JP4308600B2 - Water-based ballpoint pen - Google Patents

Description

The present invention relates to water of a ball-point pen. More specifically, a dye with excellent dry-up resistance (cap-off performance) and dripping prevention performance that suppresses the occurrence of blurring or inability to write due to drying of the nib for a long time to the outside air It relates to a system water of a ball-point pen.

Conventionally, a large number of ballpoint pens that contain water-based ink for ballpoint pens directly in an ink containing tube and have an ink backflow preventer at the rear end of the ink are on the market. Among them, the so-called knock-type ballpoint pen that does not require a cap can prevent the ink from dripping to some extent if the ink contained therein has a relatively high viscosity, but it tends to cause drooping if low-viscosity ink is used. Become.
In the water-based ink for ballpoint pens, cap-off performance is further important, and attempts have been made to increase the amount of urea and / or its derivative as a nib drying inhibitor (see, for example, Patent Document 1).
However, since urea and / or urea derivatives exhibit cap-off performance due to their high water-absorbing performance, inks with excessive addition of these cap-off performance-imparting agents will remain in the nib portion when left under high humidity conditions. Moisture is absorbed locally. Therefore, when such an ink is applied to a water-based 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.
In particular, when a dye is used as a colorant, drooping is significant, and it is difficult to satisfy both cap-off performance and dripping prevention performance.
Japanese Patent Publication No. 5-54875

The present invention has been made to solve the above problem, i.e., to satisfy the contradictory functions of sag and the cap off resistance, it is intended to provide an excellent water resistance ballpoint pen writing performance.

The present invention comprises a dye as at least a colorant, water, the ink composition comprising a water-soluble organic solvent, and also contains the polyurethane emulsion, the average particle size of the emulsion Ri der less 0.1 [mu] m, The viscosity measured at 100 rpm (20 ° C.) of the EM type rotational viscometer has an ink viscosity in the range of 3 to 160 mPa · s, and the shear thinning index is in the range of 0.9 to 0.99. The measured viscosity (20 ° C.) at 60 rpm of a water-based ink, B-type rotational viscometer is in the range of 1 to 20 mPa · s, and the shear thinning index is in the range of 0.9 to 0.99. A water-based ink or a non-shear thinning water-based ink having a viscosity measured at 60 rpm (20 ° C.) of a B-type rotational viscometer in the range of 1 to 20 mPa · s is used directly or inside a ballpoint pen tip. Member was charged directly to the ink reservoir tube fitted through and, tan [delta points exceeding 1 in viscoelastic properties measured ink composition rear end face (omega) is in the range of 20rad / s ≦ ω ≦ 450rad / s A water-based ballpoint pen with an ink backflow preventer. Is a requirement.
Furthermore, the polyurethane emulsion is a self-emulsifying emulsion in which the hydrophilic group exhibits anionic or nonionic properties, exhibits self-dispersibility in a medium, and the polyurethane emulsion is used in an ink composition in an amount of 0.1 to 5 It is necessary that the content is within the range of 0.0% by weight, and that the ball-point pen tip has a retracting mechanism stored in the shaft cylinder in a state exposed to the outside air .

The present invention is equipped with both preventive effect and a cap-off effect sagging can provide excellent water resistance ballpoint pen writing performance.

The polyurethane used in the present invention forms an emulsion in an aqueous medium.
The average particle size of the emulsion is as small as 0.1 μm or less, and it is stably present in the ink and imparts the ability to prevent dripping.
Since the polyurethane emulsion has an average particle size of 0.1 μm or less, it satisfies the stability over time. However, if it exceeds 0.1 μm, the specific gravity is so heavy that it settles and separates in the ink and satisfies the expected performance. It becomes difficult to let you.
The average particle size of the emulsion is preferably 0.01 to 0.1 μm.
Regarding the cap-off performance, it is presumed that the polyurethane emulsion forms a dry film at the tip of the pen to suppress ink evaporation, and the film is destroyed by the impact at the time of writing to recover the ink discharge.
The polyurethane emulsion is preferably a self-dispersing type to which a hydrophilic group is added in order to stably disperse in an aqueous medium.
Examples of the hydrophilic group include an anionic group or a nonionic group, and more preferably an anionic group.
When a polyurethane having a hydrophilic group that is cationic is used, the stability is poor, and precipitation may occur due to a reaction with an additive contained in the ink or an acidic dye used as a colorant. In addition, if the type is forcibly dispersed by adding an activator or the like, it is difficult to obtain a sufficient dispersion effect, and the intended particle size cannot be obtained.

  As the polyurethane, trade names: Superflex 130, 460, 470, 840, etc. manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. can be used.

  The oxidized polyurethane emulsion is blended in the range of 0.1 to 5.0% by weight, preferably 0.5 to 3.0% by weight, based on the total amount of the ink composition. If the amount is less than 0.1% by weight, it is difficult to obtain a drooping prevention effect. If the amount exceeds 5.0% by weight, the viscosity of the ink increases, which may cause crying or blurring, and hinder followability. Furthermore, the dry-up resistance may be deteriorated.

As the colorant, any dye that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are illustrated 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.

Moreover, various pigments can be used in combination as required.
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 are used.
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.

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, one or more water-soluble resins such as alkyd resins, acrylic resins, styrene maleic acid copolymers, cellulose derivatives, polyvinyl pyrrolidone, polyvinyl alcohol, and dextrin are added in a category that does not impair drying resistance. Alternatively, one or more wetting agents such as urea, nonionic surfactant, sorbit, mannitol, sucrose, glucose, reduced starch hydrolyzate, sodium pyrophosphate and the like can be added.
In addition, a pH adjuster, a rust preventive, a preservative or a fungicide, and a lubricant 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 metal soap, polyalkylene glycol fatty acid ester, ethylene oxide addition type cationic activator, phosphate ester activator, thiocarbamate, dimethyldithiocarbamate 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 filled into the ink containing tube and used for a ballpoint pen of the type in which an ink backflow preventer is disposed on the rear end surface of the ink composition, if the gas is mixed in the ink, the gas As bubbles are gathered to generate ink, adversely affect the ink discharge at the time of writing, and there is a risk that writing will be impossible if bubbles exist at the tip of the writing, ascorbic acid, ascorbic acid derivative, α-tocopherol, catechin, Catechin derivatives, synthetic polyphenols, kojic acid, alkylhydroxylamine, oxime derivatives, α-glucosyl rutin, phosphonates, phosphinates, sulfites, sulfoxylate, dithionite, thiosulfate, thiourea dioxide, form It is preferable to chemically remove bubbles by adding amidinesulfinic acid, glutathione, etc. .

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 composed of glucose and galactose, which is soluble or dispersible in water. Succinoglycan (average molecular weight of about 100 to 8 million), guar gum, alka gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, and methacrylic acid alkyl esters as main components of 100,000 to 15 Polymers, glucomannan, thickening polysaccharides having 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 esters, Reoxyethylene sorbitan 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 Examples thereof include nonionic surfactants having an HLB value of 8 to 12, salts of dialkyl or dialkenylsulfosuccinic acid, and the like, which 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 viscosity characteristics of the ink directly stored in the ink storage tube, the measured viscosity (20 ° C.) at 100 rpm of the EM type rotational viscometer is in the range of 3 to 160 mPa · s, and the shear thinning index [shear by viscometer N calculated by applying an empirical formula (T = Kj ^n, where K and n are calculated constants), derived from rheological measurements of stress values (T) and shear rate (j) values. Value] is a shear-thinning water-based ink selected from the range of 0.9 to 0.99, the measured viscosity at 20 rpm (20 ° C.) of a B-type rotational viscometer is in the range of 1 to 20 mPa · s, and A shear-thinning water-based ink having a shear-thinning index in the range of 0.9 to 0.99, or a measured viscosity at 20 rpm (20 ° C.) of a B-type rotational viscometer in the range of 1 to 20 mPa · s. Shear thinning water-based ink Used.

  The structure and shape of the writing instrument itself filled with the water-based ink composition for the ballpoint pen of the present invention is not particularly limited, and a conventional one can be applied, for example, ink storage in which the ink composition is filled in a shaft cylinder The ink storage tube communicates with a ballpoint pen tip with a ball attached to the tip, and a ballpoint pen with a backflow prevention body for preventing backflow is in close contact with the end surface of the ink. Examples thereof include a ballpoint pen that is housed in the shaft cylinder in a state exposed to the outside air and has a retracting mechanism such as a knock type, a rotary type, and a slide type.

The ballpoint pen tip is a conventional general-purpose tip mechanism, for example, a metal cutting machine formed with a ball receiving seat and an ink lead-out portion inside, and a plurality of inward protruding portions on the inner surface near the tip of a metal pipe. It can be applied by pressing deformation from the outer surface, and an ink outflow gap extending radially outward from the central portion can be applied between the inward protruding portions. The contact area with the edge is relatively small, and a smooth writing feeling can be given with a low writing pressure.
Balls held by the ballpoint pen tip are effectively balls having an outer diameter of 0.3 to 1.5 mm, such as cemented carbide, stainless steel, ruby, ceramic, and the like. The movable distance in the radial direction is preferably 10 to 50 μm, and the movable distance in the axial direction of the ball is preferably 10 to 30 μm.
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, and a linear plastic processed body. The elastic member can be pressed by an elastic force of 15 to 45 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 low evaporation and productivity.
Further, the ink containing tube having an inner diameter of 2.5 to 10 mm is preferably used.
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.
The ink storage tube may be accommodated in the shaft cylinder as a form of refill, or the shaft cylinder itself having a tip attached to the tip may be used as an ink storage tube, and ink may be directly filled into the shaft cylinder.

An ink backflow preventer is filled at the rear end of the ink stored in the ink storage tube.
The ink backflow preventer is a base oil composed of a conventionally known non-volatile liquid or hardly volatile liquid such as polybutene, α-olefin oligomer, silicone oil, refined mineral oil, silica, aluminum silicate, swellable mica, fatty acid amide. What added the thickeners, such as, is applied. Polybutene or silicone oil is preferably used as the base oil, and fatty acid amide or silica is preferably used as the thickener.
The ink backflow preventer used in the present invention has an ink viscosity measured at 100 rpm (20 ° C.) of an EM rotational viscometer in the range of 3 to 160 mPa · s, and a shear thinning index of 0.9. The measured viscosity at 20 rpm (20 ° C.) of a shear-thinning water-based ink in the range of ˜0.99 and a B-type rotational viscometer is in the range of 1 to 20 mPa · s, and the shear thinning index is 0.9 shear-thinning aqueous ink is in the range of to 0.99, or measuring the viscosity at 60rpm of B-type rotational viscometer (20 ° C.) is, for using the non-shear-thinning aqueous ink is in the range of 1 to 20 mPa · s in that the tanδ in viscoelasticity measurement exceeds 1 (omega) is area by the near of 20rad / s ≦ ω ≦ 450rad / s.
More specifically, the ink has a low viscosity in a stationary state, and is inferior in impact resistance as compared with a conventional shear thinning water-based ink having a shear thinning index adjusted to about 0.1 to 0.6. Therefore, ink is likely to leak out from the rear part of the ink containing tube, and writing may become impossible or the commercial value may be impaired.
Therefore, it is necessary to provide impact resistance to the ink backflow preventer disposed at the rear end of the ink to eliminate the above-described problems.
The ink backflow prevention body in which the point (ω) where tan δ in the viscoelasticity measurement exceeds 1 is in the range of 20 rad / s ≦ ω ≦ 450 rad / s exhibits viscoelasticity and exhibits an intermediate property between elastic response and viscous response. .
The viscoelasticity is measured by a rheometer vibration method. Tan δ is obtained by dividing the value of the loss elastic modulus by the value of the storage elastic modulus. When this value is low (tan δ <1), the elastic property is high. In addition, the viscosity characteristics are lowered. On the other hand, when this value is high (tan δ> 1), the elastic characteristics are low and the viscosity characteristics are high.
In the above-described viscoelasticity measurement, the region where the angular frequency (rad / s) is 20 or more is a region close to a state where an impact such as a drop is applied to the writing instrument.
Therefore, the ink backflow preventive body showing viscoelasticity with tan δ exceeding 1 at 20 rad / s can satisfy the impact resistance depending on the strength of the viscous response.
The point where tan δ exceeds 1 is 20 rad / s or more, but if it exceeds 450 rad / s, the elastic response becomes strong and the ink followability tends to be deteriorated, resulting in poor ink discharge.
Therefore, both the impact resistance and the writing performance can be satisfied by adjusting the point (ω) where tan δ of the ink backflow preventive body exceeds 1 to the range of 20 rad / s ≦ ω ≦ 450 rad / s.
The ink backflow preventer can be used in combination with a solid plug formed by resin molding.

Examples will be described below, but the present invention is not limited to these examples. The following table shows compositions and viscosities of water-based inks for ballpoint pens of Examples and Comparative Examples.
In addition, the numerical value of a composition in a table | surface shows a weight part.
The ink viscosities of Examples 1 to 5 and Comparative Examples 1 to 5 were measured at 60 ° C. using a B-type rotational viscometer (manufactured by Tokyo Keiki Co., Ltd., BL, BL adapter) at 20 ° C.
The ink viscosity of Comparative Example 6 was measured at 100 rpm using an EMD type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., RE-80R, using a standard rotor) at 20 ° C.
Example 2, 4, 5 and shear thinning index of the ink of Comparative Example 2, 4, and 5 is 0.97, the shear thinning index of the ink ratio Comparative Examples 6 was 0.3.

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) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 130, average particle size 0.02 μm, solid content 35%, hydrophilic group: anionic (5) Daiichi Kogyo Seiyaku Co., Ltd., commercial product Name: Superflex 460, average particle size 0.03 μm, solid content 38%, hydrophilic group: anionic (6) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 470, average particle size 0.05 μm, Solid content 38%, hydrophilic group: anionic (7) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex 840, average particle size 0.02 μm, solid content 27%, hydrophilic group: anionic (8 ) Product name: Sankara 634, manufactured by Taiyo Chemical Co., Ltd.
(9) Product name: Rubiscol K-30, molecular weight 40000, manufactured by BASF
(10) Made by Sanki Co., Ltd., trade name: Leozan (11) 1,2-benzthiazolin-3-one, manufactured by Avicia Co., Ltd., trade name: Proxel XL-2
(12) Phosphate ester surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Prisurf AL
(13) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Superflex E-2500, average particle size 0.96 μm, solid content 45%, hydrophilic group: anionic

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.
The ink backflow preventer was measured at 20 ° C. using a rheometer (Paar Physica, DSR4000, 2 ° cone plate (diameter 25 mm)). As a result, tan δ exceeded 1 at 100 rad / s. Met.

Preparation of water-based ballpoint pen Each ink composition was filled in a ballpoint pen refill fitted with one end of a polypropylene pipe (inner diameter: 3.8 mm) with a stainless steel chip holding a ball of 0.5 mm in diameter. After the ink backflow prevention body was disposed, the ballpoint pen refill was incorporated into a shaft tube to produce an aqueous ballpoint pen.

The following tests were performed with each of the water-based ballpoint pens.
Dripping test A water-based ballpoint pen with the cap removed is held downward (inverted) in a non-contact state with the pen tip (ballpoint pen tip) and left for 20 hours in an atmosphere at a temperature of 20 ° C. and a relative humidity of 90%. Were visually observed and evaluated according to the following criteria.
Cap-off test After assembly, the water-based ballpoint pen, which was confirmed to be writable, was placed horizontally under conditions of room temperature (20 ° C.) and humidity 55-75% RH with the pen tip exposed, and left for 10 days. P3201 writing paper A was handwritten and 12 circles were written continuously in one line, and from what line the writing was normally performed was examined and evaluated according to the following criteria.
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.
Cap-off test ○: Can be written immediately △: Written within 1 line.
Ink stability test ○: No abnormality.
X: The emulsion floats or settles.

Claims (4)

A dye as at least a colorant, water, the ink composition comprising a water-soluble organic solvent, and also contains the polyurethane emulsion, the average particle size of the emulsion Ri der less 0.1 [mu] m, the ink viscosity EM A shear-thinning water-based ink having a viscosity measured at 100 rpm (20 ° C.) of a type rotational viscometer in the range of 3 to 160 mPa · s and a shear thinning index in the range of 0.9 to 0.99, B A shear-thinning water-based ink having a measured viscosity (20 ° C.) at 60 rpm of a mold rotational viscometer in the range of 1 to 20 mPa · s and a shear thinning index in the range of 0.9 to 0.99, or A non-shear thinning water-based ink having a viscosity measured at 60 rpm (20 ° C.) of a B-type rotational viscometer in the range of 1 to 20 mPa · s, either directly with a ballpoint pen tip or via a relay member Directly filled in the ink accommodating tube attached Te, and prevention ink follower there tanδ points exceeding 1 in viscoelastic properties measured ink composition rear end face (omega) is in the range of 20rad / s ≦ ω ≦ 450rad / s A water-based ballpoint pen with a body. The aqueous ballpoint pen according to claim 1, wherein the polyurethane emulsion is a self-emulsifying emulsion in which a hydrophilic group exhibits anionic or nonionic properties and exhibits self-dispersibility in a medium . The water-based ballpoint pen according to claim 1 or 2, wherein the polyurethane emulsion is contained in the ink composition in the range of 0.1 to 5.0% by weight . Water resistant ballpoint pen according to any one of claims 1 to 3 ballpoint pen chip has a retractable mechanism that is housed within the barrel to a state exposed to ambient air.