JPH0240518B2 - HEIBANINSATSUYOGENBANNOSHIJITAIOYOBISONOSEIZOHO - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a support for a lithographic printing original plate that has excellent workability when attached to a plate cylinder and is inexpensive, and a method for manufacturing the same. Conventionally, aluminum plates have been mainly used as supports for image-receiving layers (photoconductive layers, photosensitive layers, heat-sensitive layers, etc.) of planographic printing original plates. Generally, aluminum plates with a thickness of 0.3 mm or more have been used for strength reasons, but aluminum is expensive and is a soft material, so it is prone to deformation and uneven damage during plate making and printing. There was a problem that the rate of repeated use was extremely low and the printing cost was high. For this reason, the inventors of the present invention conducted various studies on supports with excellent strength, and as a result, they devised the use of molten aluminum-plated steel plates as supports, and succeeded in solving the above problem. As shown in the cross section shown in Fig. 1, the plating layer 1 of the molten aluminum plated steel sheet is composed of an alloy layer 3 bonded to the steel sheet 2 and an aluminum layer 4 located on the alloy layer 3. Aluminum 4 has the same properties as aluminum, and has a thickness that allows it to be subjected to treatments such as graining, so that it can be used satisfactorily as a support. Moreover, since the plating layer 1 is supported by a steel plate, it exhibits excellent strength. However, the surface of the hot-dip aluminum plated steel sheet as it is plated has spangle irregularities S, grain boundary depressions C, pinholes P, etc.
Normally, in its original state, it cannot be used as a support where even minute defects are a problem. As a method to solve these drawbacks, there is a method of subjecting a hot-dip aluminum plated steel plate to cold rolling with a bright roll after plating at a total reduction rate of 30 to 85%. However, in this method, although pinholes are crimped, since a bright roll is used as a roll, the frictional force between the roll surface and the surface of the plating layer is weak, and even if the rolling reduction rate is increased, the surface layer, such as spangled grain boundaries, is The disadvantage was that the dents formed in the rolling direction were only extended in the rolling direction and became shallower, but could not be completely erased. On the other hand, as a method of eliminating spangles generated on the surface layer, there is a method of using dull rolls having a large friction coefficient during cold rolling to strengthen the fluidity immediately below the plating layer. However, in the case of this method, the dull roll has a surface roughened by shot blasting or the like, and if the rolling reduction ratio is large, the roll eyes will wear out quickly, so it was necessary to keep the rolling reduction ratio to a light rolling reduction. For this reason, the pinholes in the plating layer are not removed, and in order to remove them, the dents at the spangle grain boundaries are corrected by light rolling with dull rolls, and then cold rolling with a reduction rate of 30 to 85% using bright rolls. It was necessary to apply rolling. However, while rolling at such a high reduction rate has the advantage of increasing the strength of the steel plate, it has traditionally been problematic that the plate cracks due to work hardening when attached to the plate cylinder. i.e. 0.3mm thick
In the case of class supports, the ends may have to be bent more than 120 degrees to attach them to the plate cylinder.
If such sudden bending was applied to a product rolled at a high reduction rate, cracks would occur. This plate cracking was particularly likely to occur when the supporting body was cut out from a molten aluminum plated steel plate and the ridgeline direction of the bending had to be in the rolling direction due to the size of the image. For this reason, a thick support with a reduction ratio of 20 to 40% has been desired.
However, in the case of conventional manufacturing methods, it has been difficult to eliminate pinholes in the plating layer even when cold rolling is performed at a preferable reduction rate. On the other hand, in the printing industry, PS plates with aluminum plate as a support are still widely used.
Printers usually purchase this PS plate from a printing plate manufacturer and use it only once, making it disposable. Therefore, when a PS plate using a molten aluminum plated steel plate as a support is used for such purposes, it is economical to make the aluminum layer as thin as possible. However, in the case of molten aluminum plated steel sheets,
The thinner the aluminum layer is, the more frequently pinholes occur, and the protrusions of the alloy layer develop closer to the surface of the aluminum layer. Therefore, when the rolling reduction ratio is increased to eliminate pinholes during cold rolling, the protrusions of the alloy layer are exposed to the surface, and as a result, there is a problem that, like the pinholes, the image is adversely affected. In view of the above-mentioned problems, the present invention aims to provide a support that does not cause plate cracking when attached to a plate cylinder and is economically advantageous for one-time disposable use, and a manufacturing method thereof. . The present inventors have conducted various studies in order to provide an inexpensive support that has plate cracking resistance against bending, and as a result, a molten aluminum plated steel plate with a Si content of 6 to 10% in the plated layer, The single-sided plating layer is
We have completed a support for a lithographic printing original plate, which consists of an alloy layer of 0.1 to 3μ and a Si-Al layer of 3μ or more, and is characterized in that the pinholes in the Si-Al layer are crimped. The present invention will be described in detail below. First, in the present invention, the reason why the plating layer of the hot-dip aluminum-plated steel sheet contains 6 to 10% Si is to form an alloy layer without protrusions. Generally, when a steel plate is plated in a Si-Al plating bath, the boundary between the alloy layer and the Si-Al layer in the plating layer is not smooth, and the protrusions of the alloy layer dig into the Si-Al layer. There is. For this reason, when thinning is required, such as in the case of a support for a disposable PS plate, if the alloy layer has protrusions, they will be exposed from the Si--Al layer after rolling and will adversely affect the image as described above. Therefore, in order to prevent the formation of protrusions on this alloy layer,
It is necessary to control the Si content in the plating layer to 6 to 10%. Next is the alloy layer and Si-Al layer in the plating layer.
The reason why these thicknesses are set as described above is to improve the bending peeling resistance of the plating layer and to reduce the cost of the support. As mentioned above, increase the Si content in the plating layer to 6 to 10%.
However, the formation of an alloy layer cannot be avoided. However, since the alloy layer has poor workability, increasing the thickness will deteriorate the peeling resistance of the plating layer. Therefore, from this point of view, the thickness of the alloy layer needs to be 0.1 to 3 μm. On the other hand, when considering the economy of disposable use, it is a good idea to make the Si--Al layer on the alloy layer as thin as possible. However, a minimum thickness of 3 μm is required so that the surface can be roughened by graining or the like as a pretreatment before forming the image-receiving layer. However, if the thickness of the Si--Al layer is reduced in this way, pinholes will occur more frequently, which will adversely affect the image-receiving layer. Therefore, it is necessary to press the pinholes in the Si--Al layer. Therefore, it is difficult to manufacture the above-mentioned support by the conventional method because the cold rolling process involves high pressure, which causes plate cracking and exposure of the alloy layer. Further, in cold rolling, the use of dull rolls and bright rolls has the disadvantage that the number of rolling steps increases. As a result of various studies in order to eliminate these drawbacks, it was discovered that it is possible to solve these problems by heating the molten aluminum plated steel sheet immediately after plating and remelting the plated layer. In other words, if a molten aluminum-plated steel sheet is heated immediately after plating to remelt the plating layer, the plating layer will reflow, so the plating layer (Si
- The pinholes existing in the Al layer are fluidized and the depressions at the spangled grain boundaries become shallow or almost completely eliminated. Therefore, during cold rolling, it is not necessary to use a high rolling reduction rate to compress pinholes, and without using dull rolls, it is possible to eliminate dents in spangle grain boundaries using just bright rolls, and the number of rolling steps can be reduced. . The method of the present invention will be specifically explained below with reference to FIG. Fig. 2 is a schematic diagram of a Sendzimer type continuous molten aluminum plating equipment, in which a cold rolled steel plate 2a, which is the original plate for plating, is set on a payoff reel 5, and the cold rolled steel plate 2a pulled out from this is annealed. - After being annealed and pretreated (reduction treatment) in a reduction furnace 6, it is immersed in a molten aluminum bath 7 and pulled up vertically via a sink roll 8, and a gas throttle nozzle 9 is placed directly above the molten aluminum bath 7. Adjust the thickness of the plating by blowing it with a At this time, the thickness of the plating layer is preferably 12 to 35μ on one side.
By 20-30μ. In order to prevent the formation of protrusions in the alloy layer in such thinning, the Si content in the molten aluminum bath should be 6 to 10.
%, preferably 7 to 10%, and the heating time for remelting is 10 seconds or less. The effect of suppressing the alloy layer in the plating layer starts to appear when 1% or more of Si is added, but if it is increased as described above,
The growth of protrusions on the alloy layer is suppressed, and the alloy layer and Si−
The boundary surface of the Al layer becomes gentle. Therefore, the alloy layer is not exposed to the surface of the Si--Al layer, and there is no adverse effect on image reception. Next, after adjusting the plating thickness, the burner 11 is placed in the reflow apparatus 10 while the plating layer is not solidified.
The steel plate 2a is heated to remelt the surface layer of the plating layer. At this time, if the remelting conditions are set appropriately, the surface layer of the plating layer will remelt and increase fluidity.
The pinholes can be crimped, and the recesses at the spangled grain boundaries can be made shallow or almost completely eliminated. As for this remelting condition, hot-dip galvanized steel plate is
It is appropriate to heat at 620-700°C for 3-10 seconds. This is due to the low fluidity of the mating layer below 620℃, which has little effect on crimping pinholes and smoothing out concavities at spangled grain boundaries;
This is because the fluidity of the fastened layer becomes too high at temperatures above 700°C, and when it is pulled up vertically, the fastened layer partially flows down, creating unevenness that cannot be eliminated by subsequent cold rolling. . Further, at such high temperatures, the growth of the alloy layer is also promoted, and the bending workability is also deteriorated. In the present invention, pinholes are crimped and concavities at spangled grain boundaries are smoothed using a reflow device 10, and then the material is wound up using a tension reel and then subjected to cold rolling. Bright rolls are used for cold rolling, and the reduction rate is
If it is carried out at 20 to 85%, preferably 20 to 30%, it is possible to eliminate pinholes and smooth out concavities at spangled grain boundaries. Furthermore, since there is no significant work hardening at such a rolling reduction ratio, the plate can sufficiently withstand bending during installation on the plate cylinder. The method of the present invention can also be applied when the Si--Al layer is thick, that is, when producing a support that can be used repeatedly. In this case, the thickness of the plating layer is increased to 20 to 60μ on one side, preferably 30 to 50μ,
The remelting conditions may be within the above range. Example: A cold rolled steel plate with a thickness of 0.4 mm and a width of 914 mm has a Si content.
After plating with 9.5% molten aluminum, the thickness of the plating layer is reduced by gas wiping on one side.
The thickness was adjusted to 11μ, and then reflow treatment was performed at 660°C for 7 seconds. Thereafter, the obtained steel plate was divided into two parts, and one of the parts was cold rolled with a bright roll at a reduction rate of 40% to produce a support having a thickness of 0.23 mm.
The other part was cold rolled using a bright roll at a reduction rate of 25% to produce a support with a thickness of 0.23 mm.
The accuracy test results for each of these samples are shown in the table below.

[Table] The Vickers hardness is the value of the steel plate after removing the plating layer. Sample No. 2 corresponds to 1/4 hardening because it was lightly rolled, and the plate does not crack even when bent in the rolling direction. It did not occur. In addition, each of the above-mentioned supports was grained and coated with a photocuring resin in accordance with conventional methods to produce printing plates, which were then made into plates and subjected to printing tests using a lithographic printing machine. Good images were obtained with both original plates. As described above, the present invention makes it possible to preliminarily eliminate pinholes and spangle grain boundary depressions by performing reflow treatment before cold rolling.
Even if the thickness of the Al layer is reduced, it can be easily erased by subsequent cold rolling. Furthermore, since the rolling reduction ratio can be made significantly smaller than in the past, plate cracking due to work hardening will not occur, and since rolling can be performed using only bright rolls, the number of rolling steps can also be reduced. Furthermore, the obtained support is of good quality despite its thinness, so it can be used for disposable PS plates.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a steel plate plated with molten aluminum, and FIG. 2 is a schematic diagram of continuous molten aluminum plating equipment using the Sendzimer method. 1... Plated layer, 2... Steel plate, 2a... Cold rolled steel plate, 3... Alloy layer, 4... Aluminum layer,
5... Payoff reel, 6... Burning pure/reducing furnace, 7
...molten aluminum bath, 8... sink roll,
9... Gas throttle nozzle, 10... Reflow device,
11...burner, 12...tension reel,
S...Irregularities of spangles, C...Dents in spangle grain boundaries, P...pinholes.

Claims (1)

[Scope of Claims] 1. An original plate support for lithographic printing having an image-receiving layer formed on its surface, the support being a molten aluminum-plated steel plate with a Si content of 6 to 10% in the plating layer; 1. A support for a lithographic printing original plate, wherein the single-sided plating layer comprises an alloy layer with a thickness of 0.1 to 3μ and a Si-Al layer with a thickness of 3μ or more, and pinholes in the Si-Al layer are crimped. 2 After pretreatment of cold rolled steel plate, Si is added to 6 to 10
The steel plate was immersed and plated in a molten aluminum bath containing 100% aluminum, then vertically pulled out of the bath, the thickness of the plated layer was adjusted by a gas wiping method, and the steel plate was subsequently heated to 620 to 700°C. The pinholes in the plating layer are fluidized by remelting the plating layer, and then the steel plate is subjected to a total reduction rate of 20 to 85.
% cold rolling process, and the alloy layer and Si-Al layer in the plating layer are each 0.1 to 3μ on one side.
and a method for producing a support for a lithographic printing original plate, characterized in that it maintains a thickness of 3μ or more.