JP2002265842A - Water-based erasable ink composition for marking pen and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based erasable ink composition for a marking pen, having excellent erasability not only after the writing is dried but also in the initial stage after writing when the ink is not completely dried, and further to provide a method for producing the ink composition. SOLUTION: This water-based erasable ink composition for the marking pen is obtained by mixing and stirring a water dispersion of an organic pigment obtained by dispersing an organic pigment having an aromatic polycyclic structure in water by using a dispersing agent, with the water, adding an aqueous emulsion obtained by emulsifying an oily material hardly volatile at normal temperature with an emulsifier and a resin to the obtained mixture, and mixing and stirring the resultant mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an aqueous erasable marking pen ink composition and a method for producing the same. Specifically, the present invention is not only water-based, but also non-absorbable or non-permeable penetrating writing surface, typically after the handwriting written on a writing surface called a so-called white board is dried, but of course is still sufficiently dry. Even in the initial stage after writing, it has excellent erasability,
The present invention relates to an aqueous erasable marking pen ink composition that does not leave stains on a white plate and an advantageous method for producing such an ink composition.

[0002]

2. Description of the Related Art Conventionally, handwriting written on a non-absorbable or non-permeable writing surface is wiped off from the writing surface by gently rubbing it with an eraser (wiping a white board) made of a soft cloth to erase the handwriting. Various such aqueous erasable marking pen ink compositions are known. Such a conventional water-erasable marking pen ink composition generally contains an additive called a release agent together with water as a solvent, a colorant, and a film-forming resin.
As described in US Pat. No. 5,252,681, a non-volatile oil at room temperature, such as an aliphatic carboxylic acid ester, is incorporated into the ink composition as an emulsion,
Used as a release agent.

Further, JP-A-10-25422 and JP-A-10-25443 disclose an aqueous erasable marking pen ink composition containing cyclodextrin or a derivative thereof as a stabilizer for the release agent. Are also described.

However, in such a conventional water-based erasable marking pen ink composition, after writing on a white plate, in the initial stage after writing where the handwriting is not yet sufficiently dried, the handwriting is erased with an eraser. When rubbed,
There is a problem that it cannot be sufficiently erased, stains remain on the white plate, and the stains accumulate.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems in the conventional water-based erasable marking pen ink composition. It is an object of the present invention to provide an aqueous erasable marking pen ink composition having excellent erasability and an advantageous method for producing such an ink composition even in an initial stage after writing that has not yet been sufficiently dried. .

[0006]

According to the present invention, an organic pigment aqueous dispersion obtained by dispersing an organic pigment having an aromatic polycyclic structure in water using a dispersant is mixed with water, and the mixture is stirred. An aqueous erasable marking pen ink composition obtained by adding an emulsion of an oily substance which is hardly volatile at room temperature and a resin to the obtained mixture, mixing and stirring the mixture is provided.

Further, according to the present invention, an organic pigment aqueous dispersion obtained by dispersing an organic pigment having an aromatic polycyclic structure in water using a dispersant is mixed with water, and the mixture is stirred. A method for producing an aqueous erasable marking pen ink composition, comprising adding an emulsion of an oily substance which is hardly volatile at room temperature and a resin, mixing and stirring.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a marking pen is, firstly, a writing implement also called a felt pen, which is provided with a pen tip made of a plastic molding or the like at the tip of a cylindrical main body. A writing instrument that is capable of writing by supplying ink using a capillary phenomenon to the pen tip from such an ink storage means by impregnating the felt, fiber bundle, etc. with ink. The second type is a non-core type or so-called free ink type marking pen in which ink is directly stored in a tubular main body as it is and this ink is supplied to a pen tip. The aqueous erasable marking pen ink composition according to the present invention can be suitably used for such a writing instrument.

In the marking pen ink composition according to the present invention, water is used as a solvent. The amount of water in the ink composition is usually in the range of 50 to 90% by weight, preferably 60 to 80% by weight.

In the aqueous erasable marking pen ink composition according to the present invention, an organic pigment aqueous dispersion obtained by dispersing an organic pigment having an aromatic polycyclic structure in water using a dispersant as a colorant is used. . As organic pigments having such a polycyclic structure, in particular, anthraquinone-based,
Perylene or perinone organic pigments are preferably used.

As the dispersant, for example, a water-soluble resin is preferably used, and in particular, a styrene-acrylic resin or a styrene-maleic acid resin is preferably used. According to the present invention, the dispersant is not particularly limited, but the solid content is based on 1 part by weight of the organic pigment.
Usually, it is used in the range of 0.05 to 20 parts by weight, preferably 0.1 to 5 parts by weight.

According to the present invention, the colorant comprising such an organic pigment aqueous dispersion is used in the ink composition in a range of 0.1 to 40% by weight in terms of solid content. When the amount of the coloring agent is less than 0.1% by weight based on the ink composition, the density of the handwriting is too low, and the practicality is poor. However, if the amount is more than 40% by weight, the handwriting does not become darker in proportion to that, and on the other hand, since the viscosity of the ink composition is too high, the writability is poor and the erasability is low. descend. Further, when the cap is removed from the pen tip and left as it is, the ink composition dries at the pen tip and clogging is likely to occur. In particular, according to the present invention, the colorant, in the ink composition, preferably,
It is blended in the range of 1 to 30% by weight.

In the water-based erasable marking pen ink composition of the present invention, at room temperature (25
C) is incorporated into the ink composition in the form of an aqueous emulsion (ie, O / W emulsion). As such an oily substance which is hardly volatile at ordinary temperature, conventionally, as long as it has been formulated as a release agent in an aqueous erasable ink composition as an emulsion of an oily substance which is hardly volatile at ordinary temperature, Any of them can be used without limitation.

Particularly, in the present invention, the oily substance which is hardly volatile at room temperature includes the above-mentioned JP-A-1-252681.
As described in Japanese Patent Application Laid-Open Publication No. H11-157, an aliphatic carboxylic acid ester, higher hydrocarbon or higher alcohol which is hardly volatile at room temperature is preferably used.

The aliphatic carboxylic acid esters include:
As the ester, a monobasic acid ester, a dibasic acid diester, a mono- or diester of a dihydric alcohol, a mono-, di- or triester of a trihydric alcohol (particularly, a natural or synthetic fatty acid triglyceride), or a polyglycerin ester is preferably used. . Particularly preferred specific examples are monobasic acid esters, particularly higher fatty acid esters such as isopropyl myristate, cetyl isooctanoate, and isostearyl palmitate, and dioctyl dodecane diacid and diisopropyl adipate. , Such as diethyl sebacate, dihydric alcohol esters propylene glycol monocaprylate, propylene glycol decanoic acid diester,
Trihydric alcohol triesters such as glyceryl tri-2-ethylhexanoate, glyceryl tri (caprylate), trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, decaglyceryl decaoleate, etc. And the like. These are used alone or as a mixture of two or more.

The higher hydrocarbons used as the release agent are usually so-called liquid paraffins or squalane. Preferably, the higher hydrocarbons are partially oxidized, such as polyethylene oxide wax. Good. The higher alcohol that is liquid at normal temperature is not particularly limited, but, for example, hexyl alcohol, octyl alcohol, lauryl alcohol, and the like are preferably used.

Such an aqueous emulsion of an aliphatic carboxylic acid ester, a higher hydrocarbon or a higher alcohol comprises:
It can be prepared by an ordinary emulsifying method using an emulsifier. As the emulsifier, a nonionic surfactant having an HLB of 15 or less is preferably used. Such nonionic surfactants include, for example, polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester,
Nonionic surfactants such as polyoxyethylenated castor oil, polyoxyethylenated hardened castor oil, polyoxyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene / polyoxypropylene alkyl ether and the like can be mentioned.

These emulsifiers may be used alone,
Further, if necessary, two or more kinds may be used in combination. In addition, even if the HLB is more than 15, the HLB can be used in combination with another one when the HLB is 15 or less when combined with another.

The aqueous emulsion of the aliphatic carboxylic acid ester, higher hydrocarbon or higher alcohol is
Commercial products can also be used. Furthermore, if necessary, two or more aqueous emulsions of an aliphatic carboxylic acid ester, a higher hydrocarbon or a higher alcohol can be blended in the ink composition.

The ink composition according to the present invention generally contains a non-volatile oil at room temperature as a release agent in an amount of 1 to 50% by weight, preferably 2 to 50% by weight. It is contained in the range of 20% by weight. In the ink composition, when the amount of such a release agent is less than 1% by weight, the erasability of the handwriting is not sufficient. On the other hand, even if the amount exceeds 50% by weight, the handwriting is elongated and the writing is extended. In addition to soiling the surface, it also reduces the erasability of handwriting.

In the aqueous erasable marking pen ink composition according to the present invention, cyclodextrin or a derivative thereof (hereinafter sometimes collectively referred to as cyclodextrins) is used as a stabilizer for the emulsion. be able to. Cyclodextrin is
A sugar oligomer in which 6 to 10 D-glucopyranose groups are cyclically linked by an α- (1,4) glucoside bond, wherein α-, whose degree of polymerization is 6, 7 and 8, respectively;
β- and γ-cyclodextrin are well known.

In the present invention, such α- and β-
Or γ-cyclodextrin, and various methyl derivatives thereof, for example, 2,6-dimethyl-β-cyclodextrin, 2,3,6-trimethyl-β-cyclodextrin, partially methylated β-cyclodextrin, Maltosyl cyclodextrin, glycosyl cyclodextrin and the like are also effectively used. All of these cyclodextrins are water-soluble, though to varying degrees.

These cyclodextrins are used in the ink composition in the range of 0.1 to 20% by weight.
The content of cyclodextrins in the ink composition is 0.1
When the amount is less than 20% by weight, the effect of stabilizing the emulsion is poor. On the other hand, when the amount is more than 20% by weight, the obtained ink composition is thickened, resulting in poor writability. In addition, the adhesive strength of the handwriting to the writing surface becomes excessively strong, and the erasability is poor. According to the present invention, the amount of the cyclodextrin to be incorporated into the ink composition is preferably in the range of 0.5 to 10% by weight, and most preferably in the range of 1 to 5% by weight.

Further, the ink composition according to the present invention has a coating or a layer made of a resin containing the colorant after writing on a non-absorbing surface and after water has volatilized. So that the layer can be separated from the release agent layer described above,
Emulsions or hydrosols of water-insoluble resins having film-forming properties at room temperature, or resins that are originally water-insoluble but water-solubilized by salt formation with a base, or water-soluble resins (hereinafter referred to as room temperature Film-forming resin). However, the resin mentioned as the dispersant is not included in the film-forming resin mentioned here.

In the present invention, the room-temperature film-forming resin preferably includes (1) an emulsion or hydrosol of polyvinyl acetate, a vinyl acetate copolymer, an alkyd resin or a urethane resin, and (2) water solubilization. Vinyl acetate copolymer, alkyd resin or urethane resin, or
(3) water-soluble resin or (4) any combination of these is used.

Examples of the comonomer in the above-mentioned emulsion, hydrosol or water-solubilized vinyl acetate copolymer include vinyl ester compounds other than vinyl acetate, such as vinyl propionate and vinyl versatate, and unsaturated carboxylic acids such as And acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, crotonic acid, citraconic acid and the like, or vinyl hydrocarbons, for example, ethylene, propylene, styrene, α-methylstyrene and the like. . These may be mixed and used as a comonomer. Further, in addition to the above, esters of the unsaturated carboxylic acids such as methyl acrylate, ethyl acrylate, methyl methacrylate, dimethyl maleate and the like can also be used as a comonomer. Also,
The vinyl acetate copolymer may be a graft copolymer onto polyvinyl acetate.

Particularly preferred specific examples of the vinyl acetate copolymer include, for example, vinyl acetate-acrylic acid copolymer,
Vinyl acetate-methacrylic acid copolymer, vinyl acetate-styrene-acrylic acid copolymer, vinyl acetate-styrene-maleic anhydride copolymer, vinyl acetate-acrylic acid-methyl acrylate copolymer, vinyl acetate-methacrylic acid -Methyl acrylate copolymer, vinyl acetate-acrylic acid-ethyl acrylate copolymer, vinyl acetate-methacrylic acid-
Examples thereof include a methyl methacrylate copolymer and a vinyl acetate-maleic anhydride copolymer. Emulsions and hydrosols of polyvinyl acetate and the above-mentioned vinyl acetate copolymer can be easily obtained as commercial products.

The water-solubilized vinyl acetate copolymer is obtained by salt-forming the above-mentioned vinyl acetate copolymer with an inorganic or organic base and solubilizing the water,
Examples thereof include alkali metal salts such as sodium and potassium, and organic salts such as ammonium salts and organic amine salts. Such a water-solubilized vinyl acetate copolymer can also be obtained as a commercial product.

Similarly, the water-solubilized alkyd resin is
An alkyd resin having a free carboxyl group obtained from an excessive amount of a polybasic acid and a polyhydric alcohol is neutralized with an alkali metal base, an ammonium base, an organic amine, and the like, and is made water-solubilized. These can also be obtained as commercial products.

The water-solubilized urethane resin also has, for example, a carboxyl group in the polymer main chain, and the carboxyl group is converted into an alkali metal base, an ammonium base,
It is obtained by solubilizing with water by neutralizing salt with an organic amine or the like, and these can also be obtained as commercial products. Further, emulsions and hydrosols of alkyd resins and urethane resins can also be obtained as commercial products.

As the water-soluble resin, for example, synthetic resins such as polyvinyl alcohol resin, polyvinyl acetal resin and polyvinyl pyrrolidone resin are preferably used.
Natural water-soluble resins such as gum arabic and shellac can also be used. Among these, a polyvinyl alcohol resin is particularly preferably used.

Such a cold film-forming resin is contained in the ink composition according to the present invention in a range of 0.1 to 20% by weight, preferably 0.3 to 15% by weight, as a solid content. When the resin is excessively contained, the viscosity of the ink composition is too high, so that the writability is deteriorated and the erasability is reduced. On the other hand, when the content of the resin is too small, the handwriting is extended and stains the writing surface, and the erasability of the handwriting is poor.

Further, in the ink composition according to the present invention, a water-soluble polyhydric alcohol may be blended as a release aid in order to enhance the effect of the release agent. Such polyhydric alcohols include, for example, ethylene glycol, diethylene glycol, triethylene glycol,
Examples thereof include propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of about 200 to 600, polypropylene glycol having a molecular weight of 1,000 to 3,000, glycerin, and trimethylolpropane. Such a polyhydric alcohol is blended in the ink composition in an amount of 20% by weight or less, preferably 10% by weight or less. When more than 20% by weight is excessively used in the ink composition,
It is not preferable because the viscosity of the ink composition becomes excessively high and the writability decreases.

The ink composition according to the present invention may preferably contain various surfactants as another release aid. As such a surfactant, any of an anion, a cation, a nonionic, and an amphoteric surfactant can be used. In particular, an anionic, nonionic, or fluorine-based surfactant is preferably used.

Examples of the anionic surfactant include sulfo fatty acid ester salts such as dioctyl sodium sulfosuccinate, higher alcohol sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl aryl sulfonates, and olefin sulfonic acids. Salts and the like can be mentioned. Examples of the nonionic surfactant include, for example, polyoxyethylene ether-type nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether, polyhydric alcohol fatty acid esters, and polyhydric alcohol fatty acid ester polyoxyethylene. Oxyethylene ether and the like can be mentioned.

[0036] The ink composition according to the present invention is used as a drying accelerator for enhancing the drying property of handwriting, usually not more than 15% by weight, preferably not more than 15% by weight, based on the ink composition, to the extent that the emulsion contained in the ink composition is not destroyed. Is 1
A lower aliphatic alcohol may be contained in the range of 10% by weight. Particularly, ethanol, propanol or butanol is preferably used.

In addition to the above, the ink composition may optionally contain any pH adjuster, preservative, preservative, and the like, which are usually added to the aqueous ink composition.

The handwriting of the ink composition according to the present invention on a non-absorbable or non-permeable penetrating surface is such that when the water evaporates, ie, when the handwriting dries, the resin contains a colorant. On the other hand, an emulsion of a non-volatile oil at room temperature, such as an aliphatic carboxylic acid ester, a higher hydrocarbon, or a higher alcohol, as the release agent is destroyed, and the oil layer described above becomes non-absorbable. Since it is formed between the surface and the resin film, the handwriting has erasability.

A surfactant as a peeling aid has an effect of assisting separation of the oily layer and the pigment-containing resin film in handwriting during writing. However, the surfactant also enhances the leveling property at the time of writing, eliminates the uneven distribution of the release agent emulsion in the handwriting before drying on the writing surface, and has the effect of imparting uniform erasability after drying the handwriting. Have.

The ink composition according to the present invention is prepared by mixing the above-mentioned aqueous dispersion of the organic pigment with water, stirring the mixture, and adding the above-mentioned release agent, that is, an aqueous emulsion of an oily substance which is hardly volatile at room temperature to a resin. Is added, mixed and stirred. When blending various auxiliaries, for example, the above-mentioned cyclodextrins, water-soluble polyhydric alcohols, surfactants, drying accelerators, pH adjusters and preservatives, preservatives, etc., the organic pigment aqueous dispersion What is necessary is just to mix and stir the necessary auxiliary agent with water together with the body.

According to the present invention, a stable ink composition can be obtained by such a method without separating the hardly volatile oily substance at the ordinary temperature.

[0042]

As described above, the aqueous erasable marking pen ink composition according to the present invention is a stable composition which does not separate components by mixing and stirring the required components in a predetermined order. As a colorant, an aqueous dispersion of an organic pigment containing an organic pigment having an aromatic polycyclic structure, preferably an aqueous dispersion of an anthraquinone-based, perylene-based or perinone-based organic pigment can be used. Thereby, the ink composition, that is, even in the initial stage after writing where the handwriting is not yet sufficiently dried,
It has excellent erasability, and after erasing by rubbing the handwriting with an eraser, almost no stain remains on the white plate. Of course, it has excellent erasability after the handwriting has dried.

According to the ink composition of the present invention, since the organic pigment has a large cohesive force, the organic pigment is agglomerated and coarsened even in the initial stage after writing, where the handwriting has not yet been sufficiently dried. Therefore, it is difficult to penetrate into fine recesses such as scratches on a white board, and since it is coarsened and easily wiped off by the eraser, even when the handwriting is not yet sufficiently dried, By rubbing with the eraser, the white plate can be wiped off without leaving any stains on the white plate, and thus it is considered that the erasability is excellent even in the initial stage after writing, which has not been dried yet.

Further, the anthraquinone-based, perylene-based or perinone-based organic pigments have a lower coloring power than the azo-based pigments conventionally used in ink compositions for marking pens. In addition, not only in the initial stage of writing, but also after drying of the handwriting, even if the handwriting is erased and the pigment remains on the erased mark, the stain is hardly noticeable.

[0045]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. In the following Examples and Comparative Examples, the amount of components is% by weight.
And the balance is water. The coloring agents used are as follows.

Colorant 1: Anthraquinone-based organic pigment, Chromophthal Red A2B (Pigment Red 17
7, a Ciba Specialty Chemicals) dispersion in water with a dispersant styrene-acrylic resin. Colorant 2: perylene organic pigment, Paliogen Black S-0084 (Pigment Black 32, BASF
(Aqueous dispersion) obtained by dispersing styrene-acryl resin in water with a dispersant styrene-acrylic resin. Coloring agent 3: Perylene organic pigment, Paliogen Black S-0084 (Pigment Black 32, BASF
(Aqueous dispersion) obtained by dispersing the above in water with a dispersant styrene-maleic acid resin. Colorant 4: an aqueous dispersion in which an azo organic pigment, Shimura First Red 4127 (manufactured by Dainippon Ink and Chemicals, Inc.) is dispersed in water with a dispersant styrene-acrylic resin. Colorant 5: an aqueous dispersion in which carbon black and Monarch 900 (Pigment Black 7, manufactured by Cabot Specialty Chemicals) are dispersed in water with a dispersant styrene-acrylic resin.

Example 1 Colorant 1 15.0 Release Agent Cetyl Isooctanoate Emulsion (40% Oil) 10.0 Resin Polyurethane Resin Emulsion (35% Solids) 10.0 Auxiliaries Sodium Dioctyl Sulfosuccinate 0.5 Polyoxyethylene nonyl phenyl ether 0.2 Fluorinated surfactant 0.1 Preservative and fungicide (effective amount)

Example 2 Colorant 1 15.0 Release Agent Emulsion of tri (caprylic capric acid) glyceride (oil content 40%) 15.0 Resin Polyvinyl alcohol resin aqueous solution (solid content 20%) 20.0 Auxiliary dimethyl -Β-cyclodextrin aqueous solution (solid content 15%) 10.0 Sodium dioctylsulfosuccinate 1.0 Polyoxyethylene nonylphenyl ether 0.1 Fluorinated surfactant 0.2 Preservative and fungicide (effective amount)

Example 3 Colorant 2 15.0 Release Agent Cetyl Isooctanoate Emulsion (Oil Content 40%) 10.0 Resin Polyurethane Resin Emulsion (35% Solid Content) 10.0 Auxiliaries Dimethyl-β-cyclodextrin Aqueous Solution ( (Solid content 15%) 5.0 Sodium dioctyl sulfosuccinate 1.0 Polyoxyethylene nonyl phenyl ether 0.5 Fluorinated surfactant 0.1 Preservative and fungicide (effective amount)

Example 4 Colorant 3 15.0 Release Agent Emulsion of tri (caprylic capric acid) glyceride (oil content 40%) 15.0 Resin Polyvinyl alcohol resin aqueous solution (solid content 20%) 20.0 Auxiliary agent Dioctyl Sodium sulfosuccinate 0.5 Polyoxyethylene nonyl phenyl ether 0.2 Fluorinated surfactant 0.1 Preservative and fungicide (effective amount)

Comparative Example 1 Colorant 4 15.0 Release Agent Cetyl Isooctanoate Emulsion (Oil Content 40%) 15.0 Resin Polyvinyl Alcohol Resin Aqueous Solution (Solid Content 20%) 20.0 Auxiliaries Dimethyl-β-cyclodextrin Aqueous Solution (Solid content 15%) 10.0 Sodium dioctyl sulfosuccinate 0.5 Polyoxyethylene nonyl phenyl ether 0.2 Fluorosurfactant 0.1 Preservative and fungicide (effective amount)

Comparative Example 2 Colorant 5 15.0 Release Agent Emulsion of tri (caprylic capric acid) glyceride (oil content 40%) 20.0 Resin Polyurethane resin emulsion (solid content 35%) 10.0 Auxiliary dimethyl- β-cyclodextrin aqueous solution (solid content 15%) 5.0 Sodium dioctyl sulfosuccinate 1.0 Polyoxyethylene nonylphenyl ether 0.5 Fluorinated surfactant 0.1 Antiseptic and fungicide (effective amount)

The above ink composition was filled in a core-type marking pen, and written on each of an acrylic-coated white board, an enamel-white board, and a melamine-coated white board at a temperature of 20 ° C. and a relative humidity of 65%, and after 5 seconds, When the handwriting was not yet dried, a load was applied to the erasing jig and the rubbing was performed to examine the erasing ability of the handwriting. The evaluation criteria are as follows. ○ indicates load 200
g, can be completely erased by 5 reciprocations.
X: Completely erasable in 0 reciprocations. X: 200 g load, even if rubbed for 10 reciprocations or more, stains remain on the white plate. Table 1 shows the results.

[0054]

[Table 1]

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J039 AB01 AD03 AD06 AD07 AD08 AD09 AD14 AE04 AE06 BC07 BC11 BC12 BC20 BC24 BC25 BE01 BE22 CA06 DA02 DA05 EA47 EA48 GA21

Claims (10)

[Claims] 1. An aqueous dispersion of an organic pigment obtained by dispersing an organic pigment having an aromatic polycyclic structure in water using a dispersant is mixed with water and stirred, and the resulting mixture is hardly volatile at room temperature. An aqueous erasable marking pen ink composition obtained by adding an aqueous emulsion prepared by emulsifying an oily substance with an emulsifier and a resin, mixing and stirring. 2. The aqueous erasable marking pen ink composition according to claim 1, wherein the organic pigment is an anthraquinone-based, perylene-based or perinone-based organic pigment. 3. The aqueous erasable marking pen ink composition according to claim 1, wherein the dispersant is a styrene-acrylic resin or a styrene-maleic acid resin. 4. The aqueous erasable marking pen ink composition according to claim 1, wherein the oily substance which is hardly volatile at normal temperature is at least one selected from aliphatic carboxylic esters, higher hydrocarbons and higher alcohols. 5. The aqueous erasable marking pen ink composition according to claim 1, wherein the surfactant is mixed with water together with the organic pigment aqueous dispersion. 6. An organic pigment aqueous dispersion obtained by dispersing an organic pigment having an aromatic polycyclic structure in water using a dispersing agent is mixed with water and stirred, and the resulting mixture is hardly volatile at room temperature. A method for producing an aqueous erasable marking pen ink composition, comprising adding an aqueous emulsion prepared by emulsifying an oily substance with an emulsifier and a resin, mixing and stirring. 7. The method for producing an aqueous erasable marking pen ink composition according to claim 6, wherein the organic pigment is an anthraquinone-based, perylene-based or perinone-based organic pigment. 8. The method according to claim 6, wherein the dispersant is a styrene-acrylic resin or a styrene-maleic acid resin. 9. The aqueous erasable marking pen ink composition according to claim 6, wherein the oily substance which is hardly volatile at room temperature is at least one selected from aliphatic carboxylic acid esters, higher hydrocarbons and higher alcohols. Method. 10. The method for producing an aqueous erasable marking pen ink composition according to claim 6, wherein the surfactant is mixed with water together with the organic pigment aqueous dispersion.