JP5712501B2 - Inkjet ink - Google Patents

Description

  The present invention relates to an inkjet ink, and more particularly, to a gel oil inkjet ink.

  Inkjet recording is a recording method in which ink droplets are ejected from a fine nozzle head and printed on a substrate. Energy saving and compact printer design are possible, so it is widely used for homes and offices. ing.

  Ink used in such a recording method is roughly classified into an aqueous type and a non-aqueous type. For water-based types, water-soluble dyes and water-soluble pigments dissolved in glycol-based water-soluble solvents and water are often used. However, printed matter printed with water-based inks generally has poor water resistance, and The cellulose, which is a component of plain paper, interacts with the solvent, and curling and cockling often occur after the solvent is dried. This becomes a big problem in the printed matter for preservation in the office. Recently, double-sided printing is widely performed in office document printing from the viewpoint of resource saving. When performing double-sided printing with water-based ink, if curling or cockling occurs immediately after printing on the front side, there will be a fatal problem for the printer, such as dirt on the paper surface due to rubbing with the head and defective ejection during back side printing. End up.

  Therefore, oil-based inks using vegetable oil or the like as a main solvent are known (for example, see Patent Documents 1 and 2). The oil-based ink has a low interaction with cellulose, and therefore can prevent curling and cockling on plain paper and has excellent water resistance. However, oil-based ink has high penetration of plain paper, so that the back-through of the ink becomes large. Therefore, when performing double-sided printing, measures such as limiting the amount of ink shot are taken, but this causes a reduction in surface density, and satisfactory print quality is not obtained. In addition, because of its high permeability to plain paper, bleeding on the print surface is likely to occur, and the character quality required for high sharpness of the dot outline is reduced, making it impossible to distinguish characters. Problems will occur. In recent years, as with double-sided printing, layout printing methods are widely used. However, in this case, there is a problem that the number of character points is reduced and the sharpness of a higher dot outline must be exhibited.

  Other than this, UV curable ink that forms an image by UV irradiation after ink is discharged onto the substrate, and hot melt ink that discharges the ink in a melted state and cools and solidifies on the substrate. High plain paper prints can be obtained. However, since UV curable ink requires the installation of a light source, the printer becomes expensive and large in size, and cannot fully utilize the merit of inkjet as a compact printer. Similarly, in the case of hot melt ink, it is necessary to increase the hardness of the ink in order to increase the rub resistance, thereby raising the problem that the melting point increases and the printer becomes large.

JP 2005-290035 A JP 2008-221780 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink-jet ink that has low system load, high plain paper suitability, and excellent character quality and fixability.

  The above object of the present invention can be achieved by the following configuration.

  1. An ink-jet ink comprising a gelling agent capable of reversibly gelling an ink-jet ink and containing a rosin resin, a terpene resin, and a non-aqueous solvent. .

  2. 2. The ink-jet ink according to item 1, wherein the ink-jet ink has a gel strength value of 1 or more and 100 or less.

  3. 3. The inkjet ink according to 1 or 2, wherein the total content of the rosin resin and the terpene resin is 10 to 30% by mass.

  4). 4. The inkjet ink according to any one of items 1 to 3, wherein the rosin resin and the terpene resin have an average molecular weight of 1000 to 50000, respectively.

  5. The inkjet ink according to any one of 1 to 4, wherein the non-aqueous solvent includes a fatty acid ester.

  6). 6. The ink-jet ink as described in 5 above, wherein the fatty acid ester is an ester compound of an alcohol having 4 or less carbon atoms.

  According to the present invention, it is possible to provide an ink-jet ink that has a low system load, high plain paper suitability, and excellent character quality and fixability.

  Hereinafter, although the form for implementing this invention is demonstrated, this invention is not limited to these.

  The present invention contains a gelling agent capable of reversibly gelling an inkjet ink in an amount of 0.5 to 10% by mass, and contains a rosin resin, a terpene resin, and a non-aqueous solvent. And

  By adopting the above-described configuration, an ink-jet ink having a low system load, high plain paper suitability, and excellent character quality and fixability can be obtained.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail.

  In the present invention, the inkjet ink of the present invention contains a gelling agent capable of reversibly gelling (gel oil inkjet ink), and the inkjet ink is used on plain paper by utilizing the phase transition of the inkjet ink depending on temperature. It gels before penetrating excessively, prevents bleeding and provides a high surface concentration. It is considered that the gel structure forms a polymer network by hydrogen bonds and intermolecular interactions in a state where the solvent is contained. The gelling agent capable of reversibly gelling the inkjet ink of the present invention has the function of causing phase transition at 40 ° C. or more and 80 ° C. or less by adding the gelling agent to the inkjet ink. A compound.

  The addition amount of the gelling agent capable of reversibly gelling the inkjet ink into the inkjet ink is preferably 0.5 to 10.0% by mass. If it is 0.5% by mass or more, it is preferable from the viewpoint of prevention of bleeding, character quality, and surface concentration. Moreover, it is preferable that it is 10.0 mass% or less from a viewpoint of the raise prevention of the phase transition temperature of an inkjet ink, and the load prevention to a printer.

  The gel referred to in the present invention means that the solute has independent mobility due to the interaction such as lamellar structure, polymer network formed by covalent bond or hydrogen bond, polymer network formed by physical aggregation, and aggregate structure of fine particles. It has a structure that has been lost and assembled, and is a solidified or semi-solidified state with a sudden increase in viscosity and a significant increase in elasticity.

  In general, a gel becomes a fluid solution (sometimes called a sol) by heating, a thermoreversible gel that returns to the original gel when cooled, and once gelled, it can be reheated even if heated. There is a heat irreversible gel that does not return. The gel formed by the gelling agent according to the present invention is preferably a thermoreversible gel.

  In the inkjet ink of the present invention, the phase transition temperature of the inkjet ink is preferably 40 ° C. or higher and 80 ° C. or lower, more preferably 45 ° C. or higher and 70 ° C. or lower. If the phase transition temperature of the ink-jet ink is 40 ° C. or higher, when the ink-jet ink droplets are ejected from the recording head, a stable light emission can be obtained without being affected by the printing environment temperature, and 80 ° C. or lower. If it is, it is not necessary to heat an inkjet recording device to excessively high temperature, and the load to the head of an inkjet recording device or the member of an inkjet ink supply system can be reduced.

  In order to realize the phase transition temperature of the inkjet ink defined above, the melting point of the gelling agent to be used is preferably 20 to 250 ° C, more preferably 40 to 90 ° C. The phase transition temperature of inkjet ink is the temperature at which the viscosity changes suddenly from a fluid solution state to a gel state. Gel transition temperature, gel dissolution temperature, gel softening temperature, sol-gel phase transition It is synonymous with terms called temperature and gel point.

  The method for measuring the phase transition temperature of the inkjet ink of the present invention (hereinafter also simply referred to as ink) is, for example, that a small iron piece sealed in a glass tube is placed in an dilatometer and spontaneously falls in the ink liquid in response to a temperature change. The method of setting the phase transition temperature at the point of time (J. Polym. Sci., 21, 57 (1956)), when an aluminum cylinder is placed on the ink, and the gel temperature is changed, the aluminum cylinder spontaneously drops. The method of measuring the temperature to perform as a phase transition temperature (The Japan Society of Rheology Vol.17,86 (1989)) is mentioned. As a simple method, place a gel-like test piece on the heat plate, heat the heat plate, measure the temperature at which the shape of the test piece collapses, and obtain this as the phase transition temperature of the ink. it can. In this invention, the measuring method on a heat plate was employ | adopted.

  Specific examples of the gelling agent used in the ink of the present invention include 12-hydroxystearyl acid, behenic acid / glyceryl eicosandioate, inulin stearate, metal soap, silicic anhydride, N-lauroyl-L-glutamic acid-α. , Γ-dibutylamide, stearone and the like.

  In the ink of the present invention containing the gelling agent, the ink viscosity at a temperature of the ink phase transition temperature + 5 ° C. is preferably 1 to 10 mPa · s, more preferably 1 to 5.0 mPa · s. . If the ink viscosity at the ink phase transition temperature + 5 ° C. is in the range of 1 to 10 mPa · s, stable emission characteristics can be obtained.

  Moreover, in this invention, fixability can be raised by using rosin resin and terpene resin together. The reason is not clear, but by adding a viscous terpene resin to a hard rosin resin, we believe that the film becomes flexible and can spread this force. The addition amount of the resin is preferably 10% by mass or more and less than 30% by mass of the rosin resin and the terpene resin from the viewpoint of injection property and fixing property, and the molecular weight of the resin is preferably 1000 to 50000.

  The rosin resins used are Sanyo Kasei's Hariphenol series (rosin-modified phenolic resin) and Harimac series (rosin-modified maleic acid resin), and Arakawa Chemical Industries' tamanor series (rosin-modified phenolic resin). And marquide series (rosin-modified maleic resin). On the other hand, examples of the terpene resin include YS resin series (terpene resin) and clearon series (hydrogenated terpene resin) manufactured by Yashara Chemical Co., Ltd.

  Furthermore, in the present invention, by using a non-aqueous solvent, penetration into plain paper can be promoted and fixability can be improved. The non-aqueous solvent referred to here is a solvent that does not become compatible and separates or becomes cloudy when mixed with water at a ratio of 1: 1. Especially, it is preferable that it is a fatty acid ester whose alcohol origin part is C4 or less from the height of plain paper permeability.

  The non-aqueous solvent is preferably 20% by mass or more and less than 60% by mass from the viewpoint of fixability and color developability.

  The ink of the present invention preferably has a gel strength of 100 or less from the viewpoint of fixability. Examples of the method for measuring the gel strength include a probe method as described in “JIS K 6503”. By setting the gel strength to 100 or less, the ink penetrates into plain paper a little. Thereby, the fixing property to plain paper is improved.

<Each component of ink>
Next, the components of the ink of the present invention excluding the above items will be described.

(Color material)
In the ink of the present invention, a dye or a pigment can be used without limitation as a color material constituting the ink, but a pigment having good dispersion stability with respect to the ink component and excellent weather resistance is used. It is preferable. Although it does not necessarily limit as a pigment, For example, the organic or inorganic pigment of the following number described in a color index can be used for this invention.

Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 53: 1. 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144, 146 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13 16, 20, 36,
Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17-1, 22, 27, 28, 29, 36, 60 as blue or cyan pigments ,
Examples of green pigments include Pigment Green 7, 26, 36, 50,
As the yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193,
As the black pigment, Pigment Black 7, 28, 26 and the like can be used according to the purpose.

  Specific product names include, for example, chromo fine yellow 2080, 5900, 5930, AF-1300, 2700L, chromo fine orange 3700L, 6730, chromo fine scarlet 6750, chromo fine magenta 6880, 6886, 6891N, 6790, 6887. , Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Ku Mofine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040 , C405 (F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B1476T-7, 1483LT, 3840, 3870 , Seika Fast Bordeaux 10B-430, Seica Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C7 18, A612, cyanine blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seikagaku), KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302 , 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (large Nippon Ink Chemical Co., Ltd.), Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pi gment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, C USN, Colortex Maroon 601, Colortex Brown B610N, Colortex violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403B, Col. , Lionol lue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink), Toner Magenta E02, Permanent RubinF6B, Toner Yellow HG, Permanent Yellow GG-02, HostaBem G2 , Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant), carbon black # 2600, # 2400, # 2350, # 2200, # 1000, # 990, # 980, # 970, # 960, # 950, # 850, MCF88, # 750, # 650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77 # 52, # 50, # 47, # 45, # 45L, # 40, # 33, # 32, # 30, # 25, # 20, # 10, # 5, # 44, CF9 (Mitsubishi Chemical) Can be mentioned.

  For the dispersion of the pigment, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like can be used.

  Further, a dispersing agent can be added when dispersing the pigment. As the dispersant, a polymer dispersant is preferably used. Examples of the polymer dispersant include Avecia's Solsperse series and Ajinomoto Fine-Techno's PB series. Furthermore, the following are mentioned.

  Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a salt of a long chain polyaminoamide and a polar acid ester, a high molecular weight unsaturated acid ester, Polymer copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formalin condensate salt, aromatic sulfonic acid formalin condensate salt, polyoxyethylene alkyl phosphate ester, polyoxyethylene nonyl Examples thereof include phenyl ether, stearylamine acetate, and pigment derivatives.

  Specific examples include “Anti-Terra-U (polyaminoamide phosphate)”, “Anti-Terra-203 / 204 (high molecular weight polycarboxylate)” manufactured by BYK Chemie, “Disperbyk-101 (polyaminoamide phosphate). And acid ester), 107 (hydroxyl group-containing carboxylic acid ester), 110 (copolymer containing an acid group), 130 (polyamide), 161, 162, 163, 164, 165, 166, 170 (polymer copolymer) ”,“ 400 ”,“ Bykumen ”(high molecular weight unsaturated acid ester),“ BYK-P104, P105 (high molecular weight unsaturated acid polycarboxylic acid) ”,“ P104S, 240S (high molecular weight unsaturated acid polycarboxylic acid and Silicone) ”,“ Lactimon (long chain amine, unsaturated acid polycarboxylic acid and silicon Down) "and the like.

  In addition, “Efka CHEMICALS” “Efka 44, 46, 47, 48, 49, 54, 63, 64, 65, 66, 71, 701, 764, 766”, “Efka Polymer 100 (modified polyacrylate), 150 (aliphatic) System modified polymer), 400, 401, 402, 403, 450, 451, 452, 453 (modified polyacrylate), 745 (copper phthalocyanine system) "; Kyoei Chemical Co., Ltd." Floren TG-710 (urethane oligomer) "," “Flonon SH-290, SP-1000”, “Polyflow No. 50E, No. 300 (acrylic copolymer)”; “Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150, manufactured by Enomoto Kasei Co., Ltd. (Aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) "and the like That.

  Furthermore, “Demol RN, N (Naphthalenesulfonic acid formalin condensate sodium salt), MS, C, SN-B (aromatic sulfonic acid formalin condensate sodium salt), EP”, “Homogenol L-18 (made by Kao Co., Ltd.) Polycarboxylic acid type polymer) "," Emulgen 920, 930, 931, 935, 950, 985 (polyoxyethylene nonylphenyl ether) "," acetamine 24 (coconut amine acetate), 86 (stearyl amine acetate) "; "Solspers 5000 (phthalocyanine ammonium salt type), 13240, 13940 (polyesteramine type), 17000 (fatty acid amine type), 24000, 32000" manufactured by Nikko Chemical Co., Ltd. "Nikkor T106 (polyoxyethylene sorbitan monooleate), MY" -IEX (polyoxyethylene monostearate), Hexagline4-0 (hexaglyceryl ruthenate Huwei rate) ", and the like.

  These pigment dispersants are preferably contained in the ink in the range of 0.1 to 20% by mass. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment. The dispersion medium is used using a solvent or a polymerizable compound.

  The pigment is preferably dispersed so that the average particle diameter of the pigment particles is 0.08 to 0.5 μm, and the maximum particle diameter is 0.3 to 10 μm, preferably 0.3 to 3 μm. The selection of the dispersion medium, the dispersion conditions, and the filtration conditions are appropriately set. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

  In the ink of the present invention, a conventionally known dye, preferably an oil-soluble dye can be used as necessary. Specific examples of oil-soluble dyes that can be used in the present invention are given below, but the present invention is not limited to these.

<Magenta dye>
MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (manufactured by Mitsui Toatsu Co., Ltd.), AIZENSOT Red-1, AIZEN SOT Red-2, AIZEN SOTRed-3, AIZEN SOT Pink-1, SPERON Red GE SPECIAL (above, manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (above, manufactured by Bayer Japan), KAYASET Red B, KAYASET Red 130, KAYASET Red Japan 802 ), PHLOXIN, ROSE BENGAL, ACID Red (above, made by Daiwa Kasei), HSR-31, DIARESIN Red K (below) , Manufactured by Mitsubishi Kasei Co., Ltd.), Oil Red (manufactured by BASF Japan Co., Ltd.).

<Cyan dye>
MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, MS Cyan VPG (manufactured by Mitsui Toatsu Co., Ltd.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, SIRIUS SUTRA TURQ. Blue FB-LL 330% (above, Bayer Japan), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5 200 (above, Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, Oleosol Fast Blue GL (above, Daiwa Kasei), DIARESIN Blue P (Mitsubishi Kasei), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (above, manufactured by BASF Japan).

<Yellow dye>
MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (Mitsui Toatsu), AIZEN SOT Yellow-1, AIZEN SOT YellowW-3, AIZEN SOT Yellow-6 (above, manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, MACROLEX FLUOR. Yellow 10GN (above, Bayer Japan), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, KAYASET Yellow EG (above, Nippon Kayaku), DAIWA Yellow 330H HSY-68 (manufactured by Mitsubishi Kasei Co., Ltd.), SUDAN Yellow 146, NEOPEN Yellow 075 (above, manufactured by BASF Japan).

<Black dye>
MS Black VPC (Mitsui Toatsu Co., Ltd.), AIZEN SOT Black-1, AIZEN SOT Black-5 (above, Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESOLIN Black BS (above, Bayer Japan Co., Ltd.), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Kasei Co., Ltd.), HSB-202 (manufactured by Mitsubishi Kasei Co., Ltd.), NEPTUNE Black X60, NEOPEN Black X58 (manufactured by BASF Japan) .

  The amount of pigment or oil-soluble dye added is preferably 0.1 to 20% by mass, more preferably 0.4 to 10% by mass. If it is 0.1% by mass or more, good image quality can be obtained, and if it is 20% by mass or less, an appropriate ink viscosity in ink ejection can be obtained. In addition, two or more kinds of colorants can be mixed as appropriate for color adjustment.

(Other additives)
In the ink of the present invention, in addition to the above description, if necessary, the output stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performance improvement objectives are known. Various additives, for example, a viscosity modifier, a specific resistance modifier, a film forming agent, an ultraviolet absorber, a fading inhibitor, an antibacterial agent, and a rust inhibitor can be appropriately selected and used.

  In particular, it is preferable to add an antioxidant to prevent oxidative polymerization in the vicinity of the nozzle. Examples of the antioxidant include amine compounds such as alkylphenol compounds, phenylenediamine, hindered phenol compounds, hydroquinone compounds, hydroxylamine compounds, and the like.

  The ink of the present invention forms an image by forming a difference between the ink temperature in the recording head and the temperature of the recording medium, thereby increasing the viscosity or gelation of the ink of the present invention that has landed on the recording medium due to a decrease in temperature. Fix and then fix by oxidative polymerization of unsaturated fatty acid esters.

  As the fixing means by thickening or gelation, for example, an inkjet recording apparatus used for inkjet recording is heated on a recording medium after heating the recording head to a predetermined temperature in a relatively low temperature environment such as room temperature. The method of landing on the surface and naturally cooling and fixing by the environmental temperature, the method of cooling the recording medium in advance, or the method of fixing by blowing cold air to the landing part, etc. are appropriately selected and used. However, the ink jet recording method of the present invention is characterized in that the ink in the recording head is heated to a predetermined temperature range higher than the room temperature. Examples of the method for heating the ink in the recording head include a method for heating the ink directly or indirectly by attaching a heater inside or outside the recording head, a method for utilizing heat generated when the recording head is driven, and the like. I can do it. As the ink discharge conditions, it is preferable from the viewpoint of improving discharge stability and image quality that the recording head and the ink are heated at a temperature of 10 ° C. or higher and lower than 40 ° C. than the gel transition temperature of the ink according to the present invention. . By making the ink ejection temperature 10 ° C. or more higher than the gel transition temperature, it is possible to prevent the ink from gelling in the recording head due to temperature fluctuations, and to suppress ejection defects. By setting the temperature below 40 ° C., the time until the ink reaches the gel transition temperature after landing on the recording medium can be shortened, and the gelation speed can be increased. As a result, high image quality can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “part” or “%” in the examples represents “part by mass” or “% by mass”.

Example 1
<Production of inkjet ink>
(Preparation of ink 1)
2 parts by mass of Solsperse 28000 (manufactured by Lubrizol) was dissolved in 67 parts by mass of butyl stearate, and 5 parts by mass of carbon black MA7 (manufactured by Mitsubishi Chemical Corporation) was added and premixed. Thereafter, it was dispersed in a bead mill for about 20 minutes to obtain an ink.

  Thereto, 20 parts by mass of rosin-modified phenol resin Tamanol 361 (Molecular weight 36000 manufactured by Arakawa Chemical Co., Ltd.) and 5 parts by mass of terpene resin YS REDIN SX 100 (Yasuhara Chemical Co., Ltd.) were added and stirred, and further 1 part by mass of stearone as a gelling agent was added. The ink was added and stirred at 90 ° C. for 20 minutes to obtain ink 1 (present invention).

(Preparation of inks 2 to 35)
Inks 2 to 35 (present invention , reference ) were obtained in the same manner as ink 1 except that the types and amounts of gelling agents, resins, and non-aqueous solvents listed in Tables 1 to 4 were used.

T-1: Ketone wax manufactured by Kao Corporation FLORASTERS 70: Fatty acid ester wax manufactured by GLORA TECH Nomucoat HK-G: Fatty acid ester wax manufactured by Nisshin Oilio Co., Ltd. Hariphenol P900: Rosin resin manufactured by Harima Kasei Co., Ltd. (molecular weight 21000 )
Marquide: Rosin resin (molecular weight 3750) manufactured by Arakawa Chemical Co., Ltd.
KG2212: Rosin modified phenolic resin (molecular weight 133000) manufactured by Arakawa Chemical Co., Ltd.
YS REDINSX 100: Terpene resin manufactured by Yasuhara Chemical Co., Ltd. CLEARON N M105: Terpene resin manufactured by Yasuhara Chemical Co., Polyamide S40E: Polyamide resin manufactured by Sanyo Kasei Co., Ltd. (molecular weight 50000)
Coumarone G90: Coumarone resin (molecular weight 770) manufactured by Nikkaku Chemical Co., Ltd.
(Preparation of inks 36 to 71)
Inks 36 to 71 (comparative) were obtained in the same manner as ink 1 except that the types and amounts of gelling agent, resin, non-aqueous solvent, colorant, and dispersant described in Tables 1 to 4 were used. .

"Evaluation method"
《Gel strength》
The gel strength was measured by the method described in JIS K 6503.

<< Inkjet image formation >>
An ink jet recording apparatus equipped with a piezo type ink jet nozzle is loaded with the inks 1 to 35 of the present invention and the comparative inks 36 to 71, and on a PPC paper (manufactured by J PAPER Konica Minolta Business Solutions Co., Ltd.) Printed.

  The ink supply system consists of an ink tank, a supply pipe, a front chamber ink tank immediately before the print head, a pipe with a filter, and a piezo head. The ink supply system insulates from the front chamber tank to the print head and increases the gel transition temperature of ink to + 30 ° C. Warm up. The piezo head also has a built-in heater, and the ink temperature in the recording head is heated to the gel transition temperature + 30 ° C. For the ink that does not cause gelation, the ink was uniformly heated to 70 ° C.

  The piezo head has a nozzle diameter of 20 μm and 512 nozzles (256 nozzles × 2 rows, staggered arrangement, 1 row nozzle pitch of 360 dpi (dpi indicates the number of dots per 2.54 cm)), and one drop of liquid each Printing was performed at a recording resolution of 1440 dpi × 1440 dpi by ejecting at a droplet velocity of about 6 m / sec under the condition that the droplet volume was 2.5 pl. Each recording medium was at room temperature (23 ° C.).

<Text quality>
With the above ink, the resolution is 1400 dpi x 1440 dpi on a PPC paper (manufactured by JPAPER Konica Minolta Business Solutions), 3 points, 4 points and 5 points of MS Mincho, and the Chinese character "mouth, four, day, times ", Cause, trouble, solid, country, eyes, figure, country" were printed, the printed character image was visually observed, and character quality was evaluated according to the following evaluation criteria.

◎: All 3 point extracted characters are clearly recorded in detail ○: 3 point extracted characters are partially unreadable △: 3 points extracted characters are partially readable, but 4 points All the extracted characters are legible. ×: Only a part of the four-point missing characters can be interpreted. XX: The four-point missing characters are not readable at all.
A sample printed with solid images on PPC paper (manufactured by JP PAPER Konica Minolta Business Solutions) with the above ink was allowed to air dry overnight, and then the printed part of the sample was printed on 2 cm x 2 cm PPC paper (non-printed part) as friction paper. As a result, 30 reciprocations of 10 cm are performed with a load of 2N. The state of the printed part and the ink adhering to the non-printed part were visually observed, and the fixability was evaluated based on the following criteria.

◎: The printing surface does not change, and ink does not adhere to the friction paper. ◎: The printing surface does not change, and ink adheres to a part of the friction paper. ○: The printing surface does not change, and it is a quarter of the friction paper. △: The printing surface does not change and the ink adheres to about half of the friction paper. ×: The printing surface peels off and the ink adheres to about half of the friction paper. XX: The printing surface peels off. Ink adheres to the entire surface of friction paper <Continuous ejection stability>
Using a piezo-type inkjet head, with the ink supply system and the piezo head heated to the gel transition temperature of the ink + 30 ° C., a drop volume of 2.5 pl and a drop speed of about 6 m / sec are 1 The time was continuously emitted, and the number of ink droplet ejection nozzles was observed with a microscope.

  A percentage of (number of nozzles−number of missing / bent nozzles at the time of continuous injection 1 h) / (number of nozzles) was determined, and continuous discharge stability was evaluated based on the following evaluation criteria.

The piezo head used a nozzle diameter of 20 μm, and the number of nozzles was 512 nozzles (256 nozzles × 2 rows, staggered arrangement, 1 row nozzle pitch 360 dpi) ○: The discharge nozzle ratio is 85% or more and 100% Δ: The discharge nozzle The ratio is 70% or more and less than 85%. X: The discharge nozzle ratio is less than 70%. The results are also shown in Tables 5 to 7.

  As is apparent from Tables 5 to 7, it can be seen that the ink of the present invention is excellent in continuous ejection stability, character quality, and fixability.

  In the case of the present invention, it can be seen that it is possible to provide an ink-jet ink having a low system load, excellent continuous ejection stability, high plain paper suitability, and excellent character quality and fixability.

Claims (5)

Containing a gelling agent capable of reversibly gelling an inkjet ink in an amount of 0.5% by weight or more and less than 10% by weight, and containing a rosin resin, a terpene resin, and a non-aqueous solvent ; An ink-jet ink characterized in that the total content of terpene resins is 10 to 30% by mass .   The inkjet ink according to claim 1, wherein the inkjet ink has a gel strength value of 1 or more and 100 or less. The inkjet ink according to claim 1 or 2 , wherein the rosin resin and the terpene resin have an average molecular weight of 1,000 to 50,000, respectively. The inkjet ink according to any one of claims 1 to 3 , wherein the non-aqueous solvent contains a fatty acid ester. The inkjet ink according to claim 4 , wherein the fatty acid ester is an ester compound of an alcohol having 4 or less carbon atoms.