JP4213352B2 - Method for producing photosensitive lithographic printing plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a photosensitive lithographic printing plate in which a mat is formed on a photosensitive layer of the photosensitive lithographic printing plate.
[0002]
[Prior art]
In an image exposure process for forming an image on a photosensitive lithographic printing plate, image blur occurs unless the photosensitive lithographic printing plate and the photographic original plate are closely overlapped so that there is no gap. For this reason, in general, a photosensitive lithographic printing plate and a photographic original plate are overlapped between a glass plate and a rubber sheet of a vacuum frame, and the photosensitive lithographic printing plate and photographic plate are evacuated by applying a vacuum between the glass plate and the rubber sheet. The original is in close contact.
[0003]
Then, in order to improve the adhesion between the photosensitive lithographic printing plate 80 and the photographic original plate 82 as shown in FIG. A trapezoidal mat m is formed so that air can easily escape from between the photosensitive lithographic printing plate 80 and the photographic original plate 82.
[0004]
Japanese Patent Publication No. 61-48994 can be cited as a matting method with improved adhesion between the mat and the photosensitive layer. In this technique, the surface temperature of the photosensitive lithographic printing plate being transported is raised to 65 ° C. in a temperature control chamber, the photosensitive layer is moistened with a wetting device, and then water-soluble using an electric field by electrostatic coating. The fine droplets are electrostatically attached to the surface of the photosensitive layer.
[0005]
In this matting method, the height and shape of the mat are controlled according to the conditions of the wetting process and the time for shifting from the wetting process to the drying process.
[0006]
By the way, in order to improve the vacuum adhesion of the photosensitive lithographic printing plate, it is conceivable to raise the mat. In addition, when the mat is raised, the diameter of the mat increases and the volume per mat increases. For example, when the mat has a diameter of 20 μm to 50 μm and a height of 2 μm to 4 μm, and the mat is considered to have a similar shape, the mat diameter needs to be increased to 40 μm to 100 μm in order to make the height 4 μm to 8 μm. There is.
[0007]
However, in the conventional matting method, as shown in FIG. 5, when a mat with a large diameter is made, the surface is dried first to form a thin film, and a hollow is formed in the center as the inside solidifies. As a result, a mat having a required height as shown in FIG. 4 could not be obtained.
[0008]
[Problems to be solved by the invention]
In view of the above facts, an object of the present invention is to produce a mat that does not have a dent in the center even when the mat has a large diameter.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 is a method for producing a photosensitive lithographic printing plate, wherein an aqueous liquid is jetted as fine droplets on the photosensitive layer of the photosensitive lithographic printing plate to electrostatically adhere and dry to form a mat. The surface temperature of the photosensitive lithographic printing plate before droplets are deposited on the photosensitive layer is measured, and the temperature of the photosensitive lithographic printing plate is set to 27 ° C. to 30 ° C. based on the measured temperature. It is characterized by that.
[0010]
In the above configuration, when the aqueous liquid is ejected as fine droplets onto the photosensitive layer of the photosensitive lithographic printing plate, the diameter of the mat is adjusted by electrostatically adhering and drying the droplet diameter during ejection. The size of can be changed.
[0011]
Here, by setting the temperature of the photosensitive lithographic printing plate before the droplets to adhere to 27 ° C. to 30 ° C. , a mat with a mat height corresponding to the mat diameter and having a good shape without a dent in the center portion can be obtained. The invention according to claim 2 is characterized in that the temperature control of the photosensitive lithographic printing plate is performed in a temperature control chamber through which the photosensitive lithographic printing plate passes before droplets are attached. Yes.
[0012]
In the above configuration, since the temperature control of the photosensitive lithographic printing plate is performed in the temperature control chamber through which the photosensitive lithographic printing plate passes immediately before the droplets are attached, the photosensitive lithographic printing plate when the droplets are attached The temperature fluctuation is small.
[0013]
The invention described in claim 3 is characterized in that the temperature control of the photosensitive lithographic printing plate is performed by controlling the indoor temperature of the temperature control chamber. In this configuration, the temperature of the photosensitive lithographic printing plate can be brought to a predetermined value by heating and cooling the room.
[0014]
The invention described in claim 4 is characterized in that the temperature control of the photosensitive lithographic printing plate is performed by exchanging heat with a pass roll disposed in the temperature control chamber. In this configuration, by adjusting the temperature of the pass roll that transports the photosensitive lithographic printing plate, the pass roll and the photosensitive lithographic printing plate are directly heat-exchanged, and the temperature of the photosensitive lithographic printing plate becomes a predetermined value.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, the manufacturing method of the photosensitive lithographic printing plate which concerns on this form is demonstrated.
[0016]
The photosensitive lithographic printing plate 10 coated with the photosensitive solution is introduced into the temperature control chamber 12. The surface temperature of the photosensitive lithographic printing plate 10 is in the range of 20 ° C. to 40 ° C. by introducing the temperature of the temperature control chamber 12 into the duct 32 formed with cold air or a blowout port for blowing out hot air. Thus, it is preferably adjusted to be in the range of 25 ° C to 35 ° C.
[0017]
Here, the surface temperature of the photosensitive lithographic printing plate 10 is measured by a non-contact temperature sensor 26. The temperature sensor 26 converges the amount of infrared radiation emitted from the surface of the photosensitive lithographic printing plate 10, converts it into an electric amount, and outputs a detection signal to the control unit 28.
[0018]
A hot air / cold air heater 30 is connected to the control unit 28, and cold air or hot air is introduced into the temperature control chamber 12 through the duct 32 based on the temperature of the photosensitive lithographic printing plate 10 detected by the temperature sensor 26. Is blown.
[0019]
In addition, instead of the method of indirectly controlling the temperature of the photosensitive lithographic printing plate 10 with hot air or cold air, as shown in FIG. 2, a heater or the like is built in the pass rolls 16 and 34 as a heat exchanger. The photosensitive lithographic printing plate 10 may be directly heated and cooled.
[0020]
In this way, the photosensitive lithographic printing plate 10 whose temperature is controlled is sent to the wetting device 18 by the pass roll 16. The wetting device 18 sprays steam onto the surface or both surfaces of the photosensitive lithographic printing plate 10 with a steam spray tube to wet it. The wet photosensitive lithographic printing plate 10 is sent to the electrostatic coating apparatus 14.
[0021]
The electrostatic coating apparatus 14 includes a rotating body 36 having a bell shape and an opening on the large diameter side. The rotator 36 is rotated by an air motor (not shown), and when the fed aqueous liquid is supplied from the small diameter side to the inner peripheral surface, the aqueous liquid L is thinned into the inner peripheral surface of the rotator 36 by centrifugal force. It is spread and discharged as an atomized flow from the opening on the large diameter side.
[0022]
Further, a voltage of −40 to −120 kV is applied to the electrostatic coating device 14 to charge the atomized flow. As a result, due to the voltage difference from the photosensitive lithographic printing plate 10 grounded by the pass roll 16, the droplets receive Coulomb force and fly and adhere to the surface of the photosensitive lithographic printing plate 10, so that the photosensitive layer A mat m is formed on the surface.
[0023]
In addition, the photosensitive lithographic printing plate 10 on which the mat m is formed is wetted by spraying steam again with the wetting device 20 disposed on the downstream side. And after wetting, it is sent to the drying chamber 22 and dried in a heated and low-humidity indoor atmosphere, or it is dried by blowing warm air. The photosensitive lithographic printing plate 10 exiting the drying chamber 22 is taken up by a take-up device via a pass roll 24.
[0024]
Next, an example of a method for producing a photosensitive lithographic printing plate according to this embodiment will be described.
[0025]
As shown in the table of FIG. 3, the temperature of the temperature control chamber 12 was adjusted to 7 ° C. to 35 ° C. so that the temperature of the photosensitive lithographic printing plate was 15 ° C. to 45 ° C. The following photosensitive lithographic printing plate was conveyed to the temperature control chamber 12.
[0026]
That is, the aluminum web was grained with a nylon brush and 400 mesh pumiston-water suspension. The grained web was washed with water and immersed in a 70 ° C. aqueous sodium phosphate (5%) solution for 2 minutes for chemical etching.
[0027]
After etching, the substrate was washed with water to remove dirt (smut) remaining on the surface and then dried.
[0028]
Next, 1 part by weight of naphthoquinone-1,2-diazide-5-sulfonic acid ester of polyhydroxyphenyl obtained by condensation polymerization of acetone and pyrogallol described in Japanese Patent Publication No. 43-28403 and a novolac type phenol formaldehyde resin 2 parts by weight was dissolved in 20 parts by weight of methyl ethyl ketone to prepare a photosensitive solution, and this photosensitive solution was applied to a web with a coating machine and dried in a drying room.
[0029]
The photosensitive lithographic printing plate produced in this way was sent to the temperature control chamber 12, wetted by spraying steam with the wetting device 18, and conveyed to the electrostatic coating device 14.
[0030]
The matte liquid used in the electrostatic coating apparatus 14 was prepared by adjusting a methyl methacrylate / ethyl acrylate / sodium acrylate (weight ratio 68:20:12 [prepared weight]) copolymer polymer aqueous solution to a solid content concentration of 18%. The coating amount per 1 m width was 140 cc / min.
[0031]
The aqueous liquid having such a concentration is atomized by the centrifugal force of the cup-shaped spray head having a bell rotational speed of 17000 rpm and the electrostatic action of the cup-shaped spray head applied to the bell high voltage: -80 kv, Due to the action of a high electric field formed between the cup-shaped spray head and the photosensitive lithographic printing plate, the average diameter of atomized and charged fine droplets is made to fly to the surface of the photosensitive layer with an average diameter of 15 μm. Attached.
[0032]
The photosensitive lithographic printing plate 10 on which the mat was formed was wetted again by spraying steam with the wetting device 20 arranged on the downstream side.
[0033]
Then, after wetting, the photosensitive lithographic printing plate 10 is sent to the drying chamber 22 and dried in a heated and low-humidity indoor atmosphere, or hot air is blown and dried.
[0034]
The table in FIG. 3 shows how the mat shape changed due to the difference in temperature of the photosensitive lithographic printing plate.
[0035]
When the mat height is evaluated as ◎, ◯, △, × with the mat height (average height of one test sheet) of 5 μm or more as ◯ and no dent as the reference, the temperature of the photosensitive lithographic printing plate 10 However, when the temperature is 15 ° C., the temperature is low and no dent is generated (（), but the mat height is as low as 3 μm (×) as shown in FIG. X.
[0036]
On the other hand, when the temperature of the photosensitive lithographic printing plate 10 is 45 ° C., the mat height is 6 μm (◯), but there is no problem, but a large dent as shown in FIG. Is x.
[0037]
Therefore, in this embodiment, when the temperature of the photosensitive lithographic printing plate 10 is 27 ° C. and 30 ° C., as shown in FIG. 4, the mat height is as high as 8 μm (◎) and no dent is formed ( ◎), and ◎ for shape evaluation.
[0038]
From the above results, it can be seen that if up to Δ is OK, a mat having a good shape can be obtained if the temperature of the photosensitive lithographic printing plate 10 is in the range of 20 ° C. to 40 ° C.
[0039]
On the other hand, in this embodiment, in order to control the temperature of the temperature control chamber 12, the temperature of the wind introduced into the temperature control chamber 12 is adjusted. However, the supply air volume, the exhaust air volume, or the circulation air volume is adjusted. Thus, the temperature of the temperature control chamber 12 may be controlled.
[0040]
Moreover, the structure which arrange | positions the heating cooler which a heat medium and a refrigerant pass in the temperature control chamber 12, and heats and cools a drying chamber may be sufficient. Further, the temperature control chamber 12 may be directly heated / cooled using electric power from a heater or a cooler.
[0041]
Here, the manufacturing process of the PS plate will be described.
[0042]
The PS plate is a JIS-A1050 aluminum material containing 99.5% by weight aluminum, 0.01% by weight copper, 0.03% by weight titanium, 0.3% by weight iron and 0.1% by weight silicon. After the surface of the 0.30 mm thick rolled plate was grained using a 20 mesh% aqueous suspension of 400 mesh Pamiston (manufactured by Kyoritsu Ceramics) and a rotating nylon brush (6,10-nylon), Washed well with water.
[0043]
This was immersed in a 15% by weight sodium hydroxide aqueous solution (containing 4.5% by weight of aluminum) and etched so that the amount of aluminum dissolved was 5 g / m ² , and then washed with running water. Further, neutralized with 1% by weight nitric acid, and then in a 0.7% by weight nitric acid aqueous solution (containing 0.5% by weight of aluminum), a rectangular wave with an anode voltage of 10.5 volts and a cathode voltage of 9.3 volts Using an alternating waveform voltage (current ratio r = 0.90, current waveform described in the example of Japanese Examined Patent Publication No. 58-5796), electrolytic surface roughening treatment was performed at an anode time electricity of 160 coulomb / dm ^2. It was. After washing with water, it was immersed in a 10 wt% sodium hydroxide aqueous solution at 35 ° C., etched so that the amount of dissolved aluminum was 1 g / m ² , and then washed with water. Next, it was immersed in an aqueous sulfuric acid solution at 50 ° C. and 30% by weight, desmutted, and washed with water.
[0044]
Further, a porous anodic oxide film forming treatment was performed using a direct current in a 20 wt% sulfuric acid aqueous solution (containing 0.8 wt% aluminum) at 35 ° C. That is, electrolysis was performed at a current density of 13 A / dm ² , and the weight of the anodic oxide film was adjusted to 2.7 g / m ² by adjusting the electrolysis time. In order to prepare a negative photosensitive lithographic printing plate using a diazo resin and a binder, this support was washed with water, immersed in a 3% by weight aqueous solution of sodium silicate at 70 ° C. for 30 seconds, and washed and dried.
[0045]
The thus-obtained aluminum support, Macbeth RD920 reflection density measured by a reflection densitometer 0.30, the center line average roughness R _a as defined in JIS B00601 was 0.58 .mu.m.
[0046]
Next, a 1.0% by weight aqueous solution of methyl methacrylate / ethyl acrylate / 2-acrylamido-2-methylpropanesulfonic acid sodium copolymer (average molecular weight of about 60,000) (molar ratio 50/30/20) was applied to the support. It applied so that the application quantity after drying might be 0.05 g / m < ² > with a roll coater.
[0047]
Furthermore, 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 .
[0048]
Photosensitive solution-1
Diazo resin-1 0.50g
Binder-1 5.00g
Stilite HS-2 (Daido Kogyo Co., Ltd.) 0.10g
Victoria Pure Blue BOH 0.15g
Tricresyl phosphate 0.50 g
Dipicolinic acid 0.20g
FC-430 (3M surfactant) 0.05 g
Solvent 1-methoxy-2-propanol 25.00g
Methyl lactate 12.00g
Methanol 30.00g
Methyl ethyl ketone 30.00g
3.00 g of water
[0049]
The above diazo resin-1 was obtained as follows. First, 29.4 g of 4-diazodiphenylamine sulfate (purity 99.5%) was gradually added to 70 ml of 96% sulfuric acid at 25 ° C. and stirred for 20 minutes. To this, 3.26 g of paraformaldehyde (purity 92%) was gradually added over about 10 minutes, and the mixture was stirred at 30 ° C. for 4 hours to allow the condensation reaction to proceed. The condensation molar ratio between 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 in which 23 g of potassium hexafluorophosphate was dissolved. Finally, the precipitate was collected by filtration and air-dried to obtain 1 g of diazo resin.
[0050]
Binder-1 is a 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). It is an alkali water-soluble film-forming polymer.
[0051]
Stylite HS-2 (manufactured by Daido Kogyo Co., Ltd.) is a polymer compound having a higher oil sensitivity than the binder, and styrene / maleic acid mono-4-methyl-2-pentyl ester = 50/50 (molar ratio). The average molecular weight was about 100,000.
[0052]
【The invention's effect】
Since the present invention is configured as described above, even if the mat has a large diameter, no depression is generated in the central portion.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a method for producing a photosensitive lithographic printing plate of the present embodiment.
FIG. 2 is a conceptual diagram showing a method for producing a photosensitive lithographic printing plate according to a modification.
FIG. 3 is a table showing the relationship between the temperature of a photosensitive lithographic printing plate and the shape of a mat.
FIG. 4 is an explanatory view showing a mat without a depression.
FIG. 5 is an explanatory view showing a recess of a mat.
FIG. 6 is an explanatory view showing a flat mat.
FIG. 7 is a conceptual diagram showing the relationship between a photosensitive lithographic printing plate and a photographic original plate.
[Explanation of symbols]
m Mat 12 Temperature control chamber 26 Temperature sensor 30 Hot air / cold air heater 32 Duct 34 Path roll

Claims (4)

In the method for producing a photosensitive lithographic printing plate, an aqueous liquid is sprayed as fine droplets on the photosensitive layer of the photosensitive lithographic printing plate to electrostatically adhere and dry to form a mat.
The surface temperature of the photosensitive lithographic printing plate before the droplets are attached to the photosensitive layer is measured, and the temperature of the photosensitive lithographic printing plate is set to 27 ° C. to 30 ° C. based on the measured temperature. A method for producing a photosensitive lithographic printing plate.   2. The photosensitive lithographic printing plate according to claim 1, wherein the temperature control of the photosensitive lithographic printing plate is performed in a temperature control chamber through which the photosensitive lithographic printing plate passes before droplets are attached. 3. Production method.   The method for producing a photosensitive lithographic printing plate according to claim 2, wherein the temperature control of the photosensitive lithographic printing plate is performed by controlling an indoor temperature of the temperature control chamber.   The method of producing a photosensitive lithographic printing plate according to claim 2, wherein the temperature control of the photosensitive lithographic printing plate is performed by directly exchanging heat with a pass roll disposed in the temperature control chamber.

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