JPH02194871A - Coating apparatus - Google Patents

Abstract

PURPOSE:To improvement a coating efficiency by arranging a compressed air delivery opening A and a delivery opening B for the compressed gas containing hardening accelerator, so that the gases delivered from these openings will not impinge against an injection opening. CONSTITUTION:The subject apparatus is provided with a liquid injection opening 1 and gas delivery openings, i.e., a first pair of gas delivery openings 2 adjacent to the opening 1 and a second pair of gas delivery openings 3 located exteriorly of the openings 2. The openings 2 and 3 air in communication with a compressed air source and a compressed gas source for supplying the gas containing a hardening accelerator, respectively. The delivery openings 2 and 3 and the injection opening 1 are so arranged as not to cause the gases from the openings 3 to impinge against the opening 1. As a result, even in the application of a liquid such as coating material rapidly cured in the presence of the hardening accelerator, there are no nozzle clogging and flisters of coating film. Therefore, this coating apparatus permits the application of rapid cure coating material with improved coating efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coating apparatus, and more particularly to a coating apparatus suitable for coating a liquid material that hardens rapidly in the presence of a curing accelerator.

(Prior art and its problems) In recent years, plastics have been widely used as materials for automobile parts and home appliances from the viewpoint of weight reduction and rust prevention.

In coating plastics, there is a strong demand for forming coating films at low temperatures from the viewpoint of heat resistance, and a catalytic vapor mixed coating system is used as one of the coating methods. The catalytic vapor mixed coating system is a method in which a two-component urethane resin paint is rapidly cured by the catalytic action of amine vapor, and the two-component urethane resin paint is mixed with a two-component urethane resin paint whose main components are polyol and incyanate. The paint, whose viscosity has been adjusted with a solvent, is atomized using a general air spray gun using mixed air containing amine vapor generated by an amine generator, and then sprayed onto the object to be coated. The sprayed paint is rapidly cured by the catalytic action of the amine, forming a urethane resin coating.

Although this catalytic vapor mixed coating system achieves the intended purpose of low-temperature curing, there is still a need for further low-temperature curing (
There are demands for rapid curing (at room temperature), thicker films, and improved coating efficiency. Although coating is performed with high viscosity, there is a tendency to increase the viscosity of the coating, that is, to make the coating highly solid during coating, and a coating machine or coating method with high coating efficiency is required.

In order to achieve the above object, the inventors of the present invention have intensively studied the combination of the catalytic vapor mixed coating system and the air mix method as a means of applying the catalytic vapor mixed coating system to high viscosity (high solid content) paints.

The air mix method is a method of inserting air from around the spray gun in the airless painting method.It prevents the occurrence of tails, which are defects in airless painting, and also reduces the spray pressure of the paint because it promotes atomization of the paint. Conventional 100-1
20 kg/am” to 40 to 70 kg
This coating method has been widely used recently because it can reduce the pressure to as low as g/cm2.

A method of applying a catalytic vapor mixed coating system to the air mix method is to use amine mixed air mixed with amine, which is a curing accelerator, instead of air in the air mix coating method (Airless Air). + amine mixed air) A different coating method can be considered. However, when applying a high viscosity (high solid content) paint that hardens rapidly with amine using a coating method in which air is simply replaced with amine mixed air (airless + amine mixed air), the liquid nozzle gets clogged. For example, it has been found that stable painting cannot be achieved because the nozzle becomes clogged, or the paint particles that accumulate in the nozzle come off and cause spots in the paint film.

(Means for Solving the Problems) The present invention was achieved as a result of research aimed at providing a coating machine for improving the above-mentioned points.

That is, the present invention provides a liquid material applicator having a spout for spouting a liquid material and a spout for spouting a gas, in which the spout is connected to a first set of spout ports disposed near the spout. and a second set of outlets disposed outside the first set of outlets, the first set of outlets communicating with a source of compressed air, and the second set of outlets communicating with a compressed air source. The outlet is adapted to communicate with a compressed gas source supplying a gas containing a curing accelerator, and the first set of outlets, the second set of outlets, and the outlet are connected to the first set of outlets. The present invention relates to a coating apparatus characterized in that the gas ejected from two sets of ejection ports is arranged so as not to hit the ejection ports.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings of one example.

FIG. 1 is a cross-sectional view of the vicinity of the liquid material spout of an apparatus showing an embodiment of the present invention, in which the liquid material under high pressure is
The compressed air is ejected from the liquid material ejection port I, passes through the compressed air communication path, and is injected from the ejection port 2 near the liquid material ejection port I at an injection angle θa, and the injected compressed air is ejected. surrounding the liquid. Further, compressed gas containing a curing accelerator is injected from the discharge ports 3 around the vicinity (outside the vicinity). As a result, the area around the injection port 1 is sealed by compressed air, and the compressed gas containing the curing accelerator does not come into close contact with the injection port 1. The air is mixed, and this mixed gas comes into contact with the injected liquid material and is applied to the object to be coated.

Therefore, the liquid material adhering to the nozzle forming the injection port 1 will not harden rapidly, which will prevent the nozzle from clogging or causing spots in the coating film. Rapid curing is possible because of the contact with the curing accelerator.

An example of coating using a coating apparatus having the structure shown in FIG. 1 will be described below. A two-component acrylic urethane resin paint containing acrylic polyol and an isocyanate crosslinking agent as the main components, which hardens rapidly at room temperature in the presence of an amine, is coated with a solvent to a viscosity of 25 to 45 seconds/Ford Cup No. 4. After thickening,
The paint was sucked in by a Zuranger pump, and the pump applied a pressure of 40 to 70 kg/cm" to the paint, which was then pumped to the spray gun. Compressed air with a pressure of 0.1 to 1 kg/am" was also compressed by a compressor. was sent to the compressed air passage. Further, 1 to 8000 ppm of amine vapor, which is a curing accelerator, preferably 10 to 20
Pressure 0.5-2kg/am2 containing concentration of 00ppm
of compressed air (compressed gas) was sent to the compressed gas communication path.

Then, the paint, compressed air, and amine-containing compressed gas were simultaneously injected under conditions of a paint discharge rate of 600 to 1000 cc/min, and coating was performed to a coating film thickness of 50 to 100 microns. Although the painting was carried out for about 30 minutes, since the amine vapor does not come into close contact with the jet nozzle 1, the liquid material adhering to the jet nozzle 1 does not harden rapidly, which may cause nozzle clogging or cause the paint film to deteriorate. There were no bumps inside.

Note that the injection angle θa of the compressed air from the discharge port 2 is 10 to 9.
0°, preferably 30° to prevent blowback.
~506. Also, when stopping the spraying of paint, you can stop the spraying of compressed air and compressed gas at the same time +1m, but
It is preferable to continue spraying the compressed air even after the spraying of the paint and the compressed gas is finished, so as to keep the amine vapor further away from the vicinity of the spray nozzle of the paint.

As the compressed gas, compressed air containing curing accelerator vapor is generally used, but nitrogen gas, carbon dioxide gas, oxygen gas, helium gas, neon gas, etc. can be used as appropriate instead of air. The liquid material to be coated is one that hardens rapidly in the presence of a hardening accelerator, for example, 0.1~
Although the apparatus of the present invention is highly effective for liquid materials that harden in 20 minutes, the apparatus of the present invention can also coat liquid materials that require a little more time to harden.

Further, the curing accelerator may be any one as long as it accelerates the curing of the liquid material to be applied, and those that accelerate curing rapidly and are easily vaporized are particularly preferred.

FIG. 2 is a sectional view of the vicinity of the liquid material spout of a device showing a more preferred embodiment of the present invention, and the tip of the liquid material spout is located very close to the liquid material spout. , and has a structure that is recessed from the periphery of the jet port surrounding the jet port. It is preferable that the degree of depression from the periphery of the jet nozzle to the tip of the jet nozzle l is 1 to 10 mm,
The presence of the recesses more reliably prevents contact with the curing accelerator-containing compressed gas. Moreover, if the recessed portion is more than 10 mm, there is a possibility that the spray pattern when the liquid material is ejected will be adversely affected. Moreover, the injection angle θb of the compressed gas from the discharge port 3 is preferably 0 to 80°.

FIG. 3 is a left side view of FIG. 2.

The shape of the discharge port for compressed air or compressed gas may be circular, slit-shaped, or ring-shaped. It is preferable that a so-called air curtain be formed surrounding the jet port 1 of the compressed air discharge port so as to prevent the compressed gas containing the curing accelerator from coming into contact with the jet port a1 by the jetted compressed air.

FIG. 4 is a sectional view of the vicinity of the liquid material spout of an apparatus showing a more preferable embodiment of the present invention, similar to FIG. Through,
It reaches the discharge pipe 6 and is injected from the discharge port 3. When compressed gas is injected, the surrounding air is drawn in, but because there is a space around the discharge port 3, especially at the rear, where air can freely circulate, the surrounding air when compressed gas is injected from the discharge port 3. The flow of air becomes smooth, turbulence is less likely to occur, and the curing accelerator is more reliably prevented from flying into the vicinity of the spout 1. FIG. 5 is a left side view of FIG. 4.

(Operation and Effects of the Invention) When the device of the present invention is used, no nozzle clogging or lumps will occur in the coating film even when coating a liquid material such as a paint that hardens rapidly in the presence of a curing accelerator. , it is possible to apply a liquid material that hardens rapidly, improving painting workability.

In addition, since it is an airless coating, it is possible to coat liquid materials with high viscosity (high solid content), and it is also possible to achieve thicker films and improved coating efficiency.

[Brief explanation of the drawing]

1, 2, and 4 are sectional views of the vicinity of the liquid material spout of an apparatus according to an embodiment of the present invention, and FIG. 3 is a left side view of FIG. 2, and FIG. is a left side view of FIG. 4. l...liquid material spout, 2...compressed air discharge port,
3... Discharge port for compressed gas containing a curing accelerator; 4.
...Difference in height between the tip of the liquid jet nozzle and the peripheral part of the jet nozzle, 5: Transfer pipe, 6: Discharge pipe of compressed gas containing a curing accelerator, θa: Compressed air injection angle, θb・
...Injection angle of compressed gas containing curing accelerator. Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In a liquid applicator having a spout for spouting a liquid and a spout for spouting gas, the spout is arranged in the vicinity of the spout. a second set of outlets disposed outside the first set of outlets, the first set of outlets communicating with a source of compressed air; The discharge ports of the first set of discharge ports, the second set of discharge ports, and the jet ports are configured to communicate with a compressed gas source that supplies a gas containing a curing accelerator. A coating device characterized in that the coating device is arranged so that the gas discharged from the second set of discharge ports does not hit the jet ports. 2. The direction in which the air is discharged from the first set of discharge ports is a direction that intersects a plane perpendicular to the direction in which the liquid material is jetted from the jet ports at an angle of 10 to 90 degrees. Painting equipment described. 3. The coating device according to claim 1, wherein the tip of the spout is recessed relative to its periphery.