Oil-based ink for ballpoints

Abstract

PURPOSE: To provide an oil-based ink for ballpoints with reduced ink leakage from a pen tip even under a low humidity environment.CONSTITUTION: An oil-based ink for ballpoints comprises at least silicone composite particles having a structure in which silicone rubber particles are coated with silicone resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-based ink for a ballpoint pen. [Background technology]

[0002] As a technology for suppressing ink leakage from the nib of oil-based ink for ballpoint pens, Patent Document 1 discloses ink for ballpoint pens containing spherical silicone resin microparticles. Patent Document 2 discloses an ink composition for oil-based ballpoint pens containing a salt-forming dye having a specific structure and 70% or more of a polyvinyl butyral resin relative to the total resin content in the ink composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-134391 [Patent Document 2] Patent Publication No. 2017-110067 Summary of the Invention [Problem to be solved by the invention]

[0004] In the invention of Patent Document 1, the silicone particles break when sandwiched between the ball and the receiving seat during writing, causing the particle shape to become uneven, which reduces the sealing effect due to crowding where the ink flow path narrows, and in low-humidity, dry environments, the ink leaks out because the ink leaks out due to the reduced fluidity caused by the precipitation of solids in the ink components by moisture in the air at the pen tip.In the invention of Patent Document 2, in high-humidity environments, the solids in the ink that appear on the pen tip surface precipitate due to the influence of moisture in the air, and the ink leathers on the pen tip surface, thereby sealing the pen tip surface, and thus preventing ink leakage.However, in low-humidity, dry environments, the precipitation rate of the solids in the ink is slow and the ink does not easily leather on the pen tip surface, so the ink leakage prevention effect is not achieved and ink leaks out. Furthermore, when the pen tip is not retracted and is pressed against a display or the like, the ball at the pen tip is pressed against the ball receiving seat, opening the ink flow path, which creates the problem of not being able to prevent ink from leaking from the pen tip.

[0005] An object of the present invention is to provide an oil-based ink for ballpoint pens that can prevent ink from leaking from the pen tip even in a low-humidity environment. [Means for solving the problem]

[0006] That is, a first aspect of the present invention is an oil-based ink for ballpoint pens characterized by containing at least silicone composite particles having a structure in which silicone rubber particles are coated with a silicone resin; a second aspect is an oil-based ink for ballpoint pens as described in the first aspect, in which the average particle size of the silicone composite particles is 0.1 μm or more and less than 1.0 μm; and a third aspect is an oil-based ink for ballpoint pens as described in the first or second aspect, in which hydroxypropyl cellulose is contained. [Effects of the Invention]

[0007] The silicone composite particles contained in the oil-based ink for ballpoint pens of the present invention have a structure in which silicone rubber particles are coated with a silicone resin. Therefore, due to the synergistic effect of the low cohesion properties resulting from the low intermolecular forces and low adhesiveness of the silicone resin coating the silicone composite particles, and the elasticity of the silicone rubber inside the silicone composite particles, the particles are not broken by the impact of being sandwiched between the ball and the receiving seat during writing, and can be concentrated without forming an aggregated structure where the ink flow path narrows, which is thought to provide an excellent sealing effect and make it possible to suppress ink leakage. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below.

[0009] The silicone composite particles of the present invention have a structure in which the silicone rubber particles are coated with a silicone resin. These composite particles have an internal silicone skeletal structure of M units and D units, and are linear polymers, resulting in elastic silicone rubber, and an external silicone skeletal structure of T units and Q units, which are branched and therefore crosslinked in a three-dimensional network. The M unit, D unit, T unit, and Q unit of silicone are terms that indicate how many organic substituents are attached to the silicon of silicone, with M unit representing silicon with three organic substituents, D unit representing silicon with two organic substituents, T unit representing silicon with one organic substituent, and Q unit representing silicon with no organic substituents. The rubber hardness can be appropriately set by changing the ratio of each unit of the silicone skeleton in the silicone rubber portion. The rubber hardness is preferably 25 to 80 inclusive, more preferably 50 to 80 inclusive, in terms of durometer type A, so that the silicone composite particles deform when sandwiched between the ball and the ball seat, and then immediately restore their original shape when the gap between the seat and the ball widens after writing, and disperse into the ink flow path. The particle size of the silicone composite particles is appropriately selected so that they can be ejected from the ballpoint pen tip, and those of 0.1 μm or more and less than 12 μm are preferably used. Of these, the use of silicone composite particles of less than 1.0 μm is even more preferred, as this further increases the density during sealing and further improves the effect of suppressing ink leakage from the pen tip. The particle size of the silicone composite particles represents the average particle size, and the average particle size is measured using a laser diffraction / scattering particle size distribution measuring device (e.g., SALD-7100 manufactured by Shimadzu Corporation), and the volume-based average particle size is calculated based on the measured value. In order to obtain silicone composite particles of the desired particle size, the particle size distribution can be adjusted by sieving, centrifugation, or filtration.

[0010] Specific examples of the silicone composite particles used in the oil-based ink for ballpoint pens used in the present invention include KMP-600 (average particle size 5 μm, rubber hardness 30 durometer A, true specific gravity 0.99 g / cm), KMP-601 (average particle size 12 μm, rubber hardness 30 durometer A, true specific gravity 0.98 g / cm), KMP-602 (average particle size 30 μm, rubber hardness 30 durometer A, true specific gravity 0.98 g / cm), KMP-605 (average particle size 2 μm, rubber hardness 75 durometer A, true specific gravity 0.99 g / cm), and X-52-7030 (average particle size 0.8 μm, rubber hardness 75 durometer A, true specific gravity 1.01 g / cm) (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0011] The silicone composite particles can be used alone or in combination, and the amount used is preferably 0.01 to 10.0% by weight, and more preferably 0.05 to 3.0% by weight in consideration of ink leakage prevention and writing performance.

[0012] When adding the silicone composite particles to the ink, they may be added directly or in the form of a dispersion in advance. As the dispersion medium, organic solvents used in oil-based inks for ballpoint pens can be used, and in particular, alcohols, glycols, and glycol ethers are preferred from the viewpoints of safety and odor.Examples of organic solvents include ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, and triethylene glycol monomethyl ether. glycol ethers such as ethylene glycol, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol tertiary butyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, 3-methyl-3-methoxy-1-butyl acetate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, octylene glycol,Examples of suitable esters include glycols such as glycerin, polyethylene glycol, 3-methyl-1,3-butanediol, 1,3-propanediol, 1,3-butanediol, and 1,5-pentanediol; alcohols such as benzyl alcohol, β-phenylethyl alcohol, α-methylbenzyl alcohol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, 3-methyl-3-methoxypentanol, lauryl alcohol, tridecyl alcohol, isodecyl alcohol, and isotridecyl alcohol; ethers such as methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, and 2-ethylhexyl ether; and esters such as 2-ethylhexyl acetate, isobutyl isobutyrate, ethyl lactate, and butyl lactate.

[0013] Furthermore, surfactants and dispersing resins can be used as dispersants, and examples thereof include nonionic surfactants, acrylic copolymers, polyvinyl butyral resins, phosphate polyesters, phosphate-based polymers, copolymers having acidic groups, alkylol ammonium salts of copolymers containing acid groups, and hydroxyl group-containing carboxylic acid esters.

[0014] It is preferable to use polyvinyl butyral as the dispersant, and it is even more preferable to use a dispersant with an acid value of 100 mgKOH / g or more in combination, as this improves the dispersion stability of the silicone composite particles and provides long-term storage stability. Specific examples of polyvinyl butyral include S-LEC BL-1, BL-1H, BL-2, BL-2H, BL-5, BL-10, BL-S, BX-L, BM-1, BM-2, BM-5, BM-S, BH-3, BH-6, BH-S, BX-1, BX-5, KS-10, KS-1, KS-3, and KS-5 (all manufactured by Sekisui Chemical Co., Ltd.), Mowital B 14 S, B 16 H, B 20 H, B 30 T, B 30 H, B 30 HH, B 45 H, B 60 T, B 60 H, B 60 HH, and B 75 H. (All manufactured by Kuraray Co., Ltd.), and specific examples of dispersants with an acid value of 100 mg KOH / g or more include DISPERBYK-102 (acid value 129 mg KOH / g), DISPERBYK-106 (acid value 132 mg KOH / g, amine value 74 mg KOH / g), DISPERBYK-111 (acid value 129 mg KOH / g), BYK-P104 (acid value 180 mg KOH / g), BYK-P104S (acid value 150 mg KOH / g), BYK-P105 (acid value 365 mg KOH / g), and BYK-220S (acid value 100 mg KOH / g) (all manufactured by BYK Japan Co., Ltd.). The amine value expressed here is expressed as the number of milligrams (mg) of potassium hydroxide (KOH) equivalent to the amount of hydrochloric acid required to neutralize the primary, secondary, and tertiary amines contained in 1 g of sample.

[0015] The dispersants can be used alone or in combination, and are preferably used in an amount of 10% by weight to 200% by weight based on the silicone composite particles.

[0016] In the present invention, the silicone composite particles can be dispersed by a conventional method. For example, the silicone composite particles, a solvent, and a dispersant are mixed and uniformly stirred using a propeller stirrer or the like, and then the silicone composite particles are dispersed using a disperser. The disperser, such as a kneader, roll mill, ball mill, sand mill, bead mill, Henschel mixer, homogenizer, high-pressure homogenizer, or thin-film rotary high-speed mixer, is appropriately selected depending on the amount of solvent in the ink and the pigment concentration. Among these, dispersion using a high-pressure homogenizer or a thin film rotary high-speed mixer is preferred from the viewpoint of enhancing the storage stability of the dispersion.

[0017] An aging step may be carried out in advance to improve the dispersion stability of the silicone composite particles, or components in the ink may be added in advance when dispersing the silicone composite particles to prevent aggregation due to solvent shock with the components in the ink.

[0018] The organic solvent used in the present invention is not particularly limited as long as it is one that has been used in conventional oil-based inks for ballpoint pens, and alcohols, glycols and glycol ethers are particularly preferred from the viewpoints of safety and odor.

[0019] Specific examples of organic solvents include ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, diethylene glycol dibutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono-2-ethylhexyl ether, and triethylene glycol monomethyl ether. glycol ethers such as ethylene glycol, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol tertiary butyl ether, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, 3-methyl-3-methoxy-1-butyl acetate, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, octylene glycol,Examples of suitable organic solvents include glycols such as glycerin, polyethylene glycol, 3-methyl-1,3-butanediol, 1,3-propanediol, 1,3-butanediol, and 1,5-pentanediol; alcohols such as benzyl alcohol, β-phenylethyl alcohol, α-methylbenzyl alcohol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-methoxy-1-butanol, 3-methyl-3-methoxy-1-butanol, 3-methyl-3-methoxypentanol, lauryl alcohol, tridecyl alcohol, isodecyl alcohol, and isotridecyl alcohol; ethers such as methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, and 2-ethylhexyl ether; and esters such as 2-ethylhexyl acetate, isobutyl isobutyrate, ethyl lactate, and butyl lactate. The use of a low-boiling organic solvent in part facilitates lowering the viscosity of the ink, making it suitable for a lighter writing experience. The low-boiling organic solvent that can be suitably used is an organic solvent selected from glycols and glycol ethers having a boiling point of 140°C or higher and 200°C or lower, and specific examples thereof include hexylene glycol, 3-methoxy-1-butanol, 3-methoxy-3-methyl-1-butanol, diethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, and ethylene glycol monoisobutyl ether. Considering the improvement in writing feel due to the lower viscosity and the resistance of the pen tip to drying, it is preferable to use a low-boiling organic solvent selected from alcohols, glycols, and glycol ethers having a boiling point of 80°C to 200°C inclusive, in combination with a high-boiling organic solvent having a boiling point of over 200°C. The weight ratio of low-boiling organic solvent / high-boiling organic solvent is preferably 1.0 to 30.0, and more preferably 1.3 to 6.0.

[0020] These organic solvents can be used alone or in combination, and the amount used is preferably 10.0% by weight or more and 90.0% by weight or less based on the total amount of the oil-based ink for ballpoint pens.

[0021] In the present invention, the colorant is not particularly limited and water-soluble dyes, oil-soluble dyes, and pigments can be used. As the water-soluble dye, specifically, any of direct dyes, acid dyes, basic dyes, etc. can be used. Specific examples of direct dyes include Japanol Fast Black D Concentrate (CI Direct Black 17), Water Black 100L (19), Water Black L-200 (19), Direct Fast Black B (22), Direct Fast Black AB (32), Direct Deep Black EX (38), Direct Fast Black Concentrate (51), Kayalas Spragray VGN (71), Kayalas Direct Brilliant Yellow G (CI Direct Yellow 4), Direct Fast Yellow 5GL (26), Aizen Primula Yellow GCLH (44), Direct Fast Yellow R (50), Aizen Direct Fast Red FH (CI Direct Red 1), Nippon Fast Scarlet GSX (4), Direct Fast Scarlet 4BS (23), Aizen Direct Rhoduline BH (same 31), Direct Scarlet B (same 37), Kayak Direct Scarlet 3B (same 39), Aizen Primula Pink 2BLH (same 75), Sumi Light Red F3B (same 80), Aizen Primula Red 4BH (same 81), Kayalas Sprat Vin BL (same 83), Kayalas Light Red F5G (same 225), Kayalas Light Red F5B (same 226), Kayalas Light Rose FR (same 2 27), Direct Sky Blue 6B (CI Direct Blue 1), Direct Sky Blue 5B (same 15), Sumilite Splat Blue BRR Concentrate (same 71), Daibogen Turquoise Blue S (same 86), Water Blue #3 (same 86), Kayalas Turquoise Blue GL (same 86), Kayalas Splat Blue FF2 GL (same 106), Kayalas Splat Turquoise Blue FBL (same 199), etc. Specific examples of acid dyes include Acid Blue Black 10B (CI Acid Black 1), Nigrosine (same 2), Suminol Milling Black 8BX (same 24), Kayanol Milling Black VLG (same 26), Suminol Fast Black BR ​​Concentrate (same 31), Mitsui Nylon Black GL (same 52), Aizen Opal Black WH Extra Concentrate (same 52), Sumiran Black WA (same 52), Ranil Black BG Extra Concentrate (same 107), Kayanol Milling Black TLB (same 109), Suminol Milling Black B (same 109), Kayanol Milling Black TLR (same 110), Aizen Opal Black New Concentrate (same 119), Water Black 187-L (same 154), Kayaku Acid Brilliant Flavin FF (CI Acid Yellow 7:1), Kayasil Yellow GG (same 17) , Xylene Light Yellow 2G 140% (same as 17), Suminol Leveling Yellow NR (same as 19), Daiwa Tartrazine (same as 23), Kayak Tartrazine (same as 23), Suminol Fast Yellow R (same as 25), Diacid Light Yellow 2GP (same as 29), Suminol Milling Yellow O (same as 38), Suminol Milling Yellow MR (same as 42), Water Yellow #6 (same as 42), Kayanol Yellow NFG (same as 4 9), Suminol Milling Yellow 3G (same 72), Suminol Fast Yellow G (same 61), Suminol Milling Yellow G (same 78), Kayanol Yellow N 5G (same 110), Suminol Milling Yellow 4G 200% (same 141), Kayanol Yellow NG (same 135), Kayanol Milling Yellow 5GW (same 127), Kayanol Milling Yellow 6GW (same 142), Sumitomo Fast Scarlet A (CIAcid Red 8), Kayaku Silk Scarlet (9), Solar Rubin Extra (14), Daiwa New Kokushin (18), Aizen Bonsaw RH (26), Daiwa Red No. 2 (27), Suminol Leveling Brilliant Red S3B (35), Kayasil Rubinol 3GS (37), Aizen Erythrosine (51), Kayaku Acid Rhodamine FB (52), Suminol Leveling Rubinol 3GP (57), Diacid Alizarin Rubinol F3G 200% (82), Aizen Eosin GH (87), Water Pink #2 (92), Aizen Acid Phloxine PB (92), Rose Bengal (94), Kayanolumi Ring Scarlet FGW (same as 111), Kayanol Milling Rubin 3BW (same as 129), Sumino All Milling Brilliant Red 3BN Concentrate (same as 131), Sumino All Milling Brilliant Red BS (same as 138), Eisen Opal Pink BH (same as 186), Sumino All Milling Brilliant Red B Concentrate (same as 249), Kayaku Acid Brilliant Red 3BL (same as 254), Kayaku Acid Brilliant Red BL (same as 265), Kayanol Milling Red GW (same as 276), Mitsui Acid Violet 6BN (CI Acid Violet 15), Mitsui Acid Violet BN (same as 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), Supranol Blue B (same 15), Orient Soluble Blue OBC (same 22), Suminol Leveling Blue 4GL (same 23), Mitsui Nylon Fast Blue G (same 25), Kayasil Blue AGG (same 40), Kayasil Blue BR (same 41), Mitsui Alizarin Sapphirol SE (same 43), Suminol Leveling Sky Blue R Extra Conc (same 62), Mitsui Nylon Fast Sky Blue B (same 78), Sumitomo Brilliant Indocyanine 6Bh / c (same as 83), Sandran Cyanine N-6B 350% (same as 90), Water Blue #115 (same as 90), Orient Soluble Blue OBB (same as 93), Sumitomo Brilliant Blue 5G (same as 103), Kayanol Milling Ultra Sky SE (same as 112), Kayanol Milling Cyanine 5R (same as 113), Aizen Opal Blue 2 GLH (same as 158), Daiwa Guinea Green B (CI Acid Green 3), Acid Brilliant Milling Green B (same as 9), Daiwa Green #70 (same as 16), Kayanol Cyanine Green G (same as 25), and Suminol Milling Green G (same as 27). Specific examples of basic dyes include Eisenkathiron Yellow 3GLH (CI Basic Yellow 11), Eisenkathiron Brilliant Yellow 5GLH (same 13), Sumiacrylic Yellow E-3RD (same 15), Maxiron Yellow 2RL (same 19), Astrazon Yellow 7GLL (same 21), Kayakryl Golden Yellow GL-ED (same 28), Astrazon Yellow 5GL (same 51), Eisenkathiron Orange GLH (CI Basic Orange 21), Eisenkathiron Brown 3GLH (same 30), Rhodamine 6GCP (CI Basic Red 1), Eisen Astraphloxine (same 12), Sumiacrylic Brilliant Red E-2B (same 15), and Examples include Strazon Red GTL (18), Eisen Katiron Brilliant Pink BGH (27), Maxilon Red GRL (46), Eisen Methyl Violet (CI Basic Violet 1), Eisen Crystal Violet (3), Eisen Rhodamine B (10), Astrazon Blue G (CI Basic Blue 1), Astrazon Blue BG (3), 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). These may be used alone or in combination.

[0022] Specific examples of oil-soluble dyes that can be used include acid dyes, basic dyes, metal complex dyes, salt-forming dyes, azine dyes, anthraquinone dyes, phthalocyanine dyes, and triphenylmethane dyes. Specific examples include Nigrosine Base EE, Nigrosine Base EEL, Nigrosine Base EX, Nigrosine Base EXBP, Nigrosine Base EB, Oil Yellow 101, Nigrosine Base 107, Oil Pink 312, Oil Brown BB, Oil Green BG, Oil Blue 613, Oil Scarlet 308, Nigrosine Base BOS, Oil Black HBB, Oil Black 860, Oil Black BS, Barrifast Yellow 1101, Nigrosine Base 1105, Nigrosine Base 1109, Nigrosine Base 1120, Nigrosine Base 3104, Nigrosine Base 3105, Nigrosine Base 3108, Nigrosine Base 4120, Nigrosine Base AUM, Barrifast Orange 2210, Nigrosine Base 3209, Nigrosine Base 3210, Nigrosine Base 1306, Nigrosine Base 1308, Nigrosine Base 1320, Nigrosine Base 1355. , 1360, 2303, 2320, 3304, 3306, 3320, Balifast Pink 2310N, Balifast Brown 2402, 3405, Balifast Green 1501, Balifast Blue 1603, 1605, 1607, 1631, 2606, 2610, 2620, Balifast Violet 1701, 1702, Balifast Blue Lac 1802, 1805, 1807, 3804, 3806, 3808, 3810, 3820, 3830, Spirit Red 102, Spirit Black AB, Ospi Yellow RY, ROB-B, MVB3, SP Blue 105 (all manufactured by Orient Chemical Industry Co., Ltd.), Aizen Spiron Yellow 3RH, Aizen Spiron GRLH Special, Aizen C-2GH, Aizen C-GNH New, Aizen Spiron Orange 2RH, GRH Concentrate Special, Aizen Spiron Red GEH, BEH, GRLH Special, C-GH, C-BH, Aizen Spiron Violet RH, C-RH, Aizen Spiron Brown BH Concentrate, RH, Aizen Spiron Mahogany RH, Aizen Spiron Blue GNH, 2BNH, C-RH, BPNH, Aizen Spiron Green C-GH, 3GNH Special, Aizen Spiron Black BNH, MH, RLH, GMH Special, BH Special, SBN Orange 703, SBN Violet 510, 521, SPT Orange 6, SPTBlue 111, SOT Pink 1, SOT Blue 4, SOT Black 1, SOT 6, SOT 10, SOT 12, SOT 13 Liquid, Eisen Rhodamine B Base, Eisen Methyl Violet Base, Eisen Victoria Blue B Base (all manufactured by Hodogaya Chemical Co., Ltd.), Oil Yellow CH, Oil Pink 330, Oil Blue 8B, Oil Black S, Eisen FS Special A, Eisen 2020, Eisen 109, Eisen 215, AL Yellow 1106D, Eisen 31 01, AL Red 2308, Neo Super Yellow C-131, C-132, C-134, Neo Super Orange C-233, Neo Super Red C-431, Neo Super Blue C-555, Neo Super Brown C-732, C-733 (all manufactured by Chuo Synthetic Chemical Industry Co., Ltd.), Oleosol Fast Yellow 2G, Oleosol Fast GCN, Oleosol Fast Orange GL, Oleosol Fast Red BL, Oleosol Fast RL (all manufactured by Taoka Chemical Industry Co., Ltd.) Sanovinyl Yellow 2GLS, Sanovinyl RLS, Sanovinyl 2RLS, Sanovinyl Orange RLS, Sanovinyl Fire Red GLS, Sanovinyl Red 3BLS, Sanovinyl Pink 6BLS, Sanovinyl Blue RN, Sanovinyl GLS, Sanovinyl Green 2GLS, Sanovinyl Brown GLS (all manufactured by Sandoz, Switzerland), Magenta SP 247%, Crystal Violet 10B 250%, Malachite Green Crystal Conc, Brilliant Green Crystal H 90%, Spirit Soluble Red 64843 (all manufactured by Holliday, UK), Neptune Red Base 543, Neptune Blue Base 634, Neptune Violet Base 604, Bassonil Red 540, Bassonil Violet 600, Victoria Blue F4R, Nigrosine Base LK (all manufactured by BASF, Germany), Methyl Violet 2B Base (all manufactured by National Anilne Div., USA). These may be used alone or in combination.

[0023] Specific pigments include carbon blacks such as Furnest Black, Contact Black, Thermal Black, and Acetylene Black, black iron oxide, yellow iron oxide, red iron oxide, ultramarine, Prussian blue, cobalt blue, titanium yellow, turquoise, molybdate orange, titanium oxide, gold powder, silver powder, copper powder, aluminum powder, brass powder, tin powder, mica pigments, and CIPIGMENT RED. 2, 3, 5, 17, 22, 38, 41, 48:2, 48:3, 49, 50:1, 53:1, 57:1, 58:2, 60, 63:1, 63:2, 64:1, 88, 112, 122, 123 , 144, 146, 149, 166, 168, 170, 176, 177, 178, 179, 180, 185, 190, 194, 206, 207, 209, 216, 245, CIPIGMENT ORANGE 5, 10, 13, 16, 36, 40, 43, CIPIGMENT VIOLET Examples include 19, 23, 31, 33, 36, 38, 50, CIPIGMENT BLUE 2, 15, 15:1, 15:2, 15:3, 15:4, 15:5, 16, 17, 22, 25, 60, 66, CIPIGMENT BROWN 25, 26, CIPIGMENT YELLOW 1, 3, 12, 13, 24, 93, 94, 95, 97, 99, 108, 109, 110, 117, 120, 139, 153, 166, 167, 173, CIPIGMENT GREEN 7, 10, and 36. These can be used alone or in combination of two or more. In addition to these pigments, processed pigments can also be used. Examples of such paints include Renol Yellow GG-HW30, HR-HW30, Orange RL-HW30, Red HF2B-HW30, FGR-HW30, F5RK-HW30, Carmine FBB-HW30, Violet RL-HW30, Blue B2G-HW30, CF-HW30, Green GG-HW30, Brown HFR-HW30, and Black R-HW30 (all manufactured by Clariant Japan Co., Ltd.), UTCO-001 Yellow, 012 Yellow, 021 Orange, 031 Red, 032 Red, 042 Violet, 051 Blue, 052 Blue, 061 Green, 591 Black, and 592 Black (all manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), and MICROLITH Yellow. These include 4G-A, MX-A, 2R-A, Brown 5R-A, Scarlet RA, Red 2C-A, 3R-A, Magenta 2B-A, Violet BA, Blue 4G-A, and Green GA (all manufactured by Chiba Specialty Chemicals Co., Ltd.).

[0024] To improve the dispersibility of the pigment, anionic, cationic, nonionic, or amphoteric surfactants or polymer resins can be used as auxiliary agents. Specific examples include anionic, nonionic, or cationic surfactants such as higher fatty acids, higher alcohol sulfate ester salts, fatty acid sulfate ester salts, alkylarylsulfonic acids, phosphate esters, polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, and sorbitan fatty acid esters, as well as resins and oligomers for dispersing pigments, such as polyvinyl butyral resins, polyvinylpyrrolidone resins, polyacrylic acid ester resins, polymethacrylic acid ester resins, styrene-acrylic acid resins, and styrene-maleic acid resins. These may be used alone or in combination of two or more.

[0025] For the purpose of adjusting the viscosity of the ink and improving the fixation of handwriting, resins can be added to the ink after adjusting the amount appropriately. Specific examples include polyvinylpyrrolidone resin, polyvinyl alcohol resin, polyvinyl butyral resin, ketone resin, acrylic acid-acrylic acid ester resin, acrylic acid-methacrylic acid ester resin, methacrylic acid-acrylic acid ester resin, methacrylic acid-methacrylic acid ester resin, styrene-acrylic acid resin, styrene-maleic acid resin, phenolic resin, rosin, rosin ester, modified rosin, modified rosin ester, maleated rosin, maleated rosin ester, fumarated rosin, fumarated rosin ester, celluloses such as carboxymethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and hydroxypropyl cellulose, synthetic polymers such as N-vinylacetamide polymer crosslinked products, and inorganic clay minerals. These may be used alone or in combination of two or more.

[0026] In the present invention, among the above resins, a resin having an acidic group is used, which electrostatically adsorbs to the silicone composite particles, increasing their apparent bulk and preventing collisions between the silicone composite particles, thereby improving dispersion stability. At the same time, the silicone composite particles that acted as a sealant are quickly loosened when rewriting after writing, thereby reducing smearing at the start of writing (hereinafter referred to as "initial stroke smearing"). The degree of acidity of a resin is expressed by its acid value, which is the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize all the acidic components contained in 1 g of sample. An acid value of 50 mg KOH / g or more and 600 mg KOH / g or less is preferable, and an acid value of 150 mg KOH / g or more and 550 mg KOH / g or less is even more preferable. Furthermore, if the resin contains OH groups, the interaction with the acidic groups will improve the adsorption to the silicone composite particles, improving lubricity and the writing feel. The amount of OH groups is expressed as an OH value, which is determined by acetylating with acetic anhydride, quantifying the free acetic acid with potassium hydroxide, and expressing it as the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize all the acidic components contained in 1 g of sample. Specific examples of rosin include KR-612 (acid value 167 mg KOH / g) and KR-614 (acid value 175 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.), maleic acid rosin includes Marquid No. 31 (acid value 188 mg KOH / g), Marquid No. 32 (acid value 130 mg KOH / g), Marquid No. 33 (acid value 305 mg KOH / g), and Marquid No. 3002 (acid value 100 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.), and Harimac T-80 (acid value 185 mg KOH / g) (both manufactured by Harima Chemical Industries, Ltd.), and maleic acid rosin ester includes Hariestar MSR-4 ( Examples of acid-modified rosins include KE-604 (acid value 238 mg KOH / g) and KR-120 (acid value 325 mg KOH / g) (both manufactured by Arakawa Chemical Industries, Ltd.), examples of specially modified rosins include Haritack F-75 (acid value 145 mg KOH / g) and Haritack FG-90 (acid value 150 mg KOH / g) (both manufactured by Harima Chemical Industries, Ltd.), and examples of styrene-acrylic acid resins include Joncryl 611 (acid value 53 mg KOH / g) and Joncryl 586 (acid value 108 mg KOH / g) (both manufactured by BASF Japan Ltd.).

[0027] Among the above resins, the use of hydroxypropyl cellulose is preferred in the present invention. The coexistence of the silicone composite particles in the molecular network of hydroxypropyl cellulose not only provides a sealing effect in the ink flow path, but is also thought to be effective in preventing ink leakage and spreading even when the pen tip is not retracted and is struck against a display or the like, as the hydroxypropyl cellulose and the silicone composite particles immediately orient themselves on the ink surface. Specific examples include NISSO HPC-VH, H, M, L, SL, and SSL (all manufactured by Nippon Soda Co., Ltd.), and Klucel-H, M, G, J, L, and E (all manufactured by Ashland Japan Co., Ltd.).

[0028] Lubricants for preventing ball seat wear and improving writing performance include higher fatty acids such as oleic acid, nonionic surfactants with long-chain alkyl groups, polyether-modified silicone oil, monoalkyl phosphates, polyoxyethylene monoalkyl ether phosphates, dialkyl phosphates, polyoxyethylene dialkyl ether phosphates, trialkyl phosphates, polyoxyethylene trialkyl ether phosphates, polyoxyethylene monostyrenated phenyl ether phosphate esters, polyoxyethylene distyrenated phenyl ether phosphate esters, perfluoroalkyl group-phosphate group-containing phosphate esters, or their metal salts, ammonium salts, amine salts, and alkanolamine salts. When these lubricants are used in combination with the silicone composite particles, lubricant molecules are adsorbed onto the surface of the silicone composite particles, forming lubricant particles covered with a film of lubricant molecules, which further prevents ball seat wear and improves writing performance. Commercially available products include Phosphanol BH-650, SM-172, ED-200, GF-339, RA-600, GF199, ML-200, ML-220, ML-240, RD-510Y, GF-185, RS-410, RS-610, RS-710, RL-210, RL-310, RB-410, and RP-71. 0, AK-25, GF702, RS-610NA, SC-6103, RD-720, LP-700, LS-500, LB400 (all manufactured by Toho Chemical Industry Co., Ltd.), Plysurf A207H, A208B, A219B, A208S, A212S, A215C, AL, AL12 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), NIKKOL Examples of lubricant lubricants that may be used include DLP-10, DOP-8NV, DDP-2, DDP-4, DDP-6, DDP-8, DDP-10, TLP-4, TCP-5, TOP-0V, TDP-2, TDP-6, and TDP-8 (all manufactured by Nikko Chemicals Co., Ltd.), and Megafac F-510 (all manufactured by DIC Corporation). In particular, monoalkyl phosphates, polyoxyethylene monoalkyl ether phosphates, dialkyl phosphates, polyoxyethylene dialkyl ether phosphates, trialkyl phosphates, polyoxyethylene trialkyl ether phosphates, polyoxyethylene monostyrenated phenyl ether phosphate esters, and polyoxyethylene distyrenated phenyl ether phosphate esters have a strong adsorption force to the surface of the silicone composite particles, which is thought to further strengthen the strength of the lubricant molecular film, thereby improving the effectiveness of preventing ball seat wear and improving penmanship. Furthermore, if the number of carbon atoms in the alkyl group contained in the phosphate ester is 10 or more and 20 or less, wear between the ball and the ball seat is reduced even when writing with a heavy load, which is preferable. Furthermore, to improve wear prevention between the ball and the ball seat, it is preferable to use a phosphate ester in which ethylene oxide groups have been introduced, preferably 1 to 20 moles of ethylene oxide groups introduced into the phosphate ester structure. By adjusting the HLB (Hydrophile-Lipophile Balance) of the phosphate ester for use in oil-based ink for ballpoint pens, the phosphate ester will not separate in the ink, making it possible to maintain good wear protection for the ball and ball seat over a long period of time. The preferred HLB range is between 5 and 12.

[0029] The amount of phosphate ester used is preferably 0.05% by weight or more and 20.0% by weight or less of the total amount of oil-based ink for ballpoint pens, more preferably 0.1% by weight or more and 10.0% by weight or less, and most preferably 0.3% by weight or more and 2.0% by weight or less, which optimizes the adsorption state between the ballpoint pen tip and the silicone composite particles and significantly improves the lubrication component. If the amount used is less than 0.05% by weight, the improvement in writing feel is insufficient, but if it exceeds 20.0% by weight, the content of organic solvent in the ink will be reduced, which will result in insufficient solubility of solid components in the ink such as dyes and resins, and may cause the letters to easily blur.

[0030] In the present invention, by maintaining the pH of the ink within an appropriate range, it is possible to increase the adsorption of acidic substances to the metal ballpoint pen tip or the silicone composite particles, thereby preventing dotted lines in handwriting and ensuring an improved writing feel. The appropriate range is from 2.5 to 7.0, more preferably from 4.0 to 6.0.

[0031] Water can also be added to the oil-based ink for ballpoint pens of the present invention. The water may be selected from mineral water, tap water, ion-exchanged water, purified water, distilled water, pure water, etc. Among these, ion-exchanged water, purified water, distilled water, and pure water are preferred, as keeping the calcium and magnesium concentrations in the ink below 100 ppm prevents calcium and magnesium from reacting with ink components and forming insoluble precipitates in the ink, such as calcium chloride, magnesium chloride, calcium-acid compounds, and magnesium-acid compounds. The addition of water increases conductivity and further enhances the pH-dependent adsorption of acidic substances to the silicone composite particle surface, thereby suppressing dotted lines in handwriting and further improving writing feel. The amount of water used can be within a range that does not cause the ink to become unstable over time. It is preferably 0.1 to 15.0 wt. % of the total weight of the oil-based ink for ballpoint pens, and more preferably 0.5 to 10.0 wt. %. The method for adding water is not particularly limited, but water may be added directly to an ink containing an appropriate mixture of ingredients other than water, or ingredients used in oil-based inks for ballpoint pens, such as colorants and resins, may be allowed to absorb moisture in advance.

[0032] The ink viscosity of the oil-based ink for ballpoint pens of the present invention is not particularly limited, but is preferably 25°C at a shear rate of 100 sec which is the same as that during writing. -1 It is preferable that the ink viscosity in this case is 30 mPa·s or more and 3000 mPa·s or less. If it is less than 30 mPa·s, the lubricating film strength of the oil-based ink will be low, which may result in a poor writing feel and a poor abrasion resistance of the ball seat. If it exceeds 3000 mPa·s, there is a risk that the writing will smear when rewriting, i.e., the initial smearing will worsen. By setting the ink viscosity to 50 mPa·s or more and 500 mPa·s or less, the ink film strength will be such that the elastic effect of the silicone composite particles can be exerted, resulting in a unique writing feel. By setting it to 60 mPa·s or more and 200 mPa·s or less, the unique writing feel will be even more pronounced.

[0033] The ball of the ballpoint pen tip used in the present invention preferably has a longitudinal movement distance of more than 3 μm and not more than 60 μm. This is because if it is less than 3 μm, it becomes difficult to obtain thick handwriting or a good writing feel, and if it exceeds 60 μm, the ink ejection volume becomes too large, resulting in severe bleeding of the handwriting. By setting the distance to more than 20 μm and not more than 55 μm, a large amount of oil-based ink containing the silicone composite particles acts as a lubricant between the ball and the ball seat, significantly improving the writing feel compared to conventional ballpoint pens.

[0034] The oil-based ballpoint pen refill is configured by directly storing the above-mentioned oil-based ink for ballpoint pens in an ink reservoir tube, and by attaching a ball tip to the tip of the ink reservoir tube directly or via a tip holder. The ball tip comprises a ball as a writing element, a ball that partially protrudes from the tip opening of a through-hole (ink passage hole), and a ball holder that holds the ball, the tip opening of the ink passage hole being smaller in diameter than the ball and that has multiple inward protrusions formed in the middle of the inner wall of the ink passage hole to form a ball house portion that defines the range of forward and backward movement of the ball. The ball holder for the above-mentioned ballpoint pen tip is typically made of a cylindrical metal member such as stainless steel, and the through hole that serves as the ink passage hole and the inward protrusions are formed using a cutting blade such as a drill or broach. However, a pipe material with a pre-formed through hole can also be used. When a pipe material is used, a recess is formed in the outer wall of the pipe material by pressing and deforming it with a pin, and a protrusion is formed in the inner wall corresponding to the recess, and this protrusion becomes the inward protrusion.

[0035] The balls that can be used in the ballpoint pen tip include those containing 75.0 to 85.0% by weight of tungsten (element symbol: W), 9.0 to 14.0% by weight of cobalt (element symbol: Co), 0.0 to 3.0% by weight of chromium (element symbol: Cr), 0.0 to 6.0% by weight of carbon (element symbol: C), and 0.0 to 5.0% by weight of Cr3C3. The ball surface roughness Ra can be 1.0 to 20.0. The ball Vickers hardness (HV) can be 1000 to 2000. In addition to the above-mentioned cemented carbide, other examples include those containing silicon carbide (molecular formula: SiC) from 0.0 to 95.0% by weight and yttrium oxide-aluminum oxide (molecular formula: Y2O3-Al2O3) from 0.0 to 5.0% by weight, with a ball surface roughness Ra of 0.5 to 10.0 nm; those containing zirconium dioxide (molecular formula: ZrO2) from 0.0 to 95.0% by weight and yttrium oxide (molecular formula: Y2O3) from 0.0 to 5.0% by weight, with a ball surface roughness of 0.5 to 10.0 nm; and those containing aluminum oxide (molecular formula: Al2O3) from 0.0 to 99.9% by weight and chromium (element symbol: Cr) from 0.0 to 0.1% by weight, with a ball surface roughness of 0.5 to 10.0 nm. The ball diameter may be any of the conventionally known diameters of 0.1 mm to 30.0 mm. To obtain fine handwriting, it is preferable to use a ball diameter of 0.5 mm or less, and to obtain bold handwriting, it is preferable to use a ball diameter of 1.0 mm or more.

[0036] The material of the ball holder that can be used with the ballpoint pen tip is stainless steel. The following components can be used: chromium (element symbol: Cr) 18.0% to 22.0% by weight, molybdenum (element symbol: Mo) 0.5% to 3.0% by weight, manganese (element symbol: Mn) 0.0% to 2.0% by weight, silicon (element symbol: Si) 0.0% to 1.0% by weight, sulfur (element symbol: S) 0.0% to 0.2% by weight, phosphorus (element symbol: P) 0.0% to 0.1% by weight, carbon (element symbol: C) 0.0% to 0.1% by weight, lead (element symbol: Pb) 0.0% to 0.5% by weight, tellurium (element symbol: Te) 0.0% to 0.1% by weight, and iron (element symbol: Fe) 0.0% to 80.0% by weight. Ball holders with a Vickers hardness (HV) of 150 or more and 300 or less can be used. If the ball holder is made of copper alloy, the following components can be used: carbon (element symbol: C) 55.0% to 65.0% by weight, nickel (element symbol: Ni) 12.0% to 18.0% by weight, manganese (element symbol: Mn) 0.0% to 1.0% by weight, iron (element symbol: Fe) 0.0% to 0.5% by weight, lead (element symbol: Pb) 0.0% to 4.0% by weight, zinc (element symbol: Zn) 0.0% to 30.0% by weight. The ball holder's Vickers hardness (HV) can be 150 to 300. In addition, the ball holder may be made of a conventionally known material such as resin or brass.

[0037] The ballpoint pen tip can also be equipped with a coil spring inside the ball holder that presses the ball forward from the backside through a central hole formed at the center of multiple inward protrusions, thereby improving the airtightness of the ball holder by pressing the ball against the inner edge of the tip opening and preventing ink from seeping out of the tip. Stainless steel wire such as SUS304 is typically used for the coil spring, but hard steel wire and piano wire can also be used. Resins such as polycarbonate and polyether ether ketone can also be used. Stainless steel wire and hard steel wire with nickel (element symbol: Ni) plating on their surfaces can also be used. When the coil spring is installed inside the ball holder, the ball can be pressed with a force of 0.01 N or more and 1.50 N or less.

[0038] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0039] The viscosity in the examples was measured using an MCR302 (manufactured by Anton Paar) with a rotor CP50-1 at 25°C and a shear rate of 100 s (unit: mPa s).

[0040] The pH in the examples was measured at 25°C using a PICCOLO plus (Hanna Instruments Japan). [Example]

[0041] As shown in Table 1, oil-based inks were prepared in Examples 1 to 9 and Comparative Examples 1 to 6. The materials used were as follows: Pigment (1): Printex 35 (carbon black, manufactured by Orion Engineered Carbons Co., Ltd.) Pigment (2): FUJI FAST RED 8800 (CI Pigment Red 254, manufactured by Fuji Pigment Co., Ltd.) Pigment (3): Chromophthalmic Blue A3R (CI Pigment Blue 60, manufactured by BASF Japan Ltd.) Dye (1): SPILON RED C-GH (a salt-forming dye made from a xanthene-based basic dye and alkyldiphenyl ether disulfonic acid, manufactured by Hodogaya Chemical Industry Co., Ltd.) Dye (2): VALIFAST RED 1364 (a salt-forming dye made from CI Basic Red 1:1, alkylbenzene sulfonic acid, and alkyldiphenyl ether disulfonic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye (3): VALIFAST YELLOW 1120 (onium salt of a basic dye and a colorless organic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye (4): SPILON YELLOW C-GNH new (a salt-forming dye made from an indolinone-based basic dye and alkyldiphenyl ether disulfonic acid, manufactured by Hodogaya Chemical Industry Co., Ltd.) Dye (5): OIL BLUE 613 (a mixture of C1 Solvent Blue 5 and rosin-modified resin, manufactured by Orient Chemical Industries, Ltd.) Dye (6): VALIFAST BLUE 1631 (a salt-forming dye made from CI Basic Blue 7 and a colorless organic acid, manufactured by Orient Chemical Industries Co., Ltd.) Dye (7): VALIFAST VIOLET 1731 (a salt-forming dye made from CI Acid Violet 17 and a methine dye, manufactured by Orient Chemical Industries Co., Ltd.) Dye (8): A salt-forming dye made from Acid Yellow 42 and benzoxonium chloride Organic solvent (1): n-propanol Organic solvent (2): Ethylene glycol monoisopropyl ether Organic solvent (3): Ethylene glycol monophenyl ether Organic solvent (4): Benzyl alcohol Phosphate ester (1): Phosphanol LB-400 (a mixture of mono-, di-, and triesters of polyoxyethylene (4) oleyl ether phosphate, HLB 8.6, manufactured by Toho Chemical Industry Co., Ltd.) Phosphate ester (2): Phosphanol GF-199 (a mixture of lauryl ether phosphate monoester, diester, and triester, HLB 5.5, manufactured by Toho Chemical Industry Co., Ltd.) Phosphate ester (3): Phosphanol LS-500 (a mixture of mono-, di-, and triesters of polyoxyethylene (4) tridecyl ether phosphate, HLB 9.0, manufactured by Toho Chemical Industry Co., Ltd.) Phosphate ester (4): Phosphanol RP-710 (a mixture of mono-, di-, and triesters of polyoxyethylene (6) phenyl ether phosphate, HLB 11.9, manufactured by Toho Chemical Industry Co., Ltd.) Phosphate ester (5): NIKKOL DDP-2 (di(C12-15)palace-2 phosphate, HLB 6.5, manufactured by Nikko Chemicals Co., Ltd.) Organic amine (1): Triisopropanolamine (Tokyo Chemical Industry Co., Ltd.) Organic amine (2): Nymeen L201 (polyethylene glycol-1 laurylamine, NOF Corporation) Organic amine (3): Triethanolamine (Tokyo Chemical Industry Co., Ltd.) Active ingredient (1): Sorgen 30 (sorbitan sesquioleate, HLB 3.7, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Activator (2): Pegnol ST-7 (polyoxyethylene (7) alkyl (C12-14) ether, HLB 12.8, manufactured by Toho Chemical Industry Co., Ltd.) Activator (3): NIKKOL HCO-10 (polyoxyethylene hydrogenated castor oil, HLB 6.5, manufactured by Nikko Chemicals Co., Ltd.) Active ingredient (4): NIKKOL Decaglyn 1-ISV (decaglyceryl monoisostearate, HLB 12.0, manufactured by Nikko Chemicals Co., Ltd.) Activator (5): NIKKOL BO-10V (polyoxyethylene oleyl ether, HLB 14.5, manufactured by Nikko Chemicals Co., Ltd.) Silicone composite particles (1): KMP-600 (silicone composite particles, average particle diameter 5 μm, rubber hardness 30 durometer A, true specific gravity 0.99 g / cm, manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone composite particles (2): KMP-605 (silicone composite particles, average particle diameter 2 μm, rubber hardness 75 durometer A, true specific gravity 0.99 g / cm, manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone composite particles (3): X-52-7030 (silicone composite particles, average particle diameter 0.8 μm, rubber hardness 75 durometer A, true specific gravity 1.01 g / cm, manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone rubber particles: KMP-597 (silicone rubber particles, average particle diameter 5 μm, rubber hardness 30 durometer A, manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone resin particles: Tospearl 120FL Silicone Beads (silicone resin particles, average particle diameter 2 μm, manufactured by Momentive Performance Materials Japan, LLC) Titanium oxide particles: JR-800 (titanium oxide particles, average particle diameter 0.27 μm, true specific gravity 3.9 g / cm, manufactured by Teika Co., Ltd.) Silica particles: QSG-170 (hydrophobic silica spherical particles, average particle diameter 0.17 μm, true specific gravity 1.8 g / cm, manufactured by Shin-Etsu Chemical Co., Ltd.) Resin (1): S-LEC BL-1 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) Resin (2): S-LEC BH-3 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) Resin (3): PVPK-90 (Polyvinylpyrrolidone, manufactured by Ashland Japan Co., Ltd.) Resin (4): TEGO Variplus SK (polyol resin, OH value 325 mg KOH / g, Tg 90 ° C, manufactured by Evonik Japan Co., Ltd.) Resin (5): TEGO Variplus CA (ketone aldehyde condensation resin, OH value 200 mg KOH / g, Tg 75 ° C, manufactured by Evonik Japan Co., Ltd.) Resin (6): Marquid 3002 (maleic rosin, acid value 100 mg KOH / g, Tg 175°C, manufactured by Arakawa Chemical Industries, Ltd.) Resin (7): Harima T-80 (maleic rosin, acid value 185 mg KOH / g, Tg 85°C, manufactured by Harima Chemicals Co., Ltd.) Resin (8): 42% acrylic acid-acrylic and methacrylic acid ester copolymer in ethylene glycol monophenyl ether solution (solid equivalent acid value 510 mg KOH / g, OH value 130 mg KOH / g, Tg 80°C) Resin (9): 42% acrylic acid-styrene-methacrylic acid ester copolymer in ethylene glycol monophenyl ether solution (solid equivalent acid value 300 mg KOH / g, OH value 80 mg KOH / g, Tg 30°C) Resin (10): NISSO HPC-H (hydroxypropyl cellulose, manufactured by Nippon Soda Co., Ltd.) Dispersant (1): DISPERBYK-102 (a copolymer having an acidic group, acid value 101 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (2): DISPERBYK-111 (copolymer containing acid groups, acid value 129 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (3): BYK-P105 (polymer of low molecular weight unsaturated carboxylic acid, acid value 365 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (4): DISPERBYK-180 (an alkylol ammonium salt of a copolymer containing an acid group, acid value 94 mg KOH / g, amine value 94 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Dispersant (5): DISPERBYK-108 (hydroxyl group-containing carboxylic acid ester, amine value 71 mg KOH / g, manufactured by BYK Japan Co., Ltd.) Rust inhibitor: Benzotriazole (manufactured by E-CHEM ENTERPRISE CORPORATION) The production procedure involved stirring an organic solvent with the silicone composite particles, silicone rubber particles, silicone resin particles, titanium oxide particles, or silica particles, the dispersion resin S-LEC BL-1, a dispersant, and optionally a pigment at 60°C, then processing for 2 minutes at a peripheral speed of 30 m / s using a thin-film rotary high-speed mixer, after which other additives were added and stirring with a propeller for 2 hours to obtain an oil-based ink.For the non-commercially available acrylic acid copolymer solution, a monomer of choice and the polymerization initiator azobisisobutyronitrile were dissolved in phenyl glycol using propeller stirring, and then heated to polymerize to obtain an acrylic acid copolymer solution.

[0042] Preparation of test ballpoint pens 1.0 mL of each of the oil-based inks of Examples 1 to 9 and Comparative Examples 1 to 6 was filled into a refill having the same structure as a water-based ballpoint pen with a ballpoint pen nib (knock-type Energel, product code BLN75, manufactured by Pentel Co., Ltd., nib material: stainless steel, ball material: carbide, ball diameter: φ0.5 mm, ball movement amount in the vertical axis direction of the ball at the ballpoint pen tip: 30 μm), the nib was attached, the nib was sealed with a packing (HM200, ethylene-vinyl acetate copolymer resin-based hot melt adhesive), and the refill was centrifuged.

[0043] Pen tip ink leakage confirmation test 1 Three of the above test ballpoint pens were prepared for each Example and Comparative Example, and after removing the packing, the "Date of the Diet" was written by hand in an environment of 25°C temperature and 30% humidity. After attaching them to a mount and leaving them face down for three days, the amount of ink leaking from the pen tip was checked at 50x magnification using a digital microscope (Keyence Corporation, VHX-7000), the diameter was recorded, and the average value was calculated (unit: mm).

[0044] Pen tip ink leakage confirmation test 2 Three of the above test ballpoint pens were prepared for each example and comparative example, each with a 50g weight attached. After removing the packing, the "Date of the Diet" was written by hand in an environment of 25°C temperature and 30% humidity, and the pen tip was then placed vertically against an acrylic resin plate and left to stand for three days. The size of the ink that had leaked from the pen tip onto the acrylic resin plate was then confirmed at 20x magnification using a digital microscope, the diameter recorded, and the average value calculated (unit: mm).

[0045] Dispersion stability confirmation test for silicone composite particles One test ballpoint pen was prepared for each Example and Comparative Example, and was left to stand for 3 days in an environment with a temperature of 70°C and no humidity control, after which the appearance was checked. 〇…Nothing more than appearance, no problem with writing △: A small amount of the silicone composite particles was observed at the grease interface or at the step formed at the crimped portion between the pipe and the ballpoint pen tip member. ×: The silicone composite particles are heavily observed at the grease interface or at the step formed at the crimped portion between the pipe and the ballpoint pen tip member.

[0046] First brush stroke blur confirmation test Three ballpoint pens for each of the above examples and comparative examples were prepared, and after removing the packing, the "Date of the Diet" was written by hand in an environment of 25°C temperature and 30% humidity. After leaving the pens in a landscape orientation for one week, the "Date of the Diet" was written by hand again, the distance of the smudge was measured, and the average value was taken as the value of the initial smudge (unit: mm).

[0047] The results are shown in Tables 1 to 3.

[0048] [Table 1]

[0049] [Table 2]

[0050] [Table 3]

[0051] The ballpoint pens of Examples 1 to 9 contain silicone composite particles in the ink, which have a structure in which silicone rubber particles are coated with silicone resin. Therefore, the particles are not broken by the impact of being pinched between the ball and the receiving seat when writing, and can be concentrated without forming an aggregated structure at points where the ink flow path narrows. This is thought to result in an excellent sealing effect even in low-humidity environments, making it possible to suppress ink leakage. Furthermore, since the ballpoint pens of Examples 4 to 7 contain silicone composite particles of less than 1 μm in the ink, it is believed that the ink sealing effect is further improved, thereby improving the effect in Pen Tip Ink Leakage Confirmation Test 1. Furthermore, since the ballpoint pens of Examples 2, 4, 5, and 7 to 9 contain hydroxypropyl cellulose, it is possible to prevent the spread of ink that leaks onto the acrylic plate, and it is thought that this has improved the effectiveness of Pen Tip Ink Leakage Confirmation Test 2. In addition to the effect of suppressing ink leakage, the ballpoint pens of Examples 1 to 8 use the silicone composite particles in combination with a phosphate ester, which eliminates the feeling of fatigue when writing and provides a unique writing feel that has never been experienced before. Furthermore, the ballpoint pens of Examples 2, 4 to 6, 8 and 9 used the silicone composite particles in combination with a resin having an acidic group, and therefore the distance of smudges at the first stroke was improved. Furthermore, in the ballpoint pens of Examples 4 to 6, a dispersant with an acid value of 100 mgKOH / g or more was used in combination, which improved the dispersion stability of the silicone composite particles, and no uneven distribution of the composite particles was observed in the refill after the dispersion stability confirmation test. The ballpoint pen of Comparative Example 1 does not contain the silicone composite particles in its ink, so it does not exhibit a sealing effect, resulting in ink leakage. The ballpoint pen of Comparative Example 2 contains silicone rubber particles, which increase the contact area due to surface deformation of the rubber powder, making it prone to aggregation. This weakens the sealing effect of the ink flow path within the ballpoint pen tip, resulting in ink leakage. The ballpoint pen of Comparative Example 3 contains silicone resin particles, which are broken by the impact of being pinched between the ball and the receiving seat during writing, resulting in irregular particle shapes. This disrupts the structure when the ink flow path narrows, resulting in insufficient sealing effect and ink leakage. The ballpoint pens of Comparative Examples 4 and 5 contain particles other than silicone, which cause particles to aggregate or break in the ink flow path, resulting in irregular particle shapes and insufficient sealing effect, resulting in ink leakage. The ballpoint pen of Comparative Example 6 contains ink containing a dye with a specific structure and a certain amount of butyral resin, but in low-humidity environments, it does not exhibit a sufficient sealing effect and ink leakage.

[0052] In this specification, expressions such as "identical," "equal," and "homogeneous" that indicate that things are in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

Claims

1. An oil-based ink for ballpoint pens, comprising at least silicone composite particles having a structure in which silicone rubber particles are coated with a silicone resin, and a dispersant.

2. 2. The oil-based ink for ballpoint pens according to claim 1, wherein the dispersant has an acid value of 100 mgKOH / g or more.

3. The silicone rubber particles are coated with a silicone resin. The silicone rubber particles are at least comprised of silicone composite particles. ... ―１ 1. An oil-based ink for a ballpoint pen, characterized in that the viscosity at 2000 kJ / min is 30 mPa·s or more and 3,000 mPa·s or less.

4. The silicone rubber particles are coated with a silicone resin. The silicone rubber particles are at least comprised of silicone composite particles. ... ―１ 1. An oil-based ink for a ballpoint pen, characterized in that the viscosity thereof is 50 mPa·s or more and 500 mPa·s or less.

5. The silicone rubber particles are coated with a silicone resin. The silicone rubber particles are at least comprised of silicone composite particles. ... ―１ 1. An oil-based ink for a ballpoint pen, characterized in that the viscosity thereof is 60 mPa·s or more and 200 mPa·s or less.

Images