JP7417441B2 - Water-based ink composition for marking pen and marking pen - Google Patents

Description

The present invention relates to an aqueous ink composition for a marking pen and a marking pen.

Titanium oxide is used as a hiding pigment in aqueous ink compositions used in marking pens and the like. Since titanium oxide has high hiding properties, by including it in a writing ink composition, it is possible to draw clear lines that are not affected by the base.

Titanium oxide has a large specific gravity and has the property of settling and agglomerating, and is known to settle and agglomerate in an ink tank built into a marking pen. Therefore, if the titanium oxide is left unused for a long period of time or stored in a place with large environmental changes such as temperature, the precipitated titanium oxide will form a strongly aggregated state (hard cake), and the redispersibility of the titanium oxide will deteriorate. It ends up.

Conventionally, in order to suppress hard cake, improvements have been made to the components constituting water-based ink compositions. For example, in the invention described in Patent Document 1, precipitation of pigment is suppressed by blending wet silica, hydrous kaolin, and an aggregation control agent. Furthermore, in the invention described in Patent Document 2, the redispersibility is improved by blending an extender, an aggregating and dispersing agent, and nylon into the ink composition.

Japanese Patent Application Publication No. 2018-104579 JP2018-095730A

The aqueous ink composition of the present invention is applied, for example, to a marking pen containing a built-in metal ball for the purpose of loosening the agglomeration of titanium oxide. By shaking the marking pen, the metal ball moves up and down within the ink tank, redistributing the agglomerated titanium oxide.

However, conventional water-based ink compositions for marking pens have insufficient hard cake suppression effects, and if marking pens are left unused for a long period of time, the number of stirrings required to redisperse the agglomerated titanium oxide is high. There was a problem.

Another possible method is to increase the viscosity of the aqueous ink composition for marking pens to prevent titanium oxide from agglomerating, but in this case, a problem arises in that the ink is not easily ejected from the pen tip.

The present invention has been made in view of this point, and an object of the present invention is to provide an aqueous ink composition for a marking pen and a marking pen that can suppress hard cake.

The aqueous ink composition for marking pens of the present invention is characterized by containing titanium oxide, a water-soluble resin as a dispersant, and ditridecylsulfosuccinic acid as a dispersion aid .

In the present invention, the ditridecylsulfosuccinic acid is preferably contained in a range of 0.1% by mass or more and 6.0% by mass or less based on the total amount of the aqueous ink composition for marking pens.

The marking pen of the present invention is characterized by containing the above-mentioned aqueous ink composition for marking pens.

According to the aqueous ink composition for marking pens of the present invention, hard cake can be suppressed. Therefore, in a marking pen containing the aqueous ink composition for a marking pen of the present invention, the number of times of stirring required to redisperse titanium oxide can be reduced.

FIG. 2 is a cross-sectional view showing an example of a marking pen according to the present embodiment.

Hereinafter, one embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail. Note that the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist. Furthermore, the notation “~” includes both the lower limit value and the upper limit value as a range.

Titanium oxide, which has excellent hiding properties, has been used as a pigment in aqueous ink compositions for marking pens. Titanium oxide, which has a high specific gravity, tends to aggregate, so it was necessary to shake the marking pen, move the metal ball built into the main body up and down, and stir it to redisperse the titanium oxide. When this agglomeration becomes strong (hard cake), there is a problem that the number of times of stirring required for redispersion increases.

Therefore, as a result of extensive research into aqueous ink compositions for marking pens, the present inventors discovered that hard cake can be suppressed by containing ditridecylsulfosuccinic acid, leading to the completion of the present invention. That is, the aqueous ink composition for a marking pen in this embodiment is characterized by containing titanium oxide and ditridecylsulfosuccinic acid.

<Pigment>
The titanium oxide used as the pigment is not limited, and all commercially available titanium oxides can be used. For example, various types of titanium oxide such as rutile type and anatase type can be used, and these titanium oxides may be surface-treated, such as silica treatment, alumina treatment, zirconia treatment, or silane coupling agent treatment. You can. These titanium oxides can be used alone or in combination. The amount of titanium oxide to be used is not particularly limited, but from the viewpoint of concealment of drawn lines, stability over time, viscosity of ink when used as a writing instrument, etc. It is preferable to add 40% by mass. Further, the average particle diameter of titanium oxide is not particularly limited, but is preferably about 200 to 400 nm.

In this embodiment, in addition to titanium oxide, other coloring materials such as pigments and dyes can be mixed. For example, metal powder such as aluminum flakes may be contained in order to impart glitter to the drawn lines.

<Ditridecyl sulfosuccinic acid>
In this embodiment, ditridecylsulfosuccinic acid can be contained as a dispersion aid. In the present embodiment, the amount of ditridecyl sulfosuccinic acid added is preferably in the range of 0.1% by mass or more and 6.0% by mass or less based on the total amount of the aqueous ink composition for marking pens. It is more preferably contained in a range of 0.2 to 4% by mass, still more preferably contained in a range of 1 to 3% by mass, and most preferably contained in a range of 1 to 2% by mass. By applying an aqueous marking pen ink composition containing ditridecyl sulfosuccinic acid within this range to a marking pen, precipitated titanium oxide becomes difficult to form a hard cake, and the redispersibility of titanium oxide can be improved. can. In this embodiment, redispersibility can be determined by the number of times the marking pen is stirred.

As described above, in this embodiment, the hard cake suppression effect is improved by adding an appropriate amount of ditridecyl sulfosuccinic acid to the aqueous ink composition for marking pens because steric hindrance is strengthened and oxidation It is speculated that this is due to increased lubricity between titanium.

<Other ingredients>
The aqueous ink composition for a marking pen in this embodiment contains at least titanium oxide and ditridecylsulfosuccinic acid. In addition to these components, each component commonly used in aqueous ink compositions, such as a dispersant, a surfactant, a water-soluble organic solvent, a viscosity modifier, and a fixing agent, may be added as necessary to the extent that the effects of the present invention are achieved. It can contain a resin, a rust preventive, a preservative or antibacterial agent, a pH adjuster, and the like. Further, as the remainder of the constituent components, it is preferable to use a solvent such as tap water, purified water, distilled water, ion exchange water, or pure water.

In this embodiment, a water-soluble resin can be contained as the dispersant and the fixing resin. For example, at least one type is selected from water-soluble resins such as acrylic resins, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, and urethane resins, and resin emulsions such as acrylic emulsions, vinyl acetate emulsions, and urethane emulsions. can do.

In this embodiment, the surfactant is not particularly limited, but at least one type of surfactant selected from fluorine-based surfactants, acetylene glycol-based surfactants, and silicone-based surfactants can be used. .

Examples of the water-soluble organic solvent in this embodiment include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, and glycerin, ethylene glycol monomethyl ether, and diethylene glycol monomethyl. Examples include ether, and these can be used alone or in combination of two or more.

In this embodiment, natural polymers such as polysaccharides and synthetic polymers can be used as the viscosity modifier. Examples of polysaccharides include gum arabic, gum tragacanth, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, xanthan gum, welan gum, succinoglycan, diutan gum, dextran, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, and starch glycol. Acids and their salts can be used. Examples of synthetic polymers include polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylic acid and its salts, polyethylene oxide, vinyl acetate-polyvinylpyrrolidone copolymer, styrene-acrylic acid copolymer and its salts, and isobutylene maleic anhydride copolymer. Polymers and their salts can be used.

As the preservative or antibacterial agent in this embodiment, phenol, sodium omazine, sodium benzoate, benzisothiazoline, benzimidazole compounds, etc. can be used. Further, as the rust preventive agent, benzotriazole, tolyltriazole, dicyclohexyl ammonium nitrite, saponins, etc. can be used.

In this embodiment, the pH adjuster includes amine compounds such as triethanolamine, diethanolamine, monoethanolamine, dimethylethanolamine, morpholine, and triethylamine, ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. Alkali metal hydroxides and the like can be used.

The aqueous ink composition according to this embodiment can be used by being stored in a marking pen. The specific structure of the marking pen is shown in Figure 1.

FIG. 1 is a sectional view of a marking pen according to this embodiment. The structure shown in FIG. 1 is merely an example, and does not limit the structure of the marking pen. The aqueous ink composition for marking pens of this embodiment is preferably applied to, for example, a valve-type marking pen as shown in FIG.

As shown in FIG. 1, the barrel 1, which is the main container of the marking pen according to the present embodiment, has a bottomed cylindrical shape with an open end. The rear part of the barrel 1 constitutes an ink tank 2 which is a space for accommodating a water-based ink composition for a marking pen. A distal end portion 3 having an open distal end is attached to the front portion of the shaft cylinder 1 by screwing. A pen core 4, which serves as a pen tip, protrudes from the opening of the tip portion 3. The pen core 4 is inserted into and held in a cylindrical holder 5 arranged inside the tip 3. A spherical stirrer 11 such as a stainless steel ball is housed inside the ink tank 2 to stir the aqueous ink composition for a marking pen.

As shown in FIG. 1, a valve 6 is housed inside the front portion of the shaft cylinder 1. As shown in FIG. In the valve 6, when the pen core 4 is pressed, the valve stem 7 inside the valve 6 retreats, and the retreated valve stem 7 is moved toward the tip by the elastic force of the spring 8 provided around the valve stem 7. It has a mechanism that pushes it back. A valve seat 9 is provided that closes and opens the ink flow path from the ink tank 2 to the pen core 4. When the pen core 4 is pressed, the valve stem 7 retreats, and a valve seat 9 is formed on the valve stem 7. The valve 10 is separated from the valve seat 9. As a result, the flow path from the ink tank 2 to the pen core 4 is opened, and the aqueous marking pen ink composition flows into the flow path. Further, from this state, when the pressure of the pen core 4 weakens, the valve rod 7 is pushed back toward the tip by the elastic force of the spring 8, the valve 10 comes into contact with the valve seat 9, and the flow path is closed.

In the marking pen having such a structure, when the user shakes the marking pen, the stirrer 11 inside the ink tank 2 moves up and down. By moving the stirrer 11 up and down, the precipitated and aggregated titanium oxide is redispersed. As described above, by using the aqueous ink composition for marking pens of this embodiment, hard cake of titanium oxide can be suppressed. Therefore, the number of times of stirring required to redisperse titanium oxide can be reduced, and a comfortable feeling can be provided to the user.

In particular, as shown in the experiments described below, even if a marking pen containing the aqueous ink composition for marking pens of this embodiment is left in a high-temperature environment for a long period of time, hard cake can be appropriately suppressed and good regeneration can be achieved. Dispersibility can be obtained. For example, when a marking pen is left for 12 weeks in an environment with a temperature of 50° C., the marking pen can be stirred no more than 10 times.

Hereinafter, the effects of the present invention will be explained using Examples and Comparative Examples of the present invention. Note that the present invention is not limited in any way by the following examples.

<Components of water-based ink composition for marking pen>
In the experiment, the following raw materials were used to obtain a water-based ink composition for marking pens.

Pigment: Titanium oxide: Ti Pure (registered trademark) R-900 (manufactured by Chemours)
Dispersant: Styrene-acrylic resin: Joncryl (registered trademark) 63J (manufactured by BASF)
pH adjuster: Triethanolamine Surfactant: Fluorine surfactant: Capstone FS-10 (manufactured by Chemours)
Preservative: Benzisothiazoline: Bioden S (manufactured by Daiwa Chemical Industries)
Water-soluble organic solvent: Propylene glycol Viscosity modifier: Xanthan gum: Echo Gum (registered trademark) RD (manufactured by CP Kelco)
Fixed resin: Acrylic emulsion: Aron (registered trademark) A-106 (manufactured by Toagosei Co., Ltd.)
Dispersion aid: Sodium ditridecyl sulfosuccinate
Dispersion aid: dioctyl sulfosuccinate Na
Dispersion aid: Sodium dicyclohexylsuccinate
Solvent: ion exchange water

In each of Examples 1-4 and Comparative Examples 1-3, aqueous ink compositions for marking pens were prepared by changing the type and amount of the dispersion aid.

In each of Examples 1-4 and Comparative Example 1-3, the prepared aqueous ink compositions for marking pens were filled into marking pens having the following configuration.

<Composition of marking pen>
Writing instrument name: Posca (registered trademark) PC-5M (manufactured by Mitsubishi Pencil Co., Ltd.)
Shaft material: PP resin Pen core material: PET fiber Stirrer material: Stainless steel (φ: 6.4 mm)
Ink supply method: Valve type

Then, redispersibility was evaluated using marking pens filled with the aqueous ink compositions for marking pens of Example 1-4 and Comparative Example 1-3. Table 1 shows the evaluation results.

<Redispersibility evaluation>
In each Example 1-4 and Comparative Example 1-3, redispersibility was evaluated. Evaluation of redispersibility was performed under the conditions shown below.

The marking pen filled with the aqueous ink composition for marking pens was left for 12 weeks in an environment at a temperature of 50° C. with the cap facing upward. After 12 weeks, the marking pen was shaken and stirred by moving the stirring bar up and down, and the number of times of stirring until a good drawn line was obtained was determined. As a criterion for evaluating redispersibility, the range of the number of times of stirring was set as follows.

(Redispersibility evaluation criteria)
A: 1-5 times B: 6-10 times C: 11-20 times D: 21 times or more

As shown in Table 1, the redispersibility of Example 1 was in the range of 6 to 10 times of stirring, and was rated B. Further, the redispersibility of Example 2-4 was in the range of 1 to 5 times of stirring, and was rated A. In contrast, in Comparative Example 1-3, the redispersibility was rated D. From these results, it was found that by adding ditridecylsulfosuccinic acid to the aqueous ink composition for marking pens, it was possible to suppress hard cakes, improve the redispersibility of titanium oxide, and reduce the number of times of stirring.

From the above, it was found that in this example in which ditridecylsulfosuccinic acid was added, it was possible to obtain the effect of suppressing hard cake.

Further, from the experimental results of Examples 1-4, the amount of ditridecyl sulfosuccinic acid added is preferably in the range of 0.1 to 6.0% by mass based on the total amount of the ink composition, and 0.1% to 6.0% by mass, based on the total amount of the ink composition. It has been found that the content is more preferably in the range of 2 to 4% by mass, and even more preferably in the range of 1 to 3% by mass. Particularly preferably, Examples 2, 3, and 4 are rated A in redispersibility, and the amount of ditridecylsulfosuccinic acid added is in the range of 1 to 3% by mass based on the total amount of the ink composition. Ta.

By using the aqueous ink composition for marking pens of the present invention in marking pens, hard cake can be suppressed and titanium oxide can be redispersed with a small number of stirrings. Therefore, it is possible to provide the user with a comfortable feeling of use.

1: Barrel 2: Ink tank 3: Tip 4: Pen core 5: Holder 6: Valve 7: Valve stem 8: Spring 9: Valve seat 10: Valve 11: Stirrer

Claims (3)

Titanium oxide, a water-soluble resin as a dispersant,
ditridecylsulfosuccinic acid as a dispersion aid ;
An aqueous ink composition for a marking pen, comprising: The ditridecyl sulfosuccinic acid is contained in a range of 0.1% by mass or more and 6.0% by mass or less based on the total amount of the aqueous ink composition for marking pens. Water-based ink composition for marking pens. A marking pen containing the aqueous ink composition for marking pens according to claim 1 or 2.

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