US3488859A - Method of drying printed or laminated sheets and webs of paper - Google Patents

Description

United States Patent 3,488,859 METHOD OF DRYING PRINTED 0R LAMINATED SHEETS AND WEBS OF PAPER Elmar Messerschmitt, Munich, Germany, assignor to Schnellpressenfabrik Frankenthal, Albert 81 Cie Aktiengesellschaft, Frankenthal, Pfalz, Germany, a corporation of Germany No Drawing. Filed Nov. 25, 1968, Ser. No. 778,773 Claims priority, application Germany, Nov. 25, 1967, 1,729,465 Int. Cl. F26b 7/00 US. Cl. 34-15 2 Claims ABSTRACT OF THE DISCLOSURE A method of drying printed or laminated sheets and webs of paper whereby warm and cold air is applied alternately to the materials to be dried along air zones in close succession. Moreover, the intensity of the applied air and the rate of succession of the warm and cold air zones is adjustable so that no appreciable change in moisture takes place to cause any undesirable shrinkage in the paper web or sheets.

This invention relates to a method of drying printed or laminated sheets and webs of paper by means of a stream of air.

Under conventional methods, printed Webs of paper are dried by applying a stream of air onto the webs by means of air nozzles. In this conventional method, Warm air is applied to the web for a longer than normal period of time. Thereafter, the web of paper is cooled down to room temperature by either applying cold air, or by means of rollers. The web of paper may also be heated by guiding it over heated drums.

In all of these drying methods, changes occur in the properties of the paper which result in shrinking of its sheets or webs. Moreover, when plastic foils are printed, changes in the properties of the foil will also occur when these conventional drying methods are used.

These changes in the aper properties are caused by a change in the dampness of the printed material, the webs of paper, or the foils.

If the web of paper is dried by means of air, or by means of drying drums, a portion of the water in the paper evaporates so that shrinking sets in. The same event also occurs when other materials are used, such as foils, etc.

In order to overcome these disadvantages, one method has attempted to dry the paper with unheated air or cold air. However, the drying effect of the cold air has been found to be too weak for drying the paper sufliciently when the sheets and the webs of paper are moved rapidly.

It is, therefore, an object of this invention to overcome the above identified disadvantages by providing a method whereby hot and cold air is alternately applied to the paper.

In the direction of the paper movement, warm and cold air zones are applied to the paper in close succession, whereby the succession and the intensity of the applied air are adjustable. This invention has the ad vantage, for example, that a printed sheet of paper which is introduced into the novel drying device is not heated, so that only the printing ink on the surface of the sheet of paper is dried.

Since the rather volatile solvents in the printing ink evaporate in a shorter period of time than the parts of water in the paper, the drying process is much more effective.

In this invention, the printing ink is alternately heated and cooled in a short period of time on the surface of the printed material, so that the solvent agents in the ink are evaporated in a pulsating fashion. Due to the short period of time under which drying takes place, and the fact that the air intensity is adjustible, evaporation of any appreciable moisture percentage in the paper material can thus be avoided. In addition, the succession of the warm and/or cold air zones may also be adjusted, i.e., two cold air zones may be adjusted in succession.

Since the moisture percentage of the paper material is not changed when applying this method, no shrinking occurs, and therefore, there are no changes in the properties of the paper.

While only a few embodiments of the present invention have been described, it will be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is:

1. A method of drying materials in motion such as printed, and laminated sheets and webs of paper by means of an air stream, comprising the steps of;

applying warm and cold air alternately to the materials to be dried, in close succession,

varying the intensity of the applied air, and

adjusting the rate of succession of said warm and cold air applications.

2. The method as recited in claim 1 wherein said step of applying additionally comprises the step of directing said hot and cold air along zones in the direction of motion of said paper material.

References Cited UNITED STATES PATENTS 273,013 2/1883 BedfOrd 34-62 X 1,768,455 6/1930 Gibson 34-66 2,469,270 5/1949 Liebel 34-66 2,807,096 9/1957 Kellgren 34-66 2,807,097 9/ 1957 Kellgren 34-66 2,952,078 9/1960 Litzler 34-66 2,955,342 10/ 1960 Litzler 34-66 3,065,551 11/1962 Cohn 34-62 3,318,018 5/1967 Steele 34-62 WILLIAM J. WYE, Primary Examiner US. Cl. X.R. 34-20, 62