JPS6341629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating method that allows continuous coating at high speed without loss of paint, is simple in terms of equipment, and has fewer problems such as breakdowns. Conventionally, many methods have been known for coating glass containers, such as those for carbonated beverages, with synthetic resin, synthetic rubber, etc. for the purpose of preventing breakage of glass containers and preventing glass pieces from scattering when broken.

One example is polyethylene in glass containers.
A method of contracting polypropylene, Surlyn, etc. to tightly engage them (Japanese Patent Application Laid-Open No. 12148/1983), hydroxyl group,
A container coated with an olefin copolymer having at least one of a carboxyl group and an acetoxy group by powder coating (Japanese Patent Publication No. 47-23882), a first layer of rubber or synthetic resin on an untreated or primer-treated glass container and a second layer of synthetic resin on the outside (Japanese Patent Application Laid-open No. 1973-
55210, JP-A-48-65214, etc.).
A wide variety of polymer materials are used, including thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyamide, and thermosetting resins such as melamine resin, epoxy resin, and polyurethane resin. The required physical properties include a coating that prevents scratches due to friction, etc., prevents breakage, and does not scatter glass fragments even if a glass container with internal pressure, such as a carbonated drink, is damaged by impact or the like. Furthermore, the film must be durable against hot and cold water, alkaline aqueous solutions, etc. that accompany repeated use of glass containers. In order to provide a film that meets these requirements, thermosetting resins are desired rather than thermoplastic resins as coating resins. Moreover, the coating applied to the glass container must have a constant thickness and have a good appearance. Therefore, as a coating method, a coating method with good quantitative properties is desirable. In addition, for the purpose of saving labor, it is desirable to reduce the number of times of coating and form a coating film to a predetermined thickness, so with liquid coating agents, the solid content of the coating agent increases, which inevitably results in a high viscosity. There is a tendency to Furthermore,
A non-polluting coating agent is desired, a solvent-free coating agent is preferred, and a liquid coating agent generally has a high viscosity.

When painting objects such as glass containers,
Multiple objects to be painted are held at intervals and painted one or several at a time.

It is desired that this coating work be performed continuously and that it can be processed at high speed. however,
When attempting to paint continuously, the object to be painted exists intermittently, so if the paint is continuously supplied to the object, one must be prepared for loss of the paint. Furthermore, in the case of a reaction-curing type coating agent in which the coating agent is a liquid, it is impossible to recover and reuse the lost coating agent, resulting in contamination of the coating equipment. The same can be said for dip coating. Further, in the case where the coating agent is intermittently supplied in synchronization with the object to be coated, the automation device becomes large-scale.

Brushing and dipping are effective methods for applying paint to objects such as glass containers, but they are effective when the viscosity of the paint is low; however, with high viscosity paints, it is difficult to form a uniform film. It is difficult to perform painting at high speed. The spray painting method is suitable for low viscosity paints,
In general, there is a large loss of paint due to scattering, and it also contaminates the coating equipment, making it difficult to apply at room temperature with a highly viscous paint, so the viscosity of the paint must be reduced by heating or using a solvent. With the flow-down coating method, it is possible to coat even high-viscosity paints, but if the object to be coated is continuous, this is not a problem, but if the object to be coated is intermittently present, it is possible to coat even with a highly viscous coating agent. To paint, the flow of paint must be synchronized and carried out intermittently, requiring extensive automated equipment.
It is expensive, complex, has many problems such as failure, and has the disadvantage of being inferior in painting speed. When coating intermittently using a coating agent that reacts quickly and hardens easily, a portion of the coating agent tends to adhere to the nozzle outlet or the like, causing the nozzle to become clogged.

As mentioned above, in any of the painting methods, when painting multiple objects to be painted that are continuously moving and arranged at regular intervals, effective use of the paint agent (no loss), high-speed painting, formation of a uniform coating film, There are few methods that satisfy all conditions such as simplifying the coating equipment.
There has been a demand for a coating method that satisfies the above conditions, especially in coating using a high viscosity liquid coating agent.

The present invention is a method that enables continuous coating at high speed, eliminates waste of coating agent, is extremely simple in terms of equipment, and has fewer failures.

That is, the present invention allows a coating agent to flow down continuously almost vertically, and rotates a plurality of glass containers arranged at regular intervals around the rotational axis while holding the rotational axis horizontally. This is a continuous coating method for glass containers, characterized in that the glass containers are moved through a falling coating area and one or more glass containers are substantially constantly present in the falling coating area. The paint is continuously poured down,
Since there is no need to stop the flow of paint according to each object to be painted, the equipment is not only simpler and cheaper, but also has faster painting processing capacity and is faster than conventional painting methods. Non-uniformity in film thickness caused by pooling of paint at the tip of the nozzle due to stopping the flow of each agent is eliminated, and a smooth film can be obtained.

The paint can be flowed down using multiple tubular nozzles vertically aligned with the horizontal surface of the object to be coated, a nozzle with multiple small tubes branching vertically from a substantially horizontal tubular nozzle, or a small hole in the bottom of the container. It may flow down from a nozzle substantially vertically in a shower-like manner, or atomized paint may be flown by air spray or airless spray methods, or curtain flow coater from a slit-shaped nozzle or from a horizontal surface. It can also be used with a flow coater using the overflow method. It is also possible to use a method of dropping the powder coating agent from a cylindrical brush, a rod-shaped brush, a mesh-shaped container, or the like. Note that the flow according to the present invention includes not only cases where the flow is completely vertical, but also cases where the flow is slightly inclined from the vertical, and cases where the flow flows down with a certain extent.

As the coating agent according to the present invention, both solvent type (organic solvent, water) and non-solvent type (liquid and powder) can be applied. Thermoplastic resins include polyethylene,
polypropylene, polystyrene, acrylic resin,
These include vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyamide, polyester, polycarbonate, silicone resin, polyether resin, and cellulose derivatives. Examples of thermosetting resins include melamine resin, urea resin, epoxy resin, silicone resin, polyurethane resin, and xylene resin.
Further, as the rubber, natural rubber and synthetic rubber can be used. Among these, as described above, thermosetting resins are more preferred, and among thermosetting resins, polyurethane resins are suitable for strengthening glass containers to be coated. The amount of coating varies depending on the object to be coated and the purpose of coating, but is usually 10 to 500μ (microns).
(dry coating film).

The flow down method varies depending on the paint used,
For example, solvent-free, solvent-based, or emulsion-type coating agents such as reaction-curing urethane resins or epoxy resins have one or more vertical tubular nozzles or a horizontal tubular nozzle that branches vertically into a plurality of small tubes. Painting from a tubular or small-hole nozzle is preferable, and for low-viscosity coatings that use reaction-curing resins and have a long pot life, air spray, airless spray, curtain flow coaters, and overflow coaters can be used. It can also be painted by In addition, thermosetting resin powder coatings such as epoxy resin powder coatings and urethane resin powder coatings, and thermoplastic resin powder coatings such as polyethylene, polypropylene, and polystyrene are obtained from cylindrical or rod-shaped brushes, or from mesh-shaped containers. Due to these rotations or vibrations, the powder coating material can be applied by flowing down substantially uniformly. There are no particular restrictions on liquid coating agents made of thermoplastic resins, and various pouring methods can be applied.

The object to be painted is something whose central axis can rotate symmetrically, such as the surface of a rod, cylinder, bottle, or can, and the objects to be painted are continuous at regular intervals to the extent that they do not touch each other. While rotating, each of them is directly supplied to the falling coating area of the coating agent and is coated.

As an example of such a method of arranging a plurality of objects to be coated at regular intervals, glass bottles are placed on rotatable bottle holders attached at regular intervals to an endless conveyor chain that moves three-dimensionally. Hold the mouth of the bottle in the bottle holder so that the long axis of the bottle is horizontal. To coat the glass bottles with the paint, the bottle holder is rotated as necessary, and each bottle is rotated around the long axis of the bottle, while a conveyor passes through the falling coating area of the paint. and then painted. At this time, the conveyor speed and the number of rotations of the bin can be varied as necessary. Hold the glass bottle horizontally
By rotating, it is possible to form a uniform coating film and cause leveling.

In the present invention, the falling coverage area refers to an area where the coating agent can be applied to a part or the entire surface of the object in the direction in which the coating agent flows down.

Next, the continuous coating method of the present invention will be explained with reference to the drawings. 1 and 4 to 7 are side views showing an outline of an embodiment of the present invention. Figure 2 is Figure 1A-
It is an A-line sectional view. FIG. 3 is a partially enlarged view of FIG. 1. In FIG. 1, a plurality of objects 2 to be coated, which are rotatably held horizontally at regular intervals on a conveyor 1, are moved obliquely to a coating material 4 that is flowing down almost vertically from a coating material flowing down means 3. The inclination of the conveyor in the falling coverage area varies depending on the moving speed of the conveyor and the spacing of the objects to be coated, and is designed so that the coating agent does not flow down to areas other than the objects to be coated.
That is, the object to be coated is moved so that it is substantially constantly present in the falling coverage area. Note that even if the object to be painted does not exist in the falling coverage area for a very short time, depending on the type of coating agent, some of the flowing down of the coating agent may be caused by the object that was present in the falling coverage area immediately before. Since it can be bent, it is possible to prevent loss of paint.

FIG. 2 shows the flow means 3 using a nozzle. Although one nozzle is shown in FIG. 2, a plurality of nozzles may be used depending on the shape of the object to be coated. Moreover, a flow means such as a curtain flow coater may be used instead of a nozzle.

FIG. 3 is a partially enlarged side view of FIG. 1 for explaining the falling coverage area, and shows a state in which the object 2 to be coated, indicated by a dotted line, moves from position 5 to position 6. While moving from position 5 to position 6, the object 2 to be coated is rotated at least once. The object to be coated 2 is moved vertically from the part 7 where the coating agent 4 comes into contact with the object 2 to be coated for the first time (the position where the object 2 is farthest from the flowing means 3 in the vertical direction) to the flowing means 3 in the vertical direction. The area indicated by the dotted line in which the coating agent flows down almost vertically between the painted parts 8 of the object 2 at the closest position 6 is the falling coverage area in the case of FIG.

FIG. 4 shows the object 2 to be coated being moved vertically from bottom to top with respect to the flowing down means 3 for the coating material 4, and the object 2 to be coated which has been coated being moved horizontally so as to exit the falling coating area. This is the method. Note that the method of leaving the downstream coverage area is not limited to horizontal movement, but may also be diagonal movement.

FIG. 5 shows an embodiment in which the number of flow means 3 for the coating material 4 is increased from one to three. All the coating agents from the respective flow down means 3 may be the same, or the coating agents 4 from the respective flow down means 3 may be different.

FIG. 6 shows a coating method in which the coating material 4 is atomized by the falling means 3 using a spray gun and continuously discharged directly downward while the object to be coated is continuously moved obliquely upward by a conveyor. In general spray painting, the paint scatters a lot, but in the method of the present invention, the spray gun is moved as close to the object to be painted as possible.
Due to the smaller spread of the coating material and the presence of the object to be coated over the spread of the coating material, losses are reduced.

FIG. 7 shows that the powder resin paint 4 is caused to flow down from the wire-mesh-like outlet 10 by the rotation of the rod-shaped brush 9, and the bottle is continuously moved by a conveyor through the area covered by the paint. In the case of powder coating, the object to be coated is heated or a powder coating agent is applied to the object by electrostatic coating.

The method is not limited to the method shown in the above drawings; for example, the moving method of the object to be coated as shown in FIG. 7 can be combined with the flow means shown in FIG. It doesn't matter if it is in the opposite direction. Further, the number of flow means is not limited to one, and coating may be performed using a plurality of nozzles as shown in FIG. In this case, the coating area for one object to be coated may be divided and sequentially coated using a plurality of flowing means.

Considering the discharge amount of each nozzle, the position and structure of each nozzle are designed so that the coating passes through three downstream coating areas and then coats all the areas to be coated. Also, consider the coating method that suits each condition, depending on the amount of coating, the size of the object to be painted, the speed of movement, the number of revolutions of the object to be painted such as a glass bottle, the slope of movement, etc.

Figure 8 shows a glass container as an object to be painted.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view schematically showing, as an example, an entire system to which a continuous coating method according to the present invention is applied when applying a reinforced film. A plurality of glass containers 2 are held horizontally by a holder at regular intervals on an endless conveyor chain, and the glass containers 2 are allowed to move continuously while rotating. The glass container may be held in any manner as long as it can be held horizontally and rotated. The glass container is attached to the holder from position 11, and washing means 12 such as a washing tank is installed.
Wash the glass container with During washing, the glass container may be held vertically. After washing, it is sufficiently dried by the drying means 14, and a primer such as a silane coupling agent, synthetic resin, etc. is applied by the primer coating means 13, and then dried or hardened by the drying means 14. Coating may be performed using the coating method according to the present invention. Note that it is not necessary to apply primer coating. Further, a means for preheating the glass container may be provided. Next, coating according to the present invention is performed. The flowing means 3 includes a coating agent supplying means 15.
For example, in the case of a liquid coating agent made of a thermosetting resin, the two liquids from each storage tank are mixed and the flowing means 3
supply to. Note that a means for heating the coating agent may be provided. The coating agent on the coated object 2 that has been coated is dried or cured by a drying and curing means 16. A cooling means may be provided if necessary. 17
The object to be painted 2, which has been painted, is attached and detached at the position shown in FIG.
Although the glass container is always rotated during the coating according to the present invention, it is not necessarily rotated in other parts, and the rotation speed may be changed.

Example 1 Coating agent PCP-0300 (polyester polyol manufactured by Union Carbide, USA) 46.5 parts by weight PCP-0210 (polyester polyol manufactured by Union Carbide, USA) 11.6 parts by weight Isophorone diisocyanate 41.9 parts by weight Stannous octylate 0.02 parts by weight In the painting method shown in Figure 1, one glass bottle of Juanta (manufactured by the Coca-Cola Company, USA) was
Attached to the conveyor chain with 154mm, bin rotation speed 60rpm, conveyor speed 3.8m/min, tilt angle
The glass bottle is continuously moved at an angle of 77 degrees, and the amount of discharge is -
The paint was allowed to flow down almost vertically at a rate of 500 g/min, and 20 g of the paint was applied to one glass bottle, forming a coating film of approximately 220 μm. The coating agent was baked in a propane gas oven at 180°C for 12 minutes.

Since the coating can be performed by continuously flowing down the coating agent, the equipment can be simplified and there is no loss of the coating agent. A uniform coating film could be formed on the obtained coating bottle.

Example 2 Instead of the coating method of Example 1 (Fig. 1), the 4th coating method was used.
This was done using the painting method shown in the figure. The conveyor chain was changed from vertical movement to horizontal movement with a radius of 200mm.
When coating was carried out under the same conditions as in Example 1, a uniform coating film was formed without any loss of coating agent.

[Brief explanation of the drawing]

1 and 4 to 7 are side views showing embodiments of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, FIG. 3 is a partially enlarged view of FIG. 1, and FIG. The figures each represent a side view showing an example of the entire system to which the coating method of the present invention is applied when applying a reinforced coating to a glass container. Symbols in the diagram: 1...Conveyor, 2...Object to be painted, 3...Flowing means, 4...Painting agent, 5, 6...
Position of the object to be painted to explain the falling coverage area, 7
. . . Position for explaining the falling coverage area, 9 . . . Rod-shaped brush, 10 . . . Discharge port, 11 . Drying means, 15... Painting agent supplying means, 16... Drying hardening means, 17... Desorption portion of the glass container.

Claims (1)

[Scope of Claims] 1. A method of rotating a plurality of glass containers arranged at regular intervals around an axis of rotation while holding the axis of rotation horizontally while causing a coating agent to flow down continuously almost vertically. passing through the downstream coverage area while
A continuous coating method for glass containers, characterized in that the glass containers are moved so that one or more glass containers are substantially constantly present in the falling coverage area. 2. The continuous coating method according to claim 1, wherein the coating agent is a high viscosity liquid coating agent. 3. The continuous coating method according to claim 1 or 2, wherein the coating agent is a reaction curing type coating agent. 4. The continuous coating method according to any one of claims 1 to 3, wherein a plurality of glass containers are moved at an angle with respect to the horizontal direction.