DE3405270A1 - Mechanically erasable writing fluid - Google Patents

Abstract

A mechanically erasable writing fluid in the form of an aqueous binder dispersion based on latex is described, which contains a colouring agent in the form of a water-insoluble dye and, if appropriate, further additives (according to Patent Application P 3230463.3-43), the writing fluid containing an anionic additive in the form of salts of carboxylic acids, salts of acidic sulphuric acid esters, salts of sulphonic acids and/or salts of phosphoric acid derivatives to stabilise it. A writing fluid of this type is distinguished by an extremely favourable stability. It is used in particular in capillary writing implements.

Description

Pelikan Aktiengesellschaft February 14, 1984 Hanover 84/6

Mechanically erasable writing fluid

The invention relates to a mechanically erasable writing fluid in the form of an aqueous binder dispersion based on latex, which is a color

contains agents in the form of a water-insoluble dye and possibly other additives, according to patent application P 32 30 463.3-43.

The writing fluid described above proves itself when used in capillary writing instruments as particularly suitable and leads to an intense, permanent font that can easily be removed from the surface the writer can remove what with a mechanical means, for example in the form

an eraser, can be done. It is advantageous if the binder is a dispersion (non-carboxylated) styrene butadiene, 2-chlorobutadiene and / or vinylpyridine-styrene-butadiene

Polymer is. Furthermore, particularly inexpensive 35

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Effects achieved when the water-insoluble dye is a water-insoluble anthraquinone and / or triarylmethane dye, the writing fluid additionally contains urea, acid amides or sulphoxides, wherein said urea in the form of N-methyl urea, thiourea or 2-hydroxyethyl urea, the acid amide in the form of Formamide or Acetarnii and the sulfoxide is in the form of dimethyl sulfoxide.

Also an additional content of a plasticizer, such as a phthalic acid ester and / or a citric acid ester, is advantageous. The same applies to an additionally incorporated humectant in the form of glycerin, 1,2,4-butanetriol or one Mixture of glycerine and sorbitol. In this writing fluid can also be a Achieve good adaptation of the surface tension and thus the flow behavior if you have low Amounts of a surfactant are incorporated. Such agents also provide stabilization of the writing fluid system without impairing the ability to erase.

It has now been shown that the writing fluid described above, in particular it is an erasable, colloid-dispersed ink system, which is then stabilized very excellently, when a careful selection is made from among the large number of surfactants, whereby cationic, nonionic and amphoteric agents of this type are excluded, and among the conceivable anion-active surfactants

a shortlist is made. 35

The invention therefore relates to a writing fluid of the type described at the outset, which is characterized in that the writing fluid contains an anionic additive to stabilize it in the form of salts of carboxylic acids, salts of acidic sulfuric acid esters, salts of sulfonic acids and / or salts of phosphoric acid derivatives.

The anionic ones which can be used according to the invention for the particular stabilization of the writing fluid Additives are surface-active substances. This is basically the collective term for most organic compounds that emerge from their solution at interfaces (e.g. Water / oil) and thus the interfacial tension reduce. These are compounds that have a lipophilic (hydrocarbon residue) and a hydrophilic (e.g. COONa, OSO.Nä, SO-Na and the like) group · keep. In the case of the anion-active additives of those described, which can only be considered according to the invention Kind are those in which the lipophilic group is in the anion, during the hydrophilic part is charged with opposite polarity.

The one in the writing fluid according to the invention The anionic additives contained therein are preferably present in a range from 0.05 to 2% by weight. If the value falls below the lower limit, the desired stabilizing effect will not be achieved reached more to the desired extent, while exceeding the upper limit of 2% by weight the later erasability of the written out writing fluid is lost and the surface tension is reduced too much will. It is particularly preferred

if the writing fluid of the mentioned anionic Contains additives 0.1 to 0.5% by weight.

For the purposes of the invention, the following more specific compounds are preferred: soaps, in particular

NH.-undecylenate, Na-oleate, N-acyl-sarcosinate, ansbe- ^lJ "" i special Na-N-lauroyl-sarcosinate and NH.-N-oleoyl-sarcosinate, N-acyl-L-glutainate, especially di-Na -N-stearoyl-L-glutamate and Na-NH.-N-lauroyl-L-glutamate, N-acyl-polypeptides, in particular the N-oleoyl-tetrapeptide-TEA salt and the N-undecylenoyl-tetrapeptide-K-salt, alkyl succinates, especially sodium dodecyl succinate, alkyl ether carboxylates, especially ΝΗ, lauryl polyethylene glycol (10) ether

! 5 acetate, aryl carboxylates, especially Na-2- (4-ethyl-

benzoyl) benzoate (salts of carboxylic acids), AUfcyl sulfate, alkyl ether sulfate, Alkyl aryl ether sulfates and fatty acid ester sulfates, in particular MEA lauryl sulfate, Na lauryl polyethylene glycol (3) ether sulfate,

on Na-oony1-phenol-polyethylene glycol- (10) -ether-sulfate

and k-ricinoleic acid monoglycerol ester sulfate (salts of acid sulfuric acid esters), condensed aromatic sulfonates, alkyl and alkenyl sulfonates as well as Aryl sulfonates, especially Na naphthalene sulfonate formaldehyde condensate, Na tridecyl sulfonate, Na eLr olefin sulfonate, Na N-benzyl sulfanilate and NH.-4-tetrapropylene-benzene-sulfonate, SuIfo-succinate and sulfo-succinamates, especially di-Na-monolauryl-polyethylene glycol- (3) -ether-sulfo-succinate,

go Di-Na-N-octadecyl-sulfo-succinamate and Tetra-Na-N-

(1,2-dicarboxy-ethyl) -N-octadecyl-sulfo-succinamate (Salts of sulfonic acids) and alkyl phosphates, Alkyl ether phosphates and alkyl aryl ether phosphates, in particular K-lauryl-phosphate, Na-oleyl-

gg phosphate, NH.-oleyl-polyethylene glycol- (3) -ether-

phosphate, NH.-cetyl-polyethylene glycol- (10) -polypropylene glycol- (5) -ether-phosphate, NH.-tridecyl-poly-

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ethylene glycol (3) ether phosphate and NHk-nonylphenol polyethylene glycol (5) ether phosphate (Salts of Phosphorus Murderivatives).

It has proven to be particularly advantageous in practice if the aforementioned hydrophobic Acyl, alkyl and alkenyl groups are higher molecular weight, especially more than 10 carbon atoms and preferably 10 to 20 carbon atoms. These hydrophobic groups can be branched or be chain-shaped. The aryl radical mentioned is preferably a benzene or naphthalene radical. This radical can have one or more substituents, such as the methyl, ethyl, propyl * "and isopropyl radical.

The compounds specifically named above are sodium and ammonium salts. Generally come for the purposes of the invention all other alkali or metal salts in question, the interfacial activity show and the desired stabilizing we on the mechanically erasable writing fluid exhibit. Identifying other suitable

Metal salts are not known to the person skilled in the art due to general knowledge and simple laboratory experiments further possible.

An example of a writing fluid according to the invention is listed below for illustrative purposes:

example

aqueous binder dispersion (25% styrene butadiene latex)

blue dye (CI 42 770: 1)

Solubilizer (N-methylurea) Plasticizer (diisobutyl phthalate) humectant (glycerine) anionic additive (Na-N-lauroyl sarcosinate)

72.0 Weight -% 2.0 Il Il 10.0 • I • I 5.0 Il Il 10.0 Il Il 1.0 Il Il 100.0 Weight · -%

Claims (3)

Pelikan Aktiengesellschaft February 14, 1984 Hanover 84/6 PATENT CLAIMS 1. Mechanically erasable writing fluid in Form of an aqueous binder dispersion based on latex, which contains a colorant in the form of a water-insoluble Dye and, if necessary, further contains re additives (according to patent application P 32 30 463.3-43), characterized in that that the writing fluid has an anionic additive in the form of to stabilize it Salts of carboxylic acids, salts of acidic sulfur contains rock acid esters, salts of sulfonic acids and / or salts of phosphoric acid derivatives. 2. writing fluid according to claim 1, characterized characterized in that it contains the anionic additive in contains an amount of 0.5 to 2 wt .-%. 3. writing fluid according to claim 1 or 2, characterized in that the salts of the carboxylic acids in the form of soaps, N-acyl sarcosinates, N-acyl-L-glutamates, N-acyl-polypeptides, alkyl- succinates, alkyl ether carboxylates and / or aryl carboxylates, the salts of acid sulfuric acid esters in the form of alkyl sulfates, alkyl ether sulfates, Alkyl aryl ether sulfates and / or fatty acid ester sulfates, the salts of sulfonic acids in the form of condensed aromatic sulfonates, Alkyl or alkenyl sulfonates, aryl sulfonates and / or sulfosuccinates and sulfosuccinamates and the salts of phosphoric acid derivatives in Form of alkyl phosphates, alkyl ether phosphates, Alkyl aryl ether phosphates are present.