WO2008071069A1

WO2008071069A1 - Manufacturing method of printing plate

Info

Publication number: WO2008071069A1
Application number: PCT/CN2007/003385
Authority: WO
Inventors: Wei Li; Peter Smith
Original assignee: Brother Gao Deng Group; Zhang, Zhi
Priority date: 2006-12-13
Filing date: 2007-11-30
Publication date: 2008-06-19
Also published as: CN1987651A

Abstract

A manufacturing method of a printing plate comprises electrolysis aperture diameters, oxidation, coating with a thermal sensing photoresist, and drying process, wherein the radiated thermal sensing photoresist is decomposed with a base. The substrate has a surface roughness of 2.5μm during the decomposing process.

Description

Method for manufacturing printing plate

Technical field

The present invention relates generally to the field of manufacture of plates, and more particularly to a method of making a printing plate. Background technique

Computer To Plate (CTP) refers to the process of outputting digital pages directly onto a printing plate through a computer. This technology not only eliminates the traditional prepress process such as laser photo-distribution film and manual spelling and printing, saves the equipment and materials needed for the intermediate link, and avoids the disadvantages of loss, deformation and telescopicity of the dot, and reduces the number of defects. The loss of color and level, and shortening the ink tone calibration and registration time and ink balance time during the printing process can greatly improve product quality and work efficiency. Pre-coated lithographic printing is a process in which a thin layer of heat-sensitive or photosensitive coating is applied to a pretreated aluminum plate. In use, the image is formed in the coating, and the coating of the non-image portion is decomposed by the solvent (or more generally the water-based solution), revealing that the original treated aluminum plate surface is not in the form of a graphic, and The coating of the image portion is not broken down to form a graphic portion, and the solution is a so-called developing solution. In the printing process, the surface of the aluminum plate of the non-image portion is hydrophilic, and the coating of the image portion has good ink affinity, so that the ink on the lipophilic image portion can be transferred onto the paper. In general, the coating on the pretreated aluminum plate is sensitive to UV light, while the image portion can be formed again after exposure to normal positive or negative film. A typical photosensitive positive-type photosensitive paste is composed of a mixture comprising naphthoquinone and a phenolic resin. It has long been believed that naphthoquinones can effectively inhibit the dissolution of phenolic resins in alkaline solvents. Recent research shows that inhibition of dissolution is through hydrogen

Confirmation The combination is achieved (Rei ser et Al. Angew Chem Int Edn. Engl 33 2428 (1996)).

U.S. Patent No. 6,063,544 describes a positive-type photosensitive adhesive that is sensitive to infrared wavelengths. It actually replaces the naphthoquinone in a common positive photosensitive paste with an infrared radiation-absorbing material. mixture. In fact, this simple process is not as effective as the use of a photopolymer containing naphthoquinone, and the plate produced according to U.S. Patent No. 6,063,544 has a short shelf life and is difficult to develop, making it difficult to flush the non-image portion. If you want to clean the non-image part, the alkaline developer will easily destroy the graphic part. In addition, the photoresist requires a higher exposure of the laser energy.

The main problem now is that the quality of the plates produced by the manufacturers has not been stable so far, and the sensitivity will change over time. Therefore, as a result, this version has to be kept at a low temperature, and it is required to always use an air conditioner to control the temperature, even if it is required to be refrigerated during transportation; however, the environmental environment is above 25 °C. Thus, its shortcoming is that it is expensive and inconvenient to store and transport.

If it is not stored and transported in a low temperature environment, it will cause a higher amount of laser energy in the plate making process, and eventually the so-called "printing dirty" phenomenon occurs, that is, the non-image portion is inked during the printing process.

Subsequently, in order to solve this problem, people have invented other methods.

U.S. Patent No. 6,074,802 describes an infrared-sensitive photosensitive adhesive manufacturing technique which, in addition to a phenolic resin and an infrared sensitizer, also contains a mixture which can be crosslinked with phenolic resin when exposed to heat. Such as an amino mixture. Its purpose is to enhance the image quality after infrared exposure, and to obtain a more stable graphic part. However, it still There is no good solution to the problem of quality stability in long-term storage.

The European Patent No. EP1024958 describes a heat curing technique in which a sheet that has been cut into sheets is stored at a temperature exceeding 50 ° C for a few days to make the layer more stable. However, this method is too cumbersome and increases production costs and scrap rates. Moreover, it does not have a good solution to the low temperature storage problem of the product.

The European patent No. EP1157854 describes part of the problem of the viscous problem in the infrared sensitized plate, that is, the surface of the aluminum plate is roughened to produce a high surface area to improve the water retention during the printing process. In the photographic coating of the printing plate, the rough surface can produce photosensitive layers of different thicknesses at the valleys and valleys of the rough surface, commonly referred to as "sands". These different coating thicknesses will require different exposures. Patent EP 1 157 854 states that for infrared imaging, the laser energy is quickly attenuated on the surface of the aluminum plate, thus greatly affecting the peaks and roughness of the infrared imaged plate. Therefore, the patent EP 1 157 854 proposes the use of alkali etching so that the 10% thickness of the thinnest portion of the photosensitive paste of the convex portion of the surface of the aluminum plate reaches 0.2 μm to 2 μm. However, after the strong alkali corrosion treatment, the surface of the sand surface is "rounded," which causes the bonding property of the aluminum plate base and the photoresist to decrease, resulting in a decrease in the printing durability, and the patent EP1 157854 does not mention such a phenomenon. Processing can improve and improve the storage of the media.

European Patent No. EP1300257 describes a new aluminum-based treatment technology that uses a special aluminum alloy aluminum plate to perform two stages of electrolysis to form a specific sand contour and then reoxidize. Treatment (two-stage oxidation, optional) to improve the anti-dirty capability of the aluminum plate. In this patent, a standard surface roughness tester such as a Taylor Hobson tester is used, and the average surface roughness measured is 0.445 um, also It is the average value of the valley peak to the valley bottom in a certain unit of measurement on the surface. However, the production process of this patent is cumbersome, and the use of this technology cannot solve the problem of stability in solving product quality. The anodic oxide film weighs more than 3.0 g per square meter. The anodic oxide film weighs more than 0.3 g. However, as with the technique provided in the patent No. EP1300257, when the Ra value is less than 0.4 um, it is generally not advantageous for printing because it is difficult to obtain a good ink-and-wash balance at the time of printing. Moreover, the aluminum version can achieve a Ra value of 0.3 um during the rolling process, so it is difficult to judge whether the 0.3 um Ra is the effect of electrolysis or the role of the aluminum version. Therefore, there is a need for a new method of producing positive-type thermal printing plates to overcome the above problems. Summary of the invention

It is an object of the present invention to provide a method of producing a printing plate. In order to solve the above technical problems, the technical solution adopted by the present invention includes a method for manufacturing a printing plate material, including electrolytic sandblasting, oxidation, coating with a thermal sensitive photoresist, and a subsequent drying process, wherein The photosensitive adhesive is decomposed by alkali after being irradiated, and a surface roughness of the base having a maximum valley depth of 2.5 μm is generated in the electrolysis process, wherein the maximum valley depth is measured by a surface roughness meter, which is called an Rv value. The specific technical solution adopted by the present invention is as follows: A method for manufacturing a printing plate material, comprising the following technical steps: (1) using a degreasing liquid to remove grease on the surface of the plate material; (2) Electrolytic treatment and decontamination treatment of the plate material;

(3) oxidizing the plate material;

(4) enhancing the adhesion and developing performance of the plate;

(5) coating the plate with a thermographic photosensitive adhesive;

(6) drying the plate;

(7) Cut the plate.

In the above technical solution, in the step (1), the oil removal solution of the plate material is 30-35 g/liter sodium hydroxide aqueous solution, the treatment temperature is 48-52 ° C, and the treatment time is 28-32 seconds.

In the above technical solution, in (2) step: the plate material is electrolyzed by alternating current; the electrolyte used is composed of nitric acid or hydrochloric acid plus a corrosion inhibitor; the corrosion inhibitor is boric acid, acetic acid, phosphoric acid, sulfuric acid or their Salt substances.

Preferably, the electrolytic solution used in the electrolytic process in the step (2) is a mixture of hydrochloric acid and boric acid, and the ratio of hydrochloric acid to boric acid is 1:1.1 to 1.3 by weight.

In the above technical solution, the detergent used in the decontamination treatment in the step (2) is a 7.0 to 8. Q g/liter sodium hydroxide aqueous solution, the treatment temperature is 24 to 25 ° C, and the treatment time is 70 ~. 75 seconds.

In the above technical solution, the oxidizing solution used for the oxidation treatment of the plate material in the step (3) is a mixed solution of phosphoric acid and sulfuric acid; the composition of the mixed solution of phosphoric acid and sulfuric acid is three parts of sulfuric acid and two parts of phosphoric acid by weight; The temperature is 22 - 24 ° C and the processing time is 75 ~ 80 seconds.

In the above technical solution, the thermal sensitive adhesive in the step (5) is composed of ethyl glycol and other solid materials; in terms of weight percentage, ethyl glycol is 80-85%, and other solid materials are 15-20. %. In the above technical solution, the other solid substances include a heat sensitive agent and a phenolic resin, and the proportion of the heat sensitive agent is 1.5% to 3.0% by weight, and the proportion of other solid materials is 97% to 98.5%. .

Preferably, the infrared heat sensitive agent is:

2-[2 {2- chloro-3—(1, 3-dihydro-l, 1, 3-tr imethyl-2H-benz (e) indol-2-yl idene) ethyl idene-l-cyclohexen-l-yl } ethenyl] -1, 1, 3 -t rime thy 1-lH-benz (e) indol ium, salt with 4- methy lbenzene sulphonic acid;

In the above technical solution, the drying temperature of the plate material in the step (6) is not less than 100 °C. Compared with the prior art, the beneficial technical effects of the present invention are:

The method for producing a positive-type thermal printing plate of the present invention is suitable for producing a plate material, and the plate material produced can be stably stored for several months at a maximum temperature of at least 40 ° C, and the plate making time thereof is also compared. Short, excellent printing quality, and the process of this method has no special requirements for production equipment, using traditional reel production equipment, using standard aluminum The coil can be used as a raw material to produce a stable and reliable product, and the produced plate has excellent printing performance and stable ink-ink balance; the method for producing the positive-type thermal printing plate of the present invention is directly washed after the plate is oxidized. The adhesion of the coating is stronger, the printing durability is higher, and the storage stability of the plate is enhanced. Features and advantages of the present invention will be described in detail by the embodiments in conjunction with the accompanying drawings.

DRAWINGS

1 is a flow chart of a method of manufacturing a printing plate according to the present invention.

Figure 2 shows the molecular structure of the infrared heat-sensitive agent. Detailed ways

The invention is further described below in conjunction with specific embodiments.

Example 1

Referring to FIG. 1, the method for producing a positive-type thermal printing plate of the present invention comprises the following steps: Step 100: The plate deoiling process uses a degreasing liquid to remove grease from the surface of the plate, and the degreasing liquid includes sodium hydroxide. Step 200: The process plate for electrolysis of the plate material is made of alternating current when performing electrolysis sand. The electrolyte is usually used (but not limited to) nitric acid or hydrochloric acid. In order to control the contour of the sand, a corrosion inhibitor is usually added. For example, boric acid, acetic acid, phosphoric acid, sulfuric acid or their salts are used to ensure that no deep pits (valleys) are formed during the electrolysis of the plate. In the electrolysis process, the grain peaks and contours of the surface of the plate material are stored for the infrared photosensitive printing plate, especially the positive-type infrared photosensitive printing plate (referred to as: thermal CTP plate). It is not important, and the peak value of the valley peak does not affect the storage quality of the thermal CTP version. However, the bottom value of the sand must be less than 2. 5um. The most important thing in practice is not to detect the Ra value, but to detect it. Rv value, that is, the maximum valley value, Ra value between 0. 3um to 0. 5um has no obvious influence on the printing quality and stability of the thermal CTP plate, because the Ra value is also strictly controlled for the bottom value, that is, Rv Relatively speaking, the Ra value is lower than the conventional version, but the Ra value is not important, because even without electrolysis, the Ra value can reach a considerable value, and the Rv value is directly related to the sand project; The sufficiency of the Rv value can be controlled below 2. 5um, the Rv value can be controlled below 2. 5um, the Rv value can be controlled below 2. 5um .

Step 300: Oxidizing the plate

Generally, the surface of the plate is hardened with sulfuric acid or phosphoric acid to prevent scratching or other physical damage, which can enhance the wear resistance of the plate and improve the printing durability of the plate. The best way is to use a mixture of phosphoric acid and sulfuric acid. The three parts of sulfuric acid have the best effect on the two parts of phosphoric acid. This kind of complex acid can be improved without hurting mechanical endurance and oxide film. The developing performance and storage stability of the plate. The addition of phosphoric acid reduces the weight of the oxide film. Moreover, when the weight of the oxide film is 2-3 g per square meter, the printing effect is the best, the printing durability is the highest, and the stability of the product quality is not affected.

Step 400: Enhance the adhesion and development performance of the plate

In the lithography industry, manufacturers generally take further steps (sealing process) to enhance the adhesion and development performance of the plate. These treatments usually involve the use of phosphorus/fluorine mixtures, acrylic polymers, ethylene phosphate polymers, vinyl alcohol polymers, sodium silicates or Many other substances.

Any of the above methods can be used. The best method is to not seal the pores after oxidation and wash them directly. This results in a stronger adhesion of the coating and a higher print durability, while also enhancing the storage stability of the plate.

Step 500: coating the plate with a thermographic photosensitive adhesive, which mainly contains a phenolic resin and an infrared photosensitive material capable of absorbing 810 nm to 830 nm, which is compared with a conventional commercial laser imager (thermal CTP platesetter) on the market. The output range of the light energy that is rapidly heated by laser irradiation is uniform. In addition, some additives such as a wetting agent, other polymers, and a polymer such as a siloxane polymer which can enhance the development resistance can also be added. It is best not to use any additives, but to use only one dye dye, which enhances the visibility of the imaging plate, but it does not have any effect in the imaging process itself.

Any suitable organic solvent such as ethyl glycol or decyloxypropanol can be used in the coating liquid.

Step 600: The plate is baked at a temperature of 110 ° C for 4 minutes. After the plate is cut to the appropriate size, it is stored in a warehouse at room temperature of 42 °C. When drying, it is necessary to heat the plate to the softening temperature of the resin, so that the plate can be kept in the long-term preservation process. Material stability. The specific drying time and temperature should be determined according to different machines and equipment. However, the drying temperature of the plate must reach above 110 °C to stabilize the coating.

Step 700: After the plate is cut to an appropriate size, it is stored in a warehouse at room temperature of 42 °C. After the plate has been processed as described above, it is cut to the right size and can then be delivered directly to the printer or stored directly at room temperature (possibly 10-45 °C). The plate processed by the above process can be stored for several months before use, and the quality of the plate will not be Very obvious change.

Hereinafter, the specific process of the present invention will be described by taking an aluminum coil raw material as an example, and the width of the aluminum coil is

1030mm, aluminum surface roughness Ra value is 0.18um, Rv value is 0.5 chaos

The process of producing a thermal CTP version includes the following steps:

Degreasing step: Using 31.14 g / liter of sodium hydroxide, the treatment temperature is 49 ° C, and the treatment time is 30 seconds.

Electrolysis step: a 78-second decontamination step was performed using an electrolyte comprising 7.34 g/l hydrochloric acid and 9.44 g/l boric acid at a voltage of 32.5 volts and a current of 1600 amps: using 7.0 g/l Sodium hydroxide, treatment temperature was 24.4 ° C, and treatment time was 70 seconds.

Oxidation step: using 143.1 g / liter of sulfuric acid and 71.3 g / liter of phosphoric acid, at a voltage of 29.5 volts (DC), a current of 1200 amps, a temperature of 22.8 ° C for 79 seconds after the oxidation of the aluminum plate Rinse and dry in DI water (demineralised water).

After testing, the Rv value of the aluminum plate treated by the above process was 1.80 um, and the Ra value was 0.44 um.

Then, the photosensitive adhesive prepared in the following formulation was coated on the surface of the aluminum plate with a squeeze coating head:

Ethylene glycol: 83%

Other solid materials: 17%, other solid substances including heat sensitive agents, phenolic resins and crystal violets, their proportions are:

Heat sensitive agent (2- [2 {2- chloro- 3- (1, 3- dihydro- 1, 1, 3- trimethyl- 2H- benz (e) ind ol-2-yl idene) ethyl i dene- 1 -eye lohexen- L-yl}

Ethenyl] - 1 , 1, 3-trimethyl- 1H- benz (e) indol ium, salt with 4-methylbenzene sulphonic acid) 2. 4% phenolic resin (K180 from K0Y0 (Japan)) 95. 95% crystal violet 1 After 65% of the coating, the aluminum plate was allowed to dry at 110 ° C for 4 minutes. After the media has been cut to the appropriate size, it is stored in a warehouse at room temperature of 42 °C.

After 90 days, the production was carried out again according to the above-mentioned entire process. After testing, the Rv value was 1.74 um.

Then, take a batch from the plate that has just been produced and the plates that were stored in the warehouse after the last production, respectively, in the Agfa Excal iber imaging mechanism version and use Agfa CTP developer at 26 °C. The lower development, the effect of the two batches of the plate is exactly the same, the imaging is fast, the good ink and water balance, no grungy phenomenon occurs.

The method for producing the positive-type thermal printing plate of the present invention is controlled by using a new electrolyte to control the Rv value of the plate to be less than 2.5 urn to control the depth of the bottom of the plate, and to control the amount of the photoresist to stay at the bottom; During the manufacturing process, the light energy is rapidly heated by laser irradiation and the heat sensitive agent is added to solve the problem of storage and transportation of the plate material. Example 2 The producer produced a 1030 mm aluminum roll on a reel production line to produce a printing plate. The production process consists of the following steps: Degreasing step: Using 32 g/l sodium hydroxide, the treatment temperature is 50 ° C and the treatment time is 30 seconds. Electrolysis step: An electrolytic solution comprising 8.5 g/L hydrochloric acid and 13.5 g/L acetic acid was used for 80 seconds at a treatment temperature of 30 ° C, an AC voltage of 11. 5 volts, and a current of 1000 amps. Decontamination step: Using 7.0 g/l sodium hydroxide, the treatment temperature was 25 ° C, and the treatment time was 70 seconds. Oxidation step: 200 g/L of sulfuric acid was used for 80 seconds at a DC voltage of 30 volts, a current of 1000 amps, and a temperature of 35 °C. Post-treatment: Treatment with polyethylene phosphate ("Polyvinyl phosphonic acid") was carried out at 85 ° C for 30 seconds. Then rinse with water and dry. After measurement, the Ra value of the aluminum plate treated by the above process was 0.41 um, and the Rv value was 2.4 um. The treated aluminum panels were coated with a solution of the following formulation: mercapto glycol: 40% ethyl glycol: 40% phenolic resin, Shell bakelite 6464: 9.6% Infrared heat sensitive agent:

2-[2 {2- chloro- 3-(1, 3-dihydro-l, 1, 3-trimethyb 2H-benz (e) indol-2-yl idene-l-cyc lohexen-l-yl} ethenyl] -1, 1, 3-tr imethyl- lH-benz(e) indolium : 0.28% Victoria Blue B : 0.1% After coating, the aluminum plate is dried at 1Q (TC temperature for 4 minutes. The plate is cut to size After that, it was stored in a warehouse at room temperature of 42 ° C for 90 days. The stored plate was plated on a screen imager at a speed of 800 r _P m (revolutions per minute), energy of 80%, and the developer of the following formulation was used automatically. Development in the developing machine, development time 30 seconds, development temperature 26 ° C: Sodium silicate: 12% Surfactant T304 ( Synperonic T304 ) : 0.1% Surfactant H6.6 (Triton H66 ) : 1.0% Water: 85.9% The developed plate was rinsed and dried, and examined with a microscope of 5Q times. The blank portion of the plate was not affected by the image dot. Example 3 This example and Example 2 are comparative examples. The same quality and batch of aluminum coils, using the production in Example 1 Process and coating, but using the following electrolyte: Containing 12 grams per liter of hydrochloric acid and 4 grams per liter of acetic acid. The rm value of the aluminum plate after the above process is 0. 7um, Rv value is

4. 3. It was coated and dried in the same manner as the aluminum plate of Example 1, and the aluminum plate was stored in a warehouse at 35 ° C for 90 days. After the treatment in the procedure of Example 2, it was found that the entire substrate was blue, and it was examined with a magnifying glass of 50 times, and it was found that the plate after the electrolytic sand molybdenum had a large number of blue dots. Since this blue dot absorbs ink during the printing process, and the blank portion of the printed matter also has a color, this version is obviously not applicable to printing. This situation is called "upper" in the printing industry. Example 4 The following formulation was used except for the electrolytic solution using the production process of Example 2: containing 8 g/l of nitric acid and 8 g/l of boric acid at a treatment temperature of 30 ° C, an alternating voltage of 12 volts, and a current of 1000 amps. It is processed for 80 seconds. Lum。 The processed aluminum plate Ra value of 0. 40um, Rv value 2. lum. The aluminum plate was then coated, dried, cut and stored as in Example 2. After the same treatment as in Example 2, observe the layout of the net, use 50 times For large mirror inspection, there are no blue dots in the blank part. Example 5 Using the production process of Example 2, the following formulation was used except for the electrolytic solution: 80 g of phosphoric acid was used at a treatment temperature of 22 ° C, a direct current voltage of 30 volts, and a current of 1,200 amps for 80 seconds. The aluminum plate was rinsed after oxidation, directly coated without any treatment, and then dried and coated as in Example 2. Produced and stored as in Example 2. After development, the layout is as clean as the version in Example 1. Example 6 An aluminum coil was treated using the process of Example 1, except that: oxidation and post treatment were carried out using the process of Example 2. The aluminum plate was coated and stored with the process of Example 1. The final layout blank portion is as clean as in Embodiment 1. The above is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any changes that can be easily conceived by those skilled in the art within the scope of the present invention are intended to be included within the scope of the present invention.

Claims

Rights request

A method of manufacturing a printing plate, comprising: the following technical steps:

(1) using a degreasing liquid to remove grease from the surface of the plate;

(2) Electrolytic treatment and decontamination treatment of the plate material;

(3) oxidizing the plate material;

(4) enhancing the adhesion and developing performance of the plate;

(5) coating the plate with a thermographic photosensitive adhesive;

(6) drying the plate;

(7) Cutting the plate material.

2. The method of manufacturing a printing plate according to claim 1, wherein: (1) wherein the plate oil removal solution is a 30-35 g/liter sodium hydroxide aqueous solution, and the treatment temperature is 48. ~ 52 ° C, processing time is 28 - 32 seconds.

3. The method of manufacturing a printing plate according to claim 1, wherein: (2) wherein: the plate material is electrolyzed by alternating current; the electrolyte used is composed of nitric acid or hydrochloric acid plus a corrosion inhibitor; The corrosion inhibitors described are boric acid, acetic acid, phosphoric acid, sulfuric acid or their salts.

4. A method of manufacturing a printing plate according to claim 3, wherein: (2) the electrolytic solution used in the electrolytic process is a mixture of hydrochloric acid and boric acid, by weight ratio, hydrochloric acid and boric acid. The ratio is 1: 1.1~1.3.

The method for producing a printing plate according to claim 1, wherein: (2) the detergent used in the decontamination treatment in the step is a sodium hydroxide aqueous solution of 7.0 to 8.0 g/liter. The treatment temperature is 24~25°C, and the treatment time is 70-75 seconds.

The method for manufacturing a printing plate according to claim 1, wherein: (3) the oxidizing solution used for oxidizing the plate material in the step is a mixture of phosphoric acid and sulfuric acid; The composition of the mixture with sulfuric acid is three parts of sulfuric acid to two parts of phosphoric acid; the treatment temperature is 22 to 24 ° C, and the treatment time is 75 to 80 seconds.

7. The method of manufacturing a printing plate according to claim 1, wherein: (5) the heat sensitive photoresist is composed of ethyl glycol and other solid materials; The base glycol is 80-85%, and the other solid materials are 15-20.

8. The method of manufacturing a printing plate according to claim 7, wherein: the other solid matter comprises a heat sensitive agent and a phenolic resin, and the proportion of the heat sensitive agent is 1.5% by weight. ~ 3.0%, the proportion of other solid substances is 97 ° /. ~ 98.5%.

9. A method of manufacturing a printing plate according to claim 8, wherein: said heat sensitive agent is:

2-[2 {2-chloro-3-(l, 3- dihydro- 1, 1, 3-tr imethyl-2H-benz (e) indol-2-yl idene) ethyl idene-l-cyclohexen-l-yl } ethenyl] -1, 1, 3 -tr imethyl-lH-benz (e) indolium, salt with 4- methy lbenzene sulphonic acid;

The formula is:

10. A method of producing a printing plate according to claim 1, wherein the drying temperature of the plate material in the step (6) is not less than 100 °C.