JPH1014664A - Brush manufacturing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] When manufacturing a brush in which a hair bundle for a handle is integrally planted, there is no entry of the hair bundle for the handle molding material to prevent the generation of burrs, and the hair is well furnished and the hair is planted. Strength is also greatly improved. SOLUTION: In a method for manufacturing a brush in which a hair bundle is integrally implanted in a handle, a total cross-sectional area of a plurality of hairs introduced into the mold is determined with respect to a cross-sectional area of a hair bundle holding hole of a mold. Filling to a ratio of 65-99% and injection molding ensures insert molding of the hair bundle, has a simple mold structure, does not require a special mold system, and has less flocking. It is possible to produce a brush having a high strength and a bristle-implanted state, and having improved quality and appearance quality.

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 brush such as a toothbrush, a hairbrush, a body brush or a cleaning brush, and more particularly to a method for forming and integrating a hair bundle and a handle.

[0002]

2. Description of the Related Art Recently, in the case of toothbrushes or the like, instead of a brush in which a bristle bundle is fixed to a bristle hole in a handle using a metal wire, it is necessary to increase the flocking density or to increase the versatility of the flocking shape. It has been proposed to integrate the handle with a hair bundle when the handle is formed of a synthetic resin without using a metal wire. Conventionally, as a method not using such a metal wire, a method of fixing a hair bundle to a handle head portion by heat fusion (Japanese Patent Application Nos. 60-132097 and 60-167).
No. 30, Japanese Patent Application No. 1-215132, etc.) or a method of introducing a hair bundle into a mold, injecting a handle resin material, and integrally molding (insert molding) (for example, Japanese Patent Application No. 59-159132).
240403, Japanese Patent Application No. 61-68897, Japanese Patent Application No. 6
No. 3-501377).

[0003]

The problem of this conventional manufacturing method is that, for example, in Japanese Patent Application No. 59-240403, the end of the hair bundle holding hole on the cavity side in the mold is melted and enlarged. The feature is to prevent the occurrence of "burrs" by closing the part, but in this method the molten enlarged part is located directly below the handle flocking surface, so sufficient flocking strength (strength to pull out hair from the molded body) There was a problem that could not be maintained. In the case of Japanese Patent Application Nos. 61-68897 and 63-501377, by providing a sleeve on the extension of the hair bundle holding hole, the hair can be implanted at a distance from the implanted surface of the handle. Although strength can be ensured, there is a problem that the mold structure becomes complicated and productivity cannot be increased.

Further, by forming a fusion mass at the end of the conventional hair bundle, and then injecting the molding material into a mold,
In the in-mold method of molding a flocked member or a brush, in order to increase the flocked strength (the difficulty of pulling out hair from the molded body), the molding material is inserted into the mold while the hair bundle fusion mass is deeply inserted into the mold. However, there is a drawback in that the molding material flows out of the through-hole due to the pressure at the time of the injection molding, and burrs which fly out of the flocking surface are generated. This burr is a part of the molding material exuding from the gap between the bristle bundle and the through hole, but it increases the density of the bristle bundle in the through hole and adjusts the molding conditions such as injection pressure and injection speed. By doing so, it is possible to reduce the incidence and size of burrs to some extent, but there is a problem that burrs that protrude from the flocked surface impair the product appearance and that large burrs may damage the oral cavity. there were. SUMMARY OF THE INVENTION The present invention seeks to eliminate these conventional disadvantages easily, and has a simple mold structure for producing a high-strength brush in-mould, without the need for a special mold system. A brush that is high in strength, prevents rotation and deformation of the hair bundle during injection molding, provides a bristle-implanted state, and improves the quality and appearance quality of burrs that are less likely to emerge above the flocked surface. To obtain a production method.

[0005]

According to the present invention, a hair bundle made of a thermoplastic synthetic resin is introduced into a plurality of hair bundle insertion holes provided in a mold to project one end of the hair bundle. Then, the protruding end is formed into a fusion mass having a cross section larger than the cross section of the holding hole by the heating means, and after the fusion mass is positioned in the cavity of the handle molding die, the thermoplastic synthetic resin molding material is introduced. In the method of manufacturing a brush in which a hair bundle is integrally implanted in a handle, a ratio of a total cross-sectional area of a plurality of hairs introduced into a hair bundle holding hole of the mold to a cross-sectional area of the hair bundle holding hole of the mold is provided. Is filled so as to be 65 to 99% and injection molded to reduce the generation of burrs and to provide a brush having high flocking strength and excellent appearance quality.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this method of manufacturing a brush, a fusion lump at one end of a bristle bundle is positioned in an inner space of a handle molding die, and a resin molding material is injected into the mold to form a bristle bundle. And the handle are integrally molded so that the ratio of the total cross-sectional area of the plurality of hairs introduced therein to the cross-sectional area of the hair bundle holding hole in the mold is 65 to 99%. Injection molding allows the hair bundle to be held on the handle without any gaps in the hair bundle, eliminating the need for a special mold system, generating less burrs, having a higher hair transplant strength, and having a good hair growth. A good quality brush with little variation can be obtained by preventing the rotation and deformation of the hair bundle, and the hair bundle in the hair bundle holding hole can be moved smoothly and the production efficiency can be improved. Can be improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a perspective view of a handle forming die 10 or a hair bundle inserting holding hole 11 provided in a hair bundle inserting die. The bristle bundle 1 is introduced, and one end of the bristle bundle is aligned and protruded by the receiving plate 14,
Projecting end portion hot plate or hot air by the heat source 12 _1, a heating means 12 such as an infrared, fused into a fused mass 2 having a larger cross-section than the cross section of the retaining hole 11, the handle mold the fused mass 2 10 , The mold is closed, and the molten molding material is introduced.
When the brush 4 in which the bristle bundle 1 is integrally implanted in the handle 3 is formed by shaping the handle by curing the molding material, the fused lump of the bristle bundle 1 is inserted into the cavity 13 in the mold 10 for forming the handle. 2, the handle forming dies 10, 10 are closed, and then the cavity 13 in the mold is formed.
Injection molding is carried out at a temperature at which the molten molding material introduced into the inside is lower than the softening point of the resin material of the hair bundle. In addition, by inserting hair at a high filling rate into the hair bundle holding hole provided in the injection molding die of the brush, the gap between the inner surface (inner wall) of the hair bundle holding hole and the outer periphery of the hair bundle can be reduced. Therefore, it is possible to prevent “burrs” generated when the injection molding resin (for example, polypropylene or the like) filled in the handle molding cavity enters the above-described space, and to fuse the molten enlarged portion deep into the handle resin. because can hold 2, wherein the certain fused mass 2 as a low-quality good brush to a high flocking intensity variation held in the molding material to the molding material is embedded fused mass 2 and tufts root portion 1 ₁ in the cavity 13 .

In this case, when the hair is inserted into the hair bundle holding hole in the handle molding injection molding die, the hair is filled into the hair bundle holding hole of an arbitrary shape and size with respect to the cross-sectional area thereof. The ratio of the total cross-sectional area of the arbitrary number of hairs is 65% to 85%, preferably 70% to 80% in the case of the hair having a circular cross section,
By setting the number of hairs or the size of the holding hole according to various hair diameters so as to be 70% to 99%, preferably 75% to 85% in the case of hair for polygonal cross section, for handle Prevent `` burrs '' that occur when the injection molding resin enters between the holding hole and the hair bundle, and close the cavity side end of the hair bundle holding hole cavity with the molten enlarged part, or place a sleeve in the hair bundle holding hole. Since it is not necessary to provide the molded product, the molded product can have good appearance and sufficient flocking strength. Furthermore, since the hair filling rate is appropriate, it is possible to improve hairiness, prevent hair bundle rotation and deformation of the hair bundle cross-sectional shape, and move (insert) the hair bundle in the hair bundle holding hole. Etc.) can be maintained smoothly between the hair bundle holding hole and the hair bundle.

If the filling rate is too high, the hair bundles may be jammed in the hair bundle transfer process (feeding, squeezing, etc.), or the length of the hairs in the hair bundles may not be uniform. Hair that does not melt when the part is melted is formed, causing hair loss. Also, if the filling rate is lower than this, burrs are likely to be generated, so care should be taken. That is, by inserting the hair bundle into the holding hole at this filling rate, the hair growth (the hair standing vertically from the root of the hair bundle) is improved, the appearance of the molded product can be improved, and the hair bundle can be improved. It is also possible to prevent the hair bundle from rotating due to the pressure of the injection molding during the injection of the handle resin after melting, and to prevent the hair bundle profile from being displaced (rotated) before the injection molding. In addition, the deformation of the hair bundle cross-sectional shape in the holding hole can be minimized, and a clearance can be provided between the inner surface of the hair bundle holding hole and the outer periphery of the hair bundle. The bundle can be smoothly inserted into the holding hole, and unreasonable stress is not applied in the longitudinal direction of the bristle bundle, so that the bristle bundle feeding failure can be prevented, and the production efficiency can be greatly improved.

The temperature of a molten molding material injected into the cavity 13 of the molding die 10 for molding the handle,
For example, the temperature at the tip of the injection molding machine nozzle is generally nylon 6, nylon 6-1 used as brush hair.
When it is 0, 6-12 or PBT, the softening point is about 215
Molding at ~ 225 ° C or lower, to prevent deformation or melting of the bristle bundle enlargement part, that is, to improve and stabilize the flocking strength of the product, and to the molded product surface of the bristle bundle enlargement part Can also be prevented from being exposed. Further, as the handle molding resin, PP, AS, ABS, PMMA, PA, PO
M, PBT, GPPS, PE, U polymer, PET, P
C, PC + PET, PC + PET + PBT, etc. are used, and it is preferable to select and mold an injection molding temperature of 150 to 225 ° C., preferably 190 to 220 ° C.
It is preferable in production to use a resin having a high fluidity grade of the molding resin.

A plunger 15 is slidably inserted into each of the plurality of bristle bundle holding holes 11 provided in the handle forming die 10, each bristle bundle 1 is stopped at a predetermined position, and the fused mass 2 is moved into the cavity 13. It is fixed and supported inside. The hair bundle holding hole 11 has a diameter larger than the diameter of the plunger 15 so that the hair bundle can be supplied easily. When the hair bundle is introduced, the ratio of the cross-sectional area of the hair bundle to the cross-sectional area of the hair bundle holding hole In consideration of stabilizing the (hair filling rate), the injection molding resin is molded so as to prevent the resin from entering between the hair bundle and the holding hole of the mold so as to eliminate burrs. That is, as shown in FIG. 4, the bristle filling rate and the burr when molding are performed under molding conditions (such as a high injection pressure) where burr is likely to occur when the bristle diameter is 0.20 mm and under normal molding conditions. Looking at the relationship with the incidence rate, there is an inverse relationship between the hair filling rate and the burr occurrence rate. Note that the burr generation rate slightly varies depending on other molding conditions, hair diameters for use, hair bundle holding holes, and the material of the molding resin.

Furthermore the molding material filled into the cavity 13, Content crowded around the molding material around the hair bundle root portion 1 ₁ in softness that can move a fused mass 2 of use tufts 1 before solidification When the hair bundle 1 is pushed into the holding hole 11 by the plunger 15 and the hair bundle fusion mass 2 is inserted into the vicinity of the center of the molded body, for example, the hair bundle fusion mass 2 and the root portion of the hair bundle are selected. because it reliably hold the 1 ₁ at molding material, sufficient flocking strength can not be obtained burr even less,
In addition, it is also possible to make hair transplanting with good hairiness.

In the present invention, the following characteristic method is also included. A method of manufacturing a brush in which a hair bundle is fixed at a predetermined position in a cavity by a hair bundle insertion plunger in each of the hair bundle holding holes, and a molding material is filled around the root of the hair bundle. The diameter of the opening end of the hair bundle holding hole is sequentially enlarged and formed in a conical space, or using a mold having an annular rib,
A method of manufacturing a brush in which a conical annular rib portion or a concave portion is formed around a root portion of a bristle bundle and the molding material is filled.

[0014]

According to the present invention, a bristle bundle made of a thermoplastic synthetic resin is introduced into a plurality of bristle bundle holding holes provided in a mold, and one end of the bristle bundle is protruded. A handle is formed by forming an end into a fusion mass having a cross section larger than the cross section of the holding hole by a heating means, positioning the fusion mass in a cavity of a handle molding die, and then introducing a thermoplastic synthetic resin molding material. In a method of manufacturing a brush having a hair bundle integrally implanted therein, the ratio of the total cross-sectional area of a plurality of hairs introduced therein to the cross-sectional area of the hair bundle holding hole of the mold is 65 to 99. %, And injection molding is performed to produce a brush in which the hair bundle is integrally implanted with the handle, so that the injection molding resin for the handle enters between the holding hole and the hair bundle and is generated. Burr prevention and hair bundle holding hole cavity Closing the end in a molten enlargement section, or for use tuft holding hole is not necessary to provide a sleeve, brought maintained good enough flocking strength appearance of the molded article. Furthermore, since the hair filling rate is appropriate, it is possible to improve hairiness, prevent hair bundle rotation and deformation of the hair bundle cross-sectional shape, and move (insert) the hair bundle in the hair bundle holding hole. Etc.) can be performed smoothly, and the strength of molded products can be improved, and the quality and appearance can be improved. As a result, sufficient flocking strength can be obtained, and good quality, high appearance quality and high reliability can be obtained. In addition, since the molding material can be injected with the gap between the fusion mass and the tip of the hair bundle holding hole being opened, the productivity can be greatly improved.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process explanatory view of a manufacturing method according to an embodiment of the present invention, in which (a) is a hair bundle insertion step, (b) is a fusion lump forming step, (c) is a step immediately before injection molding, and (d) is a hair bundle pushing-in step. Step (e) shows a release step.

FIG. 2 is an enlarged vertical sectional view of a part of a molding process of the example of FIG.

FIG. 3 is a cross-sectional view of the example of FIG.

FIG. 4 is a graph showing the relationship between the hair filling rate and the burr generation rate of the product of the present invention.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 hair bundle 2 fused mass 3 handle 4 brush 10 handle forming die 11 hair bundle holding hole 11 ₁ open end 12 heating means 12 ₁ heat source 13 cavity 14 receiving plate 15 plunger

Claims (1)

[Claims] A hair bundle made of a thermoplastic synthetic resin is introduced into a plurality of hair bundle insertion holes provided in a mold, one end of the hair bundle is projected, and the protruding end is heated. Means for forming a fusion mass having a cross section larger than the cross section of the holding hole, positioning the fusion mass in the cavity of the handle molding die, and then introducing a thermoplastic synthetic resin molding material to the hair bundle for the handle. In the method of manufacturing a brush in which the hairs are integrally planted, the ratio of the total cross-sectional area of the plurality of hairs introduced therein to the cross-sectional area of the hair bundle holding hole of the mold is 65 to 65.
A method for producing a brush, characterized by filling the mixture to 99% and injection molding.