US1446947A - Process of drying lithographed metal plates - Google Patents

Description

Feb. 27, 1923. 1, 1Zef947. T. L. TALIAFERRO PROCESS OF DRYING LITHOGRAFHED METAL PLATES.

FILED APR. 7, 1920.

avwewboz Patented Feb. 27, 1%23.

entree stares p fi.

THOMAS L. TALiArEImo, or CHICAGO, ILLINOIS, essrsnoa 'rornonmx nn'nmn'rrc COMPANY, or cnroaeo, ILLIN lS, A CORPORATION or nEw YORK."

PROCESS OF DRYING LITHOGRAPHED METAL PLATES.

Application filed April 7, 1920. 4 Serial NO. 372,055.

' useful Improvements in Processes of Drying Lithographed Metal Plates, of which the following is a description, reference being had to the accompanying drawing and to" the figures of reference marked thereon.

The invention relates to a new and useful improvement in the process of drying litho graphed metal plates, and more particularly to metal plates such as are used in the {ginning of metal containers, covers, orthe An object of the invention is to provide a process of drying lithographed plates, whereby the plate may be quickly dried without any discoloration of the pigments of the lithographing ink.

A further Object of the invention isto pro.- vide a process whereby the drying. of the sheets may be efiected during the continuous travel of the sheets. 1

These and other Objects will in part be obvious'and will in part be hereinafter more described.

fullyl T e figure of the drawings shows more or.

less diagrammatically a rying oven..'for carrying out my improved process.

Prior to my invention, it has been -common to decorate metal sheets with ink by various lithographing processes, and then the sheets are dried. This drying of a lit'hographcd sheet has been accomplished by sub--- jecting the sheet tov a low heat fora considerable period of time, and this was thought necessary in order toprevent the discoloration of the pigments -.contained in the ink. It is well known that the drying of a'lithograph ink is not a volatilization' process, but,

on the contrary, is'a chemical actlomvthe ingredients oxidizing and thus bringing about a settingor drying of the ink. This oxidation process,whiol1 results in the drying of the ink is therefore a progressive or. cumulative actionf andgtlmeis' required in. order to-efiectthe same; I have discovered that a lithographed sheet of metal maybe heated to relatively high temperature so as toincr'ease'the rapidity of the chemical action, and the resulting drying of the; ink provided that .thisintense heat to which the ink is subjected, isrestricted to a veryshort the pigments.

tion described in detail in my interval of time. The discloration of the pigments due to heat, is not rapid, but Occurs only after the lithograph ink has been subjected to a relatively high temperature for a relatively long period of time; My improved process of drying lithographed plates consists therefore in the heating of the lithographed sheet to a comparatively high temperature so as to bring about a rapid oxidation of the ink and the resulting drying thereof and the restricting of the heatperiod withdrawn from the heating chamber and allowed to quickly cool.

Another Object of my process consists in the passing I of the sheets continuously through a heating chamber wherein the sheet will be quickly raised to the tempera ture referred to above, and the withdrawing of the sheet from the heatin chamber at the end. of the period referre to above, and preferably maintaining the sheets in vertical position while they are passing through said heatin chamber and for a period of time after t ey leave the'heating chamber.- This not only causes the sheet to be quickly heated, to a temperaturewhich brings about'the rapid oxidation of the ingredients of the ink, but it also quickly cools the 'sheetland thus preventsthe high temperature effects. upon the ink from causing discoloration-of .75 vided the sheet is at the end of the heating 1 In the drawings l have shown one-form) of apparatus for oarrying out the process, and brief reference will be made thereto. The drying Oven is indicated at l in the drawings and is preferably of the construc- Patent #1318487, granted October 7, 1919. Passin "through the Oven is an endless conveyor 2 iaving vertically extending arms 3 between which the. jsh'eets are placed. The,

"endless conveyor is driven in any suitable way and the: sheets are fed between'the arms by the feeding-in conveyor 4. I have indicated in the drawings the sheets at S.

The drying chamber is heated as shown in the drawings by gas burners 5 which are of such a character that the interior 'of the oven may be maintained at a temperature from two hundred and fifty to four hundred and fifty degrees. At the upper part of the chamber there is a longitudinally extending pipe 6 having openings, and air is supplied to this pipe and allowed to pass into the chamber. The amount of air thus delivered to the chamber is comparatively slight and is mainly for the purpose for causing a. movement of the air within the heating oven so as to bring about a uniform distribution. of the heat in-the oven thus avoidin hot spots and insuring uniformdrying 0% the sheets. At the receiving end of the oven there is a pipe 7 which is provided with openings, and this ipe is connected with a suitable supply of air which causes the blanket of air indicated by the lines 8 to be formed at the entrance of the oven. This blanket of air serves as a. door for closing the oven, so as-to maintain the heat in the oven. The sheets, however, will readily pass through the blanket. At the delivery end of the oven there is another pipe 9 which forms a blanket of air 10 for closing the delivery end of the oven. Throu h these air blankets, the oven is substantia y closed so that it may be maintained at a relatively high heat between two hundred and fifty and four hundred and fifty degrees throughout the entire extent ofthe oven. Through this arrangement, the lithographed sheet is subjected to this intense heat just as soon as it enters the oven and the intense heat continues until the sheet passes the blanket at the end of the oven out into the open atmosphere. Through the subjecting of the lithographed sheets to this high temperature, a very rapid oxidation of the ink takes place. The lengthof the oven and the speed of travel of the conveyor is such that the sheet will be from four to five minutes in passing. through the oven, and therefore,

the drying process which is brought about through the oxidation of'the ingredients of the ink will be substantially efl'ected when the sheet leaves the drying oven. By arranging the sheets vertically the surface of the ink is directly subjected to the circulating heated air in the oven, and is therefore more quickly brought to the maximum. temperature of the oven. On the othef-hand as soon as the sheets passout of the oven, the vertical arrangement thereof in the open atmosphere brings about a rapid cooling of the metal and the ink, this withdraws the heat from the metal sheet andthe ink and prevents the discoloration of the pigments which might result from the heat held in the metal if the metal was not rapidly cooled.

Through the process described above, it will be apparent that I am able to very quickly bring the lithographed ink to a teinperature where. the oxidation is ver rapid, maintain it for a short interval at t is temperature, and then quickly cool the same, and therefore the drying of the sheet is very much more quickly efi'ected, and without any injurious results, such as discoloration f the pigments.

The apparatus which has been described in brief above, forms no part broadly of the present invention, but is described and claimed in my Patent No. 1,399,415, granted Dec. 6, 1921. I

I have described the above apparatus for the purpose of makingmore clear the process.- It is obvious that the apparatus for carrying out the process may be widely varied. It is also obvious that the specified. temperatures, and the time interval to which the sheet .of metal is subjected to the temperature stated, may be variedwithin suitable ranges. the period of time stated are those preferred.

The temperatures and The 'essential feature of the invention consists however, in the heating of thesheet to a relatively highltemperature for producing rapid oxidation of the ingredients of the lithograph ink and restricting the period of heating so as .to prevent discoloration of the pigments, and this is greatly aided by the rapid cooling of the sheet-after the heat- 1 ing period. v

It is obvious that minor changes in the details of construction ma be made without departing fromthe spirit of theinvention as set forth in the appended claims. 1

, Having thus described the invention,what

I claim as new and desire to'secure by Letters-Patent, is':

1. The' process of treating lithographed plates consisting in' travelling the sheet through a drying oven heated to a relatively high temperature which would, if the operation be continued, carry the oxidization of the ingredients to a point ofdiscoloration of the pigments of the ink, and wherein the airis continuously moving so as to prevent hot spots and to produce a uniform rapid oxidization of the ingredients for drying the the end thereof so as to prevent discoloration of the pigments of the ink.

3. The process of drying lithographed plates consisting in travelling the lithographed sheets in succession through a drying oven heated to a temperature of two hundred and fifty to four hundred and fifty degrees, the speed of travel being such as to subject the sheets to the heat of the oven for a period of between four and five minutes and rapidly cooling the sheet after it leaves the oven.

4. The process of drying lithographed plates consisting in travelling the lithographed sheets in succession through a drying oven heated to a temperature of two hundred and fifty to four hundred and fifty degrees, the speed of travel being such as to subject the sheets to the heat of the oven for a period of between four and five minutes and rapidly cooling the sheet after it leaves the oven, and closing the receiving and delivering ends of the oven by a blanket of air and causing a circulation of the air within the oven so as to bring about a substantially uniform temperature from one end to the other of the oven.

5. The process of drying lithographed plates consisting in travelling the sheets in vertical position through a drying oven heated to a temperature between two hundred and fifty and four hundred and fifty degrees, regulating the speed of travel of the sheet so that each sheet will be retained in the oven from a period of four to five minutes, and maintaining the sheets in vertical position in the open air after leaving the oven until the sheets are cooled.

6. The process of drying lithographed plates consisting in travelling the sheets in vertical position through a drying oven heated to a temperature between two hundred and fiftyvand four hundred and fifty degrees, regulating the speed of travel of the sheet so that each sheet will be retained in the oven from a period of four to five minutes and maintaining the sheets in vertical position in the open air after leaving the oven until the sheets are cooled, closing the receiving and delivering ends of the oven by a blanket of air and circulating the air within the oven so as to maintain substantially a uniform temperature from one end to the other thereof.

In testimony whereof, I aflix my signature.

THOMAS LUCIEN TALIAFERRO.

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