US1810484A - Stencil sheet - Google Patents

Description

Patented June 16, 1931 UNITED STATES PATENT orrlcr CHARLES E. KUMLI, OF CIHCAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

I SELEUIOGRAPH COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION OF ILLINOIS STENCIL SHEET No Drawing.

i yoshino paper, having a hardened coatingof '5 organic colloid,-impervious to ink, in wh1ch the stencil characters are cut, by the expression process, to permit the ink or other c01- oring to print through the fibers of the paper or other porous support.

One of the common types of stencils long in use consisted of Japanese yoshino paper coated with gelatin which was coagulated either by a' chrome salt such as potassium dichromate, or by an aluminum salt, which chemically combined with the gelatin to form a hard coating.

In order to adapt the coated sheet for making the stencil bypressure, asfor instance by the impact of the types of a typewriter,

the sheet must be dampened so as to permit the type to rupture the impervious film without cutting or otherwise injuring the fiber of the paper, or other porous support. In dam ening coated sheets which have been bar ened by "aluminum salts alone, the fibers of the paper have a tendency to stretch so as to cause. the stencil to become baggy in the frame, and the paper has a tendency to become sticky. For this reason, aluminum salts have not 1 been satisfactory as hardening agents.

Potassium dichromate as a, hardening a ent is also objectionable because it necessltates two steps in the coating process.

When potassium dichromateis employed,

the stencil sheet must first be' coated with the glue or gelatin and then coated with the hardening solution.

If the potassium dichromate were mixed with the glue or gelatin, before being applied to the sheet, coagulation would'take place in the solution, thereby rendering it diflicult to apply.

The mam objects of this invention are to I provide an improved coating material which is waterproof and which has none of the aforementioned objectionable characteristics inherent in solutions contai ing chrome or aluminum salts; to provide coating solution which may be applied in one opera- Application filed December 20, 1928. Seria1 No. 327,482.

tion; to provide an improved stencil sheet which is tough and waterproof and which will not become baggy when dam ened; and to provide an improved method 0 preparing stencil sheets which are to be moistened before being used.

Stencils may be made of any suitable fibrous, porous material, but Japanese yoshino paper is preferred because of its thin texture.

The improved coating material comprises an organic colloid, a volatile vehicle, a tempering agent, and an ammoniacal solution of cupric hydrate commonly known as Schweitzers reagent.

The colloid is the base or binding agent. It

Nbinds together the fibers of the paper and ives strength to the sheet. A good grade of ide glue has been found to be satisfactory,

but it may be replaced by any coagulable organic colloid.

The volatile vehicle may be water or any other suitable solvent which evaporates quickly after the film has been applied to the? sheet. 0

Glycerine is preferred as the tempering agent, but it may be replaced by sugar, glucose or any of the other well known tempering agents.

The Schweitzers reagent is the waterproofing agent. It coagulates the glueor other organic colloid to render the colloid waterproof.

In preparing this improved coating ma terial, the ingredients are mixed preferably in two separate vessels.

In one vessel, he glue is soaked in water for a period ranging from 6 to 10 hours. The glycerine is then added and the mixture heated to about 70 C. These ingredients may be combined in various proportions but highly satisfactory results can be obtained as follows:

In another vessel, copper'sulphate is dis solved in water by the application of heat.

The solution is then cooled and ammonium hydroxide is added.

When the first few drops of ammonium hydroxide come in contact with the solution of copper sulphate and water, a blue pre-' cipitate of cupric hydroxide is formed. A suflicient quantity of ammonium hydroxide is used to redissolve the cupric hydroxide.

The ingredients of the solution may be combined satisfactorily in the following proortions:

Parts by weight Ounces Copper sulphate 15 ater 42 Ammonium hydroxide solution) 9 The solutions in the two vessels are then mixed and the temperature brought to about 40 C. At this temperature the improved ing from the spirit'of the invention as defined by the following claims I claim: 1. A coating material for stencil sheets ,comprising a mixture of an organic colloid, 40 a tempering agent, and Schweitzers reagent.

2. A coating material for stencil sheets comprising glue, a tempering agent, and Schweitzers reagent. I

3. A coating material for stencil sheets comprising a mixture of an organic colloid,

salt, and ammonium hydroxide.

and ammonium hydroxide.

9. A composition for use in coatingthe porous base of a stencil sheet comprising an organic colloid about 11 parts, water about 43 parts, a tempering agent about 20 ounces, copper sulphate, and ammonium hydroxide.

10. The method of preparing a coating solution for stencils which consists in mixing an organic colloid and water, adding a tempering agent, and then adding Schweitzers reagent.

11. The method of preparing a coating material for stencils which consists in mixing an organic colloid with water and a temper ing agent, and then adding to the mixture a solution of a water soluble copper salt and ammonium hydroxide.

12. The method of preparing a coating material for stencils which consists in mixing an organic colloid with water and a tempering agent, and then adding to the" mixture a solution of copper sulphate, water, and ammonium hydroxide.

13. The method of reparing a coating ma-' terial for stencils w ich consists in mlxing glue about 11 parts with water about 43 parts, addingv20 ounces of glycerine, heating the mixture, making a solution of copper sulphate about 15 parts, water about 42 parts,

and ammonium hydroxide about 9 parts, and then adding said solution to said mixture.

14. A stencil'sheet coated with.- a mixture of a protein, colloid, a tempering agent, and Schweitzers r ent.

15. A stencil sheet coated with a. mixture of glue, a tempering agent, and Schweitzers reagent.

Signed at Chicago this 17th day of December, 1928.

CHARLES F. KUMLI.

a tempering agent, a water soluble copper 4. A coating material for stencil sheets comprising a mixture of glue, water, atemperlng agent, a water soluble copper salt,

and ammonium hydroxide.

: 5. A stencil sheet coated with a mixture of an'organic colloid, a tempering agent, and Schweitzers rea ent.

6. A stencil s eet coated with a mixture of an organic colloid, a tempering agent, a

water soluble copper salt, andammonium hydroxide.

7 A composition for use in coating the porous base of a stencil sheet comprising a mixture of an organic colloid, a tempering agent, copper sulphate, water, and ammo-.

nium hydroxide.

8. A stencil sheet coated ,with a mixture 5 of glue, a tempering agent, copper sulphate,