JPH0480378B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for manufacturing a photosensitive printing plate, and particularly to a method for manufacturing a photosensitive printing plate with improved vacuum adhesion. [Prior art] Conventionally, when exposing a photosensitive printing plate to light through an original image, the photosensitive printing plate and the original image are placed between a rubber sheet and a pressure bonding glass in order to make the original image completely adhere to the surface of the photosensitive layer of the photosensitive printing plate. A method was used in which the rubber sheet and the bonded glass were placed one on top of the other, and a vacuum was created between the rubber sheet and the bonded glass to bring them into close contact. In order to shorten the time required for vacuuming and adhesion, for example, as described in JP-A-51-111102, a photosensitive layer is provided with a minute pattern consisting of a coated area and a non-coated area. A printed version is known. Furthermore, Japanese Patent Application Laid-Open No. 12974/1983 discloses a method of powdering a solid powder and fixing it onto a photosensitive printing plate using heat. Furthermore,
JP-A-57-34558 discloses a method of spraying an aqueous solution in which a resin is dissolved or dispersed onto the surface of a photosensitive layer and drying the solution. However, in photosensitive printing plates provided with such fine pattern layers, solid powder layers, etc. (hereinafter referred to as "matte layers"), the height of the convex portions of the matte layers decreases due to pressure, and As a result, there was a drawback that vacuum adhesion deteriorated. For example, when printing multiple sides of a photosensitive printing plate, or after vacuum-adhering an original image, you discover that there is dust on the film surface, remove it, and then vacuum-adher the original image again. In some cases, an original image is vacuum-adhered to the same photosensitive printing plate multiple times. In such cases, with a photosensitive printing plate on which a matte layer is formed on the surface using a conventional method, the original image can be brought into close contact with the original image in a relatively short time during the first vacuum contact, but at this time, The convex portions of the pine layer are crushed by atmospheric pressure. For this reason,
When vacuum-adhering the original picture again, the time required becomes significantly longer. Recently, with the mass production of photosensitive printing plates, a processing method has been implemented in which a photosensitive printing plate provided with a matte layer is once wound up into a coil, and then cut at high speed and packaged. This winding is performed under high tension in order to prevent the coil from slipping (unwinding). Therefore, the closer to the center of the winding coil, the greater pressure is applied to the surface of the photosensitive printing plate, crushing the convex portions of the matte layer, and as a result, the vacuum adhesion deteriorates. The reason why the convex parts of the mat layer are crushed by pressure and the vacuum adhesion deteriorates as a result is that the resin forming the convex parts of the mat layer is soft. It is also thought that the large convex portions, which greatly contribute to vacuum adhesion, are selectively crushed. Therefore, in order to prevent a decrease or fluctuation in vacuum adhesion, the convex portions of the mat layer should be made of a hard material, or the height distribution of the convex portions should be made as narrow as possible, and the pressure should be applied as many times as possible. It can be seen that the influence of pressure can be reduced by dispersing it in the convex portions. The present inventors paid particular attention to the latter point and conducted extensive research. [Object of the Invention] An object of the present invention is to provide a method for producing a photosensitive printing plate in which the vacuum adhesion is less reduced or fluctuated. [Structure of the Invention] As mentioned above, the present inventors have investigated various ways to disperse pressure and reduce the influence of pressure by narrowing the height distribution of the convex portions of the pine layer as much as possible. The present inventors have discovered that the above object of the present invention can be achieved by applying appropriate pressure to crush the convex portions of the mat layer after forming the layer, and have completed the present invention. The present invention is a photosensitive printing plate characterized in that after a matte layer is formed on the surface of a photosensitive printing plate, pressure is applied to the matte layer to reduce the height of the convex portions of the matte layer and to average them. This is a method for manufacturing printing plates. Incidentally, it is known to apply pressure using a roll or the like in order to adhere solid fine powder, which is the material for forming the convex portions of the matte layer, to the surface of a photosensitive printing plate. For example, in the lower right column, line 14 of page 3 of JP-A-55-12974, it is stated that ``Means for applying pressure to the solid powder by means of rolls or the like may be used in combination.'' However, he later added, ``In addition to the methods described above, various methods of fixing the solid powder to the surface of the photosensitive printing plate can be considered, but in short, any method that fixes the solid powder and the photosensitive layer to the extent that it is not extremely deformed is sufficient. "As is clear from the description, this is not intended to lower the height of the formed matte particles by pressure, but to bring the solid fine powder into complete contact with the photosensitive layer. It means to put pressure on someone. When fine powder is fused to a surface using heat, the viscosity of the molten resin is very high, so it takes a long time to completely adhere to the surface. However, holding the product at high temperature for a long time not only increases manufacturing costs, but also
This is not preferable because it has an adverse effect on the photosensitive layer. Therefore, as disclosed in Japanese Patent Application Laid-open No. 55-101951, etc., fine powder is photosensitive printed in a short time by contacting it with a heating roll having a surface with good mold releasability and thermally fusing it. This ensures complete contact with the surface of the plate. The rolls used at this time are made of fluororesin such as Teflon (trade name), which is not as hard as metal rolls, so the mat particles are not completely crushed. This method uses a heated roll, so the matte particles are thermally fused to the surface of the photosensitive printing plate, and then a part of the sphere is cut flat by the surface tension of the resin that makes up the particles. It solidifies into the desired shape.
Therefore, the height of the convex portions formed on the surface is proportional to the size of the pine particles, and the distribution of the height of the convex portions is determined by the particle distribution of the pine particles. In addition, if the powdered solid powder is locally dissolved and fixed to the photosensitive layer by the solvent remaining in the photosensitive layer, apply light pressure to push the fine powder a little into the photosensitive layer and remove the solvent. It is desirable to bring the differential powder into sufficient contact with the powder. However, the height distribution of the convex portions of the matte layer thus obtained is still wide, and such photosensitive printing plates still have the disadvantage that vacuum adhesion is significantly reduced by pressure. In this way, applying pressure to pine particles was known, but the purpose of this was to make the pine particles stick, not to prevent pressure-induced fluctuations in vacuum adhesion. Moreover, in practice, it has not been possible to prevent or reduce variations in vacuum adhesion due to pressure by such a method. That is, no attempt has ever been made to apply pressure after forming the mat layer in order to equalize the height of the convex portions of the mat layer. The present inventors have surprisingly found that after forming the matte layer, by lowering and averaging the height of the matte layer using pressure, a photosensitive printing plate that is resistant to pressure and has good vacuum adhesion can be obtained. I discovered that. The mat layer forming method applicable to the present invention is as follows:
A method of making the photosensitive layer uneven (making it uneven during coating, adding a matting agent internally, making it uneven when drying using a foaming agent), a method of making the top layer that does not contain the photosensitive material uneven (making it uneven when applying a matting agent) There are various methods such as a resin layer containing a resin layer, a matte layer consisting of a coated part and a non-coated part)), but a matte layer consisting of a coated part and a non-coated part is preferable because it has less negative effect on vacuum adhesion and other properties. A method of forming is advantageously used. Particularly preferred is one in which the applied portion is removed during development. Copolymers containing the following monomer units (a), (b), and (c) are particularly preferred as resins used in this method, from the viewpoint of strong adhesion to the photosensitive layer and hardness. Are better. (a) at least one monomer unit selected from the group consisting of alkyl acrylates whose alkyl residues have 2 to 10 carbon atoms and alkyl methacrylates whose alkyl residues have 4 to 10 carbon atoms; . (b) At least one monomer unit selected from the group consisting of styrenes, acrylonitriles, methyl methacrylate and ethyl methacrylate. (c) at least one monomer unit selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, itaconic acid, and alkali metal salts and ammonium salts thereof. The monomer unit (a) is a component that imparts adhesion to the surface of the photosensitive layer, and specific examples include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n- Amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate,
Included are 2-ethylhexyl methacrylate, n-octyl methacrylate, n-decyl methacrylate, and the like. The monomer unit (b) is a component that imparts resistance to pressure, and specific examples thereof include styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,4-dimethylstyrene, 3,5-dimethylstyrene, 2,
4,5-trimethylstyrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 3,5-diethylstyrene, 2,4,5-triethylstyrene, p-n -butylstyrene, m-sec-butylstyrene, m-tert-butylstyrene, p-hexylstyrene, p-n-heptylstyrene, p-
2-Ethylhexylstyrene, o-fluorostyrene, m-fluorostyrene, p-fluorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, 2,3-dichlorostyrene, 2,4-dichlorostyrene, 2 , 5-dichlorostyrene, 2,6-dichlorostyrene, 3,
4-dichlorostyrene, 3,5-dichlorostyrene, 2,3,4,5,6-pentachlorostyrene, m-trifluoromethylstyrene, o-cyanostyrene, m-cyanostyrene, m-nitrostyrene, p- Nitrostyrene, p-dimethylaminostyrene, acrylonitrile, α-chloroacrylonitrile, α-bromoacrylonitrile, α
-trifluoromethylacrylonitrile, α-trifluoromethylcarboxyacrylonitrile,
Includes methyl methacrylate, ethyl methacrylate, etc. The above monomer unit (c) is a component that improves solubility in a developer, and specific examples thereof include acrylic acid, sodium acrylate, potassium acrylate, ammonium acrylate, methacrylic acid,
These include sodium methacrylate, potassium methacrylate, ammonium methacrylate, maleic acid, sodium maleinate, potassium maleate, ammonium maleate, itaconic acid, sodium itaconate, potassium itaconate, ammonium itaconate, and the like. In such copolymers, the monomer units
The amounts of (a), (b) and (c) are 10 to 70% by weight and 20% by weight, respectively.
-80% by weight and ranges from 6 to 50% by weight are preferred. As the amount of monomer unit (a) decreases below 10% by weight, the adhesion of the copolymer to the surface of the photosensitive layer decreases, while as the amount exceeds 70% by weight, the pressure resistance of the copolymer decreases. Sexuality decreases. Also,
As the amount of monomer units (b) becomes less than 20% by weight, the height of the copolymer decreases and the pressure resistance decreases, while as the amount becomes more than 80% by weight, the height of the copolymer decreases. The solubility in the developer decreases, and the adhesion to the photosensitive layer also decreases. Furthermore, as the amount of the monomer unit (c) becomes less than 6% by weight, the solubility of the copolymer in a developer deteriorates, while as the amount becomes more than 50% by weight, the copolymer becomes brittle, and the photosensitive layer becomes weaker. The adhesion force to the surface also decreases. Therefore, particularly preferred monomer units
The amounts of (a), (b) and (c) are 15 to 50% by weight, respectively;
40-70% by weight and 10-25% by weight. The above copolymer is produced by solution polymerizing in an organic solvent, evaporating to dryness, and turning it into a fine powder in a pulverizer.
Part of (c) acrylic acid, methacrylic acid, maleic acid, or itaconic acid can be obtained as a sodium salt, potassium salt, or ammonium salt as an aqueous copolymer solution. Alternatively, in the same manner as the usual latex synthesis method, raw monomers may be emulsified in water with a surfactant and then emulsion polymerized using a polymerization initiator such as potassium persulfate to obtain an aqueous dispersion. . The copolymer may also contain fillers. Examples of the filler include silicon dioxide, zinc oxide, titanium oxide, zirconium oxide, glass particles, alumina, and polymer particles (eg, particles of polymethyl methacrylate, polystyrene, phenolic resin, etc.). Two or more of these can be used in combination. Methods of coating these resins to form a matte layer include a method of solidifying fine powder of the resin on the photosensitive layer using heat or a solvent (Japanese Patent Application Laid-open No. 12974/1983), and a method of dissolving or dispersing the resin. A method of spraying and drying the aqueous liquid
34558), but from the viewpoint of safety, manufacturing stability, cost, etc., the matting methods described in JP-A-57-34558 (air spray method, airless spray method, electrostatic air spray method) , electrostatic atomization, electrostatic coating, etc.) are preferred, and electrostatic atomization and electrostatic coating, which have a high adhesion rate, are particularly preferred. In the present invention, since the height of the convex part is lowered by pressure after the mat layer is formed, it is preferable that the height of the convex part at the time of forming the mat layer is made higher than before. A range of 30μ is preferred. In order to increase the height of the convex portion, it is better to increase the particle size of the fine powder when using the method disclosed in JP-A-55-12974, and by increasing the particle size of the fine powder when using the method disclosed in JP-A-57-34558. It is preferable to increase the concentration, increase the size of the matte liquid fine particles, raise the temperature and lower the humidity during the adhesion of the fine particles, reduce the amount of post-humidification, etc., and it is particularly good to increase the liquid concentration. Although the influence of the size (width) and amount (number) of the convex portions on the vacuum adhesion time is smaller than the influence exerted by the height of the convex portions, their influence on the adhesion strength and pressure resistance is large. Therefore, the size (width) of the convex portion is 5 to 200μ, and the amount (number) is 1 to 1000.
A suitable number is 5 to 500 pieces/mm ² , preferably 5 to 500 pieces/mm ² .
If it is lower than this range, the adhesion strength and pressure resistance of the convex portions will be low, and if it is higher than this range, it will have an adverse effect on the developability, tone reproducibility, etc. of the photosensitive printing plate. Pressure is applied to the mat layer thus formed to reduce the height of the convex portions. Pressure can be applied by any method, such as vacuum-adhering a glass plate, pressing a metal plate or the like on top of the surface, or pressing a metal or other roll.
The method of crimping onto rolls is the most suitable since it is easy to mass-produce. The pressure applied is close to the pressure experienced when the original painting is placed in vacuum contact, that is, atmospheric pressure.
It is preferable that it is 0.8Kg/cm ² or more. This pressure is determined by the height, shape, number, material, material of the photosensitive layer, desired height of the protrusions, method of pressurization, material of the pressure member, and winding process. Generally, a range of 0.8 to 10 Kg/cm ² is appropriate, although it varies depending on post-processing conditions. The material for the pressure member may be any material that is harder than the pine layer forming resin; for example,
Metal, glass, reinforced plastic, etc. are preferred. When such a pressure member is used to uniformly apply pressure to the surface of the photosensitive printing plate, a large force is selectively applied to the tall protrusions, so these are selectively crushed and the protrusions are crushed. Height is averaged. Pressure must be applied at a temperature at which the convex portion-forming resin does not undergo thermal fluidization. Therefore, the temperature during pressurization varies depending on the type of resin, but generally 50°C or less, usually room temperature, is sufficient. The height of the convex part after pressurization is 1
A range of ~15μ is preferred. If it is lower than 1μ, the vacuum adhesion will be poor, and if it is higher than 15μ, the distance between the photosensitive layer and the film will be too wide, resulting in poor tone reproducibility and causing blurring. Further, the pressure may be applied uniformly over the entire surface of the photosensitive printing plate, or may be applied only to the central portion that is used in close contact with the original film. A photosensitive printing plate, which is the object to which a resin is attached as described above, basically has a photosensitive layer provided on a support. In the case of a lithographic printing plate, the effects of the present invention are significantly exhibited. Various supports for such photosensitive lithographic printing plates are known, and details thereof are described in British Patent Publication No. 2030309A. Further, the photosensitive layer may be made of a diazo resin, an o-quinone diazide compound, a photosensitive azide compound, a photopolymerizable composition, or a photosensitive resin. These details are also explained in detail in the above-mentioned publication.
The thickness of the photosensitive layer is generally from 0.1 to 0.1 by dry weight on one side.
7g/ ^m2 , preferably 0.5-3g/ ^m2 . [Effect of the invention] By applying pressure in this way to lower the height of the convex portions and thereby averaging the heights of the convex portions, it is thought that the density of the convex portions will increase and the pressure will be dispersed. Therefore, the deformation of the convex part due to pressure is extremely rare, and the vacuum adhesion does not deteriorate even if the vacuum adhesion operation is repeated multiple times. There is almost no difference in vacuum adhesion between the two parts. Furthermore, even if the conditions during the formation of the pine layer change and the shape, especially the height, of the convex parts changes, this pressure treatment averages out the height of the convex parts, so it will always remain stable. A matte layer can be formed and a stable vacuum adhesion time can be ensured. [Examples] Examples of the present invention will be specifically shown below, but the present invention is not limited thereto. Example 1 and Comparative Examples a and b Aluminum plate with a thickness of 0.24 mm, width 1003 mm, length
3000m was continuously grained using a nylon brush and 400 mesh of pumice stone-water suspension.
Washed thoroughly with water. This plate was immersed in a 25% sodium hydroxide aqueous solution at 45° C. for 9 seconds for etching, washed with water, and then further immersed in 20% nitric acid for 20 seconds and washed with water. The amount of etching on the grained surface at this time was approximately 3 g/m ² . Next, this plate was coated with a DC anodic oxide film of 3 g/m ² at a current density of 15 A/dm ² using 7% sulfuric acid as an electrolyte, and then washed with water and dried. On this support, naphthoquinone-1,2- of polyhydroxyphenyl obtained by polycondensation of acetone and pyrogallol as described in Japanese Patent Publication No. 43-28403 was used.
A photosensitive solution was prepared by dissolving 1 part by weight of cyazide-5-sulfonic acid ester and 2 parts by weight of novolac-type phenol formaldehyde resin in 20 parts by weight of 2-methoxyethyl acetate and 10 parts by weight of methyl ethyl ketone, and the photosensitive solution was coated on the above support.・After drying, a matte layer-forming resin liquid is sprayed and adhered as described below to form a matte layer, and a photosensitive lithographic printing plate is prepared. Next, this is pressed at room temperature using a metal roll ( It was 4 to 5 kg/cm ² ) as measured by Prescale manufactured by Fuji Photo Film Co., Ltd. Furthermore, the initial tension was set to 400Kg, and the tension was continuously lowered until the tension was 200Kg at the time of 3000m winding, and then cut and packaged at high speed to 1003mm x 800mm.
Sample 1 was created. Comparative sample a was prepared in the same manner except that no pressure was applied using a metal roll. In addition, without applying pressure with metal rolls, and
Comparative sample b was prepared in the same manner except that the resin liquid concentration was changed.
It was created. Table 1 shows the resin liquid composition and processing conditions. In addition, for all samples, the atomizing head rotation speed of the rotary atomizing electrostatic coating machine was 25,000 rpm, the resin liquid feeding rate was 40 ml/min, and the voltage applied to the atomizing head was -
90kv, ambient temperature during application is 25℃, relative humidity is 50
Approximately 2.5 seconds after application, steam is sprayed onto the surface to moisten it, and 3 seconds after the surface has been moistened, the temperature is
It was dried by blowing warm air at 60°C and 10% humidity for 5 seconds.

[Table] The pine particles near the winding core, the middle (1500 m), and the outside of the winding (3000 m) of each sample were observed using an electron microscope, and film original plates (550 mm x 650 mm) were superimposed using a vacuum contact printer. The vacuum adhesion time (first time) when the plate was brought into close contact with the vacuum plate after being vacuumed for 2 minutes.
The film was removed and the vacuum adhesion time was measured again (second time). In addition, the sample near the outside of the winding (3000 m) was placed in close contact with the original film, and then exposed to light from a distance of 70 cm using a 30 ampere carbon arc lamp. The film was developed for 60 seconds at 25°C using a 6-fold dilution of the developer. The exposure time at this time was set to a point where the 5th step was completely clear in a gray scale with a density difference of 0.15, and it was observed to what extent the minimum halftone dot of the original film was reproduced. These results are shown in Table 2.

【table】

【table】

[Table] The photosensitive lithographic printing plate according to the prior art is sample b. The first vacuum contact time for the outer sample after winding was 35 seconds, while the second vacuum contact time was longer at 45 seconds. This indicates that the convex portion was crushed by the first vacuum contact. In addition, in this sample b, the vacuum adhesion time varies from 35 seconds (outside) to 45 seconds as it approaches the winding core side.
seconds (middle), and 65 seconds (core). Observation with an electron microscope revealed that this was because the high convex portion was pushed in on the winding core side, reducing the height. Furthermore, by increasing the resin liquid concentration, it is possible to increase the height of the convex portion without changing its diameter (sample a). This makes it possible to obtain a vacuum contact time of 36 seconds, which is comparable to the outer sample of sample 1, even at the core. However, while the first vacuum contact time for the outer sample after winding was 20 seconds,
The vacuum adhesion time for the second time was longer at 26 seconds, and the vacuum adhesion times were significantly different for the outside (20 seconds), middle (28 seconds), and winding core (36 seconds). This is because even if the height of the convex part is increased, it shows the same behavior in response to pressure, and electron microscopic observation shows that the high convex part of the winding core is being crushed from above. observed. In addition, regarding minimum halftone dot reproducibility, the plate without a matte layer and sample b reproduced 2%, whereas sample a lost the minimum halftone dot of 2% and reached 3% halftone. I just couldn't reproduce it.
This is because the distance between the plate and the film was too wide due to the increased height of the convex portion. On the other hand, sample 1 according to the present invention was used for the first time (36
The vacuum adhesion times were very stable, such as the second time (37 seconds), the outside (36 seconds), the middle (38 seconds), and even the core (40 seconds). In addition, the minimum halftone dot reproduction was 2%, and good results were obtained. Observation with an electron microscope revealed that the upper portions of the tall convex portions were pushed in by the pressure applied by the metal rolls. For this reason, the mat layer of Sample 1 of the present invention is strong against pressure and is not crushed any further at the winding core or after vacuum contact, providing a stable vacuum contact time. . Example 2 In Comparative Example b, the resin liquid concentration was set to 11.5%, and after cutting to 1003 mm x 800 mm without winding up, the film was vacuum-adhered to pressure-bonded glass for 2 minutes using a printer without overlapping with the original film. When this plate was stacked with a film and the time when it was in vacuum contact was measured.
It was very stable at 35 seconds (first time) and 37 seconds (second time), and the minimum halftone dot reproducibility was also good. Example 3 and Comparative Example c The same operations as in Example 1 and Comparative Example b were repeated except that the film was cut into 1003 mm x 800 mm without being wound up (referred to as Example 3 and Comparative Example c, respectively). At this time, the pine layer forming conditions are shown in Table 3.
It was varied as shown. The first vacuum adhesion time of these samples was measured. The results are shown in Table 3. It can be seen that Example 3 according to the present invention is stable even if the manufacturing conditions vary.

[Table] Example 4 and Comparative Example d A styrene-acrylic acid-butyl acrylate (ratio 45:30:20) copolymer was pulverized using a jet pulverizer at supersonic speed, and then classified using a classifier. Direction diameter: 0.5 to 40μ (Example 4)
A heat-fusible fine powder of 0.5 to 30 μm (Comparative Example d) was obtained. These heat-fusible fine powders were powdered with a spray gun on the surface of the photosensitive lithographic printing plate before being sprayed as shown in Example 1 (approximately 170 particles/powder).
mm ² ), and was exposed to an air bath at 150°C for 10 seconds to make it stick, and then Example 4 was further crimped with a metal roll (approximately 2 mm 2 ).
Kg/cm ² : prescale measurement). This is 1003
After cutting to mm x 800 mm, vacuum adhesion was examined.

[Table] It can be seen that Comparative Example d has a large fluctuation between the first and second times and is weak against pressure, whereas Example 4 is strong against pressure. In Example 4, it was found through electron microscopy that the tall pine particles were pressed in by pressure from above and exhibited strong resistance to pressure.

Claims (1)

[Claims] 1. A method characterized in that after a matte layer is formed on the surface of a photosensitive printing plate, pressure is applied to the matte layer to reduce the height of the convex portions of the matte layer and to average them. A method for producing a photosensitive printing plate. 2. The method for producing a photosensitive printing plate according to claim 1, wherein the pressure is 0.8 to 10 Kg/cm ² . 3. The method for producing a photosensitive printing plate according to claim 2, wherein the matte layer comprises a coated area and a non-coated area that are removed during development.