JP4658255B2 - Water-based ink composition for writing instruments, ink cartridge containing the same, and writing instrument - Google Patents

Description

  The present invention relates to a water-based ink composition for writing instruments, an ink cartridge containing the same, and a writing instrument. More specifically, the present invention relates to a water-based ink composition for a writing instrument having excellent light resistance, an ink cartridge containing the same, and a writing instrument.

2. Description of the Related Art Conventionally, colorful writing instruments in which a shaft cylinder and an ink storage tube are formed of a transparent material and ink compositions of various colors are accommodated therein are widely used.
When the ink composition housed in the writing instrument is exposed to light and the colorant fades or browns, the color tone of the ink that is visible through the writing instrument changes remarkably, so that the appearance different from the initial color tone appears. The merchandise value is impaired by being visually recognized.
As a cause of color fading of the colorant, it is considered that application of a colorant or an additive that generates active oxygen species generates active oxygen species by photosensitization, and the active oxygen species causes the colorant to fade.
In order to solve the above-mentioned problems, it is conceivable to add ultraviolet absorbers such as benzophenone, salicylic acid, benzotriazole, and cyanoacrylate into the ink (for example, see Patent Documents 1 and 2). The absorbent is very poorly soluble in the medium and can be added only in a small amount, particularly when used in water-based inks. Therefore, deterioration due to active oxygen species cannot be suppressed, and thus the contained ink composition is sufficient. The effect of improving light resistance was not obtained.
JP-A 62-106971 JP 9-279080 A

  The present invention is capable of visually confirming the color tone of the ink, and the color tone of the ink visually recognized through the cartridge and the writing instrument does not deteriorate the appearance due to fading or browning, and forms a good handwriting permanently. It is an object of the present invention to provide a water-based ink composition for a writing instrument and an ink cartridge and a writing instrument incorporating the same.

The present invention is an ink composition for a writing instrument housed in an ink cartridge or writing instrument that can visually recognize the color tone of the ink from the outside, wherein the ink composition is a dye having a xanthene structure having water and a halogen group, or A water-based ink composition for a writing instrument comprising resin particles containing a dye having a xanthene structure having a halogen group and at least α-lipoic acid is a requirement.
Furthermore, it is a requirement made the previous SL α- lipoic acid containing 0.1 to 5% by weight in the total amount of the ink composition.
Furthermore, the transparent ink cartridge containing the water-based ink composition for a writing instrument, the water-based ink composition for the writing instrument is contained in a transparent shaft cylinder, and the pen is directly or via a relay member at the tip of the shaft cylinder. A writing instrument formed by fixing a tip, the water-based ink composition for a writing instrument stored in a transparent ink storage tube, and a refill formed by fixing the pen tip directly to the tip of the ink storage tube or via a relay member. A writing instrument housed in a cylinder, a water-based ink composition for the writing instrument in an ink storage part in a transparent shaft cylinder, and a synthetic resin pen core that temporarily stores ink in the ink storage part according to changes in internal and external pressure And a writing instrument having a pen tip at the tip of the pen core.

  The present invention can visually confirm the color tone of the ink in the ink cartridge and the writing instrument, and the stored ink does not fade or brown and does not impair the appearance, and can form a good handwriting permanently. A water-based ink composition for a writing instrument with high commercial value, an ink cartridge containing the ink composition, and a writing instrument can be provided.

前記染料を含む樹脂粒子は、染料を樹脂として熱可塑性樹脂粒子又は熱硬化性樹脂粒子中に含有させたもの、或いは、熱可塑性樹脂粒子又は熱硬化性樹脂粒子表面に染着させたものが挙げられる。
前記樹脂としては熱硬化性樹脂粒子が好適であり、エポキシ系樹脂、エポキシアクリレート系樹脂、キシレン系樹脂、トルエン系樹脂、グアナミン系樹脂、メラミン系樹脂、ウレタン系樹脂、フェノール系樹脂、アルキッド系樹脂、アミド系樹脂、イミド系樹脂、ポリアミドエステル系樹脂、尿素系樹脂、シリコーン系樹脂、不飽和ポリエステル系樹脂等が挙げられる。
また、前記熱硬化性樹脂のうち、グアナミン系樹脂或いはメラミン系樹脂は、含有させる染料の溶出を妨げる機能に優れているため、好適に用いられる。
前記染料を含む樹脂粒子として具体的には、黄色蛍光顔料〔シンロイヒ（株）製、商品名：ＳＦ５０１５レモンイエロー、固形分３０％〕、桃色蛍光顔料〔シンロイヒ（株）製、商品名：ＳＦ５０１７ピンク、固形分３０％〕、橙色蛍光顔料〔日本蛍光化学（株）製、商品名：ルミコールＮＫＷ−３９０４Ｅ、固形分３３．５％〕等が挙げられる。
なお、インキ組成物中に含まれる染料や染料を含む樹脂粒子の総量が１重量％以下の淡色のインキは、筆記具に収容されたインキの退色が目視により顕著であり、見栄えを著しく損なうため、本発明のα−リポ酸を適用することは重要な要件となる。
前記活性酸素種を発生させる物質を併用することにより染料や染料を含む樹脂粒子の退色を防止するために用いられるα−リポ酸は、インキ組成物全量中０．１乃至５重量％、好ましくは０．３乃至５．０重量％含有される。
０．１重量％未満では所望の効果を得ることは困難であり、又、５重量％を越えて添加しても更なる耐光性の向上は認められないので、これ以上の添加を要しない。 The α-lipoic acid used in the present invention can prevent substances that generate active oxygen species contained in the ink, for example, a dye used as a colorant and resin particles containing the dye from fading. In addition, phenols used as additives and compounds having phenolic hydroxyl groups, naphthalene derivatives, acridine derivatives, benzothiazole derivatives, benzophenone derivatives, naphthoquinone derivatives, anthraquinone derivatives, etc. generate reactive oxygen species by photosensitizing action, and the activity It is possible to prevent the oxygen species from fading the dye or the resin particles containing the dye.
The active oxygen species refers to singlet oxygen, superoxide anion radical, hydrogen peroxide, hydroxy radical, alkyl radical, hydroperoxide radical, and the like.
As for the dye, particularly, a dye having a xanthene structure having a halogen group is likely to generate active oxygen species due to photosensitization, and the dye itself is discolored so that it is difficult to maintain the initial color tone, and other dyes are used in combination. In some cases, the reactive oxygen species will act on the fading of other dyes, resulting in further fading.
Examples of the dye having a xanthene structure having a halogen group include the dyes shown below.

Examples of the resin particles containing the dye include those containing a dye as a resin in thermoplastic resin particles or thermosetting resin particles, or those dyed on the surface of the thermoplastic resin particles or thermosetting resin particles. It is done.
Thermosetting resin particles are preferable as the resin, and epoxy resin, epoxy acrylate resin, xylene resin, toluene resin, guanamine resin, melamine resin, urethane resin, phenol resin, alkyd resin. Amide resin, imide resin, polyamide ester resin, urea resin, silicone resin, unsaturated polyester resin, and the like.
Of the thermosetting resins, guanamine-based resins or melamine-based resins are preferably used because they are excellent in the function of preventing elution of dyes to be contained.
Specific examples of the resin particles containing the dye include a yellow fluorescent pigment (trade name: SF5015 lemon yellow, solid content: 30%), a pink fluorescent pigment (trade name: SF5017 pink, manufactured by Sinloi Corporation). , Solid content 30%], orange fluorescent pigment [manufactured by Nippon Fluorochemicals, Inc., trade name: Lumicol NKW-3904E, solid content 33.5%] and the like.
In addition, the light-colored ink in which the total amount of the dye particles contained in the ink composition and the resin particles containing the dye is 1% by weight or less is noticeable in visual fading of the ink contained in the writing instrument, and the appearance is remarkably impaired. It is an important requirement to apply the α-lipoic acid of the present invention.
The α-lipoic acid used to prevent discoloration of the dye or the resin particles containing the dye by using the substance that generates the active oxygen species together is 0.1 to 5% by weight, preferably in the total amount of the ink composition It is contained at 0.3 to 5.0% by weight.
If it is less than 0.1% by weight, it is difficult to obtain a desired effect, and even if it is added in excess of 5% by weight, no further improvement in light resistance is observed, so no further addition is required.

As the solvent, water and, if necessary, a water-soluble organic solvent are used.
Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, and ethylene glycol monomethyl. Ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N-methyl-2- Pyrrolidone, and the like.
Specific examples of the water-based ink used in the present invention include a shear-thinning ink containing a shear-thinning agent, a cohesive ink obtained by suspending a pigment in a gentle aggregation state with a water-soluble polymer flocculant, and a viscosity of A low viscosity ink of about several mPa · s can be mentioned.

By adding a polymer flocculant in the ink, the flocculant causes a loose bridging action between pigments (resin particles containing dye), and exhibits a loose agglomeration state. Ink showing such a loose aggregation state does not cause separation of the pigment in the capillary gap between the ink occlusion body (batting) made of a fiber bundling body and the marking pen body made of a resin bundle of fibers.
Therefore, it is possible to obtain a marking pen having a storage performance equivalent to that of a marking pen filled with a dye ink by suppressing the occurrence of darkening or lightening of the handwriting by separating the pigment by standing upright or inverted.
As the water-soluble polymer flocculant, a water-soluble polymer compound is used, and examples include water-soluble polysaccharides such as tragacanth gum, guar gum, pullulan, cyclodextrin, and cellulose derivatives, polyvinyl pyrrolidone, and polyethylene oxide.
Specific examples of the cellulose derivative include methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose and the like.

By adding a shear thinning agent to the ink, ink leakage from the gap between the ball and the tip can be prevented when the ballpoint pen filling the ink is not used, or the writing tip can be faced up (upright state). When the ink is left as it is, it is possible to prevent the ink from flowing backward and to prevent the aggregation and sedimentation of the pigment.
The viscosity of the ink composition added with the shear thinning agent is 200 to 3000 mPa · s at a shear rate of 3.84 s ⁻¹ by an E-type rotational viscometer at 20 ° C., and It is preferable that the shear thinning index is 0.1 to 0.6.
The shear thinning index (n) is expressed by an empirical formula T = Kj ⁿ (K is a non-Newtonian viscosity coefficient) obtained from rheological measurement by a viscometer such as a shear stress value (T) and a shear rate value (j). It is a value calculated by fitting.
Examples of the shear thinning agent include xanthan gum, welan gum, succinoglycan (average molecular weight of about 1 to 8 million) whose constituent monosaccharide is an organic acid-modified heteropolysaccharide of glucose and galactose, alka gum, guar gum, locust bean gum and A gel having a gelling ability extracted from seaweeds such as glucomannan, agar and carrageenan, polymers having a molecular weight of 100,000 to 150,000 mainly composed of derivatives thereof, hydroxyethyl cellulose, alginic acid alkyl esters, and alkyl esters of methacrylic acid. Viscous polysaccharides, benzylidene sorbitol and benzylidene xylitol or derivatives thereof, crosslinkable acrylic acid polymer, inorganic fine particles, polyglycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester , Polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether, fatty acid amide and other nonionic surfactants having an HLB value of 8 to 12, salts of dialkyl or dialkenylsulfosuccinic acid, N-alkyl Examples thereof include a mixture of -2-pyrrolidone and an anionic surfactant, and a mixture of polyvinyl alcohol and an acrylic resin.

  Further, when the ink is incorporated into a ballpoint pen for practical use, a higher fatty acid such as oleic acid, a nonionic surfactant having a long chain alkyl group, a polyether-modified silicone oil, a thiophosphorous acid tri (alkoxycarbonylmethyl ester) And thiophosphorous acid triesters such as thiophosphorous acid tri (alkoxycarbonylethyl ester), polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether It is preferable to add a lubricant such as phosphoric acid diesters or their metal salts, ammonium salts, amine salts, alkanolamine salts and the like to impart an effect of preventing wear of the ball seat.

In addition, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin and other rust preventives, carboxylic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, dehydro as necessary Preservatives or antifungal agents such as sodium acetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, urea, nonionic surfactants, reduced or non- Reduced starch hydrolyzate, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbit, mannitol, sodium pyrophosphate and other wetting agents, antifoaming agents, dispersants, ink permeability Improved fluorosurfactant It may be used nonionic surfactants.
Moreover, an acrylic resin, a styrene maleic acid copolymer resin, polyvinyl alcohol, dextrin, etc. can also be used for the sticking property to a paper surface, or viscosity imparting if needed.

  The pH of the ink composition obtained as described above is preferably 7 to 13, and α-lipoic acid efficiently suppresses a chemical reaction that causes the active oxygen species to fade the dye or the resin particles containing the dye. be able to.

The ink is put into practical use by filling a fountain pen, a ballpoint pen, a marking pen, or a brush pen with a pen tip attached to the writing tip.
When filling a fountain pen, ink is stored directly inside the shaft tube, and a comb groove-shaped ink flow rate adjusting member or an ink flow rate adjusting member consisting of a fiber bundle is interposed between the fountain pen tip and the shaft tube. Examples include a structure in which a cartridge containing ink is housed and an ink flow rate adjusting member having a comb groove shape or a fiber bundle is interposed between a fountain pen nib.
When filling the ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited. For example, an ink occlusion body consisting of a fiber bundle housed in the shaft tube is impregnated with ink, and the pen tip (ballpoint pen tip) is filled with ink. A structure that supplies ink directly into the shaft cylinder, a structure in which an ink flow rate adjusting member composed of a comb groove-like ink flow rate or a fiber bundle is interposed between the pen point, a pen point directly or a connecting member And a structure in which a liquid stopper for preventing ink and backflow is accommodated in a shaft cylinder connected via a pipe, and a structure in which a ballpoint pen refill in which a liquid stopper for preventing ink and backflow is accommodated in an ink accommodating tube is accommodated in the shaft cylinder.
When filling the marking pen, the structure and shape of the marking pen itself are not particularly limited. For example, the marking pen itself is composed of a fiber bundle that has a pen tip (marking pen tip) attached to the writing tip and accommodated inside the shaft tube. A structure in which ink is impregnated into the ink occlusion body and ink is supplied to the pen tip, ink is stored directly inside the shaft cylinder, and an ink flow rate adjusting member comprising a comb groove-like ink flow rate adjusting member or a fiber bundle is connected to the pen tip. Examples include a marking pen having a structure in which the ink is directly interposed inside the shaft cylinder and a predetermined amount of ink is supplied to the pen tip by a valve mechanism.

Specifically, as the fountain pen type nib, a metal plate such as a stainless steel plate or a gold alloy plate is cut into a taper taper shape, bent or curved, or resin-molded into a nib shape can be applied. The fountain pen-type pen body can be provided with a slit at the center or a ball at the tip.
The ball pen tip used as the nib will be described in more detail. 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, or a metal material. A chip formed by holding a ball in a ball holding portion formed by cutting with a drill or the like, a chip provided with a resin ball receiving seat inside a metal or plastic chip, or a ball held by the chip What was urged | biased ahead with the spring body etc. can be applied.
The ball may be about 0.1 to 3 mm in diameter, such as cemented carbide, stainless steel, ruby, ceramic, resin or rubber.
In addition, the writing instrument filled with the ink of the present invention includes those provided with a rolling mechanism such as a roller at the tip of the writing for forming a handwriting by the same rolling operation as that of the ball.
The marking pen tip used as the pen tip will be described in more detail, such as fiber tip, felt tip, and plastic tip.

For the ink cartridge, the shaft cylinder, and the ink storage tube for storing ink, a transparent molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon is used.
The transparency includes colored transparency, translucency, and colored translucency, and can confirm the ink color, the ink remaining amount, and the like.
In addition, the transparent ink cartridge, the shaft cylinder, and the ink storage tube as a whole may have transparency, or may have a partially transparent portion where the remaining amount of ink can be visually recognized. .

The back end of the ink stored in the ink storage tube or the shaft tube may be filled with an ink backflow prevention body.
The ink backflow prevention body composition is composed of a non-volatile liquid or a hardly volatile liquid.
Specifically, petroleum jelly, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, Examples thereof include polyether-modified silicone oil and fatty acid-modified silicone oil, and one or more can be used in combination.

It is preferable to add a gelling agent to the nonvolatile liquid and / or the hardly volatile liquid to increase the viscosity to a suitable viscosity. The surface of the silica is hydrophobized, the surface is methylated fine particle silica, and aluminum silicate. , Swellable mica, hydrophobic thickeners such as bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, zinc stearate, tribenzylidene sorbitol, fatty acid amide, amide modified Examples include dextrin compounds such as polyethylene wax, hydrogenated castor oil, fatty acid dextrin, and cellulose compounds.
Furthermore, the liquid ink backflow prevention body composition and a solid ink backflow prevention body composition can be used in combination.

The writing instrument form of the present invention is not limited to that described above, and may be a double-headed writing instrument in which different types of pen nibs are mounted or pen nibs that lead out different colors of ink are mounted.
As the double-headed writing instrument, a partition wall is provided in the shaft cylinder, and the writing tip is fixed to the both ends of the shaft cylinder directly or via a relay member, respectively. In a writing instrument or a shaft tube, two refills are stored so that the writing tip is located at both ends of the shaft tube, and each of the two refills has a different color tone. The writing instrument which accommodates can be illustrated.

  The ink composition of an Example and a comparative example is described in the following table | surfaces. In addition, the part in a table | surface shows a weight part.

The contents of the raw materials in the table will be described along the note numbers.
(1) Eisen Hodogaya Co., Ltd., Acid Red 87, Trade name: Eosin GH 35% -L
(2) Eisen Hodogaya Co., Ltd., Acid Red 92, trade name: Phloxine (3) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL, polyoxyethylene distyrenated phenyl ether phosphate ( 4) Preservative, manufactured by Avicia Co., Ltd., trade name: Proxel XL-2
(5) Toyo Fermentation Co., Ltd., trade name: α-lipoic acid (6) Kyowa Hakko Co., Ltd., trade name: Glutathione (7) Clariant Japan, trade name: SANDUVOR 3225 DISP
(8) Product name: SANDUVOR PT21 DISP, manufactured by Clariant Japan
(9) Daiwa Kasei Co., Ltd., Acid Red 51, Product Name: Edible Red No. 3 (Erythrosin)
(10) Made by Daiwa Kasei Co., Ltd., Acid Red 94, Product Name: Edible Red No. 105 (Rose Bengal)
(11) Daiichi Kogyo Seiyaku Co., Ltd., trade name: F-6212, triethanolamine neutralized product of polyoxyethylene distyrenated phenyl ether phosphate (12) Daiichi Kogyo Seiyaku Co., Ltd., commercial product Name: Haitenol NF-13, polyoxyethylene alkylphenyl ether sulfonate (13) manufactured by Sanki Co., Ltd., trade name: Leozan (14) manufactured by Sinroihi Co., Ltd., trade name: SF5017 pink, solid content 30%
(15) Nikko Chemicals Co., Ltd., trade name: Nikkor PBC-34, polyoxyethylene polyoxypropylene cetyl ether (16) Hokuko Sangyo Co., Ltd., trade name: Hokuside R-150

Production of Ink Cartridge Each ink composition of Example 1 and Comparative Examples 1 to 4 was accommodated in a transparent cartridge container made of polyethylene, and a stopper was fixed to produce an ink cartridge.

Preparation of Ink Backflow Preventer Body In 85 parts of polybutene as a base oil, 15 parts of fatty acid amide as a thickener was added, and then kneaded with three rolls to obtain an ink backflow preventer body.

Preparation of Ballpoint Pen A ballpoint pen refill in which each of the ink compositions of Example 2 and Comparative Example 5 is fitted with a stainless steel chip holding a ball having a diameter of 0.3 mm at one end of a polypropylene pipe (inner diameter: 3.8 mm). After the ink backflow prevention body was disposed at the rear end, the ballpoint pen refill was incorporated into a shaft tube to prepare a writing instrument (water-based ballpoint pen).

Preparation of Marking Pen Each ink composition of Example 3 and Comparative Example 6 was impregnated into a fiber sizing ink occlusion body in which a polyester sliver was coated with a synthetic resin film, and accommodated in a shaft tube, and a chisel at the tip of the shaft tube A marking fiber pen was obtained by attaching a mold fiber pen body.

Production of Ink Cartridge Each ink composition of Example 4 and Comparative Example 7 was accommodated in a transparent cartridge container made of polyethylene, and a stopper was fixed to produce an ink cartridge.

Light Resistance Test The following tests were conducted using each ink cartridge and writing instrument.
Each ink cartridge and writing instrument was irradiated with light for 20 hours at an irradiation intensity of 180 W / m ² using a xenon light resistance tester (Suga tester, xenon lamp applied), and then the color tone of the ink visible through the ink cartridge and writing instrument was adjusted. Compared with the initial stage (appearance test).
Furthermore, for writing instruments, the handwriting written on the paper with the cap removed was compared with the initial (writing test).
The test results are shown in the following table.

In addition, the evaluation regarding the symbol of the test result in a table | surface is as follows.
Appearance test ○: No change was observed in the color of the ink compared to the initial stage.
X: Discoloration was seen in the ink compared with the initial stage.
Written test ○: There was no change in the color of the handwriting compared to the initial.
X: Significant discoloration was observed in the handwriting as compared with the initial stage.

Application example 1
Preparation of fountain pen-type writing instrument Ink cartridges containing the ink compositions of Example 1 and Comparative Examples 1 to 4 are temporarily stored in a transparent shaft cylinder in accordance with changes in internal and external pressures. A pen tip made of synthetic resin is housed, and a fountain pen tip is provided at the tip of the pen lead, and an ink guide lead for guiding ink from the ink storage unit to the pen tip is arranged on the pen lead. The fountain pen-type writing instrument was obtained by being housed in the ink storage section.
As a result of the appearance test and the writing test of the writing instrument, the appearance test showed no change in the color tone of the ink compared to the initial stage, and the writing test showed no change in the color tone of the handwriting compared to the initial stage.

Claims (10)

An ink composition for a writing instrument that is housed in an ink cartridge or writing instrument that can visually recognize the color tone of the ink from the outside, wherein the ink composition has water and a dye having a xanthene structure having a halogen group, or a halogen group A water-based ink composition for a writing instrument comprising resin particles containing a dye having a xanthene structure and at least α-lipoic acid. The water-based ink composition for a writing instrument according to claim 1, wherein the α-lipoic acid is contained in an amount of 0.1 to 5% by weight based on the total amount of the ink composition. A transparent ink cartridge containing the water-based ink composition for a writing instrument according to claim 1. A writing instrument comprising the water-based ink composition for a writing instrument according to claim 1 or 2 accommodated in a transparent shaft tube, and a pen tip fixed to the tip of the shaft tube directly or via a relay member. The writing instrument according to claim 4, wherein the ink occlusion body impregnated with the ink composition is accommodated in a transparent shaft cylinder. The water-based ink composition for a writing instrument according to claim 1 or 2 is accommodated in a transparent ink storage tube, and a refill formed by adhering a pen tip to the tip of the ink storage tube directly or via a relay member is formed in the transparent shaft cylinder. Writing instruments housed in The writing instrument according to claim 4 or 6, wherein the water-based ink composition for a writing instrument is stored in a direct liquid state in a shaft cylinder or an ink storage tube. 8. The writing instrument according to claim 7, wherein an ink backflow preventer is disposed at the rear end of the water-based ink composition for a writing instrument. A water-based ink composition for a writing instrument according to claim 1 or 2 and a synthetic resin pen core for temporarily storing ink in the ink storage section according to changes in internal and external pressures are accommodated in an ink storage section in a transparent shaft cylinder. A writing instrument comprising a pen tip at the tip of the pen core. The writing instrument according to claim 9, wherein a transparent ink cartridge containing ink is stored in the ink storage section.