JP3414521B2 - Method for producing a lithographic printing plate support - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lithographic printing plate support, and more particularly to a method for producing an aluminum support having a good electrolytic graining property.

[0002]

2. Description of the Related Art Aluminum plates (including aluminum alloy plates) are used as aluminum supports for printing plates, especially as supports for offset printing plates. Generally, in order to use an aluminum plate as a support for an offset printing plate, it is necessary to have appropriate adhesiveness to a photosensitive material and water retention.

For this purpose, the surface of the aluminum plate must be roughened so as to have a uniform and fine grain. This roughening treatment has a significant influence on the printing performance and printing durability of the plate material when offset printing is actually carried out after plate making, and therefore its quality is an important factor in the plate material production. As a roughening method of the aluminum support for printing plates, AC electrolytic etching method is generally adopted,
As the current, a normal sine wave alternating current or a special alternating waveform current such as a rectangular wave is used. Then, the surface of the aluminum plate is roughened by an alternating current using an appropriate electrode such as graphite as a counter electrode, which is usually performed in a single treatment, but the pit depth obtained there is generally shallow. The printing durability was inferior. Therefore, various methods have been proposed in order to obtain an aluminum plate suitable as a printing plate support having a grain in which pits having a depth deeper than its diameter are present uniformly and densely. As a method thereof, a surface roughening method using a special electrolysis power source waveform (Japanese Patent Laid-Open No. Sho 5)
3-67507), the ratio of the amount of electricity at the time of anode and cathode at the time of electrolytic surface roughening using an alternating current (Japanese Patent Laid-Open No. 6560/54).
No. 7), a power supply waveform (JP-A-55-25381), and an energization amount per unit area (JP-A-56).
No. 29699) is known.

Further, a method combined with mechanical surface roughening (Japanese Patent Application Laid-Open No. 55-142695) is also known. On the other hand, as a method of manufacturing an aluminum support, an aluminum ingot is melted and held to form a slab (thickness: 4 mm).
00-600mm, width 1000-2000mm, length 2
000 to 6000 mm) and subjected to a chamfering step of cutting the impurity textured portion of the slab surface with a chamfering machine into 3 to 10 mm increments, and then in a soaking furnace for removing stress inside the slab and homogenizing the texture A soaking treatment step of holding at 480 to 540 ° C for 6 to 12 hours is performed, and then hot rolling is performed at 480 to 540 ° C. After hot rolling to a thickness of 5 to 40 mm, cold rolling is performed to a predetermined thickness at room temperature. Further, after that, annealing is performed to homogenize the structure to homogenize the rolled structure and the like, and then cold rolling is performed to a prescribed thickness to correct the plate so as to have a good flatness. The aluminum support thus prepared was used as a support for a lithographic printing plate.

However, in the case of electrolytic surface-roughening treatment, it is particularly susceptible to the influence of the aluminum support as a target,
When manufacturing the aluminum support through the process of melting and holding → casting → chamfering → soaking, heating and cooling are repeated,
Even if there is a step of scraping off the surface layer called surface grinding, variations in metal alloy components and the like occur in the surface layer, which causes a reduction in the yield as a lithographic printing plate.

On the other hand, the applicant of the present invention first reduced the variation in the material of the aluminum support and improved the yield of the electrolytic surface roughening treatment to obtain a lithographic printing plate of excellent quality and good yield. As a method that can be made, after casting from an aluminum melt and hot rolling continuously to form a thin plate hot rolling coil, cold rolling, heat treatment, straightening the aluminum support to roughen it A method for producing a support for a lithographic printing plate characterized by the following is proposed (JP-A-3-79).
798 publication).

[0007]

However, the manufacturing method previously proposed by the present applicant in Japanese Patent Laid-Open No. 3-79798 is also shown in FIG. 2 when continuous casting and rolling is performed from molten aluminum using twin rolls. As described above, on the surface of the aluminum plate (hereinafter referred to as a base plate) 7 after continuous casting and rolling,
There was a problem that stepwise unevenness 8 (see enlarged portion 9) extending in a direction perpendicular to the rolling direction, that is, in the width direction of the base plate 7 was generated. This step-like unevenness 8 causes a problem that it remains as wavy unevenness on the surface of the planographic printing plate that has been subjected to the roughening treatment thereafter.

An object of the present invention is to reduce the occurrence of stepwise unevenness that occurs during twin roll continuous casting and rolling, and to provide a lithographic printing plate support excellent in surface quality after roughening by a twin roll continuous casting and rolling method. An object of the present invention is to provide a method for producing a lithographic printing plate support which can be stably produced by using the support.

[0009]

[Means and Actions for Solving the Problems]
As a result of diligent research on the stepwise unevenness that occurs during continuous casting and rolling, the plate thickness in the cold rolling step and the treatment temperature in the subsequent intermediate annealing step are regulated within a predetermined range, thereby providing a support for a lithographic printing plate without wavy unevenness. It was found that the above was obtained, and the present invention was completed.

That is, the above object of the present invention is to continuously cast and roll an aluminum melt directly into a plate shape with twin rolls, then cold-roll and intermediate-anneal it, and further roll it to a final plate thickness and straighten it. In a method for producing a lithographic printing plate support comprising a series of steps for roughening, a plate obtained by continuous casting and rolling is cold rolled to obtain a plate thickness of 2 after continuous casting and rolling.
~ 8 % thickness, then 10 at 450 ~ 600 ℃
A method for producing a lithographic printing plate support characterized by performing intermediate annealing for 10 minutes to 10 hours, and then rolling to a final plate thickness, and a temperature rising rate during intermediate annealing of 10 ° C./sec or less. And a method for producing a lithographic printing plate support according to the above paragraph.

In the present invention, as a method for forming a coil continuously cast from molten aluminum by using twin rolls, a thin plate continuous casting technique such as Hunter method or 3C method has been put into practical use. According to these methods, the molten aluminum can be solidified and rolled at the same time, and a base plate having a thickness of 2 to 10 mm can usually be manufactured. The present invention, in order to obtain excellent properties as a lithographic printing plate support, a base plate obtained by continuous casting and rolling from a molten aluminum, the plate thickness of the base plate in the cold rolling step after the continuous casting and rolling. 2 to 8 %, preferably 3 to 8%, more preferably 4 to 7%
%.

Then, in the intermediate annealing step,
The treatment temperature is 600 ° C., preferably 460 to 550 ° C., more preferably 470 to 520 ° C. In particular, in this intermediate annealing step, the temperature rising rate is 10 ° C./sec or less, preferably 5 ° C./sec or less, more preferably 2 to 0.5.
It is desirable to raise the temperature gently at ° C / sec. It was found that the above-mentioned wavy unevenness was caused by uneven distribution of crystal grains and alloy components inside the support. By regulating the plate thickness during cold rolling and the processing temperature and temperature rising rate during intermediate annealing as in the present invention, the distribution of the crystal grains and alloy components is made uniform and the occurrence of wavy unevenness is suppressed. Is.

Then, the final plate thickness is rolled by finish rolling, further straightened for flattening, and then roughened to obtain a support for a lithographic printing plate. Next, FIG.
Embodiments of the method for producing a lithographic printing plate support used in the present invention will be described more specifically with reference to the process schematic diagrams of (A) to (D). Reference numeral 1 is a melting and holding furnace, in which the ingot is held by melting. From here, it is sent to the twin roll continuous casting machine 2. In other words, a coil of thin plate may be formed directly from the molten aluminum, and may be wound by the coiler 6.
It may be subsequently subjected to heat treatment, a cold rolling mill, and a straightening device.

The manufacturing conditions will be described in more detail. In the melting and holding furnace 1, it is necessary to keep the temperature at the melting point of aluminum or higher, and the temperature changes depending on the aluminum alloy component. Generally, it is 800 ° C or higher. Further, as a measure for suppressing the generation of oxides in the molten aluminum and removing the alkali metal that is harmful to the quality, an inert gas purge, a flux treatment, etc. are appropriately performed.

Subsequently, it is cast by the twin roll continuous casting machine 2. There are various casting methods, but most of them currently in industrial use are the Hunter method, the 3C method, and the like.
The casting temperature varies depending on the cooling conditions of the mold, but the optimum temperature is around 700 ° C. The crystal grain size after continuous casting, cooling conditions, casting speed, and plate thickness change during casting are controlled. The original plate obtained as described above is rolled by the cold rolling mill 3 so as to have a prescribed plate thickness described above, that is, a thickness of 2 to 8 % of the plate thickness after continuous casting and rolling.

Thereafter, the heat treatment machine 4 performs intermediate annealing. In this intermediate annealing, the cold rolled and coiled base plate is placed in a heating furnace, and the temperature is gradually raised at a prescribed temperature rising rate of 10 ° C./sec or less to obtain a prescribed processing temperature. Hold at 450 to 600 ° C. for a predetermined time. The annealed base plate is again cold rolled by the cold rolling mill 3
Is rolled to the final plate thickness. The plate thickness at this time is usually 0.
It is about 1 to 1 mm, and is appropriately rolled depending on the design.

Then, straightening is performed by the straightening device 5,
A support for a lithographic printing plate is provided with a predetermined flatness, and the support is roughened. Further, straightening may be included in the final cold rolling. Various methods such as mechanical surface roughening, chemical surface roughening, electrochemical surface roughening, and combinations thereof may be used as the method of surface roughening the lithographic printing plate support of the invention.

Mechanical graining methods include, for example, a ball grain method, a wire grain method, a brass grain method and a liquid honing method. An alternating current electrolytic etching method is generally adopted as the electrochemical graining method, and a special alternating current such as an ordinary sinusoidal alternating current or a rectangular wave is used as the current. Further, as a pretreatment for this electrochemical graining, etching treatment with caustic soda may be performed.

In the case of performing electrochemical surface roughening, it is preferable that the surface is roughened by an alternating waveform current with an aqueous solution mainly containing hydrochloric acid or nitric acid. The details will be described below. The support is first alkali etched. Preferred alkaline agents are caustic soda, caustic potash, sodium metasilicate, sodium carbonate, sodium aluminate, sodium gluconate and the like. Concentration 0.0
1 to 20%, temperature is 20 to 90 ° C, time is 5 sec to 5
It is suitable to be selected from the range of min, and the preferable etching amount is 0.1 to 5 g / m ² .

Particularly in the case of a support containing a large amount of impurities, 0.01
-1 g / m ² is suitable (JP-A-1-237197). Subsequently, a substance (smut) which is insoluble in the alkaline agent remains on the surface of the support which has been subjected to the alkali etching, and therefore a desmut treatment may be performed if necessary. The pretreatment is as described above, but is subsequently subjected to AC electrolytic etching in an electrolytic solution containing hydrochloric acid or nitric acid as a main component. The frequency of the alternating electrolysis current is 0.1 to 100 Hz, more preferably 0.1 to 1.0 or 10 to 60 Hz.

The liquid concentration is 3 to 150 g / l, more preferably 5 to 50 g / l, and the amount of aluminum dissolved in the bath is preferably 50 g / l or less, more preferably 2 to 20 g / l. is there. If necessary, additives may be added, but in the case of mass production, it becomes difficult to control the liquid concentration. A current density of 5 to 100 A / dm ² is suitable, but 10 to 80 A / dm ² is more preferable.
Further, the power source waveform is appropriately selected depending on the desired quality and the components of the support to be used.
It is more preferable to use the special alternating waveforms described in JP-B No. 280 and JP-B-55-19191. Waveform like this,
The liquid conditions are appropriately selected depending on the quality required along with the quantity of electricity, the components of the support used, and the like.

The electrolytically roughened support is then immersed in an alkaline solution as part of the smut treatment to dissolve the smut. There are various alkali agents such as caustic soda, but pH 10 or higher, temperature 25 to 60 ° C., immersion time 1 to 1
It is preferable to perform it in an extremely short time of 0 sec. Next, it is dipped in a liquid containing mainly sulfuric acid. As the liquid condition of sulfuric acid, the concentration is 50 to 400 g / l, the temperature is 25 to 65, which is much lower than the conventional one.
C is preferred. When the concentration of sulfuric acid is 400 g / l or more or the temperature is 65 ° C. or more, the corrosion of the treatment tank and the like becomes large, and the support containing a large amount of manganese (for example, 0.3% by weight) electrochemically The roughened grain will collapse. In addition, the amount of the base material dissolved is 0.2 g / m
^If it is etched by ² or more, the printing durability will decrease, so it is preferably 0.2 g / m ² or less.

The anodic oxide film has a thickness of 0.1 to 10 g / m ² ,
More preferably, 0.3 to 5 g / m ² is formed on the surface. The treatment conditions for anodization are not generally determined because they vary depending on the electrolytic solution used, but generally the concentration of the electrolytic solution is 1 to 80% by weight, the liquid temperature is 5 to 70 ° C,
Current density 0.5 to 60 A / cm ² , voltage 1 to 100 V,
A range of electrolysis time of 1 second to 5 minutes is suitable.

Since the grain-like support having the anodized film thus obtained is stable and excellent in hydrophilicity, it is possible to immediately form a photosensitive coating film on it.
If necessary, further surface treatment can be performed. For example,
A silicate layer made of an alkali metal silicate or an undercoat layer made of a hydrophilic polymer compound can be provided.
The coating amount of the undercoat layer is preferably 5 to 150 mg / m ² .

Next, a photosensitive coating film is provided on the support thus treated, imagewise exposed and developed to form a plate, which is then set in a printing machine to start printing.

[0026]

Examples (Examples 1 to 3 , Comparative Examples 1 and 2) A twin roll continuous casting and rolling apparatus as shown in FIG. 1 (A) was used to cast a base plate having a plate thickness shown in Table 1. It was wound up with a coiler 6. The aluminum material filled in the melting and holding furnace 1 was Fe: 0.35, Si: 0.12, Cu: 0.0.
1, Ti: 0.03 (unit: wt%), balance Al was prepared using an aluminum ingot and a mother alloy.

After that, the cold rolling mill 3 shown in FIG. 1 (B) was used to obtain each plate thickness, and then the heat treatment machine 4 shown in FIG. 1 (C) was used to perform intermediate annealing under each heating condition. Next, each of the samples of Examples and Comparative Examples was produced by the cold rolling mill 3 shown in FIG. 1 (B) to each final plate thickness and further straightening by the straightening device 5 shown in FIG. 1 (D).

[0028]

[Table 1]

Further, the sample thus produced was used as a support for a lithographic printing plate, and then etched with a 5% aqueous solution of caustic soda at a temperature of 60 ° C. to an etching amount of 5 g / m ² , and washed with water to give 150 g. It was immersed in a sulfuric acid solution of 1 / l, 50 ° C. for 20 seconds to desmut, and washed with water. Furthermore,
In a 16 g / l nitric acid aqueous solution, Japanese Examined Patent Publication No. 55-19191
The surface was electrochemically roughened using an alternating waveform current described in Japanese Patent Publication No. As the electrolysis conditions, the anode voltage V _A = 14
V and cathode voltage V _C = 12 V, and the amount of electricity at the anode was set to 350 coulomb / dm ² .

Subsequently, desmut treatment was carried out by immersing in a sulfuric acid solution of 300 g / l at 60 ° C. for 20 seconds. Furthermore,
Sulfuric acid 150g / l, aluminum ion concentration 2.5g /
Voltage of 22V in 1mm aqueous solution at distance between electrodes of 150mm
Anodizing treatment was carried out for 60 seconds with the direct current.

A photosensitive lithographic printing plate is obtained by applying a photosensitive solution to the support prepared as described above. Here, the surface quality of the support before the application of the photosensitive solution was evaluated.
When the photosensitive lithographic printing plate is exposed through a negative film or a positive film and then developed, the surface of the support itself becomes a non-image part or an image part of the lithographic printing plate. This is because the surface quality of the surface of the support before applying the photosensitive solution has a great influence on the printability and the visibility of the printing plate.

The results of the appearance evaluation of the wavy unevenness after roughening the samples shown in Table 1 are also shown in Table 1. As shown in Table 1, the samples (Examples 1 to 3 ) according to the present invention had a good appearance after roughening. On the other hand, wavy unevenness was confirmed in the samples (Comparative Examples 1 and 2) not according to the present invention.

[0033]

INDUSTRIAL APPLICABILITY As described above, the lithographic printing plate produced by the method for producing a lithographic printing plate support of the present invention has no wavy unevenness and is excellent in appearance as compared with the conventional ones, The surface quality after surface treatment is significantly improved. Further, since the twin roll continuous casting method can be adopted, the manufacturing process is greatly streamlined, and the effect of reducing the manufacturing cost becomes large.

[Brief description of drawings]

FIG. 1 is a partial step of a method for producing a lithographic printing plate support of the present invention. (A) A side view of one embodiment of a twin roll continuous casting process. (B) The side view of one embodiment of the cold rolling process. (C) A side view of one embodiment of the heat treatment step. (D) The side view of one embodiment of the correction process.

FIG. 2 is a conceptual diagram illustrating stepwise unevenness of a base plate and wavy unevenness of a lithographic printing plate support.

[Explanation of symbols]

1 Melt-holding furnace 2 twin roll continuous casting machine 3 cold rolling mill 4 heat treatment machine 5 Straightening device 6 coiler 7 original plate 8 stepped uneven part 9 Enlarged part

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C22F 1/00 681 C22F 1/00 681 684 684C 691 691A 691B 691C 694 694A (72) Inventor Kakei Shizuoka Prefecture Yoshida-cho 4000 Kawajiri Fuji Photo Film Co., Ltd. (72) Inventor Akio Uesugi 4000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji Photo Film Co., Ltd. (56) Reference JP-A-5-156414 (JP, A) JP-A-6-220593 (JP, A) JP-A-6-210308 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41N 1/08 C22F 1/04 -1/057 B22D 11/06 B21B 1 / 46

Claims (2)

(57) [Claims] 1. A molten aluminum melt is continuously cast and rolled into a plate shape by twin rolls, followed by cold rolling and intermediate annealing,
Further, in a method for producing a lithographic printing plate support comprising a series of steps of roughening after rolling to a final plate thickness and straightening, a plate obtained by continuous casting and rolling is continuously cast by cold rolling. After making the thickness 2 to 8 % of the plate thickness after rolling, 4
A method for producing a lithographic printing plate support, which comprises performing intermediate annealing at a temperature of 50 to 600 ° C. for 10 minutes to 10 hours and further rolling to a final plate thickness. 2. The temperature rising rate during the intermediate annealing is 10 ° C. /
The method for producing a support for a lithographic printing plate according to claim 1, wherein the time is not more than sec.