JP7245672B2 - Water-based ink composition for writing instruments, writing instruments and water-based ink products using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an aqueous ink composition for writing instruments, a writing instrument using the same, and an aqueous ink product. More particularly, the present invention relates to a water-based ink composition for writing instruments which is excellent in antibacterial performance and pigment dispersion stability, a writing instrument using the same, and water-based ink products.

Conventionally, low-viscosity ink using a pigment as a coloring agent is filled in a fountain pen, a ball-point pen, or the like, and written on a writing medium. Since it can be done, it is being actively studied.
However, in writing instruments such as fountain pens, in which a comb tooth-shaped ink reservoir member capable of supplying ink from an ink reservoir to the writing tip is arranged as an ink flow rate adjusting body, the writing tip is exposed to the atmosphere for a while. In addition, such writing utensils are used by repeatedly filling ink stored in an ink storage container with an opening and closing opening such as an ink bottle, and the ink composition is exposed to the outside air more often. something happened. Exposure of the ink composition to the outside air also increases the chances of contamination by microorganisms. As a result, microorganisms may proliferate abnormally, and depending on the type of antibacterial substance, there is a problem that the antibacterial performance is not sufficiently exhibited. If the antibacterial performance is not sufficient, microorganisms will propagate and the ink composition will rot, causing changes in the physical properties of the ink composition such as viscosity, and foreign substances such as precipitates and aggregates will occur in the ink composition. In addition, when a pigment ink is used, the ink composition functions as a function of the ink composition may be impaired, such as destruction of the dispersion of the pigment due to the influence of the generated foreign matter. When used in a writing instrument, foreign substances such as deposits and aggregates due to propagation of microorganisms may occur in the ink supply mechanism, narrowing the flow path for supplying the ink composition. As a result, the amount of ink supplied is reduced, which may affect the writability, such as blurring of handwriting. Furthermore, if the amount of foreign matter increases or the amount of agglomeration increases, the flow path for supplying ink may be blocked by the foreign matter, making it impossible to supply ink and making writing impossible. In addition, even with an ink composition that generates a small amount of foreign matter, if the ink is repeatedly filled and used, even if the writing performance is good at the beginning of use, the ink will be supplied by repeating filling and use. Foreign matter gradually accumulates in the flow path, and the influence on writing performance increases. Further repetition of filling and use may lead to further accumulation of foreign matter in the flow path, blockage of the flow path, and the possibility of becoming unable to write again.
Therefore, an antibacterial substance is added to the ink composition to suppress the propagation of microorganisms (see Patent Documents 1, 2 and 3). However, depending on the materials used and their combinations, the effect could not be fully exhibited, and there was room for improvement.
In addition, from the viewpoint of safety, there are restrictions on the use of some antibacterial agents, and in some cases, sufficient antibacterial performance cannot be exhibited.

JP-A-2002-322406 JP-A-2004-231895 JP-A-2007-9046

The present invention has a writing tip and an ink reservoir, and ink can be supplied from the ink reservoir to the writing tip between the writing tip and the ink reservoir. A water-based ink composition for writing instruments, which is incorporated in an ink reservoir of a writing instrument in which an ink flow rate regulator (hereinafter sometimes simply referred to as a "pen core") having a comb tooth-shaped ink reservoir that effectively retains ink is disposed. Aqueous ink composition for writing utensils (hereinafter simply referred to as "aqueous ink composition" or "ink composition") that has excellent pigment dispersibility, excellent antibacterial performance, etc. and excellent ink storage stability. There is), writing instruments using it, and water-based ink products.

The present invention has solved the above problems by providing a water-based ink composition for writing instruments containing self-dispersible carbon black and ortho-phenylphenol or a salt thereof.
That is, the present invention
"1. A water-based ink composition for writing instruments comprising water, a coloring agent, and an antibacterial substance, wherein the coloring agent is self-dispersing carbon black, and the antibacterial substance is ortho-phenylphenol or a salt thereof. , and at least one of 1,2-benzisothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one, wherein the orthophenylphenol or a salt thereof and the 1,2-benzisothiazolin- 3-one and at least one of the 2-n-octyl-4-isothiazolin-3-one in a weight ratio of 1:1 to 1:0.01. .
2. 2. The water-based ink composition for writing instruments according to item 1, wherein the amount of the ortho-phenylphenol or its salt added is 100 to 10,000 ppm.
3. Item 1 or The water-based ink composition for writing instruments according to Item 2.
4 . Items 1 to 5, wherein the ink composition has a viscosity of 1.0 to 5.0 mPa s when measured using a B-type rotational viscometer at a rotational speed of 60 rpm and 20°C. 3. The water-based ink composition for writing instruments according to any one of 3 items.
5 . The water-based ink composition for writing instruments has a writing tip and an ink reservoir, and ink can be supplied from the ink reservoir to the writing tip between the writing tip and the ink reservoir as the internal pressure of the ink reservoir rises. Item 1. A water-based ink composition for writing instruments, which is incorporated in an ink reservoir of a writing instrument in which an ink flow rate regulator having a comb tooth-shaped ink reservoir for temporarily holding overflowed ink is arranged. 4. The water-based ink composition for writing instruments according to any one of 4. to 4. above.
6 . A writing instrument filled with the water-based ink composition for writing instruments according to any one of items 1 to 5 .
7 . A water-based ink product comprising the water-based ink composition for writing instruments according to any one of items 1 to 5 stored in an ink storage container, wherein the ink storage container stores the water-based ink composition for writing instruments. The water-based ink composition for a writing instrument has an opening and closing opening for dispensing, the water-based ink composition for a writing instrument dispensed from the ink storage container has a writing tip and an ink reservoir, and the writing tip and the ink reservoir are located between the writing tip and the ink reservoir. an ink reservoir of a writing utensil having a comb tooth-shaped ink reservoir that can supply ink from the ink reservoir to the writing tip and temporarily retain ink that overflows as the internal pressure of the ink reservoir increases; A water-based ink product characterized by being filled in a "About.

According to the present invention, by including self-dispersing carbon black and ortho-phenylphenol or a salt thereof in the ink composition, the dispersibility of the pigment is improved while maintaining the antibacterial performance of the ink composition, and the antifoaming performance is improved. It has excellent effects such as an improved ink composition.

The water-based ink composition for writing instruments of the present invention has a writing tip and an ink reservoir, and a pen core is arranged between the writing tip and the ink reservoir. One feature is that it contains water, self-dispersible carbon black, and ortho-phenylphenol or a salt thereof.

The water-based ink composition for writing instruments used in the present invention contains self-dispersing carbon black.
Self-dispersing carbon black refers to carbon black that can be dispersed in an aqueous medium without using a dispersant. For example, by subjecting carbon black to physical or chemical treatment, carbon black It has a hydrophilic functional group etc. on the surface of Since the self-dispersing carbon black does not contain components such as a dispersant, better color development can be obtained than the forced dispersion-type carbon black dispersion. In addition, because of its excellent redispersibility, even when the ink composition adheres to the writing tip of a writing instrument, the ink flow rate regulator, etc., it can be easily washed off.

Examples of the physical treatment include a vacuum plasma treatment, and examples of the chemical treatment include a wet oxidation method in which an oxidizing agent is used in water, and bonding p-aminobenzoic acid to the surface of the pigment. A method of bonding a carboxyl group via a phenyl group and the like can be mentioned.

The self-dispersing carbon black that can be used in the present invention is not particularly limited. Aqua-Black series manufactured by the company, Fuji-JET Black series manufactured by Fuji Pigment Co., Ltd., and the like.

These self-dispersing carbon blacks include anionic and cationic self-dispersing carbon blacks. It is preferred to use dispersed carbon black. Moreover, the self-dispersing carbon black can be used alone or in combination of two or more. However, when two or more of them are mixed and used, they preferably have the same ionicity so as not to affect the dispersibility of the carbon black, and more preferably have the same surface hydrophilic groups. .

The content of self-dispersing carbon black in the water-based ink composition is preferably 1 to 20% by mass, more preferably 1 to 10% by mass, based on the total mass of the water-based ink composition. is preferably 1 to 5% by mass. When the content of the self-dispersing carbon black is within the above range, it is possible to prevent deterioration of the ink follow-up performance to the writing tip and to obtain handwriting with good coloring.

The water-based ink composition for writing instruments according to the present invention uses ortho-phenylphenol or a salt thereof as an antibacterial substance. Ortho-phenylphenol is an antibacterial substance approved for use as a food additive, and is safer than conventional antibacterial substances. Specific examples include orthophenylphenol, sodium orthophenylphenol, and the like. Sodium orthophenylphenol is suitable because it has high solubility in the ink composition and the amount added can be arbitrarily adjusted.

Antibacterial substances such as 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, although the reason is not clear, It tends to reduce the dispersibility of the self-dispersing carbon black, and the pigment in the ink composition slightly aggregates. And especially when self-dispersing carbon black is used, the antibacterial effect is reduced, but this is 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n Antibacterial substances such as -octyl-4-isothiazolin-3-one are taken in and adsorbed by carbon black, which is thought to reduce the antibacterial performance.

However, in ortho-phenylphenol or its salt, since the phenol group is anion-charged, the anionic self-dispersing carbon black and ortho-phenylphenol or its salt electrically repel each other, resulting in self-dispersing carbon black. It becomes difficult to be adsorbed to, does not impair the dispersibility of the self-dispersing carbon black, and does not deteriorate the antibacterial performance of the ink composition. Furthermore, even when antibacterial substances such as 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and 2-n-octyl-4-isothiazolin-3-one are used in combination, It is preferable because it does not impair the dispersibility of the self-dispersing carbon black and can give a synergistic effect to the antibacterial performance. Considering more antibacterial performance, it is preferable to use 1,2-benzisothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one in combination.

The ortho-phenylphenol or its salt used in the present invention can further improve defoaming performance by adding it to the ink composition. Conventional antibacterial substances do not have defoaming properties even when added to ink compositions, but ortho-phenylphenol or a salt thereof used in the present invention has both antibacterial and defoaming properties.

The water-based ink composition for writing instruments according to the present invention can be suitably used for writing instruments having a specific structure, and examples include writing instruments having a structure in which the ink reservoir of the writing instrument is repeatedly filled with ink when used. . As an example of the ink reservoir, a so-called converter can be used. When the ink composition is filled into the converter, the ink composition is sucked while the air in the converter is discharged. As a result, ink can be sucked without generating unnecessary air bubbles.

Furthermore, since air bubbles are less likely to occur in the ink composition, even when the internal pressure of the ink reservoir rises, the ink composition smoothly flows into the comb tooth-shaped ink retaining member that temporarily retains the overflowing ink composition. The ink flows in and the ink is less likely to drip from the writing tip, making it an excellent ink composition.

The amount of ortho-phenylphenol or its salt added to the water-based ink composition for writing instruments of the present invention is preferably 100 to 10,000 ppm. More preferably, it is 100 to 5,000 ppm. If the amount is less than this range, the defoaming performance tends to be slightly inferior, and if the amount is more than this range, the stability and writing performance of the ink composition may be affected. When it is within the above range, the antifoaming performance is sufficient, the dispersibility of the pigment is effectively affected, the stability and writing performance are not affected, and the antibacterial performance is sufficiently obtained, which is preferable. .

The water-based ink composition for writing instruments according to the present invention can further contain an antibacterial substance within a range that does not impair the performance of the ink composition. The antibacterial substance is not particularly limited as long as it is an antibacterial substance that can be used in conventional ink compositions for writing instruments. 3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, 2-pyridinethiol-1-oxide sodium, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one and the like. In particular, use of 1,2-benzisothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one is preferable because an odorless ink composition can be obtained. It is more preferable because the antibacterial performance against resistant bacteria is enhanced.
Combined use of orthophenylphenol or a salt thereof with 1,2-benzisothiazolin-3-one and/or 2-n-octyl-4-isothiazolin-3-one has a synergistic effect on antibacterial performance without impairing dispersibility. It is particularly preferable because it is possible to reduce the total amount of the antibacterial substance while maintaining dispersion stability, antibacterial performance, and antifoaming properties.

The water-based ink composition for writing instruments of the present invention may use orthophenylphenol or a salt thereof and 1,2-benzisothiazolin-3-one and/or 2-n-octyl-4-isothiazolin-3-one in combination. However, the amount of 1,2-benzisothiazolin-3-one and/or 2-n-octyl-4-isothiazolin-3-one to be added is preferably 10 to 1,000 ppm. More preferably, it is 20 to 200 ppm. If the amount is less than this range, the effect of combined use cannot be obtained sufficiently, and if it is more than this range, the dispersibility of the self-dispersing carbon black may be deteriorated. Within the above range, there is no effect on the dispersibility of the self-dispersing carbon black, there is no problem with safety, and sufficient antibacterial performance can be obtained, which is preferable.

The water-based ink composition for writing instruments of the present invention may use orthophenylphenol or a salt thereof and 1,2-benzisothiazolin-3-one and/or 2-n-octyl-4-isothiazolin-3-one in combination. However, the addition amount ratio is preferably 1:1 to 1:0.01, preferably 1:0.2 to 1:0.02, in terms of mass ratio based on ortho-phenylphenol or its salt. is more preferable. Within this range, the antifoaming performance, the dispersibility of the self-dispersing carbon black, and the antibacterial performance are favorable, which is preferable.

The water-based ink composition for writing instruments according to the present invention comprises self-dispersible carbon black and ortho-phenylphenol or a salt thereof.
In general, surfactants and resin-based dispersants are used to disperse pigments such as carbon black. When dispersing carbon black, a dispersant suitable for the carbon black is selected in order to improve the dispersion stability of the carbon black. Functionality may be reduced. In this case, the carbon black cannot be stably dispersed, and the carbon black aggregates, making it impossible to maintain the dispersion stability of the ink composition. As described above, self-dispersing carbon black can be dispersed without using a dispersant. However, ortho-phenylphenol or a salt thereof can improve the dispersion stability of self-dispersing carbon black without impairing its dispersibility.

<Pigment>
The water-based ink composition according to the present invention can use pigments other than self-dispersing carbon black as long as the performance of the ink composition is not impaired. Examples of pigments to be used include pigments usually used in water-based ink compositions for writing instruments.

Pigments that can be used in the present invention are not particularly limited as long as they are dispersible in an aqueous medium. Examples include inorganic, organic, and processed pigments, and specific examples include carbon black (not self-dispersing), aniline black, ultramarine, chrome, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, Examples include quinophthalone-based, threne-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, aluminum pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments. In addition, a microcapsule pigment obtained by encapsulating or dissolving a colored body, which is obtained by dispersing a pigment in a medium as a colored resin particle body, in a shell made of a resin wall film-forming substance by a known microencapsulation method or the like may be used. good. As the pigment, a water-dispersible pigment product or the like which is finely and stably dispersed in an aqueous medium in advance using a surfactant or resin may be used.

<Water>
Water is not particularly limited, and for example, tap water, ion-exchanged water, ultrafiltered water, distilled water, or the like can be used.

The water-based ink composition according to the present invention can contain various additives such as wetting agents, water-soluble organic solvents, pH adjusters, moisturizing agents, and rust preventives within the range that does not impair the effects of the present invention.

<Other ingredients>
Various wetting agents can be used in the water-based ink composition of the present invention in order to improve the wettability of the ink flow regulator when used in a writing instrument. As the wetting agent, polyetheramine is preferably used, although it is not particularly limited. Polyetheramine can improve the dispersion stability of the self-dispersing carbon black and maintain the wettability of the ink flow controller appropriately.

In addition, since the polyetheramine can maintain an appropriate level of wettability with respect to the ink flow rate regulator, the function of the ink flow rate regulator can be sufficiently obtained. Even when the writing tip is turned downward for writing, the ink composition can smoothly flow down in the direction of the writing tip, and the ink ejection property from the writing tip can be maintained satisfactorily. In addition, since surplus ink can smoothly flow into the ink flow rate adjusting body, the dripping phenomenon of ink can be suppressed. Furthermore, when the water-based ink composition for writing instruments using polyetheramine is built into a writing instrument and written, the penetrability to the paper surface becomes high, and the handwriting does not bleed or strike through. , good handwriting can be obtained.

The HLB value of the polyetheramine that can be used in the present invention is preferably 10-20. This is because when the HLB value of the polyetheramine is 10 or more, it dissolves completely in water and does not form an aggregate with the self-dispersing carbon black, so the dispersion stability in the ink composition is not affected. This is because there is no effect.

The polyetheramine has an average addition mole number of ethylene oxide (EO number) of preferably 10-35, more preferably 13-30. If the average ethylene oxide addition mole number (EO number) of the polyetheramine is within the above numerical range, the effect of the polyetheramine can be obtained stably because of its high solubility in water.

Examples of the polyetheramine include polyoxyethylene stearylamine, polyoxyethylene (20) alkyl (C14-C18) amine, polyoxyethylene tallow alkylamine, polyoxyethylene alkylamine ether, polyoxyethylene laurylamine, polyoxyethylene. Alkyl (palm) amines and the like can be mentioned.

The content of the polyetheramine in the aqueous ink composition is preferably 0.1 to 2.0% by mass, more preferably 0.5 to 1.0% by mass, based on the total mass of the aqueous ink composition. It is more preferable to have

Water-soluble organic solvents include (i) glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, (ii) methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t - alcohols such as butanol, propargyl alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, ethylene glycol monomethyl ether acetate and other higher alcohols, and (iii) ethylene glycol monomethyl ether, ethylene glycol mono Glycol ethers such as ethyl ether, 3-methoxybutanol, and 3-methoxy-3-methylbutanol are included. The amount of the water-soluble organic solvent added is preferably 0.1 to 10% by mass, more preferably 0.1 to 7% by mass, relative to the water-based ink composition.

Examples of pH adjusters include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate and sodium hydroxide; basic organic compounds such as sodium acetate, triethanolamine and diethanolamine; lactic acid and citric acid; Considering the stability of the ink composition over time, it is preferable to use a basic organic compound, and more preferably, it is preferable to use triethanolamine, which is weakly basic. These pH adjusters may be used alone or in combination of two or more.
The content of the pH adjuster is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the water-based ink composition.

Examples of moisturizing agents include urea, sorbitol, N,N,N-trialkylamino acids, and the like, in addition to the water-soluble organic solvents. In particular, N,N,N-trialkylamino acids are preferred because they have extremely high moisture retention when dry compared to other moisturizing agents. The amount of the humectant added is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, relative to the water-based ink composition.

The N,N,N-trialkylamino acids are represented by the following formula (1).

Linear or branched alkyl groups can be widely used as R ₁ to R ₃ . Examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group and tert-butyl group. R ₁ to R ₃ may be the same or different. Specific examples include trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine with n=1, trimethyl-β-alanine with n=2, and trimethyl-γ-aminobutyric acid with n=3. Trimethylglycine is preferably selected and used in consideration of the improvement of dry-up resistance and the improvement of the storage stability of the water-based ink composition.

Rust inhibitors include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, dialkylthiourea, and the like.

Chelating agents include ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), glycol etherdiaminetetraacetic acid (GEDTA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG ), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA) and their alkali metal salts, ammonium salts or amine salts.

A writing instrument in which the pen core used in the present invention is arranged as an ink flow controller can be replenished with ink by the user repeatedly, and the replenished ink may be stored in an ink container such as a glass bottle. Glass bottles are inexpensive, easy to mold, and easy to obtain the desired strength. There is a high possibility that the alkaline component in the glass will be eluted into the water-based ink composition, and the eluted alkaline component may react with the components of the water-based ink composition to form a precipitate. Therefore, in the water-based ink composition used in the present invention, the alkaline component eluted from the glass ink container is captured, and the alkaline component reacts with the components in the water-based ink composition to form a water-insoluble precipitate. It is preferable that the ink contains the chelating agent, which can prevent the occurrence of such a phenomenon and prevent the ink flow path from being clogged by the generated deposits, etc., resulting in blurry handwriting and impossibility of writing.
Ethylenediaminetetraacetic acid (EDTA) is preferred among the chelating agents because it can sufficiently supplement the alkaline component and does not easily change the physical properties and performance of the water-based ink composition before and after the chelating agent is blended. is preferred.

The viscosity of the water-based ink composition for writing instruments used in the present invention is preferably 1.0 to 5.0 mPa·s as measured at 60 rpm and 20° C. using a B-type rotational viscometer. . If the thickness is larger than this range, when the pen core is used as an ink flow regulator in a writing instrument, the ink may not be stably supplied to the writing tip, resulting in blurred handwriting or impossibility of writing. It is more preferably 1.0 to 3.0 mPa·s, still more preferably 1.0 to 2.0 mPa·s. If the ink viscosity is within the above range, ink is stably supplied to the writing tip when used in a writing instrument in which the pen core is arranged as an ink flow rate adjusting body, and ink follow-up is achieved, such as obtaining good handwriting. This is because the performance can be improved.

The ink viscosity in the present invention can be measured according to JIS Z 8803:2011 using a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd.).

The surface tension at 20° C. of the water-based ink composition according to the present invention is preferably 30-70 mN/m, more preferably 35-60 mN/m. If the surface tension of the water-based ink composition is within the above numerical range, it is possible to maintain adequate wettability with respect to the pen core when used in a writing instrument in which the pen core is disposed as an ink flow rate regulator. Therefore, even when the internal pressure of the ink reservoir rises, the spilled ink can smoothly enter the pen core, and it is possible to effectively suppress ink dripping from the writing tip. Furthermore, since the wettability to the writing surface is properly maintained, it is possible to prevent the obtained handwriting from blurring and the handwriting from being smudged by rubbing due to slow drying of the handwriting. The surface tension is determined by measuring with a surface tension measuring instrument (model: DY-200, manufactured by Kyowa Interface Science Co., Ltd., under an environment of 20° C., platinum plate, vertical plate method).

<Method for producing ink composition>
The aqueous ink composition for writing instruments according to the present invention can be produced by any conventionally known method. Specifically, the necessary amount of each component described above is blended and mixed with various stirrers such as a propeller stirrer, homodisper, homomixer, and planetary stirrer, and various dispersers such as a bead mill.

<Writing implements>
The water-based ink composition of the present invention can be used in writing instruments such as marking pens and ballpoint pens with a pen tip such as a fiber tip, felt tip, plastic tip or ballpoint tip, and fountain pens with a metal tip.

The writing instrument of the present invention may be of a construction in which the water-based ink composition is directly filled, or may be provided with an ink reservoir or ink-absorbing body capable of being filled with the water-based ink composition.

The retracting mechanism of the writing instrument of the present invention is not particularly limited, and includes a cap type provided with a cap covering the pen tip, a knock type, a rotating type, a sliding type, and the like. Moreover, it may be of a retractable type in which the pen tip can be accommodated in the barrel.

In addition, the ink supply mechanism of the writing instrument is not particularly limited. For example, (1) a mechanism that includes an ink guide core made of a fiber bundle or the like as an ink flow rate control member and supplies a water-based ink composition to the pen tip; (2) A mechanism having a groove-shaped ink flow control member interposed therebetween to supply the water-based ink composition to the pen tip; and (4) a mechanism for directly supplying the water-based ink composition to the pen tip from an ink container or barrel provided with the pen tip.

The writing instrument used in the present invention has a writing tip and an ink reservoir, and ink can be supplied from the ink reservoir to the writing tip between the writing tip and the ink reservoir, and overflows as the internal pressure of the ink reservoir rises. It is preferable to use a writing instrument having an ink flow control body having a comb tooth-like ink reservoir for temporarily holding ink. The ink flow rate regulator having the comb tooth-shaped ink reservoir supplies the water-based ink composition from the ink reservoir to the writing tip, and temporarily removes the water-based ink composition overflowing as the internal pressure of the ink reservoir rises. It is possible to hold Specific examples of the writing instruments include fountain pens, ballpoint pens, calligraphy pens, and the like.

In other embodiments, the writing instrument is a marking pen, and the pen tip is not particularly limited, and may be, for example, a fiber tip, a felt tip, or a plastic tip. Alternatively, it may be of a brush pen type or the like.

In other embodiments, the writing instrument is a ballpoint pen, preferably a ballpoint pen with an ink backflow preventer.

A water-based ink composition for writing instruments was obtained by the following composition and method.
(Example 1)
Self-dispersing carbon black 1 17.5% by mass
(Product name: Fuji Jet Black-20 manufactured by Fuji Pigment Co., Ltd., ionicity: anionic carbon black 20% aqueous dispersion)
Sodium orthophenylphenol 0.5% by mass (equivalent to 5,000 ppm)
Diethylene glycol (water-soluble organic solvent) 3.0% by mass
Triethanolamine (pH adjuster) 1.0% by mass
Ion-exchanged water Remainder An antibacterial substance, a water-soluble organic solvent, and a pH adjuster were added to ion-exchanged water, and the mixture was stirred with a propeller to obtain a base liquid. Then, self-dispersing carbon black was added to the base liquid and mixed by propeller stirring to obtain a water-based ink composition for writing instruments. The viscosity of the obtained water-based ink composition was measured according to JIS Z 8803:2011 with a B-type rotational viscometer (model: BLII, rotor: BL adapter, manufactured by Toki Sangyo Co., Ltd., sample volume: 20 ml). Specifically, the ink viscosity at 20° C. and a rotation speed of 60 rpm was 1.65 mPa·s. In addition, the surface tension of the resulting water-based ink composition was measured with a surface tension measuring instrument (model: DY-200, manufactured by Kyowa Interface Science Co., Ltd., under an environment of 20° C., platinum plate, vertical plate method). 0 mN/m.

(Examples 2-7, Comparative Examples 1-3)
Water-based ink compositions for writing instruments of Examples 2 to 7 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1, except that the composition shown in (Table 1) was used for Example 1. .

(Antibacterial performance test)
Aspergillus sp. (BIT-resistant bacteria) was inoculated to about 1×10 ⁶ per 1 ml. Using this as a test ink, the test ink immediately after inoculation was cultured at 28° C. for 7 days by the smear plate method on a potato dextrose agar medium, and the antibacterial performance was evaluated from the number of remaining bacteria.
◯: The number of remaining bacteria is less than 1×10 ¹ cfu/ml.
Δ: The number of remaining bacteria is 1×10 ¹ cfu/ml or more and less than 1×10 ³ cfu/ml.
×: The number of remaining bacteria is 1×10 ³ cfu/ml or more and less than 1×10 ⁶ cfu/ml.
XX: The number of remaining bacteria is 1×10 ⁶ cfu/ml or more.

自己分散型カーボンブラック１：商品名：Ｆｕｊｉ Ｊｅｔ Ｂｌａｃｋ－２０ 冨士色素株式会社製、イオン性：アニオン カーボンブラック２０％水分散体
カーボンブラックＩ：商品名：Ｆｕｊｉ ＳＰ Ｂｌａｃｋ ８９８０ 冨士色素株式会社製、アクリル樹脂分散 カーボンブラック１５％水分散体

Self-dispersion type carbon black 1: Product name: Fuji Jet Black-20 manufactured by Fuji Pigment Co., Ltd., ionicity: anionic carbon black 20% water dispersion carbon black I: Product name: Fuji SP Black 8980 manufactured by Fuji Pigment Co., Ltd., acrylic Resin dispersion Carbon black 15% water dispersion

(Dispersion stability test)
A 30 ml screw tube was filled with the water-based ink compositions for writing instruments of Examples 1 to 7 and Comparative Examples 1 to 3, left at room temperature for 4 weeks, and the ink compositions at the top and bottom of the screw tube were observed under a microscope. bottom.
◯: The pigment is uniformly dispersed in both the top and the bottom, and the dispersion stability is good.
Δ: Aggregation of the pigment was slightly observed, and the amount of pigment on the top was smaller than that on the bottom.
x: Pigment agglomeration was observed, and the amount of pigment on the top was smaller than that on the bottom, and uniform dispersion was not obtained.

(Antifoaming test)
The water-based ink compositions for writing instruments of Examples 1 to 7 and Comparative Examples 1 to 3 were filled in a 100 ml screw tube and shaken, and foaming after 1 minute was visually observed.
◯: Air bubbles have completely disappeared, and the state before shaking has been restored.
Δ: Small air bubbles are observed.
x: Large air bubbles are observed, and almost no air bubbles have disappeared.

(Writing performance test)
The water-based ink compositions for writing instruments of Examples 1 to 7 and Comparative Examples 1 to 3 were injected into a polyethylene ink cartridge, mounted on a fountain pen manufactured by Pilot Corporation (Custom 74: pen type M), and written on writing paper A. did the writing. The handwriting at that time was visually observed.
◯: Good handwriting is obtained without faint handwriting.
Δ: The handwriting is blurred.
x: Writing was impossible because the precipitate clogged the ink flow path and the ink did not come out.

In comparison with Comparative Example 1, Examples 1 to 7 were superior in antibacterial performance and defoaming performance. Compared with Examples 1 to 7, the ink composition of Comparative Example 2 was inferior in dispersion stability and defoaming performance. The ink composition of Comparative Example 3 was inferior in dispersion stability. As described above, the ink compositions for writing instruments of Examples 1 to 7 were excellent.

The water-based ink composition for writing instruments of the present invention can be used for various writing instruments such as fountain pens, ballpoint pens, calligraphy pens, calligraphy pens, and various markers. It can be suitably used as a composition.

Claims (7)

A water-based ink composition for writing instruments comprising water, a coloring agent, and an antibacterial substance,
The coloring agent is self-dispersing carbon black,
the antimicrobial substance comprises orthophenylphenol or a salt thereof and at least one of 1,2-benzisothiazolin-3-one and 2-n-octyl-4-isothiazolin-3-one;
The mass ratio of the orthophenylphenol or its salt and at least one of the 1,2-benzisothiazolin-3-one and the 2-n-octyl-4-isothiazolin-3-one is 1:1 to 1:1: 0.01, water-based ink composition for writing instruments. 2. The water-based ink composition for writing instruments according to claim 1, wherein the amount of said ortho-phenylphenol or its salt added is 100 to 10,000 ppm. The amount of at least one of the 1,2-benzisothiazolin-3-one and the 2-n-octyl-4-isothiazolin-3-one added is 10 to 1,000 ppm, or The water-based ink composition for writing instruments according to claim 2. 3. The ink composition has a viscosity of 1.0 to 5.0 mPa·s when measured using a B-type rotational viscometer at a rotational speed of 60 rpm and 20° C. The water-based ink composition for writing instruments according to any one of the above. The water-based ink composition for writing instruments has a writing tip and an ink reservoir, and ink can be supplied from the ink reservoir to the writing tip between the writing tip and the ink reservoir as the internal pressure of the ink reservoir rises. 1. A water-based ink composition for writing utensils, which is incorporated in an ink reservoir of a writing utensil in which an ink flow rate regulator having a comb tooth-shaped ink reservoir for temporarily holding overflowed ink is arranged. 5. The water-based ink composition for writing instruments according to any one of 1 to 4 . A writing instrument filled with the water-based ink composition for writing instruments according to any one of claims 1 to 5 . A water-based ink product comprising the water-based ink composition for writing instruments according to any one of claims 1 to 5 stored in an ink storage container, wherein the ink storage container separates the water-based ink composition for writing instruments. The water-based ink composition for a writing instrument dispensed from the ink storage container has a writing tip and an ink reservoir, and the ink is stored between the writing tip and the ink reservoir. Filling the ink reservoir of a writing utensil having a comb tooth-shaped ink reservoir that can supply ink from the reservoir to the writing tip and temporarily retain ink overflowing due to an increase in the internal pressure of the ink reservoir. A water-based ink product characterized by being used as a