JPH08206580A - Powder coating method and coating equipment - Google Patents

Abstract

(57) [Summary] [Purpose] Eliminating the difficulty of changing the color of conventional powder coating,
Further, by eliminating the difficulty of color change, the application range of the powder coating material, in particular, the applicability to multi-color coated products is broadened. [Structure] When applying the colored powder coating material, a plurality of types of elementary colored powder coating materials are quantitatively and continuously mixed in parallel with the coating operation and supplied to the coating machine for coating, resulting in a toned color. A coating method for powder coating, which comprises obtaining the above-mentioned coated article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method of powder coating material for obtaining a coating material having a continuously toned color. It also relates to a device used in the above method.

[0002]

2. Description of the Related Art Conventionally, in order to obtain a coated product having a desired color tone adjusted by powder coating, generally, a resin as a base material of powder coating is kneaded with a plurality of pigments necessary for toning. However, a method of applying a single powder coating material produced by further pulverization (hereinafter referred to as method A) was general.

Further, according to the patent application publication No. Hei 4-504431, various kinds of elementary powder coating materials added after mixing plural kinds of elementary powder coating material powders colored in different colors and further granulating A method (hereinafter referred to as method B) of producing secondary particles containing a mixture of raw material powder particles and coating the secondary particles as a powder coating material is described.

As shown in FIG. 3, in the method A,
In order to perform powder coating of one color and then coating of another color, generally, a mixer 1 of a pigment and a powder coating base material is used.
6. Melt-kneader 1 for melt-kneading the pigment and the powder coating material base material
7, cooling conveyor 18, crusher 1 for crushing and classifying the kneaded material
It is necessary to strictly clean 9, the classifier 20, and the coating machine. This work is extremely complicated, and it has been extremely difficult to economically perform powder coating particularly when the frequency of color change is high.

Further, as shown in FIG. 4, in the method B as well, the mixing machine 16 for the raw powder of the raw material powder for powder coating and the secondary granulating device 2 are used.
1. It is necessary to clean the drying conveyor 22, the screen 23, the classifier 20, and the coating machine. In particular, the secondary granulation device 21,
Cleaning the sieve 23 and the classifier 20 requires a lot of time and labor. The difficulty of changing colors as described above
It has greatly limited the application range of powder coating.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the difficulty of changing the color of the conventional powder coating as described above. Further, by eliminating the difficulty of changing the color, the application range of powder coating, especially the applicability to multicolor coated products, is broadened. Therefore, according to the present invention, the toning and the color changing for each toning that does not require cleaning of a device having a complicated structure such as the melt-kneader 17, the crusher 19, the classifier 20, the secondary granulator 21, the screen 23, etc. It is an object of the present invention to provide an easy powder coating method.

[0007]

According to the present invention, when coating a colored powder coating material, a plurality of kinds of elementary colored powder coating materials are quantitatively and continuously mixed in parallel with the coating operation and supplied to a coating machine. The present invention provides a method for coating a powder coating material, which is characterized in that a coated article having a toned color is obtained by coating.
Further, the present invention comprises a plurality of elementary colored powder paint storage containers, an elementary colored powder paint take-out quantitative feeder, an elementary colored powder paint mixing machine, and a coating machine, and continuously mixes the elementary colored powder paint. The present invention provides a coating apparatus for powder coating material having a mechanism for supplying the coating material to a coating machine.

In the present invention, the color adjustment is performed by simply mixing the elementary colored powder coating materials. The elementary colored powder coating material is a colored powder coating material used as a basic color for toning to develop a desired color. In principle, it is sufficient for the types of elementary colored powder coatings to have the three primary colors of red, yellow and blue, and black, white and transparent, but in reality it is difficult to obtain these pure colors. It is desirable to prepare some neutral colors to facilitate the toning. Further, when a large number of tonings in the vicinity of a specific color are required, it is desirable to prepare an uncolored powder paint of the specific color. The elementary colored powder coating material in the present invention includes all of the above powder coating materials.

The elementary colored powder coating material itself must have the characteristics as a powder coating material. That is, in the case of coating with an electrostatic powder coating gun equipped with an air flow transport device, it is necessary to have the required air flow transport property and the required charging property. Further, in the case of coating by the fluid immersion method, air flow fluidity is required. Furthermore, generally, the pigmented powder coating material contains a resin as a base material of the coating material, a pigment, a crosslinking agent, and other additives.

Examples of the resin include (meth) acrylic acid esters, (co) polymers such as styrene, vinyl acetate and vinyl chloride, thermoplastic resins such as polyolefin, saturated polyester and polyamide, and crosslinkable functional groups to these resins. There is a resin provided with. Also, as another example,
Epoxy resin, phenol resin, urethane resin, etc. are also available.

Further, for coloring, organic pigments, inorganic pigments, dyes and the like are used, and as cross-linking agents, isocyanates, epoxy compounds, polyvalent organic acids and the like are used.
Further, as additives, charge control agents, other UV absorbers, antioxidants and the like are also used.

As a method of coating the powder coating material, there are electrostatic coating with an electrostatic coating gun, fluidized immersion coating and the like. In the method of the present invention, the coating machine, ie the electrostatic coating gun or fluidized dipping tank in the above example, is successively fed with powder coating during the coating operation. Further, the powder coating material to be supplied is adjusted in parallel with the coating operation by quantitatively and continuously mixing a plurality of types of elementary colored powder coating material. In this case, the mixing operation is performed concurrently with the painting operation. Completing the mixing operation prior to the painting operation requires the production and storage of a large amount of raw materials, and the color change requires a great deal of labor and switching time to clean the large mixer and the large storage container. .

In the method of the present invention, the coating operation can be smoothly started if a small amount of mixing operation is performed prior to the coating operation. Thereafter, the powder coating is replenished by continuously mixing the elementary colored powder coatings necessary to replenish the powder coating consumed in parallel with the coating operation. in this case,
Mixing may be done continuously by repeating small batch mixing. In addition, in the mixing of the present invention, in order to obtain a constant color tone during a series of coating operations, it is necessary that the mixing ratio of each elementary colored powder coating material be constant. In order to increase the accuracy for obtaining a constant mixing ratio, it is desirable to repeat the small batch method.

Further, in the method of the present invention, in order for the coated product to have a uniform appearance as a composite color of the colors of each elementary colored powder coating material, the substantially maximum particle size of the elementary colored powder coating material is 20 μm or less. Is highly desirable. This is also effective for obtaining the surface smoothness of the coated product. Sometimes, particles with a particle size of 20 μm or more are intentionally added to obtain a coated product having a frosted appearance. In this case as well, considering the smoothness of the surface, the component having a particle size of 20 μm or less is 70% by weight or more. Is desirable. More preferably, it is desirable that 70% or more of the elementary colored powder coating material is a powder having a particle diameter of 4 to 20 μm.

The particle size is determined by a corta multisizer (Co., Ltd.).
(Made by Nikkaki), set 100μ orifice,
Can be measured. The particle size-weight percentage integral curve is obtained from the particle size distribution obtained from a Coulter Multisizer, and the particle size with a weight percentage integrated value of 99% is taken as the particle size distribution.

When the substantially maximum particle size of the elementary colored powder coating material is 20 μm or less, more preferably 17 μm or less, airflow transportability, airflow fluidity and quantitative feedability are generally deteriorated, and suitability as a powder coating material is lacking. Tend. However, by excluding particles having a particle size of substantially 4 μm or less and adjusting the S value that defines the particle shape in the range of 100 to 160, a raw material powder coating material having a particle size of 20 μm or less can be obtained. Powder coating properties can be imparted.

Here, the S value means a shape factor obtained by dividing the square of the perimeter of the powder particles by the area, for example LUZEX 3
A plane image is obtained by an image processor such as U (manufactured by Nikon Corporation) and the perimeter (PM) and area (A) on the plane image are calculated to obtain the following formula. S value = {(PM) ² ÷ (4Aπ)} × 100 Usually, about 100 particles are measured and the average value is calculated,
S value.

Next, the method of the present invention comprises a plurality of elementary colored powder paint storage containers, an elementary colored powder paint take-out quantitative supply device, an elementary colored powder paint mixer, an intermediate service container for mixed paint as required, and coating. Carried out by the combined system of the machine. A control computer and sensors are provided as needed.
The elementary color powder coating material take-out quantitative feeder and the elementary color powder coating material mixer may be those which operate completely continuously, or those of a small batch type which repeatedly operate. When changing the color of the powder coating, as long as the powder coating does not change, only the powder coating mixer and coating machine and, if necessary, the mixed coating intermediate service container need to be cleaned. Also, in order to minimize their effort, it is desirable that they be as small as possible.

Therefore, the present invention is based on the above-mentioned plurality of elementary colored powder coating material storage containers, elementary coloring powder coating material dispensing quantitative feeders,
A powder paint coating device comprising an elementary color powder paint mixer and a coating machine and having a mechanism for continuously mixing the elementary color powder paint and supplying the mixture to the coating machine. Is.

The powder coating material is taken out from the storage container for the base colored powder coating material, and the powder coating material is flown into a fixed quantity feeder and discharged in a fixed amount. For the quantitative supply machine for taking out powdery powder paint,
For example, a screw type, a table type, a vibration type, etc. may be used, and a weighing method may be either a weight type or a volume type.

[0021]

Using the method and apparatus of the present invention, the pigmented powder coating material is applied while being mixed in a desired ratio. In addition, color change is extremely easy.

[0022]

EXAMPLE 1 Example 1 of the present invention will be described with reference to FIG. As shown in FIG. 1, four elementary colored powder coating material dispensers 2 each having an elementary colored powder coating material storage container 1 are installed. As a method for supplying the elementary color powder coating material to the elementary color powder coating material storage container 1, an operator may manually inject each time, or a mechanical method such as a screw type transportation machine or an air type transportation machine. Yes, any method is acceptable.

Prior to the coating operation, in order to obtain a powder coating material toned and mixed in a desired hue, the mixing ratios of the four types of elementary colored powder coating materials, which are basic colors, are confirmed in advance,
Quantitative supply machine 2 for extracting 4 color-colored powder paints each
The supply amounts of a, 2b, 2c and 2d are set. The weight-type weighing device 4 for sequentially measuring the elementary coloring powder coating materials discharged from the four elementary coloring powder coating material dispensing quantitative feeders 2 is freely connected between the four elementary coloring powder coating material dispensing quantitative feeding apparatuses 2. The weight type weighing device 4 is installed as a single unit, and a container for containing the elementary colored powder paint to be weighed is placed on the weight type weighing device 4. The containers are fluid tank tanks 3a and 3b for sending powder coating to the electrostatic coating gun 6. In addition, the weight type weighing device 4
It may be attached to each of the elementary color powder coating material take-out constant quantity feeders 2. The weight scale 4 may be either an electric type or a mechanical type.

The discharge order of the quantitatively colored powder paint take-out fixed quantity feeder 2 is, for example, 2a, 2b, 2c, 2d in a horizontal row.
, The elementary colored powder coating material take-out quantitative feeders 2a, 2b, 2c, 2d are sequentially discharged from the left side, and discharged while being sequentially metered in the right direction. In this container, the elementary colored powder coating materials which have been weighed out by the quantitative supply apparatus 2 for each elementary colored powder coating material are accumulated and added. This operation ends the first weighing.

Next, while feeding air from the air pipe 10 to the lower part of the fluidized bed tank 3a which is a fluidized-bed type mixing device, a plurality of types of elementary colored powder coating materials are uniformly mixed. Air is sent from the air pipe 10 to the injector 15 above the fluidized tank 3a. The mixed powder paint is sucked up from the fluid tank 3a, supplied to the electrostatic paint gun 6 through the paint pipe 11, and the powder paint is sprayed onto the object 7 to be coated. In this case, the injector air switching valve 12 and the flow air switching valve 14 are open to the fluid tank tank 3a side, and the powder paint switching valve 13 is also open to the fluid tank tank 3a side. There is.

When the powder coating material in the fluid tank 3a becomes low, the injector air switching valve 12, the fluid air switching valve 14 and the powder coating switching valve 13 are switched to the fluid tank 3b side. The fluid tanks 3a and 3b also serve as paint tanks for the electrostatic coating gun 6. The air used is supplied by connecting the compressor 24 to the powder coating controller 5.

The total weight of the four types of elementary color powder coating materials is treated with the amount of coating material supplied from the electrostatic coating gun 6, and the four types of elementary color powder coating materials are weighed to obtain a toned color. Are sequentially and alternately supplied to the fluid tank tanks 3a and 3b. This operation is sequentially repeated to continuously perform powder coating. The amount of coating material supplied to the electrostatic coating gun 6 is determined by the physical properties of the powder coating material, the coating film thickness of the coating object 7, the material of the coating object 7, and the like.

In changing the color of the powder coating material, as long as the powder coating material remains unchanged, the storage container 1 for the powder coating material powder,
It is not necessary to clean the four elementary colored powder paint take-out quantitative feeders 2, and the fluid tank tanks 3a, 3b, the injectors 15,
Only the paint pipe 11, the powder paint switching valve 13, and the powder coating gun 6 need to be cleaned. As a method of cleaning these, the fluid tank tanks 3a and 3b have a structure in which the injector 15 and the fluid tank tanks 3a and 3b can be easily disassembled with one touch, and the fluid tank tanks 3a and 3b are replaced with those which have been previously cleaned. . The injector 15, the paint pipe 11, the powder paint switching valve 13, and the electrostatic coating gun 6 send air from the rear of the injector 15 to clean all of them.

As described above, the cleaning at the time of color change solves the difficulty of the conventional method A and B at the time of color change, and the structure of the apparatus of the present invention is very simplified, so that it can be easily performed. ,easily,
It can be cleaned in a short time.

Example 2 Example 2 will be described with reference to FIG. First of all, 4 of the fixed quantity supply machines 2a, 2b, 2c, 2d for taking out the colored powder coating material
The ejectors 8a, 8b, 8c, 8 are set such that the supply amounts of the various types of elementary colored powder coating materials are set to a constant mixing ratio.
continuously supplied to d. Air is sent to the air piping 10 connected to the four ejectors 8 to send these elementary colored powder coating materials to the continuous mixer 9. Further, air is sent to the continuous mixer 9 to mix the elementary colored powder coating material into the coating pipe 11.
It is continuously fed to the electrostatic coating gun 6 through and the object 7 to be coated is coated. Here, the elementary colored powder coating material take-out quantitative feeder 2 is of a capacity type, and a type of type most suitable for the physical properties of the powder can be selected.

In changing the color of the powder coating, as long as the powder coating does not change, the powder coating storage container 1,
It is not necessary to clean the four elementary colored powder paint dispensing constant quantity feeders 2 and the ejectors 8a, b, c and d, and only the continuous mixer 9, the paint pipe 11 and the electrostatic coating gun 6 need to be cleaned. Good. As a cleaning method for these, the continuous mixer 9 is detached from the front and rear paint pipes 11 with one touch and washed with air, and the electrostatic coating gun 6 sends air from the paint pipes 11 and simultaneously performs air washing.

As described above, the cleaning at the time of color change solves the difficulty of the conventional method A and B at the time of color change, and the structure of the apparatus of the present invention is very simplified, so that it can be easily performed. ,easily,
It can be cleaned in a short time.

[0033]

The coating method of the powder coating material according to the present invention is
Melt kneader, crusher, classifier, secondary granulator for each toning,
Eliminates the difficulty of color adjustment and powder coating method that does not require cleaning of equipment with complicated structure such as sieves and easy color change Since the structure of the device of the present invention is greatly simplified,
It is an object of the present invention to provide a coating device for powder paint which can be easily and quickly cleaned.

[Brief description of drawings]

FIG. 1 is a process explanatory diagram showing an overall configuration of a first embodiment of the present invention.

FIG. 2 is a process explanatory diagram showing an overall configuration of a second embodiment of the present invention.

FIG. 3 is a process explanatory diagram showing an overall configuration of a conventional method A.

FIG. 4 is a process explanatory diagram showing an overall configuration of a B method of a conventional technique.

[Explanation of symbols]

 1 Primary colored powder paint storage container 2 Fixed colored powder paint take-out quantitative feeder 3 Fluid tank tank 4 Weight measuring device 5 Powder coating control device 6 Electrostatic coating gun 7 Object to be coated 8 Ejector 9 Continuous mixer 10 Air piping 11 Paint Piping 12 Air Changeover Valve for Injector 13 Powder Paint Changeover Valve 14 Air Changeover Valve for Flow 15 Injector 16 Mixer 17 Melt Kneader 18 Cooling Conveyor 19 Crusher 20 Classifier 21 Secondary Granulator 22 Drying Conveyor 23 Sieve 24 compressor

Claims (5)

[Claims] 1. When applying a colored powder coating material, a plurality of types of elementary colored powder coating materials are quantitatively and continuously mixed in parallel with the coating operation and supplied to a coating machine for coating toning. A method for coating powder paint, characterized in that a coated object of different colors is obtained. 2. 70% or more of the elementary colored powder coating composition is 4 to 20.
2. The coating method for powder coating material according to claim 1, which is a powder having a particle size of μ. 3. The S value of the elementary colored powder particles is 100 to 160.
The powder coating material coating method according to any one of items 1 and 2, wherein 4. A plurality of elementary colored powder coating materials are quantitatively weighed and mixed in a small-quantity batch system, and this is repeated to obtain:
The method for coating powder coating material according to any one of the first, second and third aspects, wherein the powder coating material is continuously mixed and supplied to a coating machine. 5. A plurality of elementary colored powder paint storage containers, an elementary colored powder paint take-out quantitative supply device, an elementary colored powder paint mixing machine,
An apparatus for coating powder coatings, comprising a coating machine, and having a mechanism for continuously mixing the elementary colored powder coatings and supplying it to the coating machine.