US1906824A - Safety paper - Google Patents

Description

2, 1933. B. w. SMETH h s SAFETY PAPER Filed Jan. 16, 1931 TANA QD'SALES CQMPANY ANYWHERE U-S-A. No.

PAY TO THE ORDER OF 11 FIRST NATIONAL BANK ANYWHERE, U.S.A.

INVENTOR BURGESS W SMITH BY I.

Patented 2, 319333 UNHTED ters orrica or noeiansrnn, new roan, inssrenon ro rm ronn coarser-tr, and, or nocmsrnn, nnw roan, a eonronnrron or new roan sarnrr Application filed January it, ion,

This invention relates to safety paper such as commonly em loyed for the making of bank checks, dra ts, bonds and other valuable instruments and more particularly to s the variety of such paper containing a sensi= tive chemical ingredient capable of reacting with a chemical eradicating means to develop a conspicuous stain or color and thus indicate an unauthorized attempt to alter to matter written on such paper.

@no object of the invention is to provide such a paper containing an improved sensitive ingredient which is relatively stable to normal influences, but quickl develops a con- 1 trasting color change with the chemical eradicators in common use, in either an acid or alkaline condition, and capable after such color change, of resisting removal by the agents commonly employed for such pur oses.

A further object is to provide a safety paper, of the above character, capable of be ing manufactured by a comparatively simple and practicable method and at a comparatively low cost,

A further object is to rovide such a paper having a surface thereo rinted with an ink containing a sensitive su stance of the char actor described to form one or more initially colorless and inherently warning symbols adapted to be conspicuousl developed in color upon the application oi chemical eradi= caters in common use,

To these and other ends the invention re= sides in certain novel features and improve= ments, all as hereinafter more fully described, such novel features and improvements being pointed out in the claims at the end of the specification.

In the drawing:

Fig. 1 shows a bank check embodying the present invention in one mode of application of the same, and

Fig, 2 is a similar view showing a portion of the bank check with a difierent mode oi aplication of the invention in the preparation of safety paper of the character described in which the use of ink eradicators is indicated by the productions m a stain or other color change, the active In Serial Ito, EQQQTZQ.

gredient contained in the paper, for mash mum eiiiciency, should possess certain important characteristics in a definite and substantial degree, to adord paper capable of functioning in a positive and reliable manner adapted to meet the exacting requirements, for example, of bank checks and similar value representing instruments. Among such requirements, the active substance should be relatively stable to normal influences and the stain when produced should reliably resist removal by reagents commonly employed for such purposes. it should react quickly with the commonly used ink eradicators which are generally composed of an alkali hypochlorite used in conjunction with an acid such as a solution of tartaric acid. It should iurthermore react regardless of whether the acid of the eradicator is used first or after the alkali hypochlorite or whether it is used at all, as otherwise its efifectiveness could be readily avoided,

There are a number of compounds which react to give a conspicuous stain when hypochlorite of soda is used alone or in other it words, in the alkaline condition as, for erample, manganese sulphate and a number of aromatic amines. But when the hypochlorite of soda solution is used after the a plication of an acid solution and therefore in an acid condition, practically no stain, or at least an insignificant one would be produced,

In an efiort to overcome such and other defects or" active ingredients heretofore one ployed in safety paper, it has been found that substances characterized by the presence of two benzene rings or groups of benzene rings, linked.- together with the diphenyl linkage or the e uivalent of such linkage and having two hy roxyl radicals in the para position so to that linkage, develop a conspicuous stain with eradicators comprising hypochlorite of soda in either an alkaline or acid conditiona Substances of this class are represented in the simplest form by p,p'dihydroxydiphenyl as and in a more com or form by p pdihy= droxydihenylsulfi e and p,pd1hydroaydi=- phenylt iourea, but any equivalent linkage till t that does not dc'troy the diphenol character-1 istics may be used, and the term diphenol its substance, using the shorter name, is employed herein and in the appended clalms as including all such forms having essentially the characteristic structure or nucleus described above, as well as their substitution products, analogues, homologues and derivatives.

These diphenol substances have been found to possess to a high degree the important qualities requisite for use in safety paper as previously described and have in addition the further advantage of being colorless or substantially colorless, at least in a relatively pure form, so that they are for this reason also particularly advantageous in that they lend themselves to use in white or light colored safety paper, as well as for printing on such paper an initially invisible warning symbol as, for example, the word Void, for development by an eradicator.

The simplest form of such substances named above is preferred as it is particularly adapted for manufacturing purposes on a commercial scale at a low cost and in a high degree of purity. In using this form, it may be dissolved'in alcohol, or made into a water solution of one of its salts, preferably its sodium salt. The exact formula of either of these solutions is a matter of choice to suit particular conditions, the amount used being in substantial proportion to the intensity of the reaction color desired to be developed. Such a solution may be used to impregnat/e or coat the paper and such application to the paper is a relatively simple matter presenting no dificulty to one skilled in the art. The solution may be incorporated in the paper at various stages of manufacture, for errample, by addition to the pulp or to the web or sizing. These solutions may be employed either with or without regenerating the original phenol by action of an acid and, alternatively, instead of using solutions as described, the base may be ground and formed as a suspension and so incorporated in the paper.

Instead of impregnating or coating the whole surface of the paper, as indicated by the general stain developed by an eradicator as shown at 5, Fig. l of the drawing, or in add1tion thereto, the diphenol substance may be made into an ink and used to print on the paper the warning symbol such as the word Void, or other printed matter covering the paper surface in whole or in part, of an initially invisible character, but adapted to be rendered visible to act as a warning upon the application of an eradicator to any substantial portion of the paper surface. This mode of application is indicated, for example, in Fig. 2 of the drawing where the paper is shown as having a background 6 printed on it, leaving unprinted portions 7 representing the letters of the warning word Void, the background being shown as neoeeaa developed by an eradicator. Such an ink may be made in any suitable or known manner, as well understood in the art, with varnishes or other vehicles regularly used for this purpose, or celluloid dissolved in diacetone alcohol, or triacetin may be used, the proportions being adapted to the particular printing process and apparatus desired to be employed.

Upon the application of the usual ink eradicators, such, for example, as hypcchlorite of soda in either an acid or alkaline condition, with or withoutthe accompanying application of an acid, and in any order of application, the diphenol substance reacts rapidly to develop a stain or change of color contrasting sharply with the surrounding paper surface. Thus the application of the hypochlorite in an acid condition develops a pronounced orange stain and when hypochlorite of soda is used alone or in an alkaline state, a pronounced purple bla-cl: stain is developed. Such stains are substantially permanent against the influence of light, moisture or temperature, and relatively insoluble.

The invention thus provides a safety paper having in a high degree those qualities of sensitiveness in development and indelibility when developed which are required for the protection of valuable instruments, such as bank checks, as well as a safety paper adapted for commercial production by practicable methods.

I claim:

1. A safety paper containing a substance characterized by two carbon rings or groups of carbon rings linked together with the diphenyl or equivalent linkage and having two hydroxyl radicals in the para position to that linkage.

2. A. safety paper containing a colorless substance having two benzene rings or groups of benzene rings linked together with the diphenyl or equivalent linkage and having two hydroxyl radicals in the para position to that linkage and adapted to react with chemical eradicating means to develop a conspicuous stain or color.

3. A safety paper having a surface coated in whole or in part with an ink comprising a substance having two benzene rings or groups of benzene rings linked together with the diphenyl or equivalent linkage and having two hydroxyl radicals in the para position to that linkage, together with a varnish or other vehicle in sultable proportions to adapt thesame for printing on said paper.

4. A safety paper having a surface coated in whole or in part with an initially colorless ink comprising a substance having two benzene rings or groups of benzene rings linked together with the diphenyl or equivalent linkage and'having two hydroxyl radicals in the para position to that linkage, and a vehineoaeae adapted to react with a chemical eradicator to form a conspicuous stain or color.

5. A safety paper having an inherently warning symbol printed thereon with a colorless ink comprising a substance having two benzene rings or grou s of benzene rings linked together with the iphenyl or equivalent linkage and having twohydroxyl radicals in the para position to that linkage, and

a vehicle, in suitable proportions for printing, the said ink being adapted to react with a chemical eradicator to develop a conspicuous color change and thereby render said warning symbol conspicuously visible.

6. A safety paper containing a diphenol substance adapted to react with chemical eradicating means to develop a conspicuous stain or color.

7. A safety paper containing the salt 0 a diphenol substance adapted to react with chemical eradicating means to develop a conspicuous stain or color.

8. A safety paper-having a surface printed in whole or in part with an ink compris ing a diphenol substance together with a vehicle in suitable proportions for printing.

9. A safety paper having an inherently warning symbol printed thereon with a colorless ink containing a diphenol substance adapted to react with a chemical eradicator to develop a conspicuous color change and thereby render said warning symbol conspicuously visible.

10. A safety paper having an inherently warning symbol printed thereon with a colorless ink containing a salt of adiphenol substance adapted to react with a chemical eradicator to develop a conspicuous color change and thereby render said warning symbol conspicuously visible. BURGESS W. SMITH.

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