JP7669761B2 - Water-based pigment ink composition for writing instruments - Google Patents

Description

The present invention relates to an aqueous pigment ink composition for writing instruments that uses pigments as coloring components to provide a coating liquid that is built into an applicator and that provides a concealing effect for the base, a shining effect for the coating marks, and water resistance for the coating marks.

Conventionally, aqueous pigment ink compositions for writing instruments have used pigments as coloring components to provide a concealing effect for the base, a shining effect for application marks, and water resistance for application marks. However, because pigments have a higher specific gravity than dyes and are dispersed and mixed rather than dissolved, the pigments gradually aggregate and settle over time as they are left to stand, forming a so-called hard cake that separates from the liquid, making it difficult to dispense from the application point of the writing instrument.
In ink compositions using such pigments, known means for delaying pigment aggregation and sedimentation include surface modification of the pigment with various surfactants and reducing the fluidity of the liquid by using thickeners or gelling agents.
For example, the invention described in Patent Document 1 discloses an aqueous ink composition for writing instruments that uses water-soluble resins such as acrylic resins, vinyl resins, and various resin emulsions, water-soluble polysaccharides such as cellulose derivatives, and inorganic thickeners such as montmorillonite-based clay minerals to produce an ink with a specific viscosity for a specific shear rate, thereby achieving good redispersibility even when left to stand at 40° C. for two weeks. Patent Document 2 discloses an aqueous pigment ink composition for use in ballpoint pens that uses a combination of multiple specific water-soluble polysaccharides to maintain the ink dispersion system stable and produce good handwriting even after storage for about two months at room temperature as well as at a low temperature of around 0° C. or a high temperature of around 60° C.

JP 2011-202086 A JP 2006-45429 A

The invention described in the above-mentioned patent document had a problem where the pen could not be written properly when left in an environment with temperatures below -5°C for an extremely long period of time (3 months or more).

The present invention aims to provide an aqueous pigment ink composition for writing instruments that can leave good marks even when left in a negative temperature environment of about -5°C for three months or more.

The first gist of the present invention is an aqueous pigment ink composition for a writing instrument, which comprises at least a pigment, an amino acid anionic surfactant made of an unsaturated fatty acid, an amino acid anionic surfactant made of a saturated fatty acid, and water, and the second gist of the present invention is an aqueous pigment ink composition for a writing instrument, which contains a resin emulsion and a plate-like inorganic compound.

According to an embodiment of the present invention, it is possible to provide an aqueous pigment ink composition for writing instruments that can be filled into writing instruments such as marking pens, brush pens, ballpoint pens, and correction fluid applicators, and that can be used for writing in a similar low-temperature environment after being stored in a negative environment for a long period of time.

That is, in the aqueous pigment ink composition for writing instruments of the present invention, an amino acid anionic surfactant made of unsaturated fatty acid and an amino acid anionic surfactant made of saturated fatty acid are bonded to the surface of the pigment, and a composite is formed in which the pigment surface is covered with an amino acid anionic surfactant made of unsaturated fatty acid and an amino acid anionic surfactant made of saturated fatty acid, and it is presumed that the interaction between the pigments is three-dimensionally gentle and the fluidity of the entire composition is not impaired even in a low temperature environment. Furthermore, when a resin emulsion or plate-like inorganic particles are added to this, in addition to the thickening effect of the solid matter, a gentle gel structure that envelops the pigment is formed by the gelling action of the plate-like inorganic particles such as bentonite, and in particular, a large gel structure composite is formed by the interaction between the amino acid anionic surfactant made of unsaturated fatty acid and the amino acid anionic surfactant made of saturated fatty acid and the gel structure formed by the plate-like inorganic particles, and it is presumed that this also suppresses the situation in which large plate-like pigments such as glittering plate-like aluminum or aluminum flakes as pigment particles are aligned and aggregated.

FIG.

The pigments used in the aqueous pigment ink composition for writing instruments of the present invention are used as coloring components to obtain a concealing effect for the base, a shining effect for the coating marks, and water resistance for the coating marks. Pigments that can be used are not particularly limited, and include organic pigments such as azo pigments, nitroso pigments, nitro pigments, basic dye pigments, acid dye pigments, vat dye pigments, mordant dye pigments, and natural dye pigments used in conventional aqueous inks and oil-based inks, inorganic pigments such as yellow ocher, barium yellow, Prussian blue, cadmium red, barium sulfate, titanium oxide, red iron oxide, iron black, and carbon black, and glitter pigments such as metal powders such as aluminum powder and bronze powder, metal-coated glass flakes, and metal-deposited films, as well as aqueous pigment bases in which pigments are dispersed in aqueous media. In particular, glitter pigments are used to form beautiful handwriting with a glittering feel.

Examples of the brilliant pigments include LG neo R-GOLD #35, LG neo B-GOLD #35, LG neo S-GOLD #35, LG neo R-GOLD #100, LG neo B-GOLD #100, LG neo S-GOLD #100, LG neo RED #100, LG neo BLUE #100, LG neo GREEN #100, LG neo VIOLET #100, LG neo BLACK #100, LG neo COPPER #100, LG neo PINK #100, and LG neo YELLOW. #100, LG neo R-GOLD #150, LG neo B-GOLD #150, LG neo S-GOLD #150, LG neo RED #150, LG neo BLUE #150, LG neo GREEN #150, LG neo VIOLET #150, LG neo BLACK #150, LG neo COPPER #150, LG neo PINK #150, LG neo YELLOW #150, LG neo R-GOLD #200, LG neo B-GOLD #200, LG neo S-GOLD #200, LG neo RED #200, LG neo BLUE #200, LG neo GREEN #200, LG neo VIOLET #200, LG neo BLACK #200, LG neo COPPER #200, LG neo PINK #200, LG neo YELLOW #200, LG neo R-GOLD #325, LG neo B-GOLD #325, LG neo S-GOLD #325, LG neo RED #325, LG neo BLUE #325, LG neo GREEN #325, LG neo VIOLET #325, LG neo BLACK #325, LG neo COPPER #325, LG neo PINK #325, LG neo YELLOW #325, LG neo SILVER #325, LG neo R-GOLD #500, LG neo B-GOLD #500, LG neo S-GOLD #500 (all manufactured by Oike Imaging Co., Ltd.), Diamond Peace LG Gold No. 55, Diamond Peace DG Gold No. 55, Diamond Peace Green No. 55, Diamond Peace Blue No. 55, Diamond Peace Red No. 55, Diamond Peace Maroon No. Diamond Piece Ocean Green No. 55, Diamond Piece Sky Blue No. 55, Diamond Piece Black No. 55, Diamond Piece Pink No. 55, Diamond Piece Violet No. 55, Diamond Piece Emerald No. 55, Diamond Piece Copper No. 55, Diamond Piece LG Gold H25, Diamond Piece DG Gold H25, Diamond Piece Green H25, Diamond Piece Blue H25, Diamond Piece Red H25, Diamond Piece Maroon H25, Diamond Piece Ocean Green H25, Diamond Piece Sky Blue H25, Diamond Piece Black H25, Diamond Piece Pink H25, Diamond Piece Violet H25, Diamond Piece Emerald H25, Diamond Piece Copper H25, Diamond Piece LG Gold H55, Diamond Piece DG Gold H55, Diamond Piece Green H55, Diamond Piece Blue H55, Diamond Piece Red H55, Diamond Piece Maroon H55, Diamond Piece Ocean Green H55, Diamond Piece Sky Blue H55, Diamond Piece Black H55, Diamond Piece Pink H55, Diamond Piece Violet H55, Diamond Piece Emerald H55, Diamond Piece Copper H55, Diamond Piece LG Gold CO-40UC, Diamond Piece DG Gold CO-40UC, Diamond Piece Green CO-40UC, Diamond Piece Blue CO-40UC, Diamond Piece Red CO-40UC, Diamond Piece Pink CO-40UC, Diamond Piece Lavender CO-40UC (all manufactured by Diamond Kogyo Co., Ltd.), Superfine No. 22000, No. 22000WN, No. 1800WN, No. 18000, Fine No. 900, No. 800 (all manufactured by Yamato Metal Powder Co., Ltd.), AA12, AA8, No. 900, No. 1800, PaleGold E5, 2L5, RichGold L7, 3L7, ECopper (all manufactured by Fukuda Metal Foil & Powder Co., Ltd.), Aluminum Powder 1000, 2700 (all manufactured by Nakatsuka Metal Foil & Powder Co., Ltd.), WB0230, WXM0630, Friend Color D452BL, Friend Color D462BL, Friend Color D851BL, Friend Color D451RE, Friend Color D462RE, Friend Color D111RE, Friend Color D452YE, Friend Color D462YE, Friend Color D85 1YE (all manufactured by Toyo Aluminium K.K.), stainless steel powder pigment, tin powder pigment, zinc powder pigment, nickel powder pigment, gold powder pigment, silver powder pigment, Metashine MT1030GP, Metashine MT2080GP, Metashine 2025PS, Metashine 1030PS, Metashine 2080PS, Metashine 5090PS, Metashine 5150PS, Metashine 5230PS, Metashine 5480PS (all manufactured by Nippon Sheet Glass Co., Ltd.).
When using a glittering pigment, the average particle size is preferably 10 μm or more in order to form beautiful handwriting with a glittering feel, and an average particle size of 30 μm or more is particularly preferable since it provides an even stronger glittering feel.

Inorganic pigments include aniline black (C.I. 50440), cyanine black, naphthol yellow S (C.I. 10316), Hansa Yellow 10G (C.I. 11710), Hansa Yellow 5G (C.I. 11660), Hansa Yellow 3G (C.I. 11670), Hansa Yellow G (C.I. 11680), Hansa Yellow GR (C.I. 11730), Hansa Yellow A (C.I. 11735), Hansa Yellow RN (C.I. 1740), Hansa Yellow R (C.I. 12710), Pigment Yellow L (C.
12720), Benzidine Yellow (C.I. 21090), Benzidine Yellow G (C.I. 21095), Benzidine Yellow GR (C.I. 21100), Permanent Yellow NCG (C.I. 20040), Balkan Fast Yellow 5G (C.I. 21220), Balkan Fast Yellow R (C.I. 21135), Tartrazine Lake (C.I. 19140), Quinoline Yellow Lake (C.I. 47005), Anthragen Yellow 6GL (C.I. 60520), Permanent Yellow FGL, Permanent Yellow H10G, Permanent Yellow HR, Anthrapyrimidine Yellow (C.I. 68420), Sudan I (C.I. 12055), Permanent Orange (C.I. 12075), Lithol Fast Orange (C.I. 12125), Permanent Orange GTR (C.I. 12305), Hansa Yellow 3R (C.I. 11725), Balkan Fast Orange GG (C.I. 21165), Benzidine Orange G (C.I. 21110), Persian Orange (C.I. 15510), Indanthrene Brilliant Orange GK (C.I. 59305), Indanthrene Brilliant Orange RK (C.I. 59105), Indanthrene Brilliant Orange GR (C.I. 71105), Permanent Brown FG (C.I. 12480), Para Brown (C.I. 12071), Permanent Red 4R (C.I. 12120), Para Red (C.I. 12070), Fire Red (C.I. 12085), Parachlor Orthoaniline Red (C.I. 12090), Lithol Fast Scarlet, Brilliant Fast Scarlet (C.I. 12315), Brilliant Carmine BS, Permanent Red F2R (C.I. 1 2310), Permanent Red F4R (C.I. 12335), Permanent Red FRL (C.I. 12440), Permanent Red FRLL (C.I. 12460), Permanent Red F4RH (C.I. 12420), Fast Scarlet VD, Balkan Fast Rubin B (C.I. 12320), Balkan Fast Pink G (C.I. 12330), Light Fast Red Toner B (C.I. 12450), Light Fast Red Toner R (C.I. 12455), Permanent Carmine FB (C.I. 12490), Pyrazolone Red (C.I. 12120), Lithol Red (C.I. 15630), Lake Red C (C.I. 15585), Lake Red D (C.I. 15500), Anthocine B (C.I. 18030), Brilliant Scarlet G (C.I. 15800), Lithol Rubin GK (C.I. 15825), Permanent Red F5R (C.I. 15865), Brilliant Carmine 6B (C.I. 15850), Pigment Scarlet 3B (C.I. 16105), Bordeaux 5B (C.I. 12170), Toluidine Maroon (C.I. 12350), Permanent Bordeaux F2R (C.I. 12385), Helio Bordeaux BL (C.I. 14830), Bordeaux 10B (C.I. 15880), Bon Maroon Light (C.I. 15825), Bon Maroon Medium (C.I. 15880), Eosin Lake (C.I. 45380), Rhodamine Lake B (C.I. 45170), Rhodamine Lake Y (C.I. 45160), Alizarin Lake (C.I. 58000), Thioindigo Red B (C.I. 73300), Thioindigo Maroon (C.I. 73385), Permanent Red FGR (C.I. 12370), PV Carmine HR, Watching Red, Monolight Fast Red YS (C.I. 59300), Permanent Red BL, Fast Violet B, Methyl Violet Lake (C.I. 42535), Dioxazine Violet, Alkali Blue Lake (C.I. 42750A, C.I. 42770A), Peacock Blue Lake (C.I. 42090), Peacock Blue Lake (C.I. 42025), Victoria Blue Lake (C.I. 42026), 4045), Phthalocyanine Blue (C.I. 74160), Fast Sky Blue (C.I. 74180), Indanthrene Blue RS (C.I. 69800), Indanthrene Blue BC (C.I. 69825), Indigo (C.I. 73000), Pigment Green B (C.I. 10006), Naphthol Green B (C.I. 10020), Green Gold (C.I. 12775), Acid Green Lake, Malachite Green Lake (C.I. 42000), Phthalocyanine Green, etc.

Water-based pigment bases include Fuji SP Black 8031, Fuji SP Black 8119, Fuji SP Black 8167, Fuji SP Black 8276, Fuji SP Black 8381, Fuji SP Black 8406, Fuji SP Red 5096, Fuji SP Red 5111, Fuji SP Red 5193, Fuji SP Red 5220, Fuji SP Bordeaux 5500, Fuji SP Blue 6062, Fuji SP Blue 6133, Fuji SP Blue 6134, Fuji SP Blue 6401, Fuji SP Green 7051, Fuji SP Yellow 4060, Fuji SP Yellow 4178, Fuji SP Violet 9011, Fuji SP Pink 9524, Fuji SP Pink 9527, Fuji SP Orange 534, Fuji SP Brown 3074, Fuji SP RED 5543, FUJI SP RED 5544 (manufactured by Fuji Shiki Co., Ltd.), Emacol Black CN, Emacol Blue FBB, Emacol Blue FB, Emacol Blue KR, Emacol Green LXB, Emacol Violet BL, Emacol Brown 3101, Emacol Carmine FB, Emacol Red BS, Emacol Orange R, Emacol Yellow FD, Emacol Yellow IRN, Emacol Yellow 3601, Emacol Yellow FGN, Emacol Yellow GN, Emacol Yellow GG, Emacol Yellow F5G, Emacol Yellow F7G, Emacol Yellow 10GN, Emacol Yellow 10G, Sandy Super Black K, Sandy Super Black C, Sandy Super Gray B, Sandy Super Brown SB, Sandy Super Brown FRL, Sandy Super Brown RR, Sandy Super Green L5G, Sandy Super Green GXB, Sandy Super Navy Blue HRL, Sandy Super Navy Blue GLL, Sandy Super Navy Blue HB, Sandy Super Navy Blue FBLH, Sandy Super Navy Blue FBL-160, Sandy Super Navy Blue FBB, Sandye Super Violet BL H/C, Sandye Super Violet BL, Sandye Super Bordeaux FR, Sandye Super Pink FBL, Sandye Super Pink F5B, Sandy Super Rubine FR, Sandy super Carmmine FB, Sandye Super Red FFG, Sandye Super Red RR, Sandye Super Red BS, Sandye Super Orange FL, Sandye Super Orange R, Sandye Super Orange BO, Sandye Gold Yellow 5GR, Sandye Gold Yellow R, Sandye Gold Yellow 3R, Sandye Yellow GG, Sandye Yellow F3R, Sandy Yellow IRC, Sandy Yellow FGN, Sandye Yellow GN, Sandye Yellow GRS, Sandye Yellow GSR-130, Sandye Yellow GSN-130, Sandye Yellow GSN, Sandye Yellow 10GN (all manufactured by Sanyo Pigment Co., Ltd.), Rio Fast Black Fx 8012, Rio Fast Black Fx 8313, Rio Fast Black Fx 8169, Rio Fast Red Fx 8209, Rio Fast Red Fx 8172, Rio Fast Red S Fx 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, NK W-2102P, NKW-2103P, NKW-2104P, NKW-2105P, NKW-2106P, NKW-2107P, NKW-2108P, NK W-2117P, NKW-2127P, NKW-2137P, NKW-2167P, NKW-3002, NKW-3003, NKW-3004, NKW-3 005, NKW-3007, NKW-3077, NKW-3008, NKW-3402, NKW-3404, NKW-3405, NKW-3407, NK W-3408, NKW-3477, NKW-3602, NKW-3603, NKW-3604, NKW-3605, NKW-3607, NKW-3677, NKW-3608, NKW-3702, NKW-3703, NKW-3704, NKW-3705, NKW-3777, NKW-3708, NKW-6013, NKW-6038, NKW-6559 (all manufactured by Nippon Fluorescent Co., Ltd.), Cosmo Color S1000F Series (manufactured by Toyo Soda Co., Ltd.), Victoria Yellow Examples include 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, and G-25 (all manufactured by Mikuni Color Co., Ltd.), and the Pollux series, including Pollux PC5T1020, Pollux Black PC8T135, and Pollux Red IT1030 (all manufactured by Sumika Color Co., Ltd.).

These pigments may be used alone or in combination of two or more.
The pigment content is preferably 0.5% by weight or more and 20.0% by weight or less based on the total amount of the aqueous pigment ink composition, and more preferably 1.0% by weight or more and 10.0% by weight or less. When the content is within the above range, the ink can be discharged stably without clogging the pen tip or brush tip while maintaining the fluidity at low temperatures.

As the colorant, a dye can be used in combination with the above pigments.
As the dye, direct dyes, acid dyes, basic dyes, etc., which are used in conventional water-based inks and oil-based inks, can be used.
Specifically, Japanol Fast Black D Concentrate (C.I. Direct Black 17), Water Black 100L (C.I. Direct Black 19), Water Black L-200 (C.I. Direct Black 19), Water Black 256L, Direct Fast Black B (C.I. Direct Black 22), Direct Fast Black AB (C.I. Direct Black 32), Direct Deep Black EX (C.I. Direct Black 38), Direct Fast Black Concentrate (C.I. Direct Black 51), Kayara Spray LaGrey VGN (C.I. Direct Black 71), Kayarusu Direct Brilliant Yellow G (C.I. Direct Yellow 4), Direct Fast Yellow 5GL (C.I. Direct Yellow 26), Aizen Primula Yellow GCLH (C.I. Direct Yellow 44), Direct Fast Yellow R (C.I. Direct Yellow 50), Aizen Direct Fast Red FH (C.I. Direct Red 1), Nippon Fast Scarlet GSX (C.I. Direct Red 4), Direct Fast Scarlet 4BS (C.I. Direct Red 23), Aizen Direct Rhoduline BH (C.I. Direct Red 31), Direct Scarlet B (C.I. Direct Red 37), Kayak Direct Scarlet 3B (C.I. Direct Red 39), Aizen Primula Pink 2BLH (C.I. Direct Red 75), Sumi Light Red F3B (C.I. Direct Red 80), Aizen Primula Red 4BH (C.I. Direct Red 81), Kayalas Spralubin BL (C.I. Direct Red 83), Kayalas Light Red F5G (C.I. Direct Red 225), Kayala Slight Red F5B (C.I. Direct Red 226), Kayalas Light Rose FR (C.I. Direct Red 227), Direct Sky Blue 6B (C.I. Direct Blue 1), Direct Sky Blue 5B (C.I. Direct Blue 15), Sumilight Sprat Blue BRR Concentrate (C.I. Direct Blue 71), Daibogen Turquoise Blue S (C.I. Direct Blue 86), Water Blue 3 (C.I. Direct Blue 86), Kayalas Turquoise Blue GL (C.I. Direct Blue 86), Kayalas Sprat Blue FF2GL (C.I. Direct Blue 106), Kayalas Splatter Turquoise Blue FBL (C.I. Direct Blue 199), and other direct dyes, Acid Blue Black 10B (C.I. Acid Black 1), Nigrosine (C.I. Acid Black 2), Suminol Milling Black 8BX (C.I. Acid Black 24), Kayanol Milling Black VLG (C.I. Acid Black 26), Suminol Fast Black BR Conc (C.I. Acid Black 31), Mitsui Nylon Black GL (C.I. Acid Black 52), Aizen Opal Black WH E Xtra Conc (C.I. Acid Black 52), Sumilan Black WA (C.I. Acid Black 52), Ranil Black BG Extra Conc (C.I. Acid Black 107), Kayanol Milling Black TLB (C.I. Acid Black 109), Sumilan Milling Black B (C.I. Acid Black 109), Kayanol Milling Black TLR (C.I. Acid Black 110), Aizen Opal Black New Conc (C.I. Acid Black 119), Water Black 187-L (C.I. Acid Black 154), Kayaku Acid Brilliant Flavin FF (C.I. Acid Yellow 7:1), Kayasil Yellow GG (C.I. Acid Yellow 17), Xylene Light Yellow 2G 140% (C.I. Acid Yellow 17), Suminol Leveling Yellow NR (C.I. Acid Yellow 19), Daiwa Tartrazine (C.I. Acid Yellow 23), Kayaku Tartrazine (C.I. Acid Yellow 23), Suminol Fast Yellow R (C.I. Acid Yellow 25), Diacid Light Yellow 2GP (C.I. Acid Yellow 29), Suminol Mimi Ring Yellow (C.I. Acid Yellow 38), Water Yellow 6 (C.I. Acid Yellow 42), Water Yellow 6C (C.I. Acid Yellow 42), Kayanol Yellow NFG (C.I. Acid Yellow 49), Suminol Milling Yellow 3G (C.I. Acid Yellow 72), Suminol Fast Yellow G (C.I. Acid Yellow 61), Suminol Milling Yellow G (C.I. Acid Yellow 78), Kayanol Yellow N5G (C.I. Acid Yellow 110), Suminol Milling Yellow 4G 200% (C.I. Acid Yellow 141), Kayanol Yellow NG (C.I. Acid Yellow 135), Kayanol Milling Yellow 5GW (C.I. Acid Yellow 127), Kayanol Milling Yellow 6GW (C.I. Acid Yellow 142), Sumitomo Fast Scarlet A (C.I. Acid Red 8), Kayaku Silk Scarlet (C.I. Acid Red 9), Solar Rubin Extra (C.I. Acid Red 14), Daiwa New Coccin (C.I. Acid Red 18), Water Red 1 (C.I. Acid Red 18), Aizen Bonso RH (C.I. Acid Red 26), Daiwa Red No. 2 (C.I. Acid Red 27), Suminol Leveling Brilliant Red S3B (C.I. Acid Red 35), Kayasil Rubinol 3GS (C.I. Acid Red 37), Aizen Erythrosine (C.I. Acid Red 51), Daiwa Red No. 106WB (C.I. Acid Red 52), Suminol Leveling Rubinol 3GP (C.I. Acid Red 57), Diacid Alizarin Rubinol F3G 200% (C.I. Acid Red 82), Aizen Eosin GH (C.I. Acid Red 87), Daiwa Red No. 104WB (C.I. Acid Red 92), Aizen Acid Phloxine PB (C.I. Acid Red 92), Rose Bengal (C.I. Acid Red 94), Kayanol Milling Scarlet FGW (C.I. Acid Red 111), Kayanol Milling Rubin 3BW (C.I. Acid Red 129), Suminoall Milling Brilliant Red 3BN Concentrate (C.I. Acid Red 131), Suminoall Milling Brilliant Red BS (C.I. Acid Red 138), Aizen Opal Pink BH (C.I. Acid Red 186), Suminoall Milling Brilliant Red B Concentrate (C.I. Acid Red 249), Kayakuashi Brilliant Red 3BL (C.I. Acid Red 254), Kayaku Acid Brilliant Red BL (C.I. Acid Red 265), Kayanol Milling Red GW (C.I. Acid Red 276), Mitsui Acid Violet 6BN (C.I. Acid Violet 15), Mitsui Acid Violet BN (C.I. Acid Violet 17), Sumitomo Patent Pure Blue VX (C.I. Acid Blue 1), Water Blue 106 (C.I. Acid Blue 1), Water Blue 119, Patent Blue AF (C.I. Acid Blue 7), Water Blue 9 (C.I. Acid Blue 9), Daiwa Blue No. 1 (C.I. Acid Blue 9), Supranol Blue B (C.I. Acid Blue 15), Orient Soluble Blue OBC (C.I. Acid Blue 22), Suminol Leveling Blue 4GL (C.I. Acid Blue 23), Mitsui Nylon Fast Blue G (C.I. Acid Blue 25), Kayasil Blue AGG (C.I. Acid Blue 40), Kayasil Blue BR (C.I. Acid Blue 41), Mitsui Alizarin Sapphirol SE (C.I. Acid Blue 43), Suminol Leveling Sky Blue R Extra Conc (C.I. Acid Blue 44), Blue 62), Mitsui Nylon Fast Sky Blue B (C.I. Acid Blue 78), Sumitomo Brilliant Indocyanine 6Bh/c (C.I. Acid Blue 83), Sandran Cyanine N-6B 350% (C.I. Acid Blue 90), Water Blue 115 (C.I. Acid Blue 90), Orient Soluble Blue OBB (C.I. Acid Blue 93), Sumitomo Brilliant Blue 5G (C.I. Acid Blue 103), Kayanol Milling Ultra Sky SE (C.I. Acid Blue 112), Kayanol Milling Shear Acid dyes such as Nin 5R (C.I. Acid Blue 113), Aizen Opal Blue 2 GLH (C.I. Acid Blue 158), Daiwa Guinea Green B (C.I. Acid Green 3), Acid Brilliant Milling Green B (C.I. Acid Green 9), Daiwa Green 70 (C.I. Acid Green 16), Kayanol Cyanine Green G (C.I. Acid Green 25), and Suminol Milling Green G (C.I. Acid Green 27); Aizen Kathiron Yellow 3 GLH (C.I. Basic Yellow 11), Aizen Kathiro Brilliant Yellow 5GLH (C.I. Basic Yellow 13), Sumiacrylic Yellow E-3RD (C.I. Basic Yellow 15), Maxilon Yellow 2RL (C.I. Basic Yellow 19), Astrazon Yellow 7GLL (C.I. Basic Yellow 21), Kayakryl Golden Yellow GL-ED (C.I. Basic Yellow 28), Astrazon Yellow 5GL (C.I. Basic Yellow 51), Eisenkachiron Orange GLH (C.I. Basic Orange 21), Eisenkachiron Brown 3GLH (C.I. Basic Orange 30), Rhodamine 6GCP (C.I. Basic Red 1), Aizen Astraphloxine (C.I. Basic Orange 12), Sumiacryl Brilliant Red E-2B (C.I. Basic Orange 15), Astrazon Red GTL (C.I. Basic Orange 18), Aizen Catilon Brilliant Pink BGH (C.I. Basic Orange 27), Maxillon Red GRL (C.I. Basic Orange 46), Aizen Methyl Violet (C.I. Basic Violet 1), Aizen Crystal Violet (C.I. Basic Violet 3), Examples of basic dyes include Eisen Rhodamine B (C.I. Basic Violet 10), Astrazon Blue G (C.I. Basic Blue 1), Astrazon Blue BG (C.I. Basic Blue 3), Methylene Blue (C.I. Basic Blue 9), Maxilon Blue GRL (C.I. Basic Blue 41), Eisen Catilon Blue BRLH (C.I. Basic Blue 54), Eisen Diamond Green GH (C.I. Basic Green 1), Eisen Malachite Green (C.I. Basic Green 4), and Bismarck Brown G (C.I. Basic Brown 1).
These dyes may be used alone or in combination of two or more.
The dye content is preferably 0.001% by weight or more and 30.0% by weight or less based on the total amount. If it is less than 0.001% by weight, color adjustment is insufficient, and if it is more than 30.0% by weight, the viscosity of the ink increases excessively and the writing feel tends to deteriorate.

The amino acid anionic surfactant comprising an unsaturated fatty acid and the amino acid anionic surfactant comprising a saturated fatty acid used in the present invention are used in combination.
The amino acid anionic surfactant is preferably used in an amount of 0.1% by weight to 5.0% by weight based on the total amount of the aqueous pigment ink composition. Within this range, stable ink ejection properties can be obtained while maintaining dispersion stability at low temperatures.

Examples of amino acid anionic surfactants made of unsaturated fatty acids include NIKKOL Sarcosinate OH (oleoyl sarcosine (condensation product of oleic acid and methylglycine)) and NIKKOL Sarcosinate OHV (oleoyl sarcosine (condensation product of oleic acid and methylglycine)) (both manufactured by Nikko Chemicals Co., Ltd.). Note that an unsaturated fatty acid is a fatty acid having a carbon-carbon double bond, and it is preferable for the carbon-carbon double bonds to have more cis-type carbon-carbon double bonds than trans-type carbon-carbon double bonds, as this will provide better fluidity.

Examples of amino acid anionic surfactants consisting of saturated fatty acids include Amisoft CS-11 (N-coconut oil fatty acid acyl-L-glutamic acid sodium), Amisoft CA (N-coconut oil fatty acid acyl-L-glutamic acid), Amisoft LA-D (N-lauroyl-L-glutamic acid), Amisoft HA-P (N-stearoyl-L-glutamic acid), Amisoft LS-11 (N-lauroyl-L-glutamic acid sodium), Amisoft MK-11 (N-myristoyl-L-glutamic acid potassium), Amisoft MS-11 (N-myristoyl-L-glutamic acid sodium), Amisoft GS-11P (N-acyl-L-glutamic acid sodium), Amisoft HS-11P (N-stearoyl-L-glutamic acid sodium), Amisoft CT-12 (N-coconut oil fatty acid acyl-L-glutamic acid) Amisoft LT-12 (aqueous solution of triethanolamine salt of lauroyl-L-glutamic acid), Amisoft CK-22 (aqueous solution of potassium salt of N-coconut fatty acid acyl-L-glutamic acid), Amisoft CS-22 (aqueous solution of sodium salt of N-coconut fatty acid acyl-L-glutamic acid) (all manufactured by Ajinomoto Healthy Supply Co., Ltd.), NIKKOL Alaninate LN-30 (30% aqueous solution of sodium lauroyl methylalanine), NIKKOL Sarcosinate CN-30 (30% aqueous solution of sodium cocoyl sarcosine (sodium salt of condensation product of coconut fatty acid and methylglycine)), NIKKOL Sarcosinate CT-30 (30% aqueous solution of triethanolamine salt of cocoyl sarcosine (condensation product of coconut fatty acid and methylglycine)), NIKKOL Examples of such surfactants include Sarcosinate LH (lauroyl sarcosine), NIKKOL Sarcosinate LN (sodium lauroyl sarcosine), NIKKOL Sarcosinate LN-30 (sodium lauroyl sarcosine, 30% aqueous solution), NIKKOL Sarcosinate LK-30 (potassium lauroyl sarcosine, 30% aqueous solution), NIKKOL Sarcosinate MN (sodium myristoyl sarcosine), and NIKKOL Sarcosinate PN (sodium palmitoyl sarcosine) (all manufactured by Nikko Chemicals Co., Ltd.). Amino acid anionic surfactants in which the amino acid moiety is glutamic acid are preferred because they have two carboxylic acids and therefore form a stable bond with the pigment. In addition, the amino acid anionic surfactant made of coconut oil fatty acid contains not only the amino acid anionic surfactant made of saturated fatty acid but also the amino acid anionic surfactant made of unsaturated fatty acid in an amount of several weight percent as an impurity, but when these are used alone, where the amount of the amino acid anionic surfactant made of unsaturated fatty acid is less than 10 weight percent, the substantial effect of the combined use is not exhibited. It is substantially necessary that the content of each of the amino acid anionic surfactant made of unsaturated fatty acid and the amino acid anionic surfactant made of saturated fatty acid is 10 weight percent or more relative to the total amino acid anionic surfactant content of the ink composition. If the content of the amino acid anionic surfactant made of unsaturated fatty acid is 20 weight percent or more relative to the total amino acid anionic surfactant content of the ink composition, and the content of the amino acid anionic surfactant made of saturated fatty acid is 20 weight percent or more relative to the total amino acid anionic surfactant content of the ink composition, the interaction between the pigments is three-dimensionally gentle, so that the fluidity of the entire composition is not impaired even in a low-temperature environment, and the effect of allowing good writing is enhanced, which is preferable.
Furthermore, when the content of the amino acid anionic surfactant consisting of an unsaturated fatty acid is 30% by weight or more relative to the total content of amino acid anionic surfactants in the ink composition, and the content of the amino acid anionic surfactant consisting of a saturated fatty acid is 30% by weight or more relative to the total content of amino acid anionic surfactants in the ink composition, this is particularly preferred because it makes the interaction between the pigments three-dimensionally gentle, does not impair the fluidity of the entire composition even in a low-temperature environment, and provides a higher effect of enabling good writing.

As the plate-like inorganic compound of the present invention, smectites and bentonites that can be dispersed in water to form a gel structure can be used. Bentonite is an inorganic mineral that is composed mainly of montmorillonite and is accompanied by secondary components such as quartz, cristobalite, feldspars, and carbonate minerals. A gentle gel structure that envelops the pigment is formed by the gelling action of plate-like inorganic particles such as bentonite, and in particular, a large gel structure complex is formed by the interaction between the amino acid activator made of unsaturated fatty acid and the amino acid activator made of saturated fatty acid and the gel structure formed by the plate-like inorganic particles, and this is used to suppress the situation in which large plate-like pigments such as glittering plate-like aluminum or aluminum flakes as pigment particles are aligned and aggregated, and to enable the pigment to be stably discharged onto the writing surface. Specific examples of the plate-like inorganic compound include OPTIGEL-WX, OPTIGEL-CG, OPTIGEL-CK, OPTIGEL-CK XR, OPTIGEL-CL, OPTIGEL-CMO, OPTIGEL-LX, OPTIGEL-W 724, OPTIGEL-WA, OPTIGEL-WH, OPTIGEL-WM, and OPTIGEL-WX. XR, LAPONITE-RD, LAPONITE-EP, LAPONITE-RDS, LAPONITE-JS, LAPONITE-S482 (all manufactured by BYK Japan Co., Ltd.), Wenger, Wenger HV, Wenger FW, Wenger 15, Wenger 23, Wenger SH, Wenger A, Wenger W-100, Wenger W-100U, Wenger W-200U, Wenger W-300U, Wenger W-300H Examples of such polyurethane foams include Esben NX, Esben NX80, Esben NZ, Esben NZ, 70 Esben NEZ, Esben NO12S, Esben NO12 (all manufactured by Hojun Co., Ltd.), Kunipia-F, Kunipia-G, Kunipia-G4, Moistnight-U, Moistnight-S, Sumecton-SA, Sumecton-ST, Sumecton-SWN, Sumecton-SWF, and Sumecton-SEN (all manufactured by Kunimine Co., Ltd.).
These plate-like inorganic compounds may be used alone or in combination of two or more.
The plate-like inorganic compound is preferably 0.05% by weight or more and 3.0% by weight or less based on the total amount of the aqueous pigment ink composition. More preferably, it is 0.1% by weight or more and 2.0% by weight or less. Within the above numerical range, the pigment does not clog the pen tip or tip while maintaining dispersion stability at low temperatures, and stable ink discharge is obtained. If it is more than 3.0% by weight, the viscosity of the ink increases extremely and the writing feel is easily deteriorated.

In the resin emulsion of the present invention, the hydrophobic portion binds to the amino acid anionic surfactant, imparting flexibility to the composite of amino acid surfactants consisting of unsaturated fatty acids and saturated fatty acids that covers the pigment surface, thereby imparting fluidity even at ultra-low temperature conditions where diffusion phenomena are minimal.
Examples of the resin emulsion include urethane resin emulsion, acrylic resin emulsion, acrylic-urethane resin emulsion, and vinyl acetate resin emulsion.
Specifically, examples of the urethane resin emulsions include U-coat UWS-145 (solid content 35%), U-coat UX-300 (solid content 38%), U-coat UX-310 (solid content 40%), Permarin UA-150 (solid content 30%), Permarin UA-200 (solid content 30%), Permarin UA-368 (solid content 50%), and Permarin UA-4000 (solid content 38%) (all manufactured by Sanyo Chemical Industries, Ltd.), Acrit WBR-016U (solid content 30%) (manufactured by Taisei Fine Chemical Co., Ltd.), Neosticker 200 (solid content 35%), Neosticker 400 (solid content 37%), Neosticker 700 (solid content 37%), Neosticker 1200 (solid content 37%), Evafanol HA-15 (solid content 30%), and Evafanol HA-107C (solid content 40%), Evafanol HA-50C (solid content 35%), Evafanol HA-170 (solid content 37%), Evafanol HA-560 (solid content 35%) (all manufactured by Nicca Chemical Co., Ltd.), acrylic resin emulsions, Bonron XGS-001 (solid content 45%), Bonron XPL-100 (solid content 30%), Bonron XPL-200 (solid content 44%), Bonron PS-001 (solid content 50%), Bonron PS-002 (solid content 45%), Bonron XPS-004 (solid content 45%), Bonron XHS-20 (solid content 40%), Bonron XHS-21S (solid content 45%), Bonron XHS-50 (solid content 20%), Bonron S-119H (50% solids), Bonron S-416BF (44.5% solids), Bonron S-415 (44% solids), Bonron S-403 (25% solids), Bonron S-476 (45% solids), Bonron S-1120 (45% solids), Bonron S-483TBF (45% solids), Bonron S-434 (45% solids), Bonron S-1360 (44.5% solids) (all manufactured by Mitsui Chemicals, Inc.), DM772 (46% solids), DM774 (46% solids) (all manufactured by Japan Coating Resin Co., Ltd.), Acrylic AKW-107 (30% solids), Acrylic ATW-008S (29.5% solids) (all manufactured by Taisei Fine Chemical Co., Ltd.), Joncryl 7100 (solid content 48.0%), Joncryl 711 (solid content 42.0%), Joncryl PDX-7370 (solid content 42.0%), Joncryl PDX-7323 (solid content 42.0%), Joncryl PDX-7611 (solid content 36.5%), Joncryl 352D (solid content 45.0%), Joncryl 538J (solid content 45.0%), Joncryl PDX-7700 (solid content 48.0%), Joncryl PDX-7177 (solid content 36.0%), Joncryl 7001 (solid content 87.0%) (all manufactured by BASF (Germany)), Aquabrid 46777 (solid content 30%), Aquabrid UX-100 (48% solids), AQUABRID UX-110 (48% solids), AQUABRID AST531 (56% solids), AQUABRID AST499 (40% solids), Cevian-A886 (42% solids) (all manufactured by Daicel FineChem Co., Ltd.), BONCOAT 40-418EF (55% solids), BONCOAT 5400EF (55% solids), BONCOAT 5495EF (55% solids), BONCOAT CG-8400 (50% solids), BONCOAT CG-8490 (50% solids), BONCOAT CG-8520 (49% solids), BONCOAT CG-8680 (50% solids), BONCOAT CM-8430 (40% solids), BONCOAT CP-6450 (40% solids), BONCOAT DV-961 (40% solids), Boncoat EC-740EF (40% solids), Boncoat EC-905EF (50% solids), Boncoat SFC-55 (40% solids) (all manufactured by DIC Corporation), Acrylic-urethane resin emulsions ACRYL WEM-202U (40% solids), ACRYL WEM-321U (38% solids), ACRYL WEM-3008 (32.5% solids) (all manufactured by Taisei Fine Chemical Co., Ltd.), vinyl acetate resin emulsions Polysol S-5J (52% solids), Polysol AX-590 (49% solids), Polysol AX-751 (46% solids), Polysol AX-428J (46% solids), Polysol AX-510ZL (43% solids), Polysol AX-951 (solid content 41%), Polysol AX-1000 (solid content 39%), Polysol BX-8004 (solid content 48%), Polysol AX-747L (solid content 50%), Polysol P-503 (solid content 40%), Polysol PS-120 (solid content 50%), Polysol Examples of suitable polyolefin resins include S-65 (solid content 50%) (all manufactured by Showa Denko K.K.), Cevian-A210 (solid content 52%), Cevian-A215 (solid content 52.5%), Cevian-A217 (solid content 52.5%), Cevian-A218 (solid content 59%), Cevian-A220 (solid content 48%), Cevian-A240 (solid content 53.5%), Cevian-A415 (solid content 55%) and Cevian-A435 (solid content 57%) (all manufactured by Daicel FineChem Ltd.).
These resin emulsions may be used alone or in combination of two or more.
The resin emulsion is preferably 1.0% by weight or more and 10.0% by weight or less in terms of solid content based on the total amount of the aqueous pigment ink composition, in which case stable ink dischargeability can be obtained while maintaining fluidity at low temperatures.

Water is used as the main solvent of the ink. In the present invention, the main solvent means a solvent that occupies 50% by weight or more of the total amount of solvents in the total amount of the ink composition. It is preferable to use ion-exchanged water or purified water.
Furthermore, the organic solvent is not particularly limited and may be used in combination as long as it is an organic solvent that has been conventionally known for the purpose of achieving various qualities as an ink, such as preventing the ink from freezing at low temperatures and preventing the ink from drying at the pen tip. Specific examples of the organic solvent include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, thiodiethylene glycol, glycerin, benzyl glycol, and benzyl diglycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, sulfolane, dipropylene glycol monoethyl ether, ethylene glycol monobutyl ether, and ethylene glycol monohexyl ether. Examples of the organic solvent include glycol ethers such as 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 solvents such as isopropyl alcohol, 3-methyl-3-methoxy-1-butanol, benzyl alcohol, α-methylbenzyl alcohol, lauryl alcohol, tridecyl alcohol, isododecyl alcohol, and isotridecyl alcohol, as well as propylene glycol methyl ether acetate, propylene glycol diacetate, 2-pyrrolidone, N-methyl-2-pyrrolidone, sulfolane, and γ-butyrolactone. These organic solvents may be used alone or in combination of two or more.

The pH of the ink composition can be adjusted by using a pH adjuster such as a basic substance such as sodium hydroxide, lithium hydroxide, triethanolamine, diethanolamine, monoethanolamine, aminomethylpropanediol, or a conventionally known acidic substance. By adjusting the pH to 6.0 or more and 10.0 or less using these pH adjusters, the fluidity maintaining effect of the ink composition is further improved. Furthermore, by adjusting the pH to 7.0 or more and 9.0 or less, it becomes easier to form bonds between the amino acid anionic surfactant made of unsaturated fatty acid and the amino acid anionic surfactant made of saturated fatty acid and the pigment surface, and it is expected that the fluidity of the aqueous pigment ink composition for writing instruments will be maintained for a long time. These pH adjusters may be used alone or in combination of two or more types.

In addition, various additives can be used as necessary.
For example, wax emulsions can be used to improve pigment adhesion. Specifically, RK-185 (solid content 45%) (manufactured by GOO Chemical Industry Co., Ltd.) and WE-65 (solid content 35%) (manufactured by Konishi Co., Ltd.) made of paraffin wax, and Chemipearl W100 (solid content 40%), Chemipearl W200 (solid content 40%), Chemipearl W300 (solid content 40%), Chemipearl W310 (solid content 40%), Chemipearl W400 (solid content 40%), Chemipearl W4005 (solid content 40%), Chemipearl W401 (solid content 40%), Chemipearl W410 (solid content 40%), Chemipearl W500 (solid content 40%), Chemipearl WF640 (solid content 40%), Chemipearl W700 (solid content 40%), Chemipearl W800 (solid content 40%), ...40 W900 (solid content 40%), Chemipearl W950 (solid content 40%) (all manufactured by Mitsui Chemicals, Inc.), HYTEC E-6500 (solid content 35%), HYTEC E-9015 (solid content 40%), HYTEC E-6400 (solid content 35%), HYTEC E-8237 (solid content 40%), HYTEC E-5403P (solid content 30%), HYTEC E-1000 (solid content 35%), HYTEC E-4A (solid content 35%) (all manufactured by Toho Chemical Industry Co., Ltd.), HYTEC P-9018 (solid content 35%), HYTEC P-5300 (solid content 30%), HYTEC P-5800 (solid content 30%), HYTEC P-5060P (solid content 40%) (all manufactured by Toho Chemical Industry Co., Ltd.), Chemipearl A100 (solid content 40%) made of ethylene-α-olefin copolymer (manufactured by Mitsui Chemicals, Inc.), Chemipearl V100 (solid content 40%), Chemipearl V200 (solid content 40%), and Chemipearl V300 (solid content 40%) made of ethylene-vinyl acetate copolymer resin (all manufactured by Mitsui Chemicals, Inc.), HYTEC S-3121 (solid content 25%), HYTEC S-3800 (solid content 25%), HYTEC S-9242 (solid content 20%), HYTEC S-9200 (solid content 20%), HYTEC S-8512 (solid content 25%), and HYTEC S-3148K (solid content 25%) (all manufactured by Toho Chemical Industry Co., Ltd.) and the like.
These wax emulsions may be used alone or in combination of two or more kinds.
As preservatives and antifungals for the aqueous pigment ink composition, sodium dehydroacetate, 1,2-benzisothiazaline-3-one, 2-pyridinethiol-1-oxide sodium salt, etc. can also be used. These preservatives and antifungals have a synergistic effect when combined with 1,2-benzisothiazaline-3-one and 2-pyridinethiol-1-oxide sodium salt, and the preservative and antifungal effect can be obtained with a smaller content.

The viscosity of the aqueous pigment ink composition for writing instruments of the present invention is appropriately adjusted according to the embodiment, such as a direct-fill marker, ballpoint pen, brush, calligraphy pen, correction fluid, etc., and is not particularly limited. By appropriately adjusting the viscosity according to the embodiment, writing performance and storage stability, such as writing feel, uniformity of handwriting, handwriting density, suppression of bleeding, ink discharge stability, control of handwriting bleed-through to the paper, suppression of handwriting smearing, suppression of drying of the pen tip and tip, writing performance when dry, and pigment dispersion stability, are ensured, which is preferable.

In producing the aqueous pigment ink composition for writing instruments of the present invention, various conventionally known methods can be used. For example, water and bentonite are put into a Henschel mixer, propeller agitator, homogenizer, turbo mixer, high-pressure homogenizer, fine flow mill, or other agitator having high shear force, and then the pigment dispersed by a dispersing machine such as a Henschel mixer, propeller agitator, homogenizer, turbo mixer, high-pressure homogenizer, ball mill, bead mill, roll mill, or other dispersing machine and other remaining components are added, and further mixed and stirred to obtain the composition. In addition, in these preparation steps, the generated dispersion heat can be used for stirring as it is, or the mixture can be heated or cooled and stirred. Removal of bubbles by a defoamer or filtration of coarse particles by a filter may be performed as necessary. These various mixing steps, dispersion steps, filtration steps, heating steps, and cooling steps may each be performed alone, or two or more steps may be performed in parallel.

The aqueous pigment ink composition for writing instruments of the present invention can be suitably used by filling it into a writing instrument, but the use is not limited to writing instruments and may also be used in cosmetic applicators such as eyeliner and eyebrow applicators.
In addition, a system may be used that includes a temporary ink reservoir member having a comb-like cross section that directly stores ink in the coating liquid storage chamber without using an ink absorbing body such as a fiber bundle, or a system that includes a valve mechanism that automatically opens and closes in response to operation or changes in internal pressure.
When the aqueous pigment ink composition used uses titanium oxide or a large-diameter plate-shaped glittering pigment, it is preferable to directly store the ink composition in a fiber bundle called batting so that the ink stored in the coating liquid storage chamber is used up, and the ink supply mechanism to the coating destination is preferably one that uses a valve mechanism that can ensure a relatively large ink passage rather than one that passes through fine holes in a fiber bundle or a temporary ink reservoir member with a comb-like cross section, or one that is equipped with a ballpoint pen or tip valve mechanism that controls the ink discharge with a valve formed at the pen tip. Furthermore, by using a brush-type coating destination that can freely form wide coating marks as desired, wide coating marks that demonstrate the glittering properties of the ink can be formed.

FIG. 1 shows an example of the structure of a writing implement.
This is a brush pen type applicator that uses a relatively soft object such as a brush tip as the application tip, has a valve mechanism located at the connection between the application tip and the application liquid storage chamber, and opens and closes the valve mechanism by knocking the rear end to control the ink supply to the application tip, a so-called rear end knock type valve mechanism.
The barrel 1 is provided with an application tip 2 at its tip and a push-in type operating section 3 at its rear end, and a cap 4 that protects the application tip 2 can be fitted to the tip of the barrel 1. The cap 4 has a rolling prevention rib 4a on its side wall that prevents the applicator from rolling when attached.
The barrel 1 has a front barrel 1a having an opening through which the application tip 2 protrudes, and a rear barrel 1b to which an operating part 3 is connected.

The front part of the front barrel 1a is small in diameter to match the diameter of the pen tip, and the rear part is large in diameter to connect to the rear barrel 1b. The inner wall of the small diameter part has vertical ribs 5 evenly arranged around the circumference to support the pen tip. The grooves 6 formed between the vertical ribs 5 also serve as air passages to take in the volume of the ink composition discharged by writing application. The rear large diameter part of the front barrel 1a is also equipped with a valve seat member 7 of a valve mechanism that controls the flow of ink. The valve seat member 7 has a central hole 7a at its center, which serves as an ink passage, and its peripheral part serves as a valve seat that can come into circumferential contact with the valve rod described below. The valve seat member 7 also has a coil spring 9 fixed to its rear end, which urges the valve rod 8 backward to keep it in close contact with the valve seat at all times when not in operation.

The rear barrel 1b has a rear hole 10 at its rear end, in which the operating part 3 is located. A connecting rod 11 that transmits the pushing operation of the operating part 3 to the valve rod 8 protrudes from the rear hole 10 and is liquid-tightly sealed by a packing member 12 made of a material with rubber elasticity and having a soft hinge part 12a. When the operating part 3 is pushed toward the inside of the barrel, it abuts against the rear end of the packing member 12, and the packing member 12 receives a pushing force, causing the hinge part 12a to deform and transmit the pushing force to the connecting rod 11. As the connecting rod 11 advances, the valve rod 8 advances against the elastic force of the coil spring 9, releasing the valve mechanism and allowing the ink composition to flow. The coil spring 9 abuts against the tip surface of the connecting rod 11, which is the connecting step between the connecting rod 11 and the valve rod 8, and urges the connecting rod 11 and the valve rod 8 backward. When the pressing operation is released, the connecting rod 11 and the valve rod 8 move backward to close the valve mechanism.

A coating tip connection tube 13 is attached to the front end of the valve rod 8, and a brush-shaped coating tip 2 is connected to the front end of the coating tip connection tube 13. Thus, the coating tip 2 also moves forward in conjunction with the pressing of the operating part 3, and when the pressing operation is released, the coating tip 2 also moves backward due to the elastic force of the coil spring 9. In this way, an external force is applied to the ink composition present in the space around the coating tip 2 with each operation, preventing it from drying and solidifying, and also assists in ejecting the ink composition. This mechanism is particularly effective when using a liquid with a relatively high solid content.

The inside of the rear shaft 1b is mainly the coating liquid storage chamber, and a cylindrical polypropylene volume adjuster 14 for adjusting the volume of the coating liquid storage chamber is arranged to surround the connecting rod 11 as an internal member. The volume adjuster 14 may be fixed to the rear shaft 1b, but it is preferable to keep it in an unfixed state so that it can move back and forth freely in relation to the operating connecting rod 11. Reducing the volume of the coating liquid storage chamber in this way suppresses the ink composition from being blown out by the expanded gas when the valve mechanism is opened, which expands due to changes in temperature and pressure when the gaseous matter containing the air or the solvent of the ink composition volatilizes. In addition, by using a transparent or translucent material for the rear shaft, when a glittering pigment or white titanium oxide is used as a coloring agent, it is possible to narrow at least a portion of the gap to make it easier to visually check the color of the ink composition contained therein and the remaining amount of the ink composition. In addition, the color of the volume adjuster 14 can be made black, white, milky white, etc. to make the color of the ink composition even easier to visually check.

When the rear shaft 1b is pressed to eject the ink composition, the rear shaft 1b can be made of a flexible material such as a polyolefin resin such as low-density polyethylene, high-density polyethylene, or polypropylene, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate, polyamide, polyacrylonitrile, polycarbonate, polyvinyl chloride, polystyrene, polyoxymethylene, or various elastomers.

The present invention will now be described in more detail with reference to examples.

(Preparation of Ink Composition)
Ink compositions of Examples 1 to 281 , Comparative Examples 1 to 54 , and Reference Examples 1 to 5 were prepared according to the blending compositions shown in Tables 1 to 35 below.

Specifically, the following materials were used for each composition shown in Tables 1 to 35 .
<Pigments>
GP-1: LG neo RED #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-2: LG neo GREEN #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-3: LG neo BLUE #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-4: LG neo YELLOW #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-5: LG neo PINK #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-6: LG neo B-GOLD #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-7: LG neo SILVER #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-8: LG neo VIOLET #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-9: LG neo R-GOLD #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-10: LG neo S-GOLD #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-11: LG neo BLACK #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-12: LG neo COPPER #325 (metal-coated film powder glitter pigment, average particle size 35 μm, manufactured by Oike Imaging Co., Ltd.)
GP-13: LG neo B-GOLD #35 (metal-coated film powder glitter pigment, manufactured by Oike Imaging Co., Ltd.)
GP-14: LG neo GREEN #100 (metal-coated film powder glitter pigment, average particle size 115 μm, manufactured by Oike Imaging Co., Ltd.)
GP-15: LG neo GREEN #150 (metal-coated film powder glitter pigment, average particle size 95 μm, manufactured by Oike Imaging Co., Ltd.)
GP-16: LG neo YELLOW #150 (metal-coated film powder glitter pigment, average particle size 95 μm, manufactured by Oike Imaging Co., Ltd.)
GP-17: LG neo GREEN #200 (metal-coated film powder glitter pigment, average particle size 60 μm, manufactured by Oike Imaging Co., Ltd.)
GP-18: LG neo BLUE #200 (metal-coated film powder glitter pigment, average particle size 60 μm, manufactured by Oike Imaging Co., Ltd.)
GP-19: LG neo B-GOLD #500 (metal-coated film powder glitter pigment, average particle size 15 μm, manufactured by Oike Imaging Co., Ltd.)
CB-1: FUJI SP BLACK 8041 (black pigment dispersion, carbon black, manufactured by Fuji Pigment Co., Ltd.)
CB-2: Carbon black MA-100 (carbon black, manufactured by Mitsubishi Chemical Corporation)
CB-3: Lovecolor 220 (MD) Black (acrylic copolymer fine particles, manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
OP-1: FUJI SP BLUE 6555 (blue pigment dispersion, organic pigment, manufactured by Fuji Pigment Co., Ltd.)
OP-2: FUJI SP BLUE 6401 (blue pigment dispersion, organic pigment, manufactured by Fuji Pigment Co., Ltd.)
TO-1: CR-50 (titanium oxide, manufactured by Ishihara Sangyo Kaisha, Ltd.)
JR-1: Ropeake OP-84J (hollow resin particles, manufactured by Rohm and Haas Japan Co., Ltd.)
JR-2: Eposter S6 (melamine, benzoguanamine-based fine particles, Nippon Shokubai Co., Ltd.)

<Amino acid anionic surfactants made from unsaturated fatty acids>
UFAA-1: NIKKOL Sarcosinate OH (oleoyl sarcosine (condensation product of oleic acid and methylglycine), manufactured by Nikko Chemicals Co., Ltd.)
UFAA-2: NIKKOL Sarcosinate OHV (oleoyl sarcosine (condensation product of oleic acid and methylglycine), manufactured by Nikko Chemicals Co., Ltd.)

<Amino acid anionic surfactants made from saturated fatty acids>
SFAA-1: Amisoft CS-11 (N-coconut oil fatty acid acyl-L-sodium glutamate, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-2: Amisoft CA (N-coconut oil fatty acid acyl-L-glutamic acid, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-3: Amisoft LA-D (N-lauroyl-L-glutamic acid, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-4: Amisoft HA-P (N-stearoyl-L-glutamic acid, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-5: Amisoft LS-11 (Sodium N-lauroyl-L-glutamate, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-6: Amisoft MK-11 (potassium N-myristoyl-L-glutamate, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-7: Amisoft MS-11 (N-myristoyl-L-sodium glutamate, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-8: Amisoft GS-11P (N-acyl-L-sodium glutamate, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-9: Amisoft HS-11P (N-stearoyl-L-glutamic acid sodium, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-10: Amisoft CT-12 (aqueous solution of N-coconut oil fatty acid acyl-L-glutamic acid triethanolamine salt, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-11: Amisoft LT-12 (aqueous solution of lauroyl-L-glutamic acid triethanolamine salt, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-12: Amisoft CK-22 (aqueous solution of N-coconut fatty acid acyl-L-glutamic acid potassium salt, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-13: Amisoft CS-22 (aqueous solution of N-coconut oil fatty acid acyl-L-glutamic acid sodium salt, manufactured by Ajinomoto Healthy Supply Co., Ltd.)
SFAA-14: NIKKOL Alaninate LN-30 (a 30% aqueous solution of sodium lauroylmethylalanine, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-15: NIKKOL Sarcosinate CN-30 (30% aqueous solution of sodium cocoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-16: NIKKOL Sarcosinate CT-30 (30% aqueous solution of cocoyl sarcosine triethanolamine salt, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-17: NIKKOL Sarcosinate LH (Lauroyl Sarcosine, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-18: NIKKOL Sarcosinate LN (sodium lauroyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-19: NIKKOL Sarcosinate LN-30 (sodium lauroyl sarcosine, 30% aqueous solution, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-20: NIKKOL Sarcosinate LK-30 (potassium lauroyl sarcosine, 30% aqueous solution, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-21: NIKKOL Sarcosinate MN (sodium myristoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.)
SFAA-22: NIKKOL Sarcosinate PN (sodium palmitoyl sarcosine, manufactured by Nikko Chemicals Co., Ltd.)

<Phosphate ester type anionic surfactant>
REA-1: Phosphanol RB-410 (polyoxyethylene lauryl ether phosphate, manufactured by Toho Chemical Industry Co., Ltd.)

<Resin emulsion>
EM-1: U-coat UWS-145 (urethane resin emulsion, solid content 35%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-2: U-coat UX-300 (urethane resin emulsion, solid content 38%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-3: U-coat UX-310 (urethane resin emulsion, solid content 40%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-4: Permarin UA-150 (urethane resin emulsion, solid content 30%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-5: Permarin UA-200 (urethane resin emulsion, solid content 30%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-6: Permarin UA-368 (urethane resin emulsion, solid content 50%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-7: Permarin UA-4000 (urethane resin emulsion, solid content 38%, manufactured by Sanyo Chemical Industries, Ltd.)
EM-8: Acrit WBR-016U (urethane resin emulsion, solid content 30%, manufactured by Taisei Fine Chemical Co., Ltd.)
EM-9: Bonlon XGS-001 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-10: Bonlon XPL-100 (acrylic resin emulsion, solid content 30%, manufactured by Mitsui Chemicals, Inc.)
EM-11: Bonlon XPL-200 (acrylic resin emulsion, solid content 44%, manufactured by Mitsui Chemicals, Inc.)
EM-12: Bonlon PS-001 (acrylic resin emulsion, solid content 50%, manufactured by Mitsui Chemicals, Inc.)
EM-13: Bonlon PS-002 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-14: Bonlon XPS-004 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-15: Bonlon XHS-20 (acrylic resin emulsion, solid content 40%, manufactured by Mitsui Chemicals, Inc.)
EM-16: Bonlon XHS-21S (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-17: Bonlon XHS-50 (acrylic resin emulsion, solid content 20%, manufactured by Mitsui Chemicals, Inc.)
EM-18: Bonlon S-119H (acrylic resin emulsion, solid content 50%, manufactured by Mitsui Chemicals, Inc.)
EM-19: Bonlon S-416BF (acrylic resin emulsion, solid content 44.5%, manufactured by Mitsui Chemicals, Inc.)
EM-20: Bonlon S-415 (acrylic resin emulsion, solid content 44%, manufactured by Mitsui Chemicals, Inc.)
EM-21: Bonlon S-403 (acrylic resin emulsion, solid content 25%, manufactured by Mitsui Chemicals, Inc.)
EM-22: Bonlon S-476 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-23: Bonlon S-1120 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-24: Bonlon S-483TBF (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-25: Bonlon S-434 (acrylic resin emulsion, solid content 45%, manufactured by Mitsui Chemicals, Inc.)
EM-26: Bonlon S-1360 (acrylic resin emulsion, solid content 44.5%, manufactured by Mitsui Chemicals, Inc.)
EM-27: DM772 (acrylic resin emulsion, solid content 46%, manufactured by Japan Coating Resin Co., Ltd.)
EM-28: DM774 (acrylic resin emulsion, solid content 46%, manufactured by Japan Coating Resin Co., Ltd.)
EM-29: Acrylit ATW-008S (acrylic resin emulsion, solid content 29.5%, manufactured by Taisei Fine Chemical Co., Ltd.)
EM-30: Joncryl 7100 (acrylic resin emulsion, solid content 48%, manufactured by BASF (Germany))
EM-31: Joncryl 711 (acrylic resin emulsion, solid content 42%, manufactured by BASF (Germany))
EM-32: Joncryl PDX-7370 (acrylic resin emulsion, solid content 42%, manufactured by BASF (Germany))
EM-33: Joncryl PDX-7323 (acrylic resin emulsion, solid content 42%, manufactured by BASF (Germany))
EM-34: Joncryl PDX-7611 (acrylic resin emulsion, solid content 36.5%, manufactured by BASF (Germany))
EM-35: Joncryl 352D (acrylic resin emulsion, solid content 45%, manufactured by BASF (Germany))
EM-36: Joncryl 538J (acrylic resin emulsion, solid content 45%, manufactured by BASF (Germany))
EM-37: Joncryl PDX-7700 (acrylic resin emulsion, solid content 48%, manufactured by BASF (Germany))
EM-38: Joncryl PDX-7177 (acrylic resin emulsion, solid content 36%, manufactured by BASF (Germany))
EM-39: Joncryl 7001 (acrylic resin emulsion, solid content 87%, manufactured by BASF (Germany))
EM-40: Acrit WEM-321U (acrylic urethane resin emulsion, solid content 38%, manufactured by Taisei Fine Chemical Co., Ltd.)
EM-41: Polysol S-5J (vinyl acetate resin emulsion, solid content 52%, manufactured by Showa Denko K.K.)
EM-42: Polysol AX-590 (vinyl acetate resin emulsion, solid content 49%, manufactured by Showa Denko K.K.)
EM-43: Polysol AX-751 (vinyl acetate resin emulsion, solid content 46%, manufactured by Showa Denko K.K.)
EM-44: Polysol AX-428J (vinyl acetate resin emulsion, solid content 46%, manufactured by Showa Denko K.K.)
EM-45: Polysol AX-510ZL (vinyl acetate resin emulsion, solid content 43%, manufactured by Showa Denko K.K.)
EM-46: Polysol AX-951 (vinyl acetate resin emulsion, solid content 41%, manufactured by Showa Denko K.K.)
EM-47: Polysol AX-1000 (vinyl acetate resin emulsion, solid content 39%, manufactured by Showa Denko K.K.)
EM-48: Polysol BX-8004 (vinyl acetate resin emulsion, solid content 48%, manufactured by Showa Denko K.K.)
EM-49: Polysol AX-747L (vinyl acetate resin emulsion, solids content 50%, manufactured by Showa Denko K.K.)
EM-50: Polysol P-503 (vinyl acetate resin emulsion, solid content 40%, manufactured by Showa Denko K.K.)
EM-51: Polysol PS-120 (vinyl acetate resin emulsion, solids content 50%, manufactured by Showa Denko K.K.)
EM-52: Polysol S-65 (vinyl acetate resin emulsion, solids content 50%, manufactured by Showa Denko K.K.)

<Water-soluble resin>
WS-1: SMA1440 (water-soluble resin, styrene-maleic acid resin, manufactured by Arco Chemical Co., Ltd.)
WS-2: Joncryl 52J (styrene acrylic resin aqueous solution, solid content: 60%, manufactured by BASF (Germany))
WS-3: Joncryl 62J (water-soluble resin, manufactured by BASF (Germany))

<Dye>
D-1: Water Black 256L (a 14% aqueous solution of black dye, manufactured by Orient Chemical Industries Co., Ltd.)
D-2: Water Red 1 (C.I. Acid Red 18, manufactured by Orient Chemical Industry Co., Ltd.)
D-3: Daiwa Red No. 104WB (C.I. Acid Red 92, manufactured by Daiwa Chemical Industries, Ltd.)
D-4: Daiwa Red No. 106WB (C.I. Acid Red 52, manufactured by Daiwa Chemical Industries, Ltd.)
D-5: Water Yellow 6C (C.I. Acid Yellow 42, Orient Chemical Industry Co., Ltd.
D-6: Water Blue 119 (Orient Chemical Industry Co., Ltd.)
D-7: Daiwa Blue No. 1 (C.I. Acid Blue 9, manufactured by Daiwa Chemical Industries, Ltd.)

<Plate-shaped inorganic compound>
BT-1: OPTIGEL-WX (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-2: OPTIGEL-CG (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-3: OPTIGEL-CK (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-4: OPTIGEL-CK XR (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-5: OPTIGEL-CL (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-6: OPTIGEL-CMO (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-7: OPTIGEL-LX (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-8: OPTIGEL-W 724 (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-9: OPTIGEL-WA (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-10: OPTIGEL-WH (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-11: OPTIGEL-WM (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-12: OPTIGEL-WX XR (modified bentonite, manufactured by BYK Japan Co., Ltd.)
BT-13: Bengel (refined bentonite, manufactured by Hojun Co., Ltd.)
BT-14: Bengel HV (refined bentonite, manufactured by Hojun Co., Ltd.)
BT-15: Bengel FA (refined bentonite, manufactured by Hojun Co., Ltd.)
BT-16: Bengel W-100 (modified bentonite, manufactured by Hojun Co., Ltd.)
BT-17: Bengel W-100U (modified bentonite, manufactured by Hojun Co., Ltd.)
BT-18: Esben NX (refined bentonite, manufactured by Hojun Co., Ltd.)
BT-19: Kunipia-F (refined bentonite, manufactured by Kunimine Co., Ltd.)
BT-20: Kunipia-G (refined bentonite, manufactured by Kunimine Co., Ltd.)
BT-21: Moistnite-U (bentonite, manufactured by Kunipia Co., Ltd.)
ST-1: LAPONITE-RD (synthetic hectorite, manufactured by BYK Japan Co., Ltd.)
ST-2: LAPONITE-EP (synthetic hectorite, manufactured by BYK Japan Co., Ltd.)
ST-3: LAPONITE-RDS (synthetic hectorite, manufactured by BYK Japan Co., Ltd.)
ST-4: LAPONITE-JS (synthetic hectorite, manufactured by BYK Japan Co., Ltd.)
ST-5: LAPONITE-S482 (synthetic hectorite, manufactured by BYK Japan Co., Ltd.)
ST-6: Sumecton-SA (synthetic saponite, manufactured by Kunimine Co., Ltd.)
ST-7: Sumecton-ST (synthetic stevensite, manufactured by Kunimine Co., Ltd.)
ST-8: Sumecton-SWN (synthetic hectorite, manufactured by Kunimine Co., Ltd.)
ST-9: Sumecton-SWF (synthetic hectorite, manufactured by Kunimine Co., Ltd.)

<Polysaccharides>
GM-1: Kelcocrete 200 (Duitan gum, manufactured by Sansho Co., Ltd.)
GM-2: Kelzan (xanthan gum, manufactured by Sansho Co., Ltd.)
GM-3: MEYPRO-GAT (guar gum, manufactured by Sansho Co., Ltd.)
GM-4: K1A96 (Welan Gum, manufactured by Sansho Co., Ltd.)
GM-5: Maprodin 200 (locust bean gum, manufactured by Sansho Co., Ltd.)
GM-6: GENU pectin type BETA (pectin, manufactured by Sansho Co., Ltd.)
GM-7: Leozan (succinoglycan, manufactured by Sansho Co., Ltd.)

<Main solvent>
W-1: Ion-exchanged water

<Organic Solvent>
SOL-1: Diethylene glycol SOL-2: Ethylene glycol SOL-3: Glycerin SOL-4: 3-methyl-3-methoxy-1-butanol SOL-5: Diethylene glycol monomethyl ether SOL-6: Propylene glycol

<Wax emulsion>
WEM-1: RK-185 (paraffin wax, manufactured by GOO Chemical Industry Co., Ltd.)
WEM-2: WE-65 (paraffin wax, manufactured by Konishi Co., Ltd.)
WEM-3: Chemipearl W900 (polyethylene wax, manufactured by Mitsui Chemicals, Inc.)
WEM-4: Chemipearl A100 (ethylene-α-olefin copolymer, manufactured by Mitsui Chemicals, Inc.)
WEM-5: Chemipearl V100 (ethylene vinyl acetate copolymer resin, manufactured by Mitsui Chemicals, Inc.)

<Antifungal agent>
AM-1: Proxel GXL (S) (mold inhibitor, manufactured by Lonza Japan Co., Ltd.)
AM-2: Proxel GXL (mold inhibitor, manufactured by Lonza Japan Co., Ltd.)
AM-3: Sanaiback Sodium Omadin (mold inhibitor, manufactured by Sanai Oil Co., Ltd.)

<Rust inhibitor>
RI-1: Benzotriazole (rust inhibitor, manufactured by E-CHEM ENTERPRISE CORPORATION)

<pH Adjuster>
PC-1: NaOH
PC-2: Triethanolamine PC-3: Diethanolamine PC-4: Aminomethylpropanol

The ink compositions of the Examples , Comparative Examples, and Reference Examples were prepared as follows.
<Examples 1 to 281, Reference Examples 1 to 5 >
The entire amount of the amino acid anionic surfactant consisting of unsaturated fatty acid, the entire amount of the amino acid anionic surfactant consisting of saturated fatty acid, the entire amount of ion-exchanged water as the main solvent, and the entire amount of the organic solvent were stirred in a homomixer for 1 hour to prepare an aqueous solution of the amino acid anionic surfactant, and then the entire amount of the pigment was added and stirred in a homomixer for 1 hour. Thereafter, the entire amount of the remaining ingredients was added and stirred in a homomixer for 1 hour to obtain an ink composition.

<Comparative Examples 1 to 4 and 51>
The entire amount of ion-exchanged water as the main solvent, the entire amount of the organic solvent, and the entire amount of the pigment were added and stirred for 1 hour using a homomixer, and then the entire amount of the remaining ingredients was added and stirred for 1 hour using a homomixer to obtain an ink composition.

<Comparative Examples 5 to 14>
The entire amount of the phosphate ester-based anionic surfactant, the entire amount of ion-exchanged water as the main solvent, and the entire amount of the organic solvent were stirred in a homomixer for 1 hour to prepare an aqueous solution of the phosphate ester-based anionic surfactant, and then the entire amount of the pigment was added and stirred in a homomixer for 1 hour. Thereafter, the entire amount of the remaining ingredients was added and stirred in a homomixer for 1 hour to obtain an ink composition.

<Comparative Examples 15 to 38>
The entire amount of the amino acid anionic surfactant consisting of saturated fatty acid, the entire amount of ion-exchanged water as the main solvent, and the entire amount of the organic solvent were stirred in a homomixer for 1 hour to prepare an aqueous solution of the amino acid anionic surfactant, and then the entire amount of the pigment was added and stirred in a homomixer for 1 hour. Thereafter, the entire amount of the remaining ingredients was added and stirred in a homomixer for 1 hour to obtain an ink composition.

<Comparative Examples 39 to 50, 52 to 54>
The entire amount of the amino acid anionic surfactant consisting of unsaturated fatty acid, the entire amount of ion-exchanged water as the main solvent, and the entire amount of the organic solvent were stirred in a homomixer for 1 hour to prepare an aqueous solution of the amino acid anionic surfactant, and then the entire amount of the pigment was added and stirred in a homomixer for 1 hour. Thereafter, the entire amount of the remaining ingredients was added and stirred in a homomixer for 1 hour to obtain an ink composition.

(Content of each amino acid anionic surfactant)
The table of examples shows the content of the amino acid anionic surfactant consisting of an unsaturated fatty acid relative to the total content of amino acid anionic surfactants in the ink composition (represented as "UFAA (%)" in the table of examples, in units of "weight %)), and the content of the amino acid anionic surfactant consisting of a saturated fatty acid relative to the total content of amino acid anionic surfactants in the ink composition (represented as "SFAA (%)" in the table of examples, in units of "weight %)).

Ink backflow prevention composition 1
Lucant HC100 (ethylene alpha olefin, base material, manufactured by Mitsui Petrochemical Industries, Ltd.)
94.5% by weight
Aerosil R974 (fine particle silica, gelling agent, manufactured by Nippon Aerosil Co., Ltd.)
4.0% by weight
Leopearl KL (dextrin fatty acid ester, manufactured by Chiba Flour Milling Co., Ltd.)
1.5% by weight
The above components were mixed and stirred with a hot stirrer at 150° C. for 2 hours to obtain an ink backflow prevention composition 1. The viscosity of this ink backflow prevention composition 1 at 25° C. was 40,000 mPa·S.

(Creation of Test Writing Instrument 1)
In order to evaluate the ink compositions according to the Examples and Comparative Examples, a test brush pen type applicator with a rear end knock type valve mechanism as shown in Figure 1 was created. This was then filled with 2.0 g of the aqueous pigment ink composition for writing instruments of Examples 1 to 278 , Comparative Examples 1 to 51, and Reference Examples 1 to 5 , to prepare test writing instrument 1. (In the table, this is indicated as "Writing Instrument 1" and the corresponding combination is indicated with "O" in the column.)

(Creation of Test Writing Instrument 2)
In order to evaluate the ink compositions according to the Examples and Comparative Examples, a commercially available paint marker (MMP20-A (manufactured by Pentel Co., Ltd.) was used without the ink, and 2.0 g of the aqueous pigment ink composition for writing instruments of Example 279 and Comparative Example 52 was filled into the marker to prepare a test writing instrument 2. (In the table, this is indicated as "Writing Instrument 2" and the corresponding combination is indicated with "◯" in the column.)

(Creation of Test Writing Instrument 3)
In order to evaluate the ink compositions according to the Examples and Comparative Examples, a commercially available correction fluid applicator (XEZL61-W, manufactured by Pentel Co., Ltd.) was used without the correction fluid, and 2.0 g of the aqueous pigment ink composition for writing instruments prepared in Example 280 and Comparative Example 53 was directly filled into it to prepare a test writing instrument 3. (In the table, this is indicated as "Writing Instrument 3" and the corresponding combination is indicated with "◯" in the column.)

(Creation of Test Writing Instrument 4)
In order to evaluate the ink compositions according to the Examples and Comparative Examples, a commercially available water-based ballpoint pen (K110-DX, manufactured by Pentel Co., Ltd.) was used for testing, with the ink and ink backflow prevention composition removed, and 0.8 g of the water-based pigment ink composition for writing instruments of Example 281 and Comparative Example 54 and 0.1 g of the ink backflow prevention composition 1 were directly filled in the pen. This was used as test writing instrument 4. (In the table, this is indicated as "Writing Instrument 4" and the corresponding combination is indicated with "◯" in the column.)

(Low temperature written test 1 after low temperature storage)
The capped test sample was left lying on its side in an environmental testing room at room temperature of -5°C for three months. While still in the -5°C environment, the cap was removed from the test sample, and the character "長" (long) measuring 2 cm x 2 cm was written on a test paper specified in 7.3 of JIS S 6061. It was confirmed that the ink was ejected and a good handwriting was formed.
○: Can be written well.
×: Cannot be written.

(Low temperature written test 2 after low temperature storage)
The capped test sample was left to stand horizontally for 4 months in an environmental testing room at room temperature of -5°C. While still in the -5°C environment, the cap was removed from the test sample, and the character "長" (long) measuring 2 cm x 2 cm was written on a test paper specified in 7.3 of JIS S 6061. It was confirmed that the ink was ejected and a good handwriting was formed.
○: Can be written well.
×: Cannot be written.

(Low temperature written test 3 after low temperature storage)
The capped test sample was left to stand horizontally for 5 months in an environmental testing room at room temperature of -5°C. While still in the -5°C environment, the cap was removed from the test sample, and the character "長" (long) measuring 2 cm x 2 cm was written on a test paper specified in 7.3 of JIS S 6061. It was confirmed that the ink was ejected and a good handwriting was formed.
○: Can be written well.
×: Cannot be written.

(Low temperature written test 4 after low temperature storage)
The capped test sample was left to stand horizontally for six months in an environmental testing room at room temperature of -5°C. While still in the -5°C environment, the cap was removed from the test sample, and the character "長" (long) measuring 2 cm x 2 cm was written on a test paper specified in 7.3 of JIS S 6061. It was confirmed that the ink was ejected and a good handwriting was formed.
○: Can be written well.
×: Cannot be written.

(Measurement of physical properties)
The following physical properties were measured for Examples 1 to 281 , Comparative Examples 1 to 54 , and Reference Examples 1 to 5 obtained as described above. The measured physical properties and the measuring methods are as follows. The measurement results of each physical property are shown in Tables 1 to 35 below.

<pH>
The pH (indicated as pH in the table) of the ink composition of each of the Examples and Comparative Examples was measured. The pH was measured at a temperature of 25° C. using a "pH METER D-52" manufactured by HORIBA. The pH of the ink composition is preferably 6.0 to 10.0, and more preferably 7.0 to 9.0. If the pH of the aqueous pigment ink composition for writing instruments is within the above numerical range, it becomes easy to form a bond between the amino acid anionic surfactant consisting of an unsaturated fatty acid and the amino acid anionic surfactant consisting of a saturated fatty acid and the pigment surface, and it can be expected that the fluidity of the aqueous pigment ink composition for writing instruments will be maintained for a long period of time.
<Viscosity>
The viscosity of each of the Examples and Comparative Examples was measured at a temperature of 25°C and a shear rate of 16.0/s (represented as viscosity@16.0 in the table). The units of the measurement results shown in the table are [mPa·s]. The viscosity was measured using an Anton Paar "MCR-302" under the measurement conditions of a temperature of 25°C and a 50 mm cone plate (1°).

The aqueous pigment ink compositions for writing instruments of Examples 1 to 281 flowed, the ink was discharged sufficiently, and the writing marks were well formed even when left to stand for more than three months in an environmental testing room at room temperature of -5°C.

In contrast, in Comparative Examples 1 to 54, an amino acid anionic surfactant made of unsaturated fatty acid and an amino acid anionic surfactant made of saturated fatty acid were not used in combination, and therefore the ink composition did not flow and writing was impossible when left for more than three months in an environmental test room at room temperature of -5°C. In addition, even when only an amino acid anionic surfactant made of saturated fatty acid was added as in Comparative Examples 15 to 38, the ink composition did not flow and writing was impossible when left for more than three months in an environmental test room at room temperature of -5°C. In addition, even when multiple amino acid anionic surfactants made of saturated fatty acid were added in combination as in Comparative Examples 37 to 38, the ink composition did not flow and writing was impossible when left for more than three months in an environmental test room at room temperature of -5°C. In addition, even when only an amino acid anionic surfactant made of unsaturated fatty acid was added as in Comparative Examples 39 to 50 and 52 to 54, the ink composition did not flow and writing was impossible when left for more than three months in an environmental test room at room temperature of -5°C.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes variations on the above-described embodiments and appropriate combinations of these embodiments.

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.
In addition, in this specification, the expressions "comprise,""include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements.

Reference Signs List 1: barrel 1a; front barrel 1b; rear barrel 2: application point 3: operation part 4: cap 4a; anti-rolling rib 5: vertical rib 6: groove 7: valve seat member 7a; central hole 8: valve rod 9: coil spring 10: rear hole part 11: connecting rod 12: packing member 12a: hinge part 13: application point connection tube 14: volume adjustment body

Claims (1)

The aqueous pigment ink composition for a writing instrument comprises at least a pigment, an amino acid anionic surfactant composed of an unsaturated fatty acid, an amino acid anionic surfactant composed of a saturated fatty acid, a resin emulsion, a plate-like inorganic compound, and water , and the content of each of the amino acid anionic surfactant composed of an unsaturated fatty acid and the amino acid anionic surfactant composed of a saturated fatty acid is 10% by weight or more relative to the total amino acid anionic surfactant content of the ink composition.

Images