JPS5848896B2 - Heiban Insatsubanno Seihou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making lithographic printing plates in which a base covered with a hydrophilic layer is imagewise irradiated, thereby creating oleophilic image areas.

In the photomechanical production of lithographic printing plates, a copying material having a photosensitive layer is usually imagewise exposed to light and then developed with a suitable developer to obtain oleophilic image areas and hydrophilic non-image areas. .

The oleophilic image areas are usually those areas of the layer that remain after development, and the non-image areas are those areas that are removed by development of the base surface.

For development, organic solvents or alkaline or acidic aqueous solutions are generally used, depending on the nature of the layer Q).

Working with this solution must always be carried out while observing the prescribed safety regulations, and additional measures such as distillation, neutralization, etc. are necessary to remove the used developer.

Therefore, it is desirable to eliminate the use of such developers.

It is also already known, for example from Example 4 of German Patent Specification No. 1 160 733, to develop exposed presensitized offset printing plates by wiping them with pure water.

However, in this case it is necessary to use photosensitive copying layers which have a limited shelf life and, if stored for too long, can no longer be developed with pure water, although copying is still possible.

In any case, in this case too, for example, diazonium salts, acids,
The washed out portions of the photosensitive layer containing metal salts etc. must be removed.

Furthermore, German patent application P 22 31 815.6 proposes irradiating a recording material consisting of a base and a non-photosensitive layer with electrons and developing it with water or an aqueous solution.

According to the method described here, offset printing plates can be produced.

The object of the present invention is to propose a method for producing lithographic printing plates by image-wise irradiation O, without any need for photosensitive materials and development steps.

The object of the invention is a method for producing lithographic printing plates in which a layer covered base is imagewise irradiated.

A feature of the method is the use of a base with a non-photosensitive hydrophilic layer, the imagewise irradiation of the layer with an electron beam, and the printing of the resulting material directly on a lithographic printing press.

The method of the present invention discloses a new and surprisingly simple facility for producing lithographic printing plates.

The recording material used here is insensitive to daylight and artificial light and to aging.

There is almost no limit to storage town Noh.

The only processing step is the image-wise irradiation of the material with an electron beam.

In this case, the hydrophilic surface layer of the irradiated area hardens, so that it becomes hydrophobic or lipophilic and absorbs the printing ink.

The irradiated plate is immediately placed in an offset printing press without further treatment and applied with oil-based or fatty printing ink and fountain solution in the conventional manner.

In this case, if the initial hydrophilic surface layer is water-soluble, this layer is removed by dampening water.

In this case the underlying base surface must also be hydrophilic.

If the hydrophilic layer is insoluble in water, removal of the layer by dampening water will hardly occur and the non-irradiated areas will serve directly as image support.

In the case of a highly hydrophilic layer, no fountain solution is required in an offset printing press, ie it can be printed by a dry offset method.

Because permanent oleophilization of hydrophilic surfaces is achieved by electron irradiation, very high plate numbers can often be achieved.

The hydrophilic layer in the present invention can include various layers and surfaces.

Layers of water-soluble organic substances suitable for forming thin amorphous homogeneous films form an important group, these being monomers or polymers.

Suitable water-soluble polymers are, for example, polyvinyl alcohol, polyvinylpyrrolidone, polyalkylene oxides, polyalkylene imines, cellulose ethers such as carboxymethyl cellulose or hydroxyethyl cellulose, polyacrylamides, polyacrylic acids, polymethacrylic acids, starches, wheat paste, dextrins, casein, gelatin, arabic gum and tannins.

Suitable heptamers or low-molecular water-soluble substances are, for example, rhodamine B1, water-soluble dyes such as methylene blue, eosin or triphenylmethane dyes, for example crystal violet, and the films described in DE-A-2036585. It is a low-molecular organic substance with a certain shape.

This includes in particular heptanomeric and olicomer carbohydrates and the reduced and oxidized parabolic compounds derived therefrom, as well as their esters, ethers and salts, such as arabite, sorbitol, pentaerythritol, dipentaerythritol, tetramethylolsicate. Pentanol, tetramethylolsichexanol, anhydroennea heptite, gluconic acid, galactonic acid, galacturonic acid, mucilage acid and its alkali metal or ammonium salts, glucose, galactose, fructose, mannose, arabinose, sutucarose, lactose, maltose , methylglucose, hydroxyethylglucose, satsucrose monourate, satsucrose monopalmitate, satsucrose mono-12-
This droxystearate, as well as humectants such as saponin 0, sodium salts of alkylated sulfoconocitric acids and alkylated arylsulfonic acids, polyglycols, polyglycol alkylphenol ethers, polyoxyethylene-sorbitan fatty acid esters. and many others.

Inorganic and organic water-insoluble hydrophilic layers can also be used advantageously.

Suitable organic water-insoluble hydrophilic substances are, for example, association products of phenolic resins and polyethylene oxide as described in DE 14 47 978, hardened melamine formaldehyde resins according to GB 907 289. , or amine-urea-formaldehyde condensation resins or sulfonated urea-formaldehyde resins as described in German Patent No. 1 166 217, furthermore reticulated hydrophilic colloids, which may optionally contain hydrophilic inorganic pigments. Polyvinyl alcohol.

A layer of a water-insoluble hydrophilic inorganic pigment, such as a layer of pyrogenic silicic acid, embedded into the surface of a paper base, such as a plastic sheet or a paper with a plastic surface, is suitable.

A particularly important and advantageous group of water-insoluble hydrophilic layers for use according to the invention is obtained by reacting metal surfaces, in particular aluminum surfaces, with monomers or polymers of organic or inorganic acids or their salts or of certain complex acids or complex salts. This is the layer obtained.

Layers of this type are well known in the lithographic printing industry and are widely used in the pretreatment of metal bases for applying photosensitive layers.

Examples of suitable treatment agents are alkali metal silicates (see DE 907 147), phosphonic acids or their derivatives (DE 11).
34093 and 1160733), hexahalogenated titanium or -zircon (see German Patent Publication No. 1183919 and 1192668), organic polyacids (German Patent Specification No. 1091433)
), monomer carboxylic acids or their derivatives, phosphomolybdates, silicomolybdates, etc.

However, for purposes of the present invention, processing solutions in which the concentration of the desired substance is higher than would normally be used, particularly solutions of about 3 to 15 parts by weight, are generally used.

A suitable hydrophilic layer is a boehmite layer obtained by further anodizing an aluminum base and then treating it with hot water or a hot aqueous solution.

Generally, the hydrophilic layer according to the present invention must satisfy the condition that it can be wetted only by water when oil-based printing ink and dampening water act simultaneously in lithography or offset printing.

Layers of this nature are well known as base or support surfaces of lithographic printing plates.

Furthermore, as mentioned above, a layer of organic material that forms a water-soluble film also satisfies this premise.

Another condition that a hydrophilic layer for use in the method of the invention must satisfy is that upon irradiation with an electron beam, its surface tension towards water and printing ink is reduced by oil-based or fatty printing ink rather than by water. It is the ability to change so that it becomes wettable, ie hydrophobic or lipophilic.

Although no reliable explanation can be given regarding the nature of the change caused by electron irradiation, it is presumed that polymerization or network formation occurs while hydrophilic groups, particularly OH groups, are decomposed or converted into hydrophobic groups.

Hydrophilic layers whose hydrophilicity is not based on the presence of hydrophilic groups that can be reticulated, for example metal surfaces such as chromium or oxidized surfaces simply anodized to aluminum, are not suitable for use with the method of the invention. it is obvious.

Suitable bases for the hydrophilic layer are materials commonly used in lithographic printing, such as cellulose acetate-coated paper, zinc, magnesium, aluminum, chromium, copper, brass, steel, multilayer metals, plastics or plastic-metal composite sheets. .

In particular, surface roughening and (
or) anodized aluminum is used.

When using a water-soluble hydrophilic layer, the base surface needs to be permanently hydrophilic.

In other cases, C can be selected arbitrarily.

The hydrophilic layer is imagewise irradiated with electrons at a charge density of about 10@-8 to 10@-2 coulombs/d and an accelerating voltage of about 5 to 50 KV.

Depending on the sensitivity of the layer used, a time of 0.005 to 10 seconds per 2 cm range is required with an irradiation current intensity of 1 to 1000 μA.

The layer is also insensitive to ultraviolet light, so irradiation can be carried out in daylight.

The electron beam is focused on predetermined programmed dots and (
or) is advantageously controlled by a rask motion.

It is a particular advantage of the invention that the imagewise irradiated printing base can be immediately fixed on an offset printing press and printing can begin immediately.

Many of the coatings are known for presensitized offset printing plates, completely eliminating the need for development of the print base or removal of non-image areas, as is often done in expensive development machines that require large amounts of space.

This advantage satisfies the speed and economy requirements of offset printing.

When working with materials irradiated by offset printing machines,
Printing is carried out using the dry offset method or in the presence of a dampening solution.

When wetting hydrophilic non-image areas with dampening water, either no material is removed (water-insoluble layer) or a relatively small amount of material is removed by the dampening solution (water-soluble layer), which If it is easily decomposed, it can be immediately discharged as wastewater.

On the other hand, when developing conventional photosensitive layers, substances are often produced that are highly corrosive and require additional measures for their removal without contaminating the environment.

The invention will now be illustrated by way of example.

Values are by weight unless otherwise specified.

If li is selected as the volume part, 1 can be used as the weight part.

Example 1 Thickness 0. A 3 mm aluminum plate was mechanically roughened with a brush, immersed in a 20φ solution of trisodium phosphate for 3 minutes at 70 °C, washed with water, and treated with 70% nitric acid for 15 seconds.
After washing with warm water once more, it is treated with a 10% sodium silicate solution at 85°C for 3 minutes, washed with water, and dried.

A non-photosensitive, multi-year shelf-stable, coated aluminum plate is image-wise irradiated in high vacuum (approximately 10@-5 Torr) with medium velocity electrons having an energy of 10-15 KV.

Beam current strength is 200 μA, deflection speed is 1. 0se
It has a range of c/2 cm.

After irradiation, the printing plate is immediately fixed in an offset printing press and printing begins, with the irradiated areas absorbing the printing ink.

You can get thousands of prints. Example 2 A cold rolled bright aluminum coil is roughened in a continuous process, anodized, coated with a 5φ aqueous solution of polyvinylpyrrolidone and dried.

The non-photosensitive material was cut into small pieces as described in Example 1, but at 5 sec/2 cm. Irradiate according to the image with medium-speed electrons at a deflection speed within the range.

After irradiation, the aluminum sheet is fixed on an offset printing machine, and then printed on an offset printing machine.

Similar results can be obtained if polyvinylpyrrolidone is replaced by its copolymer or casein or 2.5% wheat starch or pentoclinic tannin dissolved in water in the coating.

Example 3 A mechanically roughened aluminum plate is dip coated in a pentahydrous aqueous solution of polyvinylphosphonic acid at 80° C., dried and imagewise irradiated with an electron beam.

Beam current strength is 200μA1 Deflection speed is Q, 5s
It has a range of ec/2.

The irradiated areas are lipophilic and absorb fatty inks during printing.

Example 4 An Al-Cr plate was coated with a 2.5% polyvinyl alcohol aqueous solution and deflected at a deflection rate of 5 sec/by 100 μA electrons.
Irradiate at 2 am.

Then print immediately as described above.

Instead of polyvinyl alcohol, dextrin 6-part solution, gum arabic 18% solution, starch 5-part solution, wheat paste 2.5% solution or hydroxyethyl cellulose o. 1
Similar results are obtained by coating with % solution.

Example 5 An anodized anoleminium plate was coated with a 5-width solution of polyethylene glycol with a medium molecular weight of 3900-4800 and heated for 5 sec/2 c with 200 μA electrons.
irradiate with a deflection speed of m.

The irradiated plate is immediately used as an offset printing plate.

Similar results are obtained by coating with a 2.5 solution of polyacrylic acid.

Example 6 In order to form a boehmite layer at least 10 times as thick as the air oxidation layer on an anodized board, it is immersed in pure water at 95°C for 60 seconds and dried.

After image-wise irradiation with 20 μA of electrons, the irradiated areas become oleophilic and absorb ink when used in an offset printing press.

Instead of anodized plates, aluminum plates roughened with nylon brushes in a pumice suspension can likewise be provided with a boehmite layer and treated as described above.

Example 7 A commercially available paper sheet suitable for use as a printing plate with a hardened coating of a hydrophilic colloidal binder containing finely divided inorganic pigments is irradiated with 25 μA of electrons and then printed as in Example 1.

Example 8 lo% trichloroacetic acid dispersed with 2% finely divided silicon dioxide and 0.0% anionic wetting agent. A polyethylene terephthalate sheet treated with a 2% aqueous solution to provide a hydrophilic adhesion layer is irradiated with 50 μA of electrons and further processed as in Example 1.

A print of similar quality to Example 1 is obtained.

Example 9 A mechanically roughened aluminum plate is coated with an aqueous crystal violet 2 solution and dried.

100 μA beam current intensity 0. ) Irradiation with electrons.

The printing plate is then fixed on the offset printing press and wiped with a damp sponge.

The highly water-soluble dye layer in the non-irradiated areas is thereby removed, while the irradiated areas are hardened and lipophilic.

Wiping with a damp sponge is not always necessary, but if you do not wipe first, the machine will become contaminated with residual dye.

Satisfactory printing of over 100,000 copies is obtained.

The same results are obtained using the same concentrations of the dyes Rhodamine B1 methylene blue and eosin instead of crystal violet.

Example 10 A mechanically roughened aluminum plate is coated with a 5-part solution of sorbitol, dried, irradiated with electrons as described in Example 1 and started printing on an offset printing press without further steps.

Instead of sorbitol solution, use the same concentration of sucrose, glucose,
The same good results are obtained using lactose and/or maltose.

Claims (1)

[Claims] 1. In the process of making a lithographic printing plate in which a metal base covered with a hydrophilic layer is image-wise irradiated, the hydrophilic layer consists of a non-photosensitive layer of a water-soluble film-forming organic compound or an organic or inorganic aluminum surface of the base. using a non-light-sensitive layer of a water-insoluble reaction product of an acid or its salt with a monomer or polymer, irradiating this layer imagewise with an electron beam and immediately printing on a lithographic press with the material obtained by irradiation A method of manufacturing a lithographic printing plate characterized by: