Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3062644 A
Publication typeGrant
Publication dateNov 6, 1962
Filing dateSep 26, 1958
Priority dateDec 28, 1956
Also published asDE1055957B, DE1059766B, US3061429
Publication numberUS 3062644 A, US 3062644A, US-A-3062644, US3062644 A, US3062644A
InventorsNeugebauer Wilhelm, Sus Oskar, Rebenstock August
Original AssigneeAzoplate Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Diazo printing plates and method for the production thereof
US 3062644 A
Images(4)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent Ofiice 3,062,644 Patented Nov. 6, 19 62 This invention relates to a novel presensitized printing plate containing a diazo compound, and to a method for the production thereof and, more particularly, to a novel presensitized printing plate which can be developed merely by washing with water, thereby eliminating the alkali or acid treatment required with printing plates known to the prior art.

It is known that the solubility of water soluble colloids changes when the colloids are exposed to light in the presence of diazo compounds. However, the results of this hardening or tanning action are generally unsatisfactory insofar as the practical use of such hardened colloids in the reproduction art is concerned. It has, therefore, been proposed to subject the colloid layers containing diazo compounds to an after-treatment with a chromate solution after exposure to light under a transparent original or master. Diazo compounds of higher molecular weight, such as condensation products of aldehydes with diazo compounds, for example the diazo compound of p-amino-diphenylamine, have been proposed for the tanning of colloid layers, and best results are obtained when these diazo compounds constitute about 10 percent by weight of the dry colloid applied.

However, the foregoing plates consisting of base materials coated with layers consisting of water soluble colloids sensitized by means of diazo compounds, have not found practical application in the printing trade. The light-hardened colloid particles of these layers are not capable of holding the greasy ink in flat and offset printing, and the mechanical strength of the hardened colloids is insufficient to permit long runs.

In accordance with the present invention, it has been found that excellent fiat and offset printing plates can be produced from light sensitive material consisting of a support having a colloid layer thereon, the colloid layer comprising a polyacrylic acid and containing as light sensitive substances the diazonium chlorides or diazonium bromides of 3-amino-carbazoles, i.e. 3-amino-carbazole and the substitution products thereof containing alkyl groups or alkoxy groups. Instead of polyacrylic acid,

there may be used polymethacrylic acid or copolymers of acrylic-methacrylic acid.

Some of the diazonium salts to be used according to the present invention have been described in the literature. Insofar as they constitute new products, they can be prepared by the known methods of diazotization from the respective amino-carbazoles.

In practicing the present invention, sheet metal in the form of a plate or a foil, preferably sheet aluminum, or a paper sheet, preferably the specific papers commercially available for the manufacture of paper printing plates are used as base supports. For the purpose of providing the base with the light sensitive layer, the respective carbazole-3-diazonium chloride or carbazole- 3-diazonium bromide, or mixtures of such diazoniurn salts, is dissolved in an organic solvent and the solution is applied to the base by a whirling, spraying or brushing operation. The coated layer supports are then dried, in

general at elevated temperatures, e.g. at about 90 C. 7

Suitable organic solvents are primarily solvents having a boiling point between 80 and 150 C. Preferredare the ethylene glycol monoalkyl ethers, dioxane, and diacetone alcohol; the organic solvents may be mixed with water and the mixture used for dissolving the 3-diazoniumcarbazole salt. The diazonium chlorides and the diazonium bromides obtained from the 3-amino-carbazoles employed form, with polyacrylic acid and polymethacrylic acid respectively, addition products which are difficultly soluble in water. For this reason it is essential that the quantity of water added to the organic solvent be insufficient to cause separation of the addition products. Advantageously, solutions of the diazonium salts are used which contain about 0.5 to 2 percent, by weight, of the respective diazonium chloride or bromide, or mixtures thereof. Although the weight ratio between the quantity of the colloid and the diazonium salt present in the solution may be varied within wide limits, it is preferred to use both components in approximately equal quantities, -i.e. 1:1.

The light sensitive colloidal layers produced according to this invention are of excellent stability and storageability. For making printing plates from the reproduction material, the colloidal layers are exposed to light under a light-image and after exposure an image is produced on the support by merely developing it with water, e.g. by showering or wiping the plate over with water or by immersing it in a water bath. Alternatively, the exposed plate may be developed by clamping it into the printing apparatus and wiping it over With a sponge soaked in Water. It is superfluous to subject the base after development to an after-treatment with dilute acid for the purpose of improving the water conductivity of the surface of the base Where the colloidal layer has been removed. Thus, a substantial simplification of the developing operation is achieved. After the treatment with water (development), the coated surface of the base is inked with greasy ink and the printing plates are ready for printing long runs of copies; faultless prints are obtained.

The following light sensitive compounds are exemplary of those which'may be employed in the present invention:

Formula 1 OT O-m 01 N/ it Formula 2 NiBr Q CH3 Example I 0.6 part by weight of the compound corresponding to Formula 1 above and 0.6 part by weight of a watersoluble polymethacrylic acid (intrinsic viscosity==0.7) were dissolved in parts by volume of ethylene glycol monomethyl'ether.- This solution was coated on an alu- 100 C. for about two minutes. exposed to a negative light-image using an arc lamp of adding a saturated sodium chloride solution.

minum foil, the surface of which had been mechanically roughened. The coated foil was then dried and the drying operation was finished by exposing the coated surface of the foil to a current of hot air at a temperature of The sensitized foil was 18 amperes for two minutes, for example, at a distance of 70 cm. The exposed surface of the foil was then rinsed with water and rinsing was continued until the yellowcolored areas of the exposed coating, i.e. the areas unattected by light during the exposure, were removed completely, by the water; a positive image of the negative pattern remained on the foil and was clearly visible on the ical Societ London, volume 121, page 2712. The diazonium chloride is purified by dissolving it in water and The carbazole-3-diazonium chloride is an orange-yellow powder, melting at 102-104 C. with decomposition.

An equally good printing plate, giving runs of the same order, was obtained by coating the aluminum foil with a solution containing, per 100 cc. of ethylene glycol .monomethyl ether, 1.2 parts by weight of carbazole-3- diazonium chloride and 0.6 part by weight of polymethacrylic acid (intrinsic viscosity=0.7).

Example II An aluminum foil, the surface of which had been tmechanically roughened, was coated with a solution, conposed foil was eifected by means of tap water, see also Example I. From a negative pattern a positive printing plate was obtained.

The compound corresponding with Formula 3 may be substituted for the compound of Formula 2 in the coating solution stated above. The sensitized foil thus obtained is very stable and storageable over a long period of time.

The compound corresponding with Formula 2 above is made by diazotizing 3-amino-6-methyl-carbazole in an aqueous hydrobromic acid solution; 3-amino-6-methylcarbazole has been described by Bremer in Justice Liebigs Annalen der Chemie, volume 514 (1934), page 279. The diazonium bromide obtained is purified by dissolving it in water and by adding a saturated potassium bromide solution. The compound is an orange-yellow powder which upon heating in a melting point tube, starts darkening at 115 C. and decomposes at 170 C.

The compound corresponding with Formula 3 above is manufactured from 3-amino-2-methoxy-carbazole. Because the statements relating to the preparation of the starting material, contained in German Patent No. 553,628, and also in Chemisches Zentralblatt, volume 32, II, page 1516, are somewhat ambiguous, 3-amino-2- methoxy-carbazole is prepared as follows:

Z-methoxy-N-acetyl-carbazole (melting point 8184 C.) is obtained by heating a mixture of Z-methoxy-carbazole (melting point 233234 C.) and acetic acid anhydride at about 200 C. The acetylated product is treated with nitric acid at room temperature for several hours which treatment results in the formation of 2-mcthoxy-3nitro-N-acetyl-carbazole (melting point 154-155 C.). This nitro compound is catalytically reduced with hydrogen and Raney nickel catalyst to 2-methoxy-3- amino-N-acetyl-carbazole (melting point ISO-181 C.). The amino-carbazole obtained is heated with a 10 percent methanolic potassium hydroxide solution for several hours, thereby splitting off the acetyl group. The resulting 2-methoxy-3-amino-carbazole is separated in the form of its hydrochloride, which decomposes above 225 C. By diazotization of the 2-methoxy-3-amino-carbazole hydrochloride in hydrobromic acid solution, Z-methoxycarbazole-3-diazonium bromide is obtained which is purified by dissolving it in water and by adding a saturated potassium bromide solution. The diazonium bromide is a greenish-yellow powder which begins darkening and decomposing upon heating to about C.

Example III An anodically oxidized aluminum foil was coated with a solution containing, per 100 parts by volume of ethylene glycol monomethyl ether, 0.6 part by weight of the compound corresponding to Formula 1 above and 0.8 part by weight of a water soluble polyacrylic acid of medium viscosity (intrinsic viscosity=0.5). Coating of the aluminum foil was effected by means of a conventional plate Whirler. The foil after being coated with the solution was dried, exposed to a negative light-image and, after exposure, rinsed with water for about one minute. A positive image was obtained which was inked up with greasy ink. The foil could then be used as a printing plate.

Example IV The processed surface of a commercial paper printing foil was coated With a solution containing, per 100 parts by volume of diacetone alcohol, 0.5 part by weight of the compound corresponding to Formula 2 above and 0.7 part by weight of a water soluble polyacrylic acid of medium viscosity (intrinsic viscosity=0.5). The coated foil was dried and subsequently exposed to a light-image; after exposure, the exposed surface of the foil was inked up with greasy ink and subsequently rinsed with water. By this treatment with water, those areas of the acrylic acid layer which were not struck by light in the course of the exposure, were dissolved and the greasy ink sticking to the areas unaffected by light was also removed. A positive printing plate is obtained if the light-image used as a pattern is a negative.

Example V A zinc plate was treated with a 4 percent acetic acid solution containing 4 percent by weight of potassium aluminum sulfate, then brushed for about 3 to 5 minutes, rinsed with water and dried. Then the plate was coated with a solution containing, per 100 parts by volume of diacetone alcohol, 2 parts by weight of the compound corresponding to Formula 2 above and 0.5 part by weight of a water soluble polyacrylic acid of medium viscosity (intrinsic viscosity=0.5). After coating, the sensitized plate was dried and exposed to a negative light-image. The exposed plate was rinsed with Water and afterwards inked up with greasy ink. Long runs of copies can be made from the positive printing plate thus obtained.

Example V1 0.5 part by weight of the compound corresponding to Formula 1 above and 0.5 part by weight of a water soluble copolymer of acrylic acid and methacrylic acid (molar ratio 1:1) were dissolved in 100 parts by volume of ethylene glycol monomethyl ether. An aluminum foil, both sides of which had been mechanically roughened, was coated with this solution. After the solution had dried, the coated side of the aluminum foil was exposed under a negative transparent original and subsequently rinsed with tap water for about 30-60 seconds. Without further treatment, the imaged side of the foil was inked with greasy ink and used as a printing plate. A positive printing plate was obtained from a negative original.

The expression a polyacrylic acid as used in the following claims is intended to include a polymethacrylic acid as well as copolymerizates of acrylic and methacrylic acid.

It will be obvious to those skilled in the art that many modifications can be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound selected from the group consisting of the diazonium chloride and bromide of a 3-amino-carbazole.

2. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula in which X is selected from the group consisting of chloro and bromo ions and R is an alkoxy radical.

3. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula N .aX

in which X is selected from the group consisting of chloro and bromo ions and R is an alkyl radical.

4. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula 5. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula 6. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula 7. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound selected from the group consisting of the diazonium chloride and bromide of a 3-amino-carbazole, and washing the exposed plate with water.

8. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly 6 coated thereon a layer comprising a polyacrylic acid and a compound having the formula NLX in which X is selected from the group consisting of chloro and bromo ions and R is an alkoxy radical, and washing the exposed plate with water.

9. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula in which X is selected from the group consisting of chloro and bromo ions and R is an alkyl radical, and washing the exposed plate with water.

10. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula @gUNzCI and washing the exposed plate with water.

11. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula HaC N Br and washing the exposed plate with water.

12. A process for developing a printing plate which comprises exposing to light under a master a presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula NaBr N OCH: H

and washing the exposed plate with water.

13. A presensitized printing plate comprising a base material having directly coated thereon a layer comprising a polyacrylic acid and a compound having the formula 3,062,844 7 coated thereon a layer comprising a polyacrylic acid and a compound having the formula R Y R1 5 2,593,928 N 2,772,974

References Qited in the file of this patent UNITED STATES PATENTS Von Glahn et a1 Nov. 28, 1950 Slifkin Apr. 22, 1952 Kosaiek et a1 Dec. 4, 1956 Kosalek et a1 Feb. 4, 1958 Seven et a1 May 17, 1960 OTHER REFERENCES Saunders: The Aromatic Diazo Compounds, Edward Arnold & Co., London, 1949, pages 7879.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2531485 *Apr 2, 1947Nov 28, 1950Gen Aniline & Film CorpDiazotypes comprising amine salts of sulfonic acid containing azo components
US2593928 *Oct 9, 1947Apr 22, 1952Gen Aniline & Film CorpDimensionally stable diazotype photographic film and process for making it
US2772974 *Feb 10, 1954Dec 4, 1956Gen Aniline & Film CorpLight sensitive diazotype materials
US2822272 *Feb 10, 1954Feb 4, 1958Gen Aniline & Film CorpLight sensitive diazotype material
US2937085 *Jan 11, 1954May 17, 1960Ditto IncComposite photosensitive plate, and method of making printing plate therefrom
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3179518 *Mar 1, 1963Apr 20, 1965Azoplate CorpPresensitized printing foil having as a coating thereon a light-sensitive diazo compound with polyvinyl phosphonic acid
US3284198 *Sep 11, 1963Nov 8, 1966Martin Marietta CorpMethod for making photolithographic plate
US3493371 *Jan 24, 1968Feb 3, 1970Agfa Gevaert NvRadiation-sensitive recording material
US4387469 *May 28, 1981Jun 7, 1983Clarion Co., Ltd.Tuner control system
US4985332 *Apr 10, 1990Jan 15, 1991E. I. Du Pont De Nemours And CompanyResist material with carbazole diazonium salt acid generator and process for use
US5002856 *Aug 2, 1989Mar 26, 1991E. I. Du Pont De Nemours And CompanyDiazonium salts as photoinitiators, glycidyl polymers for development
US5219711 *May 18, 1992Jun 15, 1993E. I. Du Pont De Nemours And CompanyAlpha alkoxyalkyl carboxylic acid ester polymer, resolution, sensitivity
Classifications
U.S. Classification430/176, 430/309, 430/302, 430/171
International ClassificationA61F13/00, G03F7/021, A61F13/15
Cooperative ClassificationG03F7/0212
European ClassificationG03F7/021P, A61F13/00