US2780168A - Composition for use in eliminating oil and grease smudges from offset printing mats and plates - Google Patents

Description

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COMPOSITION FOR USE IN ELINIINATING OIL AND GREASE SMUDGES FROM OFFSET PRINT- ING MATS AND PLATES Oliver S. Nichols, Granite City, 111., assignor of one-half to John H. Schneider, Lake Bluff, lll.

No Drawing. Application November 16, 1951, Serial No. 256,829

2 Claims. c1. 101-4491 This invention relates to a liquid composition for use upon planographic printing plates including parchment or like cellulose base and metal planographic plates, and in particular to liquid compositions for the elimination of oil and grease smudges from such plates or mats, and to a method of making the said composition.

Briefly stated, the composition of this invention comprises a mixture of a water-miscible aliphatic alcohol selected from the group consisting of isopropyl alcohol, glycerol and glycols with water and an aqueous colloid dispersion of silicic acid, said mixture being adjusted to a pH in the range of 3-5, and desirably buffered in that range. The effectiveness of the composition in removing oil and grease smudges from offset mats or plates is developed by the addition of a water-immiscible solvent, such as a petroleum ether solvent, to the mixture and shaking together the two layers thus formed to provide a dispersion of droplets of the solvent throughout the aqueous layer before applying the composition to the smudges on the mat or plate.

Among the objects of this invention is the provision of a novel composition for the elimination of oil and grease smudges from offset printing mats or planographic plates; the provision of a composition for the removal of oil and grease smudges from offset printing mats or planographic plates; the provision of a composition for the removal of oil and grease smudges from offset printing mats and plates which is compatible with the repellent solutions employed in preparing the mat or plate for the inking operation and free from any effect upon such repellent solutions when employed for their intended purpose; the provision of a composition for eliminating oil and grease smudges from offset printing mats and plates with a minimum of deterioration or weakening of the image or ink lines present on the mat and which are to be reproduced; the provision of an aqueous composition which, when agitated with a water-immiscible organic solvent of the petroleum ether type to disperse the solvent throughout the aqueous phase in the form of droplets and applied to offset printing mats and plates, renders oil and grease smudges present on the mats and plates incapable of attracting ink during the planographic printing process; and the provision of a method for making oil and grease smudge elimination compositions. Other features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the ingredients and combinations of ingredients, the proportions thereof, steps and sequence of steps, and features of composition and manipulation, which will be exemplified in the products and methods hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the preparation of planographic printing plates for the printing operation, etching solutions are applied to the plate to render the non-printing areas of the plate repellent to greasy or fatty acid-containing planographic printing inks. Similarly, in the preparation of plates rates Patent 9 2,780,168 Patented Feb. 5, 1957 or mats of parchment or like cellulose base for the offset printing operation, so-called etching or repellent solutions are applied to render the non-printing areas of the mat repellent to greasy or fatty acid-containing planographic printing inks. In the handling of these plates or mats before, during or after the operation of applying to the plate or mat the image or impression which is to be copied, oil and grease smudges are frequently formed on the plates or mats as a result of contact with the fingers of the operator or others who handle the plate or mat, or as a result of contact with the plate or mat with oily or greasy surfaces or objects. The smudges thus formed are frequently transparent and hence escape the notice of the operator until the mat is placed on the duplicating machine, inked and impressions are run off. At that time, the oil or grease smudges attract ink and print off on the blanket of the machine and thereafter on the impression paper areas of ink corresponding to the areas covered by the oil or grease smudges. These ink smudges resulting from the attraction of ink to the oil or grease smudges frequently cover large areas of the impression copy and render the copy illegible and unsightly. The oil or grease smudges are not effectively removed from the mat by rubbing the mat with conventional etching or repellent solutions and any dimunition in the extent of the oil or grease smudge by this means is accompanied with damage or weakening of the impression to an extent which renders it impractical to attempt to remove oil or grease smudges with conventional etching or repellent solutions in this manner. The presence of oil and grease smudges on offset printing mats and plates and the lack of any effective means or material heretofore for removing or dispersing these oil or grease smudges has generally handicapped the utility of the offset printing mat as a medium for producing legible, clean copies.

According to the present invention, generally stated, an effective composition for eliminating oil and grease smudges from offset printing mats and plates substantially without weakening the image on the mat is provided by mixing a water-miscible aliphatic alcohol selected from the group consisting of isopropyl alcohol, glycerol and glycols, with an aqueous colloid dispersion of silicic acid, adjusting the pH of the solution to a pH within the range of 3-5, for example, by the addition of a small quantity of an acid, and desirably buffering the solution, forexample, by the addition of ammonium dihydrogen phosphate to the solution. This solution when mixed with a water-immiscible organic solvent such as mineral spirits having a boiling point range of 300-317" F. and a specific gravity of 0.782 and agitated to disperse the waterimm'iscible organic solvent as droplets throughout the aqueous portion, provides an effective composition for application to offset printing mats, for example, by means of a wad of cotton soaked with the solution and rubbed on the smudged portions, over the entire surface of the mat. Inasmuch as it has been found unnecessary to remove the composition from the mat after the rubbing operation, the composition may be said to render the smudges ineffective as ink-attracting areas, probably by dispersing the oil or grease smudges in the composition as it is rubbed over the met and preventing the oil or grease thereafter from redepositing on the mat or attracting ink. The dispersion of droplets of the water-immiscible solvent in the aqueous portion by shaking the two layers together serves to provide sufficient of the two layer components in conjunction with each other on the surface of the mat so that these materials can cooperate to produce the desired result. The droplets tend to coalesce quickly upon standing and it is necessary to shake the layers together each time before applying the composition to the cotton wad or other medium for application to. the mat.

The composition composed of the aqueous and non-aqueous layers ma'y'be employed in the form of a stable emulsion produced with the aid of a suitable emulsifying agent. However, it has not been found necessary to resort to that practice and furthermore it is desirable in the offset printing process to avoid emulsions which may tend to emulsi-fy the greasy or fatty acld base inks and thereby weaken the image on the mat or blur the impression on the copy paper.

The composition of this invention may be applied either before or after the application of the conventional etching or repellent solution normally applied to the mat for rendering the non-printing areas repellent to grease and fatty acid-containing plano'graphic inks. The operator may apply the composition over the entire surface of the mat before the mat is placed on the duplicating machine or may run off an impression on the duplicating machine to locate smudged areas on the repellentwetted mat through their ink-attracting characteristics and may then rub the composition over the smudged areas while the mat is in position on the machine to disperse and sequester the oil and grease smudges in the applied composition and thereby render the smudges i11- capable of attracting the ink in the subsequent running off of copies or impressions on the machine. The composition of this invention has been found to remove oil and grease smudges on offset printing mats and plates, including those areas of the plate or mat on which lines or typing are present, without weakening the lines or the typing. After treatment of the plate or mat with the composition, the impressions run oif on the duplicating machine show the lines and typing as clearly as though the oil and grease smudges had never been present on the plate or mat. it has further been found that any residual ink smudge on the blanket of the duplicating machine after the mat has been treated with the composition of this invention will run off and become dissipated in a few copies and thereafter be absent from the subsequent copies. it is unnecessary therefore to clean the blanket roll for the purpose of removing the ink transfer thereto by oil or grease smudges as long as the composition of the present invention has been employed on the mat for the purpose of dispersing the oil and grease smudges. It is generally the custom in the offset printing trade to allow mats to stand for approximately twelve hours before running them on the duplicator machine, in order to set or age the ink lines or typing and thereby to minimize any tendency for the lines or typing to wear off rapidly. This practice is desirable in connection with the application of the composition of the present invention to oil and grease smudges on the mats, out is not essential, since the composition may be applied to mats which have not been aged quite as long as the customary period.

Illustrative of the water-miscible aliphatic secondary alcohol suitable for the purpose of the present invention is isopropyl alcohol. Illustrative of the water-miscible gly cols for the same purpose are ethylene glycol, propylene glycol, triinethylene glycol and diethylene glycol. Glycerol is the preferred trihydric alcohol. These aliphatic alcohols are miscible with Water in all proportions and hence the concentrations of the alcohol for the purpose of this invention can be readily attained. The watermiscible aliphatic alcohol content of the composition of the present invention may be varied between the limits of -80 parts by volume of the aqueous solution, and preferably between the limits of 10-4O parts by volume. A small quantity of a Water-soluble aldehyde, for example, 0.l2% by Weight of the aqueous solution, for example, formaldehyde, acetaldehyde or furfuraldehyde, when added to the solution, particularly at the higher concentrations of the water-miscible aliphatic alcohol, serves to prevent the composition from forming an oil-inwater type of emulsion with fatty or greasy lithographic inks and consequent glazing of the ink rolls of pianographic printing presses or duplicators. In most instances, the aldehyde has not been found necessary.

The pH of the composition in the range of 3-5 may be elfected by the addition of small quantities of an acid such as phosphoric, axalic, glycolic, glyoxylic, pyruvic acids or the like. It frequently happens that glycols contain sufficient acid as a result of oxidation on standing to render their aqueous solutions acidic in the pH range of 3-5. In that case, no additional acid need be added. The aqueous composition'is desirably buttered in the pH range of 3-5, for example, by the addition of a builering agent which will maintain the pH of the aqueous solution in that range. Mono-ammonium dihydrogen phosphate in the amount of 2% by weight of the aqueous solution (i. e., prior to the addition of the Water-immiscible solvent) has been found satisfactory for this purpose. Smaller or larger quantities of the buffering agent may be employed but it is desirable to maintain the concentration of both the acid and the bulfering agent at as low a level as possible and still achieve a stable pH in the range of 3-5. While fatty acids such as acetic andpropionic acids may be employed for the acidifying operation, it is desirable to avoid the use of fatty acids, sincethey tend to weaken the image on the mat and render the image less capable of attracting ink when the mat is inked for the purpose of. preparing copies. Strong acids such as phosphoric and sulfuric acid may be employedin sparing amounts.

The aqueous colloidal silicic acid dispersion component of the aqueous composition of this invention is conventionally prepared by passing aqueous sodium ortho silicate solutions through'a bed of cation exchange resins and then through a bed of anion exchange resins to remove all but a trace of the cations and anions, leaving a colloidal solution ofsilicic acid which may range in silicic acid content from 1-15% or more byweight, depending upon the concentration of the sodium ortho silicate starting solution. Other methods of preparing the colloidal solution of silicic acid may be employed. The quantity of aqueous colloidal silicic acid solution for admixture with the other components of the composition of this invention may vary Widely. For example, a 1% colloidal silicic acid solution (20 cc.) when admixed with a solution of glycerol (35 cc.) in water (45 cc.), which latter solution has been adjusted in pH to within the range of 3-5 by the addition of 0.5 cc. of phosphoric acid, and agitated with a petroleum solvent (ll) cc.) having a boiling point range of 300-317" F. and a specific gravity of 0.782, has been found very eifective in dispersing oil and grease smudges on offset printing mats. Smaller concentrations of colloidal silicic acid solution may be employed in the composition of the present in vention with diminishing effectiveness. Larger amounts are desirable and the upper limit is fixed by the amount of Water permissible in the composition in view of the concentration of the Water-miscible aliphatic alcohol selected.

The Water-immiscible organic solvent employed in the composition of the present invention is desirably selected from among those petroleum solvents known as petroleum ethers, consisting essentially of paratfins, chiefly hexane and heptane', both mixed and straight, which possess a sufficiently slow rate of evaporation to permit the droplets of solvent to remain in contact with the oil or grease smudge on the matin conjunction with the aqueous portion of the composition long enough to disperse the oil or grease in the composition without evaporating prematurely with subsequent'redeposition of the oil or grease upon the mat. Once the oil or grease has been dispersed in the composition of this invention as applied to the mat, there appears to be no tendency for the oil or grease thereafter to attract ink in the subsequent inking operation. The quantity of water-immiscible solvent employed with the aqueous composition may be relatively small, since it is only necessary to provide a dispersion of droplets of the solvent throughout the aqueous composition at the time the composition is applied to oil and grease 15 smudges. For example,.10 ml. of water-immiscible solventadded to 100 cc. of the aqueous composition has been found to be adequate. More or less than this amount may be employed. Too much of the waterimmiscible solvent tends to leave a residue of solvent on the mat which will tend to attract ink and print out as anink smudge on the impressions. A desirable solvent for the purpose of the present invention has been found to be a mineral spirits fraction having a boiling point range of 300-317 F. and a specific gravity of 0.782. Another petroleum ether solvent known to the trade as Stoddards solvent, having a boiling point range of 300- 400 F., has been found satisfactory. Other mineral spirits solvents having boiling point ranges of 3l0360 F. and 360-410 R, respectively, and specific gravities of 0.7699 and 0.7857, respectively, have been found satisfactory. Other water-immiscible solvents having the aforescribed properties as well as the characteristics described hereinbefore in conjunction with the composition of the present invention may be employed. Many of the petroleum solvents available commercially contain portions of aromatic solvents. Such petroleum solvents have also been found satisfactory for the purpose of the present invention when they possess a suitably low evaporation rate.

The composition containing the water-miscible aliphatic alcohol, colloidal silicic acid solution, water and hydrogen ions may be dispensed commercially in suitable containers such as glass bottles and the petroleum ether may be added to the container or to a portion of the solution and shaken therewithjust prior to using 'the composition on offset printing mats and plates.

.The following examples will serve to illustrate the methodsand products of the present invention:

Example I Parts by volume Propylene glycol (containing acidic oxidation products 40 Water 40 Colloidal silicic acid solution (1% silicic acid by weight, in water) 20 The propylene glycol and water were mixed and the colloidal silicic acid solution was admixed therewith. The resulting solution was found to have a pH in the range of 3-5 as a result of the acidic oxidation products present in the propylene glycol. To the solution was added mineral spirits ml.) having a boiling point range of 300-317 F. and a specific gravity of 0.782.

.The two layers were shaken together until the mineral spirits .became dispersed in the aqueous layer in the form of small'droplets. The composition was then 'applied by means of a piece of cotton 'soaked with the mixture to a cellulose base offset printing mat (known to the trade as Colitho) upon which drawings and typing had been executed and oil and grease smudges had been deposited through handling of the mat by various personnel. The that had previously been wetted with a glycerol-base etching or repellent solution, inked on a duplicator machine and several copies run therefrom. .The oil and grease smudges which were invisible prior to the inking operation attracted ink and transferred an image of the smudges to the copies. The oil and grease smudge eliminating composition of the invention as illustrated hereinabove was then applied to the wetted mat with moderate rubbing over the areas of the mat correspondingto theareas of visible ink smudge on the copies. The mat was then inked in the machine and copies were run oif. After a run-off of several copies, the ink smudges ceased to appear on the copies. The

' lines of the drawings and the typing appearing on the copies were clear and sharp with substantially no evidence of weakening of the image on the mat through application of the smudge eliminating composition to the lines and typing on the oifset printing mat. This was evidence of the fact that the smudge removing composition did not destroy the lines of the drawing and typing or weaken them was to render them incapable of attracting ink during the inking operation, or interfere in any manner with, the proper functioning of the printing operation.

It was also found that the smudge eliminating composition could be applied to the mat prior to the wetting of the mat with a repellent solution with equally good results, rubbing the composition over the entire area of the surface of the mat to insure that any invisible oil or grease smudges present on the mat were eliminated.

Example ll Parts by volume Glycerol 30 Mono-ammonium dihydrogen phosphate (10% by weight, solution in water) l0 Colloidal silicic acid solution (5% silicic acid by weight, in water) 10 The glycerol was dissolved in the mono-ammonium dihydrogen phosphatesolution and the colloidal silicic acid solution was admixed therewith. To the solution thus formed was added phosphoric acid (0.5 ml., The pH of the solution was in the range of 3-5. To the resulting mixture ml.) was added a petroleum ether fraction (10 ml.) having a boiling point range of 310-360 F. The resulting composition was shaken to disperse the petroleum ether layer in the form of fine droplets throughout the aqueous layer and was then applied to an oifset printing mat in the manner described in Example I with good results.

Example III Parts by volume Furfuraldehyde Colloidal silicic acid (5% silicic by Weight, in water)- 20.0

The furfuraldehyde and mono-ammonium dihydrogen phosphate were mixed together in the water and the glycerol and colloidal silicic acid solution were mixed. The two solutions were then thoroughly mixed together and the resulting composition was acidified with 0.5 g. of glycollic acid. The resulting composition was found to have a pH in the range of 3-5. Mineral spirits (10 ml.) having a boiling point range of 360-410 F. and a specific gravity of 0.7857 was added to the composition and the resulting composition was agitated to disperse the mineral spirits in the form of fine droplets throughout the aqueous layer.

The composition as thus prepared as applied to oil and grease smudges on offset printing mats according to the procedure described in Example I with excellent results.

Example IV Parts by volume Formaldehyde (37% in water) (Formalin) Mono-ammonium dihydrogen phosphate (2% by weight, in water) 24.5 Glycerol 20.0 Water 35.0

Colloidal silicic acid solution (1% silicic acid by weight, in water) 20.0

The formaldehyde and mono-ammonium dihydrogen phosphate solution were mixed and to this solution was Example V Parts by volume Isopropyl alcohol 40 Mono-ammonium dihydrogen phosphate (2% by weight, in water) 4O Colloidal silicic acid solution (1% silicic acid by weight, in water) 20 The isopropyl alcohol and mono-ammonium dihydrogen phosphate solutionwere mixed and to the resulting solution was added the colloidal silicic acid solution. The solution was found to have a pH in the range of 3-5. The solution (100 ml.) was placed in a bottle until the occasion arose to remove oil and grease smudges from offset printing mats. At that time, a petroleum ether fraction (20 ml.) having a boiling point'in the range of 300-317'F. was added and the twolayers were shaken together until the petroleum ether fraction became dispersed throughout theaqueous layer in the form of fine droplets. The resulting dispersion was then applied by means ofa piece of cotton to the oflset printing mat, rubbing the solution over the areas bearing the oil and grease smudges. The printing mat was then placed in a duplicator machine and inked in the usual manner. After a run-off of several copies, the subsequent impressions were found to be entirely free of ink smudges resulting from the attraction of ink by oil and grease on the mat.

Example V1 Parts by volume Ethylene glycol 1O Ammonium dihydrogen phosphate (2% by weight,

in water) 3O Colloidal silicic acid solution silicic acid by weight, in water) 60 The ethylene glycol and ammonium dihydrogen phosphate solution were mixed and the colloidal-silicic acid solution was added to the mixture. Glycolic acid was added to the solution until the pH of thesolution was in the range of 3-5. To the composition (100 ml.) thus prepared was added a petroleum ether fraction (10 ml.) having a boiling point in the range of 310-360 F. The two layers were agitated together to disperse the waterimmiscible layer in the aqueous layer in the form of fine droplets. The resulting composition was applied to oil and grease smudges on cellulose-base oifset printing mats in the manner described in Example I with good results.

Example VII Parts by volume The components were mixed in the order presented hereinabovc and a petroleum ether fraction (10 ml.) hav ing a boiling point in the range of 300-317 F. was added. The two layers were shaken together to disperse the petroleum ether fraction in the form of droplets throughout the aqueous layer and the composition was applied to offset printing mats in the manner described in Example I with excellent results.

In view of the above, it will be seen-that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above methods and products withoutdeparting from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limitingrsense.

I claim:

1. A composition for rendering oil and grease smudges present on planographic mats and plates incapable of attracting ink during the planographic process, comprising as an aqueous phase 10-80 parts by volume of a watermiscible aliphatic alcohol selected from the group consisting of glycerol and glycols, water and 1060 parts by volume of a colloidal solution of silicic acid in water containing 1-15 by weight of silicic acid, said aqueous phase containing suflicient hydrogen ions to establish a pH in the range of 3-5, and as a non-aqueous phase about 10 ml. per 100 m1. of solution of a petroleum ether fraction boiling within the range of 300-420 F., said petroleum ether fraction adapted to be dispersed throughout said aqueous phase in the form of droplets by agitation of said phases together at the time of application of the composition to mats and plates.

2. A method for rendering. oil and grease smudges present on planographic mats and plates incapable of attracting ink during the planographic process comprising intimately contacting said smudges with a composition comprising as an aqueous phase 10-80 parts by volume of a water-miscible aliphatic alcohol selected from the group consisting of glycerol and glycols, water and 10-60 parts by volume of a colloidal solution containing 1-1S% by weight of silicic acid in water, said aqueous phase having a pH in the range of 35, and as a non-aqueous phase 10 ml. per ml. of solution of a petroleum ether fraction having a boiling point within the range of 300-420 F., said non-aqueous phase being dispersed throughout said aqueous phase in the form of droplets as a result of agitation of the two phases together at the time of application of said composition to said mats and plates.

References Cited in the file of this patent UNITED STATES PATENTS 1,892,875 Dietz Jan. 3, 1933 1,911,239 Reed et al May 30, 1933 1,922,006 Von Hoessle' Aug. 8, 1933 1,977,646 Rowell Oct. 23, 1934 2,016,517 Rowell Oct. 8, 1935 2,132,443 Simons Oct; 11', 1938 2,233,573 Ayers Mar. 4, 1941 2,297,929 Wise Oct. 6, 1942 2,311,047 Hagelin Feb. 16, 1943 2,356,773 Marshall Aug. 29, 1944 2,393,875 Van Dusen Jan: 29, 1 946 2,433,780 Marshall Dec. 30, 1947 2,515,536 Van Dusen' July 18, 1950 2,534,588 Frost Dec. 19, 1950 2,561,354 Finno -2 'July 24, 1951 2,635,056 Powers Apr. 14, 1953 2,681,617 Worthen et al June 2 2, 1954 FOREIGN PATENTS 8,544 Great Britain May- 18,- 1916 OTHER REFERENCES Conant: The Chemistry of Organic Compounds. Revised ed. 1939, MacMillan Co., N. Y. Only page 277 cited. (Copy available in Division 17.)

Ellis: Printing Inks, 1940. Reinhold Pub. Co., N. Y. Only pages 259 and 260 cited. (Copy available in-Div. 17.)

Claims (1)

1. 2. A METHOD FOR RENDERING OIL AND GREASE SMUDGES PRESENT ON PLANOGRAPHIC MATS AND PLATES INCAPABLE OF ATTRACTING INK DURING THE PLANOGRAPHIC PROCESS COMPRISING INTIMATELY CONTACTING SAID SMUDGES WITH A COMPOSITION COMPRISING AS AN AQUEOUS PHASE 10-80 PARTS BY VOLUME OF A WATER-MISCIBLE ALIPHATIC ALCOHOL SELECTED FROM THE GROUP CONSISTING OF GLYCEROL AND GLYCOLS, WATER AND 10-60 PARTS BY VOLUME OF A COLLOIDAL SOLUTION CONTAINING 1-15% BY WEIGHT OF SILICIC ACID IN WATEAR, SAID AQUEOUS PHASE HAVING A PH IN THE RANGE OF 3-5, AND AS A NON-AQUEOUS PHASES 10 ML. PER 100 ML. OF SOLUTION OF A PETROLEUM ETHER TRACTION HAVING A BOILING POINT WITHIN THE RANGE OF 300-420* F., SAID NON-AQUEOUS PHASES BEING DISPERSED THROUGHOUT SAID AQUEOUS PHASES IN THE FORM OF DROPLETS AS A RESULT OF AGITATION OF THE TWO PHASES TOGETHER AT THE TIME OF APPLICATION OF SAID COMPOSITION TO SAID MATS AND PLATES.