US3406066A - Vitrifiable photosensitive emulsion - Google Patents

Description

United States Patent O 3,406,066 VITRIFIABLE PHOTQSENSITIVE EMULSION Francis J. Avery, Vestal, N.Y., assignor to GAF Corporation, a corporation of Delaware No Drawing. Filed Apr. 30, 1964, Ser. No. 363,982 13 Claims. (Cl. 9634) ABSTRACT OF THE DISCLOSURE Photosensitive emulsion layers on a refractory surface, adapted for vitrification while resisting contraction, stretching, blistering, tearing and frilling, containing to 50% of polyacrylamide or acrylamide-acrylic acid copolymer, or in the case of silver halide gelatin emulsions, containing 1.25 to 3.75 parts of silver per part of gelatin; and a method of producing vitreous colored images therewith involving imagewise exposure of such silver halide emulsions, developing, converting the image to metal ferrocyanide(s) which yield a colored oxide on firing, and firing the image.

The present invention relates to photosensitive hydrophilic emulsion layers capable of being subjected to a vitrification process without causing the emulsion layer to exhibit such defects as contraction, stretching, blistering, tearing or frilling during a firing process in which all of the organic matter is consumed. More particularly, the invention pertains to gelatino-silver halide emulsions containing less gelatin than is normally present in such silver halide emulsions and which are especially applicable to the formation of permanent vitrified images on refractory surfaces and to a method of using the silver image produced from such emulsions to supply the ceramic pigment and flux needed for formation of said vitrified image.

The prior art has indicated that it is necessary to use collodion emulsions for producing vitrified photographic images since the carbonaceous ash residue formed while firing a normal gelatino-silver halide emulsion causes contraction, streaching, blistering, tearing or frilling of the emulsion layer.

I have discovered, contrary to the fixed notion of the prior art, that gelatino-silver halide emulsions may be used to form excellent permanent vitrified photographic images on refractory surfaces providing that the quantity of gelatin in such gelatino-silver halide emulsion is reduced below that usually present in silver halide emulsions and bears a ratio to the weight of silver in such emulsion of silver/ gelatin by weight ranges from 3.75/1 to 1.25/1.

I have also discovered that the silver image formed by the usual photographic process from such silver halide emulsions is uniquely adapted to a conversion method leading to the imagewise formation of a lead sulfate flux and a ferrocyanide of a base metal yielding the ceramic pigment on firing.

The employment of such emulsions for such purpose and their processing to produce such ceramic pigment and flux constitute, in part, the objects of my invention.

The radiation-sensitive halide employed in the emulsions may be any silver halide generally used in forming photographic emulsions, such as silver bromide, silver chloride, silver chlorobromide, silver bromoiodide, silver chlorobromide iodide, or the like. The silver halide se lected while observing the noted ratio of silver to gelatin, however, must be such that the resulting emulsion has satisfactory speed, preferably that of enlarging paper. Such emulsion, when coated on a refractory surface, may be used with any photoenlarger to produce enlarged pictures directly on such surface. Exposures for a normal negative at three times enlargement may be at 116 for 10 to 40 seconds. This is in sharp contrast to colloidion F ice emulsions which are of a very low photographic sensitivity and require are light exposures.

While, for best results, I prefer to use the aforesaid silver halide emulsions, I find that damage to the photo sensitive emulsions may be avoided by employing. a photosensitive hydrophilic emulsion, the colloidal carrier of which is combined with a polyacrylamide, such as the homopolymer; a copolymer of acrylamide and acrylic acid, or a mixture of the homopolymer and copolymer. The colloidal carrier or binding agent for these photosensitive emulsions may be gelatin, gum arabic, or egg albumen, and the carrier may be sensitized with a substance which hardens the colloid upon exposure to light or may be a silver halide. Suitable sensitizers which harden colloids, such as gelatin, on exposure to light are the bichromates and certain diazo compounds as described in Charlton, US. Patent 2,900,255.

If the photosensitive emulsion be a silver halide, it may be processed by conventional procedure, by tanning development as in Yackel, U.S. Patent 2,607,683, or by a tanning bleach as in the carbro process. Despite the sensitizer or the mode of processing, however, the photosensitive hydrophilic emulsion must contain the polyacrylamide to be resistant to damage on firing.

The polyacrylamide is generally present in an amount of from 10 to 50 percent by weight of the colloidal carrier. The preferred polymers are the anionic copolymer of acrylamide and acrylic acid sold by American Cyanamid Company under the name of Cyanamer P-26, or the polyacrylamide homopolymer sold under the name of Cyanamer P-ZSO. Such polymers are compatible with the colloidal carriers and mixtures thereof dry to films of good clarity.

The emulsions contemplated for use herein may be applied directly to a refractory permanent base by whirling, brushing, spraying, dipping, or the like. Although the direct application is preferred, it is also possible to use the photosensitive emulsion in the form of a so-called stripping film, pigment papers or transfer papers from which the image formed thereon is subsequently transferred to the permanent base for firing or vitrification.

The emulsions may be used for permanentizing photographic images on any refractory surface, such as ceramic articles, glass plates, metal plates, and enameled metal plates. These permanent images may be used to produce reticles, record data, printed circuits, photographic pictures or designs of a decorative nature.

In addition to the photosensitive emulsion, there must also be present a vitrifiable ceramic pigment and a flux. The vitrifiable pigment may be underglaze COlOrs and stains, color glazes, overglaze colors, enamel colors and glass colors, or even simple metal compounds, such as the carbonates of cobalt, manganese and iron. The flux may comprise a low melting glass composed of lead silicates or lead borosilicates, or the like. The flux should be compatible with the permanent base as to coefiicient expansion and vitrification temperatures.

Underglaze colors, applied to unglazed ceramic ware, which are suitable for use are:

Color glazes of the fritted variety which I may employ are represented by:

Glossy Black Glaze #600 Red Brown Glossy Glaze #-l0-G-179A (Both Cone 06 by the above manufacturer) Overglaze colors, low melting color glasses maturing at cone 017, which are usually applied to glazed and fired ceramic ware are exemplified by:

Overglaze Brown #2210-U (Cone 017 by the above manufacturer) The ceramic pigment and flux may be added to the photosensitive emulsion, particularly when the sensitizer causes hardening on exposure to light. However, when the emulsion is a silver halide to be processed to a silver image, best results ensue when the ceramic pigment or the flux, or both, are formed imagewise through use of the silver image.

To this end, a base coated with a silver halide emulsion of the type herein described is exposed to light underneath a pattern, developed and fixed to yield a silver image.

The silver image may then be bleached with a watersoluble ferricyanide in the presence of a salt of a heavy base metal, the oxide of which is a ceramic pigment. The ferrocyanide of the heavy base metal is then converted to the oxide by treatment with an alkali metal hydroxide. For example, a silver image formed as above may be treated wtih an aqueous solution of potassium ferricyanide and then with an aqueous solution of manganous sulfate. The resulting manganese ferrocyanide is converted by means of sodium hydroxide into manganese dioxide. The manganese dioxide image is fired at cone 09 similar to an underglaze ceramic pigment. The ceramic base is then glazed and refired at cone O6 to yield a brownish-black image under the glaze.

Similar results are obtainable by replacing the man ganous sulfate by ferric sulfate, copper sulfate, cobalt sulfate, nickel sulfate, uranium sulfate, vanadyl sulfate, and stannous sulfate.

It is possible, however, by proper selection of the conversion conditions, to utilize the silver image to produce both the ceramic pigment and the flux. Thus a silver image formed as noted is bleached with a ferricyanide solution containing a salt of lead to a yellow-white lead ferrocyanide image. The image is then treated with an acid solution of a sulfate of a heavy base metal to form the ferrocyanide of the heavy base metal and lead sulfate.

The image is then fired and, after cooling, the plate contains a vitrified positive image completely within the glaze. The decomposition of the ferrocyanide has resulted in a colored image and the decomposition of the lead sulfate caused the image to be fluxed to a glossy vitrified surface.

By using in this procedure, for example, an acid solution of ferrous sulfate for reaction with the lead ferrocyanide, there is formed imagewise a mixture of ferrous ferrocyanide and lead sulfate. Firing produces a reddishbrown image fluxed by the lead sulfate. The ferrous sulfate in this procedure may be replaced by ferric sulfate to give a blue-white image; copper sulfate, a redbrown image; manganous sulfate, a blue-white image; cobaltous sulfate, a grey-green image; nickel sulfate, a yellow-green image; uranium sulfate, a reddish image; vanadyl sulfate, a yellow image; and stannous sulfate, a white image.

The invention is further illustrated by the following examples but it is to be understood that the invention is not restricted thereto.

Example I The following solutions are made up separately:

Distilled water cc 1500 Potassium bromide gm' 80 Potassium iodide gm 1 Gelatin gm 10 Distilled water cc 300 Silver nitrate gm Ammonia (28%) cc 100 Dissolve each solution separately and make the emulsion under red light illumination. At a temperature of 42 C. with rapid stirring, dump solution II into solution I. Digest at 42 C. for 10 minutes. Add 400 gm. of dry powdered ammonium sulfate and, with stirring, cool to 25 C. Wash the resulting precipitate three times by the process of decantation. (1000 cc. of water per wash). After the last decantation, add to the resulting sludge:

Gelatin gm 15 Potassium bromide (10%) cc 10 Allow the sludge and gelatin to soak 1 hour, then melt up with rapid stirring to a temperature of 55 C. Digest for 1 hour at 55 C., then chill the resulting emulsion. Upon remelting the emulsion, it can be coated directly upon ceramic ware, glass plates, enameled metal plates, paper base or stripping film base.

At a temperature of 40 C., and with rapid stirring, add solution 11 to solution I. Stir three minutes, then add solution III, stir three minutes. This photosensitive material is now coated directly on a ceramic base.

Example 111 The following solutions are made separately:

Gelatin gm 20 Sugar gm 5 Ceramic color glaze (Glossy Black #600) gm 10 Distilled water cc Dist1lled water cc 50 Cyanamer P-26 gm 5 Distilled water cc 50 Potassium dichromate gm 2 At a temperature of 45 C., and with rapid stirring, add solution II to solution I. Stir for three minutes and then add solution III, stir three minutes. This photosensitive material can now be coated directly on a ceramic base.

Example IV The following solutions are made up separately:

Distilled water cc 500 Potassium bromide gm 80 Potassium iodide gm 1 Gelatin gm 70 Distilled water cc 100 Silver nitrate gm 100 Ammonia (28%) cc 100 Distilled water cc 100 Cyanamer P-26 gm Cyanamer P-250 gm 1 This emulsion, with such normal additions as sensitizing dyes, stabilizers, wetting agents, etc., is coated directly on a ceramic base.

Example V The following solutions are made up separately:

Gum arabic gm Gelatin gm 10 Sugar gm 5 Distilled water cc 200 Distilled water cc 200 Cyanamer P-26 gm 20 Cyanamer P-250 gm 3 (III) Distilled Water cc 50 Potassium dichromate gm 3 At a temperature of 45 C., and with rapid stirring, add solution II to solution I. Stir for three minutes and add solution III, stir three minutes. This photosensitive material can now be sprayed directly on a ceramic base.

Example VI Water cc 300 Potassium ferricyanide gm 7 Ammonia (28%) cc 7 The image is washed for 5 minutes and then toned for 15 to minutes in Water cc 300 Manganous sulfate gm 7 HCl (conc.) cc 4 The image is washed for 5 minutes and converted to manganese dioxide by bathing for 10 minutes in Water cc-.. 200 Sodium hydroxide gm 1 After washing for 5 minutes, the image is fired at cone 09 similar to an underglaze ceramic pigment. The base is then glazed and refired at cone 06 to a brown-black colored image under the glaze.

Example VII The emulsion of Example I is coated on a porcelain plate and dried. By means of a photo-enlarger, a negative image is projected onto this light-sensitive surface for an exposure time of fl6 for 10' to 30 seconds. The resulting latent image is then developed for 1 minute at 18 C. in

Distilled water cc 1000 Metol (p-methylaminophenol sulfate) gm 1 Sodium sulfite gm 28 Hydroquinone gm 4 Sodium carbonate gm 21 Potassium bromide gm 1 After development, the plate is rinsed in Water for 30 seconds and then fixed for 5 minutes in a 25 solution of sodium thiosulfate. After the fixer has removed all undeveloped silver halide, the plate is washed in water for 5 minutes and then dried. The resulting silver positive image is then bleached for 15 minutes at 18 C. in

Distilled Water cc 1000 Glacial acetic acid cc 30 Lead nitrate gm 10 Potassium ferricyanide gm 10 While in this solution, all of the silver image bleaches out to form a yellow-white image of lead ferrocyanide. The yellowish image is then washed for 15 minutes during which time it becomes colorless. The plate is then treated for 10 minutes at 18 C. in

Distilled Water cc 1000 Hydrochloric acid (98%) cc 10 Ferrous sulfate gm 10 This solution causes the rapid formation of a deep purplish-blue positive image consisting of ferrous ferrocyanide and the decomposed lead ferrocyanide yields a flux image of lead sulfate. After washing for 5 minutes, the plate is dried and finally fired in a ceramic kiln to cone 014 to 013. This will normally require 1 to 3 hours, depending on the particular kiln.

After cooling, the plate will contain a vitrified positive image that is contained completely within the glaze. The decomposition of ferrous ferrocyanide has resulted in a red-brown image and the decomposition of the lead sulfate has caused it to be fluxed to a glossy vitrified surface.

Example VIII The procedure as given in Example VII may be followed exactly, but, in place of ferrous sulfate, the following metal salts may be used either individually or in combinations.

Ferric sulfate Blue-white image. Copper sulfate Red-brown image. Manganous sulfate Blue-white image. Cobaltous sulfate Grey-green image. Nickel sulfate Yellow-green image. Uranium sulfate Reddish image. Van-adyl sulfate Yellow image. Stannous sulfate White image.

The use of these salts will result in the formation of metal ferrocyanides as Well as :a lead sulfate flux.

Example IX The ceramic ware coated as in Example II is exposed to a negative by use of an are light for 3 minutes. This exposure causes hardening of the emulsion in the lightstruck areas. The non-light struck areas are swabbed with water or dilute acid to effect removal of the emulsion in the image areas. This produces a relief which may be fired at cone ()6 to produce a permanent positive colored i-ma-ge.

Modifications of the invention will occur to persons skilled in the art and I, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

I claim:

1. A refractory surface coated with a gelatino-silver halide emulsion capable of producing vitrified colored photographic images by subjection to a vitrification process without causing the emulsion to contract, stretch, blister, tear, or frill, said emulsion containing a ratio of silver to gelatin ranging by weight from 3.75/1 to 1.25/1.

2. An article as defined in claim 1 in which the emulsion contains a ceramic pigment.

3. An article as defined in claim 1 wherein the emulsion contains a ceramic pigment and a flux.

4. An article as defined in claim 1 wherein the silver halide emulsion is a silver bromoiodide of the ammonia type.

5. A refractory surface coated with a photosensitive hydrophilic emulsion layer capable of being subjected to a vitrification process without causing the emulsion layer to contract, stretch, blister, tear, or frill, said emulsion layer comprising a colloidal carrier containing a radiation-sensitive compound, said colloidal carrier containing from about 10 to 50% of its 'weight of a polymer selected from the class consisting of polyacrylamide, a copolymer of acrylamide with acrylic acid and mixtures of said polymer.

6. An article as defined in claim 5 wherein the radiationsensitive compound is a silver halide.

7. An article as defined in claim 5 wherein the radiationsensitive compound is a bichromate.

8. An article as defined in claim 5 wherein the emulsion contains a ceramic pigment.

9. An article as defined in claim 5 wherein the emulsion contains a ceramic pigment and a flux.

10. A method of producing permanent vitrified color images on a refractory surface which comprises exposing the article of claim 1 to light underneath a pattern to form a latent image, developing and fixing said image to produce a silver image, bleaching the silver image with a water-soluble ferricyanide in the presence of a salt of a heavy base metal, the oxide of which is a ceramic pigment, converting the resulting ferrocyanide to the oxide and firing the oxide.

11. A method of producing permanent vitrified color images on a refractory surface which comprises exposing the article of claim 1 to light underneath :a pattern to form a latent image, developing and fixing said image to produce a silver image, bleaching said silver image with a ferricyanide solution containing a salt of lead to produce a lead ferrocyanide image, treating the image with an acid solution of a sulfate of a heavy base metal to form .an image of the ferrocyanide of the heavy base metal and lead sulfate and firing the image.

12. A method of producing permanent vitrified color images on a refractory surface which comprises exposing the article of claim 6 to light underneath a pattern to form a latent image, developing and fixing said image to produce a silver image, bleaching the silver image with a water-soluble ferricyanide in the presence of a salt of a heavy base metal, the oxide of which is a ceramic pigment, converting the resulting ferrocyanide to the oxide and firing the oxide.

13. A method of producing permanent vitrified images or a refractory surface which comprises exposing the article of claim 6 to light underneath a pattern to form a latent image, developing and fixing said image to produce a silver image, bleaching said silver image with a ferricyanide solution containing a salt of lead to produce a lead ferrocyanide image, treating the image with an acid solution of a sulfate of a heavy base metal to form an image of the ferrocyanide of the heavy base metal and lead sulfate and firing the image.

References Cited UNITED STATES PATENTS 2,607,683 8/1952- Yackel et a1. 96-1l4 X 3,341,327 9/1967 Avery 96-34 2,900,255 8/ 1959 Charlton 96-34 3,171,742 3/1965 Yu 96-34 3,271,158 8/1966 Allentof et a1. 96-114 NORMAN G. TORCHIN, Primary Examiner.

R. E. MARTIN, Assistant Examiner.