JP2012017400A - Inkjet ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet ink composition controllable of bleeding even on a nonabsorbing surface of a medium to be recorded such as polyvinyl chloride.SOLUTION: This inkjet ink composition includes a shear thinning giving agent, a colorant and a solvent.

Description

  The present invention relates to a composition for an inkjet ink in which bleeding on a recording medium is suppressed.

  Conventional ink jet recording systems can be broadly classified into two systems, a continuous type and an on-demand type. The excellent features of these ink jet recording methods are that the direct recording is simple and the process is simple. In addition, since it is not an impact method, it is noiseless, easy to color, and high speed. For example, recording is possible, running paper is low because plain paper can be used, and high-resolution recording is possible because fine ink droplets are ejected. Also, the inkjet recording method, unlike the printing method, does not require a printing plate and can record various patterns with a single machine. For example, it can be used in a wide range of fields such as packing materials, posters, and car body wrapping. Is possible.

  On the other hand, the ink used in the ink jet recording method (hereinafter abbreviated as “inkjet ink” or “ink”) has a considerably lower viscosity than that of, for example, gravure ink, and ink droplets have landed. The ink tends to wet and spread on the recording medium from the time of drying to the time of drying, and the bleeding may increase and the contrast of recorded information such as printed matter may decrease. Therefore, development of ink-jet ink with suppressed bleeding is strongly desired.

  On the other hand, conventionally, by applying a reaction liquid that reacts with and solidifies the ink after landing on the landing surface of the recording medium, the ink is solidified to suppress bleeding (for example, , See Patent Document 1), in particular, a technique for preventing ink from penetrating into the paper surface and spreading the ink due to capillary action (see Patent Document 2). In the ink after landing on the recording medium, A technique (Patent Document 3) that suppresses ink bleeding by accelerating the increase in viscosity due to volatilization has been proposed. In addition, by using gel ink having a characteristic that the viscosity is reduced by the application of pressure and the viscosity is increased in a normal state where the application of the pressure is eliminated, the ink is ejected from the inkjet head without any trouble on the recording medium. There has been proposed a technique (Patent Document 4) that suppresses bleeding by increasing the viscosity of landed ink.

JP 2010-076395 A Japanese Patent Laying-Open No. 2005-036303 JP 2006-016412 A JP 2007-301876 A

However, in the techniques proposed in Patent Documents 1 to 3, for example, a non-absorbing surface such as polyvinyl chloride (PVC) cannot provide a sufficient bleeding suppression effect, and the recording medium that can be used is limited. There was a problem that it was.
Further, Patent Document 4 does not disclose the degree of the effect and the discharge conditions of the gel ink as well as the specific composition and physical properties. In addition, the physical property that the viscosity is high in a normal state and the viscosity is reduced by application of pressure is recognized to some extent even in a wide range of liquid compositions including conventional inks. Therefore, in patent document 4, nothing is disclosed about the gel ink by which the bleeding was suppressed.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an ink-jet ink composition capable of suppressing bleeding even on a non-absorbing surface such as polyvinyl chloride of a recording medium.

To solve the above problem,
The present invention provides an ink-jet ink composition comprising a shear thinning agent, a colorant and a solvent.
In the inkjet ink composition of the present invention, the viscosity immediately after applying a shear of 10,000 s ⁻¹ after standing at 25 ° C. for 5 minutes is 0.001 to 0.03 Pa · s, and is further allowed to stand for 5 seconds. The viscosity immediately after applying a shear of 0.01 s ⁻¹ at 25 ° C. is preferably 0.04 to 100 Pa · s.
In the inkjet ink composition of the present invention, the viscosity immediately after applying a shear of 10,000 s ⁻¹ after standing at 25 ° C. for 5 minutes is preferably 0.001 to 0.03 Pa · s.
In the inkjet ink composition of the present invention, the viscosity immediately after applying a shear of 0.01 s ⁻¹ after standing at 25 ° C. for 5 minutes is preferably 0.1 to 100 Pa · s.
In the ink-jet ink composition of the present invention, the shear thinning agent is a natural polysaccharide, wherein one or more hydrogen atoms constituting the hydroxyl group of the natural polysaccharide are an alkyl group, a hydroxyalkyl group, or a hydroxyalkyl group. A group having an ether bond in which one or more carbon atoms are substituted with an oxygen atom, a natural polysaccharide derivative substituted with a carboxyalkyl group, a carbamoyl group, an alkylcarbamoyl group or a phosphate group, a salt of the natural polysaccharide, It is preferably at least one selected from the group consisting of salts of natural polysaccharide derivatives, acrylic resins and mineral substances.
In the ink composition for inkjet according to the present invention, the shear thinning agent is one or more carbons in which one or more hydrogen atoms constituting hydroxyl groups of cellulose and cellulose are alkyl groups, hydroxyalkyl groups, or hydroxyalkyl groups. Selected from the group consisting of a group having an ether bond in which an atom is substituted with an oxygen atom, a cellulose derivative substituted with a carboxyalkyl group, a carbamoyl group, an alkylcarbamoyl group or a phosphate group, a salt of cellulose, and a salt of the cellulose derivative It is preferable that it is 1 or more types.

  According to the present invention, bleeding can be suppressed even on a non-absorbing surface of a recording medium such as polyvinyl chloride. As a result, for example, the contrast of recorded information is improved, and a clear and high-quality information recording medium can be obtained.

It is a graph which shows the measurement result of the viscosity immediately after giving the shear | shear of a predetermined magnitude | size after leaving still at 25 degreeC about the inkjet ink composition of Examples 1-5 and Comparative Examples 1-2.

The inkjet ink composition of the present invention (hereinafter sometimes abbreviated as “ink composition”) is characterized by containing a shear thinning agent, a colorant, and a solvent.
Such an ink composition exhibits shear thinning by containing the shear thinning agent. Here, “shear thinning” means that the viscosity is high in a stationary state, but the viscosity is lowered by applying external pressure such as vibration and shear. Therefore, when ejected from an inkjet head, the viscosity is low and good ejectability is exhibited, but after landing on the recording medium, the application of pressure is canceled by leaving it stationary, and the viscosity increases, so that bleeding occurs. It is suppressed.

(Shear thinning agent)
In the present invention, the shear thinning agent imparts shear thinning to the ink composition.
Examples of the shear thinning agent include polysaccharides, polysaccharide derivatives, polysaccharide salts, polysaccharide derivative salts, (meth) acrylic resins, and mineral substances. Here, “(meth) acrylic resin” refers to both acrylic resin and methacrylic resin.
The shear thinning agent is preferably water-soluble.

Examples of the polysaccharide derivative include those in which one or more hydrogen atoms of the polysaccharide are substituted with a substituent. Especially, what substituted one or more hydrogen atoms which comprise the hydroxyl group of the said polysaccharide by the substituent is preferable.
Preferred examples of the substituent include an alkyl group, a hydroxyalkyl group, a group having an ether bond in which one or more carbon atoms of the hydroxyalkyl group are substituted with an oxygen atom, a carboxyalkyl group, a carbamoyl group (-C (= Examples thereof include O) —NH ₂ ), alkylcarbamoyl groups, and phosphate groups (—P (═O) — (OH) ₂ ).
The alkyl group in the substituent may be linear, branched or cyclic, but is preferably linear or branched, and preferably has 1 to 10 carbon atoms.
Examples of the hydroxyalkyl group in the substituent include a monovalent group in which one hydrogen atom of the alkyl group is substituted with a hydroxyl group (—OH), and preferred examples include those found in hydroxypropylcellulose. those represented by "-CH ₂ -CH (CH ₃₎ -OH" can be used.
As the “group having an ether bond in which one or more carbon atoms of a hydroxyalkyl group are substituted with an oxygen atom” in the substituent, a general formula “(—CH ₂₎ found in hydroxypropyl cellulose is preferable. _{-CH (CH 3) -O) m} H ( wherein, m is an integer of 2 or more.) "represented by materials can be exemplified.
Examples of the carboxyalkyl group in the substituent include a monovalent group in which one hydrogen atom of the alkyl group is substituted with a carboxy group (—COOH).
Examples of the alkylcarbamoyl group in the substituent include monovalent groups in which one or two hydrogen atoms of the carbamoyl group are substituted with the alkyl group. When two hydrogen atoms are substituted with an alkyl group, the two alkyl groups may be the same as or different from each other.
When there are two or more substituents, these substituents may be the same as or different from each other. That is, all the substituents may be different from each other, some of the substituents may be the same, or all the substituents may be the same.
The substitution position of the substituent is not particularly limited.

Examples of the salt of the polysaccharide or a derivative thereof include, for example, a carboxy group (—COOH), a sulfonic acid group (—SO ₃ H), a hydroxyl group (—OH), a phosphorus in a molecule constituting the polysaccharide or a derivative thereof. Examples of one or more groups capable of dissociating hydrogen ions (H ⁺ ) such as an acid group (—P (═O) — (OH) ₂ ) in which the hydrogen ions are substituted with other cations can be given.
As the cation substituted with hydrogen ions, if derived from one atom, alkali metal ions such as lithium ion, sodium ion and potassium ion; alkaline earth metal ions such as magnesium ion and calcium ion; iron Examples thereof include transition metal ions such as ions, copper ions, silver ions, and zinc ions, and ammonium ions may be used as long as they are derived from molecules composed of a plurality of atoms.

The polysaccharide is preferably a natural polysaccharide, and more preferably cellulose. The polysaccharide preferably has a mass average molecular weight of 1 × 10 ⁴ to 1 × 10 ⁹ .

  The (meth) acrylic resin may be either a crosslinked type or a non-crosslinked type, and may be a known one such as poly (meth) acrylate or polymethyl methacrylate (PMA), but is preferably an acrylic resin. .

  The mineral-based material may be a known material such as aluminum magnesium silicate, organic hectorite, smectite, or silicic anhydride, and is not particularly limited.

  In addition, as the shear thinning agent, a surfactant such as 4-oxyethylene oleyl ether phosphoric acid or a salt thereof which exhibits shear thinning in a specific pH range can be used. Here, the surfactant preferably has a relatively high molecular weight, and examples thereof include those having a molecular weight of 250 or more, but are not limited thereto.

  Commercially available products may be used as the shear thinning agent, and specific examples include HPC-SL, HPC-L, HPC-M, HPC-H (above, Nippon Soda Co., Ltd.), Avicel PH. -101, Avicel PH-102, Avicel PH-301, Avicel PH-M06, TG-101 (above, manufactured by Asahi Kasei Co., Ltd.) and other celluloses and derivatives thereof; Kelzan, Kelzan S, Kelzan F, Kelzan AR, Kelzan M, Kelzan D (above, manufactured by Sanki Co., Ltd.), Kojin, Kojin F, Kojin T, Kojin K (above, manufactured by Kojin Co., Ltd.), Inager V-7, Inager 7T (above, manufactured by Ina Food Industry Co., Ltd.), etc. Xanthan gum; natural polymers with glucose, glucuronic acid, or rhamnose as the main chain, such as Arcacy Gum and Zeta Sea Gum (above, Hakuto Co., Ltd.) Saccharino glucan such as Leosan (manufactured by Sancho Co., Ltd.); Welan gum such as K1A96 (manufactured by Sancho Co., Ltd.); Ramsan gum such as K1A112, K7C2433 (manufactured by Sancho Co., Ltd.); Jaguar 8111, Jaguar 8600, Jaguar HP- 8. Guar gum and its derivatives such as Jaguar HP-60, Jaguar CP-13 (above, manufactured by Sancho Co., Ltd.) and other natural products such as carrageenan, dextran, sodium alginate, locust bean gum, pectin (above, manufactured by Sancho Co., Ltd.), etc. Saccharides; Acrylic water-soluble resins such as PVM / MA cross polymer, carboxyvinyl polymer (manufactured by Sansho Co., Ltd.), Pemulen TR-1 and Pemulen TR-2 (manufactured by BF Goodrich); Bee gum (silicic acid) Aluminum magnesium), Benton (existence) Hectorite (above, manufactured by Sansho Co., Ltd.), VANGEL-B, VANGEL-C, VANGEL-ES, VANGEL-O, VEGUM-T, VEEGUM-F, VEEGUM-HV, VEEGUM-HSK, VEEGUM-PRO, VEEGUM-PRO Examples thereof include mineral substances such as D, VEEGUM-ULTRA, and VEEGUM-PLUS (above, manufactured by RT Vanderbilt Co. LTD, USA).

  The shear thinning agent may be used alone or in combination of two or more. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.

  The content of the shear thinning agent in the ink composition is preferably 0.05 to 5% by mass, and more preferably 0.08 to 3.5% by mass.

  As the shear thinning agent, it is not necessary to limit the pH range at the time of use, the degree of freedom in selecting the colorant to be used is high, and there is less concern about the occurrence of corrosion of the members that come into contact with the discharge device or the like. The polysaccharide, the polysaccharide derivative, the salt of the polysaccharide, the salt of the polysaccharide derivative, a (meth) acrylic resin, and a mineral substance are preferably used.

(Coloring agent)
In the present invention, the colorant can be appropriately selected depending on the use of the composition of the present invention.
For example, when applied to an aqueous inkjet ink, a known dye or pigment used in a conventional aqueous ink composition can be used as the colorant.

Examples of the dye used in the water-based ink composition include direct dyes, acid dyes, and basic dyes.
More specifically, Japanol Fast Black D Conch (CI Direct Black 17), Water Black 100L (CI Direct Black 19), Water Black L-200 (CI Direct Black 19), Direct Fast Black B (CI Direct Black 22), Direct Fast Black AB (CI Direct Black 32), Direct Deep Black EX (CI Direct Black 38), Direct Fast Black Conc (CI Direct Black 51), Cayalas Spragley VGN (CI Direct Black 71), Cayalas Direct Brilliant Yellow G (CI Direct Yellow 4), Direct Fast Yellow 5GL (CI Direct Yellow) 6), Eisen Primula Yellow GCLH (CI Direct Yellow 44), Direct Fast Yellow R (CI Direct Yellow 50), Eisen Direct Fast Red FH (CI Direct Red 1), Nippon Fast Scarlet GSX (CI Direct Red 4), Direct Fast Scarlet 4BS (CI Direct Red 23), Eisen Direct Rhodurin BH (CI Direct Red 31), Direct Scarlet B (CI Direct Red) 37), Kayak Direct Scarlet 3B (CI Direct Red 39), Eisen Primula Pink 2BLH (CI Direct Red 75), Sumilite Red F3B (CI Direct Red 80), Eisen Primula Re 4BH (C.I. Direct Red 81), Cayalas Spralbin BL (C.I. Direct Red 83), Cayalas Light Red F5G (C.I. Direct Red 225), Cayalas Light Red F5B (C.I. I. Direct Red 226), Cayalas 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), Sumilite Spula Blue BRR Conch (CI Direct Blue 71), Dibogen Turquoise Blue S (CI Direct Blue 86), Water Blue # 3 (CI Direct Blue 86), Kayara Star Coyze Blue GL (CI Direct Blue 86), Kayara Sprub Lou FF2GL (C.I. I. Direct dyes such as Direct Blue 106) and Caillas Splatter Turquoise Blue FBL (CI Direct Blue 199);
Acid Blue Black 10B (C.I. Acid Black 1), Nigrosine (C.I. Acid Black 2), Suminol Milling Black 8BX (C.I. Acid Black 24), Cyanol Milling Black VLG (C.I. Acid Black 26), Suminol Fast Black BR Conch (CI Acid Black 31), Mitsui Nylon Black GL (CI Acid Black 52), Eisen Opal Black WH Extra Conque (CI Acid Black 52) , Sumilan Black WA (CI Acid Black 52), Ranil Black BG Extra Conch (CI Acid Black 107), Kayanol Milling Black TLB (CI Acid Black 109), Suminol Milling Black B (C CI Acid Black 109), Cyanol Milling Black TLR (CI Acid Black 110), Eisen Opal Black New Conch (CI Acid Black 119), Water Black 187-L (CI Acid Black 154) ), Kayac Acid Brilliant Flavin FF (CI Acid Yellow 7: 1), Kayasil Yellow GG (CI Acid Yellow 17), Xylene Light Yellow 2G 140% (CI Acid Yellow 17), Suminol Leveling Yellow NR (C.I. Acid Yellow 19), Daiwa Tarrazine (C.I. Acid Yellow 23), Kyakuto Thrazine (C.I. Acid Yellow 23), Suminol Fast Yellow R (C.I. Acid Yellow) 25), Diacid Light Yellow GP (C.I. Acid Yellow 29), Suminol Milling Yellow O (C.I. Acid Yellow 38), Suminol Milling Yellow MR (C.I. Acid Yellow 42), Water Yellow # 6 (C.I. Acid Yellow 42), Cyanol Yellow NFG (CI Acid Yellow 49), Suminol Milling Yellow 3G (CI Acid Yellow 72), Suminol Fast Yellow G (CI Acid Yellow 61), Sumi Nord Milling Yellow G (CI Acid Yellow 78), Kayanol Yellow N5G (CI Acid Yellow 110), Suminol Milling Yellow 4G 200% (CI Acid Yellow 141), Kayanol Yellow NG (C CI Acid Yellow 135), Kayanol Milling Yellow 5 GW (CI Acid Yellow) Law 127), Cyanol Milling Yellow 6 GW (C.I. I. Acid Yellow 142), Sumitomo Fast Scarlet A (CI Acid Red 8), Kayak Silk Scarlet (CI Acid Red 9), Solar Rubin Extra (CI Acid Red 14), Daiwa New Coxin ( CI Acid Red 18), Eisenbonso RH (CI Acid Red 26), Daiwa Red No. 2 (CI Acid Red 27), Suminol Leveling Brilliant Red S3B (CI Acid Red) 35), Kayasil rubinol 3GS (CI acid red 37), Eisen erythrosin (CI acid red 51), kayak acid rhodamine FB (CI acid red 52), Suminol leveling rubinol 3GP (C.I. Acid Red 57) Alizarin Rubinol F3G 200% (CI Acid Red 82), Eisen Eosin GH (CI Acid Red 87), Water Pink # 2 (CI Acid Red 92), Eisen Acid Phloxin PB (CI Acid Red 92), Rose Bengal (CI Acid Red 94), Cyanol Milling Scarlet FGW (CI Acid Red 111), Cyanol Milling Rubin 3BW (CI Acid Red 129), Sminool Milling Brilliant Red 3BN Conch (CI Acid Red 131), Suminol Milling Brilliant Red BS (CI Acid Red 138), Eisen Opal Pink BH (CI Acid Red 186), Suminol Milling Brilliant Red B Conch (C.I. Acid Red 249), Kayak Acid Brilliant Red 3BL (C.I. Acid Red 254), Kayak Acid Brilliant Brilliant Red BL (C.I. Acid Red 265), Cyanol Milling Red GW ( CI Acid Red 276), Mitsui Acid Violet 6BN (CI Acid Violet 15), Mitsui Acid Violet BN (CI Acid Violet 17), Sumitomo Patent Pure Blue VX (CI Acid Blue 1) ), Water Blue # 106 (C.I. Acid Blue 1), Patent Blue AF (C.I. Acid Blue 7), Water Blue # 9 (C.I. Acid Blue 9), Daiwa Blue No. 1 (C.I.) I. Acid Blue 9), Supra Noble Bull -B (C.I. I. Acid Blue 15), Orient Soluble Blue OBC (CI Acid Blue 22), Suminol Leveling Blue 4GL (CI Acid Blue 23), Mitsui Nylon Fast Blue G (CI Acid Blue 25), Kayasil Blue AGG (CI Acid Blue 40), Kayasil Blue BR (CI Acid Blue 41), Mitsui Alizarin Saphirole SE (CI Acid Blue 43), Suminol Leveling Sky Blue R Extra Conch (C.I.) I. Acid Blue 62), Mitsui Nylon Fast Sky Blue B (C.I. Acid Blue 78), Sumitomo Brilliant Indocyanine 6Bh / c (C.I. Acid Blue 83), Sandlancyanine N-6B 350% (C.I. I. Acid Blue 90) Water Blue # 115 (CI Acid Blue 90), Orient Soluble Blue OBB (CI Acid Blue 93), Sumitomo Brilliant Blue 5G (CI Acid Blue 103), Kyanol Milling Ultra Sky SE ( CI Acid Blue 112), Cyanol Milling Cyanine 5R (CI Acid Blue 113), Eisen Opal Blue 2GLH (CI Acid Blue 158), Daiwa Guinea Green B (CI Acid Green 3) ), Acid Brilliant Milling Green B (CI Acid Green 9), Daiwa Green # 70 (CI Acid Green 16), Cyanol Cyanine Green G (CI Acid Green 25), Suminol Milling Green G (C.I. Acid dyes of the green 27), and the like;
Eisen Cachilon Yellow 3GLH (CI Basic Yellow 11), Eisen Cachiron Brilliant Yellow 5GLH (CI Basic Yellow 13), Sumiacryl Yellow E-3RD (CI Basic Yellow 15), Maxilon Yellow 2RL (C.I. Basic Yellow 19), Astrazone Yellow 7GLL (C.I.Basic Yellow 21), Kayacrill Golden Yellow GL-ED (C.I.Basic Yellow 28), Astrazone Yellow 5GL (C.I Basic Yellow 51), Eisen Cachilon Orange GLH (C.I. Basic Orange 21), Eisen Cachiron Brown 3GLH (C.I.Basic Orange 30), Rhodamine 6GCP (C.I.Basic Red 1), Eisen Strafloxin (CI Basic Red 12), Sumiacryl Brilliant Red E-2B (CI Basic Red 15), Astrazone Red GTL (CI Basic Red 18), Eisen Catillon Brilliant Pink BGH ( CI Basic Red 27), Maxilon Red GRL (CI Basic Red 46), Eisen Methyl Violet (CI Basic Violet 1), Eisen Crystal Violet (CI Basic Violet 3), Eisen Rhodamine B (CI Basic Violet 10), Astrazon Blue G (CI Basic Blue 1), Astrazon Blue BG (CI Basic Blue 3), Methylene Blue (CI Basic Blue 9) , Maxilon Lou GRL (C.I. Basic Blue 41), Eisen Cachilon Blue BRLH (C.I.Basic Blue 54), Eisen Diamond Green GH (C.I.Basic Green 1), Eisen Malachite Green (C.I.Basic Blue 41) Examples include basic dyes such as Green 4) and Bismarck Brown G (CI Basic Brown 1).

Examples of the pigment used in the water-based ink composition include azo pigments, nitroso pigments, nitro pigments, basic dye pigments, acidic dye pigments, built dye pigments, mordant dye pigments, and natural dye pigments. Examples thereof include organic pigments such as pigments; inorganic pigments such as ocher, barium yellow, bitumen, cadmium red, barium sulfate, titanium oxide, petals, iron black, and carbon black.
More specifically, 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. 11740), 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 Aero NCG (CI 20040), Balkan Fastoe -5G (C.I. 21220), Vulcan Fast Yellow R (C.I. 21135), Tartrazine Lake (C.I. 19140), Quinoline Yellow Lake (C.I. 47005), Anslagen Yellow 6GL (C I.60520), permanent yellow FGL, permanent yellow H10G, permanent yellow HR, anthrapyrimidine yellow (CI 68420), Sudan I (CI 12055), permanent orange (CI 12075), resole Fast Orange (C.I. 12125), Permanent Orange GTR (C.I. 12305), Hansa Yellow 3R (C.I. 11725), Vulcan Fast Orange GG (C.I. 21165), Benzidine Orange G (C.I 21110), Persian ole Di (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 ortho aniline red (C.I. 12090), resol fast scarlet, brilliant fast scarlet (C.I. 12315), brilliant carmine BS, permanent red F2R (C.I. 12310), permanent red F4R (C I.1 2335), permanent red FRL (C.I. I. 12440), Permanent Red FRLL (C.I. 12460), Permanent Red F4RH (C.I. 12420), Fast Scarlet VD, Vulcan Fast Rubin B (C.I. 12320), Vulcan 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), Resol Red (C.I. 15630), Lake Red C (C.I. 15585), Lake Red D (C.I. 15500), Anthosine B (C.I. 18030), Brilliant Scarlet G (C.I. 15800), Risol rubin GK (C.I.158) 5), 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 Perm. Bordeaux F2R (C.I. 12385), Helio Bordeaux BL (C.I. 14830), Bordeaux 10B (C.I. 15880), Bon Maroon Light (C.I. 15825), Bonn 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 Rune (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, Alkaline 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), Indance Ren Blue BC (C.I.6 9825), Indigo (C.I. 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), Examples include phthalocyanine green.

Further, examples of the pigment used in the water-based ink composition include processed pigments in addition to those exemplified above.
More specifically, Renol Yellow GG-HW30, Renol Yellow HR-HW30, Renol Orange RL-HW30, Renol Red HF2B-HW30, Renol Red FGR-HW30, Renol Red F5RK-HW30, RenolBelHH30 RL-HW30, Renol Blue B2G-HW30, Renol Blue CF-HW30, Renol GreenGG-HW30, Renol Brown HFR-HW30, Renol BlackR-HW30 (manufactured by Clariant Japan Co., Ltd.), UTCO-001 , UTCO-021 orange, UTCO-031 red, UTCO-032 , UTCO-042 Violet, UTCO-051 Blue, UTCO-052 Blue, UTCO-061 Green, UTCO-591 Black, UTCO-592 Black (manufactured by Daiichi Seika Kogyo Co., Ltd.), MICROLITH Yellow 4G-A, MICROLITH Yellow MX-A, MICROLITH Yellow 2R-A, MICROLITH Brown 5R-A, Scarlet RA, Red2C-A, Red3R-A, Magenta2B-A, VioletB-A, Blue4G-A, GreenG Etc.).

Examples of the pigment used in the water-based ink composition include commercially available water-dispersed pigments in addition to those exemplified above. These water-dispersed pigments are preferable in terms of improving the handleability and the productivity of the ink composition.
More specifically, as the water-dispersed pigment, in the case of a dispersion of inorganic or organic pigment, uniperse series (manufactured by Ciba Specialty Chemicals Co., Ltd.), Hostfine series (manufactured by Clariant Japan Co., Ltd.), Disperse series, Ryudyye Series (above, Dainippon Ink & Chemicals Co., Ltd.), Rio Fast series, EM Color series (above, Toyo Ink Co., Ltd.), Emacol series, Sandye series (above, Sanyo Dye Co., Ltd.), FUJI SP series ( For example, FUJI COLOR Co., Ltd., Polux series (Sumitomo Color Co., Ltd.), etc. If the dispersion is a fluorescent pigment, NKW series (Nihon Fluorescence Co., Ltd.) ), Shinro Examples include Ihi Color Base Series (Shinloihi Co., Ltd.).

  On the other hand, when the ink composition of the present invention is applied to a non-aqueous inkjet ink, a known dye or pigment used in a conventional non-aqueous ink composition can be used as the colorant.

  The dye used in the non-aqueous ink composition is not particularly limited. For example, any water-insoluble dye can be used in consideration of solubility in a solvent in the ink. More specifically, nigrosine base EE, nigrosine base EEL, nigrosine base EX, nigrosine base EXBP, nigrosine base EB, oil yellow 101, oil yellow 107, oil pink 312, oil brown BB, oil brown GR , Oil Green BG, Oil Blue 613, Oil Blue BOS Oil Black HBB, Oil Black 860, Oil Black BS, Bali Fast Yellow 1101, Bali Fast Yellow 1105, Bali Fast Yellow 3108, Bali Fast Yellow 4120, Bali Fast Orange 2210, Bali Fast Orange 3209, Bali Fast Orange 3210, Bali Fast Red 1306, Bali Fast Red 1308, Bali Fast Red 1355, Bali Fast 1360, Bali Fast Red 2303, Bali Fast Red 2320, Bali Fast Red 3304, Bali Fast Red 3306, Bali Fast Red 3320, Bali Fast Pink 2310N, Bali Fast Brown 2402, Bali Fast Brown 3405, Bali Fast Green 1501, Bali Fast blue 1603, Bali fast blue 1605, Bali fast blue 1607, Bali fast blue 1631, Bali fast blue 2606, Bali fast blue 2610, Bali fast blue 2620, Bali fast violet 1701, Bali fast violet 1702, Bali fast black 1802, Bali Fast Black 1807, Bali Fast Black 3804, 3806, 3808, 3810, 3820, 3830, Spirit Red 10 Varifast Black 2, Ospi Yellow RY, ROB-B, MVB3, SP Blue 105 (manufactured by Orient Chemical Co., Ltd.), Eisenspiron Yellow 3RH, Eisenspiron Yellow GRLH Special, Eisenspiron Yellow C-2GH, Eisenspiron Yellow C-GNH, Eisenspiron Orange 2RH, Eisenspiron Orange GRH Conch Special, Eisenspiron Red GEH, Eisenspiron Red BEH, Eisenspiron Red GRLH Special, Eisen Spiron Red C-GH, Eisen Spiron Red C-BH, Eisen Spiro Violet RH, Eisen Spiron Violet C-RH, Eisen Spiron Brown BH Conch Aisenspiron Brown RH, Aisenspiron Mahogany RH, Aisenspiron Blue GNH, Aisenspiron Blue 2BNH, Aisenspiron Blue C-RH, Aisenspiron Blue BPNH, Aisenspiron Green C-GH, Aisenspiron Green 3GNH Special, Aisen Spiron Black BNH, Eisen Spiron Black MH, Eisen Spiron Black RLH, Eisen Spiron Black GMH Special, Eisen Spiron Black BH Special, S.C. B. N. Orange 703, S.I. B. N. Violet 510, S.I. B. N. Violet 521, S.I. P. T.A. Orange 6, S. P. T.A. Blue 111, SOT Pink 1, SOT Blue 4, SOT Black 1, SOT Black 6, SOT Black 10, SOT Black 12, 13 Liquid, Eisen Rhodamine B Base, Eisen Methyl Violet Base, Eisen Victoria Blue B Base (above, Hodogaya Chemical Industries, Ltd.), Oil Yellow CH, Oil Pink 330, Oil Blue 8B, Oil Black S, Oil Black FS Special A, Oil Black 2020, Oil Black 109, Oil Black 215, AL Yellow 1106D, AL Yellow 3101, AL Red 2308, Neo Super Yellow C-131, Neo Super Yellow C-132, Neo Super Yellow C-134, Neo Super Orange C-233, Neo Super Red C-431, Osuper Blue C-555, Neo Super Brown C-732, Neo Super Brown C-733 (manufactured by Chuo Synthetic Chemical Co., Ltd.), Oreosol Fast Yellow 2G, Oreosol Fast Yellow GCN, Oreosol Fast Orange GL, Oreo Zole Fast Red BL, Oreosol Fast Red RL (manufactured by Taoka Chemical Co., Ltd.), Savinyl Yellow 2GLS, Savinyl Yellow RLS, Savinyl Yellow 2RLS, Savinyl Orange RLS, Savinyl Fire Red GLS, Savinyl Red 3BLS, savinyl pink 6BLS, savinyl blue RN, savinyl blue GLS, savinyl green 2GLS, savinyl brown GLS (above, manufactured by Sand Corp.), magenta SP247%, Chris Le Violet 10B 250%, Malachite Green Crystal Conch, Brilliant Green Crystal H 90%, Spirit Soluble Red 64843 (manufactured by Holiday), Neptune Red Base 543, Neptune Blue Base 634, Neptune Violet Base 604, Basonyle Red 540, Batho Neil violet 600 (above, manufactured by BASF) can be exemplified.

Examples of the pigments used in the non-aqueous ink composition include azo pigments, nitroso pigments, nitro pigments, basic dye pigments, acidic dye pigments, built dye dye pigments, mordant dye pigments, and natural dyes. Examples of known pigments include organic pigments such as organic pigments; inorganic pigments such as ocher, barium yellow, bitumen, cadmium red, barium sulfate, titanium oxide, dial, iron black, and carbon black.
More specifically, TITON SR-1, TITON 650, TITON R62N, TIONE R3L, TITON R7E (manufactured by Sakai Chemical Industry Co., Ltd.), Kronos KR-310, Kronos KR-380, Kronos 480 (more, Titanium Industry) Co., Ltd.), Taipure R-900, Taipure R-602, Taipure R-960, Taipure R-931 (and above, manufactured by DuPont Japan Limited), TITANIXJR301, TITANIXJR805, TITANIXJR602, TITANIXJR701, TITANIXJR800 and above Titanium oxide such as
Special Black 6, Special Black S170, Special Black S610, Special Black 5, Special Black 4, Special Black 4A, Special Black 550, Special Black 35, Special Black 250, Special Black 100, Printex 150T, the U, said V, the 140U, 140V, 95, 90, 85, 80, 75, 55 Printex, Printex 45, Printex P, Printex XE2, Printex L6, Printex L, Printex 300, Printex 30, Printex 3, Printex 3 Printex 25, Printex 2 0, Printex A, Printex G (manufactured by Degussa Japan Co., Ltd.), # 2400, # 2350, # 2300, # 2200B, # 1000, # 950, # 900, # 850, # MCF88, MA600, MA100, MA7 MA11, # 50, # 52, # 45, # 44, # 40, # 33, # 32, # 30, CF9, # 20B, # 4000B (Mitsubishi Chemical Industry Co., Ltd.), MONARCH 1300, MONARCH 1100 , MONARCH 1000, MONARCH 900, MONARCH 880, MONARCH 800, MONARCH 700, MOGUL L, REGAL 400R, REGAL 660R, REGAL 500R, REGAL 330R, REGAL 300R, REGAL 99R, ELFTE 8, ELFTEX 12, BLACK PEARLS 2000 (above, manufactured by Cabot Co. LTD), RAVEN7000, RAVEN5750, RAVEN5250, RAVEN5000, RAVEN3500, RAVEN2000, RAVEN1500, RAVEN1255, RAVEN10250, RAVEN10RA, RAVEN1200RA, RAVEN10RA, RAVEN1200RA Raven890H, Raven890, Raven850, Raven790, Raven780, Raven760, Raven500, Raven450, Raven430, Raven420, Raven410, Raven22, Raven16, Raven14, RAV N825Oil Beads, RAVENH20, RAVENC, Conductex 975, Conductex 900, Conductex SC (manufactured by Koronbiyan Carbon Japan Co., Ltd.) such as carbon black;
BS-605, BS-607 (above, manufactured by Toyo Aluminum Co., Ltd.), Bronze powder P-555, Bronze powder P-777 (above, manufactured by Nakajima Metal Foil Industry Co., Ltd.), Bronze powder 3L5, Bronze powder 3L7 (above, Metal powder pigments such as Fukuda Metal Foil Industry Co., Ltd.
Inorganic pigments such as black iron oxide, low-order titanium oxide, yellow iron oxide, red iron oxide, ultramarine blue, bitumen, cobalt blue, chromium green, chromium oxide;
Hansa Yellow-10G, Hansa Yellow-5G, Hansa Yellow-3G, Hansa Yellow-4, Hansa Yellow-GR, Hansa Yellow-A, Benzine Yellow, Permanent Yellow NCG, Tartrazine Lake, Quinoline Yellow, Sudan 1, Permanent Orange, Indanthren Brilliant Orange GN, Permanent Brown FG, Para Brown, Permanent Red 4R, Fire Red, Brilliant Carmine BS, Pirazone Red, Lake Red C, Quinacridone Red, Brilliant Carmine 6B, Bordeaux 5B, Thioindigo Red, Fast Violet B, Dioxazine Violet, Alkaline Blue Lake Organic pigments such as phthalocyanine blue, indigo, acid green lake, phthalocyanine green;
Examples thereof include inorganic fluorescent pigments such as zinc sulfide, zinc silicate, zinc cadmium sulfate, calcium sulfide, strontium sulfate, and calcium tungstate.

When the pigment used in the non-aqueous ink composition is used as a pigment chip in a state dispersed in an oil-soluble resin, the suitability for producing the ink is improved.
More specifically, as the pigment chip, NC790 white, L1 / 8 red F3RK-70, L1 / 8 black MA100, L1 / 8 yellow N1F, L1 / 8 orange 501, L1 / 8 brown 5R, L1 / 8 blue Examples include KLG, NCL1 / 8 violet PRL50 (manufactured by Taihei Chemical Co., Ltd.) and the like.

  The said colorant may be used individually by 1 type, and may use 2 or more types together. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.

  The content of the colorant in the ink composition is preferably 0.5 to 30% by mass, and more preferably 1 to 25% by mass. By setting it to the lower limit value or more, information can be recorded at a more sufficient density, for example, characters can be recognized more easily. Further, by setting the value to the upper limit value or less, it is possible to obtain a higher effect of suppressing the deterioration of the writing performance accompanying the increase in the dry-up of the ink filled in the chip.

When applying the ink composition of the present invention to an aqueous inkjet ink, when a pigment is used as a colorant, a dispersant may be used to stably disperse the pigment.
Examples of the dispersant for water-based inks include water-soluble resins, water-soluble resins, anionic or nonionic surfactants that are usually used. More specifically, if it is a polymer dispersant (water-soluble resin, water-soluble resin), natural polymers such as lignin sulfonate and shellac; polyacrylate, styrene-acrylic acid copolymer salt, Examples thereof include salts of vinyl naphthalene-maleic acid copolymer, sodium salts of β-naphthalene sulfonic acid formalin condensate, anionic polymers such as phosphates; nonionic polymers such as polyvinyl alcohol and polyethylene glycol. In addition, if it is a surfactant, alkyl sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether acetate, alkyl sulfocarboxylate, α-olefin sulfonate, alkyl phosphate, polyoxyethylene Nonionic surfactants such as anionic surfactants such as alkyl ether phosphates; polyoxyethylene alkyl ethers, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters can be exemplified.

When applying the ink composition of the present invention to a non-aqueous inkjet ink, when a pigment is used as a colorant, a dispersant may be used to stably disperse the pigment.
Examples of the dispersant for non-aqueous ink include a commonly used polymer dispersant, an anionic or nonionic surfactant, and the like. More specifically, in the case of a polymer dispersant, a styrene-butadiene-styrene copolymer, a styrene-acrylic acid copolymer, a copolymer containing styrene-acrylic acid alkyl ester as a main component, and styrene-maleic acid. Examples thereof include oil-soluble polymers such as copolymers and copolymers mainly composed of styrene-maleic acid alkyl ester. For surfactants, alkyl sulfates, polyoxyethylene alkyl ether sulfates, N-acyl amino acids, N-acyl amino acid salts, N-acyl methyl taurine salts, polyoxyethylene alkyl ether acetates, alkyl sulfos Anionic surfactants such as carboxylates, α-olefin sulfonates, alkyl phosphates, polyoxyethylene alkyl ether phosphates; polyoxyethylene alkyl ethers, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters Nonionic surfactants such as the like can be exemplified.

  The said dispersing agent may be used individually by 1 type, and may use 2 or more types together. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.

  The content of the dispersant in the ink composition is preferably 0.1 to 15% by mass, regardless of whether the dispersant is for aqueous ink or non-aqueous ink. By setting the lower limit value or more, a better dispersion effect can be obtained. By setting the upper limit value or less, the dissolution balance of the components contained in the ink can be further improved.

(solvent)
In the present invention, examples of the solvent include water-soluble organic solvents used for the purpose of preventing ink drying at the nozzle opening and preventing ink freezing at low temperatures.
More specifically, as the water-soluble organic solvent for such drying or freeze prevention, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, hexylene glycol, 1,3-butylene glycol, Examples include polyhydric alcohols such as thiodiethylene glycol and glycerine; amides such as 2-pyrrolidone and N-methyl-2-pyrrolidone; polyhydric alcohol amines such as triethanolamine.
The water-soluble organic solvent is preferably used in combination with water.

The content of the water-soluble organic solvent in the ink composition is preferably 5 to 50% by mass.
The total content of the water-soluble organic solvent and water in the ink composition is preferably 10 to 90% by mass.

Examples of the solvent include various organic solvents as a solvent for dissolving or dispersing the colorant.
More specifically, examples of the organic solvent for dissolving or dispersing the colorant include ketones such as acetone, dimethyl ketone, and diphenyl ketone; methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol. Alcohols such as 2-methyl-1-propanol and benzyl alcohol; esters such as ethyl acetate, butyl acetate, amyl acetate, monomethyl ether acetate and propylene glycol monomethyl acetate; alicyclic hydrocarbons such as methylcyclohexane and ethylcyclohexane And aromatic hydrocarbons such as toluene and benzene can be exemplified.

  The content of the organic solvent for dissolving or dispersing the colorant in the ink composition is preferably 5 to 90% by mass. By setting the lower limit value or more, a better dissolution or dispersion effect can be obtained, and a higher effect of suppressing the generation of insoluble matter and aggregates can be obtained. In addition, by setting it to the upper limit value or less, a higher effect can be obtained for suppressing an increase in the ejection amount accompanying a decrease in ink viscosity and improving the stability of ink ejection.

  The said solvent may be used individually by 1 type, and may use 2 or more types together. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.

  The total content of the solvent and water in the ink composition may be appropriately adjusted according to the components to be contained and the purpose, and is not particularly limited, but is preferably 3 to 95% by mass. Water may or may not be contained in the ink composition depending on the purpose.

(Other ingredients)
The ink composition of the present invention may contain, in addition to the shear thinning agent, colorant, solvent, and, if necessary, other components not corresponding to these.
Examples of the other components include various additives such as a rust inhibitor, an antiseptic, an antifoaming agent, a stringing agent, a leveling agent, a coloring aid, and a fixing agent. These additives may be known ones usually used in the field of ink jet ink.
One of these other components may be used alone, or two or more thereof may be used in combination. When using 2 or more types together, the combination and ratio may be appropriately selected according to the purpose.
The content of the other components may be appropriately adjusted according to the purpose and is not particularly limited.

(Viscosity characteristics of ink composition)
The ink composition of the present invention exhibits shear thinning.
Therefore, the ink composition of the present invention has a high viscosity in a stationary state. Specifically, it is preferable that the viscosity (X ₁ ) immediately after applying a shear of 0.01 s ⁻¹ at 25 ° C. without being affected by the application of shear is 0.1 to 100 Pa · s. It is more preferably 5 to 100 Pa · s, and particularly preferably 1 to 100 Pa · s. When it is at least the lower limit value, the viscosity in the state of standing or near standing is high, and the effect of suppressing bleeding of the ink composition is further enhanced. Moreover, handleability will become still more favorable that it is below an upper limit.

The ink composition of the present invention has a low viscosity when an external pressure is applied. Specifically, it is preferable that the viscosity (X ₂ ) immediately after applying a shear of 10,000 s ⁻¹ at 25 ° C. is 0.001 to 0.03 Pa · s without being affected by the application of shear. It is more preferably 001 to 0.026 Pa · s, and particularly preferably 0.001 to 0.022 Pa · s. When it is at least the lower limit, the handleability is further improved. Further, when the pressure is not more than the upper limit value, the ink composition can be discharged more stably and easily due to a decrease in viscosity when a pressure is applied such as when flowing.

  In the present invention, the “state without the influence of shearing” means a state in which the influence is eliminated even if shearing has been applied in advance. For example, a specific state after shearing is applied. The state after time passes is mentioned. In the present invention, the “state without the influence of shearing” can be exemplified by a state of standing for 5 minutes or more, and it is usually sufficient to stand for 5 minutes.

Furthermore, the ink composition of the present invention has a viscosity (X ₂ ) immediately after applying a shear of 10000 s ⁻¹ at 25 ° C. without being affected by the application of shear, and after standing for 5 seconds. The viscosity (X ₃ ) immediately after applying a shear of 0.01 s ⁻¹ at 25 ° C. is preferably 0.04 to 100 Pa · s, more preferably 0.2 to 100 Pa · s, It is particularly preferable that the pressure is 0.4 to 100 Pa · s.
Thus, after applying a shear of 10000 s ⁻¹ at 25 ° C. and allowing to stand for 5 seconds, a viscosity (X ₃ ) immediately after applying a shear of 0.01 s ⁻¹ at 25 ° C. is a shear of 10,000 s ⁻¹ . Is 40% or more of the viscosity (X ₁ ) when no ink is applied (in the state where there is no effect of applying shear), the ejected ink composition immediately reaches the viscosity after landing on the recording medium. As a result, the effect of suppressing bleeding is exhibited more rapidly.

  The viscosity of the ink composition in various states can be adjusted by appropriately adjusting the type and amount of the component.

  The viscosity of the ink composition can be measured by a known method using, for example, a rheometer as a measuring instrument. The angle of the plate used for measurement is preferably 3 ° or less.

(Method for producing ink composition)
The ink composition of the present invention can be produced by the same method as the conventional ink composition.
For example, each component as a raw material may be added and blended with sufficient stirring and mixing using an apparatus such as a ball mill, a bead mill, a roll mill, a Henschel mixer, a propeller stirrer, a homogenizer, a homomixer, or a kneader. At this time, after adding all the components, these may be stirred and mixed, or may be stirred and mixed while adding some or all of the components sequentially.

  The composition obtained by blending each component may be subjected to filtration or centrifugation to remove coarse particles and gas.

Although the temperature at the time of mix | blending each component can be 15-35 degreeC, for example, it is not limited to this. The blending time may be appropriately adjusted in consideration of other conditions.
At the time of blending or after blending each component, the mixture may be subjected to temperature adjustment such as heating and cooling, pressure adjustment such as pressurization and decompression, and atmosphere adjustment such as inert gas replacement.
For example, in order to sufficiently swell the shear thinning agent, the obtained ink composition is allowed to stand at 40 to 90 ° C. for a short time, or stirred and mixed at 40 to 70 ° C. A good quality ink composition may be obtained.
In addition, by keeping the temperature of the ink composition low (for example, 0 to 30 ° C.), an ink composition in which deterioration of quality over time may be further suppressed may be obtained.

  Each of the above operations during the production of the ink composition may be performed alone or in combination of two or more. In the case of performing a combination of two or more, the combination and number of these operations may be appropriately selected according to the purpose.

  The ink composition of the present invention is excellent in the solubility and dispersion stability of the contained components. In addition, when the pressure is applied from the outside, the fluid has sufficient fluidity due to a decrease in viscosity, so that the followability in the flow path and the nozzle is high, and it can be discharged stably and easily. Further, after landing on the recording medium, the viscosity increases rapidly and bleeding is suppressed. This bleeding suppression effect is also manifested on non-absorbing surfaces such as polyvinyl chloride (PVC), so the type of recording medium is not limited. As a result, the contrast of recorded information is improved in various recording media, and a clear and high-quality information recording medium can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.

<Manufacture of ink composition>
Example 1
Ink compositions having the compositions shown in Table 1 were produced. Specifically, an aqueous solution of zeta seagum that was ion-exchanged in advance and dissolved in ethylene glycol was prepared, and other components were added thereto at room temperature and normal pressure, followed by stirring and filtration to obtain an ink composition.

(Example 2)
Ink compositions having the compositions shown in Table 2 were produced. Specifically, a Kelzan AR aqueous solution previously ion-exchanged and dissolved in ethylene glycol was prepared, and other components were added thereto at room temperature and normal pressure, followed by stirring and filtration to obtain an ink composition.

(Example 3)
Ink compositions having the compositions shown in Table 3 were produced. Specifically, an aqueous solution of alkasy gum that was ion-exchanged in advance and dissolved in ethylene glycol was prepared, and other components were added thereto at room temperature and normal pressure, followed by stirring and filtration to obtain an ink composition.

Example 4
Ink compositions having the compositions shown in Table 4 were produced. Specifically, a Pemulene TR-1 aqueous solution previously ion-exchanged and dissolved in ethylene glycol was prepared, and other components were added thereto at room temperature and normal pressure, followed by stirring and filtration to obtain an ink composition. did.

(Example 5)
Ink compositions having the compositions shown in Table 5 were produced. Specifically, a VEEGU PRO aqueous solution that was ion-exchanged in advance and dissolved in ethylene glycol was prepared, and other components were added thereto at room temperature and normal pressure, followed by stirring and filtration to obtain an ink composition.

(Comparative Example 1)
Ink compositions having the compositions shown in Table 6 were produced. Specifically, each component was added at room temperature and normal pressure, dissolved by stirring, and then filtered to obtain a conventional ink composition.

(Comparative Example 2)
Ink compositions having the compositions shown in Table 7 were produced. Specifically, each component was added at room temperature and normal pressure, dissolved by stirring, and then filtered to obtain a conventional ink composition.

<Performance evaluation of ink composition>
[Evaluation of viscosity]
About the ink composition manufactured in Examples 1-5 and Comparative Examples 1-2, after leaving still at 25 degreeC for 5 minute (s), the viscosity immediately after giving the predetermined magnitude | size shear was measured. The measurement results are shown in FIG. In FIG. 1, the vertical axis and horizontal axis of the graph are both logarithmic, and the symbol “m” attached to the unit of viscosity on the vertical axis represents “milli”. In particular, Table 8 shows the viscosity (X ₁ ) immediately after applying a shear of 0.01 s ⁻¹ and the viscosity (X ₂ ) immediately after applying a shear of 10000 s ⁻¹ . At this time, when a shear of 10,000 s ⁻¹ was applied, the viscosity (X ₃ ) immediately after applying a shear of 0.01 s ⁻¹ at 25 ° C. was measured after standing for 5 seconds. Table 8 shows the measurement results.
The viscosity was measured using a rheometer MCR301 (manufactured by Anton Paar), using a cone plate having a diameter of 50 mm and an angle of 1 °, and setting the gap to 0.050 mm.

<Performance evaluation of ink-jet ink>
50 g of the ink compositions produced in Examples 1 to 5 and Comparative Examples 1 and 2 are placed in a centrifugal sedimentation tube, and a tube centrifuge (H-103NR, manufactured by Kokusan Co., Ltd.) is used so that the tube bottom faces outward. Centrifugation was performed and defoamed to obtain a test ink. The following performance evaluation was performed on this test ink.

[Evaluation of discharge performance]
The obtained test ink was ejected with a liquid jet recording apparatus (360 dpi, drive frequency 8 kHz, number of nozzles 508), and whether or not the ink was stably ejected was confirmed using a strobe. The ejection performance was evaluated according to The evaluation results are shown in Table 8.
○: Time for stable ejection is 1 minute or longer Δ: Time for stable ejection is less than 1 minute ×: Cannot be ejected

[Evaluation of bleeding]
Using the obtained test ink, an alphabet is printed on a polyvinyl chloride (PVC) film with a width of 2 mm and a height of 3 mm using a liquid jet recording apparatus (360 dpi, drive frequency 8 kHz, number of nozzles 508). Then, it was visually observed whether it was legible, and the degree of bleeding was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 8.
○: All legible △: Half or more legible characters ×: Half or less legible characters

As apparent from Table 8, the ink composition of Comparative Example 1 containing no shear thinning agent was insufficient in shear thinning and could not suppress bleeding.
Further, the ink composition of Comparative Example 2 had a high viscosity and could not be stably ejected.
On the other hand, the ink compositions of Examples 1 to 5 were excellent in both bleeding suppression and ejection performance.

  The present invention can be used in the field of ink jet recording.

Claims (6)

  An inkjet ink composition comprising a shear thinning agent, a colorant, and a solvent. The viscosity immediately after applying a shear of 10000 s ⁻¹ after standing at 25 ° C. for 5 minutes is 0.001 to 0.03 Pa · s, and after standing for 5 seconds, the viscosity is 0.01 s ⁻¹ at 25 ° C. The inkjet ink composition according to claim 1, wherein the viscosity immediately after applying shear is 0.04 to 100 Pa · s. The inkjet ink composition according to claim 1, wherein the viscosity immediately after applying a shear of 10000 s ^-1 after standing at 25 ° C for 5 minutes is 0.001 to 0.03 Pa · s. 4. The viscosity immediately after applying a shear of 0.01 s ⁻¹ after standing at 25 ° C. for 5 minutes is 0.1 to 100 Pa · s, according to claim 1. Ink-jet ink composition.   The shear thinning agent is a natural polysaccharide, one or more hydrogen atoms constituting the hydroxyl group of the natural polysaccharide are substituted with an alkyl group, a hydroxyalkyl group, or one or more carbon atoms of a hydroxyalkyl group with an oxygen atom A group having an ether bond, a natural polysaccharide derivative substituted with a carboxyalkyl group, a carbamoyl group, an alkylcarbamoyl group or a phosphate group, a salt of the natural polysaccharide, a salt of the natural polysaccharide derivative, an acrylic resin, and The ink composition for inkjet according to any one of claims 1 to 4, wherein the ink composition is one or more selected from the group consisting of mineral substances.   The shear thinning agent is an ether bond in which one or more hydrogen atoms constituting a hydroxyl group of cellulose or cellulose are substituted with an alkyl group, a hydroxyalkyl group, or one or more carbon atoms of a hydroxyalkyl group with an oxygen atom. A cellulose derivative substituted with a group having a carboxyalkyl group, a carbamoyl group, an alkylcarbamoyl group or a phosphate group, a salt of cellulose, and one or more selected from the group consisting of salts of the cellulose derivative Item 6. The inkjet ink composition according to any one of Items 1 to 5.

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