JPS61162351A - Manufacture of grain on lithographic printing plate - Google Patents

Abstract

PURPOSE:To obtain a grained plate of of a lithographic printing whose uniformity of a rough surface and density of concave part are high and roughness is sufficient, by a method wherein rolling of an aluminium plate or foil is performed at a specific pressure decreasing ratio by a roll having a specific rough surface. CONSTITUTION:Rolling of an aluminium plate or foil is performed at a rolling reduction of 2-20% by a roll whose mean roughness (Ra) at the center line is made into 0.7-1.7mum and the number of crests of unevenness having depth of more than 0.6mum is made more than 500 piece/mm<2> by electric discharge machining. Under a state wherein the mean roughness (Ra) at the center line is less than 0.7mum, the number of crests of unevenness having depth of less than 0.6mum is made less than 500 piece/mm<2> and pressure decreasing ratio is less than 2% adhesion of a photosentive film and water retention characteristics at the time of printing is not sufficient, and when the mean roughness at the center line and the rolling reduction exceeds respectively 1.7mum and 20%, a small point reproducibility is deteriorated. As for the upper limit of the number of crests of the unevenness, it is desirable to make it into 20,000 piece/mm<2> and if it is more than this, it becomes that sufficient roughness and uneven density can not be obtained as a supporting member for lithographical printing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing grains of a lithographic printing plate support, and more specifically, the present invention relates to a method for producing grains of a planographic printing plate support, and more specifically, The present invention relates to a method for producing grains of a lithographic printing plate support having roughness (Ra).

[Prior Art 1 Aluminum is currently widely used as a base material for manufacturing lithographic printing plates.

(Hand) Hello Fulgonium! The stamp length is 1+7J and the surface of the plate is roughened to form grains, a photosensitive composition is applied, and this is exposed and developed to leave the image area to be printed as a resist layer. Ru.

The purpose of forming this grain on the surface of the aluminum plate is twofold: firstly, it provides appropriate water retention during printing operations, and secondly, it increases the adhesion between the photoresist coating and the surface of the aluminum plate to provide sufficient durability. It is to give printing power.

There are various methods for graining, and they are roughly divided into mechanical methods and chemical methods.

First, there are standard methods such as ball graining, wire graining, and brush graining, and second, chemical methods include corrosion methods in acid or alkaline solutions, electrochemical corrosion methods, etc. has been made into

However, these methods have the following problems.

In other words, the problems with mechanical graining are that it requires considerable skill in adjusting the machine and the abrasive material, and that the abrasive material and aluminum shavings embedded in the surface of the roughened aluminum plate can be easily removed. This requires work to remove.

In addition, problems with chemical graining include bath composition, bath temperature,
The electrolytic conditions must be adjusted within a fairly narrow range, and furthermore, if electrochemical graining is used, which provides the highest quality grain, the power consumption will account for a considerable proportion of the printing plate manufacturing cost. It's about getting bigger.

This kind of conventional 8! As a method to solve the problems of mechanical graining method and chemical graining method,
Publication No. 074898 describes a grain production method in which holes with a depth of 3.5 μm or less are formed by passing an aluminum plate through a roll having an inverted graining surface, and
JP-A-57-500329 describes a method in which an aluminum plate is passed through a roll having a specified surface roughness to form a specified surface barrier depth, and then anodized.

These graining methods are easy to repeat and do not require the removal of abrasives, aluminum chips, etc. unlike conventional mechanical graining methods.Furthermore, they are fast and greatly streamline the manufacturing process. There is a possibility that However, when creating holes using the Naga-Mutsu press, it is difficult to control only the depth of the holes as described in these publications.
It has not been possible to obtain a grain suitable for a lithographic printing plate, and it has not yet been put to practical use.

The present inventor solved the problems in the graining method explained above, and not only streamlined the manufacturing process, but also
The invention described in Japanese Patent Application No. 58-145401 was completed with the aim of producing a grained plate that was also satisfactory in terms of performance as a lithographic printing plate support. That is, it was discovered that the desired goal could be achieved by providing four oval presses at a specific density on the surface of the support, with some of them overlapping to form a wavy pattern. As a method for roughening the roll surface, shot blasting was used to form four oval presses on the surface at a density of 200 pieces/ml or more, and the press recesses partially overlapped to form a wavy pattern. The planographic printing plate support is made of an aluminum plate.

However, in the Nagamu Shishit Blasting method, in order to increase the density of recesses, it is necessary to reduce the diameter of the grid to be shot when processing the roll, and as the grid diameter becomes smaller, the impact force of each grid becomes smaller, and the printing There is a tendency that a sufficient roughness (Ra) value cannot be obtained as a plate, and this tendency is caused by impeller rotation speed, grid input amount, 21
Although it can be reduced by adjusting for 71 hours, it is easy to obtain sufficient performance by having high density, uneven parts, the necessary roughness (Ra), and uniformity on the rough surface. Moreover, in this method, if an attempt is made to give sufficient performance to the rough surface, the rough surface tends to lack uniformity in some areas, and problems such as staining of the plate are likely to occur. That is, in order to manufacture a roll with sufficient characteristics, it is necessary to perform the process under a large number of conditions and select a good product from among them, resulting in poor productivity and high costs, and furthermore, it is necessary to improve the quality.

[Problem to be Solved by the Invention 1] As explained above, the present invention solves problems in various methods of roughening the surface of an aluminum plate as a lithographic printing plate support to form grains, and the present inventors This invention was made based on the knowledge of the invention of the earlier application, and as a result of research by the present inventor, by rolling an aluminum plate or foil at a specific rolling reduction rate with a roll having a specific rough surface, the rough surface can be improved. They have developed a manufacturing method that allows the grain of a lithographic printing plate support to be obtained with high uniformity, high recess density, and sufficient roughness (Ra).

[Means for Solving the Problems] A feature of the grain manufacturing method of the lithographic printing plate support according to the present invention is that the center line average roughness (Ra) can be improved by electric discharge machining.
is 0.7 to 1.7μ+n, and the depth is 0.6.17111
The object of the present invention is to roll an aluminum plate and an aluminum foil at a rolling reduction ratio of 2 to 20% using the roll having the above-described unevenness of 500/mm<2> or more.

Regarding the grain production method of the lithographic printing plate support according to the present invention,
This will be explained in detail below.

First, the surface roughness (Ra) of the roll by electric discharge machining, the depth and density of unevenness, and the rolling reduction rate during rolling are important requirements for producing grain on the surface of the lithographic printing plate support. In other words, the roll surface roughness is an important factor that determines the surface roughness of the rolled material, but the transfer rate of the roll roughness to the rolled material (
It is simply called the transcription rate.

) is also regulated by the rolling reduction rate during rolling. Therefore, in order to obtain sufficient roughness for a lithographic printing plate and to ensure uniformity of the unevenness density, the roll surface roughness, rolling reduction rate, and roll It becomes necessary to specify the unevenness density.

That is, the aluminum plate rolled by the rolls is
Oval-shaped depressions are densely arranged on the surface, and the 7 linos partially overlap to form a wavy pattern.
The shape and density of the four oval parts are related to the suitability of the lithographic printing plate, and it is necessary to control these values within a certain range. This control is performed by performing rolling multiple times.

In order to satisfy these characteristics, the center line average roughness (Ra) of the roll must be less than 0.7 μm, the number of uneven peaks with a depth of 0.8 μm or more must be less than 500 pieces/mm, and the rolling reduction rate must be 2%. If it is less than 20%, the adhesion of the photosensitive film and water retention during printing will not be sufficient, and if the centerline average roughness (Ra) exceeds 1.7 μm or the reduction rate exceeds 20%, the dot reproducibility will decrease. It becomes like this.

Therefore, due to electric discharge machining, the center line average roughness (R
a) The number of irregularities of 0.7-1.7 μm and depth of 0.6 μm or more is 500/nu++2 or more, and the aluminum plate and aluminum foil are rolled at a rolling reduction rate of 2 to 2 using a shida roll.
It is necessary to roll it at 0%.

It should be noted that the upper limit of the number of irregularities with a depth of 0.6 μm or more on the roll is preferably 20,000 pieces/mm2, and if the number is greater than this, the aluminum plate (?i!i) will be damaged during rolling.
The rolls become clogged due to the generation of abrasion powder, making it impossible to obtain sufficient roughness and unevenness density as a lithographic printing plate support.

Further, the aluminum plate or aluminum foil used in the grain production method of the lithographic printing plate support according to the present invention may be a pure aluminum plate or an aluminum alloy plate, and various aluminum alloy plates can be used.
For example, Sl, Cu, Fe, Mn, Mg, Cr5Ti, Z
An aluminum alloy plate containing one or more of Pb%Ni, Pb%Ni, etc. can be used. As explained above, the graining surface of these aluminum plates (foils) and aluminum alloy plates (foils) is formed by one or more graining meals forming a specific graining surface. It is possible to transfer the opening onto the surface of an aluminum plate or the like by rolling down the opening by a specific rolling reduction amount.

[Example] An example of a method for producing grains of a lithographic printing plate support according to the present invention will be described.

Example 1 Rolls with six different surface morphologies were manufactured by electrical discharge machining as shown in Table 1, and their surface conditions were measured using a scanning electron microscope and a stylus surface roughness meter to determine the surface roughness, surface shape, and unevenness. Check the density and show the results.

As a comparison material, a similar test was conducted on the surface morphology by shot blasting using a grid particle size of 300 μm, and the results are also shown in Table 1.

Table 1×1) The roughness shape type a+brc+d is shown in FIG.

(,) The i distance F is shallow and the pitch P is large.

(b) Urine size F and pitch P are small.

(c) Depth F is deep and pitch P is large.

(d) The depth F is deep, the pitch P is large, and there is a protrusion H.

×2) Comprehensive evaluation based on roughness pitch, rough surface shape, uniformity, etc.

×3) Shot blast (comparison material).

From this Table 1, if the center line average roughness of the roll surface due to electrical discharge machining is in the range of 0.7 to 1.7 μm and the number of unevenness with a depth of 0.6 μm or more is 500 or more, the roll It can be seen that the overall evaluation is far superior to Ike's.

Example 2 Table 2 shows that the center line average roughness (Ra) was 1.1 by electrical discharge machining.
μn+, number of mountain bows over 0.611m ooo pieces/m
Plate thickness 0.2 using graining roll with m2
8III11 aluminum plate was rolled at three different rolling reduction ratios, and the surface condition of the rolled plate was investigated using a scanning electron microscope and a stylus type surface roughness meter, and the surface roughness, surface shape, and density of unevenness were investigated. The printing characteristics were evaluated and the results are shown below.

Table 2 also shows the results of a similar test using the shot blasted graining meal of Example 1.

Further, the relationship between the amount of reduction by the roll and the transfer situation is shown in FIG.

From this Table 2, it can be seen that the rolling reduction rate is 2 to
20% range, the center line average roughness of the roll is 0.7 to 1.
If the number of uneven peaks with a range of 7 μm and a depth of 0.6 μm or more is 500/111111” or more, the rolled aluminum plate has excellent adhesion to the lithographic printing plate support during printing, and the overall evaluation It can be seen that the comparative material has good adhesion but poor corrosion resistance and poor printability in the overall evaluation.

Figure 2 shows the change in the transfer rate of surface roughness (Ra) due to rolling and the number of peaks of unevenness of 0.6 μm or more on the roll. You can see that

Comparative Example 1 In Figure 3 (>(b), a plate thickness of 0.2
When an 8 mm aluminum plate was rolled at a rolling reduction rate of 6.0% in one pass, the roughness profile of the surface perpendicular to the rolling direction of the aluminum plate surface was determined using a stylus type surface roughness meter and compared. This is an indication.

In addition, the electric discharge machining of the roll is rough (Rmax) 6.0
The processing was carried out at a machining liquid pressure of 0.3 kg/'cm' or more and a machining speed of 2.4 m/min, and the center line average roughness (Ra) of the roll surface was 1.1 μm. In addition, the shot blasting process also uses a kale grid particle size of 300 μm, an impeller rotation speed of 2250 rpm, and a blasting rate of 300 kg/min.
The test was carried out under conditions of a truck speed of 0.3 m/min. The center line average roughness (Ra) was 1.1 μm.

In Figure 3 (a)), fir and lateral magnification 1000X
Looking at IO, the grain profile of the lithographic printing plate support produced by the electric discharge machining method has a smaller pitch and more uniformity than that produced by the shot blasting method, whereas the grain profile of the planographic printing plate support produced by the shot blasting method is uneven, and the pinch is rougher, especially , uneven protrusions are noticeable in the John de blasting method, and these are likely to be exposed on the photoresist film and cause corrosion leakage.Furthermore, deep depressions tend to leave photoresist film residue, causing background smearing, and the lithographic printing plate The grain is insufficient. Therefore, it is possible to obtain a better grain profile with electric discharge machining than with shot blasting.

Comparative Example 2 Figure 4 shows the grain structure of an aluminum plate obtained by rolling an aluminum plate of N O, 28m+n in one pass at a reduction rate of 6.0% in the same way as Comparative Example 1, using the electric discharge machining method and shot blasting. The center line average roughness (Ra) of the rolled plate is 0.85 μm and 0.8 μm.
It was 1μII+. Then, from the chart profile of the stylus type surface roughness meter, the depth of the unevenness is 0.2 μm or more, 0.6
The results show that the number of peaks larger than μm and 1.2 μm in an area of 9 mm2 was measured, and the grains produced by electrical discharge machining were more sensitive to each irregularity than the grains produced by shosoplastrol. It can be seen that the depth and the number of peaks are large, and in particular, those with a depth of 1.2 μm or more are significantly improved. That is, an increase in the number of shallow peaks improves the adhesion of the photoresist film, and an increase in the number of deep peaks improves spot reproducibility and water retention.

Therefore, the grain structure of the lithographic printing plate support is better than that produced by a graining roll produced by the electric discharge machining method, or by the at-method method. Well, it's cheap.

[Effect of the Invention 1] As explained above, the method for producing grains of a lithographic printing plate support according to the present invention has the above structure;
This has the effect of providing a grain structure having excellent surface roughness, surface shape, and unevenness density as a lithographic printing plate support.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the type of roughness shape in Example 1,
Figure 2 is a diagram showing changes in the transfer rate of surface roughness (Ra) and unevenness density due to rolling, and Figure 3 is a diagram showing the stylus type of a rolled aluminum plate when rolled by a roll using the electrical discharge machining method and the shot blasting method. FIG. 4 is a diagram showing a grain profile measured by a surface roughness meter, and FIG. 4 is a diagram showing the density of unevenness of a grain structure on a chart of a stylus type surface roughness meter. Patent Applicant: Kobe Steel, Ltd. Sai3 Figure (α) (Yamago Kyoei Men) f3 Figure (I)) Spear 4 Figure 0.2 0,6 1.2 i? 1'° on the 9th chart
9 unevenness 5 instep (P77?)

Claims (1)

[Claims] By electric discharge machining, the center line average roughness (Ra) is 0.7 to 1.
．． 7μm, and the number of unevenness with a depth of 0.6μm or more is 50.
1. A method for producing grains for a lithographic printing plate support, which comprises rolling an aluminum plate and aluminum foil at a rolling reduction ratio of 2 to 20% using rolls of 0 pieces/mm^2 or more.