JPH027838B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a support for a lithographic printing plate having excellent strength. Conventionally, aluminum plates have been mainly used as supports for image-receiving layers (photoconductive layers, photosensitive layers, thermosensitive layers, etc.) of planographic printing original plates, but aluminum plates with a thickness of 0.3 mm or more are recommended for strength reasons. I needed to use something. However, even if an aluminum plate of such thickness is used as a support, since the aluminum plate itself is soft, deformation and uneven damage occur during handling during plate making and printing, making it difficult to use repeatedly. There was a problem that the ratio was extremely low and printing costs were high. The present invention provides a method for manufacturing a support for a lithographic printing original plate that solves this problem. Conventionally, an aluminum plate has been generally used as a support for the image-receiving layer, but the portion that requires aluminum as a support is the surface layer with a thickness of several microns. In other words, the surface layer of several micrometers needs to have the same softness and chemical properties as aluminum because it is grained and alumite treated to improve the adhesion of the image-receiving layer and the hydrophilicity of non-image areas. Such properties are not required inside the body. Therefore, the inventors of the present invention conducted various studies on supports reinforced with metal cores, and as a result, they were able to achieve their desired objective by using a hot-dip aluminum plated steel plate as the support. In a molten aluminum plated steel sheet, the plating layer 1 is composed of an alloy layer 3 in contact with the steel sheet 2 and an aluminum layer 4 located on the alloy layer 3, as shown in FIG. The surface aluminum layer 4 has the same properties as aluminum, and its thickness is such that it can be subjected to graining and alumite treatment, and is no different from conventional aluminum plates. Therefore, when this steel plate is used as a support, it exhibits much greater strength than an aluminum plate due to the presence of the steel plate as a core metal, and can be used repeatedly as long as there is no abnormal handling during plate making and printing. Further, since the aluminum layer wears out by repeated use by 1 to 2 microns per use, this level of wear can be counteracted by increasing the plating thickness. The aluminum layer of this support does not require a particular aluminum purity, and may have the purity of an aluminum layer obtained by plating in a conventionally commonly used molten aluminum bath. Like a plated steel plate Si
It has been confirmed through experiments that there is no problem even if the material contains 1 to 10% of 1 to 10%, and even if it contains other elements that are inevitably mixed in due to glare. However, the thickness of the aluminum layer needs to be 7μ or more. This is because the support is usually subjected to graining to improve the adhesion of the image-receiving layer and the hydrophilicity of the non-image area after printing, and if the support is too thin, the effects of these treatments will be reduced. The alloy layer in the plating layer is usually Al-Fe or Al-
It is Fe-Si or a mixture of both, and generally has poor workability. For this reason, in the case of a support that is subjected to a bending process or the like when attached to a plate cylinder after plate making, it is preferable that the alloy layer be as thin as possible. Normally, in the case of hot-dip aluminum plated steel plate supports, it is difficult to use them in the plated state due to quality reasons, and cold rolling with a total reduction rate of 30 to 85% is required after plating. In order to withstand repeated bending, the maximum thickness of the alloy layer after rolling in the above rolling reduction range is 5μ. Further, during hot-dip galvanizing, the formation of a normal alloy layer is unavoidable, and it is extremely difficult to reduce the thickness to less than 0.2 μm even when rolled within the above-mentioned rolling reduction range in relation to the work hardening of the steel sheet. From these points, the thickness of the alloy layer of the support is preferably in the range of 0.2 to 5 μm. Since the support of the molten aluminum plated steel plate has a steel plate having higher strength than the aluminum plate as the core metal, its thickness can be made thinner than the conventional aluminum plate, and can be made as thin as 0.25 mm or even 0.15 mm. Therefore, the bending process when attaching to the plate cylinder during printing becomes easy, and there is an advantage that printing costs can be reduced. A support for a molten aluminum plated steel plate can be produced by pre-treating a cold rolled steel plate, plating it in a molten aluminum plating bath, and then cold rolling. As is well known, hot-dip aluminum-plated steel sheets are manufactured in two ways: weather-resistant ones by plating in a bath containing industrially pure aluminum;
Heat resistant by plating in an aluminum bath containing 10%
There are two methods for manufacturing products for processing, and the latter method is used in the present invention. In other words, when manufactured by the former method, the alloy layer in the plating layer develops significantly, and the workability of the plating layer cannot withstand repeated bending. The case of manufacturing according to the latter method will be explained below based on FIG. 2. FIG. 2 is a schematic diagram of a Sendzimer type continuous molten aluminum plating apparatus, in which a cold rolled steel plate 2a, which is a plating original plate, is set on a payoff reel 5. This cold rolled steel plate 2a
An unannealed material is usually used for this purpose, but an annealed material is used when an in-line annealing furnace is not provided, such as in a flux type continuous melting and gluing device. The cold-rolled steel plate 2a is annealed from the payoff reel 5, subjected to annealing and pretreatment (reduction treatment) in the reduction furnace 6, and then immersed in a molten aluminum bath 7 and pulled up vertically through a sink roll 8, and then transferred to the molten aluminum bath. The thickness of the plating layer is adjusted by wiping with a pair of gas throttle nozzles 9 placed directly above the plating layer. In this case, the thickness of the plating layer on one side is as follows:
20-60μ, preferably 30-50μ. In the present invention, a bath containing 1 to 10% Si is used as the molten aluminum bath 7. This is because when the Si content is less than 1%, the effect of suppressing the alloy layer due to Si is small, and the alloy layer thickness is 60% of the entire plating layer.
This is because unless the aluminum layer reaches a thickness of ~70% and the plating is about 60μ, it will not be possible to secure the thickness of the aluminum layer that is the objective of the present invention. In addition, when the alloy layer becomes thick like this, protrusions protruding from the surface side of the alloy layer appear on the surface due to the cold rolling process for the purpose of crimping pinholes, which will be performed later, and this will cause pinholes etc. to appear in the image receiving layer. This is because it may cause defects. On the other hand, the effect of suppressing the alloy layer of Si increases as the amount of Si added increases, but if it exceeds 10%, it approaches the eutectic point and causes various damage in terms of quality and work, so it is not generally used. After being plated as described above, it is cooled and wound onto a tension reel 10 to form a molten aluminum plated steel sheet 11. However, as shown in Fig. 3, the molten aluminum plated steel sheet manufactured in this manner has concavities 12 of spangled grain boundaries on the surface and pinholes 13 in the plating layer, and immediately lithographic printing is performed. It cannot be used as a support for original plates. That is, even if an image-receiving layer is formed on the above-mentioned steel sheet, the image-receiving layer will also have dents and pinholes at the spangle grain boundaries, making it impossible to use the image-receiving layer as a support that requires a smooth surface. Therefore, in the present invention, in order to solve this problem, the molten aluminum plated steel sheet is subjected to cold rolling at a total reduction rate of 30 to 85% to crimp the pinholes and smooth out the depressions at the spangle grain boundaries. It is. The number of pinholes that occur in the plating layer is generally relatively small when the plating layer is thicker than 60μ due to the bridge effect, but as the plating layer becomes thinner, the number of pinholes generated increases. do. In order to compress these pinholes by causing plastic deformation in the plating layer by rolling, complete compression cannot be achieved with a total rolling reduction of 20 to 25%, and a rolling reduction of at least 30% is required. On the other hand, if the total rolling reduction exceeds 85%, work hardening will be excessive, making it difficult to bend the plate when attaching it to the plate cylinder. Generally, when a molten aluminum steel sheet is subjected to cold rolling, the steel sheet and the plated layer are rolled in proportion, but in the present invention, the aluminum layer of the single-sided plated layer is made to have a thickness of 7μ or more after rolling. The preferred total rolling reduction rate in the present invention is 50 to 70%
It is. When rolled at this rolling reduction ratio, the surface of the plating layer is smoothed, pinholes are crimped, and the steel plate is suitably work hardened to exhibit excellent strength as a support. Example A cold-rolled steel plate with a thickness of 0.5 mm and a width of 914 mm was plated in a molten aluminum bath containing 8% Si, and the plating thickness on one side was adjusted to 43 μm. Post-plating reduction rate 60
% cold rolled to produce a support with a thickness of 0.2 mm,
The sample number of the support was designated as No.1. On the other hand, a cold-rolled steel plate with a thickness of 0.3 mm and a width of 914 mm was plated in a molten aluminum bath containing 9% Si, and the plating thickness on one side was adjusted to 31 μm. After plating, cold rolling was performed at a reduction rate of 50% to produce a support with a thickness of 0.15 mm, and the sample number of the support was designated as No. 2. Table 1 shows the surface roughness Hmax of these supports.
The results measured according to JIS B 0651 are shown.

[Table] Table 2 also shows the thickness of the single-sided plated layer of each of the supports and its changes.

[Table] Next, check the presence or absence of pinholes in the aluminum layer.
Table 3 shows the results of investigation using the feroxyl test method specified in JIS H 8672-1969. Five test pieces of 100 x 100 mm were prepared for each support, and the number of pinholes generated in each test piece was investigated.

[Table] Each of the supports described above was grained in accordance with a conventional method, and then a photocurable resin was applied to form an image-receiving layer to produce a lithographic printing original plate. When this original plate was made into a plate and subjected to a printing test using a lithographic printing machine, no abnormalities due to concavities or pinholes at the spangle grain boundaries appeared, and the printing was otherwise good with no unevenness. As is clear from this example, the cold rolled steel plate is
If plated in a molten aluminum bath with a content of 8 to 9%, the alloy layer can be suppressed to 4 to 7μ or less, and if cold rolled with a reduction rate of 50 to 70% after plating, the alloy layer will be It can be made less than 5μ. In addition, if the thickness of the aluminum layer after plating is 27 to 36μ, the thickness of the aluminum layer after cold rolling can be maintained at 13 to 17μ, and the alloy layer is not exposed to the surface layer and has a thickness that can be used repeatedly. be. Moreover, the surface is smoothed by cold rolling, and pinholes are also compressed, resulting in a suitable base material for forming an image-receiving layer. As described above, the support according to the present invention has a surface layer made of an aluminum layer that can be subjected to graining and plate-making, and has a steel plate core inside, so it has high strength and is resistant to deformation and damage like conventional aluminum plates. It is considered that it can be used repeatedly as it does not cause any flaws. In addition, the obtained support is easy to bend, does not peel off the plating layer by bending due to repeated use, and has a smooth surface without pinholes 1, making it excellent as an image-receiving layer support. It has a hard surface.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a hot-dip aluminum plated steel plate which is a support manufactured by the method of the present invention. FIG. 2 is a schematic diagram of a continuous molten aluminum plating apparatus. FIG. 3 is a cross-sectional view of a hot-dip aluminum plated steel sheet having pinholes and spangled grain boundary depressions. 1... Plated layer, 2... Steel plate, 2a... Cold rolled steel plate, 3... Alloy layer, 4... Aluminum layer,
5... Payoff reel, 6... Annealing, reduction furnace, 7
...molten aluminum bath, 8... sink roll,
9... Gas throttle nozzle, 10... Tension reel, 11... Molten aluminum plated steel, 12...
...Concavities in spangled grain boundaries, 13...Pinholes.

Claims (1)

[Claims] 1 After pre-treating the cold rolled steel plate, Si is added to 1~
A molten aluminum plated steel plate is produced by plating in a molten aluminum bath containing 10%,
Next, the plated steel plate is subjected to cold working at a total reduction rate of 30 to 85%, in order to compress pinholes on the surface of the plated layer and smooth the surface, and to make the thickness of the cold rolled steel plate 0.15 to 0.25 mm. In addition, the thickness of the alloy layer and aluminum layer of the single-sided plating layer was 0.2
A method for producing a support for a printing original plate, characterized in that the support has a thickness of ~5μ and 7μ or more.