JP7721701B2 - Cleaning fluid for writing instruments and cleaning fluid package containing the same - Google Patents

Description

The present invention relates to a writing instrument cleaning fluid and a writing instrument cleaning fluid package containing it. More specifically, it relates to a writing instrument cleaning fluid for cleaning writing instrument components such as the comb grooves, nibs, and converters (ink reservoirs (fountain pen ink injectors) that have the function of directly drawing ink from an ink reservoir such as an ink bottle into the ink reservoir of a writing instrument) of writing instruments equipped with comb grooves as an ink flow rate adjustment mechanism, and to a writing instrument cleaning fluid package containing it.

Writing instruments such as fountain pens and drafting pens that are connected to ink cartridges or converters (ink reservoirs (fountain pen ink inhalers) that have the function of directly drawing ink from an ink container such as an ink bottle into the ink reservoir) have been well known.
When such fountain pens or drafting pens run out of ink, they can be replaced with a new ink cartridge filled with ink or ink can be drawn into the converter from the nib, allowing them to be used repeatedly without having to discard the writing instrument itself.

If such writing instruments are left unused for a long period of time, the water content in the ink gradually evaporates, causing ink components such as dyes and pigments to harden on the writing instrument's grooves, nib, converter, and other parts.If the ink dries up, this can result in poor writing performance or malfunction of the converter.
Therefore, before a writing instrument is to be used again after a long period of non-use or after a long period of storage, the writing instrument components such as the nib, tip, and converter are washed with water or lukewarm water.
Furthermore, for example, when red ink is newly used in place of black ink in a writing instrument, the black ink and the red ink may mix inside the writing instrument components, resulting in mixed-color handwriting, or the mixing of different types of ink may cause aggregation or deposition. To prevent this, the remaining black ink in the writing instrument components, such as the writing instrument's comb grooves, nib, and converter (ink injector for fountain pens), is washed away with water or lukewarm water.

In ink compositions for writing instruments that contain colorants, resins, etc., in order to obtain excellent handwriting that is excellent in water resistance and light resistance and exhibits good color development, the ink contains a resin component, and therefore, once the ink dries, it is extremely difficult to remove the dried ink by simply immersing the grooves, nib, or converter of the writing instrument in water or lukewarm water. Therefore, there are cleaning methods (e.g., Patent Documents 1 and 2) in which ultrasonic waves are applied while the writing instrument is immersed, but this requires a large-scale cleaning device, and there is a problem that, particularly when cleaning a writing instrument that uses an ink composition that uses a pigment as a colorant (pigment ink), once the ink dries, it tends to dry out and harden on the writing instrument components such as the nib and converter.
In particular, with fountain pens, when ink runs out during writing, ink is sucked from the nib into a converter (a fountain pen ink injector), allowing the writing instrument body to be reused without being discarded, and the same writing instrument components, such as the comb groove, nib, converter, etc., can be used over a long period of time. Therefore, when ink is sucked into the writing instrument, scratches such as mounting scratches and sliding scratches can appear on the writing instrument components, and if ink seeps into these scratches and dries up, it becomes extremely difficult to remove the dried ink.

Japanese Utility Model Application Publication No. 56-76092 Japanese Patent Application Publication No. 2001-96974

The object of the present invention is to solve the above-mentioned problems of the prior art by providing a writing instrument cleaning liquid (hereinafter sometimes simply referred to as "cleaning liquid") for cleaning writing instrument components such as comb grooves, nibs, and converters, which can efficiently clean writing instrument components such as comb grooves, nibs, and converters (ink reservoirs (fountain pen ink injectors) that have the function of directly drawing ink from an ink reservoir such as an ink bottle into the ink reservoir of the writing instrument) of writing instruments that have comb grooves arranged as an ink flow rate adjustment mechanism, and which also provides good re-writing properties after cleaning, as well as a writing instrument cleaning liquid package that contains the same.

The present invention provides
"1. A cleaning liquid for a writing instrument comprising water, a pH adjuster, and a nonionic surfactant, wherein the HLB value of the nonionic surfactant is 15 or less.
2. The writing instrument cleaning liquid according to item 1, characterized in that the surface tension of the writing instrument cleaning liquid at 20°C is 20 to 50 mN/m.
3. The writing instrument cleaning liquid according to item 1 or 2, wherein the nonionic surfactant has a polyoxyalkylene group.
4. The writing instrument cleaning liquid according to any one of items 1 to 3, wherein the alkyl group of the nonionic surfactant has 1 to 20 carbon atoms.
5. The writing instrument cleaning liquid according to any one of items 1 to 4, wherein the pH adjuster is a water-soluble amine compound.
6. A writing instrument cleaning liquid package, characterized in that the writing instrument cleaning liquid according to any one of items 1 to 5 is contained in the package.

This invention provides a writing instrument cleaning fluid and a writing instrument cleaning fluid package containing it that can efficiently clean writing instrument components such as the grooves of a writing instrument that have grooves arranged as an ink flow rate adjustment mechanism, the nib, and a converter (an ink reservoir (fountain pen ink inhaler) that has the function of directly drawing ink from an ink reservoir such as an ink bottle into the ink reservoir of the writing instrument), and that also provides good re-writing properties after cleaning.

Hereinafter, embodiments of the present invention will be described in detail.
In this specification, "parts,""%,""ratio," and the like indicating the composition are based on mass unless otherwise specified.

<Cleaning liquid for writing instruments>
A feature of the present invention is that it is a cleaning liquid for a writing instrument comprising water, a pH adjuster, a surfactant, and a chelating agent, wherein the HLB value of the surfactant is 15 or less.
By using the above-mentioned writing instrument cleaning liquid, it is possible to obtain a writing instrument cleaning liquid that has excellent cleaning properties for ink that has dried and hardened inside the fine grooves, precision nibs, and converters (ink reservoirs (ink inhalers for fountain pens) that have the function of directly sucking ink from an ink container such as an ink bottle into the ink reservoir of the writing instrument) of writing instruments that have grooves arranged as an ink flow rate adjustment mechanism, and that also has good re-writing properties after cleaning.
In particular, with fountain pens, when the ink runs out due to writing, ink is drawn from the nib into the converter, allowing the writing instrument body to be used repeatedly without being discarded, and therefore the writing instrument components, such as the comb groove, nib, converter, etc., can be used for a long period of time without replacement. Therefore, when drawing ink or during daily use, scratches such as mounting scratches and sliding scratches can appear on these components, and if ink gets into these scratches and dries up, it becomes extremely difficult to remove the dried up ink. However, even in such cases, it is possible to achieve excellent cleanability.

<Surfactant>
The writing instrument cleaning solution of the present invention comprises a surfactant with an HLB value of 15 or less. This is because surfactants with an HLB value of 15 or less can clean the grooves, nib, and converter (ink injector for fountain pens) of a writing instrument even when the ink has dried up due to hardening of ink components, and because surfactants with an HLB value of 15 or less are stable in the writing instrument cleaning solution, they provide a long-term cleaning effect. Furthermore, even after cleaning writing instrument components such as the grooves, nib, and converter (ink injector for fountain pens), there are no problems with writing performance and re-writing is also good. The reason for this is not clear, but it is speculated as follows.
It is believed that the surfactant with an HLB value of 15 or less acts to lower the surface tension of the writing instrument cleaning liquid, improving its wettability to the comb grooves, nib, and converter of the writing instrument, and that the colorants and resins contained in the dried ink are efficiently dispersed in the cleaning liquid by the surfactant after dissolving in the cleaning liquid, and that the colorants and resins dispersed in the cleaning liquid are prevented from re-adhering to the comb grooves, nib, and converter, thereby providing high cleaning performance. Furthermore, it is believed that the cleaning liquid does not continue to adhere to the writing instrument components after cleaning and affect writing performance, resulting in good re-writability.
In particular, in the case of fountain pens equipped with a neck shaft equipped with a nib and comb grooves, and a converter (an ink reservoir (fountain pen ink inhaler) that has the function of directly drawing ink from an ink reservoir into the ink reservoir of the writing instrument), the comb grooves have a fine and complex structure, so once the ink has dried, ink stains are difficult to remove even with cleaning, and therefore the use of the writing instrument cleaning liquid of the present invention is effective and preferable.

Among surfactants with an HLB value of 15 or less, taking into consideration solubility in water and cleanability, surfactants with an HLB value of 4 to 15 are preferred, and even more preferably an HLB value of 6 to 15. Furthermore, taking into consideration the possibility of scratches on writing implement components such as the comb grooves, pen tip, and converter, surfactants with an HLB value of 8 to 14, which have excellent cleanability, are preferred, and even more preferably an HLB value of 11 to 14.
The HLB value is calculated by the Griffin method using the following formula:
HLB value = 20 × (mass % of hydrophilic groups) = 20 × (sum of formula weights of hydrophilic groups/molecular weight of surfactant)

Methods for cleaning writing instruments using writing instrument cleaning fluid include removing the cap, barrel, converter, etc. from the writing instrument to leave the nib (neck) and nib, and then immersing the nib (neck) and converter in the cleaning fluid; using a dropper or similar to pour the cleaning fluid into the nib (neck) and converter; or using a converter used as an ink reservoir to suck the cleaning fluid into the nib as if refilling ink.

Examples of surfactants include polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyethylene polyoxypropylene glycols, sucrose fatty acid esters, sorbitan fatty acid esters, alkyl glycosides, alkyl glyceryl glycosides, and methyl glucoside fatty acid esters. Among these, nonionic surfactants having a polyoxyalkylene group such as polyoxyethylene are preferred. This is because they have high affinity with colorants and resins, making them more effective at removing colorants and resins from comb grooves, pen nibs, and converters. Furthermore, the polyoxyalkylene group provides good solubility in water, stability in aqueous inks, and a long-term, stable cleaning effect. Among these surfactants, it is preferred to use one or more of polyoxyalkylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters, and polyethylene glycol fatty acid esters, with polyoxyalkylene alkyl ethers being more preferred. This is because it has excellent penetration and low foaming power, so it can penetrate and clean even scratches on writing instrument components such as comb grooves, nibs, and converters, as well as comb grooves with thin and complex structures, precise nibs, and converters, and is therefore effective in cleaning even difficult-to-remove stains.
In particular, in the case of fountain pens equipped with a neck shaft equipped with a nib and comb grooves, and a converter (an ink reservoir (ink inhaler for fountain pens) that has the function of directly drawing ink from an ink reservoir into the ink reservoir of the writing instrument), once the ink has dried, ink stains are difficult to remove even with cleaning, so the use of polyoxyalkylene alkyl ethers is effective and preferable.

For the nonionic surfactant having a polyoxyalkylene group, the alkyl group of the nonionic surfactant having a polyoxyalkylene group preferably has 1 to 20 carbon atoms. This is because this range provides an alkyl group length suitable for easily penetrating scratches on writing implement components and fine, complex structures, and is likely to provide a high cleaning effect. On the other hand, if the alkyl group has too many carbon atoms and is too long, it will be difficult to dissolve in water, which will likely affect the cleaning effect. Also, if the alkyl group has too few carbon atoms and is too short, it will be difficult to achieve a sufficient cleaning effect. Therefore, the alkyl group preferably has 4 to 16 carbon atoms, and more particularly, the alkyl group preferably has 8 to 14 carbon atoms.

The alkyl group of the nonionic surfactant having the polyoxyalkylene group may have a straight-chain structure or a branched structure, but an alkyl group having a branched structure is preferred because it has a bulky structure and can penetrate and effectively clean even when there are scratches on the writing instrument component, or even when there are thin, complexly structured comb grooves, precision pen tips, and converters, thereby making it easier to remove difficult-to-remove stains.
Specific examples of the nonionic surfactant having a polyoxyalkylene group, polyoxyalkylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester include polyoxyalkylene isodecyl ether (alkyl group: branched structure), polyoxyalkylene isotridecyl ether (alkyl group: branched structure), polyoxyalkylene tridecyl ether (alkyl group: linear structure), polyoxyalkylene decyl ether (alkyl group: linear structure), polyoxyalkylene lauryl ether (alkyl group: linear structure), polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trilaureate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate. However, considering that reducing the dynamic surface tension and providing excellent penetration make it easier to improve cleaning power, it is preferable to use polyoxyalkylene isodecyl ether.

The polyoxyalkylene group of the polyoxyalkylene alkyl ether preferably contains an ethylene oxide group or a propylene oxide group. This is because it has good solubility in water, is stable in aqueous inks, and is more likely to provide cleaning effects. From a more specific perspective, it is preferable for it to contain at least an ethylene oxide group. Furthermore, the polyoxyalkylene group preferably has an average added mole number of alkylene oxide of 1 to 20. This is because, within this range, the alkylene oxide has a length that allows it to easily penetrate scratches on writing implement components, making it more likely to provide a high cleaning effect. On the other hand, if the average added mole number of alkylene oxide is too high or too long, it becomes less soluble in water and is more likely to affect cleaning effects. If the average added mole number of alkylene oxide is too low or too short, it is less likely to provide a cleaning effect. Therefore, the average added mole number of alkylene oxide is preferably 3 to 15, and more preferably 5 to 10.

The cloud point of the polyoxyalkylene alkyl ether is preferably 90°C or lower, taking into consideration cleaning effectiveness, and more preferably 30 to 80°C, and even more preferably 40 to 80°C.

The content of the surfactant in the writing instrument cleaning liquid of the present invention is preferably 0.01 to 10% by mass, preferably 0.5 to 8% by mass, and more preferably 1 to 5% by mass, based on the total mass of the writing instrument cleaning liquid. This is because if the content is less than this range, it is difficult to fully exert the cleaning effect, and if it is more than this range, the solubility in water is likely to be poor and it is difficult to see any improvement in the effect, so it is not necessary to include more than this amount.

Regarding the nonionic surfactants, specific examples of polyoxyalkylene alkyl ethers include the Noigen LF series (polyoxyalkylene isodecyl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Noigen SD series (polyoxyethylene isodecyl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Noigen TDX series (polyoxyalkylene isotridecyl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Noigen XL series (polyoxyalkylene isodecyl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Noigen TDS series (polyoxyethylene tridecyl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Noigen LP series (polyoxyethylene lauryl ether, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Sorgen series (sorbitan fatty acid ester, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), the Sorgen TW series (polyoxyethylene sorbitan fatty acid ester, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the Rheodol series (sorbitan fatty acid ester/polyoxyethylene sorbitan fatty acid ester, manufactured by Kao (manufactured by Kao Corporation), and the Emanone series (polyethylene glycol fatty acid esters, manufactured by Kao Corporation).

<pH adjuster>
The writing instrument cleaning liquid of the present invention contains a pH adjuster.
Examples of pH adjusters include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate, and sodium hydroxide, which are basic components, basic organic compounds such as sodium acetate, triethanolamine, and diethanolamine, and acidic components such as lactic acid and citric acid. In the present invention, it is preferable to use a basic component in consideration of compatibility with the surfactant having an HLB value of 15 or less. These pH adjusters may be used alone or in combination of two or more.

Among basic components, water-soluble amine compounds such as monoethanolamine, diethanolamine, and triethanolamine are preferred because they have good affinity with the surfactants and result in writing instrument cleaning solutions with excellent long-term storage stability. From a more specific perspective, alkanolamines are preferred, and among these, triethanolamine, which is weakly basic, is even more preferred.

The content of the pH adjuster in the writing instrument cleaning liquid of the present invention is preferably 0.01 to 50% by mass, more preferably 0.1 to 15% by mass, and even more preferably 0.1 to 5% by mass, based on the total mass of the writing instrument cleaning liquid. Taking into consideration both the cleaning properties of the comb grooves, nibs, and converters of the writing instrument and the increase in pH of the writing instrument cleaning liquid, the content is preferably 0.5 to 5% by mass.
If the content of the pH adjuster is too small, the intended effect of the present invention may not be fully exhibited, and conversely, if the content is too large, safety concerns may arise due to the pH of the cleaning solution.

The writing instrument cleaning liquid of the present invention is used to clean dried ink from the thin, complexly structured grooves of a writing instrument component in which grooves are arranged as an ink flow rate adjusting mechanism, the inside of a precise nib, a converter (ink injector for fountain pens), etc., so that the surface tension of the writing instrument cleaning liquid in an environment of 20°C is preferably 50 mN/m or less, more preferably 40 mN/m or less, and even more preferably 35 mN/m or less. Furthermore, a surface tension of 20 mN/m or more is preferable, since even if cleaning liquid remains in the grooves, nib, or converter of the writing instrument, it is less likely to affect newly added ink to the writing instrument, and 23 mN/m or more is more preferable.
The surface tension can be determined by measuring in an environment of 20° C. using a surface tension measuring instrument manufactured by Kyowa Interface Science Co., Ltd., by the vertical plate method using a platinum plate.
In particular, in the case of fountain pens equipped with a neck shaft equipped with a nib and comb grooves, and a converter (an ink reservoir (fountain pen ink inhaler) that has the function of directly drawing ink from an ink reservoir into the ink reservoir of the writing instrument), the comb grooves have a fine and complex structure, so once the ink has dried, ink stains are difficult to remove even with cleaning, and therefore the use of the writing instrument cleaning liquid of the present invention is effective and preferable.

Furthermore, the writing instrument cleaning liquid according to the present invention has excellent penetration properties, and therefore penetrates into even scratches on writing instrument components such as the grooves, nib, and converter, or even thin grooves and precise nibs, providing excellent cleaning properties. Therefore, the viscosity of the writing instrument cleaning liquid, measured at 20°C and a shear rate of 380 sec ^-1 (rotation speed 100 rpm) using a Brookfield DV-II viscometer (CPE-42 rotor), is preferably 12 mPa·s or less, and, taking into consideration further improved penetration properties and cleaning properties, it is preferably 6 mPa·s or less, and from further consideration, more preferably 3 mPa·s or less.

The writing instrument cleaning liquid containing the surfactant of the present invention having an HLB value of 15 or less preferably has a pH of 10 or less in an environment of 20°C. This is because, when the writing instrument cleaning liquid exceeds pH 10 and becomes more alkaline, it is easier to suppress precipitation and discoloration of colorants such as dyes contained in ink, and it is also safe even if the cleaning liquid comes into contact with the user's hands or clothes during cleaning.
Furthermore, in consideration of cleaning properties and stability, the pH of the writing instrument cleaning liquid in an environment of 20° C. is preferably pH 7 to 10, more preferably pH 8 to 10.
The pH of the writing instrument cleaning liquid may be measured by measuring the pH of a highly concentrated stock solution, which will be described later, or by measuring the pH of the cleaning liquid when the stock solution is diluted with water or the like.
In particular, it is advisable to measure the pH when cleaning the grooves and nib of the writing implement.
In the present invention, the pH value is measured in an environment of 20° C. using a commercially available pH meter (for example, IM-40S pH meter manufactured by DKK-TOA Corporation).

The writing instrument cleaning liquid of the present invention may be sold at a concentration suitable for cleaning writing instruments, or may be sold as a concentrated solution that becomes suitable for cleaning writing instruments when diluted with water, and it is preferable that the pH when cleaning writing instrument components is 10 or less in a 20°C environment.
Selling the product in a highly concentrated form has the advantage of being able to store it in a small container, reducing transportation costs, and reducing waste after use.
The writing instrument cleaning liquid of the present invention has a pH of 10 or less in a 20°C environment even at high concentrations, so it is highly safe even if the high concentration liquid comes into contact with the user's hands or clothing.

The writing instrument cleaning liquid of the present invention is preferably contained in a package such as a film or sheet to form a writing instrument cleaning liquid package, but from the standpoint of portability and convenience, it is preferable to individually package the amount used for one time in a film or sheet package, and further, in consideration of improving long-term storage stability such as moisture evaporation, it is preferable to package in a metal film, and particularly preferable to package in an aluminum compound film. Furthermore, with regard to the content of the cleaning liquid contained in the package, in consideration of cleaning ability and portability, it is preferable to have a writing instrument cleaning liquid package containing 3 to 15 ml in the package, and from further consideration, it is preferable to have a writing instrument cleaning liquid package containing 5 to 10 ml in the package.
Furthermore, when two or more writing instrument cleaning liquid packages are sold, they are preferably sold in a state in which they can be separated along a seam or perforation, and 3 to 12 writing instrument cleaning liquid packages may be sold as a set.Furthermore, it is preferable to sell a writing instrument set in which the writing instrument cleaning liquid package and the writing instrument are combined.
Furthermore, the writing instrument cleaning liquid package is preferably sold as a writing instrument set together with a writing instrument such as a fountain pen, ballpoint pen, marking pen (sign pen), brush pen, calligraphy pen, or drafting pen, and is preferably sold as a writing instrument cleaning liquid set together with an inhaler such as a dropper for collecting the writing instrument cleaning liquid.

After removing dried ink from the grooves and nib using the above-mentioned method for cleaning a writing instrument, the cleaning solution is generally washed away with water, i.e., "rinsing." However, if rinsing is insufficient, cleaning solution will remain in the grooves and nib of the writing instrument. If a converter filled with new ink is attached to the grooves and nib (neck) of the writing instrument in this state and the new ink is drawn into the converter from the nib, the cleaning solution remaining in the grooves, nib, and converter of the writing instrument may become mixed into the new ink.
At this time, if rinsing is insufficient and cleaning liquid remains in the grooves, nib, or converter of the writing instrument, it may mix with the newly drawn ink and have adverse effects, so in order to reduce the likelihood of such effects, the writing instrument cleaning liquid preferably has a pH of 10 or less in an environment of 20°C and a surface tension of 20 to 50 mN/m. More preferably, the writing instrument cleaning liquid preferably has a pH of 7 to 10 in an environment of 20°C and a surface tension of 23 to 40 mN/m.

In particular, when cleaning a writing instrument that uses an ink composition (pigment ink) that uses a pigment as a colorant, the nonionic surfactant is preferred because it has a high affinity for the pigment and pigment dispersant contained in the pigment ink.
Pigment dispersants for pigment inks include acidic resins, basic resins, nonionic surfactants, and anionic surfactants. Nonionic surfactants with an HLB value of 15 or less are preferred because they are particularly effective in cleaning writing instruments that use inks that employ acidic resins such as acrylic resins, styrene-acrylic resins, styrene-maleic acid resins, and phenolic resins, and are even more effective in cleaning writing instruments that use inks that employ acrylic resins and styrene-acrylic resins.
Therefore, the writing instrument cleaning liquid of the present invention, which uses the nonionic surfactant, is preferably used as a cleaning liquid for writing instruments that use pigment inks.

When using an ink composition (pigment ink) that uses a pigment, once the ink dries and hardens on the comb grooves, nib, and converter, it is generally difficult to remove stains even with washing, making the use of the writing instrument cleaner of the present invention effective. Pigments used in ink compositions (pigment inks) include inorganic, organic, and processed pigments, but organic pigments are particularly difficult to remove stains with washing, making the use of the cleaner of the present invention effective. Furthermore, when considered in particular, phthalocyanine-based organic pigments are the most effective, and ink compositions using phthalocyanine green and phthalocyanine blue are preferred. Examples of phthalocyanine greens include Pigment Green 7, 36, and 58, and examples of phthalocyanine blues include Pigment Blue 16, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 75, and 79, with Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, and 15:6 being particularly effective.

<Water>
The writing instrument cleaning liquid of the present invention contains water.
The water is not particularly limited, and for example, ion-exchanged water, ultrafiltered water, distilled water, etc. can be used.

In addition, the writing instrument cleaning liquid of the present invention preferably contains various additives such as preservatives, rust inhibitors, and chelating agents in order to improve the properties and functions of the cleaning liquid.

Examples of preservatives (antibacterial agents) include phenol, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl parahydroxybenzoate, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, sodium 2-pyridinethiol-1-oxide, 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, etc. These preservatives may be used alone or in combination of two or more.
Among these antiseptics (antibacterial agents), it is preferable to use an isothiazolin-based compound in consideration of the antiseptic (antibacterial) effect, and more particularly, it is preferable to select from 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and 2-n-octyl-4-isothiazolin-3-one. Furthermore, as in the present invention, it is preferable to use 1,2-benzisothiazolin-3-one in consideration of the influence of compatibility with other components such as the nonionic surfactant on the stability of the cleaning solution (change over time, change over time with heating, change in color).

Examples of rust inhibitors include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, and dialkylthiourea. Considering the rust-preventing effect and compatibility with the nonionic surfactant used in the present invention, benzotriazole is preferred among the rust inhibitors. These rust inhibitors may be used alone or as a mixture of two or more.

Furthermore, the writing instrument cleaning liquid according to the present invention preferably contains a chelating agent to suppress precipitation of ionic substances contained in water after rinsing (i.e., washing away) with water the ionic substances in the colorant of the ink composition contained in the writing instrument and the cleaning liquid adhering to the writing instrument components.

Examples of the chelating agent include aminocarboxylic acids such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), glycoletherdiaminetetraacetic acid (GEDTA), nitrilotriacetic acid (NTA), hydroxyethyliminodiacetic acid (HIDA), dihydroxyethylglycine (DHEG), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), and alkali metal salts, ammonium salts, or amine salts thereof.
Considering that the chelating agent tends not to significantly affect the physical properties of the writing instrument cleaning liquid before and after its addition, and also the compatibility with the nonionic surfactant used in the present invention, it is preferable to use aminocarboxylic acid or a salt thereof among the above chelating agents, and in particular, it is preferable to use ethylenediaminetetraacetic acid (EDTA) or a salt thereof.

The content of the chelating agent in the writing instrument cleaning solution of the present invention is preferably 0.01 to 1% by mass, based on the total mass of the ink composition. This is because if it is 1% by mass or less, it is unlikely to affect the performance and physical properties of the cleaning solution, and if it is 0.01% by mass or more, it is unlikely to suppress the formation of precipitates. A content of 0.01 to 0.5% by mass is more preferable.

The writing instrument cleaning liquid of the present invention may also contain a water-soluble organic solvent.
Examples of the water-soluble organic solvent include (i) glycols such as ethylene glycol, polyethylene glycol, and glycerin; (ii) alcohols such as methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, propargyl alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, ethylene glycol monomethyl ether acetate, and other higher alcohols; and (iii) glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 3-methoxybutanol, and 3-methoxy-3-methylbutanol.
These water-soluble organic solvents may be used alone or in combination of two or more.

Example 1
Nonionic surfactant 1.0% by mass
(Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Noigen XL-70, polyoxyalkylene branched decyl ether, HLB value 13.2)
Triethanolamine 3.0% by mass
Preservative 0.2% by mass
(1,2-benzisothiazolin-3-one)
Rust inhibitor 0.1% by mass
(benzotriazole)
Chelating agent 0.1% by mass
(aminocarboxylic acid)
Ion-exchanged water 95.7% by mass
A nonionic surfactant, triethanolamine, an antiseptic, a rust inhibitor, and a chelating agent were added to ion-exchanged water and mixed by propeller stirring to obtain a cleaning liquid for writing instruments.
The pH value of the resulting writing instrument cleaning liquid was measured using an IM-40S pH meter (manufactured by DKK-TOA Corporation, under an environment of 20° C.), and was found to be 9.2.
The surface tension of the resulting writing instrument cleaning liquid was measured using a surface tension meter (in a 20°C environment, platinum plate, vertical plate method, manufactured by Kyowa Interface Science Co., Ltd.) and found to be 27.2 mN/m.
The viscosity of the resulting writing instrument cleaning liquid was measured using a Brookfield DV-II viscometer (CPE-42 rotor) at 20°C and a shear rate of 380 sec ^-1 (100 rpm), and was found to be 1.1 mPa·s.

<Examples 2 to 29, Comparative Examples 1 to 5>
In Examples 2 to 29 and Comparative Examples 1 to 5, writing instrument cleaning liquids were obtained in the same manner as in Example 1, except that the types and amounts of components contained in the writing instrument cleaning liquid were changed to the compositions shown in the table.

The cleaning liquids for writing instruments obtained in Examples 1 to 29 and Comparative Examples 1 to 5 were evaluated as follows, and the results are shown in the table below.
A fountain pen (product name: Custom NS) manufactured by Pilot Corporation was fitted with a nib, comb grooves (neck barrel), and a push-type converter (an ink reservoir (ink inhaler for fountain pens) having the function of being able to directly inhale ink from an ink reservoir into the ink reservoir of the writing instrument) that uses a pressing member filled with 0.5 ml of the aqueous pigment ink composition for a writing instrument of Example 1, to prepare a test fountain pen. The fountain pen was then used and continued to write until the ink was used up.
After that, ink was sucked up from the ink bottle using a push-type converter and refilled with ink. After using this repeatedly 10 times, scratches such as attachment marks and sliding marks were formed on the pen tip and converter due to the repeated use of the same writing instrument component.
Water was sucked into the nib, comb groove (neck shaft), and converter, which had scratches and stains from ink, and cleaned them.
After that, the nib, comb groove (neck shaft), and converter were cleaned with writing instrument cleaning fluid.
The converter was removed from the nib and grooves (neck), and the nib, grooves (neck) and converter were left immersed in 100 ml of cleaning fluid for writing instruments in a 20°C environment for 24 hours.
Next, the pen tip, comb grooves, and converter were washed with ion-exchanged water, and the presence or absence of ink was visually evaluated.
Furthermore, a converter filled with 0.5 ml of an aqueous pigment ink composition for writing instruments was attached to the pen, and rewriting performance was evaluated.
The viscosities of the resulting writing instrument cleaning liquids were measured using a Brookfield DV-II viscometer (CPE-42 rotor) at 20°C and a shear rate of 380 sec ^-1 (100 rpm). The viscosities of the writing instrument cleaning liquids of Examples 6, 17, and 18 were 1.3 mPa·s, 5.5 mPa·s, and 10.7 mPa·s, respectively.

<Water-based pigment ink composition for writing instruments>
Pigment dispersion (acrylic resin dispersion) 18.0% by mass
(manufactured by Fuji Pigment Co., Ltd., containing Pigment Blue 15:3, 17% by mass aqueous dispersion)
Moisturizing agent 2.0% by mass
(glycerin)
pH adjuster 0.5% by mass
(triethanolamine)
Preservatives 0.2% by mass
(Manufactured by Lonza Japan Co., Ltd., product name: Proxel XL-2)
Ion-exchanged water 79.3% by mass
Ion-exchanged water, a humectant, a pH adjuster, and a preservative were added and mixed with a propeller to obtain a base liquid, and then the pigment dispersion was added to the base liquid and mixed with a propeller to obtain an aqueous pigment ink composition for a writing instrument.

<Converter (with scratches) cleaning>
⊚: Almost no ink stains were observed on the converter.
○: A small amount of ink staining was observed on the converter.
△: Ink stains were observed on the converter, but were at a level that did not cause any practical problems.
×: A lot of ink stains remained on the converter.

<Cleanability of pen tip (with scratches)>
⊚: Almost no ink stains were observed on the pen tip.
○: A small amount of ink staining was observed on the pen tip.
△: Ink staining was observed on the pen tip, but was at a level that did not cause any practical problems.
×: A lot of ink stains remained on the pen tip.

<Cleaning of comb grooves>
⊚: Almost no ink staining was observed in the comb grooves.
○: A small amount of ink staining was observed in the comb grooves.
△: Ink stains were observed in the comb grooves, but were at a level that did not cause any practical problems.
×: A lot of ink stains remained in the comb grooves.

<Rewriting performance>
⊚: Good handwriting.
◯: The handwriting was practically acceptable.
×: There was some smearing in the handwriting, which was problematic.

<Stability test of cleaning solution>
100 ml of the cleaning liquid for writing implements obtained in Examples 1 to 29 and Comparative Examples 1 to 5 was collected in a glass tube and left to stand at 50° C. for 2 weeks, after which the cleaning liquid was visually observed.
⊚: The stability of the cleaning solution was good.
⊚: The stability of the cleaning solution was slightly affected, but was at a level that would not pose a problem in practical use.
◯: The stability of the cleaning solution was affected, but to a level that was not problematic in practice.

As can be seen from the table, compared to the writing instrument cleaning solutions of Comparative Examples 1 to 5, the writing instrument cleaning solutions of Examples 1 to 29 have a high cleaning effect even when the pigment ink has dried up inside the converter, nib, and comb grooves, and even if there are scratches, they are highly effective in cleaning the converter and nib, and do not affect re-writability.
In addition, in Examples 2 to 4, the surfactant content was low at less than 1%, which resulted in slightly poor stability in the cleaning solution, and the cleaning solution was slightly cloudy when visually inspected, with Example 1 having a higher detergency. In Example 14, the surfactant had an HLB value of less than 10, which resulted in slightly poor solubility in the cleaning solution, and the cleaning solution was slightly cloudy when visually inspected, with Example 1 having a higher detergency.

On the other hand, the writing instrument cleaning solutions of Comparative Examples 1 to 5 did not contain a surfactant with an HLB value of 15 or less, so ink stains remained even after cleaning the converter (with scratches). Furthermore, in Comparative Examples 1, 2, and 4, ink stains remained in the comb grooves.
As is clear from the above results, it has become clear that the writing instrument cleaning liquid of the present invention is an excellent cleaning liquid.

In the examples, the fountain pen nib, comb grooves, and converter were used to clean the writing instrument parts using the cleaner, but other writing instrument parts may also be used, such as ballpoint pen nibs made of plastic or metal tips, ballpoint pen tip holders, ink cartridges, writing instrument barrels, writing instrument caps, and other writing instrument parts.
In addition, the converter may be a push-type converter that uses a pressing member to suck up ink, a slide-type converter that uses a sliding member to suck up ink, or a rotary converter that uses a rotating body to suck up ink, and is not particularly limited.

The writing instrument cleaning liquid of the present invention can be suitably used as a cleaning liquid for writing instruments equipped with comb grooves as an ink flow rate adjustment mechanism, such as fountain pens, ballpoint pens, marking pens (signtip pens), brush pens, calligraphy pens, and drafting pens.

Claims (6)

A cleaning liquid for a writing instrument comprising water, a pH adjuster, a nonionic surfactant, and a chelating agent, wherein the HLB value of the nonionic surfactant is 15 or less. The writing instrument cleaning liquid according to claim 1, characterized in that the chelating agent is an aminocarboxylic acid. The writing instrument cleaning liquid according to claim 1 or 2, characterized in that the content of the chelating agent is 0.01 to 1% by mass, based on the total mass of the ink composition. The writing instrument cleaning liquid according to any one of claims 1 to 3, characterized in that the surface tension of the writing instrument cleaning liquid at 20°C is 20 to 50 mN/m. The writing instrument cleaning liquid according to any one of claims 1 to 4, characterized in that the pH adjuster is a water-soluble amine compound. A writing instrument cleaning liquid package containing the writing instrument cleaning liquid according to any one of claims 1 to 5.