JP2018033510A - Toothbrush manufacturing method - Google Patents

Abstract

To provide a toothbrush manufacturing method capable of satisfying both necessary mechanical properties / strength quality and transparency. A head portion 2 having a flocked surface 20 on the front end side, a handle portion 7 disposed on the rear end side from the head portion and including a gripping portion 8, and disposed between the flocked surface and the handle portion. And a neck portion 4 that is deformed by an external force applied to the portion. Including a step of filling a resin material through a gate portion arranged at a predetermined position. The gate part is arranged on the tip side from the grip part. [Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a toothbrush.

  In the toothbrush, the head portion may be thinned in order to improve operability and allow the oral cavity to be thoroughly wiped. In Patent Document 1, the head portion is formed of a polyacetal resin or polybutylene terephthalate resin, and the thickness of the head portion is set to 2 mm or more and less than 3 mm, thereby improving the oral operability and sufficient brush holding strength and A toothbrush that maintains the bending strength of the head portion is disclosed.

JP 2011-004852 A

  When the handle body is made transparent or semi-transparent in order to improve the appearance, an amorphous resin material is often used. However, the amorphous resin material is excellent in transparency but inferior in mechanical properties and strength quality compared to the crystalline resin material. Therefore, the specifications required for the above-mentioned thin head portion and ultra-fine neck portion are required. It was difficult to meet.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide a method for manufacturing a toothbrush that can achieve both necessary mechanical characteristics / strength quality and transparency.

  According to the first aspect of the present invention, a head portion having a flocked surface on the front end side, a handle portion disposed on the rear end side from the head portion and including a gripping portion, and the flocked surface and the handle portion. A method of manufacturing a toothbrush, comprising: a step of filling a resin material through a gate portion disposed at a predetermined position, the neck portion being disposed between and a neck portion that is deformed by an external force applied to the head portion. There is provided a method for manufacturing a toothbrush, wherein a portion is arranged closer to the tip side than the grip portion.

  Moreover, in the manufacturing method of the toothbrush which concerns on the one aspect | mode of the said invention, the said gate part is arrange | positioned at the said head part, It is characterized by the above-mentioned.

  In the method for manufacturing a toothbrush according to one aspect of the present invention, a concave portion is disposed in a part of the head portion, and the gate portion is disposed in the concave portion.

  The toothbrush manufacturing method according to one embodiment of the present invention includes a step of covering at least the gate portion with a second resin material.

  In the method for manufacturing a toothbrush according to one embodiment of the present invention, the resin material is a hard resin, and the second resin material is a soft resin.

  Moreover, in the manufacturing method of the toothbrush which concerns on the one aspect | mode of the said invention, the 1st part containing the connection part arrange | positioned rather than the said head part, the said neck part, and the said neck part is shape | molded by filling with the said resin material. And forming a second part including the handle part connected to the first part by the connecting part by filling the resin material using the molded first part, and The gate part in one part is arranged in the connecting part.

  In the method for manufacturing a toothbrush according to one embodiment of the present invention, the resin material is amorphous.

  According to the present invention, it is possible to manufacture a toothbrush that can achieve both necessary mechanical properties / strength quality and transparency.

(A) of the toothbrush 1 which concerns on 1st Embodiment is a top view, (b) is a front view. 4 is an enlarged partial plan view of a head unit 2. FIG. 4 is an enlarged partial cross-sectional view of a head unit 2. FIG. FIG. 4 is a view showing a molded product in which a gate portion G extends in a length direction from the tip of a head portion 2. It is a figure for demonstrating the evaluation method of a bending elastic modulus. It is the fragmentary top view which expanded the head part 2 of the toothbrush 1 which concerns on 2nd Embodiment. 4 is an enlarged partial cross-sectional view of the head unit 2. FIG. It is a figure which shows the molded product from which the gate part G extends in the length direction from the front-end | tip of the head part 2 in 2nd Embodiment. (A) of the toothbrush 1 which concerns on 3rd Embodiment is a top view, (b) is a front view.

Hereinafter, an embodiment of a method for producing a toothbrush of the present invention will be described with reference to FIGS. 1 to 9.
The following embodiments show one aspect of the present invention and do not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each configuration easy to understand, the actual structure is different from the scale and number of each structure.

[First Embodiment]
Fig.1 (a) is a top view of the toothbrush 1 which concerns on 1st Embodiment. FIG. 1B is a front view of the toothbrush 1.
A toothbrush 1 shown in FIG. 1 includes a head portion 2 having a substantially square shape in plan view, a neck portion 4 extending to the head portion 2, and a handle portion 7 extending to the neck portion 4 (hereinafter, the head portion 2 and the neck portion). 4 and the handle portion 7 are also referred to as a handle body 10). The head portion 2 is provided with a flocked portion (not shown) and a covering portion 30. The handle portion 7 is provided with a soft elastic portion 6.

The handle body 10 is integrally formed in a long shape as a whole. For example, the handle body 10 is obtained by injection molding using a resin material as a material.
The handle body 10 excluding the soft elastic portion 6 and the covering portion 30 is formed of an amorphous hard resin that is transparent or translucent. Examples of the amorphous hard resin include polystyrene resin (PS), acrylonitrile butadiene styrene resin (ABS), polyarylate resin, polycarbonate resin, acrylonitrile styrene resin (AS), and polyester resin.
As for said resin, 1 type may be used independently and 2 or more types may be used in combination.

  The bending elastic modulus of the material of the handle body 10 is preferably 1200 to 3000 MPa, and more preferably 1500 to 3000 MPa. If the flexural modulus of the handle body material is in the above range, the amount of deflection of the head can be set to an appropriate value, improving the oral cleaning power and operability, and improving the user's feeling of use. It leads to. The length of the handle body 10 can be determined in consideration of operability and the like, for example, 150 to 200 mm.

The head portion 2 has a substantially rectangular flat plate shape in which the length direction of the handle body 10 is long, and four apexes are cut off by a curve in plan view. A plurality of flocking holes 22 are formed on one surface (flocking surface 20) of the head portion 2. A hair bundle in which hairs are bundled is planted in the flock hole 22 to form a flocked portion composed of a plurality of hair bundles.
In this specification, the direction parallel to the flocked surface 20 and orthogonal to the length direction of the handle body 10 is defined as the width, and the direction orthogonal to the flocked surface 20 is defined as the thickness. In addition, the side where the flocked surface 20 faces is the front surface, and the side opposite to the side where the flocked surface 20 faces is the back surface.

  In plan view, the head portion 2 expands in the width direction from the tip toward the neck portion 4, then extends in the same width, then narrows in the width direction, and reaches the boundary P <b> 1 with the neck portion 4. In the present embodiment, the boundary P1 is the end point of a curve forming a corner cut from the neck portion 4 in the plan view shape of the head portion 2 (that is, a position where the bending direction of the curve forming the corner cut changes (inflection). Point)).

The size of the head portion 2 can be determined in consideration of the operability in the oral cavity.
If the maximum width of the head part 2 is too large, the operability in the oral cavity will be reduced, and if it is too small, the number of hair bundles to be implanted will be too small and the cleaning power will be easily impaired. For this reason, a width | variety shall be 5-13 mm, for example.
The thickness of the head part 2 is preferably 2.0 to 4.0 mm, more preferably 2.0 to 3.5 mm, and even more preferably 2.5 to 3.2 mm. When the thickness of the head part 2 is equal to or more than the lower limit value, it is easy to suppress the strength of the head part 2 from being lowered, and durability is improved. Furthermore, it becomes easy to form the flock holes 22 in the thickness direction, and it becomes easy to firmly plant the hair bundles in the flock holes 22 and to prevent the hair bundles from coming out. Moreover, the operativity in the oral cavity of the toothbrush 1 is improved more as the thickness of the head part 2 is below the said upper limit. Furthermore, the hair can reach all corners of the oral cavity such as the back of the back teeth, and the effect of removing dirt in the oral cavity is further enhanced.
In addition, when the thickness of the head part 2 is not constant, the thickness of the head part 2 means the minimum thickness of the head part 2.
If the length of the head part 2 is too long, the operability in the oral cavity is liable to be impaired, and if it is too short, the number of hair bundles to be implanted becomes too small and the cleaning effect is liable to be impaired. For this reason, the length of the head part 2 is appropriately determined within a range of 10 to 40 mm, for example.

  FIG. 2 is an enlarged partial plan view of the head unit 2. FIG. 3 is an enlarged partial cross-sectional view of the head unit 2. In addition, illustration of the flock hole 22 is abbreviate | omitted in FIG. A gate portion G is disposed in the head portion 2 in the present embodiment. The gate portion G is disposed on the side surface 2 a on the distal end side in the head portion 2.

  The gate portion G is a region that is filled with a molten resin material when the handle body 10 is injection-molded (injection molding). About the molded product which cooled and hardened the resin material with which it filled, since the gate part G protrudes from the handle body 10, it is cut | disconnected and removed by a post process. The gate mark after cutting is shown in the gate portion G in FIGS. As an example, the position on the back surface side of the gate portion G in the thickness direction is formed at the position of the parting line PL.

  The covering portion 30 includes a side portion 30 a that covers the side surface 2 a of the head portion 2 and a bottom portion 30 b that covers a part of the back surface 2 b of the head portion 2. The covering portion 30 is made of a soft resin. As the soft resin, for example, those having a Shore hardness A of 90 or less are preferable, and those having a Shore hardness A of 50 to 80 are more preferable. Examples of the soft resin include elastomers (for example, olefin elastomers, styrene elastomers, polyester elastomers, polyurethane thermoplastic elastomers, etc.) and silicone. The thickness of the side portion 30a is formed larger than the protruding amount of the gate mark in the gate part G, and covers the gate mark. A substantially arc-shaped curved surface is formed at the edges of the side portion 30a and the bottom portion 30b, and the touch feeling is soft even when the head portion 2 is inserted into the oral cavity.

  The soft elastic portion 6 is provided substantially flush with the handle portion 7 on each of the front surface side and the back surface side of the handle portion 7. The soft elastic part 6 is arranged on the rear end side from the boundary P2 (details will be described later) with the neck part 4. The soft elastic portion 6 is disposed in the grip portion 8 located on the rear end side of the predetermined distance from the boundary P2 that is the maximum width in the handle portion 7. As an example, the soft elastic portions 6 provided on the front surface side and the back surface side are connected via a connection portion (not shown) embedded in the handle portion 7. The soft elastic part 6 is made of a soft resin. As the soft resin, for example, the same resin as that of the covering portion 30 described above is used.

The shape of the flocking hole 22 is not particularly limited, and examples thereof include a circle such as a perfect circle or an ellipse, and a polygon such as a triangle or a rectangle.
The quantity of the flock hole 22 is not specifically limited, For example, you may be 10-60.
The diameter of the flock hole 22 is determined according to the desired thickness of the hair bundle, and is, for example, 1 to 3 mm.
The arrangement pattern of the flock holes 22 is not particularly limited, and may be any arrangement pattern such as a so-called grid pattern or zigzag pattern.

As the hair constituting the hair bundle, the hair whose diameter gradually decreases toward the hair tip (tapered hair), the hair whose outer diameter is substantially the same except for the rounded portion of the hair tip (straight hair), Examples include hair for which the hair tip is in the shape of a spatula, a sphere, a tip crack, or the like.
As the hair, tapered hair is preferable. By making the bristles into tapered hairs, the effect of removing dirt such as periodontal pockets can be enhanced. Furthermore, the massage effect of gingiva is enhanced and the feeling of use is further improved.

Examples of the hair material include polyamide such as 6-12 nylon and 6-10 nylon, PET, PBT, polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), and the like. Examples thereof include synthetic resin materials such as polyolefins such as polyester and polypropylene, olefin elastomers, and styrene elastomers. These resin materials may be used individually by 1 type, and may be used in combination of 2 or more type.
Further, the bristle may have a multi-core structure having a core part and at least one or more sheath parts provided outside the core part.

  The cross-sectional shape of the bristles is preferably a perfect circle, but is not necessarily limited to a true circle, and can be any shape depending on the intended use of the toothbrush 1. For example, an ellipse, a polygon (for example, a triangle, a quadrangle, a pentagon, a hexagon, etc.), an irregular shape (for example, a star shape, a three-leaf clover shape, a four-leaf clover shape, etc.) can be used.

The thickness of each hair is not particularly limited. For example, when the cross section is a true circle, 4 to 8 mil (1 mil = 1/1000 inch = 0.025 mm) is preferable. If it is more than the lower limit, the self-supporting property is improved and the cleaning property is higher, and if it is not more than the upper limit, the fluff of the hair bundle 11 becomes moderate and the contact feeling becomes better.
The hairs constituting the hair bundle 11 may all have the same thickness, or two or more different types of hairs may be combined.

  The hair length of the hair is preferably 8 mm to 15 mm for adults and 6 mm to 12 mm for children, for example. In addition, from the viewpoint of usability in the oral cavity and usability, it is preferable to shorten the hair length of the hair as the diameter of the hair selected is smaller. Further, a plurality of hairs having different thicknesses may be used in combination depending on purposes such as a feeling of use, a feeling of cleaning, a cleaning effect, and durability.

The neck portion 4 connects the head portion 2 and the handle portion 7.
In the present embodiment, the neck portion 4 extends from the boundary P1 toward the handle portion 7 with substantially the same diameter, and then expands to reach the boundary P2 with the handle portion 7. The boundary P2 is an end point of diameter expansion of the neck portion 4 (that is, a position at which a bending direction of a curve forming both ends of a straight line forming both edges of the widened portion or a curved line forming both edges of the widening portion changes in a plan view) (Inflection point)).

The width of the neck portion 4 is preferably 3.0 to 4.5 mm, and more preferably 3.0 to 4.2 mm. When the width of the neck portion 4 is equal to or greater than the lower limit value, it is easy to suppress the strength of the neck portion 4 from being lowered, and the durability of the toothbrush 1 is enhanced. Furthermore, the toothbrush 1 does not become too soft, and a good feeling of use is easily obtained. Moreover, the operativity in the oral cavity of the toothbrush 1 is improved as the width | variety of the neck part 4 is below the said upper limit. Further, the hair can reach every corner of the oral cavity, and the dirt removal effect in the oral cavity is further enhanced.
When the width of the neck portion 4 is not constant, the width of the neck portion 4 means the minimum width of the neck portion 4.

The thickness of the neck portion 4 is preferably 3.0 to 4.5 mm, and more preferably 3.0 to 4.2 mm. When the thickness is equal to or more than the lower limit value, it is easy to suppress the strength of the neck portion 4 from being lowered, and the durability of the toothbrush 1 is enhanced. Furthermore, the toothbrush 1 does not become too soft, and a good feeling of use is easily obtained. Moreover, the operativity in the oral cavity of the toothbrush 1 is improved as the thickness of the neck part 4 is below the said upper limit. Further, the hair can reach every corner of the oral cavity, and the dirt removal effect in the oral cavity is further enhanced.
When the thickness of the neck portion 4 is not constant, the thickness means the minimum thickness of the neck portion 4.

The minimum diameter of the neck portion 4 is preferably 3.0 to 4.5 mm, and more preferably 3.0 to 4.2 mm. When the minimum diameter of the neck portion 4 is equal to or larger than the lower limit value, it is easy to suppress the strength of the neck portion 4 from being lowered, and the durability of the toothbrush 1 is enhanced. Furthermore, the toothbrush 1 does not become too soft, and a good feeling of use is easily obtained. Moreover, the operativity in the oral cavity of the toothbrush 1 is improved as the minimum diameter of the neck part 4 is below the said upper limit. Further, the hair can reach every corner of the oral cavity, and the dirt removal effect in the oral cavity is further enhanced.
The minimum diameter of the neck portion 4 means the smaller value of the width and thickness of the neck portion 4.

  The length of the neck portion 4 can be determined in consideration of the length of the head portion and the like, for example, a length of 30 to 90 mm. When the length of the neck part 4 is not less than the above lower limit value, it becomes easy to reach the hair to every corner in the oral cavity, and the dirt removal effect in the oral cavity is further enhanced. When the length of the neck portion 4 is not more than the above upper limit value, the operability of the toothbrush 1 in the oral cavity can be further enhanced.

Then, the manufacturing method of the said toothbrush 1 is demonstrated.
The manufacturing method of the toothbrush 1 includes a primary molding step in which the handle body 10 excluding the covering portion 30 and the soft elastic portion 6 is molded by injection molding using a first mold, and the handle body 10 molded in the primary molding step. The covering portion 30 and the soft elastic portion 6 are integrally formed on the handle body 10 using the process of cutting and removing the gate portion G from the handle body 10 and the handle body 10 and the second mold from which the gate portion G has been cut and removed. Secondary molding step.

  In the primary molding step, a first mold having a cavity (cavity) corresponding to the shape of the handle body 10 is used. In the first mold, a resin flow path that opens to the hollow portion in the gate portion G is formed, and a protrusion for forming a space in the handle body 10 in which the soft elastic portion 6 and the connection portion are disposed. Is formed.

  The molten hard resin supplied to the cavity in the first mold through the gate portion G is sequentially filled in the head portion 2, the neck portion 4 and the handle portion 7. Here, since the gate part G is arranged in the head part 2, the molten hard resin (hereinafter referred to as molten resin) supplied from the gate part G is a neck part with a short flow length and a short flow length. 4 is filled.

  By filling the cavity in the first mold with molten resin and cooling the first mold for a predetermined time to solidify the molten resin, as shown in FIGS. The handle body 10 is manufactured as a molded product in which the gate portion G extends in the length direction from the tip. The first mold in the present embodiment exemplifies a side gate system in which the gate extends from the molded product in the length direction (direction parallel to the parting surface), but the gate portion is formed on the back surface 2b of the head portion 2. May be locally disposed, and a pinpoint method in which the molded product and the gate portion are separated by the mold opening operation of the first mold may be adopted.

  Next, in the cutting / removing step, the gate portion G extending from the handle body 10 is cut and removed. The cutting of the gate portion G can be performed using an apparatus including a predetermined jig, a robot, and the like. The gate portion G is preferably completely removed from the handle body 10, but as shown in FIGS. 2 and 3, a part of the gate portion G remains as shown here.

  Next, in the secondary molding step, there is an internal space in which the handle body 10 is accommodated, and a molten soft resin is filled between the handle body 10 and the covering portion 30 and the soft elastic portion 6 are molded. Using the second mold forming the molding space, the molten soft resin is filled in the molding space in which the handle body 10 is accommodated. Then, by cooling the second mold for a predetermined time and solidifying the melted soft resin, as shown in FIGS. 1 to 3, the cover portion 30 and the soft elastic portion 6 are integrally formed on the handle body 10. The toothbrush 1 made is manufactured.

  Usually, an amorphous hard resin has a bulky molecular chain in the molecular skeleton, and it is difficult to take a regular molecular arrangement in the process of cooling and solidifying from a molten state. Therefore, for example, the molten resin supplied to the neck portion 4 is filled with high orientation as compared with the case where the molten resin is filled from the rear end of the handle portion 7. Therefore, the handle body 10 of the toothbrush 1 manufactured by the manufacturing method of the present embodiment improves the bending elastic modulus and fatigue strength of the neck portion 4 by increasing the orientation of the resin material.

  For this reason, in the manufacturing method of the present embodiment, it is possible to satisfy the specifications required for the thin head portion 2 and the extremely thin neck portion 4 even when an amorphous hard resin is used. Therefore, in the manufacturing method of this embodiment, the toothbrush 1 excellent in the external appearance which has the handle | steering-body 10 which can satisfy | fill both required mechanical characteristics and intensity | strength quality, and transparency can be manufactured easily. Moreover, in the manufacturing method of this embodiment, since the coating | coated part 30 has coat | covered the gate part G, safety | security can be ensured even when a gate trace remains. Moreover, since the coating | coated part 30 is formed with soft resin, when a head part 2 is inserted in an oral cavity, a soft touch feeling is obtained.

  EXAMPLES Hereinafter, although an experiment example is shown and this invention is demonstrated in detail, this invention is not limited by the following description.

(Examples, comparative examples, reference examples 1-2)
According to the specifications in Table 1, the flexural modulus and the fatigue strength of the neck portion were evaluated for the handle body 10 having the head portions of Examples, Comparative Examples, and Reference Examples 1 and 2. The width, length, thickness and shape of the head part were all the same.

  The head portion of the example had 28 hole implantation holes, and the tip of the head portion was the gate portion. The head part of the comparative example had 28 flock holes and the rear end of the handle part was a gate part. In the head part of Reference Example 1, the number of flock holes was set to 0, and the tip of the head part was used as a gate part. In the head part of Reference Example 2, the number of flock holes was only 12 located at both ends in the width direction, and the tip of the head part was a gate part.

<Evaluation method of flexural modulus>
Based on ISO178, as shown in FIG. 5, the front side of the head part 2 and the neck part 4 are supported by support elements 111 and 112 separated by a distance of 60 mm, and the position on the back side of 40 mm from the front end of the head part 2 A three-point bending test was performed in which a load was applied in the direction of the back surface by the presser 113. For applying the load by the pressing element 113, the pressing element 113 was moved at a speed of 2 mm / min. The calculation method for the flexural modulus was the secant method, and the three-point bending test was repeated three times (n = 3).

<Neck fatigue strength evaluation method>
Based on ISO20126, the fatigue strength was evaluated by the following procedure.
(1) The toothbrush (handle body) to be evaluated is immersed in the chemical challenge solution for 24 hours or more in the head portion and the entire length of the handle body.
(2) Fix to the fatigue strength tester at a position of 55 ± 1 mm from the longitudinal center of the head.
(3) Apply a load of 4.0 ± 0.1 N to the center of the head part and push it down, and repeat until the neck part breaks at a speed of 50 ± 10 times / min. The number of breaks of the neck portion was used as an index of fatigue strength. Evaluation was carried out with 8 samples.
(4) A ratio based on the index of the comparative example was obtained.

  As shown in Table 1, the handle body in which the gate portion is arranged in the head portion has improved bending elastic modulus and fatigue strength of the neck portion as compared with the handle body in which the gate portion is arranged at the rear end of the handle portion. I was able to confirm. In addition, from the evaluation of Reference Example 1 and Reference Example 2, it can be confirmed that the bending elastic modulus and the fatigue strength of the neck part are greatly improved by reducing the flow resistance of the molten resin filled through the gate part. It was.

  In the case where the flocking hole 22 is provided and the hair bundle is driven into the flocking hole 22 via a flat line to plant the hair, it is necessary to provide the handle portion 7 with a plurality of axial projections for forming the flocking hole 22. It is difficult to obtain the flexural modulus and the neck portion fatigue strength as in Reference Example 1 and Reference Example 2. Therefore, it is also possible to manufacture a toothbrush having a configuration in which a hair bundle member in which a hair bundle is preliminarily implanted is bonded to the flocked surface 20 with an adhesive or the like without forming a flock hole in the head portion 2. In the case of the toothbrush having this configuration, it is not necessary to provide the first mold with a plurality of shaft-like protrusions for forming the flocking hole 22, thereby greatly reducing the flow resistance of the molten resin filled through the gate portion. Therefore, it is possible to manufacture a toothbrush in which the flexural modulus and the fatigue strength of the neck portion are significantly improved.

[Second Embodiment]
Next, 2nd Embodiment of the manufacturing method of the toothbrush 1 is described with reference to FIG. 6 thru | or FIG. In these drawings, the same components as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 6 is an enlarged partial plan view of the head unit 2 according to the second embodiment. FIG. 7 is an enlarged partial cross-sectional view of the head unit 2 according to the second embodiment.
The toothbrush 1 in the second embodiment is different from the toothbrush in the first embodiment in that a recess 25 is provided in a part of the head portion 2 and a gate portion G is disposed in the recess 25.

That is, as shown in FIG. 7, a concave portion 25 having a shape in which the side surface 2 a is omitted is provided on the back surface side of the tip of the head portion 2. For example, as shown in FIG. 6, the recess 25 is formed in a concave shape having a substantially arc shape in a plan view. As an example, the position on the surface side of the gate part G in the thickness direction (the position on the surface side of the recess 25) is formed at the position of the parting line PL.
Other shapes are the same as those in the first embodiment.

  In the primary molding step when manufacturing the toothbrush 1 having the above-described configuration, a first mold is used in which the position of the parting line PL is the mold alignment position. In the first mold, a convex portion having a position and a shape corresponding to the concave portion 25 is provided, and a resin flow path opening in the hollow portion that constitutes the gate portion G is disposed on the convex portion.

  Then, by filling the cavity in the first mold with a molten resin and cooling the first mold for a predetermined time to solidify the molten resin, as shown in FIGS. 8A and 8B, The handle body 10 is manufactured as a molded product in which the gate portion G extends in the length direction from the concave portion 25 at the tip of the head portion 2.

  Next, in the cutting / removing step, the gate portion G extending from the handle body 10 is cut and removed.

  Next, in the secondary molding step, the above-described second mold is used to fill the molding space with the molten soft resin. And the toothbrush 1 which has the coating | coated part 30 and the soft elastic part 6, and has the head part 2 shown in FIG.6 and FIG.7 by solidifying the soft resin which cooled and melt | dissolved the 2nd metal mold | die for the predetermined time. Manufactured.

  In the toothbrush 1 of the present embodiment, since the gate portion G is disposed in the concave portion 25, the gate trace is also generated when the gate portion G extending from the handle body 10 is cut in the cutting / removing process. Protruding from the outer contour of the can be suppressed. Therefore, in the manufacturing method of the toothbrush 1 of the present embodiment, in addition to obtaining the same operations and effects as those of the first embodiment, it is possible to suppress the gate trace from protruding from the covering portion 30, and the safety is high. The toothbrush 1 can be manufactured.

[Third Embodiment]
Next, 3rd Embodiment of the manufacturing method of the toothbrush 1 is described with reference to FIG. In these drawings, the same components as those of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 9, in the toothbrush 1, the first portion 101 and the second portion 102 are connected via a connecting portion 103. The first portion 101 includes the head portion 2, the neck portion 4, and the connecting portion 103. The connecting portion 103 is disposed on the rear end side of the neck portion 4. The connecting portion 103 is formed in a size included in the outer contour of the distal end of the handle portion 7 and is embedded and connected to the distal end side of the handle portion 7. The connecting portion 103 is disposed on the front end side of the grip portion 8 in the handle portion 7.

  The first portion 101 of the toothbrush 1 having the above-described configuration is molded by being filled with molten resin with the rear end side of the connecting portion 103 as the gate portion G. Since the gate portion G extends from the neck portion 4, the distance from the neck portion 4 is short. For example, the gate portion G is supplied to the neck portion 4 as compared with the case where molten resin is filled from the rear end of the handle portion 7. The molten resin is filled with high orientation. Therefore, the first portion 101 manufactured by the manufacturing method of the present embodiment improves the bending elastic modulus and fatigue strength of the neck portion 4 by increasing the orientation of the resin material.

  As a method of manufacturing the toothbrush 1 including the first portion 101, the second mold other than the soft elastic portion 6 is filled by filling the molding space of the second mold containing the molded first portion 101 with the molten hard resin. The portion 102 is formed as the handle body 10 integrally connected to the first portion 101 and the connecting portion 103 in the secondary forming step, and further, a forming space for forming the covering portion 30 and the soft elastic portion 6 is formed. By using the third mold and filling the molding space of the third mold in which the handle body 10 is accommodated with the molten soft resin, the cover body 30 and the soft elastic part 6 are molded integrally with the handle body 10. The toothbrush 1 made is manufactured.

  In addition, as a method of connecting the first portion 101 and the second portion, in addition to insert molding the first portion 101, for example, the soft elastic portion 6 is integrally formed and the connecting portion 103 is inserted. Even if the second portion 102 having a hole is manufactured in advance, the connecting portion 103 is inserted into the hole, and the first portion 101 and the second portion 102 are integrally connected by an adhesive or the like. Good.

  As described above, the preferred embodiments according to the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the first and second embodiments described above, the configuration in which the gate portion G is disposed at the tip of the head portion 2 is exemplified, but the configuration is not limited to this configuration, and the side portion in the width direction of the head portion 2 is not limited. The structure to distribute may be sufficient. In this case, as described above, the gate portion is provided on the rear end side of the flocked hole 22 so that the flow resistance of the molten resin is not increased by the shaft-shaped protrusion provided in the first mold for forming the flocked hole 22. It is preferable to arrange G.

  DESCRIPTION OF SYMBOLS 1 ... Toothbrush, 2 ... Head part, 4 ... Neck part, 7 ... Handle part, 8 ... Gripping part, 10 ... Handle body, 20 ... Flocking surface, 101 ... First part, 102 ... Second part part, 103 ... Connection Part, G ... Gate part

Claims (7)

A head portion having a flocked surface on the front end side, a handle portion disposed on the rear end side from the head portion, including a gripping portion, and disposed between the flocked surface and the handle portion, and an external force applied to the head portion A manufacturing method of forming a toothbrush having a neck portion deformed by a resin material filled through a gate portion arranged at a predetermined position,
A method for manufacturing a toothbrush, wherein the resin material is filled through the gate portion disposed on the tip side of the grip portion.   The method for manufacturing a toothbrush according to claim 1, wherein the gate portion is disposed in the head portion.   The method for manufacturing a toothbrush according to claim 2, wherein the gate portion is disposed in a concave portion disposed in a part of the head portion.   The method for manufacturing a toothbrush according to any one of claims 1 to 3, further comprising a step of covering at least the gate portion with a second resin material.   The method for manufacturing a toothbrush according to claim 4, wherein the resin material is a hard resin, and the second resin material is a soft resin. Forming the first portion including the head portion, the neck portion, and the connecting portion disposed on the rear end side with respect to the neck portion by filling the resin material, and using the molded first portion, the resin material Forming a second part including the handle part connected to the first part by the connecting part by filling
The method for manufacturing a toothbrush according to claim 1, wherein the gate portion in the first portion is disposed in the connecting portion.   The method for manufacturing a toothbrush according to any one of claims 1 to 6, wherein the resin material is amorphous.

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