JP2017109412A - Inkjet recording method and recording liquid set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording method and a recording liquid set which are excellent in ink discharging stability and can prevent bleeding and cracking of an ink coating film when printing is performed on a recording medium comprising a film base material by an inkjet method.SOLUTION: There is provided an inkjet recording method of printing an ink containing at least a pigment, a pigment dispersant, water, a pigment dispersant and a surfactant on a recording medium having a coating layer obtained by coating a coating liquid containing at least a resin and a pigment coagulant on a film base material by an inkjet method, where at least a water-soluble resin dispersant (A) which is dissolved in water and a water-soluble resin dispersant (B) which is not dissolved in water and obtained by alkali neutralization of an anionic group are used in combination as the pigment dispersant.SELECTED DRAWING: None

Description

  The present invention relates to an ink jet recording method and a recording liquid set. More specifically, when printing on a recording medium composed of a film substrate by an ink jet method, the ink discharge stability is excellent, and further, ink film blurring and cracking are prevented. The present invention relates to an ink jet recording method and a recording liquid set.

  When printing on a recording medium composed of a film substrate by an ink jet method, it is difficult to fix the pigment on the recording medium, unlike when an ink-absorbing recording medium such as paper is used.

  Patent Document 1 discloses that two types of inks constituting an ink set are ink-jetted in order to obtain a printed matter that is excellent in abrasion resistance immediately after printing even when printing on a film substrate. It is disclosed that it is applied onto a film substrate by the method, and the components derived from the respective inks are aggregated and quickly fixed.

Japanese Patent No. 5500410

  However, when the ink set disclosed in Patent Document 1 is used, when ink-jet printing is performed on a recording medium made of a film substrate, both ink film bleeding and cracking are prevented while maintaining ink ejection stability. I can't do it.

  Accordingly, an object of the present invention is to provide an ink jet recording method and a recording liquid set which are excellent in ink ejection stability when printing on a recording medium comprising a film base material by an ink jet method, and which can further prevent bleeding and cracking of an ink coating film. Is to provide.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

1.
Ink-jet ink containing at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant is applied to a recording medium having a coating layer formed by applying a coating liquid containing at least a resin and a pigment flocculant on a film substrate. An inkjet recording method for printing by a method,
As the pigment dispersant, at least a water-soluble resin dispersant (A) that dissolves in an acid and a water-soluble resin dispersant (B) that does not dissolve in an acid and alkali neutralizes an anionic group are used in combination. An ink jet recording method.
2.
The pigment flocculant includes an acid having a first dissociation constant of 3.5 or less,
2. The ink jet recording method according to 1 above, wherein the pH of the coating solution is less than a first dissociation constant of the acid.
3.
3. The ink jet recording method according to 1 or 2, wherein the resin dispersant (A) and the resin dispersant (B) satisfy the relationship of the following formula (1) in the ink.
25 <(X _A · M _A + X _B · M _B ) / (M _A + M _B ) <65 (1)
(Wherein, _{X A} and _{X B} each represent the acid value of the resin dispersant (A) and the resin dispersant (B) [mgKOH / g] , M A and _{M B} are respectively the resin dispersant (It represents the content [% by mass] of (A) and the resin dispersant (B) with respect to the total amount of the ink.)
4).
The resin dispersant (A) has a nonionic water-soluble group,
4. The ink jet recording method according to any one of 1 to 3, wherein the resin dispersant (B) has an alkali-neutralized carboxyl group.
5).
The ink contains at least glycols and / or glycol ethers as the water-soluble organic solvent, and the content of glycols and / or glycol ethers is 10% by mass or more and 40% by mass or less based on the total mass of the ink. The inkjet recording method according to any one of 1 to 4, wherein the inkjet recording method is in a range.
6).
6. The ink jet recording method according to any one of 1 to 5, wherein the resin contained in the coating liquid is a cationic or nonionic resin having a polyurethane structure.
7).
A recording liquid set comprising the following [I] and [II].
[I] A coating liquid containing at least a resin and a pigment flocculant [II] containing at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant,
As the pigment dispersant, at least a water-soluble resin dispersant (A) that dissolves in an acid and a water-soluble resin dispersant (B) that does not dissolve in an acid and alkali neutralizes an anionic group are used in combination. Inkjet ink

  According to the present invention, there is provided an ink jet recording method and a recording liquid set that are excellent in ink ejection stability when printing on a recording medium comprising a film base material by an ink jet method, and that can simultaneously prevent bleeding and cracking of an ink coating film. Can be provided.

  Below, the form for implementing this invention is demonstrated.

  The ink jet recording method of the present invention can be suitably used when printing on a recording medium comprising a film substrate by an ink jet method.

  The recording medium is formed by applying a coating liquid containing at least a resin and a pigment flocculant on a film substrate.

  On such a recording medium, an ink (also referred to as an inkjet ink) containing at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant is printed by an inkjet method.

  In the present invention, as the pigment dispersant of the ink, a water-soluble resin dispersant (A) that dissolves in an acid, and a water-soluble resin dispersant (A that does not dissolve in an acid and alkali neutralizes an anionic group) One feature is that at least B) is used in combination.

  Thereby, when printing on the recording medium which consists of a film base material by the inkjet method, it is excellent in ink discharge stability, and also the effect of being able to achieve both prevention of bleeding and cracking of the ink coating film is obtained.

  Further, since the recording liquid set of the present invention is composed of the above-described coating liquid and inkjet ink, as described above, when printing on a recording medium composed of a film substrate by the inkjet method, ink ejection stability is achieved. In addition, an effect of achieving both prevention of ink film bleeding and cracking can be obtained.

  Below, the form for implementing this invention is demonstrated in more detail.

<Recording medium and coating solution>
First, a recording medium to be printed by the ink jet method is prepared. The recording medium has a coating layer formed by applying a coating liquid containing at least a resin and a pigment flocculant on a film substrate.

  The resin constituting the film substrate is not particularly limited, but preferred examples include plastics such as polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate, polyamides such as nylon, and the like. The film substrate may be either an unstretched film or a stretched film. As the film substrate, a non-ink-absorbing or slightly absorbing ink can be suitably used. The surface of the film substrate may be subjected to surface treatment such as corona treatment.

  The coating liquid applied on such a film substrate contains at least a resin and a pigment flocculant.

  The resin is not particularly limited, but a cationic or nonionic resin can be preferably used from the viewpoint of improving the dispersibility of the pigment flocculant. As such a resin, for example, a cationic or nonionic resin having a polyurethane structure, a cationic or nonionic resin having a polyolefin structure such as polypropylene can be preferably exemplified, and in particular, a cation having a polyurethane structure. Or nonionic resins are preferred.

  Cationic or nonionic resins having a polyurethane structure are excellent in adhesion to the film substrate, and also exhibit the flexibility to follow the deformation of the film substrate. Furthermore, it is excellent in affinity for ink applied at the time of printing by the ink jet method, and the effect of preventing cracks can be further improved.

  Specific examples of the cationic or nonionic resin having a polyurethane structure are given below. Examples of cationic resins include “Superflex 620” and “Superflex 650” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (“Superflex” is a registered trademark of the company), “Permarin UC-20” manufactured by Sanyo Chemical Industries, Ltd. ("Permarin" is a registered trademark of the company), "Parasurf UP-22" manufactured by Ohara Palladium Chemical Co., Ltd., and nonionic resin fine particles include "Superflex 500M" and "Super Flex E-2000 "can be mentioned.

  The resin is preferably contained in the coating liquid as resin fine particles. The average particle diameter of the resin fine particles is preferably in the range of 10 nm to 10 μm. The average particle size can be measured by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, etc., but the measurement by the dynamic light scattering method is simple and the particle size region is Accurate measurement.

  The content of the resin in the coating solution is preferably in the range of 5% by mass to 40% by mass with respect to the mass of the coating solution, and more preferably in the range of 10% by mass to 30% by mass.

  The pigment flocculant is not particularly limited as long as it can agglomerate the pigment in the ink applied by the ink jet method, and preferred examples include acid, acidic polymer, polyvalent metal salt, and cationic polymer.

  The acid causes aggregation and thickening of the resin in the ink due to pH fluctuation, and can aggregate the pigment. Examples of the acid include formic acid, acetic acid, propionic acid, isobutyric acid, oxalic acid, fumaric acid, malic acid, citric acid, malonic acid, succinic acid, maleic acid, benzoic acid, 2-pyrrolidone-5-carboxylic acid, and lactic acid. Acrylic acid or a derivative thereof, methacrylic acid or a derivative thereof, acrylamide or a derivative thereof, a sulfonic acid derivative, phosphoric acid or a derivative thereof can be preferably exemplified. As the acid, an organic acid can be preferably used rather than an inorganic acid. By using an organic acid, compatibility with other components such as a resin constituting the coating liquid can be improved. Further, even when the coating layer formed by the coating liquid is dried, it does not easily become a salt. Excellent effects can also be obtained.

  Preferable examples of the acidic polymer include polyacrylic acid or derivatives thereof, polymethacrylic acid or derivatives thereof, polyacrylamide or derivatives thereof, polysulfonic acid or derivatives thereof, polyphosphoric acid or derivatives thereof, and the like.

  The acid and acidic polymer may be neutralized, but those that are unneutralized or partially neutralized can be used more preferably.

  The polyvalent metal salt can cause aggregation of a resin or the like in the ink by salting out to aggregate the pigment. Preferred examples of the polyvalent metal salt include water-soluble salts such as calcium salts, magnesium salts, aluminum salts, and zinc salts.

  Similar to the polyvalent metal salt, the cationic polymer can cause aggregation of the resin in the ink by salting out and aggregate the pigment. As the cationic polymer, a polymer having a primary to quaternary amine can be preferably used. The cationic polymer may be neutralized or not neutralized. The cationic polymer can be obtained as a commercial product, and examples thereof include “polyallylamine” manufactured by Nittobo Medical Co., Ltd.

  Among the aggregating agents described above, in particular, acids and polyvalent metal salts have a relatively low molecular weight, and thus easily diffuse into the ink. Therefore, acids and polyvalent metal salts are particularly preferable from the viewpoint of improving the aggregation rate, and acids are most preferable from the viewpoint of safety and compatibility with other components constituting the coating layer.

When an acid is contained in the coating liquid as a pigment flocculant, the pH of the coating liquid is preferably less than the first dissociation constant (pK _a1 ) of the acid. The first dissociation constant of the acid is preferably 3.5 or less. Thereby, the effect of the present invention is further remarkably exhibited.

  The coating solution can contain a solvent. Although a solvent is not specifically limited, For example, water, an organic solvent, etc. can be used. The solvent can be removed by drying after coating.

  The coating solution can contain a surfactant. Thereby, the adaptability to various application methods can be improved.

  In the coating solution, other components such as a crosslinking agent, an antifungal agent, and a bactericidal agent can be appropriately blended as long as the effects of the present invention are not impaired.

The weight ratio of the resin and the pigment flocculant in the coating layer formed by application of the coating liquid can be appropriately set. For example, when the pigment flocculant is an acid, the resin content is 100% by mass. In this case, the content of the pigment flocculant is preferably in the range of 5% by mass to 40% by mass, and more preferably in the range of 10% by mass to 25% by mass. As the amount with the pigment aggregating agent in the coating ^layer, it is preferably in the range of 0.1g ^{/ m 2} ~1g ^/ m 2 in the range of 0.03g / ^{m 2} ~1.5g / m 2 More preferably. As a result, good cohesiveness can be exhibited, image disturbance can be prevented, and the printed matter can be improved in abrasion resistance and water resistance, and precipitation on the coating layer can also be prevented. It is preferable to adjust the composition of the coating solution so that the content of the resin and the pigment flocculant is in the above range.

  Although the coating method of the coating liquid on a film base material is not specifically limited, For example, a roller coating method, a curtain coating method, a spray coating method, an inkjet method etc. can be mentioned preferably.

  By applying the coating solution on the film substrate, a recording medium provided with a coating layer containing at least a resin and a pigment flocculant is obtained.

  Although the thickness of the coating layer after drying is not specifically limited, For example, it is preferable that it is the range of 0.1 micrometer or more and 4 micrometers or less. Thereby, it can prevent suitably that the texture of a film base material changes, and a sufficient quantity of pigment flocculants can be contained in this coating layer.

<Ink>
Next, ink (also referred to as inkjet ink) used when printing on a recording medium by an inkjet method will be described.

  The ink includes at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant.

  In the present invention, when printing on a recording medium comprising a film substrate by an ink jet method, it is excellent in ink ejection stability, and is further included in the ink in order to obtain an effect capable of both preventing bleeding and cracking of the ink coating film. As a pigment dispersant for dispersing a pigment to be dispersed, a water-soluble resin dispersant (A) that dissolves in an acid, and a water-soluble resin dispersant (B that does not dissolve in an acid and alkali neutralizes an anionic group) ) At least. The above effect is not exhibited by the single use of the resin dispersant (A) or the resin dispersant (B), but is synergistically exhibited by using these in combination. This point will be described in detail below.

  In the present invention, the pigment is dispersed in the ink in order to obtain ink ejection stability in the ink jet method. On the other hand, after the ink has landed on the recording medium composed of the film base material, the pigment is aggregated on the recording medium in order to fix the pigment. That is, at the time of printing, the pigment in the ink is shifted from the dispersed state to the aggregated state.

  Electric charges can be used to shift the pigment in the ink from the dispersed state to the aggregated state. That is, as a pigment dispersant for dispersing the pigment, a water-soluble resin dispersant (B) that does not dissolve in an acid but is obtained by neutralizing an anionic group with an alkali is used to make it dissociated in water-based ink. The pigment can be dispersed by repulsion between charges (negative charges) of a certain anionic group. At the time of printing, the repulsion due to the charge can be reduced and the pigment can be aggregated by binding a cation such as a proton from the pigment aggregating agent on the recording medium to the anionic group of the resin dispersant (B). .

  However, when only the water-soluble resin dispersant (B) formed by alkali neutralization of an anionic group without dissolving in an acid is used and the aggregation mechanism utilizing such charges is used, the ink coating film is prevented from cracking. There are limits. This cause is considered to be caused by cracking because the cohesive force is too strong. In particular, a recording medium composed of a film substrate is unlikely to absorb ink unlike an ink-absorbing recording medium such as paper. Therefore, the ink applied on the recording medium constituted by the film base material remains on the surface of the recording medium. If a strong cohesive force acts on the pigment in the ink in this state, the ink coating film is distorted and cracks are likely to occur. In an ink-absorbing recording medium, such cracks are not observed because the ink is absorbed into the recording medium. Such a crack is a phenomenon peculiar to a recording medium constituted by a film base material.

  In order to prevent cracking of the ink coating film due to strong cohesive force, it is also conceivable to reduce the anionic group of the resin dispersant (B) or reduce the pigment coagulant. However, from the viewpoint of obtaining the dispersibility of the pigment, there is a limit to reducing the anionic group of the resin dispersant (B). In addition, the amount of ink applied to the recording medium may vary depending on printing conditions and the like (for example, in color printing, the amount of ink applied reaches 300% in total for each color). There is a limit to reducing the pigment flocculant.

  In addition, the resin dispersant (A) alone has a property of dispersing the pigment, but it is difficult to aggregate with the pigment flocculant. Therefore, there is a limit in fixing the pigment on the recording medium constituted by the film base material.

  Therefore, in the present invention, a water-soluble resin dispersant (A) that dissolves in an acid and a water-soluble resin dispersant (B) that does not dissolve in an acid and alkali neutralizes an anionic group are used in combination. Thereby, first, the repulsion due to the charge of the resin dispersant (B) is rapidly reduced by the pigment flocculant, so that the pigment agglomerates rapidly and the ink coating can be suitably prevented from bleeding. On the other hand, unlike the resin dispersant (B), the resin dispersant (A) is not easily affected by the pigment flocculant and tries to maintain the function of dispersing the pigment. As a result, the cohesive force as a whole is relaxed, and cracking of the ink coating film is suitably prevented. That is, by using the resin dispersant (A) and the resin dispersant (B) in combination, “rapid aggregation” can be caused by “relaxed aggregation force”, and both ink film bleeding and cracking prevention can be achieved. Is possible.

  Both the resin dispersant (A) and the resin dispersant (B) exhibit a function of dispersing the pigment until the ink is applied to the recording medium. Therefore, the pigment can be fixed to the recording medium while maintaining the ink ejection stability.

  As described above, when the resin dispersant (A) and the resin dispersant (B) are used in combination, the ink discharge stability is excellent when ink-jet printing is performed on a recording medium composed of a film base material, and the ink coating film is further blurred. The effect of achieving both prevention and crack prevention can be obtained.

  Furthermore, since the above effect is suitably exhibited even when the amount of the pigment flocculant previously applied to the recording medium is increased, the amount of the pigment flocculant can be set with a high degree of freedom in accordance with the printing conditions. Can also be obtained.

  Hereinafter, each of the resin dispersant (A) and the resin dispersant (B) will be described in more detail.

  As the resin dispersant (A), a water-soluble resin that dissolves in an acid is used. That the resin dispersant (A) is “soluble in an acid” means that the resin dispersant (A) is dissolved in water of pH 5 by 10% by mass or more.

  The resin dispersant (A) preferably has a nonionic water-soluble group. By having a nonionic water-soluble group, the solubility in an acid is suitably exhibited, and the water-soluble property is stably exhibited even after the pigment flocculant is allowed to act. Therefore, it is based on the resin dispersant (B) described above. The strong cohesive force is preferably relaxed, and cracking of the ink coating film is more preferably prevented. The nonionic water-soluble group is not particularly limited, but preferred examples include a hydroxyl group and an alkyleneoxy group.

  Specific examples of the resin dispersant (A) include DISPERBYK-190, DISPERBYK-193, DISPERBYK-2015 (above, manufactured by BYK Chemie), EFKA-4585 (manufactured by BASF), and the like.

  The resin dispersant (B) has water solubility by having an anionic group neutralized with alkali, but has a property of not dissolving in an acid.

  Specific examples of the resin dispersant (B) include resins obtained by neutralizing an acrylic polymer such as Joncrill 586 and Joncrill 819 (above, manufactured by BASF) with an alkali.

  “The resin dispersant (B) has water solubility but does not dissolve in acid” means that it is 10% by mass or more in pH 7 water, but its solubility in water at pH 5 is less than 10% by mass. To do.

  The resin dispersant (B) is preferably dissolved in the ink before being applied to the recording medium, but not dissolved in the ink after being applied to the recording medium. That is, it is preferable that the solubility is lost by binding a cation such as a proton from the pigment flocculant of the recording medium to an anionic group that has been dissociated in the ink before being applied to the recording medium. Thereby, rapid aggregation of the pigment can be suitably realized.

  Preferred examples of the alkali-neutralized anionic group contained in the resin dispersant (B) include an alkali-neutralized carboxyl group, sulfonic acid group, etc., and quick aggregation particularly when a pigment flocculant is acted on. From the viewpoint of realizing the above, an alkali neutralized carboxyl group is preferable.

  Examples of the alkali that neutralizes the anionic group include metal base compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide, organic amines such as ammonia, triethylamine, pyridine, morpholine, and monoethanolamine. Preferred examples include alkanolamines such as

  The acid value [mgKOH / g] of the resin dispersant (B) is preferably in the range of 70 to 200.

  In the ink, the resin dispersant (A) and the resin dispersant (B) preferably satisfy the relationship of the following formula (1).

25 <(X _A · M _A + X _B · M _B ) / (M _A + M _B ) <65 (1)

(Wherein, _{X A} and _{X B} each represent a resin dispersant (A) and resin dispersant acid value of (B) [mgKOH / g] , M A and _{M B} are respectively the resin dispersant (A) And the content [% by mass] of the resin dispersant (B) relative to the total amount of ink.

In the following description, the value of the side “(X _A · M _A + X _B · M _B ) / (M _A + M _B )” in the above formula (1) may be referred to as an X _AB value.

When the resin dispersant (A) and the resin dispersant (B) satisfy the relationship of the above formula (1) in the ink, the pigment can be fixed to the recording medium while maintaining the ink ejection stability. Further, the pigment flocculant can act on the pigment dispersant (B) to rapidly aggregate the pigment and to relieve excessive cohesive force due to the pigment dispersant (A) in a more preferable balance. It is possible to more suitably achieve both prevention of ink film bleeding and cracking. When the X _AB value is larger than 25, the bleeding prevention property is remarkably improved, and when the X _AB value is smaller than 65, the crack prevention property is remarkably improved.

  The total content of the resin dispersant (A) and the resin dispersant (B) in the ink is preferably in the range of 10% by mass to 100% by mass when the pigment content is 100% by mass, More preferably, it is in the range of 10% by mass to 50% by mass.

  As the pigment to be included in the ink, 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, or oxidation pigments can be used. Inorganic pigments such as titanium and carbon black can be preferably used. These pigments can be used in the state of being dispersed in the ink by the above-described pigment dispersant.

  The insoluble pigment is not particularly limited. , Diketopyrrolopyrrole and the like are preferable.

  Although an organic pigment is not specifically limited, For example, the following can be illustrated preferably.

  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. Pigment yellow 138, C.I. I. And CI Pigment Yellow 155.

  Examples of green or cyan pigments 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 in the ink is preferably in the range of 50 nm to 200 nm. Thereby, the dispersion stability of the pigment can be improved, and the storage stability of the ink can be improved. The particle size of the pigment can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, etc., but the measurement by the dynamic light scattering method is simple and the particle size region is Accurate measurement.

  The pigment can be used after being dispersed by a disperser together with a pigment dispersant and other additives necessary for various desired purposes.

  As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. Among them, it is preferable to disperse the pigment by a sand mill because the particle size distribution becomes sharp. The material of the beads used for sand mill dispersion is not particularly limited, but zirconia or zircon is preferable from the viewpoint of preventing generation of bead fragments and contamination of ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

  Although the content of the pigment in the ink is not particularly limited, for example, the inorganic pigment is preferably in the range of 7% by mass to 18% by mass, and the organic pigment is in the range of 0.5% by mass to 7% by mass. It is preferable.

  Preferable examples of the water-soluble organic solvent contained in the ink include monohydric alcohols, glycols (dihydric alcohols), trihydric alcohols, glycol ethers, acetates, amines, amides and the like.

  Preferred examples of monohydric alcohols include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, and tertiary butanol.

  Examples of glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having 5 or more ethylene oxide groups, propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, and propylene oxide groups. Polypropylene glycol, butylene glycol, thiodiglycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,2-hexanediol 1,2-heptanediol, 3-methyl-2,4-pentanediol and the like can be preferably exemplified.

  Preferred examples of the trihydric alcohols include glycerin and hexanetriol.

  Examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, Triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene Glycol monoethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol Preferred examples include dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, and tripropylene glycol dibutyl ether.

  Preferred examples of acetates include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol diacetate.

  Examples of amines include ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, Preferred examples include pentamethyldiethylenetriamine and tetramethylpropylenediamine.

  Preferred examples of amides include 2-pyrrolidinone, dimethylimidazolidinone, formamide, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

  These solvents may be used alone or in combination of two or more.

  In the present invention, it is particularly preferable to contain at least glycols or glycol ethers as the water-soluble organic solvent. Thereby, the ink discharge stability in the inkjet method can be further improved.

  The total content of glycols and glycol ethers in the ink is preferably in the range of 10% by mass to 40% by mass with respect to the total mass of the ink. As a result, the ink ejection stability can be improved, and further, the drying of the ink after being applied onto the recording medium proceeds suitably, and the ink film can be more suitably prevented from bleeding and cracking.

  The ink preferably contains a surfactant in order to improve dischargeability and wettability. The surfactant is not particularly limited, and examples thereof include a cationic surfactant, an anionic surfactant, an amphoteric surfactant, and a nonionic surfactant.

  Preferred examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like.

  Examples of the anionic surfactant include fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acyl glutamate, acylated peptide, alkyl sulfonic acid Salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl sulfoacetate, α-olefin sulfonate, N-acylmethyl taurine, sulfated oil, higher alcohol sulfate, secondary Higher alcohol sulfate, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate, polyoxyethylene alkylphenyl ether sulfate, monoglyculate, fatty acid alkylolamide sulfate, alkyl ether phosphate, alkyl Preferred examples include acid ester salts.

  Preferred examples of the amphoteric surfactant include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine and the like.

  Nonionic surfactants include, for example, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene glycerin. Fatty acid ester, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide , Polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxy Id, acetylene glycol, acetylene alcohol can be preferably exemplified.

  From the viewpoint of reducing the surface tension, it is preferable that some of these surfactants are substituted with fluorine atoms or silicon atoms.

  These surfactants may be used individually by 1 type, and may use multiple types together. The content of the surfactant in the ink is not particularly limited, but is preferably in the range of 0.1% by mass to 5.0% by mass.

  Other components can be appropriately blended in the ink as long as the effects of the present invention are not impaired.

<Inkjet method>
The ink jet method used when applying the ink described above to the recording medium is not particularly limited, and a printer including an ink jet head loaded with ink can be used. Specifically, it is possible to perform printing by ejecting ink as droplets from the nozzles of an inkjet head based on digital signals and landing them on a coating layer of a recording medium.

  The ink jet head may be either an on-demand system or a continuous system. As an inkjet head droplet 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, any system such as a thermal ink jet type or a bubble jet (registered trademark) type may be used.

  In particular, an ink jet head (also referred to as a piezo ink jet head) using a piezoelectric element as the electro-mechanical conversion element used in the electro-mechanical conversion system is suitable.

  In view of the fact that many common films are distributed in roll form, it is preferable to use a one-pass type ink jet recording method. The effect of the present invention is particularly remarkable in the one-pass type ink jet recording method. That is, when the one-pass ink jet recording method is used, the above-described cracks are likely to occur. However, according to the present invention, a high-definition image can be formed even in such a case.

  The one-pass ink jet recording method is a method in which when a recording medium passes under one ink jet head unit, ink droplets are applied to all pixels where dots are to be formed in one pass.

  As a means for achieving the one-pass type ink jet recording method, it is preferable to use a line head type ink jet head.

  The line head type ink jet head refers to an ink jet head having a length longer than the width of the printing range. As the line head type ink jet head, a single head having a width larger than the print range may be used, or a plurality of heads may be combined so as to be larger than the width of the print range.

  It is also preferable to arrange a plurality of heads side by side so that the nozzles are arranged in a staggered arrangement, thereby increasing the resolution of the heads as a whole.

  In the one-pass type ink jet recording method or the ink jet recording method using an ink jet head in which a plurality of heads are arranged in parallel to increase the resolution, the amount of ink applied on the recording medium tends to be relatively large. According to the invention, even in such a case, the effect of preventing bleeding and cracking is exhibited, and the effect of forming a high-definition image is obtained.

  The ink jet recording method of the present invention can be suitably used for various applications for printing on a recording medium comprising a film substrate by an ink jet method. The use of the recording medium on which printing is performed by the inkjet recording method of the present invention is not particularly limited. As a specific example of the use of the printed recording medium, for example, a packaging film for packaging food, beverages and the like can be preferably exemplified.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
1. Preparation of coating solution <Coating solution 1>
Resin-1 as described below is 76.9% by mass, malonic acid (first dissociation constant pK _a1 = 2.8) is 4.0% by mass, and ion-exchanged water (residual amount; coating solution total amount is ₁ %) Were added sequentially with stirring, and then filtered through a 5.0 μm filter to obtain coating solution 1. There was no substantial change in composition before and after filtration. The composition and pH of the coating solution 1 are as shown in Table 1.

Resin-1: Cationic resin having a polyurethane structure (emulsion of cationic carbonate polyurethane resin fine particles; “Superflex 650” manufactured by Daiichi Kogyo Seiyaku Co., Ltd .; resin solid content 20% by mass)

<Coating liquid 2>
In the coating liquid 1, the coating liquid 2 was obtained using 4.0 mass% of citric acid (first dissociation constant pK _a1 = 3.1) instead of malonic acid. The composition and pH of the coating solution 2 are as shown in Table 1.

<Coating liquid 3>
In the coating liquid 1, the coating liquid 3 was obtained by using 3.0 mass% of succinic acid (first dissociation constant pK _a1 = 4.1) instead of malonic acid. The composition and pH of the coating solution 3 are as shown in Table 1.

<Coating liquid 4>
In the coating liquid 1, the coating liquid 4 was obtained using 0.5 mass% of calcium chloride instead of malonic acid. The composition and pH of the coating solution 4 are as shown in Table 1.

<Coating liquid 5>
In the coating liquid 1, the coating liquid 5 was obtained by setting the content of resin-1 (in terms of solid content) to 10% by mass. The composition and pH of the coating solution 5 are as shown in Table 1.

<Coating liquid 6>
In the coating liquid 1, the resin-1 was replaced with 44.4% by mass of the following resin-2 to obtain a coating liquid 6. The composition and pH of the coating solution 6 are as shown in Table 1.

Resin-2: Nonionic resin having a polyurethane structure (emulsion of ester polyurethane resin fine particles; “Superflex 500M” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., resin solid content 45% by mass)

<Coating liquid 7>
In the coating liquid 1, the resin-1 was replaced with 66.7 mass% of the following resin-3 to obtain a coating liquid 7. The composition and pH of the coating solution 7 are as shown in Table 1.

Resin-3: Cationic resin (emulsion of acrylic resin fine particles; “Vinyl Blanc 2687” manufactured by Nissin Chemical Industry Co., Ltd., solid content 30% by mass)

2. Preparation of inkjet ink <Pigment dispersion 1>
Pigment Blue 15: 3 as a pigment to 18% by mass, 7.5% by mass of the following resin dispersant A-1 as a pigment dispersant, 15.0% by mass of the following resin dispersant B-1 and ethylene glycol 20 After premixing a mixed solution containing mass% and ion-exchanged water (remaining amount), the mixture was dispersed using a sand grinder filled with 50% by volume of 0.5 mm zirconia beads, and the pigment content was 18 A mass% pigment dispersion 1 was prepared. The average particle diameter of the pigment particles contained in this pigment dispersion was 113 nm. The average particle size was measured by “Zeta Sizer 1000HS” manufactured by Marul Balloon. The composition of the obtained pigment dispersion 1 is shown in Table 2. In Table 2, the content of each component in the composition of the pigment dispersion 1 is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.

Resin dispersant A-1: Resin dispersant having a nonionic water-soluble group (“DISPERBYK-193” manufactured by Big Chemie, no acid value, solid content: 40% by mass)
Resin dispersant B-1: Resin dispersant having a carboxyl group neutralized with alkali (sodium hydroxide) ("Joncrill 819" manufactured by BASF, acid value 75 [mgKOH / g], solid content 20% by mass)

<Ink 1>
The pigment dispersion 1 is 22.2% by mass, 20% by mass of ethylene glycol, 10% by mass of diethylene glycol, 0.5% by mass of surfactant (“Megafac F-444” manufactured by DIC) and the remaining amount of ions. Exchanged water was added with stirring, and the resulting mixture was filtered through a 1 μm filter to obtain Ink 1. The composition of 22.2% by mass of the pigment dispersion 1 is as shown in Table 3. In Table 3, the content of each component in the composition of the pigment dispersion 1 is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass. Table 4 shows the composition and _XAB value of ink 1 containing 22.2% by mass of pigment dispersion 1.

<Pigment dispersion 2 and ink 2>
In pigment dispersion 1, pigment dispersion 1 was used except that 9.0% by mass of resin dispersant A-2 and 18.0% by mass of resin dispersant B-1 were used instead of resin dispersant A-1. Similarly, pigment dispersion 2 was obtained.
The composition of the obtained pigment dispersion 2 is shown in Table 2. In Table 2, the content of each component in the composition of the pigment dispersion 2 is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
The composition of 22.2% by mass of the pigment dispersion 2 is as shown in Table 3. In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion liquid 1 was replaced with the pigment dispersion liquid 2, and the organic solvent was replaced as shown in Table 2 to obtain an ink 2.
Table 4 shows the composition and _XAB value of Ink 2 containing 22.2% by mass of Pigment Dispersion Liquid 2.

Resin dispersant A-2: Resin dispersant having a nonionic water-soluble group ("DISPERBYK-190" manufactured by Big Chemie, acid value 10 [mgKOH / g], solid content 40% by mass)

<Pigment dispersion 3 and ink 3>
In Pigment Dispersion Liquid 1, 11.3% by mass of the following resin dispersant A-3 is substituted for the resin dispersant A-1, and 6.75% of the following resin dispersant B-2 is substituted for the resin dispersant B-1. Pigment Dispersion Liquid 3 was obtained in the same manner as Pigment Dispersant 1, except that% was used.
The composition of the obtained pigment dispersion 3 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion 1 was replaced with the pigment dispersion 3, and the organic solvent was changed as shown in Table 2, to obtain an ink 3.
The composition and _XAB value of ink 3 containing 22.2% by mass of pigment dispersion 3 are as shown in Table 4.

Resin dispersant A-3: resin dispersant having a nonionic water-soluble group (“DISPERBYK-2015” manufactured by BYK Chemie, acid value 10 [mgKOH / g], solid content 40% by mass)
Resin dispersant B-2: Resin dispersant having a carboxyl group that is neutralized with alkali (sodium hydroxide) ("Joncrill 67" manufactured by BASF is dissolved in a sodium hydroxide aqueous solution and neutralized. Acid value 213 [mg KOH / g], solid content 20% by mass)

<Pigment dispersion 4 and ink 4>
In the pigment dispersion 1, the pigment dispersant 1 was used except that 18.0% by mass of the resin dispersant A-1 and 7.2% by mass of the following resin dispersant B-3 instead of the resin dispersant B-1 were used. In the same manner, a pigment dispersion 4 was obtained.
The composition of the obtained pigment dispersion 4 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion 1 was replaced with the pigment dispersion 4, and the organic solvent was changed as shown in Table 2 to obtain ink 4.
Table 4 shows the composition and _XAB value of ink 4 containing 22.2% by mass of pigment dispersion 4.

Resin Dispersant B-3: Resin Dispersant Having Carboxyl Group Neutralized with Alkali (Alkanolamine) (“DISPERBYK” manufactured by BYK Chemie, Acid Value 85 [mgKOH / g], Solid Content 50% by Mass)

<Pigment dispersion 5 and ink 5>
In Pigment Dispersion Liquid 3, Pigment Dispersion Liquid 5 was prepared in the same manner as Pigment Dispersant 3 except that Resin Dispersant A-3 was replaced with 18.0% by mass and Resin Dispersant B-2 was replaced with 18.0% by mass. Obtained.
The composition of the obtained pigment dispersion 5 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion 1 was replaced with the pigment dispersion 5, and the organic solvent was replaced as shown in Table 2 to obtain an ink 5.
The composition and _XAB value of ink 5 containing 22.2% by mass of pigment dispersion 5 are as shown in Table 4.

<Pigment dispersion 6 and ink 6>
In Pigment Dispersion Liquid 2, Pigment Dispersion Liquid 6 was prepared in the same manner as Pigment Dispersant 2, except that Resin Dispersant A-2 was replaced with 18.0% by mass and Resin Dispersant B-1 was replaced with 4.5% by mass. Obtained.
The compositions of the obtained pigment dispersion 6 are shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion liquid 1 was replaced with the pigment dispersion liquid 6, and the organic solvent was replaced as shown in Table 2 to obtain an ink 6.
The composition and _{X AB} value of the ink 6 containing the pigment dispersion 6 22.2% by weight are shown in Table 4.

<Pigment dispersion 7 and ink 7>
In Pigment Dispersion Liquid 4, Pigment Dispersion Liquid 7 was prepared in the same manner as Pigment Dispersant 4 except that Resin Dispersant A-1 was replaced with 16.9% by mass and Resin Dispersant B-3 was replaced with 13.5% by mass. Obtained.
The composition of the obtained pigment dispersion 7 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the pigment dispersion 1 was replaced with the pigment dispersion 7, and the organic solvent was changed as shown in Table 2 to obtain ink 7.
The composition and X _AB value of ink 7 containing 22.2% by mass of pigment dispersion 7 are as shown in Table 4.

<Pigment dispersion 8 and ink 8>
In pigment dispersion 1, pigment dispersion 8 was obtained in the same manner as pigment dispersant 1, except that 22.5% by mass of resin dispersant A-1 was used and the blending of resin dispersant B-1 was omitted.
The composition of the obtained pigment dispersion 8 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Furthermore, in the ink 1, the pigment dispersion 1 was replaced with the pigment dispersion 8, and the organic solvent was replaced as shown in Table 2 to obtain an ink 8.
Table 4 shows the composition and _XAB value of the ink 7 containing 22.2% by mass of the pigment dispersion 8.

<Pigment dispersion 9 and ink 9>
In Pigment Dispersion Liquid 1, Pigment Dispersion Liquid 9 was obtained in the same manner as Pigment Dispersant 1 except that the blending of Resin Dispersant A-1 was omitted and 33.8% by mass of Resin Dispersant B-1 was used. .
The composition of the obtained pigment dispersion 9 is shown in Tables 2 and 3.
In Table 2, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 100% by mass.
In Table 3, the content of each component in the composition of the pigment dispersion is the content (% by mass) when the total amount of the pigment dispersion is 22.2% by mass.
Further, in the ink 1, the ink 9 was obtained by replacing the pigment dispersion 1 with the pigment dispersion 9 and replacing the organic solvent as shown in Table 2.
The composition and X _AB value of ink 7 containing 22.2% by mass of pigment dispersion 9 are as shown in Table 4.

  In Table 2, “EG” represents ethylene glycol, “PG” represents propylene glycol, “DEG” represents diethylene glycol, and “1,2-HD” represents 1,2-hexanediol.

3. Inkjet recording method <Test 1>
(1) Formation of coating layer On a film substrate (material: biaxially stretched polypropylene film ("FOS # 60" manufactured by Futamura Chemical Co., Ltd.)), the coating liquid 1 has a thickness after drying of 1.5 µm. The coating layer was formed by coating with a wire bar and drying with a hot air dryer at 80 ° C.

(2) Printing Two independent drive heads of Konica Minolta's piezo-type inkjet head (360 dpi, discharge amount 14 pL) are arranged so that the nozzles are staggered, and a head module of 720 dpi × 720 dpi is created, on the stage transporter The nozzle row was installed so as to be orthogonal to the conveying direction. Similarly, another head module was installed side by side in the transport direction so that ink-jet print images for two colors could be printed by the one-pass method. Both the head modules for two colors are loaded with the ink 1 prepared as described above, and the amount of ink applied is 22.5 cc / m ^{2 by} the one-pass method on the coating layer of the film base material conveyed by the stage conveyance machine. The ink jet recording apparatus was configured so that solid printing was possible.

Using the ink jet recording apparatus, ink 1 was solid-printed at an ink application amount of 22.5 cc / m ² on a square area of 5 cm in length and width on the coating layer of the film base material, and then 60 ° C. on a hot plate. And dried for 15 minutes to form a solid image.

<Test 2>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 2 was used instead of ink 1, and an image was formed on the coating layer.

<Test 3>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that coating solution 2 was used instead of coating solution 1 and ink 3 was used instead of ink 1, and an image was formed on the coating layer. .

<Test 4>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 4 was used instead of ink 1, and an image was formed on the coating layer.

<Test 5>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that coating solution 2 was used instead of coating solution 1 and ink 5 was used instead of ink 1, and an image was formed on the coating layer. .

<Test 6>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 6 was used instead of ink 1, and an image was formed on the coating layer.

<Test 7>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 7 was used instead of ink 1, and an image was formed on the coating layer.

<Test 8>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that the coating liquid 2 was used instead of the coating liquid 1, and an image was formed on the coating layer.

<Test 9>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that the coating liquid 3 was used instead of the coating liquid 1, and an image was formed on the coating layer.

<Test 10>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that coating solution 4 was used instead of coating solution 1, and an image was formed on the coating layer.

<Test 11>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that the coating liquid 5 was used instead of the coating liquid 1, and an image was formed on the coating layer.

<Test 12>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that the coating liquid 6 was used instead of the coating liquid 1 and the ink 2 was used instead of the ink 1, and an image was formed on the coating layer. .

<Test 13>
In Test 1, a coating layer was formed in the same manner as in Test 1 except that coating solution 7 was used instead of coating solution 1 and ink 3 was used instead of ink 1, and an image was formed on the coating layer. .

<Test 14> (Comparison)
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 8 (comparative) was used instead of ink 1, and an image was formed on the coating layer.

<Test 15> (Comparison)
In Test 1, a coating layer was formed in the same manner as in Test 1 except that ink 9 (comparative) was used instead of ink 1, and an image was formed on the coating layer.

4). Evaluation Method (1) Bleeding Prevention For each of the images obtained in Tests 1 to 15, the bleeding prevention was evaluated according to the following evaluation criteria.
<Evaluation criteria>
AA: No bleeding is observed even when enlarged with a loupe.
A: Smear is observed when magnified with a magnifying glass, but is not visually observed.
B: Although blur can be discerned visually, there is no practical problem.
C: Severe blurring and not practical.

(2) Crack prevention property About each image obtained by the tests 1-15, the crack prevention property was evaluated by the following evaluation criteria.
<Evaluation criteria>
AA: No cracks are observed even when magnified with a loupe.
A: Cracks are observed when magnified with a magnifying glass, but are not visually observed.
B: Fine cracks can be discriminated by visual inspection.
C: Cracks are severe and not practical.

  The above results are shown in Table 3.

Claims (7)

Ink-jet ink containing at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant is applied to a recording medium having a coating layer formed by applying a coating liquid containing at least a resin and a pigment flocculant on a film substrate. An inkjet recording method for printing by a method,
As the pigment dispersant, at least a water-soluble resin dispersant (A) that dissolves in an acid and a water-soluble resin dispersant (B) that does not dissolve in an acid and alkali neutralizes an anionic group are used in combination. An ink jet recording method. The pigment flocculant includes an acid having a first dissociation constant of 3.5 or less,
The inkjet recording method according to claim 1, wherein the pH of the coating solution is less than a first dissociation constant of the acid. 3. The ink jet recording method according to claim 1, wherein the resin dispersant (A) and the resin dispersant (B) satisfy the relationship of the following formula (1) in the ink.
25 <(X _A · M _A + X _B · M _B ) / (M _A + M _B ) <65 (1)
(Wherein, _{X A} and _{X B} each represent the acid value of the resin dispersant (A) and the resin dispersant (B) [mgKOH / g] , M A and _{M B} are respectively the resin dispersant (It represents the content [% by mass] of (A) and the resin dispersant (B) with respect to the total amount of the ink.) The resin dispersant (A) has a nonionic water-soluble group,
The inkjet recording method according to claim 1, wherein the resin dispersant (B) has an alkali-neutralized carboxyl group.   The ink contains at least glycols and / or glycol ethers as the water-soluble organic solvent, and the content of glycols and / or glycol ethers is 10% by mass or more and 40% by mass or less based on the total mass of the ink. The inkjet recording method according to claim 1, wherein the inkjet recording method is a range.   The ink jet recording method according to claim 1, wherein the resin contained in the coating solution is a cationic or nonionic resin having a polyurethane structure. A recording liquid set comprising the following [I] and [II].
[I] A coating liquid containing at least a resin and a pigment flocculant [II] containing at least a pigment, a pigment dispersant, water, a water-soluble organic solvent, and a surfactant,
As the pigment dispersant, at least a water-soluble resin dispersant (A) that dissolves in an acid and a water-soluble resin dispersant (B) that does not dissolve in an acid and alkali neutralizes an anionic group are used in combination. Inkjet ink