CA1150089A - Clear aqueous developers for lithographic plates including an active solvent and a water miscible cosolvent - Google Patents
Clear aqueous developers for lithographic plates including an active solvent and a water miscible cosolventInfo
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- CA1150089A CA1150089A CA000324931A CA324931A CA1150089A CA 1150089 A CA1150089 A CA 1150089A CA 000324931 A CA000324931 A CA 000324931A CA 324931 A CA324931 A CA 324931A CA 1150089 A CA1150089 A CA 1150089A
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Abstract
Case 790315 CLEAR AQUEOUS DEVELOPERS FOR PHOTOPOLYMER LITHOGRAPHIC PLATES Abstract of the Disclosure A single-phase, non-emulsion aqueous solution subtractive developer for lithographic plates having photopolymer coatings is provided. These clear developers are aqueous solutions in-cluding an active or primary solvent which is only partially soluble in water and which is a good solvent for the photopolymer of a lithographic plate that has not been exposed to and insolublized by actinic radiation, this active solvent typically being present at a concentration near its water solubility limit. Preferably, a cosolvent is also included to increase the water solubility of the active solvent when necessary. A desensitizer may be included to impart to the formulation the properties of a one-step developer or of a finisher, the desensitizer being a hydrophilic synthetic resin. Formulation and development methods for these developers are also included, and they may be used either as developers or as a machine developer solution replenisher.
Description
Case 3!l~L~
SPECIFICATION
Background and Description of the Invention This invention generally relates to developers for lithographic plates, especially clear, subtractive developers that are of the single-phase, non-emulsion aqueous solution type.
More particularly, the present invention is directed to an improved developer composition and method of preparing and using it, including a solution of an active solvent that is only partially soluble in water but that is a good solvent for the unexposed photopolymer of the plate being developed, the active solvent preferably being present at a concentration near its water solu-bility limit. In another important aspect of this invention, the composition includes a hydrophilic synthetic resin desensitizer at low concentrations in order to render the composition a one-step developer or a finisher as well as a developer.
Developers for photosensitive lithographic plates can be said to fall into two general classes, emulsion developers and non-emulsion developers. Emulsion developers are often addi-tive developers in that they add coloring to -the image and usually include a reinfor~ing resin to coat and strengthen the plate image area. Subtractive type emulsion developers are also known, such as S85CKK (Richardson Graphics)! this being a color-less emulsion developer which takes away non-image coloration in developing a photopolymerizable plate. Other emulsion developers are mentioned in Hall U.S. Patent No. 2,754,279. Entirely organic or primarily all organic developers are shown in Martinson et al., U.S. Patent No. 3,707,373. Parker et al. U.S. Patent No. 3,909,269 mentions that ethylene glycol monoethyl ether acetate (2-ethoxyethyl acetate) may be employed by itself or in emulsion form as a developer for the photopolymers of that patent.
Emulsion developers typically include water at varying percentages. Being an emulsified composition of organic compounds, emulsion developers tend to separate on storage and typically exhibit high viscosity levels making them unsuitable for use in lithographic plate processing machines, meaning that such developers will require hand working of the plate. ~lso, subtractive emulsion developers have some tendency to redeposit polymer removed from non-image areas onto image areas, resulting in unsightly specks on the developed plate, often leading to the rejection of that plate by the plate maker. Emulsion or all-organic developers, because of their high concentrations oE organic solvents, are generally expensive, possess unpleasant odors, and generate serious disposal problems.
It is accordingly desirable to provide a developer which is not an emulsion and which does not have large concentrations of organic solvents. Examples of developers or processing solutions which do not have large concentrations of organic solvents can be found in Larson U.S. Patent No. 3,136,637 and ~onham U.S.
Patent No. 3,905,815, which show developer systems that are a~ueous systems which include water miscible solvents.
Synthetic resin desensitizers useful in compositions for lithographic platemaking are discussed in Lawson U.S. Patent No. 4,033,919.
While aqueous systems having water miscible solvents ~5~
and low concentrations of organic solvents generally avoid many of the problems associated with emulsion developers or developers that are primarily or entirely organic solvents, these types of aqueous systems have certain drawbacks which limit their ability to be used within machine or automatic type developers. Since these developers are typically simple, single phase highly miscible solutions that supplyonly one-dimensional solvent properties for the overall lithographic plate system. they tend to directly solubilize the non-image area lithographic plate layers, making the removed polymer susceptible of being redeposited on the image areas by the mechanical operation of a developing machine which could other-wise be avoided by the skilled hand of an experienced operator~
Additionally, these types o developers can occasionally lead to problems because the one-dimensionally acting solvent may tend to attack the image areas on the plate if allowed to soak thereon for excessive periods of time.
Accordingly, there has been brought about a need for a two-dimensional type of developer which can selectively remove only the non-image areas of an exposed photopolymer plate with-out having the non-image areas dissolved within an entire single-phase solvent that can lead to redeposition of the removed polymer onto a plate by the mechanical, unthinking action of an automatic machine developing apparatus. Also needed is a developer that will not attack image areas on a plate, even if allowed to stand undisturbed on a plate being developed for excessive lengths of time.
By the present invention, it is now possible to have a non-emulsion, aqueous-type developer that exhibits improved selectivity properties which cause the unexposed photopolymer layer to be swollen and lifted off of the plate by an active solvent that will be absorbed out of the homogeneous solution by its affinity for the unexposed photopolymer but not the exposed photopolymer, which swollen photopolymercan then be removed by mechanical action, either by hand or as provided by machine developers, with the water remaining within the developer removing an unhardened diazo layer or similar type of resin layer that may be underneath the photopolymer.
These results are accomplished primarily by formulating a non-emulsion, single-phase aqueous solution to include an active solvent which is a good solvent for the unexposed photopolymer of the particular plate being treated but is only partially soluble in water, the active solvent preferably being present within the formulation at a concentration near its solubility limit in the aqueous system. The active solvent in such a developer has an affinity for the unexposed photopolymer on the plate that is greater than its tendency to remain within the single-phase aqueous developer solution, resulting in the general migration of the active solvent out of the non-emulsion developer to thereby form in situ a type of two-dimensional developer, with the amount of solvent needed to solublize the une~posed photopolymer being drawn out of the aqueous developer in order to dissolve the unexposed photopolymer, which dissolved photopolymer and active solvent can be readily and mechanically removed without redeposition or attack on exposed image areas, these results being brought about with a developer that has a substantial water content and with the advantages attendent to an aqueous developer solution.
It is, therefore, a general object of the present invention to provide an improved developer for lithographic plates which include photopolymer coatings.
Another object of the present invention is to provide a single-phase, clear developer for photopolymer lithographic plates suitable for use either in lithographic plate processing machines or by hand.
Another object of thls invention is to provide a developer in which the majority constituent is water so that the cost, odors, and disposal problems associated with organic solvents can be reduced.
Another object of the present invention is to provide an improved developer which, when used, eliminates or all but eliminates redeposition of removed non-image polymer back onto the plate, particularly the image areas thereof.
Another object of this invention is an improved developer that will desensitize, or render more hydrophilic, the non-image areas of lithographic photopolymer plates after removal of polymer therefrom in order to increase the ink-repellency of such areas during subsequent printing operations.
Another object of the present invention is to provide an improved developer which, after it is used, need not be rinsed off of the developed plate.
Another object of the present invention is the provision of an improved developer which will also perform the function of a finisher in order to gum or finish photopolymer lithographic plates after development to the extent that the developer is a one-step developer requiring no additional gumming or other treat-ment in order to form a clean running plate during printing, whether the plate is used immediately or is stored indefinitely before printing use.
Another object of this invention is to provide an improved developer formulation that is initially a single-phase developer having an active solvent which is selectively absorbed out of the single phase due to its af~inity for the unexposed photopolymer being greater than its tendency to remain within the aqueous system.
These and other objects o~ this invention will be apparent from the following further detailed description thereo~.
In its basic embodiment, the lithographic plate developer in accordance with this invention is a single-phase, non-emulsion aqueous solution subtractive developer having an active solvent which is a good solvent for the photopolymer of the particular plate being developed and which is only partially soluble in the aqueous system. Preferably, the active solvent is present within that system at a concentration near its solubility limit there-within. It is preferred that the active solvent be in solution in the presence of an organic cosolvent, operating as an extender or diluent, when it is necessary to render the system clear and homogeneous and in order to temper somewhat the photopolymer solubilizing activity of the active solvent. Also preferably included within the single-phase solution is a hydrophilic sur-factant to improve the ability of the solution to prevent redeposition of removed polymer onto the plate. When a single-step developer is desired or when the developer is to be used as a finisher, a hydrophilic synthetic resin desensitizer is included, preferably in combination with an acidity enhancing agent. In any possible formulation, the balance thereof will be water to make up an aqueous solution, which may include up to 90 weight percent or more water.
Essential to this invention is an active or primary solvent which is a good solvent for a lithographic plate photo-polymer and which is partially water insoluble or only partially soluble within the total aqueous sys-tem oE the developer. Such active solvents will have an affinity for the unexposed photo-polymer at the non-image areas of a lithographic plate which is greater than its tendency to remain at equilibrium within the aqueous developer solution, especially when the active solvent is at a concentration near its water solubility limit. An acceptable active solvent will be one having a boiling point of greater than 100 C. to make it less volatile than water or azeotropes at less than 100C.; it should also have an odor level and a toxicity low enough to render the developer acceptable for use in unvented locations and the active solvent should be re-latively inexpensive. Typical acceptable active solvents will have a moderate molecular weight. Preferred active solvents include those having ethylene glycol groups to impart water solubility properties thereto, together with acetate groups to provide the solvent with partial insolubility attributes.
Active or primary solvents may be glycol diacetates and diethers and glycol ether acetates; keto-ethers; cyclic ketones;
highly polar nitrogen-containing solvents; chlorinated hydro-carbons; and miscellaneous solvents having the requisite properties. Generally, the chlorinated hydrocarbons and the highly polar nitrogen-containing solvents will be less desirable due to the harshness properties usually associated with such compounds.
Examples of glycol diacetates and diethers and glycol ether acetates include 2-ethoxyethyl acetate; 2-methoxyethyl acetate;
SPECIFICATION
Background and Description of the Invention This invention generally relates to developers for lithographic plates, especially clear, subtractive developers that are of the single-phase, non-emulsion aqueous solution type.
More particularly, the present invention is directed to an improved developer composition and method of preparing and using it, including a solution of an active solvent that is only partially soluble in water but that is a good solvent for the unexposed photopolymer of the plate being developed, the active solvent preferably being present at a concentration near its water solu-bility limit. In another important aspect of this invention, the composition includes a hydrophilic synthetic resin desensitizer at low concentrations in order to render the composition a one-step developer or a finisher as well as a developer.
Developers for photosensitive lithographic plates can be said to fall into two general classes, emulsion developers and non-emulsion developers. Emulsion developers are often addi-tive developers in that they add coloring to -the image and usually include a reinfor~ing resin to coat and strengthen the plate image area. Subtractive type emulsion developers are also known, such as S85CKK (Richardson Graphics)! this being a color-less emulsion developer which takes away non-image coloration in developing a photopolymerizable plate. Other emulsion developers are mentioned in Hall U.S. Patent No. 2,754,279. Entirely organic or primarily all organic developers are shown in Martinson et al., U.S. Patent No. 3,707,373. Parker et al. U.S. Patent No. 3,909,269 mentions that ethylene glycol monoethyl ether acetate (2-ethoxyethyl acetate) may be employed by itself or in emulsion form as a developer for the photopolymers of that patent.
Emulsion developers typically include water at varying percentages. Being an emulsified composition of organic compounds, emulsion developers tend to separate on storage and typically exhibit high viscosity levels making them unsuitable for use in lithographic plate processing machines, meaning that such developers will require hand working of the plate. ~lso, subtractive emulsion developers have some tendency to redeposit polymer removed from non-image areas onto image areas, resulting in unsightly specks on the developed plate, often leading to the rejection of that plate by the plate maker. Emulsion or all-organic developers, because of their high concentrations oE organic solvents, are generally expensive, possess unpleasant odors, and generate serious disposal problems.
It is accordingly desirable to provide a developer which is not an emulsion and which does not have large concentrations of organic solvents. Examples of developers or processing solutions which do not have large concentrations of organic solvents can be found in Larson U.S. Patent No. 3,136,637 and ~onham U.S.
Patent No. 3,905,815, which show developer systems that are a~ueous systems which include water miscible solvents.
Synthetic resin desensitizers useful in compositions for lithographic platemaking are discussed in Lawson U.S. Patent No. 4,033,919.
While aqueous systems having water miscible solvents ~5~
and low concentrations of organic solvents generally avoid many of the problems associated with emulsion developers or developers that are primarily or entirely organic solvents, these types of aqueous systems have certain drawbacks which limit their ability to be used within machine or automatic type developers. Since these developers are typically simple, single phase highly miscible solutions that supplyonly one-dimensional solvent properties for the overall lithographic plate system. they tend to directly solubilize the non-image area lithographic plate layers, making the removed polymer susceptible of being redeposited on the image areas by the mechanical operation of a developing machine which could other-wise be avoided by the skilled hand of an experienced operator~
Additionally, these types o developers can occasionally lead to problems because the one-dimensionally acting solvent may tend to attack the image areas on the plate if allowed to soak thereon for excessive periods of time.
Accordingly, there has been brought about a need for a two-dimensional type of developer which can selectively remove only the non-image areas of an exposed photopolymer plate with-out having the non-image areas dissolved within an entire single-phase solvent that can lead to redeposition of the removed polymer onto a plate by the mechanical, unthinking action of an automatic machine developing apparatus. Also needed is a developer that will not attack image areas on a plate, even if allowed to stand undisturbed on a plate being developed for excessive lengths of time.
By the present invention, it is now possible to have a non-emulsion, aqueous-type developer that exhibits improved selectivity properties which cause the unexposed photopolymer layer to be swollen and lifted off of the plate by an active solvent that will be absorbed out of the homogeneous solution by its affinity for the unexposed photopolymer but not the exposed photopolymer, which swollen photopolymercan then be removed by mechanical action, either by hand or as provided by machine developers, with the water remaining within the developer removing an unhardened diazo layer or similar type of resin layer that may be underneath the photopolymer.
These results are accomplished primarily by formulating a non-emulsion, single-phase aqueous solution to include an active solvent which is a good solvent for the unexposed photopolymer of the particular plate being treated but is only partially soluble in water, the active solvent preferably being present within the formulation at a concentration near its solubility limit in the aqueous system. The active solvent in such a developer has an affinity for the unexposed photopolymer on the plate that is greater than its tendency to remain within the single-phase aqueous developer solution, resulting in the general migration of the active solvent out of the non-emulsion developer to thereby form in situ a type of two-dimensional developer, with the amount of solvent needed to solublize the une~posed photopolymer being drawn out of the aqueous developer in order to dissolve the unexposed photopolymer, which dissolved photopolymer and active solvent can be readily and mechanically removed without redeposition or attack on exposed image areas, these results being brought about with a developer that has a substantial water content and with the advantages attendent to an aqueous developer solution.
It is, therefore, a general object of the present invention to provide an improved developer for lithographic plates which include photopolymer coatings.
Another object of the present invention is to provide a single-phase, clear developer for photopolymer lithographic plates suitable for use either in lithographic plate processing machines or by hand.
Another object of thls invention is to provide a developer in which the majority constituent is water so that the cost, odors, and disposal problems associated with organic solvents can be reduced.
Another object of the present invention is to provide an improved developer which, when used, eliminates or all but eliminates redeposition of removed non-image polymer back onto the plate, particularly the image areas thereof.
Another object of this invention is an improved developer that will desensitize, or render more hydrophilic, the non-image areas of lithographic photopolymer plates after removal of polymer therefrom in order to increase the ink-repellency of such areas during subsequent printing operations.
Another object of the present invention is to provide an improved developer which, after it is used, need not be rinsed off of the developed plate.
Another object of the present invention is the provision of an improved developer which will also perform the function of a finisher in order to gum or finish photopolymer lithographic plates after development to the extent that the developer is a one-step developer requiring no additional gumming or other treat-ment in order to form a clean running plate during printing, whether the plate is used immediately or is stored indefinitely before printing use.
Another object of this invention is to provide an improved developer formulation that is initially a single-phase developer having an active solvent which is selectively absorbed out of the single phase due to its af~inity for the unexposed photopolymer being greater than its tendency to remain within the aqueous system.
These and other objects o~ this invention will be apparent from the following further detailed description thereo~.
In its basic embodiment, the lithographic plate developer in accordance with this invention is a single-phase, non-emulsion aqueous solution subtractive developer having an active solvent which is a good solvent for the photopolymer of the particular plate being developed and which is only partially soluble in the aqueous system. Preferably, the active solvent is present within that system at a concentration near its solubility limit there-within. It is preferred that the active solvent be in solution in the presence of an organic cosolvent, operating as an extender or diluent, when it is necessary to render the system clear and homogeneous and in order to temper somewhat the photopolymer solubilizing activity of the active solvent. Also preferably included within the single-phase solution is a hydrophilic sur-factant to improve the ability of the solution to prevent redeposition of removed polymer onto the plate. When a single-step developer is desired or when the developer is to be used as a finisher, a hydrophilic synthetic resin desensitizer is included, preferably in combination with an acidity enhancing agent. In any possible formulation, the balance thereof will be water to make up an aqueous solution, which may include up to 90 weight percent or more water.
Essential to this invention is an active or primary solvent which is a good solvent for a lithographic plate photo-polymer and which is partially water insoluble or only partially soluble within the total aqueous sys-tem oE the developer. Such active solvents will have an affinity for the unexposed photo-polymer at the non-image areas of a lithographic plate which is greater than its tendency to remain at equilibrium within the aqueous developer solution, especially when the active solvent is at a concentration near its water solubility limit. An acceptable active solvent will be one having a boiling point of greater than 100 C. to make it less volatile than water or azeotropes at less than 100C.; it should also have an odor level and a toxicity low enough to render the developer acceptable for use in unvented locations and the active solvent should be re-latively inexpensive. Typical acceptable active solvents will have a moderate molecular weight. Preferred active solvents include those having ethylene glycol groups to impart water solubility properties thereto, together with acetate groups to provide the solvent with partial insolubility attributes.
Active or primary solvents may be glycol diacetates and diethers and glycol ether acetates; keto-ethers; cyclic ketones;
highly polar nitrogen-containing solvents; chlorinated hydro-carbons; and miscellaneous solvents having the requisite properties. Generally, the chlorinated hydrocarbons and the highly polar nitrogen-containing solvents will be less desirable due to the harshness properties usually associated with such compounds.
Examples of glycol diacetates and diethers and glycol ether acetates include 2-ethoxyethyl acetate; 2-methoxyethyl acetate;
2-(2-ethoxyethoxy) ethyl acetate; triethylene glycol diacetate;
ethylene glycol diacetate; diethylene glycol diethyl ether;
dibutylene glycol diethyl ether; di.ethylene ~lycol dimethyl ether;
and triethylene glycol dimethyl ether. Examples of keto-ethers include 4-methoxy-4-methyl-pentanone-2; and examples of cyclic ketones include cyclohexanone and isophorone. Highly polar nitro~en-containin~ solvents include dimethylformamide; nitrobenzene;
l-nitro~ropane; 2-nitropropane; succinonitrile (butanedinitrile);
benzonitrile ~phenyl cYanide); and acetonitrile. Chlorinated hydrocarbon active solvents may include trichloroethylene and chlorobenzene. Examples of miscellaneous solvents include e-thyl lactate (ethyl ~-hydroxy propionate) and 2-methyl-2-ethyl-1,3 dioxolane.
Most preferred as the active solvent is 2-ethoxyethyl acetate because it is particularly inexpensive~ has low volatility and toxicity, and has only a mild odor. It also has especially acceptable partial water solubility properties, having a solubility in water of about 23.8 weight percent, meaning that, while it does exhibit limited water solubility, it is partially water insoluble and clearly not miscible with water. In general, the active or primary solvent can be present within the developer or machine developer solution replenisher at a concentration below its water solubili.ty limit, usually at a percentage no more than 10 weight percentage points less than or more than its water solubility limit, preferably no more than 7 weight per-centage points less than or greater than its water solubilitylimit, and most preferab].y no more than 3 weight percentage points less than and no more than 7 weight percentage points greater than its water solubility limit. The active solvent usually will make up between about 10 to about 40 weight percent of the developer or replenisher, preEerably between about 12 and 35 weight percent, and most preferably between about 15 to about 30 weight percent of the developer, based on total developer ; weight. It is to be appreciated that, since the concentration of the active solvent is generally keyed to its water solubility limit, these concentration ranges can vary depending upon the particular active solvent chosen.
When, as is preferred, a cosolvent is included in the single-phase, non-emulsion aqueous solution developer as an extender or diluent of the active solvent, such cosolvent must be compatible with -the chosen active solvent primarily for the purpose of avoiding a phase separation of the active solvent from the water within the formulation whereby effective levels of active solvent may be included within the single-phase aqueous _~ _ solution. The active solvent, the cosolvent and the water of these developers will, once they reach equilibrium, form a clear single phase that exhibits no light scattering.
Through the use of a cosolvent, the active solvent will be able to be included at a concentration that is even above if not actually substantially equal to its water solubility limit without experiencing undesirable phase separation when the developer is stored for lengthy periods of time. These co-solvents will be more miscible with water than will the active solvent with which each cosolvent is combined in any one formu-lation.
Typical cosolvents will be alcohols, glycols, glycol ethers, ketones, acetates and the like. Representative co-solvents include diacetone alcohol (~-hydroxy-~-methyl-pentanone-2); 2-(2-ethoxyethoxy) ethanol; 2-(2-methoxyethoxy) ethanol;
2-ethoxyethanol; 2-methoxyethanol; 2-butoxyethanol; glycerol;
ethylene glycol; propylene glycol; diethylene glycoli tri-ethylene glycol; tetraethylene glycol; a polyethylene glycol;
methyl alcohol; ethyl alcohol; n-propyl alcohol; isopropyl alcohol; acetone; methyl ethyl ketone; acetyl acetone; and ethyl acetate.
Examples of preferred solvents include diacetone alcohol and 2-ethoxyethanol, since each may be used in relatively low concentrations while still rendering the single-phase solution developer clear and homogeneous. Also to be considered in selecting one of these various cosolvents are the relative costs thereof. Cosolvents of high volatility and toxicity are less desirable. Concentration levels for the cosolvent within the ~:5~
total single-phase, non-emulsion aqueous solution developer can range between zero and about 30 weight percent, preferably between about 2 and about 25 weight percent, and most preferably within a range of between about 5 to about 15 weight percent.
These concentration ranges will be variable depending upon the particular combination of active solvent and cosolvent, and is especially dependent upon the limit of water solubility for the active solvent being cosolubilized or extended.
Especially advantageous results obtain when the single-phase aqueous developer solution further includes a surfactant,which will all but eliminate any possible redeposition problems.
Surfactants that are especially hydrophilic will be particularly useful in avoiding image area solubilization and excessive softening of the removed photopolymer. Surfactants will function to assist in making the developer formulation a clear one, to aid in wetting the photopolymer surface as the developer solution is applied, and to operate as a wetting agent for the removed polymer in order to prevent redeposition. The surfactant is also believed to help control the amount of total solvent absorption by the photopolymer which can lead to an overly soft condition resulting in redeposition on image areas. Concerning its wetting function, the surfactant will cause the homogeneous developer solution to surround photopolymer globules as they are removed, rather than surrounding them with active solvent which could make them generally tacky and inclined to adhere to image areas.
Excessive surfactant concentrations render the developer solution too foamy, may result in some image loss, and/or may ~s~
reduce developer activity. Surfactant concentrations, based on the total weight of the developer solution, can range from zero to about 5 weight percent, preferably from about 0.01 to about 2 weight percent and most preferably between about 0.05 and about 1.0 weight percent.
Surfactants useful in this ~ormulation should be hydro-philic. They may be either nonionic, cationic, anionic, or amphoteric, the nonionic surfactants being generally preferred.
Any one of a number of known surfactants can be incorporated such as those including ethylene oxide groups as their hydro-philic constituent. Representative of this type are an ethoxylated long chain tridecyl alcohol composition of medium viscosity (about 116 cps) having a molecular weight o~ 770; and certain block copolymers of propylene oxide and ethylene oxide terminated at both ends with polyethylene oxide groups haviny a ~-hydro-omega-hydroxy-poly(oxyethylene)poly(oxypropylene)poly(oxyethylene) block copylymer structure as described in U.S. Patent No. 2,674,619.
Acceptable examples of this latter group of block copolymers are those having 40~ polyoxyethylene hydrophilic units in the total molecule, the poly(oxypropylene) hydrophobe having a typical molecular weight of about 1750 and those having 50~ polyoxyethylene units in the molecule, the hydrophobe having a typical molecular weight of about 3250, the latter polymer being especially preferred because it can be used at a very low level while still being effective in bringing about the results desired by the surfactant when it is included within the aqueous solution developers.
In proceeding with another aspect of this invention, the single-phase, non-emulsion aqueous solution developer may be modified into a one-step developer, which modification also makes it suitable for use as a finisher as well as a developer.
The modification is accomplished by including a desensitizer within the total single-phase formulation, typically a desensitizer which is a hydrophilic synthetic resin.
An acceptable desensitizer will render more hydrophilic the non-image areas of lithographic plates after the photopolymer has been removed therefrom so that these areas will be ink-repellent during printing. They will assist in avoiding scummingor toning of these non-image areas during printing, which can often occur even after lithographic plates have been developed and gummed. Also, the inclusion of a desensitizer in accordance with this aspect of the invention will result in the improved development of plates that have been stored for several months prior to exposure and development.
In addition to being hydrophilic, the desensitizer should be soluble in and compatible with the rest of the aqueous system of the developer. Usually, the desensitizer will be a synthetic resin that is hydrolyzed or alcoholized to a significant and sub-stantial level. Resins that have been hydrolyzed to particularly high levels axe most suitable. Hydrophilic synthetic resin desensitizers include styrene-maleic anhydride copolymers which have been hydrolyzed or alcoholized, vinyl ether-maleic anhydride copolymers which have been hydrolyzed, and modified polyacrylamides having a molecular weight of about 200,000 and a minority carboxyl content.
Preferred is a hydrophilic synthetic resin that is a poly~
acrylamide having a molecular weight of approximately 200,000 in which approximately 70 percent of the acrylamide groups thereof have been hydrolyzed to acrylic acid groups and that can be thought of as a 70/30 copolymer of sodium acrylate and acrylamide which is predominately in salt form and therefore alkaline.
Amounts of this desensitizer typically incorporated within these developer formulations can be as high as about 5 percent by weight based upon the total weight of the developer :Eormulation, this upper limit being variable depending upon the specific desensitizer and being determined generally by the viscosity increases brought about by the inclusion of these ~` resins into the solution. The extent of solubility within the aqueous formulation is also a limiting factor on the amount of desensitizer that can be included. A typical preferred range will be between about 0.5 and about ~ weight percent. An : especially preferred range for the preferred polyacrylamide resin is between about 0.5 and about 1.5 weight percent.
Since a desensitizer will generally be predominately in salt form be~ore inclusion within the formulation in ac-cordance with this invention, best desensitization properties will be achieved by rendering the developer somewhat acidic, which will increase the solubility of the desensitizer within the single-phase, non-emulsion aqueous solution developer. It is accordingly preferred to include an acidity agent in the formulations which include desensitizers that are provided in `:~
alkaline form. Typical acidity agents will be weak mineral acids and acidic salts thereof, as well as organic acids and acidic salts thereof, added in concentrations that will generally lower the pH of the developer or finisher to between about 4.5 and 5.5. Examples include lactic acid, phosphoric acid, ammonium dihydrogen phosphate, citric acid and its acidic salts, acetic acid, tartaric acid, and the like, the preferred agent being lactic acid. Such an acidity agent can be included in amounts from zero to about 5 weight percent based upon the total weight of the developer solution, preferably between about 0.5 to about 2 weight percent.
Miscellaneous materials may further be included within the sinc~le-phase, non-emulsion aqueous solution developers in accordance with this invention. These include defoamers, anti-foamers, synthetic resin viscosity increasing agents such as hydroxypropyl cellulose, colorants, corrosion inhibitors, chelating agents, humectants, antioxidants, and buffers. If needed to insure ready acceptance of ink by the image areas of the developed photopolymer plate, hydrophobic defoaming materials compatible with the aqueous solution could be added up to about 0.1 weight percent of the composition, such as Carboset (Trade Mark) resins or ~-nydro-omega-hydroxy-poly(oxyethylene)poly(oxypropylene)-poly(oxyethylene)block copolymer hydrophobic surfactants having only about 10%
polyoxyethylene groups in the total molecule and polyoxypropylene hydrophobes of molecular weights from about 900 to about 1800.
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..
Developers made in accordance with this invention will be of the subtractive type, meaning that they take away non-exposed or non-crosslinked photopolymers, which makes them particularly suitable for use in conjunction with subtractive developable negative-working plates. The invention is capable of developing negative working plates which are normally developed by an additive type of developer.
As a general proposition, developers in accordance with this invention will develop lithographic plates that are sus-ceptible to a typical photo-insolubilization process. They are particularly well suited for developing photopolymer litho-graphic plates known as 3-R plates, S-85 plates, and S-56 plates (Richardson Graphics), which are brush grained, anodized and subbased aluminum plates coated with a thin layer (2-lO
mg./sq. ft.) o~ diazo material which is then overcoated with a moderate layer (20-120 mg./sq. ft.) of cinnamate photopolymer, such as generally described in U.S. Patent No. 3,808,004.
Numerous other plates can be adequately developed according to this invention; the principle requirement is that they include a polymer that is swellable by the active solvent. When used as a hand developer, this invention will be suitable for developing almost any presently known photopolymer lithographic plate.
When machine development is to be practiced, the developer is particularly suitable for plates having cinnamate photopolymer layers.
In proceeding with the method in accordance with this invention, the active solvent is dissolved in water to near its water solubility limit, preferably with the assistance of the cosolvent extender or diluent in the proportions specified herein. Small amounts of surfactant may also be included to improve the general wetability of the developer formulation pre-pared. Other optional ingredients may be put into solution, such as defoamers, antifoamers, viscosity increasing agents, colorants, corrosion inhibiters, chelating agents, humectants, antioxidents, buffers, and hydrophobic materials. By another aspect of this method, the hydrophilic synthetic resin de-sensitizers are added, with stirring, up to about 5 weight percentin order to provide a formulation that is both a one-step developer and a formulation suitable for finishing as well as developing.
When the desensitizer put into solution is alkaline, best de-sensitization properties are usually realized by dissolving an acidity agent into the formulation.
After these solution forming steps are completed, the resulting formulation is a single-phase, non-emulsion aqueous subtractive developer for lithographic plates having a swellable photopolymer layer. During development, the method is believed to proceed by the following steps.
When the developer is applied to an exposed lithographic plate, either by hand with a developer-saturated developing pad or by machine with the brushes or the like of automatic plate processors which recirculate developer after filtering out re-moved polymer particles, the developer will be allowed to presoak into the plate for a total period of time between about 10 seconds to about 60 seconds, depending upon the temperature, the size of the lithographic plate, and/or the capabilities of the pro-cessing machine. During this presoaking period, the active i3'9 solvent, which may be accompanied by some of the cosolvent, is ab-sorbed out of the homogeneous single-phase developing solution and into the photopolymer due to its affinity for the swellable photopolymer layer being greater than its tendency to remain in solution at or near its water solubility limit. This absorbing step results in a swelling of the photopolymer which is followed by mechanically re-moving the swollen polymer, either by hand rubbing or automatically within a processing machine. When the plate being developed includes a diazo resin layer or other water soluble layer, the water within the formulation will solubilize this underlying, unhardened layer for removing it from the plate in the non-image areas.
During these developing steps, each of the other components dissolved within the formulation function in accordance with their intended purpose when included within the formulation. Generally, if the developer formulation contains too much active solvent or too little cosolvent when included, the developer formulation will be too active and will tend to a-ttack the image areas of the plate. sut if the ~ormulation contains too little active solvent and/or too much cosolvent, the unexposed photopolymer will not be completely removed from the non-image areas of the photo-lithographic plate.
For formulations that do not include the hydrophilicdesensitizer, the developed plate will then typically be subjected to secondary development steps common to a two-step process, including rinsing the plate thoroughly with tap water to remove polymer globules and remaining developer from the plate surface, usually in conjunction with gently rubbing the plate with a wet sponge or the like, after which the plate may then be s~eegeed or buffed dry with absorbent material such as paper tissue, followed by gumming with any conventional litho gum or gum asphaltum etch. When a desensitizer is included, the same secondary development steps can be proceeded with, or they can be omitted in order to accomplish a one-step developing procedure by merely wiping off the excess developer and by omitting the subsequent water rinsing and gumming steps.
Alternatively, the developing formulation can be used also as a finisher, in which case the water rinsing and gumming can also be omitted, although the water rinsing step can be pro-ceeded with if desired; thereafter, the developing formulation is applied as a finisher with a plain pad, absorbent tissue, or the like, followed by bufEing the plate dry with absorbent tissue.
The following speciEic examples will more precisely illustrate the invention and teach the procedures presently preferred for practicing the same, as well as the improvements and advantages realized thereby.
EXAMPLE I
Various formulations were made including from 20 through 50 weight percent of 4-methoxy-4-methyl-pentanone-2 as the active solvent, together with from 10 through 20 weight percent of diacetone alcohol as the cosolvent, the balance being water.
These compositions were found to be ~seful and tested well in their ability to develop S-85 photopolymerizable lithographic plates at moderately fast speeds. The developer was a sing]e-phase,non-emulsion aqueous solution subractive developer.
EXAMPLE I I
A moderately fast single-phase, non-emulsion aqueous solution subtractive developer was formulated by mixing 25 weight percent of 4-methoxy-4-methyl-pentanone-2 with 75 weight percent water. This developer was tested on and found to develop an S-85 plate to a clean background and satisfactory image. Concentrations less than 25 weight percent also exhibited developing properties.
EXAMPLE I I I
At 15 weight percent 2-ethoxyethyl acetate formed a single-phase solution in water which made up the remaining 85 weightpercent thereof. Although the rate was slow, plate development was satisfactory; when tested upon a S-85 plate, it gave a clean background and a satisfactory image.
EXAMPLE IV
On a 100 parts by weight basis, 23 weight percent 2-ethoxyethyl acetate, 10 weight percent 2~ethoxyethanol, and 0.1 weight percent propylene oxide and ethylene oxide block copolymer surfactant having polyethylene oxide groups at both ends, having about 50~ polyoxyethylene units in the total molecule, and having the polyoxypropylene hydrophobic units at a molecular weight of about 3250, were dissolved within 66.9 weight percent water to form a single-phase, non-emulsion aqueous solution subtractive developer which was suitable for either hand development or machine development or a cinnamate overcoated subtractive lithographic plate.
In proceeding with the hand development, an exposed subtractive plate was placed on a developing table, and a short nap pad held flat in a pad clamp was saturated with this developer, followed by application to the entire plate without exerting any substantial pressure on the plate until the entire plate was covered with developer. The developer was allowed to soak into the plate surface for about lO seconds, after which a re-saturated developing pad was rubbed over the plate with moderate pressure to remove the coatings in the unexposed areas of the plate by using long, straight strokes along the length and the width of the plate. Development was continued until all the polymer was removed from the non-image areas, the smaller plates taking a total of about 45 seconds to develop and larger plates about 90 to 120 seconds at 70 F.
The thus developed plate was then rinsed thoroughly with tap water to remove the remaining developer and polymer globules from the surface, the rinsing being accompanied by gentle rubbing with a wet sponge. This was ~ollowed by drying the plate with absorbent paper tissue, and then by gumming with a conventional lithographic gum asphaltum etch to make it ready for storage or use on a lithographic printing press.
Another amount of this developer was tested within a 440 Processor automatic developing machine of the rotary brush drum type by feeding the exposed plate into the entrance slot while the feed foot switch was activated. The plate which emerged from the exit slot was then rinsed, dryed and gummed using the same techniques as described in the hand development operation. A total of forty S-85 plates, each having an area of five square feet, were processed without changing the developer or filter bag before the quantity of developer fed into the machine (12 kilograms) was no longer able to completely develop these plates.
8~
Another 12 kilograms of this developer was added to a 440 Processor and was used for successfully developing an Eastman Kodak LN-L photopolymer lithographic plate which does not contain a diazo layer but which does contain a photopolymer that was found to be swellable by the developing solution.
EXAMPI.E V
Another Eastman Kodak LN-L photopolymer lithographic plate was successfully developed by hand with a solution that contained two cosolvents, the formulation being 23 weight percent 2-ethoxyethyl acetate, 8 weight percent 2-ethoxyethanol, 5 weight percent ethylene glycol, 0.3 weight percent of the surfactant of Example IV, and the balance water.
EXAMPLE VI
Several one-step developers and finishers were prepared that each contained, on a lO0 percent by weight basis, 25 percent 2-ethoxyethyl acetate, 14 percent 2-ethoxyethanol, and 0.1 percent of the surfactant used in Example IV. Single-phase, non-emulsion aqueous solution subtractive developers were pre-pared by dissolving these three compositions with the preferred hydrolyzed polyacrylamide desensitizer, lactic acid, and water at the various weight percentage formulations A through G, as indicated in the following Table l:
g A B _ C D E F G_ Desensitizer 0.5 1.9 0.75 1.0 1.0 1.5 2.0 (weight %) Lactic Acid 0 0 0.25 0.500.75 1.0 1.5 (weight %) Water 60.4 59.0 59.959.4 59.15 58.~ 57.4 (weight %) The 3-R cinnamate photopolymer lithographic plates were treated with these formulatior.s both by hand and in a 440 Processor. Three different developing procedures were used after the initial development steps were completed either by hand or when they exited from the machine. A two-step development was accomplished in substantially the same manner as specified in Example IV for plates after the firs~ steps of hand development and for machine developed plates. Also, a one-step development was practiced with substantially the same procedures of the two-step except that the latter steps of subsequent water rinsing and gumming were omitted; instead, the excess developer was merely wiped off. In another alternative procedure, the rinsing and gumming steps were again omitted, and the plate was merely wiped to remove excess developer and polymer, ater which the developer formulation was reapplied with a clean pad andbuffed dry with absorbent tissue, by which procedure the formulation was used as both a developer and a finisher.
Generally, each formulation resulted in acceptable plate development, as evaluated in humid-oven aging studies by which the developed plates were cut into sections, one set of the sections being tested by running a short press test, another ~lS~
set or more`plates being stored for several days in a humid oven at 120 F. and 70 percent relative humidity and then press tested.
Each of the formulations A through G desensitized satisfactorily.
Formulations B and G tended to be somewhat more viscous than would be desireable for a developer. Formulations A and B did not sensitize quite as satisfactorily as did the other formulations, apparently due to the absence of lactic acid, resulting in the desent tizer remaining somewhat alkaline. Composition C, having a low lactic acid content~had desensitizing properties that were not quite as satisfactory as formulations D, E and F.
EXAMPLE VII
A developer solution of 40 weight percent 2-methoxyethyl acetate and 60 weight percent water satisfactorily developed on S-85 plate at a moderately fast rate, while a similar solution of 30 weight percent 2-methoxyethyl acetate and 70 weight perce.nt water satis~actorily developed another S-85 plate at a slow rate.
EXAMPLE VIII
When 30 weight percent 2-(2-ethoxyethoxy)ethyl acetate was dissolved i.nto 70 weight percent water, satisfactory but slow development o~ an S-85 plate was observed. Increasing the active solvent concentration to 40 weight percent resulted in moderately fast and satisfactory development.
EXAMPLE IX
Dissolving 2-ethoxyethyl acetate at 20 weight percent concentrations with various cosolvents, at differing concentrations, balance water~provided developers that were tested for development speed on S-85 plates~ Using 2-(2-ethoxyethoxy)ethanol as the cosolvent component at 4 weight percent resulted in fast development, 5 ~eight percent diacetone alcohol gave very fast development; 3 weight percent 2-(2-ethoxy-ethoxy)ethanol gave very fast development; 5 weight percent 2(2-methoxyethoxy)-ethanol gave very fast developrnent; and 11 weight percent 2-butoxyethanol resulted in very slow plate development.
EXAMPLE X
A developer formulation of 25 weight percent 2-ethoxyethyl acetate, 10 weight percent diacetone alcohol and 65 weight percent water developed on S-85 plate with satisfactory speed and resulted in good image quality.
EX~PLE XI
Following exposure of Enco's N200 (Trade Mark) and of 3M's XN (Trade Mark) photopolymer plates to a pu]sed xenon light source for 60 seconds, and 50 seconds respectively, the plate was satisfactorily hand developed with a developer of 26 weight percent 2-ethoxyethyl acetate, 14 weight percent 2-ethoxyethanol, 0.1 weight percent of the surfactant of Example IV, 1.0 weight percent of the desensiti~er oI Example VI, 0.75 weight percent lactic acid, 0.004 weight percent of a hydrophobic defoamer, balance water at about 58.15 weight percent, the image quality being good. The hydrophobic defoamer was a block copolymer of propylene oxide and ethylene oxide of the type discussed herein, having 10 weight percent poly-oxyethylene units and a molecular weight of about 4000 for the polyoxypropylene hydrophobe.
25 ~
EXAMPLE XII
Machine processor replenisher solutions were tested within an automatic plate processor having a 5 gallon developer capacity. The automatic processor was filled initially with a developer solution including 26 weight percent 2-ethoxyethyl acetate, 14 weight percent 2-ethoxyethanol, and 0.004 weight percent of the defoamer in Example XI. Rather than periodically removing the used developer and replacing it with a fresh 5-gallon batch, the initial developer fill was replenished periodically by adding enough of a developer solution replenisher formulation to bring the total developer solution up to full volume capacity of the machine. The particular replenisher formulation used included 28 weight percent 2-ethoxyethyl acetate, 11.5 weight percent 2-ethoxyethanol, and 0.1 weight percent of the surfactant used in Example IV.
Table 2 reports the number of plates and the cumulative plate square footage run through the machine processor before replenisher was added, the volume of replenisher solution added each time, and a partial analysis of the overall developer solution formulation within the machine processor after each replenisher addition. Analyses shown in Table 2 are for 2 ethoxyethyl acetate (~ EEAc) and for 2-ethoxyethanol (~ EE), which illustrate that the solvent concentrations were successfully maintained at very constant levels throughout the test period.
NO. OF CUMULATIVE REPLENISHER SOLVENT ANALYSIS
PLATES SQ. FT. ADDITION (ml.) % EEAc % EE
0 0 0 26.0 14.00 110 0 24.8 13.8 128 1164 24.8 13.8 117 604 1027 25.0 14.0 117 604 327 ~
227 1251 0 24.8 14.3 239 1298 1244 25.2 14.2 The preceding examples are offered to illustrate the aqueous developers of the present invention and their method o~ formulation and use, and they are not intended to limit the general scope of this invention in st:rict accordance therewith, but the invention is to be construed and limited only by the scope of the appended claims.
ethylene glycol diacetate; diethylene glycol diethyl ether;
dibutylene glycol diethyl ether; di.ethylene ~lycol dimethyl ether;
and triethylene glycol dimethyl ether. Examples of keto-ethers include 4-methoxy-4-methyl-pentanone-2; and examples of cyclic ketones include cyclohexanone and isophorone. Highly polar nitro~en-containin~ solvents include dimethylformamide; nitrobenzene;
l-nitro~ropane; 2-nitropropane; succinonitrile (butanedinitrile);
benzonitrile ~phenyl cYanide); and acetonitrile. Chlorinated hydrocarbon active solvents may include trichloroethylene and chlorobenzene. Examples of miscellaneous solvents include e-thyl lactate (ethyl ~-hydroxy propionate) and 2-methyl-2-ethyl-1,3 dioxolane.
Most preferred as the active solvent is 2-ethoxyethyl acetate because it is particularly inexpensive~ has low volatility and toxicity, and has only a mild odor. It also has especially acceptable partial water solubility properties, having a solubility in water of about 23.8 weight percent, meaning that, while it does exhibit limited water solubility, it is partially water insoluble and clearly not miscible with water. In general, the active or primary solvent can be present within the developer or machine developer solution replenisher at a concentration below its water solubili.ty limit, usually at a percentage no more than 10 weight percentage points less than or more than its water solubility limit, preferably no more than 7 weight per-centage points less than or greater than its water solubilitylimit, and most preferab].y no more than 3 weight percentage points less than and no more than 7 weight percentage points greater than its water solubility limit. The active solvent usually will make up between about 10 to about 40 weight percent of the developer or replenisher, preEerably between about 12 and 35 weight percent, and most preferably between about 15 to about 30 weight percent of the developer, based on total developer ; weight. It is to be appreciated that, since the concentration of the active solvent is generally keyed to its water solubility limit, these concentration ranges can vary depending upon the particular active solvent chosen.
When, as is preferred, a cosolvent is included in the single-phase, non-emulsion aqueous solution developer as an extender or diluent of the active solvent, such cosolvent must be compatible with -the chosen active solvent primarily for the purpose of avoiding a phase separation of the active solvent from the water within the formulation whereby effective levels of active solvent may be included within the single-phase aqueous _~ _ solution. The active solvent, the cosolvent and the water of these developers will, once they reach equilibrium, form a clear single phase that exhibits no light scattering.
Through the use of a cosolvent, the active solvent will be able to be included at a concentration that is even above if not actually substantially equal to its water solubility limit without experiencing undesirable phase separation when the developer is stored for lengthy periods of time. These co-solvents will be more miscible with water than will the active solvent with which each cosolvent is combined in any one formu-lation.
Typical cosolvents will be alcohols, glycols, glycol ethers, ketones, acetates and the like. Representative co-solvents include diacetone alcohol (~-hydroxy-~-methyl-pentanone-2); 2-(2-ethoxyethoxy) ethanol; 2-(2-methoxyethoxy) ethanol;
2-ethoxyethanol; 2-methoxyethanol; 2-butoxyethanol; glycerol;
ethylene glycol; propylene glycol; diethylene glycoli tri-ethylene glycol; tetraethylene glycol; a polyethylene glycol;
methyl alcohol; ethyl alcohol; n-propyl alcohol; isopropyl alcohol; acetone; methyl ethyl ketone; acetyl acetone; and ethyl acetate.
Examples of preferred solvents include diacetone alcohol and 2-ethoxyethanol, since each may be used in relatively low concentrations while still rendering the single-phase solution developer clear and homogeneous. Also to be considered in selecting one of these various cosolvents are the relative costs thereof. Cosolvents of high volatility and toxicity are less desirable. Concentration levels for the cosolvent within the ~:5~
total single-phase, non-emulsion aqueous solution developer can range between zero and about 30 weight percent, preferably between about 2 and about 25 weight percent, and most preferably within a range of between about 5 to about 15 weight percent.
These concentration ranges will be variable depending upon the particular combination of active solvent and cosolvent, and is especially dependent upon the limit of water solubility for the active solvent being cosolubilized or extended.
Especially advantageous results obtain when the single-phase aqueous developer solution further includes a surfactant,which will all but eliminate any possible redeposition problems.
Surfactants that are especially hydrophilic will be particularly useful in avoiding image area solubilization and excessive softening of the removed photopolymer. Surfactants will function to assist in making the developer formulation a clear one, to aid in wetting the photopolymer surface as the developer solution is applied, and to operate as a wetting agent for the removed polymer in order to prevent redeposition. The surfactant is also believed to help control the amount of total solvent absorption by the photopolymer which can lead to an overly soft condition resulting in redeposition on image areas. Concerning its wetting function, the surfactant will cause the homogeneous developer solution to surround photopolymer globules as they are removed, rather than surrounding them with active solvent which could make them generally tacky and inclined to adhere to image areas.
Excessive surfactant concentrations render the developer solution too foamy, may result in some image loss, and/or may ~s~
reduce developer activity. Surfactant concentrations, based on the total weight of the developer solution, can range from zero to about 5 weight percent, preferably from about 0.01 to about 2 weight percent and most preferably between about 0.05 and about 1.0 weight percent.
Surfactants useful in this ~ormulation should be hydro-philic. They may be either nonionic, cationic, anionic, or amphoteric, the nonionic surfactants being generally preferred.
Any one of a number of known surfactants can be incorporated such as those including ethylene oxide groups as their hydro-philic constituent. Representative of this type are an ethoxylated long chain tridecyl alcohol composition of medium viscosity (about 116 cps) having a molecular weight o~ 770; and certain block copolymers of propylene oxide and ethylene oxide terminated at both ends with polyethylene oxide groups haviny a ~-hydro-omega-hydroxy-poly(oxyethylene)poly(oxypropylene)poly(oxyethylene) block copylymer structure as described in U.S. Patent No. 2,674,619.
Acceptable examples of this latter group of block copolymers are those having 40~ polyoxyethylene hydrophilic units in the total molecule, the poly(oxypropylene) hydrophobe having a typical molecular weight of about 1750 and those having 50~ polyoxyethylene units in the molecule, the hydrophobe having a typical molecular weight of about 3250, the latter polymer being especially preferred because it can be used at a very low level while still being effective in bringing about the results desired by the surfactant when it is included within the aqueous solution developers.
In proceeding with another aspect of this invention, the single-phase, non-emulsion aqueous solution developer may be modified into a one-step developer, which modification also makes it suitable for use as a finisher as well as a developer.
The modification is accomplished by including a desensitizer within the total single-phase formulation, typically a desensitizer which is a hydrophilic synthetic resin.
An acceptable desensitizer will render more hydrophilic the non-image areas of lithographic plates after the photopolymer has been removed therefrom so that these areas will be ink-repellent during printing. They will assist in avoiding scummingor toning of these non-image areas during printing, which can often occur even after lithographic plates have been developed and gummed. Also, the inclusion of a desensitizer in accordance with this aspect of the invention will result in the improved development of plates that have been stored for several months prior to exposure and development.
In addition to being hydrophilic, the desensitizer should be soluble in and compatible with the rest of the aqueous system of the developer. Usually, the desensitizer will be a synthetic resin that is hydrolyzed or alcoholized to a significant and sub-stantial level. Resins that have been hydrolyzed to particularly high levels axe most suitable. Hydrophilic synthetic resin desensitizers include styrene-maleic anhydride copolymers which have been hydrolyzed or alcoholized, vinyl ether-maleic anhydride copolymers which have been hydrolyzed, and modified polyacrylamides having a molecular weight of about 200,000 and a minority carboxyl content.
Preferred is a hydrophilic synthetic resin that is a poly~
acrylamide having a molecular weight of approximately 200,000 in which approximately 70 percent of the acrylamide groups thereof have been hydrolyzed to acrylic acid groups and that can be thought of as a 70/30 copolymer of sodium acrylate and acrylamide which is predominately in salt form and therefore alkaline.
Amounts of this desensitizer typically incorporated within these developer formulations can be as high as about 5 percent by weight based upon the total weight of the developer :Eormulation, this upper limit being variable depending upon the specific desensitizer and being determined generally by the viscosity increases brought about by the inclusion of these ~` resins into the solution. The extent of solubility within the aqueous formulation is also a limiting factor on the amount of desensitizer that can be included. A typical preferred range will be between about 0.5 and about ~ weight percent. An : especially preferred range for the preferred polyacrylamide resin is between about 0.5 and about 1.5 weight percent.
Since a desensitizer will generally be predominately in salt form be~ore inclusion within the formulation in ac-cordance with this invention, best desensitization properties will be achieved by rendering the developer somewhat acidic, which will increase the solubility of the desensitizer within the single-phase, non-emulsion aqueous solution developer. It is accordingly preferred to include an acidity agent in the formulations which include desensitizers that are provided in `:~
alkaline form. Typical acidity agents will be weak mineral acids and acidic salts thereof, as well as organic acids and acidic salts thereof, added in concentrations that will generally lower the pH of the developer or finisher to between about 4.5 and 5.5. Examples include lactic acid, phosphoric acid, ammonium dihydrogen phosphate, citric acid and its acidic salts, acetic acid, tartaric acid, and the like, the preferred agent being lactic acid. Such an acidity agent can be included in amounts from zero to about 5 weight percent based upon the total weight of the developer solution, preferably between about 0.5 to about 2 weight percent.
Miscellaneous materials may further be included within the sinc~le-phase, non-emulsion aqueous solution developers in accordance with this invention. These include defoamers, anti-foamers, synthetic resin viscosity increasing agents such as hydroxypropyl cellulose, colorants, corrosion inhibitors, chelating agents, humectants, antioxidants, and buffers. If needed to insure ready acceptance of ink by the image areas of the developed photopolymer plate, hydrophobic defoaming materials compatible with the aqueous solution could be added up to about 0.1 weight percent of the composition, such as Carboset (Trade Mark) resins or ~-nydro-omega-hydroxy-poly(oxyethylene)poly(oxypropylene)-poly(oxyethylene)block copolymer hydrophobic surfactants having only about 10%
polyoxyethylene groups in the total molecule and polyoxypropylene hydrophobes of molecular weights from about 900 to about 1800.
. .~
..
Developers made in accordance with this invention will be of the subtractive type, meaning that they take away non-exposed or non-crosslinked photopolymers, which makes them particularly suitable for use in conjunction with subtractive developable negative-working plates. The invention is capable of developing negative working plates which are normally developed by an additive type of developer.
As a general proposition, developers in accordance with this invention will develop lithographic plates that are sus-ceptible to a typical photo-insolubilization process. They are particularly well suited for developing photopolymer litho-graphic plates known as 3-R plates, S-85 plates, and S-56 plates (Richardson Graphics), which are brush grained, anodized and subbased aluminum plates coated with a thin layer (2-lO
mg./sq. ft.) o~ diazo material which is then overcoated with a moderate layer (20-120 mg./sq. ft.) of cinnamate photopolymer, such as generally described in U.S. Patent No. 3,808,004.
Numerous other plates can be adequately developed according to this invention; the principle requirement is that they include a polymer that is swellable by the active solvent. When used as a hand developer, this invention will be suitable for developing almost any presently known photopolymer lithographic plate.
When machine development is to be practiced, the developer is particularly suitable for plates having cinnamate photopolymer layers.
In proceeding with the method in accordance with this invention, the active solvent is dissolved in water to near its water solubility limit, preferably with the assistance of the cosolvent extender or diluent in the proportions specified herein. Small amounts of surfactant may also be included to improve the general wetability of the developer formulation pre-pared. Other optional ingredients may be put into solution, such as defoamers, antifoamers, viscosity increasing agents, colorants, corrosion inhibiters, chelating agents, humectants, antioxidents, buffers, and hydrophobic materials. By another aspect of this method, the hydrophilic synthetic resin de-sensitizers are added, with stirring, up to about 5 weight percentin order to provide a formulation that is both a one-step developer and a formulation suitable for finishing as well as developing.
When the desensitizer put into solution is alkaline, best de-sensitization properties are usually realized by dissolving an acidity agent into the formulation.
After these solution forming steps are completed, the resulting formulation is a single-phase, non-emulsion aqueous subtractive developer for lithographic plates having a swellable photopolymer layer. During development, the method is believed to proceed by the following steps.
When the developer is applied to an exposed lithographic plate, either by hand with a developer-saturated developing pad or by machine with the brushes or the like of automatic plate processors which recirculate developer after filtering out re-moved polymer particles, the developer will be allowed to presoak into the plate for a total period of time between about 10 seconds to about 60 seconds, depending upon the temperature, the size of the lithographic plate, and/or the capabilities of the pro-cessing machine. During this presoaking period, the active i3'9 solvent, which may be accompanied by some of the cosolvent, is ab-sorbed out of the homogeneous single-phase developing solution and into the photopolymer due to its affinity for the swellable photopolymer layer being greater than its tendency to remain in solution at or near its water solubility limit. This absorbing step results in a swelling of the photopolymer which is followed by mechanically re-moving the swollen polymer, either by hand rubbing or automatically within a processing machine. When the plate being developed includes a diazo resin layer or other water soluble layer, the water within the formulation will solubilize this underlying, unhardened layer for removing it from the plate in the non-image areas.
During these developing steps, each of the other components dissolved within the formulation function in accordance with their intended purpose when included within the formulation. Generally, if the developer formulation contains too much active solvent or too little cosolvent when included, the developer formulation will be too active and will tend to a-ttack the image areas of the plate. sut if the ~ormulation contains too little active solvent and/or too much cosolvent, the unexposed photopolymer will not be completely removed from the non-image areas of the photo-lithographic plate.
For formulations that do not include the hydrophilicdesensitizer, the developed plate will then typically be subjected to secondary development steps common to a two-step process, including rinsing the plate thoroughly with tap water to remove polymer globules and remaining developer from the plate surface, usually in conjunction with gently rubbing the plate with a wet sponge or the like, after which the plate may then be s~eegeed or buffed dry with absorbent material such as paper tissue, followed by gumming with any conventional litho gum or gum asphaltum etch. When a desensitizer is included, the same secondary development steps can be proceeded with, or they can be omitted in order to accomplish a one-step developing procedure by merely wiping off the excess developer and by omitting the subsequent water rinsing and gumming steps.
Alternatively, the developing formulation can be used also as a finisher, in which case the water rinsing and gumming can also be omitted, although the water rinsing step can be pro-ceeded with if desired; thereafter, the developing formulation is applied as a finisher with a plain pad, absorbent tissue, or the like, followed by bufEing the plate dry with absorbent tissue.
The following speciEic examples will more precisely illustrate the invention and teach the procedures presently preferred for practicing the same, as well as the improvements and advantages realized thereby.
EXAMPLE I
Various formulations were made including from 20 through 50 weight percent of 4-methoxy-4-methyl-pentanone-2 as the active solvent, together with from 10 through 20 weight percent of diacetone alcohol as the cosolvent, the balance being water.
These compositions were found to be ~seful and tested well in their ability to develop S-85 photopolymerizable lithographic plates at moderately fast speeds. The developer was a sing]e-phase,non-emulsion aqueous solution subractive developer.
EXAMPLE I I
A moderately fast single-phase, non-emulsion aqueous solution subtractive developer was formulated by mixing 25 weight percent of 4-methoxy-4-methyl-pentanone-2 with 75 weight percent water. This developer was tested on and found to develop an S-85 plate to a clean background and satisfactory image. Concentrations less than 25 weight percent also exhibited developing properties.
EXAMPLE I I I
At 15 weight percent 2-ethoxyethyl acetate formed a single-phase solution in water which made up the remaining 85 weightpercent thereof. Although the rate was slow, plate development was satisfactory; when tested upon a S-85 plate, it gave a clean background and a satisfactory image.
EXAMPLE IV
On a 100 parts by weight basis, 23 weight percent 2-ethoxyethyl acetate, 10 weight percent 2~ethoxyethanol, and 0.1 weight percent propylene oxide and ethylene oxide block copolymer surfactant having polyethylene oxide groups at both ends, having about 50~ polyoxyethylene units in the total molecule, and having the polyoxypropylene hydrophobic units at a molecular weight of about 3250, were dissolved within 66.9 weight percent water to form a single-phase, non-emulsion aqueous solution subtractive developer which was suitable for either hand development or machine development or a cinnamate overcoated subtractive lithographic plate.
In proceeding with the hand development, an exposed subtractive plate was placed on a developing table, and a short nap pad held flat in a pad clamp was saturated with this developer, followed by application to the entire plate without exerting any substantial pressure on the plate until the entire plate was covered with developer. The developer was allowed to soak into the plate surface for about lO seconds, after which a re-saturated developing pad was rubbed over the plate with moderate pressure to remove the coatings in the unexposed areas of the plate by using long, straight strokes along the length and the width of the plate. Development was continued until all the polymer was removed from the non-image areas, the smaller plates taking a total of about 45 seconds to develop and larger plates about 90 to 120 seconds at 70 F.
The thus developed plate was then rinsed thoroughly with tap water to remove the remaining developer and polymer globules from the surface, the rinsing being accompanied by gentle rubbing with a wet sponge. This was ~ollowed by drying the plate with absorbent paper tissue, and then by gumming with a conventional lithographic gum asphaltum etch to make it ready for storage or use on a lithographic printing press.
Another amount of this developer was tested within a 440 Processor automatic developing machine of the rotary brush drum type by feeding the exposed plate into the entrance slot while the feed foot switch was activated. The plate which emerged from the exit slot was then rinsed, dryed and gummed using the same techniques as described in the hand development operation. A total of forty S-85 plates, each having an area of five square feet, were processed without changing the developer or filter bag before the quantity of developer fed into the machine (12 kilograms) was no longer able to completely develop these plates.
8~
Another 12 kilograms of this developer was added to a 440 Processor and was used for successfully developing an Eastman Kodak LN-L photopolymer lithographic plate which does not contain a diazo layer but which does contain a photopolymer that was found to be swellable by the developing solution.
EXAMPI.E V
Another Eastman Kodak LN-L photopolymer lithographic plate was successfully developed by hand with a solution that contained two cosolvents, the formulation being 23 weight percent 2-ethoxyethyl acetate, 8 weight percent 2-ethoxyethanol, 5 weight percent ethylene glycol, 0.3 weight percent of the surfactant of Example IV, and the balance water.
EXAMPLE VI
Several one-step developers and finishers were prepared that each contained, on a lO0 percent by weight basis, 25 percent 2-ethoxyethyl acetate, 14 percent 2-ethoxyethanol, and 0.1 percent of the surfactant used in Example IV. Single-phase, non-emulsion aqueous solution subtractive developers were pre-pared by dissolving these three compositions with the preferred hydrolyzed polyacrylamide desensitizer, lactic acid, and water at the various weight percentage formulations A through G, as indicated in the following Table l:
g A B _ C D E F G_ Desensitizer 0.5 1.9 0.75 1.0 1.0 1.5 2.0 (weight %) Lactic Acid 0 0 0.25 0.500.75 1.0 1.5 (weight %) Water 60.4 59.0 59.959.4 59.15 58.~ 57.4 (weight %) The 3-R cinnamate photopolymer lithographic plates were treated with these formulatior.s both by hand and in a 440 Processor. Three different developing procedures were used after the initial development steps were completed either by hand or when they exited from the machine. A two-step development was accomplished in substantially the same manner as specified in Example IV for plates after the firs~ steps of hand development and for machine developed plates. Also, a one-step development was practiced with substantially the same procedures of the two-step except that the latter steps of subsequent water rinsing and gumming were omitted; instead, the excess developer was merely wiped off. In another alternative procedure, the rinsing and gumming steps were again omitted, and the plate was merely wiped to remove excess developer and polymer, ater which the developer formulation was reapplied with a clean pad andbuffed dry with absorbent tissue, by which procedure the formulation was used as both a developer and a finisher.
Generally, each formulation resulted in acceptable plate development, as evaluated in humid-oven aging studies by which the developed plates were cut into sections, one set of the sections being tested by running a short press test, another ~lS~
set or more`plates being stored for several days in a humid oven at 120 F. and 70 percent relative humidity and then press tested.
Each of the formulations A through G desensitized satisfactorily.
Formulations B and G tended to be somewhat more viscous than would be desireable for a developer. Formulations A and B did not sensitize quite as satisfactorily as did the other formulations, apparently due to the absence of lactic acid, resulting in the desent tizer remaining somewhat alkaline. Composition C, having a low lactic acid content~had desensitizing properties that were not quite as satisfactory as formulations D, E and F.
EXAMPLE VII
A developer solution of 40 weight percent 2-methoxyethyl acetate and 60 weight percent water satisfactorily developed on S-85 plate at a moderately fast rate, while a similar solution of 30 weight percent 2-methoxyethyl acetate and 70 weight perce.nt water satis~actorily developed another S-85 plate at a slow rate.
EXAMPLE VIII
When 30 weight percent 2-(2-ethoxyethoxy)ethyl acetate was dissolved i.nto 70 weight percent water, satisfactory but slow development o~ an S-85 plate was observed. Increasing the active solvent concentration to 40 weight percent resulted in moderately fast and satisfactory development.
EXAMPLE IX
Dissolving 2-ethoxyethyl acetate at 20 weight percent concentrations with various cosolvents, at differing concentrations, balance water~provided developers that were tested for development speed on S-85 plates~ Using 2-(2-ethoxyethoxy)ethanol as the cosolvent component at 4 weight percent resulted in fast development, 5 ~eight percent diacetone alcohol gave very fast development; 3 weight percent 2-(2-ethoxy-ethoxy)ethanol gave very fast development; 5 weight percent 2(2-methoxyethoxy)-ethanol gave very fast developrnent; and 11 weight percent 2-butoxyethanol resulted in very slow plate development.
EXAMPLE X
A developer formulation of 25 weight percent 2-ethoxyethyl acetate, 10 weight percent diacetone alcohol and 65 weight percent water developed on S-85 plate with satisfactory speed and resulted in good image quality.
EX~PLE XI
Following exposure of Enco's N200 (Trade Mark) and of 3M's XN (Trade Mark) photopolymer plates to a pu]sed xenon light source for 60 seconds, and 50 seconds respectively, the plate was satisfactorily hand developed with a developer of 26 weight percent 2-ethoxyethyl acetate, 14 weight percent 2-ethoxyethanol, 0.1 weight percent of the surfactant of Example IV, 1.0 weight percent of the desensiti~er oI Example VI, 0.75 weight percent lactic acid, 0.004 weight percent of a hydrophobic defoamer, balance water at about 58.15 weight percent, the image quality being good. The hydrophobic defoamer was a block copolymer of propylene oxide and ethylene oxide of the type discussed herein, having 10 weight percent poly-oxyethylene units and a molecular weight of about 4000 for the polyoxypropylene hydrophobe.
25 ~
EXAMPLE XII
Machine processor replenisher solutions were tested within an automatic plate processor having a 5 gallon developer capacity. The automatic processor was filled initially with a developer solution including 26 weight percent 2-ethoxyethyl acetate, 14 weight percent 2-ethoxyethanol, and 0.004 weight percent of the defoamer in Example XI. Rather than periodically removing the used developer and replacing it with a fresh 5-gallon batch, the initial developer fill was replenished periodically by adding enough of a developer solution replenisher formulation to bring the total developer solution up to full volume capacity of the machine. The particular replenisher formulation used included 28 weight percent 2-ethoxyethyl acetate, 11.5 weight percent 2-ethoxyethanol, and 0.1 weight percent of the surfactant used in Example IV.
Table 2 reports the number of plates and the cumulative plate square footage run through the machine processor before replenisher was added, the volume of replenisher solution added each time, and a partial analysis of the overall developer solution formulation within the machine processor after each replenisher addition. Analyses shown in Table 2 are for 2 ethoxyethyl acetate (~ EEAc) and for 2-ethoxyethanol (~ EE), which illustrate that the solvent concentrations were successfully maintained at very constant levels throughout the test period.
NO. OF CUMULATIVE REPLENISHER SOLVENT ANALYSIS
PLATES SQ. FT. ADDITION (ml.) % EEAc % EE
0 0 0 26.0 14.00 110 0 24.8 13.8 128 1164 24.8 13.8 117 604 1027 25.0 14.0 117 604 327 ~
227 1251 0 24.8 14.3 239 1298 1244 25.2 14.2 The preceding examples are offered to illustrate the aqueous developers of the present invention and their method o~ formulation and use, and they are not intended to limit the general scope of this invention in st:rict accordance therewith, but the invention is to be construed and limited only by the scope of the appended claims.
Claims (26)
1. A composition which is a developer or develop-er solution replenisher for photopolymeric lithographic plates, the developer composition being an aqueous system of the non-emulsion subtractive type consisting essentially of: a single-phase aqueous solution including an active solvent in admixture with a water miscible cosolvent, and water, said active solvent having a water solubility concentration at which it is partially water insoluble or only partially soluble within the total aqueous system developer composition, said active solvent also being a good solvent for unexposed photopolymer of a lithographic plate, which photopolymer is insolubilized upon exposure to actinic radiation, said active solvent being selected from the group consisting of glycol diacetates, glycol diethers, glycol ether acetates, keto ethers, ethyl lactate, and 2-methyl-2-ethyl-1,3 dioxolane, said cosolvent being selected from the group consisting of water-miscible alcohols, glycols, glycol ethers, ketones and acetate esters, said cosolvent being a diluent for said active solvent, said cosolvent being more water soluble than said active solvent, and said active solvent being dissolved within the total composition in admixture with said water and with said water-miscible cosolvent at an unexposed photopolymer swelling concentration at which said active solvent migrates out of the developer composition to swell the unexposed photopolymer of the exposed and imaged lithographic plate for subsequent removal thereof from the plate, said photopolymer swelling concentration of the active solvent being no more than about 10 weight percentage points less or greater than said water solubility concentration of the active solvent, based on the weight of the total aqueous system developer composition.
2. The composition of claim 1, wherein said con-centration of the active solvent is no more than 7 weight percentage points less or greater than said water solubility concentration of the active solvent, based on the weight of the total composition.
3. The composition of claim 1, wherein said con-centration of the active solvent is no more than 3 weight percentage points less than and no more than 7 weight percentage points greater than said water solubility concentration of the active solvent, based on the weight of the total composition.
4. The composition of claim 1, wherein said concentration of the active solvent is between about 10 weight percent to about 40 weight percent of the total composition and said water is present at a concentration of up to about 90 weight percent.
5. The composition of claim 1, wherein said active solvent is 2-ethoxyethyl acetate.
6. The composition of claim 1, wherein said cosolvent is within said composition at a concentration up to about 30 weight percent, based on the total weight of the composition.
7. The composition of claim 1, wherein said cosolvent is diacetone alcohol or 2-ethoxyethanol.
8. The composition of claim 1, further including a surfactant dissolved therein at a concentration up to about 5 weight percent, based on the total weight of the composition.
9. The composition of claim 1, further including a desensitizer dissolved therein at a concentration up to about 5 weight percent, based on the total weight of the composition, together with an acidity agent being present at a concentration up to about 5 weight percent to adjust the composition to a pH between about 4.5 and 5.5.
10. The composition of claim 1, further including a hydrolyzed or alcoholized hydrophilic synthetic resin desensitizer.
11. The composition of claim 1, further including a synthetic resin desensitizer being a polyacrylamide in which approximately 70 percent of acrylamide groups thereof have been hydrolyzed to acrylic acid groups.
12. The composition of claim 1, wherein said single phase aqueous solution includes between about 12 to about 35 weight percent of said active solvent, between about 2 and about 25 weight percent of said cosolvent, said single phase aqueous solution further including about 0.01 to about 2 weight percent of a surfactant, all based on the total weight of the composition.
13. The composition of claim 1, wherein said single phase aqueous solution includes between about 15 to about 30 weight percent of said active solvent, between about 5 and about 15 weight percent of said cosolvent, said single phase aqueous solution further including about 0.05 to about 1 weight percent of a surfactant, all based on the total weight of the composition.
14. The composition of claim 1, wherein said single phase aqueous solution includes between about 12 to about 35 weight percent of said active solvent, between about 2 and about 25 weight percent of said cosolvent, said single phase aqueous solution further including about 0.01 to about 2 weight percent of a surfactant, between about 0.5 to about 2 weight percent of a hydrophilic synthetic resin desensitizer, all based on the total weight of the composition.
15. The composition of claim 1, wherein said single phase aqueous solution includes between about 15 to about 30 weight percent of said active solvent, between about 5 and about 15 weight percent of said cosolvent, said single phase aqueous solution further including about 0.05 to about 1 weight percent of a surfactant, and between about 0.5 to about 1.5 weight percent of a hydrophilic synthetic resin desensitizer, all based on the total weight of the composition.
16. The composition of claim 1, further including up to about 0.1 weight percent, based on the total weight of the composition, of a hydrophobic defoamer.
17. The composition of claim 1, wherein said composition has a pH between about 4.5 and about 5.5.
18. The composition of claim 1, wherein said single-phase aqueous solution further includes an antifoamer, a viscosity increasing agent, a colorant, a corrosion inhibitor, a chelating agent, a humectant, a buffer, or combinations thereof.
19. A method of providing a composition which is a developer or a developer solution replenisher for developing imaged photopolymeric lithographic plates, the composition being an aqueous system of the non-emulsion subtractive type, the method comprising: forming a single-phase aqueous solution consisting essentially of water in admixture with a water miscible cosolvent, an active solvent having a water solubility concentration at which it is partially water insoluble or only partially soluble within the total aqueous system composition, said active solvent being a good solvent for unexposed photopolymer of a lithographic plate, which photopolymer is insolubilized upon exposure to actinic radiation, said active solvent being selected from the group consisting of glycol diacetates, glycol diethers, glycol ether acetates, keto ethers, ethyl lactate, and 2-methyl-2-ethyl-1,3 dioxolane, said cosolvent being selected from the group consisting of water-miscible alcohols, glycols, glycol ethers, ketones and acetate esters, said cosolvent being a diluent for said active solvent, said cosolvent being more water soluble than said active solvent, said single-phase aqueous solution forming step including admixing said water and said cosolvent with said active solvent at an unexposed photopolymer swelling concentration, said photo-polymer swelling concentration of the active solvent being no more than about 10 weight percentage points less or greater than said water solubility concentration of the active solvent, based on the weight of the total composition, applying the composition to an exposed and imaged photo-polymeric lithographic plate, permitting said active solvent to absorb out of said composition solution and to the unexposed photopolymer, swelling said unexposed photo-polymer with said absorbed active solvent, and removing the swollen photopolymer from the lithographic plate.
20. The method of claim 19, wherein said active solvent is admixed at an active solvent concentration between about 10 and about 40 weight percent of the total composition.
21. The method of claim 19, wherein said active solvent is admixed into said single-phase aqueous solution at up to about 30 weight percent of said cosolvent for said active solvent, together with up to about 5 weight percent of a surfactant, both as based on the total weight of the composition.
22. The method of claim 19, wherein said composition further includes up to about 5 weight percent of a hydrophilic synthetic resin desensitizer, together with up to about 5 weight percent of an acidity agent, both as based on the total weight of the composition.
23. The method of claim 19, further including adjusting the pH of the composition to between about 4.5 and 5.5.
24. The method of claim 19, further including solubilizing a diazo layer of the lithographic plate with said water of the composition, and removing the solubilized diazo layer from the lithographic plate.
25. The method of claim 19, wherein said composition is a developer solution replenisher, and said method further includes adding said composition to a partially expended developer solution within a developer processing machine.
26. The method of claim 19, wherein said composition further includes an antifoamer, a viscosity increasing agent, a colorant, a corrosion inhibitor, a chelating agent, a humectant, a buffer, or combinations thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90027678A | 1978-04-26 | 1978-04-26 | |
| US900,276 | 1978-04-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1150089A true CA1150089A (en) | 1983-07-19 |
Family
ID=25412270
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000324931A Expired CA1150089A (en) | 1978-04-26 | 1979-04-05 | Clear aqueous developers for lithographic plates including an active solvent and a water miscible cosolvent |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1150089A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10952430B2 (en) | 2019-02-06 | 2021-03-23 | Virox Technologies Inc. | Shelf-stable antimicrobial compositions |
-
1979
- 1979-04-05 CA CA000324931A patent/CA1150089A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10952430B2 (en) | 2019-02-06 | 2021-03-23 | Virox Technologies Inc. | Shelf-stable antimicrobial compositions |
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