US 3046131 A
Description (OCR text may contain errors)
United States PatentG 3,046,131 PHDTOGRAPHIC MATEREAL CONTAINING LIGHT SENSITIVE QUENONE DIAZIDES Maximilian Paul Schmidt, Wilhelm Neugebauer, and August Rebenstock, Wieshaden-Biebrich, Germany, assignors, by mesne assignments, to Azoplate Corporation, Murray Hill, NJ. N Drawing. Filed Feb. 14, 1958, Ser. No. 715,132 Claims priority, application Germany Jan. 5, 1952 Claims. (Cl. 96-75) This invention relates to an improved light-sensitive material which is especially useful in the field of reproduction. More particularly it relates to laminated material comprising a support layer an intermediate layer containing a light-sensitive and water-insoluble substance and a coating of a water-soluble substance.
Water-insoluble diazo compounds belonging to the group of the so-called diazo anhydrides otherwise known as quinone diazides have been found to be well suited for sensitizing a base material for making images which can be used as stencils or after inking with greasy printing ink, as printing plates.
The water-insoluble diazo compounds, in solution with organic solvents are coated in a thin layer on a support layer, preferably on metal foils or plates. After the layers have been dried and exposed to light under a pattern the exopsed material can be developed with dilute kaline solutions to show a positive image from a positive master and a negative image from a negative master, or when certain of the water-insoluble diazo anhydrides are used, development may be accomplished with dilute acids. Development with acid reacting agents provides positive images from negative masters and negative images from positive masters.
In practicing the above described processes the lightsensitive layers, for example such layers as have been produced from water-insoluble quinone diazides, often show a feeble coloring in those areas of the layer that are not covered by the pattern and that contact the glass of the copying frame. This coloring may be caused by heat radiation from the glass but whatever its cause it is disadvantageous in that it is very ditficult to remove and may cause a coloring of the background of the copies drawn from the image.
It has now been found that light-sensitive material of the above mentioned kind does not show the disadvan tage described above it the light-sensitive layer is covered by a protective coating consisting of film-forming watersoluble substances.
The protective coating may be produced by applying to the surface of the light-sensitive layer by means of, for example, a brush or a plate-whirler, an aqueous solution of dextrine, gum arabic, mesquite gum, tragacanth, water-soluble salts of pectic acid and alginic acid, water-soluble cellulose others, such as methylcellulose, hydroxyethylcellulose, water-soluble salts of carboxyalkyl cellulose, water soluble salts of carboxy alkyl starch, glue, albumen, pepton, water-soluble caseinates, polyvinyl alcohol, polyvinylpyrolidone, polyacrylamides, water-soluble salts of polyacrylic acids or other water-soluble polymerization products, which are capable of forming films. After drying the solution which has been applied covers the lightsensitive layer as a protective coating. In general, aqueous solutions containing 0.2 to of the colloidal substances and showing an approximately neutral re ction are suited for producing the colloidal coating.
The presence of the protective coating prevents the direct contact between the light-sensitive layer and the glass of the copying apparatus. Another important advantage of the coating is that it protects the thin light-sensitive diazo layer from being damaged by friction, dust or direct contact with the fingers. If the light-sensitive layer is not protected and is touched by the man handling it, then fingerprints become reproduced on the copies during the printing and especially in the cases where the negative working process is followed. The coating also improves development of the image because it provides for improved wetting of the exposed layer. The addition of wetting or emulsifying agents such as alkyl substituted naphthalene sulfonic acids, saponins or sulfonates of high molecular aliphatic alcohols to the solutions of watersoluble film forming substances improves the formation of a uniform coating and the development of the images.
The following examples are included to illustrate the invention:
(1) A 1.5% solution of the a-naphthylester of naphthoquinone-( 1,2)-diazide-( 2)-5-sulfonic acid in glycol-mono methylether is coated as for example, with the use of rollers as a thin layer on an aluminum foil which has been mechanically roughened. After drying the layer, a 4 to 6% aqueous solution of gum arabic or dextrine is applied to the layered foil in the same manner and then dried.
The material thus obtained is exposed to light under a master and subsequently developed with a 3% aqueous solution of trisodium phosphate. From a positive master a positive image is obtained. A perfectly clean background is obtained in those areas which had not been protected by the master and which contacted the glass.
Instead of the above described a-naphthylester, other esters or amides of a quinone diazide sulfonic acid may be used for the formation of the light-sensitive layer underneath the water-soluble layer. The u-naphthylester of naphthoquinone-(1,2)-diazzide-(2)-5-sulfonic acid is produced in the following manner:
3 parts by weight of a-naphthol and 5.4 parts by weight of naphthoquinone-(l,2)-diazide-(2)-5 sulfonic acid chloride are dissolved in 45 parts by volume of diox-ane. 15 parts by volume of a 10% soda solution is slowly added to the solution at room temperature. After about 10 to 15 minutes a yellow compound precipitates. The reaction mixture is heated to 35 C. for a short time, is cooled down again to room temperature, then the mixture is made alkaline by addition of a small quantity of a 10% soda lye and the yellow colored a-naphth'ylester is separated at once. Recrystallized from benzene it decomposes at to 148 C.
(2) A 1% solution of the naphthoquinone-(l,2)-diazide- (2)-4-sulfonic acid ester of 7-hydroxy-2-e'thyl-N-(n-propyl)naphth'o-1,2:4,5-imidazole in glycolmonomethylether is whirl-coated onto a roughened or superficially oxidized aluminum foil. A 5% aqueous solution of dextrine or a 1% aqueous solution of polyvinyl-alcohol mixed with a small quantity of a saponin is coated onto the dried layer by means of a cotton swab and dried. The light-sensitive material thus obtained is exposed to light under a transparent negative; then the exposed layer is developed by wiping over with a 2.5% phosphoric acid with the aid of a cotton swab and the developer is removed by rinsing the layer with water. After rubbing in with greasy printing ink the thus obtained positive image may be used for printing in the usual manner.
The above mentioned diazo compound is produced in the following manner:
To a solution of 5 g. of 7-hydroxy-2-ethyl-1-(or 3)-N- n-propylnaphtho-1,2:4,5-imidazole in 50 cc. of dioxane and 30 cc. of water 26 cc. of a 10% soda solution are added and thereafter, at about 30 to 35 C., a warm solution of 6 g. of naph-thoquinone-(l,2)-diazide-(2)-4-sulfochloride in 25 cc. of dioxane is added and. the reaction mixture is heated to 50 C. for a short time. After cooling down to room temperature the reaction mixture is diluted with such a quantity of water that the condensation product is perfectly precipitated. The precipitate representing the condensation product is separated and' washed with water. The product is then recrystallized from a mixture of alcohol/dioxane (2:1) with the addition of animal charcoal and yellow crystals are obtained which decompose at about 150 C.
The 7-hydroxy-l(or 3)-N(n-propyl)-2-ethylnaphtho- 1',2':4,5-imidazole is obtained in the following manner:
1 mol of l,2-diaminonaphthalene-7-sulfonic acid and 2 moles of n-propaldehyde are heated in an aqueous solution to the boiling point for about 4 hours, then the precipitated Z-ethyl-N-(n-propyl)-naphtho-l,2:4,5-irnidazole-7- sulfonic acid is separted and dried and thereafter it is fused with a fourfold to fivefold quantity of caustic po tash at about 230 to 250 C. The reaction mixture is dissolved in water and by neutralizing the aqueous solution with the aid of hydrochloric acid the crude 7-hydroxy 2 ethyl 1(or 3) N (n propyl) naphtho 1,2:4,5-imidazole is separated out. The imidazole is purified by recrystallization from alcohol and then has a melting point of 250 to 251 C.
(3) By means of a plate-whirler a 2% solution of the condensation product obtained from 2 moles of naphthoquinone-(l,2)-diazide-(2)-5-sulfochloride with a'mole of 2,2-dihydroxy-1,ldinaphthylmethane in glycol-monomethyl ether is coated onto a mechanically roughened aluminum plate and dried in a hot-air current. On top of the dried layer, by means of a plate-whirler, an aqueous solution is poured containing 1.5% of sodium alg-inate and 0.1% of saponine and then the coating is dried. After exposing the dried layer under a positive pattern, the exposed layer is developed with a 3% aqueous solution of trisodium-phosphate and then rinsed with water. The positive image thus obtained can be used, in the usual way, for printing in a customary offset printing machine. This process guarantees prints free from tone, whereas plates not coated with alginate show some tone wherever they come into contact with the glass plate of the copying machine.
Substitution of the sodium alginate solution in Example 3 by a 5% sodium polyacrylate solution, provides equally good results.
The condensation product of 2 moles of naphthoquinone-(1,2)-diazide-(2)-5-sulfochloride and 1 mole of 2,2'-dihydroxy-l,l'-dinaphthylmethane can be prepared in a manner similar to that described in Example 1 and the product corresponds to the following structural formula:
V o ll ll may, @Nz
(4) On a plate-whirler a mechanically roughened alu- -rninum foil is coated with a solution containing 2% naphthoquinone-( 1,2 -diaZide-( 2 -5 -sulfonic acid-p-xylide and 0.2% 1phenyl-3-methylpyrazolon-5, dissolved in glycolmonornethylether. The coated foil is dried and, after a 5% aqueous solution of sodium polyacrylate, pH=7, is applied on top of the foil in the plate-whirler it is dried again. The coated side of the foil is exposed to light under a positive pattern. Thereupon the exposed oil is r t s e e t9 he i fl en a mo ia gas whereby a positive image of the pattern appears. Then the background of the image is cleared by treating the coated side of the toil with a solution of 5% aqueous disodium-phosphate. The toll is then rinsed with water. As usual in the ofiset technique, the image side of the foil is briefly treated with a solution of gum arabic in phosphoric acid (10 g. phosphoric acid and g. gum arabic to one liter of water). The foil can then be used for printing in the offset machine. Prints which are free from tone are obtained, in contrast to foils prepared without any sodium polyacrylate coating which are strongly toning wherever, during the printing process, they have come into direct contact with the glass of the copying machine.
The above mentioned p-xylidide can be produced in I the usual way by causing naphthoquinone-(1,2)diazide- (2)-5-sulfonic acid to react with xylidine in an organic solvent in the presence of acid binding substances.
This application is a continuation-impart of applications Serial Nos. 472,224 and 517,086, filed Nov. 30, 1954, and June 21, 1955, respectively, which are, in turn, continuations-in-part of application Serial No. 328,808, filed Dec. 30, 1952, and now abandoned.
What we claim is:
1. Laminated material for use in photography consisting of a support layer, an intermediate layer of light sensitive material comprising a water insoluble quinone diazide, and a top coat consisting essentially of a substance of the group consisting of dextrine, gum arabic, mesquite gum, water-soluble salt of the group consisting of pectic acid and alginic acid, water soluble cellulose ether, water soluble salt of carboxy alkyl cellulose, water soluble salt of carboxy alkyl starch, glue, albumen, pepton, water soluble, caseinate, polyvinylalcohol, polyvinylpyrolidone, polyacrylamide, and water soluble salt of poly-acrylic acid.
2. Laminated material for use in photography consisting of a support layer, an intermediate layer comprising a water insoluble quinone diazide, and a top coat consisting essentially of dextrin.
3. Laminated material for use in photography consisting of a support layer, an intermediate layer comprising a water insoluble quinone diazide, and a top coat consisting essentially of polyvinyl alcohol.
4. Laminated material for use in photography consisting of a support layer, an intermediate layer comprising a water insoluble quinone diazide, and a top coat consisting essentially of gum arabic.
5. Laminated material for use in photography consisting of a support layer, an intermediate layer comprising a water insoluble quinone diazide, and a top coat consisting essentially of alginic acid.
6. Laminated material for use in photography consisting of a support layer, an intermediate layer comprising a water insoluble quinone diazide, and a top coat consisting essentially of a water soluble salt of carboxyl alkyl cellulose.
References Cited in the file of this patent UNITED STATES PATENTS 2,667,415 Neugebauer et al Jan. 26, 1954 2,702,243 Schmidt Feb. 15, 1955 FOREIGN PATENTS 497,135 Belgium Nov. 16, 1950 51 7 6 B i No 54