JP2003025376A - Method for manufacturing toothbrush handle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a toothbrush handle having a multilayered structure excellent in appearance discriminability, functionality and quality without requiring much mold cost. SOLUTION: A single handle mold 4 is constituted so that a plurality of resin filling gates becoming a multiple core structure are provided to the end part of a cavity 1 assuming the shape of a handle. This handle mold 4 is used to successively fill the cavity 1 with a resin 7 so as to pierce the central part of the resin 6 charged in the cavity 1 immediately before from the outside gate 2, among a plurality of the resin filling gates 2 and 3 becoming the multiple core structure, before the resin 6 charged in the cavity 2 immediately before is cooled and solidified to obtain the toothbrush handle 5 constituted so that a plurality of the resins 6 and 7 are laminated in a core-sheath state along the longitudinal direction of the handle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a toothbrush handle having a multi-layer structure.

[0002]

2. Description of the Related Art In a method of manufacturing a toothbrush handle using a single mold, it is difficult to change the physical characteristics of the handle depending on the location without changing the shape of the handle because there is only one type of resin to be filled. Further, if a soft resin is used to soften the bending of the neck portion, the bristle transplanting strength of the hair bundle on the head portion becomes weak, which causes a problem in quality. On the other hand, when a hard resin is used, the bristle transplant strength of the hair bundle is secured, but there is a risk that the bending performance of the neck may be impaired. In particular, when the thickness of the head portion is thin, it is difficult to balance the bristle implant strength and the bending of the neck portion.

Conventionally, as a technique for differentiating the appearance and improving the functionality of a toothbrush handle, a secondary molding method using two kinds of resins and a molding method using three or more kinds of resins have been known. It is widely practiced to give a plurality of colors and to give a handle a non-slip function such as a rubber grip. However, this method requires as many molds as there are resins and colors to be used, and requires a great deal of cost. In addition, there is also known a method of improving appearance differentiation and functionality of a toothbrush handle by performing secondary molding or more using insert molding,
In the case of this method, the number of molding steps is increased by the number of molds, and the productivity is significantly reduced.

On the other hand, in Japanese Patent Laid-Open No. 2-71710,
A method of manufacturing a brush handle in which an outer body is integrally molded on a handle part by using injection molding of an insert method is shown, but this method is the most general two-color molding method A mold corresponding to that is required for molding, and a great mold cost is required. Further, since it is insert molding, cooling and handling time are required for each molding process, and there is a problem that productivity is poor.

Further, Japanese Unexamined Patent Publication No. 50-149751 discloses a method of simultaneously molding a plurality of color molded products with a single mold using a single injection molding machine having a plurality of units. However, in this molding method, the mold structure is a complicated slide type because it divides different resins, so it is expensive to manufacture the mold, and a lot of labor is required to manage the equipment during production. And Further, in a molded product having a long shaft structure such as a toothbrush handle, it is difficult to make a molded product in which a hard resin and a soft resin are layered inside and outside like a core-sheath.

Further, in Japanese Patent Laid-Open No. 2-139232, a hard resin such as polypropylene and a non-vulcanized thermoplastic elastomer are melt-bonded and integrated, and
Although a method of simultaneously obtaining a composite plastic molded product in the same mold without the need for insert molding is shown, in this method, after the first type of resin cools and solidifies in the mold, Since the resin is injected, there is a problem that it takes a long time to solidify by cooling. Also, if the adhesive interface is flat, it is possible to perform simultaneous molding using the same mold, but in the case of a three-dimensional adhesive interface, insert molding is required.
High cost.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a multilayer structure excellent in appearance distinction, functionality and quality without requiring a large die cost. It is an object of the present invention to provide a method for manufacturing a toothbrush handle capable of manufacturing the above toothbrush handle.

[0008]

In order to achieve the above object, a method of manufacturing a toothbrush handle according to a first aspect of the present invention is a method for filling a plurality of resins having a multi-core structure at the end of a cavity shaped like a handle. By using a single handle mold having a gate, the resin immediately before the resin is filled in at least immediately before the resin outside the plurality of resin filling gates having the multi-core structure in order from the outside. By sequentially filling other resin so as to penetrate the central part of
A toothbrush handle in which a plurality of resins are laminated in a core-sheath shape along the handle longitudinal direction is obtained.

The toothbrush handle manufacturing method according to a second aspect of the present invention uses a single handle mold having a single resin filling gate at the end of the handle-shaped cavity. A toothbrush in which a plurality of resins are laminated in a stripe shape along the longitudinal direction of the handle by sequentially filling the other resin at least immediately before the resin is cooled and solidified from one resin filling gate. It was designed to get a handle.

When the manufacturing method as described above is adopted, the physical characteristics can be changed without changing the shape of the handle, and the physical properties of each part of the toothbrush handle can be easily and complicatedly controlled. In addition, since a single mold can be used to perform multi-layer molding, it is possible to improve the appearance distinction and the functionality of the toothbrush handle without incurring a large mold cost. further,
Since simultaneous multicolor molding or simultaneous multilayer molding can be carried out using a single mold, it is possible to reduce the resin filling, cooling, and handling time required for each mold, which is required in ordinary secondary molding.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. In the first embodiment, as shown in (a), a soft resin filling gate having a cavity 1 shaped in a predetermined handle shape and having an inner-outer double core structure at the rear end of the die. 2 and a single handle mold 4 having a hard resin filling gate 3 and two injection molding machines (not shown), a core-sheath shape is formed along the handle longitudinal direction as shown in (f). 2 shows an example of manufacturing the toothbrush handle 5 having the two-layer structure described above. Although not shown, a soft resin injection molding machine is connected to the soft resin filling gate 2, and a hard resin injection molding machine is connected to the hard resin filling gate 3. Hereinafter, the manufacturing method will be described with reference to the drawings.

(I) Filling of the soft resin (FIG. 1 (b)) In the same molding cycle, first, the soft resin 6 is injected into the cavity 1 from the injection molding machine (not shown) through the outer soft resin filling gate 2. And is filled toward the tip side of the handle cavity 1a to the extent that a predetermined space is formed.

As the soft resin 6, various resins such as polyolefin-based TPE (TPE: thermoplastic elastomer), polystyrene-based TPE, polyurethane-based TPE, polyester-based TPE, natural rubber-based TPE, and fluorine-based TPE are used. However, considering the physical properties required for the toothbrush handle, the price, etc., the polyolefin-based TPE is most preferable.

(Ii) Filling with hard resin (FIG. 1 (c)-
(E)) Next, in the molten state in which the filled soft resin has not yet been cooled and solidified, the inner hard resin filling gate 3
Through the injection molding machine, the hard resin 7 is injected into the cavity 1. The injected hard resin 7 has a viscosity,
By controlling the injection pressure, injection speed, injection amount, injection time, etc., as shown in FIGS.
The central portion of the soft resin 6 in a molten state is axially penetrated, and is injected into the head cavity 1c through the handle cavity 1a and the neck cavity 1b. Then, when the hard resin 7 fills the inside of the head cavity 1c, the filling of the hard resin 7 is completed.

As the hard resin 7, various resins such as polypropylene, polyester, polyamide and polyarylate can be used, but polypropylene is most preferable in consideration of the physical properties required for the toothbrush handle and the price.

(Iii) Removal of finished product (FIG. 1 (f)) After the filled soft resin 6 and hard resin 7 are cooled and solidified, the mold 1 is opened and the molded product is taken out. As a result,
As shown in (f), the entire head portion 8 is made of hard resin, and the neck 9 and the handle portion 10 have a hard resin running axially in the center thereof and an outer side covered with a soft resin. Toothbrush handle 5 with a split core-sheath structure
Is obtained.

In the case of the toothbrush handle 4 having the above-mentioned structure, the head part 8 for implanting the brush is hard, and the neck part 9 and the handle part 10 are moderately smooth. Further, since the molding is performed using a single mold, the molding time can be reduced to half or less as compared with the ordinary secondary molding. Also, the die cost can be reduced to about half that of ordinary secondary molding. Furthermore, the appearance of the toothbrush handle can be improved by changing the color of the resin used.

FIG. 2 shows a second embodiment of the present invention. In the second embodiment, as shown in FIG.
Using a single handle mold 24 with two resin filling gates 22 and two injection molding machines (not shown), (b)
This is an example of manufacturing a toothbrush handle 25 having a striped pattern as shown in FIG.

(I) Filling of the first resin (FIG. 2 (a)) In the same molding cycle, first, the resin filling gate 22 is connected to the first injection molding machine and the resin filling gate 22 is connected. The first resin 26 having a predetermined color is injected into the cavity 21 from. Then, this first resin 2
By controlling the viscosity of 6, the injection pressure, the injection speed, the injection amount, the injection time, etc., the first resin 26 is sent to the tip of the head cavity as shown in FIG. The filling of the first resin 26 is completed at the time of filling.

(Ii) Filling of second resin (FIG. 2 (a)) Next, in a molten state in which the filled first resin 26 has not yet been cooled and solidified, the resin filling gate 22 is secondly injected. After connecting to the molding machine, a second resin 27 of a color different from the first resin 6 is injected from the second injection molding machine into the cavity 21. And this second resin 2
By controlling the viscosity, the injection pressure, the injection speed, the injection amount, the injection time, and the like of No. 7, as shown in FIG. The first resin 26 is fed to the position of the first resin 26 to be laminated, and when the predetermined amount is filled, the filling of the second resin 27 is completed.

By repeating the resin filling of the above (i) and (ii) sequentially, as shown in FIG.
6 and the second resin 27 are alternately laminated in a stripe shape along the longitudinal direction of the handle. And Javity 21
The filling of the first and second resins is completed when the first and second resins 26 and 27 are completely filled in the space.

(Iii) Taking out the finished product (FIG. 2 (b)) After the first resin 26 and the second resin 27 laminated in a stripe shape are cooled and solidified, the mold 1 is opened and the molded product is taken out. . As a result, the multi-layered toothbrush handle 25 having a striped pattern as shown in FIG. 2B is obtained.

Also in the case of the second embodiment, the head portion is hard and the handle portion and the neck portion are not suitable by changing the kind and combination of the first and second resins 26 and 27 and the laminated thickness. You can give a compliant. Further, since the molding is performed using a single mold, the molding time can be reduced to half or less as compared with the ordinary secondary molding. Also, the die cost can be reduced to about half that of ordinary secondary molding. Furthermore, the appearance of the toothbrush handle can be improved by changing the color of the resin used.

If three or more molding machines are prepared and resins of different colors are supplied to the respective molding machines, it is possible to control the injection amount and injection time of each resin by 3 or more.
A multicolor handle of more than one color can be easily obtained. Further, when it is desired to apply gradation to the boundary of the resin as the outer appearance of the handle, it is sufficient to use a mold without a gate in the resin flow path and to fill the resin only by switching the injection of each molding machine.

[0025]

As described above, according to the method for manufacturing a toothbrush handle of the present invention, the following excellent effects can be exhibited. (1) A highly functional toothbrush handle can be manufactured. (2) It is possible to manufacture a toothbrush handle having a high appearance distinction. (3) The three-dimensional and planar adhesiveness between different resins in the toothbrush handle can be improved. (4) It is possible to reduce the die cost. (5) Since it can be manufactured using a single mold, productivity can be improved. (6) The physical characteristics of the toothbrush handle can be changed without changing the handle shape. (7) Secondary molding or higher molding productivity can be improved.

[Brief description of drawings]

1A to 1F are schematic process explanatory views of a first embodiment of a method of the present invention.

2 (a) and 2 (b) are schematic process explanatory views of a second embodiment of the method of the present invention.

[Explanation of symbols]

1 cavity 1a Handle cavity 1b neck cavity 1c Head cavity 2 Soft resin filling gate 3 Hard resin filling gate 4 mold 5 toothbrush handle 6 Soft resin 7 hard resin 8 head 9 neck 10 handle 21 cavity 22 Resin filling gate 24 mold 25 toothbrush handle 26 First resin 27 Second resin

Claims (2)

[Claims] 1. A single handle mold having a plurality of resin filling gates having a multiple core structure at the end of a cavity shaped like a handle, and a plurality of resin fillings having the multiple core structure. In order from the outer gate of the gate for use, at least before the resin filled immediately before that is cooled and solidified, another resin is sequentially filled so as to penetrate through the central portion of the resin immediately before, so that a plurality of resins can be formed. A method for manufacturing a toothbrush handle, comprising obtaining a toothbrush handle laminated in a core-sheath shape along a handle longitudinal direction. 2. A single handle mold having a single resin filling gate at the end of a handle-shaped cavity is used, and at least immediately before the single resin filling gate. Manufacture of a toothbrush handle characterized by obtaining a toothbrush handle in which a plurality of resins are laminated in a stripe shape along the handle longitudinal direction by sequentially filling other resins before the filled resin is cooled and solidified. Method.