US2317370A

US2317370A - Method of setting printing inks and composition therefor

Info

Publication number: US2317370A
Application number: US340338A
Authority: US
Inventors: Geese Charles
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-06-13
Filing date: 1940-06-13
Publication date: 1943-04-27
Anticipated expiration: 1960-04-27

Description

-' 106, COMPOSITIONS,

COATING OR PLASTIC Patented Apr. 27, 1943 s 7:

CROSS REFERENCE METHOD OF SE'ITING PRINTING INKS AND COMI'OSITION THEREFOR charles qeese, Somerton, Pa.

No Drawing. Application June 13, 194 Serial No.340,338

The invention relates to printing, and more particularly to the method of accelerating 'the drying of printing inks immediately after they have been transferred to the material to be printed upon. More particularly the invention relates to the use of liquid sprays which I have discovered are very beneficial in connection with the drying of printing inks. I

In high speed printing presses a long recognized obstacle to obtaining uniform high grade printing has been the difficulty of drying the-ink fast enough to prevent the oilsetting or smearing of ink from freshly. printed sheets or webs, as, for example, paper, during the steps which immediately follow the printing steps, namely, during the piling of the sheets or the folding or winding of printed webs. The condition thus produced is commonly known as offset.

The methods and expedients to overcome' this undesirable condition that have been commonly adopted in the printing art have not beenidirooted to attacking the source of the difiiculty, namely, the slowness in dryingof the printing inks, but have more or less accepted that condition and have sought means of eliminating the undesirable results of the existing conditionproduced by relatively slow drying inks. The makeshift method of preventing the smearing of. the slow drying inks has been to deposit, as by spraying, a multitude of minute particles upon the freshly printed sheets or webs, the particles serving in effect as small projections upon the:surface of the sheet and spacing the sheets orportions of the webs sufliciently apart so that the ink from one sheet or web will not be transferred to an adjacent sheet or portion of the web. Various substances, both in dry -or solution form, have been employed as the ofiset preventing;particles. For example, such substance as wax,-cellulos e derivatives and clay, tal c and the like, we

been employed as showif'ii'i the Young Patent No. 2,114,792, the Bucy Patent No. 2,0'78,' 790, and the Grammer Patent;l Io,'- 1,445,273. Obviously, these methods are merelymakeshift expedients without attacking thebasic dimculty, namely, of accelerating drying of theljnk and in themselves frequently smear or gumup the"printed, sheets and the moving parts of the printing'press.

The primary object of the present inyention the printing ink is immobilized and the smearing is to attack the basic difficulty' of the offsetting'efio of the ink is prevented and the effective drying or setting thereof is accelerated.

It has been found particularly essential in the practice of the invention that in spraying any of the solutions which I have found to be satisfactory on the freshly printed sheets or web the solution or suspension be in very finely-divided form. An excess of the solution in any spot or area is as objectionable as is a deficit of the solution. In sprays containing numerous liquid particles of relatively large diameter, the heavy particles not only tend to deposit at a disproportionate rate; but it is impossible to maintain a 'uniform'density of liquid'in the air above the sheet or web to be sprayed, and irregular and uncontrollable results are obtained. It is preferred that the particles be kept of approximately 50 microns in diameter or smaller, and it has been found that the spray of the solution of that order may be deposited readily and uniformly on the freshly printed sheets or webs.

The invention may'be employed to facilitate the setting of any of the various types of printing ink,'in cluding the oil or varnish base inks and the cellulose base inks, and the invention may be employed in general'letterpress printing such as fiat-bed or rotary presses including newspaper presses and color printing as well as offsetlithographic printing. I

Particular solutions which I have found satisfactory are the alkaline silicates which are soluble in water and whi'cfiihhy be employed with or without modifiers. For example, aqueous solutions of sodium silicate and potassium silicate have been oun par icularly suitable. e solution is preferably applied to the freshly printed paper in the finely divided form described just after it emerges from the printin cylinders and as it is passing over the delivery mechanism.

Any suitable spraying means may be employed, for example, a liquid atomizing device adapted to spray the solution in the form of a finely divided mist. The spraying mechanism may comprise one or a plurality of spraying -n0zzles preferably disposed above the printed sheet and adapted to spray downwardly in such manner that a continuous and even filmis formed on the entire printed surface; the number of spraying nozzles employed is dependgntajupon the width of the "printed' sheet or web,'the number being suflicient so that fthe entire width of the sheet is covered. The spraying mechanism is preferably enclosed in a hoodin order that the spray may not escape and spread through the pressroom.

The concentration of the silicate in the aque- Examiner ous solution may vary within rather wide limits, depending upon the type of printing and the nature of the paper employed, for example, in printing on newspaper stock in a rotary web press a satisfactory solution to be sprayed upon the freshly printed web may comprise approximately -12 sodium silicate, in offset printing an aqueous so ution comprising sodium silicate as 'eefi round satisfactory, and in general letterpress printing such as on fiat beds and printing on cartons a solution comprising 50% sodium silicate has been found to be suitable. The concentration of the solution has an important bearing on the character of the drying action, since if the solution is extremely dilute it will not set fast enough after being sprayed upon the freshly printed paper, and if it is extremely concentrated it will set too rapidly and before the solution has properly penetrated the paper fibres and formed a continuous film.

When the silicate solution is sprayed in the form of a mist on the freshly printed paper, a very thin film is formed over the printed surface which penetrates to some extent into the fibres of the paper. a gel forming a glaze over each fibre and between the surface fibres. Since the layer of ink on the freshly printed paper is quite thin, it also is absorbed into the surface fibres of the paper and it is believed that there is some intermingling or interaction of the ink and the silicate in the paper fibre so that, when the silicate sets into a gel, the ink will be immobilized and held quite firmly in place. Even where the ink deposit on the sheet is fairly heavy as in solids, it is fairly well surrounded with the silicate gel since the silicate solution penetrates into the paper fibres very rapidly. Evaporation of the solvent continues .for some time after the silicate gel has formed on the printed surface and within the paper fibres, and the resulting surface gel or glaze is quite porous so that oxygen may readily penetrate it and accentuate the normal process 01 the drying of the ink. As previously set forth, the alkaline silicates are preferred since the more alkaline the silicate the greater is the wetting power or degree of penetration of the solution into the paper fibres, whereas the less alkaline silicates will tend to set faster.

After the solution has been sprayed on the freshly printed paper, the evaporation of the solvent may be accelerated by heating the sheet by means of a gas flame under the sheet, such as is now the standard equipment on numerous printing presses, or by any other suitable heating element.

In view of the porosity of the silicate gel on the freshly printed surface, a second layer of ink may be readily printed thereon, as in color printing, and the process of printing and then spraying with the silicate solution may be repeated quite a number of times with satisfac- The solution then sets to tory results. Furthermore, if desired, a film of a silicate solution may be applied to the paper before it has been printed upon.

A modification of the method contemplates the inclusion of a small percentage of watersoluble or water-dispersible wax in the silicate solution. For example, four ounces of a watersoluble or water dispersible wax may be dissolved in a gallon of a 20% solution of sodium silicate.

An important feature of the method is the fact that fine printing can be obtained with less expensive inks in that it is not necessary to employ with my method printing inks having expensive volatile solvents and driers.

I claim:

"1. The method of setting printing ink comprising applying an alkaline silicate solution in finely divided form to a freshly printed surface.

2. The method of setting printing ink which comprises spraying a solution of a water-soluble silicate upon a freshly printed surface. 3. The method of setting printing ink comprising applying a thin film of an aqueous solution of sodium silicate in finely divided form to a freshly printed surface.

4. The method of setting printing ink comprising applying a thin film of an aqueous solution of potassium silicate in finely divided form to a freshly printed surface.

5. The method of setting printing ink which comprises applying to a freshly printed surface a'thin film of an aqueous solution of an alkaline silicate in finely divided form and heating said printed material to accelerate the evaporation of the solvent.

6. The method of printing which comprises applying a film of an aqueous solution of an alkaline silicate in finely divided form to the surface of material to be printed upon just prior to the time printing ink is applied to said surface.

7. The method of setting printing inks cornprising applying a thin film of an aqueous solution of :an alkaline silicate and a small proportion of a water soluble or water dispersible wax in finely divided form to a freshly printed surface.

8. A composition of matter for setting printing inks which may be applied to a freshly printed surface in finely divided form, comprising an aqueous solution of an alkaline silicate having relatively high wetting power and adapted to rapidly penetrate the paper fibres, said alkaline silicate comprising 10-50% of the solution.

9. A composition of matter for setting printing inks, which may be sprayed upon a freshly printed surface in finely divided form, comprising an aqueous solution having a major proportion of an alkaline silicate and minor proportions of a water-soluble wax.

CHARLES GEESE.