JPH0474060B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention atomizes and disperses liquid paint using a rotating atomizing head, and uses electrostatic action to spread the atomized paint onto the object to be coated. The present invention relates to a rotary atomizing electrostatic coating device for coating materials and an electrostatic coating method using the same.

(Prior Art) An electrostatic coating device is used when painting the surface of an automobile body by applying paint uniformly over the entire surface. In the case of painting using such an electrostatic coating device, that is, electrostatic painting,
A high DC voltage is applied between the object to be painted and a sprayer placed opposite to it that atomizes and disperses the paint to form an electrostatic field, and the paint atomized and dispersed from the sprayer is charged, causing an electrostatic adsorption effect. Use it to attach it to the object to be painted. By employing such electrostatic coating, it is possible to improve the adhesion efficiency of paint to the object to be coated, and therefore, it is possible to reduce loss of paint.

When such electrostatic coating is performed, if the object to be coated is metal, a bake-drying paint such as a melamine alkyd resin paint is usually used. The bake-dry paint applied to the object to be painted is cured in a heated atmosphere of, for example, about 140°C. On the other hand, when the object to be painted is made of a material with relatively low heat resistance, such as plastic, a two-component paint consisting of an acrylic resin paint base and a curing agent is used, for example. and,
The two-component paint applied to the object to be painted generally dries and hardens at room temperature, providing good adhesion to the object and providing a coated surface with excellent gloss, hardness, and weather resistance. Become something.

Two-component paints, which have the advantages mentioned above, are cured in a relatively short time when the paint base and curing agent are mixed, so generally the paint base and curing agent are prepared separately. , and are mixed immediately before the coating is applied to the object to be coated.
Therefore, when performing electrostatic painting using such a two-component paint, a mixer is usually provided to mix the paint base and the hardening agent; After mixing, the two-component paint is supplied to an atomizer, and the two-component paint is atomized and dispersed by the atomizer. Therefore, when a color change of the paint base is required, before supplying the new color paint base and curing agent to the mixer, the mixer must be used to remove the old two-component paint that has adhered to the mixer. There is a problem in that the amount of time wasted in cleaning the mixer becomes relatively large in a consistent painting process.

For this reason, for example, as described in JP-A No. 57-45370 or JP-A No. 59-228960, a bell-shaped rotary atomizing head that rotates at high speed while applying a DC high voltage is used. The main paint component and the curing agent constituting the two-component paint are supplied from a plurality of nozzles to the inner circumferential surface of the rotary atomizing head, so that the main paint component and the curing agent are mixed in the rotary atomizing head. A combination of an atomizer and a mixer for mixing a paint base ingredient and a curing agent is used. A rotary atomization electrostatic coating device has been proposed that does not require the use of rotary atomization. In such a rotary atomization electrostatic coating device, in addition to a main agent supply nozzle and a curing agent supply nozzle that supply a paint base agent and a curing agent, respectively, a cleaning agent supply nozzle that supplies a cleaning agent such as thinner is connected to its opening. A configuration is adopted in which the end is located near the inner circumferential surface of the rotary atomizing head. and,
When changing the color of the paint base, after stopping the supply of the paint base and curing agent from the base paint supply nozzle and curing agent supply nozzle, a rotating mist is created using the cleaning agent supplied from the cleaning agent supply nozzle. The inner circumferential surface of the coating head is cleaned to prepare for changing the color of the paint base, and the time loss during the painting process associated with changing the color of the paint base is significantly reduced.

(Problems to be Solved by the Invention) When a rotary atomizing electrostatic coating device as described above is used to apply paint to an object to be coated,
The paint base agent and curing agent supplied to the inner peripheral surface of the rotary atomizing head instantly reach the edge of the rotary atomizing head due to the centrifugal force generated by the high speed rotation of the rotary atomizing head, and are scattered from there. You will be forced to do so. Therefore, the paint base agent and curing agent, which are separately supplied to the inner peripheral surface of the rotary atomizing head from the opening ends of the base agent supply nozzle and the curing agent supply nozzle, are individually scattered from the edge of the rotary atomizing head. As a result, there is a possibility that the rotary atomizing head may not be able to properly mix the paint base material and the curing agent and atomize and disperse them. If the paint base agent and hardener are not properly mixed in the atomized state, the paint base to which the paint base agent and hardener will adhere may be partially coated on the painted surface. There is an inconvenience that an excess or deficiency of the main agent or curing agent occurs, resulting in unevenness in the gloss, hardness, weather resistance, etc. of the painted surface.

Therefore, for example, the base agent supply nozzle and the curing agent supply nozzle are layered so that their respective open ends are overlapped in the direction perpendicular to the rotational axis of the rotary atomization head in the vicinity of the inner peripheral surface of the rotary atomization head. The main paint material and hardening agent supplied from each atomizer are arranged so that they collide at approximately the same position on the inner circumferential surface of the rotary atomizing head, so that the paint main material and hardening agent are properly distributed. It is conceivable to try to obtain a state in which the substances are mixed together and atomized and dispersed. However, even in such a case, if the amounts of the paint base agent and curing agent spouted from the respective opening ends of the base agent supply nozzle and the curing agent supply nozzle are relatively large, the amounts of the paint base agent and curing agent that are ejected from the respective opening ends of the base agent supply nozzle and the curing agent supply nozzle may be reduced. The paint base material and curing agent jetted out from the open end of the rotary atomizing head collide with the hub etc. of the rotary atomizing head, so that a pulsating flow of the paint base material and hardening agent is formed on the inner peripheral surface of the rotary atomizing head. As a result, there is a possibility that the content of the coating material and the curing agent in each of the fine particles atomized and dispersed from the edge of the rotary atomizing head may become non-uniform.

In view of these points, the present invention provides a method for supplying a paint base agent and a curing agent, or a plurality of types of paints individually, to a rotary atomizing head and scattering them from the rotary atomizing head. Regardless of the amount of paint base and curing agent or multiple types of paint used, the paint base and curing agent or multiple types of paint are properly mixed and atomized and dispersed by the rotating atomizing head. The state is obtained, so that
The paint is applied uniformly to the object to be painted,
An object of the present invention is to provide a rotary atomizing electrostatic coating device and an electrostatic coating method using the same, which can provide a coated surface of an object to be coated with excellent gloss, hardness, weather resistance, etc. without any unevenness. purpose.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the rotary atomizing electrostatic coating device according to the present invention has a liquid-contacting surface in the form of an inner surface of a cup having an open end for atomizing and dispersing paint. a rotary atomizing head, a rotary drive means for driving the rotary atomizing head to rotate with a rotational axis surrounded by a liquid contact surface, and an open end facing into the rotary atomizing head. and a plurality of supply nozzles for supplying paint to the liquid contact surface of the rotary atomizing head, the plurality of supply nozzles supplying the paint or a liquid constituting the paint from each of their open ends, In order to spray the liquid almost simultaneously toward a common position on the liquid contact surface of the rotary atomization head, the opening ends of each of the atomization heads are aligned in the direction along the rotation axis of the rotary atomization head in the vicinity of the liquid contact surface of the rotary atomization head. The atomizers are arranged adjacent to each other so as to face the liquid contact surface of the rotary atomizing head, and are bent and arranged so as to face the liquid contact surface of the rotary atomizing head.

Further, in the electrostatic coating method according to the present invention, a rotary atomizing head having a liquid-contacting surface shaped like the inner surface of a cup having an open end is rotated about a rotation axis surrounded by the liquid-contacting surface. The opening ends facing inward are arranged adjacent to each other in the direction along the axis of rotation of the rotating atomizing head in the vicinity of the liquid-contacting surface of the rotating atomizing head so as to face the liquid-contacting surface of the rotating atomizing head. The paint is supplied to the liquid-contacting surface of the rotating rotary atomizing head through a plurality of supply nozzles bent to achieve this, and the paint or the liquid forming the paint is rotated from each of the open ends of the plurality of supply nozzles. The paint is sprayed almost simultaneously toward a common position on the wetted surface of the atomizing head, and the sprayed paint or the liquid that makes up the paint is atomized and dispersed from the open end of the wetted surface of the rotary atomizing head. An electrostatic painting method characterized by applying it to the body.

(Function) In the rotary atomizing electrostatic coating device and the electrostatic coating method using the same according to the present invention configured as described above, the liquid contacting surface of the rotary atomizing head rotationally driven by the driving means. On the other hand, liquid agents constituting multiple types of paints, such as a paint main agent and a curing agent, or each of multiple types of paints, are individually and simultaneously supplied from the respective opening ends of multiple supply nozzles. . At this time, the opening ends of the plurality of supply nozzles are arranged adjacent to each other in the direction along the rotational axis of the rotary atomizing head in the vicinity of the liquid contact surface so as to face the liquid contact surface. Paint main agent and curing agent sprayed from each open end of the supply nozzle,
Alternatively, multiple types of paints will directly collide at approximately the same position on the liquid contact surface without colliding with other parts in the rotary atomization head, and after collision, they will rotate on the liquid contact surface. The atomizing head moves toward the open end of the liquid contact surface while forming overlapping layers in a direction perpendicular to the rotational axis of the atomizing head. For example, the paint main agent and curing agent that form a double layer on the liquid contact surface, or multiple types of paints that form multiple layers on the liquid contact surface, are Atomization is emitted from the open end of the Thereby,
Each of the fine particles of the atomized paint forms a double layer or multiple layers, and as a result, the rotary atomization head properly mixes the paint base and curing agent, or multiple types of paint, and creates a mist. A state in which the paint is diffused is obtained, and the paint is uniformly applied to the object to be painted.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 schematically shows an example of a rotary atomization electrostatic coating device according to the present invention.

In the example shown in FIG. 2, the rotary atomizing head 2 is comprised of a cup-shaped portion 4 and a hub 6 provided in the center of the cup-shaped portion 4. In the example shown in FIG. The cup-shaped portion 4 has a large-diameter opening end 4a and a small-diameter opening end 4.
b, and the cup-shaped inner circumferential surface between them is the liquid contact surface 5. The inner surface of the large-diameter open end 4a of the cup-shaped portion 4 is the open end of the liquid contact surface 5. A large number of through holes 8 are formed at the connection portion between the cup-shaped portion 4 and the hub 6. Further, at the end of the cup-shaped portion 4 of the hub 6 located on the small-diameter open end 4b side, there is provided a small-diameter open end 4 of an air motor 11 for rotationally driving the rotary atomizing head 2.
A rotating shaft 12 extending into the cup-shaped portion 4 is connected via b. By this air motor 11,
The rotary atomizing head 2 is surrounded by the liquid contact surface 5 of the cup-shaped portion 4 and is rotated at high speed with a rotation axis passing through the hub 6 and the center of the rotating shaft 12.

A bracket 14 is fixed to the air motor 11, and at a predetermined position of the bracket 14, a paint supply nozzle section 16 is arranged such that its opening 17 approaches the liquid contact surface 5 through the small-diameter open end 4b of the cup-shaped section 4. At least it's installed. This paint supply nozzle section 16 includes paint supply pipes 20a and 2.
0b and a hardening agent supply pipe 20c
is connected at one end. Paint supply pipe 20
a and 20b are flow rate regulators 22 and 2, respectively.
3, and pumps 26 and 27, the other ends of which are inserted into paint tanks 32 and 33. Further, the curing agent supply pipe 20c is provided with a flow rate regulator 24 and a pump 28, and the other end is inserted into the curing agent tank 34.

Different types of paint bases or paints are stored in the paint tanks 32 and 33. For example, the paint tank 32 stores a paint base made of an acrylic resin paint containing a red pigment, and the paint tank 33 stores an acrylic resin paint containing a white pigment. A paint base consisting of resin paint is stored.
Further, in the curing agent layer 34, for example, an isocyanate-based curing agent is stored. The flow rate regulators 22 to 24 are connected to the paint supply pipes 20a and 2.
It is possible to independently adjust the amounts of the paint base material flowing through the pipe 20b and the amount of the curing agent flowing within the curing agent supply pipe 20c.

Further, a cleaning liquid supply nozzle 18 is attached to the bracket 14 with its open end 18a brought close to the liquid contact surface 5 through the small diameter open end 4b of the cup-shaped portion 4. One end of a cleaning liquid supply pipe 35 is connected to the cleaning liquid supply nozzle 18, and the cleaning liquid supply pipe 35 is provided with a flow rate regulator 36 and a pump 37, and the other end is used to store cleaning liquid such as thinner. Cleaning liquid tank 3
8.

FIGS. 1A and 1B show the above-mentioned paint supply nozzle part 1.
6 and its surroundings are shown enlarged. In a specific example of the paint supply nozzle section 16 shown in FIGS.
6c, and a paint supply nozzle 16a.
and 16b and the curing agent supply nozzle 16c,
Each is connected to one end of each of the paint supply pipes 20a and 20b and the curing agent supply pipe 20c. The paint supply nozzles 16a and 16b and the curing agent supply nozzle 16c are connected to the opening 17 of the paint supply nozzle portion 16 in the vicinity of the liquid contact surface 5 of the cup-shaped portion 4 of the rotary atomizing head 2.
The respective open ends 17a, 17b and 17 forming
c are arranged adjacent to each other in the direction along the rotational axis of the rotary atomizing head 2 so as to face the liquid contact surface 5. For this reason, the tips of the paint supply nozzles 16a and 16b and the curing agent supply nozzle 16c are bent toward the liquid contact surface 5 of the cup-shaped portion 4, as clearly shown in FIG. In this case, the degree of bending of the tips of the paint supply nozzles 16a and 16b and the curing agent supply nozzle 16c is determined relative to the normal line of the liquid contact surface 5 of the paint base material etc. spouted from the opening ends 17a, 17b and 17c. The injection angle θ is set to be, for example, 45 degrees or less.

Although not shown, for example, a DC high voltage is applied between the rotary atomizing head 2, which is composed of the cup-shaped portion 4 and the hub 6, and the object to be coated, with the rotary atomizing head 2 side being the negative pole side. It is made to be done.

When the object to be coated is coated with the above-described configuration, first, the air motor 11 is activated, and the rotary atomizing head 2 is moved to the above-mentioned cup-shaped portion 4 in contact with the liquid. It is surrounded by the surface 5 and rotates at a rotation speed of 20,000 to 30,000 rpm, for example, with a rotation axis passing through the center of the hub 6 and the rotating shaft 12. At this time, the rotary atomizing head 2 has, for example, -
A high DC voltage is applied so that the potential is 90 kV.

In such a state, for example, the pumps 27 and 28 are activated, and the acrylic resin paint base containing the white pigment stored in the paint tank 33 and
The isocyanate curing agent stored in the curing agent tank 34 is guided to the paint supply nozzle 16b and curing agent supply nozzle 16c in the paint supply nozzle section 16 through the paint supply pipe 20b and the curing agent supply pipe 20c. At that time, the flow rate regulator 23
and 24 are metered.

The paint main agent and curing agent respectively guided to the paint supply nozzle 16b and curing agent supply nozzle 16c in the paint supply nozzle section 16 are simultaneously supplied from the opening end 17b of the paint supply nozzle 16b and the opening end 17c of the curing agent supply nozzle 16c. The liquid is ejected and supplied to the liquid contact surface 5 of the cup-shaped portion 4 of the rotary atomizing head 2 rotating at high speed. At this time, the opening end 17b of the paint supply nozzle 16b and the opening end 17c of the curing agent supply nozzle 16c rotate and atomize in the vicinity of the liquid contact surface 5 of the cup-shaped part 4, as shown in FIGS. 1A and 1B. Since they are arranged adjacent to each other in the direction along the rotational axis of the head 2 and face the liquid contact surface 5, the paint main agent ejected from the opening end 17b of the paint supply nozzle 16b and the opening of the curing agent supply nozzle 16c. Even when the amount of curing agent spouted from the end 17c is relatively large, it will directly collide with substantially the same position on the rotating liquid contact surface 5.

In this way, the paint base and curing agent collide at approximately the same position on the rotating liquid contact surface 5.
Thereafter, the large-diameter open end 4 of the cup-shaped part 4 is moved along the liquid-contacting surface 5 and passes through a large number of through holes 8 formed at the connection part between the cup-shaped part 4 and the hub 6.
Forms a flow toward a. Then, the liquid contact surface 5 is collided with substantially the same position on the liquid contact surface 5.
As shown in FIG. 2, the paint main agent and curing agent flowing along the surface are affected by the centrifugal force caused by the high-speed rotation of the rotary atomizing head 2, and as shown in FIG. The main paint component with a high specific gravity forms a layer Fa in contact with the wetted surface 5, and the curing agent with a low specific gravity forms a layer Fi in contact with the layer Fa of the main paint component.
form. That is, the paint main agent and the curing agent form respective layers stacked on the liquid contact surface 5 in a direction perpendicular to the rotational axis of the rotary atomizing head 2, and move toward the open end of the liquid contact surface 5. It will become something you will continue to do. At this time, the paint main agent jetted from the opening end 17b of the paint supply nozzle 16b and the curing agent jetted from the opening end 17c of the hardening agent supply nozzle 16c collide with the hub 6 etc. 5 does not form a pulsating flow.

Then, the paint main agent and curing agent that reach the large-diameter opening end 4a of the cup-shaped portion 4, that is, the open end of the liquid contact surface 5, forming layers Fa and Fi, are transferred to the rotary atomizing head 2 at high speed. Due to the centrifugal force associated with rotation, the wetted surface 5
From the open end of , fine particles R are formed and atomized and dispersed. At that time, the paint main agent and curing agent are used in layer Fa and layer
Since the fine particles R are atomized and dispersed while still forming Fi, each of the fine particles R contains the respective layers of the paint base agent and the curing agent, and the large-diameter opening end of the cup-shaped portion 4 in the rotary atomization head 2 From the part 4a, the atomized paint in which the main paint agent and the curing agent are properly mixed is emitted.

Therefore, a paint obtained by mixing an acrylic resin paint base containing a white pigment and an isocyanate hardener at a weight ratio of 3:1 is uniformly adhered to the surface of the object to be painted. Paint is applied.

After the object to be painted is coated with an acrylic resin paint base containing a white pigment, the other objects to be painted are painted using an acrylic resin paint base containing a red pigment. Therefore, when changing the color of the paint base,
The operation of the pumps 27 and 28 is stopped, and the supply of the paint main agent and curing agent from the paint tank 33 and the curing agent tank 34 is stopped, and the pump 37 provided in the cleaning liquid supply pipe 35 is activated. As a result, the cleaning liquid such as thinner stored in the cleaning liquid tank 38 is supplied to the cleaning liquid supply nozzle 1 through the cleaning liquid supply pipe 35 and the flow rate regulator 36.
Guided by 8. Then, the cleaning liquid guided to the cleaning liquid supply nozzle 18 is supplied from the opening end 18a of the cleaning liquid supply nozzle 18 to the liquid contact surface 5 of the cup-shaped part 4 of the rotating rotary atomizing head 2, and the inside of the rotary atomizing head 2 is supplied. cleaning is performed.

Thereafter, the operation of the pump 37 is stopped, and the pumps 26 and 28 are started, and the acrylic resin paint base and isocyanate hardener containing the red pigment stored in the paint tank 32 and hardener tank 34 are supplied to the paint. The flow rate regulators 22 and 2 are
4 is performed, and the paint supply nozzle section 16
The paint supply nozzle 16a and the curing agent supply nozzle 16c are further connected to the paint supply nozzle 1.
6a and the curing agent supply nozzle 16c are simultaneously ejected from the open end 17a of the paint supply nozzle 16a and the open end 17c of the curing agent supply nozzle 16c, and the rotary atomizing head rotates at high speed. Liquid contact surface 5 of cup-shaped part 4 in 2
supplied for. Also at this time, the opening end 17a of the paint supply nozzle 16a and the opening end 17c of the curing agent supply nozzle 16c rotate in the vicinity of the liquid contact surface 5 of the cup-shaped portion 4, as shown in FIGS. 1A and 1B. They are arranged in the direction along the rotational axis of the atomizing head 2 and face the liquid contact surface 5, so that the paint base sprayed from the open end 17a of the paint supply nozzle 16a and the curing agent supply nozzle 16c are separated. Even when the amount of curing agent spouted from the open end 17c is relatively large, it directly
The liquid will collide with substantially the same position on the rotating liquid contact surface 5.

Therefore, in this case as well, the paint main agent and the curing agent form respective layers that are stacked on the liquid contact surface 5 in a direction perpendicular to the rotational axis of the rotary atomizing head 2, in the same way as in the above case. The liquid then moves toward the open end of the liquid contact surface 5, and is atomized and dispersed from the open end of the liquid contact surface 5. As a result, the atomized paint is dispersed from the large-diameter opening end 4a of the cup-shaped portion 4 in the rotary atomization head 2, with the paint main component and curing agent properly mixed. The surface of the painted body is coated with a paint obtained by mixing an acrylic resin paint base containing a red pigment and an isocyanate curing agent in a predetermined weight ratio, and uniformly adheres to the paint.

In addition, in the example shown in FIG.
6, 27, and 28 were operated simultaneously, and the acrylic resin paint base containing red pigment stored in paint tanks 32 and 33 and the acrylic resin paint base containing white pigment stored in hardener tank 34. The isocyanate curing agent is supplied to the paint supply pipes 20a and 20b and the curing agent supply pipe 2.
The paint is guided to the paint supply nozzles 16a and 16b and the curing agent supply nozzle 16c in the paint supply nozzle section 16 through the paint supply nozzle 0c, and further guided to the paint supply nozzles 16a and 16b and the curing agent supply nozzle 16c, respectively. The main agent and curing agent are
Open ends 17a of paint supply nozzles 16a and 16b
and 17b and the opening end 17c of the curing agent supply nozzle 16c, and may be simultaneously jetted out and supplied to the liquid contact surface 5 of the cup-shaped portion 4 in the rotary atomization head 2 rotating at high speed. . In such a case, the paint supply nozzles 16a and 16b
and the opening end 17c of the curing agent supply nozzle 16c.
The curing agent ejected from the liquid contact surface 5 directly collides with substantially the same position on the rotating liquid contact surface 5.

In such a case, the paint supply nozzle 16
A mixture of two types of paint main ingredients and a curing agent are sprayed from the open ends 17a and 17b of the a and 16b, respectively, and are superimposed on the liquid contact surface 5 in a direction perpendicular to the rotational axis of the rotary atomizing head 2. Each layer is formed and moves toward the open end of the liquid contact surface 5, and is atomized and dispersed from the open end of the liquid contact surface 5. As a result, the acrylic resin paint base containing the red pigment, the acrylic resin paint base containing the white pigment, and the isocyanate curing agent are coated on the surface of the object to be painted.
Paint is applied by uniformly adhering the paint obtained by mixing at a predetermined weight ratio.

Further, unlike the above-described example, the paint tanks 32 and 33 in the example shown in FIG. 2 are configured to store red paint and white paint, such as melamine alkyd paint, respectively. Mixed coating of these two types of paints may be performed.

In such a case, the pumps 26 and 27 are operated, and the red paint and white paint stored in the paint tanks 32 and 33 are metered by the flow rate regulators 22 and 23 through the paint supply pipes 20a and 20b. and are guided to the paint supply nozzles 16a and 16b, respectively, in the paint supply nozzle section 16,
Furthermore, the paint introduced to the paint supply nozzles 16a and 16b is supplied to the paint supply nozzles 16a and 16b, respectively.
The liquid is simultaneously ejected from the open ends 17a and 17b of the atomizer 6b, and is supplied to the liquid contact surface 5 of the cup-shaped portion 4 in the rotary atomizing head 2 rotating at high speed. In such a case, the paint ejected from the open ends 17a and 17b of the paint supply nozzles 16a and 16b, respectively, will directly collide with substantially the same position on the rotating liquid contact surface 5.

In this case, the paint supply nozzle 16a
The two types of paint sprayed from the open ends 17a and 17b of the rotary atomizing head 2 are stacked on the liquid contact surface 5 in a direction perpendicular to the axis of rotation of the rotary atomizing head 2 according to their specific gravity. to form the wetted surface 5
The liquid moves toward the open end of the liquid contact surface 5, and is atomized and dispersed from the open end of the liquid contact surface 5. As a result, the surface of the object to be painted is coated with a mixed paint obtained by mixing red paint and white paint in a predetermined weight ratio, which is uniformly adhered to the surface.

Next, as described above, when two types of paint are made to collide with the liquid contact surface 5 of the cup-shaped part 4 in the rotary atomizing head 2, the injection angle θ of each paint with respect to the normal to the liquid contact surface 5 is determined. The relationship with the coating state of the object to be coated will be described with reference to the graph shown in FIG.

In the graph in Figure 3, the horizontal axis shows the spray angle θ, and the vertical axis shows the painted surface of the object to be painted and the two types of paint calculated using a color difference meter based on Hunter's color difference formula. The color difference ΔE from a standard coated plate on which the mixed paint obtained by sufficiently mixing the paint was applied extremely homogeneously was measured, and an experiment was conducted to determine the color difference ΔE by setting the jetting angle θ. The solid line α, the broken line β, and the dashed-dotted line γ show the results of repeated experiments.
ml/min, 200ml/min and 50ml/min. From this experimental result, when the ejection angle θ is 60 degrees or more, the amount of paint ejected is 300ml/min,
The value of color difference ΔE is large regardless of whether it is 200 ml/min or 50 ml/min, and if the ejection angle θ is 45 to 60 degrees, the value of color difference ΔE will be large if the amount of paint ejected is relatively small. However, when the amount of sprayed paint is relatively large, the value of color difference ΔE is not small.On the other hand, when the spray angle θ is 45 degrees or less, the color difference ΔE is not small. The color difference ΔE value is small not only when the amount of paint applied is relatively small, but also when it is relatively large, and the painted surface of the object to be painted can be coated with a good, uniform coating. be understood.

Therefore, when electrostatic coating is performed using a rotary atomizing electrostatic coating device according to the present invention in which the jetting angle θ is 45 degrees or less as described above, the coating surface of the object to be coated is extremely I know it will be excellent.

In the above example, the paint supply nozzle section 16 includes a curing agent supply nozzle in addition to the paint supply nozzle, but instead of the paint supply nozzle section 16, a plurality of paint supply nozzles may be used. It is also possible to use a paint supply nozzle section formed by a chisel.

(Effects of the Invention) As is clear from the above explanation, according to the rotary atomizing electrostatic coating device and the electrostatic coating method using the same according to the present invention, the paint base material can be applied to the rotary atomizing head for electrostatic coating. and a curing agent, or when supplying multiple types of paint individually and scattering them from the rotary atomizing head, the paint base material and the curing agent supplied to the liquid contact surface of the rotary atomizing head, or, Multiple types of paint are directly collided with each other at approximately the same position on the wetted surface, forming respective layers that overlap in a direction perpendicular to the axis of rotation of the rotary atomizing head on the wetted surface, while opening the wetted surface. It moves toward the end and is atomized and dissipated from the open end of the wetted surface.
A state is obtained in which the paint main ingredient and the curing agent, or a plurality of paints, are properly mixed and atomized and dispersed. Therefore, it is possible to uniformly apply the paint to the object to be painted, and the painted surface of the object to be painted can be made to have excellent gloss, hardness, weather resistance, etc. without any unevenness. .

[Brief explanation of drawings]

FIGS. 1A and 1B are a perspective view and a cross-sectional view, including a partially broken surface, showing essential parts of an example of a rotary atomizing electrostatic coating apparatus according to the present invention, and FIG. 2 is a rotary atomizing electrostatic coating apparatus according to the present invention. Schematic configuration diagram showing an example of a coating device, Part 3
The figure is a graph used to explain the coating state of an object to be coated using the examples shown in FIGS. 1 and 2. In the figure, 2 is a rotating atomizing head, 4 is a cup-shaped part,
5 is a liquid contact surface, 11 is an air motor, 16 is a paint supply nozzle part, 16a and 16b are paint supply nozzles,
16c is a curing agent supply nozzle, 17 is an opening, 17
a, 17b and 17c are open ends, 20a and 20
b is a paint supply pipe, 20c is a curing agent supply pipe, 32 and 33 are paint tanks, and 34 is a curing agent tank.

Claims (1)

[Scope of Claims] 1. A rotary atomizing head having a wetted surface in the form of an inner surface of a cup having an open end for atomizing and dispersing paint, and a rotating axis surrounding the rotary atomizing head by the wetted surface. and a rotary drive means for driving the rotary atomizing head to rotate, and an open end facing into the rotary atomizing head, and supplying paint to the liquid contact surface of the rotary atomizing head. a plurality of supply nozzles, each of which supplies the paint or a liquid forming the paint from its respective open end;
In order to eject liquid substantially simultaneously toward a common position on the liquid contact surface of the rotary atomization head, the opening ends are aligned along the rotation axis of the rotary atomization head in the vicinity of the liquid contact surface of the rotary atomization head. A rotary atomizing electrostatic coating device characterized in that the rotary atomizing electrostatic coating device is arranged adjacent to each other in the direction and bent so as to face the liquid contacting surface of the rotary atomizing head. 2. A rotary atomizing head having a liquid contact surface shaped like the inner surface of a cup having an open end is rotated about a rotation axis surrounded by the liquid contact surface, and an open end facing into the rotary atomization head. are arranged adjacent to each other in the direction along the axis of rotation of the rotary atomizing head in the vicinity of the liquid contact surface of the rotary atomizing head and are bent so as to face the liquid contact surface of the rotary atomizing head. The paint is supplied to the liquid-contacting surface of the rotary atomizing head in a rotating state through a plurality of supply nozzles, and the paint or the liquid constituting the paint is applied from each of the open ends to the liquid-contacting surface of the rotary atomizing head. An electrostatic coating characterized in that the paint is ejected almost simultaneously toward a common position, and the ejected paint or the liquid forming the paint is atomized and dispersed from the open end of the liquid-contacted surface to adhere to the object to be painted. Method.