JP2653496B2 - Manufacturing method of hollow body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a hollow body used for decoration, display containers and the like.

[Conventional technology]

Conventionally, when manufacturing a molded body having a three-dimensional pattern inside, an internal mold having a three-dimensional pattern is arranged in a molding die,
A liquid transparent molding material is poured between an inner wall surface and an inner mold of the molding die, and is solidified. The inventor of the present invention has invented a method of manufacturing a hollow body in which an internal pattern is formed by an internal hollow space in such a molded body, and has already filed an application (Japanese Patent Application No. 62-91634).

[Problems to be solved by the invention]

However, the accuracy of the hollow body obtained by the above method is not yet satisfactory, and improvement is desired.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a method for manufacturing a hollow body in which a hollow body having a pattern therein can be manufactured with high accuracy without a complicated process by improving the above-described manufacturing method invented by the present inventors.

[Means for solving the problems]

In order to achieve the above object, a method for manufacturing a hollow body according to the present invention includes the steps of: forming an inner mold formed of a cellulose resin having solubility in a predetermined solvent in a molding space of the mold; A molding material made of a synthetic resin having no solubility in the solvent is injected into the molding space of the molding die in a state where a predetermined distance is maintained with the inner wall surface of the molding die, and then solidified and molded. Then, a hole is drilled from the outside of the molded body to the internal mold inside the molded body, the solvent is injected from the hole, the internal mold inside the molded body is dissolved, and the solution is poured from the hole. It is configured to pour out the molded body and form a hollow space consisting of the trace of dissolution of the internal mold inside the molded body.

[Action]

That is, the present inventor conducted a series of studies to form a pattern in the internal hollow space in the molding method using the molding die, and as a result, arranged the internal die made of cellulose resin in the molding space of the molding die. After the molding material made of synthetic resin is injected and solidified in the molding space in that state, the inner mold is dissolved using a solvent that can dissolve the cellulose resin and cannot dissolve the synthetic resin. It has been found that the outer shape of the inner mold is faithfully transferred to the hollow wall surface to form a hollow pattern, and the present invention has been achieved.

Ethyl cellulose resin, cellulose acetate resin, nitrocellulose resin, butyrate acetate cellulose resin and the like can be used as the cellulose resin forming the inner mold of the present invention, and the molding material is polystyrene resin,
Synthetic resins such as polymethyl methacrylate resin, AS (styrene-acrylonitrile copolymer) resin, ABS (styrene-acrylonitrile-butadiene copolymer) resin, and PVA (polyvinyl alcohol) resin can be used. As the solvent, methyl alcohol, ethyl alcohol and the like can be used.

Using such a raw material, the production of a hollow body can be performed, for example, as follows. That is, an inner mold made of cellulose resin having a desired pattern is formed in advance by using an inner mold forming mold. Then, when assembling a mold such as a split mold for forming a hollow body, the mold is fixed to the tip of a thread or the like and suspended in a state of being positioned in a molding space through a molding material injection hole or the like. Next, in this state, a molding material is injected into the molding space in the molding die from the injection hole and solidified. Then, after solidification, a hole that reaches the internal mold from the injection hole is drilled, and a solvent is injected from the hole,
The inner mold is brought into contact with a solvent, dissolved and removed.
As a result, removal marks of the inner mold are formed in a hollow pattern. When removing the inner mold, there is no problem either before or after removing the molded body from the mold, as long as the molding material has been solidified and formed into a molded body. In the case where the molding material is formed by injection molding, traces of a support rod or the like for solidifying the internal mold in the molding die can be used as holes for solvent injection, and particularly for solvent injection. There is no need to drill holes.

A method of dissolving the above-mentioned inner mold made of cellulose resin from the molded body by dissolution will be described. First, when ethyl cellulose resin is used as a dissolved substance for the inner mold, put ethyl alcohol into a syringe equipped with a small-diameter injection needle, make a hole from the injection hole for molding material to the inner mold, and inject ethyl alcohol. I do. By contact with this ethyl alcohol, the internal mold composed of ethyl cellulose resin is dissolved,
The dissolved ethyl cellulose resin solution flows backward from the outer periphery of the needle and elutes. Next, when it is necessary to fill the elution hole from which the ethylcellulose resin solution has been taken out, the elution hole is filled, for example, by discharging a molding material of the same quality as the molding material of the molded article from a syringe needle. As a result, a space having the same shape as that of the inner mold is formed in the molded body.
At this time, since the ethyl cellulose resin has extremely low affinity with other synthetic resins, the mold is separated from the molded body very smoothly, and the finished state and accuracy of the obtained inner wall surface of the space are excellent. become. In addition, by manufacturing the inner mold by injection molding, a large amount of the inner mold can be obtained with high accuracy and the cost can be reduced.

The hollow body with the internal pattern obtained in this way is usually a transparent product, and the internal hollow pattern can be clearly seen through the transparent portion, and thus can be used for various decorations and displays.

〔The invention's effect〕

The present invention is to produce a hollow body with an internal pattern as described above, and using a molding material or the like made of a synthetic resin to easily and accurately form an internal pattern made of a hollow space inside the molded body. Can be formed. By changing the outer shape and outer peripheral pattern of the inner mold made of cellulose resin, those shapes and patterns can be faithfully transferred to the hollow wall surface of the hollow space, and a variety of hollow patterns can be formed. . As an application, a decorative solution is injected into the hollow pattern, a paint film is applied to the hollow wall surface of the hollow pattern,
By forming a decorative object such as a metal vapor deposition film, a coating, and printing, it is possible to provide a product having a high decorative property. Further, for example, when a soluble substance such as ethyl cellulose resin is used for the inner mold, it can be reused because it can be regenerated after use, thereby realizing cost reduction.

 Next, the present invention will be described based on embodiments.

[Example 1] A two-part mold for forming an inner mold having a golf ball shape engraved on the inner wall surface was prepared, and a golf ball-shaped inner mold was formed by injecting ethylcellulose resin into the mold. Formed. Next, as shown in FIG. 1, the internal mold 3 was placed in the internal space of the upper and lower halves of the injection-molding cylinder forming die 1 and hung with wires. In this state, a molding material made of a transparent liquid urethane resin was poured from the molding material injection hole 2 and waited for solidification. Next, the mold 1 is opened to take out the columnar forming body, and as shown in FIG. 2, an elution hole 4 reaching the inner mold 3 in the form of a golf ball.
Was drilled. Next, a small-diameter injection needle is inserted into the elution hole 4 and ethyl alcohol is injected from the tip of the injection needle to dissolve the dissolved ethyl cellulose resin solution with the outer periphery of the injection needle while dissolving the inner mold 3. It flowed out from the gap with the hole 4, and a golf ball-shaped middle space (pattern space) was formed at the outflow trace. Then, the columnar formed body was laid down, and polystyrene resin of the same quality as the molding material was poured into only the elution hole 4 with a small-diameter injection needle to fill the elution hole 4. Thus, a transparent hollow body having a golf ball-shaped pattern space formed therein was obtained.

Example 2 A spherical inner mold made of cellulose acetate resin was injection molded using a mold having a spherical molding space. Next, the above-mentioned internal mold was inserted and suspended in the internal space of the cube molding die. Then, from the molding material injection hole of the mold,
A molding material made of a transparent liquid polymethyl methacrylate resin was poured and left for a predetermined time to wait for solidification. Next, the cubic molded body was taken out of the mold, and a relatively large-diameter elution hole capable of serving as a vase was formed. A syringe needle was inserted into the elution hole, and a solvent was injected from the tip of the syringe needle to dissolve the inner mold made of cellulose acetate resin. The dissolved cellulose acetate resin was poured out from the elution hole. Thus, a transparent container as a vase, a cosmetic container, and a food container as shown in FIG. 3 was obtained.

[Example 3] A golf ball pattern was replaced with a bolt pattern, and it was made of nitrocellulose resin, and a transparent AS resin was used as a molding material. Otherwise, Example 1
In the same manner as in the above, a transparent hollow body for display having a bolt pattern therein was obtained. This is shown in FIG.

Example 4 An inner mold was prepared by coating a paint film on the surface of a round ball injection-molded with butyrate cellulose resin, and a transparent ABS resin was prepared as a molding material. Otherwise in the same manner as in Example 1, a hollow body for display having a daruma pattern inside was obtained. At this time, the paint film was transferred to the wall surface of the pattern space of the molded article due to the heat of the injection molding material, and it appeared as if the daruma were actually embedded. This is shown in FIG.

In the above description, a transparent hollow body is manufactured using a transparent molding material.However, an opaque molding material is used, and the internal pattern space is enlarged, for example, to be used as a space for filling a reinforcing material. You may. In the above embodiment, the inner mold is formed by injection molding. However, the present invention is not limited to this, and may be formed by a gypsum mold or the like. In the case where the above inner mold is manufactured by injection molding,
By using a turntable type rotary molding machine, the production efficiency of the internal mold can be greatly improved. Further, the hollow body can also be obtained by two-color molding in which an inner mold is first injection-molded and a molding material is injected around the outer periphery of the inner mold. To dissolve and remove the internal mold. The hollow body is used not only as a decorative article or a vase, but also as a large-capacity tank such as a fuel tank of an automobile, a cosmetic container such as a container for cosmetic cream, an artificial organ such as an artificial heart, a lighting device such as a headlamp, and the like. Can be used. When a headlamp is manufactured, a coating film or the like for forming a reflection surface is applied to a portion of an internal mold corresponding to the reflection surface of the headlamp, and the coating is transferred to a molded body.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a state in which an inner mold is inserted into a space for internal molding of a mold, FIG. 2 is a perspective view showing a state in which an elution hole is formed in a cylindrical molded body, and FIGS. FIG. 5 and FIG. 5 are perspective views of another embodiment. 1 ... mold, 2 ... molding material injection hole, 3 ... inner mold 4
…… elution hole

Claims (3)

(57) [Claims] 1. An inner mold made of a fibrous resin having a solubility in a predetermined solvent is inserted into a molding space of the mold while maintaining a predetermined distance from an inner wall surface of the mold. In this state, a molding material made of a synthetic resin having no solubility in the solvent is injected into the molding space of the molding die and solidified to form a molded body. Drilling a hole over the internal mold, injecting the solvent through the hole, dissolving the internal mold inside the molded body, and pouring the solution out of the molded body from the hole,
A method for producing a hollow body, wherein a hollow space comprising a trace of dissolution of the internal mold is formed inside the molded body. 2. The method according to claim 1, wherein the inner mold is formed by injection molding. 3. The method for producing a hollow body according to claim 1, wherein the molding material is transparent.