JPS61212359A - Coating apparatus - Google Patents

Abstract

PURPOSE:To control an increase in viscosity to a minimum and to coat continuously by connecting a paint discharger equipped with an agitator to a coating vessel, discharging and replenishing the requisite amt. of two liqs. into the coating vessel while mixing and agitating the liqs. CONSTITUTION:In a dip coating apparatus, a paint discharger 5 equipped with an agitator 1 is connected to a coating vessel 10, two liqs. are mixed and agitated, the mixture is simultaneously passed through the inside of the agitator 10 and discharged into the coating vessel 10 from the orifice of the agitator 1. Consequently, since the essential agent of a thermosetting resin, a curing agent, etc., of two liqs. mixing type can be discharged and replenished respectively in the requisite amt. while being mixed and agitated into the coating vessel, an increase in viscosity is prevented, continuous coating is made possible and the yield of paint can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dip coating device that is capable of mixing a coating material immediately before coating and coating the coating material continuously to form a uniform coating film.

[Prior art]

A dip coating method is generally used to apply a paint to the surface of an object to be coated, and a good paint film can be obtained relatively easily.

On the other hand, it requires a large amount of paint, especially the two-component heating type 4N-+7. When using heat-curable resins such as urethane and acrylic, after preparing the paint by mixing it with a curing agent,
Even at room temperature, the viscosity increases over time due to the reaction, making it difficult to continuously obtain uniform coatings under the same conditions. As such, continuous coating is not possible, and the paint remaining in the paint tank is uneconomical because it is discarded once its viscosity increases and it becomes dull.

[Problem that the invention seeks to solve]

The present invention makes it possible to effectively utilize the paint in the coating tank, and in particular minimizes the increase in viscosity due to reaction by mixing and supplying the two-component heating type thermosetting resin base and curing agent immediately before coating. It is an object of the present invention to provide a coating device capable of continuous coating.

[Means for solving problems]

According to the present invention, the coating tank is comprised of a coating tank having a through hole that is approximately the same as the outer diameter of the object to be coated, and a paint circulation system, and the coating tank is provided with a leakage prevention sheet that is slightly smaller than the outer diameter of the object to be coated. In a device that collects paint in a gap formed by a leakage prevention sheet and a coating tank and moves the object to be coated vertically to form a coating film, a paint discharger equipped with an agitator is connected to the coating tank. There is provided a coating device characterized in that 28 or more liquids are mixed and stirred and the mixed paint is discharged from an orifice of the stirrer into a coating tank.

The invention is illustrated in the accompanying drawings. FIG. 1 is a schematic diagram illustrating a coating apparatus of the present invention. The coating tank 10 is used to store objects 11 to be coated.
A through hole is drilled that is approximately the same as the outer diameter of the object to be coated 1.
A ring-shaped liquid leakage prevention sheath) 15 having an inner diameter slightly smaller than the outer diameter of 1 is provided, and a gap portion 16 consisting of the object to be coated 11, the coating tank 10, and the liquid leakage prevention sheath) 15 is provided. Collect paint. The object 11 to be coated is vertically moved by a drive system 13 via a screen screw 14 to form a coating film. FIG. 1 shows a circulation system for can liquid (one is a main agent and the other is a curing agent) and a cleaning solvent tank when using a paint that is cured by reaction by mixing two liquids. The main agent and curing agent cans are put into the tank 6, and the optimal amount is determined in consideration of the curing conditions of the paint, and the amount is transported in a fixed amount. The heat exchanger 7 maintains a constant temperature in order to equalize the viscosity and reactivity. The flow meter 8 is a means for measuring the circulating flow rate. When there is sufficient paint in the coating tank 10, the liquid is returned to the tank 6 by the three-way valve 2. When paint is required in the coating tank 10, the three-way valve 2 directs the liquid toward the discharger 5 side. The combined liquids in the discharge device are mixed and stirred while passing through the stirrer 1, and then discharged into the coating tank 10. It is conceivable that a liquid pressure difference occurs when the paint returns to the tank 6 and when it is stirred and discharged, causing a change in the mixing flow ratio, but by adjusting the pressure regulating valve 3, an appropriate mixing flow ratio can be ensured. Ru.

At the paint discharge rate 5 with the above-mentioned stirrer 1 attached, the two liquids are mixed and stirred, and at the same time, the mixed paint passes through the stirrer and is discharged from the orifice of the stirrer 1 into the coating im""1" o. It is important that such an agitating extruder has a built-in helical type screen.A particularly preferable agitating extruder is shown in FIG. Its enlargement is shown in Figure 3.

By operating the above-mentioned circulation system, the canned liquid is discharged through the orifice 23 of the discharger, but the liquid is in the 2-sen zone g2 in the stirrer 1.
1 and is mixed and stirred while passing through the discharge orifice 22.
The liquid is then discharged into the coating tank 10. By appropriately selecting the diameters of the orifices 22 and 23, the circulation and discharge pressure can be adjusted appropriately depending on the viscosity of the paint. The optimum value of stirring efficiency can be obtained by appropriately selecting the diameter of the helical band blade 21, the depth and the number of helices.

The discharger main body 5 supports the stirrer 1 and the orifice 23, and is provided with liquid passages 24 and 25 and a solvent passage 26 for cleaning the stirrer inside.

〔effect〕

As mentioned above, by discharging the required amount of cured resin paint of the type that mixes two or more liquids into the coating tank while mixing and stirring immediately before coating, continuous coating due to thickening by reaction is possible. The coating process, which was previously impossible and uneconomical, can now be performed continuously, and the yield of paint can be improved.

Example 1 Thermosetting acrylate (product name) as a paint resin.

Aronix M8060. Toagosei Kagaku Co., Ltd. was prepared. To 100 parts by weight of the resin, 50 parts by weight of titanium oxide (trade name: 5RIT, manufactured by Sakai Chemical Co., Ltd.) was dispersed in a sand mill for 2 hours to prepare a paint. This paint is made by mixing 1 part by weight of benzyl peroxide with 100 parts by weight of resin, and cures at 130°C, but even at room temperature, after 5 hours, small pieces of dull particles appear on the paint. Occurred, 2
The paint has poor stability over time, with almost no fluidity after 4 hours.

The coating resin and benzoyl peroxide were separately prepared in tanks using the coating apparatus shown in FIG. Note that benzoyl peroxide was prepared by taking into consideration the viscosity after stirring and using methyl ethyl ketone (MEK).
) and diluted 50 times to make 9 diluted diluted products.

A metering pump made by Swiss company Maag was used to circulate the paint resin at a flow rate of 100.9 g/min and the benzoyl peroxide/MEK solution at a flow rate of 50 g/min. The pressure regulating valves were set so that the pressures were 2sHt7cxi' and 5 and 9f/m2, respectively.

The necessary amount of this was discharged into the coating tank while stirring, and then the cylindrical object to be coated was moved upward at a constant speed to form a coating film, resulting in a continuous coating process as shown in the table below. However, a uniform film thickness was obtained.

The coating film was cured by heating in a drying oven at 130°C for 30 minutes after coating, and then the film thickness was measured.

Star) 20μ 20μ After 3 hours 20μ After 5 hours when the 20μ at film is coated 21μ 25μ After 8 hours when () is applied 21μ Unable to apply (due to ruolization) Example 2 A two-component urethane was prepared as a paint. A homogeneous system consisting of 100 parts by weight of polyester Iliol (trade name: F42F 8002 Nippon Riurethane Co., Ltd.) as a main ingredient, 60 parts by weight of ethyl glycol acetate, 60 parts by weight of ethyl acetate, and 60 parts by weight of toluene, as a curing agent. Polyisocyanate (Product name: Coronate L1 Japan? Riurethane (
Co., Ltd.) 100 parts by weight, toluene 20 parts by weight)
Each system was individually charged into the tank 6 of the coating device.

The circulation amount based on a fixed amount of 47 grams is 7097 minutes for the main agent and 30 minutes for the hardening agent.
When coating was carried out in the same manner as in Example 1 for 97 minutes, continuous coating for 8 hours from the start of coating was h
Therefore, variations in film thickness were not considered. As a comparative example, a coating film was prepared by mixing the base resin and curing agent at a ratio of 70 parts by weight to 30 parts by weight and applied by a normal dip coating method, and the film thickness was doubled 5 hours after the start of coating. After some time, the viscosity increased and it became impossible to apply.

[Brief explanation of the drawing]

Fig. 1: 01 is an explanatory diagram of the entire coating device of the present invention.
...Spiral stirrer, 2...3-way switching valve, 3...
Pressure regulating valve, 4...metering pump, 5...discharge device, 6
... Paint tank, 7 ... Heat exchanger, 8 ... Flow meter, 9 ... Cleaning solvent tank, lO ... Application tank, 11
...To be coated, 12...To be coated object lifting platform, 13...
- Drive system, 14...Screw screw, 15...Leakage prevention sheet, 16...Gap portion for collecting paint. Fig. 2: An explanatory view of a discharger equipped with an agitator Fig. 3: An enlarged view of a helical band blade. 21... Spiral band blade, 22... Discharge orifice, 2
3... Orifice, 24.25... Paint passage, 26
...Cleaning solvent passage. 1st rXI

Claims (3)

[Claims] (1) Consists of a coating tank with a through hole that is approximately the same as the outer diameter of the object to be coated and a paint circulation system, and a leak prevention sheet that is slightly smaller than the outer diameter of the object to be coated is provided in the coating tank to prevent liquid leakage. In an apparatus for forming a coating film by storing paint in a gap formed by a sheet and a coating tank and vertically moving an object to be coated, the coating tank is connected to a paint discharger equipped with an agitator, and 2 A coating device characterized in that, while mixing and stirring two or more liquids, the mixed paint is discharged from an orifice of the stirrer into a coating tank. (2) The coating device according to claim 1, wherein the agitator incorporates a combination of helical band blades having different helical directions. (3) The coating device according to claim 1, wherein each of the two or more types of liquids is supplied to the paint discharger from a circulation system having at least a paint tank, a pump, and a pressure regulating valve.