JP2008254296A - Ink-jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording method which keeps a discharge stability excellent even in a low humidity environment and an anti-wear property of the printed image excellent for a non-water-absorbent medium in addition to a water-absorbent medium such as paper. <P>SOLUTION: The ink-jet recording method uses an ink including a surfactant having at least a cloud point, a water-soluble polymer, and a colorant, the water-soluble polymer including 0.5 to 10.0 mass% of the total ink amount, and 80 to 98% thereof not adsorbing to the colorant. The surface temperature of a recording medium is characteristically heated to over the clouding point of the surfactant for recording. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inkjet recording method, and more particularly to a novel inkjet recording method for achieving both stable ink ejection properties and a fast drying speed on a recording medium.

  In recent years, inkjet recording methods can be easily and inexpensively produced images, and thus have been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters.

  In many cases, the ink used in such an ink jet recording method includes various dyes or pigments and water or a water-soluble organic solvent in which the dyes or pigments are dissolved or dispersed as basic components, and various additives as necessary. Additives are known and used.

  Such ink is required to be stably ejected under various environments without causing clogging in the nozzles of the recording head. Furthermore, after the ink is printed on the recording material, quick drying is required in handling the recorded matter.

  In particular, on-demand type ink jet printers are used very often because they discharge ink droplets only when necessary, so that energy is not wasted and the structure is simple. However, in an on-demand type ink jet printer, the viscosity of the ink near the discharge port increases due to evaporation and drying of water at the nozzle port where ink is not discharged according to the image during printing, especially in a low humidity environment. However, there is a drawback that normal ejection is not performed.

  Specifically, the droplet velocity at the time of ejection decreases, and the amount of droplets increases by merging with subsequent droplets, or the landing accuracy deteriorates, causing the image to be disturbed. In severe cases, it may become impossible to discharge. In particular, when a polymer is used in the ink for the purpose of improving the abrasion resistance of the image or when a dispersion such as a pigment is contained, the viscosity is likely to be improved by drying, and the above-mentioned problem appears remarkably. .

In order to prevent this phenomenon, generally, a method of suppressing moisture evaporation at the nozzle opening by adding a high-boiling solvent such as glycerin or a humectant such as sugar to the ink is generally used (see, for example, Patent Document 1). ) However, since these humectants are generally high in viscosity, the amount added to the ink is limited and a sufficient effect cannot be obtained. In addition, when printed on non-absorbing water-based recording media such as polyvinyl chloride and PET, or glossy paper that has not been surface-treated for inkjet, the ink is not absorbed at all or has a slow absorption rate, and is dried by the humectant. Improvement is demanded because the performance is significantly slowed down.
JP 2005-113147 A

  The present invention has been made in view of the present situation, and the object thereof is excellent in ejection stability even in a low humidity environment, and also for non-water-absorbing recording media in addition to water-absorbing media represented by paper. An object of the present invention is to provide an ink jet recording method excellent in image abrasion resistance.

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

  1. A surfactant containing at least a cloud point, a water-soluble polymer, and a pigment are used, and the water-soluble polymer is used as a free polymer in an amount of 0.5 to 10.0% by mass based on the total amount of the ink. An ink jet recording method comprising recording by heating the surface temperature of the recording medium to a cloud point or higher of the surfactant.

  2. 2. The ink jet recording method as described in 1 above, wherein the recording medium is a non-water-absorbing recording medium.

  3. 3. The inkjet recording method according to 1 or 2 above, wherein the water-soluble polymer is a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component, and is neutralized and dissolved with an amine.

  4). 4. The ink jet recording method according to any one of items 1 to 3, wherein the surface temperature of the recording medium is 10 to 60 ° C. higher than the cloud point of the surfactant.

  5. Any one of the above 1 to 4, wherein the ink further contains a solvent selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and 1,2-alkanediol in a total amount of 10 to 30% by mass. The inkjet recording method according to item.

  According to the present invention, there is provided an ink jet recording method which is excellent in ejection stability even in a low humidity environment, and further excellent in image abrasion resistance on a non-water absorbent recording medium in addition to a water absorbent medium represented by paper. I was able to.

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventors have used an ink containing at least a surfactant having a cloud point and 0.5 to 10.0% by mass of a water-soluble polymer as a free polymer, and recording. In an ink jet recording method, wherein recording is performed by heating the surface temperature of the medium above the cloud point of the surfactant, it has been found that both ejection stability in a low humidity environment and quick drying of printed images can be achieved. It is up to the present invention.

  The free polymer as used in the present invention refers to a water-soluble polymer that is not adsorbed to a dispersion such as a pigment in the ink, and in the case where a dispersion such as an ink using a water-soluble dye is not included in the ink, The total amount of water-soluble polymer added is present as free polymer. The free polymer content can be measured by GPC using a supernatant obtained by centrifuging the ink at 30000 rpm for 2 hours.

  It is presumed that the presence of the water-soluble polymer in a free polymer state results in a high contact probability between the molecular chains spread in the drying stage and an excellent film forming ability, resulting in a high ink film rub resistance.

  The printed image includes not only an image printed using an ink containing a color material but also a print formed with an ink not containing a color material for the purpose of imparting gloss or the like.

  Although the effect of the present invention has not yet been clearly interpreted, it is considered as follows. In other words, the fact that ejection stability is obtained in a low-humidity environment is interpreted as an effect based on a mechanism similar to the rise in boiling point, in which evaporation of water is suppressed by a surfactant oriented on the surface of the ink liquid. ing. On the other hand, on the recording medium after printing, the surface of the recording medium is insolubilized by heating the surface of the recording medium above the cloud point of the surfactant contained in the ink, and the effect of suppressing water evaporation is lost and it is easy to dry. I guess it will be. In other words, it is possible to realize an ideal method in which the ink is difficult to dry at the nozzle opening of the head and easy to dry on the recording medium, and even in an ink containing a water-soluble polymer necessary for imparting image abrasion resistance. We believe that stable discharge was possible.

  Hereinafter, the ink jet recording method according to the present invention will be described in detail.

  The surfactant having a cloud point used in the present invention will be described. A cloud point means the temperature which dehydrates and becomes cloudy above a specific temperature when an aqueous solution of a surfactant is heated, and is a physical property found in nonionic surfactants. Examples of the surfactant having a cloud point include polyethylene such as higher alcohol ethylene oxide adduct, alkylphenol ethylene oxide adduct, fatty acid ethylene oxide adduct, polyhydric alcohol fatty acid ester ethylene oxide adduct, polypropylene glycol ethylene oxide adduct, etc. A glycol type surfactant is mentioned. The surfactant having a cloud point that can be used in the present invention is not limited to the above.

  The addition amount of the surfactant having a cloud point varies depending on the molecular weight of the surfactant to be used and the size of the hydrophobic group, but is generally in the range of 0.03 to 2.0%, more preferably 0.2 to 1. Good discharge stability is obtained in the range of 0.0%.

  The surfactant having a cloud point needs to be dissolved inside the head, and the preferred cloud point is 35 ° C. or higher in view of the environmental temperature in which the printer is normally used is 10 ° C. to 30 ° C. Preferably it is 45 degreeC or more. In addition, the upper limit of the cloud point is preferably less than 100 ° C., more preferably 60 ° C. or less because of the necessity of heating the surface temperature of the recording medium above the cloud point of the surfactant, which is a requirement of the present invention. When the cloud point is 100 ° C. or higher, it is necessary to heat the surface temperature of the recording medium to be higher than the boiling point of water, and a bubble-like failure may occur in the recorded image. In addition, when the surface temperature of the recording medium is heated to a temperature higher than 60 ° C., thermal deformation may occur depending on the recording medium.

  Furthermore, the effect of the present invention can be more easily obtained by drying the recording medium at a surface temperature of 10 ° C. higher than the cloud point of the surfactant.

  Next, the water-soluble polymer according to the present invention will be described. In the ink jet recording method of the present invention, in order to obtain the abrasion resistance of the ink film, the water-soluble polymer contained in the ink needs to be used in the range of 0.5% by mass or more and 10.0% by mass or less as a free polymer. is there. More preferably, if it is in the range of 1.0 mass% or more and 5.0 mass% or less, it is easy to achieve both rub resistance and ejection stability.

  A preferred water-soluble polymer in the present invention is a water-soluble copolymer having a hydrophobic monomer as a polymerization component from the viewpoint of obtaining image abrasion resistance even in a high-humidity environment or when moisture adheres. A water-soluble copolymer having a hydrophobic monomer as a polymerization component (hereinafter abbreviated as “water-soluble copolymer”) is stably dissolved in ink, but is given water resistance after drying on a recording medium. A resin is more preferable.

  As such a resin, a resin having a hydrophobic component and a hydrophilic component is designed and used. At this time, as the hydrophilic component, either an ionic or nonionic component may be used, but an ionic component is more preferable, and an anionic component is more preferable. In particular, those which are rendered water-soluble by neutralizing anionic substances with a volatile base component are preferred.

  In particular, at least one of the water-soluble polymers is a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component, and the acid value is preferably in the range of 80 or more and less than 300 in view of the effect of the present invention.

  Hydrophobic monomers of the copolymer include acrylic acid esters (n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc.), methacrylic acid esters (ethyl methacrylate, butyl methacrylate, glycidyl methacrylate). Etc.) and styrene.

  Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, acrylamide and the like, and those having an acidic group such as acrylic acid are preferably partially or completely neutralized with a base component after polymerization. As the neutralizing base in this case, alkali metal-containing bases such as sodium hydroxide and potassium hydroxide, and amines (ammonia, alkanolamine, alkylamine and the like can be used) can be used. In particular, neutralization with amines having a boiling point of less than 200 ° C. is particularly preferable from the viewpoint of improving image fastness.

  As the molecular weight of the water-soluble polymer, an average molecular weight of 3000 to 30000 can be used, and a more preferable molecular weight range is 7000 to 20000.

  The water-soluble polymer having a Tg of about -30 ° C to 100 ° C can be used, and a more preferable Tg range is -10 ° C to 80 ° C.

  The ink of the present invention preferably contains a water-soluble organic solvent selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether or 1,2-alkanediol, and is also suitable for hydrophobic media such as polyvinyl chloride recording media. Excellent wettability and good image quality without ink repelling.

  In addition to this effect, it has been found that the discharge stability under the low humidity environment, which is the object of the present invention, is also effective. With respect to this effect, since these water-soluble organic solvents are relatively hydrophobic, the affinity for the hydrophobic portion of the surfactant having a cloud point used in the present invention is high. It is presumed that ink drying in the mouth can be prevented more effectively.

  Examples of the 1,2-alkanediol include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like. It is particularly preferable in terms of ejection stability.

  The total amount of water-soluble organic solvent selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether or 1,2-alkanediol is preferably used in the range of 7% to 30%, more preferably 10% to 20 % Range. Within this range, good wettability to the recording medium and particularly stable ink ejection properties can be obtained even in a low humidity environment.

  In addition to glycol ether or 1,2-alkanediol, a solvent can be added to the ink of the present invention.

  Specifically, as the solvent according to the present invention, an aqueous liquid medium is preferably used, and examples include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol). , Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), amine (For example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine) , Morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N , N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides ( Examples thereof include dimethyl sulfoxide).

  Next, the pigment according to the present invention will be described.

  As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation, and any of water-dispersible pigments, solvent-dispersible pigments, and the like can be used, for example, organic pigments such as insoluble pigments and lake pigments, An inorganic pigment such as carbon black can be preferably used. This pigment is allowed to exist in a dispersed state in the ink, and this dispersion method may be any of self-dispersion, dispersion using a surfactant, polymer dispersion, and microcapsule dispersion. Particularly preferred from the viewpoint of long-term storage stability.

  The insoluble pigment is not particularly limited, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 202, C.I. I. Pigment red 222, C.I. I. Pigment violet 19 and the like.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  The average particle size in the dispersed state of the pigment is preferably 50 nm or more and less than 200 nm. When the average particle size of the pigment dispersion is less than 50 nm or 200 nm or more, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and often used.

  The pigment according to the present invention is preferably used after being dispersed by a disperser together with a dispersant and other necessary additives depending on other desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. In particular, the particle size distribution of the ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

  A polymer dispersant can be used in the dispersion of the pigment. The polymer dispersant referred to in the present invention has a polymer component having a molecular weight of 5000 or more and 200000 or less. The polymer dispersant is selected from styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid and fumaric acid derivatives. Examples thereof include a block copolymer comprising at least one kind of monomer, a random copolymer and salts thereof, polyoxyalkylene, and polyoxyalkylene alkyl ether.

  In the case of an acidic polymer dispersant, it is preferably added after neutralization with a neutralizing base. Here, the neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine.

  Moreover, it is preferable that it is 10-100 mass% with respect to a pigment as addition amount of a polymer dispersing agent.

  The pigment dispersion according to the present invention is particularly preferably a so-called capsule pigment in which the pigment is coated with a resin. Various known methods can be used as a method for coating the pigment with the resin. Preferably, in addition to the phase-emulsification method and the acid precipitation method, the pigment is dispersed using a polymerizable surfactant. It is preferable to select from a method in which a monomer is fed to the substrate and coating is performed while polymerizing.

  As a more preferred method, the water-insoluble resin is dissolved in an organic solvent such as methyl ethyl ketone, and after partially or completely neutralizing the acidic groups in the resin with a base, the pigment and ion-exchanged water are added and dispersed. After that, a production method in which the organic solvent is removed and is adjusted by adding water as necessary is preferable.

  The mass ratio of the pigment to the resin can be selected in the range of 100/40 to 100/150 as the pigment / resin ratio. In particular, the range of 100/60 to 100/110 has good image durability, injection stability, and ink storage stability.

  In the ink used for the ink jet recording method of the present invention, various surfactants can be preferably used in addition to the surfactant having a cloud point. The surface tension of the ink is preferably 30 mN / m or less, more preferably 28 mN / m or less, from the viewpoint of obtaining high permeability to a water-absorbing recording medium and higher wettability to a non-water-absorbing recording medium. A particularly preferable surfactant for adjusting to this surface tension is a silicon-based surfactant, an acetylene glycol-based surfactant or a fluorine-based surfactant.

  The silicon-based surfactant is a dimethylpolysiloxy acid side chain or terminal-modified polyether, such as KF-351A and KF-642 manufactured by Shin-Etsu Chemical, BYK347 and BYK348 manufactured by Big Chemie. It is commercially available.

  The acetylene glycol surfactant is preferably one having a triple bond in the molecule, a hydroxyl group and an alkyl group on the adjacent carbon atom, and a symmetrical structure with respect to the triple bond. The acetylene glycol compound and acetylene alcohol compound used in the present invention can be obtained as commercial products, and examples thereof include Surfinol and Olphine manufactured by Nissin Chemical Industry Co., Ltd., and acetylenol manufactured by Kawaken Fine Chemical Co., Ltd.

  The fluorosurfactant is particularly preferably a fluorosurfactant having a perfluoroalkenyl group. A fluorosurfactant having a perfluoroalkenyl group is synthesized by introducing a hydrophilic group into a dimer, trimer or pentamer obtained by anionic polymerization of 4-fluoroethylene or hexafluoropropylene. Any of a nonionic type having a polyoxyethylene ether in a hydrophilic group, an anionic type having a sulfonic acid or a carboxylic acid, and a betaine type having a quaternary ammonium salt and a carboxylic acid can be preferably used. It is marketed as the Footage series.

  In addition to the above-described explanation, the ink used in the present invention, if necessary, according to the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances, Various known additives such as resin fine particles, polysaccharides, viscosity modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust preventives, etc. are appropriately selected. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, and the like described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476 UV absorbers, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-14659, JP-A-1-95091 and JP-A-3-95091. No. 3376, etc., described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266. Examples thereof include a fluorescent brightening agent.

  The viscosity of the ink having the above constitution used in the ink jet recording method of the present invention is preferably 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and further preferably 5 to 20 mPa · s. It is.

  In the present invention, the ink is dried by heating the surface temperature of the recording medium above the cloud point of the surfactant. The recording medium may be heated at any timing of the conveyance stage before the image formation with the ink, the image formation stage, and the conveyance stage after the image formation, but before the image formation. It is preferable to set the temperature of the recording medium so that the surface temperature of the recording medium is equal to or higher than the cloud point in the conveyance stage after image formation.

  From the range of the preferred cloud point of the surfactant described above, the preferred heating temperature of the recording medium surface is 35 ° C. or more and less than 100 ° C., and the more preferred range is 45 ° C. or more and 60 ° C. or less.

  As a heating method, it is possible to select a heating method in which a heating heater is incorporated in the media conveyance system or the platen member and heated from the lower side of the recording medium, or a non-contact heating method from the lower side or the upper side by an infrared heater or the like.

  When the ink used in the present invention is ejected to form an image, the ink jet head to be used may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

  Next, the non-water absorbent recording medium according to the present invention will be described.

  The ink of the present invention is suitable not only for printing on a non-absorbent medium such as a vinyl chloride sheet, but also for printing on plain paper, coated paper, inkjet special paper and the like.

  Examples of the non-absorbable recording medium include polymer sheets, boards (soft vinyl chloride, hard vinyl chloride, acrylic plates, polyolefins, etc.), glass, tiles, rubber, synthetic paper, and the like.

  Examples of the low absorption or absorption medium include plain paper (copy paper, plain paper for printing), coated paper, art paper, inkjet exclusive paper, inkjet glossy paper, cardboard, and wood.

  In particular, a preferable non-water-absorbing recording medium capable of obtaining a good image and high image fastness is a recording medium having at least polyvinyl chloride on the recording surface side.

  Specific examples of the recording medium made of polyvinyl chloride include SOL-371G, SOL-373M, SOL-4701 (manufactured by Big Technos Co., Ltd.), glossy vinyl chloride (manufactured by Systemgraph Co., Ltd.), KSM-VS, KSM. -VST, KSM-VT (above, manufactured by Kimoto Co., Ltd.), J-CAL-HGX, J-CAL-YHG, J-CAL-WWWG (above, manufactured by Kyo Show Osaka Co., Ltd.), BUS MARK V400 F vinyl, LITEcal V-600F vinyl (above, manufactured by Flexcon), FR2 (manufactured by Hanwha), LLBAU13713, LLSP20133 (above, manufactured by Sakurai Co., Ltd.), P-370B, P-400M (above, manufactured by Kambo Plus Co., Ltd.), S02P, S12P, S13P, S14P, S22P, S24P, 34P, S27P (manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (manufactured by Lintec Corporation), LKG-19, LPA-70, LPE-248, LPM-45 LTG-11, LTG-21 (manufactured by Shinsei Co., Ltd.), MPI 3023 (manufactured by Toyo Corporation), Napoleon Gloss PVC (manufactured by Futaki Electronics Co., Ltd.), JV-610, Y-114 ( As described above, manufactured by ICC Corporation), NIJ-CAPVC, NIJ-SPVCGT (hereinafter, manufactured by Nichie Corporation), 3101 / H12 / P4, 3104 / H12 / P4, 3104 / H12 / P4S, 9800 / H12 / P4, 3100 / H12 / R2, 3101 / H12 / R2, 3104 / H12 / R 2, 1445 / H14 / P3, 1438 / One Way Vision (manufactured by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (above, manufactured by Mactac, MP1100, MP1100 MPI2001, MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Co., Ltd.), FR2 (manufactured by Hanwha Japan Co., Ltd.), AY-15P, AY-60P, AY-80P, DBSP137GGH, DBSP137GGL (above, manufactured by Insight Inc.), SJT-V200F, SJ T-V400F-1 (above, manufactured by Hiraoka Oryome Co., Ltd.), SPS-98, SPSM-98, SPSH-98, SVGL-137, SVGS-137, MD3-200, MD3-301M, MD5-100, MD5- 101M, MD5-105 (manufactured by Metamark), 640M, 641G, 641M, 3105M, 3105SG, 3162G, 3164G, 3164M, 3164XG, 3164XM, 3165G, 3165SG, 3165M, 3169M, 3451SG, 3551G, 3551M, 3631, 3641M , 3651G, 3651M, 3651SG, 3951G, 3641M (above, manufactured by Orafol), SVTL-HQ130 (manufactured by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl l (above, manufactured by Catalina), RM-SJR (produced by Ryoyo Shoji Co., Ltd.), Hi Lucky, New Lucky PVC (above, produced by LG), SIY-110, SIY-310, SIY-320 (above, Sekisui Chemical) Industrial Co., Ltd.), PRINT MI Frontlit, PRINT XL Lightweight banner (above, manufactured by Endutex), RIJET 100, RIJET 145, RIJET165 (above, manufactured by Ritrama), NM-SG, NM-SM Co., Ltd. Manufactured), LTO3GS (manufactured by Lucio Co., Ltd.), easy print 80, performance print 80 (manufactured by Jetgraph Co., Ltd.), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, 300WG, V350WG (manufactured by Hexis Ltd.), Digital White 6005PE, 6010PE (or, Multifix Co., Ltd.).

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
(Preparation of pigment dispersion-1)
As a pigment dispersant, 3 parts by mass of a styrene-acrylic acid copolymer (John Cryl 678, molecular weight 8500, acid value 215), 1.3 parts of dimethylaminoethanol, and 80.7 parts of ion-exchanged water are stirred and mixed at 70 ° C. and dissolved. did.

  Then, C.I. I. After 15 parts of Pigment Blue 15: 3 was added and premixed, the mixture was dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads, and a pigment dispersion having a cyan pigment content of 15%- 1 was prepared. The average particle diameter of the pigment particles contained in this pigment dispersion was 122 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

(Synthesis of water-soluble polymer aqueous solution)
50 g of methyl ethyl ketone was added to a flask equipped with a dropping funnel, a nitrogen introducer, a reflux condenser, a thermometer and a stirring device, and heated to 75 ° C. while bubbling nitrogen. Thereto, a mixture of 40 g of n-butyl methacrylate, 40 g of styrene, 20 g of acrylic acid, 50 g of methyl ethyl ketone, and 500 mg of initiator (AIBN) was dropped from a dropping funnel over 3 hours. It heated and refluxed for 6 hours after dripping. After allowing to cool, the mixture was heated under reduced pressure to distill off methyl ethyl ketone.

  The polymer residue was dissolved in a solution in which dimethylaminoethanol corresponding to 1.05 mol of acrylic acid added as a monomer was dissolved in 450 ml of ion-exchanged water. A water-soluble polymer aqueous solution having a solid content of 20% and having a hydrophobic monomer as a polymerization component was prepared with ion-exchanged water.

<Preparation of ink>
(Preparation of ink A-1)
The above-mentioned pigment dispersion-1, water-soluble polymer aqueous solution and the compounds shown in the following table were added in this order to prepare an ink composition, which was then filtered through a 0.8 μm filter to obtain ink A-1.

Pigment Dispersion-1 26.7 parts Water-soluble polymer aqueous solution 16.0 parts Diethylene glycol monobutyl ether 8.7 parts 1,2-hexanediol 11.1 parts Surfactant having a cloud point (Pionine P-1525B, Cloud point 35) ℃, Takemoto Oil & Fats Co., Ltd.) 0.3 parts Fluorosurfactant (manufactured by Neogene, Footent 100 Co., Ltd.) 0.2 parts ion-exchanged water remainder (preparation of inks A-2 to A-9)
In the preparation of ink A-1, the active agent having a cloud point was changed to the surfactant shown in Table 1 to prepare inks A-2 to A-5. Further, inks A-6 to A-9 were prepared by changing to various solvents shown in Table 1 as humectants without adding an activator having a cloud point.

  The recording methods 1-1 to 1-12 in which the heating temperatures of the inks and recording media prepared above were set as shown in Table 2 were evaluated according to the following methods. Each ink was centrifuged at 30000 rpm for 2 hours in a centrifuge (cooling high-speed centrifuge H-2100M2 manufactured by Kokusan Co., Ltd.), and the supernatant was collected. The supernatant was dried and concentrated, then dissolved in tetrahydrofuran, and GPC (HLC-8220 GPC Tosoh Corporation) measurement was performed to determine the content of the free polymer. As a result, the amount of free polymer was 2.7 to 3.1 mass. % Range.

<Evaluation of ejection stability>
Each ink was loaded into an inkjet printer equipped with a drop-on-demand piezo-type inkjet head (nozzle number 512 (256 × 2 rows), nozzle diameter 39 μm, nozzle interval 70.5 μm (141 μm × 2 rows)). Next, a 35 × 35 mm square image was recorded in one scan on the recording medium under the conditions of a head scanning speed of 200 mm / second, an ink droplet volume of 42 pl, and a recording density of 360 × 360 dpi. After stopping the head for 20 seconds at a position 5 mm apart from the image, a square image was similarly recorded adjacently. Similarly, the head stop time was changed to 1 minute, 3 minutes, and 10 minutes, and adjacent square images were recorded at 5 mm intervals (a total of 5 square images adjacent at 5 mm intervals).

  Note that the surface temperature of the recording medium was controlled by heating the recording medium from the back with a heater for 3 minutes after the start of printing. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

  As recording media, two types of recording media made of polyvinyl chloride, JT5929PM (manufactured by Mactac) and plain paper (full color PPC paper type 6000, manufactured by Ricoh) were used.

  Using the square image formed as described above, the ejection stability was evaluated based on the head stop time when the disturbance of the edge of the image due to abnormal ejection of ink started to occur.

<Evaluation of image drying>
Using the above-described inkjet printer, 35 × 100 mm was applied to JT5929PM (manufactured by Mactac), which is a recording medium made of polyvinyl chloride, under the conditions of a head scanning speed of 200 mm / second, an ink droplet volume of 42 pl, and a recording density of 360 × 360 dpi. Images were recorded in one scan. Note that the recording medium was heated by a heater from the back side in the same manner as the ejection stability evaluation.

  A regular paper (full color PPC paper type 6000 manufactured by Ricoh Co., Ltd.) was superimposed on the surface of each image with a heater heating time of 1 minute, 3 minutes, and 10 minutes, and rubbed with a finger under a load of about 300 g, and image drying property was evaluated according to the following criteria. .

◎: No color transfer to plain paper in heater heating time 1 minute ○: No color transfer to plain paper in heater heating time 3 minutes △: No color transfer to plain paper in heater heating time 10 minutes ×: Heater heating time Color transfer to plain paper is recognized even in 10 minutes.

<Evaluation of abrasion resistance>
For each recorded image produced in the evaluation of image drying property, the image was rubbed with dry cotton (Kanakin No. 3) for 12 hours at 23 ° C. and 55% relative humidity, and the abrasion resistance was evaluated according to the following criteria.

○: Image hardly changes even after rubbing 50 times or more. Δ: Image density decreases while rubbing 20 to 50 times. ×: Image density decreases while rubbing less than 20 times.

  In the said evaluation rank, (triangle | delta)-(circle) is a practically preferable range.

<Evaluation of marker resistance>
In the evaluation of image drying property, a 35 × 100 mm image was recorded in one scan in the same manner except that the recording medium used was changed to plain paper (full color PPC paper type 6000 manufactured by Ricoh). Next, each of the produced recorded materials was allowed to stand for 30 minutes in an environment of 23 ° C. and 55% RH, and then was rubbed with a yellow fluorescent pen (Sparky 2) manufactured by Zebra under conditions of 500 g load and a speed of 10 mm / sec. The occurrence status was evaluated according to the following criteria.

◯: Dirt is not generated even after rubbing twice. Δ: Dirt is not generated by rubbing once, but dirt is generated by rubbing second time. X: Dirt is generated by rubbing once.

  In the said evaluation rank, (triangle | delta)-(circle) is a practically preferable range.

  Table 2 shows the results obtained as described above.

  As is apparent from this result, it can be seen that the recording method of the present invention is excellent in ejection stability and has a high image drying speed even after long-term recording is stopped. Also, good results were shown in terms of abrasion resistance when printed on a non-water-absorbing recording medium and marker resistance when printed on plain paper.

Example 2
<Preparation of ink>
In the preparation of ink A-2 prepared in Example 1, the amount of water-soluble polymer aqueous solution added was changed, and diethylene glycol monobutyl ether and 1 so that the viscosity range was ± 10% relative to the viscosity of ink A-1. Ink A-10 to A-14 shown in Table 3 were prepared in the same manner except that the addition amount of 2-hexanediol was adjusted.

  Table 4 shows the results of the same evaluation as in Example 1 for recording methods 2-1 to 2-5 in which the heating temperature of the recording medium was set to 55 ° C. using each of the inks prepared above.

  From this result, it can be seen that good results can be obtained in the recording methods 2-2 to 2-4 using the ink whose free polymer amount is within the range of the present invention. The amount of free polymer was measured in the same manner as in Example 1.

Example 3
(Preparation of Pigment Dispersion-2)
50 g of methyl ethyl ketone was added to a flask equipped with a dropping funnel, a nitrogen introducer, a reflux condenser, a thermometer and a stirring device, and heated to 75 ° C. while bubbling nitrogen. Thereto, a mixture of 80 g of n-butyl methacrylate, 5 g of butyl acrylate, 5 g of 2-hydroxyethyl methacrylate, 10 g of acrylic acid and 50 g of methyl ethyl ketone, and 500 mg of initiator (AIBN) was dropped from a dropping funnel over 3 hours. It heated and refluxed for 6 hours after dripping. After standing to cool, volatilized methyl ethyl ketone was added to obtain a resin solution having a solid content of 50% by mass.

  Next, a predetermined amount of a 20% aqueous sodium hydroxide solution as a neutralizing agent was added to 100 g of a 50% solution of the synthesized dispersion resin in methyl ethyl ketone as a neutralizing agent to neutralize 100% of the salt-forming groups. I. Pigment Blue 15: 3 and 50 g were added little by little, and then kneaded in a bead mill for 2 hours. 400 g of ion-exchanged water was added to the resulting kneaded product and stirred, and then heated under reduced pressure to distill off methyl ethyl ketone. Further, ion-exchanged water was added to obtain Pigment Dispersion-2 coated with a resin insoluble in water having a solid content concentration of 15%.

<Preparation of ink>
(Preparation of inks A-15 to A-21)
While stirring 26.7 parts of the pigment dispersion-2 produced above, the compounds shown in Table 5 below were added in order to prepare an ink composition, which was then filtered through a 0.8 μm filter to prepare ink A-15. -A-21 was obtained. In addition, the water-soluble polymer aqueous solution used in Example 1 was used. The amount of free polymer in each ink measured in the same manner as in Example 1 was in the range of 2.7 to 3.1% by mass.

  Table 6 shows the results of evaluating the ejection stability and the image drying properties of the recording methods 3-1 to 3-5 in which the heating temperature of the recording medium is set to 55 ° C. using the prepared inks.

  From this result, in the recording methods 3-1 and 3-2 using the ink in which the total addition amount of triethylene glycol monobutyl ether and 1,2-hexanediol is in the range of 10 to 20% by mass, the ejection stability and the image are obtained. It can be seen that a particularly good drying property is obtained. In addition, with respect to abrasion resistance and marker resistance, good results were obtained in all the recording methods.

Claims (5)

A surfactant containing at least a cloud point, a water-soluble polymer, and a pigment are used, and the water-soluble polymer is used as a free polymer in an amount of 0.5 to 10.0% by mass based on the total amount of the ink. An ink jet recording method comprising recording by heating the surface temperature of the recording medium to a cloud point or higher of the surfactant. The ink jet recording method according to claim 1, wherein the recording medium is a non-water-absorbing recording medium. The inkjet recording method according to claim 1 or 2, wherein the water-soluble polymer is a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component, and is neutralized and dissolved with an amine. . The inkjet recording method according to claim 1, wherein the surface temperature of the recording medium is 10 to 60 ° C. higher than the cloud point of the surfactant. 5. The ink according to claim 1, wherein the ink further contains a solvent selected from diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and 1,2-alkanediol in a total amount of 10 to 30% by mass. 2. The ink jet recording method according to item 1.