Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/42—Aqueous compositions containing a dispersed water-immiscible liquid

Definitions

• This invention relates to etching metal. More particularly it relates to a new and novel bath composition and method concerning the powderless etching of curved magnesium base metal work pieces such as curved etchable photoengraving plates and the like.
• Patent 3,023,138 is illustrative of such a bath, employing particular filming agents, specifically usable for fiat plate etching and comprises: nitric acid with the optional inclusion therewith of small amounts of sulfuric acid, hydrochloric acid, acetic acid and the like; an organic water-immiscible solvent stable in the presene of dilute acids, and a substituted halogenated diaryloxide sulfonate wherein the substituents on halogenated diaryloxide sulfonates are hydrophobic groups containing up to 30 carbon atoms; the balance being essentially water including, for example, various by-products generated from the bath components.
• film controlling agents have been added to the above bath formulations in an attempt to improve their performance.
• One such group of film controlling agents comprises, for example, a single organic dicarboxylic acid or a blend of such compounds which individually consist of only hydrogen, carbon, and oxygen and have from 4 to 10 carbon atoms with up to 3 carbon to carbon double bonds, the latter referring to aromatic unsaturation as well as that which may occur in aliphatic chains.
• Such additaments may be aromatic, cycloaliphatic or aliphatic in character or a combination thereof such as alkylaromatics.
• etching baths By their use in the above described etching baths, it is possible to increase the depths of etch obtainable in small areas of penetration in combination of photoengraving plates, such as halftone areas where proper or adequate depths of etch are usually difiicult to obtain by bath modulation without, at the same time, adversely weakening the protection achieved in open line areas of the same plate.
• the film-controlling agents have a beneficial stabilizing effect on the protective film in open line areas of the plate thereby minimizing lateral etching and chipped or rough image sidewalls.
• An object of the present invention is to provide a new and novel etching bath composition and method specifically for powderless etching of magnesium and magnesium base alloy curved segments, which significantly minimizes the disadvantages herein before mentioned with respect to etching such work pieces.
• Another object of the invention is to provide a novel bath solution primarily for etching curved magnesium and magnesium base alloy photoengraving plates of large diameter which substantially avoids chipping, tailing of the image shoulder and dirty, pimply plates, and which improves the uniformity, quality and cleanliness of the plate and relief images in general.
• Still another object is to provide a novel method of powderless etching curved work pieces.
• This three component organic solvent system comprises three groups of organic liquids, each group being identified by a certain range of Kauri Butanol values (termed herein as KB values).
• the first group is called the low KB solvent having a KB range of from about 25 to about 75
• the second group being called the intermediate KB solvent having a KB range of fro-m about to about 100
• the third group called the high KB solvent having a KB value in excess of 100.
• KB value refers to a known and used standard test for determining the solvent power value of a given organic liquid as the amount of a solvent which can be added to a standard kauri gum solution in butanol to produce a definite turbidity, as compared with the amount of pure benzene used as a standard in a similar titration and arbitrarily taken as percent standard.
• required properties of the low KB solvent are that it have a KB value within the range of from about 25 to about 75, be substantially stable in the presence of dilute nitric acid at bath temperatures, have some solvency for the filming agent employed and that it be substantially water-immiscible. Substantially stable is defined as the non-occurrence of deterioration, within a reasonable time period, in contact with dilute nitric acid which deterioration significantly alters the function of the organic waterimmiscible component within the bath in an unfavorable manner. Also, it is essential that this additive be a liquid at bath temperatures.
• Suitable organic materials which can be used individually, or in combination with other such solvents within the total amount of such solvent as specified below, are aromatics, aliphatics, napht'henes, ethers, and esters having a KB value Within the range of from 25 to 75.
• Such low KB solvents include, for example, dodecylbenzenes, (an alkylbenzene, wherein the average of the alkyl chains contains 12 carbon atoms), mineral seal oils, other alkylbenzenes, napthenes with alkyl carbon atoms with the inclusive range of from about 8 to 10, and the like.
• water-immiscible esters, ketones, terpenes, ethers, aliphatic, naphthenic, and aromatic hydrocarbons which have a KB in the range of 25 to 75 are operable.
• the total amount of the low KB solvent employed may range from about 0.5 to about 2 volume percent of the bath and preferably from about 0.75 to about 1.25 volume percent. A particularly desirable amount to use has been found to be about 1.0 percent.
• the intermediate KB solvent constituent is present in the present novel bath formulation for the purpose and function, among other things, of aiding in the control of the transverse shoulder width, in general, and more specifically to avoid tightening and under-cutting of the shoulder in the transverse direction of the curve of the plate.
• This organic liquid is a solvent having with respect to the other organic solvents in the bath as intermediate KB value, for example, from 75 to 100.
• Examples of such organic liquids suitable for use in the present invention are: Solvesso 150 (a trade name for a mixture of approximately 90 percent alkylbenzenes, 2 percent napthalene and 8 percent napthenes); diethylbenzenes, such as, for example, Penola H.A.N.
• the amount of such organic liquid to be used individually or in mixture thereof will be within the range of from about 0.8 to about 2.8 percent by volume of the composite bath.
• the amount Will be within the range of from about 1.0 to about 1.8 volume percent, said Solvesso 150 being preferred as the organic liquid to be used.
• the high KB, low viscosity, solvents are characterized by their immiscibility with water and a relatively high KB value, preferably within the range, for example, of from about 100 to about 130, but also including those having a KB value in excess of 130, such as, for example, hexylacetate which has a KB value of about 203.
• they are substantially unreactive with the mineral acid component (dilute as used in the bath) and contain no terminal functional groups but rather a preponderance of carbon and hydrogen atoms.
• These solvents may be used separately or in mixture within the total amount of said high KB solvent to be used, as specified below and have the primary function in the present bath of aiding in clean liness of etch, i.e., avoidance of pimples on the etched plate without causing tailing on the image shoulders of half-tone dots, or bleed off as it is called herein since it concerns more particularly the shoulders of half-tone highlight dot type images.
• the total amount of this high KB solvent to be used in the bath ranges from about 0.25 to about 1.5 volume percent and preferably from about 0.4 to about 0.6 volume percent. A particularly suitable amount has been found to be about 0.5 volume percent.
• high KB solvents examples include hexyl acetate, dibutyl phthalate, trichloroethylene and the like.
• a very desirable high KB solvent preferred for use herein is a group of high boiling aromatic naphtha solvents known under the trade name of Panasol AN petroleum solvents, having high flash points (190230 F.), particularly those designated as AN-l made and identified as such by the Amoco Chemicals Corporation which are a group of relatively non-toxic, low volatile, aromatic napthas of wide boiling range, having a KB value of about 108 and containing typically 99 percent of said high boiling aromatics.
• the novel three component, water-immiscible, organic solvent is admixed with the dilute nitric acid, a filming agent and a film controlling agent, all as previously described, the balance being essentially water, to form an etching bath.
• This novel bath is then impinged upon the surface to be etched, such impingement being accomplished as by spraying, splashing, bubbling agitated immersion, or the like. Etching is continued until the desired depth, which may be, for example, from about 25 to about 40 thousandths of an inch in large, open, non-image areas, is achieved.
• the average bath temperature may be within a range from 40 to 120 F. but a preferred range is from to 90 F., and more preferably from to 85 F.
• etching bath In formulating the etching bath, it is a general rule that as the concentration of the nitric acid is increased within the aforementioned limits, it is usually desirable to also increase the proportion of filming agent employed. Also, as will be manifest to those skilled in the art, it may become desirable during the use of the bath to replenish the acid that has been used up and possibly to add other agents such as bath extenders for special purposes.
• the metals which may be etched by the process of this invention include primary magnesium, and magnesium base alloys, which are substantially homogeneous and suitable for photoengraving.
• a magnesium base alloy is defined as having percent of the base component.
• a preferred bath composition of the present invention for use particularly in an etching machine adapted to etching curved plates comprises from about 88 to about 107 grams per liter of nitric acid; from about 1.0 to about 1.8 volume percent of Solvesso .150 (defined hereinbefore) as the intermediate KB solvent; from about 3.2 to about 3.6 grams per liter of bath volume percent of a filming agent comprising a mixture primarily of the sodium salts of mono and disulfonated monochlorododecyl, mostly C12, diphenyloxide with a preponderance of monosulfonated oxide (termed herein as diphenyloxide mixture); from about 1.2 grams per liter of bath to about 1.8 grams per liter of bath of adipic acid as a film controlling agent; from about 0.75 to about 1.25 percent by volume of the low KB solvent dodecylbenzene; and from about 0.4 to about 0.6 percent by volume of Panasol AN-l as the high KB solvent
• a particularly desirable group of filming agents to use comprise a mixture of primarily the sodium salts of mono and disulfonated monochlorododecyl, mostly 1-2 carbons, diphenyloxide with a preponderance of monosulfonated oxide, both the pure compounds and mixtures thereby being termed herein as diphenyloxide filming agents.
• Operable amounts of the film controlling agents which may be 7 used include from about 0. 3 to about 2.5 grams per liter of bath of said agent.
• the film controlling agents may be, for example, single organic dicarboxylic acid or a blend of such compounds which individually consist of only hydrogen, carbon and oxygen and have 4 to 10 carbon atoms with up to 3 carbon to carbon double bonds, the latter referring to aromatic unsaturation as well as that which may occur in aliphatic chains.
• Such additaments may be aromatic, cycloaliphatic or aliphatic in character or a combination thereof such as alkylaromatic.
• Adipic acid is a preferred film controlling agent.
• Example I A powderles-s etching bath of 77 liters was prepared for use in etching curved photoengraving plates in a M-32 master etching machine by admixing; 9.93 grams per liter of HNO 0.335 grams per liter of bath of the aforesaid diphenyloxide mixture (both defined hereinbefore); 1.34 percent by volume of Solvesso 150; 1 percent by volume of dodecylbenzene; and 0.5 volume percent of Panasol AN-l, and 1.5 grams per liter .of adipic acid. The balance of the bath was made up with water. The bath temperature was then adjusted .to 80 F.
• a 11 inch diameter by 18 inch long curved segment 0.064 inch thick of an etchable magnesium base alloy phot-oengraving plate exhibiting a polyvinyl alcohol type etch resist coating as the image pattern and bare metal in the non-image areas (the areas to be etched) was then placed in position for etching in the machine by clamping it onto a mandrel.
• the machine was then operated whereupon, the paddles were turned and the prepared bath compositions splashed on the segment as it turned.
• the mandrel speed was about 40 rpm, and the direction of rotation was reversed each 20 seconds.
• Etching was continued for about minutes to a depth of about .030 inch.
• the depth of the etch in the high-light dot areas of the 65 line screen halt-tone areas was about 0.005 inch.
• Example [I] To illustrate the present invention on a comparative basis, an 8 inch diameter curved segment was etched in a powderless etching bath in the same machine and under the same conditions as used in Example I, except that a lower bath temperature of about 70-71 F. was employed, and the etching time was increased to give the same open area depth of about 0.030 of an inch.
• This standard bath contained 94 grams per liter of HNO 3.3 grams per liter of a diphenyloxide filming agent, 1.5 grams per liter of adipic acid, and 45 volume percent of Solvesso 150.
• Combinations of bath additives with the present invention other than those hereinbefore specified may also be used to constitute other novel bath composition formulations within the present invention with the same good results in etching curved plates, with respect to significantly reducing tailing and bleed-01f aflects. Examples of such other combination include:
• Example II The same composition as in Example I except that /2 percent of Solvesso 150 was used and also a mixture of A percent diisodecylphthalate and 1 percent Panasol AN-l as the high KB solvent.
• an etching bath composition comprising substantially nitric acid, a sulfonated dodecyl diphenyl oxide filming agent, a film controlling agent and an organic water-immiscible fluid substantially stable in the presence of dilute nitric acid, the balance being essentially water; the improvement consisting essentially of employing a three-component organic solvent system as the waterimmisci-ble fluid, said system comprising as a first component from about 0.5 to about 2.0 volume percent of the bath of at least one organic liquid having a kauributanol value within the range of from about 25 to about 75, as a second component from about 0.8 to about 2.8 volume percent of the bath of an organic liquid having a kauri-butanol value within the range of from about 75 to about 100, and as a third component from about 0.25 to about 1.5 volume percent of the bath of an organic liquid having a kauri-butanol value in excess of 100.
• the second component organic liquid is a mixture of approximately percent alkylbenzenes with about 2 percent of naphthalene and 8 percent naphthenes.
• An aqueous bath composition for etching etchable curved photoengraving plates consisting essentially of from about 88 to about 107 grams per liter of nitric acid; from about 3.0 to about 3.6 grams per liter of bath of a sodium salts of mono and disulfonated monochlorododecyl diphenyl oxide filming agent; from about 0.75 to about 1.25 volume percent of the bath of dodecyl benzene; from about 1.0 to about 1.8 volume percent of the bath of a mixture of approximately 90 percent alkyl benzenes, 2 percent naphthalene and 8 percent naphthenes; from about 0.4 to about 0.6 volume percent of the bath of a high boiling aromatic naphtha solvent having a kauri-butanol value of about 108; from about 1.2 to about 1.8 grams per liter of bath of adipic acid as a film controlling agent; the balance being essentially water.
• a method of etching etchable curved photoengraving plates of magnesium base metal having an acid resistant image on the surfaces thereof to be etched comprising; (a) establishing an aqueous powderless etching bath composition comprising from about 88 to about 107 grams per liter of nitric acid, from about 2.5 to about 4.0 grams per liter of bath of a sodium salts of mono and disulfonated monochlorododecyl diphenyl oxide filming agent; from about 0.5 to about 2 volume percent of the bath of at least one organic liquid having a kauri-butanol value within the range of from about 25 to about 75; from about 0.8 to about 2.8 volume percent of the bath of at least one organic solvent having a kauri-butanol value within the range of from about 75 to about 100; from about 0.25 to about 1.0 volume percent of the bath of at least one organic solvent having a kauri-butanol value in excess of 100; from about 1.2 to about 1.8 grams per liter of at least

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• 1964
  • 1964-08-27 US US392589A patent/US3320171A/en not_active Expired - Lifetime
• 1965
  • 1965-07-21 DE DE19651496156 patent/DE1496156B1/de active Pending
  • 1965-07-28 CH CH1057765A patent/CH458400A/de unknown
  • 1965-08-11 GB GB34429/65A patent/GB1041160A/en not_active Expired
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  • 1965-08-27 BE BE668902D patent/BE668902A/xx unknown

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