US2320769A - Duplication process and master sheet for use therein - Google Patents

Description

W. J. CHAMPION June 1, 1943.

DUFLICATION PROCESS AND MASTER SHEET FOR USE THEREIN Filed NOV. 17, 1941 QHTEAM TEEN-18 jw i W Patented June 1, 1943 s V 2,320,169 I normcA'no rnooass AND MAs'rEn SHEET non use 'rnnnnm William 5. Champion, Ghicago, Ilit, ass'ignorto- Ditto, Incorporated, Chicago, lit, a corporation or West Virginia Application November 117, Nah- Serial No. erases 10 Claims. (Cl. ion-mas) This invention relates to solvent" process duplication. and more specifically to a solvent process duplication in which solvent is applied to the design surface of the master copy and need not be applied atall to the copy sheet. The invention includes master sheets adapted for use in the process.

Solvent process duplication generally is char acterized by the steps of contacting a master de sign containing a dyestufl with a succession of copy sheets pre-moistened with a substantially volatile solvent for this dye. of the dye in the master design is dissolved by the solvent and transferred to each of the successive copy sheets so as to give copies of the master design. D

While this process is very convenient and has met with commercial success, it has several disadvantages:

1. It is necessary to moisten with solvent the entire area of the copy sheet. Actually, this sol vent is used only on those small portions of the copy sheets which contact the actual dye design on the master. The rest of the solvent performs no function. This waste may amount to as much as 98% and almost invariably exceeds 80% of,

the total liquid consumed.

2. Under conditions not favoring rapid evaporation of the solvent, an excessive amount of solvent is easily retained in the copy paper, causing continuous difiusion or blurring and "strik- 4. The use of volatile solvents represents a 40 definite fire hazardfparticularly in electricallydriven machines.

5. The use of solvent in contact with the various metals in the machine results in progressive corrosion and consequent service and replacement problems.

6. The mechanism required for supplying and regulating the solvent flow is quite complex and expensive.

In some instances solventhas been applied to the under surface of a master sheet instead of to thecopy sheets. This method has the same disadvantage outlined above and in addition fur ther disadvantages including the necessity for.

On contact some complicated mechanism for applying the solvent to the under surface of the master sheet.

tirely satisfactory.

The present invention obviates the above disadvantages of the prior art.

10 According to this invention, the solvent is applied directly to the design surface of the master, which has been treated so that only the dyecarrying parts thereof are receptive to the solvent, and so that the dissolved dye cannot spread or difiuse to parts of the master sheet adjacent the design.

This pre-treatment of the master may be accomplished by applying to the master a fluid which is non-miscible with the said solvent.

To illustrate, the process is hereafter described step by step, reference being made to the accom= panying drawing of which Fig. 1 represents a master sheet, and Fig. 2 a sectional view of a duplication machine on which the invention is hee practiced.

. A dye-carrying design in mirror reverse is produced on a carrier sheet, for example, by drawing directly or by typing'with a typewriter having special reversed type on the keys, or preferable by writing or printing on a sheet the back side of which is adjacent to a dye-carrying transfer sheet. The carrier sheet to which the master design is applied is preferably a paper sheet, but may also be a thin metal sheet having a sand- 5 blasted or similarly roughened surface, a similar plastic sheet or the like.

The nature of the carrier sheet and of the dyecarrying design, and the way in which these have been obtained, prepared or produced, are unimportant so long as the carrier sheet is adapted to retain the solvent repellent further discussed below and to retain the design; and so long as the design is adapted to give colored impressions or copies when acted upon with a dye 5 solvent and contacted with a succession of copy sheets.

The master is then treated to make all nondye-carrying parts thereof repellent to the dye solvent employed in subsequent steps of the process, as detailed below. This treatment includes application to the master of a liquid which is substantially non-miscible with the said dye solvent, and also a non-solvent for the dyestufi of the master design. The mode of supplying this as liquid is non-essential. It-may be depositedby wiping the master with an applicator moistened in the repellent, or by contacting the master with repellent-carrying moistening means such as rollers, wicks or the like, either on the duplicating machines or in a separate operation.

Referring now to the attached sketch, the master 6 which has been moistened with the repeller,

is fastened to master holding meansd on the .revolvable drum 2. As the drum is caused to rotate by means well known to; the art and not shown in the sketch, the master contacts the solvent-applying roller 3. This roller carries the dye solvent and applies this in a very thincontacts a copy sheet 'I which is being fed between the drum and a lower pressure roller 4 by means known to the art (not shown). On contact, a sufiicient amount of dye is transferred from the master to produce a copy on the copy sheet. m I

This cycle is repeated and copies thus produced until the dye on the master is exhausted. The number of copies obtained depends on the selection of ingredients for the dye-carrying design, the porosity of this design, the composition of the solvent, the quantity of solvent applied, the composition and absorbency of the master sheet and of the copy sheets, and on the pressure between master and copy sheets at the moment of transfer.

Generally, any change tending to increase the amount of dye transferred to eacn copy sheet will enhance copy brightness and reduce the number of copies obtainable, and vice versa. Most conveniently, the copy brightness and length of run can be selected at will by varying the amount of solvent applied to the master sheet.

The solvent may be furnished by almostany type of mechanism adapted to apply a uniform film of liquid to a moving surface. I prefer to effect this transfer of liquid from a surface traveling at the same rate of speed as that of the master. Therefore, a roller driven by friction with the drum and the master or positively driven to have the same peripheral speed, is a preferred mode of applying the liquid. However, usable results may be obtained also with wick type applicators or the like, although the drag or friction tends to accelerate deterioration or breaking down of the master design. The pressure between the various members of the solvent applying and distributing mechanism, and between this and the master, should preferably be adjustable.

In an embodiment not shown in the drawing, the solvent applying roller receives the solvent from a felt roller 5 which in turn is partly immersed in a reservoir containing the solvent but in the particular embodiment shown in the drawing the solvent applying roller 3 is itself partly immersed in the solvent.

Obviously, the solvent may be brought to the surface of the applying roller by a great number of means or devices, including wicks, gravity feed, atomizers or spraying devices, and the numerous types of means used in the printing invention is not limited to any particular genera or species of these means.

\ V The solvent may be any liquid or semi-liquid composition which is a solvent or plasticlur for the particular dy'e contained inthe master design. For example, if thedye is a water or spirit soluble dyestuff, such as a Fuchsin, Eosin, Auramin, Rhodamin, methyl or crystal violet, methylene blue, a metamine dye, Victoria green, or the like, then polyhydric liquid dye solvent alcohols such as 2 methyl 2,4 pentane diol are preferred solvents, and nitrat d oxygen containing liquid dye solvent hydrocarbon derivatives such as 2 nitro 1 butanol,.dye solvent liquid amide such as formamid, esters such as ethyl lactate, and glycol derivatives dye solvents such as diethylene glycol mono ethyl ether and the like, and their mixtures are suitable assoligtsi If, for. example, an oil soluble dye is us d in the master design, then I may use hydrocarbon type solvents such as light mineral oils, preferably high boiling solvent naphthas or the like. Generally oil miscible solvents are suitable for use in conjunction with this type of dye. I prefer to employ solvents which are substantially odorless, have a low volatility, and are adapted to dissolve or plasticize the dye in the master design, although obviously the odor does not influence copy results, and volatile solvents may be used, if the speed of rotation of the drum or the design of the machine is such as to keep the rate of evaporation within economically practical limits.

As the repellent, Imay use any composition which is readily imbibed or retained in the nondye,carrying portions of the master sheet, and which is substantially non-miscible with the dyesolvent and is a non-solvent for the dye.

For example, in conjunction with the water or spirit soluble dyes and solvents enumerated above, I prefer to use as repellent a water solution of an electrolyte, such as a solution of calcium chloride, ammonium sulfate, barium'nitrate, lead acetate, sodium lactate, and the like, in

-high enough concentration to reduce the solvency of the water for the other materials mentioned above. a

In conjunction with oil soluble dyes and hydrocarbon-type solvents, I may use as the repellent water, glycols, glycerines, solutions of electrolytes or of gums, starches or glues and the like in water.

Shortly, I may use as repellent any liquid composition which can be retained by themaster sheet, and is non-miscible with the solvent and a non-solvent for the dye used. To illustrate, the following specific examples are given:

Example I A master was prepared by typing with a hectograph ribbon of prior art onto a paper sheet. Copies ere taken in the device shown in the sketch, using as the solvent 2 methyl 2,4 pentane diol, as the repellent a 10% solution of calcium chloride, and as copy sheets an absorbent sulflte sheet known as Ditto direct process B."

Eal'ample II A master was prepared by the procedure disclosed in Figure l and Example 1 of U. S. Patent No. 2,254,483 to Hess and Bjorksten. Copies were taken in the device shown in the sketch, using as a solvent a mixture of 2 parts by weight of 2 nitro l butanol and one part of Carbitol, as repellent a saturated solution of ammonium sulfate, and as copy sheet a sulfite sheet known as "Longrun B."

' Example III A master was prepared by typing through an enamel type coated paper sheet against a conventional direct process type duplication transfer paper. Copies were taken in the device shown in the sketch using a 7% solution of sodium silicate as the repellent, formamid as the solvent, and a sulfite sheet known as Longrun E" as the copy paper.

Example IV A master was prepared by typing through a super-calendered cofiee bag paper against a duplication transfer paper comprising as the active dye ingredient the stearate of methyl violet. Copies were taken in the device shown in the sketch, using high flash solvent naphtha as the solvent, a 2% solution in water of gum arabic as the repellent, and a sulflte sheet known as "Direct process D as the copy paper.

Obviously these examples are given only to show, by concrete instances, certain modes in which the invention can be applied. They are not to be construed in any sense of limitation as I realize fully that the ingredien rocedures and devices can be varied within wide limits without departure from the spirit or scope of this invention.

The term "relatively non-volatile solvent" is used in the specification and claims to refer to solvents in which the major part of the solvent has less volatility than ethyl alcohol.

I claim:

1. The method of duplicating which comprises applying to the non-design portions of a master having thereon a design of a soluble dye a coating which is substantially non-absorbent of a carrying the design, and thereafter contacting said surface with a copy sheet.

3. The method of duplicating which comprises applying an aqueous solution of an electrolyte to a master sheet having a design thereon of a soluble dye, applying a solvent to the design surface, and thereafter contacting said surface with a copy sheet.

4. The method of duplicating which comprises applying an aqueous solution of an electrolyte to a master sheet having a design thereon of an alcohol soluble dye, applying a glycol type solvent to the design surface, and thereafter contacting said surface with a copy sheet.

5. The method of duplicating which comprises applying an oil repellent liquid to a master sheet having a design thereon of an oil soluble dye, applying a solvent for said oil dye to the design surface, and thereafter contacting said surface with a copy sheet. r

6. In the method of duplicating wherein a solvent is applied to a master copy sheet having a design thereon of a soluble dye, the step of pre-treating said master copy sheet by applying thereto a liquid which is substantially nonmiscible with said dye solvent and a non-solvent for the dyestufl of the master design.

7. In the method of duplicating Wm solvent is appll'ed to a master copy sheet having a design thereon of a soluble dye, the steps which comprise applying a fluid to the master copy sheet which is substantially non-miscible with said solvent and a non-solvent for the dyestufl of the master design, and then applying as the said solvent a relatively non-volatile solvent to said design surface.

8. A master sheet adapted for liquid process duplication, said master comprising a sheet having a design thereon of a soluble-dye, the

non-design portions carrying a fluid which is substantially a non-solvent for the dye of said design, and non-miscible with asolvent for the dye of said design.

9. A master sheet comprising a sheet having a design thereon of a soluble dye, the non-design portions of the sheet containing a solution of an electrolyte.

' 10. A master sheet comprising a sheet having a design thereon of a water and alcohol soluble dye, the non-design portions of the sheet containing a solution of an electrolyte.

WILLIAM J. CHAMPION.

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