JP2005154682A - Handwriting erasing liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a handwriting erasing liquid which is satisfactory in erasing a handwriting well written with a good color-developing writing ink while giving a erased state stable and hardly changing with time, which is stable itself, superior in safety without containing heavy metals and the like, and which is rewritable in the erased part with the same writing ink. <P>SOLUTION: The handwriting erasing liquid comprises at least a reducing sulfur compound, a recoloring inhibitor and water, and is characterised in that the recoloring inhibitor is a specified polyethyleneimine and/or a polyethyleneimine derivative. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an erasing liquid for erasing handwriting written with a writing ink using a dye that can be decolorized by a reducing sulfur compound. More specifically, the erasing liquid has good erasability, and the erasing state changes with time. The present invention relates to a handwriting erasing liquid that is difficult to rewrite using the same writing ink for the erasure part.

  Conventionally, as a erasing liquid for writing ink, a sulfite system for erasing handwriting written with a writing ink using a basic dye as a coloring material as proposed in JP-A-53-65123. An erasing solution using a reducing agent is known. However, a basic dye as a colorant has difficulty in water solubility and erasability, and could not be a good erasable writing ink. In addition, the conventional erasing liquid has problems such as insufficient rewriting after erasing and a problem of recurrent color.

  On the other hand, dyes that can be decolored with a reducing sulfur compound such as triallylmethane acid dyes have been used in writing inks, and erasers for erasing them have already been marketed. Since the above dyes have good erasability and good water solubility, they may be used as washable inks and are also suitably used as writing inks for erasing. However, since these erasers cannot be rewritten with the same ink after erasing, it is necessary to separately prepare rewriting ink that cannot be erased with the eraser in order to rewrite.

  To solve this problem, a technique for erasing and rewriting using the same ink has been proposed. In USP 4,213,717, USP 4,228,028, EP 0,032,652, C.I. which is a dye that can be decolorized with a triallylmethane dye, that is, a reducing sulfur compound. I. Acid Blue 22, 93 or the like is used as a dye for writing ink, and amine is disclosed as an erasing agent for erasing this. However, these techniques require the use of a strong base in order to activate the amine, and the erasing solution becomes strongly alkaline, which has the problem that the paper is damaged during erasing and cannot be rewritten. .

  USP 5,006,171 uses a reducing sulfur compound as an erasing agent for the purpose of solving these problems. In order to improve long-term storage stability without using a strong base. A method of adding a large amount of sugar alcohol such as sorbit has been proposed. In the present invention, since a strong base is not used, paper damage can be reduced. However, in order to obtain storage stability, it is necessary to add a large amount of sugar alcohol of several tens of percent. The physical properties of the erasing liquid were not suitable, such as an increase in viscosity.

  US Pat. No. 5,378,752 proposes a method of reducing film damage during erasing by including a film-forming polymer in an erasing solution in an erasing system using a sulfite-based reducing agent. There was a problem that letters recolored over time.

  Furthermore, USP 5,649,999 has proposed a erasing / rewriting system that uses a writing ink that decolorizes when contacted with an amine and uses an aqueous amine solution as a erasing agent. This is intended to enable rewriting. A water-soluble heavy metal salt that binds to an amine is added to the writing ink, and the use of the heavy metal salt is not preferable from the viewpoint of safety.

  As described above, in these background technologies, the erasability is good, the erased state is stable and hardly changes over time, the eraser itself is stable, and the erased portion can be rewritten using the same writing ink. No satisfactory proposal has been made regarding the liquid.

JP-A-53-65123 USP 4,213,717 USP 4,228,028 EP0,032,652 USP 5,006,171 USP 5,378,752 USP 5,649,999

  Good erasability of handwriting written well with writing ink with good color development, its erased state is stable and difficult to change over time, the erasing liquid itself is stable, and it has excellent safety without heavy metals, It is an object of the present invention to provide a handwriting erasing liquid that can be rewritten using the same writing ink for the erasure portion, and proposes means for solving such a problem.

As a result of diligent research, the present inventor, in order to solve the above-mentioned problem, uses a writing ink using a dye that can be decolorized by a reducing sulfur compound, and after writing well with good color development, safely and stably In order to erase the handwriting, the handwriting erasing solution of the present invention was completed by using a handwriting erasing solution comprising at least a reducing sulfur compound, a recurrent color preventing agent and water.
That is, the present invention
“1. A reductive sulfur compound that erases handwriting written with a writing ink using a dye that can be decolorized by a reductive sulfur compound, an anti-recuring colorant, and an erasing solution that is at least from water, A rewritable handwriting erasing solution, wherein the recoloration inhibitor is a polyethyleneimine and / or a polyethyleneimine derivative having a number average molecular weight of 1,000 or more.
2. 2. The handwriting erasing solution according to item 1, wherein the recurrent color preventing agent is a polyethyleneimine derivative having an added tertiary amine structure in the main chain.
3. The handwriting erasing solution according to any one of Items 1 and 2, wherein the anti-recoloration agent is a polyethyleneimine derivative having an alkyl group-added tertiary amine structure in the main chain.
4). 4. The handwriting erasing solution according to any one of items 1 to 3, wherein the recurrent color preventing agent is a polyethyleneimine propylene oxide adduct.
5). 5. The handwriting erasing solution according to any one of Items 1 to 4, wherein the dye decolorizable with the reducing sulfur compound is a triallylmethane acid dye. ".

  According to the erasing solution, etc., the erasability of the handwriting well written with good coloring ink is good, the erased state is stable and hardly changes over time, the erasing solution itself is stable, heavy metals, etc. It has an excellent effect of being able to obtain a handwriting erasing liquid which is excellent in safety and does not contain odors and which can be rewritten using the same writing ink for the erased portion.

The present invention will be specifically described below.
The present invention uses a writing ink using a dye that can be decolorized by a reducing sulfur compound such as a triallylmethane acid dye, and after writing well with good color development, it is erased by using the handwriting erasing solution of the present invention. It is very useful as a handwriting eraser that can be rewritten with the same writing ink.

  In the present invention, the mechanism capable of erasing the handwriting and rewriting with the same ink can be shown as follows. First, the handwriting written with the dye is redissolved in an erasing solution containing a large amount of water and the dye is eluted. Second, the redissolved dye is reacted with the reducing sulfur compound in the erasing solution. Then, through a process of decoloring and thirdly, a process of diffusing and penetrating the erasing liquid into the paper, good erasure of the handwriting and stable maintenance of the erased state are performed.

  Here, as the coloring material of the writing ink, a dye that can be decolored by a reducing sulfur compound such as a triallylmethane acid dye is used. The dye can be well written with good color when used in writing inks, and has extremely good solubility in water, so that it can be eluted into the erasing solution in the first stage. By being done more efficiently. Furthermore, there are many advantages such as high reactivity with the reducing sulfur compound in the third stage, and elimination in a shorter time. For example, C.I. I. Acid Blue 22, 93 and the like.

  In the present invention, in order to erase the handwriting, a reducing sulfur compound that reacts with a dye such as a triallylmethane acid dye present in the writing ink is blended in the erasing liquid. A reducing sulfur compound is a compound that reacts with a dye in a writing ink and decolorizes the dye by a reducing action. For example, sulfites such as sodium sulfite, potassium sulfite, sodium bisulfite, potassium bisulfite, dithionite Sulfur compounds such as salts, Rongalite (formaldehyde sodium sulfoxylate dihydrate), pyrosulfite and the like can be mentioned.

In the present invention, in order to give good rewriteability, the reducing sulfur compound remaining in the erased paper is used by using the reducing sulfur compound concentration in the erasing liquid as dilute as possible. The compound concentration is designed to be as dilute as possible. As a result, even when rewriting with the same writing ink, a slight decrease in density can be suppressed, so that rewriting can be made substantially.
The compounding amount of the reducing sulfur compound in the erasing solution varies depending on the reducing sulfur compound to be used, but it can be used in the range of 0.05 to 2% by mass, preferably 0.1 to 1% by mass. If the blending amount exceeds this range, it will be excessive as a function of erasing the handwriting. If it is below this range, it tends to be difficult to obtain sufficient erasability, which is not preferable.

The present invention is also excellent in the stability of erase marks, that is, the ability to prevent recurrent color. The reducing sulfur compound used as the erasing agent is oxidized on the paper by the atmosphere, and the reducing power disappears with time. For this reason, the dye which has been reduced and decolored by the reducing sulfur compound is oxidized by the atmosphere and becomes a colored state, which may cause a recurrent color. Therefore, the erasure mark is maintained in a reducing atmosphere in order to prevent reoccurrence color. In the present invention, a recoloration preventing agent is blended in order to maintain the reducing atmosphere of the erase mark. The re-coloring inhibitor is not suitable as the main erasing agent because it has a slower erasing speed than the reducing sulfur compound, but its stability on paper is better than that of the reducing sulfur compound, and the erasing trace reducing atmosphere. Is used for a long period of time, and by blending the substance, the handwriting erasing solution of the present invention can provide excellent anti-recoloration performance.
Thus, only by containing a reducing sulfur compound and a recoloration preventing agent, a handwriting erasing solution having excellent erasability and rewriting property and excellent erasing solution stability and erase mark stability can be obtained. It can be done.

  As the recoloration inhibitor, it is effective to add a polyethyleneimine and / or a polyethyleneimine derivative having a number average molecular weight of 1,000 or more. Such polyethyleneimine and / or polyethyleneimine derivatives are unsuitable for use as a main erasing agent, such as a slower erasing speed than reducing sulfur compounds, but are more stable on paper than reducing sulfur compounds. It is good, and the reducing atmosphere of the erasure trace can be continued for a long period of time, and the performance of preventing recurrent color is excellent. If it is less than the above range, the stability on the paper is insufficient, and there is a tendency that recurrent colors are likely to occur. At present, commercially available products have a number average molecular weight of about 70,000 at the maximum, but it is estimated that other molecular weights can be used. However, the liquid viscosity tends to increase as the molecular weight increases.

  Further, it is even better if the anti-recoloring agent is a polyethyleneimine derivative having an added tertiary amine structure in the main chain. Polyethyleneimine is obtained by ring-opening polymerization of ethyleneimine. Therefore, it is a block copolymer of a primary or secondary amine. However, when there are many 1st and 2nd class parts, there is a tendency that the color tone tends to yellow, and the erasure trace tends to yellow with time or after time. In particular, when the tertiary amine ratio in the amine was 30% or less, a tendency to gradually turn yellow was observed. Therefore, it is preferable to add an alkyl group or the like to the amine group so as to have an added tertiary amine structure in the main chain because yellowing of the erased trace is reduced. Further, when an alkyl group having a hydroxyl group such as propylene oxide is used as an adduct and a polyethyleneimine derivative having an added tertiary amine structure of the alkyl oxide group in the main chain is improved in water solubility, stability in an erasing solution is improved. This is more preferable because it improves the erasure stability of the handwriting. As the recoloration inhibitor, a polyethyleneimine propylene oxide adduct is most suitable. Such an anti-recurrent agent is available, for example, under the name of Epomin manufactured by Nippon Shokubai Co., Ltd. Representative examples include Epomin PP-061.

The preferred blending amount of the re-coloring inhibitor into the erasing solution varies depending on the molecular weight and the like, but is generally in the range of 0.3 to 4% by mass as the solid content. If it falls below this range, the effect of suppressing the recurrence color will be insufficient, and if it exceeds this range, the rewriteability tends to be inferior.
Also, as described above, the combined use of the reducing sulfur compound and the anti-reoccurrence colorant provides good erasability and re-writeability, and the stability of the erasing liquid and the stability of the erasure mark. The amount is closely related, and the suitable blending amount in the erasing liquid is 0.05-2% by mass of the reducing sulfur compound and 0.3-4% by mass of the recurrent color inhibitor is in a good balance. Demonstrate.

On the other hand, since the erasing liquid is an alkaline aqueous solution, the surface of the paper may be damaged when the erasing liquid is used, and bleeding may occur during rewriting. Therefore, in the present invention, it is possible to add a rewriting imparting agent having a binder ability to bind the fibers of the paper after drying mainly with the main purpose of preventing bleeding.
Examples of the rewriting imparting agent include water-soluble resins and emulsion resins, and among them, the alkali-soluble acrylic acid polymer is preferable because it prevents fuzz on the paper surface by erasing and drying and is excellent in the function of preventing bleeding during rewriting. Such a rewriting imparting agent is available, for example, under the trade name of John Crill of Johnson Polymer Co., Ltd. A suitable blending amount of the rewriting imparting agent in the erasing liquid is 0.5 to 5% by mass.

  In the present invention, the reducing sulfur compound in the erasing solution is used in a dilute concentration as described above, but the stability of the erasing solution is also improved by adding a specific antioxidant. The antioxidant is added for the purpose of preventing the reducing sulfur compound from being oxidized with time in the erasing solution and reducing its reducing ability. As such compounds that act, amines such as ethanolamine, polyhydric alcohols typified by glycerin, sugar alcohols such as sorbit, and the like are effective. Among these, triethanolamine and glycerin are preferable, and these can be used alone or in combination of two or more. The addition amount varies depending on the antioxidant to be used, but can be used in the range of 0.5 to 10% by mass. In addition, polyethyleneimine and / or polyethyleneimine derivatives used as recurrence color preventing agents in the present invention also act as antioxidants for reducing sulfur compounds, and therefore, polyethyleneimine and / or polyethyleneimine derivatives as recurrence color preventing agents, Furthermore, a polyethylenimine derivative having an added tertiary amine structure in the main chain, a polyethylenimine derivative having an added tertiary amine structure of an alkyl oxide group in the main chain, and a polyethylenimine propylene oxide adduct can have both functions. Since the tendency to have becomes strong, it becomes more suitable. Although it is effective to some extent to use a substance having both functions, it is more preferable to use the above antioxidant in combination.

  In the present invention, the erasing liquid can dissolve the dye in the handwriting well by lowering the viscosity of the erasing liquid or having a lower surface tension. By doing so, it is possible to diffuse and dilute excess dye reactive substances such as a reducing sulfur compound, reduce the reaction with the dye in the same ink during rewriting, and achieve a minimum density loss. The viscosity of the erasing solution is preferably 1.0 to 10 mPs (20 ° C.), and the surface tension is preferably about 30 to 55.

The erasing solution of the present invention can be used in the range of pH = 10-12, preferably pH = 10.5-12.0. The reason is that it is desirable to increase the pH from the viewpoint of the stability and activation of the reducing sulfur compound used. As the alkalinizing agent, generally known inorganic / organic alkalizing agents can be used, and sodium hydroxide, potassium hydroxide, sodium carbonate, morpholine, guanidines and the like are typically exemplified.
In addition, antibacterial agents, surface tension adjusting agents, water-soluble solvents for adjusting the drying speed, and the like can be added.

  Examples of the present invention will be described below, but the present invention is not limited to the examples.

Preparation of blue ink for writing
CIAcid Blue 93 3.0 parts by mass Ethylene glycol 3.0 parts by mass Antibacterial agent 0.2 parts by mass * 1,2-Benzisothiazolin-3-one aqueous solution (Avicia Co., Ltd., Proxel XL-2 (S) )
Ion-exchanged water 94.0 parts by mass CIAcid Blue 93 was used as a dye that can be decolorized with a reducing sulfur compound, and the dye was stirred and dissolved in the above composition to prepare a blue ink for writing.

Example 1
Reducing agent 0.2 parts by weight Recoloring inhibitor 6.0 parts by weight Antioxidant 1.0 part by weight Rewriting imparting agent 3.3 parts by weight Alkalizing agent 0.7 parts by weight Bactericide 0.15 parts by weight Ion Exchange water 88.65 parts by mass Each component was stirred and dissolved in ion exchange water with the above composition to prepare a handwriting erasing solution.
Each component is as described in Table 1 and notes.

Examples 2-10, Comparative Examples 1-4
A handwriting erasing solution was obtained in the same manner as in Example 1 except that the composition of the erasing solution was as shown in Tables 1 and 2. Each component in the table was used as noted.

注１：ポリエチレンイミン酸化プロピレン付加物５０％水溶液（（株）日本触媒社製、エポミンＰＰ−０６１、数平均分子量１４００）
注２：ポリエチレンイミン（（株）日本触媒社製、エポミンＳＰ−０１２、数平均分子量１２００）
注３：ポリエチレンイミン（（株）日本触媒社製、エポミンＳＰ−０１８、数平均分子量１８００）
注４：ポリエチレンイミン（（株）日本触媒社製、エポミンＳＰ−２００、数平均分子量１００００）
注５：ポリエチレンイミン３０％水溶液（（株）日本触媒社製、エポミンＰ−１０００、数平均分子量７００００）
注６：ポリエチレンイミン（（株）日本触媒社製、エポミンＳＰ−１１０、数平均分子量１０００）
注７：ポリエチレンイミン（（株）日本触媒社製、エポミンＳＰ−００６、数平均分子量６００）
注８：アルカリ可溶性アクリル酸系ポリマー３０％水溶液（ジョンソンポリマー(株)社製、ジョンクリル６１Ｊ）
注９：アルカリ可溶性アクリル酸系ポリマー（ジョンソンポリマー(株)社製、ジョンクリル６８）
注１０：ベンヅイソチアゾロン水溶液（(株)パーパケム・アジア社製、トップサイド６００）※実施例８は１，２−ベンゾイソチアゾリン−３−オン水溶液（アビシア（株）社製、プロキセルＸＬ−２（Ｓ））

Note 1: Polyethyleneimine propylene oxide adduct 50% aqueous solution (manufactured by Nippon Shokubai Co., Ltd., Epomin PP-061, number average molecular weight 1400)
Note 2: Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP-012, number average molecular weight 1200)
Note 3: Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP-018, number average molecular weight 1800)
Note 4: Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP-200, number average molecular weight 10,000)
Note 5: Polyethyleneimine 30% aqueous solution (manufactured by Nippon Shokubai Co., Ltd., Epomin P-1000, number average molecular weight 70000)
Note 6: Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP-110, number average molecular weight 1000)
Note 7: Polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., Epomin SP-006, number average molecular weight 600)
Note 8: 30% aqueous solution of alkali-soluble acrylic acid polymer (Johnson Polymer 61J)
Note 9: Alkali-soluble acrylic acid polymer (John Crill 68, manufactured by Johnson Polymer Co., Ltd.)
Note 10: Ben ヅ isothiazolone aqueous solution (manufactured by Perpachem Asia Co., Ltd., Topside 600) * Example 8 is a 1,2-benzisothiazolin-3-one aqueous solution (manufactured by Avicia Co., Ltd., Proxel XL-2 ( S))

  A fountain pen (FKK-1000) manufactured by Pilot Corporation and filled with the above-mentioned blue ink for writing as a writing ink using a dye that can be decolorized by a reducing sulfur compound, and Examples 1 to 10 and Comparative Examples 1 to 4 A writing instrument set composed of an erasing tool in which the obtained handwriting erasing solution was filled in FUDEPEN (SKF-150R) manufactured by Pilot Corporation was prepared. Then, the following tests were performed and evaluated. The contents of each test and its evaluation criteria are as shown below, and the results are shown in Tables 1 and 2.

1. Eraseability: Twenty characters were written on a commercially available copy paper using the writing instrument, and the handwriting was applied three times with an erasing liquid and visually judged.
A: The handwriting was completely erased.
○: A trace of handwriting remained after erasure.
Δ: A trace of handwriting remained after erasure.
X: The ink color tone of the handwriting remained.
2. Concentration during rewriting (A): After erasing in the same manner as in the above erasability evaluation, dried at room temperature for 30 minutes. Immediately thereafter, the same pen was used for the erasing mark, and rewriting was performed. Judged.
A: Almost no change in concentration.
Δ: Density decreases.
X: The color of the ink has disappeared.
3. Concentration at rewriting (B): Concentration of rewritten handwriting after being rewritten in the same manner as the above-mentioned concentration at rewriting (A) for 24 hours in an environment of 40 ° C./90% RH The change was judged visually.
○: No decrease in concentration was observed.
(Triangle | delta): The density | concentration fall was confirmed.
X: The color tone of the ink has disappeared.
4). Erase trace stability (recurrent color): Recurrence of erased handwriting when the handwriting is erased by the same method as in the above erasability evaluation and left in an environment of 40 ° C./90% RH for 7 days. The color state was judged visually.
○: Almost no change was observed before and after the introduction.
(Triangle | delta): It was confirmed that the trace of handwriting is dark.
X: Recurrence color of handwriting was confirmed.
5). Stability of erasing solution: 10 g of the erasing solution was injected into a 50 ml polybin container, and the handwriting erasability after standing at 50 ° C./2 months was visually determined.
○: Demonstrated the same level of erasability as before.
Δ: Although the handwriting can be erased, it was inferior to that before the introduction.
X: The handwriting could not be erased.
6). pH measurement method: Measured with a pH meter (ion meter IM-40S) manufactured by Toa Denpa Kogyo Co., Ltd. (at 20 ° C.).

  From the results of Table 1 and Table 2, the handwriting erasing liquids of Examples 1 to 10 can erase the handwriting well, are excellent in safety without containing heavy metals, and the erasing liquid itself is stable. It can be seen that the handwriting can be erased satisfactorily, the erased state is stable, hardly changes over time, and the rewriting property at the erased portion is also excellent.

After writing with the above ink that cannot be erased with an eraser, etc., if an errant or other error occurs, the handwritten part of the errant part will be erased by the handwriting erasing solution of the present invention, which is stable and does not contain heavy metals. By erasing, the erasing state is stable, it is possible to obtain a good handwriting erasability that hardly changes over time, and the erasing part can be rewritten using the same writing ink Applicable to sets etc. It can also be used for digital pen applications that read handwriting electronically with digital devices, and can also be used for writing / erasing systems in handwriting recognition systems such as reading handwriting and erasing digital information at the same time as erasing in the present invention. Can be applied.

Claims (5)

  A reductive sulfur compound that erases handwriting written with a writing ink using a dye that can be decolorized by a reductive sulfur compound, a recoloring inhibitor, and an erasing solution that is at least a part from water. A rewritable handwriting eraser, wherein the agent is a polyethyleneimine and / or a polyethyleneimine derivative having a number average molecular weight of 1,000 or more.   2. The handwriting erasing solution according to claim 1, wherein the recurrent color preventing agent is a polyethyleneimine derivative having an added tertiary amine structure in the main chain.   The handwriting erasing solution according to any one of claims 1 and 2, wherein the anti-recurrent agent is a polyethyleneimine derivative having an alkylamine-group-added tertiary amine structure in the main chain.   The handwriting erasing solution according to any one of claims 1 to 3, wherein the recurrent color preventing agent is a polyethyleneimine propylene oxide adduct. The handwriting erasing solution according to any one of claims 1 to 4, wherein the dye that can be decolorized by a reducing sulfur compound is a triallylmethane acid dye.