JPH0352502B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a colorless dye-developer ink that can provide dark, clear and sharp handwriting, and that can be easily erased using a desensitizer made of a polar compound. It is something. Color is developed by the exchange of electrons between a color developer having a phenolic hydroxyl group and a colorless electron-donating organic compound (colorless dye) that is colored by this color developer.
Writing means that utilize a reversible reaction in which color development due to the exchange of electrons is inhibited by a desensitizer, which is a polar compound, and become colorless have been proposed. For example, a writing material made of a dye with a color developing component structure in the molecule (colorless dye), a compound with an acidic hydroxyl group in the molecule (developer), and a polar solvent (desensitizer) was published in 1973. Listed in 21649. This writing material aims to be a special ink that is colorless until just before writing, and the handwriting only appears after the writing is done by the volatilization of the polar solvent.Since the handwriting cannot be confirmed at the same time as the writing, it is different from ordinary ink for writing instruments. It is not suitable as Furthermore, Japanese Patent Publication No. 51-48085 describes an electron-donating organic compound (colorless dye), a compound having a phenolic hydroxyl group (color developer), and a non-volatile compound (desensitizing dye) that desensitizes the color reaction of the two compounds. A coloring agent for writing instruments is described. Handwriting made with such coloring agents is colored immediately after writing, but it can be made colorless or discolored by volatilizing the color developer in the handwriting by heating or washing it out with water. Unlike ordinary ink, it is not possible to obtain solid, stable handwriting that does not change or fade over time. Therefore, the present inventors have proposed that if a color developer and a colorless dye that is colored by the developer are dissolved in a solvent that does not inhibit this color reaction, the colorless dye-color developer type ink can be used to write the color. Ability to produce dark and clear handwriting similar to regular oil-based ink;
This ink does not contain a desensitizer, which is a polar compound that makes the colorless dye colorless, so the handwriting does not have to worry about fading or discoloration over time caused by the desensitizer. He discovered that erasing could be done easily and completely using an erasing material made of a sensitive material, and had already applied for a patent (patent application filed in 1983).
212257 and others). Many types of compounds can be considered as color developers with phenolic hydroxyl groups that can be used in such colorless dye-color developer inks, but the stability of the color developer present in handwriting depends on the vertical shape of handwriting. Subsequent research has revealed that it has a significant impact on prison performance. Among the many color developers, novolac type phenolic resin in particular exists stably without being volatilized or removed by heat, light, water, etc. in the outside world, so it can produce solid handwriting without fading in the density of the handwriting when writing. I discovered what I could give. Furthermore, it has been found that when a novolak type phenolic resin is used as a color developer, aromatic alcohol or ethylene glycol monophenyl ether can be effectively used as a solvent for the color developer and colorless dye. The present invention has been made based on the above-mentioned new findings. That is, the erasable colorless dye-developer ink of the present invention combines a color developer made of a novolak type phenolic resin and a colorless electron-donating organic compound (colorless dye) that develops color with the color developer. It is obtained by dissolving it in a solvent consisting of a group alcohol and/or ethylene glycol monophenyl ether. Since the aromatic alcohol and ethylene glycol monophenyl ether used as a solvent in the present invention are polar compounds, they have a desensitizing effect, and therefore, at first glance, they appear to inhibit the color development reaction in colorless dye-developer type inks. It cannot be used as an ink solvent. Despite that,
The reason why these polar solvents can be used as effective solvents in the present invention is inferred as follows. In other words, aromatic alcohols and ethylene glycol monophenyl ether dissolve novolak-type phenolic resin color developers and colorless dyes very well and promote the color reaction, so the color reaction is more effective than the desensitizing effect of these polar solvents. is considered to be dominant. Further, since such a polar solvent dissolves the colorless dye and the color developer well, an ink with practically good physical properties without the risk of precipitation of insoluble matter etc. over time can be obtained. It was totally unexpected that polar compounds with a desensitizing effect, such as aromatic alcohols and ethylene glycol monophenyl ether, could be used as effective solvents when used in combination with a novolak-type phenolic resin developer. As mentioned above, in the present invention, a novolak type phenolic resin is used as a color developer, so that safe, solid handwriting that does not fade or disappear even if external conditions such as heat, light, and water are applied after writing is achieved. can be given. Non-volatile color developer having a phenolic hydroxyl group other than novolak type phenolic resin,
For example, when nonylphenol, 2,2-methylenebis(4-methyl-6-tert-butylphenol), bisphenol F, phenolic resin initial condensate, etc. are used, they have the effect of coloring colorless dyes, but The density of handwriting tends to fade over time. For example, when using a liquid color developer such as nonylphenol, the nonylphenol in the handwriting is absorbed by the paper, resulting in more than 50% discoloration after one day at room temperature. When used as a coloring agent, more than 50% discoloration is observed after one day, and more than 90% discoloration after one month. On the other hand, when a novolak type phenolic resin is used, the color hardly fades even after 7 days at 50°C. As the colorless dye used in the present invention, a colorless electron-donating organic compound that develops color with a novolak type phenolic resin developer can be used. For example, phthalide color-forming organic compounds such as crystal violet lactone and malachite green lactone; 3-dimethylamino-6-methoxyfluoran, 3,6-diethoxyfluoran, 1,
2-benz-6-diethylaminofluorane, 2
-anilino-3-methyl-6-pyrrolindino-fluorane, 3',6'-bis-(diethylamino)spiro-(phthalan-1,9'-xanthine), 1,1
-Fluorane-based color-forming organic compounds such as bis-(p-aminophenyl)-phthalane; Spiropyran-based color-forming organic compounds such as di-β-naphtho-spiropyran, xantho-β-naphtho-spiropyran, and benzo-β-naphtho-isospiropyran Compounds etc. can be used. The amount of colorless dye used is 10 to 10% of the total amount of ink.
About 30% by weight is preferable in terms of ink concentration and ink dissolution stability. In addition, the ratio of novolak type phenolic resin developer and colorless dye is 1:3~
A ratio of 10:1 is more preferable in terms of color density and color stability of the ink. In the present invention, aromatic alcohol and/or ethylene glycol monophenyl ether can be preferably used as a solvent for dissolving the color developer and colorless dye. As mentioned above, these are polar compounds that have a desensitizing effect, but because they dissolve the color developer and colorless dye extremely well, the color reaction between the two is promoted, and therefore the developer has a desensitizing effect that overcomes the desensitizing effect of polar solvents. It is thought that the color developing effect of the coloring agent is developed, 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 to be used is preferably about 25 to 50% by weight based on the total amount of ink from the viewpoint of stability and fluidity of the ink. Furthermore, various additives commonly used for adjusting the viscosity and lubricity of ink can also be appropriately selected and used as necessary. Next, to briefly describe the method for manufacturing the ink used in the present invention, the color developer, colorless dye, and solvent are mixed using equipment normally used for ink manufacturing, such as a kneader, three-roll roll, and a heating stirring mixer. easily obtained by In addition, when adding other additives as necessary, they may be added to the above components and mixed in the same manner. The ink thus obtained is stored in the ink storage part of conventionally used ballpoint pens, felt pens, felt-tip pens, markers, etc., supported by the pen shaft, and leached from the pen tip. It can be used as a brush. As can be seen from the above explanation, the ink according to the present invention contains a colorless dye that has already developed a deep color with the ink developer, and does not contain a desensitizer, so it can be used similarly to ordinary writing ink. This handwriting can be easily and completely erased using desensitizers. In particular, in the present invention,
A novolak type phenol resin was used as a color developer, and aromatic alcohol and/or ethylene glycol monophenyl ether, which dissolves this color developer and colorless dye extremely well, were used as a solvent, so it is resistant to external heat, light, water, etc. On the other hand, it is possible to provide stable handwriting without worrying about fading or discoloration over time, and at the same time, it is possible to obtain an ink with good physical properties that does not cause precipitation of insoluble matter over time. It is. The present invention will be further explained below by giving Examples and Comparative Examples. Note that "parts" in the examples indicate parts by weight. Example 1 Novolac type phenolic resin "Tamanol PA" (manufactured by Arakawa Chemical Co., Ltd.) 30 parts Fluorane colorless dye "BK-14" (manufactured by Yamada Chemical Industry Co., Ltd.) 20 parts benzyl alcohol 20 parts ethylene glycol monophenyl ether 30 parts The above formulation was heated and dissolved at 100° C. for 1 hour, and then a small amount of insoluble matter was removed by filtration to obtain a black colored ink of the present invention. This ink is used in a ballpoint pen (JIS S-6039-1980
Fill the paper (E type for fine print) and draw a line on paper (JIS P-3201 writing paper A) to examine the handwriting when writing, and also examine the change over time when this handwriting is left at 50℃ for 7 days. Ta. The results are shown in Table 1. Comparative Example 1 Bisphenol F [Developer] 30 parts Fluorane colorless dye "BK-14" 20 parts Benzyl alcohol 20 parts Ethylene glycol monophenyl ether 30 parts Bisphenol was used as the developer for the novolac type phenol resin in Example 1. The handwriting during writing and its change over time were examined in the same manner as in Example 1 except that F was used instead. The results are shown in Table 1. Comparative Example 2 Novolac type phenolic resin "Tamanol PA" 30 parts Fluorane colorless dye "BK-14" 20 parts Diethylene glycol monophenyl ether 30 parts The solvents of benzyl alcohol and ethylene glycol monophenyl ether in Example 1 were replaced with diethylene glycol monobutyl ether. Other than that, the handwriting during writing and its change over time were examined in the same manner as in Example 1. The results are shown in Table 1. Table 1 Handwriting left at 50℃ for 7 days Example 1 Clear black line Almost no change Comparative Example 1 Clear black line Approximately 90% discoloration * Comparative Example 2 Almost colorless Black line annotation * Hunter Color Difference Meter Calculated by measuring the Y value (reflectance). For example, the Y value of paper is 70
%, the Y value of the handwriting immediately after writing is 56%, and the difference between the two is
If the Y value of the handwriting is 14% and the Y value of the handwriting becomes 63% after a certain period of time and the difference from the Y value of the paper becomes 7%, it is considered 50% fading, and the Y value of the handwriting becomes 70% and the Y value of the paper becomes 7%. 100% if the difference from the value is zero
The color faded. As can be seen from Table 1, the ink of Example 1 according to the present invention can be used to write clear lines similar to oil-based ballpoint pen ink, and these lines did not fade even in a forced test at 50°C for 7 days. Therefore, it is suitable as an ink that leaves a clear record. On the other hand, Comparative Example 1 is no different from Example 1 in writing, but the color fades over time, so it is not suitable as an ink for stably leaving records. From this, it can be seen that as a color developer, novolak type phenolic resin provides more stable color development than bisphenol F, that is, gives a sharper handwriting. Furthermore, in Comparative Example 2, the handwriting was almost colorless and difficult to read. This is considered to be because the coloring reaction between the color developer and the colorless dye was hindered because a polar compound with a strong desensitizing effect was used as the solvent. However, the handwriting became dark in color after the solvent evaporated, and because a novolak type phenolic resin was used as the color developer, almost no discoloration of the handwriting over time was observed. On the other hand, an ink eraser consisting of 7.5 parts of N-vinylpyrrolidone-vinyl acetate copolymer [a desensitizer that is solid at room temperature], 89.5 parts of ethanol [a solvent], and 3 parts of high molecular weight polyvinylpyrrolidone was used with an oil-based marker (Pentel Co., Ltd.). When the black ink handwriting obtained in Example 1, Comparative Example 1, and Comparative Example 2 was rubbed 2 to 3 times into a part made by M-10), all handwriting could be completely erased. did it. Example 2 Novolac type phenolic resin “Tamanol PA”
30 parts fluoran colorless dye “PSD150” (Shin Nisso Kako Co., Ltd.)
Co., Ltd.) 25 parts β-phenylethyl alcohol 43 parts Oleic acid [Lubricant] 2 parts The above mixture was heated and dissolved at 100°C for 1 hour, and a small amount of insoluble matter was removed by passing. An ink of the present invention which developed a black color was obtained. Using a test piece of paper (JIS P-3201 writing paper A) coated with this ink, the degree of discoloration was measured after applying it to a fade meter for 5 hours, the degree of discoloration after being left at 50℃ for 7 days, and the degree of discoloration after being soaked in water. The color change after 10 hours of immersion was examined. The results are shown in Table 2. Comparative Example 3 Nonylphenol [Developer] 30 parts Fluorane colorless dye "PSD150" 25 parts β-phenylethyl alcohol 43 parts Oleic acid [Lubricant] 2 parts The color developer for the novolak type phenolic resin in Example 2 In the same manner as in Example 2 except that nonylphenol was used, the degree of discoloration was measured after 5 hours in a fade meter, the degree of discoloration after being left at 50°C for 7 days, and the color change after immersed in water for 10 hours. Ta. At the same time, Comparative Example 1 and commercially available oil-based ballpoint pen inks were also tested in the same manner. The results are shown in Table 2.

[Table] Le Pen
As can be seen from Table 2, the degree of fading of the ink of Example 2 according to the present invention is almost comparable to that of a commercially available oil-based ballpoint pen, and the color change after 10 hours of immersion in water was as follows.
It exhibited superior durability compared to commercially available oil-based ballpoint pens. On the other hand, the inks of Comparative Examples 1 and 3 easily faded, and it was not possible to obtain sharp handwriting. In addition, Example 2 was carried out using the above-mentioned ink erasing material.
And the black ink handwriting obtained in Comparative Example 3 is
After rubbing it three times, I was able to completely erase all handwriting.

Claims (1)

[Claims] 1. A colorless dye obtained by dissolving a color developer made of a novolac-type phenolic resin and a colorless electron-donating organic compound that develops color with this color developer in a solvent made of aromatic alcohol and/or ethylene glycol monophenyl ether. -Developer-based ink.