JPH0139701B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel ink composition, more specifically, an ink composition that can erase characters and designs written on paper with a commercially available eraser, and can also write characters and designs again in the erased traces. It is related to. When writing ink used in conventional fountain pens, ballpoint pens, felt-tip pens, etc. is used to write on paper, it is almost impossible to erase the written information with an eraser. To erase information written with conventional ink, erasing fluid or concealing fluid is generally used. However, when using such erasing liquid or concealing liquid, the erased marks are in a wet state, so it is not possible to write on them immediately after erasing them, and in order to write on the erased marks again, It was necessary to completely dry the erased traces. The present inventor has conducted various researches to develop an ink composition that allows written characters and designs to be easily erased with a conventional eraser, without using the above-mentioned erasing liquid or concealing liquid. We have proposed an ink composition in which a pigment selected from black and aniline black is uniformly dispersed in an aqueous medium in which high-molecular weight polyethylene oxide or alginic acid derivatives are dissolved (Japanese Patent Application No. 57-209148, same).
57-209149, 58-98455, 58-98456)
However, they found that an easily erasable in-composition can be obtained even when carbon black or aniline black non-emulsion pigments are used as pigments, and they also found that the dispersion stabilizer is improved by adding methylcellulose. , we have completed the present invention. That is, according to the present invention, non-emulsion water-insoluble organic pigments other than aniline black have a molecular weight of 10.
Letters written on paper characterized by being uniformly dispersed in an aqueous medium in which at least one water-soluble polymer selected from over 10,000 polyethylene oxides and alginate alkylene glycol esters and methyl cellulose are dissolved. An ink composition for paper whose design can be erased with an eraser is provided. The pigment used in the present invention is a non-emulsion water-insoluble organic pigment other than aniline black and carbon black. Preferred organic pigments include phthalocyanine pigments such as Phthalocyanine Blue and Phthalocyanine Green; nitrone pigments such as Naphthol Green B, nitro pigments such as Naphthol Yellow S; azo pigments such as Permanent Red FRL, Toluidine Maroon, and Hansa Yellow 3R. Pigment; Isoindolinone pigment; Indanthrene brilliant orange
Examples include vat dye-based pigments such as GK and Monolite Fastread YS; basic dye-based pigments such as Victoria Blue Lake; and acid dye-based pigments such as Quinoline Yellow Lake. The organic pigments mentioned above are used in concentrations ranging from 0.1 to 20% by weight, preferably from 2 to 10% by weight in the ink. Water-soluble polymers are used to prevent ink from penetrating paper, and include polyethylene oxide,
Alginate alkylene glycol esters and mixtures thereof are used. The molecular weight of polyethylene oxide is usually about 100,000 to 5,000,000, preferably about 100,000 to 1,500,000. In the ink composition of the present invention, the concentration of the water-soluble polymer is usually 0.01 to 15% by weight, preferably 0.05 to 10% by weight in the case of polyethylene oxide, and 0.05% in the case of alginate alkylene glycol ester.
-3% by weight. The ink composition of the present invention may contain various additives such as a surfactant, a thickener, a dispersion stabilizer, and a PH adjuster, if necessary. The surfactant promotes the dispersion of the pigment in the ink, and nonionic and anionic surfactants are optionally used. Its concentration is between 0.01 and 7% by weight, preferably between 0.05 and 5% by weight. In this case, the nonionic surfactants include polyethylene glycol alkyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples of anionic surfactants include sorbitol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, and polyoxyethylene alkyl amine. Examples of anionic surfactants include higher fatty acid alkali salts, alkyl phosphates,
polyoxyethylene alkyl ether phosphate,
Examples include alkyl sulfonates, alkylaryl sulfonic acids, acylamino acid salts, polyoxyethylene alkyl ether sulfates, and sulfosuccinate ester salts. As the surfactant, it is particularly effective to use one containing a polyoxyethylene group. Examples of such surfactants include polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene alkyl ether, and polyoxyethylene phytate. Sterol, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene alkyl phenyl ether, polyoxyethylene castor oil, polyoxyethylene beeswax derivative, polyoxyethylene lanolin derivative, N-polyoxyethylene alkylamine, N-polyethylene fatty acid amide , polyethylene glycol fatty acid esters, polyoxyethylene nonylphenyl formaldehyde condensates, etc., as well as polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl acetate salts, polyoxyethylene alkyl phosphate salts, etc. Examples include anionic ones. As the dispersion stabilizer, it is preferred to use methylcellulose. By using this, the dispersion stability of the ink is increased and precipitation of pigment particles during storage is prevented. The amount of methylcellulose used in the ink varies depending on its molecular weight, but is usually 0.002 to 15% by weight, preferably 0.005 to 10% by weight.
is within the range of Examples of thickeners include glycerin, alkylene glycols, and polyalkylene glycols with molecular weights up to 300. The thickener concentration in the ink is 3-40% by weight, preferably 5-30% by weight. Incidentally, a small amount of an organic solvent such as alcohol can be used for the purpose of increasing the solubility of components other than the organic pigment in the aqueous medium. However, inks containing organic solvents tend to increase their permeability into paper and reduce erasability. Therefore, it is necessary to suppress the amount of organic solvent used to 10% or less based on water.
In this regard, the use of commercially available O/W type (oil-in-water) emulsion pigments as pigments causes a decrease in ink erasability and should be avoided. The water content in the ink composition of the present invention is usually 50
-90% by weight, preferably in the range 55-85% by weight. In addition, in order to create an ink with appropriate fluidity and good writing properties, the viscosity of the ink was increased to 1.5.
A range of ~70 cps is preferable. The ink composition of the present invention is applied as an ink for writing instruments such as ballpoint pens, felt tip pens (signature pens), fountain pens, etc., and characters and figures drawn on paper thereby can be easily erased with a commercially available eraser. Next, the present invention will be explained in more detail with reference to Examples. Example An ink composition was prepared by uniformly mixing and dispersing a pigment, an aqueous solution of a polymeric substance, a surfactant, and various auxiliary agents together with water. Table 1 shows the component composition of the ink composition prepared as described above. The symbols shown in Table 1 have the following meanings. PCB: Phthalocyanine blue (blue) PCG: Phthalocyanine green (green) PR: Permanent Red FRL (red) NY: Naphthol Yellow S (yellow) PEO: Polyethylene oxide (molecular weight 10) MC…………Methylcellulose (Product name: Marporose Matsumoto Yushi Pharmaceutical Co., Ltd., product number M-400, used as a 5% aqueous solution)
SA ()...Polyoxyethylene alkyl phenyl ether SA ()...N-polyoxyethylene alkylamine ALG...Alginate propylene glycol ester (used as a 1% aqueous solution) GL...Glycerin

[Table] Next, each of the above ink compositions was separately impregnated into the wadding of a felt-tip pen, and allowed to ooze out from the pen core. Any characters written with this felt-tip pen could be erased with a commercially available eraser. However, No.1 without adding methylcellulose~
The dispersion stability of compositions No. 4, No. 9 and No. 10 was determined by
When compared with other compositions containing methylcellulose, it was confirmed that the composition containing methylcellulose exhibited superior dispersion stability. For comparison, when polyethylene oxide having a molecular weight of about 20,000 was used, the ink characters easily permeated into the paper, making it difficult to erase them with an eraser.

Claims (1)

[Claims] 1 A non-emulsion water-insoluble organic pigment other than aniline black is dissolved in an aqueous medium in which at least one water-soluble polymer selected from polyethylene oxide with a molecular weight of 100,000 or more and alkylene glycol alginate and methyl cellulose are dissolved. An ink composition for paper, which is characterized in that characters and designs written on paper can be erased with an eraser, the composition being uniformly dispersed in the presence of a surfactant if necessary.