JP2003010780A - Method of manufacturing inside surface coated vessel and inside surface coated vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an inside surface coated vessel which is free of blowholes in the coating films near the seaming sections of the body and bottom plate or top plate of the inside surface of the vessel. SOLUTION: The method of manufacturing the inside surface coated vessel having a process step of heating and melting a resin powder coating material to be electrostatic applied to the inside surface of the vessel and a process step of cooling the vessel after the heating and melting process step has a repair process step of the inside surface coating resin between the heating and melting state and the cooling process step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an inner surface coated container and an inner surface coated container manufactured by the manufacturing method.

[0002]

2. Description of the Related Art In a container filled with contents such as various liquids and powders, a method of coating and coating the inner surface of the container is widely used in order to prevent the contents from being contaminated and the container from being corroded. In such a container having an inner surface coated, it is desired that the filled contents have a good discharge property. When the container is used repeatedly, it is desired that the previous contents do not remain in the container when the contents such as liquid are filled next time.

For example, in the case of a drum can, after winding a body and a base plate or a top plate to form a cup-shaped can, a polyethylene powder paint is electrostatically powder coated on the inner surface to protect the inner surface, and heated. A method of heating and melting in a furnace to form a polyethylene coating film is known. Also, apply polyethylene powder paint to the body and the base plate or top plate in advance by electrostatic powder coating, and heat and melt in a heating furnace to form a polyethylene coating film. It is also known to perform heating and melting again in order to carry out the deposition. Further, there is also a method in which a body and a base plate or a top plate are formed from a laminated steel plate, and after winding and tightening, heating and melting are performed to fuse the winding and tightening portion.

[0004]

However, after the above-mentioned body and the main plate or the top plate are wound and fastened, the inner surface of the drum can is electrostatically powder-coated with polyethylene powder paint, and the container is heated in a heating furnace to form a polyethylene coating film. Blow holes may be generated in the winding tightening portion when forming the. This is because the slight gas existing between the particles of the polyethylene powder coating applied to the wedge-shaped gap between the body and the base plate or top plate during electrostatic powder coating expands and melts due to the heating in the heating furnace. By pushing up the polyethylene coating film, bubbles are generated between the metal surface of the drum and the coating film, and the resin pushed up by the bubbles bursts during cooling, forming blowholes that are open to the outside. This is because. In addition, even if the resin pushed up by the bubbles does not burst during cooling, the coating film where the bubbles are generated is thin and the mechanical strength of the coating film is weak, causing the coating film to peel off during use. Will also be.

In the case where the body and the base plate or the top plate are electrostatically powder-coated with a polyethylene powder coating material in advance and heated and melted in a heating furnace to form a polyethylene coating film, which is wound and fastened, or laminated. In the case where the body and the base plate or the top plate are formed by steel plates and wound, the step of heating and melting the resin of the winding portion is necessary to fill the wedge-shaped gap of the winding portion. Similarly, there is a problem that air bubbles are generated in the blow-fastened portion or the coating film at the winding tightening portion.

The presence of such blow holes or air bubbles in the coating film lowers the barrier property of the coating film, and depending on the content, the inner surface of the drum can is corroded or the content is contaminated, and the content is blown. There is a problem that it remains in the holes and deteriorates the discharge performance.

In order to prevent the formation of blowholes and air bubbles in the coating film, a method of filling the wedge-shaped gap with a substance having a large fluidity at the time of melting to reduce the amount of air or a substance having a small fluidity at the time of melting is used. A method is conceivable in which the air layer in the wedge-shaped gap is hardened and covered so that the expansion and contraction of gas due to heating and cooling does not affect the polyethylene coating film.

However, the method of filling the wedge-shaped gap with a substance having a large fluidity at the time of melting to reduce the air layer has a practically limited fluidity and its effect is not sufficient. Further, in any of the above methods, a complicated step of previously filling the wedge-shaped gap with another substance is required, which causes a problem of increasing the step and cost.

The present invention has been made in order to solve the above problems, and is free from blowholes in the coating on the body of the inner surface of the container and near the winding portion of the main plate or the top plate, and has a good barrier property. It is an object of the present invention to provide a method for manufacturing an inner surface coated container.

[0010]

The features of the present invention for solving the above problems are as follows.

According to the first aspect of the present invention, there is provided an inner surface coated container having a step of heating and melting a resin powder paint electrostatically coated on the inner surface of the container, and a step of cooling the container after the heating and melting step. It is a manufacturing method, and has a repair process of an inner surface coating resin between the heating and melting step and the cooling step.

According to a second aspect of the present invention, there is provided a method for manufacturing an inner surface coated container constituted by joining two or more resin-coated members, wherein at least the coating resin on the inner surface of the container is melted by heating. And a step of cooling the heated and melted coating resin, and an inner surface coating resin repairing step between the heating and melting step and the cooling step. Is the way.

According to a third aspect of the present invention, in the second aspect, the resin coating is a coating film or a laminate coating obtained by heating and melting an electrostatically coated resin powder coating material. It is a manufacturing method of an inner surface covering container.

The invention of claim 4 is the first to third aspects of the invention.
4. The inner surface coated container according to claim 1, wherein the repairing step is performed while the temperature of the inner surface coated resin is equal to or higher than the softening point of the resin. It is a manufacturing method.

The invention of claim 5 relates to claims 1 to 4.
An inner surface coated container manufactured by the method for manufacturing an inner surface coated container according to any one of 1.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for manufacturing an inner surface coated container according to the present invention will be described below.

FIG. 1 is a process chart showing an example of a manufacturing process of an inner surface-coated metal drum can.

In the case of manufacturing a metal drum having an inner surface coated, first, the top plate and the body are molded. Next, the top plate and the body are subjected to chemical conversion treatment. The chemical conversion treatment is performed, for example, by degreasing or blasting the top and bottom plates and the inner surface of the body, if necessary, and then performing a phosphate treatment such as zinc phosphate or iron phosphate or a chromate treatment. In addition, when using a surface-treated steel plate etc. for a top and bottom board, the said chemical conversion treatment is not necessarily required.

Thereafter, the body and the base plate (top plate in some cases, the same applies hereinafter) are wound and tightened to form a cup-shaped can.

Undercoating is applied to the inner surface of the cup-shaped can thus formed. As the undercoating, for example, it is preferable to coat with an epoxy resin-based, phenol epoxy resin-based or epoxy polyester resin-based paint, and the coating thickness of the undercoating is about 0.1 to 50 μm. It is desirable that the thickness is about 1 to 10 μm. In addition, the step of the base coating may be performed before the step of winding and tightening the body and the base plate (the top plate in some cases, the same hereinafter). Moreover, when using a pre-coated steel plate for the top and bottom plates and the body, the above-mentioned base coating step is not always necessary.

The base coating is preferably carried out in order to improve the adhesion with the coating applied thereon and further improve the corrosion resistance of the inner surface of the drum can.
It is also possible to omit the base coating depending on the purpose of use of the drum.

Next, electrostatic powder coating with resin powder coating is performed on the base coating (or directly on the inner surface of the drum if the base coating is omitted). Examples of the resin used for the resin powder coating material include polyethylene, polypropylene, nylon, fluorine-based, polyester, ethylene vinyl acetate copolymer,
A resin containing one or more resins selected from ethylene ethyl acrylate, vinyl chloride and modified resins thereof is preferable. The average film thickness of the coating film after melting of the electrostatic powder coating is preferably about 10 to 2000 μm, more preferably about 50 to 500 μm. Further, the coating film may be used as a single layer, or may be used as a multilayer having two or more layers. When electrostatic powder coating is performed, in order to reduce or eliminate the wedge-shaped gap between the body and the main plate, the wedge-shaped gap is sufficiently filled with the resin powder paint, that is, the body and the main plate are tightened. It is preferable to thicken the vicinity of the portion.

The drum that has been subjected to the electrostatic powder coating is then placed in a heating furnace or the like, and heated and melted at a temperature not lower than the melting point of the resin used for the resin powder coating. As a result, the applied resin forms a smooth coating film on the inner surface of the drum.

After the heating and melting, the drum can is
Next, proceed to the repair process. In the electrostatic powder coating process, a slight gas present between the particles of the resin powder coating applied to the wedge-shaped gap between the body and the base plate expands due to the heating in the heating and melting process, and the molten resin coating film Push up,
Bubbles may be generated between the metal surface of the drum can and the coating film or in the coating film, or the bubbles may burst to leave a rupture hole. When the next cooling step is performed with the bubbles still generated, the resin on the bubbles bursts due to the difference in shrinkage ratio between the metal of the drum can and the coating resin during cooling, the metal surface of the drum can is exposed, and blow holes are generated. Cause Further, the rupture holes become defects in the coating film as they are after cooling.
Even when the resin on the bubbles does not rupture during cooling, the coating film in that portion becomes thin, resulting in deterioration of the barrier property of the coating film.

Therefore, by removing the bubbles or repairing the rupture holes in the repairing step before proceeding to the cooling step, the occurrence of defects in the coating film such as blowholes in the cooling step can be prevented, and the coating film such as blowholes can be prevented. A metal drum having a good barrier property without defects can be obtained.

As a method of removing the air bubbles, for example, the coating film in the drum can, particularly in the vicinity of the wedge-shaped gap between the body and the ground plate, is visually observed, and a hole is formed in a portion where the coating film swells due to the generation of air bubbles. It can be performed by opening the chamber to remove the internal gas, pressing the coating film with a rod-shaped device or the like, or by locally blowing high-temperature and high-pressure air from a nozzle to locally heat. Here, as the rod-shaped device,
It is preferable to use a material having poor adhesion to the coating resin, for example, aluminum, or a material having a mechanism capable of cooling the contact portion with the coating film so as not to adhere to the coating film. preferable.

As a method for repairing the rupture hole, the hole may be closed by using the rod-shaped device so that the surrounding resin may be collected, or a resin extruding machine for separately melting a resin to be fused with a coating film prepared separately. For example, it may be injected and closed. The same resin as the coating film is preferably used as the resin fused to the coating film.

The air bubbles are removed preferably at a temperature above the softening point of the resin powder coating, which is the temperature of the coating resin which is heated and melted on the metal surface of the drum can and coated on the inner surface thereof, and the softening point temperature plus 10 ° C. It is more preferable to carry out at a temperature of about a certain level or higher. By punching and pressing the part where the coating film is swollen at a temperature above the softening point of the applied resin powder coating, or by repairing the rupture hole, the adhesion with the metal surface of the drum can is further improved, This is because a metal drum having no coating film defects such as blowholes can be obtained, and by further performing the softening temperature plus about 10 ° C. or higher, the adhesion is improved and the flatness of the resin surface is further improved. Here, the softening point refers to the softening point defined in JIS K6760.

After the removal of the air bubbles, the metal drum can is next cooled to room temperature.

The metal drum, which has been cooled to the room temperature, is then carried into a clean room and the coating film is inspected for the presence of coating film defects such as blow holes.

For the drums that have passed the coating film inspection, the top plate (base plate if necessary) is tightened in a clean room. In addition, when further processing is performed, it is carried to the next process.

In the above embodiment, the body and the base plate are wound together to form the cup-shaped can, and then electrostatic powder coating is performed with the resin powder coating material. The present invention can also be applied to an inner surface coated container manufactured by winding and fastening the base plate.

2 and 3 are views showing an example of a manufacturing process of an inner surface coated container manufactured by winding and tightening a body and a main plate which are resin-coated in advance, and FIG. In the case of a coating film obtained by heating and melting an electrostatically coated resin powder coating material, FIG. 3 is a process diagram in the case where the resin coating is laminated. 2 and 3
In FIG. 1, the same steps as those in FIG.

In the case where the body and the base plate which are previously coated with resin are fastened, the resin coating is a coating obtained by heating and melting a resin powder coating which has been electrostatically coated, and a laminated coating. In either case, a heating and melting step of heating and melting the resin of the winding fastening portion is required after the winding step of the body and the main plate to fill the wedge-shaped gap of the winding fastening portion. It should be noted that this heating and melting step can be carried out by placing it in a heating furnace or the like as in the heating and melting step after electrostatic powder coating. It is also possible to melt only the vicinity of the tightened portion.

As the method of locally heating, for example, a method of blowing high-temperature and high-pressure air from a nozzle, a method of induction heating, a method of using a heater, a method of applying a flame such as a burner, or the like can be used.

Also in the heating and melting step after the body and main plate winding step, similar to the heating and melting step after electrostatic powder coating in FIG. 1, the metal surface and the coating film of the drum can near the winding section are removed. Bubbles may be generated during the period or in the coating film, or the bubbles may burst to leave rupture holes. If this is left unattended, the same problem as described with reference to FIG. 1 is caused. Therefore, before proceeding to the next cooling step, the bubbles are removed or the rupture holes are repaired in the repairing step, so that the blow hole in the cooling step, etc. It is possible to obtain a metal drum can having a good barrier property, in which the occurrence of defects in the coating film is prevented, and there are no coating defects such as blow holes.

As the bubble removing method and the rupture hole repairing method, the same methods as described with reference to FIG. 1 can be used.

Needless to say, the method described in this embodiment is not limited to the metal drum can and can be applied to all inner surface coated containers manufactured by winding or welding two or more members.

[0039]

As described above, according to the present invention, an inner surface coated container having no coating defects such as blow holes in the coating on the inner surface of the container and in the vicinity of the winding fastening portion of the main plate or the top plate is manufactured. be able to.

[Brief description of drawings]

FIG. 1 is a process chart showing an example of a manufacturing process of an inner surface-coated metal drum according to the present invention.

FIG. 2 is a view showing an example of a manufacturing process of an inner surface coating container manufactured by winding and tightening a body and a main plate which are resin-coated in advance according to the present invention, in which the resin coating is electrostatically coated resin powder. It is process drawing in case it is a coating film obtained by heat-melting body paint.

FIG. 3 is a diagram showing an example of a manufacturing process of an inner surface coated container manufactured by winding and fastening a pre-resin-coated body and a base plate according to the present invention, in which the resin coating is laminated. It is a process drawing of a case.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 5/03 C09D 201/00 201/00 B65D 1/00 B (72) Inventor Toyofumi Fuga Tokyo Central Ginza 8-11-11, Ginza Steel Pipe Drum Co., Ltd. (72) Inventor Tetsuhiro Koike 8-11-11 Ginza, Chuo-ku, Tokyo Steel Pipe Drum Co., Ltd. (72) Inventor Hisao Uchiyama Ginza, Chuo-ku, Tokyo 8-11-11 Steel Pipe Drum Co., Ltd. (72) Inventor Yoshinori 圷 8-11-11 Ginza, Chuo-ku, Tokyo Steel Pipe Drum Co., Ltd. F-term (reference) 3E033 AA06 BA08 EA10 4D075 AA09 BB18Z BB29Y BB33Y BB34Y BB35Y BB36Y BB93Y DA06 DA15 DA19 DA27 DB01 DC42 EA02 EA15 EA17 EB13 EB15 EB16 EB19 EB22 EB32 EB33 EB35 EB39 4J038 CB081 CD021 CG141 CJ011 DD001 DH001 PA03 PB04 PC02

Claims (5)

[Claims] 1. A method for producing an inner surface coated container, comprising: a step of heating and melting a resin powder paint electrostatically coated on the inner surface of the container; and a step of cooling the container after the heating and melting step. A method for producing an inner surface coated container, comprising a step of repairing an inner surface coating resin between the heating and melting step and the cooling step. 2. A method for manufacturing an inner surface coated container, which is constituted by joining two or more resin-coated members,
There is a step of heating and melting the coating resin of at least the joint portion on the inner surface side of the container, and a step of cooling the coating resin that has been heated and melted, and between the heating and melting step and the cooling step, A method for manufacturing an inner surface coated container, comprising a repair step. 3. The inner surface coated container according to claim 2, wherein the resin coating is a coating film obtained by heating and melting an electrostatically coated resin powder coating material or a laminate coating. Production method. 4. The inner surface coated container according to any one of claims 1 to 3, wherein the repairing step is performed while the temperature of the inner surface coated resin is equal to or higher than the softening point of the resin. Production method. 5. An inner surface coated container manufactured by the method for manufacturing an inner surface coated container according to any one of claims 1 to 4.