JP2001220530A - Aqueous marker ink composition using decoloring composition with solvent or heating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink composition which gives a written line which has density enough to be used for writing utensils such as a marker and is excellent in adhesiveness to the surface of paper. SOLUTION: This ink composition contains (a) a colorant which is microcapsules containing a leuco dye, a developer, and a decoloring agent or fine particles comprising a leuco dye, a developer, a decoloring agent, and a resin, (b) water as a solvent, and (c) at least one resin which has a film- forming capability at normal temperature and is selected from the group consisting of water-soluble resins and water-soluble resin emulsions. The viscosity of the ink under a shear rate of 75s-1 at 25 deg.C is 1-50 mPa.s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink composition for a water-based marker which is used for a writing instrument such as a marker and which can erase a writing line by a solvent or heating after writing.

[0002]

2. Description of the Related Art In recent years, mass consumption of paper has become a serious problem from the viewpoint of resource conservation. The collection and recycling of used paper has been energetically promoted along with the growing desire to reuse reusable resources.However, to recycle paper written with conventional writing instruments, the paper itself must be reclaimed. Large amounts of energy are required to re-fibrillate or re-paper. In addition, in order to obtain paper having high whiteness, a large amount of bleaching agent and water are required for the bleaching of the ink, so that the recycling cost is increased and this is a major obstacle from the viewpoint of resource conservation and paper recycling. This is because conventional inks have been developed with an emphasis only on improving light resistance and heat resistance in order to increase the durability of writing lines, so from the viewpoint of recycling paper, The high chemical or physical stability of the ink is an obstacle to regeneration. Therefore, if you can write on paper with a writing instrument using erasable ink, erase the writing lines, and return to a blank paper state, it is possible to reuse or reuse the paper as it is Therefore, it is considered that the substantial amount of paper used can be reduced.

Hitherto, from the standpoint of protecting paper resources, there has been proposed an ink composition which can be erased after printing for the purpose of recycling paper printed by a printer or a copying machine (Japanese Patent Laid-Open No. 10-8).
No. 8046). That is, the ink composition contains a color developing compound, a color developer, and an erasing agent, and the color developing compound and the color developing agent interact with each other to form a color. When the composition is melted or dissolved by a solvent, it has the property of preferentially binding to the color developer. The ink composition may be microencapsulated as necessary. This ink composition can be printed with a sufficient contrast and can be erased by heat, so that the paper can be reused.

[0004]

According to the disclosure of the above publication, microcapsules containing a leuco dye, a color developer and a decolorant, or fine powder containing a leuco dye, a color developer, a decolorant and a resin When used directly as a colorant in a water-based marker ink, there are two problems: poor adhesion of the colorant to the paper surface and extremely low density of writing lines.

Accordingly, the present invention has been developed in view of the above-mentioned social needs and various problems of the prior art, and provides an ink which can easily erase a writing line by a solvent and / or heating. It is intended to enable the reuse or reuse of paper without significant costs. Another object of the present invention is to provide a writing instrument using ink that can easily erase a writing line by a solvent and / or heating. In particular, a microcapsule containing a leuco dye, a color developer, a decoloring agent or a fine powder containing a leuco dye, a color developing agent, a decoloring agent, and a resin is used as a coloring agent to enhance the adhesion of the coloring agent to the paper surface. It is an object of the present invention to provide a water-based ink having a writing line thick enough to be used for a writing instrument such as a marker by adding the resin, and having excellent adhesion of the writing line to the paper surface.

[0006]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, obtained microcapsules or leuco dyes containing a leuco dye, a color developer and a decolorant, and a color developer. When a fine powder containing a colorant, a decolorizing agent and a resin is used as a colorant, and the colorant is dispersed in water containing a resin for increasing the adhesion of the colorant to the paper surface, and the ink is used as a water-based marker ink, the ink viscosity is particularly low. ５０50 mPa · s (Temperature 25
℃, shearing rate of 75 s ^-1 ), it was found that writing was not impossible due to an insufficient supply of ink, and that it was excellent in adhesion to the paper surface and extremely effective in giving dark writing lines. As a result, the present invention has been reached.

That is, the present invention provides (1) (a) a microcapsule containing a leuco dye, a developer and a decolorant as a colorant, or a fine powder comprising a leuco dye, a developer, a decolorant and a resin. , (B) water as a solvent, and (c) a water-soluble resin or at least one resin having a film-forming property at room temperature selected from aqueous resin emulsions (for enhancing the adhesion of a colorant to a writing surface such as a paper surface). Resin), and the ink viscosity at a shear rate of 75 s ⁻¹ at a temperature of 25 ° C. is ¹ to 50 mPa · s, preferably 5 to 35 mPa
The ink composition for a water-based marker according to the above (1), further comprising (2) a thixotropic compound which prevents solidification of the colorant during sedimentation. ,

(3) At least one developer selected from the group consisting of hydroxyacetophenone, hydroxybenzophenone, gallic ester, benzenetriol, benzenediol, bisphenol, triphenol and cresol (1)
Or the ink composition for an aqueous marker described in (2),
(4) The aqueous marker ink composition according to any one of (1) to (3), wherein the decoloring agent is at least one selected from the group consisting of bile acids, bile acid esters, steroid compounds, and starch. (5) The above (1) to (5), wherein the average particle size of the microcapsules or fine powder is 0.1 to 15 μm.
(4) The ink composition for an aqueous marker according to any of (4),

(6) The molar ratio between the leuco dye and the developer is
The ink composition for an aqueous marker according to any one of the above (1) to (5), which is 1: 1 to 1: 3, and (7) the mass ratio or the molar ratio between the developer and the decolorant is 1 : 3 to 1:15, wherein the amount of the aqueous marker ink composition described in any one of the above (1) to (6), (8) the amount of microcapsules or fine powder is 5 based on the amount of the ink composition substance. To 20% by mass of the ink composition for an aqueous marker according to any one of the above (1) to (7).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, in order to increase the adhesion of a writing line to a paper surface, the particle size of a microcapsule or a fine powder is reduced and at least one type selected from a water-soluble resin and a water-based resin emulsion is used. By adding a resin having a film forming property at room temperature, the adhesion of the writing line to the paper surface can be improved. Here, the reason for setting the ink viscosity to 1 to 50 mPa · s is that this ink composition is an aqueous dispersion, and the viscosity of water itself is 1 mP.
Since it is a · s, it is difficult to prepare an ink having an ink composition of less than 1 mPa · s, and if it is 1 mPa · s or more, it can be used without any practical problems. On the other hand, if the viscosity of the ink exceeds 50 mPa · s, a shortage of ink supply to the pen tip occurs, which causes a drawback that writing becomes impossible. In addition, in order to secure the concentration of the writing line as a concentration sufficient for use, the coloring agent composed of microcapsules or fine powder shows a high concentration, and the coloring agent is used in order to easily reuse or reuse the paper. The agent must have good erasing performance. For this purpose, it is necessary to optimally select the types of leuco dye, color developer and decolorant and their ratio.

In the present invention, microencapsulation can be performed according to a conventional method. That is, leuco dye,
After dissolving and mixing the developer and the decolorant, the mixture is gradually cooled to obtain a solid. Using a ball mill, this solid is finely pulverized and dispersed in an aqueous gum arabic solution, and then an aqueous acetic acid solution and formalin are added to adjust the pH. The liquid is cooled and left at room temperature to form microcapsules. In addition, the fine powder is heated and mixed using a kneader according to a conventional method using a composition comprising a leuco dye, a developer, a decoloring agent, and a resin, to obtain a colored pigment-like mass pigment, and jet the obtained pigment. Pulverizing and classifying with a mill preferably obtains fine powder having an average particle size of 0.1 to 15 μm.

Here, the average particle size of the microcapsules or fine powder used as the coloring agent is preferably 0.1 to 15 μm, particularly preferably 0.1 to 5 μm, and the concentration of the writing line is sufficient. It is desirable that the colorant used has a high concentration in order to ensure a proper concentration, and that the colorant be easily decolored in order to promote the reuse of paper. For that purpose, the molar ratio between the leuco dye and the developer is
The ratio is most preferably from 1: 1 to 1: 3, particularly preferably from 1: 1.5 to 1: 2, and the mass ratio or the molar ratio between the color developer and the decolorant is
1: 3 to 1:15, especially 1: 3 to 1:10, has been found to be optimal. In the manner described above, the adhesion of the writing line, and the concentration of the writing line sufficient for use,
Further, they have found that high erasability can be ensured, and have reached the present invention.

The leuco dye used in the present invention is, for example, a compound having a lactone ring in the molecule, such as triphenylmethanephthalide, spiropyran, diphenylmethane, fluoran, and rhodaminelactam. One type or a mixture of two or more types can be used. As the water-soluble resin, for example, a water-soluble nylon resin, a water-soluble polyvinyl acetal resin, a water-soluble polyamide resin, a polyethylene oxide resin,
A water-soluble resin such as a polyvinylpyrrolidone-based resin is used. The amount of the water-soluble resin is preferably 3 to 30% by mass based on the amount of the ink composition. As the aqueous resin emulsion, an emulsion such as a styrene-maleic acid copolymer, a vinyl chloride copolymer, an alkyd resin, or a urethane resin is used. The amount of the aqueous resin emulsion is preferably 10 to 70% by mass based on the amount of the ink composition substance. As a developer which forms a leuco dye by forming a pair with the leuco dye, hydroxyacetophenones such as dihydroxyacetophenone and trihydroxyacetophenone, hydroxybenzophenones such as dihydroxybenzophenone, trihydroxybenzophenone and tetrahydroxybenzophenone, methyl gallate, and gallic acid Gallic acid esters such as ethyl, propyl gallate and butyl gallate, 4-[(4′-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4-[(3 ′, 5′-dimethyl-) 4'-hydroxyphenyl) methyl] -1,2,3-benzenetriol, 4,6-bis [(3 ', 5'-dimethyl-4'-hydroxyphenyl) methyl] -1,2,3-benzenetriol Benzenetriol, methylenetris-
benzenediols such as p-cresol and 3,3′-diallyl-4,4′-dihydroxydiphenylsphone;
Bisphenols such as 4,4'-bisphenol, 4,4'-cyclohexylidenebisphenol, and 4,4 '-(1-phenylethylidene) bisphenol;
It is a triphenol-based compound such as 4 ′, 4 ″ -ethylidene trisphenol, and one or a mixture of two or more thereof can be used. However, even among the compounds classified into the above system, methylenetetrakis-p-cresol, which is a benzenediol compound, has a weak effect as a color developer and weakly develops a leuco dye. On the other hand, 2,3-hydroxybenzoic acid, which is also a benzenediol type, has a strong effect as a color developer and cannot be decolorized. Similarly, triphenyl-based 4,4 ′, 4 ″ -methylidenetrisphenol has a strong effect as a developer and cannot be decolorized. As described above, although being classified into the above-mentioned system, it does not necessarily mean that it can be used as a suitable color developer, but the compounds of the above-mentioned system are good because they generally show good color developing action and decoloring property. .

The thixotropic compounds include, for example, xanthan gum, welan gum, guar gum, locust bean gum and derivatives thereof, hydroxyethyl cellulose, alkyl alginate, carbohydrates having a gelling ability extracted from seaweeds such as agar and carrageenan, and crosslinked type. It is a thickener such as an acrylic acid copolymer or a liquid resin-provided substance of modified anhydrous silica having a fine particle diameter, and one or more of them can be used in combination. The amount of the thixotropic compound is preferably 0.1 to 1% by mass based on the amount of the ink composition. Further, as the decoloring agent which is apparently decolored by being combined with a developer separated from the leuco dye, those having high erasing performance and high aging stability of the erasing state are desirable, and bile acids, bile acid esters, steroids It has been found that the use of one or more of the compounds and starch is extremely effective. As used herein, bile acids are cholic acid, hydroxycholic acid, lithocholic acid, hydroxyacids of steroids based on colanic acid such as deoxycholic acid, and bile acid esters are esterified products of the above bile acids. . In addition, the steroid compounds include cortisone, hydrocortisone, and hydrocortisone acetate.

Among the leuco dyes used in the present invention, as a particularly preferred dye, as a result of intensive studies, it has been found that PSD-184 exhibiting black is effective, but leuco dye exhibiting other colors, and And leuco dyes having other structures can be used without any limitation. The resin used as the coloring agent in the present invention preferably does not prevent color development and decoloration, and examples thereof include polystyrene, epoxy resin, and styrene-acryl copolymer. The aqueous marker ink composition according to the present invention is an aqueous dispersion of a colorant consisting of microcapsules or fine powder composed of a leuco dye, a developer and a decoloring agent, if necessary, as described above. It is possible to erase the color after writing. That is, in the present invention, the mechanism of the manifestation of the action and effect is based on a state in which the leuco dye and the developer are chemically bonded in advance, that is, a colorant in a color-developing state is used as the ink, and when erasing, the solvent is swollen or heated. The chemical bond between the leuco dye and the developer is broken by the pseudo-liquid phase reaction in the pseudo-molten state of the coloring agent, and the decolorizing agent and the developing agent contained in the coloring agent newly form a strong chemical bond. By forming, the writing line can be erased without re-coloring, and the object can be achieved.

The ink composition of the present invention is characterized in that a microcapsule containing a leuco dye, a developer, a decolorant, or a fine powder containing a leuco dye, a developer, a decolorant, and a resin is used as a colorant. Although it is characterized, the stoichiometric basis in the molar ratio of the leuco dye and the developer in the ink composition, and the mass ratio or the molar ratio of the developer and the decolorant is not necessarily clear, In general, it is presumed as follows. That is, if the molar ratio of the developer to the leuco dye is less than 1, complete coloring of the leuco dye is stoichiometrically impossible, and a sufficient writing line concentration for use cannot be ensured. On the other hand, if the molar ratio exceeds 3, the density of the writing line does not increase so much, but rather adverse effects such as lowering of erasing performance and re-coloring after erasing occur, which is not preferable. In addition, bile acids, bile acid esters, steroidal compounds and starch are used as decolorizing agents.However, since it is difficult to specify the molecular weight of starch, starch is used as a mass ratio with the developer and the molecular weight is used. Those that can be specified were used as molar ratios. The mass ratio or molar ratio of the decoloring agent to the developer is 3
Below, the erasing of the writing line may be incomplete,
Also, re-coloring after erasure may occur. On the other hand, if the mass ratio or the molar ratio exceeds 15, the erasability does not increase so much, but rather the color forming components (leuco dye and developer) in the colorant become relatively low, so that a sufficient writing line is used. This is not preferable because a problem such as the inability to secure the concentration of the above-mentioned is caused.

Rust inhibitors, preservatives, fungicides, pH adjusters, surface tension adjusters, humectants, lubricants, dispersion stabilizers, dispersion resins, and the like, which are commonly used as ink materials, may also be used as necessary. Can be. The other additives are not restricted at all, but in view of the object of the invention, they must not prevent the coloring and decoloring of the ink.

[0018]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.
[In the present invention, the viscosity was measured by a Brookfield (D-III) as an E-type viscometer.
Performed using an L3.3 LV spindle CP-40. (Example 1) (parts by mass) Leuco Dye PSD-184 (trade name, manufactured by Nippon Soda Co., Ltd.) 2.5 Developer 3,5-dihydroacetophenone 1.5 Decolorizer Potato starch 15.0 resin SB-130 (polystyrene manufactured by Sanyo Chemical Industries, Ltd., trade name) 40.0 [leuco dye: developer = 1: 2 (molar ratio), developer: decolorant = 1: 10 (mass ratio) Was heated and mixed using a kneader to obtain a colored pigment-like mass pigment.

This pigment was pulverized by a jet mill, and the resulting mixture was stirred and mixed with a fine powder pigment of 5 to 10 μm having the following composition using a stirrer to obtain a black ink. (Mass%) Black fine powder 10.0 Deltop (Takeda Pharmaceutical Co., Ltd., trade name, 2-benzisothiazoline-3-one 10%, diethylene glycol 70%) 0.3 U-coat UWS-145 (Sanyo Chemical Industries, Ltd.) (Trade name, self-emulsifying urethane resin emulsion) 35.0 0.35% by mass aqueous ammonia 3.2 Aerosil 200 (trade name, anhydrous-modified silica, manufactured by Nippon Aerosil Co., Ltd.) 0.5 ion Exchange water 51.0 The viscosity of the aqueous black ink composition is 7.6 mPa · s.
(25 ° C., 75 s ⁻¹ ) and pH 7.7.

(Example 2) (parts by mass) Leuco dye PSD-184 2.5 Developer 2,3,4-trihydroxybenzophenone 2.3 Decolorant Cholic acid 20.2 Resin ST-120 (Sanyo Chemical Co., Ltd.) 50.0 [leuco dye: developer: decolorant = 1: 2: 10 (molar ratio)] is heated and mixed using a kneader to form a colored mass. Was obtained.

This pigment is pulverized by a jet mill, and a fine powder pigment of 0.5 to 5 μm separated by classification is used.
The following composition was stirred and mixed using a stirrer to obtain a black ink. (% By mass) Black fine powder 10.0 Deltop 0.3 Ucoat UWS-145 20.0 0.35% by mass ammonia water 3.2 Xanthan gum 0.2 Deionized water 66.3 Viscosity of the aqueous black ink composition Is 31.5 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 9.6.

Example 3 (parts by mass) Leuco Dye Crystal Violet Lactone 2.1 Developing Agent Ethyl Gallate 2.0 Decolorizing Agent Methyl Cholate 21.4 Resin SB-130 50.0 [Leuco Dye: Developed (Coloring agent: Decoloring agent = 1: 2: 10 (molar ratio)] was heated and mixed using a kneader to obtain a colored mass of pigment.

This pigment was pulverized by a jet mill, and the resulting mixture was agitated and mixed using a fine powder pigment of 5 to 10 μm classified by using a stirrer with the following composition to obtain a blue ink. (Mass%) Blue fine powder 10.0 Deltop 0.3 PVP K-30 (manufactured by ISP Co., Ltd., trade name, polyvinylpyrrolidone) 10.0 0.35 mass% ammonia water 3.5 ion-exchanged water 76. 5 The viscosity of the aqueous blue ink composition is 12.3 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 7.3.

(Example 4) (parts by mass) Leuco dye PSD-V (trade name, red leuco dye manufactured by Nippon Soda Co., Ltd.) 2.0 Developer 4-[(4-hydroxyphenyl) methyl] -1,2,3-Benzentriol 1.1 Decoloring agent Cholic acid 23.3 resin ST-120 45.0 [leuco dye: developer: decoloring agent = 1: 1: 12 (molar ratio)] Was heated and mixed using a kneader to obtain a colored pigment mass.

This pigment was pulverized by a jet mill, and a fine powder pigment of 1 to 5 μm classified by classification was stirred and mixed with a stirrer according to the following composition to obtain a red ink. (% By mass) Red fine powder 10.0 Deltop 0.3 Ucoat UWS-145 35.0 0.35% by mass ammonia water 3.2 Xanthan gum 0.15 Deionized water 51.35 Viscosity of the aqueous red ink composition Is 38.3 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 9.8.

(Example 5) (parts by mass) Leuco dye PSD-V 2.0 Developer Methylenetris-p-cresol 1.7 Decolorant Potato starch 20.4 Resin TB-1000F (Sanyo Chemical Industries, Ltd.) ), Trade name, styrene-acryl copolymer) 45.0 [leuco dye: developer = 1: 1 (molar ratio), developer: decolorant = 1: 12 (mass ratio)] Was heated and mixed to obtain a colored pigment mass. This pigment was pulverized by a jet mill and classified by classification into 5 to 10 parts.
A μm fine powder pigment was obtained. The obtained pigment was stirred and mixed with the same composition as in Example 1 except for the fine red powder using a stirrer to obtain a red ink. The viscosity of the aqueous red ink composition is 7.7 mPa · s (25 ° C., 75 s ⁻¹ ), pH
7.7.

(Example 6) (parts by mass) Leuco dye PSD-V 2.0 Developer 3,5-dihydroacetophenone 1.5 Decolorizer Potato starch 15.0 Resin ST-120 50.0 [Leuco dye : Developer: 1: 2 (molar ratio), developer: decolorant = 1: 10 (mass ratio)] by using a kneader and heating to obtain a colored pigment mass.

This pigment was pulverized by a jet mill to obtain a fine powder pigment of 5 to 10 μm classified by classification. The obtained fine powder was stirred and mixed with the following composition using a stirrer to obtain a red ink. (% By mass) Red fine powder 5.0 Deltop 0.3 U-coat UWS-145 10.0 0.35% by mass ammonia water 3.2 Ion-exchanged water 81.5 The viscosity of the aqueous red ink composition is 1.9 mPa.・ S
(25 ° C., 75 s ⁻¹ ) and pH 8.2.

(Example 7) (parts by mass) Leuco dye PSD-V 2.0 Developer Methylenetris-p-cresol 1.7 Decolorizer Prognenolone 17.0 [Leuco dye: developer = 1: 1] (Molar ratio), developer: decolorant = 1: 10 (mass ratio)] and mixed, and then cooled slowly to obtain a red solid. Using a ball mill, this solid was dissolved in an 8% by mass aqueous solution of gum arabic.
It was ground and dispersed to the order of μm. Next, an aqueous gelatin solution was mixed at 40 ° C., and the mixture was stirred for 1 hour, and then water was added dropwise, followed by dilution by stirring. Subsequently, a 10% by mass aqueous solution of acetic acid was added to adjust the pH of the solution to 3.9, and 37% formalin was added dropwise to adjust the pH of the solution to 7.0. The solution was cooled to 5 ° C. and allowed to stand at room temperature for 3 days, and then microcapsules formed in the solution were separated by a centrifuge to prepare red-like microcapsules.

The obtained microcapsules were stirred and mixed with the following composition using a stirrer to obtain a red ink. (% By mass) Red microcapsules 10.0 Deltop 0.3 Ucoat UWS-145 35.0 0.35% by mass ammonia water 3.2 Xanthan gum 0.15 Aerosil 200 0.5 Deionized water 50.85 Above aqueous red The viscosity of the ink composition is 42.7 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 7.6.

(Comparative Example 1) (parts by mass) Leuco dye PSD-184 2.5 Developer 2,4,4'-trihydroxybenzophenone 2.3 Decolorant Potato starch 2.3 Resin ST-120 0 [Leuco dye: color developer = 1: 2 (molar ratio), color developer: decolorant = 1: 1 (mass ratio)] using a kneader, and heat-mixed to form a colored pigment. I got This pigment was pulverized by a jet mill, and 5 to 10 μm separated by classification.
m of fine powder pigment was obtained. The obtained pigment was stirred and mixed with the same composition as in Example 1 except for the fine powder using a stirrer to obtain a black ink. The viscosity of the aqueous black ink composition is 7.5 mPa · s (25 ° C., 75 s ⁻¹ ), and the pH is 7.0.
It was 6.

(Comparative Example 2) (parts by mass) Leuco dye Crystal violet lactone 2.0 Developer Methylenetetrakis-p-cresol 4.6 Decolorant Potato starch 22.9 Resin SB-130 50.0 [Leuco dye : Developer: 1: 2 (molar ratio), developer: decolorant = 1: 5 (mass ratio)] by using a kneader and heating to obtain a colored pigment mass. This pigment was pulverized by a jet mill, and 5 to 10 μm separated by classification.
m of fine powder pigment was obtained. The color of the obtained pigment was light, and a sufficient density could not be obtained.

Comparative Example 3 (parts by mass) Leuco Dye Crystal Violet Lactone 2.0 Developer 2,4,4′-Trihydroxybenzophenone 2.2 Decolorant Cortisone Acetate 38.5 Resin ST-120 50. 0 [leuco dye: developer: decolorant = 1: 2: 20 (molar ratio)] was heated and mixed using a kneader to obtain a colored pigment mass. This pigment was pulverized with a jet mill to obtain a fine powder pigment of 5 to 10 μm classified by classification. Except for the blue fine powder using the obtained pigment,
Using a stirrer with the same composition as described above, stirring and mixing were performed to obtain a blue ink. The viscosity of the aqueous blue ink composition is 7.8 mPa.
S (25 ° C., 75 s ⁻¹ ), pH 7.5.

(Comparative Example 4) (parts by mass) Leuco Dye Crystal Violet Lactone 2.1 Developing Agent Ethyl Gallate 2.0 Decolorizing Agent Methyl Cholate 21.4 Resin ST-120 50.0 [Leuco Dye: Developed (Coloring agent: Decoloring agent = 1: 2: 10 (molar ratio)] was heated and mixed using a kneader to obtain a colored mass of pigment.

This pigment was pulverized by a jet mill to obtain a fine powder pigment of 5 to 10 μm classified by classification. The resulting fine powder was stirred and mixed with the following composition using a stirrer to obtain a blue ink. (% By mass) Blue fine powder 10.0 Deltop 0.3 U-coat UWS-145 35.0 0.35% by mass ammonia water 3.2 Aerosil 200 0.5 Xanthan gum 0.2 Ion exchange water 50.8 Above aqueous blue The viscosity of the ink composition is 64.7 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 8.0.

(Comparative Example 5) (parts by mass) Leuco Dye Crystal Violet Lactone 2.1 Developing Agent Ethyl Gallate 9.5 Decoloring Agent Cholic Acid 98.4 Resin SB-130 80.0 [Leuco Dye: Developing Color Agent: decoloring agent = 1: 10: 50 (molar ratio)] by using a kneader and heat-mixing to obtain a colored pigment mass. This pigment was pulverized by a jet mill to obtain a fine powder pigment of 0.5 to 5 μm which was classified by classification. The obtained pigment was stirred and mixed using a stirrer with the same composition as in Example 2 except for the fine blue powder to obtain a blue ink. The viscosity of the aqueous blue ink composition is 30.6 m
Pa · s (25 ° C., 75 s ⁻¹ ) and pH 9.8.

(Comparative Example 6) (parts by mass) Leuco dye PSD-184 2.5 Developer 2,4,4'-trihydroxybenzophenone 2.3 Decolorant Potato starch 69.0 Resin ST-120 55. 0 [Leuco dye: color developer = 1: 2 (molar ratio), color developer: decolorant = 1: 30 (mass ratio)] using a kneader, and heat-mixed to form a colored pigment. I got This pigment was pulverized with a jet mill, and classified by classification into 20 to 3
A fine powder pigment of 0 μm was obtained. The obtained pigment was stirred and mixed with the same composition as in Example 1 except for the fine powder using a stirrer to obtain a black ink. The viscosity of the aqueous black ink composition is 7.5 mPa · s (25 ° C., 75 s ⁻¹ ), pH
7.7.

(Comparative Example 7) (parts by mass) Leuco dye PSD-184 2.5 Developer 3,5-dihydroacetophenone 1.5 Decolorant Potato starch 15.0 Resin SB-130 40.0 [Leuco dye : Developer: 1: 2 (molar ratio), developer: decolorant = 1: 30 (mass ratio)] by using a kneader and heating to obtain a colored pigment mass.

This pigment was pulverized by a jet mill to obtain a fine powder pigment of 5 to 10 μm classified by classification. The obtained fine powder was stirred and mixed with the following composition using a stirrer to obtain a black ink. (% By mass) Black fine powder 10.0 Deltop 0.3 Ucoat UWS-145 5.0 0.35% by mass ammonia water 3.2 Aerosil 0.5 Deionized water 81.0 Viscosity of the aqueous black ink composition Is 5.3 mPa · s
(25 ° C., 75 s ⁻¹ ) and pH 7.2.

(Test Method) Each of the inks of Examples 1 to 7 and Comparative Examples 1 to 7 was preliminarily used in the same manner as a commercially available normal direct liquid type aqueous marker (Zebra Popstar extra fine-trade name-). A stainless steel stirrer is placed in a polypropylene tube with the valve built-in tip fitted to the extra-fine side, and after filling with ink, the valve built-in tip is fitted to the fine side and made of polyester. The chip was assembled, the inside of the tube was set to normal pressure, and an aqueous marker pen was prepared. In addition, the marker was shaken about 10 times immediately before writing, the ink was thoroughly stirred, and after sufficient ink ejection, a writing test was performed. Density test of writing line Using a plurality of the marker pens, writing was performed on copy paper, and it was observed whether the density of the writing line was sufficient for use. Writing line adhesion test A plurality of the above-mentioned marker pens were used to write on copy paper, and after the writing line was dried, the writing line was rubbed with an eraser to observe whether the writing line was erased.

Decolorization Test Using Solvent A few drops of methyl ethyl ketone were dropped on a writing line written on report paper using the above-mentioned marker pen, and it was confirmed whether the writing line at the dropped location was decolorized. Further, after the solvent was dried, it was confirmed whether or not recoloring occurred. Decolorization test by heating An electric iron heated to about 200 degrees was pressed against a writing line written on report paper using the marker pen for 5 seconds to check whether the writing line was decolorized. or,
After the paper had cooled, it was checked whether it would re-color.

(Test Results) The test results are shown in Table 1.

[0043]

[Table 1]

As is evident from the test results in Table 1, Comparative Example 1 had poor erasability and recolored in both solvent and heating due to the low content of the decoloring agent. In Comparative Example 2, since the developer was not properly selected, the interaction between the leuco dye and the developer was weak, and a sufficient concentration of the colorant could not be secured. In Comparative Example 3, the writing line could not be erased for both the solvent and the heating because of the poor selection of the decoloring agent. In Comparative Example 4, since the viscosity of the ink composition was high,
The ink supply was insufficient and writing was impossible. In Comparative Example 5, since the content of the developer was large, the erasability was poor in both the erasing by the solvent and the heating, and the color recurred. In Comparative Example 6, since the particle size of the pigment particles was large, the pigment was clogged in the chip and writing was impossible. In Comparative Example 7, since the amount of the fixed resin was small, the writing line was erased when the writing line was rubbed with an eraser. However, in Examples 1 to 7, the writing density was also good, and the solvent,
The writing lines were erased to the extent that they could not be seen without re-coloring upon heating, demonstrating the effects of the invention.

[0045]

The adhesiveness of the microcapsules containing at least the leuco dye, the developer and the decoloring agent or the fine powder containing the leuco dye, the developer, the decoloring agent and the resin, water, and the colorant to the paper surface. In a water-based marker ink composition comprising at least a resin for enhancing, the developer is a hydroxyacetophenone-based, hydroxybenzophenone-based, gallic ester-based, benzenetriol-based, benzenediol-based, bisphenol-based, triphenol-based or cresol-based And the molar ratio between the leuco dye and the developer is
1: 1 to 1: 3, wherein the decolorizing agent is a bile acid, a bile acid ester, a steroid compound or a starch, and a mass ratio or a molar ratio between the developer and the decoloring agent. In an ink composition having a ratio of 1: 3 to 1:15,
The ink viscosity at a shear rate of 75 s ⁻¹ at a temperature of 25 ° C. is ¹ to 50 mPa · s, the adhesion of the writing line to the paper surface is good, and the concentration of the writing line sufficient for use can be ensured, and the color recurs. And an ink composition exhibiting good erasing performance can be obtained.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Yoshida 2-9 Higashigokencho, Shinjuku-ku, Tokyo Inside Zebra Co., Ltd. (72) Inventor Koichi Ito 2-9 Higashigokencho, Shinjuku-ku, Tokyo No. Zebra Co., Ltd. F term (reference) 4J039 AB01 AB02 AD03 AD05 AD07 AD09 AD14 AD23 AE04 AE06 AE07 AE08 BA21 BC07 BC16 BC19 BC20 BC29 BC31 BC33 BC65 BC68 BC69 BD03 BE02 BE23 BE33 CA06 EA29 EA42 EA43 GA26

Claims (8)

[Claims] (A) a leuco dye as a coloring agent, a developer
And a microcapsule containing a decoloring agent, or a leuco dye,
A fine powder composed of a developer, a decolorant and a resin, (b) a solvent and
And water, and (c) a water-soluble resin or an aqueous resin emulsion
At least one type selected from the group
At a temperature of 25 ° C.
75s ^-1The ink viscosity at the time is 1 to 50 mPa · s
And an aqueous marker ink composition. 2. The ink composition for an aqueous marker according to claim 1, further comprising a thixotropic compound. 3. The developer according to claim 1, wherein the developer is a hydroxyacetophenone-based developer.
The aqueous marker according to claim 1 or 2, wherein the aqueous marker is at least one selected from the group consisting of hydroxybenzophenone, gallic ester, benzenetriol, benzenediol, bisphenol, triphenol and cresol. Ink composition. 4. The aqueous marker ink composition according to claim 1, wherein the decoloring agent is at least one selected from the group consisting of bile acids, bile acid esters, steroid compounds and starch. object. 5. The aqueous marker ink composition according to claim 1, wherein the average particle size of the microcapsules or fine powder is 0.1 to 15 μm. 6. The molar ratio of leuco dye to developer is 1: 1.
The ink composition for an aqueous marker according to any one of claims 1 to 5, wherein the ratio is from 1: 3. 7. The mass ratio or the molar ratio between the color developer and the decolorant is as follows:
The ink composition for an aqueous marker according to any one of claims 1 to 6, wherein the ratio is 1: 3 to 1:15. 8. The ink composition for a water-based marker according to claim 1, wherein the amount of the microcapsules or fine powder is 5 to 20% by mass based on the amount of the ink composition substance.