JPS60190479A - Erasable ink composition - Google Patents

Abstract

PURPOSE:An ink composition erasable with an alkali, heat, etc., having stable recording properties during reprinting, obtained by blending basic dye such as azo type, etc. as a main agent of ink with thiourea dioxide. CONSTITUTION:One or more dyes of azo type, methine type and triphenyl type basic dye are used as a main agent of ink, it and thiourea dioxide are dissolved in an aqueous solvent such as water, etc., to give the desired ink composition. In erasing with heat, mistaken record is traced with a hot brush pen so that thiourea dioxide is decomposed, and a sulfinic acid is liberated. In erasing with an alkali, mistaken record is traced with an alkali aqueous solution, so that thiourea dioxide is neutralized and it is erased.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an erasable ink composition used, for example, in a pen-type recording device, and more specifically to an alkali ink composition containing a specific basic dye and thiourea dioxide. and/or relates to an ink composition that can be decolorized by heat.

(Prior art and its problems) In recent years, in recording devices such as pen typewriters,
It has come to be used to erase errors and make it possible to rewrite. Such a recording device generally uses an ink composition whose main ingredient is one or more dyes selected from basic dyes that can be erased with a sulfite-based reducing agent. Therefore, in the past, when writing was performed using this ink composition and an error occurred, the color was erased using a color erasing liquid in which a sulfite-based reducing agent was dissolved. However, if you try to write again on the area that has been erased by the sulfite reducing agent, there is the inconvenience that the area you have written on again will also be erased because the erasing effect of the sulfite reducing agent remains. Ta. For this reason, rewriting is performed using a different ink composition that is not erased by the sulfite-based reducing agent, or after the erasing liquid is neutralized with a neutralizing liquid to eliminate its erasing action. For example, in the case of a pen-type recording device, this means that a total of three pens are required: an erasable ink pen, an erasable liquid pen, and a non-erasable ink pen or a neutralizing liquid pen. Therefore, it is inevitable that the printing mechanism will become complicated and the cost will increase.

Equity No. 11J (No. 54-22344) contains a sulfite-based reducing agent, which is made by adding a basic dye to an essential medium to make it the main ink ingredient, and further adding an acidic substance to this aqueous medium as an ink auxiliary agent for color reproduction. proposed an ink composition capable of erasing 0f. According to this ink composition, when errors are erased with an erasing liquid containing a sulfite-based reducing agent,
The remaining color erasing liquid is neutralized or decomposed by the acidic substance contained in the ink composition, and the color erasing effect is erased.
There is an advantage that the color will not be erased even if writing is performed again from that =1-.

However, in this ink composition, the neutralization or decomposition reaction of the remaining decolorizing liquid by the acidic substance does not occur quickly, so as shown in the example, the characters gradually appear in the first writing in +tf writing. They often faded and eventually disappeared, and there remained concerns that the records of the rewritten characters were not reliable.

(Object of the Invention) The object of the present invention is to provide an erasable ink composition that can be rewritten after erasing errors, and can provide stable recording performance even in rewriting. Our goal is to provide the following.

(Structure of the Invention) The ink composition according to the present invention uses one or more dyes selected from azo-based, methine-based, and triphenyl-based basic dyes as an ink main ingredient, and thiourea dioxide is blended therein. , the color is erased by alkali and/or heat.

- Thiourea oxide is a stable compound that has neither oxidizing nor reducing properties under normal conditions, and even if it is blended into an ink composition, it will not adversely affect recording performance. However, thiourea dioxide is decomposed by heat or alkali as shown in the following formula to liberate sulfinic acid.

HN: G (SO, H) NO3 + H20 heat → 82 NG
(:0)NO3+ 82504HN:C(So□H)N
H2+ 2NaOH-+H2NG(:0)NH2+ N
a,SO,,+H,,0 Sulfinic acid has a strong reducing power and has the effect of reacting with dyes and decolorizing them. In addition, sulfinic acid is extremely unstable and decomposes when oxidized in the air, losing its reducing power. Therefore, after decoloring, the decoloring effect hardly remains.

Therefore, according to the present invention, when writing is performed using an ink composition containing thiourea dioxide, and when an error occurs, the color is erased with alkali and/or heat, and the thiourea oxidation is re-discolored from -1-. Re-writing can be performed using the ink composition contained. This results in
For example, when the present invention is applied to a pen-type recording device, etc., errors can be erased and rewritten using two pens, a writing pen and an erasing pen, simplifying the printing mechanism. Cost reduction can be achieved.

In the present invention, one or more dyes selected from azo, methine, and triphenyl basic dyes are used. Examples of azo dyes include C,1, Basic Yellow 3B, C,1, Basic Blue 65, G,
Examples of methine dyes include C, R, and Basic Yellow 14.
, C,1, and Basic Violet 21. Examples of triphenyl dyes include malachite green and crystal violet. The concentration of dye in the ink composition is 0.1 to 10% by weight
is appropriate. Further, the amount of thiourea dioxide to be blended cannot be unconditionally determined as it is an amount that can liberate an amount of sulfinic acid that can erase the dye concentration in the ink.

Then, the ink composition according to the present invention can be obtained by dissolving these components in an aqueous solvent such as water. In order to prevent evaporation and drying, a non-volatile solvent such as an alkylene glycol such as ethylene glycol or propylene glycol, a polyalkylene glycol such as polyethylene glycol or polypropylene glycol, or a polyhydric alcohol such as glycerin is added to the aqueous solvent. May be added. Moreover, in order to promote evaporation, a volatile solvent such as methanol or ethanol may be added. The amount of these solvents to be added is usually 5 to 30% by weight.

As means for decolorizing the ink composition according to the present invention,
Heat or alkali is used. In the case of heat, for example, a method of tracing the errors with a heated marker is adopted.

The thermal pen is a pen that can instantly raise the temperature to 50 to 100°C, thereby rapidly decomposing thiourea dioxide in the ink composition and liberating sulfinic acid. In addition, when using a hot spot pen, the erased area dries immediately, which has the advantage that no smudging occurs when writing again. In the case of using alkali, for example, a method is adopted in which an alkaline aqueous solution is used as a color erasing liquid to trace the errors. In this case, the alkalis to be used include strong alkalis such as thorium hydroxide, weak alkalis such as calcium hydroxide, etc.・Various types of salts such as salts of strong alkalis and weak acids such as sodium lipolyphosphate can be used. The concentration of alkali in the decolorizing solution is preferably such that it is substantially neutralized after reacting with thiourea dioxide. Furthermore, alkali and heat can be used together as a color erasing means. In that case, trace the errors with abrasive color erasing liquid and heat the paper with appropriate heating means.

(Embodiment of the Invention) The figure shows an example of a pen-type recording device to which the present invention is applied, and is mainly composed of a Y cursor l that moves in the Y direction and an X cursor 2 that moves in the X direction. ing.

The Y cursor 1 has a waiting groove 1a for the ink pen 4 to be erased,
A standby groove 1b for the hot spot pen 5 is formed. Also,
The X cursor 2 is provided with a holding body 3, and a holding groove 3a is formed in this holding body 3. Therefore, each pen 4.
5 is selectively held in the holding groove 3a of the holder 3, and by adjusting the amount of movement of the Y cursor 1 and the X cursor 3, arbitrary characters and figures can be drawn on the recording paper 7. ing.

The erasable ink pen 4 is filled with the ink composition according to the present invention. As an example, 1.5 parts by weight of malachite green and 1.5 parts by weight of thiourea dioxide are added to 7 parts of water.
A blue ink dissolved in a solution consisting of 5 parts by weight and 15 parts by weight of polyethylene glycol can be used.

Therefore, the ink pen 4 to be erased is held in the holding groove 3 of the holding body 3.
When the user draws arbitrary characters or figures on the recording paper 7 by moving the Y cursor 1 and the X cursor 2 while holding the cursor at the position a, blue writing is done. When an error occurs, the ink pen 4 to be erased is returned to the standby groove 1a of the Y cursor 1, the hot spot pen 5 in the standby groove 1b is held in the holding groove 38 of the holder 3, and the Y cursor l and When the X cursor 2 is moved to trace an area where a typo has occurred, the area is instantaneously heated to a temperature of 50 to +00°C by the hot spot pen 5.

As a result, thiourea dioxide in the ink composition is decomposed to liberate sulfinic acid, and the reducing power of the sulfinic acid decomposes the dye and erases the color. More heat spot pen 5
The heat can quickly dry the writing area.

After the liberated sulfinic acid reacts with the dye and decolorizes it,
It decomposes due to air oxidation and loses its reducing power. After that, return the thermal marking pen 5 to the standby groove tb again, hold the erasable ink pen 4 in the standby groove 1a in the holding groove 38 of the holder 3, move the Y cursor 1 and the X cursor 2, and write again. I can do it.

Furthermore, instead of the hot spot pen 5, a decoloring liquid pen filled with an alkaline aqueous solution can be used. As the alkaline aqueous solution, for example, a 2% by weight aqueous solution of sodium hydroxide is used. When a erroneous note is traced with this color erasing liquid pen, thiourea dioxide is decomposed by the alkali, sulfinic acid is liberated, and the color can be immediately erased.

In this case, almost no odor can be detected. Since the alkali reacts with thiourea dioxide and is almost neutralized, it is possible to write again using the erasable liquid pen 4.

(Effects of the Invention) As explained above, according to the present invention, since thiourea dioxide is blended with a specific basic dye, thiourea dioxide is decomposed by alkali and/or heat to liberate sulfinic acid. The reducing power of sulfinic acid can decompose the dye and erase the color. The liberated sulfinic acid is air oxidized and quickly loses its reducing power, so it can be rewritten with the original ink composition. Therefore, when the ink composition of the present invention is applied to, for example, a pen-type recorder, two pens are used: an erasable ink pen containing the ink composition and a hot spot pen or an erasing liquid pen containing an alkaline solution. As a result, writing, erasing, and rewriting can be performed repeatedly, and the printing mechanism can be simplified.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a pen-type recording device using an ink composition according to the present invention. In the figure, 4 is an erasable ink pen, and 5 is a hot spot pen. Figure 1

Claims (1)

[Claims] The ink is made of one or more dyes selected from azo, nothine, and triphenyl basic dyes, and thiourea dioxide is added to the ink.The color can be erased by alkali and/or heat. ink composition.