JPS5949185B2 - Double wall structure molded body made of synthetic resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double wall structure of a synthetic resin molded article, which improves the appearance and strength of the molded article, and improves the sealing effect when used as a container or a cap. Or, when used as a cup, it has properties such as resistance to two contents.

When we think about synthetic resin caps and lipstick caps used for containers, etc., we find that the cap has a sealing effect on the container body, has a certain degree of strength, and has a design that makes it look beautiful. It is required to have an effect, etc.

When it comes to cups, aside from the sealing effect, they need to have strength and beauty, and they are also required to have content resistance. Therefore, for caps and cups made of synthetic resin, it is desirable that the outer surface is scratch-resistant and glossy, and the inner surface has a sealing effect or is resistant to contents. Therefore, when manufacturing such a synthetic resin molded article, it is conceivable to use a double-walled structure in which synthetic resins having the above-mentioned properties are assembled on the outer and inner surfaces.

If the molded product has a double-walled structure, the various advantages of the synthetic resin described above can be utilized, and furthermore, it can be strengthened and a design effect can be obtained by using different colors. By the way, when a molded object is made of synthetic resin, if it is a soft synthetic resin, it will have an excellent sealing effect, and if it is a hard synthetic resin, it will be excellent in terms of strength and beauty such as gloss and texture. Become.

Therefore, in order to satisfy all the conditions such as sealing, strength, and aesthetics required depending on the purpose of the molded product, it is necessary to have the aforementioned double-walled structure, with a hard synthetic resin for the outer shell and a soft synthetic resin for the inner shell. It is preferable to use synthetic resin. The same thing applies to cups; from the standpoint of strength and aesthetics, a hard synthetic resin is used for the outer shell, and a synthetic resin with different properties that is resistant to contents is used for the inner shell.

However, in the case of such a double-walled structure, the melting point of the hard synthetic resin that forms the outer shell is higher than the melting point of the soft synthetic resin that forms the inner shell, so the inner shell must be part of the formwork. I can't do that.

Therefore, an outer shell body made of hard synthetic resin is molded in advance as a mold, and an inner shell body made of soft synthetic resin is injection molded from the inner surface of the outer shell body to the lower end on the circumferential side. However, if the inner shell is later injection molded in this way, a significant sink phenomenon occurs when the inner shell is cooled and solidified. As a result, delamination occurs, resulting in mechanical deterioration and strength problems.

Therefore, in FIG. 1, which shows a conventional cap molded product, in order to prevent such peeling, a flange 3 is provided at the lower end of the inner shell in contact with the lower surface of the inner shell for one circumference. However, if this is done, a new stepped portion due to sinking phenomenon will be created at the joint between the outer lower surface of the outer shell and the flange 3, resulting in a significant deterioration of the appearance. The present invention was developed to solve the above-mentioned disadvantages of the conventional techniques, and involves injection molding of an inner shell on the inner surface and end surface of an outer shell circumferential body, which is a part of the mold surface. The purpose of this is to enable a double-walled structure of the molded product, and to prevent the formation of a step at the joint with the outer shell due to sinkage of the inner shell after injection molding.
The purpose is to provide a molded product with a double wall structure that is excellent both in substance and appearance, and its structure is such that a lip is protrudingly provided on the inner end of the circumferential end surface of a cylindrical synthetic resin outer shell. The outer shell is used as a core, and the inner shell is injection molded on the inner surface and end surfaces of the circumference. Embodiments of the present invention will be described below based on the structure of the cap, with reference to FIGS. 2 to 5.

Reference numeral 11 denotes a cylindrical outer shell with a capped plate, which is made of hard synthetic resin.

The upper part of the outer shell 11 is an end wall 12 having a diameter slightly smaller than the inner diameter of the outer shell 11, and the end wall 12 is connected to the circumferential shell 13.
It is located so as to protrude upward from the upper end, and is connected to the circumferential body 13 via a connecting piece 14 .

Therefore, a notch 15 is formed at the upper end of the outer surface of the outer shell 11, and a portion of an inner shell 18, which will be described later, is injection molded into this cutout 15. Due to the shape of the outer shell body 11, a gap is formed between the end wall 12 and the upper end of the circumferential body 13, and the gap is defined as a communication hole 16. Also, the circumference of the trunk 13
At the inner end of the lower end surface, a rib 17 is provided with a protruding circumference that performs a function to be described later.

Next, FIG. 3 shows a state in which the outer shell body 11 is fitted into the cavity 21 as a core body, and FIG. 4 shows a state in which a core 22 and a core plate 23 are further installed.

Here, 24 is a gate, which serves as an injection passage for the synthetic resin material. Further, 18a and 18b are molding spaces for molding the inner shell 18, the molding space 18a is formed by the notch 15 of the outer shell 11 and the capit y 21, and the molding space 18b is formed by the outer shell 11. It is formed by the inner surface, the lower end surface of the outer shell circumferential body 13, the core 22, and the core plate 23, and these molding spaces 18a and 18b communicate with each other via the communication hole 16 of the outer shell 11.

In the state shown in FIG. 4, if a soft synthetic resin material for molding the inner shell 18 is injected and filled through the gate 24,
The inner shell 18 is formed from the notch 15 of the outer shell 11 and the inner surface of the outer shell 11 to the lower end of the circumference 13 of the outer shell 11.

The flange 19a at the lower end of the circumferential body 19 of the inner shell body 18 is where the shrinkage phenomenon appears most prominently during this molding process.
The lip 17 provided on the lower end surface of the outer shell body circumferential body 13 restricts the inward sinking phenomenon, and there is no room for a step to be formed on the outer surface of the outer shell circumferential body body 13 and the outer surface of the inner shell body flange portion 19a after molding. .

FIG. 6 shows an application of the present invention to a cap for a lipstick container, the structure of which is exactly the same as the cap described above, but in this case, the most important issue is its aesthetic appearance. Therefore, in order to provide strength to the outer shell and obtain design effects such as optical selection, hard synthetic resin is used,
Since the lipstick cap is usually fitted into the container body with its lower end in the form of an undercut, it is desirable to use an elastic soft synthetic resin for the inner shell. Next, Fig. 7 shows an application of the present invention to a cap, and its structure is almost the same as the cap described above, but here, considering the purpose of the cap, there are other problems such as strength and appearance. However, there are problems with heat retention, heat resistance, and content resistance. Therefore, by making the synthetic resin cup a double structure, problems such as strength and heat retention can be addressed, and by making the outer shell body from a hard synthetic resin, it gives an aesthetic appearance such as light selection, and the inner shell body is made of durable material. The properties of the contents are addressed by using synthetic resins that have physical properties and heat resistance.

According to the embodiment described above, it is possible to prevent as much as possible the introverted sink phenomenon that should occur at the end of the inner shell, so that the There is no step on the outer circumferential surface of the end of the molded body that becomes the joint, and the surface is flush with the other, and the appearance is not impaired.

In addition, there is no delamination between the outer shell and the inner shell, resulting in mechanical strength. Therefore, an outer shell made of hard synthetic resin that is strong and flexible is molded in advance, and this is used as a core as part of the molding frame, which is different from elastic soft synthetic resin or the outer shell. It becomes possible to later injection mold the inner shell made of a synthetic resin with physical properties.

Moreover, since the inner shell is injection molded not only on the inner surface of the outer shell but also on the end face of the outer shell and the outer peripheral surface of the outer shell, there is no possibility of incompatibility due to differences in physical properties between the outer shell and the inner shell. It is firmly assembled without being held. As a result, it is possible to produce a double-walled synthetic resin molded product that has excellent strength, is aesthetically pleasing, and has sealing effects and resistance to contents.

[Brief explanation of drawings]

Fig. 1 is a front half-sectional view of a cap showing an example of the double wall structure of the molded body, Fig. 2 is a plan view of an outer shell in which the present invention is applied to a cap, and Fig. 3 is a plan view of the outer shell. FIG. 4 is a front half-sectional view of the outer shell housed in the cavity as part of the molding frame, and a front half-sectional view of the outer shell housed in the cavity and a core and core plate installed. FIG. 5 is a front half-sectional view of the present invention. FIG. 6 is a longitudinal sectional view of a lipstick container cap according to the present invention, and FIG. 7 is a longitudinal sectional view of a lipstick container cap according to the present invention. 11... Outer shell, 12... End wall, 13
......Outer shell body circumference, 14...Connection piece, 1
5... Outer shell notch, 16... Communication hole, 17... Rib, 18... Inner shell, 18a, 18b...・・Inner shell molding space, 19・
...Inner shell body circumference, 19a...Brim section, 21
...Cavity, 22...Core, 23
...Core plate, 24...Gate.

Claims (1)

[Claims] 1. In a molded body with a double wall structure, a synthetic resin inner shell 18 is injection molded from the inner surface of the cylindrical synthetic resin outer shell 11 serving as the core body to the end surface of the circumferential body 13 as part of the mold surface. , a double-walled structure molded from synthetic resin in which ribs 17 are protrudingly provided on the inner end of the end surface of the outer shell body 13 where the inner shell body 18 portion whose outer circumferential surface is flush with the outer circumferential surface of the outer shell body 11 is located. body.