US2157388A - Method of printing and setting a printing ink - Google Patents

Description

M y 9, 1939- c. J. M ARTHUR 2,157,388

METHOD OF PRINTING AND SETTING A PRINTING INK Filed Jan. 22, 1957 INVENTQR R M KMCQUIL BYqz ATTORNEY Patented May 9, 1939 UNIT STATES PATENT". OFFlCE METHOD OF PRINTING AND SETTING A.

PRINTING INK Charles J. MacArthur, Glen Ridge, N. 1., assignor to Interchemical Corporation, a corporation of Ohio Application January 22, '1937, Serial No. 121,833

10 Claims. (Cl. 1014l6.1)

volatile at room temperature, so that the ink does not dry on the press. In many cases, the

coloring matter of the ink used in the method is soluble in the solvent. After the printing operation, the solvent is evaporated at a high temperature, ordinarily above 400 C., in order to set the ink and convert it to a dry, non-smudging' condition.

Even with the use of such high temperatures, it has sometimes been found'that the ink was not entirely dry after the printed material cooled. The reason for this imperfection was not at once apparent, but after considerable research, it was discovered that the less than complete dryness of the ink was due to condensation of the high-boiling solvent in the presence of the ink solids on the printed material. If the solvent vapors be withdrawn from the presence of the printed material before it cools, then undesired condensation is avoided, but this is diflicult to accomplish, par.- ticularly in the case of a rapidly traveling web, due, perhaps, to a tendency of the web to sweep along with it those vapors which lie closely adjacent its surface.

I have found that resoftening of the ink can be avoided by applying to the printed material, preferably immediately after the heating, and before the web cools, a thin, non-viscous moistening fluid, which is miscible with the solvent of the ink. When the solvent of the ink is miscible with water, I prefer to employ water as petroleum fractions, which are employed in inks of the type mentioned, are somewhat viscous or have poor aflinity for paper, and do not readily penetrate paper or similar materials, even though these materials are porous to some extent. Ac-

cordingly when the solvents condense on the surface of the paper, they tend to betaken up by the ink solids, rather than by the paper. When a small amount of water, or other non-viscous moistening fluid, iaapplied to the paper, or other porous material, it penetrates the same, and the condensing or residual solvents are attracted to the mo'istening fluid, with which they are miscible, rather than to the solid particles of the ink. Moreover, when the solvents mix with water, or other moistening fluid which is a nonsolvent for the binder and. coloring matter, they are diluted, and their solvent power for the binder and coloring matter is thus reduced. Therefore, instead of the solvents resoftening the ink, they appear to be spread through the surrounding material, and what little of them remains in close proximity to the ink solids is so dilute as to have no deterious softening action. Thedesired result may be fostered by blowing a jet of moist-air against the unprinted side of the printed material, just after it passes beyond the heating stage.

Moisture, in the form of a gaseous fluid, such as that contained in warm, moist air and steam, is distributed uniformally throughout the printed material and over any intermediate surface used to assist in its application. In such form it readily penetrates the interstices and films of printed material and thereby increases proper distribution of the liquid to act in the manner described for improving the quality of the printed material and drying the ink. Quick, as well as thorough distribution is important in the quickdrying processes referred to. Upon cooling, according to my invention, the moisture condenses within the paper and functions as described.

Other features, objects and advantages of the present invention will in part be pointed out and in part become apparent in connection with the following detailed description of one illustrative r side elevation, partly in section.

Referring to the drawing, a web of paper 5 passes through a rotary printing press, including a plate cylinder 6 and impression cylinder I, and then passes directly into a furnace 9, over a guide roll 4 and through a slit H in the furnace wall. The furnace is provided with suitable burners l0, arranged to direct their flames toward or against the printed face of the web 5, and includes a hood 8 arranged so the a portion of a chilled roll l2 projects within the discharge end of the furnace.- Roll I2 is mounted on a positively driven shaft I3 and may be chilled by circulating brine through the interior thereof.

Provision is made for withdrawing most of the solvent vapor from the furnace I. This may be accomplished to advantage by providing a pipe H. one end of which opens into the top of the furnace at It, and the other end of which opens into a suitable receptacle i1, after passing through a heat exchanger it. In order to apply moisture to the web, there is provided a blower 20 for forcing moist air through heat exchanger II and thence against the surface of chilled roll i2, preferably at a point just ahead of the point where the chilled roll contacts the hot printed web. When the moisture-laden air strikes the surface of the chilled roll, the moisture condenses on the roll and is thus brought into contact with the rear face of the porous web. by which it is absorbed. The uncondensed moisture-laden air penetrates into the films of the paper and is condensed within the paper when it contacts the chilled roll. The moisture-laden air is cool compared to the hot gases in pipe I4, and thus tends, by heat exchange, to cool the gases and thus condense the solvent vapors therein. This condensation results in withdrawing more vapors from the furnace. At thesame time, the moisture-laden air is heated. A jet of air may be blown toward the printed face of the web, at a point and in a direction adapted to blow solvent vapor away from the web, and preferably opposite to the direction in which the web is traveling. For this purpose, any suitable blower 23 and nozzle 22 may be employed.

The roll I! is driven so as to draw the printed web forward at the same speed at which it passes through the printing press, and maintains the web taut, so that the web presses against the surface of the chilled roll. The printed web passes around a portion of the circumference of the drum l2, and thence over tension roller 24, to rewind roll 25.

It. will be appreciated that the temperatures developed by the burners It depends somewhat upon the amount of solvent employed in the ink, and upon the boiling point of the solvent. A temperature of about 450 C. is ample for most conditions. The temperature of the chilling roll it will depend upon the temperature in the furnace 9, the circumference of the chilling roll and the extent of contact between the printed web and this roll, but ordinarily a temperature in the order of 30 F. is satisfactory. By applying the moistening fluid while the printed web is still subject to the direct heat of the furnace, the adsorption of moisture by the web is promoted, and it is only necessary to employ a minute amount of moisture, such as is readily condensed on a chilled roll, as described.

While the invention is not restricted to the particular ink employed, the ink may comprise, for example, 25 parts of pigment, 17 parts of a binder, such as nitrocellulose or a resin, and 58 parts of a solvent such as butyl carbitol acetate, by weight.

Although I have described the theory of my invention in some detail, its operation and usefulness are not restricted by the particular theory expressed. For instance, the addition of moisture to the printed web is advantageous irrespective of the reason for the presence of solvent on the sheet after the heating operation, particularly when extremely high temperatures of more than 4 0 C. exist in the heating chamber. Furthermore, while the invention is particularly adaptedto web printing, the method is also applicable to printing on separate sheets. Other moistening fluids, such as alcohol, may be employed in case the solvent used is not miscible with water. While the primary purpose accomplishedis the setting of the ink to a substantially dry, nonsmudging condition, in a rapid and convenient manner, an incidental advantage of the invention lies in reconditioning the printed material by supplying moisture to it in order to make up for any moisture which has been evaporated during the heating.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described, or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What I claim is:

1. Method of setting a printing ink and the like containing a binder and a solvent, which comprises heating the ink on the printed material to remove solvent therefrom, and applying to the 'printed material a moistening fluid which is miscible with said solvent and which is a nonsolvent for the binder.

2. Method of setting a printing ink containing a binder and a solvent, which comprises heating the ink on the printed material to remove solvent therefrom, moistening the printed material with a liquid which is misciple with, and less viscous than, said solvent, and which is a nonsolvent for the binder, and cooling said moistened material.

3. Method of setting a printing ink containing a binder and a solvent and applied to porous material, which comprises heating the ink on said material to remove solvent therefrom, and applying a moistening fluid, which is miscible with the solvent, and which is a non-solvent for the binder, to the unprinted face of. the porous material.

4. Method of setting a printing ink containing a binder and a solvent and applied to porous material, which comprises heating the ink on said material to remove solvent therefrom, applying a moistening fluid which is miscible with the solvent, and which is a non-solvent for the binder, to the unprinted face of the porous material, and cooling the moistened material.

5. Method of setting a printing ink containing a binder and a solvent and applied to porous material, which comprises heating the ink on said material to remove solvent therefrom, applying moisture in gaseous form to the porous material, said moisture being a non-solvent for the binder, and cooling the moistened material.

6. Method of setting a printing ink containing a binder and a solvent and applied to porous material, which comprises heating the ink on said material to remove solvent therefrom, applying moisture in gaseous form to the interstices and film of the porous material, said moisture being a non-solvent for the binder, and cooling the moistened material.

'7. Method of setting a printing ink containing a binder and a solvent and applied to porous material, which comprises heating the ink on said material to remove solvent therefrom, applying moisture in gaseous form to the porous material from the unprinted side thereof, said moisture being a non-solvent for the binder, and cooling the moistened material.

8. Method of setting a printing ink containing a binder and a solvent, which comprises heating the ink on the printed material to remove solvent 2,1 szsse therefrom, and applying to the printed material, while warm', in moistening fluid which is miscible with said solvent and which is a non-solvent for the binder.

9. Method of setting a printing ink containing a binder and a solvent, which comprises heating the ink to remove solvent therefrom, applying to the printed material while warm a molstening fluid, which is miscible with the solvent and 10 which is a non-solvent-for the binder, and cooling the printed material.

f0. Method of setting a printing ink containing a binder and a solvent, which comprises heating the ink on the printed material to remove solvent therefrom, applying to the printed material a moistening fluid which is miscible with said solvent and which is a non-solvent for the binder, and directing a jet of air against the inked face of theprintedmaterial in a direction adapted to blow solvent vapors away from the printed face of the material.

CHARLES J. MACARTHUR.

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