US2127955A - Method of printing - Google Patents

Description

Patented Aug. 23, I938 FATE N Ii/METHOD OF PRHNTHNG Philip A. Frazier, Oak Park, Ill.

No lDrawing. Application .luly 17, 1936,

Serial No. 91,095

9 Claims.

. The present invention relates to letterpress or relief printing generally and applies to printing from metallic plates, whether performed by presses with fiat, horizontal or vertical beds or rotary presses.

This invention also relates to an improved method of printing and more particularly to a method which makes the ink and the paper so unite as to secure results hitherto not obtained.

in This invention further resides in the method of printing whereby proper and sufiicient moisture is produced either by breaking up water with air or in the form of steam.

Among the objects of my invention are the production of a method of printing whereby clearer,

sharper printing is produced, even though the hourly rate of the run is speeded up from 30 to r 50% more than is now commercially practicable;

a method of printing where the ink lies on the surface of the paper, producing an even color distribution; a method of printing which elimihates the filling up of the middle tones or semisolids, which produces an unevenness of tone and makes the printing appear spotty and smudgy;

an improved method of printing whereby no heavy impression pressure is required even where runs are made at high speeds and so eliminates the practice of increasing pressure as the rate of the run increases which inevitably results in the 3D offsetting of the printing if sufficient printing pressure is obtained; an improved method of printing whereby a lustrous finish and sheen is produced instead of the dead lifeless color or tone of the present printing; an improved method of printing which will give from 15% to 30% greater ink coverage, or, stated another way, which will require from 15% to 30% less ink per job, thus eilecting substantial savings, together with such other and further objects as will appear as the description of this invention proceeds.

' It is Well known that in the making of paper it is necessary to evaporate as rapidly as possible the moisture from the web which ultimately forms the continuous sheet of paper. Usually this requires artificial driers operated at high temperatures. Also, if the paper is subjected to calendering, further high temperature drying is required. This forced evaporation of moisture from the paper has directly caused a printing 5o problem which has long been recognized, i, e., securing enough moisture in the paper to produce a creditable and commercial printing result. Various efforts have been made to apply water to the paper just prior to the printing, following the analogy of engraving. This has many serious (or. wit-42s) defects which make such wetting impracticable commercially, particularly where high speed work is essential. Among the various difiiculties caused by wetting of the paper are the uneven stretching of the wet paper which not only produces an s unsightly result but throws out the alignment of the pages and the register of the job. In short, no precision work can be attained or maintained; the inability to secure the proper tension on paper passing through the press because ofthe no weakening of the paper by the wetting, thus increasing to a serious extent, and in most cases to a non-commercial degree, the danger of breaking and tearing in the press. Further, if sunlcient wetting could be obtained, then the printed it material would have to be dried artificially, in-

creasing the cost of equipment and handling enormously.

Recently it has been demonstrated that a fair degree of success can be attained by so-called 20 humidification of the paper itself. By this means moisture is supplied to the paper as it is unrolled and passes through the press in a finely divided spray, the paper fibres absorbing this moisture prior to the printing. There is some lapse of 25 time before the ink is applied over the printing surface and before the inked printing surface is applied to the paper and if the spray is not operating perfectly and evenly for the particular kind of paper or subject being run, many diificulties so are encountered. If too little moisture is being applied, the lapse of time and the rapid move ment causes the paper to lose some of this moisture and thereby the paper is delivered to the inked printed surface too dry to obtain the reg sults claimed for this method. Or, if too much moisture is being applied even in one spot, then the dangers already enumerated for wetting of the paper are present. The application of moisture to the paper directly puts the moisture into M the paper fibres so that it may penetrate and be absorbed deeply and inwardly, expanding the fibres thereof to allow for quick and ready penetration of the ink when the inked printing surface comes in contact with the paper or subject. M

The method of printing which I have developed and invented recognizes the problem of securing moisture in printing, the solution of which has long been sought and the problems engendered in the attempts of securing such moisture directly so to the paper to humidify it. I have found that the objectsheretofore stated for my invention may be accomplished by applying moisture in a finely divided form to the ink in the press immediately prior to the time the ink is applied to the printing surface. It has formerly been thought quite impracticable, if not impossible, to secure a sufiicient amount of water in the form of moisture in the inks and to a sufiicient extent to supply the deficiency of moisture requisite for quality and efficient printing. It is a well known fact that there is a great variation in the kinds of ink used in prining and a great variance of opinion as to the proper consistency of inks even for employment in the same kind of job, but this much may be said, that sufficient ink must be applied to the printing surface to make it print properly. No matter the kind of paper or subject being used, and no matter the type or consistency of the ink being used, I have found that fine lustrous printing of a quality never before attained can be speedily and economically accomplished in the method of my invention which comprises the step of supplying moisture in the form of water in finely divided form to the ink immediately prior to its application to the printing plate or surface. It will be understood by those skilled in the printing art that, since in my improved method the primary function of the ink is to serve as a vehicle to transfer the moisture in finely divided form to the material to be printed upon, the method will be preferably employed with water-immiscible printing inks. By thus applying moisture to the ink, many things are accomplished, which will take it wholly out of the realm of anything in printing which has heretofore been commercially accomplished.

, Only the proper amount of moisture for fine printing is delivered to the paper, which entirely eliminates the dangers of too little moisture or of wetting. The paper itself, not being the vehicle for the moisture, is wholly unaffected until the time of the actual printing, thus eliminating the lessening of tension or the speed of operation, and, on the contrary, increasing the speed of operation as is described below. The moisture in the form of water carried by the ink to the subject or paper to be printed is absorbed first and is not in sumcient amount to open up the fibres through excessive swelling. Thus, the ink lies on the surface and does not penetrate to any appreciable degree the inner fibres of the paper or subject. It is the oil or varnish in ink which gives luster or sheen to the finish and, since these are not absorbed by the subject or paper but are laid on the surface thereof with the pigment, the result is brilliant live printing. In this connection it should also be said that the color tones as a consequence thereof remain true, and there is no fading or loss of value because of the penetration experienced in the ordinary method of printing. Since the ink itself lies nicely on the surface of the paper, not as much ink is required to print, and I have found by actual tests and experience that from 15% to 30% greater ink coverage is obtained by using my method of printing. This also means that less pressure is required to print, which combined, leads to.

greater speed of printing with practiaclly no offset. The reduction of ink required and the reduction of pressure required speeds up the hourly rate of the run to as high as in excess in actual commercial runs.

Where heavy inking is required in order to make the color hold and wherever heavier pressure is applied, there is always present a tendency in the finished product of showing light spots. This is due not solely to inaccuracies in the printing surface itself but to the well recognized fact that the paper itself, or the subject being printed, has

high and low spots. To compensate for this irregularity of printed surface, the conventional method is to use a great deal of pressure and more ink. By employing my method, such light spots are eliminated and the color held without increasing the amount of ink or the pressure involved. The moisture with the ink as a vehicle causes a slight expanding of the fibres of the paper or subject material, but not to an extent sufiicientto expand the fibres to a point where the ink will penetrate upon printing, so that the low spots are brought up and leveled off under the pressure of the impression cylinder.

Another remarkable advantage obtained by using my method of printing is the prevention of the filling up of the .middle tones. One of the most diflicult things in printing is to print solid colors evenly and have them remain even, after the printing is accomplished. By printing from plates whose surfaces are composed of small dots or from a surface which is solid, the ink with its moisture is so applied that all of the tiny dots print evenly without the present tendency of smudging Where the interstices between the dots fill up or light spots where the dots barely print at all and the solid surfaces print evenly and smoothly on the foundation of proper moisture. Much time and effort is directed to cooling the rollers carrying the ink during the printing process. I have found that there has been remarkable cooling effect by following the method of my invention. it will readily be seen that evaporation and the time of evaporation play an important part in this process. By supplying moisture in accordance with the disclosure made herein, 1 am able to eliminate to a large degree the idle time on a press by using my method, in that, by properly supplying moisture to the ink when the press is idle, the water will be evaporated. In the conventional printing inks, when the press is idle as frequently occurs in preparation for a run, the driers and oils in the inks evaporate, with the result that dried ink accumulates on the rollers and plates and has to be cleaned off before the press or run is started again. The time in which this phenomena occurs is materially increased due to the presence of moisture in the ink, allowing much more leeway in press manipulation without the frequent enforced idleness required to clean dried ink from the plates and the rollers.

Ihe described method of my invention of supplying moisture to the printing ink in finely divided form just prior to the time the printing ink is applied to the printing surface may be readily carried out by means of any suitable vaporizing or humidifying device which may be attached at any suitable point on the press such as the ink fountain, the ductor rollers, distributor rollers, or the ink bed, but preferably i. prefer to humidify the ink at the form rollers. While I have set forth certain portions of a press as exemplifications, it is understood that these are given for the purpose of illustration of the application of my invention in its aspects but are not to be taken in any sense as a limitation upon the scope of this method and invention.

Having thus described my invention and illustrated the method, what I claim as new and desire to secure by Letters Patent is:

i. In relief or letterpress printing the method of supplying moisture to material to be printed, comprising spraying the printing ink of an oil or grease base with water in finely divided form just prior to the time said printing ink is applied to a printing face.

2. In the relief or letterpress printing art employing inks non-miscible with water, the method of supplying moisture to material to be printed comprising continuously spraying one or more of the rollers of the inking mechanism with water in finely divided form during the printing operation.

3. In the relief or letterpress printing art employing inks non-miscible with water, the method of applying moisture to material to be printed comprising continuously spraying the form rollers of the inking mechanism with water in finely divided form during the printing operation.

4. In the relief or letterpress printing art employing inks non-miscible with water, the method 01' applyingmoisture to material to be printed comprising continuously spraying the distributor rollers of the inking mechanism with wa ter in finely divided form during the printing operation.

5. In the relief for letterpress printing art employing inks non-miscible with water, the method of applying moisture to material to be printed comprising continuously spraying the bed of the inking mechanism with water in finely divided form during the printing operation.

6. In letterpress or relief printing employing inks of an oil or varnish base, the method of printing whereby moisture is supplied to the printing ink in finely divided form Just prior to the time said printing ink is applied to the printing surface.

'7. In letterpress or relief printing employing inks non-miscible with water, the method of facilitating the transfer of ink to paper, which comprises coating the ink-covered printing surfaces with water in finely divided form by spraying one or more members of theinking train with water and impressing said water-coated ink directly upon the paper to be printed upon.

8, In letterpress printing using inks non-miscible with water, the method of preventing absorption of ink by the paper to be printed upon. which comprises spraying one or more members of the inking train with minute particles of water to coat the ink-covered printing surfaces with water in finely divided form, and impressing said water-coated ink directly upon said paper.

9. The method of letterpress printing which comprises coating the printing ink with a layer of water non-miscible with said ink, in finely divided form, Just prior to the time said printing ink is applied to the printing surface,