Water-based pigment ink composition for writing instruments

Abstract

To provide a water-based pigment ink composition for writing instruments that can form good writing marks even after let stand in a subzero temperature environment at about -5°C for 3 months or longer.SOLUTION: A water-based pigment ink composition for writing instruments has a pigment, an amino acid anionic surfactant composed of an unsaturated fatty acid, an amino acid anionic surfactant composed of a saturated fatty acid, and water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an aqueous pigment ink composition for writing instruments that uses a pigment as a coloring component in order to obtain a hiding effect on a base, a brilliance effect on a coating mark, water resistance of a coating mark, etc., and is used by being incorporated in a coating tool.

Background Art

[0002] Conventionally, an aqueous pigment ink composition for writing instruments that uses a pigment as a coloring component in order to obtain a hiding effect on a base, a brilliance effect on a coating mark, water resistance of a coating mark, etc. has a larger specific gravity than a dye and is dispersed and mixed rather than dissolved. Therefore, over time, the pigment gradually aggregates and precipitates, forming a so-called hard cake and separating from the liquid component, making it difficult to be discharged from the application site of the writing instrument. In such an ink composition using a pigment, as a means of delaying the aggregation and sedimentation of the pigment, methods such as surface modification of the pigment with various surfactants and reducing the fluidity of the liquid by using a thickener or a gelling agent are known. For example, in the invention described in Patent Document 1, a water-soluble resin such as an acrylic resin, a vinyl-based resin, various resin emulsions, a water-soluble polysaccharide such as a cellulose derivative, and an inorganic thickener such as a montmorillonite-based clay mineral are used to obtain an ink having a specific viscosity with respect to a specific shear rate. Thus, an aqueous ink composition for writing instruments with good redispersibility even when left standing at 40°C for 2 weeks is obtained. Also, in Patent Document 2, a water-based pigment ink composition for a ballpoint pen is disclosed, in which a plurality of specific water-soluble polysaccharides are used in combination, and the dispersion system of the ink is kept stable and good writing can be formed even after storage at a low temperature of about 0°C or a high temperature of about 60°C for about two months as well as at room temperature.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the invention described in the above patent document, there was a problem that it became impossible to write well in an environment of a minus temperature of less than -5°C for a super-long period of three months or more over time.

[0005] An object of the present invention is to provide an aqueous pigment ink composition for writing instruments that can form a good coating trace even when left standing in a minus temperature environment of about -5°C for three months or more.

MEANS FOR SOLVING THE PROBLEMS

[0006] A first gist of the present invention is an aqueous pigment ink composition for writing instruments comprising 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, and water. Further, a second gist of the present invention is an aqueous pigment ink composition for writing instruments containing a resin emulsion and a plate-like inorganic compound.

EFFECTS OF THE INVENTION

[0007] According to an embodiment of the present invention, an aqueous pigment ink composition for writing instruments that can write well can be provided even when filled in writing instruments such as marking pens, fountain pens, ballpoint pens, correction fluid applicators, etc., stored in a minus environment for a long time, and then used for writing in the same low-temperature environment.

[0008] That is, in the aqueous pigment ink composition for writing instruments of the present invention, an amino acid anionic surfactant composed of an unsaturated fatty acid and an amino acid anionic surfactant composed of a saturated fatty acid are bonded to the surface of the pigment, and the pigment surface is covered with an amino acid anionic surfactant composed of an unsaturated fatty acid and an amino acid anionic surfactant composed of a saturated fatty acid to form a composite. It is presumed that the interaction between the pigments is made sterically gentle and the fluidity of the whole composition is not impaired even in a low-temperature environment. Further, when a resin emulsion or plate-like inorganic particles are added thereto, a gentle gel structure that wraps the pigment is formed by the thickening effect due to the incorporation of solids and the gelling action of plate-like inorganic particles such as bentonite. In particular, a large gel structure composite is formed by the interaction between the amino acid anionic surfactant composed of an unsaturated fatty acid, the amino acid anionic surfactant composed of a saturated fatty acid, and the gel structure formed by the plate-like inorganic particles, and a situation where large plate-like pigments such as shiny plate-like aluminum or aluminum flakes as pigment particles are aligned and aggregated is also suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Embodiments for Carrying Out the Invention

[0010] The pigment used in the aqueous pigment ink composition for writing instruments of the present invention is used as a coloring component for obtaining the hiding effect of the base, the gloss effect of the coating mark, the water resistance of the coating mark, and the like. The pigments that can be used can be used without particular limitation, and include organic pigments such as azo pigments, nitroso pigments, and nitro pigments used in conventional aqueous inks and oil-based inks, and inorganic pigments such as loess, barium yellow, ultramarine blue, cadmium red, barium sulfate, titanium oxide, valve handle, iron black, and carbon black, and metal powders such as aluminum powder and bronze powder, and shiny pigments such as metal-coated glass flakes and metal-vapor-deposited films, and aqueous pigment bases in which pigments are dispersed in an aqueous medium. In particular, shiny pigments and the like are mentioned in order to form a shiny and beautiful handwriting.

[0011] As the brilliant pigment, 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, 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 (manufactured by Oike Imaging Co., Ltd.), Diamond Piece LG Gold No.55, Diamond Piece DG Gold No.55, Diamond Piece Green No.55, Diamond Piece Blue No.55, Diamond Piece Red No.55, Diamond Piece Maroon No.55, 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 PiecePink CO-40UC, Diamond Piece Lavender CO-40UC (both manufactured by Daiya Kogyo Co., Ltd.), Super Fine No. 22000, No. 22000WN, No. 1800WN, No. 18000, Fine No. 900, No. 800 (all manufactured by Yamato Metal Powder Industry Co., Ltd.), AA12, AA8, No. 900, No. 1800, Pale Gold E5, No. 2L5, Rich Gold L7, No. 3L7, E Copper (all manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.), Aluminum Powder 1000, No. 2700 (both manufactured by Nakatsuka Metal Foil & Powder Industry 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 D851YE (all manufactured by Toyo Aluminum Co., Ltd.), Stainless Steel Powder Pigment, Tin Powder Pigment, Zinc Powder Pigment, Nickel Powder Pigment, Gold Powder Pigment, Silver Powder Pigment, Meta Shine MT1030GP, Meta Shine MT2080GP, Meta Shine 2025PS, Meta Shine 1030PS, Meta Shine 2080PS, Meta Shine 5090PS, Meta Shine 5150PS, Meta Shine 5230PS, Meta Shine 5480PS (all manufactured by Nippon Sheet Glass Co., Ltd.), etc. When using bright pigments or the like, in order to form a bright and beautiful handwriting, the average particle size is preferably 10 μm or more, and when the average particle size is 30 μm or more, the brightness is further enhanced, which is particularly preferable.

[0012] Examples of 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. I.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), Anthraquinone 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), Rhodamine 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), Parachloroorthoaniline Red (C.I.12090), Rhodamine Fast Scarlet, Brilliant Fast Scarlet (C.I.12315), Brilliant Carmine BS, Permanent Red F2R (C.I.12310), 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 Rubine 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), Resorcin Red (C.I. 15630), Lake Red C (C.I. 15585), Lake Red D (C.I. 15500), Anthocyanin B (C.I. 18030), Brilliant Scarlet G (C.I. 15800), Resorcin Rubine 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, Monolite 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. 44045), 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.

[0013] As water-based pigments, there are 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 (all of the above are manufactured by Fuji Pigment 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, Sandye Super Black K, Sandye Super Black C, Sandye Super Grey B, Sandye Super Brown SB, Sandye Super Brown FRL, Sandye Super Brown RR, Sandye Super Green L5G, Sandye Super GreenGXB, Sandye Super Navy Blue HRL, Sandye Super Navy Blue GLL, Sandye Super Navy Blue HB, Sandye Super Navy Blue FBLH, Sandye Super Navy Blue FBL-160, Sandye 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, Sandye Super Rubine FR, Sandye super Carmine 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, Sandye Yellow IRC, Sandye Yellow FGN, Sandye Yellow GN, Sandye Yellow GRS, Sandye Yellow GSR-130, Sandye Yellow GSN-130, Sandye Yellow GSN, Sandye Yellow 10GN (all of the above are manufactured by Sanyo Shikiso 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 8315, Rio Fast Red S Fx 8316, Rio Fast Blue Fx 8170, Rio Fast Blue FX 8170, Rio Fast Blue S Fx 8312, Rio Fast Green S Fx8314 (manufactured by Toyo Ink Co., Ltd. as above), NKW-2101, NKW-2102, NKW-2103, NKW-2104, NKW-2105, NKW-2106, NKW-2107, NKW-2108, NKW-2117, NKW-2127, NKW-2137, NKW-2167, NKW-2101P, NKW-2102P, NKW-2103P, NKW-2104P, NKW-2105P, NKW-2106P, NKW-2107P, NKW-2108P, NKW-2117P, NKW-2127P, NKW-2137P, NKW-2167P, NKW-3002, NKW-3003, NKW-3004, NKW-3005, NKW-3007, NKW-3077, NKW-3008, NKW-3402, NKW-3404, NKW-3405, NKW-3407, NKW-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 (manufactured by Nippon Fluorescent Co., Ltd. as above), Cosmo Color S1000F series (manufactured by Toyo Soda Manufacturing Co., Ltd.), Victoria Yellow G-11, the same G-20, Victoria Orange G-16, the same G-21, Victoria Red G-19, the same G-22, Victoria Pink G-17, the same G-23, Victoria Green G-18, the same G-24, Victoria Blue G-15, the same G-25 (manufactured by Mikuni Shikiso Co., Ltd. as above), Pollux PC5T1020, Pollux Black PC8T135, Pollux series such as Pollux Red IT1030 (manufactured by Sumika Color Co., Ltd. as above), etc. are mentioned.

[0014] These pigments may be used alone or in a mixture of two or more. The pigment 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. Further, 1.0% by weight or more and 10.0% by weight or less is more preferable. Within the above numerical range, stable ink ejection performance can be obtained without clogging of the pigment at the pen tip or nozzle tip while maintaining fluidity at low temperatures.

[0015] The amino acid anionic surfactant composed of an unsaturated fatty acid used in the present invention and the amino acid anionic surfactant composed of a saturated fatty acid are used in combination. The amino acid anionic surfactant is preferably used in an amount of 0.1% by weight or more and 5.0% by weight or less based on the total amount of the aqueous pigment ink composition. Within the above numerical range, stable ink ejection properties can be obtained while maintaining the dispersion stability at low temperatures.

[0016] Examples of the amino acid anionic surfactant composed of an unsaturated fatty acid include NIKKOL Sarcosinate OH (oleoyl sarcosine (condensate of oleic acid and methyl glycine)), NIKKOL Sarcosinate OHV (oleoyl sarcosine (condensate of oleic acid and methyl glycine)) (both manufactured by Nikko Chemicals Co., Ltd.), etc. The unsaturated fatty acid is a fatty acid having a carbon-carbon double bond, and it is preferable that the cis-type carbon-carbon double bond is more than the trans-type carbon-carbon double bond in the carbon-carbon double bond because better fluidity is exhibited.

[0017] Examples of amino acid anion surfactants composed of saturated fatty acids include Amisoft CS-11 (sodium N-coconut oil fatty acid acyl-L-glutamate), Amisoft CA (N-coconut oil fatty acid acyl-L-glutamate), Amisoft LA-D (N-lauroyl-L-glutamic acid), Amisoft HA-P (N-stearoyl-L-glutamic acid), Amisoft LS-11 (sodium N-lauroyl-L-glutamate), Amisoft MK-11 (potassium N-myristoyl-L-glutamate), Amisoft MS-11 (sodium N-myristoyl-L-glutamate), Amisoft GS-11P (sodium N-acyl-L-glutamate), Amisoft HS-11P (sodium N-stearoyl-L-glutamate), Amisoft CT-12 (aqueous solution of triethanolamine salt of N-coconut oil fatty acid acyl-L-glutamate), Amisoft LT-12 (aqueous solution of triethanolamine salt of lauroyl-L-glutamic acid), Amisoft CK-22 (aqueous solution of potassium salt of N-coconut oil fatty acid acyl-L-glutamate), Amisoft CS-22 (aqueous solution of sodium salt of N-coconut oil fatty acid acyl-L-glutamate) (all of the above are manufactured by Ajinomoto Health Supply Co., Ltd.), NIKKOL Alaninate LN-30 (30% aqueous solution of sodium lauroylmethylalanine), NIKKOL Sarcosinate CN-30 (30% aqueous solution of sodium cocoyl sarcosinate (sodium salt of condensate of coconut oil fatty acid and methylglycine)), NIKKOL Sarcosinate CT-30 (30% aqueous solution of triethanolamine salt of cocoyl sarcosine (condensate of coconut oil fatty acid and methylglycine)), NIKKOL 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), NIKKOL Sarcosinate PN (sodium palmitoyl sarcosine) (all of the above are manufactured by Nikko Chemicals Co., Ltd.), and the like.An amino acid anionic surfactant in which the amino acid moiety is glutamic acid is preferable because it has two carboxylic acids and thus the binding to the pigment is stable. Incidentally, the amino acid anionic surfactant composed of coconut oil fatty acids contains not only the amino acid anionic surfactant composed of saturated fatty acids but also an amino acid anionic surfactant composed of unsaturated fatty acids in an amount of about several weight % as an impurity. However, when these are used alone with the content of the amino acid anionic surfactant composed of unsaturated fatty acids being less than about 10% by weight, the substantial combined effect is not exhibited. It is substantially necessary that the content of each of the amino acid anionic surfactant composed of unsaturated fatty acids and the amino acid anionic surfactant composed of saturated fatty acids is 10% by weight or more based on the content of the total amino acid anionic surfactant in the ink composition. When the content of the amino acid anionic surfactant composed of unsaturated fatty acids is 20% by weight or more based on the content of the total amino acid anionic surfactant in the ink composition and the content of the amino acid anionic surfactant composed of saturated fatty acids is 20% by weight or more based on the content of the total amino acid anionic surfactant in the ink composition, the interaction between the pigments is made sterically mild so that the fluidity of the whole composition is not impaired even in a low-temperature environment, and the effect of being able to write well is enhanced, which is preferable. Furthermore, when the content of the amino acid anionic surfactant composed of unsaturated fatty acids is 30% by weight or more based on the content of the total amino acid anionic surfactant in the ink composition and the content of the amino acid anionic surfactant composed of saturated fatty acids is 30% by weight or more based on the content of the total amino acid anionic surfactant in the ink composition, the interaction between the pigments is made sterically mild so that the fluidity of the whole composition is not impaired even in a low-temperature environment, and the effect of being able to write well is further enhanced, which is particularly preferable.

[0018] As the plate-like inorganic compound of the present invention, smectite group, bentonite, etc. that can be dispersed in water to form a gel structure can be used. Bentonite is an inorganic mineral mainly composed of montmorillonite, accompanied by secondary components such as quartz, cristobalite, feldspar minerals, and carbonate minerals. Due to the gelling action of plate-like inorganic particles such as bentonite, a gentle gel structure that wraps the pigment is formed. In particular, a large gel structure complex is formed by the interaction between an amino acid activator composed of an unsaturated fatty acid, an amino acid activator composed of a saturated fatty acid, and the gel structure formed by the plate-like inorganic particles, suppressing a situation where large plate-like pigments such as shiny plate-like aluminum or aluminum flakes as pigment particles align and aggregate, and it is used to enable the stable ejection of the pigment 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, OPTIGEL-WX XR, LAPONITE-RD, LAPONITE-EP, LAPONITE-RDS, LAPONITE-JS, LAPONITE-S482 (all of the above are manufactured by BYK-Chemie Japan Co., Ltd.), Benger, Benger HV, Benger FW, Benger 15, Benger 23, Benger SH, Benger A, Benger W-100, Benger W-100U, Benger W-200U, Benger W-300U, Benger W-300HP, Esven NX, Esven NX80, Esven NZ, Esven NZ, 70 Esven NEZ, Esven NO12S, Esven NO12 (all of the above are manufactured by Hoejun Co., Ltd.), Kunipia-F, Kunipia-G, Kunipia-G4, Moistnite-U, Moistnite-S, Smeton-SA, Smeton-ST, Smeton-SWN, Smeton-SWF, Smeton-SEN (all of the above are manufactured by Kunimine Co., Ltd.), etc. 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, stable ink ejection properties can be obtained without clogging of the pigment at the pen tip or nozzle tip while maintaining the dispersion stability at low temperatures. If it is more than 3.0% by weight, the viscosity of the ink extremely increases and the writing quality is likely to deteriorate.

[0019] The resin emulsion of the present invention imparts flexibility to a composite of an amino acid activator composed of an unsaturated fatty acid and an amino acid activator composed of a saturated fatty acid, which covers the pigment surface by binding the hydrophobic part to an amino acid anionic surfactant, and imparts fluidity even in a super-low temperature state with few diffusion phenomena. Examples of the resin emulsion include urethane resin emulsion, acrylic resin emulsion, acrylic-urethane resin emulsion, vinyl acetate resin emulsion, and the like. Specifically, Eucote UWS-145 (solid content 35%), Eucote UX-300 (solid content 38%), Eucote UX-310 (solid content 40%), Permaline UA-150 (solid content 30%), Permaline UA-200 (solid content 30%), Permaline UA-368 (solid content 50%), Permaline UA-4000 (solid content 38%) (all manufactured by Sanyo Chemical Industries, Ltd.), Acrit WBR-016U (solid content 30%) (manufactured by Dainippon Fine Chemical Co., Ltd.), Neo Sticker 200 (solid content 35%), Neo Sticker 400 (solid content 37%), Neo Sticker 700 (solid content 37%), Neo Sticker 1200 (solid content 37%), Evafanol HA-15 (solid content 30%), 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 Nippon Kayaku Co., Ltd.), 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 (solid content 50%), Bonron S-416BF (solid content 44.5%), Bonron S-415 (solid content 44%), Bonron S-403 (solid content 25%), Bonron S-476 (solid content 45%), Bonron S-1120 (solid content 45%), Bonron S-483TBF (solid content 45%), Bonron S-434 (solid content 45%), Bonron S-1360 (solid content 44.5%) (all manufactured by Mitsui Chemicals, Inc.), DM772 (solid content 46%), DM774 (solid content 46%) (all manufactured by Japan Coating Resin Co., Ltd.), Acrit AKW-107 (solid content 30%), Acrit ATW-008S (solid content 29.5%) (all manufactured by Dainippon Fine Chemical Co., Ltd.), Joncryl 7100 (solid content 48.0%), Joncryl 711 (solid content 42.0%), Joncryl PDX-7370 (solids content 42.0%), Joncryl PDX-7323 (solids content 42.0%), Joncryl PDX-7611 (solids content 36.5%), Joncryl 352D (solids content 45.0%), Joncryl 538J (solids content 45.0%), Joncryl PDX-7700 (solids content 48.0%), Joncryl PDX-7177 (solids content 36.0%), Joncryl 7001 (solids content 87.0%) (above, manufactured by BASF (Germany)), Aquabrid 46777 (solids content 30%), Aquabrid UX-100 (solids content 48%), Aquabrid UX-110 (solids content 48%), Aquabrid AST531 (solids content 56%), Aquabrid AST499 (solids content 40%), Sevian-A886 (solids content 42%) (above, manufactured by Daicel Finechem Co., Ltd.), Boncoat 40-418EF (solids content 55%), Boncoat 5400EF (solids content 55%), Boncoat 5495EF (solids content 55%), Boncoat CG-8400 (solids content 50%), Boncoat CG-8490 (solids content 50%), Boncoat CG-8520 (solids content 49%), Boncoat CG-8680 (solids content 50%), Boncoat CM-8430 (solids content 40%), Boncoat CP-6450 (solids content 40%), Boncoat DV-961 (solids content 40%), Boncoat EC-740EF (solids content 40%), Boncoat EC-905EF (solids content 50%), Boncoat SFC-55 (solids content 40%) (above, manufactured by DIC Corporation), Acrit WEM-202U consisting of an acrylic-urethane resin emulsion (solids content 40%), Acrit WEM-321U (solids content 38%), Acrit WEM-3008 (solids content 32.5% or more (manufactured by Taisei Fine Chemical Co., Ltd.), Polyzol S-5J (solid content 52%) consisting of vinyl acetate resin emulsion, Polyzol AX-590 (solid content 49%), Polyzol AX-751 (solid content 46%), Polyzol AX-428J (solid content 46%), Polyzol AX-510ZL (solid content 43%), Polyzol AX-951 (solid content 41%), Polyzol AX-1000 (solid content 39%), Polyzol BX-8004 (solid content 48%), Polyzol AX-747L (solid content 50%), Polyzol P-503 (solid content 40%), Polyzol PS-120 (solid content 50%), Polyzol S-65 (solid content 50%) (manufactured by Showa Denko K.K. as above), Sevian-A210 (solid content 52%), Sevian-A215 (solid content 52.5%), Sevian-A217 (solid content 52.5%), Sevian-A218 (solid content 59%), Sevian-A220 (solid content 48%), Sevian-A240 (solid content 53.5%), Sevian-A415 (solid content 55%), Sevian-A435 (solid content 57%) (manufactured by Daicel Finechem Ltd. as above), etc. can be mentioned. 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 as a solid content based on the total amount of the aqueous pigment ink composition. Within the above numerical range, stable ink ejection performance can be obtained while maintaining fluidity at low temperatures.

[0020] 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, as long as it is an organic solvent that has been conventionally known for various purposes as an ink, such as preventing ink freezing at low temperatures and preventing ink drying at the pen tip, it is not particularly limited and can be used in combination. 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 benzyldiglycol; glycol ethers such as 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, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, propylene glycol monobutyl ether, propylene glycol monophenyl ether, tripropylene glycol monobutyl ether, and tripropylene glycol monophenyl ether; alcohol 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; and propylene glycol methyl ether acetate, propylene glycol diacetate, 2-pyrrolidone, N-methyl-2-pyrrolidone, sulfolane, γ-butyrolactone, and the like. These organic solvents may be used alone or in a mixture of two or more.

[0021] The pH of the ink composition can be adjusted by using basic substances such as sodium hydroxide, lithium hydroxide, triethanolamine, diethanolamine, monoethanolamine, aminomethylpropanediol, and pH adjusters such as conventionally known acidic substances. By adjusting the pH to 6.0 or higher and 10.0 or lower with these pH adjusters, the effect of maintaining the fluidity of the ink composition is further improved. Furthermore, by adjusting the pH to 7.0 or higher and 9.0 or lower, it becomes easier to form a bond between the pigment surface of the amino acid anionic surfactant composed of unsaturated fatty acid and the amino acid anionic surfactant composed of saturated fatty acid, and it is possible to expect the maintenance of the fluidity of the aqueous pigment ink composition for writing instruments in the long term. These pH adjusters may be used alone or in combination of two or more kinds.

[0022] In addition, various additives can be used as appropriate according to need. For example, in order to improve the fixing property of the pigment, a wax emulsion can be used. Specifically, RK-185 (solid content 45%) made of paraffin wax (manufactured by Gohou Chemical Industry Co., Ltd.), WE-65 (solid content 35%) (manufactured by Konishi Co., Ltd.), Chemparl W100 (solid content 40%) made of polyethylene wax, Chemparl W200 (solid content 40%), Chemparl W300 (solid content 40%), Chemparl W310 (solid content 40%), Chemparl W400 (solid content 40%), Chemparl W4005 (solid content 40%), Chemparl W401 (solid content 40%), Chemparl W410 (solid content 40%), Chemparl W500 (solid content 40%), Chemparl WF640 (solid content 40%), Chemparl W700 (solid content 40%), Chemparl W800 (solid content 40%), Chemparl W900 (solid content 40%), Chemparl W950 (solid content 40%) (all of the above are 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 of the above are manufactured by Toho Chemical Industry Co., Ltd.), HYTEC P-9018 (solid content 35%) made of polypropylene wax, HYTEC P-5300 (solid content 30%), HYTEC P-5800 (solid content 30%), HYTEC P-5060P (solid content 40%) (all of the above are manufactured by Toho Chemical Industry Co., Ltd.), Chemparl A100 (solid content 40%) made of ethylene-α olefin copolymer (manufactured by Mitsui Chemicals, Inc.), Chemparl V100 (solid content 40%), Chemparl V200 (solid content 40%), Chemparl V300 (solid content 40%) (all of the above are 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%), HYTEC S-3148K (solid content 25%) (all of the above are manufactured by Toho Chemical Industry Co., Ltd.), etc. can be mentioned. These wax emulsions may be used alone or in combination of two or more kinds. In addition, as an antiseptic and antifungal agent for the aqueous pigment ink composition, sodium dehydroacetate, 1,2-benzisothiazolin-3-one, sodium 2-pyridinethiol-1-oxide, etc. can also be used. These antiseptic and antifungal agents have a synergistic effect by combining 1,2-benzisothiazolin-3-one and sodium 2-pyridinethiol-1-oxide, and an antiseptic and antifungal effect can be obtained with a smaller content.

[0023] The viscosity of the aqueous pigment ink composition for writing instruments of the present invention is appropriately adjusted according to the embodiments of direct liquid markers, ballpoint pens, brushes, pen pens, correction fluids, etc., and is not particularly limited. By appropriately adjusting according to the embodiments, writing performance and storage stability such as writing feel, uniformity of handwriting, handwriting density, bleeding suppression, ink ejection stability, control of bleeding through the paper of handwriting, suppression of handwriting blur, suppression of drying at the pen tip and nib, writing performance during drying, and dispersion stability of pigments are ensured, which is preferable.

[0024] When manufacturing the aqueous pigment ink composition for writing instruments of the present invention, various conventionally known methods can be adopted. For example, after putting water or bentonite into stirrers such as Henschel mixers, propeller stirrers, homogenizers, turbo mixers, high-pressure homogenizers, fine flow mills, etc. having high shear force and stirring and dispersing, pigments and other remaining components dispersed by dispersers such as Henschel mixers, propeller stirrers, homogenizers, turbo mixers, high-pressure homogenizers, ball mills, bead mills, roll mills, etc. are added, and further mixing and stirring can easily obtain it. Also, in these preparation processes, the generated dispersion heat can be directly utilized for stirring, heating, or cooling and stirring. Removal of bubbles by a defoamer or filtration of coarse particles by a filter may be performed as necessary. These various mixing processes, dispersion processes, filtration processes, heating processes, or cooling processes may be performed alone, or two or more processes may be performed in parallel.

[0025] The aqueous pigment ink composition for writing instruments of the present invention can be suitably used when filled in writing instruments, but is not limited to writing instruments only, and may also be an applicator for cosmetics such as an eyeliner or an eyebrow pencil. Also, a method having a longitudinally-sectioned comb-shaped temporary ink reservoir member that directly stores ink without using an ink storage body such as a fiber converging body in the coating liquid storage chamber, or a method having a valve mechanism that automatically opens and closes according to changes in operation or internal pressure may be used. When the aqueous pigment ink composition to be used uses titanium oxide or a large-diameter plate-shaped lustrous pigment, it is preferable that the ink stored in the coating liquid storage chamber is directly stored without being occluded in a fiber converging body called batting or the like so as to use up the ink, and also, the ink supply mechanism to the application destination is more than one that passes through pores such as a fiber converging body or a longitudinally-sectioned comb-shaped temporary ink reservoir member. It is preferable to use a valve mechanism that can secure a relatively large ink passage, or a ballpoint pen or a tip valve mechanism that controls ink ejection with a valve formed at the pen tip. Furthermore, by using a brush-type application tip that can freely form a wide application mark as desired, a wide application mark exhibiting the luster of the ink can be formed.

[0026] Fig. 1 shows an example of the structure of a writing instrument. A so-called rear-end knock type valve mechanism pen-type applicator that uses a relatively soft one such as a pen tip as the application tip, arranges a valve mechanism at the connection portion between the application tip and the coating liquid storage chamber, and opens and closes the valve mechanism by a rear-end knock operation to control the supply of ink to the application tip. The tip of the shaft cylinder 1 is provided with an application tip 2, the rear end is provided with a push-type operation portion 3, and a cap 4 for protecting the application tip 2 can be fitted to the tip portion of the shaft cylinder 1. The cap 4 is provided with an anti-rolling rib 4a on the side wall to prevent the applicator from rolling when the cap 4 is attached. The shaft cylinder 1 has a front shaft 1a having an opening through which the application tip 2 protrudes and a rear shaft 1b to which the operation portion 3 is connected.

[0027] The front shaft 1a has a small diameter at the front part on the tip side of the pen tip that matches the diameter of the pen tip, and a large diameter at the rear side that serves as a connection part with the rear shaft 1b. Vertical ribs 5 that support the pen tip are evenly arranged circumferentially on the inner wall of the small diameter part. The groove 6 formed between these vertical ribs 5 also serves as a ventilation passage for taking in air of the volume of the ink composition discharged by writing application inside. Also, a valve seat member 7 for controlling the ink flow is arranged in the large diameter part at the rear in the front shaft 1a. At the center position of the valve seat member 7, a central hole 7a serving as an ink passage is provided, and the peripheral part thereof is a valve seat that can be circumferentially abutted against a valve stem described later. Also, the valve seat member 7 fixes a coil spring 9 that biases the valve stem 8 rearward and keeps it in close contact with the valve seat at all times when not in operation at the rear end.

[0028] The rear shaft 1b has a rear hole part 10 at the rear end part, and the operation part 3 is arranged. From the rear hole part 10, a connecting rod 11 that transmits the pushing operation of the operation part 3 to the valve stem 8 protrudes, and is liquid-tightly sealed with a packing member 12 made of a material having rubber elasticity and having a flexible hinge part 12a. When the operation part 3 is pushed into the direction inside the shaft cylinder, it abuts against the rear end of the packing member 12, and the packing member 12 receives the pushing force and the hinge part 12a deforms to transmit the pushing force to the connecting rod 11. As the connecting rod 11 advances, the valve stem 8 advances against the elastic force of the coil spring 9 and the valve mechanism is released, allowing the ink composition to flow. The coil spring 9 abuts against the tip surface of the connecting rod 11 that serves as the connection step part between the connecting rod 11 and the valve stem 8 to bias the connecting rod 11 and the valve stem 8 rearward. When the pressing operation is released, the connecting rod 11 and the valve stem 8 are moved rearward to close the valve mechanism.

[0029] A coating tip connection tube 13 is attached to the front end portion of the valve rod 8, and a pen tip-shaped coating tip 2 is connected to the front end of the coating tip connection tube 13. Therefore, the coating tip 2 also moves forward in conjunction with the pushing operation of the operation unit 3, and when the pushing operation is released, the coating tip 2 also moves backward by the elastic force of the coil spring 9. By doing so, an external force can be applied to the ink composition existing in the space around the coating tip 2 every time an operation is performed, suppressing drying and solidification, and also assisting in discharging the ink composition. Such a mechanism is particularly effective when using a liquid with a relatively large solid content.

[0030] The inside of the rear shaft 1b mainly serves as a coating liquid storage chamber, and a cylindrical polypropylene volume adjuster 14 for adjusting the volume of the coating liquid storage chamber as an internal member is arranged so as to surround the connecting rod 11 in a circumferential manner. The volume adjuster 14 may be fixed to the rear shaft 1b, but it is preferably in a non-fixed state that can move back and forth in relation to the operating connecting rod 11. Reducing the volume of the coating liquid storage chamber in this way suppresses the gas-like substances such as the air and the solvent of the ink composition stored inside from expanding due to changes in temperature and pressure, and the ink composition from being blown out by the expanded gas when the valve mechanism is opened. Also, by using a transparent or translucent material for the rear shaft, when using a fluorescent pigment or white titanium oxide as a colorant, at least a part of the gap can be narrowed to make it easier to visually recognize the color and remaining amount of the built-in ink composition. Also, by making the color of the volume adjuster 14 black, white, milky white, etc., it is possible to make it even easier to visually recognize the color of the ink composition.

[0031] When attempting to discharge the ink composition by pressing the rear shaft 1b, the rear shaft 1b can be made of a flexible material such as polyolefin resins such as low-density polyethylene, high-density polyethylene, and polypropylene, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide, polyacrylonitrile, polycarbonate, polyvinyl chloride, polystyrene, polyoxymethylene, and various elastomers.

[0032] The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and also includes forms obtained by modifying the above-described embodiments and forms obtained by appropriately combining these forms.

[0033] In this specification, expressions indicating that things such as "identical", "equal", and "homogeneous" are in an equal state represent not only a strictly equal state but also a state in which there are tolerances or differences to the extent that the same function can be obtained. Also, in this specification, the expressions "comprising", "including", or "having" for one component are not exclusive expressions excluding the existence of other components.

Explanation of Reference Numerals

[0034] 1 Shaft cylinder 1a Front shaft 1b Rear shaft 2 Coating destination 3 Operation part 4 Cap 4a Anti-rolling rib 5 Vertical rib 6 Groove 7 Valve seat member 7a Central hole 8 Valve stem 9 Coil spring 10 Rear hole part 11 Connecting rod 12 Packing member 12a Hinge part 13 Coating destination connecting pipe 14 Volume regulator

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, does not contain a dye, 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.

2. 2. The aqueous pigment ink composition for a writing instrument according to claim 1, wherein the pigment is a glittering pigment.

Images