JP2002248386A - Method of recovering and recycling water paint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of trapping and recovering to recycle an un- applied paint of a water paint. SOLUTION: In the method of recovering unapplied particles not applied on a material to be coated in a spray coating for the water paint, an unapplied particle collecting apparatus provided with a discharge electrode and a dust collecting (ground) electrode is provided in a suction duct inlet of a coating booth to recover the paint stuck on the discharge electrode and the dust collecting electrode and the recovered paint is used for coating after the component-is adjusted again or is used while being mixed with a fresh paint.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for collecting and reusing a water-based paint, and more particularly, to a method for capturing and collecting an uncoated paint of a baking-type water-based paint for reuse.

[0002]

2. Description of the Related Art Conventionally, when atomizing a paint on a paint line, the rate at which paint particles atomized by a painter are applied to an automobile body as an object to be coated is at most about 60%, and the remaining rate is about 60%. 40% of particles were captured as uncoated particles by a dry filter of a coating booth (Drivus) or were taken into water by gas-liquid contact with a water curtain of the coating booth (washing booth).

[0003] Uncoated particles are periodically disposed of as waste. In dry lime, uncoated particles captured by the dry filter are incinerated as industrial waste together with the filter, while uncoated particles taken into the water in the washing booth are separated and dehydrated with a polymer flocculant. Has been treated as plastic industrial waste.

In particular, since the uncoated particles of the paint taken into the washing booth water contain a small amount of a hydrophilic solvent, a high concentration of the hydrophilic solvent is accumulated in the washing booth water over time. As a result, there is a problem that an excessive load is required for finally separating the discharged water to the reference value.

In order to solve the above problems, various systems have been proposed in recent years for capturing and collecting uncoated particles of a water-based paint and reusing them for coating. One of the methods is to capture uncoated particles in the circulating water for water curtains in the washing booth, periodically concentrate the water with a UF (ultrafiltration) membrane, and re-use the paint components composed of resin and pigment. There is a recycling system in which the baffle plate is adjusted and used (for example, Japanese Patent Application Laid-Open No. 2000-126669). There is a direct recovery type closed system in which the paint in the recovered paint tank is immersed in the paint tank and redissolved, and the paint in the recovered paint tank is constantly adjusted and reused (for example, Japanese Patent Application Laid-Open No. H10-165863). Both are systems that do not generate waste.

[0006] However, these systems have the following disadvantages. In the former system, since the uncoated particles are excessively diluted by the circulating water for water curtain, it is extremely difficult to regenerate the original paint properties even if the uncoated particles are concentrated on the UF membrane. In the latter system, the baffle plate covered with the wet paint has a structure that captures uncoated particles, so that the moisture and hydrophilic solvent from the wet paint always evaporates in the supply and exhaust flow of the paint booth. As a result, there is a problem that a large amount of adjusting liquid is required to keep the paint components in the paint tank constant.

Further, in both systems, when the paint color of the paint used is changed or when the color needs to be changed, all the circulating water in the washing booth is replaced, or a system for the required number of colors is used. There was a problem that needed.

An object of the present invention is to provide a method for efficiently capturing and recovering an uncoated paint generated at the time of atomizing coating of a water-based paint without the above-mentioned problems, and reusing the uncoated paint.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method of recovering uncoated particles that have not been applied to an object to be sprayed in a water-based paint, comprising: A method for collecting a water-based paint, comprising: providing an uncoated particle capturing device having a discharge electrode and a dust collection (ground) electrode; and collecting the paint adhered to the discharge electrode and the dust collection electrode.
The present invention also relates to a method for reusing a water-based paint, which comprises adjusting the components of the recovered paint again for use in coating, or mixing and using this with a new paint.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in the atomization coating of a water-based paint, an uncoated particle capturing device is provided at the entrance of a suction duct of a coating booth, and the paint is collected here. The coated particles are guided to the uncoated particle capturing device on the exhaust airflow of the coating booth. The coating booth may be a conventionally known dry booth having a suction duct or a washing booth.

The uncoated particles generated by an atomizing coating machine such as an internal electrode type bell electrostatic coating machine are usually charged particles having electric charge, but the external electrode type bell type electrostatic coating machine is used. Uncoated particles generated by an atomizing coating machine such as a spraying machine do not sufficiently retain a charge due to low charging efficiency.

Therefore, the uncoated particle capturing apparatus used in the present invention comprises a discharge electrode for recharging the paint particles passing therethrough, and a dust collecting (ground) electrode for capturing the charged paint particles by Coulomb force. It is provided. At the discharge electrode, corona discharge is generated near the electrode due to the applied high voltage to ionize air. Usually, a stable negative voltage of the discharge is applied to the discharge electrode, and a large amount of negative ions are generated near the electrode. The uncoated particles are recharged by the negative ions to become saturated charged particles. The applied voltage at the discharge electrode is usually a negative voltage of 5 KV or more, preferably 15 KV or more. On the other hand, the dust collecting electrode is installed to face the discharge electrode, and is used in a grounded state. As a result, an electric field is formed between the discharge electrode and the ground (dust collecting) electrode, and the charged uncoated particles are captured by the dust collecting electrode by Coulomb force. Most of the uncoated particles are captured by the dust collection electrode, but the uncoated particles having a small charge amount are also captured by the discharge electrode by the gradient force.
The distance (distance) between the discharge electrode and the dust collection electrode is usually 2 to 20.
cm is appropriate, and the average wind speed of the exhaust air passing through each electrode is desirably about 1.0 m / s or less.

Each of the discharge electrode and the dust collecting electrode is preferably a continuous molded product made of a conductive wire, and is usually formed in a loop or mesh shape, and the uncoated particles in the coating zone are suspended. It is desirable to be stretched so as to cover the area.

In the present invention, the uncoated particle capturing device is a device for removing and collecting the above-mentioned discharge electrode and dust collecting electrode, and a paint adhered to each wire, and a driving device for rotating each wire in a continuous or tact operation. Those having the following are preferred. The adhered paint can be removed and collected by methods such as ironing or blowing off with a high-pressure air nozzle or the like. It is appropriate to collect. While rotating each wire in a continuous or tact operation, it can be ironed off by an ironing member attached to the wire, and the adhered paint can be collected. There is almost no paint on the wire after recovery,
If there is any residue, a wire cleaning device may be provided as necessary. Since the paint is hardly adhered to the recovered wire, the color of the water-based paint can be easily changed.

When the coating zone is wide, the unit for capturing uncoated particles as described above may be one unit, and a plurality of units may be applied according to the size.

Since the paint recovered as described above has a high solid content from which water has evaporated, a diluent comprising water and additives is added as necessary to adjust the solid content again. Then, it can be reused by directly using it for painting, or by using this reconditioned material while mixing it with a new paint. Before reuse as a paint, it is desirable to filter and separate impurities such as dust.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory view of a coating booth showing one embodiment, and FIG. 2 is a schematic explanatory view of a dust collecting electrode and a discharge electrode of an uncoated particle capturing device used in the present invention. Also, FIG.
It is explanatory drawing which shows the example of collection | recovery in an uncoated particle capture device.

In FIG. 1, a floor conveyor 6 is installed on a drive 1 for painting an automobile body 2, and the automobile body 2 is mounted on a trolley and equipped with a bell-type electrostatic painting machine 3 in tact operation. It is transported to the painting zone by the painting robot 4. In the coating zone, the uncoated particle capturing device 5 is installed in a floor portion corresponding to an area where the spray dust floats in the bell type electrostatic coating machine 3 within an operation range of the coating robot 4. Booth 1
Is exhausted toward the uncoated particle capturing device 5, and a dry filter 7 is provided below the uncoated particle capturing device 5.

The uncoated particle capturing device 5 comprises a dust collecting electrode 8 and a discharge electrode 9 as shown in FIG. A negative high voltage 10 of about 5 to 30 KV was applied to the discharge electrode 9, and the application was synchronized with the time when the painting robot 4 performed the spraying operation. The dust collecting electrodes 8 are provided above and below the discharge electrodes 9 and are grounded to the ground, so that accidents due to contact with the uncoated particle capturing device 5 from outside can be prevented. The distance between the collection electrode 8 and the discharge electrode 9 is about 10 cm
Set to.

Each of the dust collecting electrode 8 and the discharge electrode 9 has one
A metal wire of mmφ was used, and each wire was formed into a loop so as to cover a spray dust floating area (approximately 10 m) in the coating zone and was stretched. A retractable operating grating (not shown) is provided on the upper surface of the uncoated particle capturing device 5, and becomes a normal grating floor during maintenance work or the like.

Uncoated paint 1 attached to and deposited on each wire
As shown in FIG. 3, 1 is ironed from the wire by an ironing unit 12 attached to each inverted portion, collected and collected in a collection pit 13, and sent to a paint regenerating device (not shown).

Here, the wind speed of the painting booth 1 is set to 0.3
With the external electrode type bell-type electrostatic coating machine 3 attached to the coating robot 4, the water-based intermediate coating material (paint solid content 25%) was set at a booth temperature and humidity of 23 ° C. and 76 RH.
%, The coating efficiency was about 55% and the remaining 45% were uncoated particles. The average wind speed of the exhaust air passing through the electrodes 8 and 9 in the uncoated particle capturing device 5 is adjusted to about 0.3 m / s, the applied voltage of the discharge electrode 9 is -15 KV, and the distance between the discharge electrode 9 and the dust collecting electrode 8 is reduced. 10cm, wire pitch of each electrode about 5cm
Under these conditions, the concentration of uncoated particles after passing through the capture device 5 was measured to calculate the capture efficiency. As a result, the capture efficiency is 99
% Or more.

The recovered paint had a solid content of about 35%, and was diluted with a dedicated diluent (a deionized water containing a slight amount of a hydrophilic solvent) so as to have a solid content of 25%. The solid content was automatically adjusted while monitoring with an ultrasonic densitometer (“DENS-K”, manufactured by Kansai Paint Co., Ltd.). The collected paint after the solid content adjustment was used again by filtering garbage butter through a filter. When the viscosity characteristics of the paint were measured,
Almost the same characteristics as the original paint were obtained, and the paint workability and finish after painting were not different from the original paint.

[0024]

According to the present invention, uncoated particles generated in the atomization coating of the water-based paint can be quickly captured by the uncoated particle capturing device provided at the entrance of the suction duct of the coating booth, and adhered to the uncoated particles.・ By collecting the deposited paint,
Uncoated paint can be efficiently reused. Therefore, with regard to the disposal of uncoated particles, which had been a problem in the past, filter replacement was drastically reduced in the case of dry sauce,
In the case of a washing booth, the cost of water treatment can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a painting booth showing one embodiment of the present invention.

FIG. 2 is a schematic explanatory view of a dust collecting electrode and a discharge electrode of the uncoated particle capturing device used in the present invention.

FIG. 3 is an explanatory diagram showing an example of recovery in an uncoated particle capturing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Driving 2 Car body 3 Bell type electrostatic coating machine 4 Painting robot 5 Uncoated particle capturing device 6 Floor conveyor 7 Filter 8 Dust collecting electrode 9 Discharge electrode 10 High voltage 11 Uncoated paint 12 Ironing unit 13 Collection pit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05B 15/12 B05B 15/12

Claims (4)

[Claims] 1. A method for recovering uncoated particles that have not been applied to an object to be applied in the atomization coating of a water-based paint, wherein a discharge electrode and dust collection (grounding) are provided at an inlet of a suction duct of a coating booth. A method for collecting a water-based paint, comprising: providing an uncoated particle capturing device having an electrode; and collecting paint adhered to the discharge electrode and the dust collecting electrode. 2. In the atomization coating of a water-based paint, uncoated particles that are not applied to an object to be coated are removed by a discharge electrode and a dust collecting (grounding) electrode provided at an inlet of a suction duct of a coating booth. A method for reusing an aqueous paint, wherein the paint is collected by a coated particle capturing device, and the recovered paint is used for coating by adjusting the components again, or is used while being mixed with a new paint. 3. The method according to claim 1, wherein the discharge electrode and the dust collecting electrode are continuous molded articles made of conductive wires, and the paint adhered to each wire is scraped off and collected. 4. A discharge electrode and a dust collecting electrode comprising a conductive wire, a device for removing and recovering paint adhered to each wire, and a driving device for rotating each wire in a continuous or tact operation. An uncoated particle capturing device used in the method according to claim 1.