US2319853A - Printing method and means - Google Patents

Description

M A H R U D N H PRINTING METHOD AND MEANS Filed May 10, 1939 ATTORNEY .PatentedMay 25, 1943 ram-rule METHOD AND MEANS Hobart N. Durham, Manhasset, N. Y., assignor to The Goss Printing Press Company, Chicago, 111., a corporation of Illinois Application May 10, 1939, Serial No. 272,822

Claims.

The invention relates to new and useful improvements in method and means for printing and drying printed surfaces, and more especially to such method and means for very rapidly drying printed surfaces in fast rotary presses. the invention being especially useful in fast rotary multicolor printing.

The invention consists in the novel methods, steps, sequences, mechanisms and combinations disclosed in the specification and pointed out in the appended claims.

Objects and advantages of the invention are set out in part hereinafter, and in part will be obvious to those skilled in the art or may be learned by practice with the invention.

The accompanying drawing, referred to herein and constituting a part hereof, illustrates one mechanical embodiment of the invention and one manner, of carrying out the method of the invention.

Of the drawing:

Fig. 1 is a diagrammatic elevation of a perfecting multi-color rotary press for relief printing, embodying the invention; and

Fig. 2 is a fragmentary, detail section on lines 22 of Fig. l.

Objects of the invention are to provide method and means for rapidly printing and easily and quickly drying inked impressions on a surface, and more especially quick and easy drying of impressions made on paper webs running through fast rotary presses. both in single color and multicolor printing; to provide such method and means which effect practically instantaneous drying without requiring wetting of the paper or its being subjected to sudden and violent temperature changes, thus avoiding consequent shrinkage, warping or other impairment of the webs resulting in poor register, strains and deformations in the webs, which especially militate against the best results, especially in certain types of multi-color printing; to provide such method and means applicable to the various kinds of printing including printing on fast relief and intaglio presses; to provide such method and means which avoid the necessity of high temperatures in press rooms, or in fact, any change in press room temperatures, and substantially avoid or eliminate fumes from the press room atmosphere, and likewise avoid the use upon the webs of flame, steam, strong air blasts and like forces and agencies; to provide method and means for rapidly printing and almost instantaneously drying the freshly printed webs by instantaneous ebullition of the volatile solvent in the ink on the web, by presenting the freshly printed impressions in an atmosphere below the vapor pressure of said volatile solvent at the printing locus, whereby the solvent flashes into vapor, as distinguished from usual drying by evaporation, burning, absorption, or oxidation, with the vapor pressure below the drying pressure; to provide, when desired, as auxiliary dryin agencies, relatively mild heat or air currents to a limited extent, to assist in the drying operation; to provide such method and means for use in a press room operating under normal atmospheric and temperature conditions, wherein the freshly printed surfaces are presented in an atmospheric pressure substantially below the vapor pressure at the press room temperature of the volatile solvent component of the ink; to provide rotary press structures and arrangements adapted for the practice of the method in relief, intaglio or other kinds of printing.

Referring now in detail to the embodiment of the invention, illustrated by way of example in the accompanying drawing, the invention is shown applied to a perfecting multi-color rotary relief press of the type wherein a plurality of plate cylinders, each having its own inking system, ooact as printing couples with a single large impression cylinder, and the web after being printed in multi-color on one side is directed to a similar mechanism to be perfected in multi-color. In said embodied form, each printing unit comprises an impression cylinder l and coacting therewith are shown four plate cylinders 2, 3, l and 5, provided. respectively, with inking mechanisms 6, I, 8 and 9. Theweb w as it goes through is printed in four colors in a known manner.

The immediate or quick dryingof the colors on the freshly printed web is effected entirely or principally by causing ebullition under reduced pressure of the highly volatile solvent in the printing ink. The invention finds one of its principal and most useful applications in fast rotary printing with the modern quick-drying inks. These inks comprise a coloring pigment or dye, a binder and a highly volatile solvent which has a high vapor pressure at usual or normal press- Acetone 2o; 185 so 283 Millimeters Means are provided by the invention for immediately subjecting the freshly printed surface of the web to an atmospheric pressure which is substantially below the vapor pressure of the volatile solvent in the ink at the temperature of the printing locus. In the embodied form of said means, a chamber is provided within which the required lower atmospheric pressure may be maintained, and the freshly printed web is led immediately thereinto. This results in immediate ebullition of the volatile solvent component of the ink, that is, it flashes into vapor, leaving the dry pigment and other non-volatile ink components as the design. This is effected without wetting the web, without subjecting it to either high or low temperature changes, or to flame or to strong air blasts; in fact, the web is left in its normal condition and not subjected to disturbing and deteriorative influences and changes that impair registration or other requisites of fine printing.

This low atmospheric pressure chambers, as embodied, comprises a relatively large drum 20 located near to the point of emergence of the web from the printing cylinders, the web being directed around the cylinder 20 for a large portion of its periphery. An almost completely closed chamber is formed around the cylinder 20, coincident with the path of travel of the web, and as embodied, a cylindrical plate 2| encircles a large part of the cylinder 20, and is spaced away therefrom so as to provide a chamber 22 between them. Seals are provided at either arcuate endof the plate 20, cooperating with the flat ends of the cylinder 20, and are shown as arcuate plates 23 fast to and extending from the arcuate edges of plate 2|, and having at their inner curved edges sealing members 24 abutting on and sucked against the fiat ends of cylinder 20. The suction within the chamber 22 draws the sealing members in tightly against cylinder 20, to form effective air seals. At the straight edges of the plate 2 I, which constitute the limits of the chamber 22, are closure plates 21 fixed to the straight edges of plate 2| and directed inwardly toward the drum 20, leaving just enough clearance for the web w to pass between the edges of the plates and the surface of the drum. Thus the cylindrical plate 2|, the side sealing plates 22 and the end plates 21 constitute a housing or closure about drum 20 within which the low atmospheric pressure is maintained. Air-exhausting means are provided exerting any desired degree of suction on the chamber 22, thereby to reduce the atmospheric pressure therein below the vapor pressure for the volatile solvent at the existent temperature, and as embodied, a pipe 29 communicates preferably with the central part of the chamber 20, and a pump 30 driven by a suitable motor 3| exhausts air from the chamber 22. This air carries off the vapors of the solvent as they are created within the chamber 22, and they are conveyed by a pipe 32 to any suitable recovery means.

There are preferably provided, as additional closure or air seal means for the chamber 22, at either end thereof, a plurality of vanes 31, fixed to the inner face of the cylindrical member 2|, and extending entirely across chamber 22. The vanes are preferably in side-by-side, parallel. spaced-apart relation, and directed toward the drum 20, but leaving a minimum clearance for the passing web w, the vanes being preferably in a non-radial relation. Because of the reduced atmospheric pressure within the chamber 22, air turbulence is created between and about the vanes 31 which impedes entrance of air, and acts to a larger extent as a sealing means, contributing to maintain the required lower atmospheric pressure within the chamber 22. At the same time this permits the passage of minute or very thin, sheet-like currents of air at high velocity which participate in the drying action, the main part of which, however, is effected by the ebullition of the solvent in the low pressure atmosphere of the chamber 22.

As an optional feature of the invention additional drying means may be provided within the chamber 22, although normally this will not be required and may not even be desirable. For this purpose, if desired, elements effecting mild heating action within the chamber 22 may be employed, as for instance, radiant heaters or infrared heaters 38. This auxiliary heating action,

if and when used, will exert a temperature effect on the web which is relatively mild and not sufficient to cause physical changes in the web such as shrinking, or cause undue heating of the press room. The purpose of such auxiliary means is to raise the temperature of the web merely sufficient to raise the vapor pressure somewhat of the ink and to overcome the heat loss caused by the ink evaporation.

In accordance with one feature of the invention, temperature reduction means are applied to the inking mechanisms for the plate cylinders 2, 3, 4 and 5, either in groups or to various mechanisms singly, to provide suificient chilling to prevent uneconomical evaporation of the ink solvent in the fountains or on the various members of the inking system. As here shown, each inking system is enclosed within a casing 4|, each such casing consisting wholly or partly of removable plates or members 42, whereby ready access can be had to the inking system for regulation, cleaning or other purposes. The inking systems there shown are of the type wherein the entire system is movable on the press frame into operative relation with the plate cylinder and also movable away therefrom to an accessible cleaning position. As shown, each of the casings 4| is provided with a plurality of refrigerating coils 43 connected by pipes 44 to a suitable refrigerating device 45.

It will be clear that the low atmospheric pressure chamber can be applied in like manner to other types of presses, such as rotogravure presses, or others, by leading the web from a printing couple into a chamber such as the chamber 22 which will operate in the manner hereinbefore described.

The invention consists in the novel steps, sequences, elements and combinations as pointed out in the accompanying claims, and it will be understood that departures may be made from the specific forms shown and described without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim is:

1. The method which comprises printing on a surface with an ink including a non-volatile color and a highly volatile solvent, and introducing said freshly printed surface into a lower pressure zone at a temperature below the boiling point at normal atmospheric pressure of the ink solvent, the pressure in said zone being sufficiently below the vapor pressure of said solvent to effect ebullition of the ink solvent.

2. The method which comprises printing on asurface with an ink including a non-volatile color and a highly volatile solvent at a given atmospheric pressure and immediately presenting the freshly printed surface in zone of less pressure at a temperature below the boiling point at normal atmospheric pressure of the ink solvent, the pressure being substantially below the vapor pressure of the solvent at the temperature of said zone to effect ebullition of the ink solvent.

3. The method which comprises printing on a surface with an ink including a non-volatile color and a highly volatile solvent, maintaining a chamber having a lower atmospheric pressure substantially below the vapor pressure of said solvent at the temperature of the printing locus and immediately presenting said freshly printed surface within said changer at a temperature below the boiling point of the ink solvent at normal atmospheric pressure and at a sufliciently reduced pressure to eflect ebullition of said vola tile solvent from the ink upon said surface while maintaining said printed surface out of contact with relatively movable members until dry.

4. The method which comprises printing on a surface with an ink including a non-volatile color and a solvent having a boiling point above the temperature of the printing locus and transferring the freshly printed web into a reduced pressure zone at a temperature below the boiling point at normal atmospheric pressure of said solvent the pressure in said zone being sufficiently below the vapor pressure of the ink solvent at the temperature of said zone to effect drying of the inked design by ebullition of said solvent said transferring being accomplished while supporting until dry the printed surface out of conto effect ebullition of a volatile solvent from the ink.

6. A printing press including in combination a rotary printing couple, inking means therefor, means for presenting a web to said printing couple to be imprinted thereby, a chamber and means for maintaining a partial atmospheric vacuum within the chamber of lower pressure than the vapor pressure of the ink solvent at the temperature of drying and means for directing the freshly printed web from the printing couple within said chamber and subject to the reduced atmospheric pressure therewithin to effect ebullition of a volatile solvent from the ink.

7. A printing press including in combination a rotary printing couple, inking means therefon.

means for presenting a web to said printing couple to be imprinted thereby, an arcuate chamber of lower pressure than the vapor pressure of the ink solvent at the temperature of drying into and about which the freshly printed web from the printing couple is directed and means for maintaining a partial vacuum within said chamber to effect ebullition of a volatile solvent from the freshly imprinted ink on the web.

8. A printing press including in combination a rotary printing couple, inking means therefor, means for presenting a web to said printing couple to be imprinted thereby, an arcuate chamber of lower pressure than the vapofpressure of the ink solvent at the temperature of drying into and about which the freshly printed web from the printing couple is directed and means for maintaining a partial vacuum within said chamber to effect ebullition of a volatile solvent from the freshly imprinted ink on the web, said means comprising mechanism for exhausting air from said chamber and closure devices located adjacent the points of entry into and emergence of the web from the chamber.

9. A printing press including in combination a rotary printing couple, inking means therefor, means for presenting a web to said printing couple to be imprinted thereby, and a chamber of lower pressure than the vapor pressure of the ink solvent at the temperature of drying for maintaining atmosphere at a reduced pressure comprising a drum about which the freshly printed web is directed, a housing spaced away from and enclosing the greater part of said drum, means for exhausting air from the chamber between the drum and housing and closure devices located adjacent the points of entry into and emergence of the web from the chamber, and means for directing a web into the chamber and about the drum and out of the chamber at the other end thereof.

10. A printing press including in combination a printing couple, inking means therefor, cooling means acting on the inking means to repress voiatilization of the ink, a casing about the inking means to reduce air circulation and evaporation, means for presenting paper to be imprinted by the printing couple, a chamber and means for maintaining a partial atmospheric vacuum of lower pressure than the vapor pressure of the ink solvent at the temperature of drying within the chamber and means for presenting the freshly printed paper within he chamber and subject to the reduced atmospheric pressure therewithin to effect ebullition of a volatile solvent from the ink.

HOBART N. DURHAM.

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