JP2002254850A - Device for electrostatic coating, method of electrostatic coating, and method of manufacturing photo-sensitive lithographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time for changing the lot of a photo-sensitive lithographic printing plate by making it unnecessary to supplement or change liquid by stopping a device. SOLUTION: A unit A, consisting of a rotary atomizer 26A, a high voltage power supply 32A, a foreign matter filter 44A, a liquid sending pump 46A and a paint tank 48, and a unit B, consisting of another atomizer 26B, another high voltage power supply 32B, another foreign matter filter 44B, another liquid sending pump 46B and another paint tank 48B, are provided so as to be exchangeable whereby the switching work of pipeline becomes unnecessary and washing work as well as a flow rate confirming work accompanied by the switching work of the pipeline become unnecessary thereby permitting the shortening of the time for changing the lot of the photo-sensitive lithographic printing plate 10 remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating device for electrostatically applying a paint, and more particularly to an electrostatic coating device for forming a mat on a photosensitive layer of a photosensitive lithographic printing plate. And a method for producing a photosensitive lithographic printing plate.

[0002]

2. Description of the Related Art In an image exposure process for forming an image on a photosensitive lithographic printing plate, image blurring occurs unless the photosensitive lithographic printing plate and the photographic original plate are superimposed on each other so that there is no gap. For this purpose, a photosensitive lithographic printing plate and a photolithographic plate are overlapped between the glass plate and the rubber sheet of the vacuum frame, and a vacuum is applied between the glass plate and the rubber sheet to bring the photosensitive lithographic printing plate and the photolithographic plate into close contact. I have.

Then, in order to improve the adhesion between the photosensitive lithographic printing plate 80 and the photographic original plate 82 as shown in FIG. 4, fine droplets are sprayed onto the photosensitive layer of the photosensitive lithographic printing plate 80 by spray coating. An infinite number of substantially trapezoidal mats m are formed so that air can easily escape from between the photosensitive lithographic printing plate 80 and the photographic original plate 82.

[0004] As a matting method for improving the adhesion between the mat and the photosensitive layer, Japanese Patent Publication No. 61-48994 has been proposed.
No. According to this technique, as shown in FIG.
Then, the photosensitive layer is wetted by the wetting device 92, and then the water-soluble fine droplets are electrostatically applied to the surface of the photosensitive layer using an electric field by the electrostatic coating device 94. It is to adhere.

[0005] The electrostatic coating device 94 is, for example, -5.
Since a method of applying a high voltage of 0 to -120 kV for coating is used, it is essential that the entire apparatus is electrically insulated. For this reason, when replenishing a water-soluble liquid or changing a liquid accompanying a lot change, the apparatus is stopped and the high-voltage power supply 96 is turned off in order to prevent an electric shock accident of an operator.

However, treatment of the residual liquid remaining in the pipe 98, cleaning of the pipe, replenishment of the liquid to the tank 100 (application of the foamed liquid causes a product failure, and thus must be replenished gently), In order to check the flow rate and the like, the apparatus must be stopped for a long time, and there is a problem of a decrease in the operation rate.

[0007]

SUMMARY OF THE INVENTION In view of the above fact, the present invention eliminates the need to stop the apparatus and replenish or replace the solution, and to reduce the lot switching time of the photosensitive lithographic printing plate. Make it an issue.

[0008]

According to a first aspect of the present invention, there is provided a mat for spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate to electrostatically adhere and dry the same. A plurality of coating facilities for forming the coating solution, and a liquid sending facility for sending the aqueous solution to the coating facility, wherein one of the coating facility and the liquid sending facility is set to 2
It is characterized in that one or more of the coating equipment or the two or more of the coating equipment or the liquid sending equipment are replaceable.

In the above configuration, by providing at least two or more coating equipment or liquid supply equipment, for example,
If one is present, by reconnecting the piping, it is possible to wash the other liquid sending equipment and replenish the tank while the aqueous solution is being sent to the coating equipment by one of the liquid sending equipment. it can.

In the case where there are two coating facilities, the pipes are reconnected so that while one of the coating facilities adheres the droplet to the object to be coated, the other is moved and the jetting is performed. Around the part and the piping can be cleaned.

The invention according to a second aspect of the present invention provides a method for forming a mat by spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate, electrostatically attaching and drying the same, and forming a mat. In an electrostatic coating apparatus including a facility and a liquid sending facility for sending the aqueous solution to the coating facility, a plurality of units including the coating facility and the liquid sending facility are provided, and each unit is replaceable. It is characterized by.

In the above configuration, since the unit can be replaced in units, piping switching work becomes unnecessary, and cleaning work and flow rate checking work associated with the piping work become unnecessary, so that the lot switching time of the photosensitive lithographic printing plate is greatly reduced. Can be shortened.

According to a third aspect of the present invention, there is provided a method for forming a mat by spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate, electrostatically attaching and drying the same, and forming a mat. Used in an electrostatic coating apparatus including equipment and a liquid sending facility for sending the aqueous solution to the coating facility, a plurality of units including the coating facility and the liquid sending facility are provided, and operation of any one of the units is performed. It is characterized in that the remaining units are washed or replenished.

According to a fourth aspect of the present invention, there is provided a method for forming a mat by spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate, electrostatically attaching and drying the same, and forming a mat. Equipment, a plurality of liquid feeding equipment for sending the coating material to the coating equipment, used in an electrostatic coating apparatus including a photosensitive lithographic printing plate to form an opening in a wall of a coating chamber through which the photosensitive lithographic printing plate passes. ,
It is characterized in that a mat is formed on a photosensitive lithographic printing plate by loading an injection section of any of the coating equipments into the opening.

An aqueous liquid coating material for forming a mat has a gelling and solidifying property when mixed with another photosensitive lithographic printing plate coating material. Therefore, when one coating unit and the liquid sending unit are used together, it is necessary to carefully perform cleaning. In addition, if foamed paint is adhered to the photosensitive lithographic printing plate, the product becomes defective, so it is necessary to replenish the liquid. Takes time.

However, according to the present invention, while the photosensitive lithographic printing plate is matted by loading the jetting part of any coating equipment into the opening of the coating chamber, other coating equipment and liquid sending equipment are used. Therefore, it is not necessary to stop the apparatus during replenishment or replacement of the paint, and the lot switching can be completed in a short time.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic coating apparatus according to a first embodiment will be described with reference to FIGS.

The photosensitive lithographic printing plate 10 made of aluminum is coated with a photosensitive liquid before reaching the electrostatic coating device 20 and sent to the temperature control chamber 12. In the temperature control chamber 12, when the temperature-controlled wind is blown onto the photosensitive lithographic printing plate 10 and reaches the coating booth 14 of the electrostatic coating device 20, the surface temperature of the photosensitive lithographic printing plate 10 falls within a predetermined range. It is adjusted as follows. After that, it is sent to the wetting device 18 by the pass roll 16.

The wetting device 18 sprays and wets the surface or both surfaces of the photosensitive lithographic printing plate 10 with a steam spray tube. The wet photosensitive lithographic printing plate 10 is sent to a painting booth 14.

The grounding coating booth 14 has openings 22A and 22B formed at the top and bottom of the wall surface, and
A and 24B open and close. The rotary atomizing device 26A is connected to the opening 22A, and the opening 2
The rotary atomizing device 26B is laid out so that it can be loaded into 2B.

The rotary atomizers 26A and 26B have rotating bodies 28A and 28B which are bell-shaped and whose large diameter sides are open.
The rotating bodies 28A and 28B are respectively rotated by air motors (not shown), and when the paint fed from the liquid feed pipes 30A and 30B is supplied to the inner peripheral surface from the small diameter side, the paint is rotated by centrifugal force. Spread out in the form of a thin film on the inner peripheral surface of the nozzle and discharge it as an atomized flow from the opening on the large diameter side. In addition, the rotating body 2
The rotation speed of 8A, 28B is 8000 to 20,000 rotations /
And the supply amount of the paint is preferably 5 to 300 cc / min.

The rotary atomizers 26A and 26B include:
Cables 34A, 34B from high voltage power supplies 32A, 32B
To apply a voltage of -40 to -120 kV to charge the atomization flow. As a result, due to the voltage difference between the photosensitive lithographic printing plate 10 and the grounded photosensitive lithographic printing plate 10, the droplets of the paint receive the Coulomb force and fly toward and adhere to the surface of the photosensitive lithographic printing plate 10. A mat is formed on the surface of the layer.

The photosensitive lithographic printing plate 10 on which the mat m has been formed in the coating booth 14 is supplied to the wetting device 3 located downstream.
In step 6, steam is sprayed again and wetted. Then, after wetting, it is sent to the drying chamber 38 and dried in a heated and low-humidity indoor atmosphere, or dried by blowing hot air. The photosensitive lithographic printing plate 10 that has exited the drying chamber 38 is taken up by a winding device via a pass roll 50.

Here, the rotary atomizers 26A and 26B are
Each is mounted on the gantry 42A, 42B. Stand 4
2A and 42B can run on the rails 40A and 40B, and by moving the gantry 42A and 42B respectively, the rotary atomizers 26A and 26B enter the coating booth 14 through the openings 22A and 22B. It can be put in and out. Also, rails 40A, 40B
Is provided with a positioning stopper, and the distance between the photosensitive lithographic printing plate 10 and the rotary atomizers 26A and 26B is set to a predetermined value.

On the other hand, foreign matter filters 44A and 44B are arranged in the liquid sending pipes 30A and 30B, and are sent from the paint tanks 48A and 48B to the rotary atomizers 26A and 26B through the liquid sending pumps 46A and 46B, respectively. Remove paint foreign matter.

As described above, the electrostatic coating device 14 includes the rotary atomizing device 26A, the high-voltage power supply 32A, and the foreign matter filter 4A.
4A, a unit A including a liquid feed pump 46A and a paint tank 48, a rotary atomizer 26B, a high voltage power supply 32
B, a foreign substance filter 44B, a liquid feed pump 46B, and a paint tank 48B. The unit A and the unit B are shielded as a high voltage application range, and are set as a worker's off-limit zone during painting.

As described above, in this embodiment, since the unit can be replaced in units, there is no need to perform a pipe switching operation.
Since the cleaning work and the flow rate confirmation work accompanying this are not required,
The lot switching time of the photosensitive lithographic printing plate 10 can be greatly reduced.

In this embodiment, the photosensitive lithographic printing plate 10
Although the case where only one side is coated has been described, the same configuration can be applied to the case where both sides are coated, so that the lot switching operation time can be reduced. Further, in the present embodiment, the opening is provided for each unit. However, a configuration may be employed in which the gantry is moved up and down or moved horizontally to share one opening.

Next, a second embodiment of the electrostatic coating apparatus will be described.

As shown in FIG. 3, in the second embodiment, there is only one set of the rotary atomizer 52 and the high-voltage power supply 54, and the foreign matter filters 56A and 56B, the liquid feed pumps 58A and 58B,
And paint tanks 60A, 60B, liquid supply pipes 62A, 62B
Are arranged in two sets. Then, by connecting the liquid supply pipe 62A and the liquid supply pipe 62B, the rotary atomizing device 52 is connected.
Can also be used.

As described above, even if a plurality of units of the electrostatic coating apparatus are not provided, by providing a plurality of liquid supply facilities, parts can be replaced, pipes can be washed and liquid can be replenished during operation of the line. Time can be shortened.

Next, the electrostatic coating apparatus according to the present embodiment and a conventional electrostatic coating apparatus will be compared in relation to a line stop time (a stop time of the electrostatic coating apparatus) at the time of lot switching.

As shown in the table of FIG. 4, the work items for lot switching include drainage of residual liquid, cleaning from the coating tank to the rotary atomizer, replenishment of paint, replacement of parts, and confirmation of the flow rate by liquid feed. Etc.

As can be seen from the table, in the conventional electrostatic coating apparatus, 5 minutes were used for discharging the residual liquid, 20 minutes for cleaning from the paint tank to the rotary atomizer, and 1 minute for replacing parts of the rotary atomizer.
It takes 0 minutes, 50 minutes to replenish the paint of the next lot, and 15 minutes to send the liquid and check the flow rate, and the line stop time (device stop time) is 100 minutes.

On the other hand, in the first embodiment, the units are replaced, that is, one of the rotary atomizing devices 26A is connected to the rail 40.
It takes only 10 minutes to retreat along A and close the door 24A and set the other rotary atomizing device 26B in the paint booth 114, so that the line stop time can be greatly reduced. Therefore, the operation rate of the line is improved.

In the second embodiment, it is not necessary to replace the units. However, it takes 15 minutes to clean the pipes from the liquid feed pump to the rotary atomizer, and 15 minutes to reconnect the pipes. It takes 10 minutes to replace parts, 15 minutes to send liquid and check the flow rate, and the line stop time is 55 minutes. As described above, also in the second embodiment, the line stop time can be reduced by 45 minutes as compared with the related art.

Here, the manufacturing process of the PS plate will be described.

The PS plate is a JIS containing 99.5% by weight of aluminum, 0.01% by weight of copper, 0.03% by weight of titanium, 0.3% by weight of iron, and 0.1% by weight of silicon.
-A1050 rolled sheet of aluminum material with a thickness of 0.30 mm was converted to a 400 mesh
Weight percent aqueous suspension and a rotating nylon brush (6,10-
(Nylon) and the surface was grained, and then washed well with water.

This was immersed in a 15% by weight aqueous sodium hydroxide solution (containing 4.5% by weight of aluminum), etched so that the amount of aluminum dissolved was 5 g / m ² , and washed with running water. Furthermore, neutralize with 1% by weight nitric acid,
Next, in a 0.7% by weight nitric acid aqueous solution (containing 0.5% by weight of aluminum), a rectangular wave alternating waveform voltage (current ratio r = 0.9) having an anode voltage of 10.5 volts and a cathode voltage of 9.3 volts was used.
0, a current waveform described in Examples of JP-B-58-5796), and an electrolytic surface roughening treatment was carried out at an anode electricity amount of 160 coulomb / dm ² . After washing with water,
It was immersed in a 0% by weight aqueous sodium hydroxide solution, etched so that the amount of aluminum dissolved was 1 g / m ² , and washed with water. Next, it was immersed in a 50% by weight aqueous solution of 30% by weight sulfuric acid, desmutted, and washed with water.

Further, a porous anodic oxide film forming treatment was performed in a 20% by weight aqueous sulfuric acid solution (containing 0.8% by weight of aluminum) at 35 ° C. using a direct current. That is, electrolysis was performed at a current density of 13 A / dm ² , and the anodic oxide film weight was adjusted to 2.7 g / m ² by adjusting the electrolysis time. To prepare a negative photosensitive lithographic printing plate using a diazo resin and a binder, the support was washed with water, immersed in a 3% by weight aqueous solution of sodium silicate at 70 ° C. for 30 seconds, washed with water and dried.

[0041] The thus-obtained aluminum support, Macbeth RD920 reflection density was measured with a reflection densitometer 0.30, the center line average roughness R _a as defined in JIS B00601 is 0.58μm met Was.

Next, methyl methacrylate /
A 1.0% by weight aqueous solution of ethyl acrylate / 2-acrylamide-2-methylpropane sodium sulfonate copolymer (average molecular weight: about 60,000) (molar ratio: 50/30/20) was dried by a roll coater to obtain an applied amount of 1.0% by weight. 0.05g
/ M ² .

Further, the following photosensitive solution-1 was applied using a bar coater and dried at 110 ° C. for 45 seconds. The dry coating amount was 2.0 g / m ² . Photosensitive solution-1 Diazo resin-1 0.50 g Binder-1 5.00 g Stylite HS-2 (manufactured by Daido Kogyo Co., Ltd.) 0.10 g Victoria Pure Blue BOH 0.15 g Tricresyl phosphate 0.50 g Dipicolinic acid 0 .20 g FC-430 (Surfactant manufactured by 3M) 0.05 g Solvent 1-methoxy-2-propanol 25.00 g Methyl lactate 12.00 g Methanol 30.00 g Methyl ethyl ketone 30.00 g Water 3.00 g

The above diazo resin-1 was obtained as follows. First, 29.4 g of 4-diazodiphenylamine sulfate (99.5% purity) was added at 25 ° C to 9
It was slowly added to 70 ml of 6% sulfuric acid and stirred for 20 minutes. To this, paraformaldehyde (purity 92%) 3.
26 g was added gradually over about 10 minutes, and the mixture was added to 30
The mixture was stirred at 4 ° C. for 4 hours to allow the condensation reaction to proceed. In addition,
The condensation molar ratio of the diazo compound and formaldehyde is 1: 1. The reaction product was poured into 2 liters of ice water with stirring, and treated with a cold concentrated aqueous solution in which 130 g of sodium chloride was dissolved. The precipitate was collected by suction filtration and the partially dried solid was dissolved in 1 liter of water, filtered, cooled with ice and treated with an aqueous solution of 23 g of potassium hexafluorophosphate. Finally, the precipitate is recovered by filtration and air-dried to give the diazo resin-
1 g was obtained.

Binder-1 was 2-hydroxyethyl methacrylate / acrylonitrile / methyl methacrylate / methacrylic acid copolymer (weight ratio 50/20/26 /
4, average molecular weight 75,000, acid content 0.4 meq /
g) is a water-insoluble, alkaline water-soluble film-forming polymer.

Stylite HS-2 (manufactured by Daido Industry Co., Ltd.)
Is a polymer compound having a higher oil sensitivity than the binder,
It was a copolymer of styrene / mono-4-methyl-2-pentyl maleate = 50/50 (molar ratio), and the average molecular weight was about 100,000.

[0047]

According to the present invention having the above-described structure, there is no need to stop the apparatus and replenish or replace the solution, and it is possible to shorten the lot switching time.

[Brief description of the drawings]

FIG. 1 is a side view showing an electrostatic coating device according to a first embodiment.

FIG. 2 is a perspective view showing the electrostatic coating device according to the first embodiment.

FIG. 3 is a side view showing an electrostatic coating device according to a second embodiment.

FIG. 4 is a table showing the difference in equipment replacement time between a conventional electrostatic coating device and the electrostatic coating device of the present invention.

FIG. 5 is a conceptual diagram showing the relationship between a photosensitive lithographic printing plate and a photolithographic plate.

FIG. 6 is a side view showing a conventional electrostatic coating device.

[Explanation of symbols]

 26A Rotary atomizer (coating equipment) 26B Rotary atomizer (coating equipment) 30A Liquid feed pipe (liquid feed equipment) 30B Liquid feed pipe (liquid feed equipment) 46A Liquid feed pump (liquid feed equipment) 46B Liquid feed pump ( Liquid supply equipment) 48A Paint tank 48B Paint tank A unit B unit

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/00 503 G03F 7/00 503 7/11 501 7/11 501 7/16 501 7/16 501F Terms (reference) 2H025 AA02 AB03 AD01 AD03 DA06 EA04 2H096 AA06 CA20 LA30 2H114 AA04 AA23 AA27 BA01 EA01 GA01 GA34 4D075 AA09 AA34 AA39 AA52 AA71 CA47 DA04 DB31 DC27 EA06 4F034 AA04 CA02 DA

Claims (4)

[Claims] 1. A plurality of coating equipment for spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate to electrostatically adhere and dry to form a mat, and to the coating equipment. A liquid sending device for sending the aqueous solution, wherein two or more of the coating device and the liquid sending device are provided, and the coating device or the liquid sending device is provided with two or more. An electrostatic coating apparatus characterized in that equipment can be replaced. 2. A plurality of coating equipment for spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate and electrostatically adhering and drying the same to form a mat; A liquid sending device for sending the aqueous solution, wherein a plurality of units each including the coating device and the liquid sending device are provided, and each unit is replaceable. apparatus. 3. A plurality of coating equipment for spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate to electrostatically adhere and dry to form a mat, and to the coating equipment. A plurality of units comprising the coating equipment and the liquid feeding equipment, and cleaning the remaining units while any one of the units is operating. Alternatively, an electrostatic coating method characterized by performing liquid replenishment. 4. A plurality of coating equipment for spraying an aqueous liquid paint as fine droplets onto a photosensitive layer of a photosensitive lithographic printing plate to electrostatically adhere and dry to form a mat, and to the coating equipment. Used in an electrostatic coating apparatus having a plurality of liquid feeding facilities for feeding the paint, wherein an opening is formed in a wall of a coating chamber through which the photosensitive lithographic printing plate passes, and any one of the openings is formed in the opening. Forming a mat on the photosensitive lithographic printing plate by loading the jetting unit of the coating equipment.