US2217620A - Method of and apparatus for printing - Google Patents

Description

w. 1.. JONES METHOD OF AND APPARATUS FOR FRINTING Filed Feb. 10, 1939 INVENTOR VILBUR JONES ATTORNEY v Patented Oct. 8, 1940 UNITED STATES METHOD OF AND APPARATUS FOR PRINTING Wilbur L. Jones, New York, N. Y., assignor to In-; tel-chemical Corporation, New York, N. Y., a

corporation of Ohio Application February 10, 1939, Serial No. 255,565 1 80ialms.

This invention relates to the art printing and aims to provide a novel method and apparatus for printing on both sides of a web with a marking material which is liquid when heated 5 and solid at normal room temperatures.

There are now available for use in printing and coating paper so-called thermoplastic" inks or marking materials whose vehicles consist essentially of normally solid but readily liqueflable substances which melt and become fiuid when heated. These inks or marking materials have been used heretofore in the making of transfers for clothing patterns, and as coatings for carbon paper. Recently in my copending joint application with Earl H. McLeod, Serial No. 147,210, filed June 9, 1937, which issued on February 21, 1939, as Patent No. 2,147,651, it has been suggested that, by using the thermoplastic inks described therein, satisfactory multi-color printing may be effected. However, all prior known printing with thermoplastic inks has been carried out on only one side of the web.

In working with thermoplastic inks, it has been observed that many of the normal conditions of 85 operation of the press tend to cause the web to become heated. For example, the contact of the web with the heated printing cylinder transfers heat to the web; and the pressures employed for satisfactory printing create additional heat at the impression line. All such conditions tend to soften any printing or markings applied on the side of the web which contacts the impression cylinder, so that, when coupled with the usual pulling of the web during printing, smudging will inevitably result.

In spite of these difficulties, I have now found that inks which are'liquid when heated and solid when cooled may be used in perfecting or printing on both sides of a web or sheet in a completely satisfactory manner. This finding was based on my discovery that an ordinary web of paper; such as is used in newspaper printing, is a sufficiently effective heat insulator that. the first printed side of the web may be momentarily cooled while thesecond side is heated before or during printing or both, wheerby the first printwith a thermoplastic ink on one side thereof in any conventional manner; and is then turned and printed on its reverse side while simultaneously cooling the first applied impressions.

To carry out my invention, I have provided two suitable thermoplastic intaglio printing units and means for reversing the web between units so that its second side will be printed in the second unit. Each unit consists of an impression cylinder and an engraved printing cylinder which is preferably immersed in a heated bath of the ink and uniformly heated. In order to cool the first printed side of the web simultaneously with the second side printing and thereby prevent any undesirable smudging, the impression cylinder of the second printing unit is adapted to be cooled in any suitable manner, such as by the circulation of a refrigerating or cooling fluid therethrough, or by the use of a chilled back-up roller in conjunction therewith.

The above and other features and objects of the invention will be apparent upon consideration of the following detailed description of one illustrative embodiment, and the accompanying drawing, wherein the single figure is a diagrammatic representation of an apparatus with which my method may be practiced.

As shown in the drawing, a web 2, of paper or other material which is to. be printed on both sides, is fed in any convenient manner from a supply roll 4 over guide rolls 6, 6 to a first printing unit 8. If desired, the web 2, or at least the side thereof which is to be first printed, may be heated by means. of a hot roll or heating device lll. When operating at high speeds this is an important consideration for the web has a definite cooling effect on the parts of the printing unit which it contacts and may cause unsatisfactory results.

The first printing unit 8 comprises a resilient impression cylinder I2, an engraved printing cylinder H, which is immersed in a bath or fountain IQ of thermoplastic ink l8, and a suitable doctor blade 20 for removing excess ink from the printing cylinder and properly conditioning it for printing. Although I do not wish to be limited thereto, any of the thermoplastic inks disclosed in my copendlng application Serial No. 244,607, filed December 8, 1938, are suitable for 'the purposes herein contemplated. Such materials are preferably continuously agitated and maintained at a substantially constant level by a pumping system 22; and further are maintained at a suitable printing temperature in any convenient manner, such as by an electric heating device 22 or by circulating a heating fluid through the walls of the fountain I8. In certain cases it is also desirable to provide means for circulating a heating fluid through, or otherwise suitably heating, the printing cylinder it, although by immersing it in the heated ink i8, it tends to become uniformly heated and maintained at the desired uniform printing temperature.

Following the printing on one side of the web 2 in the printing unit 8, the printed side is cooled by means of a chilled air blast 28, or any other suitable cooling means, and is then led over guide rollers 28, 30, 32 and 34 to a second printing unit 36. These guide rollers, which constitute a reversing or turning means for the web, are so arranged that the web will be turned before entering the second printing unit where the thermoplastic ink is to be applied to the unprinted side thereof. The printing unit 36 is in most respects, identical with the first printing unit 8, and comprises an impression cylinder 38, and an engraved printing cylinder 40 immersed in a bath or fountain 42 of the thermoplastic ink 44. A doctor blade-46, heating means 48, and a pumping system 50 are also provided.

It would normally be expected that the heat from the heated printing cylinder and that created by the pressure employed during printing would soften the first printed impressions so that the smooth faced impression cylinder would cause them to smudge. I have found, however, that in spite of this difilculty, satisfactory printing on both sides of the web may be accomplished and any smudging tendency eliminated by cooling the first printed side simultaneously with the second printing. Apparently ordinary paper stock has a sufficiently effective insulating power to permit a heating of one side of the paper for proper printing and a simultaneous cooling of the other side for preserving the first applied impressions. For accomplishing such a simultaneous cooling of the printedside of the web, the impression cylinder, which is hollow, is preferably chilled by circulating a cooling or refrigerating liquid therethrough in any convenient manner, and/or by contact with a chilled back-up or pressure cylinder'5l. In most cases, the cooling thus obtained is sumcient, but, if desired, it may be supplemented by the use: of a chilled air blast 52 directed upon the printed side of the web and into the nip between the impression and printing cylinders.

There may be situations where the web, in traveling between the two printing units, becomes sufiiciently cool to cause an undesirable chilling of the heated printing cylinder 40. In such event, it may be desirable to heat the unprinted side of the web by means of a suitable heater 54. It will Q be understood that, when the web is traveling at relatively high speeds, any heating of the un printed side or cooling of the printed side will only be momentary, but it is nevertheless sufiicient to accomplish the desired results; and, as already mentioned, due to the insulating effect of the paper, the heating and cooling will not be counteracted during the printing operation.

After the web has been printed on both sides in the manner described, it may be cooled by means of chilled air blasts 5i, and then passed over a guide roller 58 to any desired subsequent web treating devices, such as cutters, folders, or a rewind mechanism.

Although I have shown and described my invention as applied to intaglio or gravure printing, it will be apparent that it may also be embodied in other well known types of printing equipment, and in its broader aspects may be utilized in the two-side coating of paper. Various changes may be made in the apparatus and method herein described, and certain features or steps may be employed without others, without departing from my invention or sacrificing any of its advantages.

What I claim is:

1. A method of printing with an ink which is liquid when heated and solid when cooled, which comprises printing with such an ink on one side of a traveling web, and then printing with such an ink on the other side of said web while simultaneously cooling the first printed side at the place where such second side printing is taking place.

2. A method of printing with an ink which is liquid when heated and solid when cooled, which comprises printing with such an ink on one side of a traveling web; causing such first applied impression to set; printing on the other side of said web while simultaneously cooling said first applied impression at a point in the travel of the web which is substantially immediately adjacent the place where such second side printing is taking place so as to prevent said first applied impression from smudging during the second side printing; and causing such second applied impression to set.

3. Apparatus for printing on both sides of a traveling web with an ink which is liquid when heated and solid when cooled, which comprises a first heated printing cylinder and cooperating impression cylinder for printing on one side of -said web; means for turning said web to bring the other side thereof into printing position; a second printing cylinder and cooperating impression cylinder for printing on the other'side of said web; and means disposed adjacent said second heated printing cylinder and cooperating impression cylinder for cooling at least the first printed side of the web.

4. A method of printing with an ink which is liquid when heated and solid when cooled, which comprises printing on one side of a traveling web by means of an intaglio printing couple including an impression cylinder and an engraved printing cylinder immersed in a heated bath of the ink; and then printing on the other .side of said web by means of a second intaglio printing couple including an engraved printing cylinder immersed in a heated bath of the ink and a cooperating cooled impression cylinder.

5. Apparatus for printing on both sides of a traveling web with an ink which is liquid when heated and solid when cooled, which comprises means for printing with such an ink on one side of said web; means for printing with such an ink on the other side of said web; and means disposed adjacent such second printing means for cooling the first printed side of said web while the second side is being printed.

6. Apparatus for printing on both sides of a traveling web with an ink which is liquid when heated and solid when cool'ed, which comprises means for printing with such an ink on one side of said web; and means for printing with such an ink on the other side of said web, said last mentioned means including means for cooling the first printed side of said web while the second side is being printed.

'7. Apparatus for printing on both sides of a traveling web with an ink which is liquid when heated and solid when cooled, which comprises a. nrst heated printing cylinder and cooperating impression cylinder for printing on one side of said web; means ior turning said web to brinl the other side into printing position; end a second heated printing cylinder and cooperstinl in pression cylinder for printing on the other side of said web, said second impression cylinder being cooled so as to cool the first printed side 0! the web while the second side is being printed.

8. Apparatus for printing on both sides of a traveling web withan ink which is liquid when printed side of the web and into the nip between 10 the second printing and impression cylinders. v

mm L. JONES.

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