US2261798A - Printing - Google Patents

Description

Nov. 4, 1941. D. R. ERICKSON ET AL PRINTING Filed NOV. 22, 1939 m 6 my@ nl TQL-; www l w. @m7 3x x W/q. L M Q MPM N i QN &\\\| S j w N N NW l Q w L ATTORNEY5.

Patented Nov. 4, 1941 2,261,798 rnnv'rmG Donald Robert Erickson and Paul J. Thoma,

Kalamazoo, Mich., assignors to Michigan Research Laboratories, Inc., Kalamazoo, Mich.

Application November 22, 1939, Serial No. 305,641

(Cl. lol-416) 4 Claims.

This invention relates to printing and has for p its objects:

First, to produce a new and improved method of printing and preventing oiset.

Second, to produce such a method in which an ink, comprising varnish made up of a binder insoluble in water and capable under the circumstances herein set forth of forming a thin hard film, and a solvent therefor miscible with water, is printed on paper or the like, after which the printed lm of ink is immediately subjected to the action of steam to form from the binder of varnish employed in the ink a thin hard film of binder completely overlying the exposed surfaces of the printed film so that offset is elim.- inated when the printed matter is stacked or rewound.

Third, to produce a method in which offset is prevented by forming from a substance in the ink a thin hard lm over the printed film of ink, leaving a major portion of the printed lm ofink unaffected so that it may dry by penetration to secure a satisfactory hond to the paper or the like on which it is printed.

Fourth, to produce a new and improved article of manufacture comprising a sheet of paper or the like having an ink film with an overlying thin hard lm of binder from the ink.

Objects relating to details and economies of the invention will appear from the detailed description to follow. The invention is dened in the claims.

In the drawing we show apparatus suitable for carrying out our new and improved method, in which:

Fig. 1 is a side elevation, partly in section, of such an apparatus.

Fig. 2 is a detail sectional view taken on line 2 2 of Fie'. 1.

Fig. 3 is a detail perspective view, partly in section, showing the arrangement for applying steam to the printed matter.

Incarrying out our new and improved process, We make use of standard printing press equipment. A film is printed on a sheet or web of paper or the like with an ink comprising a varnish made up of a binder which is insoluble in water and a solvent therefor which is miscible with water. The binder must be capable of forming a thin hard film on the surface of the printed sheet or web of paper when a printed nlm of ink is subjected to the action of steam.

A suitable ink may be made using shellac as the binder and diethylene glycol as the solvent.

binder a resin comprising a rosin modied with an alpha beta unsaturated organic poly basic acid, such as maleic acid or fumaric acid, as described in Patent No. 2,063,542, issued December 8, 1936, to Carleton Ellis, for Diene resin, with diethylene glycol as a solvent. The last mentioned ink with the resin binder diiers from the first mentioned ink in that the binder is soluble in the solvent with a limited quantity of water but is not soluble in the solvent with an unlimited quantity of water added. This is a desirable feature because the ink has a Water tolerance such that pressroom humidities, which may be as high as 80 per cent. relative humidity when the steam is employed, will not cause the binder and solvent to separate on the press.

Immediately after printing a film of suitable ink on the paper, the water content of the binder solvent of the surface of the printed film is increased to a point to render the mixture of binder solvent and water incapable of retaining the binder of the surface of film in solution. This causes a thin hard lm. of the binder to be formed over the exposed portions of the printed lm. The underlying portions of the film remain in the state in which they were applied to the paper, so that the ink may dry by penetration. The thin hard film over the exposed surfaces of the printed lm prevents offset when the paper is stacked in sheets or rewound in the web.

ing the printed iilm to the action of steam to thin film of binder on the printed film the paper increase the water content of the surface of the printed lm to cause the thin film. of binder to form. The water content of the steam should f be such that in the time required to form the will not be affected. The water content must be low enough to prevent the surface fibers from separating from the sheet or to increase the water content of the paper materially beyond its content at the time of printing so as to cause the paper to change its dimensions because of the increased water content. The steam must not be at high enough temperature and dry enough to cause the paper to lose any material amount of its moisture during treatment.

We have .found that satisfactory results may be obtained with the apparatus shown in the drawing. In the drawing we show a conventional printing press l from which a web of paper or the Another suitable ink may be made using as a like 2 passes after printing. The printed matter consists of a nlm of ink. The web2 then passes to our steam apparatus 2 which consists of a chamber 4 having its end walls l and side walls l of Celotex or the like. The end walls are apertured' at 1 to permit the web of paper to pass therethrough. The upper surface of the web on which the nlm of ink is printed passes directly under the .steam applying apparatus 8, which consists of a pipe 2 extending transversely between the side walls 6 of the chamber. Equally spaced from the center line of the bottom of the pipe are a series of apertures I Il spaced approximately 120 degrees apart. Below the pipe 8 is provided a metal trough I I having a flannel cover I2 extending around the bottom thereof to prevent condensed moisture from dripping onto Ithe web 2 as it passes through the chamber. The flannel is laced in position by suitable lacing Il.

Steam is fed from a supply line I4 to a separator or drier I5 which is provided with a trap I6 and an outlet pipe I1 for moisture removed from the steam. From the separator the steam passes through pipe I8 to the pipe 8, which is provided with an outlet valve I9. Valves 20, 2l and 22 control the passage of steam to the jets.

With this apparatus the pipe 9 is located approximately 6 inches above the printed surface of the web 2 and the steam is directed downwardly against the surface of the web as the webv passes through the chamber 4. We supply steam of approximately 95 per cent. quality to the pipe 9 and the steam as it reaches the surface of the paper does not have any appreciable condensed water therein. The top of the chamber 4 is closed "by a top 23 of flannel. After the web 2 passes from the chamber 4 it passes to a. suitable die cutting apparatus, indicated conventionally at 24 live have found that our process is highly satisfactory for printing cartons or the like where it is essential to have speed and register. It is y also satisfactory for printing bread wrappers. It eliminates offset without causing shrinkage of the paper on which the film of ink is printed. This permits the cutting dies, if cartons or the like are being made, to cut the printed web to desired form without losing register. In the case of bread wrappers the paper may be rewound immediately. 'Ihe finished product is highly satisfactory because the ink is adequately bonded to the sheet of paper by penetration and will not flake off. There is no offset. The Eimen dorf test is improved.

In using this apparatus the temperature of the steam and its water content, when it reaches the paper, are such that the water content of thex Paper is not materially disturbed. The steam is dry enough so that it does not add water to the paper and is moist enough so that it does not remove water. The steam is approximately at atmospheric pressure and 100 degrees centlgrade.

We have found that with the above apparatusthe steam reaching the paper is not hot-or dry enough to cause shrinkage of the paper. It is not too wet to cause expansion of the paper and a raising of the ribes on the surface of the paper.

It will be apparent that some differences in condltions will be required for different papers but those skilled in the art will be able to control the steam to avoid deleteriously affecting the papel* The terms and expressions which have been employed herein 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 rating together a water insoluble pigment, a

water soluble vehicle and a water insoluble binder soluble in said vehicle and in said vehicle and a limited quantity of water such as would be encountered in ink on a press at 80% relative humidity and having -the property of being separable from said vehicle by the addition of water to a solution of said binder in said vehicle and in said limited quantity of water and, when dissolved in said vehicle to form a varnish, of separating from a mass of the varnish to form a thin hard water impenetrable skin on the surface onlylof said mass when the water content of the vsurface of said mass is raised to a point at which the binder separates from the vehicle. printing a sheet of paper or the like with said ink, and immediately thereafter raising the water content ofthe vehicle of the exposed surface only of said printed ink to an amount to render the vehicle incapable of retaining said binder in solution by subjecting the printed ink to a quantity of steam sufncient to raise the water content of the vehicle at the surface of said printed ink to render said vehicle incapable of retaining the binder at said surface in solution.

2. The process of producing an anti-smudging imprint comprising forming an ink by incorporating together a water insoluble pigment, a water soluble vehicle and a water insoluble binder soluble in said vehicle and in said vehicle and a limited quantity of water such as would be encountered in ink on a press at relative humidity and having the property of being separable from said vehicle by the addition of water to a solution of said binder in said vehicle and in said limited quantity of water and, when dissolved in said vehicle to form a varnish, of separating from a mass ofthe varnish to form a thin hard water impenetrable skin on the surface only of said mass when the water content of the surface of said mass is raised to the point at which the binder separa-tes from the vehicle, printing a sheet of paper or the like with said ink. and immediately thereafter raising the water content of the vehicle of the exped surface only of said printed ink to an amount to render the vehicle incapable of retaining said binder in solution by adding 4water thereto to raise the water content of the :vehicle at the surface of said printed ink to render saidv vehicle incapable of retaining the binder at said surface in solution.

3. The process of producing an anti-smudging imprint comprising forming an ink by incorporating together a water insoluble pigment, a water soluble vehicle and a water insoluble binder soluble in said vehicle and having the property when in solution in said vehicle of being separable from said vehicle by the addition of water to said solution, when dissolved in said vehicle to form a varnish, of separating from a mass of the varnish to form a thin hard water impenetrable skin on the surface only of said mass when the surface of said mass is exposed to water to raise the water content at the surface of themass to the point at which which the binder separates from the vehicle, printing a sheet of paper or the like with said ink, and immediately thereafter raising the water content of the vehicle of the exposed surface only of said printed ink to an amount to render the vehicle incapable of retaining said binder in solution by subjecting the printed ink to a quantity of steam sufiicient to raise the water content of the vehicle at the 'surface of said printed ink to render said Vehicle incapable of retaining the binder at said surface in solution.

4. The process of producing an anti-smudging imprint comprising forming an ink by incorporating together a water insoluble pigment, a water soluble vehicle and a water insoluble binder soluble in said vehicle and having the property when in solution in said vehicle of being separable from said vehicle by the addition of water to said solution, when dissolved in said vehicle to form a varnish, of separating from a mass of the varnish to form a thin hard water impenetrable skin on the surface only of said mass when the surface of said mass is exposed to Water to raise the water content at the 'surface oi the mass to the point at which the binder separates from the vehicle, printing a sheet of paper or the like with said ink, and immediately thereafter raising the water content of the vehicle of the exposed surface only of said printed ink to an amount to render the vehicle incapable of retaining said binder in solution by adding water thereto to raise the water content of the vehicle at the surface of said printed ink to render said vehicle incapable of retaining the binder at said surface in solution. y

DONALD ROBERT ERICKSON. PAUL J. THOMA.

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