JPS60208293A - Preparation of support for planographic printing plate - Google Patents

Abstract

PURPOSE:To meka it possible to form a homogenous grain reduced in an etching amount by chemically treating the surface of an aluminum plate within a short time, by using an aqueous solution containing ferric chloride and phosphoric acid as an etching solution. CONSTITUTION:An aluminum plate, of which the surface was cleaned, is chemically grained by using an aqueous solution containing ferric chloride and phosphoric acid as an etching solution. The concn. of ferric chloride contained in the etching solution is selected from a range of 20-60wt% and that of phosphoric acid from a range of 40-70wt%. The treatment condition of chemical graining is within a range wherein average center line roughness (Ra) is 0.3-1.0mum and it is advantageous to select said condition from such a range that the temp. of the etching solution is 20-100 deg.C and the treating time thereof is 5- 120sec. As a treating means, a method for immersing the aluminum plare in the bath of the etching solution or one for spraying the etching solution to the surface of the aluminum plate is used. Because smut is generated on the surface of the aluminum plate, desmutting treatment is performed for 1-300sec at 20- 100 deg.C by using a 0.5-40wt% aqueous alkali solution.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method for manufacturing a support for a lithographic printing plate, and in particular to a method for manufacturing a support for a lithographic printing plate, and in particular for the surface of an aluminum plate. [Prior art] Regarding the manufacturing method including the step of chemically graining [Prior art] In order to use an aluminum plate as a support for a lithographic printing plate, it must be made to have good adhesion to the photosensitive layer provided thereon, and Its surface to improve water retention? Roughening is usually performed. This surface roughening treatment is called graining, and is performed by using a mechanical graining chamber such as ball graining, wire graining, or brush graining to give the surface of the aluminum a satin-like appearance using a corrosive solution. Chemical graining by electrolytic etching and electrochemical graining by electrolytic etching are known.

The present invention relates to a method for producing a support for a lithographic printing plate, which is characterized by the step of roughening the surface of an aluminum plate by a chemical graining method among the various graining methods described above. Erosive liquids used in such chemical graining are described, for example, in US Pat.
, an aqueous solution containing ferric chloride, nitric acid and ligation, as described in British Patent No. Aqueous solutions are known.

However, when chemically graining the surface of an aluminum plate using these known corrosive solutions, a long etching process is required to obtain a uniformly grained surface. This technique has the disadvantage that a considerable amount of the parts that do not need to be etched (for example, the tops of the grains) are etched, resulting in inefficiency and a large amount of aluminum being etched. These drawbacks lead to a reduction in production speed and a large burden on maintaining the composition of the corrosive liquid within a certain tolerance range in industrial implementation, and are a major problem in industrialization. It was a hindrance.

[Purpose of the invention]

Accordingly, it is an object of the present invention to provide an improved method for manufacturing a support for a lithographic printing plate, which includes the step of chemically graining the surface of an aluminum plate. That is, an object of the present invention is to provide a method for producing a support for a lithographic printing plate, which includes a chemical graining step that can form uniform grains on the surface of an aluminum plate in a short time. . Another object of the present invention is to provide a method for producing a support for a lithographic printing plate, which includes a chemical graining step capable of forming uniform grains on the surface of an aluminum plate with a small amount of etching. .

[Structure of the invention]

As a result of extensive research, the present inventors have discovered that the above object can be achieved by using an aqueous solution containing ferric chloride and phosphoric acid as an etchant used in chemical graining. That is, the present invention provides a method for producing a support for a lithographic printing plate, which includes a step of chemically graining the surface of an aluminum plate with an etching solution, in which the etching solution is an aqueous solution containing ferric chloride and phosphoric acid. The manufacturing method is characterized by:

Hereinafter, the present invention will be explained in detail in step 2.

The aluminum plate used in the present invention includes pure aluminum and aluminum alloy plate. Various aluminum alloys can be used, such as aluminum alloy, copper, manganese, magnesium, chromium, e-lead, lead,
An alloy of aluminum and metals such as bismuth or nickel is used. These compositions contain some iron and titanium as well as other negligible twill impurities.

Prior to chemical graining, the aluminum surface may be subjected to a spinning treatment in order to remove rolling oil from the aluminum surface and expose a clean aluminum surface.

For the former, VC uses a solvent such as trichlene, a surfactant, and the like. For the latter, a method using an alkaline etching agent such as sodium hydroxide or potassium hydroxide is widely used. In the latter case where a pretreatment with an alkaline etching agent is performed, smut is generated on the surface of the aluminum plate, so it is customary to perform a desmut treatment using nitric acid or the like.

The aluminum plate whose surface has been cleaned as necessary in this way has a concentration of ferric chloride contained in the aqueous corrosive solution containing ferric chloride and phosphoric acid. suitable, more preferably selected from the range 10-≦0% by weight.

On the other hand, it is appropriate that phosphoric acid be contained in the corrosive solution in an amount of 10-10%. As the concentration of phosphoric acid decreases above 10% by weight, the processing time required to obtain a uniform grain increases and the aluminum etching tool increases, reducing the thickness of the aluminum plate. On the other hand, as the amount exceeds 10% by weight, the desired grains are not formed and the surface becomes glossy.

Therefore, a more preferable concentration of phosphoric acid is selected from the range of μ0 to 70% by weight.

The above-mentioned corrosive liquid may be subjected to a known process of machining, if necessary. For example, chlorides like ammonium chloride, calcium chloride, nickel chloride, sodium chloride, aluminum chloride, copper chloride etc., various acids like hydrochloric acid, nitric acid, sulfuric acid, chromic acid, acetic acid etc? can be mentioned. It is appropriate that the content be within the range of this concentration.

The processing conditions for chemical graining using a corrosive solution as described above are such that the centerline average roughness (Ra) is 0.3 to 1.

It is preferable that the temperature of the corrosive solution be selected to be in the range of Oμn1, and such conditions are generally set in the range of
C, the processing time is advantageously selected from the range j~/, 20 seconds. The treatment methods include a method of placing an aluminum plate in a 7ζ bath filled with a corrosive solution, a method of spraying a corrosive solution onto the surface of the aluminum plate, and a method of bringing the aluminum plate into contact with the corrosive material. can also be adopted.

Since smut is produced on the surface of the trap aluminum plate chemically grained in this way, it is preferable to perform a desmutting process to remove the trap aluminum plate. The desmut treatment is carried out by bringing the aluminum surface into contact with an aqueous acid or alkali solution, for example, by dipping.

Acids include phosphoric acid, sulfuric acid, chromic acid, etc., and alkalis include sodium hydroxide, potassium hydroxide, sodium triphosphate, potassium triphosphate, sodium aluminate, sodium metasilicate, sodium carbonate, etc. It will be done. Among these, it is particularly preferable to use the latter aqueous alkali solution because the processing speed is faster. These acids (7) are generally treated for 7-300 seconds at a liquid temperature of λO ~ 1000C using an alkali 0.2-μO weight coefficient aqueous solution IF1. When using an alkaline aqueous solution, aluminum When the surface of the plate is dissolved, an insoluble residue that does not dissolve in alkali is generated on the surface, so in this case, it is further treated with phosphoric acid, nitric acid, sulfuric acid, chromic acid, or a mixed acid that is a combination of two or more of these acids. , this undissolved residue is removed.

The trap aluminum plate treated as described above can be used as a support for lithographic printing plates either as it is or after being subjected to a hydrophilic treatment, but when used for making lithographic printing plates with high printing durability, is subsequently anodized.

The anodic oxidation treatment can be performed by a method conventionally used in this field. Specifically, sulfuric acid, phosphoric acid,
Chromic acid, oxalic acid, sulfamic acid, (benzenesulfonic acid, etc.) or all combinations of two or more of these are passed through the aluminum substrate in an aqueous or non-aqueous solution, and an anode is applied to the surface of the aluminum support. An oxide film can be formed.

What treatment conditions are used for anodizing? Although it cannot be determined unambiguously because it varies depending on the M solution, in general, the concentration of the actual solution is determined by l-rθ weight, and the liquid temperature is j~71:)0C:
%m flow density θ, j ~ 6o an is a/l (m2, voltage t
~io OV% tlJ time r# jθ0 to 10 minutes is appropriate.

These 11! Among the polar oxidation treatments, the British patent number 1. μ/j, 7i<r, a method of anodizing at high current density in sulfuric acid, and U.S. Pat. Preferred is the method of anodic oxidation using phosphoric acid solution as described in .

The anodized aluminum plate is further coated with US Pat. No. λ, 7/41. OAA No. 3. lri.

As described in the specifications of US Pat.
As described in Kou 26, it can also be provided in an undercoat layer of hydrophilic cellulose (eg, carboxymethyl cellulose, etc.) containing a water-soluble metal salt (eg, zinc acetate, etc.).

A conventionally known photosensitive layer (1-) is provided as a photosensitive layer for the 28th plate on the upper l/c of the support for the + plate printing plate according to the present invention, and a photosensitive lithographic printing plate (hereinafter referred to as I) S plate ) can be obtained, this? The lithographic printing plate obtained by the plate-making process has excellent properties.

The composition of the photosensitive layer is (a) composed of an azo resin and a binder, (b) composed of an o-naphthoquinone diand compound, (C) composed of an and compound and a binder, and (d) ethylenically unsaturated. 40 monomer, a photopolymerization initiator, and a local molecular binder; (e) -C1 (=(?)() in the main chain or side chain of the polymer;
-(: those made of photocrosslinkable polymers having a Q-group, etc.), details of which are described in U.S. Patent No.
It is explained in detail in the tO specification. Such a photosensitive layer is coated according to the present invention and attached to the trap support at about θ, 7 to about 7 f.
/m, more preferably iL, O1o, s~μ9/17t.

〔Effect of the invention〕

According to the method for manufacturing a support for a lithographic J printing plate of the present invention, the chemical graining step can be completed in a short time, and the amount of aluminum etched is smaller than in the conventional chemical graining method. Is it a homogeneous grain? It has the distinct advantage that it can be formed on the surface of an aluminum plate. Therefore,
In the case of industrial rush currents, a great effect can be obtained in that the raw I) U speed is fast and the burden of maintaining the composition k of the corrosive liquid within a certain allowable ψα range is small. Further, a support for a 7ζ printing plate produced according to the present invention is used to prepare a 1ζ lithographic f-JJ printing plate 1:1, and a mechanical graining method?
It has also been found that it has the unexpected effect that the non-image area is less stained compared to lithographic printing plates made from trap lithographic printing plate supports manufactured using this technology.

〔Example〕

Hereinafter, the present invention will be further explained with reference to Examples. In addition, in winter in the examples, unless otherwise specified, it is heavy duty? show.

Example 1 Aluminum plate with a thickness of 0.211 m and 1 m (material: JIS
Aloso) In an aqueous solution containing ferric chloride of 23o and phosphoric acid of jO, the centerline average roughness was 0.3.
Chemically grained with VC immersion treatment to 0 μm [1]. Then 10% aqueous sodium hydroxide solution VCj00
The smut generated by the graining process was removed by immersion in C for 10 seconds, followed by neutralization cleaning with VC and 20 qb nitric acid to remove undissolved residue, followed by washing with water. Next, the front of the oxide film is /, s? in a polysulfuric acid aqueous solution. /m2, washed with water, immersed in an aqueous solution of sodium flat silicate VC70'C: for 7 minutes, washed with water, dried, and prepared as a support (1).

A photosensitive solution having a uniform composition was coated on the support thus obtained and dried for two minutes to form a photosensitive layer. The dry coating weight of the photosensitive layer was λ or 7 m.

Photosensitive liquid The photosensitive lithographic printing plate made in this way is coated with a bright negative film k )+u I,te,/ in a vacuum printing frame.
From the phase separation of tn, the plate was exposed to SO light for seconds using a 3KW metallolide lamp, and then subjected to the phenomenon of composition F, and gummed with an aqueous gum arabic solution to prepare a lithographic printing plate.

The developer thus prepared was printed onto trap printing plates in the usual manner. The results are shown in Table 1 below.

Comparative Example 1: 30% ferric chloride and 0% hydrochloric acid as a corrosive solution for chemical graining. A support Ak was prepared in exactly the same manner as in Example 1 except that an aqueous solution containing the following was used. Using this support, the steps from coating the photosensitive layer, exposure, development*, gumming to printing were carried out in the same manner as in Example 1. The results are shown in Table 7 below.

Comparative Example 2 Aluminum plate 2t, t with thickness O8, 2μm/rn
o.

Mechanical graining was carried out with a rotating nylon brush in a suspension of mesh and water. This grained aluminum i 10% sodium hydroxide aqueous solution V
It was immersed in cjO0C for up to seconds, and the rJJf calendar agent and aluminum debris that had penetrated into the aluminum surface during grain molding were removed, the surface was leveled, and the trap was washed with running water.
It was neutralized with 0% nitric acid and washed with water. Next, anodize in a vcir% sulfuric acid water bath solution so that the amount of oxide film becomes /, 397 m2.
Immerse at 00C for 7 minutes, wash with water, and dry to form support CB)
Prepared for '. Exposure 1 - The steps from coating, exposure, sanding, and printing were carried out in the same manner as in Example 1. The result is the result of the first straw>1-1. It can be seen that the support produced by Akira Motomoto has a smaller decrease in the weight f- of the support than Comparative Example 1Yζ. This means that the reduction in thickness due to chemical graining is small. Furthermore, it can be seen that when the support of the present invention is used as a printing plate, the non-image area is less likely to be smudged than the mechanically grained support of Comparative Example 7ζ.

Rush current-12 ノV-jθ,-! 4Lns/zn aluminum plate (material 11: JIS Aiosθ)? μθ ferric chloride and 6
It was treated with SOoC in an aqueous solution containing #acid of θ so that the center line average roughness was 0.3 μm, and was chemically grained. Next, add 500c to the sodium hydroxide aqueous solution.
The smut generated by the above-mentioned grain molding was removed by immersion in water for 10 seconds, and the mixture was further neutralized and washed with VCλo% nitric acid to remove undissolved residues, and then washed with water. Dip in C for 30 seconds, wash with water, dry, and use as a support [λ] and plate 1ζ.

A photosensitive solution having the following composition was coated on the support thus obtained, and dried to form a photosensitive layer. The dry coverage of the photosensitive layer was 1,377 m2.

Photosensitive liquid The photosensitive lithographic printing plate thus prepared was placed in a trap position at a distance of 7 m using a JKW metal halide lamp as 51j, and a positive transparent image was made for 60 seconds;
-U Th After exposure, develop g with the following composition (liquid temperature,
2j0U)i was used, and the second layer was gummed.

The degree of contamination of h6 was determined, and the results are shown in Table 2 below [7
Ta.

Comparison P Reli 3 An aqueous solution containing 4tO% diferric chloride and t, toqb of nitric acid 2 as a corrosive solution for chemical graining? Support [U) 2 was prepared in exactly the same manner as in Example I'l+2 except that a trap was used. This support was photosensitive 1-coating exposure, development, gumming η
・Printing was carried out in the same manner as in Example 2. From the results shown in Table 2, the support according to the present invention showed less weight loss than Comparative Example 17, that is, the thickness decreased due to graining. It can be seen that the non-image area is less stained and the printing durability is also excellent.

Claims (1)

[Claims] /) A method for producing a support for a lithographic printing plate, which includes a step of chemically graining the surface of an aluminum plate with an etching solution, wherein the etching solution is an aqueous solution containing ferric chloride and phosphoric acid. Something? The manufacturing method is characterized by: 2) A method for producing a lithographic printing plate support comprising steps of chemically graining the surface of an aluminum plate with an etchant and anodizing the surface, the etchant being an aqueous solution containing ferric chloride and phosphoric acid. The manufacturing method is characterized in that: