JP3536040B2 - Manufacturing method of rod-shaped molded body - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rod-shaped molded body which is injection-molded into a predetermined shape by sequentially using resins having different characteristics, and more specifically, a tip portion such as a hard resin fork and spoon. The present invention relates to a method for producing a rod-shaped molded product having a functional structure, and further, a rod-shaped handle portion to be gripped when used is provided with a gripping surface coating layer on the outer periphery thereof.

[0002]

2. Description of the Related Art Forks and spoons used by infants and the like are preferably made of a material such as a plastic which is hard but slightly deformed, rather than a material having a high strength such as a metal. Further, when selling baby food or the like, by attaching a fork or spoon formed of plastic or the like to the baby food, it is very convenient to save the trouble of preparing and washing the dishes when giving the baby food or the like.

Under these demands, tableware such as synthetic resin forks and spoons are used for infants and children. It is preferable that such tableware for infants or children has a design that makes it fun to use, in addition to the function as a tableware originally possessed by a fork or spoon. The tip portion preferably has a certain level of strength in order to function as tableware, but the handle portion is preferably formed of an elastic resin or the like so that it is easier to grip and is less likely to slip. As a method of manufacturing a molded body using different resins as described above, there are molding methods such as insert molding and two-color molding.

FIG. 5 shows a conventional method for manufacturing a rod-shaped molded body by insert molding. First, in the case of insert molding, the primary mold 120 is made of a resin such as polypropylene that is hard but has a slight deformation.
The primary molded body 101 is manufactured therein. FIG. 5 shows a mode in which four forks 111 and four spoons 112 are manufactured by one molding. The primary molded body 101 thus formed is set in another mold 240 as shown in FIG. 6 and an elastic resin is injection-molded to form a fork 211 or a spoon 212 having a predetermined shape. .

[0005]

However, in actuality, during the secondary molding, the primary molded body 101 having a rod-like structure like the handle portion 130 is attached to the base end portion 13 of the handle portion 130.
2 Hold the secondary molding resin in a cantilevered state in one place and mold 240
If you try to injection mold and insert mold inside,
As indicated by the wavy line, the position of the tip portion 133 of the rod-shaped structure may be displaced by the injection pressure of the secondary molding resin, and the secondary molding resin may not evenly flow into the front and back surfaces of the primary molding. In such a case, the primary molded body 101 serving as the core material is deformed and the tip portion 133 thereof is exposed on the surface of the secondary molded body. In particular, in the case where the cross-sectional shape of the primary molded body 101 is elliptical, such displacement is larger and the defective rate is higher than in the case where the cross-sectional shape is circular. For tableware such as forks or spoons, it is easier to grasp the handle portion when the handle has an elliptical cross-section than when it has a circular cross-sectional shape, and this is especially the case for tableware such as infants.

As a method for improving the molding failure when the above rod-shaped member is held in a cantilevered state in a mold, generally, (A) a position near the base end portion 132 holding the primary molded body is used. Method for injecting resin for secondary molding from (B)
A method in which not only the base end portion 132 but also the tip end portion 133 is clamped by the secondary molding die is adopted.

However, in the above method (A), the primary molded body that is the closest to the gate into which the secondary molding resin flows is partially melted by the molten secondary molding resin. (Or softened state). Especially, the distance from the gate to the primary compact is about 5 mm
When the length is shorter than that or when the primary molded body is arranged in a wall shape that blocks the resin for secondary molding, the above tendency becomes large. Therefore, this method cannot be adopted when the thickness of the secondary molded body is not so thick as in the case of a fork handle or a spoon handle.

In the method (B), when the tip 133 is also held by the secondary molding die 240, the tip cannot be covered with the resin used for the secondary molding. Further, the movable mold is arranged in the secondary molding mold so as to clamp the tip of the primary molding, and the core mold is moved backward by interlocking with the inflow of the secondary molding resin. It is possible to position the primary molded body which is

However, such a mold having a movable part which is movable in conjunction with the inflow of the molten resin is very expensive, and the injection pressure of the resin and the sandwiching mold for centering the core material are required. There are also manufacturing problems such as the timing of retracting is very difficult. In view of the conventional situation as described above, the present invention enables injection molding of a secondary molded body into a predetermined shape on the outer peripheral portion of the primary molded body without causing molding failure by sequentially using resins having different characteristics. An object of the present invention is to provide a method for producing a rod-shaped molded body.

[0010]

According to the present invention for achieving the above object, a functional portion formed on the distal end side, a base end portion for supporting the functional portion, and a rod-shaped handle formed on the rear end side are provided. A primary molded body consisting of a part is molded with a hard resin, and further, over the substantially entire outer peripheral surface of the rod-shaped handle part, a method for manufacturing a rod-shaped molded body covered with a secondary molded body made of an elastic resin, On the rear end side of the rod-shaped handle portion of the primary molded body ,
And the gate of the secondary molded body die that covers the secondary molded body
The outer peripheral surface of the rear end side which is disposed opposite to said primary molding
It is one step higher than the surrounding surface of the body,
A secondary molded body made of an elastic resin is formed on the outer peripheral surface of the rod-shaped handle.
When it is coated, it protrudes from the surface of the secondary molded body.
Convex parts exposed to the outside are formed on both the front and back surfaces of the primary molding.
The secondary molding die is formed while projecting.
The rear end of the rod-shaped handle arranged to face the gate of
Upon section was formed to be inclined to place the primary molded body having the protrusion in a predetermined position in said secondary molding die,
The outer peripheral surface of the base end portion of the primary molded body and the outer peripheral surface of the convex portion are closely pressed against the inner peripheral surface of the secondary molding die, and from this state, the elastic resin forming the secondary molded body. The rod shape
It is introduced into the secondary molding die from the gate opened on the rear end side of the handle , and then the secondary molding die is opened.
When the rod-shaped molded product is taken out from the secondary molding die
The projecting portion from the elastic resin of the secondary molded body to the outside.
It is characterized in that substantially the entire outer peripheral surface of the rod-shaped handle portion is covered with the elastic resin in the state of being extended.

According to the present invention as described above, when the elastic resin is insert-molded on the outer peripheral portion of the primary molded body by the secondary molding die, the tip of the convex portion provided on the rod-shaped handle of the primary molded body is secondary. Since the base end side shaft of the primary molding is pressed against the inner surface of the secondary molding die while being pressed against the inner surface of the molding die, the primary molding should be firmly fixed in the secondary molding die. You can Therefore, if the secondary molding resin is injected from this state, the primary molding body does not move or swing due to the pressure at the time of injection, and therefore the secondary molding resin can be injected within a predetermined range. .

Here, the inner diameter of the die in the range in which the base end portion is sandwiched in the secondary molding die is formed smaller than the inner diameter of the die used for molding the primary compact. Is preferred. With such a configuration, it is possible to prevent the secondary molding resin from leaking to the outside.

Further, the hard resin constituting the primary molded body is made of a thermoplastic resin or a thermoplastic resin composition,
The elastic resin forming the secondary molded body is preferably composed of an elastomer or an elastomer composition containing an elastomer. Further, the height of the convex portion formed by projecting on both sides of the primary molded body is preferably in the range of 0.005 mm to 0.2 mm.

With such a structure, the tip of the convex portion of the primary molded body can be partially projected from the surface of the secondary molded body by injecting the secondary forming resin and then releasing the mold. Therefore, the projecting convex portion becomes a pattern, and a facial expression or the like can be expressed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a rod-shaped molded body according to the present invention will be described below with reference to the drawings. Figure 1
FIG. 4 is a plan view of a spoon that is an example of a rod-shaped molded body manufactured by the manufacturing method according to the embodiment of the present invention. 2 is a sectional view taken along the line AA in FIG. Also, FIG.
FIG. 3 is a sectional view taken along line BB in FIG. 1.

The spoon 10 comprises a rod-shaped handle portion 12 and a spoon portion 14 extending from the tip of the rod-shaped handle portion 12. The surface of the rod-shaped handle portion 12 of the spoon 10 is covered with an elastomer 15. The spoon portion 14 of the spoon 10 is formed of a thermoplastic resin. As the thermoplastic resin forming the spoon portion 14, polyolefin such as polypropylene, polystyrene, polycarbonate, polyether sulfone, polyamide, AS resin, One type of resin selected from ABS resin and polyacetal can be mentioned. Among these, by using a resin having appropriate hardness and flexibility, such as polypropylene, the spoon 14 is less damaged during use. The surface coating of the handle 12 is
It is preferable to use a resin having a high elasticity, and an elastic resin called an elastomer is used for the surface coating of the handle portion 12. Examples of such elastic resins include:
Styrene-based elastomer, olefin-based elastomer,
At least one elastomer selected from urethane elastomers and silicone rubbers is preferable. Desirably, styrene / ethylene / propylene / styrene copolymer (SEPS) or styrene / ethylene / butylene / styrene copolymer (SEBS) is preferable. Such an elastomer is less slippery on the surface than the thermoplastic resin forming the spoon portion 14, and gives a very good feeling in use.

Spoon 10 which is an example of the molded article of the present invention
The handle portion 12 of the primary molded body is extended from the spoon portion 14 with the same resin. And, in this handle 12,
From the spoon portion 14 through the base end portion 16 having a predetermined length, the base end portion 1
A core member 18 having a diameter smaller than that of the core 6 is formed. A surface coating layer made of a thermoplastic elastomer 15 is provided on the outer periphery of the core material portion 18 having a reduced diameter.
The outer peripheral surface 20 is covered so as to be substantially flush with the outer peripheral surface 20. Furthermore, the tip of the surface coating layer made of the elastomer 15 is a ball-shaped mass.

On the other hand, on the tip side of the core portion 18, three convex portions 22 that represent a human face are integrally formed so as to project at symmetrical positions on both front and back surfaces. The number and height of the convex portions 22 and the pattern to be displayed on the outside as a whole can be arbitrarily set, but the height H1 of the portion of the convex portion 22 protruding from the surface coating layer 15 is the convex portion 22. 1 / thickness T1
It is in the range of 100 to 1/5, more preferably 1 /
It is 50 to 1/10. Further, the protruding height H1 is
It is in the range of 0.005 mm to 0.2 mm, and more preferably in the range of 0.05 mm to 0.1 mm. Further, the thickness T2 of the core member 18 which is the primary molded body is 0.5 mm to 1
Within the range of 2 mm. Furthermore, the total thickness T0 is 2
mm to 15 mm, more preferably 2 mm to 10 mm.

A manufacturing method for molding such a molded body 10 will be described below. First, using a primary mold 120 similar to that shown in FIG. 5, a plurality of primary molded bodies each including a rod-shaped handle portion 12 and a spoon portion 14 are assembled by hard resin and integrally molded. By injection of the hard resin, the obtained primary molded body is separated from the mold after being released from the mold.

Next, the primary molded body 10 is set in the secondary molding die 40 as shown in FIG. At this time,
The mold inner diameter of the portion S of the secondary molding die 40 that holds the base end portion 16 of the primary molded body is 1/10 or less of the die inner diameter used when molding the primary molded body. That is, the length is preferably reduced by 1/20 or less, here by 3/100. Further, the mold closing pressure of this portion S is set to be slightly higher than the normal mold closing pressure.

On the other hand, at the position of the convex portion 22 provided so as to protrude between the front and back surfaces, the height of the primary molded body is formed slightly larger than the diameter of the inner wall surface of the secondary mold 40. Therefore,
When the secondary molding die 40 is closed and closed, the convex portion 2
2 is slightly deformed by the secondary molding die 40. When an elastic resin such as an elastomer is injected into the secondary molding die 40 from this state, those resins flow into the periphery of the core portion 18 and are covered in a predetermined range. At this time, the gate into which the resin is injected is located a predetermined distance away from the tip of the rod-shaped core 18 as shown in FIG. 2, and the tip 29 does not block the flow of the gate. As described above, since the resin reservoir 32 is ensured because of the inclined angle, the tip portion 29 of the core material portion 18 is not deformed by the heat of the molten resin. When the mold 40 is released after the elastic resin is cured, the pressure acting on the convex portion 22 is released, and the convex portion 22 returns to its original shape. Then, since the convex portion 22 which is the primary molded body has flexibility, the convex portion 2 is released when the closing pressure is released.
2 is very small, but it projects. As a result, the tip portion 25 of the convex portion 22 is exposed from the surface of the secondary molded body 15.

In this way, the secondary molding can be insert-molded on the surface of the primary molding. The molded body obtained by the secondary molding die 40 has three convex portions 22 appearing on the front and back surfaces of the handle portion 12, and has a pattern as if it were a human face. The molded body of
It is preferred by users such as infants and can double the enjoyment of eating.

Since the color of the convex portion 22 is the color of the primary molded body, it can be easily recognized from the outside due to the difference in hue from the secondary molded body. Although the method for manufacturing the rod-shaped molded product according to one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the embodiment, the protrusions 22 are formed at one location on the front and back surfaces, but when the handle 12 is long, for example, the number of locations where the protrusions 22 are provided is increased to two. You can also do it. Further, in the above embodiment, the facial expression is expressed by the three convex portions 22, but the appearing pattern may be a geometric pattern.

[0024]

As described above, according to the method for manufacturing a rod-shaped molded article according to the present invention, a rod-shaped molded article is injection-molded into a predetermined shape by successively using resins having different characteristics without causing defective molding. The body can be provided.

[Brief description of drawings]

FIG. 1 is a front view of a rod-shaped molded body manufactured according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a cross-sectional view when insert molding is performed by the secondary molding die according to the present embodiment.

FIG. 5 is a cross-sectional view of a mold when an injection is performed using a primary mold of a conventional example.

FIG. 6 is a cross-sectional view of a mold when injection is performed using a secondary molding mold of a conventional example.

FIG. 7 is a cross-sectional view of a mold showing an operation when the secondary molding mold of the conventional example is used for injection.

[Explanation of symbols]

10 Rod shaped body 12 handle 14 Tsubasa 15 Elastomer 16 Base end 22 convex

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B29L 31:06 B29L 31:06 (56) References JP 2000-79624 (JP, A) International publication 00/010442 (WO, A1 ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 45/14 B29C 45/16 B29C 45/26 A47G 21/00

Claims (6)

(57) [Claims] 1. A primary molded body composed of a functional portion formed on the front end side, a base end portion supporting the functional portion, and a rod-shaped handle portion formed on the rear end side is formed of a hard resin. ,
Furthermore, a method for producing a rod-shaped molded body in which a secondary molded body made of an elastic resin is covered over substantially the entire outer peripheral surface of the rod-shaped handle , which is the rear end side of the rod-shaped handle of the primary molded body , and The two
Opposite the gate of the secondary molding die that covers the secondary molding
On the outer peripheral surface on the rear end side to be arranged, it is made one step higher than the surface around the primary molded body,
An elastic resin is formed on the outer peripheral surface of the rod-shaped handle of the primary molded body.
When the secondary molded body is coated, the surface of the secondary molded body
The convex portion protruding from the outside and exposed to the outside,
Is formed so as to project on both front and back surfaces, and is further arranged so as to face the gate of the secondary molding die.
The form inclined rear end portion of the rod-shaped handle portion which is, when arranging the primary molded body having the protrusion in a predetermined position in said secondary molding die, the proximal end of said primary molded member The outer peripheral surface of the portion and the outer peripheral surface of the convex portion are pressed tightly against the inner peripheral surface of the secondary molding die, and the elastic resin forming the secondary molded body from this state is formed into the rod shape.
It is introduced into the secondary molding die from the gate opened on the rear end side of the handle , and then the secondary molding die is opened.
When the rod-shaped molded product is taken out from the secondary molding die
The projecting portion from the elastic resin of the secondary molded body to the outside.
A method for manufacturing a rod-shaped body, wherein substantially the entire outer peripheral surface of the rod-shaped handle portion is covered with the elastic resin in a state of being taken out . Wherein the inner diameter of the mold ranges for clamping the proximal end portion of the secondary molding die, as compared to the mold inner diameter was used in molding the primary molded body is small fence formed The method for producing a rod-shaped molded body according to claim 1, wherein. 3. The hard resin constituting the primary molded body,
The rod-shaped molded body according to claim 1, wherein the rod-shaped molded body is made of a thermoplastic resin or a thermoplastic resin composition, and the elastic resin constituting the secondary molded body is an elastomer or an elastomer composition containing an elastomer. Method. 4. The rod-shaped molded body according to claim 1, wherein the height of the protrusions formed by projecting on both sides of the primary molded body is in the range of 0.005 mm to 0.2 mm. Production method. 5. The height protruded from the elastic resin of the secondary molded body of the convex portion provided in the primary molded body is in the range of 1 / 100-1 / 5 of the thickness of the convex portion The method for producing a rod-shaped molded body according to claim 1, wherein The convex portion 6. provided in the primary molded body, the symmetrical position of the front and rear surfaces of the primary molded body, the rod shaped molded according to claim 1, characterized in that it is protruded integrally Body manufacturing method.