JPH0472720B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing a lithographic printing plate support made of an aluminum alloy. [Prior Art] A lithographic printing plate is a so-called "PS plate" which is an aluminum plate whose surface has been roughened and coated with a photosensitive composition and dried.
Those that have been subjected to plate-making processes such as water-washed lattice printing are widely used. This image exposure causes a difference in solubility in a developer in the subsequent development process between the exposed and non-exposed areas of the photosensitive resin layer, and then the development process creates a difference in solubility between the exposed and non-exposed areas of the photosensitive resin layer. One is dissolved in the developer or removed, and the other remains on the aluminum plate serving as the support to form an image. This image area exhibits ink receptivity, and the non-image area where the photosensitive resin layer has been dissolved and removed as described above exhibits water receptivity due to the exposed surface of the hydrophilic aluminum support. Therefore, by supplying dampening water (water or an aqueous liquid) to the plate surface made up of these two parts, a film of dampening water is maintained on the non-image area, and the ink is applied to the image area. Printing is performed by repeating the process of depositing the ink on the image area and directly or indirectly (that is, transferring it once to the blanket and then transferring it to the paper surface). In this printing, by appropriately selecting the photosensitive composition coated on the support, it is possible to obtain a printing plate that can produce as many as 100,000 good-quality prints from one printing plate. It is possible. However, in the current state of the printing industry, there is a demand for printing plates that can print even more sheets, and there is also a need to reduce the cost of printing plates.
Due to reasons such as simplifying printing operations, there is a strong desire to be able to obtain more printed matter, that is, to improve the printing durability of printing plates. One way to improve this printing durability is, in the case of a lithographic printing plate using aluminum as a support, after exposure and development using the usual method described above,
An effective and commonly used method is to sinter and harden the composition forming the image area by heating it at a high temperature (a process called burning) to strengthen the image area. be. The heating temperature and heating time of the normal burning process are 200 to 280° C. and about 3 to 7 minutes, depending on the composition forming the image. However, in order to improve the printing durability and shorten the working time, there is a demand for this burning treatment to be performed at a higher temperature and in a shorter time. On the other hand, aluminum used as a support for this lithographic printing plate includes AA1050, AA1100,
Aluminum alloys such as AA3003 are formed into ingots by normal continuous casting, hot-rolled, cold-rolled, and heat-treated in intermediate steps as necessary to form plates or strips, whose surfaces are machined. The surface is roughened by any one of chemical, chemical, and electrochemical methods, or a combination of two or more thereof, and is further subjected to anodization treatment. [Problems to be solved by the invention] However, when the aluminum alloy plates conventionally used as described above are heated at high temperatures of 280°C or higher, the aluminum recrystallizes, resulting in extremely low strength. If the plate is used as a support for a lithographic printing plate, handling of the plate becomes extremely difficult. There was a problem in that there were drawbacks such as the inability to register the colors of the plate when printing. An object of the present invention is to provide a method for producing an aluminum alloy plate that eliminates the drawbacks of the prior art as described above, does not impair the excellent printing plate performance of the conventional lithographic printing plate support, and is resistant to thermal softening. It is something to do. [Problem and means for solving the problem] A support for a lithographic printing plate is produced from an aluminum alloy containing 0.02 to 0.20% by weight of zirconium through a series of steps including hot rolling, cold rolling, intermediate annealing, and final cold rolling. In the manufacturing method, intermediate annealing is performed,
From the electrical resistance value of the rolled plate after final cold rolling, 380℃,
A method for producing a support for a lithographic printing plate, characterized in that the value obtained by subtracting the electrical resistance value after 6 hours of heating and the correction value of the contribution due to work hardening is 0.01 μΩ·cm or more. The aluminum alloy used in the present invention uses a base metal with a dullness of 99.50% by weight or more, and the impurities contained in the base metal are 0.40% by weight or less of iron and silicon.
The content is preferably 0.20% by weight or less. A characteristic component of the aluminum alloy is zirconium, whose content is 0.02 to 0.20% by weight. 0.02
If it is less than 0.20% by weight, the effect of improving thermosetting properties will be insufficient, and if it exceeds 0.20% by weight, the heat softening properties will be further improved, but the crystal structure of the aluminum plate will become non-uniform and printability will deteriorate. In addition, iron has the effect of refining the crystals of the alloy and preventing coarsening of the recrystallized grains, but if it exceeds 0.40% by weight, the size of iron-based compounds formed during casting increases, causing a decrease in printing performance. . Furthermore, if the silicon content exceeds 0.20% by weight, the effect of improving thermal softening properties due to zirconium will be reduced, so it is preferably kept at 0.20% by weight or less. Note that the aluminum alloy in the present invention is
Like AA1050 and AA1100, after facing the DC ingot,
By soaking at a temperature of 520°C or higher, and then hot rolling from a starting temperature of 450°C or higher to a finishing temperature of 350°C or higher, and cold rolling with a rolling reduction of 40% or higher, the appropriate plate thickness is obtained. Next, this cold-rolled plate is subjected to intermediate annealing, and further cold-rolled to a predetermined degree depending on the degree of processing to form a plate-like product with a thickness of 0.1 to 0.5 mm. It is used as an aluminum alloy plate for printing plate supports. In the present invention, the conditions of intermediate annealing are important in this series of steps, and the effect of adding zirconium is thereby further exhibited. For intermediate annealing, a continuous method is preferable to the conventionally used batch method, which suppresses the precipitation of Zr, Fe, etc., and ensures a sufficient amount of solid solution thereof. The conditions are as follows: Temperature increase: 20°C/second or more, preferably 50°C/second or more, Holding temperature: 350°C or more, preferably 400°C or more, Holding time: 30 seconds or less, preferably 15 seconds or less, Cooling rate: 500°C C/sec or more, preferably 1000 C/sec or more, thereby suppressing the precipitation of solid solution components during intermediate annealing to improve softening resistance, and further uniform recrystallization to maintain printing characteristics. In addition, since the method of directly measuring the solid solution content is complicated and difficult to use industrially, the present invention adopts a method of measuring the electrical resistance value as a simple method for estimating the solid solution content. Measure and substitute △ρ found by the following formula, and in that case, △ρ≧
It needs to be 0.01μΩ・cm. △ρ＝ρ _H −ρ _O −P _W =0.01μΩ・cm _ρW =0.002×(UTS _H −UTS380℃×6 hours) where: _ρH : Electrical resistance value of final cold rolled sheet (μΩ・cm) ρ _O : Electrical resistance value (μΩ・cm) obtained by heating the final cold-rolled sheet at 380℃ for 6 hours ρ _W : Correction value for the contribution due to work hardening (μΩ・cm) UTS _H : Electrical resistance value of the final cold-rolled sheet Tensile strength (Kg/mm ² ) UTS 380°C x 6 hours: Tensile strength (Kg/mm ² ) of the final cold-rolled sheet heated at 380°C for 6 hours Electrochemical graining method, in which electricity is applied in a nitric acid electrolyte to grain the surface; wire brush graining method, in which the aluminum surface is grained with a metal wire; ball graining method, in which the aluminum surface is grained with an abrasive ball and abrasive agent; and a nylon brush. A mechanical graining method such as a brush graining method in which the surface is grained with an abrasive and an abrasive can be used, and any of the above graining methods can be used alone or in combination. Thus, grained aluminum is chemically etched with acid or alkali. When an acid is used as an etching agent, it takes a very long time to destroy the fine structure, which is disadvantageous in industrial application, but this can be improved by using an alkali as an etching agent. Alkaline agents suitably used for these purposes include caustic soda, soda carbonate, sodium aluminate, sodium metasilicate, sodium phosphate, potassium hydroxide, lithium hydroxide, etc., and the preferred ranges of concentration and temperature are 1 to 50% each. wt%, 20-100℃,
Conditions are preferable such that the amount of Al dissolved is 5 to 20 g/m ² . After alkaline etching, pickling is performed to remove dirt (smut) remaining on the surface.
The acids used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and hydrofluoric acid. In addition, for the smut removal treatment after electrochemical surface roughening, preferably contact with 15 to 65% by weight sulfuric acid at a temperature of 50 to 90°C as described in JP-A-53-12739. Method of making
This is the alkali etching method described in Japanese Patent No. 28123. The aluminum plate treated as described above can be used as a support for a half-plate printing plate, but it can also be further subjected to treatments such as anodic oxidation coating treatment and chemical conversion treatment. The anodic oxidation treatment can be performed by a method conventionally used in this field. in particular,
When direct or alternating current is passed through aluminum in an aqueous or non-aqueous solution containing sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a combination of two or more of these, an anodized film forms on the surface of the aluminum support. can be formed. The treatment conditions for anodic oxidation vary depending on the electrolyte used, so they cannot be determined unconditionally.
Generally, the electrolyte concentration is 1 to 80% by weight, and the liquid temperature is 5%.
~70°C, current density of 0.5 to 60 ampere/dm ² , voltage of 1 to 100 V, and electrolysis time of 10 to 100 seconds are suitable. Among these anodic oxide coating treatments, it is particularly used in the invention described in British Patent No. 1412768. The method of anodizing in sulfuric acid at high current density and the method of anodizing using phosphoric acid as an electrolytic bath as described in British Patent No. 3,511,661 are preferred. The anodized aluminum plate may be further treated by immersion in an aqueous solution of an alkali metal silicate, such as sodium silicate, as described in U.S. Pat. An undercoat layer of hydrophilic cellulose (eg, carboxymethyl cellulose, etc.) containing a water-soluble metal salt (eg, zinc acetate, etc.) can also be provided as described in Japanese Patent No. 3,860,426. On the lithographic printing plate support treated as described above, a conventionally known photosensitive layer is provided as a photosensitive layer of a PS plate, and a photosensitive lithographic printing plate can be obtained. The lithographic printing plate obtained by the plate-making process has excellent performance. The composition of the above-mentioned photosensitive layer includes the following. Photosensitive layer consisting of diazo resin and binder Specifications of U.S. Pat. The binder is preferably a diazo resin described in British Patent No. 1350521 or the like.
1460978 and U.S. Patent No. 4123276,
The binders described in the specifications of the same No. 3751257 and the same No. 3660097 are preferred. Photosensitive layer made of o-quinonediazide compound Particularly preferred o-quinonediazide compounds are:
It is an o-naphthoquinone diazide compound, for example, U.S. Pat. No. 2,766,118, U.S. Pat.
No. 2772972, No. 2859112, No. 2907665,
Same No. 3046110, Same No. 3046111, Same No. 3046115
No. 3046118, No. 3046119, No. 3046119, No. 3046118, No. 3046119, No.
No. 3046120, No. 3046121, No. 3046122,
Same No. 3046123, Same No. 3061430, Same No. 3102809
No. 3106465, No. 3635709, No. 3635709, No. 3106465, No. 3635709, No.
It is described in numerous publications including the specifications of No. 3647443, and these can be suitably used. Azide compound and binder (photosensitive layer made of a polymer compound) For example, British Patent No. 1235281, British Patent No. 1495861
The specifications of each issue and JP-A No. 51-32331,
In addition to the compositions comprising an azide compound and a water-soluble or alkali-soluble polymer compound described in JP-A-51-36128, etc., JP-A-50-5102,
Included are compositions comprising a polymer containing an azide group and a polymer compound as a binder, which are described in publications such as No. 50-84302, No. 50-84303, and No. 53-12984. Other photosensitive resin layers For example, polyester compounds disclosed in JP-A-52-96696, British Patent No.
No. 1112277, No. 1313390, No. 1341004,
Included are polyvinyl cinnamate resins described in U.S. Pat. No. 1,377,747 and other specifications, and photopolymerizable photopolymer compositions described in U.S. Pat. Additives can be added to these various photosensitive compositions as appropriate. For example, cyclic acid anhydrides are used as sensitizers to increase sensitivity, dyes are used as printing agents to make the exposed image immediately visible, and extenders are used for the image area, and for coloring the plate surface. Various additives such as colorants can be added. A coating solution is prepared by appropriately blending the above components (materials) and making a solution with an organic solvent. The concentration of the coating liquid is 2 to 50% by weight in terms of solid content. This is coated onto the above-mentioned support by conventional means.
There are various coating methods such as a roll coater, a reverse roll coater, a gravure coater, an air knife method, and a curtain coating method, which can be appropriately selected and used for the present invention. The coating amount is about 0.1 to 7.0 g/m ² as a solid substance, preferably about 0.5 to 4.0 g/m ² . After application,
After all, it is dried by a known conventional method, and if necessary, it is cut into a suitable size. The printing plate (developing plate) manufactured in this way is imagewise exposed and then brought into contact with a developer. Specifically, the original plate is immersed in a developer bath or the original plate is exposed to a developer. Supplied and developed using methods such as spraying. The developer has a unique composition for each of the above compositions, and specific examples are described in the literature for each composition, so it is possible to use them as a developer in accordance with each composition as appropriate. can.
Depending on the composition, there are two types: positive type, in which exposed areas are removed during development, and negative type, in which non-exposed areas are removed. need to be selected. After the development treatment, the printing plate is subjected to appropriate post-treatment as desired. In post-processing, the most relevant process is burning for enhancement of image parts. Regarding burning, for example, JP-A-52-6205, JP-A-Sho.
No. 51-34001, Special Publication No. 55-28062, Special Publication No. 57
Although it is described in Publication No. 3938 and US Patent No. 4191570, basically, burning involves placing a developed printing plate in an atmosphere at a temperature of 150° to 350°C, and burning the image portion of the plate surface. In other words, it is hardening. In this case, it is preferable to supply an aqueous solution of, for example, boric acid, a borate salt, an anionic surfactant, or another compound having a specific chemical structural formula to the printing plate before or after burning. Thereby, various harmful effects caused by burning can be prevented. The burning temperature is related to the burning effect as well as the processing time, and if the processing time is about 3 to 10 minutes, it can be performed at a temperature of 180 to 300°C. The aluminum alloy support produced according to the present invention can withstand such burning treatment,
It maintains its inherent physical properties and achieves extremely high printing durability, especially as a support for lithographic printing plates. The present invention will be explained in more detail with reference to Examples below. Note that % indicates weight % unless otherwise specified. Example 1 Table 1 shows four types of aluminum DC ingots (560
mm thickness), each was subjected to homogenization treatment at 560℃ for 6 hours, then hot rolled and cold rolled to a thickness of 1.5mm, and then batch-processed at 100℃/
Intermediate annealing is performed by raising the temperature for an hour, holding it at 400℃ for 1 hour, and allowing it to cool naturally. Also, when using a continuous method, magnetic induction heating (Transverse Flux Induction) is performed.
Intermediate annealing was performed by heating at 150°C/sec, holding at 450°C for 5 seconds, and water cooling at 500°C/sec, followed by final cold rolling in each case to a thickness of 0.3 mm. . Table 1 shows the chemical compositions of aluminum alloys A, B, C, and D for offset printing plates.

[Table] Next, these aluminum alloy rolled plates were heated with a rotating nylon brush in a suspension of pumice stone and water.
After graining, it was etched using a 20% aqueous solution of caustic soda so that the amount of aluminum dissolved was 5 g/m ² . After thoroughly washing with running water, pickling with a 25% nitric acid aqueous solution and washing with water to prepare a substrate. The board prepared in this way was
As described in Publication No. 146234, nitric acid 0.5
AC electrolysis was carried out at a current density of 20 A/dm ² or more in an electrolytic bath containing ~2.5%. After cleaning the surface by immersing it in a 15% sulfuric acid solution at 50°C for 3 minutes,
Bath temperature 30℃ in electrolyte mainly composed of 20% sulfuric acid
Then, an oxide film of 3 g/dm ² was provided. The following photosensitive layer was provided on the sample prepared in this way so that the dry coating amount was 2.5 g/m ² . Ester compound of naphthoquinone-1,2-diazido-5-sulfonyl chloride, pyrogallol, and acetone resin (described in the Examples of US Pat. No. 3,635,709) 0.75 g Cresol novolac resin 2.00 g Oil Blue #603 (Orient Chemical 0.04g ethylene dichloride 16g 2-methoxyethyl acetate 12g The photosensitive lithographic printing plate thus obtained was placed in close contact with the transparent positive and exposed to a PS light [equipped with a Toshiba metal halide lamp MU2000-2-OL type 3KW light source] from a distance of 1m. After exposure for 30 seconds using a 5% sodium silicate aqueous solution (sold by Fuji Photo Film Co., Ltd.), the film was developed by immersing it in a 5% by weight aqueous solution of sodium silicate for about 1 minute. Next, after washing with water, potassium borate 4
The weight percent aqueous solution was soaked into a sponge, applied onto the developed printing plate, and squeegeeed to ensure that the application was as uniform as possible. After drying the printing plate treated in this way, it was heated at 260 liters in a Burning Processor 1300 [equipped with a 12 KW heat source and sold by Fuji Photo Film Co., Ltd.].
℃, 280℃, 300℃, and 320℃ for 7 minutes. After cooling, the 0.2% proof stress value of the printing plate which had been burnt to 260°C to 320°C was measured by a tensile test.
As a result, △ρ (electrical resistance value of the rolled plate after final cold rolling, electrical resistance value after heating at 380°C for 6 hours, and correction value for contribution due to work hardening) of each aluminum rolled plate used as a support. )
(μΩ·cm) and are shown in Table 2. Note that each electrical resistance value was measured according to JISH0505 "Method for measuring volume resistivity and electrical conductivity of non-ferrous metals".

[Table] As shown above, aluminum alloys, A, B,
When rolling C and D, in this example, when the intermediate annealing was performed by the batch method, Δ was both smaller than the range of the present invention, and when it was performed by the continuous method, both were within the range of the present invention, The latter had higher yield strength at high temperatures, the plate had firmness, and the plate was easier to handle. In addition, these printing plates can be printed using an offset printing machine.
When it was attached to KOR and printed, good printed matter was obtained with no stains or dots in the non-image areas. Table 3 shows the printing durability at that time.

[Table] [Effects of the Invention] As described above, according to the present invention, a support for a lithographic printing plate that can provide a printing plate with low heat softening property, high heat resistance, and good printability can be obtained. Obtainable.

Claims (1)

[Claims] 1. A method for producing a lithographic printing plate support from an aluminum alloy containing 0.02 to 0.20% by weight of zirconium through a series of steps including hot rolling, cold rolling, intermediate annealing, and final cold rolling, in which intermediate annealing is performed, From the electrical resistance value of the rolled plate after final cold rolling
The value obtained by subtracting the electrical resistance value after heating at 380℃ for 6 hours and the correction value for the contribution due to work hardening is 0.01μΩ・
1. A method for producing a support for a lithographic printing plate, the method comprising: manufacturing a support for a lithographic printing plate so that the thickness is at least cm.