JPS63112193A - Manufacturing method of aluminum substrate for lithographic printing - Google Patents

Abstract

PURPOSE:To provide a durable hydrophilic surface in non-printing areas and enhance adhesion of a photosensitive layer to an aluminum plate, by providing a resin film on the surface of an aluminum plate or aluminum alloy plate by applying an aqueous solution containing as a main constituent an organic high- molecular weight material which shows a cationic property in aqueous solutions. CONSTITUTION:A resin film is provided on the surface of an aluminum plate by applying an aqueous solution containing as a main constituent an organic high molecular weight material showing a cationic property in aqueous solutions, thereby producing an aluminum base for planography. The aluminum preferably has a surface previously subjected to mechanical graining, anodizing or a chemical conversion treatment to enhance adhesion of the resin film thereto. A organic high-molecular weight resin to be used as the organic high-molecular weight material comprises, as a main constituent, a high molecular weight resin having a multiplicity of amino groups (-NR2, wherein R is H, Oh or an alkyl) in the molecule thereof. Among the resins, those which give a particularly favorable result include a water-soluble polyamide resin and a cationic acrylic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing an aluminum substrate for planographic printing. More specifically, an aluminum or aluminum alloy plate used for a lithographic printing plate (in the present invention, aluminum and aluminum alloy plates are collectively referred to as aluminum plates hereinafter) has a hydrophilic surface and has improved printability. [Prior art] Aluminum plates used as base materials for producing lithographic printing plates are often 0.1 to 0.4 mm thick, and the surface is coated with oil. Since it is attached, degrease it,
use. In some cases, aluminum plates are coated with a photosensitive liquid on a smooth surface without any particular graining, but since printing durability is poor, for purposes other than light printing, brush polishing with abrasive sand or surface roughening by electrolysis is used. Alternatively, after pre-treatment such as anodization, washing with water and drying is performed to obtain an aluminum substrate.

Thereafter, a photosensitive liquid is applied and a matting agent is applied to the surface to form a lithographic printing plate.

The aluminum plate has a rough surface for the purpose of improving the adhesion with the photosensitive layer coated on the aluminum plate and improving the water retention of the non-image area of the lithographic printing plate produced using it. However, with this treatment alone, these surfaces change from hydrophilic to hydrophobic over time.

Therefore, it is not desirable for lithographic printing plates for obtaining extremely high printing plate numbers. That is, as the surface changes to a hydrophobic surface, oil-based ink tends to gradually accumulate in non-printing areas, and a phenomenon called so-called toning or scumming appears, resulting in poor printability. To eliminate this toning or scumming, the surface of the aluminum substrate must be inert and have a persistent hydrophilic surface.

One method for imparting a hydrophilic surface is to treat an aluminum plate with an aqueous alkali silicate solution.

The thus treated aluminum substrate is coated with a photosensitive layer such as a photosensitive water-soluble diazo resin to form a lithographic printing plate, but when a light beam is exposed onto the plate through a base paper or a negative, the exposed portions of the photosensitive layer react. , forming an image of a hydrophobic resin. It is characterized in that the unexposed areas are washed away with a developer such as an alkaline solution, leaving the silicate layer portions with a hydrophilic surface imparted to the non-image areas on the aluminum surface.

[Problems to be Solved by the Invention] Treatment with an aqueous alkali silicate solution is useful for imparting hydrophilicity to the aluminum surface, but the hydrophilicity does not last long enough, and the photosensitive layer coated thereon is This has disadvantages such as poor adhesion with the photosensitive layer and short life of the photosensitive layer.

The present invention has been made in view of the above problems.It forms a long-lasting hydrophilic surface in the non-printing area, improves the adhesion of the photosensitive layer to the aluminum plate, and provides a robust printed surface. An object of the present invention is to provide a method for manufacturing an aluminum substrate for lithographic printing.

[Means for Solving the Problems] The present invention is a method for achieving the above object, and the gist thereof is as follows. Namely, (1) a method for producing an aluminum substrate for lithographic printing, which comprises coating the surface of an aluminum plate with an aqueous solution mainly composed of an organic polymeric material exhibiting cationic properties in an aqueous solution to form a resin film; and (2) the resin film is a resin film formed by applying an aqueous solution of an aqueous polyamide resin exhibiting cationic properties in an aqueous solution, and (3) the resin film is a resin film formed in an aqueous solution. (1) above, which is a resin film formed by coating an aqueous solution of a cationic acrylic resin exhibiting cationic properties.
(4) The resin film is a resin film formed by applying an aqueous solution containing a compound of a tetravalent metal element to an organic polymeric material exhibiting cationic properties in an aqueous solution.
), and (5) the method of (1) above, in which the resin film is coated with an aqueous solution containing colloidal silica on an organic polymeric material exhibiting cationic properties in an aqueous solution; ) The aluminum plate is an aluminum plate whose surface has been mechanically roughened in advance (1) to (5).
), and (7) the aluminum plate is an aluminum plate on which an anodic oxide film has been previously formed on its surface or on the surface of the mechanically roughened aluminum plate shown in (6) above. (1) to (6), and (8) an aluminum plate is applied to the surface of the aluminum plate or the mechanically roughened surface of the aluminum plate shown in (6) above, or in the method (7) above. (1) to (7) above, which are aluminum plates on which a chromate conversion film has been previously formed on the surface on which the anodic oxide film has been formed as shown.
).

[Function] In order to improve the adhesion with the resin film, the aluminum plate used in the present invention preferably has its surface mechanically roughened, anodized, or chemically treated in advance.

Anodic oxidation is carried out using an electrolyte such as sulfuric acid, oxalic acid, phosphoric acid, or chromic acid. Generally, the electrolyte is 1 to 80% by weight5, the bath temperature is 5 to 70℃, the current density is 0.5 to 60 ampere/
dra'', a voltage of 1 to 100 V, and an electrolysis time of 30 seconds to 50 minutes. Chemical conversion treatment methods that can be used inventively include alkali-chromate method, chromate method, phosphoric acid method, etc. There are the chromate method and the resin film treatment method containing chromic acid, and the zinc phosphate method and the phosphate film chemical conversion treatment method for titanium and zircon, which do not contain chromium. Chromate conversion coatings such as acid chromate are simple and common.

The organic polymer resin that exhibits cationic properties in the aqueous solution used in the present invention has many amino groups (-NR2:R is H
, OH or alkyl group).

A resin having -NR in its resin skeleton exhibits cationic properties as -NHR- by an inorganic or organic acid in an aqueous solution, and is dissolved or dispersed in an aqueous solution.

A resin that exhibits cationic properties and is dissolved or dispersed in an aqueous solution has the property of losing its charge in an alkaline solution or with an anionic compound, and precipitating or becoming insolubilized to precipitate. It also has the property that the resin associates with polyvalent metal ions, becomes insolubilized, and precipitates.

Therefore, on a chemical conversion coating consisting of polyvalent metal ions such as zinc, chromium, and aluminum, and anions such as phosphate ions and chromate ions, these polyvalent metals and anions combine with the resin to form an organic polymer resin. Forms a film. The resin film exhibits water wettability and is excellent in hydrophilicity, but in order to further improve hydrophilicity, carboxyl groups, hydroxyl groups, amino groups, etc. can be introduced into the resin skeleton.

Typical examples of these resins include water-soluble polyamide resins, polyethyleneimine, cationic polymeric surfactants, and resins used in cationic electrodeposition paints, which show particularly good results. Examples include water-soluble polyamide resins and cationic acrylic resins.

In addition, according to the present invention, a salt of a tetravalent metal such as silicon, zirconium, titanium, or tin is added to an organic polymer resin solution that exhibits cationic properties in an aqueous solution, and then an inorganic or organic acid is added. A polymer resin film formed by preparing a treatment liquid with a pH adjusted to a range of 2 to 7 and applying this treatment liquid can have improved adhesion and hydrophilic performance compared to a resin-only coating.

In addition, the resin coating according to the present invention using a liquid containing colloidal silica having a cationic charge that can be uniformly dispersed in an organic polymer resin solution exhibiting cationic properties in an aqueous solution is a resin-only coating. Corrosion resistance and hydrophilic performance can be further improved.

The most effective inorganic acid that can be used in the present invention is phosphoric acid. Moreover, various monobasic acids, dibasic acids, and polybasic acids can be used as the organic acids.

The processing temperature of the above-mentioned processing liquid in the present invention is room temperature to 80°C.
This is usually set at room temperature (10 to 40°C), but it is also possible to increase the bath temperature for the purpose of improving workability. A temperature of 80° C. or higher is disadvantageous because water evaporates quickly and the concentration of the treatment liquid tends to change.

A photosensitive planographic plate can be obtained by further coating a photosensitive material on the surface of the aluminum substrate thus obtained.

As the photosensitive material, currently available commercially available materials can be used. The general basic composition is (1) main polymer, (
2) a vinyl polymer, (3) a photopolymerization initiator, (4) a thermal polymerization inhibitor, and (5) other additives, and the combination of compounds and blending ratios varies depending on the purpose of use.

(1) Examples of the main polymer include polyamide, water-soluble polymer, cellulose, unsaturated polyester, and synthetic rubber.

(2) Vinyl polymers include acrylic ester, acrylic amide, and methacrylic ester.

and methacrylic acid amide.

(3) As the photopolymerization initiator, radical polymerization initiators such as benzophenone, benzoin, ketal, thioxanthone, and anthraquinone are used.

(4) As the thermal polymerization inhibitor, hydroquinone, methoxyphenol, and N-nitrosohydroxylamine are used as an inhibitor for stability during storage and polymerization due to heating during formation of the photosensitive layer.

(5) Other additives include dyes and pigments for coloring, plasticizers for changing the physical properties of the photosensitive layer, and solvents for improving coating workability.

[Example] The present invention will be explained below with reference to Examples.

Example 1 A chromate chromate film conversion treatment agent for aluminum (registered trademark Bonderite 7132 manufactured by Nippon Parriki Rising Co., Ltd.) was diluted with water at a ratio of 72 gIQ,
This aqueous solution was maintained at 50°C, and a pre-cleaned aluminum plate (A 1050) was placed in the aqueous solution for about 2 hours.
After soaking for 1 minute, the amount of chromium deposited is approximately 100 mg/m
A chromic acid chromate conversion film was formed, and then the aluminum plate was washed with water. After that, a water-soluble polyamide resin (trade name: AQ Nylon, Toshishiku Co., Ltd.) that exhibits cationic properties in an aqueous solution was applied at a rate of 20 gIQ. After dissolving the aluminum plate and coating it by dipping in a treatment solution with a bath temperature of 30'C adjusted to pH 3.0 with phosphoric acid, it was dried in a hot air drying oven for 12 hours.
By carrying out a dry baking process at a temperature of 0° C. for 3 minutes, a water-wettable polyamide resin film was formed on the chromate conversion film with a coating weight of about 0.5 g/m''.

On the aluminum substrate obtained in this way, a photosensitive layer consisting of a diazo compound and an acrylic copolymer is deposited for approximately
μ was formed.

The aluminum plate thus obtained was exposed to light.

Development was performed using a weakly alkaline developer.

After wiping the surface of the aluminum plate after development with water, when it was roll-coated with oil-based printing ink, the resin surface of the photosensitive layer blended well with the ink, but the non-printing areas where the photosensitive layer had been removed repelled the oil-based printing ink well. .

In order to confirm the hydrophilicity of this non-printed part, we measured it using a gonio-type contact angle measuring device, and found that the water contact angle was approximately 10 degrees, a good result. There was no increase in the contact angle.

On the other hand, even after the product of the present invention was immersed in running water for about one month, there was almost no increase in the contact angle of water, indicating that the water wettability of the product of the present invention could be maintained well over a long period of time without deterioration.

To evaluate the adhesion of the photosensitive layer to the substrate, a test was conducted in which a 1 mm square scratch reaching the substrate was made in the photosensitive layer, a cellophane tape was attached, and then it was strongly peeled off. The results showed that there was no peeling of the photosensitive layer and good adhesion was observed.

The test results of Example 1 are summarized in Table 1 below.

Comparative Example 1 In this comparative example, a chromate conversion coating was formed in the same manner as in Example 1, but no resin coating treatment was performed. Comparative Example 1 was treated and tested in the same manner as Example 1, but as shown in Table 1, the initial water wettability was lower than that of Example 1.
However, as time passed, the contact angle of water increased and the water wettability significantly decreased.

Example 2 Phosphate chromate film chemical conversion treatment solution for aluminum (AB agent 48g of registered trademark Bonderite 701/
A pre-cleaned aluminum plate was immersed for 1 minute in a mixed solution of Q and 27 g/Q of AC agent also Bonderite 701 (manufactured by Nippon Parriki Rising Co., Ltd.) at a temperature of 50°C to determine the amount of chromium deposited. A phosphoric acid chromate film of 150 mg/m2 was formed and then washed with water. After that, the aluminum plate was placed in an aqueous solution of 20 g/u of a quaternary salt compound of vinylpyrrolidone and dimethylaminoethyl methacrylate copolymer (cationic acrylic resin, trade name Copolymer 937, GAF Corporation), pH 6.5, bath temperature 35°C. After immersing it, it was dried and baked in a hot air drying oven at a temperature of 120°C for 30 minutes.

As a result, the resin film was formed on the phosphoric acid chromate conversion film with a coating weight of about 0.5 g/m 2 .

The aluminum substrate subjected to this treatment was subjected to the same test as in Example 1, and the results are shown in Table 1. The water wettability was maintained well over a long period of time without deterioration, and the adhesion of the photosensitive layer was It was also good.

Comparative Example 2 As shown in Table 1, when the phosphoric acid chromate chemical conversion coating alone was treated in the same manner as in Example 2 and did not form a resin coating, the contact angle of water increased over time and the water wettability decreased. decreased.

Example 3 A chromate chromate conversion film was formed on the surface of an aluminum plate in the same manner as in Example 1, and then washed. Subsequently, 6 g of zirconate hydrogen fluoride complex salt was added to the aqueous solution of 20 g IQ of the water-soluble polyamide resin used in Example 1.
/Q was added and dissolved, and the aluminum plate was dip-coated in an aqueous solution with a bath temperature of 30°C adjusted to pH 3 with phosphoric acid,
Dry and bake for 30 minutes at 120℃ in a hot air drying oven, resulting in approximately 0.
．． A resin film with a coating weight of 3 g/m2 was formed.

Example 1 Confirming the performance of aluminum substrates subjected to this treatment
The results obtained using the same method as above are shown in Table 1, and the water wettability was maintained well over a long period of time without deterioration, and the adhesion of the photosensitive layer was also good.

Examples 4 to 6 A chromate conversion film was formed on the surface of an aluminum plate in the same manner as in Example 1, and then washed. Subsequently, three kinds of mixtures were prepared by adding cationically charged dispersive colloidal silica (registered trademark Snowtex AK, Nissan Chemical) to an aqueous solution of 20 g IQ of the water-soluble polyamide resin used in Example 1 at a ratio of 2 g IQ, 5 g IQ, and Log, l. The aluminum plates were immersed in each of the mixed solutions at room temperature, and then subjected to a drying and baking process at 120°C for 30 minutes in a hot air drying oven. A polymer resin film containing colloidal silica was formed with a coating weight of 0.5 g/m''.

Example 1 Confirming the performance of aluminum substrates subjected to this treatment
The results obtained using the same method as above are shown in Table 1, and the water wettability was maintained well over a long period of time without deterioration, and the adhesion of the photosensitive layer was also good.

Comparative Examples 3 to 5 A chromate chromate conversion film was formed in the same manner as in Example 1, and then an anion-dispersible acrylic resin emulsion (registered trademark Tokutsuru N-142) was formed.
, Toyo Ink Manufacturing) Three types of mixed liquids in which anionic charge dispersive colloidal silica (registered trademark Snowtex O2 Nissan Chemical) was added to an aqueous solution with a resin solid content concentration of 20 g IQ at a ratio of 5 g/Q, Log/Ω, and 20 g/Q. The aluminum plates were dip-coated in each of the mixed solutions at room temperature, and then dried and baked in a hot air drying oven at 120°C for 30 minutes.

Polymer resin films containing colloidal silica were formed with adhesion amounts of approximately 0.4, 0.5 and 0.6 g/m2, respectively. The performance of the aluminum substrate subjected to this treatment was confirmed in the same manner as in Example 1, and the results are shown in Table 1. As shown in Table 1, in Comparative Example 3.4.5, it is necessary to increase the proportion of colloidal silica in the resin in order to exhibit good water wettability, but on the other hand, increasing the proportion of colloidal silica added , the adhesion of the photosensitive layer tended to decrease.

Example 7 Aluminum plate (A105) with a thickness of 0.2 mm
0) was immersed in an alkaline etching cleaning solution mainly containing 2% caustic soda at 60° C. for 1 minute, and then washed with water. Next, an anodic oxidation treatment was performed in a 15% sulfuric acid aqueous solution at a DC voltage of 20 μm for 1 minute, followed by washing with water. Thereafter, a water-wettable polyamide resin film was coated on the approximately 1μ anodic oxide film with a coating weight of approximately 0.4 g/+a'' under the same conditions using the treatment solution containing water-soluble polyamide used in Example 1. formed.

The aluminum substrate subjected to this treatment was subjected to the same test as in Example 1, and the results are shown in Table 1. The water wettability was good with no deterioration over time, and the adhesion of the photosensitive layer was also good.

Example 8 After roughening the surface of the same aluminum plate as in Example 7 with Kenreki sand, 0.4 g of a water-wettable polyamide resin film was applied with the treatment solution containing the water-soluble polyamide used in Example 1. It was formed with an adhesion amount of /m2. Table 1 shows the results of the same tests as in Example 1 performed on the aluminum substrate treated with this treatment, and the water wettability was maintained well, and the adhesion of the photosensitive layer was also good.

[Effects of the Invention] The aluminum plate for lithographic printing of the present invention has a long-lasting hydrophilic surface formed in the non-image area after image formation, and also has good adhesion of the photosensitive layer, so it can be used in a large number of sheets. It is suitable for lithographic printing and has great industrial effects.

Claims (1)

[Scope of Claims] (1) A lithographic plate comprising a resin film formed by coating the surface of an aluminum or aluminum alloy plate with an aqueous solution mainly containing an organic polymeric material exhibiting cationic properties in an aqueous solution. Method for producing an aluminum substrate for printing (2) The method for lithographic printing according to claim 1, wherein the resin film is a resin film formed by applying an aqueous solution of a water-soluble polyamide resin that exhibits cationic properties in an aqueous solution. Method for manufacturing an aluminum substrate (3) The method for manufacturing an aluminum substrate according to claim 1, wherein the resin film is a resin film formed by applying an aqueous solution of a cationic acrylic resin that exhibits cationic properties in an aqueous solution. (4) P in which a tetravalent metal element compound is added to an organic polymer material whose resin film exhibits cationic properties in an aqueous solution.
A method for producing an aluminum substrate for lithographic printing according to claim 1, wherein the resin film is formed by applying an aqueous solution in which H is 2 to 7. (6) The method for producing an aluminum substrate for lithographic printing according to claim 1, which is a resin film formed by coating a polymeric material with an aqueous solution containing colloidal silica. The method for producing an aluminum substrate for lithographic printing according to claim 1 or 2 or 3 or 4 or 5, which is an aluminum or aluminum alloy plate whose surface has been mechanically roughened in advance. (7) Claim 1 or 2 or 3 or 4 or 5, wherein the aluminum or aluminum alloy plate is an aluminum or aluminum alloy plate on which an anodized film has been previously formed.
The method for manufacturing an aluminum substrate for lithographic printing according to item 1 or 6, wherein the aluminum or aluminum alloy plate is an aluminum or aluminum alloy plate on which a chromate conversion film has been previously formed on the surface of the aluminum or aluminum alloy plate. The method for producing an aluminum substrate for lithographic printing according to item 1 or 2 or 3 or 4 or 5 or 6 or 7.