FI62425B - PHOTOGRAPHIC PHOTOGRAPHIC EQUIPMENT FOR FOUNDATION - Google Patents

Description

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Pmtent- och registerstyrelsen v An »ek» n utiifd och uti. «Krtft * n public · ™ * 31.08.82 (32) (33) (31) Pyrlatty ttuetkau * —S * i * rd prtorttM Qy Q1 y ^ 11.12. TU USA (US) U3136U, 531712 (71) Minnesota Mining and Manufacturing Company, 3M Center, Saint Paul,

Minnesota 55101 »USA (US) (72) David Robert Boston, St. Paul, Minnesota, USA (US) (7 ^) 0y Kolster Ab (5I +) Photolithographic plate and method for its production This invention relates to flat printing, and in particular to a photolithographic, image receiving plate and to a method for making a metallic silver image naturally olefinic.

U.S. Patent No. 3,914,123 discloses a plate structure suitable for photolithographic printing. The plate structure comprises a base plate having an organophilic surface coated with a tough hydrophilic layer (e.g. silica). The hydrophilic layer is liquid permeable and contains a metal ion reduction promoter. In preferred structures, a photoemulsion is applied over the hydrophilic layer.

After exposure of the photographic emulsion, the emulsion is contacted with a liquid developer which, by diffusion transfer processes, causes non-reduced metal ions to migrate from the non-photographic region of the photographic emulsion) to a hydrophilic layer where these ions are reduced to the metallic state. The photographic emulsion is then removed, after which the hydrophilic layer is contacted with a bleaching solution which extracts silver from this layer. The disc is then wiped with a damp cloth while rinsing 2 6 0 · 4? 5 to completely remove portions of the hydrophilic layer to expose the underlying organophilic surface in the desired image area. The resulting plate can then be placed in a press, dyed and used for printing.

Although the above-mentioned plate structure has numerous advantages over previously used structures, the image quality and the print resistance of the obtained printing plate depend on the opposing properties of the hydrophilic layer. Thus, for optimal ease of development and image quality, the hydrophilic layer should be relatively brittle and easily removable from the image areas to expose the organophilic surface below. On the other hand, the long service life depends on the hydrophilic layer being hard and durable. Because of these opposing properties, the hardness or toughness of the hydrophilic layer must be adjusted to achieve the desired balance between image quality and plate weight life. There is also usually no visible image in the plate structure after development, which prevents the plate from being assembled before staining.

In one aspect, the present invention relates to a method of treating a plate structure as described above to provide a highly durable printing plate having visible image areas and obtaining a good quality image. When using the method of the present invention, the image quality of the obtained sheet does not depend on the hardness of the hydrophilic layer.

The activators used to process silver metal image plates are known in the art. For example, U.S. Patent No. 3,721,559 discloses an activator solution containing an oxidizing agent and organic thiones or mercapto tautomers of the rings. Similarly, British Patent No. 1,292,029 discloses an activator solution containing a Cr 2+ oxidizing compound with an organic complexing agent. It is known that nowhere is an activator solution of the composition presented here capable of providing inherently oleophilic silver image areas without having to pre-treat the image with excipient or lacquer solutions.

According to the present invention, there is provided a method of inherently oleophilic a surface having metallic silver, and the method comprises contacting the metallic silver with a homogeneously stable aqueous salt acid solution containing ferricyanide anion capable of oxidizing metallic silver and an organic cation capable of forming oxidized silver. with a water-insoluble, inherently oleophilic complex, wherein the organic cation is derived from a protonatable nitrogen-substituted hydrocarbon compound containing an imine group in resonant association with adjacent groups in the hydrocarbon compound.

According to another aspect of the invention there is provided a sucral compound comprising a ferricyanide anion and at least one protonated organic molecule as defined above, which salt compound, when dissolved in water, forms an activator solution useful in the above process.

The invention thus makes it possible to produce flat printing plates with inherently oleophilic image areas by merely chemically (as opposed to a method involving mechanical treatment) a surface bearing a silver metal image, whereby the formed oleophilic image areas are clearly visible without dyeing or other further treatment.

Figure 1 shows the manufacture and handling of one type of flat plate; step A shows a substrate adhered to a hydrophilic coating by means of an adhesive coating; step B is the structure of step A over which a photoresist pulse is applied, and step C shows the structure after exposure; step D shows the exposed structure after contacting with a suitable developer; and step E is a finished flatbed plate. And Fig. 2 shows various steps in another method of manufacturing and processing the flatbed plate, wherein step A shows a carrier to which a photographic emulsion has been applied; step B is the structure of step A after exposure; step C is the structure of step B after being contacted with the developer and then placed against the hydrophilic layer supported by the substrate; step D shows the structure of step C after the developer has diffused into the hydrophilic layer; and step E is the complete Flat Weight plate.

Step A of Figure 1 shows a washer 10 coated with a layer 12 which acts as an adhesive coating between the hydrophilic layer 14 and the washer 10. The hydrophilic layer 14 is preferably tough and durable and need not be liquid permeable. It preferably comprises colloidal silica. Layer 14 also contains a metal ion reduction promoter.

Step B shows the structure of Step A with the addition of a layer 16 of high contrast photographic emulsion. The structure shown in step C is the structure of step B after being exposed to the image. In the exposed areas, the silver compound in the emulsion layer 16 changes to a latent reduced state, in areas 16a, while in areas 16b it remains unexposed and still photosensitive.

In step D, the structure of the lie C is shown after it has been contacted with the developing solution. In the light regions 16a, the silver compound is then reduced to a metallic space of visible black color. The soluble silver halide previously present in the regions 16b has migrated, i.e. diffused together with the developing solution into the layer 14 and into contact with the metal ion reduction promoting agent therein, in which layer the silver is reduced to the metallic state. In fact, the reduction of silver in layer 14 usually occurs a few seconds later than in the exposed areas 62625 of emulsion layer 16a, so when the plate is developed, the image (negative for the original image) first appears black in areas 16a, after which the entire visible surface of the plate turns black. when silver is reduced to a metallic space in layer 14 ·

In step E, the plate is shown after the emulsion layer has been removed. The surfaces 15 of the plate comprise metallic silver, which must be treated in accordance with the present invention to make the surfaces oleophilic (i.e., color-receptive). This result is achieved by contacting the surfaces 15 (or the entire surface of the structure) with a homogeneously stable, saline acidic aqueous solution containing a ferricyanide anion capable of oxidizing metallic silver and an organic cationic complexing agent capable of forming an insoluble in water with oxidized silver as defined below. , oleophilic complex. By homogeneously stable is meant that the ferricyanide anion and the organic cationic complexing agent are substantially non-reactive with each other. Background regions 17 remain hydrophilic.

Figure 2 shows an alternative method of manufacturing a flat plate. Step A shows the carrier plate 18 supporting the emulsion layer 16. Step B shows the structure of step A after it has been exposed to the image. The structure of step B is then contacted with a developer solution to impregnate layer 16.

When the layer 16 becomes saturated with the developer, a composite structure is formed, as shown in step C, wherein the layer 16 is fitted against the hydrophilic layer 14. Layer 14 contains a metal ion reduction promoter.

Step K shows the structure of step C after the soluble silver halide has migrated, i.e. diffused from layer 16 together with the developing solution to layer 14 and has come into contact with a din metal ion reduction promoting agent, whereby silver is reduced to the metallic state.

In step E, the plate is shown after the emulsion layer has been removed therefrom. The surfaces 15 of the plate comprise metallic silver and are rendered oleophilic by contacting them homogeneously with a stable activator solution.

A useful oxidizing agent herein is an alkali metal ferricyanide that is soluble in water, e.g., potassium ferricyanide of the formula Ki [Fe (CN) g]. Although alkali metal dichromates are useful as oxidizing agents in the activator solution, they do not naturally form an oleophilic silver imaging region. Inherently, oleophilic refers to areas of silver imaging that accept inks without the need for prior treatment with an excipient solution, varnish, etc.

The organic cationic complexing agent is derived from a protonatable nitrogen-substituted hydrocarbon compound containing 5,62425 formal iminine groups, i. C = N group, wherein the imine group is resonantly attached to adjacent groups in the compound.

By resonant linkage is meant that a formal imine group, together with adjacent groups in the molecule, causes a phenomenon known as resonance. This phenomenon means that the electronic structure of a molecule can be described in two or more ways, while the positions of the atoms remain unchanged. In this case, the actual electronic state of the molecule has a higher stability, i. higher negative potential energy than other private structures. See Glasstone, Textbook of Physical Chemistry, 7an Nostrand Co., Inc., New York, New York (1940), pages 110-111.

A structural condition for resonance to occur is that the imine group in the hydrocarbon compound must be in conjugation with the C = C group or another imine group, or it is attached to a nitrogen atom. This can be represented graphically by the following structural notation:

(C = N) -Z

wherein Z represents C = N, C-C, or N, and wherein Z may be attached to either a carbon atom or a nitrogen atom of the imine group.

Resonance stabilizes the imine-functional group and thus provides a high degree of oleophilicity to the image surfaces formed by the complexed silver.

Examples of nitrogen-substituted hydrocarbon compounds are cyclic and acyclic amidines, i. compounds having a formal chemical group:

-OF

> E2

-OF

T

R 1 wherein R 1 and R 8 may be hydrogen, hydrocarbons or nitrogen-substituted hydrocarbons belonging to the alkyl, aryl or aralkyl group, and wherein the cyclic or cyclic amidines are supplemented with hydrocarbon groups to form 5- or 6-membered ring structures. Examples of acyclic amidines are acetamidine, benzamidine, guanidine and biguanide. Typical cyclic amide # and are 2-propyl-2-imidazoline, 2-pentyl-2-imidazoline, 2-benzyl-2-imidazoline and naphthazoline.

Further examples of suitable complexing agents include aromatic nitrogen-substituted heterocyclic aromatic compounds, such as 5- and 6-membered cyclic or bicyclic compounds containing one or more nitrogen atoms, including their monosubstituted or poly-substituted hydrocarbon-substituted hydrocarbon-functional compounds. Examples of 6,624,255 aromatic heterocyclic compounds include 2-methylimidazole, 1-benzylimidazole, ί-butylimidazole, 2-undecylimidazole, 2,2 * -dipyridylamine, 2,4-lutidine, pyridine and N-aminopyridine. . Bicyclic compounds include benzimidazole, 2-methylbenzimidazole and 1-ethyl-2-methylbenzimidazole.

The aromatic nitrogen heterocyclic compounds must all contain at least one nitrogen atom in the basic ring structure which is sterically unimpeded so as to be able to coordinate with the silver ion, i. that it is capable of mating a chemical compound with it.

Activator solutions useful herein can be prepared simply by mixing an alkali metal ferricyanide salt, e.g., potassium ferricyanide, an organic nitrogen compound, and a sufficient amount of concentrated acid to protonate the organic nitrogen compound, e.g., HCl, with water. Alternatively, instead of using an acid, a hydrohaloid salt of an organic compound may be used. To ensure proper oxidation of the metallic shame, at least about 0.01 moles of ferricyanide salt per liter of solution should be used.

It has been shown that the cationic derivatives of organic nitrogen-containing complexing compounds and the ferricyanide anion, i.e. [Fe (CN) g] - ^, represent the least soluble ion pair or salt when mixed with water as described above. By evaporating the water from the solution or using another similar method which affects the solubility, salt crystals of this least soluble ion pair are formed and can be efficiently separated from the solution. This new ferricyanide salt of the protonated organic nitrogen-containing complex-forming compound can then be conveniently redissolved in water to provide an activator solution to render the metallic silver surfaces inherently oleophilic.

The water solubility of the salt formed due to the interaction between the cationic derivatives of the organic moiety as defined above and the ferricyanide anion should be greater than about 0.01 moles per liter to provide a sufficient amount of ferricyanide anion to effectively oxidize the metallic silver.

The invention is further illustrated by the following examples.

Example 1

The backing sheet, which consists of a 0.1 mm (100 micron) thick polyethylene terephthalate film, is coated on one surface with an 8 micron thick (dry) organophilic layer, the organophilic layer being formed from a solution containing 4Θ printing solids (vinyl chloride) "sold under the trade name Union Carbide) and titanium dioxide pigment (" Unitane OR350 "sold under the trade name American Cyanaaid) in a ratio of 3 parts by weight of titanium dioxide to one part by weight per vinyl chloride acetate resin. The pigment is dispersed before After coating, the solution on the support plate is dried at 66 ° C for 5 minutes.

The support plate thus coated is then coated with a hydrophilic layer, the composition of which is shown below, and then dried for 20 seconds at 66 ° C.

Ingredient Quantity "Nalco 1030", colloidal silica ($ 30 solids; available in 800 grams under the trade name Nalco Chemical Company)

696 grams of water

Glycerin 15 grams "Silver Protein Mild" (diluted $ 10 solids in water »; available in 8 milliliters called Merck and Co., Inc.)

A high contrast chlorotromide photographic emulsion (e.g., one with a chloride / bromide ratio of 2: 1 and a gelatin / silver ratio of 1.2: 1) is then applied as a coating to the hydrophilic layer so that the weight of the silver coating becomes 20 mg per square decimetre.

A 25.4 cm x 40.64 cm plate of the above material is placed on a vacuum plate of a Robertson 320 process camera equipped with an image-turning lens. The plate is then exposed to a positive, positive line copy original image for 12 seconds at an aperture of 32. The exposed plate is then immersed for 30 seconds in a diffuse transfer developer of the following configuration at a temperature of 22 ° C.

Ingredient Amount of deionized water 1000 ml sodium sulphite 80 grams hydroquinone 35 grams sodium thiosulphate 15 grams sodium hydroxide 28.5 grams potassium bromide 2.5 grams 0.5 μm. by way of an aqueous solution of benzotriazole 25 ml. After immersion in the developer, a silver negative image appears at the exposed points, and after a short time, a silver positive image forms in the hydrophilic layer. The emulsion layer is then removed by running tap water at a temperature of about 110 ° C over the plate for about 20 seconds to expose the underlying hydrophilic surface containing the positive silver image (i.e., metallic silver), leaving at least a portion of the metallic silver remaining hydrophilic. layer surface.

The plate is then immersed for 25 seconds at room temperature in a homogeneously stable activator solution containing the following ingredients: Amount of potassium ferricyanide 35 * 0 grams of sodium chloride 17 → 5 grams of 2-benzyl-2-imidazoline hydrochloride 10.0 grams of deionized water (enough to comes 1 liter)

The plate is then washed with water for 5 seconds and dried. Clearly visible positive image areas are color receptive and background areas remain hydrophilic. To further improve the color / water balance, the plate can be rubbed with a $ 0.5 aqueous solution of sodium oleate if desired.

The plate is attached to a flatbed press and used to make thousands of good quality copies.

The aforementioned homogeneously stable solution remains substantially stable (i.e., active and homogeneous) indefinitely. After standing for a long time, some foaming of the solution can be observed, but this has no effect on the ability of the solution to make metallic silver surfaces inherently oleophilic. An amount of five gallons of this solution is sufficient to handle more than 15,000 plates of the type described in this example.

Sodium chloride is added to the activator solution shown in the example above to aid in the oxidation of metallic silver. Other alkali metal / halide salts can be used for the same purpose. If desired, other additives may be added to achieve a particular purpose as long as such a component does not react with either the cationic organic complexing agent or the ferricyanide anion.

Example 2

A solution similar to the activator solution of Example 1 was prepared by first dissolving 6.60 g (0.02 moles) of potassium ferricyanide in 200 ml of water. To this solution was added 7-08 g (0f04 moles) of 2-benzyl-2-imidazoline hydrochloride, and the resulting mixture was heated until complete dissolution. The solution was cooled to 0 ° C overnight, resulting in the separation of yellow crystals from the solution.

The crystals were collected and recrystallized twice by dissolving them in a small amount of water at 50 ° C and then cooling. The twice recrystallized salt was dried in vacuo using phosphorus pentoxide.

The resulting ferricyanide salt was calculated to contain 62.1 wt% carbon, 5 → 6 wt% hydrogen, 24 → 5 wt% nitrogen, and 0.1 wt% iron based on elemental analysis. Assuming that a salt is formed from the protonated imidazoline compound and ferricyanide, its simplified formula would be C Calculation of the theoretical weight amounts results in $ 62.1 carbon, 5 »6 (hydrogen, 24.3 1 ° nitrogen, and $ 8.0 iron, which values are consistent with the actual amounts obtained by elemental analysis.

As an additional experiment of salt assembly, 1.39 grams (0.002 moles) of yellow crystals were dissolved in 50 ml of water, followed by the addition of 0.45 g (0.006 moles) of potassium chloride.

To this solution was added 500 ml of absolute ethyl alcohol to effect ion pair metathesis, i. to change the solubility properties between the ion pairs so that the least soluble ion pair is no longer a ferricyanide anion and an organic nitrogen-substituted hydrocarbon cation. A yellow precipitate formed which, according to analysis, turned out to be almost pure potassium ferricyanide.

When a plate with metallic silver image areas formed according to Example 1 is treated with an aqueous solution of the ferricyanide salt of the protonated imidazoline compound formed simply by dissolving the salt in water, the silver image areas become inherently oleophilic and thousands of excellent impressions can be made using the plate.

Example 5-14

Separate activator solutions are prepared by mixing 0.06 moles of concentrated hydrochloric acid, 0.03 moles of potassium ferricyanide, and 0.06 moles of organic nitrogen compound 500 in any water, followed by the addition of sufficient water to give a volume of 1.0 liter. The following are used as organic nitrogen compounds: acetamidine, 2-propyl-2-imidazoline, 2-pentyl-2-imidazoline, guanidine, biguanide, 1-benzylimidazole, 2-methylbenzimidazole, 1-ethyl-2-methylbenzimidazole, pyridine, 2.4 -lutidine, N-aminopyridine and 2,2, -dipyridalamine.

When each of these activator solutions is used instead of the activator solution of Example 1, inherently oleophilic silver image regions result and a flatbed plate is thus obtained.

Example 15

A solution was prepared by dissolving 4 to 12 g (0.0125 moles) of potassium ferricyanide 50 in any water. To this solution were added 2.05 ml of concentrated hydrochloric acid and 3 .mu.l (0.025 mol) of 4-phenylimidazole. A precipitate immediately formed which was collected and dried in vacuo over phosphorus pentoxide. Elemental analysis compared to theoretical calculations clearly shows that the compound is the ferricyanide salt of protonated imidazole.

The salt was placed in any water and stirred to form a saturated solution and used to treat a 10,624 image imaged with metallic silver prepared as described in Example 1 to give a printing plate with oleophilic silver image areas.

Example 16

A solution was prepared by dissolving 16.50 g (0.05 moles) of potassium ferricyanide 200 in any water. To this solution were added 8.26 ml of concentrated hydrochloric acid and 16.02 g (0.10 mol) of 1-ethyl-2-methyl'benzamidazole. A yellow precipitate immediately formed and was collected. The precipitate was redissolved in 250 ml of warm water (50 ° C) and the solution was allowed to cool to room temperature, whereupon a yellow precipitate formed. The yellow crystals were collected and air dried. When the result of the elemental analysis was compared with the theoretical calculations, the solid turned out to be the ferricyanide salt of the clearly protonated imidat-Sol. A saturated solution was prepared by placing the salt in 10 ml of water while stirring, and the solution was treated with a silver image printing plate formed according to Example 1 to obtain the results of Example 15.

Example 17

A solution was prepared by dissolving 9.90 g (0.03 moles) of potassium ferricyanide in one liter of water. To this solution were added 4.96 ml of concentrated hydrochloric acid and 7 * 08 g (0.06 mol) of henzimidazole. After allowing the solution to stand for about one day at room temperature, yellow crystals formed. These crystals were collected and air dried. Compared to theoretical calculations, Elemental analysis clearly showed the crystals to be the ferricyanide salt of protonated imidat-Sol.

The saturated solution, prepared by mixing the salt with 10 ml of water, formed an excellent activator solution on the silver metal image plate formed according to Example 1.

Example 18

A solution was prepared by adding 3 x 50 g (0.01 mol) of potassium ferricyanide to 150 ml of water. To this solution were added 1.65 ml of concentrated hydrochloric acid and 4.48 g (0.02 mol) of 2-undecyl-2-imidazoline, the latter being added slowly while stirring the solution vigorously. A yellow precipitate immediately formed which was collected and dried. Compared to theoretical calculations, Elemental analysis of the solid clearly showed that the substance was the ferricyanide salt of protonated imidazoline.

A saturated solution prepared by mixing salt 10 with any water formed an excellent activator solution capable of making hcpea metal image plates inherently oleophilic in image areas.

Example 19

A solution was prepared by dissolving 2.5 g (0 * 0075 moles) of potassium ferricyanide in any water. To this solution was added 15 ml of an aqueous solution containing 2.11 g (0.015 mol) of 2-phenyl-2-imidazoline and 0.55 ml of concentrated hydrochloric acid. A yellow precipitate immediately formed. The solid was collected and dried. Elemental analysis, when compared to theoretical calculations, clearly showed that the crystals were the Ferri cyanide salt of protonated imidazoline.

A saturated solution prepared by mixing the salt with 10 ml of water formed an excellent activator solution as in the above examples.

Example 20

A solution was prepared by dissolving 16.5 6 (0.05 mol) of potassium ferricyanide in 10 ml of water. To this solution were added 16.42 g (0.20 mol) of 2-methylimidazole and 16.5 nil of concentrated hydrochloric acid. The volume of the solution was reduced without the use of heat until a considerable amount of solid appeared on the bottom of the flask. When the solid was collected, white crystals and yellow crystals were seen. The solid was stirred in methanol to dissolve the yellow solid. The yellow solution was then separated by decantation and therefore reduced in volume until yellow crystals formed. The crystals were collected and dried, and Elemental analysis, comparing its results with theoretical calculations, showed the substance to be the ferricyanide salt of protonated imidazole.

A saturated solution prepared by mixing salt 10 with any water formed an excellent activator solution to naturally make the silver metal surfaces oleophilic.

Example 21

A solution was prepared by dissolving 8.25 S (0.025 moles) of potassium ferricyanide 50 in any water. To this solution were added 4.13 ml of concentrated hydrochloric acid and 7.6 g (0.05 mol) of 1-benzylimidazole. The solution was cooled in cold water for 15 minutes to form a precipitate. The solid was collected and dried. Elemental analysis, comparing its results with theoretical calculations, showed the substance to be the ferricyanide eu of protonated imidazole.

The saturated solution, prepared by mixing the salt with 10 ml of water, formed an excellent activator solution to naturally make the silver metal image areas oleophilic.

In some of the above examples, it can be seen that the old ferric cyanide salt compound was formed almost immediately. This is, of course, due to the fact that the excess component was intentionally added to exceed the solubility limits of the salt in solution. The same results could have been obtained by other methods to reduce the solubility of the salt, e.g. by cooling the solution or removing part of the water.

In some cases, it has been found that the solubility properties of ion pairs in solution are such that the salt formed contains a cationic moiety comprising one potassium ion and two ions of protonated organic matter ✓ in contrast to the above examples where the cationic moiety comprised three ions of protonated organic matter.

Example 22

A solution was prepared by stirring 3.30 g (0.01 mol) of potassium ferricyanide in 150 ml of water. To this solution were added 0.83 ml of concentrated hydrochloric acid and 4.94 S (0.02 mol) of naphthazoline hydrochloride, the latter being added slowly with vigorous stirring. A yellow-green solid was immediately obtained. The solid was collected and placed in 300 any water and heated to about 70 ° C. A portion of the solid dissolved, after which the solution was separated from the solid and allowed to cool to room temperature. After cooling, greenish crystals formed which were collected and dried. Elemental analysis, comparing its results with theoretical calculations, showed that the crystals were a ferricyanide salt in which the cationic moiety comprised one ion of potassium and two ions of protonated naphthazoline.

A saturated solution prepared by mixing the salt with 10 ml of water formed an excellent activator as in the previous examples.

Example 23

A solution was prepared by dissolving 8.6 g (0.026 mol) of potassium ferricyanide in 20 ml of water. To this solution was added 5.0 g (0.053 mol) of acetamidine hydrochloride in small portions while heating the solution. At the same time, small amounts of water, about 2 ml each, were added, therefore, until complete dissolution was achieved. Water was removed from the solution by means of a rotary evaporator until yellow crystals appeared. The crystals were collected and dried. Elemental analysis, comparing its results with theoretical calculations, showed that the substance was a ferricyanide salt in which the cationic moiety consisted of two acetamidine ions and one potassium ion.

A saturated solution prepared by mixing the salt with 10 ml of water formed an excellent activator as in the previous examples.