Water-based ink composition for ballpoint pens and refill for water-based ballpoint pens

Abstract

The present invention provides a water-based ink composition for ballpoint pens and a refill for water-based ballpoint pens that suppresses ball corrosion over long periods of time and maintains a smooth writing feel. [Solution] An aqueous ink composition for ballpoint pens comprising at least water, a coloring agent, polyoxyethylene cetyl ether, and 2-pyridinethiol 1-oxide sodium.

Description

Technical Field

[0001] The present invention relates to an aqueous ink composition for ballpoint pens containing at least a colorant and water as a liquid medium.

Background Art

[0002] A ballpoint pen basically consists of an ink-containing tube that houses ink, and a ballpoint pen tip that is connected directly or via a connecting member to the ink-containing tube and allows the ink to flow through it in a communicating manner. The ballpoint pen tip is at least composed of a ball that transfers ink when it contacts the writing surface and a ball holder that holds the ball rotatably. As a ball for ballpoint pens, a sintered body of tungsten carbide containing chromium, cobalt, etc. as binding components is known, and such a material is what is called so-called cemented carbide. Chromium, cobalt, etc., which are binding components in this cemented carbide ball, cause so-called corrosion where the binding components are eluted into the ink due to the water contained in the aqueous ink and the oxygen present in the ink or outside. When the binding components are eluted, tungsten carbide particles, cobalt, etc. which are binding components are exposed on the surface, causing the ball surface to become uneven, and the smoothness of the writing feel may be lost.

[0003] To prevent this, there are examples such as leaving the ink under reduced pressure before housing it in the ink-containing tube to make the amount of dissolved gas in the ink below a certain value (Patent Document 1), and examples of adding polyphenols or hydroquinone derivatives, which are substances having reducing properties that bind to oxygen, to the ink (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] The invention described in Patent Document 1 describes a method of filling an ink storage tube with ink by leaving it under reduced pressure before filling it with ink to reduce the amount of dissolved gas in the ink to below a certain level. However, if the ink storage tube is made of resin, oxygen from the atmosphere permeates through the ink storage tube and mixes into the ink over time, causing the amount of dissolved gas in the ink to exceed a certain level, and thus a sufficient corrosion prevention effect cannot be obtained. The invention described in Patent Document 2 describes a method of adding polyphenols or hydroquinone derivatives, which are reducing substances, to the ink. Although the reduction in dissolved oxygen prevents oxidative bonding with the ball binding components, there is a problem in that peroxide radicals generated when the reducing substances react with dissolved oxygen attack and dissolve the ball binding components. Furthermore, the decrease in dissolved oxygen in the ink leads to a large difference in oxygen concentration with the outside air, forming an oxygen concentration cell in the tiny space at the tip of the ball holder. This causes iron, the main component of the ball holder, to dissolve, and the dissolved iron then turns into hydroxide and adheres to the ball surface, resulting in an uneven surface and a loss of smooth writing. [Means for solving the problem]

[0006] The present invention relates to an aqueous ink composition for ballpoint pens comprising at least water, a colorant, polyoxyethylene cetyl ether, and 2-pyridinethiol 1-oxide sodium. [Effects of the Invention]

[0007] The polar groups of polyoxyethylene cetyl ether and 2-pyridinethiol 1-oxide sodium adsorb to the metal surface of the ball, forming a film on the ball surface with their respective hydrophobic groups facing away from the metal surface. The carbon chains of the polyoxyethylene cetyl ether adsorbed on the metal surface of the ball surround and cover the 2-pyridinethiol 1-oxide sodium through hydrophobic interactions, forming a dense hydrophobic film on the metal surface of the ball. This dense hydrophobic film reduces contact with water and oxygen on the ball surface, preventing the leaching of ball components, suppressing ball corrosion, and maintaining a smooth writing feel. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view showing a writing instrument according to one embodiment. [Figure 2] Figure 1 is a longitudinal cross-sectional view showing the refill used in the writing instrument shown. [Figure 3] This is an enlarged cross-sectional view showing part I in Figure 2. [Figure 4] This is a longitudinal cross-section of a test ballpoint pen tip. [Figure 5] This is a longitudinal cross-sectional view showing a writing instrument according to one embodiment. [Modes for carrying out the invention]

[0009] The coloring agent used in the water-based ballpoint pen ink of the present invention provides a coloring effect to the handwriting, making it visible, and includes dyes and pigments. Specific examples of dyes include acid dyes, direct dyes, and basic dyes. To give some examples, Japanol Fast Black D Concentrate (CI Direct Black 17), Water Black 100L (CI 19), Water Black L-200 (CI 19), Direct Fast Black B (CI 22), Direct Fast Black AB (CI 32), Direct Deep Black EX (CI 38), Direct Fast Black Concentrate (CI 51), Kayaras Splashray VGN (CI 71), Kayaras Direct Brilliant Yellow G (CI Direct Yellow 4), Direct Fast Yellow 5GL (CI 26), Eisen Primula Yellow GCLH (CI 44), Direct Fast Yellow R (CI 50), Daiwa IJ Yellow 306H (CI 123), Eisen Direct Fast Red FH (CI Direct Red 1), Nippon Fast Scarlet GSX (CI 4), Direct Fast Scarlet 4BS (CI 23), Eisen Daiwa Rectlow Durine BH (31), Direct Scarlet B (37), Kayak Direct Scarlet 3B (39), Eisen Primula Pink 2BLH (75), Sumilight Red F3B (80), Eisen Primula Red 4BH (81), Kayaras Spurarbin BL (83), Kayaras Light Red F5G (225), Kayaras Light Red F5B (226), Kayaras Light Rose FR (227), Dai Direct dyes such as Rect Sky Blue 6B (CI Direct Blue 1), Direct Sky Blue 5B (CI 15), Sumilight Supra Blue BRR Concentrate (CI 71), Daibogen Turquoise Blue S (CI 86), Kayaras Turquoise Blue GL (CI 86), Water Blue #3 (CI 87), Kayaras Supra Blue FF2GL (CI 106), Kayaras Supra Turquoise Blue FBL (CI 199), and Acid Blue Black 10B (CIAcid Black 1), Nigrosine (2), Suminol Milling Black 8BX (24), Kayanol Milling Black VLG (26), Suminol Fast Black BR ​​Concentrate (31), Mitsui Nylon Black GL (52), Eisen Opal Black WH Extra Concentrate (52), Sumilan Black WA (52), Ranil Black BG Extra Concentrate (107), Kayanol Milling Black TLB (109), Suminol Milling Black B (109), Kayanol Milling Black TLR (110), Eisen Opal Black New Concentrate (119), Water Black 187-L (154), Water Black #256L, Kayak Acid Brilliant Flavin FF (CI Acid Yellow 7:1), Kayacil Yellow GG (17), Xylene Light Yellow 2G 140% (17) Suminol Leveling Yellow NR (No. 19), Daiwa Turtrazine (No. 23), Kayactrazine (No. 23), Water Yellow #1 (No. 23), Suminol Fast Yellow R (No. 25), Diacid Light Yellow 2GP (No. 29), Suminol Milling Yellow O (No. 38), Suminol Milling Yellow MR (No. 42), Water Yellow #6C (No. 42), Kayanol Yellow NFG (No. 49) Suminol Milling Yellow 3G (72%), Suminol Fast Yellow G (61%), Suminol Milling Yellow G (78%), Kayanol Yellow N5G (110%), Suminol Milling Yellow 4G 200% (141%), Kayanol Yellow NG (135%), Kayanol Milling Yellow 5GW (127%), Kayanol Milling Yellow 6GW (142%), Sumitomo Fast Scarlet A (CIAcid Red 8), Kayak Silk Scarlet (9), Solar Rubin Extra (14), Daiwa New Kokushin (18), Eisen Bonso RH (26), Daiwa Red No. 2 (27), Suminol Leveling Brilliant Red S3B (35), Kayakil Rubinol 3GS (37), Eisen Erythrosine (51), Kayak Acid Rhodamine FB (52), Daiwa Red No. 106 WB (52), Suminol Leveling Rubinol 3GP (57), Diacid Alizarin Rubinol F3G 200% (82), Eisen Eosin GH (87), Daiwa Red No. 103 WB (87), Daiwa Red No. 104 WB (92), Water Pink #2 (92), Eisen Acid Floki Shin PB (92), Rose Bengal (94), Kayanol Milling Scarlet FGW (111), Kayanol Milling Rubin 3BW (129), Suminol Milling Brilliant Red 3BN Concentrate (131), Suminol Milling Brilliant Red BS (138), Eisen Opal Pink BH (186), Suminol Milling Brilliant Red B Concentrate (249), Kayaku Acid Brilliant Red 3BL (254), Kayaku Acid Brilid Brilliant Red BL (265), Kayanol Milling Red GW (276), Mitsui Acid Violet 6BN (CI Acid Violet 15), Mitsui Acid Violet BN (17), Sumitomo Patent Pure Blue VX (CIAcid Blue 1), Water Blue #106 (same 1), Patent Blue AF (same 7), Water Blue #9 (same 9), Daiwa Blue No. 1 (same 9), Water Blue #116 (same 15), Suprano Blue B (same 15), Orient Solubble Blue OBC (same 22), Suminol Leveling Blue 4GL (same 23), Mitsui Nylon Fast Blue G (same 25), Kayashil Blue AGG (same 40), Kayashil Blue BR (same 41), Mitsui Alizarin Saphirol SE (same 43), Suminol Leveling Sky Blue R Extra Concentrate ( 62), Mitsui Nylon Fast Sky Blue B (78), Sumitomo Brilliant Indocyanine 6Bh / c (83), Sandran Cyanine N-6B 350% (90), Water Blue #105S (90), Fisco Blue 664 (90), Orient Solubble Blue OBX (93), Orient Solubble Blue OBB (93), Sumitomo Brilliant Blue 5G (103), Kayanol Milling Ultra Sky SE (112), Kayanol Milling Cyanine 5R (113), Eisen Opal Blue 2GLH (1 58) Acid dyes such as Water Blue #119, Daiwa Guinea Green B (CI Acid Green 3), Acid Brilliant Milling Green B (CI 9), Daiwa Green #70 (CI 16), Kayanol Cyanine Green G (CI 25), Suminol Milling Green G (CI 27), Eisen Katiron Yellow 3GLH (CI Basic Yellow 11), Eisen Katiron Brilliant Yellow 5GLH (CI 13), Sumi Acrylic Yellow E-3RD (CI 15), Maxilon Yellow 2RL (CI 19), Astrazon Yellow 7GLL (CI 2 1) Kayakuril Golden Yellow GL-ED (28), Astrazon Yellow 5GL (51), Eisen Kachiron Orange GLH (CI Basic Orange 21), Eisen Kachiron Brown 3GLH (30), Rhodamine 6GCP (CI Basic Red 1), Eisen Astrafloxin (12), Sumiacryl Brilliant Red E-2B (15), Astrazon Red GTL (18), Eisen Kachiron Brilliant Pink BGH (27), Maxylon Red GRL (46), Eisen Methyl Violet (CIExamples of basic dyes include Basic Violet (1), Eisen Crystal Violet (3), Eisen Rhodamine B (10), Astrazon Blue G (CI Basic Blue 1), Astrazon Blue BG (3), Water Blue #10C (7), Methylene Blue (9), Maxilon Blue GRL (41), Eisen Katiron Blue BRLH (54), Eisen Diamond Green GH (CI Basic Green 1), Eisen Malachite Green (4), and Bismarck Brown G (CI Basic Brown 1).

[0010] Specific examples of pigments include organic pigments such as azo pigments, nitroso pigments, nitro pigments, basic dyes, acid dyes, vat dyes, mordant dyes, and natural dyes; inorganic pigments such as yellow ochre, barium yellow, ultramarine, Prussian blue, cadmium red, barium sulfate, titanium dioxide, iron oxide, iron black, and carbon black; metallic powder pigments such as aluminum powder, gold powder, silver powder, copper powder, tin powder, and brass powder; fluorescent pigments; and mica-based pigments. To give specific examples, carbon black includes Mitsubishi Carbon Black #10B, #20B, #14, #25, #30, #33, #40, #44, #45, #45L, #50, #55, #95, #260, #900, #1000, #2200B, #2300, #2350, #2400B, #2650, #2700, #4000B, CF9, MA8, MA11, MA77, MA100, MA220, MA230, MA600 and MCF88 (all manufactured by Mitsubishi Chemical Corporation), Monarch 120, Monarch 700, Monarch 800, Monarch 880, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, Mogul L, Regal 99R, Regal 250R, Regal 300R, Regal 330R, Regal 400R, Regal 500 and Regal 660R (all manufactured by Cabot) Printex A, Printex G, Printex U, Printex V, Printex 55, Printex 140U, Printex 140V, Printex 35, Printex 40, Printex 45, Printex 85, Ninepex 35, Special Black 4, Special Black 4A, Special Black 5, Special Black 6, Special Black 100, Special Black 250, Special Black 350, Special Black 550, Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160 and Color Black S170 (all manufactured by Degussa Japan Co., Ltd.), Raven 5000 Ultra II, Raven 2500 Ultra, Raven 1250, Raven 760 Ultra (all manufactured by Colombian Carbon Japan Co., Ltd.)Examples include CI Pigment Black 7, etc. Specific examples of organic pigments include CI Pigment Red 170, CI Pigment 213, CI Pigment Orange 38, CI Pigment Blue 15, CI Pigment Violet 23, Aniline Black (CI50440), Cyanine Black, Naphthol Yellow S (CI10316), Hansa Yellow 10G (CI11710), Hansa Yellow 5G (CI11660), Hansa Yellow 3G (CI11670), Hansa Yellow G (CI11680), Hansa Yellow GR (CI117 30), Hansa Yellow A (CI11735), Hansa Yellow RN (CI11740), Hansa Yellow R (CI12710), Pigment Yellow L (CI12720), Benzidine Yellow (CI21090), Benzidine Yellow G (CI21095), Benzidine Yellow GR (CI21100), Permanent Yellow NCG (CI20040), Vulcan Fast Yellow 5G (CI21220), Vulcan Fast Yellow R (CI21135), Tartrazine Lake (C I19140), Quinoline Yellow Lake (CI47005), Anthragen Yellow 6GL (CI60520), Permanent Yellow FGL, Permanent Yellow H10G, Permanent Yellow HR, Anthrapyrimidine Yellow (CI68420), Sudane I (CI12055), Permanent Orange (CI12075), Resol Fast Orange (CI12125), Permanent Orange GTR (CI12305), Hansa Yellow 3R (CI11725), Vulcan Fast Orange GG (CI21165), Benzidine Orange G (CI21110), Persian Orange (CI15510), Indanthrene Brilliant Orange GK (CI59305), Indanthrene Brilliant Orange RK (CI59105), Indanthrene Brilliant Orange GR (CI71105), Permanent Brown FG (CI12480), Para Brown (CI12071), Permanent Red 4R (CI12120), Para Red (CI12070),Fire Red (CI12085), Parachlor-Ortho-Aniline Red (CI12090), Resol Fast Scarlet, Brilliant Fast Scarlet (CI12315), Brilliant Carmine BS, Permanent Red F2R (CI12310), Permanent Red F4R (CI12335), Permanent Red FRL (CI12440), Permanent Red FRLL (CI12460), Permanent Red F4RH (CI12420), Fast Scarlet VD, Vulcan Fast Rubin B (CI12320), Vulcan Fast Pink G (CI12330), Light Fast Red Toner B (CI12450), Light Fast Red Toner R (CI12455), Permanent Carmine FB (CI12490), Pyrazolon Red (CI12120), Resol Red (CI15630), Lake Red C (CI15585), Lake Red D (CI15500), Anthocyn B (CI18030), Brilliant Scarlet G (CI15800), Resol Rubin GK (CI15 825), Permanent Red F5R (CI15865), Brilliant Carmine 6B (CI15850), Pigment Scarlet 3B (CI16105), Bordeaux 5B (CI12170), Toluidine Maroon (CI12350), Permanent Bordeaux F2R (CI12385), Helio Bordeaux BL (CI14830), Bordeaux 10B (CI15880), Bon Maroon Light (CI15825), Bon Maroon Medium (CI15880), Eosin Lake (CI45380), Rhodamine Lake B (CI45170), Rhodamine Lake Y (CI45160), Alizarin Lake (CI58000), Thioindigo Red B (CI73300), Thioindigo Maroon (CI73385), Permanent Red FGR (CI12370), PV Carmine HR, Watching Red, Monolight Fast Red YS (CI59300), Permanent Red BL, Fast Violet B, Methyl Violet Lake (CI42535), Dioxazine Violet, Alkali Blue Lake (CI42750A,Examples include CI42770A), Peacock Blue Lake (CI42090), Peacock Blue Lake (CI42025), Victoria Blue Lake (CI44045), Phthalocyanine Blue (CI74160), Fast Sky Blue (CI74180), Indanthrene Blue RS (CI69800), Indanthrene Blue BC (CI69825), Indigo (CI73000), Pigment Green B (CI10006), Naphthol Green B (CI10020), Green Gold (CI12775), Acid Green Lake, Malachite Green Lake (CI42000), Phthalocyanine Green, etc., which are used dispersed in a liquid medium.

[0011] When pigments are used as colorants, it is permissible to use dispersants to stably disperse the pigments. Conventional dispersants such as water-soluble resins or anionic or nonionic surfactants used as pigment dispersants can be used. Examples of polymeric dispersants include natural polymers such as lignin sulfonates and shellac, anionic polymers such as polyacrylates, styrene-acrylic acid copolymer salts, vinylnaphthalene-maleic acid copolymer salts, sodium salts and phosphates of β-naphthalene sulfonic acid formalin condensates, and nonionic polymers such as polyvinyl alcohol and polyethylene glycol. Furthermore, surfactants include anionic surfactants such as alkyl sulfates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids and their salts, N-acylmethyl taurates, polyoxyethylene alkyl ether acetates, alkyl sulfocarboxylic acid salts, α-olefin sulfonates, alkyl phosphates, and polyoxyethylene alkyl ether phosphates, as well as nonionic surfactants such as polyoxyethylene alkyl ethers, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters. These water-soluble resins and surfactants can be used individually or in combination of two or more types. The amount used is preferably 0.05% to 20.0% by weight relative to 10.0% by weight of the pigment.

[0012] Commercially available water-dispersible pigments are preferred because they offer improved handling and productivity. Specific examples of water-dispersible pigments include Fuji SP Black 8031, 8119, 8167, 8276, 8381, 8406, Fuji SP Red 5096, 5111, 5193, 5220, Fuji SP Bordeaux 5500, Fuji SP Blue 6062, 6133, 6134, 6401, Fuji SP Green 7051, Fuji SP Yellow 4060, 4178, Fuji SP Violet 9011, Fuji SP Pink 9524, 9527, Fuji SP Orange 534, Fuji SP Brown 3074, Fuji SP RED 5543, 5544 (all manufactured by Fuji Pigment Co., Ltd.), Emacol Black CN, Emacol Blue FBB, FB, KR, Emacol Green LXB, Emacol Violet BL, Emacol Brown 3101, Emacol Carmmine FB, Emacol Red BS, Emacol Orange R, Emacol Yellow FD, Emacol Yellow IRN, Emacol Yellow 3601, Emacol FGN, Emacol GN, Emacol GG, Emacol F5G, Emacol F7G, Emacol 10GN, Emacol 10G, Sandye Super Black K, Emacol Black C, Sandye Super Grey B, Sandye Super Brown SB, Emacol FRL, Emacol RR, Sandye Super Green L5G, Emacol GXB, Sandye Super Navy Blue HRL, Emacol GLL, Emacol HB, Emacol FBL-H, Emacol FBL-160, Emacol FBB, Sandye Super Violet BL H / C, Emacol BL, Sandye Super Bordeaux FR, Sandye Super Pink FBL, Emacol F5B, Sandye Super Rubine FR, Sandye Super Carmmine FB, Sandye Super Red FFG, RR, BS, 1315, Sandye Super Orange FL, R, BO, Sandye Gold Yellow 5GR, R, 3R, Sandye YellowGG, F3R, IRC, FGN, GN, GRS, GSR-130, GSN-130, GSN, 10GN (all manufactured by Sanyo Pigment Co., Ltd.), Rio Fast Black Fx 8012, 8313, 8169, Rio Fast Red Fx 8209, 8172, Rio Fast Red S Fx 8315, 8316, Rio Fast Blue Fx 8170, Rio Fast Blue FX 8170, Rio Fast Blue S Fx 8312, Rio Fast Green S Fx 8314, EM green G, (all manufactured by Toyo Ink Co., Ltd.), NKW-2101, NKW-2102, NKW-2103, NKW-2104, NKW-2105, NKW-2106, NKW-2107, NKW-2108, NKW-2117, NKW-2127, NKW-2137, NKW-2167, NKW-2101P, NKW-2102P, NKW-2103P, NKW-2104P, NKW-2105P, NKW-2106P, NKW-2107P, NKW-2108P, NKW-2117P, NKW-2127P, NKW-2137P, NKW-2167P, NKW-3002, NKW-3003, NKW-3004, NKW-300 5, 3007, 3077, 3008, 3402, 3404, 3405, 3407, 3408, 3477, 3602, 3603, 3604, 3605, 3607, 3677, 3608, 3702, 3703, 3704, 3705, 3777, 3708, 6013, 6038, 6559 (all manufactured by Nippon Fluorescent Co., Ltd.), Cosmo Color S1000F series (manufactured by Toyo Soda Co., Ltd.), Victoria Yellow Examples include G-11, G-20, Victoria Orange, G-16, G-21, Victoria Red, G-19, G-22, Victoria Pink, G-17, G-23, Victoria Green, G-18, G-24, Victoria Blue, G-15, G-25 (all manufactured by Mikuni Pigment Co., Ltd.), and the Pollux series such as Pollux PC5T1020, Pollux Black PC8T135, Pollux Red IT1030 (all manufactured by Sumika Color Co., Ltd.). These dyes and pigments can be used individually or in combination.

[0013] Water is used as the main solvent in the ink. In this invention, the main solvent refers to a solvent that accounts for 50% by weight or more of the total amount of solvent in the total amount of ink composition. It is preferable to use deionized water or purified water. Furthermore, conventionally known organic solvents can be used in combination to improve various ink qualities, such as preventing ink freezing at low temperatures and preventing ink drying at the pen tip. Specific examples of organic solvents include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, hexylene glycol, 1,2-propanediol, 1,3-butanediol, 2-ethyl-1,3-hexane glycol, propylene glycol, polypropylene glycol, dipropylene glycol, polyethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, thiodiethylene glycol, glycerin, diglycerin, benzyl glycol, benzyl diglycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, dipropylene glycol monoethyl ether, ethylene glycol monobutyl ether, and ethylene glycol monomethyl ether. Examples include glycol ethers such as glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, propylene glycol monobutyl ether, propylene glycol monophenyl ether, tripropylene glycol monobutyl ether, and tripropylene glycol monophenyl ether; alcohol-based solvents such as ethanol, 1-propanol, 2-propanol, butyl alcohol, isopropyl alcohol, 3-methyl-3-methoxy-1-butanol, benzyl alcohol, α-methylbenzyl alcohol, lauryl alcohol, tridecyl alcohol, isododecyl alcohol, and isotridecyl alcohol; and propylene glycol methyl ether acetate, propylene glycol diacetate, 2-pyrrolidone, N-methyl-2-pyrrolidone, sulforane, γ-butyrolactone, and 2-phenoxyethanol. These can be used individually or in combination of two or more selected types.Furthermore, the amount used is preferably 2.0% by weight or more and 50.0% by weight or less of the total ink amount. This is preferable because it makes it easier to obtain a drying prevention effect on the pen tip. The amount of water used in this invention is preferably 30% by weight or more of the total ink composition.

[0014] 2-Pyridinethiol 1-oxide sodium is used to adsorb onto the ball surface, form a dense film with polyoxyethylene cetyl ether, and prevent the elution of the ball's binding components. Examples of 2-Pyridinethiol 1-oxide sodium include San-ai Oil Co., Ltd.'s San-ai Bac Sodium Omazine and San-ai Bac P-100, and Lonza Japan Co., Ltd.'s Sodium Omazine. The amount of 2-Pyridinethiol 1-oxide sodium used is preferably 0.001% by weight or more and 1.00% by weight or less of the total amount of the ink composition. 0.005% by weight A value of 0.50% by weight or less is more preferable. A value of 0.001% by weight or more and 1.00% by weight or less relative to the total amount of the ink composition is preferable because it is easier to form a denser film with polyoxyethylene cetyl ether and easier to prevent the elution of the ball binding component, and a value of 0.005% by weight or more and 0.50% by weight or less is particularly preferable because it exhibits an even greater effect.

[0015] Polyoxyethylene cetyl ether is used to adsorb onto the ball surface and form a dense film through hydrophobic interactions with 2-pyridinethiol 1-oxide sodium, thereby preventing the elution of the ball's binding components. Examples of polyoxyethylene cetyl ethers used include NIKKOL BC-2 (HLB value 8.0), BC-5.5 (HLB value 10.5), BC-7 (HLB value 11.5), BC-10 (HLB value 13.5), BC-15 (HLB value 15.5), BC-20 (HLB value 17.0), BC-23 (HLB value 18.0), BC-25 (HLB value 18.5), BC-30 (HLB value 19.5), and BC-40 (HLB value 20.0) from Nikko Chemicals Co., Ltd., and nonionic cetyl ether from NOF Corporation. P-202 (HLB value 5.3), P-207 (HLB value 11.2), P-208 (HLB value 11.9), P-210 (HLB value 12.9), P-213 (HLB value 14.1), P-220 (HLB value 15.7), P-223 (HLB value 16.1), P-230 (HLB value 16.9), P-240 (HLB value 17.6), EMALEX manufactured by Nippon Emulsion Co., Ltd. 102 (HLB value 5), 103 (HLB value 6), 104 (HLB value 7), 105 (HLB value 8), 107 (HLB value 10), 112 (HLB value 12), 115 (HLB value 13), 117 (HLB value 13), 120 (HLB value 14), 125 (HLB value 15), BLAUNON manufactured by Aoki Oil & Fat Industry Co., Ltd. Examples include CH-302 (HLB value 5.7), CH-305 (HLB value 9.4), CH-308 (HLB value 11.4), CH-310 (HLB value 13.2), CH-310 (HLB value 12.9), CH-313 (HLB value 13.7), CH-315 (HLB value 14.3), CH-320 (HLB value 15.5), CH-325 (HLB value 16.3), CH-330 (HLB value 16.7), CH-340 (HLB value 17.4), CH-340F (HLB value 17.4), CR-640 (HLB value 17.6), and CR-640F (HLB value 17.6). The HLB value of polyoxyethylene cetyl ether is preferably 8 or higher and less than 14, and more preferably 8 or higher and less than 12.When the HLB value is 8 or higher, polyoxyethylene cetyl ether is more easily dispersed stably in the ink composition, the polyoxyethylene cetyl ether present on the ball surface becomes denser, and the elution of the ball's binding components is more easily prevented, which is preferable. On the other hand, when the HLB value is less than 14, the carbon chain of polyoxyethylene cetyl ether can more easily cover 2-pyridinethiol 1-oxide sodium, the hydrophobic film becomes stronger, and the effect of preventing the elution of the ball's binding components is more easily exerted, which is preferable, and when the HLB value is less than 12, the effect is even more easily exerted, which is particularly preferable. The amount of polyoxyethylene cetyl ether used is 0.1% by weight or more of the total amount of ink composition, which makes it easier to form a denser film and more easily prevents the elution of the ball's binding components. On the other hand, when the amount of polyoxyethylene cetyl ether is 3.0% by weight or less of the total amount of ink composition, ink discharge from the pen tip is more easily stabilized, which is preferable. Polyoxyethylene cetyl ether may be added after preparing a polyoxyethylene cetyl ether dispersion by adding polyoxyethylene cetyl ether to ion-exchanged water and mixing and stirring. Mixing and stirring may be carried out by heating.

[0016] In the present invention, sugars can be used in the aqueous ink composition for ballpoint pens to suppress ink leakage from the pen tip by being highly viscous when standing, and to obtain shear-thinning properties that reduce viscosity due to the shear force of the rotating ball when writing, thereby enabling smooth ink discharge. Specific examples include HPC-SL, HPC-L, HPC-M, HPC-H (all hydroxypropyl cellulose, manufactured by Nippon Soda Co., Ltd.), Avicel PH-101, PH-102, PH-301, M06, TG-101, Ceolus SC-900, SC-900S, RC591S, RC-N81, RC-N30, CL-611S, DX-2, DX-3, UF-F711, UF-F702, ST-100, ST-02, FD-101, FD-301, FD- Celluloses such as F20, Ceolus Fiber DF-17 (all crystalline cellulose, manufactured by Asahi Kasei Corporation), Kelzan, Kelzan S, Kelzan T, Kelzan ST, Kelzan ASX, Kelzan ASXT, Kelzan AR, Kelzan HP, Kelzan G, Kelzan Ketrol CG, Kelzan CG-T, Kelzan CG-SFT (all manufactured by Sansho Co., Ltd.), Sunace, Sunace S, Sunace C, Sunace CS, Sunace BS, Sunace NF, Sunace G, Sunace ES, Sunace NXG-S, Sunace NXG-C, Bistop D-3000-DF, Sunace D-3000-DF-C (all manufactured by San-Ei Gen F.S.I. Co., Ltd.), Kojin, Sunace F, Xanthan gum such as the following: T, K (manufactured by Kojin Co., Ltd.), Echo Gum, 630, F, T, GM, RD, SF, 521, LAX-T, Monart Gum GS, HP, HS, KT, Minute GR, MA, Salt (manufactured by DSP Gokyo Food & Chemical Co., Ltd.), Nomucoat (manufactured by Nisshin Oil Co., Ltd.), Inagel V-7, V-7T (manufactured by Ina Food Industry Co., Ltd.), Leozan (succinoglucan, manufactured by Sansho Co., Ltd.), K1A96, BG3810 (manufactured by Sansho Co., Ltd.), etc. Ramsang gum such as Welan gum, K1A112, K7C2433 (all manufactured by Sansho Co., Ltd.), guar gums such as Jaguar 8111, Jaguar 8600, Jaguar HP-8, Jaguar HP-60, CP-13 (all manufactured by Sansho Co., Ltd.), pullulan (water-soluble polysaccharide, manufactured by Hayashibara Shoji Co., Ltd.), Leojic 250H (manufactured by Nippon Junyaku Co., Ltd.), Junron PW111 (manufactured by Nippon Junyaku Co., Ltd.), U-Jeri-CP (manufactured by Showa Denko K.K.), Carbopol 934, Carbopol 940, Carbopol 941,Examples include alkyl acrylate methacrylate copolymers such as Carbopol 980, Carbopol 981, Carbopol 1342, Carbopol 1382, Carbopol 2984, Carbopol 5984, Carbopol ETD2020, Carbopol ETD2050, EZ-1, Pemuren TR-1, Pemuren TR-2 (manufactured by Lubrizol, USA), and N-vinylacetamide polymerized crosslinked products such as GX-205 and NA-010 (manufactured by Showa Denko K.K.). Other examples include sadaiutan gum, alkasilan, alkasi gum, zetasi gum, gellan gum, psyllium seed gum, tamarind seed gum, tragacanth gum, galactomannan, carrageenan, ghati gum, karaya gum, and their salts. Xanthan gum is particularly preferred because its high shear viscosity reduction significantly lowers the ink viscosity during writing, resulting in less ink blotting and line breakage. It is also preferred due to its stability against temperature changes, pH, and salts, as well as its compatibility with acyl amino acids and / or their salts. Xanthan gum is a polysaccharide composed of glucose, mannose, and glucuronic acid, separated and purified from the culture solution of Xanthomonas. The viscosity, viscoelasticity, and shear viscosity reduction of these sugars can be adjusted by heat treatment of the sugars or by applying high pressure to the sugar solution to create high shear when it passes through the nozzle. The amount of sugar used is preferably 0.05% to 5.0% by weight of the total ink composition, but more preferably 0.1% to 2.0% by weight of the total ink composition in order to maintain the performance of the ballpoint pen. An amount of 0.05% by weight or more of the total ink composition is preferable because it makes the ink less likely to leak. On the other hand, a concentration of 5.0% by weight or less of the total ink composition is preferable because it results in more stable ink discharge from the pen tip and a better writing experience.

[0017] Fine particles can also be added to prevent wear on the ball holder. Specific examples of fine particles include alumina, silicon carbide, chromium oxide, boron carbide, zircon, celerite, jadeite, calcium fluoride, tungsten carbide, silica, diamond, garnet, aluminum nitride, and silicon nitride. Among these, alumina is preferred because, when used in combination with sugars, it can form a stronger sugar network structure. High-purity alumina from Sumitomo Chemical Co., Ltd. is used as the alumina particle. AKP-53 (center particle size 0.17 μm), AKP-50 (center particle size 0.20 μm), AKP-30 (center particle size 0.30 μm), AKP-20 (center particle size 0.46 μm), AKP-3000 (center particle size 0.70 μm), AA-03 (center particle size 0.44 μm), AA-04 (center particle size 0.50 μm), AA-05 (center particle size 0.53 μm), Examples include AA-07 (central particle size 0.83 μm), WA#30000 (central particle size 0.35 μm), WA#20000 (central particle size 0.45 μm), WA#10000 (central particle size 0.60 μm), WA#8000 (central particle size 1.2 μm), WA#6000 (central particle size 2.0 μm) from Fujimi Incorporated, and alumina powder AP005 (central particle size 0.05 μm), AP01 (central particle size 0.1 μm), AP03 (central particle size 0.3 μm), AP1 (central particle size 1 μm) from Herzog Japan Co., Ltd. The central particle size of the alumina was measured using a Nanotrac Wave2-EX150 (dynamic light scattering particle size distribution analyzer manufactured by Microtrac Bell Co., Ltd.) in a dispersion obtained by dispersing alumina in ethanol with ultrasound for 20 minutes. The median particle size is the diameter at which, when a powder is divided into two parts from a certain particle size, the larger and smaller parts are in equal amounts. This value is also called the median diameter, median size, or d50. The amount of these fine particles used is preferably 0.001% to 10% by weight, and more preferably 0.003% to 0.05% by weight, relative to the total amount of the ink composition. These fine particles may be used individually or in a mixture of two or more types.

[0018] Styrene-acrylic resin emulsions can also be used to provide stability against hand grease during long-distance writing. Specific examples include BASF Japan's Joncryl 7100 (solids acid value 51, solids content 48%, average particle size 0.10 μm), Joncryl 390 (solids acid value 54, solids content 46%, average particle size 0.09 μm), PDX7326 (solids acid value 38, solids content 38.5%, average particle size 0.10 μm), PDX7370 (solids acid value 87, solids content 42%, average particle size 0.08 μm), PDX7341 (solids acid value 51, solids content 49%, average particle size 0.10 μm), and PDX7380 (solids acid value 87). 19, Solid content 41%, average particle size 0.09μm), same 8300 (Solid content acid value 60, Solid content 43.5%, average particle size 0.09μm), same 74J (Solid content acid value 51, Solid content 45%, average particle size 0.08μm), same 8383 (Solid content acid value 23, Solid content 40%, average particle size 0.09μm), same PDX7323 (Solid content acid value 87, Solid content 42%, average particle size 0.08μm), same PDX7734 (Solid content acid value 89, Solid content 41.4%, average particle size 0.09μm), same PDX7775 (Solid content acid value 55, Solid content 45%, average particle size 0.08 μm), PDX7741 (solid content acid value 52, solid content 49%, average particle size 0.10 μm), PDX7677 (solid content Acid value 70, solid content 46%, average particle size 0.01 μm), 7600 (solid content acid value 60, solid content 47%, average particle size 0.09 μm), 775 (solid content Acid value 55, solid content 45%, average particle size 0.08μm), 537J (solid acid value 40, solid content 46%, average particle size 0.07μm), 352J (solid content) Acid value 51, solid content 45%, average particle size 0.10 μm), 352D (solid acid value 51, solid content 45%, average particle size 0.10 μm), PDX714 5 (solid content acid value 32, solid content 50%, average particle size 0.16 μm), same 538J (solid content acid value 61, solid content 45%, average particle size 0.10 μm), same 8 311 (solid content acid value 26, solid content 42%, average particle size 0.09 μm), PDX7667 (solid content acid value 82, solid content 45%, average particle size 0.09 μm) ), PDX7700 (solid content acid value 60, solid content 48%, average particle size 0.10μm), PDX7641 (solid content acid value 60, solid content 52%, average particle size 0. 10 μm), 780 (solid acid value 46, solid content 48%, average particle size 0.10 μm), 7610 (solid acid value 50, solid content 52%, average particle size 0.13 μm), the same as PDX7643 (solid content acid value 64, solid content 51.5%, average particle size 0.14 μm), the same as PDX7690 (solid content acid value 85, solid content 42.5%, average particle size 0.10 μm), the same as PDX7511 (solid content acid value 54, solid content 45.0%, average particle size 0.09 μm), the same as PDX7164 (solid content acid value 4, solid content 47.0%, average particle size 0.17 μm), the same as PDX7430 (solid content acid value 20, solid content 38.0%, average particle size 0.12 μm), the same as PDX7440 (solid content acid value 1, solid content 48.5%, average particle size 0.25 μm), the same as PDX7480 (solid content acid value 18, solid content 44.0%, average particle size 0.10 μm), the same as PDX7357 (solid content acid value 59, solid content 49.5%), the same as PDX7616A (solid content acid value 38, solid content 44%), the same as PDX7732 (solid content acid value 87, solid content 41.4%, average particle size 0.10 μm), the same as PDX7787 (solid content acid value 87, solid content 41.4%, average particle size 0.10 μm), the same as PDX7356 (solid content acid value 78, solid content 45.5%), the same as PDX7615 (solid content acid value 51, solid content 50.5%, average particle size 0.12 μm), the same as PDX7158 (solid content acid value 54, solid content 41%), the same as PDX7199 (solid content acid value 31, solid content 49.5%, average particle size 0.27 μm), the same as PDX7538 (solid content acid value 62, solid content 45.5%, average particle size 0.08 μm), the same as PDX7780 (solid content acid value 46, solid content 48%, average particle size 0.10 μm), etc. are exemplified. These styrene-acrylic resin emulsions may be used alone or in combination of two or more kinds.

[0019] In order to fix the coloring material of the ink on the paper surface, various resins can also be used in combination as a binder. Specifically, shellac, styrene-maleic acid copolymer, alkali metal salts of styrene-acrylic acid copolymer, amine salts thereof, ammonium salts thereof, alkali metal salts of α-methylstyrene-acrylic acid copolymer, amine salts thereof, ammonium salts thereof, and other water-soluble resins can be used. Also, water-insoluble resins such as acrylic resins, vinyl acetate resins, styrene-butadiene copolymers, etc. can be used. Incidentally, the water-insoluble resins are used in the form of an aqueous emulsion.

[0020] In addition to the above components, various additives conventionally used in aqueous inks for writing instruments can also be used as appropriate according to need. For example, sugar alcohols such as sorbitol, xylitol, tetritol, pentitol, hexitol, inositol, maltitol, maltotritol, maltotetratol, maltopentitol, maltohexitol, maltoheptitol, etc., urea, ethylene urea, and their derivatives can be used to prevent evaporation of the ink. Specifically, PO-10, PO-20, PO-30, PO-40 (all manufactured by Towa Kasei Kogyo Co., Ltd.), SE-30, SE-100 (all manufactured by Niken Chemical Co., Ltd.), Diamond Tol L (manufactured by San-Ei Kasei Co., Ltd.), etc. can be mentioned. Also, lubricants such as polyethylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, oleic acid, acyl amino acids, taurine, and alkali metal salts or amine salts of methyl taurine can be used to improve the writing feel. Specifically, NIKKOL Sarcosinate CN-30, Sarcosinate CT-30, Sarcosinate LH, Sarcosinate LN, Sarcosinate LN-30, Sarcosinate LK-30, Sarcosinate MN, Sarcosinate OH, Sarcosinate OHV, Sarcosinate PN, CMT-30, CMT30-T, LMT, LMT-30, MMT, PMT, SMT (all manufactured by Nikko Chemicals Co., Ltd.) can be mentioned.

[0021] Furthermore, anionic surfactants such as fatty acid soaps, n-acyl amino acid salts, alkyl ether carboxylates, acylated peptides and other carboxylate salts, alkyl sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, sulfosuccinates, α-olefin sulfonates, N-acyl sulfonates and other sulfonates, sulfated oils, alkyl sulfates, alkyl ether sulfates, alkyl allyl ether sulfates, alkyl amide sulfates and other sulfate ester salts, alkyl phosphates, alkyl ether phosphates, alkyl allyl ether phosphates and other phosphate ester salts, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyl ether, polyoxyethylene monotetradecyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene polyoxypropylene cetyl ether, polyethylene glycol monostearate, polyethylene glycol distearate, monococonut oil fatty acid polyoxyethylene sorbitan, monopalmitate polyoxyethylene sorbitan, monolaurate poly Nonionic surfactants such as oxyethylene sorbitan, polyoxyethylene sorbitan monooleate, hydrogenated polyoxyethylene castor oil, decaglyceryl monolaurate, sucrose stearate, sucrose palmitate, sucrose myristicate, sucrose oleate, sucrose laurate, tetramethylammonium chloride, tetramethylammonium hydroxide, tetrabutylammonium chloride, dodecyldimethylbenzylammonium chloride, alkyltrimethylammonium chloride, alkyltrimethylammonium bromide Cationic surfactants such as benzyltrimethylammonium chloride, benzalkonium chloride, benzaltonium bromide, benzethonium chloride, dialkyldimethylammonium chloride, monomethylamine hydrochloride, dimethylamine hydrochloride, trimethylamine hydrochloride, butylpyridinium chloride, dodecylpyridinium chloride, cetylpyridinium chloride, PEG-11 methyl ether dimethicone, PEG / PPG-20 / 22 butyl ether dimethicone, PEG-9 dimethicone, PEG-3 dimethicone, PEG-9 methyl ether dimethicone, PEG-10 dimethicone,Silicone-based surfactants such as PEG-32 methyl ether dimethicone, PEG-9 polydimethylsiloxyethyl dimethicone, lauryl PEG-9 polydimethylsiloxyethyl dimethicone, polyglyceryl-3 disiloxane dimethicone, polyglyceryl-3 polydimethylsiloxyethyl dimethicone, and lauryl polyglyceryl-3 polydimethylsiloxyethyl dimethicone; fluorine-based surfactants such as perfluorobutanesulfonates, perfluoroalkyl group-containing carboxylates, perfluoroalkyl ethylene oxide adducts, and perfluoroalkyl group-containing phosphate esters; and preservatives and fungicides such as sodium dehydroacetate and 1,2-benzoisothiazarin-3-one may be used as needed. Examples of benzothiazoline-based preservatives include Proxel GXLS and Proxel GXL (manufactured by Lonza Japan Co., Ltd.). Rust inhibitors such as benzotriazole may also be used in combination. Alkalizing agents such as sodium hydroxide, monoethanolamine, diethanolamine, triethanolamine, amines, and ammonium may also be used as pH adjusters. ,

[0022] The aqueous ink composition for ballpoint pens of the present invention is preferable because it ensures writing performance and storage stability, such as writing feel, uniformity of handwriting, density of handwriting, control of so-called ink clumping (where ink forms droplets on the paper), suppression of bleeding, ink ejection stability, control of ink show-through on the paper, suppression of ink streaking, performance when the pen is dry, suppression of ink dripping, suppression of ink leakage from the gap between the ball and the tip when the ballpoint pen is not in use, suppression of ink backflow when the writing tip is left facing upwards, suppression of pigment sedimentation, and suppression of separation.

[0023] Various conventionally known methods can be used to manufacture the ink composition of the present invention. For example, it can be easily obtained by adding water or a solvent and polysaccharides to a stirrer with high shear force, such as a Henschel mixer, propeller stirrer, homogenizer, turbo mixer, or high-pressure homogenizer, stirring and dispersing, then adding the colorant and other remaining components dispersed by a disperser such as a Henschel mixer, propeller stirrer, homogenizer, turbo mixer, high-pressure homogenizer, ball mill, bead mill, or roll mill, and further mixing and stirring. In these preparation steps, the heat generated by dispersion can be used directly for stirring, or heating can be applied, or cooling can be used for stirring. Removal of foam using a degasser or filtration of coarse matter using a filter may be performed as needed. Furthermore, an aging process may be performed after ink preparation to ensure sufficient dispersibility of the polysaccharides. These various mixing, dispersion, filtering, heating, or cooling processes may be performed individually, or two or more processes may be performed in parallel. When incorporating high-density materials such as alumina, an alumina dispersion may be prepared beforehand by adding alumina to a highly viscous liquid such as an aqueous solution containing glycerin or a thickening agent and mixing and stirring to disperse it. Alternatively, if an alumina dispersion is not used, a thickening agent may be added immediately after adding alumina and mixing and stirring to increase viscosity, or alumina may be added after the thickening agent has been added and mixed and stirred. Substances that are poorly soluble in deionized water, such as benzotriazole, may be prepared beforehand by adding benzotriazole to ethylene glycol and mixing and stirring to prepare a benzotriazole-ethylene glycol solution before incorporating it. Substances that are poorly soluble in deionized water when not neutralized, such as sarcosinate OHV, may be prepared beforehand by neutralizing sarcosinate OHV with NaOH or triethanolamine to prepare a neutralized aqueous solution of sarcosinate OHV before incorporating it. Deliquescent substances such as sodium hydroxide may be prepared beforehand by adding sodium hydroxide to deionized water and mixing and stirring to prepare an aqueous sodium hydroxide solution before incorporating it.

[0024] Furthermore, by placing an ink backflow prevention body at the ink interface within the ink reservoir tube, unintended movement of ink to the opposite side of the pen tip and ink leakage from the rear opening of the ink reservoir tube due to such movement can be suppressed. When the ink backflow prevention body is a liquid composition, non-volatile and / or low-volatility liquids can be used. Specifically, examples include petrolatum, 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, polyether-modified silicone oil, fatty acid-modified silicone oil, etc. These non-volatile and / or low-volatility liquids may be used alone or in mixtures of two or more. The non-volatile and / or low-volatility liquid is preferably thickened to a suitable viscosity by adding a gelling agent. Examples of such gelling agents include hydrophobic silica, methylated silica, aluminum silicate, swollen mica, clay-based thickeners such as hydrophobic bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, tripenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, dextrin compounds such as fatty acid dextrin, and cellulose compounds. Among these, fatty acid metal soaps, fatty acid dextrins, and amide-modified polyethylene waxes are suitable for use because they provide excellent solvent resistance for the gel. In addition, alcohol-based solvents, glycol-based solvents, surfactants, resins, fine particles of metal oxides, etc., can be added to adjust gel strength and viscosity, prevent discoloration of the backflow prevention body, and provide backflow prevention function. Furthermore, a solid such as a columnar synthetic resin object, referred to as a float, may be placed within the ink backflow prevention composition to narrow the space in which the apparent backflow prevention composition is located, thereby making it less likely to move under external force and improving impact resistance.

[0025] Hereinafter, several embodiments of a ballpoint pen using the aqueous ink composition for ballpoint pens of the present invention will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described as embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples.

[0026] Figure 1 is a longitudinal cross-sectional view showing a writing instrument according to one embodiment. Figure 2 is a longitudinal cross-sectional view showing the refill portion of the writing instrument shown in Figure 1. As shown in Figure 2, the refill 200 comprises a ballpoint pen tip 1 as a writing section and an ink storage tube 3 as an ink storage section in which the ink composition 2 supplied to the ballpoint pen tip 1 (writing section) is stored. The ink storage tube may be made of a transparent material or an opaque material, and illustrations or other designs may be written on or colored on the ink storage tube, or it may be decorated with a transfer film or the like. Using a transparent material for the ink storage tube is preferable because the amount of ink remaining and the color of the ink can be visually confirmed. Using an opaque material or a transparent material that blocks ultraviolet rays for the ink storage tube is preferable because it can suppress deterioration and discoloration of the ink due to ultraviolet rays. The inner diameter of the ink storage tube may be 1.0 mm or more and 5.0 mm or less. In particular, an inner diameter of 1.0 mm or more and 3.1 mm or less is preferable because it provides good shape retention for the ink backflow prevention body, preventing the ink backflow prevention body from flowing out, and preventing the ink backflow prevention body from flowing out even without using a float in contact with the ink backflow prevention body. The thickness of the ink storage tube can be determined by subtracting the inner diameter from the outer diameter, and the thickness of the ink storage tube may be between 0.5 mm and 10.0 mm. A thickness of 1.0 mm to 10.0 mm provides high gas barrier properties, preventing solvent evaporation of the ink, and a thickness of 2.8 mm to 10.0 mm is even more preferable as it provides particularly high gas barrier properties.

[0027] In the exemplary embodiments shown in Figures 1 and 2, the writing instrument 100 comprises a refill 200 and an outer casing 300. The outer casing may be made of a transparent or opaque material. Using transparent materials for the outer casing and ink reservoir tube is preferable because the amount of ink remaining and the color of the ink can be seen without removing the casing. Using transparent materials for the outer casing and adding illustrations or coloring to the ink reservoir tube is preferable because the illustrations and coloring of the ink reservoir tube can be seen without removing the casing. Furthermore, using transparent materials for the outer casing and an ink reservoir tube of the same color as the ink allows the ink color to be seen without writing. Using opaque materials or transparent materials that block ultraviolet rays for the casing is preferable because it suppresses deterioration and discoloration of the ink due to ultraviolet rays. The outer casing may be decorated with illustrations or coloring, or decorated with transfer film, etc. One or more types of luminous pigments such as aluminum flakes, glass flakes, and pearl pigments can be used as appropriate in the materials of the outer casing and ink reservoir tube.

[0028] In the embodiment shown in Figure 1, the outer casing 300 consists of a shaft cylinder 4, the shaft cylinder 4 having a front shaft 5 and a rear shaft 6 that are detachably fixed by screws. The surface of the front shaft 5, which is formed from a relatively hard resin material, is covered with a relatively soft resin material (soft member) as a grip portion 7. Examples of the relatively hard resin material forming the front shaft 5 and rear shaft 6 include polycarbonate, polyethylene terephthalate, acrylic, acrylonitrile butadiene styrene copolymer (ABS), acrylonitrile styrene copolymer (AS), polypropylene, etc., and either a transparent or opaque member may be used. Examples of the relatively soft resin material (soft member) forming the grip portion 7 include thermoplastic elastomer, soft acrylic, etc., and either a transparent or opaque member may be used. The grip portion 7 is preferably a grip that is less likely to slip when held, such as a grip with irregularities on the surface, a triangular grip, a grip with a polygonal outer surface, or a grip shaped to resemble a fingerprint. The cap 8 is attached and fixed to the rear of the rear shaft 6 by a screw-in mechanism while being inserted into the inner bore of the rear shaft 6, and the portion exposed from the rear end of the rear shaft 6 is positioned to cover the base surface of the clip 9 attached to the outer surface of the rear shaft 6. The cap 8 is cylindrical in shape, and a groove formed inside it serves as the cam groove of the David Cam mechanism, regulating the sliding position of the internal rotor 10, and defining the forward and backward movement position of the ballpoint pen refill 200 connected to it as the rotor 10 rotates due to the pushing operation of the knock 11. A ballpoint pen refill 200 is positioned inside the barrel 4 so as to be movable back and forth. An elastic member 12, such as a coil spring, is positioned in front of the ballpoint pen refill 200, biasing the ballpoint pen refill 200 toward the rear. The rear end of the ballpoint pen refill 200 abuts against the tip of the rotor 10. In other words, the ballpoint pen refill 200 extends and retracts from the tip opening of the barrel 4 when the knock 11 is pressed.

[0029] As shown in Figure 2, the refill 200 has a ballpoint pen tip 1 having a writing ball 13, which is a writing element, and a ball holder 14 that rotatably holds the writing ball 13, and an ink reservoir tube 3 connected to the ballpoint pen tip 1 via a tip holder 15 having a through hole. The ball holder 14 holds the writing ball 13 so that it partially protrudes from the tip opening of the ink passage hole, which is formed as a through-hole. The writing ball 13 can be a ball with a diameter of 0.18 mm or more and 2.0 mm or less. A ball with a diameter of 0.3 mm or more and 1.6 mm or less is preferred because it is less affected by the unevenness of the writing surface and provides a smooth writing feel. A ball with a diameter of 0.8 mm or more and 1.0 mm or less is even more preferred because it can achieve both a smooth writing feel and neat handwriting. Furthermore, the ink container 3 contains the ink composition 2, and an ink backflow prevention body 16, which is incompatible with the ink composition 2, is placed in contact with the rear end interface of the ink composition 2, and a float 17 is placed in contact with the ink backflow prevention body 16. It is also possible to create a ballpoint pen body without an outer casing 300 by placing a tail plug or the like at the rear end of the ink container 3 of the refill 200 to prevent leakage of the ink composition 2. Additionally, it is possible to place a pen tip protection member such as a cap.

[0030] Figure 3 is a diagram showing the configuration of the ballpoint pen tip 1 of a ballpoint pen refill 200 according to one embodiment, and is an enlarged longitudinal cross-sectional view of part I in Figure 2. The ballpoint pen tip 1 shown in Figure 3 rotatably holds a writing ball 13, which is a writing member, within a ball holder 14, with a portion of it protruding from the tip opening of the ink passage hole, which is a through hole. Behind the writing ball 13, an intermediate ball 18 is rotatably arranged in contact with the writing ball 13, and further behind the intermediate ball 18, a coil spring 19, which is a resilient member, is arranged in contact with the intermediate ball 18. The coil spring 19 is inserted from the rear of the ball holder 14 and pushed in to compress its entire length and prevent it from coming out. The restoring force due to this compression biases the intermediate ball 18 forward, and via the intermediate ball 18, biases the writing ball 13 forward. The rear end of the coil spring 19 is received by four protrusions 20 provided at equal intervals around the rear inner wall surface of the ball holder 14, and is prevented from coming out from inside the ball holder 14. This protrusion 20 is formed by broaching the inner wall surface of the rear end of the ball holder 14 and creating a cut piece. In addition to broaching, the protrusion 20 may also be formed by punching or other methods to create a recess on the side wall of the ball holder 14, or by using a separate component, etc., so the method and shape of preventing the coil spring 19 from coming off can be selected as appropriate.

[0031] The writing ball 13 moves backward when pressed against a writing surface such as paper, and ink flows out through the gap formed between it and the ball holder 14 (described later), or is transported outwards as the ball rotates and transferred. The size of the writing ball 13 can be any size with a diameter of 0.18 mm to 2.0 mm, which is commonly used in ballpoint pens. Considering the writing feel and abrasion resistance with the ball holder, the arithmetic mean height (Sa) of the surface is preferably between 2 nm and 25 nm. The writing ball can be made from various materials, including cemented carbide mainly composed of tungsten carbide, metals such as stainless steel, aluminum, and iron, resin materials such as polyethylene, polypropylene, polyacetal, and polyamide, and ceramics and glass, which can be polished. However, considering the sliding properties with the intermediate ball, abrasion resistance, and corrosion resistance from ink, stainless steel, cemented carbide, and ceramics are preferred.

[0032] The intermediate ball 18 is rotatably positioned in contact with the writing ball within the ink passage hole behind the writing ball. The size of the intermediate ball is not particularly limited, but considering the fluidity of the ink, the diameter of the intermediate ball is preferably 30% to 160% of the diameter of the writing ball, and considering the frictional resistance between it and the writing ball 13, the arithmetic mean height (Sa) of the surface is preferably 2 nm to 25 nm. The material of the intermediate ball 18 can be cemented carbide mainly composed of tungsten carbide, metals such as stainless steel, aluminum, and iron, resin materials such as polyethylene, polypropylene, polyacetal, and polyamide, or ceramics and glass, which can be polished. However, cemented carbide and ceramics are preferred considering sliding properties with the writing ball, wear resistance, and corrosion resistance from ink.

[0033] In this embodiment, the ballpoint pen tip is configured with an intermediate ball 18 positioned between the writing ball 13 and the coil spring 19 as described above, for the purpose of improving the writing feel. However, it is also acceptable to have a configuration in which the coil spring 19 and the writing ball 13 are in direct contact without the intermediate ball 18, or to form a straight tip portion at the end of the coil spring 19 by extending the coil wire straight up, and the writing ball 13 is in contact with this straight tip portion, thereby directly biasing the writing ball 13 forward with the coil spring. Furthermore, if the ballpoint pen is designed in a way that protects the ballpoint pen tip with a cap when not in use, a so-called capped ballpoint pen, problems such as ink seepage from the tip and skipping due to ink drying are less likely to occur. Therefore, it is not necessary to bias the writing ball 13 forward to ensure airtightness, and the coil spring 19 and intermediate ball 18 can be omitted.

[0034] Next, the details of the ballpoint pen tip 1 will be explained in Figure 4, which is an enlarged view of part II in Figure 3. The ball holder 14 has an ink passage hole which is a through hole. This ink passage hole has a tip opening 21 which is crimped to a smaller diameter from the tip side, a writing ball holding part 23 which is divided by an internal protrusion 22 and in which the writing ball 13 is positioned with a portion protruding from the tip opening 21, a central hole 24 formed in the center of the internal protrusion 22, and a rear hole 25. The inner edge of the tip opening 21 is mirror-finished by pressing it against the writing ball 13 during the crimping process, thereby transferring the curved surface of the writing ball 13 and improving the sealing performance when the writing ball 13 is pressed against it by the coil spring 19 via the intermediate ball 18. In addition, multiple ink passage grooves 26 are formed radially and at equal intervals on the inward projection 9 by cutting. These ink passage grooves 26 are made to penetrate to the rear hole 25 to ensure reliable ink supply to the writing ball holding portion 23, but they may also be made to stop midway through the central hole 24 without penetrating to the rear hole 25. Furthermore, a concave ball-receiving seat 27 is formed by pressing the writing ball 13 against the inward projection 9. The ball-receiving seat 27 stabilizes the position of the writing ball 13 when it retracts upon contact with the paper surface during writing, ensuring smooth rotation with minimal unwanted vibration. The shape is such that the writing ball 13 and the ball-receiving seat 27 make substantially surface contact. The ink passage groove 26 has an opening outside the ball-receiving seat 27 formed on the inward projection 9, ensuring ink supply to the writing ball holding portion 23. In this embodiment, five ink passage grooves 26 are formed circumferentially at equal intervals, but their size and number are not particularly limited.

[0035] Figure 5 is a longitudinal cross-sectional view showing a writing instrument with a cap placed on the pen tip according to one embodiment. In the writing instrument of Figure 5, a cap 28 is detachably attached to the pen tip to protect it. The cap 28 also includes a clip 9. The pen tip has a ballpoint pen tip 1, which is a writing member, and an ink reservoir tube 3 connected to the ballpoint pen tip 1 via a tip holder 15 having a through hole. A ballpoint pen tip like those shown in Figures 3 and 4 may be used as the ballpoint pen tip 1, which is the writing member. The surface of the ink reservoir tube 3, which is formed from a relatively hard resin material, is covered with a relatively soft resin material (soft member) as a grip portion 7. One example of the relatively hard resin material forming the ink reservoir tube 3 is polycarbonate, polyethylene terephthalate, acrylic, acrylonitrile butadiene styrene copolymer (ABS), acrylonitrile styrene copolymer (AS), polypropylene, etc. Another example of the relatively soft resin material (soft member) forming the grip portion 7 is thermoplastic elastomer, soft acrylic, etc. The grip portion 7 is preferably a grip that is less likely to slip when held, such as a grip with an uneven surface, a triangular grip, a grip with a polygonal outer surface, or a grip shaped to resemble a fingerprint. The ink container 3 contains an ink composition 2, and an ink backflow prevention body 16 that is incompatible with the ink composition 2 is placed in contact with the rear end interface of the ink composition 2, and a float 17 is placed in contact with the ink backflow prevention body 16. The rear end of the ink container 3 is provided with a tail plug 29 to prevent leakage of the ink composition 2. The ballpoint pen tip 1 is protected by a packing 30 embedded inside the cap 28, and airtightness is maintained to prevent ink drying. The packing 30 is made of an elastic material such as nitrile butadiene rubber, silicone rubber, or butyl rubber, but can be appropriately selected depending on the type of ink used and the material of the cap. If it is not necessary to protect the ballpoint pen tip with a packing or to maintain airtightness, a packing may not be used. When using the writing instrument, the removed cap 28 can also be placed over the tail plug end of the ink reservoir tube 3.The ink reservoir tube, grip section, tip holder, and cap may be made of transparent or opaque material. Using transparent material for the ink reservoir tube, grip section, tip holder, and cap is preferable because the remaining ink level and ink color can be seen without removing the cap. Using transparent material for the cap and adding illustrations or coloring to the ink reservoir tube, grip section, and tip holder is preferable because the illustrations and color of the ink reservoir tube can be seen without removing the cap. Using opaque material or a transparent material that blocks ultraviolet light for the ink reservoir tube, grip section, tip holder, and cap is preferable because it can suppress deterioration and discoloration of the ink due to ultraviolet light.

[0036] In the above, retractable ballpoint pens and capped ballpoint pens were described as examples of ballpoint pens. However, some embodiments of ballpoint pens may be configured to assist in the ejection of the ink composition during writing by pressure such as compressed gas. [Examples]

[0037] The present invention will be described in detail below with reference to examples.

[0038] (Preparation of ink composition) Ink compositions for Examples 1-26 and Comparative Examples 1-17, having the compositions shown in Tables 1-7, were prepared. The following materials were specifically used for each composition shown in Tables 1-7.

[0039] <Main solvent> MS: Ion-exchanged water <Organic solvents> SOL-1: Ethylene glycol SOL-2: Glycerin SOL-3: Thiodiglycol

[0040] <Coloring agent> Coloring agent-1: Water Black #256L (14% aqueous solution of black dye, manufactured by Orient Chemical Industry Co., Ltd.) Coloring agent-2: Water Yellow #1 (CI Acid Yellow 23, manufactured by Orient Chemical Industry Co., Ltd.) Coloring agent-3: Daiwa Red No. 103WB (CI Acid Red 87, manufactured by Daiwa Chemical Co., Ltd.) Coloring agent-4: Daiwa Red No. 104WB (CI Acid Red 92, manufactured by Daiwa Chemical Co., Ltd.) Coloring agent-5: Water Yellow #6C (CI Acid Yellow 42, manufactured by Orient Chemical Industry Co., Ltd.) Coloring agent-6: Water Blue #119 (triphenylmethane-based blue dye, molecular formula C51H56N3NaO7S2, manufactured by Orient Chemical Industry Co., Ltd.) Coloring agent-7: Daiwa Red No. 106WB (CI Acid Red 52, manufactured by Daiwa Chemical Co., Ltd.) Coloring agent-8: Daiwa Blue No. 1 (CI Acid Blue 9, manufactured by Daiwa Chemical Co., Ltd.) Coloring agent-9: Daiwa IJ Yellow 306H (CI Direct Yellow 123, manufactured by Daiwa Chemical Co., Ltd.)

[0041] <Polyoxyethylene cetyl ether> PC-1:BC-5.5 (Polyoxyethylene cetyl ether (HLB value 10.5), manufactured by Nikko Chemicals Co., Ltd.) PC-2:BC-2 (Polyoxyethylene cetyl ether (HLB value 8.0), manufactured by Nikko Chemicals Co., Ltd.) PC-3:BC-7 (Polyoxyethylene cetyl ether (HLB value 11.5), manufactured by Nikko Chemicals Co., Ltd.) PC-4: EMALEX 115 (Polyoxyethylene cetyl ether (HLB value 13.0), manufactured by Nippon Emulsion Co., Ltd.) PC-5: EMALEX 125 (Polyoxyethylene cetyl ether (HLB value 15.0), manufactured by Nippon Emulsion Co., Ltd.) PC-6: EMALEX 104 (Polyoxyethylene cetyl ether (HLB value 7.0), manufactured by Nippon Emulsion Co., Ltd.)

[0042] <2-Pyridinethiol 1-oxide sodium> SO: Sun Eye Back Sodium Omajin (Sodium 2 - pyridinethiol 1 - oxide (45% solution), manufactured by Mihama Oil Co., Ltd.)

[0043] <Additive> Additive - 1: Benzotriazole Additive - 2: Proxel GXL(S) (20% dipropylene glycol solution of 1,2 - benzisothiazolin - 3 - one, manufactured by Lonza Japan Co., Ltd.) Additive - 3: AKP - 50 (Fine particle alumina (median particle size 0.20μm), manufactured by Sumitomo Chemical Co., Ltd.) Additive - 4: AKP - 20 (Fine particle alumina (median particle size 0.46μm), manufactured by Sumitomo Chemical Co., Ltd.) Additive - 5: Potassium hydroquinone sulfonate Additive - 6: Sarcosinate OHV (N - oleoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.)

[0044] <Polysaccharide> Polysaccharide: Kelzan AR (Xanthan gum, manufactured by Sankyo Co., Ltd.)

[0045] <pH adjuster> pH adjuster: Sodium hydroxide

[0046] The ink compositions of Examples 1 - 26 and Comparative Examples 1 - 17 were prepared as follows. The total amount of Kelzan AR as a polysaccharide was added to 10% by weight of ion - exchanged water while stirring with a propeller stirrer, and stirred for 1 hour to obtain an aqueous Kelzan AR solution. Then the remaining components were mixed, heated and stirred for 1 hour to dissolve uniformly, and then the aqueous Kelzan AR solution was added and stirred for another 2 hours to obtain an aqueous ink composition.

[0047] The ink compositions of Examples 1-26 and Comparative Examples 1-17 were filled into refills 200 based on the example shown in Figure 2, and housed in an outer casing 300 based on the example shown in Figure 1 to obtain test sample ballpoint pens. For the test sample ballpoint pens, two types of ballpoint pen tips were prepared based on the example shown in Figure 3, with writing ball diameters of 0.8 mm and 1.0 mm. The diameter of the intermediate ball 18 was set to 0.8 mm regardless of the size of the writing ball. The material of the writing ball and intermediate ball was a cemented carbide mainly composed of tungsten carbide, with chromium and cobalt as binder components, sintered together. The test ballpoint pen tip with a writing ball diameter of 0.8 mm was designated as the first ballpoint pen tip (indicated as the first tip in the table), and the test ballpoint pen tip with a writing ball diameter of 1.0 mm was designated as the second ballpoint pen tip (indicated as the second tip in the table).

[0048] The combinations of the ink compositions of Examples 1-26 and Comparative Examples 1-17 with the first and second ballpoint pen tips are shown in the table (indicated by ○ in the corresponding column of the table).

[0049] The tip holder 15 of the test sample ballpoint pen was molded from polybutylene terephthalate resin based on the example shown in Figure 2, and the minimum inner diameter of the through hole 4 from the rear of the ballpoint pen tip 1 to the ink reservoir tube 3 was set to 0.75 mm.

[0050] The ink reservoir tube 3 of the test sample ballpoint pen used a pipe molded by extrusion molding of polypropylene resin, based on the example shown in Figure 2, with an inner diameter of 4.65 mm and a thickness of 0.75 mm. It was filled with 1.0 g of ink composition and 0.1 g of ink backflow prevention composition. The ink backflow prevention composition was prepared by gelling polybutene with fine silica particles and dextrin fatty acid ester.

[0051] The following tests were conducted using the sample ballpoint pens described above.

[0052] (Ball surface roughness test) The surface roughness (arithmetic mean roughness (Ra)) of the writing balls of test samples, both initially and after time had passed (ballpoint pens were left in a constant temperature bath at 50°C and 30%RH with the pen tip facing downwards for 90 days), was measured using a scanning probe microscope SPI-400 (manufactured by Hitachi High-Tech Science Corporation) for an arbitrary 20 μm × 20 μm area (unit: nm). A smaller surface roughness indicated a less uneven surface of the writing ball.

[0053] (Smoothness of writing test) Initial and post-treatment test samples (ballpoint pens left in a constant temperature bath at 50°C and 30%RH with the pen tip facing downwards for 90 days) were tested using a Tribo-master (Type: TL201Sa) manufactured by Trinity Lab Co., Ltd. on the f-side of high-quality paper (Kinmari SW manufactured by Hokuetsu Corporation, paper thickness (JIS P 8118) 95±3μm, smoothness of the f-side (felt side (surface)) (JIS P 8155) 65±20 seconds). Under writing conditions of a writing speed of 7cm / sec, a writing angle of 70°, and a writing load of 100gf, the writing resistance value (unit: gf) applied in the writing direction was measured, and a lower writing resistance value was evaluated as indicating a smoother writing experience.

[0054] [Table 1]

[0055] [Table 2]

[0056] [Table 3]

[0057] [Table 4]

[0058] [Table 5]

[0059] [Table 6]

[0060] [Table 7]

[0061] The water-based ink compositions for ballpoint pens in Examples 1 to 26 maintained a good writing feel even after a long period of time, with the surface of the writing ball remaining smooth and even after prolonged use. In particular, in Examples 1-15, polyoxyethylene cetyl ether and 2-pyridinethiol 1-oxide sodium formed a denser film through hydrophobic interaction, reducing contact with water and oxygen on the ball surface, preventing the leaching of ball components, resulting in a smooth writing surface, suppressing ball corrosion, and maintaining a particularly smooth writing feel.

[0062] In contrast, Comparative Example 1 did not contain polyoxyethylene cetyl ether, Comparative Example 2 did not contain 2-pyridinethiol 1-oxide sodium, and Comparative Examples 3 to 17 did not contain either polyoxyethylene cetyl ether or 2-pyridinethiol 1-oxide sodium. As a result, the ball surface came into contact with water and oxygen more frequently, causing the ball components to dissolve over time, resulting in an uneven surface on the writing ball and a loss of smooth writing.

[0063] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0064] In this specification, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equivalent state shall not only describe a state of being strictly equal, but also describe a state in which tolerances or differences exist to the extent that the same function can be obtained. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components. [Explanation of Symbols]

[0065] 1 Ballpoint pen tip 2. Ink composition 3 ink storage tubes 4 shaft cylinder 5 Front axle 6 rear axle 7. Grip section 8 crown 9 clips 10 rotors 11 knocks 12 Resilient components 13 Writing ball 14 Ball Holder 15 Chip holder 16. Ink backflow prevention element 17 Floats 18 Intermediate Ball 19 Coil springs 20 Convex part 21 Tip opening 22 Internal protrusion 23. Writing ball holder section 24 Center hole 25 Posterior foramen 26 Ink passage grooves 27 Ball bearing seat 28 caps 29. Tail plug 30 packing 100 writing instruments 200 refills 300 Exterior

Claims

1. A water-based ink composition for ballpoint pens comprising at least water, a coloring agent, and polyoxyethylene cetyl ether and 2-pyridinethiol 1-oxide sodium as film-forming agents for the ball surface.

2. The amount of 2-pyridinethiol 1-oxide sodium added is 0.001% by weight or more and 1.0% by weight or less, relative to the total amount of the aqueous ink composition for the ballpoint pen. The aqueous ink composition for ballpoint pens according to claim 1.

3. The amount of polyoxyethylene cetyl ether added is 0.1% by weight or more and 3.0% by weight or less of the total amount of the aqueous ink composition for the ballpoint pen. A water-based ink composition for ballpoint pens according to claim 1 or claim 2.

4. The HLB value of the aforementioned polyoxyethylene cetyl ether is 8 or higher and less than 14. A water-based ink composition for ballpoint pens according to claim 1 or claim 2.

5. The HLB value of the aforementioned polyoxyethylene cetyl ether is 8 or higher and less than 14. The aqueous ink composition for ballpoint pens according to claim 3.

6. A water-based ballpoint pen refill comprising at least an ink storage tube containing the water-based ink composition for ballpoint pens according to claim 1 or claim 2, and a ballpoint pen tip comprising at least a writing ball and a ball holder that rotatably holds the writing ball, The ball holder has an intermediate ball positioned behind the writing ball that can rotate while in contact with the writing ball. Refill for water-based ballpoint pens.

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