JP7545285B2 - Water-based ink composition for brush pens, and brush pens and ink cartridges for brush pens incorporating the same - Google Patents

Description

The present invention relates to a water-based ink composition for a brush pen, and a brush pen and an ink cartridge for a brush pen that incorporate the same.

In the past, research has been conducted into inks for writing instruments that can produce clear handwriting. In particular, water-based pigment inks that use pigments as coloring materials have been actively studied in recent years because they are highly safe and can provide handwriting that is water-resistant and light-resistant. (See, for example, Patent Document 1)

Patent Document 1 describes an aqueous recording liquid composition that contains carbon black and a specific water-soluble resin, and has a specified content ratio of carbon black to water-soluble resin and a specified surface tension. The composition produces good characters and images without bleeding, and is also applicable for writing.

However, the inks of the above-mentioned conventional technology do not have sufficient paper penetration, and when the ink is applied to a writing instrument, it is sometimes difficult to form handwriting that has excellent drying properties. In particular, in the case of a brush pen, a large amount of ink is applied to the paper surface, making it even more difficult to achieve good drying properties of the handwriting. In addition, when the ink is ejected onto the paper surface, some of the carbon black in the ejected ink penetrates into the paper without remaining on the paper surface, making it difficult for the ink to produce good color development of the handwriting.

Japanese Patent Application Publication No. 11-5935

The present invention aims to provide a water-based ink composition for a brush pen that is capable of producing deep, vivid, black handwriting with reduced bleeding while ensuring good drying of the handwriting, and a brush pen and an ink cartridge for a brush pen that incorporate the same.

ここで、Ｒ_１～Ｒ_４は炭化水素基を示し、Ｒ_５はエチレン基を示す。
ｍ、ｐは０以上の整数である。
２.第１項に記載のインキ組成物が内蔵されてなる筆ペン。
３.インキ貯蔵部と、ペン先と、前記インキ貯蔵部のインキをペン先へ供給するためのインキ供給機構とを備えてなる、第２項に記載の筆ペン。
４.インキカートリッジを備えてなる、第３項に記載の筆ペン。
５.前記インキ貯蔵部が内側にインキ収容室を設けた軸筒からなり、前記インキ貯蔵部と前記ペン先とが前記インキ供給機構を介して接合されてなる、第３項に記載の筆ペン。
６.多数の円盤体が櫛溝状の間隔を開け並列配置され、前記円盤体を軸方向に縦貫するスリット状のインキ誘導溝及び該溝より太幅の通気溝が設けられ、軸心にペン先へインキを誘導するためのインキ誘導芯が配置されてなるペン芯を前記インキ供給機構として備える、第３項～第５項のいずれか１項に記載の筆ペン。
７.第１項に記載のインキ組成物が内蔵されてなる、筆ペン用インキカートリッジ。」とする。 In order to solve the above problems, the present invention provides
"1. A water-based ink composition for a brush pen, comprising self-dispersing carbon black, a surfactant having an acetylene bond, and water, wherein the surfactant having an acetylene bond has a structure represented by the following formula (1):

Here, R ₁ to R ₄ represent a hydrocarbon group, and R ₅ represents an ethylene group.
m and p are integers of 0 or more.
2. A brush pen incorporating the ink composition described in paragraph 1.
3. A brush pen as described in paragraph 2, comprising an ink reservoir, a pen tip, and an ink supply mechanism for supplying ink from the ink reservoir to the pen tip.
4. The brush pen described in claim 3, which is equipped with an ink cartridge.
5. A brush pen as described in paragraph 3, wherein the ink storage section comprises a barrel having an ink containing chamber inside, and the ink storage section and the nib are joined via the ink supply mechanism.
6. A brush pen as described in any one of items 3 to 5, comprising a pen core as the ink supply mechanism, in which a number of disks are arranged in parallel with comb-like intervals, each disk has a slit-shaped ink guide groove running vertically through the axial direction, and a wider ventilation groove than the slit, and an ink guide core is arranged in the axial center to guide ink to the pen tip.
7. An ink cartridge for a brush pen, which contains the ink composition described in paragraph 1.

The present invention provides a water-based ink composition for a brush pen that allows for the creation of handwriting that is deep, vivid, and suppresses bleeding, while also providing good drying properties for the handwriting, and a brush pen and an ink cartridge for a brush pen that incorporate the same.

FIG. 1 is an explanatory diagram showing an embodiment of a brush pen according to the present invention. FIG. 11 is an explanatory diagram showing another embodiment of the brush pen of the present invention. FIG. 1 is an explanatory diagram showing one embodiment of an ink cartridge for a brush pen according to the present invention.

The following is a detailed description of the embodiments of the present invention. In this specification, the terms "parts," "%," and "ratio" used to indicate the composition are based on mass unless otherwise specified.

The aqueous ink composition for brush pens according to the present invention (hereinafter, sometimes referred to as the "aqueous ink composition" or "composition") contains at least water, self-dispersing carbon black, and a surfactant having an acetylene bond. Each component constituting the aqueous ink composition for brush pens according to the present invention will be described below.

(Self-dispersing carbon black)
The ink composition contains self-dispersible carbon black.
Self-dispersing carbon black refers to carbon black that can be dispersed in an aqueous medium without a dispersant such as a resin or a surfactant, and refers to carbon black in which a hydrophilic functional group is bonded to the surface of the carbon black by, for example, subjecting the carbon black to a physical or chemical treatment without using a dispersant for dispersing the carbon black. The hydrophilic group is preferably one or more hydrophilic groups selected from, for example, -COOM, -SO3M, -SO2M, -CO-, -COO-, -OM, -SO2NH2, -RSO2M, -PO3HM, -PO3M2, -SON2NHCOR, -NH3, and -NR3. In these formulas, M independently represents a hydrogen atom, an alkali metal, ammonium, a phenyl group which may have a substituent, or an organic ammonium. In addition, R in these formulas independently represents an alkyl group having 1 to 12 carbon atoms or a naphthyl group which may have a substituent.
Examples of the physical treatment include vacuum plasma treatment, and examples of the chemical treatment include a wet oxidation method in which oxidation is performed with an oxidizing agent in water, and a method in which p-aminobenzoic acid is bonded to the carbon black surface to bond a carboxyl group via a phenyl group.
Pigment inks with excellent paper surface permeability tend to have difficulty in providing good color development of handwriting because the pigment easily penetrates into the paper together with the vehicle. However, the composition of the present invention contains the above-mentioned self-dispersing carbon black, and can form a deep black and vivid handwriting while providing good paper surface permeability of the ink composition. In addition, the composition of the present invention can also suppress bleeding of handwriting due to the self-dispersing carbon black.
This is presumably because the hydrophilic functional groups present on the surface of the self-dispersed carbon black have a high affinity with the cellulose of the paper fibers, so that when the ink composition is ejected onto the paper surface, the self-dispersed carbon black is quickly adsorbed to the cellulose on the paper surface via its own hydrophilic functional groups, preventing the self-dispersed carbon black from penetrating into the paper or spreading around the written area on the paper surface.

Examples of commercially available self-dispersing carbon black that can be used in the ink composition include the Microjet series manufactured by Orient Chemical Industry Co., Ltd., the CAB-O-JET series manufactured by Cabot Corporation, the Aqua-Black series manufactured by Tokai Carbon Co., Ltd., and the Fuji-JET Black series manufactured by Fuji Pigment Co., Ltd.

The content of the self-dispersing carbon black is preferably 5 to 15 mass % and more preferably 6 to 12 mass % based on the total mass of the ink composition.
When the content is within the above range, the black color of the handwriting can be made deep and vivid, while preventing the self-dispersing carbon black in the handwriting from adhering to the periphery of the handwriting when the handwriting is rubbed, thereby contaminating the paper surface, and preventing the ink remaining on the pen tip from evaporating and drying out the tip, making it impossible to rewrite.

(Surfactants having acetylene bonds)
A surfactant having an acetylene bond is essential for the aqueous ink composition, as it improves the paper surface permeability of the ink composition.
Since a brush pen can hold a large amount of ink in the tip, when writing with a brush pen, a large amount of ink is likely to be applied to the paper surface, but the handwriting tends to dry poorly. However, since the ink composition of the present invention has excellent paper surface permeability, the handwriting dries well even when a large amount of ink is applied.
Furthermore, the surfactant can improve ink dischargeability by enabling the ink composition to move smoothly through ink flow paths in the ink reservoir, ink supply mechanism, and pen tip of the brush pen.

ここで、Ｒ_１～Ｒ_４は炭化水素基を示し、Ｒ_５はエチレン基を示す。
ｍ、ｐは０以上の整数である。 The surfactant having an acetylene bond that can be used in the ink composition has a structure represented by the following general formula (1).

Here, R ₁ to R ₄ represent a hydrocarbon group, and R ₅ represents an ethylene group.
m and p are integers of 0 or more.

In consideration of improving the paper surface permeability of the ink composition, the surfactant having an acetylene bond used in the present invention preferably has an HLB value of 4 to 18, more preferably 8 to 17, and particularly preferably 12 to 16.
Furthermore, m+p in formula (1) preferably satisfies 0≦m+p≦30, and more preferably satisfies 0≦m+p≦20.
Here, the HLB value of the surfactant used in the present invention is a value proposed by Griffin to evaluate the hydrophilicity of a compound, and refers to a value calculated by the following general formula (2). The HLB value according to the Griffin method indicates a value within a range of 0 to 20, and the larger the value, the more hydrophilic the compound is.
HLB value = 20 × (mass % of hydrophilic group) = 20 × (sum of formula weight of hydrophilic group / molecular weight of surfactant) (2)

Specific surfactants having an acetylene bond that can be used in the ink composition of the present invention include Olfine D-10A, Olfine D-10PG, Olfine E1004, Olfine E1010, Olfine E1020, Olfine E1030W, Olfine PD-001, Olfine PD-002W, Olfine PD-003, Olfine PD-004, Olfine PD-201, Olfine PD-301, Olfine EXP.4001, Olfine EXP.4200, Olfine EXP.4123, Olfine EXP. Examples of the surfactant include 4300, Surfynol 82, Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104PA, Surfynol 104PG-50, Surfynol 104S, Surfynol 420, Surfynol 440, Surfynol 465, Surfynol 485, Surfynol 2502, Dynol 604, and Dynol 607, all manufactured by Nissin Chemical Industry Co., Ltd., and Acetylenol E13T, Acetylenol EH, Acetylenol EL, Acetylenol E40, Acetylenol E60, Acetylenol E81, Acetylenol E100, and Acetylenol 85, all manufactured by Kawaken Fine Chemicals Co., Ltd., and one or more of these can be preferably used. Of the above surfactants, Olfine E1010, Olfine E1020 and Surfynol 485 are preferred in view of improving the ink dischargeability and the paper surface permeability of the ink composition.
The surfactant having an acetylene bond may be used alone or in combination of two or more kinds.

The content of the surfactant having an acetylene bond is preferably 0.5 to 3 mass % of the total mass of the ink composition, and more preferably 0.5 to 2.5 mass %, in order to improve the ink's paper permeability and increase the drying speed of the handwriting while further suppressing bleeding of the handwriting.

(water)
The water is not particularly limited, and for example, ion-exchanged water, ultrafiltered water, distilled water, or the like can be used.

(Water-soluble organic solvent)
For the ink composition, a conventionally known water-soluble organic solvent can be used.
Specific examples include polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol; alkanolamines such as 3-methoxy-3-methyl-1-butanol, monoethanolamine, diethanolamine, and triethanolamine; and 2-pyrrolidone.
Among these, ethylene glycol, diethylene glycol, propylene glycol, 3-methoxy-3-methyl-1-butanol and 2-pyrrolidone are preferably used because they can further enhance the drying properties of handwriting.
The water-soluble organic solvent may be used alone or in combination of two or more.

(others)
The ink composition of the present invention may contain other substances than those mentioned above, if necessary. Specifically, dyes, pigments other than the self-dispersing carbon black, preservatives, extenders such as kaolin, talc, mica, clay, bentonite, calcium carbonate, aluminum hydroxide, sericite, and potassium titanate, resin particles made of polyolefin resin, acrylic resin, nylon resin, silicone resin, urethane resin, and fluororesin, acrylic resin, urethane resin, styrene-butadiene resin, alkyd resin, sulfoamide resin, maleic acid resin, polyvinyl acetate resin, ethylene vinyl acetate resin, vinyl chloride-vinyl acetate resin, copolymers of styrene and maleic acid ester, styrene-acrylonitrile resin, cyanate-modified polyalkylene glycol, ester gum, xylene resin, urea resin, urea aldehyde resin, phenol resin, alkylphenol resin, and terpene phenol resin. , rosin-based resins and hydrogenated compounds thereof, rosin phenolic resins, polyvinyl alkyl ethers, polyamide resins, polyolefin resins, nylon resins, polyester resins, cyclohexanone-based resins, shear thinning agents, rust inhibitors such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin, various surfactants such as urea, phosphate ester surfactants, silicone surfactants, and fluorine-based surfactants, pigment dispersants made of water-soluble resins such as polyvinyl alcohol and polyvinylpyrrolidone, reduced or non-reduced starch hydrolysates, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate.
Also applicable are acidic substances such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, and basic substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen phosphate, and potassium hydrogen phosphate.

The viscosity of the ink composition is preferably 1 to 6 mPa·s, and more preferably 2 to 5 mPa·s, at 20° C. If the viscosity is within the above range, the ink dischargeability is improved, and it is easy to increase the ink's penetration into paper and improve the handwriting drying property.
The viscosity of the ink composition is measured using an EL type viscometer.

The surface tension of the ink composition is preferably 25 to 40 mN/m, and more preferably 25 to 35 mN/m at 20° C., in order to improve the paper surface permeability of the ink composition while further suppressing bleeding of handwriting.
The surface tension of the ink composition can be determined by measuring with a surface tension meter manufactured by Kyowa Interface Science Co., Ltd. using a platinum plate according to the vertical plate method.

The aqueous ink composition according to the present invention can be produced by any conventionally known method. Specifically, the required amounts of the above-mentioned components are mixed together using various stirrers such as a propeller stirrer, homodisper, or homomixer, or various dispersing machines such as a bead mill, to produce the composition.

(Brush pen)
The structure of the brush pen is not particularly limited as long as it has a brush-shaped pen tip. One example of the brush pen is a brush pen that has an ink reservoir, a brush-shaped pen tip, and an ink supply mechanism for supplying the ink stored in the ink reservoir to the pen tip.
Specific examples of the structure of the brush pen include: (1) a structure comprising a brush-shaped nib, an ink storage section, and an ink supply mechanism, the ink storage section consisting of a barrel with an ink containing chamber inside, and the ink storage section and the nib being joined via the ink supply mechanism; and (2) a structure comprising a brush-shaped nib, an ink storage section, and an ink supply mechanism, and a removable ink cartridge as the ink storage section.
As a more specific example of the structure in (1) above, there can be mentioned a structure in which a pen tip and an ink supply mechanism are attached to the front part of a barrel consisting of a bottomed cylindrical body, and an ink storage chamber is formed inside the barrel behind the ink supply mechanism.
As a more specific example of the structure in (2) above, there can be mentioned a structure in which a front barrel having a pen tip and an ink supply mechanism attached thereto is releasably connected to a rear barrel consisting of an ink cartridge, and a structure in which a front barrel having a pen tip and an ink supply mechanism attached thereto is releasably connected to an ink cartridge, and the ink cartridge is covered by a rear barrel.

There is no limit to the materials that can be used as constituent materials for the ink storage section, and metals, glass, rubber, and synthetic resins such as polyethylene resin, polypropylene resin, polymethylpentene resin, polycarbonate resin, polyethylene terephthalate resin, polyacetal resin, ABS resin, polyurethane resin, and polystyrene resin can be used. Among these, polyethylene resin and polypropylene resin are preferred.

The ink reservoir may be configured to be filled directly with the ink composition, or may be configured to include an ink reservoir or ink occlusion body that can be filled with the water-based ink composition.
In addition, when the brush pen is configured to directly fill the ink composition, the ink container may incorporate an agitator such as an agitator ball for agitating the ink in order to redisperse the self-dispersing carbon black. Examples of the shape of the agitator include a spherical body and a rod-shaped body. The material of the agitator is not particularly limited, but specific examples include metal, ceramic, resin, and glass.
Furthermore, when the brush pen is provided with an ink occlusion body capable of being filled with an ink composition, the ink occlusion body is preferably a fiber bundle made of twisted fibers.

There are no limitations on the structure of the ink storage section, so long as it has a structure capable of storing the ink composition in the ink storage chamber.

Ink cartridges can be ones that double as the barrel of the brush pen when connected to the brush pen body, or ones that cover and protect the barrel (rear barrel) after being connected to the brush pen body. These cartridges can be filled with ink before connecting to the brush pen.

The structure of the ink cartridge is not particularly limited, and may be, for example, a bottomed cylinder having a circular cross section perpendicular to the longitudinal direction. The cylinder refers to a hollow, elongated rod-like body. The ink cartridge may have a structure that can be deformed and restored by pressure.
In the ink cartridge used in the present invention, the outer surface or inner surface of the cylindrical body may be tapered or may have a step.

The pen tip can be a brush-shaped tip made of a fiber bundle such as a writing brush, in which the fibers are tightly bundled in the longitudinal direction, a plastic porous body with continuous pores, a heat-fused or resin-processed body of synthetic resin fibers, or an extrusion-molded body of soft resin or elastomer. The tip may be glued with a water-soluble substance such as polyvinyl alcohol, polyvinylpyrrolidone, starch, or gum arabic.

The ink supply mechanism is not particularly limited, and examples thereof include: (1) a mechanism that includes an ink guide core made of a fiber bundle or the like as an ink flow rate adjusting member and guides the aqueous ink composition to the pen tip; (2) a mechanism in which a large number of disks are arranged in parallel with a comb-like groove-like space between them, a slit-like ink guide groove that runs vertically through the disks in the axial direction, and a wide ventilation groove is provided beyond the groove, and the ink composition is supplied to the pen tip through the ink guide groove; (3) a mechanism in which a large number of disks are arranged in parallel with a comb-like groove-like space between them, and a slit-like ink guide groove that runs vertically through the disks in the axial direction and a mechanism for directing the ink composition to the pen tip via a pen tip having a wider ventilation groove than the groove and an ink guide core arranged in the shaft center for directing ink from the ink storage unit to the pen tip; (4) a mechanism for supplying the water-based ink composition to the pen tip, equipped with an ink flow rate adjustment member using a valve mechanism; (5) a mechanism for supplying the water-based ink composition directly to the pen tip from an ink reservoir or barrel equipped with a pen tip; and (6) a mechanism for supplying the ink composition to the pen tip via a porous body with continuous pores that can be impregnated with the ink composition.

When the ink supply mechanism is a pen core in which a number of disks are arranged in parallel with a comb-like gap between them, a slit-shaped ink guide groove that runs vertically through the disks in the axial direction and a vent groove that is wider than the slit-shaped ink guide groove are provided, and an ink guide core for guiding ink from the ink storage unit to the pen tip is arranged at the axial center, the ink supply mechanism tends to stably and satisfactorily supply ink from the ink storage unit to the pen tip, thereby improving ink ejection performance. For this reason, the ink supply mechanism of (3) is a preferred form as an ink supply mechanism for a brush pen.

Materials for the ink supply mechanism include polyethylene resin, polypropylene resin, polymethylpentene resin, polycarbonate resin, and acrylonitrile-butadiene-styrene copolymer resin, and any of these can be preferably used.

Below are examples of the aqueous ink composition of the present invention, as well as a brush pen and an ink cartridge for a brush pen that use the same, but the present invention is not limited to these.

Example 1
The following raw materials and amounts were mixed and stirred at room temperature for 1 hour using a Homo Disper to obtain a water-based ink composition for brush pens.
Self-dispersing carbon black dispersion: 40% by mass
(Dispersion in which carbon black having carboxy groups bonded to the surface by surface treatment is dispersed, 20% by mass dispersion in water, no dispersant contained, product name: Aqua-Black 162, manufactured by Tokai Carbon Co., Ltd.)
Surfactant having an acetylene bond: 1% by mass
(Product name: Olfin E1010, HLB value: 13.3, manufactured by Nissin Chemical Industry Co., Ltd.)
Ion-exchanged water 59% by mass

(Examples 2 to 11, Comparative Examples 1 and 2)
Ink compositions of Examples 2 to 11 and Comparative Examples 1 and 2 were obtained by changing the types and amounts of the components to be blended as shown in Table 1 in comparison with Example 1.
Details of the materials used in the above examples are as follows:
Self-dispersing carbon black dispersion 1
(Dispersion in which carbon black having carboxy groups bonded to the surface by surface treatment is dispersed, 20% by mass dispersion in water, no dispersant contained, product name: Aqua-Black 162, manufactured by Tokai Carbon Co., Ltd.)
Self-dispersing carbon black dispersion 2
(Dispersion in which carbon black having carboxy groups bonded to the surface by surface treatment is dispersed, 15% by mass dispersion in water, no dispersant contained, product name: Fuji-JETBlack B-15, manufactured by Fuji Pigment Co., Ltd.)
Carbon black dispersion (a dispersion in which carbon black is dispersed using a dispersant made of POE(20) POP(8) cetyl ether, 20% by mass aqueous dispersion)
Surfactant having an acetylene bond 1
(Product name: Olfin E1010, HLB value 13.3, manufactured by Nissin Chemical Industry Co., Ltd.)
Surfactant 2 having an acetylene bond
(Product name: Olfin E1020, HLB value 15-16, manufactured by Nissin Chemical Industry Co., Ltd.)
Phosphate ester surfactant (polyoxyalkylene styrenated phenyl ether phosphate ester, product name: Plysurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・Silicone surfactant 1
(Polyether modified silicone, product name: TSF-4440, manufactured by Momentive Performance Materials Japan, Inc.)
・Silicone surfactant 2
(Polyether modified silicone, product name: KF-6004, manufactured by Shin-Etsu Chemical Co., Ltd.)
・Triethanolamine ・Preservative Benzisothiazolin-3-one (product name: Proxel XL-2, manufactured by Lonza Japan Co., Ltd.)
・Ethylene glycol ・Glycerin ・2-pyrrolidone ・Urea ・Ion-exchanged water

The prepared water-based ink compositions were evaluated as follows. The results are shown in Table 1.
The following brush pens were used in the evaluation tests.
Brush pen (A) A brush pen equipped with a removable ink cartridge as an ink storage unit (see FIG. 1)
The brush pen 1 is composed of a rear barrel consisting of an ink cartridge 2 which is a cylindrical bottomed body made of polyethylene resin and which can be deformed when pressed and restored to its original shape, and a front barrel 3 which is fitted with a nib 4 consisting of a bundle of thermoplastic polyester elastomer and an annular porous body 5 having continuous pores formed therein. An inside plug 7 having a central hole 6 is fitted into one end of the ink cartridge 2. The nib 4 is provided with an adhesive layer 8 having a protrusion 9 on its rear end surface. The annular porous body 5 is loosely inserted around the rear side circumference of the nib 4, and the protrusion 9 and the front end of the inside plug 7 are in contact with each other, forming an induction gap 10 between the adhesive layer 8 and the front end of the inside plug 7.
(B) A brush pen in which the ink reservoir is made of a barrel with an ink storage chamber inside, and the ink reservoir and the pen tip are joined via an ink supply mechanism (see FIG. 2).
The brush pen 11 has an ink supply mechanism 13 attached to the front of a barrel 12 made of a polyethylene resin with a bottomed cylinder, and the ink supply mechanism 13 has a pen tip 14 made of an extrusion molded body of soft resin with a polyurethane surface coating, and an ink storage chamber 15 is formed inside the barrel behind the ink supply mechanism 13. The ink supply mechanism 13 has a number of disks 16 arranged in parallel with comb-like intervals, a slit-like ink guide groove 17 that runs vertically through the disks 16 in the axial direction, and a vent groove 18 that is wider than the groove. An ink guide core 19 is arranged at the axial center and connected to the pen tip 14.

The following ink cartridges were used for the brush pen (A).
- Ink cartridge to be attached to the brush pen (A) (see Figure 3)
The ink cartridge 2 has a first mounting hole 21 larger in diameter than the central hole 6 and a second mounting hole 21 larger in diameter than the first mounting hole 20 arranged concentrically at the rear of the inner plug 7, and an inner pipe 23 and an outer pipe 24 are fitted into the holes 22 and 23.

(Evaluation of handwriting color development)
The character "Komoro naru" was written with a brush pen containing the ink composition, and the color tone and thickness of the handwriting were visually observed. Note that, as the writing test paper, a writing paper (product name: NPi Form <55>, manufactured by Nippon Paper Industries Co., Ltd.) conforming to "Brush Pen" (Japan Writing Instruments Industry Association standard, JWIMA M 003:2015) was used. The evaluation criteria were A as pass and B as fail.
A: Deep, vivid black.
B: Dark grayish black. Slightly pale.
The color density (K value) of the handwriting was measured using a fluorescent spectrodensitometer (product name: FD-7 type, manufactured by Konica Minolta, Inc.) The measured value (K value) was the average value of three measurements, and a larger value indicates a higher density of the handwriting.

(Evaluation of handwriting drying property)
After writing, the handwriting was rubbed with a finger, and the spread of the ink composition around the handwriting was visually observed. The same type of paper as that used in the evaluation of the handwriting color development was used as the test paper. The evaluation criteria were A and B as pass, and C as fail.
A: When the handwritten mark is rubbed 1 second after writing, no evidence of the ink composition spreading to the periphery of the handwritten mark is observed.
B: When the handwritten mark is rubbed 1 second after writing, the ink composition spreads to the periphery of the handwritten mark, but when the handwritten mark is rubbed 3 seconds after writing, no evidence of the ink composition spreading to the periphery of the handwritten mark is observed.
C: Even when 4 seconds have passed since writing, when the handwritten mark is rubbed, there is evidence that the ink composition has spread to the periphery of the handwritten mark.

(Evaluation of handwriting bleeding)
A character (the Chinese numeral "一") was written, and the presence or absence of bleeding at the beginning of writing was confirmed. When forming the beginning of writing, a load of 50 g was applied and the writing was stopped for 1 second. The same type of writing paper as that used in the above evaluation was used. The evaluation criteria were A and B as pass, and C as fail.
A: No bleeding was observed and the outline was clear.
B: Blurring is observed in some parts of the outline.
C: The outline is noticeably blurred and unclear.

REFERENCE SIGNS LIST 1 Brush pen 2 Ink cartridge 3 Front barrel 4 Pen tip 5 Annular porous body 6 Central hole 7 Inner plug 8 Fixing layer 9 Projection 10 Guiding gap 11 Brush pen 12 Barrel 13 Ink supply mechanism 14 Pen tip 15 Ink storage chamber 16 Disk body 17 Ink guiding groove 18 Ventilation groove 19 Ink guiding core 20 First mounting hole 21 Second mounting hole 22 Inner pipe 23 Outer pipe

Claims (2)

A brush pen comprising an ink reservoir, a pen tip, and an ink supply mechanism for supplying ink stored in the ink reservoir to the pen tip,
The ink storage unit includes an ink cartridge,
The pen tip is made of a fiber bundle,
the ink supply mechanism is made of a porous body having continuous pores,
A brush pen having a built-in aqueous ink composition, the brush pen comprising: self-dispersing carbon black; a surfactant having an acetylene bond; and water, the surfactant having an acetylene bond having a structure represented by the following formula (1):

Here, R1 to R4 each represent a hydrocarbon group, R5 represents an ethylene group, and m and p each represent an integer of 0 or more. A brush pen comprising an ink reservoir, a pen tip, and an ink supply mechanism for supplying ink stored in the ink reservoir to the pen tip,
The ink storage section is made of a barrel having an ink storage chamber therein,
The pen tip is made of an extrusion molded body of a soft resin or an elastomer,
the ink reservoir and the pen tip are joined via the ink supply mechanism,
The ink supply mechanism is a pen core comprising a number of disks arranged in parallel with comb-like intervals, a slit-shaped ink guide groove that runs vertically through the disks in the axial direction, and a vent groove that is wider than the slit, and an ink guide core that guides ink to the pen tip is disposed in the axial center,
A brush pen having a built-in aqueous ink composition, the brush pen comprising: self-dispersing carbon black; a surfactant having an acetylene bond; and water, the surfactant having an acetylene bond having a structure represented by the following formula (1):

Here, R1 to R4 each represent a hydrocarbon group, R5 represents an ethylene group, and m and p each represent an integer of 0 or more.

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