JPS6151395A - Preparation of support for planographic printing plate - Google Patents

Abstract

PURPOSE:To obtain an aluminum alloy plate not losing excellent capacity as a printing plate and hard to thermally soften, by performing intermediate annealing so that the electric resistance value of a rolled plate satisfies a specific condition. CONSTITUTION:Intermediate annealing is performed so that the value, which is obtained by subtracting an electric resistance value after heating at 380 deg.C for 6hr and a correction value corresponding to contribution by processing hardening from the electric resistance value of a rolled plate after final cold rolling, is 0.01OMEGA.cm or more. This aluminum alloy is prepared by using Al being a metal with purity of 99.50wt% and the impurities contained in the metal desirably consists of 0.40wt% or less of iron and 0.20wt% or less of silicon. The content of zirconium of the aluminum alloy is set to 0.02-0.20wt% and, if below 0.02%, the improving effect of a heat softening characteristic is insufficient and, if exceeds 0.20wt%, the heat softening characteristic is improved still more but the crystal structure of the aluminum alloy plate becomes non-uniform and the printability thereof is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a support for a lithographic printing plate made of an aluminum alloy.

[Prior Art] As a lithographic printing plate, a photosensitive composition is coated on an aluminum plate whose surface has been subjected to a roughening treatment, and then dried. A so-called "PS plate" is imagewise exposed, developed, and washed with a water-washing lacquer. Those that have been subjected to a plate-making process such as printing are widely used.This image exposure creates a difference in solubility in a developer between the exposed and non-exposed areas of the photosensitive resin layer in the subsequent development process. Then, through development processing, either the exposed area or the non-exposed area is dissolved in the developer or removed, while the other remains on the aluminum plate serving as the support to form an image. exhibits ink receptivity,
Further, as described above, in the non-image area where the photosensitive resin layer is dissolved and removed, the surface of the hydrophilic aluminum support is exposed and exhibits water receptivity. Therefore, by supplying dampening water (water or aqueous liquid) to the printing plate formed by this image area, a film of dampening water is maintained on the non-image area, and on the other hand, ink is attached to the image area, and this film is kept on the non-image area. Printing is performed by repeating the process of directly or indirectly transferring the ink attached to the image area (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 an even larger number of sheets, and also for reasons such as reducing the cost of printing plates and simplifying the printing process.
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 i[lJ force is to expose and develop a planographic printing plate using aluminum as a support by the usual method described above, and then heat it at a high temperature (so-called burning). The composition forming the image area is hardened by sintering, so to speak.
An effective and commonly used method is to enhance the image portion. The heating temperature and heating time of the normal burning process are about 200 to 280[deg.] a and about 3 to 7 minutes, depending on the composition forming the image.

However, there is a demand for this burning process to last for long printing times and to be carried out in a short time.

On the other hand, the aluminum used as the support for the lithographic printing plate is AA1050. AAlloo.

An aluminum alloy such as AA5003 is formed into an ingot by normal continuous casting, hot-rolled, cold-rolled, and heat-treated in intermediate steps as necessary to form a plate or band-shaped body, and its surface is polished by mechanical methods. The surface is roughened by a chemical method, an electrochemical method, or a combination of two or more of these methods, and is further subjected to an anodic oxidation treatment.

[Problems to be solved by the invention] However, when the aluminum alloy plates conventionally used as described above are heated at a high temperature of 280°C or higher, the aluminum recrystallizes, and as a result, the strength decreases. This causes the plate to lose its stiffness, making it very difficult to handle the plate when used as a support for a lithographic printing plate, for example, making it impossible to install the plate on a printing machine. There has been a problem in that it is impossible to register the colors of the plate in the case of multicolor printing.

An object of the present invention is to provide a method for producing an aluminum alloy plate that eliminates the above-mentioned drawbacks of the prior art, impairs the excellent printing plate performance of the conventional lithographic printing plate support, and is resistant to thermal softening. It is something.

[Problem and means for solving the problem] An aluminum alloy containing 0.02 to 0.20% by weight of zirconium is made from gold for lithographic printing plates through a series of steps including hot rolling, cold rolling, intermediate annealing, and final cold rolling. In the method for manufacturing a support, intermediate annealing is performed by subtracting the electrical resistance value after heating at 380° for 6 hours and the correction value for the contribution due to work hardening from the electrical resistance value of the rolled plate after final cold rolling. A method for producing a support for a lithographic printing plate, characterized in that the method is carried out so that the value is 0.01 μΩ·am or more.

The aluminum alloy used in the present invention has a purity of 99.50% by weight or more as the base metal, and the impurities contained in the base metal are 0.40% by weight of iron or less and 0.20% by weight of silicon.
The following is desirable. The characteristic component of the aluminum alloy is zirconium, whose content is 0.0
It is 2 to 0.20% by weight. If it is less than 0.02%, the effect of some companies on heat softening 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 be non-uniform and the suitability for marking and shaving will be reduced. decreases. 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. becomes. Moreover, the content of silicon is 0.
If it exceeds 20% by weight, the effect of improving thermal softening properties due to zirconium will be reduced, so it is preferable to keep the content to 0.20% by weight or less.

Note that the aluminum alloy in the present invention is AA105
0t AAlloo Similarly, after facing the DC ingot,
A suitable plate is obtained by carrying out annealing at a temperature of 520°C or higher, followed by hot rolling at a starting temperature of 450°C or higher and a finishing temperature of 35,000°C or higher, and cold rolling at a rolling rate of 40% or higher. This cold-rolled plate is then subjected to intermediate annealing to achieve a thickness of 0.1~Q.
, and processed into a plate-like product with a thickness of 5 mm, which is used as an aluminum alloy plate for a lithographic printing plate support.

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, and it is possible to suppress the precipitation of zr, yθ, etc., and to ensure a sufficient amount of solid solution thereof.

The conditions are as follows: temperature increase 20'a/sec or more, preferably 5 CPC/sec 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. The speed is 500°C/sec or higher, preferably 1000°C/sec or higher, thereby suppressing precipitation of solid solution during intermediate annealing to improve softening resistance, and further uniform recrystallization to maintain printing characteristics.

Note that the method of directly determining the amount of solid solution is complicated and difficult to use industrially, so the present invention adopts a method of measuring the electrical resistance value as a simple method for estimating the amount of solid solution. Measure and substitute Δe, which is determined by the following formula, and in this case, it is necessary that Δe≧0.01 μm/am.

ΔP-f=-β'/'w-0.011'n-arn
βw -0,002X(UTSn-U'I'53acP
ax6i1@f"+5) However: PH: Electrical resistance value (μ, , Q-am) Po of final cold-rolled sheet
= Electrical resistance value (μΩ so cm) obtained by heating the final cold-rolled sheet for 680°016 hours p: Correction of the contribution due to work hardening IJISH: Tensile strength of the final cold-rolled sheet (K g / mm2
)"TS380'c
For example, there is an electrochemical graining method in which electricity is applied in a hydrochloric acid or nitric acid electrolyte to form a grain chamber, a wire brush graining method in which the aluminum surface is scratched with a metal wire, and an aluminum surface is grained in a polishing ball and JIIFJ. Mechanical graining methods can be used, such as the boulderaine method in which the surface is grained using a nylon brush and an abrasive; They can also 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,
Using sodium phosphate, potassium hydroxide, lithium hydroxide, etc., the preferred concentration and temperature ranges are 1 to 50% by weight and 20 to 100°a, respectively, and the amount of dissolved A/ is 5 to 20%.
Conditions such that the ratio is g/male are preferable.

After alkaline etching, acid washing is performed to remove the dirt (smut) remaining on the surface.

The acids used include nitric acid, sulfuric acid, phosphoric acid, chromic acid, hydrofluoric acid, and the like.

In addition, for the smut removal treatment after the electrochemical surface roughening treatment, preferably contact with 15 to 65% by weight sulfuric acid at a temperature of 50 to 9 CFa as described in JP-A-53-12739. Method of making and Special Publication No. 48-28123
This is the alkali etching method described in the publication.

The aluminum plate treated as described above can be used as a support for a lithographic 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. Specifically, sulfuric acid, phosphoric acid,
When a direct or alternating current is passed through aluminum in an aqueous or non-aqueous solution containing chromic acid, oxalic acid, sulfamic acid, benzenesulfonic acid, etc. or a combination of two or more of these, a polar oxide film is formed on the surface of the aluminum support. I can do it.

The processing conditions for anodic oxidation vary depending on the electrolyte used and cannot be determined unconditionally, but generally the electrolyte concentration is 1 to 80% by weight, the solution temperature is 5 to 70°a, the current density is 0. .5~607>Hair/dnl”.

A suitable range is a voltage of 1 to 1oov and an electrolysis time of 10 to 100 seconds.

Among these anodic oxidation coating treatments, the British Patent No. 1
, 412,768 and the method of anodizing phosphoric acid at high current density in sulfuric acid and electrolytic phosphoric acid as described in U.S. Pat. No. 3,511,661. A method of anodizing as a bath is preferred.

Anodized aluminum plates are further described in U.S. Patent No. 2.
As described in U.S. Pat. A subbing layer of a water-soluble gold base (such as carboxymethylcellulose) may also be provided as described in 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. No. 2,063,631 and U.S. Pat.
The diazo resins described in JP 45322, JP 49-45323, British Patent No. 1.312,925, etc. are preferred, and the binder is the one described in British Patent No. 1.3.
No. 50,521, No. 1,460,978 and U.S. Patent No. 4,123,276, No. 3.751,2
The binders described in No. 57 and No. 3,660,097 are preferred. '■ Photosensitive layer made of 0-quinonediazide compound Particularly preferred 0-quinonediazide compound is 〇-, naphthoquinonediazide compound,
For example, U.S. Patent Nos. 2,766,118 and 2,76
No. 7,092, No. 2,772,972, No. 2,8
No. 59,112, No. 2,907.665, No. 3,
No. 046,110, No. 3.04.15,111, No. 3.04 t! S, No. 115, same No. 3,046,11
No. 8, No. 3,046,119, No. 3,046,1
No. 20, No. 3,046,121, No. 3,046,
No. 122, No. 3,046,123, No. 3,061
, No. 43.0, No. 3,102,809, No. 3,1
No. 06,465, No. 5,655,709, No. 3,
It is described in numerous publications including the specifications of No. 647,443, and these can be used suitably.

■ Azide compound and binder (photosensitive layer consisting of a polymer compound) For example, British Patent No. 1,235.281, British Patent No. 1.4
Specifications of No. 95.861 and JP-A-51-32!13
In addition to the compositions comprising an azide compound and a water-soluble or alkali-soluble polymer compound described in Japanese Patent Application Laid-open Nos. 50-5102, 50-84302, and 50-50, -84303, 53-
12984, etc., compositions consisting of a polymer containing an azide group and a polymer compound as a binder are included.

■ Other photosensitive resin layers, such as polyester compounds disclosed in JP-A-52-96696, British Patent No. 1.112,27
No. 7, No. 1,313,390, No. 1,! 141,
Polyvinyl cinnamate resins described in specifications such as No. 004 and No. 1,377,747, U.S. Patent No. 4,0
The photopolymerizable photopolymers described in the specifications of No. 72,528 and No. 4,072,527 and the like are included.

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.

As the coating method, there are various 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 amount of application is 1 to 7.
About 0g/7, preferably 0.5 to 4.0g/m2
There is a range of degrees. After coating, it is dried by a known conventional method and, if necessary, cut into a suitable size.

The printing plate (original 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 sprayed with a developer. Examples of these methods are described in the literature for each composition, so they can be used as a developer in accordance with each composition as appropriate.

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, and a positive type composition or negative type composition is selected as appropriate depending on the printing purpose or work content. There is a need. 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-51-1400
No. 1, Special Publication No. 55-28062, Special Publication No. 57-5
No. 938 and U.S. Pat. No. 4,191,570 Fi
AI! Although described in IT books and the like, burning basically involves placing a developed printing plate in an atmosphere at a temperature of 1500 to 650°C to sinter and harden the image portion of the plate surface.

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 temperature as well as the processing time, and if the processing time is about 3 to 10 minutes, it will be 180 to 600°.
It can be carried out at a temperature of 0.

The aluminum alloy support produced according to the present invention can sufficiently withstand such burning treatment, maintain its original physical properties, and achieve extremely high printing durability, especially as a support for lithographic printing plates. be.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that % indicates weight % unless otherwise specified.

Example 1 Table 1 shows four types of aluminum DO ingots (5som
Thickness) After applying homogenization treatment for 560'016 hours, hot rolling and cold EM to a thickness of 1
．． 5 mm, and then subjected to intermediate annealing by raising the temperature to 100°C/hour in the batch method, holding at 400°C for 1 hour, and letting it cool naturally, or magnetic induction heating (in the case of the continuous method).
Tran-verseFlux engineering
n Heating) at 150°C/sec;
Intermediate annealing was carried out by holding at 450° for 0.5 seconds and cooling with water at 500°0/second or more, and in both cases, a final cold rolling was carried out at σ1 to a thickness of 0.6 mII+. Table 1 shows the chemical compositions of aluminum alloys A, B, and Old for offset printing plates.

Table 1 Next, these aluminum alloy rolled plates were grained using a rotating nylon brush in a suspension of pumice stone and water, and then the dissolved amount of aluminum was determined to be 5 g/m2 using a 20% aqueous solution of caustic soda. I etched it to make it look like this.

After thoroughly washing with running water, pickling with 25% nitric acid aqueous solution,
The substrate was prepared by washing with water. The substrate prepared in this way was heated at a current density of 20% in an electrolytic bath containing 0.5 to 2.5% nitric acid as described in Japanese Patent Application Laid-open No. 146234/1983.
AC electrolysis was performed at A/ay2 or more. Subsequently, the surface was cleaned by immersion in a 50°C aqueous solution of 15% sulfuric acid for 6 minutes, and then immersed in an electrolytic solution containing 20% sulfuric acid as a main component at a bath temperature of 30°C.
An oxide film of 3 g/arn2 was formed with 'O.

The following photosensitive layer was provided on the sample prepared in this manner so that the dry coating amount was 2.5 g/m2.

The thus obtained photosensitive lithographic printing plate was placed in close contact with the transparent positive image and was exposed to a PS light from a distance of 1 m, equipped with a Toshiba metal halide lamp MU2000-2-Oll type 3KW light source,
[Sold by Fuji Photo Film Co., Ltd.]6
After exposure for 0 seconds, 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, to prevent stains caused by the burning process,
Soak a sponge with a 4% by weight aqueous solution of potassium borate,
It was 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°0.2 in a 1300 Burning Processor [equipped with a 12 KW heat source and sold by Fuji Photo Film Co., Ltd.].
80°0.300°0.320°07 at each temperature
Heated for minutes.

After cooling, the 0 and 2% proof stress values of the printing plate which had been burnt to 26,000 to 620°C were measured by a tensile test.

As a result, △y (3 from the electrical resistance value of the rolled plate after final cold rolling) of each of the above aluminium rolled plates used as a support.
The electrical resistance after heating for 800,096 hours and the correction value of the contribution due to work hardening are subtracted (μm1-arn) and are shown in Table 2.

In addition, each electric resistance value was measured by the volume resistivity and conductivity measurement method of J-K5HO505r non-ferrous metals. ' Table 2 △P (μcm/cm) As above, aluminum alloys, A, B, o.

In the case of rolling D, when intermediate annealing is carried out by a batch method in the example, △ is smaller than the range of the present invention, and when a continuous method is used, both are 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.

Further, when these printing plates were attached to an offset printing machine KOH and printed, good printed matter was obtained without staining in non-image areas or dotted stains.

Table 3 shows the printing durability at that time.

Table 3 [Effects of the invention] As described above, according to the present invention, the heat softening property is low,
It is possible to obtain a support for a lithographic printing plate that can provide a printing plate that has high heat resistance and exhibits good printability.

Claims (1)

[Claims] (1) A method for manufacturing 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 intermediate annealing, the value obtained by subtracting the electrical resistance value after heating at 380°C for 6 hours and the correction value for the contribution due to work hardening from the electrical resistance value of the rolled plate after final cold rolling is 0.01 μΩ・cm. A method for producing a support for a lithographic printing plate, which is characterized in that the method is carried out as described above.