US1604884A - Duplicating - Google Patents

Description

Patented Oct. 26, 1926.

UNITED STATES ARMAND DE WAELE, OF LONDON,

ENGLAND, AS$IGNOR TO D. GES'IETNER, LIMITED, OF LONDON, ENGLAND.

DUPLICATING.

No Drawing. Application filed June 15, 1923, Serial No. 645,707, and in Great Britain April 12, 1923.

body, and which do not need moistening or softening prior to cutting the stencil by means of a typewriter or style.

Stencil sheets of the kind in question having a stencil layer of the character indicated formed from gelatinizing organic colloids which are peptized or dispersed in organic solvents and also others. in which colloids. for instance gelatine, which are peptized or dispersed in an aqueous medium are present, although organic solvents have in this case been usedin forming the coating composition, are known. The employment of organic solvents is, however, open to objection on account of expense and, further, stencil sheets of the kind specified formed from a gelatinizing organic colloid dispersible in an aqueous medium as hitherto produced have been found to be unsatisfactory.

The object of the present invention is to provide improvements in connection with stencil sheets-of the kind specified.

According to the present invention the main tempering agent is present in the composition, of which the stencil layer is constituted, prior to the gelation thereof, in that degree of dispersion which is regarded as characteristic of the colloid state.

Thus, acording to the invention, the composition may comprise a gelatinizing organr ic colloid dispersiblc in an aqueous medium and a tempering agent of the class de-i scribed below which prior to the gelation of the composition is dispersed to the degree specified.

My investigations appear to show that the main tempering agent will be present in the composition after gelation in substantially the same degree of dispersion but that such is the case I have not yet been able to show definitely. However, it would appear to be characteristic of the gelated compositions constituting the stencil layer in accordance with the present invention, that the tempermg agent is highly dispersed therein and most probably dispersed to the degree con-x sldered to be characteristic of the colloid state. ThlS high degree of dispersion I have found to be necessary for securing a highly sensitive stencil layer and at the same time a durable stencil.

In this connection it may be remarked that the tempering agents present in certain compositions constituting known stencil layers may be dispersed in the material after gelation to the degree considered to be characteristic of the colloid state, but if this is in fact the case they have been present in the composition prior to gelation in the form of true or molecular solutions usually in the medium used for securing the dispersion of the gelatinizing colloid.

The invention is not confined to the employment of particular organic colloids which will gelatinize but it may be remarked that organic colloids such as the protein colloids, which pepti'ze in aqueous media, may, in accordance with the invention, be employed in association with oilywaxy bodies or with waxy bodies and if necessary with an agent adapted to secure the dispersion of the latter to the degree above indicated.

The invention consists more particularly in a stencil sheet having a stencil layer of the character specified broadly in the above preceding paragraph, in which the oily-waxy bodies or waxy bodies present are soft or even liquid at the-ordinary temperature of the air.

The invention also extends to the process of forming stencil sheets which comprises applying to a porous support, for instance 'yoshino paper, an emulsion from whichvolatile organic solvents are absent, comprising a gelatmizmg organic colloid dispersed in an aqueous medium, an oily-waxy body or waxy bodyand, if necessary, an agent adapted to secure theemulsification of the latter in the organic colloid disperse.

Preferably, as emulsifying agents, sulphonated wax containing oil or sulphonated waxes and particularly the sulphonated oiland-wax mixtures or sulphonated liquid waxes or the sulphonation products of material proportions of liquid waxes derived from marine animals are employed.

The liquid Waxes include the oil from the case of the true sperm whale, Pity seter macrocephalus, and the oil from the head cavity of the bottlenose whale, Hy peroorlon 'r'ostmt'us and Hy joeroodon (Hod-on, both oils being, it is believed, described in commerce as sperm oil. Other oils obtainable commercially, for instance the oil from the blubber of the whales above referred to, contain material proportions of liquid waxes, and the products obtained by the sulphonation of such oils are suitable for use.

Highly satisfactory results, may be secured in accordance with the invention by using as the emulsifying agent sulphonated sperm oil which may also act as a tempering agent, and by the use of sperm oil as the oily or waxy constituent of the stencil layer or main tempering agent. The invention is, however,not confined to the use of sperm oil in this capacity as many other oils, ineluding for instance mineral oils, are suitable for use in accordance with the invention. I

In this connection it may be remarked that the employment of Turkey' red oil in association with fatty bodies and gelatinizing organic colloids, such as gelatine, dispersed in water has been proposed in the production of stencil sheets. I have found, however, that sulphonatedcastor oil and its derivatives. such as Monopol soap, are entirely unsuitable in the circumstances heretofore prescribed for use in accordance with the invention as they are incapable in such circumstances of securing the dispersion of the oily or fatty material throughout the gelatine or the like to produce a product inwhich the oily-waxy or waxy material is present in a degree of sub-division comparable with that regarded asa characteristic of colloid particles.

oily-waxy or waxy constituents are esent in thestencil layers in accordance with the invention in such proportion that they constitute wholly or mainly the tempering agent for the organic colloid. such as gelatine,-'that'is.to say, the agent adapted so to modify the properties of the colloid that the structure of the stencil layer may' be 7 broken down by the blows of the type when ;1'nsed in forming stencils in a typewriter or the style when producing a stencil by gland.

The proportion of the tempering agent I at it hav found 'it convenient to employ may 1 5 ry between six and ten parts to one of a "colloid, such as gelatine. This indication, however, is only given for the purpose of illustrating the proportionl have found it convenient to use incertain atmospheric or climatic conditions.

An opaque pigment, the colour of which will contrast with the ink with which the stencil will be used, for instance a white pigment, may be incorporated in the stencil layer, as indicated in the specification of the co-pending application for Letters Patent No. 645.708 care being taken to select a pigment which does not operate to break down the structure of the coating composition.

The coating of the porous material forming the base of the stencil sheet may be effected in the usual manner by the employment of a trough or roller, the coated sheet being then dried Without, however, subjecting it to treatment which would cause the composition constituting the stencil layer to liquefy.

Further, the coated sheet may be formolized or otherwise treated to convert the organic colloid, such as gelatine, present therein into the insoluble or hardened form.

As is well known, gelatines vary considerably in their properties; for instance. some ar more acid than others. It is therefore important to select a gelatine, the properties of which are not inimical (in consequence, for example, of the presence of impurities in it) to the formation of a-stable colloid when it is brought together with the oily or waxy bodies and the emulsifying agent.

The-following particulars are given by way of example to illustrate a suitable method of carrying the inventionintoeffect.

A coating composition isv prepared by mixing 150 parts of a 10% aqueous solution of gelatine with 25 parts of sulphonated sperm oil and 75 parts of sperm oil and adding 20 parts of a composite White titanium oxide pigment. The composition when uniform and diluted to a suitable viscosity is introduced into the tank of a coating machine of the kind in which the material to be coated is drawn over a roller partly immersed in the coating composition, meanwhile maintaining the com osition at a-temperature substantially over its gelating temperature, for example, F. to 140 F.

The coated sheets are then allowed to dry, care being taken to avoid liquefying the composition during this operation.

The coated sheets may then be formolized by passing them through a chamber in which an atmosphere containing formaldehyde is maintained,

It is to be understood that the expressions employed herein in attempting to define the scope of the invention may by further research be found inappropriate; they are, however, believed to be suflicient to define the invention in accordance with current conceptions in the try. 1'?" A Further, as used in the claims, the expression oily body includes bodies which are in fact waxes or contain material proporlmpf physical chemis q tions of waxes and sulphonated wax and sulphonated liquid wax include products obtained by the sulphonation of oils con-' taining material pro ortions of wax.

Having now descri ed my invention, what I claim as new, and desire to secure by Letters Patent is 1. A stencil sheet for use in duplicating manuscript and typewritten documents, drawings and the like, comprising a stencil layer in the form of a disperse system including a gelatinized organic colloid deposited from anaqueous medium, an oily body as the main tempering agent and a sulfonated material containing a sulfonated wax adapted to secure the desired degree of dispersion of the oily body in the stencil layer. I

2. A stencil sheet for use in duplicatin manuscript and typewritten f documents drawings and the like, comprising a stencil layer in the form of a disperse system .including a gelatinized organic colloid deposited from an aqueous medium, an oily body as the main tempering agent and a sulphonated wax.

3. A-stencil sheet for use in duplicating manuscript and typewritten documents, drawings and the like, comprising a stencil layer in the form of a disperse system including a gelatinized organic colloid deposited from an aqueous medium, an oily body as the main tempering agent and a Sulphonated liquid wax.

4. The process of forming stencil sheets which comprises applying to a porous support, for instance yoshino paper, an emulsion from which volatile organic solvents are absent, comprising a gelatinizing organic colloid dispersed in an .aqueous medium, an oily bodyfiin' a proportion considerably in excess of the said colloid, and functioningas the main tempering agent, and a sulphonated wax. I

5. The process of forming stencil sheets which comprisesapplying to a porous support, for instance yoshin'o paper, an emulsion from which volatile organic solvents are absent, comprising a gelatinizing organic colloid dispersed in an aqueous medium,

an oily body in a proportion considerably in excess of the said colloid, and fimctioning as the main tempering agent, and a sulphonated liquid wax.

6. The process of forming stencil'sheets which comprises applying to a porous support, for instanceyoshino paper, an emulsion from which volatile organic solvents are absent, comprising a gelatinizing organic colloid dispersed in an aqueous medium, an oily body in a proportion considerably in excess of the said colloid, and function