JPH0422948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel writing ink, particularly a writing ink that allows for dark and clear writing, and also enables handwriting to be erased with a special erasing material if necessary. be.

Various methods have been developed for erasing ink handwriting. For example, (1)
A method of erasing handwriting made with ink using easily bleachable dyes with bleach; (2) A rubber-like polymer substance mixed with a coloring material is dissolved in a solvent to form ink, and the handwriting made with this ink is erased with an eraser. There are ways to do this. However, method (1) has the disadvantage that the erased marks tend to yellow and the bleaching agent has poor stability over time. On the other hand, method (2) requires a pressurized ballpoint pen structure because the ink becomes highly viscous, and is not necessarily satisfactory in terms of erasing performance.

A writing method has also been proposed that utilizes a reversible reaction in which a color is developed by the exchange of electrons between a color-forming substance and a color developer, and the color is rendered colorless by inhibiting the exchange of electrons with a desensitizer. For example, dyes with a color-developing component structure within the molecule (color-forming substances) and compounds with acidic hydroxyl groups within the molecule (color-developers)
A writing material consisting of a polar solvent (desensitizer) and a polar solvent (desensitizer) is described in Japanese Patent Publication No. 1983-21649. This writing material is designed to be a special ink that is colorless until just before writing, and the handwriting only appears after the writing due to the volatilization and evaporation of the polar solvent.Since the handwriting cannot be confirmed at the same time as it is written, it cannot be used with ordinary writing instruments. Not suitable as ink. In addition,
48085 includes electron-donating organic compounds (color-forming substances)
and a compound with a phenolic hydroxyl group (color developer)
and a nonvolatile compound (desensitizer) that desensitizes the color reaction of the two compounds. Handwriting made with such a coloring agent is colored immediately after writing, but it can be made colorless by volatilizing the color developer in the handwriting by heating or washing it out with water. However, such erasing means is not as simple as using an eraser or erasing liquid, and therefore is not suitable for use as an erasable ink for ordinary writing instruments.

SUMMARY OF THE INVENTION An object of the present invention is to provide a new writing ink that allows for writing darker and clearer than a pencil, and also allows for easy erasing of handwriting as needed.

That is, the gist of the present invention is a writing ink comprising a color developer having a phosphoric acid group, a colorless electron-donating organic compound that develops color with the color developer, and a solvent that does not inhibit the color reaction. be.

The writing ink of the present invention contains an electron-donating organic compound that is colored by a color developer, and has a dark color similar to ordinary oil-based ink, so it can produce dark and clear handwriting. can bring.

The color developer having a phosphoric acid group used as an ink component is sufficiently non-volatile (preferably melting point is 100°C or higher) to the extent that handwriting does not fade over time.
Any substance can be used without particular limitation as long as it has a solubility in a solvent to the extent that it can be formed into an ink, such as phenylphosphonic acid, 1,3-dimethyl-phenylsulfonic acid, diphenylphosphinic acid, ter-butyl -Phenylsulfonic acid and the like. These color developers may be used alone or in combination of two or more.

Examples of colorless electron-donating organic compounds that develop color with the above color developer include phthalide-based color-forming organic compounds such as crystal violet lactone and malachite green lactone; 3-dimethylamino-6-methoxyfluoran; 3,6-diethoxyfluorane, 1,2-benz-6-diethylaminofluorane, 2-anilino-3-methyl-6-pyrrolindino-fluorane, 3'.6'-bis-
(diethylamino)spiro-(phthalane-1,9'-xanthine), 1,1-bis-(p-aminophenyl)-
Fluoran-based color-forming organic compounds such as phthalane;
Di-β-naphtho-spiropyran, xantho-β-
Spiropyran-based color-forming organic compounds such as naphtho-spiropyran and benzo-β-naphtho-isospiropyran can be used.

The amount of the electron-donating organic compound to be used is preferably about 1 to 140% by weight based on the total amount of the ink in terms of ink concentration and ink dissolution stability. Further, the ratio of the color developer to the electron-donating organic compound is 1:3 to 1:3.
A ratio of 20:1 is more preferable in terms of color density and color stability of the ink.

The ink solvent should be one that does not inhibit the color-forming reaction between the above-mentioned color developer and the electron-donating organic compound.
Any material can be used without particular limitation as long as it can dissolve them. For example, aromatic alcohol and/or ethylene glycol monophenyl ether can also be preferably used. Since these solvents are polar compounds, they have a desensitizing effect and therefore, at first glance, they cannot be used as ink solvents because they inhibit the color development reaction in colorless dye-developer type inks. Nevertheless, the reason why these polar solvents can be used as effective solvents in the present invention is that they dissolve the color developer and the colorless dye very well, promoting the color-forming reaction between them, and therefore the polar solvent It is thought that the color developing effect of the color developer is superior to the desensitizing effect, and a dark and clear colored ink is obtained. Examples of the aromatic alcohol include benzyl alcohol, β-phenylethyl alcohol, 3-phenyl-1-propanol, 4-phenyl-2-butanol, and methylphenyl carbinol. on the other hand,
Among the glycols, ethylene glycol monophenyl ether was particularly used because its desensitizing effect is weaker than that of other glycols. These solvents may be used alone or in combination of two or more.
The amount of solvent used is 25 to 50% by weight based on the total amount of ink.
from the viewpoint of ink stability and fluidity.

Furthermore, a resin that does not prevent color development may be used to adjust the viscosity of the ink and the fixability of handwriting, and a lubricant may be appropriately selected and used as necessary to adjust the lubricity of the ink.

Next, to briefly describe the method for producing the ink of the present invention, the color developer, electron-donating organic compound, and solvent are mixed using equipment normally used for ink production, such as a kneader, three-roll roll, and a heated stirring mixer. can be easily obtained by Incidentally, when adding resins, lubricants, etc. as necessary, they may be added to the above components and mixed in the same manner.

The ink thus obtained can be used as ink for dip pens, or it can be stored in the ink storage part of conventionally used ballpoint pens, felt pens, felt pens, markers, fountain pens, etc. and supported on the pen shaft. It can be used as a pen-shaped writing instrument that exudes water from the pen tip or as a recording instrument for printers and the like.

Handwriting based on the above ink can be easily erased, if necessary, with an erasing material containing a desensitizing polar compound such as alcohol, ketone, ester, ether, amine, or amine. That is, it is thought that the color-forming complex produced by the reaction between the color developer and the electron-donating organic compound is decomposed by the desensitizing action of the polar compound, resulting in complete colorlessness.

The present invention will be further explained below with reference to Examples. Note that "parts" in the examples indicate parts by weight.

Example 1 Phenylphosphonic acid 25 parts Crystal violet lactone 15 parts Benzyl alcohol 30 parts Phenyl glycol 20 parts Nicanol HP20 (resin, manufactured by Mitsubishi Gosei Chemical Co., Ltd.)
15 parts The above formulation was heated at 100° C. for 1 hour to dissolve it, and then filtered to remove a small amount of insoluble matter to obtain a blue colored ink. When I filled this ink into a ballpoint pen (JIS-S-6039-1980 E type for fine print) and drew a line on paper (JIS-P-3201 writing paper A), I was able to write smoothly just like regular ballpoint pen ink. , a clear blue line was obtained.
This line remained robust without fading even after being left at 50°C for 10 days.

In addition, the above lines can be completely erased by gently wiping them with paper soaked in a 30% dioctyl adipate acetone solution, and the color does not return even after being left at 50℃ for 10 days, ensuring stable erasability. Indicated.

Example 2 Diphenylhoffuic acid 15 parts 2-anilino-3-methyl-6-pyrrolindino-
Fluoran 15 parts β-phenylethyl alcohol 15 parts Benzyl alcohol 35 parts Phenyl glycol 20 parts The above mixture was heated at 100°C for 1 hour to dissolve it, and then filtered to remove a small amount of insoluble matter. A black colored ink was obtained. When this ink was filled into an oil-based marker component (MM50, manufactured by Pentel Co., Ltd.) and a line was drawn on paper (JIS-S-3201 writing paper A), a clear black line was obtained. This line remained robust without fading even after being left at 50°C for 10 days.

As can be seen from the above explanation, since the ink used for writing according to the present invention contains an electron-donating organic compound that has already been darkly colored by a color developer, it is darkly colored like normal writing ink. It is possible to produce clear handwriting, and furthermore, the handwriting made with the above ink can be easily and completely erased if necessary using a desensitizing polar compound that makes the colored electron-donating organic compound colorless. It has excellent characteristics.

Claims (1)

[Scope of Claims] 1. A writing ink comprising a color developer having a phosphoric acid group, a colorless electron-donating organic compound that develops color with the color developer, and a solvent that does not inhibit the color development reaction. 2. The writing ink according to claim 1, wherein the color developer having a phosphoric acid group is a compound having a melting point of 100°C or higher.