JPH0813482B2 - Closure member and its injection molding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a closure member and its injection molding method, and in particular,
The present invention relates to a capping member formed by foaming only a part thereof.

(B) Problems to be solved by the conventional technology and invention The foamed resin foamed by adding a volatile or decomposable foaming agent or by adding gas utilizes various properties such as heat insulation and elasticity. Widely used for.

However, these foamed resins cannot be used for products that require rigidity, since the entire resin is foamed and lacks rigidity, as found in, for example, cup noodle containers, extrusion molded sheets, packings for packing, and the like.

Therefore, for example, in the case of a stopper member for a bottle mouth that requires rigidity, the stopper member body must be formed of unfoamed resin, and a separate rubber packing or foam packing must be attached to the seal portion before use. . However, mounting the packing on the stopper member is an additional step, and it is desirable that the stopper member main body has a packing function.

The present inventor, in order to solve the above problems,
The present invention was developed.

(C) Means for Solving the Problems The present invention is a cap member for a bottle mouth, and the cap member is formed by injection molding, and a foamed portion is integrally formed with the cap member body during injection molding. The present invention relates to a capping member in which a foaming part is provided in a sealing part with a bottle mouth of the capping member.

The cap member of the bottle mouth of the present invention is a mold part at a portion where foaming is required in the process of injecting a molten resin mixed with a decomposable foaming agent into a cavity of a mold at high pressure and cooling to a pyrolysis foaming temperature. It is an injection molding method of a cap member of a bottle mouth that foams a sealing part with a bottle mouth, in which a mechanical decompressed space is formed by operating parts to foam a resin in the decompressed space. Loosen or heat the mold parts to
It is molded by an injection molding method in which the mold other than the mold part is cooled.

In the present invention, the degree of foaming can be appropriately changed by adjusting the degree of formation of the depressurized space, temperature conditions, content of the foaming agent, and the like. Further, the foaming location can be set appropriately by selecting or adjusting the location forming the depressurized space.

As the resin of the molded article of the present invention, resins capable of injection molding such as polyethylene, polypropylene and polystyrene can be used.

The above-described capping member can apply the characteristics of the foamed resin to the sealing portion of the capping member, and examples thereof include the following.

The capping member is the outer lid of the bottle mouth, and the foaming portion occupies most of the back side of the top surface portion of the outer lid including the sealing portion with the top surface of the bottle mouth.

The capping member is an outer lid of the bottle mouth, and the foaming portion is annularly provided in a sealing portion with the bottle mouth top surface on the back side of the top surface portion of the outer lid.

The stopper member is the inner stopper of the bottle mouth, and this inner stopper has a cylindrical inner leg that press-contacts and seals the inner peripheral surface of the bottle mouth, and the foaming portion is provided on this cylindrical inner leg. .

(D) Action and effect The closure member according to the present invention is partially foamed,
Moreover, since the degree of foaming is also adjusted appropriately, the unfoamed portion has rigidity and excellent shape retention, and various characteristics of the foamed resin can be utilized.

That is, since the seal portion is a bottle cap closure member that is foamed during injection molding, the outer surface, the mounting portion with the bottle mouth, and the like have rigidity, and sufficiently perform the function as the cap member, and are separate members. Sealing property can be provided without using the packing.

(E) Embodiment FIG. 1 shows a cap member for a bottle mouth according to a first embodiment of the present invention, and FIGS. 2 and 3 show an injection molding method therefor.

As shown in FIG. 1, the closure member of the first embodiment is
A cap member for a bottle mouth, the cap member being formed by injection molding, a foam portion is formed integrally with the body of the cap member at the time of injection molding, and the foam portion is provided in a seal portion with the bottle mouth of the cap member. ing. That is, this stopper member is the outer lid 1 of the bottle mouth.
Most of the back side of the top surface portion 2 is foamed. The foaming portion 3 injects a molten resin mixed with a decomposable foaming agent from the gate 4 into the cavity 6 of the mold 5 at a high pressure, and cools the molten resin to the pyrolysis foaming temperature. The inner core 7 forming the portion requiring foaming is pulled by operating a fluid pressure cylinder such as hydraulic pressure or pneumatic pressure (Fig. 3).
A mechanical decompressed space is formed, and resin is foamed so as to fill the decompressed space to form the foamed portion 3. At the time of injecting into the cavity 6, the molten resin, which is, for example, about 200 ° C., which varies depending on the type of resin, is cooled in the course of cooling, or is cooled by the middle core 7 heated by the heater 9 as shown The foaming agent is kept at a foamable temperature of, for example, 100 to 180 ° C. until the mechanical decompression space is filled, while the cavity plate 10 and the outer core 11 which are the other constituent parts of the cavity 6 are cooled and come into contact with them. The resin is cooled so that it quickly solidifies in the unfoamed state after passing the foaming temperature. 12 is a stripper ring.

The capping member of the first embodiment molded in this way is
The outer surface, which is an unfoamed portion, has a rigidity required as a closure member, and the foamed portion 3 seals the top surface of the bottle mouth when it comes into pressure contact.

4 and 5 show a second embodiment and a third embodiment of the present invention, respectively.

The stopper member of the second embodiment is the outer lid 21 of the bottle mouth, and only the contact seal portion on the top surface of the bottle mouth on the back side of the top surface portion thereof is foamed,
An annular foam part 23 is formed.

The closure member of the third embodiment is an inner plug 31 of the container, and only the cylindrical inner leg 33 that seals the inner peripheral surface of the bottle mouth 34 by pressure contact is foamed. In FIG. 5, 35 is a score, 36 is a score tear-off ring, and 37 is a fitting portion on the outer surface of the bottle mouth.

[Brief description of drawings]

FIG. 1 is a sectional view of a stopper member according to the first embodiment of the present invention, and FIG.
FIG. 3 and FIG. 3 are sectional views showing a step of injection molding the stopper member of the first embodiment, FIG. 4 is a sectional view of the stopper member of the second embodiment, and FIG. 5 is a stopper member of the third embodiment. FIG. 1,21,31 …… Capping member, 2 …… Top surface, 3,23,33, …… Bubbling part, 6 …… Cavity.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // B29K 105: 04 B29L 9:00 31:56

Claims (5)

[Claims] 1. A cap member for a bottle mouth, wherein the cap member is formed by injection molding, and a foam portion is integrally formed with the body of the cap member at the time of injection molding, and the foam portion forms a bottle mouth of the cap member. A stopper member provided in the seal portion. 2. The capping member according to claim 1, wherein the capping member is an outer lid of the bottle mouth, and the foaming portion occupies most of the back side of the top surface portion of the outer lid including the sealing portion with the top surface of the bottle mouth. 3. The capping member according to claim 1, wherein the capping member is an outer lid of the bottle mouth, and the foaming portion is annularly provided in a sealing portion with the bottle mouth top surface on the back side of the top surface portion of the outer lid. . 4. The stopper member is an inner stopper of the bottle mouth, and the inner stopper has a cylindrical inner leg for press-sealing the inner peripheral surface of the bottle mouth.
The closure member according to claim 1, wherein the foamed portion is provided on the tubular inner leg. 5. A molten resin mixed with a decomposable foaming agent is injected into a cavity of a mold at a high pressure to activate a mold part portion where foaming is required in the process of cooling to a pyrolysis foaming temperature. A method for forming a mechanical decompressed space, in which resin is foamed in the decompressed space, is an injection molding method for a cap member of a bottle mouth that seals a bottle mouth, and a mold part part that forms the mechanical decompressed space. An injection molding method in which the cooling of the mold is loosened or heated, and the mold other than the mold part is cooled.