JP2010006919A - Ink composition for use in rollerball pen and refill for use in rollerball pen using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide such an ink composition for use in a rollerball pen as the ink composition for use in the rollerball pen has the excellent feel of writing and suppresses the abrasion on a ball seat, and to provide a refill for use in the rollerball pen using it. <P>SOLUTION: The ink composition contains at least water, a coloring agent, a shear-thinning agent, a surfactant and a solid lubricant, and is characterized in that the solid lubricant is a fluorine-based resin which comprises a structure having unbranched -CF<SB>2</SB>- groups. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink composition for water-based ballpoint pens, and more particularly to an ink composition for water-based ballpoint pens that is excellent in lubricity and suppresses wear of a ball seat and a refill for water-based ballpoint pens using the same.

  2. Description of the Related Art Conventionally, water-based ballpoint pen ink compositions that contain a surfactant, a solid lubricant, or the like as a lubricant and have improved lubricity have been proposed in order to improve the handwriting such as writing quality and blur.

  Examples of the former containing a surfactant include those disclosed in JP-A No. 61-235479 “Pigment aqueous ink” using a fluorine-based surfactant, and JP-A No. 2004-346181 “Water-based ballpoint pen ink”. Is a combination of a fluorine-based surfactant and a silicon-based surfactant, and Japanese Patent Application Laid-Open No. 10-330678 “Titanium oxide-containing water-based ink for ball-point pens” describes a water-based ball-point pen containing a phosphate ester-based surfactant. An ink composition is disclosed.

As for the latter using a solid lubricant, JP-A-2-199182 “Pigment ink for ballpoint pen” discloses an aqueous ballpoint ink composition containing molybdenum disulfide and boron nitride.
"Japanese Patent Laid-Open No. 61-235479" "JP 2004-346181 A" "Japanese Patent Laid-Open No. 10-330678" "JP-A-2-199182"

  However, as in Patent Documents 1 to 3, by containing a surfactant in the water-based ballpoint pen ink composition, the writing quality is improved and the ball seat wear is suppressed compared to the case where no surfactant is contained. However, it is desired to further suppress wear and improve writing quality.

  In particular, as in Patent Documents 1 and 2, the fluorine-based surfactant and / or the silicon-based surfactant are more susceptible to wear on the ball seat than the phosphate ester surfactant in Patent Document 3, and the handwriting scraps and writing. There was also a risk of causing defects.

  On the other hand, in Patent Document 4, wear of the ball seat can be suppressed by using a solid lubricant of molybdenum disulfide or boron nitride, but the writing quality is lowered and molybdenum disulfide or boron nitride has a specific gravity. It was high and settled in the ink and had a problem of poor writing.

  An object of the present invention is to provide a water-based ballpoint pen ink composition with good writing quality and improved suppression of ball seat wear, and an aqueous ballpoint pen refill using the same.

In order to solve the above problems, the present invention
"1. An aqueous ballpoint pen ink composition containing at least water, a colorant, a shear thinning agent, a surfactant, and a solid lubricant, wherein the solid lubricant is a fluororesin. Water-based ink composition for ballpoint pens.
2. _{2. The} ink composition for water-based ballpoint pens according to item 1, wherein the fluororesin has an unbranched structure having a —CF ₂ — group.
3. The water-based ballpoint pen ink composition according to Item 1 or 2, wherein the fluorine-based resin has a molecular weight of 1,000,000 to 10,000,000.
4). The water-based ballpoint pen ink composition according to any one of claims 1 to 3, wherein the surfactant is a phosphate ester-based surfactant.
5). 5. The water-based ballpoint pen ink composition according to claim 1, wherein the phosphate ester-based surfactant has an HLB of 14 or more.
6). The water-based ballpoint pen ink composition according to claim 1, wherein the surfactant contains at least a fluorosurfactant.
7). A ballpoint pen tip holding a ball rotatably is provided at the tip of the ink storage cylinder directly or via a chip holder, and the ink storage cylinder is described in any one of items 1 to 6 A water-based ballpoint pen refill in which a water-based ink composition is directly packed, wherein the material of the ink containing cylinder is a transparent or translucent synthetic resin. "

  The present invention is characterized by containing a fluororesin as at least water, a colorant, a shear thinning agent, a surfactant, and a solid lubricant. It was possible to provide an ink composition for water-based ballpoint pens and a refill for water-based ballpoint pens using the same.

  The first feature of the present invention is to use a surfactant and a fluororesin in combination as a solid lubricant.

  The surfactant has an effect of improving lubricity between the ball and the chip body, obtaining a smooth writing feeling, improving writing quality and suppressing wear of the ball seat. Specific examples of the surfactant used in the present invention include phosphate ester surfactants, silicon surfactants, fluorine surfactants, acetylene glycol surfactants, fatty acids, and salts thereof. 1 type, or 2 or more types can be used.

  On the other hand, solid lubricants, such as molybdenum disulfide and graphite, improve the lubricity between the surfaces of the relatively moving materials, thereby preventing damage to the materials that move relatively. Lubricant.

  However, as solid lubricants, molybdenum disulfide (specific gravity 4.7), graphite (specific gravity 2.2), boron nitride (specific gravity 3.4 to 5.5), tungsten disulfide (specific gravity 7.4 to 7. 5), fluorine resin (specific gravity 1.7 to 2.3), polyimide resin (specific gravity 1.4 to 1.6) and the like can be exemplified, but there is a problem that the ink stability with time is poor.

  As a result of earnest research on the lubricity between the ball and the chip body and the wear of the ball seat, the inventors of the present application have used a surfactant and a fluororesin in combination as a solid lubricant, and compared with the surfactant alone. The present inventors have found that the suppression of wear of the ball seat is improved and that the lubricity not obtained with a solid lubricant alone is improved.

  Fluorine resin is a resin having many C—F bonds, and fluorine (F) is the atom with the greatest force (electronegativity) to take in other electrons, so the C—F bond energy becomes very high. The bond strength of C—F is very strong, and it is difficult to react with colorants such as dyes and pigments, solvents, surfactants, etc., so that the ink aging stability is also good.

  Furthermore, among solid lubricants, fluorine-based resins have low intermolecular force and very low intermolecular cohesive energy. Therefore, if force is applied by the rotation of the ball, it is between the ball of the ballpoint pen tip and the ball seat. Sliding easily occurs between molecules of fluororesin. Therefore, the wear suppression of the ball seat can be improved by the synergistic effect of the lubricity of the surfactant and the lubricity of the fluororesin.

  Specific examples of fluorine resins include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), and polyvinylidene fluoride (PVDF). ), Polyvinyl fluoride (FEP), ethylene / tetrafluoroethylene polymer (ETFE), and the like.

［式中nは、整数とする。］

［式中m、nは、整数、Rfは、パーフルオロカーボン基とする。］

［式中m、nは、整数とする。］
Further, among fluorine-based resins, those having a structure having a non-branched —CF ₂ — group as shown in (Chemical Formula 1) are preferable. The non-branched structure having a non-branched —CF ₂ — group is a non-polar structure in which F atoms are completely filled around the —CC— chain, and C—F bonds with a short bond distance are connected at equal distances. It becomes the structure of. For this reason, the surface of the molecule has few irregularities and is almost flat, so that the structure is more slippery. Examples of the fluororesin having such a structure include polytetrafluoroethylene (—CF ₂ —CF ₂ —) n. On the other hand, if the structure has a branched —CF ₂ — group, irregularities are generated on the molecular surface, and frictional resistance tends to occur. For example, as in (Chemical Formula 2), in the perfluoroalkoxyalkane (—CF ₂ —CF ₂ —) m (—CF ₂ —CF (ORf) —) n, (—ORf—) is changed to (Chemical Formula 3) In addition, in the case of perfluoroethylene propene copolymer (-CF ₂ -CF _2- ) m (-CF ₂ -CF (CF ₃ )-) n, (-CF _3- ) is branched, but the surface of the molecule is uneven. As a result, the frictional resistance is likely to occur, so that it is less slippery than (—CF ₂ —CF ₂ —) n having a —CF ₂ — group and no branching group. Therefore, as shown in (Chemical Formula 1), by using a fluorine-based resin having a structure having a non-branched —CF ₂ — group, it is more slippery in water-based inks and is more stable over time due to its nonpolar structure. Since it is possible to make the property good, it is most preferable.

[In the formula, n is an integer. ]

[Wherein m and n are integers, and Rf is a perfluorocarbon group. ]

[Wherein m and n are integers. ]

Specific examples of the fluorine-based resin having a structure having an unbranched —CF ₂ — group as in (Chemical Formula 1) include KT-300M, 400M, 600M, KTL-2N, 4N, 8N, 10N, 20N, 8F, 500F, 450, 610, 620 (Kitamura Corporation), Neophron AD-2, Lubron L2, Polyflon PTFE M391, 392, 393 (Daikin Industries, Ltd.) ), Teflon series such as Teflon 30-J and 120-J, Mouldin powder 7AJ (Mitsui / Dupont Fluorochemical Co., Ltd.) and the like can be used. In addition, the powder can be used in the form of powder, liquid that has been dispersed in advance with a surfactant, or paste. The fluororesins having these specific structures can be used alone or in combination of two or more. May be.

  Furthermore, as fluorine-based resins, there are a low molecular weight system having a relatively low molecular weight and a molecular weight of less than 1 million, and a high molecular weight system having a relatively high molecular weight of 1,000,000 to 10,000,000. However, the longer the molecular chain, the easier it is to break. For this reason, the molecular chain is broken by the rotation of the ball, and slipping occurs between the broken molecules. Therefore, a molecular weight of 1 million to 10 million is preferable.

  Further, if the content of the fluororesin is less than 0.1% by mass, the effect of suppressing the wear of the ball seat cannot be obtained, and if it exceeds 20.0% by mass, the ink aging stability may be deteriorated. The content is preferably 0.1 to 20.0% by mass relative to the total mass of the ink composition. More preferably, it is 5.0-12.0 mass%.

  The surfactant used in the present invention preferably contains at least a phosphate ester surfactant in consideration of writing quality and suppression of wear of the ball seat. This is because those having phosphate groups are adsorbing to metals, so they are adsorbing to balls and chip bodies, and are therefore more lubricious than other types of surfactants. This is because good writing quality is obtained and the effect of suppressing wear of the ball seat is excellent.

Phosphoric ester surfactants have a lower lipophilicity due to lower HLB values as the number of moles of ethylene oxide (CH ₂ CH ₂ O) added is lower, improving ball lubricity, and reducing writing and wear. In order to improve the effect, it is preferable to use a phosphate ester surfactant having an HLB of 13 or less in consideration of writing quality and wear suppression. On the other hand, if the HLB value is low and the lipophilicity is strong, the phosphate ester There is a problem that the system surfactant and metal ions such as manganese ions and chromium ions eluted from the inside of the chip body react to easily form a metal salt, and writing defects due to metal salt deposits are likely to occur. On the other hand, phosphate surfactants with an HLB of 14 or more have increased hydrophilicity due to an increase in the number of hydrophilic ethylene oxide (CH ₂ CH ₂ O), and are soluble in aqueous ink compositions. Stabilize. Therefore, the writing taste and wear-inhibiting ability are slightly reduced as compared with phosphate ester surfactants having an HLB of 13 or less. However, when used as a water-based ballpoint pen ink, the HLB is 14 in consideration of ink aging stability. It is preferable to use the above phosphate ester surfactants.

  The phosphate ester surfactant used in the present invention includes a plurality of types such as styrenated phenol, nonylphenol, lauryl alcohol, tridecyl alcohol, short chain alcohol, dinonylphenol, and octylphenol. .

［式中、Ｒはアルキル又はアルキルアリル基を、nはエチレンオキサイド付加モル数を、Ｒ’はＨまたはＲＯ（ＣＨ_２ＣＨ_２Ｏ）_ｎ基を示す。］ Examples of the phosphoric acid ester-based surfactant include polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid diester, and phosphoric acid triester. Although there are esters or derivatives thereof, these phosphate ester surfactants may be used alone or in admixture of two or more. Among these, in consideration of ink aging stability, it is preferable to use a polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether monoester or diester of polyoxyethylene alkylaryl ether represented by the general formula .

[Wherein, R represents an alkyl or alkylallyl group, n represents the number of moles of ethylene oxide added, and R ′ represents H or a RO (CH ₂ CH ₂ O) _n group. ]

Examples of the phosphoric acid ester surfactant such as (Chemical Formula 4) include styrenated phenols, nonylphenols, lauryl alcohols, tridecyl alcohols, octylphenols, short chain alcohols, and the like. Further, among this, styrenated phenol, nonylphenol type, phenyl skeleton of octylphenol system such as _{(C 6 H 5 -, C} 6 H 4 -, C 6 H 3 - , etc.) phosphoric acid ester-based surfactant having a can, Since the phenyl skeleton forms a three-dimensional structure, it has the effect of causing steric hindrance compared to other systems, and the lubricity is somewhat inferior, and the improvement in writing quality is small. It is most preferable to use a tridecyl alcohol type or a short chain alcohol type.

Specific examples of the phosphate ester surfactant represented by the general formula such as (Chemical Formula 4) include Prisurf A212C (HLB value of 9, from the Prisurf series (Daiichi Kogyo Seiyaku Co., Ltd.)). Tridecyl alcohol), A210G (HLB value 9, octylphenol), A207H (HLB value 7, dinonylphenol), AL (HLB value 5, styrenated phenol), A208B (HLB value 6, lauryl) Alcohol type), A208S (HLB value 7, synthetic alcohol type), A208F (HLB value 9, short chain alcohol type), A212E (HLB value 10, nonylphenol type), A215C (HLB value 11, tridecyl alcohol) Type), A217E (HLB value 14, nonylphenol type), A219B (HLB value 16, Lauri) Alcohol-based), and the like. These phosphate ester surfactants may be used alone or in combination of two or more.
In addition, HLB can be calculated | required from HLB = 7 + 11.7log (Mw / Mo) and (Mw: molecular weight of a hydrophilic group, Mo: molecular weight of a lipophilic group) as a general formula.

  Further, if the content of the phosphate ester surfactant is less than 0.1% by mass, the desired writing taste cannot be obtained, and if it exceeds 5.0% by mass, the ink aging stability may be deteriorated. It is preferable to make it 0.1-5.0 mass% with respect to the total mass of an ink composition. More preferably, it is 0.5-3.0 mass%.

  In order to stabilize the fluororesin of the solid lubricant used in the present invention for a long period of time, it is preferable to disperse using a surfactant. In particular, the same fluorine-based surfactant has an effect of stably dispersing the fluorine-based resin in the water-based ink composition, and has a high specific gravity of a fluorine-based resin (specific gravity 1.7 to 2.3). Since it becomes easy to suppress sedimentation, it is preferable, and it is most preferable to use together with the phosphate ester surfactant mentioned above.

  Further, the content of the surfactant used to stabilize the dispersion of the fluororesin of the solid lubricant is inferior in dispersibility when it is less than 0.1% by mass, and the stability with time with ink when it exceeds 10.0% by mass. Since it may be inferior, it is preferable to make it into 0.1-10.0 mass% with respect to the ink composition total mass. More preferably, it is 0.5-5.0 mass%.

Further, the shear thinning agent is used as an ink viscosity adjustment, a solid lubricant used in the present invention, a pigment dispersant, a cross-linked acrylic acid polymer, xanthan gum, succinoglycan, gar gum, welan gum, ramzan gum, locust. Shear thinning agents such as Bingham and Dieutan gum are used. You may use these individually or in mixture of 2 or more types. Among them, when an acrylic resin is used, a large number of carboxyl groups (—COO ⁻ ) encapsulate metal ions eluted from the inside of the ballpoint pen chip, thereby suppressing the reaction between the metal ions and the phosphate ester surfactant. Therefore, it is preferable to use at least a cross-linked acrylic acid polymer because it acts as a chelating agent in suppressing metal salt precipitates. You may use these individually or in mixture of 2 or more types.

  In addition, when the content of the shear thinning agent is less than 0.1% by mass, it is difficult to suppress sedimentation of the fluororesin, and when it exceeds 2.0% by mass, the writing quality is lowered. It is preferable to set it as 0.1-2.0 mass% with respect to. More preferably, it is 0.1-0.6 mass%.

The ink viscosity is not limited, but considering the dispersion stability and writing performance of the solid lubricant used in the present invention, the shear rate is 1.92 sec ⁻¹ and 1000 mPa · s to 3500 mPa · s. Is preferable. More preferably, it is 1200 Pa · s to 2500 mPa · s.

  Further, the colorant is not particularly limited, such as a dye or a pigment, and can be appropriately selected and used. As the dye, direct dyes, acid dyes, basic dyes, metal-containing dyes, various salt-forming dyes, and the like can be used. Examples of pigments include inorganic, organic, and processed pigments. Specific examples include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, quinophthalone, and selenium. , Triphenylmethane, perinone, perylene, glyoxazine, aluminum pigment, pearl pigment, fluorescent pigment, phosphorescent pigment, and complementary color pigment. In addition, a microcapsule pigment obtained by encapsulating or solidifying a colored body obtained by dispersing a pigment in a medium as a colored resin particle body in a shell made of a resin wall film forming substance by a known microencapsulation method or the like may be used. good. Further, colored resin particles in which the pigment is covered with a transparent or translucent resin or the like, or colored resin particles or colorless resin particles colored with a pigment or a dye can also be used. These dyes and pigments may be used alone or in combination of two or more. The content is preferably 1% by mass to 20% by mass with respect to the total amount of the ink composition.

  Other organic solvents include glycols such as ethylene glycol and glycerin, pH adjusters such as triethanolamine, antibacterial agents such as 1,2 benzoisothiazolin-3-one, humectants such as urea and sorbit, benzotriazole A rust preventive agent such as ethylenediaminetetraacetic acid can be added. In addition, dispersants can be added as appropriate. As water-soluble resins, acrylic resins, alkyd resins, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, etc., and resin emulsions such as acrylic resins, urethane resins, styrene-butadiene resins. Polyester resins, vinyl acetate resins and the like can be added. These can be used alone or in combination of two or more.

Next, an Example is shown and this invention is demonstrated.
Example 1
Water 48.5 parts by mass Water-soluble organic solvent (ethylene glycol) 20.0 parts by mass Solid lubricant (fluorine resin) 10.0 parts by mass Surfactant (phosphate ester-based surfactant) 1.0 part by mass interface Activator (Fluorosurfactant) 2.0 parts by mass pH adjuster (triethanolamine) 1.5 parts by mass humectant (urea) 5.0 parts by mass humectant (Sorbit) 5.0 parts by mass antibacterial agent (1,2 benzoisothiazolin-3-one) 0.5 parts by mass rust inhibitor (benzotriazole) 0.5 parts by mass colorant (direct black 154) 6.0 parts by mass shear thinning agent (crosslinked acrylic acid) Polymer) 0.40 part by mass

  First, in the water-based ink composition of Example 1, a fluororesin dispersion was prepared in advance by stirring and dispersing a fluororesin using a fluorosurfactant, water, and ethylene glycol. Thereafter, the fluororesin dispersion, water-soluble organic solvent, water, phosphate ester surfactant (Pricesurf 219B: Daiichi Kogyo Seiyaku Co., Ltd.), triethanolamine, colorant, antibacterial agent, A predetermined amount of the rusting agent was accurately weighed and heated and stirred with a magnet hot stirrer to prepare a base ink.

Ink viscosity in Examples and Comparative Examples was measured using a Brookfield DV-II viscometer (CPE-42 rotor) in a 20 ° C. environment at a shear rate of 1.92 sec ⁻¹ (rotation speed: 0.5 rpm), The ink viscosity was measured under two conditions of a shear rate of 384.0 sec ⁻¹ (rotation speed: 100 rpm).

Examples 2-11
As shown in Tables 1 and 2, water-based ink compositions of Examples 2 to 11 were obtained in the same procedure as in Example 1 except that each component was changed to a blend. Tables 1 and 2 show the measurement and evaluation results.

Comparative Examples 1-6
The composition of the ink is as shown in Table 3, and Table 3 shows the measurement and evaluation results.

Test and Evaluation A ballpoint pen tip in which the water-based ink composition produced in Examples 1 to 11 and Comparative Examples 1 to 6 was held in a tip holder of an ink containing cylinder rotatably with a ball having a ball diameter of φ0.5 mm was used as a chip holder. A ballpoint pen filled in an ink containing cylinder (made of polypropylene) was prepared, and the following tests and evaluations were performed. The ball seat wear test, writing taste, and handwritten writing test were evaluated by the following test method using JIS P3201 writing paper A as the writing test paper. In the ball seat wear test, the running writing test was performed at a writing angle of 65 °, a writing load of 100 g, and a writing speed of 4 m / min.

Ball seat wear test: The amount of sinking of the ball seat after writing 500 m was measured.
Ball seat wear of less than 10 μm
Ball seat wear of 10 to 20 μm
Ball seat wear exceeding 20 μm ・ ・ ・ ×

Written taste: A hand-written sensory test was performed and evaluated.
Smooth and good ・ ・ ・ ◎
Somewhat inferior ・ ・ ・ ○
Heavy and inferior ・ ・ ・ ×

Handwritten writing test: Handwriting written on paper was observed.
No smearing or line skipping in the handwriting
Scratches, severe line skipping, or poor writing in the handwriting

Solid lubricant dispersion test: Each water-based ink composition was placed in a 15 mm diameter open / close glass test tube, allowed to stand at room temperature for 1 month, and then collected in an appropriate amount. The dispersion state of the solid lubricant was observed with a microscope.
Solid lubricant dispersed uniformly ・ ・ ・ ◎
Sedimentation of solid lubricant was confirmed to some extent, but there was no practical problem.
Solid lubricant with a severe sedimentation level and poor writing

Ink aging test of chip body: The ink in the chip body was microscopically observed after leaving the refill for a ballpoint pen in an environment of 50 ° C. and 0% humidity for 3 months at room temperature.
Good without deposits ... ◎
Slightly generated precipitates, but no problem in practical use
Precipitates are generated and the practicality is poor.

  From the results of Tables 1 and 2, in Examples 1 to 11, good performances were obtained for the ball seat wear test, writing taste, handwriting writing test, solid lubricant dispersion test, and chip body ink aging test.

  From the results in Table 3, in Comparative Examples 1 and 2, since the fluorine-based resin of the solid lubricant was not used, the wear of the ball seat was 10 to 20 μm.

  In Comparative Examples 3 and 4, since the surfactant was not used, the writing was heavy and the handwriting was severely damaged.

  In Comparative Example 5, since molybdenum disulfide was used, the specific gravity was high and sedimentation occurred. In Comparative Example 6, since no shear thinning agent was used, the fluororesin sedimentation occurred. It could not be used as a water-based ink.

  The ink containing cylinder attached to the water-based ballpoint pen used in the present invention uses a transparent or translucent synthetic resin such as polyethylene or polypropylene so that the remaining amount of ink can be confirmed, but contains a fluorine-based resin as in the present invention. Filling the ink containing cylinder with the water-based ink composition suppresses ink adhesion to the inner wall surface of the ink containing cylinder and has a water repellent effect that allows the remaining amount of ink to be read.

  Furthermore, in the ink composition to which a large particle size such as a pigment is added, the writing quality may be deteriorated due to rotation inhibition between the ball and the chip body, and a ball having a ball diameter of 0.7 mm or less was used. Since the ball pen has a small contact area between the ball and the ball seat, and there is a possibility that the writing quality is deteriorated due to a high load applied to the unit area, the effect of the present invention is remarkable.

  The present invention relates to an ink composition for water-based ballpoint pens, and more specifically, characterized in that it contains at least water, a colorant, a shear thinning agent, a surfactant, and a fluorine-based resin as a solid lubricant. An ink composition for water-based ballpoint pens having good writing quality and suppressing wear of a ball seat can be provided. Therefore, it can be widely used as a ballpoint pen, such as a cap type and a knock type.

Claims (7)

An aqueous ballpoint pen ink composition comprising at least water, a colorant, a shear thinning agent, a surfactant, and a solid lubricant, wherein the solid lubricant is a fluororesin. Ink composition. The water-based ballpoint pen ink composition according to claim 1, wherein the fluororesin has a structure without a branch and having a —CF ₂ — group. The water-based ballpoint pen ink composition according to claim 1, wherein the fluororesin has a molecular weight of 1,000,000 to 10,000,000. The water-based ballpoint pen ink composition according to any one of claims 1 to 3, wherein the surfactant contains at least a phosphate ester-based surfactant. The water-based ballpoint pen ink composition according to claim 4, wherein the phosphate ester surfactant has an HLB of 14 or more. The water-based ballpoint pen ink composition according to claim 1, wherein the surfactant contains at least a fluorosurfactant. The water-based ballpoint pen according to any one of claims 1 to 6, wherein a ballpoint pen tip holding a ball rotatably is provided directly or via a tip holder at a front end portion of the ink containing cylinder. A water-based ballpoint pen refill directly packed with an ink composition for water-based ballpoint pens, wherein the ink container is made of a transparent or translucent synthetic resin.