US2194911A

US2194911A - Process of newsprinting

Info

Publication number: US2194911A
Application number: US185158A
Authority: US
Inventors: Philip K Porter
Original assignee: Interchemical Corp
Current assignee: Interchemical Corp
Priority date: 1938-01-15
Filing date: 1938-01-15
Publication date: 1940-03-26
Anticipated expiration: 1957-03-26
Also published as: GB523160A

Description

Patented Mar. 26, 1940 UNITED STATES 2,194,911 raoorss or NEwsramrmG Philip'K. Porter, Jackson Heights, N. Y., a'ssignor to Interchemical Corporation, New York, N. Y

a corporation of Ohio Application January 15, 1938, Serial No. 185,158

No Drawing.

6 Claims. (Cl. 101-416) This invention relates to the art of newsprinting and provides a method in which printing ink applied rapidly to porous paper is set or dried by controlled penetration.

In the extremely rapid printing required in printing newspapers, it is necessaryto rely on penetration of the inkvehicle into porous paper to set or dry the ink. The rapidity with which the ink must be transferred from'the printing 10 roller to the paper determines the viscosity of the ink which must be used and in general requires an ink of low viscosity. The penetration of the ink vehicle into the porous paperjwhich in general varies inversely to the viscosity, is entirely uncontrolled. Consequently, the initial penetration is sometimes insuflicient to dry the ink before the web is rolled up so that oifsetting occurs, and, in nearly all cases, the penetration continues for a considerable period both downwardly into the paper and outwardly from the printed letters, frequently causing the print to be visible on the back side of the sheet and making the print more or less fuzzy onthe front side.

My invention overcomes these difllculties by controlling the penetration of the ink into porous paper in newsprinting. In accordance with my invention, the viscosity of the ink on the print is varied so as to cause a rapid initial penetration followed by an arresting of the pene- 'tration: As a result, I obtain even more rapid 'drying than is customarily obtained by penetration in newsprinting, and at the same time avoid the disadvantages of fuzziness and striking through which result from too great penetration.

In carrying out my invention, a low viscosity printing ink, preferably containing a thermoplastic binder is applied to a highly porous paper of the type known as newsprint paper. The viscosity of the ink on the print is momentarily recosity which the ink reaches in the third step must be considerably higher than the viscosity which the ink has when applied to the paperin the first step. This result may be attained by cooling the print to a temperature considerably below the temperature at which the ink is applied to the paper, or more conveniently by evaporating a portion of the liquid in the ink vehicle durin the second step of the method, so that, on cooling the ink to its original temperature, it contains a larger'proportion of binder than it did originally, and is, therefore, more viscous. For this reason, it is desirable that the heat applied momentarily to cause the initial penetration be suflicient to cause evaporation of at least a 'minor I part Of the liquid in the ink.

duced by heat to cause rapid penetration, andinitial penetration will vary, depending on the speed of printing. For the highest printing speeds, of 1500-1800 feet per minute, a viscosity range of from two to eight poises at printing temperatures has been found desirable; while viscosities up to a limit of about 20 poises are satisfactory for the slower speed printing (800-1000 feet per minute) used in printing the typical colored newsprint.

Any ink may be used which prints in a satisfactory manner, and which becomes much more fluid when exposed to heat; for the preferred practice of my invention, the ink should 'lose some of its solvent during the heating operation.

Typical inks which are satisfactory include the following:

Viscosity, 3.8 poises at 30 C.

EXAMPLEII Parts by weight Carbon black 11.25 Gilsonite 12.5 Methyl violet toner 2.0 Induline toner 2.0

Ink oil (viscosity 100 seconds Saybolt at 100 c.) 62.25 Petroleum oil (boiling range 202-264 C.) 10.00

Viscosity, 3.9 poises at 30 C.

This ink, unlike the last, contains a very large percentage of ink oil which is non-volatile even at elevated temperatures. However, this ink oil has such slight solvent action on the resin that 1 comprises applying by conventional relief printafter the more volatile solvent is evaporated during the heating step, and the ink has cooled, the viscosity becomes very high and further penetration is blocked. Inks of this type may be used which only lose a very small percentage of solvent by evaporation.

Either of the above inks may be applied in a news press to a web of newsprint paper traveling at a speed of about 1,800 feet per minute.

Each portion of the printed web is momentarily heated to a temperature of about 400-450 F., to reduce the ink to a very thin consistency and cause it to penetrate rapidly into the porous paper. The heat also has the effect of-evapcrating a minor proportion (about 25%) of the liquid petroleum fraction in the ink. Such heating may conveniently be effected by passing the web as it leaves the printing roller through an oven 6 or 8 feet long, heated to a temperature of the order of 1000-2000 F., so that each part of the web is exposed to this temperature for about one quarter of a second.

Each portion of the web, after it has been heated, is cooled immediately to approximately room temperature (25 C. or less). This increases the viscosity of the ink well above its original viscosity and stops further penetration of the ink. The cooling may most conveniently be eflected by passing the web over a chilled metal roller immediately after it leaves the oven.

Other modes of carrying out the invention may obviously be used without departing from the spirit of my invention.

. What I claim is:

1. The improvement in newsprinting, which comprises applying a low viscosity press stable printing ink containing a thermo-plastic binder and a volatilizable liquid to a highly absorbent paper by conventional relief printing, momentarily heating the ink on the paper sufllciently to cause rapid absorption thereof into the paper, and to cause evaporation of a portion of the liquid, and thereafter coolin the evaporation of liquid being sufllcient to raise the viscosity of the ink sumciently after cooling so that further movement of the ink through the paper is substantially arrested.

2. The method of claim 1, in which the heat is sufficient to evaporate at -"least 25% of the liquid. v

3. The improvement in' newsprinting, which ing to a highly absorbent paper a low-viscosity press stable printing ink containing a thermoplastic resin dissolved in a mixture of a relatively non-volatile solvent of low solvency and a relatively volatile solvent of high solvency, momentarily applying sufllcient heat to the ink on the paper to reduce its viscosity and cause it to penetrate rapidly, and to evaporate solvent of high solvency, and thereafter cooling the ink, the evaporation of high solvency liquid being sufficient to raise the viscosity of the ink sufficiently so that after cooling further movement of the ink through the paper is substantially arrested.

4. The improvement in newsprinting which comprises applying, by conventional relief printing, a press-stable ink containing a volatilizable solvent and having a. viscosity of from 2 to 8 poises at printing temperature to a web of highly absorbent paper travelling at a speed of at least 1500 feet per minute, heating the web after printing by exposing each portion thereof to a temperature of the order of 1000 to 2000 F. for a fraction of a second, whereby the ink is absorbed into the paper and a portion of the solvent is evaporated, and immediately cooling the web, whereby the viscosity of the ink is increased sumciently to substantially arrest further movement of the ink through the paper.

5. The improvement in newsprinting, which comprises applying, by conventional relief printing, a press-stable ink containing a volatilizable solvent and having a viscosity of from 2 to 20 poises at printing temperature to a web of highly absorbent paper travelling at a speed of at least 800 feet penminute, heating the web after printing by exposing each portion thereof to a temperature of the order of 1000 to 2000 F. for a fraction of a second,'whereby the ink is absorbed into the paper and a portion of the solvent is evaporated, and immediately cooling the web. whereby the viscosity of the ink is increased sufficiently to substantially arrest further movement of the ink through the paper.

6. The method of printing which comprises applying a low viscosity press stable printing ink to a highly absorbent paper by conventional relief printing, momentarily heating the applied ink sumciently to cause rapid absorption thereof into the paper and to so change the ink that its viscosity at ordinary room temperature is so increased that on cooling further movement of the ink through the paper is substantially arrested,

and thereafter cooling the paper.

PHILIP K. PORTER.