JPH0237316B2 - INSATSUHANYOKIBANOYOBI INSATSUHAN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Lithographic printing, which is said to be the mainstream of printing, basically uses an aluminum plate as a substrate, and prints an image on it using a hydrophobic and lipophilic resin. In this case, the hydrophilicity of the aluminum surface in the non-image area is used to form a water film on the non-image area to prevent oil-based ink from adhering, and printing is performed by applying ink only to the lipophilic resin image area. Therefore, the balance between the hydrophilicity of the aluminum surface, the lipophilicity of the resin in the image area, the ability to form a water film during printing, and the receptivity of ink determines the printing condition, and the accuracy, clarity, and ink transferability of the printed image are determined by the balance. The quality of printed matter, such as scumming, printing durability, and gloss of printed matter, and printing workability are greatly influenced by the properties of the aluminum surface and the properties of the resin used to draw images on it.

Many of the printing plates currently in use have their aluminum surfaces mechanically polished to create fine irregularities, or electrically anodized to roughen the aluminum surface and expand its surface area. It not only provides adsorption and water film forming properties, but also mechanically strengthens the adhesion of the lipophilic resin that forms the image area.

Furthermore, in order to increase the hydrophilicity of the aluminum surface and improve water retention, various inorganic acids such as sulfuric acid, phosphoric acid, caustic soda, sodium phosphate, water glass, etc.
Other methods have been proposed, such as surface treatment with an inorganic alkali to create a finely rough surface on the aluminum surface, or a method of sealing the aluminum after anodizing.

However, although the methods proposed to date are effective in improving the hydrophilicity of aluminum surfaces and forming water films during printing, some of the methods may cause corrosion spots to appear on the aluminum surface or cause uniform roughness. In addition, there were disadvantages such as difficulty in surface-forming operations, and poor adhesion of the lipophilic resin that forms the image, reducing the printing durability of the printing plate.

From a scientific point of view, it is not easy to increase the hydrophilicity of the aluminum surface, maintain its activity and stability, and further strengthen the adhesion with hydrophobic and lipophilic resins. To use resin to maintain high resolution of optical images and express them down to minute points, to improve developability, to perfect adhesive fixation of minute images, and to maintain ink receptivity and printing durability. This means that many conflicting developments must be resolved and completed at the same time.

The present invention solves all of these problems. That is, the aluminum surface is treated with a mixed aqueous solution of a polyamine compound and a polycarboxylic acid compound, and the polyamine compound used is one of polyalkylene polyamines such as ethylene diamine, dipropylene triamine, and triethylene tetramine, and has a polymerization degree of 2 or 20. Water-soluble materials are used within a range of degrees. In addition, polycarboxylic acid compounds include water-soluble carboxylic acids having two or more carboxyl groups such as malic acid, maleic acid, citric acid, succinic acid, and malonic acid, as well as polyols having two or more hydroxyl groups such as glycerin, Condensation products with trimethylolpropane, pentaerythtol, ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, etc., which have an acid value of 10 or more, preferably 50 or more, and are water-soluble are used.

Further, as the polyamine compound, a reaction product of a polyamine and a carboxylic acid compound can also be used. Furthermore, as the polycarboxylic acid compound, a reaction product of a polycarboxylic acid and a polyamine can also be used.

Add a mixture of such a polyamine compound and a polycarboxylic acid compound to an aqueous solution at 20°C to 80°C.
When aluminum is immersed for 2 seconds to 2 minutes at a temperature in the temperature range of , the surface of the aluminum becomes largely hydrophilic.
When the aluminum surface is polished or anodized, the effect is even more remarkable, and a substrate suitable for printing plates can be obtained. conventional inorganic acids,
Compared to the inorganic alkali treatment method, the method of the present invention uses organic substances, so it not only corrodes the aluminum surface, but also hydrophilic organic substances are reacted and adsorbed to the aluminum surface. The resulting aluminum plate has good affinity with the photosensitive resin that photosensitively forms the lipophilic image area, making it easier to apply the photosensitive resin, and the adhesion of the lipophilic image area after photosensitive image formation is also good. While becoming
It does not inhibit leaching of non-photosensitive areas by the developer.

As a method for producing a printing plate using the substrate of the present invention, a photosensitive agent composed of a known photosensitive composition is applied to the surface treated with a polyamine compound and a polycarboxylic acid compound, and a photosensitive layer is provided. , by exposing the image to light and then removing the non-image area, or by drawing an image on the treated surface using a lipophilic substance such as crayon or asphalt.

Since the substrate of the present invention has excellent hydrophilicity, it is possible to attach the printing plate thus prepared as is to an offset printing machine and print on it. There is nothing wrong with adding operations such as chemical treatment or gumming.

A printing plate having an aluminum surface treated with the polyamine compound and polycarboxylic acid compound of the present invention does not necessarily have to be coated with a photosensitive agent such as a photosensitive resin or a There is no need to draw an oil-based image, and by processing a printing plate with an image created by a normal conventional method, the hydrophilicity of only the aluminum substrate surface in the non-image area is improved and the non-image area is printed. It can also improve the formation of a water film during printing and improve the printing operability and printing performance of the printing plate.

Example 1 (% is weight % below) The surface of an aluminum plate with a thickness of 0.3 mm was polished by the same ball-sharpening method as in the production of ordinary printing plate substrates, and the surface was roughened. Acid value obtained by condensing 5% triethylenetetramine, 3 moles of citric acid, and 2 moles of glycerin at 165℃ for 1 hour in a nitrogen atmosphere.
1 at 60℃ in a solution of 5% polymer of 402 and 90% water.
After soaking for 80 minutes and thoroughly washing with 30℃ warm water,
Dry for 10 minutes in a dryer at °C. This aluminum plate was uniformly coated with the following photosensitive resin liquid and dried in a dryer at 80°C for 10 minutes to produce a PS plate having a thickness of 2.5 gr/m ² of dry resin weight.
A negative photographic film was closely attached to this PS version and printed with a 2kw high pressure mercury lamp, and 0.5% of sodium phosphate was used.
% aqueous solution, washed with water, and dried to prepare a printing plate. This plate has good hydrophilicity and water film forming properties in non-image areas, and printing tests have shown that it has good printability and 20%
It was possible to print on a consistent basis.

As a comparative example, the same photosensitive resin liquid was applied to a polished aluminum plate that had not been subjected to the treatment of the present invention, and a printing plate was prepared using the same method. Background smearing occurred due to poor formation, and printing was continued by increasing the amount of water, but after about 100,000 prints, peeling was observed in the details of the plate image.

(Photosensitive liquid preparation method) The following monomer composition solution was mixed with isopropyl alcohol.
Polymerization was carried out by dropping 100 g of the solution, and then 30 g of acrylonitrile, 30 g of butyl acrylate, 30 g of acrylic acid, 10 g of styrene, 3 g of N,N'-azobisisobutyronitrile, 30 g of glycidyl methacrylate, and trimethylbenzylammonium hydroxide as a catalyst were added. In addition, an addition reaction was carried out (addition rate to carboxyl group: 68
%) 250g of the prepared polymer solution, 1300ml of n-butyl alcohol, 200ml of benzene and 200ml of ethyl acetate.
ml, pentaerythol tetramethacrylate 25
g, 0.9 g of 2-ethyl anthraquinone, and 0.1 g of benzoin methyl ether, and stir well to mix.

Example 2 A 3% acid value 112 polymer was prepared by reacting an aluminum substrate for printing with a thickness of 0.3 mm, which had been subjected to ordinary brush polishing, with equimolar amounts of malic acid and ethylene glycol at 160°C for 2 hours in an N ₂ atmosphere. , immersed in an aqueous solution of 6% diethylenetriamine at a temperature of 50° C. for 1 minute, then washed with water and dried. A photosensitive resin liquid was applied to this material in the same manner as in Example 1 to prepare a printing plate. Using this printing plate, we were able to smoothly print 100,000 copies. The same test was conducted without using the method of the present invention, but as in Example 1, under the same printing conditions, water film formation in the non-image area was poor and scumming occurred.

Example 3 A printing substrate made of an ordinary brushed aluminum plate whose surface was anodized was dehydrated with ethylene glycol and citric acid in a molar ratio of 1:2 at 135°C for 1 hour, and then reacted at 165°C for 1.5 hours. acid value
532 polymer and 5% tetraethylenepentamine for 30 seconds at a temperature of 70°C, and then washed with water and dried. A positive diazo photosensitive liquid (manufactured by Ueno Chemical) was applied to this material and dried to create a PS plate with a dry resin layer of 2 g/m ² .The image was printed and developed in the usual manner to create a printing plate. did. Printing was possible with this version without any problems.

For a comparative test, the present invention was not carried out, and the same photosensitive liquid was applied to a printing substrate made of an anodized brushed aluminum plate, and a printing plate was prepared in the same manner as usual.

When we applied water to the surface of both printing plates in the normal printing start condition and immediately applied ink to print, we were able to print similarly to both, but after applying water to the surface,
When ink was applied to the plate according to the present invention after a few minutes, the ink did not adhere to the non-image area, and the ink applied only to the image area, resulting in smooth printing.However, the conventional anodized aluminum plate not according to the present invention Ink adhered to the aluminum surface of the non-image area, causing scumming, resulting in poor printability.

Claims (1)

[Scope of Claims] 1. A printing plate substrate comprising an aluminum plate whose surface has been treated with a polyamine compound and a polycarboxylic acid compound. 2 Surface treated by immersion in an aqueous solution containing a polyamine compound and a polycarboxylic acid compound at a temperature range of 20°C to 80°C for 2 seconds to 120 seconds,
The substrate according to claim 1. 3 In a lithographic printing plate having an aluminum plate as a substrate and having an image area made of a lipophilic substance and a hydrophilic non-image area on the surface thereof, the hydrophilic non-image area is treated with a polyamine compound and a polycarboxylic acid compound. A printing plate characterized by a polished aluminum surface.