JP2007297514A - Water-based ink composition for ballpoint pen, ballpoint pen refill containing the same and ballpoint pen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based ink composition for ballpoint pen effective for preventing the drooling and dropping of the ink from a ballpoint tip and having good dry resistance and excellent writing performance, and to provide a ballpoint pen refill containing the water-based ink composition and a ballpoint pen. <P>SOLUTION: The water-based ink composition for ballpoint pen contains water, a colorant, a water-soluble organic solvent and a polyester resin and has viscosity of 1-20 mPa s and a shear-thinning index of 0.9-1.0. The invention further provides a ballpoint pen refill containing the ink composition and a ballpoint pen. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water-based ink composition for ballpoint pens, a ballpoint pen refill incorporating the same, and a ballpoint pen. More specifically, it has dry-up resistance (cap-off performance) that suppresses the occurrence of shading and inability to write even when the nib is exposed to the outside air for a long time, and also prevents dripping The present invention relates to an excellent aqueous ink composition for ballpoint pens, a ballpoint pen refill incorporating the same, and a ballpoint pen.

2. Description of the Related Art Conventionally, many ballpoint pen refills that include water-based ink for ballpoint pens directly in an ink storage tube and have an ink backflow preventer at the rear end of the ink, and ballpoint pens that contain the ballpoint pen refill in a shaft tube have been on the market. Among them, a so-called retractable ballpoint pen that does not require a cap can prevent the ink from dripping to some extent if the ink contained in the pen is relatively high in viscosity. Become. Further, even a ballpoint pen equipped with a cap, when low viscosity ink is used, it tends to sag when left with the cap removed.
The water-based ink for a ballpoint pen is important for drying resistance in a state where the pen tip is exposed, and an attempt has been made to increase the amount of urea and / or its derivative as a pen tip drying inhibitor (see, for example, Patent Document 1).
However, since urea and / or urea derivatives exhibit high water absorption performance and express dry resistance, when inks containing these compounds in excess are left under high-humidity conditions, water is locally absorbed at the nib portion. Will be absorbed. Therefore, when such an ink is applied to a ballpoint pen, the ink viscosity of the pen tip portion decreases due to moisture absorption, and the ink droops in the pen tip portion, or the “dropping” phenomenon in which the collected ink falls. Will occur.
Japanese Patent Publication No. 5-54875

  The present invention solves the above-described problems, that is, provides a water-based ink composition for ballpoint pens that satisfies the contradictory functions of sagging and drying resistance, and has excellent writing performance, and a ballpoint pen refill and ballpoint pen incorporating the same. It is something to try.

The present invention comprises at least water, a colorant, a water-soluble organic solvent, and a polyester resin, has a viscosity in the range of 1 to 20 mPa · s, and a shear thinning index of 0.9 to 1. A water-based ink composition for ballpoint pens in the range of 0.0 is a requirement.
Furthermore, the polyester resin is contained in the ink composition in the range of 0.5 to 5% by weight, and the colorant is a dye.
Furthermore, the water-based ink composition for a ballpoint pen is incorporated in an ink containing tube in which a ballpoint pen chip holding a ball is attached directly or via a relay member, and an ink backflow prevention body is disposed on the rear end surface of the ink composition. A ballpoint pen refill provided, the ballpoint pen refill is accommodated in a shaft cylinder, and a ballpoint pen provided with a cap, or the ballpoint pen refill is accommodated in the shaft cylinder, and the pendulum is configured so that the ballpoint pen tip can be projected and retracted from the tip hole A ballpoint pen is required.

  INDUSTRIAL APPLICABILITY The present invention can provide a water-based ink composition for ballpoint pens that can prevent ink from dripping or dripping from a ballpoint pen tip and has excellent drying performance, a ballpoint pen refill, and a ballpoint pen that incorporates the same.

The water-soluble polyester resin used in the present invention is stably present in the ink and is excellent in sag prevention performance.
As for drying resistance, the polyester resin at the tip of the pen forms a coating at the tip of the ballpoint pen tip to suppress ink evaporation, and the coating is destroyed by the impact of writing and the ink output is recovered. Is done.
As the polyester resin, trade name: Plus Coat Z-221, Plus Coat Z-446, Plus Coat Z-561, etc., manufactured by Kyodo Chemical Industry Co., Ltd. can be used.

  The said polyester resin is mix | blended in 0.5-5 weight% with respect to the ink composition whole quantity, Preferably it is 1-3 weight%. If the amount is less than 0.5% by weight, it is difficult to obtain a drooping prevention effect. If the amount exceeds 5% by weight, the viscosity of the ink increases, which may cause crying or blurring, and hinder followability. Furthermore, drying resistance may be deteriorated.

As the colorant, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are exemplified below.
As an acid dye,
New coccin (CI. 16255),
Tartrazine (C.I. 19140),
Acid Blue Black 10B (C.I. 20470),
Guinea Green (C.I.42085),
Brilliant blue FCF (C.I.42090),
Acid Violet 6BN (C.I. 43525),
Soluble Blue (C.I. 42755),
Naphthalene green (C.I. 44025),
Eosin (C.I. 45380),
Phloxin (C.I. 45410),
Erythrosine (C.I. 45430),
Nigrosine (C.I. 50420),
Acid flavin (C.I. 56205) or the like is used.

As basic dye,
Chrysoidine (C.I. 11270),
Methyl violet FN (C.I. 42535),
Crystal violet (C.I. 42555),
Malachite green (C.I. 42000),
Victoria Blue FB (C.I. 44045),
Rhodamine B (C.I. 45170),
Acridine orange NS (C.I. 46005),
Methylene blue B (C.I. 52015) or the like is used.

As a direct dye,
Congo Red (C.I. 22120),
Direct Sky Blue 5B (C.I. 24400),
Violet BB (C.I. 27905),
Direct deep black EX (CI 30235),
Caillas Black G Conch (C.I. 35225),
Direct Fast Black G (C.I. 35255),
Phthalocyanine blue (C.I. 74180) or the like is used.
When a dye is used as the colorant, dry-up is significant in a system applied to a knock-type ballpoint pen that does not require a cap, and the dry-up resistance is an important requirement.

Examples of the pigment include inorganic pigments such as carbon black and ultramarine, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water dispersion finely and stably dispersed in an aqueous medium in advance using a surfactant or resin. Pigment products and the like are used. I. Pigment Blue 15: 3B [Product name: Sandy Super Blue GLL, pigment content 24%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Red 146 [Product name: Sandye Super Pink FBL, pigment content 21.5%, manufactured by Sanyo Dye Co., Ltd.]
C. I. Pigment Yellow 81 [Product name: TC Yellow FG, pigment content about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Red 220/166 [Product name: TC Red FG, pigment content of about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.].
In addition, as a water-dispersed pigment using a water-soluble resin,
C. I. Pigment Black 7 (trade name: WA color Black A25, pigment content 15%, manufactured by Dainichi Seika Kogyo Co., Ltd.),
C. I. Pigment Green 7 [trade name: WA-S color Green, pigment content 8%, manufactured by Dainichi Seika Kogyo Co., Ltd.]
C. I. Pigment Violet 23 [trade name: Micropigmo WMVT-5, pigment content 20%, manufactured by Orient Chemical Co., Ltd.]
C. I. Pigment Yellow 83 [trade name: Emacol NS Yellow 4618, pigment content 30%, manufactured by Sanyo Color Co., Ltd.].

As fluorescent pigments, synthetic resin fine particle fluorescent pigments in which various fluorescent dyes are formed into a solid solution in a resin matrix can be used. Other examples include metallic luster pigments, phosphorescent pigments, white pigments such as titanium dioxide, silica, and calcium carbonate, capsule pigments encapsulating a reversible thermochromic composition, capsule pigments encapsulating perfume and perfume.
Examples of the metallic luster pigment include metal powders such as aluminum and brass, natural mica, synthetic mica, glass pieces, alumina, and pearl pigments in which the surface of a transparent film piece is coated with a metal oxide such as titanium oxide, metal Examples thereof include those obtained by finely cutting a metallic glossy film piece provided with a transparent or colored transparent film on one side or both sides of the deposited film, and those obtained by finely cutting an iris film in which a plurality of transparent resin layers are laminated.
In addition, when using metal powders, such as said aluminum and brass, what coat | covered the surface of the said metal powder with transparent resin or colored transparent resin is used suitably, and it is excellent in stability in an ink composition.

Further, when a pigment is used as the colorant, a pigment dispersant can be added as necessary.
Examples of the pigment dispersant include surfactants such as anion and nonion, anionic polymers such as polyacrylic acid and styreneacrylic acid, and nonionic polymers such as polyvinylpyrrolidone and polyvinyl alcohol.

Examples of the water-soluble organic solvent include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, hexylene glycol, 1,3-butanediol, and neoprene. Glycol, polyethylene glycol, propylene glycol, butylene glycol, 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 monomethyl ether, propylene glycol monoether Ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, N- methyl-2-pyrrolidone.
The water-soluble organic solvent can be used alone or in combination of two or more.

In addition to the above components, alkalis such as alkyd resin, acrylic resin, styrene maleic acid copolymer, cellulose derivative, polyvinyl pyrrolidone, polyvinyl alcohol, dextrin, λ-carrageenan, methylcellulose, carboxymethylcellulose, and carboxymethylcellulose are used in a category that does not interfere with drying resistance. One or more water-soluble polymers such as metal salts can be added.
In addition, a pH adjuster, a rust inhibitor, an antiseptic or an antifungal agent, a lubricant, and a wetting agent can be added as necessary.
Examples of the pH adjusting agent include inorganic salts such as sodium carbonate, sodium phosphate, sodium hydroxide and sodium acetate, and organic basic compounds such as water-soluble amine compounds such as triethanolamine and diethanolamine.
Examples of the rust inhibitor include benzotriazole and derivatives thereof, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, ethylenediaminetetraacetate, saponin, and dialkylthiourea.
Examples of the preservative or antifungal agent include carboxylic acid, sodium salt of 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2, 3, 5, 6 -Tetrachloro-4- (methylsulfonyl) pyridine and the like.
Examples of the lubricant include higher fatty acids such as oleic acid, nonionic surfactants having a long chain alkyl group, polyether-modified silicone oil, thiophosphite tri (alkoxycarbonylmethyl ester) and thiophosphite tri (alkoxycarbonylethyl). Esters), phosphoric acid monoesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, phosphoric acid diesters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, or metals thereof Examples include salts, ammonium salts, amine salts, alkanolamine salts, and the like.
Examples of the wetting agent include urea, nonionic surfactant, sorbit, mannitol, sucrose, glucose, reduced starch hydrolyzate, sodium pyrophosphate and the like.
In addition, an antifoaming agent such as a fluorine-based surfactant that improves the permeability of the solvent, a nonion, an anion, a cationic surfactant, or dimethylpolysiloxane may be added.

  When the ink composition is directly incorporated in the ink containing tube or the shaft tube and used for a ballpoint pen of a type in which an ink backflow prevention body is disposed on the rear end surface of the ink composition, gas is mixed in the ink. As the gas gathers over time, bubbles are generated, which adversely affects the ink discharge during writing, and if there are bubbles at the tip of the writing, there is a possibility that writing becomes impossible, so ascorbic acid, ascorbic acid derivatives, erythorbic acid , Ersorbic acid derivative, α-tocopherol, catechin, catechin derivative, synthetic polyphenol, kojic acid, alkylhydroxylamine, oxime derivative, α-glucosylrutin, phosphonate, phosphinate, sulfite, sulfoxylate, dithionite Salt, thiosulfate, thiourea dioxide, formamidinesulfinic acid, glutathione, etc. It is preferable to add bubbles to chemically remove bubbles.

The aqueous ink composition for ballpoint pens of the present invention contains a known shear thinning agent, for example, xanthan gum, welan gum, organic acid-modified heteropolysaccharide of glucose and galactose, which is soluble or dispersible in water. Succinoglycan (average molecular weight of about 100 to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, methacrylic acid alkyl ester as a main component and a molecular weight of 100,000 to 150,000 Polymer, glucomannan, thickening polysaccharide with gelling ability extracted from seaweed such as agar and carrageenin, benzylidene sorbitol and benzylidene xylitol or their derivatives, crosslinkable acrylic acid polymer, inorganic fine particles, polyglycerin fatty acid ester , Polyoxye Lensorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene castor oil, polyoxyethylene lanolin, lanolin alcohol, beeswax derivative, polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene alkyl phenyl ether, fatty acid amide, etc. Nonionic surfactants having an HLB value of 8 to 12, salts of dialkyl or dialkenylsulfosuccinic acid and the like can be exemplified, and they can be used alone or in combination.
Furthermore, a mixture of N-alkyl-2-pyrrolidone and an anionic surfactant, a mixture of polyvinyl alcohol and an acrylic resin can also be used.
Ink shear thinning is a rheological property that has a high viscosity and is difficult to flow in a static state or when stress is low, and it exhibits low fluidity and good fluidity when stress increases. It means liquidity called pseudo plasticity. Therefore, the ink composition is temporarily destroyed in the three-dimensional structure under high shear stress at the time of writing and the viscosity of the ink is lowered, and the ink at the tip of the writing becomes a low-viscosity ink suitable for writing and transferred to the paper surface. The When not writing, the viscosity of the ink becomes high, so that leakage of the ink can be prevented, and separation and backflow of the ink can be prevented. Also, the ink physical properties can be kept stable over time.

As the viscosity characteristics of the ink of the present invention, the viscosity (20 ° C.) measured with a viscometer is in the range of 1 to 20 mPa · s, and the shear thinning index [shear stress value (T) and shear rate by viscometer] (J) The empirical formula (T = Kj ^n, where K is a calculated constant) derived from rheological measurement of the value is 0.9 to 1. 0, preferably in the range of 0.91 to 0.99.
When the viscosity exceeds 20 mPa · s, it is difficult to satisfy the ink following ability by writing, and the handwriting when writing at high speed is likely to be blurred.
When the shear thinning index is less than 0.9, the writing feeling is inferior and the ink hardly transfers to the ball at the initial writing.
Furthermore, the handwriting with ink having a shear thinning index of less than 0.9 is difficult to dry, and tends to be transferred to a blank portion of the writing surface and contaminated by finger touch or rubbing between papers.
By satisfying the above-mentioned viscosity and shear thinning index, in addition to satisfying the drooping and drying resistance, it is possible to satisfy the writing performance, that is, the writing feeling, initial writing, the drying property of the handwriting and the formation of a good handwriting. .

The structure and shape of the ballpoint pen itself filled with the water-based ink composition for the ballpoint pen of the present invention are not particularly limited. For example, the ink composition is incorporated in an ink containing tube equipped with a ballpoint pen tip, and the ink end face is further provided. A ballpoint pen containing a ballpoint pen refill that is in close contact with the ink backflow prevention body, and the ink composition is built into the shaft cylinder equipped with the ballpoint pen tip, and an ink backflow prevention body for backflow prevention is provided on the ink end face. An example is a ballpoint pen that is in contact. The ballpoint pen has a cap.
In addition, the ink composition is built in the ink containing tube equipped with the ballpoint pen tip, and the ballpoint pen refill with the ink backflow preventer placed on the end face of the ink is housed in the shaft cylinder, knock type, rotary type, slide A retractable ballpoint pen that is configured to allow the ballpoint pen tip to protrude and retract from the tip hole of the shaft cylinder, which includes a retractable mechanism such as an expression.

The ball-point pen tip is formed, for example, by cutting a metal to form a ball receiving seat and an ink lead-out portion inside, and providing a plurality of inward protruding portions on the inner surface near the tip of a metal pipe by pressing deformation from the outer surface. It is possible to apply an ink outflow gap extending radially outward from the central portion between the inwardly protruding portions, and the tip, especially the chip formed by pressing deformation, has a comparative contact area with the rear end of the ball. It is small and can give a smooth writing feeling with a low writing pressure.
The ball held by the ballpoint pen tip is 0.1 to 2.0 mm in outer diameter of cemented carbide, stainless steel, ruby, ceramic, etc., preferably 0.3 to 1.5 mm, more preferably 0.4 to A 1.0 mm ball is effective, and the moving distance in the radial direction between the inner diameter of the ball holding portion of the chip and the ball is in the range of 10 to 50 μm, and the moving distance in the axial direction of the ball is in the range of 10 to 30 μm. preferable.
The ballpoint pen tip is provided with a resilient member for projecting the rear end of the ball forward in the tip. When not writing, the ball is pressed against the inner edge of the tip of the tip to bring it into close contact, and when writing, it is It is preferable that the ball is retracted so that ink can flow out, and ink leakage when not in use can be suppressed.
Examples of the elastic member include a metal thin wire spring, a member provided with a straight portion (rod portion) at one end of the spring, a linear plastic processed body, and the like, and can be pressed by an elastic force of 10 to 40 g. Applied.

The ink storage tube connected to the ballpoint pen tip directly or via a connecting member is a general-purpose cylindrical molded member, for example, a molded member made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, etc. It is preferably used in terms of productivity.
Furthermore, by using a transparent, colored transparent, or translucent molded body as the ink containing tube, the ink color, the remaining amount of ink, and the like can be confirmed.

An ink backflow preventer is filled at the rear end of the ink stored in the ink storage tube.
The ink backflow preventer comprises a non-volatile liquid and / or a hardly volatile liquid (base oil).
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, poly Ether-modified silicone oil, fatty acid-modified silicone oil and the like can be mentioned, and one kind or two or more kinds 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.
Polybutene or silicone oil is preferably used as the base oil of the ink backflow preventer, and fatty acid amide or silica is preferably used as the thickener.
A resin solid stopper can be used in combination with the ink backflow preventer.

Examples will be described below, but the present invention is not limited to these examples. The composition of the water base ink for ball-point pens of Examples and Comparative Examples, viscosity, and shear thinning index are shown in the following table.
In addition, the numerical value of a composition in a table | surface shows a weight part.
The ink viscosity of each Example and Comparative Example was measured at 60 rpm using a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., using BL adapter) at 20 ° C.
The shear thinning index (n) of each Example and Comparative Example was calculated by measuring the ink viscosity at 20 ° C. using an E-type viscometer [manufactured by Tokyo Keiki Co., Ltd.].

The contents of the raw materials in the table will be described along the note numbers.
(1) Orient Chemical Industry Co., Ltd., trade name: FISCO BLACK 886, active ingredient 15%
(2) Eisen Hodogaya Co., Ltd., C.I. I. 45410, trade name: Phloxine (3) manufactured by Sumitomo Chemical Co., Ltd., C.I. I. 42655, Product Name: Acid Blue PG
(4) Product name: Plus Coat Z-221, 20% solid content
(5) Product name: Plus Coat Z-446, solid content 25%, manufactured by Kyoyo Chemical Industry Co., Ltd.
(6) Product name: Plus Coat Z-561, solid content 25%, manufactured by Kyoyo Chemical Industry Co., Ltd.
(7) Taiyo Chemical Co., Ltd., trade name: Sankara 634
(8) Product name: Rubiscol K-30, manufactured by BASF
(9) 1,2-benzthiazolin-3-one, manufactured by Avicia Co., Ltd., trade name: Proxel XL-2
(10) Made by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL, polyoxyethylene distyrenated phenyl ether phosphoric acid monoester and diester mixture

Ballpoint refill fabrication (see Figure 1)
The ball-point refill 1 includes a ball-point pen tip 2 that rotatably holds a ball 3 having a diameter of 0.7 mm at the tip, a connection member 5 to which the ball-point pen tip 2 is fixed at the front, and the connection member 5 that opens at the tip. An ink containing tube 6 fixed to the ink container and containing an ink 61 and an ink backflow prevention body 62 therein, a tail plug 7 fixed to a rear end opening of the ink containing tube 6, and the ballpoint pen tip 2 And a resilient member 4 (coil spring) that is housed inside the connecting member 5 and biases the ball 3 forward.
As the ink 61, those described in the examples and comparative examples are used.
The ink backflow prevention body 62 is an ink backflow prevention body in which polybutene is kneaded as a base oil and fatty acid amide is kneaded as a thickener.
The resilient member 4 includes a rod portion 41 and a rear coil portion 42, and a bulging portion 43 having an outer diameter larger than the outer diameter of the coil is formed at the rear end portion of the coil portion 42.
The bulging portion 43 is locked to a locking protrusion 51 on the inner surface of the connection member 5.
The tail plug 7 is provided with ventilation holes 71 in the front and rear.

Ballpoint pen production (see Figure 2)
The ballpoint pen 8 has a clip 83 formed on the outer surface of the rear portion of the shaft cylinder 81, and the ballpoint pen refill 1 is accommodated in the shaft cylinder 81 in a rear biased state by a spring 82 (coil spring). By knocking the rear end portion (knock operation portion) forward, the ball-point pen tip 2 protrudes from the tip hole of the shaft cylinder 81 to the outside.

The following tests were performed with each of the ballpoint pens.
Suspension test Each ballpoint pen is held with the ballpoint pen tip exposed from the barrel, and left for 20 hours in an atmosphere at a temperature of 20 ° C. and a relative humidity of 90%. It was evaluated with.
Drying resistance test Each ballpoint pen is held with the ballpoint pen tip exposed from the barrel, left for 30 days in a horizontal state at a temperature of 20 ° C., and then 12 circles handwritten on JIS P3201 writing paper A in a line. The number of items that can be normally written was visually observed.
Ink stability test Each ink composition was allowed to stand at room temperature (20 ° C) and 50 ° C for 7 days, and then the state of the ink was visually observed.

The test results are shown in the following table.

The contents of the test result evaluation symbols are as follows.
Sag test ○: No ink leakage (sag) was observed.
Δ: Ink droplets are observed at the tip of the chip.
X: Large ink droplets are observed at the tip of the chip, or ink leaking from the tip of the chip is falling.
Drying resistance test ○: Writing is possible within one circle.
Δ: Can be written within one line.
X: Cannot be written within one line, or cannot be written.
Ink stability test ○: No abnormality.
X: Generation of aggregates or significant increase in viscosity is observed.

It is a longitudinal cross-sectional view of one Embodiment of the ball-point pen refill used for this invention. It is a cross-sectional explanatory drawing of the ball-point pen which accommodated the ball-point pen refill of FIG. 1 in the axial cylinder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ball-point pen refill 2 Ball-point pen tip 3 Ball 4 Repelling member 41 Rod part 42 Coil part 43 Bulging part 5 Connection member 51 Locking protrusion 6 Ink storage pipe 61 Ink 62 Ink backflow prevention body 7 Tail plug 71 Vent hole 8 Ball-point pen 81 Axis Tube 82 Spring 83 Clip

Claims (7)

  It contains at least water, a colorant, a water-soluble organic solvent, and a polyester resin, has a viscosity in the range of 1 to 20 mPa · s, and a shear thinning index of 0.9 to 1.0. A water-based ink composition for ballpoint pens.   The water-based ink composition for ballpoint pens according to claim 1, comprising the polyester resin in an amount of 0.5 to 5% by weight in the ink composition.   The aqueous ink composition for ballpoint pens according to claim 1 or 2, wherein the colorant is a dye.   The water-based ink composition for a ballpoint pen according to any one of claims 1 to 3, wherein the ballpoint pen tip holding the ball is incorporated directly or via a relay member into the ink containing tube, and the ink composition rear end surface A ballpoint pen refill with an ink backflow preventer.   The ballpoint pen tip is provided with a resilient member that bounces the rear end of the ball forward. When not writing, the ball is pressed against the inner edge of the tip to bring it into close contact, and when writing, the ball is retracted by writing pressure. 5. The ballpoint pen refill according to claim 4, wherein the ink is configured to be allowed to flow out.   6. A ballpoint pen comprising a cap and a ballpoint pen refill according to claim 4 accommodated in a shaft cylinder.   6. A retractable ballpoint pen configured to house the ballpoint pen refill according to claim 4 or 5 in a shaft tube and to allow the ballpoint pen tip to protrude and retract from a tip hole of the shaft tube.

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