Compositions: coating or plastic – Coating or plastic compositions – Metal-depositing composition or substrate-sensitizing...
Patent
1980-09-06
1983-01-11
Kight, III, John
Compositions: coating or plastic
Coating or plastic compositions
Metal-depositing composition or substrate-sensitizing...
106 26, C09D 1100
Patent
active
043680763
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ink composition which affords ink images of a brilliant tint which are erasable with water. More particularly, the present invention relates to an ink composition which contains as predominant ingredients thiocyanate ion, a metal ion capable of showing a specific tint with the thiocyanate ion, and polyalkylene glycol and which produces ink images of a brilliant tint on a material to be transferred, such as paper. The ink images are easily erasable, if necessary, with water.
BACKGROUND ART
The thiocyanate ion shows a specific color in the presence of a certain kind of metal, for example, a metal of the iron group. When a slightly yellow aqueous solution of ferric nitrate or a light carmine aqueous solution of cobalt chloride is added to a colorless aqueous solution of potassium thiocyanate, for example, an orange brown or red purple aqueous solution attended with no precipitate is formed, respectively. Because of these characteristic color reactions, the thiocyanate ion and these coloring metal ions have been utilized for simple qualitative analyses of the individual ions. From the past, aqueous colored colloidal dispersions and aqueous solutions of certain kinds of organic dyes were used as ink compositions. Whereas, an ink composition containing thiocyanate ion has not yet been known heretofore.
The present inventor previously provided an ink composition containing cobalt thiocyanate as a predominant ingredient (Japanese Patent Publn. No. 49-27527; Japanese Pat. No. 765,826). This ink composition has a character that letters and lines drawn with the ink composition can easily be erased, if necessary, by wiping with cloth, paper or fibers impregnated with water.
In this ink composition, however, there is such a disadvantage in actual use that if the amount of cobalt thiocyanate used is saved and a solution of a lower concentration is used as ink, the written letters are not colored in blue immediately but are colored for the first time when the solvent is evaporated to increase the concentration. To overcome such disadvantage, the use of an ink wherein the concentration is increased to at least 30% is necessary. In such case, however, fluidity of the ink becomes poor because of such high concentration so that difficulty arises in charging a pen core with the ink. When the concentration of cobalt thiocyanate becomes higher by gradual evaporation of the solvent on the repeated use of a pen, the ink will not come out clearly so that the written letters become thin. Considering these situations, inks containing cobalt thiocyanate as a predominant ingredient is used usually in a concentration of about 20%. In this case, however, difficulties arise in actual use as described above because of such too low concentration.
DISCLOSURE OF INVENTION
As a result of extensive researches made to overcome drawbacks in the above mentioned conventional "easily erasable" ink compositions, it has now been found that the tint formed between thiocyanate ion and cobalt ion can be intensified remarkably by adding polyalkylene glycol to a solution containing in a liquid vehicle cobalt thiocyanate alone or both of thiocyanate ion and cobalt ion and that a deep blue ink composition can be obtained even in case either or both of thiocyanate ion and cobalt ion is low in concentration. The present invention has been accomplished on the basis of the above finding.
In accordance with the present invention, there is provided an ink composition which comprises a solution of cobalt thiocyanate or a mixture of a compound capable of producing thiocyanate ion and a compound capable of producing cobalt ion in a liquid vehicle such as water and/or an organic solvent, the solution having been incorporated with polyalkylene glycol as a color-intensifying assistant.
Cobalt thiocyanate is easily soluble in water and in a number of the organic solvents and its aqueous solution gives red violet color probably due to the formation of a cobalt complex in which 5 molecules of water are coordinated
REFERENCES:
patent: 4014833 (1977-03-01), Story
Adger Kogyo Co., Ltd.
Kight III John
Yarbrough Amelia B.
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