US3409516A - Electrolytic recording paper containing a sequestering agent - Google Patents

Description

Ueied Stat s Paten Qflie ELECTROLYTIC RECORDING PAPER CONTAIN- v ING A SEQUESTERING AGENT Robert S. Ives, Lexington, Mass., assignor to.

Milton Alden, Needham, Mass. No-Drawing. Filed June '11, 1963-, Ser. No. 286,951 Claims. (Cl. 204-2) ABSTRACT OF THE DISCLOSURE a'record' of improved definition.

Electrolytic recording. bypassing a modulated electric curte'nt through an electrochemical recording paper to produce markson the paper in accordance with the cur-.

rent is well-known in the facsimile art. One type of paper utilized in such' recording has been impregnated with a Water solution'containing an electrolyte and an organic lake-former which combines with electrode'metal ions to form a colored lake on the paper. These recording papers have been used commercially but have given rise to a number of problems and limitations. Such papers after impregnation andparticularly after recording, have not been as? stable in, storageas is desirable and the definition of the record. .onsuch paper has been limited. This limited definitionis .due, partto the fact that the background of the record. tends. to discolor. with time and also tothe fact that the recording marks have tendency to trail behind the electrodeafter the current has stopped and to bleed later ally on'the paper from the point of recording The*principal' pbjct of-- this invention'is to provide electrolytic recording material of the above type which is will provide a record more stable in storage and which with improved definition.

In accordance with this invention, the improved electrolytic recording material, for recording with a lake-forming metal electrode, comprises a support impregnated with a water solution containing an organic lake-former, an electrolyte, and a chelating or sequestering agent, said agent retaining stray recording metal ions in colorless form at non-recording parts of the support. Amino carboxylic acid sequestering agents and particularly amino polycarboxylic acids are preferred. Suitable materials include water-soluble salts of ethylenediaminetetraacetic acid (EDTA), and of N-hydroxyethylethylenediaminetriacetic acid.

It is believed that the discoloration of the background of the recorded material is to a substantial degree caused by small amounts of metal lake-forming ions which either migrate in a record or are deposited in non-recording portions of the record as it moves between the electrodes. Similarly, it is believed that the trailing of the mark behind the electrode after the recording current has ceased is due to small amounts of the metal ions combining to form a lake either by migration to the support or by mechanical transfer from the record to the electrode and back again to the support. Such trailing is particularly noticeable with highly sensitive organic lake-formers. Both phenomena are substantially reduced with corresponding improvement in the record by the inclusion of chelates according to this invention which complex with such stray metal lakeforming ions to form colorless complexes at non-recording points of the record.

3,409,516 Peter en 5.1 96 8 .This invention may be better understood byire ference jto the following examples:

Example 1 Methylene disalicylic acid (MDA) 9 Potassium nitrate a I "9 Sodium hydroxide L 2125 Versenol 120 (0.5%) 0.6

Water to make 100 cc.

Versenol 120 is the trademark of the Dow-Chemical Co. for a concentrated water solution of the trisodium salt of N-hydroxyethylethylenediaminetriacetic acid. 7

'- Example2 t Grams MDA 9 K C1 I I l 9 NaOH t v 2.25' Sequestrene 30A 0.6.-

Water to make 100cc.

Sequestrene 30A is the trade name of the Geigy Co. for a 39% aqueous solution of tetrasodium ethylenediaminetetraacetate.

Example 3 Grams MDA 9 KCI s 9, NaOH 2.25 Cheelox B14 Water to make 100 cc.

Cheelox B-l4 is a trade name of the AntaraChemical Co. for a 41% aqueous solution of amixture of soluble salts of amino carboxylic acids.

Example 4 V Grams Tannic acid 140 NaCl 120 Se'questrene Na- -2 1.25 Water to make 2 pints.

- Sequestrene Na-2 is the trademark for a solution-of salts of amino polycarboxylic acids by the Alrose Chemical Co.

Nullapon Fe-12 is a trademark of the General Dyestuff Corp. for amino polycarboxylic acid salt solutions.

Example 6 Grams Protocatechuic acid 150 KNO 800 Thiourea Permakleer OH 10.5

Water to make 2 gal.

1 Permakleer OH is the trade name for amino polycarboxylic :cid chelatlng agent solutions made by the Refined Products orp.

In the above examples the MDA, tannic acid, catechol and pyrocatechol are all organic lake-formers which combine with the metal electrode ions to form a colored lake.

The potassium chloride, and sodium chloride are electro- I lytes. Other suitable electrolytes include the chlorides, bromides and nitrates of the alkali metals. Other suitable organic materials which form insoluble lakes with the metal ions of the electrode can be used. Suitable electrode metals include chromium, copper, nickel and, preferably,

ll'OIl.

In the above examples the Versenol 120, Sequestrene 30A, Cheelox B-14, Sequestrene 'Na2, Nullapon Pe-12, and Perma Kleer OH are all chelates of the amino carboxylic acid type. Other amino carboxylic acids which may be used include di (hydroxyethyl) glycine and diethylenetriaminepentaacetic acid which latter compound is an effective chelate in both alkaline and acid solutions. The di (hydroxyethyl) glycine which is an amino monooarboxylic acid is less effective than the amino polycarboxylic acid chelates. The chelates according to this invention are preferably used in amounts which may vary from about 0.05% to about 1.0% pure chelate by weight of the total impregnating solution.

A support, preferably paper, is impregnated with any of the abovesolutions by passing'it through a bath of the solution. Pressure rolls can be employed to remove excess. Recording paper having 40% by weight moisture is suitable. Treated paper is preferably stored in sealed containers until used.

It should be understood that this disclosure is for the purpose of illustration only and that the invention includes all equivalents and modifications falling within the scope of the appended claims.

I claim:

1. In an electrolytic facsimile recording medium for recording solely by passing a modulated electric current therethrough to form a' colored mark with an organic marking compound contained therein, said medium consisting of a support impregnated with an electrolytically conductive solution consisting of an electrolyte and an organic marking compound producing color by chemical combination with metal electrode ions, the improvement which comprises including in said solution an amino polycarboxylic sequestering agent for said electrode metal ions in an amount sufiicient to improve definition by complexing in colorless form recording metal electrode ions in non-recording parts of the support.

2. A recording medium according to claim 1 wherein said sequestering agent comprises from about 0.05 to about 1.0 percent by weight of said solution.

3. Electrolytic recording material according to claim 1 wherein said sequestering agent comprises a water soluble salt of ethylenediamine polyacetic acid.

4. Electrolytic recording material according to claim 1 wherein said sequestering agent comprises a water soluble salt of ethylenediaminetetraacetic acid.

5. Electrolytic recording material according to claim 1 wherein said sequestering agentcomprises a Water soluble salt of N-hydroxyethylethylenediaminetriacetic acid.

6. A recording medium according to claim 1 wherein said marking compound is selected from the group consisting of methylene disalicylic acid, tannic acid, catechol and protocatechuric acid.

7. A recording medium according to claim 6 wherein said metal electrode ions comprise iron.

8. A recording medium according to claim 7 wherein said sequestering agent is selected from the group consisting of water soluble salts of EDTA, N-hydroxyethylethylenediaminetriacetic acid, di(hydroxyethyl) glycine and diethylenetriaminepentaacetic acid.

9. Electrolytic recording material according to claim 1 which comprises a support impregnated with a water solution containing an electrolyte, methylene disalicylic acid, and 'a sequestering agent selected from the group which consists of soluble salts of N-hydroxyethylenediaminetriacetic acid and ethylenediamine tetraacetic acid.

10. Electrolytic recording material according to claim 1 which comprises a support impregnated with a water solution containing an electrolyte, a polyhydroxy phenol, and a sequestering agent selected from the group consisting of soluble salts of N-hydroxyethylenediaminetriacetic acid and ethylenediaminetetraacetic acid.

References Cited UNITED STATES PATENTS 2,949,409 8/ 1960 Richards 2042 3,108,050 10/1963 Mandrel et a1 204'2 3,113,910 12/1963 Hepher 2042 3,142,562 7/1964 Blake 204-2 3,165,458 1/1965 Harriman 204l8