JP2021107518A - Water-based ink composition for writing instruments and writing instrument that stores the same - Google Patents

Abstract

To provide a water-based ink composition for writing instruments that has excellent ink discharge stability, suppresses a failure in handwriting such as fading and line skipping, and also suppresses blurred writing and bleed-through on a paper surface, and can form excellent handwriting, and a writing instrument that stores the same.SOLUTION: A water-based ink composition for writing instruments has at least a colorant, water, and a nonionic surfactant of a specific structure, wherein: the nonionic surfactant is added in a range of 0.1-1 mass% relative to the total amount of the water-based ink composition; a surface tension of the water-based ink composition for writing instruments is set to 30-60 mN/m, and a viscosity thereof is set to 1-20 mPa s. There is also provided a writing instrument that stores the water-based ink composition for writing instruments.SELECTED DRAWING: None

Description

The present invention relates to a water-based ink composition for a writing tool and a writing tool containing the composition. More specifically, the present invention relates to a water-based ink composition for a writing tool capable of suppressing bleeding and strike-through of handwriting on a paper surface while having excellent ink ejection stability, and a writing tool containing the composition.

Conventionally, inks using water as a main solvent (water-based inks) have been known, and are widely used because of their low odor and high safety. Further, a large number of discs are arranged in parallel with a comb-groove-like interval, and a slit-shaped ink guide groove that runs through the disc in the axial direction and a ventilation groove wider than the groove are provided like a pen nib. A writing instrument (called a direct liquid writing instrument) that guides ink to the pen tip via a simple ink flow rate adjusting body is widely used.
Normally, the pen core is molded from synthetic resin, but since the surface of synthetic resin is relatively hydrophobic, when applying water-based ink to a direct-liquid writing tool, it imparts affinity to the hydrophobic surface. Therefore, it is necessary to adjust the surface tension of the ink to improve the wettability (affinity) with respect to the pen core. If the surface tension of the ink is high, the wettability to the pen core is poor, and the ink may not be stably ejected from the pen tip, resulting in writing defects such as blurring and line skipping. Therefore, there are disclosed ink compositions in which the surface tension of the ink is lowered by using various additives to improve the ink ejection stability from the pen tip (see, for example, Patent Documents 1 to 3).
Patent Document 1 discloses an aqueous ink composition containing at least a water-soluble dye, a nonionic surfactant having an HLB of 18.0 to 20.0, and water.
Further, Patent Document 2 discloses an ink composition for a water-based ballpoint pen, which comprises a water-based ink composition containing a colorant containing a water-soluble silicone oil and a fatty acid salt in combination.
Further, Patent Document 3 discloses an ink for a water-based ballpoint pen containing a dye, a solvent composed of water and a polyhydric alcohol, a fluorine-based surfactant, and a silicone-based surfactant.
However, when the surface tension of the ink is lowered to improve the ink ejection stability, the permeability to the paper surface is extremely increased depending on the type and amount of the additive, and bleeding or strike-through may occur in the handwriting. .. In addition, the wettability with respect to the pen core is improved so that the ink smoothly flows in and is held between the comb grooves of the pen core, and the ink holding power (retention property) is improved, but the ink is held between the comb grooves. Ink is not sufficiently collected in the ink storage of the writing tool, and if the pressure inside the writing tool is repeatedly changed due to temperature changes or the attachment and detachment of the cap, there is a problem that ink leakage (ink dripping) occurs from the pen tip. there were.

Japanese Unexamined Patent Publication No. 3-79682 Japanese Unexamined Patent Publication No. 10-21244 Japanese Unexamined Patent Publication No. 2004-346181

An object of the present invention is to provide a water-based ink composition for a writing tool capable of suppressing bleeding and strike-through of handwriting on a paper surface while having good ink ejection stability, and a writing tool containing the composition.

（式中、ｍは０〜１１の整数を示し、ｎは０〜１１の整数を示し、ｍ＋ｎ＝９〜１１である。また、ｘはオキシエチレン基の平均付加モル数であり、１〜２０の数を示し、ｙはオキシプロピレン基の平均付加モル数であり、１〜２０の数を示す。）
さらには、前記ノニオン系界面活性剤が、水性インキ組成物全量中に０．１〜１質量％の範囲で添加されてなること、表面張力が３０〜６０ｍＮ／ｍであること、２０℃において、ＥＬ型回転粘度計による回転速度２０ｒｐｍでの粘度が１〜２０ｍＰａ・ｓであることを要件とする。
さらには、前記筆記具用水性インキ組成物を収容してなる筆記具であること、前記筆記具が、ペン先と、インキ充填機構と、インキ供給機構とを備え、前記インキ供給機構に前記筆記具用水性インキ組成物を直に充填し、前記インキ供給機構が、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、軸心にインキ充填機構から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備える直液式筆記具であること、前記ペン先がボールペンチップであること、前記筆記具が、キャップを備えてなる筆記具であることを要件とする。 The present invention requires at least a water-based ink composition for writing tools, which comprises a colorant, water, and a nonionic surfactant represented by the following general formula (1).

(In the formula, m represents an integer of 0 to 11, n represents an integer of 0 to 11, and m + n = 9 to 11. Further, x is the average number of moles of oxyethylene groups added, and is 1 to 20. , Y is the average number of moles of oxypropylene groups added, and indicates the number of 1 to 20.)
Further, the nonionic surfactant is added in the range of 0.1 to 1% by mass in the total amount of the aqueous ink composition, the surface tension is 30 to 60 mN / m, and at 20 ° C. It is required that the viscosity at a rotation speed of 20 rpm by an EL type rotational viscometer is 1 to 20 mPa · s.
Further, the writing tool is a writing tool that houses the water-based ink composition for writing tools, the writing tool includes a pen tip, an ink filling mechanism, and an ink supply mechanism, and the ink supply mechanism includes the water-based ink for writing tools. The composition is directly filled, and the ink supply mechanism is such that a large number of discs are arranged in parallel with a comb-groove-like interval, and a slit-shaped ink guide groove that runs through the disc in the axial direction and a thicker than the groove. A direct-liquid writing tool having a width vent groove and a pen core in which an ink guide core for guiding ink from an ink filling mechanism to a pen tip is arranged at the axis, and the pen tip is a ball pen tip. It is a requirement that the writing tool is a writing tool provided with a cap.

The present invention is a water-based ink composition for writing instruments containing a nonionic surfactant having a specific structure, which has good wettability to writing instrument members such as a pen tip and an ink flow rate controller, and has good ink ejection stability. Therefore, it is possible to provide a water-based ink composition for a writing instrument capable of forming a good writing instrument by suppressing bleeding and strike-through of the writing instrument on a paper surface while suppressing writing defects such as blurring and line skipping, and a writing instrument containing the composition. ..
Further, when the water-based ink composition of the present invention is applied to a writing tool provided with a pen core as an ink flow rate regulator, even when the pressure inside the writing tool changes due to repeated temperature changes and cap attachment / detachment. It is possible to provide a writing tool having good ink storage property in the comb groove portion of the pen core and ink recovery property in the ink storage portion of the ink filling mechanism, and having good pen core performance in which ink does not easily drop from the pen tip.

The water-based ink composition for writing tools of the present invention (hereinafter, may be referred to as "water-based ink composition", "ink composition" or "ink") includes at least a colorant, water, and the above general formula (1). It is composed of a nonionic surfactant having a specific structure indicated by. Hereinafter, each component constituting the water-based ink composition of the present invention will be described.

The colorant applied to the water-based ink composition of the present invention is not particularly limited as long as it is a dye or pigment that can be dissolved or dispersed in an water-based medium.
Examples of the dye include acid dyes, basic dyes, and direct dyes.
Specifically, as acid dyes, ponceau (CI 16255), tartrazine (CI 19140), acid blue black 10B (CI 20470), guinea green (CI 42085), Brilliant Blue FCF (CI 42090), Acid Violet 6B (CI 42640), Solve Blue (CI 42755), Naphthalene Green (CI 44825), Eosin (CI 45380) ), Phloxine (CI 45410), erythrosine (CI 45430), niglosin (CI 50420), acid flavin (CI 56205) and the like.
Specifically, as basic dyes, chrysoidine (CI 11270), methyl violet FN (CI 42535), crystal violet (CI 42555), malachite green (CI 42000), Victoria. Examples thereof include blue FB (CI 44045), rhodamine B (CI 45170), acridine orange NS (CI 46005), methylene blue B (CI 52015) and the like.
Specifically, as direct dyes, Congo Red (CI 22120), Direct Sky Blue 5B (CI 24400), Violet BB (CI 27905), Direct Deep Black EX (CI 30235). ), Kayaras Black G Conc (CI 35225), Direct First Black G (CI 35255), Phthalocyanine Blue (CI 74180) and the like can be exemplified.

Examples of the pigment include inorganic pigments, organic pigments, brilliant pigments, fluorescent pigments, phosphorescent pigments and the like.
Examples of the inorganic pigment include titanium oxide such as carbon black, rutile type and anatase type, zinc oxide, iron black, yellow iron oxide, petals, ultramarine blue and the like. Further, it is also possible to use an aqueous dispersion pigment or the like which is finely and stably dispersed in an aqueous medium by using a surfactant or a resin in advance.
Specifically, as an inorganic pigment, C.I. I. Pigment Blue 15: 3B [manufactured by Sanyo Dye Co., Ltd., trade name: Sandye Super Blue GLL-E (solid content: 24%)], C.I. I. Pigment Red 146 [manufactured by Sanyo Dye Co., Ltd., trade name: Sandye Super Pink FBL (solid content: 21.5%)], C.I. I. Pigment Yellow 81 [manufactured by Dainichiseika Kogyo Co., Ltd., trade name: TC Yellow FG (solid content: about 30%)], C.I. I. Pigment Red 220/166 [manufactured by Dainichiseika Kogyo Co., Ltd., trade name: TC Red FG (solid content: about 35%)] and the like can be exemplified.
Specific examples of the resin for dispersing the inorganic pigment include polyamide resin, polyurethane resin, polyester resin, epoxy resin, melamine resin, phenol resin, silicone resin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate resin, and polyvinyl chloride resin. , Polyvinylidene chloride resin, polystyrene resin, acrylic acid resin, maleic acid resin, gum arabic, cellulose, dextran, casein, derivatives thereof, copolymers of the above resins and the like can be exemplified.

Organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindolin pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, and quinophthalone pigments. Examples thereof include pigments, diketopyrrolopyrrole pigments, slene pigments, indigo pigments, phthalone pigments, methine / azomethine pigments, and metal complex pigments.

Glittering pigments include metallic glossy pigments in which the surface of a core material such as a glass piece is coated with gold, silver, etc., and a metal oxide such as titanium oxide on the surface of a core material such as natural mica, synthetic mica, and flaky aluminum oxide. Metal pigments obtained by peeling off a metal vapor deposition film such as aluminum formed on a base material such as pearl pigments, cholesteric liquid crystal pigments, metal powder pigments, films, etc. coated with, and metals such as aluminum on colorless transparent or colored transparent films. Examples thereof include metal pigments having a vapor-deposited film formed and powder-treated.

Specifically, as a metallic luster pigment in which the surface of a core substance such as a glass piece is coated with gold, silver, etc., manufactured by Nippon Sheet Glass Co., Ltd., trade names: Metashine 5480PS, 5230PS, 5150PS, 5090PS, 2080PS , 1030PS, 2025PS, 1030GP, 2080GP and the like can be exemplified.

Specific examples of pearl pigments in which the surface of natural mica is coated with titanium oxide are manufactured by Merck & Co., Inc., trade names: Iriodin 100, 111, 120, 153, 201, 211, 223, 231. Examples thereof include the same 302, the same 323, the same 520, the same 522, and the same 524.
Further, as a pearl pigment in which the surface of synthetic mica is coated with titanium oxide, specifically, it is manufactured by Nippon Koken Kogyo Co., Ltd., trade name: TWINCLE PEARL SXB, YXB, RXB, BXB, SXD, YXD. , RXD, BXD, SX, YX, RX, BX,
Made by Nippon Koken Kogyo Co., Ltd., Product names: ULTIMICA SB-100, SD-100, SE-100, SF-100, SH-100, YB-100, YE-100, YF- 100 etc. can be exemplified.
Further, as a pearl pigment in which the surface of flaky aluminum oxide is coated with titanium oxide, specifically, manufactured by Merck Group, trade name: Xirallic T60-10 WNT Cristal Silver, T60-20 WNT Sunbeam Gold, T60- Examples thereof include 21 WNT Solaris Red, T60-23 WNT Galaxy Blue, T60-24 WNT Stellar Green, and T60-25 WNT Cosmic Turquoise.

Specific examples of the cholesteric liquid crystal pigment include Wacker Chemie's trade name: HELICONE HC Sapphire, Scarabeus, Jade, and Maple.

Examples of the metal powder pigment include metal powder pigments having a metallic luster such as aluminum powder, brass powder, stainless steel powder, and bronze powder, and metal powder pigments in which colorants such as dyes and pigments are adsorbed on these metal powder pigments. Can be mentioned. Further, it is also possible to use a pigment dispersion in which the above metal powder pigment is processed in advance with a surfactant, a resin, a solvent or the like and dispersed to form a paste, or a liquid metal powder pigment dispersion.

Examples of the fluorescent pigment include synthetic resin fine particle fluorescent pigments in which various fluorescent dyes are solid-solved in a resin matrix.

As the phosphorescent pigment, a general-purpose pigment is used as long as it has the property of absorbing and accumulating light rays such as the sun and electric lamps, and gradually emitting light in a dark place to emit light (this is called afterglow). Examples thereof include phosphorescent pigments such as CaS / Bi-based, CaSrS / Bi-based, ZnS / Cu-based, ZnCdS / Cu-based, and SrAl2O4 / rare earth metal-based.

The above colorants may be used alone or in admixture of two or more, and are preferably blended in the range of 1 to 50% by mass, more preferably 5 to 30% by mass, based on the total amount of the ink composition. NS. If the blending ratio of the colorant exceeds 50% by mass, the ink ejection stability of the writing instrument containing the ink composition is lowered, and handwriting defects such as blurring and line skipping are likely to occur. On the other hand, if the blending ratio of the colorant is less than 1% by mass, it becomes difficult to obtain a suitable handwriting concentration as a writing tool.
When the above pigment is used as the colorant, a pigment dispersant can be used if necessary. Examples of the pigment dispersant include anionic and nonionic surfactants, anionic polymers such as polyacrylic acid and styrene acrylic acid, and nonionic polymers such as PVP and PVA.

Further, as the colorant, a microcapsule pigment containing a thermochromic composition, a microcapsule pigment containing a dye or a pigment together with the thermochromic composition, or the like can also be used.
The thermochromic composition includes (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction that determines the temperature at which the color reaction of the above (a) and (b) components occurs. Examples thereof include a reversible thermochromic composition composed of a medium.
Examples of the reversible thermochromic composition include those before and after a predetermined temperature (discoloration point) described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-2398, and the like. Discolored in the temperature range above the high temperature side discoloration point, and exhibited in the temperature range below the low temperature side discoloration point. Of both states, only one specific state exists in the normal temperature range, and the other. The state of is maintained as long as the heat or cold required for the state to develop is applied, but returns to the state exhibited at room temperature when the heat or cold is not applied, and the hysteresis width is relatively small. A heat-decoloring type (decoloring by heating and developing color by cooling) reversible thermochromic composition having a characteristic (ΔH = 1 to 7 ° C.) can be used.

Further, relatively large hysteresis characteristics (ΔH = 8 to 50) described in JP-A-4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936 and the like. It exhibits a large hysteresis characteristic described in JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523, and the like. That is, the shape of the curve plotting the change in color density due to temperature change is large in the case where the temperature is raised from the lower temperature side than the discoloration temperature range and the case where the temperature is lowered from the higher temperature side than the discoloration temperature range. The color changes by following different paths, and the color development state in the temperature range of the _{complete color development temperature t 1 or less, or the decolorization state in the high temperature range of the complete decolorization temperature t 4} or more is the specific temperature range [color development start temperature t ₂ ~. (decolored by heating, color is by cooling) heat-decolorizable with color-memorizing in a temperature range of between decoloring starting temperature t ₃ (substantially two-phase retaining temperature region)] the reversible thermochromic composition of Can be used.
Specifically, as the reversible thermochromic composition having the above-mentioned color memory applied to the present invention, the complete color development temperature can be obtained only in a freezer, a cold region, or the like, that is, −50 to 0 ° C. , Preferably -40 to -5 ° C, more preferably -30 to -10 ° C, and the complete decolorization temperature is the frictional heat of the friction body, the temperature obtained from a familiar heating body such as a hair dryer, that is, 50 to 95 ° C. By specifying the temperature in the range of preferably 50 to 90 ° C., more preferably 60 to 80 ° C., and specifying the ΔH value to 40 to 100 ° C., it is effective in maintaining the color exhibited in the normal state (daily living temperature range). Can work.

Further, as a reversible thermochromic composition, a heat-coloring type using a gallic acid ester described in Japanese Patent Publication No. 51-44706, Japanese Patent Application Laid-Open No. 2003-253149, etc. (coloring by heating and decoloring by cooling). The reversible thermochromic composition of) can also be used.

The reversible thermochromic composition is a companion containing the above components (a), (b), and (c) as essential components, and the ratio of each component is the concentration, discoloration temperature, discoloration form, and type of each component. However, in general, the component ratio at which the desired characteristics are obtained is (a) component 1, (b) component 0.1 to 100, preferably 0.1 to 50, and more preferably 0. It is in the range of 5 to 20, (c) component 1 to 800, preferably 5 to 200, and more preferably 10 to 100 (the above ratios are all parts by mass).

Although the reversible thermochromic composition can be used as it is, it is preferable to enclose it in microcapsules and use it as a reversible thermochromic microcapsule pigment. This is because a physically stable pigment can be formed, and further, the reversible thermochromic composition can be kept in the same composition under various usage conditions and can exert the same action and effect.
Microencapsulation is performed by conventionally known isocyanate-based interfacial polymerization methods, melamine-formaline-based in-Situ polymerization methods, in-liquid curing coating methods, phase separation methods from aqueous solutions, phase separation methods from organic solvents, and melt dispersion. There are a cooling method, an aerial suspension coating method, a spray drying method, etc., which are appropriately selected according to the application. Examples of the material of the capsule include epoxy resin, urea resin, urethane resin, isocyanate resin and the like.
Further, a secondary resin film may be further provided on the surface of the microcapsules depending on the purpose to impart durability, or the surface characteristics may be modified for practical use.
The reversible thermochromic microcapsule pigment preferably has a mass ratio of inclusions: wall film of 7: 1 to 1: 1, and the mass ratio of inclusions and wall film is within the above range. , It is possible to prevent deterioration of color density and sharpness at the time of color development. More preferably, the mass ratio of inclusions: wall membrane is 6: 1 to 1: 1.

The reversible thermochromic microcapsule pigment has an average particle size of 0.01 to 50 μm, preferably 0.1 to 30 μm, and more preferably 0.5 to 20 μm.
When the average particle size of the reversible thermochromic microcapsule pigment exceeds 50 μm, dispersion stability and processability are likely to be lacking when blending into ink, paint, or resin. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to exhibit high-concentration color development.
For the measurement of the average particle size, the particle area is determined using the image analysis type particle size distribution measurement software [Manufactured by Mountech Co., Ltd., trade name: MacView], and the projected area circle equivalent diameter is determined from the area of the particle area. (Heywood diameter) is calculated and measured as the average particle size of particles corresponding to equal volume spheres based on the value.
If the particle size of all or most of the particles exceeds 0.2 μm, use a particle size distribution measuring device [Beckman Coulter Co., Ltd., trade name: Multisizer 4e] to equal volume by the Coulter method. It is also possible to measure as the average particle size of particles corresponding to spheres.
Furthermore, a laser diffraction / scattering type particle size distribution measuring device calibrated based on the numerical values measured using the above software or the measuring device by the Coulter method [manufactured by HORIBA, Ltd., trade name: LA- 300] may be used to measure the volume-based particle size and average particle size.

The above-mentioned reversible thermochromic microcapsule pigment is preferably blended in the range of 5 to 40% by mass, more preferably 10 to 40% by mass, and further preferably 15 to 35% by mass with respect to the total amount of the ink composition. .. If the blending ratio of the pigment exceeds 40% by mass, the ink ejection stability of the writing instrument containing the ink composition is lowered, and handwriting defects such as blurring and line skipping are likely to occur. On the other hand, if the blending ratio of the pigment is less than 5% by mass, it is difficult to obtain suitable discoloration property and handwriting density as a writing instrument, and it is difficult to sufficiently satisfy the discoloration function.

The water-based ink composition of the present invention contains a nonionic surfactant having a specific structure represented by the above general formula (1).
The surfactant represented by the general formula (1) is a polyoxyethylene polyoxypropylene alkyl ether type nonionic surfactant obtained by addition-polymerizing ethylene oxide and propylene oxide to a secondary alcohol, and is an ink composition. In order to reduce the surface tension, improve the wettability to writing tool members such as the pen tip and the ink flow control body, develop excellent ink ejection stability, and appropriately suppress the decrease in the surface tension of the ink composition. , It is possible to suppress bleeding and strike-through of the brush strokes formed on the paper surface without excessively increasing the permeability to the paper surface.

Specifically, as the nonionic surfactant represented by the above general formula (1) applied to the water-based ink composition of the present invention, Nippon Shokubai Co., Ltd., trade names: Softanol EP 5035, 7025, the same. Examples thereof include 7045, 7085, 9050, 90150, and 12030.

In addition, the nonionic surfactant represented by the above general formula (1). It is preferably blended in the range of 0.1 to 1% by mass, more preferably 0.2 to 0.6% by mass, based on the total amount of the ink composition. When the blending ratio of the nonionic surfactant represented by the general formula (1) is within the above range, the surface tension of the ink composition is appropriately lowered, excellent ink ejection stability is exhibited, and handwriting is caused. It is possible to obtain an ink composition capable of forming a better handwriting by suppressing handwriting defects such as line skipping and bleeding and strike-through of the handwriting on the paper surface.

Further, the ink composition is adjusted to a desired viscosity and surface tension by further adding a surfactant other than the nonionic surfactant represented by the above general formula (1) to the aqueous ink composition of the present invention. In addition to improving ink ejection stability and suppressing handwriting defects, it is possible to obtain an ink composition capable of forming better handwriting by suppressing bleeding and strike-through of handwriting on the paper surface.

Examples of the surfactant other than the nonionic surfactant represented by the general formula (1) include a phosphate ester-based surfactant, a silicone-based surfactant, and a fluorine-based surfactant.
In particular, since the phosphoric acid ester-based surfactant has an adsorptive power to metals, it adsorbs to a ball or a chip body, and the ink composition exhibits high lubricity. Therefore, when an ink composition containing a phosphoric acid ester-based surfactant is applied to a writing tool in the form of a ballpoint pen, the lubricity between the ball and the chip body is improved and the rotation of the ball becomes smooth. It is possible to suppress the wear of the ball receiving seat and improve the writing quality.

Examples of the phosphoric acid ester-based surfactant include a phosphoric acid monoester of a polyoxyethylene alkyl ether or a polyoxyethylene alkylaryl ether, a phosphoric acid diester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, and a phosphoric acid triester. Alternatively, derivatives thereof and the like can be exemplified, and these phosphoric acid ester-based surfactants can be used alone or in admixture of two or more.
Among these, phosphoric acid monoesters and phosphoric acid diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers are preferably used, and by adding them to the aqueous ink composition of the present invention, the ink ejection stability of the ink composition is stable. It is possible to obtain an ink composition that can further improve the properties and further suppress bleeding and strike-through of brush strokes. Further, the writing instrument to which the above ink composition is applied does not impair the pen core performance, has a good writing quality, and is also excellent in stability over time.
As the above-mentioned phosphoric acid ester-based surfactant, those having an HLB value of 5 to 16 can also be preferably used. The HLB value is a value for evaluating the hydrophilicity of a compound, and is calculated by the Griffin method or the upstream method.

Specifically, as a phosphoric acid ester-based surfactant, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade names: Prysurf A217E, A219B, A215C, A208N, A208B, AL,
Examples thereof include Toho Chemical Industry Co., Ltd., trade names: Phosphanol RB-410, RS-410, RS-610, RS-710 and the like.

The water applied to the water-based ink composition of the present invention is not particularly limited, and for example, tap water, ion-exchanged water, ultrafiltered water, distilled water and the like are used.

Further, the aqueous ink composition of the present invention contains, if necessary, a constitutional material such as kaolin, talc, mica, clay, bentonite, calcium carbonate, aluminum hydroxide, sericite, and potassium titanate, methanol, ethanol, and the like. Alcohols or glycols such as 1-propanol, 2-propanol, butanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, glycerin, diglycerin, and polyglycerin, Resin particles composed of polyolefin resin, acrylic resin, nylon resin, silicone resin, urethane resin, fluorine resin, etc., acrylic resin, urethane resin, styrene-butadiene copolymer resin, alkyd resin, sulfoamide resin, maleic acid resin, polyacetic acid. Vinyl resin, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, copolymer of styrene and maleic acid ester, styrene-acrylonitrile copolymer resin, cyanate-modified polyalkylene glycol, ester gum, xylene resin, Fixation of urea resin, urea aldehyde resin, phenol resin, alkylphenol resin, terpenphenol resin, rosin resin and hydrogenated compound thereof, rosin phenol resin, polyvinyl alkyl ether resin, polyamide resin, polyolefin resin, polyester resin, cyclohexanone resin, etc. Agents, pH adjusters, benzotriazole, tolyltriazole, dicyclohexylammonium nitrate, diisopropylammonium nitrate, and rust preventives such as saponin, various surfactants such as urea, anion type, cationic type, nonionic type, and both sexes, polyvinyl Pigment dispersants consisting of alcohols, water-soluble resins such as polyvinylpyrrolidone, reduced or non-reduced starch hydrolysates, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbit, mannit, and pyrrolin. Additives such as wetting agents such as sodium acid, chelating agents such as ethylenediamine tetraacetic acid and salts thereof, preservatives, bubble inhibitors, and bubble absorbers can also be applied.

The water-based ink composition of the present invention can be produced by any conventionally known method. Specifically, each of the above-mentioned components can be blended in a required amount and mixed with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill to produce the product.

The surface tension of the water-based ink composition of the present invention is preferably 30 to 60 mN / m, more preferably 30 to 50 mN / m, and even more preferably 30 to 40 mN / m. When the surface tension of the ink composition is within the above range, the permeability of the ink composition to the paper surface is not excessively increased, the bleeding and strike-through of the handwriting on the paper surface can be suppressed, and a better handwriting can be formed. .. Further, the ink composition has good wettability with respect to the writing instrument member, particularly the pen core made of synthetic resin, the ink ejection stability from the pen tip of the writing instrument is further improved, and the ink composition capable of exhibiting more excellent pen core performance. Can be a thing.
For the surface tension of the ink composition, an automatic surface tension meter [manufactured by Kyowa Interface Science Co., Ltd., trade name: DY-300] was used, and the ink composition was prepared using a platinum plate in an environment of 20 ° C. It is a value measured by the vertical plate method.

The viscosity of the aqueous ink composition of the present invention is preferably 1 to 20 mPa · s when measured at 20 ° C. under the condition of a rotation speed of 20 rpm, and more preferably 1 to 10 mPa · s. It is preferably 2 to 8 mPa · s, and more preferably 2 to 8 mPa · s. When the viscosity of the ink composition is within the above range, the ink ejection stability from the pen tip of the writing instrument is further improved, and handwriting defects such as blurring and line skipping are suppressed, and an ink capable of forming a better handwriting. It can be a composition.
The viscosity of the ink composition was measured using an EL type rotational viscometer [manufactured by Toki Sangyo Co., Ltd., trade name: RE-80L, cone type rotor: standard type (1 ° 34'x R24)]. The value.

The water-based ink composition of the present invention is a ballpoint pen, a marking pen, or a marking pen, which includes a pen tip, an ink filling mechanism, and an ink supply mechanism for supplying the ink composition to be filled in the ink filling mechanism to the pen tip. It is housed in various writing tools such as fountain pens.

The water-based ink composition of the present invention is smoothly supplied to the pen tip of a writing instrument, and excellent ink ejection stability can be exhibited regardless of the type of pen tip. The pen tip is not particularly limited, and a pen tip provided with various chips is used.
Among various tips, the ball pen tip includes, for example, a tip formed by holding a ball in a ball holding portion obtained by pressing and deforming the vicinity of the tip of a metal pipe inward from the outer surface, and cutting a metal material with a drill or the like. A chip formed by holding a ball in a ball holding portion formed by processing, a chip provided with a resin ball receiving seat inside a metal or plastic chip, or a ball held by the chip is forward by a spring body. Examples of those urged to the above can be given. The material of the ballpoint pen tip and the ball is not particularly limited, and specific examples thereof include cemented carbide, stainless steel, ruby, ceramic, resin, rubber, etc., and the diameter of the ball is 0.1 mm. Those in the range of ~ 2.0 mm are preferably used. Further, the ball may be subjected to a surface treatment such as DLC coating.
Examples of the marking pen tip include a fiber tip, a felt tip, a plastic tip, and a brush.
As the fountain pen-shaped tip (pen body), a metal plate such as a stainless steel plate or a gold alloy plate is cut into a tapered shape and bent or curved, or a pen tip shape is resin-molded. .. The pen body may be provided with a slit at the center or a ball portion at the tip.

The ink filling mechanism may be arranged behind the ink supply mechanism and directly fill the water-based ink composition, and an ink container or an ink occlusion body capable of filling the water-based ink composition may be provided. It may be provided.
When the writing instrument is configured to directly fill the water-based ink composition and a pigment is used as the colorant, the ink container is provided with a stirrer such as a stirrer ball for stirring the ink in order to facilitate the redispersion of the pigment. It is preferable to incorporate. 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, and specific examples thereof include metal, ceramic, resin, and glass.
When the writing tool is provided with an ink occlusion body capable of filling the water-based ink composition, a fiber bundle made of twisted fibers is preferably used as the ink occlusion body.

Further, the ink filling mechanism may be in the form of an ink cartridge as a detachable structure. In this case, since the writing tool body is used by replacing it with a new cartridge after the ink to be stored is used up, it is necessary to newly smoothly flow the ink composition in the ink storage part of the ink filling mechanism to the pen tip. Become. When the water-based ink composition of the present invention is applied to a writing instrument provided with an ink filling mechanism in the form of an ink cartridge, the ink composition in the ink storage unit smoothly flows to the pen tip when the ink cartridge is replaced with a new ink cartridge. It is preferably used because a writing instrument exhibits excellent ink ejection stability, is less likely to cause poor writing, and can suppress bleeding and strike-through of the writing on the paper surface to form a good writing.
As the ink cartridge, one that also serves as a shaft cylinder that constitutes a writing tool by being connected to the writing tool main body, or one that covers and protects the shaft cylinder (rear shaft) after being connected to the writing tool main body is used. In the latter case, in addition to using the ink cartridge alone, the writing instrument before use may be used by connecting the writing instrument body and the ink cartridge, or by connecting the ink cartridge in the barrel when the writing instrument user uses it. It may be any of those housed in the barrel in a disconnected state so as to start.

The ink supply mechanism is not particularly limited, but for example, (1) a mechanism provided with an ink guide core composed of a fiber bundle or the like as an ink flow rate regulator and supplying an ink composition to a pen tip, (2) a comb. A groove-shaped ink flow control body is provided, and a mechanism for supplying the ink composition to the pen tip via the groove-shaped ink flow control body. Through a pen core, which is provided with a slit-shaped ink guide groove and a ventilation groove wider than the groove, and an ink guide core for guiding ink from the ink filling mechanism to the pen tip is arranged at the axis. A mechanism for supplying the ink composition to the pen tip, (4) a mechanism for supplying the ink composition to the pen tip with an ink flow rate adjusting body by a valve mechanism, and (5) an ink container or a shaft provided with the pen tip. A mechanism for supplying the ink composition directly to the pen tip from the cylinder can be mentioned.
The material of the pen core is not particularly limited as long as it is a synthetic resin that can be injection-molded into a structure in which a large number of discs are formed into a comb groove shape. Specific examples of the synthetic resin include general-purpose polycarbonate resins, polypropylene resins, polyethylene resins, acrylonitrile-butadiene-styrene copolymer resins (ABS resins), and the like. In particular, an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) is preferably used because it has high moldability and easily obtains pen core performance.
The ink container provided with the pen tip may be an ink refill having the above-mentioned ballpoint pen tip at the tip and filling the rear end with an ink backflow preventive body made of a viscous liquid such as grease.

The writing tool accommodating the water-based ink composition of the present invention can be configured by appropriately selecting each member from the above-mentioned pen tip, ink filling mechanism, and ink supply mechanism. Considering that the material has excellent ink ejection stability and can suppress bleeding and strike-through of the brush stroke on the paper surface, the writing tool preferable in the present invention has a structure in which the ink filling mechanism directly fills the ink composition. It is a writing tool.
A writing instrument in which the ink composition is directly filled in the ink filling mechanism can form a clear handwriting due to a large amount of ink ejected, and the ink composition can be used up to the end, and the ink filling mechanism is transparent. In this case, it is preferably used because the remaining amount of ink can be visually recognized, but bleeding or strike-through is likely to occur in the handwriting on the paper surface. However, the writing instrument having the above configuration containing the water-based ink composition of the present invention has excellent ink ejection stability, is less likely to cause handwriting defects such as blurring and line skipping, and has an appropriately good surface tension of the ink composition. Therefore, it is preferably used as a writing instrument capable of suppressing bleeding and strike-through of handwriting on a paper surface and forming a good handwriting.

Further, as an ink supply mechanism, a large number of discs are arranged in parallel with a comb groove-like interval, and a slit-shaped ink guide groove that runs through the disc in the axial direction and a ventilation groove wider than the groove are provided. A writing tool provided with a pen core in which an ink guiding core for guiding ink from an ink filling mechanism to a pen tip is arranged at the axis is used as a preferable writing tool in the present invention.
In the writing tool having the above configuration, the ink flow rate from the ink filling mechanism is appropriately adjusted, and the wettability of the ink composition to be filled with respect to the pen core is appropriately adjusted, so that the ink ejection stability is improved, and further, the ink ejection stability is improved. Ink does not drip from the pen tip due to pressure changes inside the writing tool caused by repeated temperature changes and cap attachment / detachment, and the ink storage property in the pen core and the ink in the ink storage part of the ink filling mechanism It is suitably used as a writing tool having excellent recoverability and good pen core performance.

A writing tool whose pen tip is a ballpoint pen tip is used as a preferable writing tool in the present invention. In general, a ballpoint pen tip has a poor capillary force of the tip itself and a low ink inducing force to the pen tip, so that ink ejection stability tends to be an issue. It is difficult to obtain discharge stability. However, the writing tool having the above configuration containing the water-based ink composition of the present invention has good wettability to the writing tool member of the ink composition, so that it is excellent in ink ejection stability and causes handwriting defects such as blurring and line skipping. It is preferably used as a writing tool that becomes difficult and can form a good handwriting by suppressing bleeding and strike-through of the handwriting on the paper surface. Further, when a metal pipe is used for the ballpoint pen tip, it is preferable to dispose a core in the tip to increase the capillary force inside the tip, and it is possible to further improve the ink ejection stability. can.

A writing instrument equipped with a pen tip, an ink filling mechanism, and an ink supply mechanism is provided with a cap that is attached so as to cover the pen tip, or a pen tip that allows the pen tip to appear and disappear from the writing instrument body (shaft cylinder). It is preferable to provide a haunting mechanism, which can prevent the pen tip from becoming dry and unable to write, and the pen tip from being contaminated or damaged.
The pen tip infestation mechanism is as follows: (1) An operating portion (clip) that can move in the front-rear direction from the rear side wall of the barrel is projected outward in the radial direction, and the operating portion is slid forward to operate the pen of the writing tool. Side slide type infestation mechanism where the tip is infested, (2) Rear end knock type infestation mechanism in which the pen tip is infested by pressing the operation unit provided at the rear end of the shaft cylinder forward, (3) Outer surface of the side wall of the shaft cylinder A side knock type infestation mechanism in which the pen tip appears and disappears by pressing the more protruding operation part inward in the radial direction, and (4) a rotary type in which the pen tip appears and disappears by rotating the operation part at the rear of the barrel. Haunting mechanism can be mentioned.

A preferred writing tool in the present invention is a writing tool provided with a cap (cap type writing tool), and more preferably, an ink supply mechanism is provided in which a large number of discs are arranged in parallel with a comb groove-like interval, and the discs are used as axes. A pen core having a slit-shaped ink guide groove penetrating in the direction and a ventilation groove wider than the groove, and an ink guide core for guiding ink from the ink filling mechanism to the pen tip is arranged at the axis. It is a writing tool with a cap added to the provided writing tool. Generally, a writing instrument containing a water-based ink composition tends to cause writing defects because the pen tip dries easily, and a cap is provided so as to cover the pen tip for the purpose of preventing the pen tip from drying. When the pressure inside the writing instrument is repeatedly changed due to the attachment / detachment of the writing instrument, the ink easily leaks from the pen tip (the ink easily drops off), and in particular, the writing instrument provided with the pen core has a problem that the ink easily drops off. However, in the writing instrument having the above configuration containing the water-based ink composition of the present invention, the wettability of the contained ink composition with respect to the pen core is appropriately adjusted, so that the inside of the writing instrument caused by repeated attachment and detachment of the cap. It is preferably used because the ink does not easily drop from the pen tip against a change in pressure and has good pen core performance.

As a writing tool accommodating the water-based ink composition of the present invention, the ink filling mechanism has a configuration in which the ink composition is directly filled, and the ink supply mechanism has a large number of discs arranged in parallel with a comb groove-like interval. A slit-shaped ink guide groove that runs through the disk in the axial direction and a ventilation groove wider than the groove are provided, and an ink guide core for guiding ink from the ink filling mechanism to the pen tip is provided at the axis. A writing tool having an arranged pen core and a ballpoint pen tip as a pen tip is a more preferable writing tool in the present invention, has excellent ink ejection stability, suppresses bleeding and strike-through of brush marks on a paper surface, and further. It is more preferably used as a ballpoint pen that can form a good ink stroke and has excellent pen core performance.
Further, a cap-type writing instrument in which a cap is attached so as to cover the pen tip of the writing instrument having the above configuration is used as a more preferable writing instrument in the present invention, has excellent ink ejection stability, and suppresses bleeding and strike-through of the writing instrument on the paper surface. In addition to being able to form even better brush strokes, it has excellent pen core performance, and it is practical that the ink does not easily drip from the pen tip due to pressure changes inside the writing instrument, and the pen tip does not dry easily. It is more preferably used as a writing instrument.

Examples are shown below, but the present invention is not limited thereto. In addition, the part in an Example shows a mass part.

Example 1
Preparation of Aqueous Ink Composition The following materials were blended in the following amounts and stirred and mixed at room temperature for 1 hour to prepare an aqueous ink composition.
・ 40.0 parts of black dye solution [Manufactured by Orient Chemical Industries Co., Ltd., trade name: Water Black 191-L (solid content: 15%)]
-Nonion-based surfactant A 0.1 part [Manufactured by Nippon Shokubai Co., Ltd., trade name: Softanol EP 12030]
-Preservative 0.3 parts [manufactured by Lonza Japan Co., Ltd., product name: Proxel XL-2 (S)]
-Diethylene glycol 5.0 parts-Phosphate ester 0.5 parts [Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf AL]
・ Triethanolamine 0.5 part ・ Water 53.6 part

Table 1 below shows the compositions of the water-based ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4.
The water-based ink compositions of Examples 2 to 7 and Comparative Examples 1 to 4 were prepared by changing the types and amounts of the materials to be blended with respect to Example 1 as shown in Table 1.

The contents of the materials in the table will be explained along with the note numbers.
(1) Black dye solution [manufactured by Orient Chemical Industries Co., Ltd., trade name: Water Black 191-L (solid content: 15%)]
(2) Blue dye solution [Manufactured by Hodogaya Chemical Co., Ltd., trade name: Brilliant Blue FCF (solid content: 35%)]
(3) Blue pigment dispersion [manufactured by Sanyo Dye Co., Ltd., trade name: Sandye Super Blue GLL-E (solid content: 24%)]
(4) Nonionic surfactant A
[Manufactured by Nippon Shokubai Co., Ltd., trade name: Softanol EP 12030]
(5) Nonionic surfactant B
[Manufactured by Nippon Shokubai Co., Ltd., trade name: Softanol EP 7085]
(6) Nonionic surfactant C
[Manufactured by Nikko Chemicals Co., Ltd., trade name: NIKKOL NP-20]
(7) Nonionic surfactant D
[Manufactured by Nikko Chemicals Co., Ltd., trade name: NIKKOL PBC-34]
(8) Fluorine-based surfactant [manufactured by AGC Seimi Chemical Co., Ltd., trade name: Surflon S-111N]
(9) Preservative [manufactured by Lonza Japan Co., Ltd., trade name: Proxel XL-2 (S)]
(10) Phosphate ester [Manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf AL]

Surface Tension Measurement For each water-based ink composition prepared in Examples 1 to 7 and Comparative Examples 1 to 4, an automatic surface tension meter [manufactured by Kyowa Interface Science Co., Ltd., trade name: DY-300] was used. The surface tension was measured by the vertical plate method using a platinum plate in a room temperature (20 ° C.) environment.

Viscosity measurement For each water-based ink composition prepared in Examples 1 to 7 and Comparative Examples 1 to 4, an EL type rotational viscometer [manufactured by Toki Sangyo Co., Ltd., trade name: RE-80L, cone type rotor: A standard type (1 ° 34'x R24)] was used to measure the viscosity under the condition of a rotation speed of 20 rpm in an environment of room temperature (20 ° C.).

Preparation of Writing Tools Each water-based ink composition prepared in Examples 1 to 7 and Comparative Examples 1 to 4 has a writing tip in the form of a ballpoint pen, further includes a pen core, and further inks directly on the ink filling mechanism. Fill 0.5 g of the ink storage part of the ink filling mechanism of the writing tool [manufactured by Pilot Corporation, trade name: Hi-Tech Point V5 Grip (LHGN-20V5)] filled with the composition, and attach the cap. A writing tool was made. The pen core of the writing instrument was manufactured by injection molding an ABS resin material.

Pen core performance test Each writing tool containing each of the water-based ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4 is held with the pen tip facing downward, and is held at 0 ° C. for 1 hour with the cap attached. After leaving it to stand, when the cap is removed and the pen tip is heated to 30 ° C with the pen tip facing down, the state of ink flowing into the comb groove of the pen core and the presence or absence of ink dripping from the pen tip are checked. Observed. Further, when the pen core was cooled to 0 ° C. again, the state of ink recovery from the comb groove portion of the pen core to the ink storage portion of the ink filling mechanism was observed. The pen core performance was evaluated based on the following criteria based on the ink inflow state and the recovery state of the writing tool.
A: The ink smoothly flowed into the comb groove of the pen core, and no dripping occurred. In addition, all the ink in the pen core was recovered satisfactorily.
B: The inflow of ink into the comb groove of the pen core was irregular, and the ink dropped. Alternatively, the ink in the pen core was not recovered and remained in the comb groove.

Written test Using each writing instrument containing each of the water-based ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4, handwritten on a test paper at room temperature (20 ° C.), 12 pieces per line. I wrote the spiral circle of No. 3 in a row, and then wrote the letters "Small". As the test paper, a writing paper conforming to the old JIS P3201 was used.

Evaluation of Ink Discharge Stability The round handwriting formed in the above writing test was visually confirmed, and the ink ejection stability was evaluated from the state of the handwriting according to the following criteria.
A: Good handwriting was obtained with no blurring or line skipping.
B: Some blurring and line skipping were confirmed in the handwriting, but it was at a level where there was no problem in practical use.
C: Many blurs and line skips were confirmed in the handwriting, and good handwriting could not be obtained.

Evaluation of bleeding / strike-through property With respect to the handwriting of the characters "Komoro" formed in the above writing test, the presence or absence of bleeding and the presence or absence of ink strike-through on the back surface of the paper on which the handwriting was formed were visually confirmed and described below. The bleeding / strike-through property was evaluated based on the criteria.
A: Good handwriting was obtained without bleeding or strike-through.
B: Slight bleeding and strike-through were confirmed, but there was no problem in practical use.
C: Bleeding and strike-through were confirmed, and good handwriting was not obtained.

Table 2 below shows the surface tension measurement, viscosity measurement, pen core performance test, and writing test (ink ejection stability) of each of the aqueous ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4. And the evaluation of bleeding / strike-through property) are shown.

Claims (8)

A water-based ink composition for writing utensils, which comprises at least a colorant, water, and a nonionic surfactant represented by the following general formula (1).

(In the formula, m represents an integer of 0 to 11, n represents an integer of 0 to 11, and m + n = 9 to 11. Further, x is the average number of moles of oxyethylene groups added, and is 1 to 20. , Y is the average number of moles of oxypropylene groups added, and indicates the number of 1 to 20.) The water-based ink composition for writing tools according to claim 1, wherein the nonionic surfactant is added in the range of 0.1 to 1% by mass in the total amount of the water-based ink composition. The water-based ink composition for writing tools according to claim 1 or 2, wherein the surface tension is 30 to 60 mN / m. The water-based ink composition for writing tools according to any one of claims 1 to 3, wherein the viscosity at a rotation speed of 20 rpm by an EL type rotational viscometer at 20 ° C. is 1 to 20 mPa · s. A writing tool containing the water-based ink composition for writing tools according to any one of claims 1 to 4. The writing tool includes a pen tip, an ink filling mechanism, and an ink supply mechanism, and the ink filling mechanism is directly filled with the writing tool water-based ink composition. A slit-shaped ink guide groove that runs through the disk in the axial direction and a ventilation groove that is wider than the groove are provided, and the ink is guided from the ink filling mechanism to the pen tip at the axis. The writing tool according to claim 5, which is a direct-liquid writing tool provided with a pen core in which an ink guide core is arranged. The writing tool according to claim 6, wherein the pen tip is a ballpoint pen tip. The writing tool according to claim 6 or 7, wherein the writing tool includes a cap.