JPS61270380A - Method for roughening surface of metallic sheet for printing plate - Google Patents

Abstract

PURPOSE:To manufacture a metallic sheet for a lithographic printing plate having superior dot reproducibility at a low cost by spraying an acidic soln. contg. ferric ions as the principal component on a steel sheet of a specified thickness so as to regulate the average surface roughness and the number of HSC to a specified value each. CONSTITUTION:A steel sheet of 30-250mum thickness is etched by spraying an acidic soln. contg. ferric ions as the principal component so as to regulate the average surface roughness to 0.1-2mum and the number of HSC to 40-110 pieces per 2.5mm. The concn. of the ferric ions in the acidic soln. is about 10g/l- the solubility limit and the preferred pH of the soln. is about 0-5. A metallic sheet for a printing plate having superior hydrophilic property, water retentivity, dot reproducibility and printing resistance is obtd. The printing plate also has superior adhesion to a substance having a great affinity for ink.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a metal plate for printing plates that has excellent hydrophilicity, water retention, adhesion resistance of ink-philic substances, halftone dot reproducibility, and printing durability. This relates to a manufacturing method and is an improvement on JP-A-57-143490.

[Conventional technology and its problems]

Currently, there are 11 metal plates for planographic printing plates using metal materials.
1. M plates, which can easily obtain a surface shape suitable for planography by mechanical or electrochemical methods, are generally used.

However, AJ! Metal plates for lithographic printing plates based on AI! are expensive, so methods have been taken to reduce the thickness of the 2M plate, but AI! The thinner the plate, the poorer its mechanical properties, and generally a thickness of 0.1 to 0.3 mm is required. For example, M plates with a thickness of 0.3 mm are used for newspaper printing.
Anodized to improve printing durability. Therefore, M plates with a thickness of 0.3 mm or less can only be used for light printing.

In addition, the process of mechanically or electrochemically polishing the 2M plate and then subjecting it to hydrophilic treatment is extremely complicated.
Furthermore, the processing time is long, and although there are many patents related to these, it has not yet been simplified, which is also the reason why lithographic printing plates based on U plates are expensive.

[Problem that the invention seeks to solve]

In this way, a metal plate for a lithographic printing plate that is inexpensive and has excellent characteristics (particularly halftone reproducibility) has not been obtained.

[Means for solving problems]

Therefore, we focused on a steel plate that has better mechanical properties than M plate and is also cheaper.

It has been found that the plate material based on steel plate is inexpensive and only needs to be 0.1 mm thick in order to obtain mechanical strength comparable to that of M plate with a thickness of 0.3 ann. Therefore, we investigated how to make the surface of the steel plate as a metal plate for lithographic printing equal to or better than that of the M plate, and found a completely new method that is superior to the U plate for lithographic printing.

The present invention provides a plate material that has excellent hydrophilicity, maintains this hydrophilicity over a long period of time without deterioration, and has excellent water retention, adhesion to ink-philic substances, halftone dot reproducibility, and printing durability. A method for obtaining a metal plate is provided.

The gist is a steel plate with a thickness of 30 to 250 μm.

Surface average roughness is 0.1-2μm, HSC is 40-110
pieces / 2. , 5 mm l=By spraying an acidic solution containing ferric ions.

After spraying an acidic solution containing ferric ions, F
The surface is roughened by e-plating, and then further plated to give corrosion resistance, and then subjected to known hydrophilic treatment.It is inexpensive, has hydrophilicity, water retention, adhesion to ink-loving substances, and halftone dot reproduction. This is a method for producing metal plates for printing plates with excellent durability and printing durability.

The present invention will be explained in detail below.

The plate metal plate of the present invention is a steel plate manufactured by a rolling method and has a thickness of 30 to 250 μm. The thickness of the steel plate is 25
If it exceeds 0 μm, it will be difficult to process the second plate material, and it will also be uneconomical in terms of material costs. Also.

If the thickness is less than 30 .mu.m, the manufacturing cost is currently high (and uneconomical), and the next step, spray etching, not only roughens the surface but also melts the steel plate, resulting in significantly poor mechanical strength.

Next, the surface average roughness Ra (JI8 B 0601) 0.1 which has good hydrophilicity, water retention and halftone dot reproducibility.
~2 μn, 40~110 HSCs/2.5 m, and to form a surface shape (2. Spray an acidic solution containing ferric ions onto the steel plate using the spray method f2, or
After spraying an acidic solution containing iron ions, Fe plating is performed in a solution containing ferrous ions as a main component. If the surface roughness Ra is 0.1- or less, the surface will be nearly smooth, so hydrophilicity and water retention will be sufficient.
If it is 2 μm or more, it will be too rough and the image will bleed during printing, making it impossible to obtain good printed matter. 40 H2O/
If it is less than 2.5 mm, the adhesion with the photosensitizer and halftone dot reproducibility will be extremely poor, and if it is more than 110 pieces/15-, the removal of the photosensitizer during development will be poor. Etching by spraying not only roughens the surface in a shorter time than etching by dipping, but also increases the number of irregularities per single area and changes the surface shape.

Adhesion with hydrophilic and water-retaining 2 photosensitizers and halftone dot reproducibility are improved. In particular, the halftone dots on the positive 74128 plate are
In the exposure process with ultraviolet rays, it is necessary to make the halftone dots smaller than those of a positive original, and in order to make the halftone dots smaller, it is better to whiten one surface or increase the number of peaks per length of the surface.

Furthermore, since spraying not only roughens the surface but also removes smudges generated by etching, desmutting treatment such as etching by dipping is not necessary. Furthermore, compared to electrolytic etching, there is no need for electricity, which is advantageous.

Spray method (double etching can be done on one side or both sides of the plate. The processing solution can be a halogen bath mainly containing ferric ions, a sulfuric acid bath, a nitric acid bath, a mixed bath of a chloride bath and a sulfuric acid bath, or a sulfuric acid bath. An acidic solution consisting of a 1-minic acid bath is used.The inclusion of ferric ions has the advantage of roughening the surface in a short time, since the ferric ions are oxidizing agents compared to simple inorganic acids.

Furthermore, since a solution containing ferric ions is used, only Fe is eluted by etching, making bath management easy. The concentration of ferric ion can be carried out in the range from 10gIt to less than the solubility, and if it is less than 10gIt
The liquid deteriorates significantly due to the consumption of iron ions, which not only makes continuous processing difficult.

The surface shape becomes uneven. Also, if the solubility is higher than
Insoluble ferric compounds are generated, which tends to clog the spray nozzle and cause trouble. Therefore, the upper limit of the ferric ion concentration is regulated by the pH 1 temperature of the etching solution and the type of salt. The pH is preferably 0 to 5, especially O
A range of 3.5 to 3.5 is preferable. If it is 5 or more, the solubility of ferric ions decreases and the generation of insoluble ferric compounds clogs the spray nozzle, and the surface shape becomes non-uniform.

To adjust the pH, if the etching solution is chloride, use hydrochloric acid,
In the case of sulfates, the same thing can be used, such as sulfuric acid. The temperature is preferably in the range from room temperature to below the boiling point, especially preferably from room temperature to 80°C or below.If the bath temperature is high, it will be possible to increase the liquid concentration, but the dissolution rate of iron will be slower than making the surface rougher. This speeds up the spraying considerably, promotes liquid deterioration, and tends to make the surface shape uneven.It is preferable to use a nozzle type that sprays the liquid in a mist rather than a liquid state.

The number of irregularities per single area in the surface shape increases,
Furthermore, bits with a diameter of 1 μm or less are generated, which makes printing easier, and water retention and halftone dot reproducibility are particularly improved. To prevent liquid deterioration due to an increase in ferrous ions, add an oxidizing agent such as hydrogen peroxide or electrolytically oxidize. In the case of chlorides, liquid deterioration can be easily prevented by blowing chlorine gas. be. Furthermore, when performing Fe plating after etching.

It is possible to replenish Fe plating with a solution reduced to ferrous ions. In that case, the Fe plating solution uses the same salt as the etching solution. Spray set etching Fe
The plating thickness is preferably in the range of 0.1 to 5 μm.

It is mainly used to adjust the average surface roughness Ra after etching. Further, a known plating solution may be used.

Examples include a halogen bath, a sulfuric acid bath, a mixed bath of a chloride bath and a sulfuric acid bath, and a sulfamic acid bath, which contain the same salt as the etching solution.

Next (; Simply roughening the steel plate will result in poor corrosion resistance.
Since red rust occurs, which is undesirable, it is preferable to perform surface treatment. Surface treatments include single-layer plating of metals such as Cr, Ni, Sn, Cu, and Zn, which have a rust-preventing effect on steel sheets, multi-layer plating that combines two or more of these metals, and one of these metals. There are plating methods such as seed or alloy plating containing two or more types.

Such surface treatment not only improves corrosion resistance.

Adhesion C2 to the ink-philic substance forming the image area also works effectively. In particular, in the case of plating, roughening of one surface≦2 is also effective due to appropriate growth of the electrodepositing solution. For this reason, it is better to perform surface treatment under uneven plating conditions than under smooth plating conditions.

It is economical to set the plating thickness so that the lower limit is such that the corrosion resistance of the steel plate is guaranteed. It is not necessary to make the thickness of expensive metals such as Cr or Ni unnecessarily thick, even if it is an inexpensive metal such as Zn. In addition, by applying a known chemical conversion treatment that imparts corrosion resistance after plating,
Not only is it possible to further reduce the plating thickness, but
Adhesion with photosensitizer is improved. Known chemical conversion treatments include immersion or electrolysis in solutions containing, for example, chromates, dichromates, phosphates, molybdates, silicates, borates, perphosphates, aluminates, etc. This is the process by.

Some metals that have been surface-treated to have the above-mentioned average surface roughness exhibit hydrophilicity and can be used as plate materials as they are, but many of the surface-treated metal plates are insufficiently hydrophilic; Moreover, the hydrophilicity deteriorated significantly over time, so parent wood treatment was performed again.

Hydrophilic treatment is common (2) Well-known treatments are best.
For example, silicate treatment, organic titanium compound treatment,
Organic phosphoric acid treatment, ferrocyanate treatment,
Examples include, but are not limited to, gallic acid treatment, phosphotungstic acid treatment, organic polymer coating treatment such as polyacrylic acid or CI'vI C, or treatment with a sol of an inorganic compound.

[For production]

The plate metal plate treated in the above process is hydrophilic.

Excellent water retention, adhesion to ink-philic substances, halftone dot reproducibility, and printing durability.

〔Example〕

Hereinafter, C will be specifically explained in Examples.

Example 1 A steel plate with a thickness of 150 μm was heated at a temperature of 30°C and a concentration of 3801
1 ferric chloride solution (pH 0.8, measured after diluting 5 times)
by passing it through a spray nozzle (TYPE-S type manufactured by Heshu Kogyo Co., Ltd.) for 40 seconds.

The surface was roughened to an average surface roughness Ra of 0.9 μm. Add to this 250 V/zinc sulfate! ! , ammonium sulfate 30 v'
Using a solution containing l, the temperature was 45°C and the current density was 20A.
Zn was plated to a thickness of 0.7 μm under the condition of /dm2 and immersed for 6 seconds in a solution containing 30 v'l of chromic anhydride and 1 g/l of sulfuric acid (temperature: 40°C). Next, 20 v'l of alumina sol (product name: AS-200, manufactured by Nissan Chemical) and 1 vol of silica sol (product name: Nisnotex-02, manufactured by Nippon Kagaku).
Electrolysis was carried out for 20 seconds at a current density of 0.2 A/dm2 using a steel plate as a cathode in a solution containing q/l (temperature 30°C).

After washing with water, it was dried. Furthermore, a solution containing 2 Jl of phosphoric acid (
Temperature: 306C) for 10 seconds, washed with water, and dried to obtain a metal plate for printing plate.

Example 2 Steel foil C2 with a thickness of 30 μm and 50 g of ferric chloride solution (measured after diluting pH 2, 1, and 5 times) at a temperature of 70°C were passed through a spray nozzle (VD type manufactured by Ikeuchi Corporation) for 10 minutes. The surface was roughened to an average surface roughness Ra of 082 μm by blowing for seconds. Add to this a Watts bath (nickel acid 240 V
/l! -Nickel chloride 4 s v'l, horic acid 30
v/l, temperature 50' (::, current density 5 people 74
Ni was plated to a thickness of 0.2 μm under conditions of
5v'l) at a temperature of 45°C and a current density of 20A/
Cr was plated to a thickness of 0.02 μm under dm2 conditions, and Ti
A steel foil was used as a cathode in a solution containing sol 60 v'l and chromic anhydride I Jl at a temperature of 30°C and a current density of 0.2.
Electrolyze for 30 seconds under the condition of "A/dm", wash with water and dry.

A metal plate for plate material was obtained.

Example 3 A steel plate with a thickness of 250 μm was heated at a temperature of 45°C and a concentration of 200a.
/l of ferric sulfate solution (pH 7) with a spray nozzle (
The surface was roughened to an average surface roughness Ra of 2 .mu.m by blowing the surface through a C2 filter for 40 seconds. Add to this a ferrostane bath (80 vt of stannous sulfate, 80 g/l of phenolic acid, Neugen E N
20 v/I, temperature 456C2 current density 10
8N was plated to a thickness of 0.07 μm under the conditions of A/dm2 (7) in a solution containing 30 g/l of potassium monochromate, using plate A as a cathode, at a temperature of 11:40°C and a current density of 5. Electrolysis was performed for 5 seconds at A7dm2. After washing with water, it was immersed for 30 seconds in a solution containing 0.9 v'l of sodium carboquine cellulose (temperature I ¥40°C), and after washing with water, it was dried to obtain a metal plate for plate material.

Example 4 Copper plate C with a thickness of 1100u, humidity temperature 0eC, 4509/l
A ferric chloride solution (pH 0.5, measured after being diluted 5 times) was passed through a spray nozzle (TYPE-AS model manufactured by Heshu Kogyo Co., Ltd.) and sprayed for 30 seconds.

Temperature 906C1 in a bath containing ferrous chloride so Og/l
The surface was roughened to an average surface roughness Ra of 0.5 μm by plating Fe to 2 μm under the condition of a current density of 20 A/dm 2 . To this, f-p end bath (chromic anhydride 250
g/I! , sulfuric acid λ5 a/l) at a temperature of 50
℃, current density 20 A/dm2, Cr 0.07
Perform μm plating and use alumina sol (product name: AS-20).
The plate was immersed in a solution containing 80 g/l (manufactured by Nissan Chemical) at a temperature of 40° C. and for a processing time of 30 seconds, washed with water, and dried to obtain a metal plate for plate material.

Example 5 A steel plate with a thickness of 200 pm was heated at a temperature of 40°C and 2009/l.
A ferric chloride solution (pH 1, 1, 5 times diluted and measured) was sprayed using a spray nozzle (TYP E-1M model manufactured by Heshu Kogyo Co., Ltd.).
9 surface average roughness Ra to 1 by spraying through the
．． 5 μml was roughened twice. Add to this 250g of stannous chloride
nickel chloride 50 v'l, sodium fluoride 2
0 g/l, using a bath containing 1011 of hydrochloric acid, at a temperature of 50°C, 1! N1-an under the condition of flow density 2.5AAm2
The alloy was plated to a thickness of 1 μm and subjected to a known hydrophilic treatment (gum arabic coated to a thickness of 0.5 μm and dried) to obtain a metal plate for second plate material.

Comparative Example 1 A steel plate having a thickness of 2001 m and an average surface roughness RaO of 5 μm was subjected to the same k as in Example 1 without being subjected to surface roughening treatment.
Plating, chromate treatment and hydrophilic treatment were performed.

Comparative Example 2 A steel plate with a thickness of 100 μm was coated with Fe plating of 5 μm using the same Fe plating solution as in Example 4 at a temperature of 90°C and a current density of 20 A/dm2, and the surface average roughness Ra was 0.
The thickness was set to 5 μm, and the same Cr plating and hydrophilic treatment as in Example 4 were performed.

Comparative Example 3 Using the same steel plate as in Example 1, the same steel plate as in Example 1 was used.
Using an iron solution, immerse it for 40 seconds and reduce the average surface roughness Ra to 0.
．． The surface was roughened by 5 μm. Furthermore, the same Zn plating, chromate treatment, and hydrophilic treatment as in Example 1 were performed.

Comparative example 4 This is a commercially available M-Pace plate-making material.

Comparative Example 1 shows an example in which surface roughening treatment was not performed, Comparative Example 2 shows an example in which Fe plating was performed as surface roughening treatment, and Comparative Example 3 shows an example in which immersion etching was performed as surface roughening treatment.

The following various tests were conducted using the plate metal plate thus obtained.

Surface roughness> The surface roughness was measured using a stylus type roughness meter (name: 5URF-1 manufactured by Tokyo Seimitsu), and the number of peaks (H) per measurement length of 2.5 m +
High 8pot Count (number of peaks and valleys) was measured by extracting 25 measurement lengths from the cross-sectional curve and distinguishing peaks and valleys based on whether they were located above the average line.

Hydrophilicity Immediately after manufacturing the metal plate for plate material, a positive type photosensitive liquid (product name: Quick Wipe On Body Type, manufactured by Ueno Chemical Co., Ltd.) was applied. The coating weight of the photosensitive liquid after drying was zOg/m2.

A positive original film was closely adhered to the lithographic printing plate material obtained in this way, and it was exposed for 70 seconds from a distance of 1 m using a 2 kW metal halide lamp (New Idol Fin 2000 manufactured by Iwasaki Electric Co., Ltd.) as a light source, and a developer ( An image was formed by immersing the film in Dp-3) manufactured by Fuji Photo Film Company. The developing conditions were 25° C. and 45 seconds.

Hydrophilicity was determined by dropping water onto the hydrophilic area on the plate thus obtained and measuring the contact angle. A contact angle of 20° or less was marked O, a contact angle of 20 to 40° was marked Δ, and a contact angle of 40° or more was marked X.

Halftone dot reproducibility> The halftone dot reproducibility is calculated by enlarging the halftone dots (48.9% halftone dots, 150 lines of positive manuscript) of the plate created for hydrophilicity evaluation by 50 times and 62 times.
The halftone dot area was measured. In addition, the evaluation.

If the difference from the positive original was 5% or more, it was marked with a circle, if it was 3 to 5%, it was marked with a Δ, and if it was 3% or less, it was marked with an X.

Printing durability> The printing durability was evaluated by offset printing the plate prepared for hydrophilicity evaluation and printing up to 50,000 sheets.

〔Effect of the invention〕

The evaluation results are shown in Table 1.

Table 1 Evaluation Results As shown in Table 1 (2), the metal plates for plate materials according to the present invention 6 in Examples 1 to 5 had better halftone reproducibility and printing durability than commercially available U-based plate making materials. It is excellent in this respect.

In addition, the surface roughening treatment is performed by spray etching and Fe plating after spray etching.

Halftone dot reproducibility and printing durability were improved.

As for printing durability, no abnormality was observed in Examples 1 to 4 even after printing 50,000 sheets, but in Comparative Example 1, the image peeled off after 10,000 sheets. Comparative Examples 2 and 3 are 40,000 sheets.

In Comparative Example 4, some images peeled off after 20,000 sheets were printed.

Claims (2)

[Claims] (1) A steel plate with a thickness of 30 to 250 μm, an average surface roughness of 0.1 to 2 μm, and 40 to 110 HSCs/2.5
1. A method for roughening a metal plate for printing plates, which comprises spraying an acidic solution containing ferric ions as a main component so that the surface roughens the surface of a metal plate. (2) A steel plate with a thickness of 30 to 250 μm, an average surface roughness of 0.1 to 2 μm, and 40 to 110 HSCs/25 m
After spraying an acidic solution containing ferric ions as the main component so that A method for roughening the surface of metal plates for printing plates, characterized by: