US2085874A - Safety paper and method of making same - Google Patents

Description

Patented July 6, 1937 OFFIQE.

SAFETY PAPER AND IWETHOD OF MAKING SAME Francis L. Simons, Needham, Mass., assignor to George La Monte & Son, Nutley, N. J., a corporation of New Jersey No Drawing.

Application February 4, 1935,

Serial No. 4,873

8 Claims.

ing fraud-preventing writing material made of paper or other substance or composition adapted for printing or lithographing or for the inscripiion of writing thereon and for use, for example, in the manufacture of checks, drafts, bonds, stock certificates, or other instruments which it is desired to have protected against fraudulent alteration and to methods of making such safety paper. This invention relates particularly to safety paper having incorporated therein by impregnation or superficial application, either continuously or locally, 2. chemical compound which is adapted upon application of a chemical ink eradicator thereto to result in a disfiguring stain of a relatively permanent and indelible character which renders apparent attempts that are made to alter the safety paper by the use of a chemical ink eradicator.

It is a purpose of this invention to afford safety chemicals which, when incorporated in safety paper, develop disfiguring stains of a desirably pronounced and permanent character when chemical ink eradicators are applied thereto. By developing color, it is meant that a colorless compound becomes colored or that a colored compound becomes more intensely colored or changes in color. It is a further purpose of this invention to afford safety paper which does not discolor undesirably on ageing due to premature development of color as the result of such causes as exposure to air and/or to light.

I have found that desirable safety paper can be prepared using as a safety chemical aminodiphenyl. Amino-diphenyl may occur in three forms, namely, the ortho, meta and para forms. Of these forms, para amino-diphenyl is regarded as preferable. In addition to amino-diphenyl, the primary mono-amino homologues, derivatives, substitution products, and salts of amino diphenyl may be employed in the practice of this invention. Among such derivatives and substitution products are those compounds in which one or more hydrogen atoms of the diphenyl nucleus is replaced by a hydrocarbon substituent. The hydrocarbon substituents include such hydrocarbon radicals as methyl, ethyl, propyl, phenyl, naphthyl, tolyl, pyridyl, pyryl, quinolyl and the like. Likewise a hydrogen atom of the diphenyl nucleus or of a hydrocarbon substituent may be replaced by an acidic radical such as SOaI-I (sulphonic), N02 (nitro), COOH (carboxyl), or Cl, Br or I (halogen). For the purposes herein set forth the OH (hydroxyl) radical may be considered as an acidicradical. These (01. 91-6735) This invention relates to safety paper includacidic substituents, with the possible exception of the halogens, form salts with such metals as the alkali metals and other salt forming alkaline earth and heavy metals. Thus the sulphonic group may form with alkali metals salts such as sodium and potassium, e. g.SO3Na. Of these salts of acidic derivatives the alkali metal salts are preferred. Hydrocarbon substituents and derivatives thereof may be referred to as aliphatic, aromatic and heterocyclic substituents.

Amino diphenyl and the primary mono amino homologues, derivatives and substitution products of amino diphenyl, being basic in char act-er, form salts such as the acetate, oxalate, hydrochloride and sulphate. Of such salts the sulphate is regarded as preferable. Salts of this type are referred to as ammonium type salts.

When safety chemicals of the character above mentioned are incorporated in safety paper, it has been found that these chemicals, when treated with chemical ink eradicators, such as the bleaching type of ink Eradicator that is extensively used at the present time, for example containing sodium hypochlorite, result in a relatively ermanent and indelible colored compound that immediately disfigures the safety paper and gives evidence of the fact that the safety paper has been tampered with. The ink eradicators most generally on the market at the present time contain hypochlorite solution, which is particularly effective in developing colored warning indicia as soon as contacted with safetypaper carrying the chemicals above mentioned. The colored compounds that result when an oxidizing ink eradicator of the bleaching type above referred to is applied to safety paper having incorporated therein the safety chemicals above mentioned are relatively indelible against removal by acids or alkalis or by reducing agents.

It is a desirable feature of this invention that the safety chemicals above mentioned do not undesirably becorne discolored on ageing and/or upon exposure to light. chemicals above mentioned are substantially colorless; that is, they do not impart substantial color to safety paper in which they are incorporated when used in amounts sufiicient to impart substantial protection to the safety paper. The use of substantially colorless compounds of the class above mentioned is regarded as preferable in the practice of this invention.

Safety paper embodying this invention may be prepared in several ways. In the case of waterinsoluble compounds such as para amino-diphenyl, for example, the safety chemical may be Likewise many of the V incorporated in safety paper by mixing the chemical with the paper fiber during the beating process which forms a part of paper manufacture. The safety chemical may be added in the form of 5 a dry powder, for example, prior to or during the beating of the fiber. In such case, the safety chemical is carried into the resulting paper so that, when a chemical ink eradicator is applied to the resulting paper, a pronounced color is developed due to the action of the ink eradicator on the safety chemical. In the usual case, approximately two per cent. to ten per cent. of the safety chemical on the dry weight of the paper may be used. or course, greater or lesser amounts can be used, depending upon the color that the substance selected develops upon being treated with a chemical ink eradicator and the intensity of the developed color that is desired. Normally, the more of the safety chemical that is incorporated 0 in a safety paper, the more intense will the color development be when a chemical ink eradicator is subsequently applied to the safety paper.

Alternatively, the safety chemical may be dissolved in a suitable solvent and applied to the paper. Thus many of the safety chemicals above mentioned are soluble in solvents therefor such as toluene, ethyl acetate or acetone or mixtures thereof. A solution of such chemicals may be applied to paper in any suitable manner as by dipping, spraying and the like. When a solution is applied to paper, the solution should be of such concentration that about two per cent. to ten per cent, for example, of the safety chemical on the dry weight of the paper becomes incorporated in the paper. In the case of water-soluble derivatives of amino-diphenyl water may, of course, be used as a solvent.

The safety chemicals by the methods above mentioned, and by other methods of impregnation or surface applications, can be impregnated in the body of the safety paper or may be applied on the surface thereof, and while it is preferable to have all parts of the safety paper reactive similarly when chemical ink eradicators are applied there- 4 to by having the safety chemical distributed uniformly, the safety chemical can be applied locally as by printing or by any other suitable method. In any event, safety paper carrying the safety chemicals herein described will be regarded as having such safety chemicals incorporated there- It will be understood that this invention is applicable among other fields of application in connection with plain white paper as well as tinted paper or paper having surface markings thereon. It is likewise applicable when a tint in the paper is delible under the action of chemical ink eradicators and/or when the surface marking or tinting is removable by mechanical erasure.

While this invention has been described in connection with certain specific examples thereof, it is to be understood that this has been done merely for the purpose of illustration and that the scope of this invention is to be governed by the following claims.

I claim:

1. A safety paper having incorporated therein a primary mono-amino diphenyl.

2. A safety paper having incorporated therein para-amino-diphenyl.

A safety paper having incorporated therein a substance selected from the group consisting of amino-diphenyl and the primary mono-amino homologues and derivatives thereof.

i. A safety paper having incorporated therein a salt of a primary mono-amino diphenyl.

5. A safety paper having incorporated therein an ammonium type salt of a primary mono-amino diphenyl.

6. A safety paper having incorporated therein the sulphate of a primary mono-amino diphenyl.

7. A method of making safety paper which comprises incorporating therein a substance selected from the group consisting of amino-diphenyl, and the primary mono-amino homologues and derivatives thereof.

8. A safety paper having incorporated therewith para-amino-diphenyl sulphonic acid.

FRANCIS L. SIMONS.