.

(3) When the olefin elastomer or polyester elastomer is coated around the hard core portion, it is necessary to set the rubber hardness to around 55 to 65 in order to ensure sufficient adhesion to the hard core portion. There was a problem that feeling and anti-slip effect were slightly inferior.

(4) Soft elastomers with a rubber hardness of around 30 or less are sticky and the elongation rate of the material itself is high, so it is difficult to cut with a normal pellet cutter. A cutter is required. In addition, in order to perform color matching with a master batch using a conventional injection molding machine, new capital investment is required. For this reason, coloring with a masterbatch is not usually performed, and all colored material resins that are previously colored on the base resin are used, but it is necessary to have a large amount of resin stock for each color, which increases costs. There was a problem. Further, all the coloring material resins have a problem that the dispersibility of the coloring agent is poorer than that of the master batch, and uneven color is easily generated in the molded product.

(5) Styrenic elastomers with low rubber hardness have high adhesion, and thus have a high sliding effect. However, they may be sticky and uncomfortable, and may be slippery when wet.

  The present invention has been made to solve the above problems, and has a high-quality brush handle in which not only the gripping portion is soft and excellent in fit, but also the adhesiveness of the soft material to the hard core portion is good, and its molding method Is intended to provide.

In order to achieve the above object, the present invention employs the following means.
That is, the invention described in claim 1 uses a blend resin of a styrene elastomer and an olefin elastomer as a soft material in a brush handle having a grip portion formed by coating a hard core portion with a soft material.

  The invention according to claim 2 is the invention according to claim 1, wherein a styrene elastomer having a rubber hardness of 15 to 25 is used, and an olefin elastomer having a rubber hardness of 60 to 80 is used. The blend ratio (styrene elastomer: olefin elastomer) is 95: 5-75: 25, and the rubber hardness after blending is 20-25. The rubber hardness shall be according to JIS K 6253 hardness test and test condition JIS A.

  The invention described in claim 3 is limited to a toothbrush handle having a head portion, a neck portion, and a grip portion as the brush handle.

  The invention according to claim 4 is a method for molding the brush handle, wherein when a blend resin of a styrene elastomer and an olefin elastomer is coated around a hard core portion, the styrene elastomer is used as a base resin in a natural manner. An olefin-based elastomer is used as a base resin for a masterbatch together with a toning material.

  According to the first aspect of the present invention, since a blend resin of a styrene elastomer and an olefin elastomer is used as a soft material covering the hard core portion, the grip portion can be soft and excellent in fit, and can be hard. A high-quality brush handle with good adhesion of the soft material to the core can be obtained.

  According to the invention described in claim 2, since the blend ratio and the rubber hardness are set to optimum values for the styrene elastomer and the olefin elastomer constituting the soft material, the above-described effect of the invention of claim 1 can be obtained. It can be realized more reliably.

  According to the third aspect of the present invention, it is possible to obtain a high-quality toothbrush handle having a soft and excellent fit and a good adhesion of the soft material to the hard core.

  According to the fourth aspect of the present invention, when forming the brush handle, it can be pelletized using a normal cutter. Therefore, since no special capital investment is required and there is no need to have an extra resin inventory, the manufacturing cost can be reduced to the same level as a normal handle molded product, and the brush handle can be provided at a low price. Moreover, since it can color with a masterbatch, the brush handle without a color nonuniformity can be manufactured.

  The brush handle of the present invention has a grip portion formed by coating a hard core portion with a soft material, and a blend resin of a styrene elastomer and an olefin elastomer is used as the soft material. Hereinafter, the material, blend ratio, handle structure, molding method, etc. will be described in more detail.

1. Material As the hard core portion constituting the base portion of the brush handle, a known hard resin such as polypropylene can be used.

  The styrenic elastomer preferably has a rubber hardness in the range of 15 to 25. If the elastomer hardness is lower than 15, adhesion cannot be ensured even if an olefin elastomer is blended. On the other hand, if the elastomer hardness exceeds 25, the rubber hardness of the blend resin becomes too high, and it becomes difficult to obtain a sufficient soft feeling. Specific examples of styrenic elastomers include “Thermolast” (Cryburg), “Lavalon” (Mitsubishi Chemical), “Septon” (Kuraray), “Reostomer” (RIKEN Vinyl), “Tuftec” (Asahi Kasei), etc. However, “Septon” (Kuraray) is most preferred because of its light resistance, transparency and high adhesion.

  Moreover, the range of rubber hardness 60-80 is preferable, and the olefin type elastomer is so good that adhesiveness is enough. If it is too soft, pelletization becomes difficult, so it is preferable to have a rubber hardness of about 60. Specific examples of the olefin elastomer include “Miralastomer” (Mitsui Chemicals), “Thermo Run” (Mitsubishi Chemical), “Santoprene” (AES Japan) and the like.

2. Blend Ratio The blend ratio of styrene elastomer and olefin elastomer (styrene elastomer: olefin elastomer) is preferably in the range of 95 to 75: 5 to 25, and more preferably about 90:11 to 80:20. The rubber hardness after blending should be in the range of 20-25. If the ratio of the olefin elastomer is small, the toning material becomes insufficiently dispersed when used as a master batch, color unevenness is likely to occur, and stabilization of the adhesive quality in continuous production may be impaired. It becomes difficult to achieve the purpose. Conversely, when the ratio of the olefin elastomer is too high, the rubber hardness increases, which is not preferable.

3. Handle structure The grip portion of the brush handle is a multi-color molded product of at least two-color molding composed of a hard core portion constituting the base portion and a blend resin covering the base portion. In order to make use of the softness characteristics of the elastomer grip, it is desirable that the blend resin covering the hard core portion has a thickness of 1.2 mm or more. However, since the blend resin of styrene elastomer and olefin elastomer has a very high anti-slip effect on the surface compared to a single olefin elastomer, the effect is exhibited even if it is thinner than that. The coverage for covering the grip portion is preferably 10 to 100%. When the usability is taken into consideration, a higher coverage is better.

4). Surface processing It is preferable that the surface of the blended resin covering the hard core is subjected to a textured process. The rough surface roughness is preferably about 10 to 50 μm in terms of a natural texture. However, considering the texture processing to the mold, smooth mold separation from the molding mold, etc., about 10 to 30 μm is more preferable.

5. Molding method When molding a brush handle, first, a hard core part to be a skeleton is obtained by injection molding polypropylene or the like using a primary mold. Next, a styrene elastomer is used as a base resin, and a resin based on an olefin elastomer is used as a coloring masterbatch, and these are set in a resin supply hopper of an injection molding machine with a predetermined hardness and a predetermined ratio. Injection molding is performed so that a predetermined portion around the hard core is covered with a blend resin of a styrene elastomer and an olefin elastomer with a mold.

  The resin temperature during injection is preferably about 200 to 240 ° C. If it is too low, adhesion failure will occur, and if it is too high, burning will occur and the surface of the molded product will be damaged. In addition, the surface of the molded product is subjected to a graining process having a predetermined surface roughness. For smooth mold separation, it is better to give the mold a draft of several degrees. After molding, it is cooled and solidified, and then released to obtain a finished brush handle. Note that dehumidification and drying before molding is basically not necessary for the elastomer.

  A specific example when the present invention is applied to a toothbrush handle will be described below.

  In a primary mold, a handle base (total length 185 mm) composed of a head part having a flocking hole, a neck part, and a gripping core part is injection-molded with polypropylene (Sumitomo Chemical "WP638C"). Next, this primary molded handle base is loaded into a secondary mold, and a styrene elastomer (Kuraray “Septon KC342D”, rubber hardness 18) is used as a base resin pellet as an elastomer constituting a soft grip. Pellets made of olefin elastomer (Mitsubishi Chemical “Miralastomer 6030N”, rubber hardness 60) as base resin are mixed at a ratio of 90:10, set in a supply hopper of an injection molding machine, and then injection molded at a resin temperature of 240 ° C. Then, after cooling and solidification, it was taken out and used as a toothbrush handle.

  The blended resin of styrene elastomer and olefin elastomer has a rubber hardness after blending of 22 and is not only excellent in softness and high fit, but also very compatible with hard core polypropylene, so it is strong Adhered to a high quality toothbrush handle. In addition, the surface of the grip composed of blend resin is textured with a roughness of 25μm to suppress the stickiness peculiar to styrenic elastomers, and to make the toothbrush handle excellent in usability and resistant to slipping when wet. I was able to. Furthermore, since the elastomer material has high transparency, the design is also high.

  In a primary mold, a handle base (total length: 180 mm) composed of a head part having a flock hole, a neck part, and a gripping core part is injection-molded with polypropylene (Idemitsu Petrochemical “J700GP”). Next, this primary molded handle base is loaded into a secondary mold, and a styrene elastomer (Kuraray “Thermolast”, rubber hardness 20) is used as a base resin pellet as an elastomer constituting a soft grip. Pellets made of olefin elastomer (Mitsubishi Chemical “Thermo Run”, rubber hardness 60) as base resin are mixed at a ratio of 80:20, set in a supply hopper of an injection molding machine, and then injection molded at a resin temperature of 230 ° C. After cooling and solidification, it was taken out and used as a toothbrush handle.

  The blended resin of styrene elastomer and olefin elastomer has a rubber hardness of 25 after blending, and it is not only excellent in soft feeling and high fit, but also very compatible with polypropylene in the hard core, so it is strong Adhered to a high quality toothbrush handle. In addition, the surface of the grip made of blended resin is textured with a roughness of 30 μm to suppress the stickiness unique to styrene-based elastomers and become a toothbrush handle with excellent usability that is difficult to slip even when wet. It was. However, since the blend resin of Example 2 is opaque, it is not suitable for light coloring.

<Evaluation test>
A toothbrush handle made of the following materials was prototyped and evaluated for adhesion and usability.
Hard core: Polypropylene (Sumitomo Chemical "WP638C")
Soft material: Elastomer blend resin (1) and (2) below
(1) Styrenic elastomer: “Septon KC342D” (Kuraray),
Rubber hardness 18
(2) Olefin elastomer: “Miralastomer 6030N” (Mitsubishi
Chemical), rubber hardness 60

1. Adhesive evaluation test An adhesive evaluation test was performed on the toothbrush handle made of the above-described material. The results are shown in Table 1.
Evaluation method: Hard core part and soft material part of the toothbrush handle produced
Peeled off and confirmed adhesion at that time

  According to the above adhesive evaluation test, the blend ratio at which the entire soft material sufficiently adheres to the hard core portion without unevenness was 95: 5, which is near the middle between 100: 0 and 90:10. The rubber hardness at that time was 20 or more.

2. Usability Evaluation Test A toothbrush was produced by implanting a hair bundle into a head portion of a toothbrush handle made of the above-described material, and the usability as a toothbrush was evaluated. The results are shown in Table 2.
Evaluation method: Each panel 50 people use a toothbrush for 1 month,
Judgment was made by a 7-step absolute evaluation. Average value of the obtained evaluation values
Evaluation results were obtained.
Evaluation criteria: 7-step absolute evaluation
7: Very good, 6: Pretty good, 5: Good
4: Neither, 3: Somewhat bad, 2: Very bad,
1: Very bad

  According to the usability evaluation test, when the ratio of the styrene elastomer is large, the softness and the fit are increased, but stickiness is not preferable. On the other hand, if the ratio of the styrene-based elastomer is small, the stickiness is improved, but the softness and fit feeling are impaired. According to the comprehensive evaluation, the blend ratio with a high quality balance (absolute evaluation of 5 points or more) was in the range of 95: 5 to 75:25. The rubber hardness at that time was in the range of 20-25.

  According to the results of the adhesiveness and usability evaluation test, the blend ratio of the styrene elastomer and the olefin elastomer is desirably 95: 5 to 75:25, and the rubber hardness after blending is desirably 20 to 25.

  A typical example of the brush handle to which the present invention is applied is the above-described toothbrush handle, but the application target is not limited to this, and other brush handles such as a hair brush, a body brush, a hairdressing and cosmetic brush, The present invention is applicable to any brush handle provided with at least a head portion in which hair bundles or brushes are implanted and a grip portion for gripping and holding the brush by hand, such as a clothing brush.

Claims (4)

  A brush handle having a grip portion formed by coating a hard core portion with a soft material, wherein the soft material uses a blend resin of a styrene elastomer and an olefin elastomer.   The styrene elastomer has a rubber hardness of 15 to 25, and the olefin elastomer has a rubber hardness of 60 to 80. The blend ratio of these elastomers (styrene elastomer: olefin elastomer) is 95: 5. The brush handle according to claim 1, wherein the rubber hardness after blending is 20-25.   The brush handle according to claim 1 or 2, wherein the brush handle is a toothbrush handle having a head portion, a neck portion, and a grip portion.   In the method of injection-molding the brush handle according to any one of claims 1 to 3 using an injection molding machine, a styrene-based blend resin of a styrene-based elastomer and an olefin-based elastomer is molded around the hard core portion. A method for molding a brush handle, wherein an elastomer is used as a base resin in a natural manner, and an olefin-based elastomer is used as a base resin for a masterbatch together with a toning material.