JP2009120693A - Inkjet ink for non-water-absorbing recording medium, and inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink for a non-water-absorbing recording medium that affords a high-quality image having a high gloss, being suppressed in spot generation and exhibiting excellent image fastness, and to provide an inkjet recording method using the same. <P>SOLUTION: The inkjet ink for a non-water-absorbing recording medium comprises an organic solvent 1 having a surface tension within the range of at least 25 mN/m and at most 35 mN/m and undissolvable in water at an arbitrary ratio, a pigment, a high-molecular weight polymer and water. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a novel water-based ink-jet ink for a non-water-absorbing recording medium and an ink-jet recording method using the same, and more particularly, high gloss with high gloss, suppressed occurrence of spots, and excellent image fastness. The present invention relates to an ink-jet ink for a non-water-absorbing recording medium capable of obtaining a high quality image and an ink-jet recording method using the same.

  In recent years, since an inkjet recording method can produce images easily and inexpensively, it has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters.

  Ink jet inks used in such ink jet recording methods include water-based ink-jet inks composed of water and a small amount of organic solvents, non-aqueous ink-jet inks that contain substantially no water, and heat-melt inks that are solid at room temperature. There are a plurality of ink-jet inks such as hot-melt ink for printing and actinic ray-curable ink-jet ink that is cured by actinic rays such as light after printing, and these are used properly depending on the application.

  On the other hand, non-water-absorbing recording media such as polyvinyl chloride are used in a wide range of applications such as outdoor postings that require long-term weather resistance and printed matter that requires adhesion to curved objects. There are many methods for printing on polyvinyl chloride. However, there is an ink jet recording method as a method suitable for the production of a small variety of products because there is no need to prepare a plate and the period until finishing is short.

  As an example of an inkjet ink system that can be recorded on the above-described polyvinyl chloride recording medium, an inkjet ink containing cyclohexanone is disclosed (see Patent Document 1). Cyclohexanone has a high solubility in polyvinyl chloride, and the pigment in the ink-jet ink penetrates into the polyvinyl chloride, so that good scratch resistance can be obtained. In addition, non-aqueous inkjet inks containing organic solvents such as N-methylpyrrolidone and amide are disclosed as organic solvents that have a weak odor compared to cyclohexanone and are preferable in the working environment (see Patent Documents 2 and 3). In addition, a non-aqueous ink jet ink to which a resin such as vinyl chloride-vinyl acetate copolymer or acrylic is added for the purpose of improving image fastness such as scratch resistance is disclosed (see Patent Documents 4 and 5).

  Although these odors can be suppressed to some extent by these ink-jet inks and ink-jet inks exhibiting excellent scratch resistance against polyvinyl chloride can be obtained, the environmental burden associated with the discharge of a large amount of organic solvent due to drying is a problem.

In response to this problem, a water-based pigment inkjet ink using an ink-soluble resin for a medium coated with a vinyl film or a vinyl resin as a recording medium has been disclosed (see Patent Document 6). However, when printing on a non-water-absorbing recording medium such as a vinyl film using an aqueous pigment ink-jet ink, the recording medium does not have ink absorption capability, so that ink droplets coalesce to generate spots or have sufficient gloss. It has been found that there are issues that are difficult to obtain.
Japanese translation of PCT publication No. 2002-526631 JP 2005-15672 A Japanese Patent Laid-Open No. 2005-60716 JP 2005-36199 A WO2004 / 007626 pamphlet JP 2005-113147 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the inkjet ink for a non-water-absorbing recording medium that has high gloss, suppresses the occurrence of spots, and provides a high-quality image with excellent image fastness. And an ink jet recording method using the same.

  The above object of the present invention is achieved by the following configurations.

  1. A non-water-absorbing recording medium characterized by containing an organic solvent 1, a pigment, a polymer, and water that have a surface tension of 25 mN / m or more and 35 mN / m or less and that do not dissolve in water at an arbitrary ratio. Inkjet ink.

  2. 2. The non-water-absorbing recording medium according to 1 above, wherein the organic solvent 1 that does not dissolve in water in an arbitrary ratio is at least one organic solvent selected from glycol ethers, diols, and esters. Inkjet ink.

  3. 3. The non-water-absorbent recording according to 1 or 2 above, wherein the organic solvent 1 that does not dissolve in water at an arbitrary ratio has a solubility in water at 20 ° C. of 1% by mass or more and 20% by mass or less. Inkjet ink for medium.

  4). The organic solvent 1 that does not dissolve in water in any proportion is dipropylene glycol monopropyl ether, 2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, butyl lactate, 3-methoxybutyl acetate, diethylene glycol monobutyl ether acetate and dipropylene glycol monomethyl ether acetate 4. The inkjet ink for non-water-absorbing recording medium according to any one of 1 to 3, which is a seed.

  5). 5. The inkjet ink for non-water-absorbing recording medium according to any one of 1 to 4, wherein the organic solvent 2 further contains diethylene glycol monobutyl ether or triethylene glycol monobutyl ether.

  6). 6. The organic solvent 3 further comprises at least one selected from 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and γ-butyrolactone, Ink-jet ink for non-water-absorbing recording medium as described in 1.

  7. In an ink jet recording method for recording an image on a non-water-absorbing recording medium using an ink set composed of ink jet inks of one or more colors, all of the ink jet inks constituting the ink set are The ink jet ink for a non-water-absorbing recording medium according to claim 1, wherein at least one color ink-jet ink constituting the ink set is a light-color ink-jet ink and a dark-color ink-jet ink having the same pigment type and different pigment concentrations; And recording with the surface temperature of the non-water-absorbing recording medium on the recording surface side being heated to 35 ° C. or more and 80 ° C. or less.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an inkjet ink for a non-water-absorbing recording medium that has high gloss, suppresses the occurrence of spots, and provides a high-quality image with excellent image fastness, and an inkjet recording method using the same. It was.

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

  Conventionally, when printing on a non-water-absorbing recording medium such as a vinyl film using a water-based pigment ink-jet ink, the ink-jet ink penetrates and the recording medium has a high ink-absorbing ability such as a paper medium. Since there is no drying, the ink droplets that have landed on the recording medium are coalesced and it is difficult to generate spots or obtain sufficient gloss. In particular, when a recording medium having a low surface energy, such as a recording medium made of vinyl chloride, is used, the ink jet ink has low wettability with respect to the recording medium, and ink droplets are coalesced and spots are likely to occur. It was. In addition, the difference in image gloss between the portion printed with the light inkjet ink used for the purpose of reducing the graininess of dots in the highlight portion of the image to be formed and the portion printed with the dark inkjet ink tends to occur. The present inventors have found that there is a problem that uniform glossiness cannot be obtained as a whole print, and that a remarkable gloss difference is caused particularly in an ink-jet ink containing a polymer.

  As a result of intensive studies on the above problems, the surface tension is in the range of 25 mN / m or more and 35 mN / m or less, and contains at least an organic solvent 1, a pigment, a polymer, and water that do not dissolve in water at an arbitrary ratio. It has been found that when recording is performed on a non-water-absorbing recording medium using an ink jet ink characterized by the above, high-quality image with high gloss and suppressed occurrence of spots can be obtained. Furthermore, the present inventors have found that the difference in gloss between the portions printed with the dark color ink and the light color ink is reduced, and that a uniform gloss feeling can be obtained, and that the present invention has been achieved.

  About the effect acquired by using the inkjet ink of the structure prescribed | regulated by this invention, although it has not resulted in clear interpretation, it is guessed as follows.

  1. It is considered that the organic solvent 1 that does not dissolve in water at an arbitrary ratio, that is, the organic solvent having a relatively hydrophobic property, is less likely to be stably present in water, and thus is likely to be easily distributed at the gas-liquid interface. Therefore, even if the organic solvent has the same surface tension, the organic solvent 1 having a low water solubility is more effective on the surface of the ink droplet landed on the recording medium than the organic solvent having a high water solubility. As a result of the presence of the organic solvent at a high concentration, it is considered that the surface energy of the ink droplets is likely to be lowered and the ink droplets are difficult to coalesce, and as a result, the spots are reduced. Further, it is presumed that a uniform ink image without unevenness is formed due to wetting and spreading, and high gloss is obtained.

  2. Regarding the non-water-absorbing recording medium ink-jet ink of the present invention, the difference in gloss between the portions printed with the dark ink-jet ink and the light ink-jet ink is reduced, and a uniform gloss feeling can be obtained as follows. ing. In the process in which water and organic solvents are evaporated and concentrated after the ink-jet ink has landed on the recording medium, the viscosity of the dark-color ink-jet ink having a higher pigment concentration than that of the light-color ink-jet ink tends to increase. As a result, it is considered that there is a difference in gloss between dark inkjet ink and light inkjet ink as a result of a difference in leveling. The inkjet ink for a non-water-absorbing recording medium of the present invention levels immediately after landing on the recording medium, spreads quickly, and as a result, is less susceptible to leveling due to the difference in viscosity during the drying process, and the gloss difference is reduced. I guess. In addition, when a general water-absorbing recording medium is used for the water-based inkjet ink, since the ink penetrates into the recording medium at an earlier stage than the evaporation of the ink, it has an influence on the difference in viscosity between the dark and light inks generated at the time of evaporation and drying. The problem of gloss difference is less likely to occur.

  Hereinafter, the inkjet ink for non-water-absorbing recording medium of the present invention (hereinafter also simply referred to as ink) and the inkjet recording method will be specifically described.

  First, the details of the organic solvent 1 (hereinafter, also simply referred to as the organic solvent 1) that has a surface tension in the range of 25 mN / m to 35 mN / m and does not dissolve in water at an arbitrary ratio will be described. .

  The surface tension referred to in the present invention is a value measured at 25 ° C., and the surface tension of the organic solvent 1 according to the present invention is in the range of 25 to 35 mN / m, preferably 25 to 30 mN. / M range. By using the organic solvent 1 that has a surface tension in this range and does not dissolve in water at an arbitrary ratio, the gloss is high even in a non-water-absorbing medium, and the occurrence of spots can be significantly suppressed.

  In the present invention, as a method of measuring the surface tension defined in the present invention, it can be measured by a conventionally known measurement method such as a drop weight method, a capillary rise method, a ring method, a flat plate method, For example, it can be measured using an automatic surface tension meter CBVP-Z type manufactured by Kyowa Interface Chemical Co., Ltd.

  One feature of the organic solvent 1 according to the present invention is that it does not dissolve in water at an arbitrary ratio. In the present invention, “not dissolving in water at an arbitrary ratio” means that it does not have a property of freely dissolving in the whole range of 1 to 100% by mass with respect to water. More specifically, it is an organic solvent having a solubility in water in the range of 0.5 to 35.0% by mass at 20 ° C., and more preferably in the range of 1.0 to 20.0% by mass. An organic solvent. Furthermore, the preferable boiling point of the organic solvent 1 according to the present invention is 150 ° C. or higher, and more preferably, a solvent having a boiling point of 180 ° C. or higher is preferable from the viewpoint of easily developing gloss. Regarding this factor, it is considered that a smooth print surface is likely to be formed by preventing rapid drying after printing and producing a leveling effect.

  Specific examples of the organic solvent 1 according to the present invention are not particularly limited as long as the organic solvent 1 has the characteristics specified above, but preferably dipropylene glycol monopropyl ether, 2,2,4-trimethyl- 1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, butyl lactate, 3- Mention may be made of methoxybutyl acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate.

  In the ink of the present invention, the content of the organic solvent 1 according to the present invention is preferably 3 to 40% by mass, and more preferably 5 to 25% by mass.

  In the ink of the present invention, when the addition of the organic solvent is required more than the solubility of the organic solvent 1 according to the present invention in water or from the viewpoint of obtaining the dissolution stability of each additive at low temperature, In addition, it is also preferable to mix other organic solvents for the purpose of mixing with water.

  As another organic solvent, glycol ether mixed with water in an arbitrary ratio such as ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, etc. can be preferably used. In particular, as organic solvent 2, diethylene glycol monobutyl ether is used. Alternatively, triethylene glycol monobutyl ether is preferably contained.

  In addition to the organic solvent 1 and the organic solvent 2, a conventionally known organic solvent can be added as an auxiliary organic solvent to the ink of the present invention.

  Specific examples include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, etc.), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, Polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyl) Diethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, Ethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclic ring (Eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexyl pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone), lactones (eg, γ-butyrolactone, etc.), S Solvents (for example, dimethyl sulfoxide, sulfolane etc.) etc. are mentioned.

  In the ink of the present invention, a higher gloss improvement effect can be obtained by using the organic solvent 3 selected from 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide, and γ-butyrolactone. Was also found by the study of the present inventor.

  In addition, water, which is one of the constituent requirements of the ink of the present invention, is preferably contained in an amount of 50% by mass or more, more preferably 60% by mass or more, from the viewpoint of improving the balance between drying property and gloss.

  Next, the high molecular polymer applied to the ink of the present invention will be described.

  One feature of the ink of the present invention is that it contains a polymer from the viewpoint of obtaining scratch resistance of the ink film to be formed.

  The polymer according to the present invention is preferably used in the range of 0.5% by mass or more and 10.0% by mass or less as the content in the ink, more preferably 2.0% by mass or more and 7.0% by mass. If it is in the range of mass% or less, it is easy to achieve both scratch resistance and ejection stability.

  In the present invention, preferred polymer is a water-soluble copolymer having a hydrophobic monomer as a polymerization component or water-dispersed polymer fine particles from the viewpoint of obtaining image scratch resistance even in a high-humidity environment or when moisture adheres. It is preferable that

  Hereinafter, a water-soluble copolymer having a hydrophobic monomer as a polymerization component will be described.

  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 high-molecular 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.

  Examples of the hydrophobic monomer of the copolymer include acrylic acid ester (n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc.), methacrylic acid ester (ethyl methacrylate, butyl methacrylate, methacrylic acid). Glycidyl acid) 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. In this case, as the neutralizing base, alkali metal-containing bases such as sodium hydroxide and potassium hydroxide, and amines (for example, ammonia, alkanolamine, alkylamine, etc.) 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 a molecular weight of the copolymer, an average molecular weight of 3000 to 30000 can be used, and a more preferable molecular weight range is 7000 to 20000. Further, Tg of about -30 ° C to 100 ° C can be used, and a more preferable range of Tg is -10 ° C to 80 ° C.

  Next, water-dispersed polymer particles that are preferably used in addition to the water-soluble copolymer having the hydrophobic monomer as a polymerization component as the polymer polymer according to the present invention will be described.

  As the polymer fine particles, a dispersion polymerized in an aqueous system may be used as it is or may be treated, or a polymer polymerized in a solvent system may be dispersed in an aqueous system. For example, acrylic, urethane Styrene, vinyl acetate, vinylidene chloride, vinyl chloride, styrene-butadiene, styrene-acrylonitrile, polybutadiene, polyethylene, polyisobutylene, polyester, and the like.

  As the physical properties of the ink, it is preferable that there is no shear dependency on the viscosity. From this viewpoint, as a dispersion form of the polymer fine particles, an emulsifier such as a surfactant is made as low as possible, or a soap-free type dispersion polymer that does not use an emulsifier. Particles are preferred. A preferred aqueous dispersion polymer fine particle is a self-dispersion dispersion of a copolymer obtained by polymerizing unsaturated vinyl having a carboxyl group as at least a monomer component. For example, an acrylic monomer such as ethyl acrylate alone or an acrylic monomer is used. A dispersion obtained by emulsion polymerization or suspension polymerization of acrylic acid or maleic acid as a carboxylic acid monomer in a composition comprising an ethylenically unsaturated monomer copolymerizable with a monomer is mechanically swelled with an alkaline compound. An acrylic hydrosol obtained by dividing particles by shearing. Among acrylic hydrosols, it is preferable to contain styrene in the monomer composition from the viewpoint of increasing the refractive index of the resin and obtaining a high gloss feeling.

  Examples of the alkaline compound include ammonia, triethylamine, 2-dimethylaminoethanol, 2-di-n-butylaminoethanol, methyldiethanolamine, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, 2- An amine such as methylaminoethanol is preferable, and ammonia, 2-amino-2-methyl-1-propanol, and 2-methylaminoethanol are particularly preferable in terms of dispersion stability of the aqueous dispersion polymer fine particles.

  The acrylic hydrosol is commercially available, for example, as the John Crill series of Johnson Polymer Co., Ltd.

  The glass transition temperature Tg of the water-based dispersed polymer fine particles is preferably 35 ° C. or higher in order to improve the scratch resistance of the image, and more preferably 49 ° C. or higher. The upper limit of Tg is not particularly limited, but is preferably less than about 100 ° C. because a flexible ink film can be obtained and cracking of an image due to bending of a printed matter can be prevented.

  The acid value of the aqueous dispersion polymer fine particles is preferably 44 mgKOH / g or more, more preferably 60 mgKOH / g or more, from the viewpoint of obtaining good redispersion / solubility of the ink dry film. The upper limit of the acid value is not particularly limited, but is preferably less than 110 mgKOH / g from the viewpoint of easily obtaining a more stable dispersion.

  The average particle size of the water-dispersed polymer fine particles is preferably 300 nm or less, more preferably 130 nm or less from the viewpoint that the nozzle of the head is not clogged and a good gloss feeling is obtained. The lower limit of the average particle diameter is preferably 30 nm or more from the viewpoint of the production stability of the fine particles. The average particle diameter of the water-dispersed polymer fine particles can be easily measured using a commercially available measuring device using a light scattering method or a laser Doppler method. Alternatively, the dispersion of the aqueous dispersion polymer fine particles can be freeze-dried, and the average particle diameter can be converted from the particles observed with a transmission microscope.

  The content of the water-based dispersed polymer fine particles is preferably 0.5% or more and 6% or less, more preferably in the range of 1% or more and 3% or less. By adjusting the total amount to 1% or more and 10% or less, more preferably 3% or more and 6% or less, good fixability (abrasion resistance, alcohol resistance) and stable use even after long-term storage of the ink are possible. It is.

  The polymer according to the present invention can be added as a dispersion stabilizer when dispersing the pigment described later, but it is preferable to add it in the process of diluting the pigment dispersion from the viewpoint of ink storage stability, Furthermore, it is more preferable to add a high molecular polymer both at the time of pigment dispersion and at the time of dilution.

  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 present in a state of being dispersed in the ink, and this dispersion method may be any of self dispersion, dispersion using a surfactant, polymer dispersion, and microcapsule dispersion.

  The insoluble pigment is not particularly limited. 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 of the dispersed state of the pigment contained in the ink of the present invention 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 according to 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.

  In the ink jet recording method of the present invention, all the ink jet inks constituting the ink set are the ink jet inks for a non-water-absorbing recording medium of the present invention, and at least one color ink jet ink constituting the ink set has a pigment type. It is characterized by using an ink set composed of a light ink jet ink and a dark ink jet ink which are the same and have different pigment concentrations.

  In the ink set according to the present invention, at least one color ink is composed of two inks of the same color having different densities, that is, a light color ink jet ink and a dark color ink jet ink. It is more preferable to use an ink set composed of two inks of the same color having different densities. In particular, it is preferable to use an ink set composed of at least two inks of the same color having different densities in three or more inks.

  This is because by using a light color ink having a low pigment concentration, it is possible to reduce graininess and form a high-quality image without so-called “roughness”. In particular, it is preferable to use at least two inks having different densities in magenta ink or cyan ink having high human visibility.

  The pigment concentration ratio between the light-color ink jet ink and the dark ink-jet ink having different densities may be an arbitrary value. However, in order to perform smooth gradation reproduction, the ratio between the light ink and the dark ink (the light ink pigment) Density / pigment density of dark ink) is preferably between 0.1 and 1.0, more preferably between 0.2 and 0.5, and more preferably between 0.25 and 0.4. It is particularly preferred that it is between.

  As described above, the polymer according to the present invention can also be used as a pigment dispersant.

  When the polymer according to the present invention is used as a pigment dispersant, a polymer having a molecular weight of 5000 or more and 200000 or less is preferable.

  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, in this invention, it is preferable that it is 10-100 mass% with respect to a pigment as addition amount in the dispersion | distribution process in the case of using a high molecular polymer as a dispersing agent.

  As the pigment dispersion used in the present invention, a so-called capsule pigment in which the pigment is coated with a resin is also preferably used. 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 group 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 present invention, it is preferable to use a surfactant from the viewpoint of imparting higher wettability to the non-water-absorbing recording medium. In order to impart wettability, the surface tension of the ink is preferably 30 mN / m or less, and more preferably 28 mN / m or less.

  The surfactant that can be used in the present invention is not particularly limited as long as the surface tension of the ink can be adjusted to 30 mN / m or less, but an anionic compound is used as another component of the ink. In view of inclusion, the ionicity of the surfactant is preferably an anionic, nonionic or betaine type.

  In the present invention, a fluorine-based or silicon-based surfactant that preferably has a high ability to reduce static surface tension, an anionic surfactant such as dioctyl sulfosuccinate that has a high ability to reduce dynamic surface tension, and a relatively low Nonionic surfactants such as molecular weight polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, acetylene glycols, pluronic surfactants, and sorbitan derivatives are preferably used. It is also preferable to use a fluorine-based or silicon-based active agent in combination with a surfactant having a high ability to reduce the dynamic surface tension.

  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 such as polysaccharides, viscosity modifiers, specific resistance regulators, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, antifungal agents, rust preventives, etc. may be appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicon oil, ultraviolet absorbers described in JP-A-57-74193, 57-87988, and 62-261476, As described in Kaisho 57-74192, 57-87989, 60-72785, 61-146591, JP-A-1-95091 and 3-13376, etc. Anti-fading agents, fluorescent whitening agents described in JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266 Can be mentioned.

  The ink of the present invention having the above-described configuration preferably has an ink viscosity of 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and still more preferably 5 to 20 mPa · s. is there.

  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-water-absorbing medium such as a vinyl chloride sheet, which is the object of the present invention, but also for printing on plain paper, coated paper, ink jet dedicated paper, and the like.

  Examples of the non-water-absorbing recording medium include a polymer sheet, a board (soft vinyl chloride, hard vinyl chloride, acrylic plate, polyolefin, etc.), glass, tile, 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, S3 P, S27P (above, manufactured by Grafityp), P-223RW, P-224RW, P-249ZW, P-284ZC (above, 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 / R2, 445 / H14 / P3, 1438 / One Way Vision (manufactured by Inetrcoat), JT5129PM, JT5728P, JT5822P, JT5829P, JT5829R, JT5829PM, JT5829RM, JT5929PM (Impact, MP1100, MP1MP, MP1MP, MP1MP MPI2002, MPI3000, MPI3021, MPI3500, MPI3501 (above, manufactured by Avery), AM-101G, AM-501G (above, manufactured by Ginichi Co., Ltd.), FR2 (made by Hanwha Japan Co., Ltd.), AY-15P, AY- 60P, AY-80
P, DBSP137GGH, DBSP137GGL (manufactured by Insight Inc.), SJT-V200F, SJT-V400F-1 (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), VTL-HQ130 (manufactured by Lamy Corporation), SP300 GWF, SPCLEARAD vinyl (above, made by Catalina), RM-SJR (made by Ryoyo Corporation), Hi Lucky, New Lucky PVC (above, made by LG), SIY -110, SIY-310, SIY-320 (above, manufactured by Sekisui Chemical Co., Ltd.), PRINT MI Frontlit, PRINT XL Lightweight banner (above, manufactured by Endutex), RIJET 100, RIJET 145, RIJET165 (above, Ritrama Company) Manufactured), NM-SG, NM-SM (manufactured by Nichiei Kako Co., Ltd.), LTO3GS (manufactured by Lucio Co., Ltd.), Easy Print 80, Performance Print 80 (above, Jetgraph shares) Co. Inc.), DSE 550, DSB 550, DSE 800G, DSE 802/137, V250WG, V300WG, V350WG (manufactured by Hexis Ltd.), Digital White 6005PE, 6010PE (or include Multifix Corp.).

  In the inkjet recording method of the present invention, when an image is recorded on a non-water-absorbing recording medium using the ink set according to the present invention, the surface temperature on the recording surface side of the non-water-absorbing recording medium is 35 ° C. or higher. The recording is performed by heating to 80 ° C. or lower.

  Heating the non-water-absorbing recording medium is preferable from the viewpoint of significantly improving the drying and thickening speed of the ink, obtaining high image quality, and improving the durability of the formed image.

  The heating temperature of the non-water-absorbing recording medium is preferably 35 ° C. or higher, so that it is easy to obtain good image resistance and bleeding resistance and sufficient image durability, and the drying time can be shortened. When the temperature is not higher than ° C., it is possible to stably form an image without greatly affecting ink ejection. More preferably, the recording surface temperature of the non-water-absorbing recording medium is preferably heated to 35 ° C. or more and 60 ° C. or less.

  As a heating method of the non-water-absorbing recording medium, a heating heater is incorporated in the recording medium conveyance system or platen member of the ink jet recording apparatus, and the heating method is performed by contact from the back of the non-water-absorbing recording medium. The heating method can be selected without contact.

  When forming an image by ejecting the ink of the present invention, 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.

  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 ink set>
[Preparation of ink set 1]
(Preparation of cyan pigment dispersion)
As a polymer-type pigment dispersant, 5 parts of a styrene-acrylic acid copolymer (Johncrill 678, molecular weight 8500, acid value 215 mgKOH / g), 2.1 parts of dimethylaminoethanol, and 77.9 parts of ion-exchanged water at 70 ° C. The mixture was dissolved by stirring. The solution was then added to 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 the cyan pigment content was 15%. A liquid was prepared. The average particle diameter of the pigment particles contained in this cyan pigment dispersion was 122 nm. The particle size was measured using a Zetasizer 1000HS manufactured by Malvern.

(Synthesis of polymer)
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 stirrer, 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 an 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.

  Next, 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 polymer aqueous solution having a solid content of 20% was obtained by adjusting with ion exchange water.

(Preparation of ink set)
An ink set 1 comprising a dark ink 1 and a light ink 1 prepared by the following method was prepared,
<Preparation of dark ink 1>
As an organic solvent 1 that does not dissolve in water at an arbitrary ratio, dipropylene glycol monopropyl ether having a solubility in water at 20 ° C. of 19% was used, and after preparing the ink composition shown below, it was filtered with a 0.8 μm filter. Filtration gave dark ink 1. The obtained dark ink 1 had a viscosity measured at 25 ° C. of 9.3 mPa · s and a surface tension of 27.6 mN / m.

Cyan pigment dispersion 26.7% by mass
High polymer aqueous solution (solid content 20%) 15.0% by mass
Organic solvent 1: Dipropylene glycol monopropyl ether 15.0% by mass
Propylene glycol 2.5% by mass
Silicon-based surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass
Amount required for finishing to 100% by mass of ion-exchanged water <Preparation of light color ink 1>
In the preparation of the dark ink 1, the light ink 1 was obtained in the same manner except that the content of each additive was changed as follows. About the obtained light color ink 1, the viscosity measured on 25 degreeC conditions was 9.1 mPa * s, and the surface tension was 27.8 mN / m.

Cyan pigment dispersion 6.7% by mass
High polymer aqueous solution (solid content 20%) 20.0% by mass
Organic solvent 1: Dipropylene glycol monopropyl ether 15.0% by mass
Propylene glycol 7.9% by mass
Silicon-based surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass
Amount required for finishing to 100% by mass of ion-exchanged water [Preparation of ink sets 2-4, 12-14]
Ink sets 2 to 4 and 12 to 14 were prepared in the same manner as in preparing ink set 1 except that dipropylene glycol monopropyl ether, which is organic solvent 1, was changed to each organic solvent 1 shown in Table 1. did. The viscosity of each of the dark color inks 2 to 4 and 12 to 14 and the light color inks 2 to 4 and 12 to 14 constituting each ink set is propylene glycol so as to be in the range of 9.0 to 9.5 mPa · s. The addition concentration of was appropriately adjusted.

[Preparation of ink set 5]
<Preparation of dark ink 5>
As an organic solvent 1 that does not dissolve in water at an arbitrary ratio, 2,4-diethyl-1,5-pentanediol having a solubility in water of 1.9% at 20 ° C. was added, and the following additives were added. After the preparation, dark ink 5 was obtained by filtration through a 0.8 μm filter. The obtained dark ink 5 had a viscosity of 9.5 mPa · s and a surface tension of 27.4 mN / m as measured at 25 ° C. In addition, in the dark ink 5 described below, by using diethylene glycol monobutyl ether which is the organic solvent 2, it is possible to dissolve 2,4-diethyl-1,5-pentanediol which is the organic solvent 1 more than the solubility in water. did it.

Cyan pigment dispersion 26.7% by mass
High polymer aqueous solution (solid content 20%) 15.0% by mass
Organic solvent 1: 2,4-diethyl-1,5-pentanediol 5.0% by mass
Organic solvent 2: Diethylene glycol monobutyl ether 10.0% by mass
Propylene glycol 1.8% by mass
Silicon-based surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass
Amount required for finishing to 100% by mass of ion-exchanged water <Preparation of light ink 5>
In the preparation of the dark ink 5, the light ink 5 was obtained in the same manner except that the content of each additive was changed as follows. With respect to the obtained light-colored ink 5, the viscosity measured under the condition of 25 ° C. was 9.4 mPa · s, and the surface tension was 27.6 mN / m.

Cyan pigment dispersion 6.7% by mass
High polymer aqueous solution (solid content 20%) 20.0% by mass
Organic solvent 1: 2,4-diethyl-1,5-pentanediol 5.0% by mass
Organic solvent 2: Diethylene glycol monobutyl ether 10.0% by mass
Propylene glycol 5.8% by mass
Silicon-based surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass
Amount required for finishing to 100% by mass of ion-exchanged water [Preparation of ink sets 6, 8 to 11]
Ink sets 6 and 8 were prepared in the same manner as in the preparation of the ink set 5 except that 2,4-diethyl-1,5-pentanediol as the organic solvent 1 was changed to each organic solvent 1 shown in Table 1. ~ 11 were prepared. The viscosity of each of the dark inks 6 and 8 to 11 and the light inks 6 and 8 to 11 included in each ink set is set to a range of 9.0 to 9.5 mPa · s. Adjusted accordingly.

[Preparation of ink set 7]
An ink set was prepared in the same manner as in the preparation of the ink set 6 except that diethylene glycol monobutyl ether as the organic solvent 2 used in the dark color ink 6 and the light color ink 6 was changed to triethylene glycol monobutyl ether as the organic solvent 2. 7 was prepared. The addition concentration of propylene glycol was appropriately adjusted so that the viscosity of the dark ink 7 and the light ink 7 constituting the ink set 7 was in the range of 9.0 to 9.5 mPa · s.

[Preparation of ink set 15]
In the preparation of the ink set 1, the addition of propylene glycol was appropriately adjusted so that the viscosity of the ink was in the range of 9.0 to 9.5 mPa · s without adding the polymer aqueous solution of each ink. Similarly, an ink set 15 was prepared.

[Preparation of ink sets 16-18]
In the preparation of the ink set 1, the propylene glycol used for the preparation of the dark ink 1 and the light ink 1 is replaced with 1,3-dimethyl-2-imidazolidinone, sulfolane, and γ-butyrolactone, which are the same amount of the organic solvent 3. Ink sets 16 to 18 were prepared in the same manner except that each was changed to.

  Table 1 shows a list of main components of each ink set.

  In addition, the detail of each organic solvent described with the abbreviation in Table 1 is as follows.

[Organic solvent 1]
DPGMPE: Dipropylene glycol monopropyl ether (surface tension: 27.6 mN / m, solubility in water: 19% by mass)
DPGMMEAc: Dipropylene glycol monomethyl ether acetate (surface tension: 27.3 mN / m, solubility in water: 19% by mass)
DPGDME: Dipropylene glycol dimethyl ether (surface tension: 26.3 mN / m, solubility in water: 35% by mass)
MMP: 4-methoxy-4-methylpentane (solubility in water: 22% by mass)
DEPDO: 2,4-diethyl-1,5-pentadiol (surface tension: 34.0 mN / m, solubility in water: 1.9% by mass)
BL: Butyl lactate (surface tension: 30.6 mN / m, solubility in water: 4% by mass)
DEGMBEAc: Diethylene glycol monobutyl ether acetate (surface tension: 29.9 mN / m, solubility in water: 6.0% by mass)
EHDO: 2-ethyl-1,3-hexanediol (surface tension: 29.0 mN / m, solubility in water: 0.6% by mass)
MBAc: 3-methoxybutyl acetate (surface tension: 27.9 mN / m, solubility in water: 7.0% by mass)
PGPE: propylene glycol phenyl ether (surface tension: 38.1 mN / m, solubility in water: 1.0% by mass)
[Organic solvent 2]
DEGMBE: Diethylene glycol monobutyl ether (surface tension: 30.6 mN / m, solubility in water: almost ∞)
TEGMBE: triethylene glycol monobutyl ether (surface tension: 32.1 mN / m, solubility in water: almost ∞)
[Organic solvent 3]
DMID: 1,3-dimethyl-2-imidazolidinone butyrolactone: γ-butyrolactone [other organic solvents]
PGPE: propylene glycol phenyl ether (surface tension: 38.1 mN / m, solubility in water: 1.0% by mass)
MP: 1-methoxy-2-propanol (surface tension: 27.6 mN / m, solubility in water: almost ∞)
DEGDEE: Diethylene glycol diethyl ether (surface tension: 26.7 mN / m, solubility in water: almost ∞)
PG: propylene glycol (surface tension: 35.6 mN / m, solubility in water: almost ∞)
<Evaluation of ink set>
Each ink set prepared above was evaluated according to the following method. In addition, about the ink sets 1-18, the surface tension measured by the plate method on 25 degreeC conditions was the range of 27-28 mN / m.

[Image formation]
A piezo head with a nozzle diameter of 28 μm, a drive frequency of 18 kHz, a nozzle number of 512, a minimum liquid amount of 14 pl, and a nozzle density of 180 dpi was mounted, and each ink set was loaded into an on-demand inkjet printer with a maximum recording density of 1440 × 1440 dpi. .

  Next, each ink set was ejected onto a recording medium made of polyvinyl chloride, JT5929PM (manufactured by Mactac), at a printing resolution of 720 dpi × 720 dpi, a head conveyance speed of 250 mm / sec, under the conditions of bidirectional printing, A solid image of 10 cm × 10 cm was printed for each of the color ink and the light color ink to obtain a recorded image.

  During printing on a polyvinyl chloride recording medium, the recording medium is heated from the back by a flat panel heater installed on the platen so that the surface temperature of the recording medium during image recording is 45 ° C. The heater temperature was controlled. The surface temperature of the recording medium was measured using a non-contact thermometer (IT-530N type, manufactured by Horiba, Ltd.).

[Evaluation of recorded images]
Each of the formed recorded images was evaluated according to the following method.

(Evaluation of image clarity)
Each recorded image was measured for image clarity (gloss value C value%) at 60 degrees reflection and 2 mm optical comb with image clarity measuring device ICM-1DP (manufactured by Suga Test Instruments Co., Ltd.), and evaluation of image clarity according to the following criteria. Went.

A: C value% is 61 or more B: C value% is 55-60
Δ: C value% is 50 to 55
X: C value% is less than 50 In the above evaluation rank, ◎ to Δ were judged to be practically preferable ranks.

(Glossiness measurement)
About the solid image formed with the produced said dark color ink and the solid image formed with the light color ink, the glossiness was measured using the Nippon Denshoku Industries Co., Ltd. variable angle glossiness meter (VGS-1001DP). The incident and reflection angles were measured at 20 °.

(Evaluation of plaque resistance)
About each recorded image, the occurrence state of the spot was visually evaluated, and the spot resistance was evaluated according to the following criteria.

○: Spots are not observed at all, and the quality is good. △: Spots are partially seen, but in a practical range. ×: Spots are generated on the entire surface, and the quality is outside the acceptable range for practical use. Yes (Evaluation of scratch resistance)
The surface of each recorded image was rubbed with dry cotton (Kanakin No. 3), and scratch resistance was evaluated according to the following criteria.

A: The image hardly changes even after rubbing 50 times or more. ○: Scratches remain slightly after rubbing 50 times, but the image density is hardly affected. Δ: The image density decreases during rubbing 20 to 50 times. : Image density decreases while rubbing less than 20 times In the above evaluation ranks, Δ to ◎ were judged to be practically preferred ranks.

  Table 2 shows the results obtained as described above.

  As is clear from the results shown in Table 2, ink sets 1 to 10 and 16 to 18 that satisfy the requirements of the present invention showed good results in all the evaluation items. On the other hand, an ink set 11 in which the surface tension of a solvent that does not dissolve in water at an arbitrary ratio is higher than 35 mN / m, an ink set 12 to 14 that contains only a solvent that dissolves in water at an arbitrary ratio, and an ink set that does not contain a polymer. It can be seen that No. 15 has practically unacceptable characteristics for any of the evaluation items.

Example 2
In the preparation of ink sets 1 to 14 and 16 to 18 described in Example 1, Superflex 300, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin fine particles, acrylic emulsion as polymer fine particles having the same mass instead of the polymer polymer Ink sets 1B to 14B, 16B to 18B, and ink sets 1C to 14C, and 16C to 18C were prepared in the same manner except that each was changed to (Tg <5 ° C., average particle size 80 nm).

  As a result of performing each evaluation in the same manner as in the method described in Example 1 using these ink sets, an image formed by the ink set of the present invention has the same effect as the results described in Table 2. We were able to confirm that

Claims (7)

A non-water-absorbing recording medium characterized by containing an organic solvent 1, a pigment, a polymer, and water that have a surface tension of 25 mN / m or more and 35 mN / m or less and that do not dissolve in water at an arbitrary ratio. Inkjet ink. 2. The non-water-absorbent recording according to claim 1, wherein the organic solvent 1 that does not dissolve in water in an arbitrary ratio is at least one organic solvent selected from glycol ethers, diols, and esters. Inkjet ink for medium. The non-water-absorbing property according to claim 1 or 2, wherein the organic solvent 1 that does not dissolve in water in an arbitrary ratio has a solubility in water at 20 ° C of 1% by mass or more and 20% by mass or less. Inkjet ink for recording media. The organic solvent 1 that does not dissolve in water in any proportion is dipropylene glycol monopropyl ether, 2,2,4-trimethyl-1,3-pentanediol, 2-butyl-2-ethyl-1,3-propanediol 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, butyl lactate, 3-methoxybutyl acetate, diethylene glycol monobutyl ether acetate and dipropylene glycol monomethyl ether acetate The inkjet ink for non-water-absorbing recording medium according to any one of claims 1 to 3, wherein the inkjet ink is a seed. The ink-jet ink for non-water-absorbing recording media according to any one of claims 1 to 4, further comprising diethylene glycol monobutyl ether or triethylene glycol monobutyl ether as the organic solvent 2. The organic solvent 3 further contains at least one selected from 1,3-dimethyl-2-imidazolidinone, sulfolane, dimethyl sulfoxide and γ-butyrolactone. Item 10. An ink-jet ink for a non-water-absorbing recording medium according to Item. In an ink jet recording method for recording an image on a non-water-absorbing recording medium using an ink set composed of one or more ink-jet inks, all the ink-jet inks constituting the ink set are any one of claims 1 to 6. The inkjet ink for a non-water-absorbing recording medium according to Item 1, wherein at least one of the inkjet inks constituting the ink set is a light inkjet ink and a dark inkjet ink having the same pigment type and different pigment concentrations. An ink jet recording method comprising: recording with a surface temperature on the recording surface side of the non-water-absorbing recording medium being heated to 35 ° C. or more and 80 ° C. or less.