US2970931A

US2970931A - Stencil sheet having transferable back coating

Info

Publication number: US2970931A
Authority: US
Inventors: Gumbinner Robert
Original assignee: Polychrome Corp
Current assignee: Polychrome Corp
Priority date: 1957-03-25
Filing date: 1957-03-25
Publication date: 1961-02-07
Anticipated expiration: 1978-02-07

Description

Feb. 7, 1961 R. GUMBINNER 2,970,931

STENCIL SHEET HAVING TRANSFERABLE BACK COATING Filed March 25, 1957 INVENTOR. faas'er y/va/xy/v'f BY W K United States PatentO i STENCIL SHEET HAVING TRANSFERABLE BACK COATING Robert Gumbinner, Tarrytown,

chrome Corporation, New York Filed Mar. 25, 1957, Ser. No. 648,250

3 Claims. (Cl. 117-355) N.Y., assignor to Poly- Yonkers, N.Y., a corporation of ing ink may flow.

It is known to assemble such stencil sheets by adhesively securing one marginal edge thereof to a carbon cushion sheet and to a backing sheet. The purpose of the carbon cushion sheet is to provide a contrast in visibility when typing the stencil and also to produce an impression on a backing sheet which can then be used as aproof copy or for other desired purposes. For example, the stencil and carbon backing sheet are sometimes attached to an invoice form so that, when the stencil is typed, a copy is obtained on the invoice and the stencil can then be used in a hand stamp or otherwise to provide copies on packing containers.

Prior to the present invention, it was not possible to successfully provide a stencil assembly of this type which would eliminate the necessity for a separate carbon sheet. However there is now provided on the backof the stencil sheet itself a dark, impression-transmitting coating which in a farmore simple andeconomical fashionperforms .the function of the separate carbon sheet heretofore. necessary. i 4' Previous attempts tocoat the backing sheet of a stencil? assembly with a carbonizedmaterial; have not proven successful, because the oils in the stencil coating tended to soften the. carbon on the backing material. fl?hll s, while contrast would be obtained during the typing o hefstencil, it would 'not be, possible by such methods to obtain the type 'ofpro'o'f co'py referred to above.

Accordingly, it is an object of the present invention to provide a stencil assembly which includes a stencil sheet having a dark, image-transmitting coating on one surface thereof which will perform the function of the extra carbon sheet heretofore necessary.

Another object is to provide a stencil assembly which includes an image-transmitting stencil sheet and a backing sheet upon which a proof copy may be formed simultaneously with the cuttingof the stencil.

These and other objects of my invention will become apparent from the following description when taken in connection with the drawing, .in which the single figure is a perspective view showing the construction of the stencil as it would appear with the stencil sheet in the partially removed position.

Essentially the present invention is directed to a stencil sheet comprising a base tissue having a pastel-colored stencilizable coating on the surface thereof which is to receive the impression from the typewriter, stylus or the like. On the opposite, or back surface thereof, a

which -is in direct contact with the backing sheet, is pro- 2,970,931 Patented Feb. 7, 1961 ice carbon, impression-transmitting coating is provided. Although this coating typically, but not necessarily, includes a carbon type pigment, for the sake of simplicity it will hereinafter be referred to as the carbon coating.

This stencil sheet is readily fastened to a suitable impression-receiving backing material by providing, on one marginal edge thereofQa coating of a pressure sensitive adhesive which allows thestencil to be removably secured to the backing.

Thus, when making stencils in accordance with the stencil sheet and assembly herein disclosed, the carbon coating on the back of the stencil sheet provides sharp contrast with the pastel coated surface normally visible to the stencil cutter and at the same time allows for the producion of carbon proof copies on the impression receiving backing sheet.

Referring now to the drawing, it is seen that stencil sheet 10 may be removably secured to backing sheet 11 by means of the pressure sensitive adhesive strip 12, so that after the stencil is cut, the stencil :sheet is readily removed from the backing. The backing sheet also is readily detachable by means of perforations 16. It is also seen from the figure that there is produced on the backing sheet a carbon impression 18 of the stencil which was cut.

The pastel coating which is applied to the normally visible or outside surface 14 of the stencil sheet .will

typically be an oil-fatty acid-nitrocellulose mixture having 1 included therewith the desired light colored pigment in suitable proportions. An example of a suitable composition for the pastel'colored coating is as follows:

In. addition to the above, of course various stabilizers and plasticizers such as tricresyl phosphate, phenol, chlorinated naphthalene may be used.

.The pigment which may be used to impart the desired pastel color would be lead chromate, titanium dioxide, Hansa yellow or other lighter shades. i

In applying this coating, the pigment is first ground thoroughlyon a three roll mill in a portion of the oil. The nitrocellulose is dissolved in a mixture of active and latent solvents such as ether, ethyl alcohol, butyl acetate, methyl acetate, acetone, ethylene glycol, monoethyl' ethers, ethyl ethers, ethyl lactate, isopropyl alcohol. Other; solvents such as are typicallyused in lacquer formulations may also beused; it

In addition to the above, a hydrocarbon diluent may be used in quantities sufficiently limited not to upset the gel formation necessary for the production of a good stencil coating.

The pastel coating is preferably applied to the stencil sheet before the carbon coating. In order to make sure that the pastel coating is applied only to one side of the fiber sheet, it is necessary to set this coating rapidly after the application of the coating solution. Since the coating may be applied at various temperatures, there are many solvents which may be selected which are sufiiciently volatile to provide the necessary rapid setting. For example, using temperatures of the order of F., ethyl alcohol and ether would be suitable solvents while at higher temperatures up to about 250 F. higher boiling solvents may be selected to obtain the same desired results.

The opposite or back side of the stencil sheet 15, which .is not normally visible to the stencil cutter and applied to the stencil sheet so mm 94 A a i 3 i a dark. p qnran mittin matin which would typically have the following composition.

, Note thatin the carbon coating, the ratio, of nitrocellulose to the fatty acid. and oil is higher thaniinithe, pastel coating; This is necessary to make a relatively hard coating; which will'givea sharp impression on the copy paper and will not result in a broad splash or blurred car on i f he e 1 In applying this carbon coating to the stencil sheet, the same solvents as used with the pastel coatings may be used, except that the percentageof the-latent solvents should'be hi'gherin order that thiscoat does not attack n'interaet with the previously applied pastel coating. 1

The dark pigments which are used in the impression: transmitting coating are commonly black pigments such a carbon black, lamp black or Peerless black. In fiddle tion; to the above, blue pigments such as iron blue can beused and, if desired, a green pigment such as a mix: ture of iron blue and a yellow-pigment may also be used to give a satisfactory color and sufficient density for good visibility. It-is, of course, necessary to limitthe pigments inboth coatings to those which will not bleed in the oils used tq plasticize the nitrocellulose;

r in addition to the pigments mentioned above, there may also be used tungstated Victoria blueor a, non-bleed.- ingredpigrnent such as certain Lithol reds which are well knewnto the art, r

B oth the-pastel and dark colored pigments should be that a suitable weight of coating is applied on each side thereof' Each gram of base tissue will have on the outside surface thereof about'2.7'to 5.8 grams of the pastel coating composition and between about .08 to 1.6 grams of the carbon coating composition. These quantities-are typically applied to a stencil sheet eight and a half by sixteen and a half inches which will commonly have a weight of the order of one gram. g As previously mentioned, itis important that the ratio ofoil (including fatty acid) to nitrocellulose should be higher in the pastel coating. Thus in this coating, the oil to nitrocellulose ratio will be in the range of about 6,511 to 9:1. The carbon coating will have aratio of oil to nitrocellulose in the range of about 4:1 to, 7:1.

In addition to the above, it is of course apparent to one skilled in the art that the oil to nitrocellulose ratio may be dependent to some extent on the viscosity of the coa in compo io It i also ap a ent hat st a a wide variety of oil plastieizers and grades of nitrocellur amass;

4, lose which can vary the specific proportions referred to in the above examples. i

By coating the stencil sheet as indicated above, there is provided a single sheet which eliminates the necessity and therefore the cost of a separate carbon sheet. This advantage not only reduces manufacturing costs, but provides for simplicity in handling because there is no need to keep a separate carbon sheet in. alignment withthe stencil and the backing-sheet.

Although. preferred forms of this invention have been hat-di a ed. it llfnq b ap n to hes s; ssi in the art that many modifications and variations aybe 7 made, and it, is preferred therefore to be limited, not by the specific disclosure herein, but only by the appended claims. 1 9

What is claimed is:

l. A stencil sheet comprising a base tissue, a pastelcolored stencilizable coating on one surface of saidbase tissue, said coating having an oil to nitrocellulose.- ratio in the range. of about 6.511 to 9: 1,' and onthe opp surface of the base tissue, a dark, impression-transmit 'ng eoating having an oil to nitrocellulose ratio in the range of about 4:1 to 7:1. HM

2. The stencil sheet of claim 1 in which the pastel colored stencilizable coating is present in an amount of from about 2.7. to 5.0 grams per gram of base tissue. and the dark, impression-transmitting coating is present in an amount between about .08 to 1.6 grams per gram if base tissue. Y I

3. A stencil sheet comprising a base tissue, a pastel; colored stencilizable coating on one surface of said base tissue, said coating having an oil to nitrocelluloseiratie in the range of about 6.511 to 9:1, said coating further being present in amounts of from about 2.7, to 5.0, g Iris per gram of base tissue and, on the. oppositev surf thesaid base tissue, a dark, impression-transmitting ing having an oil tov nitrocellulose ratio in the range of about 4:1 to. 7:1, said coating further being present in an amount of between about '.08 to 1.6 grams per gram of base tissue. V v 1" References: e m h fil h s an:

UNITED STATES'PATENTS i "1,617,386 Fuerth eb. 15-, 1,645,593 Geiger .4 Oct. 13,1921 1,6 64,77 7 Horii Apr. 3, 1928 828,766 De Waele Oct. 27, 1931 1,937,75 Elliott Dec. 5, 1933 2,313,810 Dalton Mar. 16, 1943 2,335,992 Biskind Dec. 1; 1943 FOREIGN PATENTS 92,220 Great Britain May 15,1933

424,495] Great Britain s

Claims

1. A STENCIL SHEET COMPRISING A BASE TISSUE, A PASTELCOLORED STENCILIZABLE COATING ON ONE SURFACE OF SAID BASE TISSUE, SAID COATING HAVING AN OIL TO NITROCELLULOSE RATIO IN THE RANGE OF ABOUT 6.5:TO 9:1, AND ON THE OPPOSITE SURFACE OF THE BASE TISSUE, A DARK, IMPRESSION-TRANSMITTING