JPH1110028A - Rotary spray coating device and electrostatic coating method using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of sprayed particles and to minutely spray a coating by using an anodically oxidized aluminum as the material of a spraying head and applying silicate treatment to the surface in contact with liquid of the spraying head. SOLUTION: The anodically oxidized aluminum, that is, the one obtained by executing a sulfuric acid electrolytic treatment in the aluminum so as to form an anodically oxidized film, is used as the material of the spraying head 1. The silicate treatment executed by an alkali metal silicate and polyvinyl phosphonic acid to form alkali silicate on the liquid contact surface 2. Polyvinyl phosphonic acid is acted as a catalyst in a silicate processing. Polyvinyl can be used in place of polyvinyl phosphonic acid in the silicate treatment. Thereafter, a thermal treatment is executed to fix a prescribed vitreous film. Thus, the coating having the highly uniform particles is applied to obtain a photosensitive printing plate without a nonuniformity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating apparatus used for electrostatic coating which atomizes paint and imparts electric charge to the atomized paint particles to increase the coating efficiency by electrostatic force. In particular, the present invention relates to a spray head of a rotary atomizer used in a process of manufacturing a photosensitive printing plate using a water-soluble resin aqueous solution as a coating material.

[0002]

2. Description of the Related Art A conventional rotary atomizing electrostatic coating apparatus is disclosed in, for example, JP-A-63-229163. FIG. 9 shows the structure of the rotary atomizing electrostatic coating apparatus described in the above publication. The rotary atomizing electrostatic coating apparatus 100 shown in FIG. 9 includes a spray head 102 fixed to a rotating shaft 101,
It mainly comprises a high voltage generator 103 for applying a high voltage between the rotating shaft 101 and the object to be coated, and a paint supply nozzle 104 for supplying paint into a spray head 102 rotating at a high speed. The paint supplied from the paint supply nozzle 104 into the annular space 102a of the spray head 102 rotating at a high speed flows out of a large number of paints which are annularly formed at the bottom of the cup-shaped inner peripheral surface 102b of the spray head 102. It flows out along the inner peripheral surface 102b through the hole 102c, and the spray head 10
2 so as to become negatively-charged paint particles from the tip 102d and emitted toward the object to which the high voltage on the positive side is applied by the high voltage generator 103. Has become.

[0003]

However, in the above-described conventional rotary atomizing electrostatic coating apparatus 100, the paint flowing out of each paint outlet 102c is difficult to spread uniformly on the inner peripheral surface 102b of the spray head 102. However, there is a tendency that the paint flowing into the spray head 102 reaches the tip end portion 102d with a large number of radially separated paint flows without being merged with the paint flowing out from the adjacent paint outlet hole 102c.
For this reason, when the paint flow is released as a thin liquid thread from the peripheral portion of the tip end portion 102d, and is then cut to form particles, the liquid thread formed from a portion adjacent to the non-wet portion is formed on the surface. Under the influence of tension, the thickness becomes thicker than the other parts, and the size of the particles cut therefrom becomes larger than the particles generated in the other parts, and the uniformity of the particles deteriorates. This may be a problem in the performance of this type of rotary atomizing electrostatic coating apparatus.

In addition, when the wetted surface spreads poorly and the wetted surface cannot be completely wet at a point close to the periphery of the wetted surface at the time of the first liquid supply, continuous rotary atomization is performed. Even when the electrostatic coating apparatus is operated, it is operated without leaving a wet surface up to the periphery without spreading out from there, which may deteriorate the uniformity of particles as described above. In the case of the cup type, the air in the cup is scattered around by the centrifugal force to generate a flow of air rotating along the inner peripheral surface of the cup (this is called air pumping).
Therefore, the particles atomized at the peripheral portion may adhere to the inner peripheral surface of the cup again. At this time, if there is a surface that is not wet by the paint for the above-described reason, particles adhere to and accumulate in that portion with the passage of time, increasing the moment of inertia of the rotary atomizing unit, and increasing the rotational speed. There is also a problem that a decrease is caused and stable particle formation is hindered.
In particular, in the manufacturing process of a photosensitive printing plate, the uniformity of the particles has a significant effect on the performance thereof, and thus improving the uniformity of the particles has become an important issue in the process.

The present invention has been made in view of the above-mentioned problems in the conventional rotary atomizing electrostatic coating apparatus, and has high uniformity of sprayed particles and can perform fine paint spraying. It is an object of the present invention to provide a rotary atomizing electrostatic coating apparatus capable of improving coating quality and improving the performance of a photosensitive printing plate, and an electrostatic coating method using the same.

[0006]

According to a first aspect of the present invention, there is provided a rotary atomizing electrostatic coating apparatus using anodized aluminum as a material for a spray head (atomizing head). The liquid contact surface of the spray head is subjected to a silicate treatment. In a second aspect, titanium oxide photocatalyst powder is sintered on the liquid contact surface of the spray head. A third aspect is characterized in that a porous body obtained by sintering aluminum powder is used as the material of the spray head, and the liquid-contact surface of the spray head is impregnated with the liquid paint in advance.

[0007] In order to solve the above-mentioned problems, a fourth aspect of the present invention is described.
In the aspect, the electrostatic coating method is characterized in that the contact angle of the liquid paint with respect to the liquid contact surface of the spray head is 30 degrees or less.

The rotary atomizing electrostatic coating apparatus according to each of the above aspects of the present invention is characterized in that the coating material supplied to the inner or outer peripheral surface of the rotating cup-shaped or disk-shaped spray head is sprayed from the peripheral edge of the tip surface of the spray head. It is generally applied to a rotary atomizing electrostatic coating device that discharges after being formed into a liquid, and the contact angle of the coating with the liquid contact surface of the spray head can be set to 30 degrees or less. According to the above viewpoints, the contact angle of the liquid contact surface with the paint is set to 30 degrees or less by forming the liquid contact surface by using a titanium oxide photocatalyst or by forming the liquid contact surface by using a porous body. This can be achieved by adding a paint to the porous body or adding a fluorine-based surfactant having a water-soluble and surface tension-reducing ability to the paint.

In the rotary atomizing electrostatic coating apparatus according to the first aspect, the contact angle of the liquid contact surface of the spray head with the coating material is 30 degrees or less without using a surfactant. Therefore, since the paint easily spreads on the liquid contact surface, even when the paint supply holes of the spray head are formed apart from each other, the paint immediately spreads on the liquid contact surface and spreads on the liquid contact surface. A liquid thin film is formed along the periphery of the spray head while forming a thin uniform liquid film, and at the tip of the peripheral portion, it becomes a fine liquid thread with a uniform thickness along the periphery of the peripheral portion, and is immediately cut and released as particles Is done. In addition, since the paint spreads uniformly on the liquid contact surface, there is no change in the film thickness due to surface tension at the boundary with the non-wet portion, and by forming a liquid thread of uniform thickness The uniformity of the generated particles can be improved.

In the rotary atomizing electrostatic coating apparatus in which the liquid contact surface according to the second aspect is formed by a titanium oxide photocatalyst, the surface is chemically illuminated by the catalytic effect of the titanium oxide itself by irradiating necessary light as needed. Hydrophobic molecules adsorbed on the adsorbed water are decomposed, and a hydrophilizing effect is exhibited by exposing the chemically adsorbed water, so that the contact angle between the liquid contact surface and the paint is 30 even without using a surfactant. Degrees or less, and an effect similar to that of the device of the first viewpoint can be obtained.

[0011] In the rotary atomizing electrostatic coating apparatus according to the third aspect, the liquid contact surface is formed of a porous material, and the coating material itself is impregnated in the porous material, thereby eliminating the use of a surfactant. Even so, the contact angle between the liquid contact surface and the paint becomes 30 degrees or less, and the same effects as those of the first and second viewpoints can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Based on the first viewpoint, the silicate treatment of the liquid contact surface of a spray head made of anodized aluminum oxide can be performed by using alkali metal silicate and polyvinylphosphonic acid, and the liquid contact surface is treated with alkali silicate. Salt is formed. Polyvinylphosphonic acid acts as a catalyst in the silicate treatment. In the silicate treatment, polyvinyl can be used instead of polyvinyl phosphonic acid. Preferably, the weight ratio of Na ₂ O to SiO ₂ is 3
0 to 70 wt%, 10 to 50 at a processing temperature of 70 to 500 ° C
For 0 minute, the weight ratio between the alkali metal silicate and the polyvinylphosphonic acid is 40 to 70 wt%. The alkali element in the alkali silicate may be any of Na, K, Li and the like. Organic silicate and ammonium silicate can also be used. After the silicate treatment, heat treatment is preferably performed at 60 to 200 ° C. for 10 to 60 minutes to fix a predetermined glassy film.

In the case where the liquid contact surface of the spray head is formed by a titanium oxide photocatalyst based on the second viewpoint,
A powder having an average particle size of 0.1 to 800 μm is
And sinter. At the time of coating, visible light is sufficient as light for irradiating the liquid contact surface made of titanium oxide photocatalyst, and ultraviolet light may be used.

Based on the third point of view, when a porous body obtained by sintering aluminum powder is used as the material of the spray head, powder having an average particle size of 0.3 to 800 μm is preferably used.
Sinter at 1200-2100 ° C. The density of the porous alumina is preferably 40 to 70% of the theoretical density.

In the rotary atomizing electrostatic coating apparatus according to the first to third aspects, unlike a conventional apparatus using a SUS spray head, the use of a surfactant is not essential. On the other hand, by adding a fluorine-based surfactant having water solubility and surface tension lowering ability, wettability is further improved.

In the above-described rotary atomizing electrostatic coating apparatus according to the first to third aspects, the liquid spraying of the spray head is substantially parallel to the radial direction of the spray head at substantially equal intervals on the periphery of the liquid contact surface. A means for guiding the liquid paint flowing on the surface substantially uniformly in a divided manner and guiding the liquid paint outward in the radial direction is preferably provided. Making the peripheral edge into a saw blade shape by forming a notch (a liquid thread is formed only from the tip of the saw blade shaped portion formed on the peripheral edge);
A baffle plate is formed at the periphery of the liquid contact surface at substantially equal intervals in a direction substantially parallel to the radial direction of the spray head, or at a peripheral portion of the liquid contact surface at substantially equal intervals in a direction substantially parallel to the radial direction of the spray head. The formation of such a groove and the formation of a liquid flow path having a uniform shape in the peripheral portion can further improve the uniformity of the liquid yarn and can surely improve the uniformity of the generated particles.

Even when the concentration of the water-soluble resin solution (paint) to be sprayed is about 20% or more, the contact angle can be made 30 degrees or less. Preferably, a water-soluble resin solution having a concentration of about 30% or less is used.

Further, by setting the contact angle of the liquid paint to the liquid contact surface of the spray head to 30 degrees or less (0 to 30 degrees), good liquid contact surface wetness is obtained and coating quality is improved.
Preferably, this contact angle is 20 degrees or less, and more preferably 10 degrees or less.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. First, the configuration and operation of the rotary atomizing electrostatic coating apparatus used in the following coating test will be described.

FIGS. 1 and 2 are views for explaining a rotary atomizing electrostatic coating apparatus used in a coating test. FIG. 1 is a front view of a spray head of the rotary atomizing electrostatic coating apparatus. FIG. 2 is a side sectional view.

In the rotary atomizing electrostatic coating apparatus shown in FIGS. 1 and 2, a cup-shaped (cone-shaped) inner peripheral surface is provided on a flange portion 14 of a rotating shaft 10 which is rotated at a high speed by a drive motor 9. The spray head 1 having an annular opening is fixed by a spray head mounting bolt 6. A paint supply nozzle 8 extends through the rotary shaft 10 to an intermediate portion in the spray head 1. A liquid diffusion plate 4 is fixed to the spray head 1 by a liquid diffusion plate mounting bolt 5 in front of the paint supply nozzle 8. Here, on the inner peripheral surface of the spray head 1, the paint supply nozzle 8 side from the liquid diffusion plate 4 is in contact with the liquid supply unit inner liquid contact surface 17,
The opening side of the liquid diffusion plate 4 is referred to as a liquid supply surface outside liquid contact surface 18. Between the outer peripheral surface of the liquid diffusion plate 4 and the inner peripheral surface of the spray head 1,
A slit-shaped liquid outflow hole 11 is provided. The liquid outflow hole 11 is formed by a liquid diffusion plate mounting bolt 5 for fixing the liquid diffusion plate 4 and a plurality of spacers 13 mounted around the liquid diffusion plate mounting bolt 5 to maintain a circumferential clearance of the liquid outflow hole. It is divided into a plurality of outlet holes. The liquid outflow hole 11 communicates between the spray head paint supply unit (internal cavity) 7 and the cone-shaped opening side. The surface of the liquid diffusion plate 4 that faces the paint supply nozzle 8 is a conical recess 4a having a predetermined cone angle θ so that the paint supplied from the paint supply nozzle 8 changes direction. The cone angle θ is 30 degrees or more, preferably 60 degrees or more. A high negative voltage is applied to the spray head 1 by a high voltage generator (not shown), so that a negative charge is applied to the atomized paint particles.

In this rotary atomizing electrostatic coating apparatus, when the liquid is ejected from the paint supply nozzle 8 toward the vicinity of the center of the liquid diffusion plate 4 fixed to the spray head 1, the paint is applied to the liquid diffusion plate 4. Then, the liquid flows uniformly to the peripheral portion of the liquid diffusion plate 4 by centrifugal force, and flows out from the liquid outflow hole 11 to the liquid contact surface 2 of the spray head 1. At the peripheral portion, the coating material forms a liquid thread, and then the particles generated by cutting the liquid thread are applied to an object to be coated by the action of a negative charge.

In the rotary atomizing electrostatic coating apparatus constructed and operated as described above, the liquid contact surface of the spray head was formed of various materials, and an electrostatic coating test was performed.

[Comparative Example 1] With a φ100 mm cup-type rotary spray head formed of SUS304, the amount of liquid sent was 60 c.
Electrostatic coating was performed on the photosensitive printing plate at c / min. The operation was performed at a rotation speed of the rotary spray head of 15,000 rpm. At this time, an aqueous solution of an acrylic acid ester, a copolymer of acrylic acid and methacrylic acid was used as a coating material, and the respective molar fractions during polymerization were 30/30/40. The liquid concentrations were 10, 20, and 28%, and the coating quality of the photosensitive printing plate after coating and the liquid contact surface of the rotary spray head were compared for each. As a result of measuring the contact angle between SUS304, which is a material of the liquid contact surface, and the paint by a drop method using a contact angle meter CA-D manufactured by Kyowa Interface Science, the contact angle was 42 degrees, respectively.
46 degrees and 54 degrees.

The continuous operation of the rotary atomizing electrostatic coating apparatus was performed for 30 minutes for coating. As a result, there was no remarkably coarse particles at 10% liquid, the coating surface quality was good, and the wetted surface of the liquid contacting surface was unremoved. I couldn't see it. With the 20% and 28% liquids, coarse particles were observed on a part of the painted surface, and the quality of the painted surface was deteriorated. Further, both the 20% liquid and the 28% liquid showed residual wet on the liquid contact surface, and in particular, with the 28% liquid, it was also observed that the atomized particles adhered to the remaining wet portion, dried and deposited.

Example 1 After being formed from aluminum and forming an anodic oxide film by sulfuric acid electrolytic treatment, silicate treatment with an alkali metal silicate and polyvinylphosphonic acid was performed as described in the section of the embodiment. The same test as in Comparative Example 1 was conducted using a φ100 mm cup-type rotary spray head. As a result of measuring the contact angle between the liquid contact surface and the paint, the contact angles were 23 degrees, 26 degrees, and 34 degrees, respectively.

As a result of continuous operation of the rotary atomizing electrostatic coating apparatus for 30 minutes, there was no remarkably coarse particles in the 10% or 20% liquid, the coating surface quality was good, and there was no wet residue on the liquid contact surface. Did not. In the case of the 28% liquid, slightly coarse particles were observed on a part of the coated surface, and the quality of the coated surface was slightly deteriorated. In the case of the 28% liquid, a slight wet residue is seen on the liquid contact surface,
It was also observed that the atomized particles adhered and dried and deposited on the remaining wet portion.

Example 2 A titanium oxide photocatalyst powder formed of SUS304 and having a liquid contact surface of about 25 μm
The same test as in Comparative Example 1 was performed using a φ100 mm cup-shaped rotary spray head formed by sintering at 0 ° C. for 6 hours. As a result of measuring the contact angle between the liquid contact surface and the paint, the contact angles were 3, 5, and 15 degrees, respectively.

As a result of the continuous operation of the rotary atomizing electrostatic coating apparatus for 30 minutes, all the 10%, 20%, and 28% liquids did not have remarkably coarse particles, had good coating surface quality, and had wetted liquid contact surfaces. The rest was not seen.

Example 3 An aluminum powder having a particle size of about 500 .mu.m was sintered at about 1600.degree. C. for about 8 hours with a .phi.100 mm cup-shaped rotary spray head formed from a porous body. Comparative Example 1
The same test was performed. As a result of measuring the contact angle between the wetted surface impregnated with the paint and the paint, the contact angle was about 0 ° for the 10 and 20% liquids and about 6 ° for the 28% liquid.

As a result of continuous operation of the rotary atomizing electrostatic coating apparatus for 30 minutes, there was no remarkably coarse particles in all of the 10%, 20% and 28% liquids, the coating surface quality was good, and the wetted surface was wet. The rest was not seen.

Example 4 φ formed by SUS304
Example 1 Using a 100 mm cup-type rotary spray head, a solution in which a fluorine-based surfactant F-120 manufactured by Dainippon Ink Co., Ltd. was added to the paint by 0.1% based on the solid content of the paint.
The same test was performed. As a result of measuring the contact angles between the liquid contact surface and the paint, the contact angles were 18 degrees, 20 degrees, and 25 degrees, respectively.

As a result of the continuous operation of the rotary atomizing electrostatic coating apparatus for 30 minutes, all the 10%, 20%, and 28% liquids did not have remarkably coarse particles, had good coating surface quality, and had wetted surfaces. The rest was not seen.

Table 1 shows the results of Comparative Example 1 and Examples 1-4.
Are shown together.

[0035]

[Table 1]

According to the above coating test, in Comparative Example 1,
The paint flow obstructed by the spacer 13 (see FIG. 2) reached the peripheral portion without spreading as it was, leaving a residue on the liquid contact surface. FIG. 3 is a diagram showing a state where a residue remaining on the liquid contact surface of the spray head is formed. In FIG.
Reference numerals 9 and 20 indicate the remaining wet parts. In contrast,
According to Examples 1 to 4, since the paint flow obstructed by the spacer 13 spreads quickly on the liquid contact surface, no wet residue as indicated by 19 or 20 in FIG. 3 was generated.

Further, when the above-mentioned paint having a concentration of 8% was sprayed using the aluminum spray head of Example 1 and the SUS spray head of Comparative Example 1, respectively, the paint flowing on the liquid contact surface of the spray head was used. The flow was turned into a liquid thread and the state of further atomization was photographed using a microscope. 4 and 5 are photographs directly observing the liquid thread formation and atomization phenomena using a microscope. FIG. 4 shows an apparatus using the spray head of Example 1, and FIG. 5 shows a spray head of a comparative example. 5 are photographs taken by an apparatus using.

According to the embodiment, as shown in FIG. 4, a liquid thread 21 having a uniform thickness is formed to prevent the flow of the paint from being uniformly wetted and spread on the liquid contact surface, and to prevent the occurrence of unwetting. It was found that fine particles having a high particle size were generated. On the other hand, according to the comparative example, an extremely thick liquid thread 23 is formed at a portion adjacent to the wet residue indicated by reference numeral 22 in FIG. 5, and the size of the particles cut therefrom is generated in other portions. It was found that the particles were larger than the particles to be formed, the uniformity of the particles was deteriorated, and coarse particles were generated.

FIG. 1 shows another embodiment of the present invention.
A preferred modification of the rotary atomizing electrostatic device shown in FIG. 2 will be described.

The apparatus shown in FIG. 6 has a notch provided at substantially equal intervals with respect to the peripheral edge of the liquid contact surface, and the peripheral edge is formed in a saw blade shape. According to this apparatus, the paint that has reached the peripheral edge of the liquid contact surface is guided to the outer peripheral portion formed in a saw blade shape, and the paint forms a uniform film in the circumferential direction of the peripheral edge portion.
4 Form a liquid thread from the tip. Therefore, it is possible to reliably form a uniform liquid thread over the circumferential direction of the spray head, and to form particles with higher uniformity.

In the apparatus shown in FIG. 7, baffle plates 25 are attached to the peripheral edge of the liquid contact surface at substantially equal intervals in a radial direction at substantially equal intervals.
Or it is processed. The paint that has reached the peripheral edge of the liquid contact surface is guided to flow channels having a uniform shape in the circumferential direction of the spray head formed by the baffle plate 25, and forms a liquid thread from the front end of each flow channel. Therefore, the paint forms a uniform film in the circumferential direction of the peripheral portion, and can reliably form a uniform liquid thread over the circumferential direction of the spray head, and can form particles with higher uniformity. .

FIG. 8 shows a case where grooves 26 are formed in the periphery of the liquid contact surface at substantially equal intervals substantially parallel to the radial direction of the spray head. The paint that has reached the liquid contact surface periphery is guided to the groove 26,
A liquid thread is formed from the front end of each channel. Therefore, the paint forms a uniform film in the circumferential direction of the peripheral portion, and can reliably form a uniform liquid thread over the circumferential direction of the spray head, and can form particles with higher uniformity. .

[0043]

As described above, in the rotary atomizing electrostatic coating apparatus of the present invention, even when a commonly used coating material is used at a high concentration, it is possible to use a surfactant without using a surfactant. The contact angle of the paint to the liquid contact surface with the spray head can be made 30 degrees or less, and even if the paint flows out from the discontinuously formed liquid outflow hole to the liquid contact surface, the paint quickly spreads over the whole liquid contact surface. The liquid thread having a uniform thickness is formed by forming a uniform liquid film on the peripheral edge portion by spreading the liquid in a uniform manner, thereby forming highly uniform particles. By applying the rotary atomizing electrostatic coating apparatus and method of the present invention to the manufacturing process of a photosensitive printing plate, coating with highly uniform particles is performed, and it is possible to obtain a photosensitive printing plate without unevenness. A significant performance improvement is achieved.

In the rotary atomizing electrostatic coating method of the present invention, by setting the contact angle of the paint to the liquid contact surface of the spray head to 30 degrees or less, good wettability of the paint to the liquid contact surface can be obtained. , The paint quickly spreads over the entire wetted surface,
By forming a uniform liquid film at the peripheral portion, a liquid thread having a uniform thickness is formed, thereby forming particles with high uniformity.

Further, the liquid paint flowing on the liquid contact surface of the spray head is divided substantially uniformly at the peripheral edge of the liquid contact surface at substantially equal intervals in a direction substantially parallel to the radial direction of the spray head and radially outward. Preferably, notches are provided at substantially equal intervals with respect to the liquid contact surface peripheral portion of the spray head to form a saw-toothed peripheral portion, or the spray head is provided at the liquid contact surface peripheral portion. It is possible to form a groove whose width gradually increases toward the outer periphery at substantially equal intervals in a direction substantially parallel to the radial direction, or to place a baffle plate at the peripheral edge of the liquid contact surface at a substantially parallel and substantially equal interval in the radial direction. By attaching or processing, the formation state of the liquid thread can be made more uniform, and more uniform particle formation can be realized.

[Brief description of the drawings]

FIG. 1 is a front view of a rotary spray head of a rotary atomizing electrostatic coating apparatus used for a test.

FIG. 2 is a side sectional view of the rotary atomizing electrostatic coating apparatus shown in FIG.

FIG. 3 shows a rotary atomizing electrostatic coating apparatus according to a comparative example.
It is explanatory drawing which shows the result of having observed the nonuniformity of the spreading of the paint on the liquid contact surface of a rotary spray head.

FIG. 4 is a photograph showing a particle structure for showing the result of observing the actual atomization state of a rotary spray head with a microscope using the rotary atomizing electrostatic coating apparatus according to the first embodiment of the present invention. is there.

FIG. 5 is a photograph showing a particle structure for showing the result of observing the actual atomization state of a rotary spray head with a microscope using the rotary atomizing electrostatic coating apparatus according to Comparative Example 1.

FIG. 6 is a perspective view showing an example in which the periphery of a rotary spray head is machined into a saw blade shape according to another embodiment of the present invention.

FIG. 7 is a perspective view showing a working example in which a baffle plate is attached to a peripheral portion of a rotary spray head according to another embodiment of the present invention.

FIG. 8 is a perspective view showing an example in which a groove is formed in a peripheral portion of a rotary spray head according to another embodiment of the present invention.

FIG. 9 is a sectional view showing a conventional rotary atomizing electrostatic coating apparatus.

[Explanation of symbols]

Reference Signs List 1 rotary spray head 2 rotary spray head liquid contact surface 3 rotary spray head peripheral edge outer periphery 4 liquid diffusion plate 4a recess (liquid diffusion plate liquid diffusion unit) 5 liquid diffusion plate mounting bolt 6 spray head mounting bolt 7 spray head paint supply unit 8 Paint supply nozzle 9 Drive motor 10 Rotating shaft 11 Liquid outflow hole 13 Spacer 14 Flange part 17 Liquid supply part inner liquid contact surface 18 Liquid supply part outer liquid contact surface 19 Contact generated due to impediment of wettability of paint by spacer Liquid surface wetting residue 20 Liquid surface wetting residue generated due to impeded wetting and spreading of paint by spacer

Claims (10)

[Claims] 1. A rotary atomizing coating apparatus for discharging and spraying liquid paint supplied to a rotating cup-shaped or disk-shaped spray head from a peripheral portion of the tip of the spray head, wherein the material of the spray head is anodized. A rotary atomizing coating apparatus, wherein aluminum is used, and a liquid contact surface of the spray head is subjected to a silicate treatment. 2. A rotary atomizing coating apparatus for discharging liquid paint supplied to a rotating cup-shaped or disk-shaped spray head from a peripheral portion of a tip of the spray head and atomizing the liquid paint. Is a rotary atomizing coating apparatus characterized by sintering titanium oxide photocatalyst powder. 3. A rotary atomizing coating apparatus for spraying liquid paint supplied to a rotating cup-shaped or disk-shaped spray head from a peripheral portion of a tip of the spray head to atomize, wherein aluminum powder is used as a material of the spray head. A rotary atomizing coating apparatus, characterized in that a porous body obtained by sintering is used, and the liquid contact surface of the spray head is impregnated with the liquid paint in advance. 4. The liquid paint flowing on the liquid contact surface of the spray head is substantially uniformly divided at substantially equal intervals substantially parallel to the radial direction of the spray head on the periphery of the liquid contact surface. A means for guiding in a radially outward direction is provided.
3. The rotary atomizing coating apparatus according to any one of 3. 5. A guide according to claim 4, wherein said guiding means is a notch in a peripheral portion of said liquid contact surface, which is substantially parallel to a radial direction of said spray head and at substantially equal intervals. Rotary atomizing coating equipment. 6. The guide according to claim 4, wherein said guiding means is a baffle plate at a peripheral portion of said liquid contact surface, substantially parallel to a radial direction of said spray head and at substantially equal intervals. Rotary atomizing coating equipment. 7. The rotating device according to claim 4, wherein said guiding means is a groove formed in a peripheral portion of said liquid contact surface at substantially equal intervals in a direction substantially parallel to a radial direction of said spray head. Type atomizing coating equipment. 8. An electrostatic coating method in which a liquid paint supplied to a rotating cup-shaped or disk-shaped spray head is discharged from a peripheral portion of a tip of the spray head and atomized, wherein the liquid with respect to a liquid contact surface of the spray head is sprayed. An electrostatic coating method wherein the contact angle of the paint is 30 degrees or less. 9. The electrostatic coating method according to claim 8, wherein a fluorinated surfactant is added to the liquid coating. 10. The electrostatic coating method according to claim 8, wherein the rotary atomizing coating apparatus according to claim 1 is used.