JPH11221516A - Coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the air conditioning energy necessary for coating and to improve deposition efficiently by forming a temp. and humidity controllable air curtain on the circumference of a spray pattern formed by using an atomizing nozzle. SOLUTION: The atomizing nozzle 1 is double cylinders and a suction port 2 is arranged at the center of the inside cylinder of a slit-like suction duct 3. The nozzle 5 for the air curtain is arranged along the inside wall of the suction duct 3. The temp. and humidity control air is released from this nozzle 5. The atomized coating material particles sprayed from the atomizing nozzle 1 draw the spray pattern 4 and deposit on a surface 7 to be coated while entailing the air stream 6 of the air curtain from the nozzle 5 for the air curtain of the inside cylinder of the suction duct 3, thereby forming a wet coating film 8. The duct 3 suck the solvent vapor vaporized from the atomized coating material particles and the undeposited particles together with the air. A bellows hose 9 connected to a discharge device prevents the splashing of the undeposited atomized coating material particles to the outer periphery from the duct 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method for spraying paint using an atomizing nozzle.

[0002]

2. Description of the Related Art Conventionally, spray coating using an atomizing nozzle is generally performed in a coating bush, and the inside of the coating bush is usually air-conditioned for appropriately controlling temperature and humidity. Has been made. This is because if the evaporation rate of the volatile components in the atomized paint particles in the spray pattern area greatly changes due to the temperature and humidity in the booth, the coating viscosity of the atomized paint particles is affected, and sagging and skin This is because a normal coating film cannot be formed due to defects or the like.

In spray coating using an atomizing nozzle,
Coating efficiency of airless coating using pressure nozzle is 50 ~
When the coating efficiency of air spray coating using a two-fluid nozzle is 60% and the coating efficiency is 40 to 50%, about half of the paint used is scattered particles (spray dust) that are not applied to an object to be coated. Electrostatic air spray, electrostatic airless spray, and rotating bell type electrostatic coating with improved coating efficiency are about 70 to 80%, and these 20 to 30% of scattered particles are treated and contained in the paint. In order to eliminate vapors caused by the solvent and maintain the concentration at a level that does not affect the human body, the paint booth requires forced air supply and exhaust.

Therefore, since the temperature and humidity are controlled while supplying and exhausting air in the paint bush, the energy consumed for air conditioning in the paint bus as a whole is considerable. Among them, this energy reduction was an important issue.

Further, of the spray dust and the solvent vapor contained in the air exhausted from the coating bush, the spray
The dust is removed in a gas-liquid contact treatment process or a dry filter, and the exhaust air containing the solvent vapor volatilized from the spray dust is directly diffused into the atmosphere or sent to the next step of activated carbon adsorption treatment to reduce the solvent concentration. It is below the emission standard and diffused into the atmosphere.

In the activated carbon adsorption treatment step, it is known that the higher the concentration of the solvent vapor, the higher the adsorption efficiency. However, the concentration of the exhaust air from the coating bush is usually very low and the efficiency is high. It was difficult to obtain activated carbon adsorption conditions.

On the other hand, in the case of automobile painting booths and the like, the standard of the concentration of the solvent contained in the air to be supplied is distinguished between automatic painting and hand-blown painting. By supplying clean air that does not contain solvent vapor, etc., and then using the exhaust air here as the supply air for automatic painting booths, the concentration of solvent vapor contained in the exhaust air that is finally processed Activated charcoal adsorption treatment is also performed after increasing the carbon content, but it has been insufficient.

An object of the present invention is to provide a coating method for reducing air conditioning energy required at the time of coating, and further provide a coating method with high coating efficiency and efficient exhaust air treatment. That is.

[0009]

According to the present invention, there is provided a coating method for spraying paint using an atomizing nozzle, wherein an air curtain with air capable of controlling the temperature and humidity is provided around the spray pattern. A coating method characterized by forming a coating.

[0010] 2. 2. The coating method according to claim 1, wherein a duct for sucking uncoated spray dust among the paint particles sprayed from the atomizing nozzle is provided on an outer periphery adjacent to the air curtain.

3. 3. The coating method according to claim 2, wherein the sum of the air flow rate of the air curtain and the air flow rate from the atomizing nozzle is smaller than the suction air amount of the duct for sucking the spray dust. About.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when a paint is sprayed using an atomizing nozzle, an air curtain is formed around the spray pattern by air whose temperature and humidity can be controlled. Examples of the atomizing nozzle include an air spray, an electrostatic air spray, an airless spray, an electrostatic airless spray,
Applicable to rotating bell type electrostatics.

Air whose temperature and humidity are appropriately controlled is
An air-curtain forming duct provided on the outer periphery of the atomizing nozzle or the like is sprayed almost perpendicularly to the object to be coated, and sprays the paint pattern or atomized air sprayed from the atomizing nozzle. It becomes the surrounding air curtain.

The atomizing air sprayed from the atomizing nozzle can control the ambient temperature and humidity in the spray pattern by entraining the control air of an air curtain formed around the atomizing air. Therefore, the control of the coating viscosity of the atomized paint particles can be performed in the same manner as in the conventional general air conditioning.

The atomized paint particles flying over the sheet portion of the spray pattern are corrected by the flow of the air curtain and collide almost vertically with the object to be coated. Even fine particles of 10 μm or less can be applied and can be applied, and the application efficiency is greatly improved.

In the present invention, a duct for sucking uncoated spray dust among the paint particles sprayed from the atomizing nozzle can be provided on the outer periphery adjacent to the air curtain.

When the duct is provided on the outer periphery adjacent to the air curtain, the flow of the air curtain is formed perpendicular to the substrate along the inner wall of the duct. The duct is
Usually, a slit-shaped duct opening is provided at a short distance from the surface of the object to be coated, and air flowing in a vertical direction toward the object to be coated is provided.
Ultra-fine particles of submicron order, which are not corrected and applied to the curtain flow and are not applied, are sucked from the duct port together with the solvent vapor and air such as air curtain volatilized from the atomized paint particles. Therefore, the atomized paint particles do not scatter outside the duct.

When the above-mentioned duct is provided, an air car
It is preferable that the sum of the air flow rate of the ten and the air flow rate from the atomizing nozzle be set to be smaller than the suction air amount of the duct for sucking the spray dust.

When the above-mentioned duct is provided, the solvent vapor which has volatilized from the ultrafine particles and the atomized paint particles is sucked by the required minimum amount of exhaust air in a limited area compared with the whole air conditioning. The solvent concentration in the discharged exhaust air can be adjusted to a concentration suitable for the activated carbon adsorption treatment, and it is possible to obtain processing conditions with high adsorption efficiency.

[0020]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

FIG. 1 is a sectional view of a spraying part for explaining a first embodiment of the method of the present invention, and FIG. 2 is a front view thereof.

In FIG. 1, the atomizing nozzle 1 is disposed at the center of the inner cylinder of a suction duct 3 having a double cylinder and a suction port 2 having a slit shape. An air curtain nozzle 5 is arranged along the inner wall of the inner cylinder of the suction duct 3. From the air curtain nozzle 5, air-conditioned air is supplied.
Temperature and humidity control air generated by a generator (not shown) is discharged.

The atomized paint particles (spray dust) sprayed from the atomizing nozzle 1 reach the surface 7 to be coated while drawing the spray pattern 4, and at this time, the inner cylinder of the suction duct 3 Nozzle 5 for air curtain provided along the inner wall of
The air-curtain air flow 6 formed by the air jetted from the surface arrives at the surface 7 to be coated and is applied thereto, forming a wet coating film 8. The duct 3 sucks solvent vapor and uncoated paint particles volatilized from the atomized paint particles together with air.

At this time, the suction port 2 of the slit-shaped suction duct 3 can suck in a larger amount of air than the sum of the amount of air ejected from the atomizing nozzle 1 and the amount of air in the air-curtain air flow 6. Thus, the capacity of the exhaust device (not shown) connected by the bellows hose 9 is set. Thereby, it is possible to suppress the uncoated atomized paint particles from scattering from the suction duct 3 to the outer periphery.

The distance between the substrate surface 7 and the suction duct 3 is 1
２2 cm, a gap formed between the inner cylinder of the suction duct 3 and the surface 7 to be coated, and the amount of exhaust air calculated from the total amount of atomized air and air-curtain air flowing through the gap. The speed of the suction air calculated from the area of the suction port 2 of the slit-shaped suction duct 3 and the air amount of the exhaust device is set higher than the speed.

Specifically, a two-fluid nozzle ("AM-25S", manufactured by Atmax Co.) is used as the atomizing nozzle 1, and an aminoacrylic solvent type paint ("Amirac", manufactured by Kansai Paint Co., Ltd.) is used as a paint. And the atomizing air pressure is 3kg /
cm ² (amount of atomized air: about 15 Nl / min), paint ejection amount 20 cc / min, air-curtain ejection amount 300
Nl / min, suction amount of slit duct is 500Nl
/ Min, the distance between the duct suction surface and the object surface is 2c
m, the suction duct 3 and the atomizing nozzle 1 attached to a coating robot (not shown) were operated at a speed of 0.5 m / sec on the surface to be coated, and the coating was performed. Efficiency is about 94% and the parting width of dust is about 1
The result was within cm.

In a coating booth having an atmosphere temperature and humidity of 25 ° C. and 85% RH, a water-based paint (“Askave”, manufactured by Kansai Paint Co., Ltd., nonvolatile content 42% by weight) was used as a paint. Using the same coating machine and coating conditions, and setting the air temperature of the air curtain at 40 to 45 ° C. (10% RH or less), the inclined coating is performed on the surface of the vertical object to be coated. Was measured. Also, for comparison, air-
Even in the conventional method without a curtain nozzle and a suction duct, the same paint was used for oblique coating on the surface of a vertical object to be coated, and the sagging limit film thickness was measured. As a result, the air-car
It was confirmed that the sagging limit film thickness when the ten was formed was about 35 μm, which was larger than about 25 μm when the ten was not formed. The result that the sagging limit film thickness is about 35 μm is as follows:
This is equivalent to the result when the entire coating bush is set at 25 ° C. and 70% RH, and the air curtain by the control air is formed around the spray pattern without such overall air conditioning. By doing so, normal coating is possible and energy can be greatly reduced.

FIG. 3 is a schematic view of a spraying part for explaining a second embodiment of the method of the present invention, and FIG.
FIG. 4 is an overall view for explaining the embodiment of FIG.

In FIG. 3, an air-curtain forming duct 11 is attached to the cylindrical body of the rotary atomizer 14 to control the temperature and humidity generated by an air-conditioning air generator (not shown). The air 10 is supplied to the air-curtain forming duct 11 through a bellows hose 16 and is further sprayed.
In conjunction with the start signal, the paint is discharged from the air curtain outlet 12 toward the spray pattern 17 of the atomized paint particles. The spray pattern 17 is a spray pattern in which the paint particles generated by the bell cup 13 are formed by shaping air ejected from around the bell cup. -Ping air is introduced into the spray pattern 17 as an accompanying flow.

Accordingly, the temperature and humidity control air 10 was entrained from the atomized paint particles in the spray pattern 17 until they flew from the bell cup 13 to the surface to be coated (not shown) and were applied. The amount of solvent volatilized is controlled by the shaping air atmosphere, and the solvent reaches the surface of the substrate with an appropriate coating viscosity.

The rotary atomizer 14 is mounted on a painting robot 15 as shown in FIG. The painting robot 15 is installed in a painting booth.

Specifically, ".mu. Microbell" (manufactured by Landsberg) as the rotary atomizing coating machine 14 was used.
Using 5% by weight of clear paint (manufactured by Kansai Paint Co., Ltd.), the number of revolutions is 30,000 rpm, and the paint discharge amount is 200 cc.
/ Min, shaping air pressure is 2 kg / cm ² (air consumption: 300 l / min), and the temperature of the control air supplied from the air-curtain forming duct 11 is 45 to 50 ° C. 10% RH or less), the supply air amount is set to 1000 Nl / min, and the entire coating bus is not air-conditioned.
Then, the inclined coating was performed on the surface of the vertical coated object, and the sagging limit film thickness was measured. As a comparison, the conventional coating method without the air-curtain duct from the above-mentioned coating machine was also applied to the vertical coating on the surface of the object to be coated under the same coating conditions and coating, and the sagging limit film thickness was measured. As a result, when the air curtain was formed by the control air, the sagging limit film thickness was about 40 μm, which was larger than about 30 μm when the air curtain was not formed. The result that the sagging limit film thickness is about 40 μm is that the entire coating bush is 25 to
The result is the same level as the result when the temperature is set to 30 ° C, and the normal coating is performed by forming the air curtain by the control air around the spray pattern without air conditioning of the entire coating bush. Was confirmed to be possible.

[0033]

According to the coating method of the present invention, it is possible to reduce the air-conditioning energy required for a coating bus while ensuring an appropriate coating atmosphere, and it is possible to perform efficient exhaust air treatment. It is.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a spray area for explaining a first embodiment of the method of the present invention.

FIG. 2 is a front view of a sprayed part for explaining a first embodiment of the method of the present invention.

FIG. 3 is a schematic view of a sprayed part for explaining a second embodiment of the method of the present invention.

FIG. 4 is an overall view for explaining a second embodiment of the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Atomizing nozzle 2 ... Duct suction port 3 ... Slit-shaped duct 4 ... Spray pattern 5 ... Air-curtain nozzle 6 ... Air-curtain air flow 7 ... Coating surface 8 ... Wet coating 9 ... bellows hose 10 ... temperature-humidity control air 11 ... air-curtain forming duct 12 ... air-curtain outlet 13 ... bell cup 14 ... rotary atomizing coating machine 15 ... painting robot 16 ... bellows hose S 17: Spray pattern

Claims (3)

[Claims] 1. A coating method in which a paint is sprayed using an atomizing nozzle, wherein an air curtain is formed around the spray pattern by air whose temperature and humidity can be controlled. 2. A duct for sucking uncoated spray dust among paint particles sprayed from an atomizing nozzle is provided with an air car.
The coating method according to claim 1, wherein the coating method is provided on an outer periphery adjacent to the ten. 3. The coating method according to claim 2, wherein the sum of the air flow rate of the air curtain and the air flow rate from the atomizing nozzle is smaller than the suction air amount of the duct for sucking the spray dust.