JP7421428B2 - injection molded products - Google Patents

Description

The present invention relates to an injection molded product that suppresses the effects of molding defects such as jetting.

Cited Document 1 describes, as an example of an injection molded product, a discharge container equipped with an HVD (High Viscosity Pump-Dispenser, hereinafter the same) type pump mechanism as an airless pump for discharging highly viscous contents. has been done. In this dispensing container, an inner tray is built into the injection-molded cylindrical container body (accommodating container 3), and when the contents are discharged using a pump mechanism, the pressure inside the container body is reduced and the inside of the container is reduced. The plate is configured to be movable. The contact area between the inner peripheral surface of the container body and the outer peripheral edge of the inner plate may cause liquid leakage if the fit is loose, and the inner plate may not move if the fit is tight. The inner circumferential surface needs to be a smooth curved surface with no irregularities.

Japanese Patent Application Publication No. 2014-148329

By the way, in injection molding, when molten resin is injected from a gate portion into a large space within a mold, there is a risk that molding defects such as jetting may occur.

In order to solve the problems in the conventional technology described above, the present invention suppresses the effects of molding defects such as jetting during molding in synthetic resin injection molded products, and has excellent moldability and dimensional stability. The challenge is to create injection molded products that

Among the means for solving the above problems, the main means of the present invention are:
A gate mark formed by the gate part coming into contact with the end surface of the molded product , and a recessed part recessed from the outer circumferential surface of the molded product toward the inner circumferential surface at a position directly below the gate mark. An injection molded product having
The gate mark is formed on the upper surface of the mouth barrel part of the container body, and the recess is formed on the outer peripheral surface of the mouth barrel part at a position opposite to the gate mark in the height direction. It is said to do so.
In the main means of the present invention, since the injection molded product has a concave portion in the vicinity of the position directly below the gate mark, during molding, the molten resin injected from the gate portion is transferred to the side of the mold forming the concave portion. The molded material is filled into a cavity while causing turbulent flow at the convex portion. Therefore, the influence of molding defects such as jetting is suppressed, and the injection molded product has excellent moldability and dimensional stability.

Therefore, the container body has excellent moldability and dimensional stability, and in particular, the inner circumferential surface has a smooth curved surface without unevenness due to poor molding.

Further, another means of the present invention is one in which the molding surface has a sealing surface that is in contact with the sealing member in addition to any of the above-mentioned means.
With the above means, for example, the inner circumferential surface of the mouth barrel portion that contacts the inner seal portion of the cap, or the inner circumferential surface of the container body where the inner plate or piston is placed, is made of a smooth curved surface without unevenness due to molding defects. It can be an injection molded article.

Further, the present invention adds to any of the above means the following: an annular stepped portion is formed on the upper surface of the mouth barrel portion.
With the above means, even if gate marks are formed on the upper surface of the mouth barrel part, the sealing member can be placed on the annular stepped part, so the sealing performance can be improved without being affected by the gate marks. can be improved.

In the present invention, the influence of molding defects such as jetting during molding is suppressed without taking measures such as increasing the diameter size of the gate part, and an injection molded product with excellent moldability and dimensional stability is achieved. be able to.

FIG. 2 is a front view of a container body showing an example of the injection molded product of the present invention. FIG. 2 is a cross-sectional view showing a part of the container body manufacturing apparatus. It is a top view of a container main body. It is an enlarged front view of a mouth barrel part. 5 is a sectional view taken along line VV in FIG. 4. FIG.

Embodiments of the present invention will be described below with reference to the drawings.
First, the general shape of the injection molded product will be explained.
The injection molded product shown in FIG. 1 is, for example, a container body 10 made of synthetic resin in which a relatively high viscosity liquid such as emulsion is accommodated, and an HVD type pump mechanism (not shown) is installed in the mouth tube part 2. It is used as a discharge container in which the liquid inside is discharged to the outside by a pressing operation applied to the pump mechanism.

In the container body 10, a narrow cylindrical mouth tube part 1 is erected on a cylindrical body part 4 with a shoulder part 3 interposed therebetween. A male thread 1a is carved on the outer circumferential surface 1A of the tip of the mouth barrel 1, and an annular screw having a flat molded surface (sealing surface) that protrudes upward is further located on the inner side of the upper surface 1b of the mouth barrel 1. A stepped portion 1c is formed, and a discharge port 6 is formed inside the annular stepped portion 1c.

Next, a manufacturing apparatus for the container body 10, which is an injection molded product, will be described.
As shown in FIG. 2, the manufacturing apparatus for the container body 10 includes a pair of split molds 21 that are movable left and right, a core mold 23 that is disposed inside the pair of split molds 21, and a pair of core molds 23 that are arranged inside the pair of split molds 21. The upper mold 24 is provided at a position above the split mold 21 and is movable up and down.

When the pair of split molds 21 are closed and the upper mold 24 is moved downward to set the mold to the closed state, the container body is placed in the portion where the pair of split molds 21 and the upper mold 24 and the core mold 23 face each other. A cavity 33 for molding 10 is formed.
The upper mold 24 is provided with a runner 31 extending in the vertical direction, and a gate portion 32 is formed at the lower end of the runner 31 in a downwardly contracted shape. and communicates with the cavity 33.
On the inner peripheral surface 21A on the upper side of the pair of split molds 21, a threaded portion 21a in which a male thread 1a is carved is formed. In addition, one (the right side in FIG. 2) of the split mold 21 has a convex portion protruding from the inner peripheral surface 21A toward the inside of the cavity 33, located directly below the gate portion 32 and in the vicinity of the gate portion 32. 21b is formed.

The thermoplastic resin is supplied as a molten resin from, for example, a screw-type extruder, passes through a runner 31, reaches a gate part 32, and is injected into a cavity 33 from the lower end of this gate part 32. The molten resin is then molded into the container body 10 through the cavity 33.
When the molten resin is injected into the cavity 33, turbulence occurs in the molten resin due to the convex portion 21b provided at a position directly below the gate portion 32. This turbulent flow suppresses molding defects such as jetting caused in the cavity 33 by the molten resin injected from the gate part 32. Therefore, the moldability and dimensional stability of the container body 10 can be improved, and in particular, the inner circumferential surface, which is a part of the surface, can be formed into a smooth curved surface without unevenness due to molding defects.

Note that the contact area between the inner circumferential surface of the container body 10 and the outer circumferential edge of the inner plate must have a necessary degree of sealing to prevent liquid leakage, so it is necessary to have a smooth curved surface with no unevenness due to molding defects. The inner circumferential surface (molding surface) of the container body 10 formed by the above functions as a sealing surface.

The overall structure of the container body 10 molded using the container body manufacturing apparatus described above is as described above, but as shown in FIG. A gate mark 7 is formed at one position where the lower end of the gate portion 32 abuts against the upper surface 1b, which is the end surface of the container body 10. However, since it is possible to suppress the occurrence of molding defects such as jetting without increasing the diameter size of the gate portion 32, the size of the gate mark 7 formed on the upper surface 1b can be reduced. . In particular, it is well known that increasing the diameter of the gate part is a method of suppressing molding defects such as jetting, and this method results in large gate marks being formed in the area where the gate part contacts, or whisker-like gate residues. However, the present invention is also effective in that such defects do not occur.
Further, as shown in FIG. 2, FIG. 3, or FIG. 4, a recess 8 formed by a convex portion 21b and depressed from the outer circumferential surface 1A of the mouth tube portion 1 toward the inner circumferential surface is located directly below the gate mark 7. is formed opposite to the gate mark 7 in the height direction. As shown in FIGS. 2 and 3, the recess 8 in this embodiment is formed in such a manner that it rests on the male screw 1a and is partially cut out. It's not something you can do.

In this embodiment, the case where the gate mark 7 is formed at only one location in the circumferential direction on the upper surface 1b of the mouth tube portion 1 is shown and explained, but the gate mark 7 is formed at multiple locations on the upper surface 1b. may be formed. In this case, the recesses 8 may be formed to correspond to the plurality of gate marks 7, respectively.

After a bottom lid (not shown) is attached to the bottom 5 having an opening, the container body 10 is filled with a relatively high viscosity liquid such as milky lotion, and an annular sealing member made of a packing (not shown) is inserted into the container body 10. It is placed on the sealing surface which is the molded surface of the annular stepped portion 1c, and an HVD type pump mechanism is attached to the mouth tube portion 1 from above, and the sealing member is pressed against the sealing member, thereby closing the discharge port 6. In this configuration, the sealing member is not formed on the upper surface 1b of the spout portion 1 where the gate mark 7 is formed, but is formed with a flat molding surface (sealing surface) that protrudes slightly above the upper surface 1b. Since it can be placed on the annular stepped portion 1c, the required degree of sealing (improved sealing performance) can be ensured, and as a result, the operation by air entering the HVD type pump mechanism (airless pump) is possible. It becomes possible to prevent defects. A movable inner plate (not shown) is set inside the container body 10 and used as a discharge container.

In such a dispensing container, the content liquid can be discharged from a nozzle (not shown) provided on the push-down head by the user pushing down the push-down head (not shown) that constitutes the pump mechanism. It is now possible to do so. At this time, since the inner tray rises within the container body 10 as the content decreases, even if the content decreases, the content can be force-fed toward the nozzle.

Here, as described above, the inner circumferential surface of the container body 10 is formed as a smooth curved surface without irregularities, without being affected by molding defects such as jetting. Therefore, the contact area between the inner circumferential surface of the container body 10 and the outer circumferential edge of the inner plate can be set to a suitable fit, and as a result, the necessary sealing degree is achieved and liquid is difficult to leak. Moreover, it is possible to make it easy to move.

Although the structure of the present invention and its effects have been described above with reference to Examples, the embodiments of the present invention are not limited to the above-mentioned Examples.

For example, in the above embodiment, the container body 10 having a cylindrical shape is shown and explained as an injection molded product, but the present invention is not limited to the above embodiment. Molded products having other shapes may also be used. When the injection molded product is a compact container, the top plate has a smooth surface with no unevenness due to molding defects, and has a beautiful appearance.

Further, in the above embodiment, the case where the gate portion 32 is formed on the upper surface 1b of the mouth barrel portion 1 has been described, but the position where the gate portion 32 is formed is not limited to the above embodiment. It may be formed on the lower end surface.

Further, in the case of a configuration in which the gate traces 7 are formed in a plurality of locations, a configuration may be adopted in which a recessed portion 8 is formed corresponding to at least one of the gate traces 7.

The present invention can be applied to a wider range of applications in the field of injection molded products that are molded under the influence of molding defects such as jetting.

1: Mouth barrel portion 1A: Outer peripheral surface 1a: Male thread 1b: Top surface 1c: Annular step portion 3: Shoulder portion 4: Body portion 5: Bottom portion 6: Discharge port 7: Gate mark 8: Recessed portion 10: Container body (injection molded product)
21: Split mold 21A: Inner peripheral surface 21a of split mold: Threaded portion 21b: Convex portion 23: Core mold 24: Upper mold 31: Runner 32: Gate portion 33: Cavity O1: Container shaft

Claims (3)

A gate mark (7) is formed when the gate part (32) comes into contact with the end surface of the molded product , and a mark is placed directly below the gate mark (7) from the outer peripheral surface to the inner peripheral surface of the molded product. An injection molded product having a recess (8) recessed toward the
The gate mark (7) is formed on the upper surface (1b) of the mouth barrel part (1) of the container body (10), and the recessed part (8) is formed on the outer peripheral surface of the mouth barrel part (1) and on the gate An injection molded product characterized by being formed at a position facing the mark (7) in the height direction . The injection molded product according to claim 1 , wherein the molding surface has a sealing surface that is in contact with the sealing member. The injection molded product according to claim 1 or 2, wherein an annular stepped portion (1c) is formed on the upper surface (1b) of the mouth barrel portion (1).

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