Ink pre-treatment solution set

Abstract

This invention provides a water-based inkjet ink that exhibits excellent ejection stability, as well as superior resistance to blocking and migration of printed materials, enabling the production of high-quality printed materials even on non-permeable substrates. [Solution] An aqueous inkjet ink comprising a pigment, a surfactant (A), and a resin (R), wherein the surfactant (A) comprises an acetylenediol-based surfactant (A1) having a specific structure, a molecular weight of 400 to 650, and an HLB value of 7 to 12, and the resin (R) comprises a block resin (R1) having a glass transition temperature of 50 to 130°C and an acid value of 3 to 60 mgKOH / g, and the value expressed as AVA-AVB is 50 to 450, where AVA (mgKOH / g) is the highest acid value among the acid values ​​of each block constituting the block resin (R1) and AVB (mgKOH / g) is the lowest.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to an aqueous inkjet ink and a printed material formed using the aqueous ink set. [Background technology]

[0002] With the increasing demand for smaller print runs and diversifying needs, digital printing methods are rapidly gaining popularity. Because digital printing does not require printing plates, it enables small-lot printing, cost reduction, and miniaturization of printing equipment.

[0003] Inkjet printing is a type of digital printing method. In this method, tiny droplets of ink are ejected and landed on a printing substrate from an inkjet head, forming images and / or characters on the substrate. Compared to other digital printing methods, inkjet printing is superior in terms of the size and cost of the printing equipment, the running costs during printing, and the ease of full-color printing, and in recent years its use has been increasing in industrial printing applications.

[0004] Inkjet printing uses a wide variety of inks, including oil-based, solvent-based, active energy ray-curing, and water-based inks. Historically, solvent-based and active energy ray-curing inks have been used for industrial printing. However, in recent years, due to concerns about environmental and human hazards, the demand for water-based inks (inks primarily composed of water) has been increasing.

[0005] In recent years, there has been a growing demand for expanded applications of water-based inks used in inkjet printing (also referred to in this disclosure as "water-based inkjet inks"), such as packaging applications including paper containers, labels, and packaging films. For these packaging applications, there is a need for inks that can produce printed materials with excellent print quality and durability for actual use, not only on poorly permeable printing substrates such as coated paper and art paper, but also on non-permeable printing substrates.

[0006] Most water-based inkjet inks that have been put into practical use to date have been designed for printing on highly permeable printing substrates such as plain paper and specialty paper. When such water-based inkjet inks, especially those that have not undergone any of the treatments described later, are used on non-permeable printing substrates, the droplets that land on the substrate will not spread due to their high surface tension. Furthermore, when these droplets come into contact with adjacent water-based inkjet ink droplets, a force acts on each droplet to reduce its surface area, causing the droplets to merge and resulting in color bleeding (where different colors mix together) and color unevenness (where the same color is uneven in areas that are supposed to be the same color). Printed materials that exhibit color bleeding or color unevenness have significantly reduced print quality.

[0007] Furthermore, when printing on non-permeable printing substrates, the water-based inkjet ink does not penetrate and absorb into the substrate. Therefore, if the drying time is short, the deposited ink droplets will not dry sufficiently, and adequate adhesion to the printing substrate cannot be obtained. As a result, when printed materials are stored in a rolled or stacked state, pressure is applied to the printed surface, causing blocking. Blocking is a phenomenon in which a portion of the ink film is taken away by the printing substrate when peeling off the printing substrate that is adhered to the ink film.

[0008] A common method to improve print quality and blocking resistance (suppress the occurrence of blocking) is to lower the surface tension of water-based inkjet inks. For example, surface tension is reduced by adding surfactants and / or water-soluble organic solvents to water-based inkjet inks. However, generally, the time between when a droplet of water-based inkjet ink lands on the printing substrate and when another droplet lands in an adjacent position is only a few hundred microseconds to tens of milliseconds. Therefore, simply employing the above measures to reduce static surface tension is not enough to adequately wet and spread the droplets of water-based inkjet ink. As a result, droplets come into contact with each other while the surface tension remains high, leading to color bleeding and uneven coloring.

[0009] As a method to significantly reduce the surface tension of water-based inkjet ink, even for a short period of time, it is preferable to use a surfactant that has a small molecular weight and a high orientation rate to the droplet surface (gas-liquid interface). However, generally, such surfactants are poorly compatible with water, so there is a risk that the surfactant may concentrate and orient at the gas-liquid interface in water-based inkjet ink near the nozzle of an inkjet head. If this happens, the surface tension of the water-based inkjet ink near the nozzle will decrease locally, causing the water-based inkjet ink to overflow from the nozzle. In particular, if such ink overflow from the nozzle occurs and progresses during continuous ejection, it can lead to ejection defects such as flight deflection (a phenomenon in which water-based inkjet ink droplets do not land in the intended location) and nozzle clogging (a phenomenon in which water-based inkjet ink is not ejected from the nozzle), that is, a deterioration of ejection stability.

[0010] Furthermore, when a laminate containing an ink film within its layers is manufactured and used as packaging such as a pouch, there is a risk that low molecular weight surfactants with a high orientation rate, which are present on the surface of the ink film and / or have bled onto the surface of the ink film (a phenomenon in which components in the ink seep out onto the surface of the layer over time), may pass through each layer constituting the laminate and reach the surface of the laminate (migration). In particular, if the surfactant migrates to the surface that comes into contact with the contents, it may adversely affect the safety of the contents. For example, when the laminate is used for food packaging or cosmetic packaging, migration may become a critical problem.

[0011] Furthermore, in recent years, there has been a demand for shorter delivery times and improved production efficiency in inkjet printing. Meeting these demands requires increasing printing speed, but in that case, improving print quality and ejection stability of printed materials becomes extremely difficult. Thus, with conventional technology, it has been extremely difficult to simultaneously improve print quality, ejection stability, suppress blocking (improve blocking resistance), and suppress migration (improve migration resistance), even at high printing speeds.

[0012] For example, Patent Document 1 discloses an aqueous inkjet ink containing an acetylenediol-based surfactant with an HLB value of 3 or less and a water-soluble organic solvent with an HLB value of 8 or less. It also discloses that using this aqueous inkjet ink suppresses white spots and uneven aggregation caused by insufficient weldability of the aqueous inkjet ink on poorly penetrating substrates, resulting in printed materials with excellent print quality, and that the ejection stability of the aqueous inkjet ink is also good. Indeed, using the above surfactant and water-soluble organic solvent reduces image defects such as uneven aggregation when printing on poorly penetrating substrates. However, the acetylenediol-based surfactant with an HLB value of 3 or less corresponds to the surfactant with a low molecular weight and high orientation rate mentioned above. Therefore, depending on the printing conditions, the surfactant may concentrate and orient at the gas-liquid interface near the nozzle of the inkjet head, potentially causing nozzle clogging (a phenomenon in which aqueous inkjet ink is not ejected from the nozzle). Furthermore, acetylenediol-based surfactants with an HLB value of 3 or less generally have a small molecular weight of 300 or less, which makes them prone to migration.

[0013] Furthermore, Patent Document 2 discloses an inkjet recording method using an aqueous ink containing a specific acetylene glycol (acetylenediol-based surfactant) and a nonionic surfactant, with the blending amounts and ratios of each component specified. In the main example of the aqueous ink specifically disclosed in Patent Document 2, 2,4,7,9-tetramethyl-5-decine-4,7-diol is used as the acetylene glycol, and polyoxyalkylene alkyl ether surfactants such as polyoxyethylene lauryl ether (12 moles of ethylene oxide groups added) are used as the nonionic surfactant. On the other hand, since 2,4,7,9-tetramethyl-5-decine-4,7-diol corresponds to the surfactant with a low molecular weight and high orientation rate mentioned above, there was a risk of deterioration in discharge stability and migration resistance, similar to the case of Patent Document 1. In addition, with the configuration of the main example of the aqueous ink, there was a problem that it could not dry sufficiently when printing at high speed on a non-absorbent printing substrate, potentially causing blocking.

[0014] Furthermore, Patent Document 3 discloses an inkjet recording water-based ink containing an acetylenediol-based surfactant and a polyether-modified silicone-based surfactant in specific amounts and mixing ratios. Patent Document 3 also states that with the above-described water-based ink, migration can be prevented even when printing on a non-permeable printing substrate, and print quality such as solid print uniformity is also good. On the other hand, the acetylenediol-based surfactant used in the example of the water-based ink specifically disclosed in Patent Document 3 is a combination of a highly hydrophobic compound ("Surfinol 420" and "Surfinol 104") and a highly hydrophilic compound ("Surfinol 465"). The present inventors have investigated and found that, depending on the printing conditions, it may not be possible to suppress the concentrated orientation of the highly hydrophobic compound at the gas-liquid interface, which may lead to a deterioration in ejection stability. [Prior art documents] [Patent Documents]

[0015] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-165809 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-139004 [Patent Document 3] Japanese Patent Application Laid-Open No. 2022-100817 [Summary of the Invention] [Problems to be Solved by the Invention]

[0016] As described above, conventionally, there has been no aqueous inkjet ink that can simultaneously satisfy all of print quality (suppression of color bleeding and color unevenness), blocking resistance, migration resistance, and ejection stability, especially for non-permeable substrates, at a high level.

[0017] Therefore, in one embodiment of the present invention, there is provided an aqueous inkjet ink that is excellent in ejection stability, blocking resistance, and migration resistance of a printed matter, and can produce a printed matter having excellent print quality even on a non-permeable substrate. In addition, the "printed matter having excellent print quality" in the present disclosure refers to a printed matter in which color bleeding and color unevenness are suppressed. [Means for Solving the Problems]

[0018] As a result of intensive studies by the present inventors, it has been found that the above-described problems can be solved by an aqueous inkjet ink having the following configuration.

[0019] That is, one embodiment of the present invention relates to an aqueous inkjet ink. Another embodiment of the present invention relates to a printed matter using the above aqueous inkjet ink. More specifically, the embodiments of the present invention include the following. However, the present invention is not limited to the following embodiments and includes various embodiments. [1] An aqueous inkjet ink containing a pigment, a surfactant (A), and a resin (R), The surfactant (A) includes an acetylenediol-based surfactant (A1) having a structure represented by the following general formula (1), a molecular weight of 400 to 650, and an HLB value of 7 to 12. The aforementioned resin (R) includes a block resin (R1) having a glass transition temperature of 50 to 130°C and an acid value of 3 to 60 mgKOH / g. A water-based inkjet ink in which, among the acid values ​​possessed by each block constituting the block resin (R1), the highest is AVA (mgKOH / g) and the lowest is AVB (mgKOH / g), and the value expressed as AVA-AVB is between 50 and 450. General formula (1): [ka] (In general formula (1), R 1 and R 2 Each of the following represents an alkyl group having 1 to 5 carbon atoms, which may be branched: EO represents an ethylene oxide group, and PO represents a propylene oxide group. Furthermore, m1 and n1 each represent integers from 1 to 10, and m2 and n2 each represent integers from 0 to 5. However, if m2 + n2 > 0, the addition pattern of the ethylene oxide group and propylene oxide group within the square brackets may be either block or random. [2] The aqueous inkjet ink according to [1], wherein the molecular weight distribution (PDI) of the block resin (R1) is 1.0 to 1.8. [3] The surfactant (A) further comprises a nonionic surfactant (A2), The aqueous inkjet ink according to [1] or [2], wherein the nonionic surfactant (A2) comprises a siloxane-based surfactant. [4] The aqueous inkjet ink according to [3], wherein the nonionic surfactant (A2) further comprises an acetylenediol-based surfactant having an HLB value greater than 12 and less than or equal to 19, and / or a polyoxyalkylene monoalkyl ether-based surfactant having an HLB value greater than 12 and less than or equal to 19. A printed material having been printed on a printing substrate using any of the water-based inkjet inks described in [5], [1], or [4]. [Effects of the Invention]

[0020] One embodiment of the present invention, an aqueous inkjet ink, exhibits excellent ejection stability, as well as superior resistance to blocking and migration of printed materials, and enables the production of printed materials with excellent print quality even on non-permeable substrates. [Modes for carrying out the invention]

[0021] The following describes an embodiment of the present invention: an aqueous inkjet ink (hereinafter simply referred to as "the aqueous inkjet ink of this embodiment" or "ink"). It should be noted that the present invention is not limited to the embodiments described below, and includes modified forms that do not alter the essential parts of the present invention.

[0022] As described above, the aqueous inkjet ink of this embodiment having the above configuration can simultaneously and at a high level solve the issues of ejection stability, print quality, blocking resistance, and migration resistance of printed materials. Although the mechanism is not clear, the inventors speculate as follows. However, the present invention is not limited by the following speculation.

[0023] Generally, water, the main solvent in water-based inkjet inks, has high surface tension and does not easily wet and spread on the printing substrate. Furthermore, when droplets of water-based inkjet ink that have landed on the printing substrate come into contact with adjacent undried droplets while they are still wet, these droplets attract each other, causing color bleeding and uneven coloring, resulting in a decrease in print quality.

[0024] As a method to suppress color bleeding and uneven coloring, it is preferable to use a surfactant with a small molecular weight and a high orientation rate to the droplet surface (interface). Among these surfactants, acetylenediol-based surfactants have acetylene groups in which no bond rotation occurs within the molecule. As a result, they are less structurally deformable compared to other surfactants, such as polyoxyethylene alkyl ether-based surfactants. Therefore, even with the addition of a small amount, a sufficient amount of acetylenediol-based surfactant molecules can be oriented at the gas-liquid interface. However, since such surfactants are poorly compatible with water, for example, in aqueous inkjet ink present near the nozzle of an inkjet head, the surfactant may concentrate and orient at the interface, potentially causing the aqueous inkjet ink to overflow from the nozzle. Such a phenomenon can lead to a deterioration in ejection stability.

[0025] Furthermore, surfactants with low molecular weight and high orientation rates are abundant on the surface of the film (ink film) formed when water-based inkjet ink dries. This can lead to blocking due to the movement of surfactant molecules caused by heat, humidity, etc. In addition, these surfactants may bleed onto the surface of the laminate containing the ink film, potentially causing migration.

[0026] On the other hand, if the amount of surfactant with a low molecular weight and high orientation rate used is reduced in order to suppress deterioration of discharge stability and the occurrence of blocking and migration, then it becomes impossible to suppress the occurrence of the aforementioned color bleeding and uneven coloring, making it difficult to obtain printed materials with good print quality.

[0027] As described above, surfactants with low molecular weight and high orientation rates are effective in improving print quality, but they come with a trade-off in terms of discharge stability, blocking resistance, and migration resistance.

[0028] On the other hand, surfactants with medium molecular weight may negatively affect print quality compared to the low molecular weight surfactants mentioned above due to their lower orientation rate. However, they are superior to the low molecular weight surfactants in terms of ejection stability and suppression of blocking and migration. In particular, controlling the hydrophilicity and hydrophobicity of surfactants with medium molecular weight suppresses the phenomenon of aqueous inkjet ink overflowing from the nozzle, resulting in good ejection stability.

[0029] From this perspective, the aqueous inkjet ink of this embodiment uses an acetylenediol-based surfactant (A1) as the surfactant, which has the structure represented by the above general formula (1), a molecular weight of 400 to 650, and an HLB value of 7 to 12.

[0030] On the other hand, in order to suppress color bleeding and unevenness and prevent deterioration of print quality while using surfactants with a medium molecular weight, it is necessary to reduce the amount of components in the water-based inkjet ink that inhibit the orientation of the surfactant at the interface. Generally, resins are components that inhibit the above orientation, but the degree to which the above orientation is inhibited differs depending on the form of the resin. Therefore, the selection of the form of the resin is very important from the perspective of improving print quality in water-based inkjet inks using surfactants with a medium molecular weight.

[0031] Generally, water-soluble resins, as well as water-insoluble resins such as hydrosols and emulsions, are known as forms of resins used in water-based inkjet inks. Here, "water-soluble resin" refers to a resin in which a 1% by mass water mixture is transparent to the naked eye at 25°C, and "water-insoluble resin" refers to a resin in which the above water mixture is opaque. Furthermore, "hydrosol" refers to a form in which a resin whose acidic and / or basic functional groups have been neutralized is dispersed in an aqueous medium (a liquid medium containing at least water), and "emulsion" refers to a form in which an emulsifier is adsorbed onto the surface of resin microparticles (microparticles containing resin as the main component) and dispersed in an aqueous medium.

[0032] Of these, water-soluble resins are thought to exist in a spread-out state within water-based inkjet inks. In this case, the resin molecules become entangled with each other, forming a network, which inhibits the orientation of the surfactant. This makes the orientation more likely to be inhibited, and therefore is not desirable.

[0033] On the other hand, if a non-water-soluble resin is used, the aforementioned network is less likely to form, thus the orientation of the surfactant is less likely to be inhibited, and the occurrence of color bleeding and uneven coloring can be suppressed. However, if an emulsion is used as the resin, depending on the type of emulsifier, it may adversely affect the orientation of the surfactant, similar to the case of a water-soluble resin. Also, generally, once an emulsion is formed into a film, it is difficult to return it to its original emulsion state, which tends to lead to a deterioration in dispensing stability.

[0034] Based on the above, in order to suppress the deterioration of print quality when using a surfactant with a moderate molecular weight, it is preferable to select a hydrosol as the resin.

[0035] The above hydrosols can be manufactured, for example, from random resins with a low acid value (resins in which monomer units are arranged randomly). However, in the case of hydrosols manufactured from such random resins, it is difficult to suppress the spreading of resin molecules in aqueous inkjet inks, and there is a risk that the inhibition of surfactant orientation described above cannot be completely prevented. Furthermore, during high-speed printing or printing of high-print-density images, it is difficult to form a sufficient film unless drying is performed using a large amount of drying energy, and if the film formation is insufficient, the strength of the ink-dried film necessary to suppress blocking cannot be obtained. In particular, when using thin polypropylene films, depending on the printing substrate used for printing, it may not have heat resistance, making it impossible to dry at high temperatures, and as a result, a sufficient film cannot be formed, which often leads to problems in achieving blocking resistance.

[0036] Therefore, in the aqueous inkjet ink of this embodiment, a block resin (R1) is used as the resin (R), which has a glass transition temperature (Tg) of 50 to 130°C and an acid value of 3 to 60 mgKOH / g, and when the highest acid value among the acid values ​​of each block is taken as AVA (mgKOH / g) and the lowest as AVB (mgKOH / g), the value expressed as AVA-AVB is 50 to 450.

[0037] If the acid value of the entire resin is 3 to 60 mgKOH / g, and the difference between the acid value of the block with the highest acid value (AVA) and the acid value of the block with the lowest acid value (AVB) is 50 to 450 mgKOH / g, then a hydrosol with suppressed spreading of resin molecules is easily formed. As a result, there is nothing to inhibit the orientation of surfactants with medium molecular weights at the interface, and the rate of orientation does not decrease. Furthermore, if the glass transition temperature (Tg) of the block resin (R1) is 50 to 130°C, the strength of the ink film after film formation is increased. Also, during drying, compared to hydrosols made of random resins, the block resin (R1) is easier to form a film, and it is considered that it is easier to obtain an ink film with sufficient strength to exhibit blocking resistance.

[0038] In addition, as mentioned above, the firm film formation of the block resin (R1) is thought to suppress the phenomenon of surfactants and other components remaining inside the ink film bleeding onto the ink film surface over time after the ink film has been formed, thereby improving migration resistance.

[0039] As described above, the ink having the configuration of the present invention can solve the above-mentioned problems simultaneously and at a high level.

[0040] Next, the components constituting the aqueous inkjet ink, which is one embodiment of the present invention, will be described in detail below.

[0041] <Surfactant (A)> (Acetylenediol-based surfactant (A1)) As described above, the aqueous inkjet ink of this embodiment contains an acetylenediol-based surfactant (A1) as the surfactant (A), which has a structure represented by the following general formula (1), a molecular weight of 400 to 650, and an HLB value of 7 to 12.

[0042] General formula (1): [ka]

[0043] In general formula (1), R 1 and R 2 Each of the following represents an alkyl group having 1 to 5 carbon atoms, which may be branched: EO represents an ethylene oxide group, and PO represents a propylene oxide group. Also, m1 and n1 each represent integers from 1 to 10, and m2 and n2 each represent integers from 0 to 5. However, if m2 + n2 > 0, the addition pattern of the ethylene oxide group and propylene oxide group within the square brackets may be either block or random. As a method for setting the molecular weight and HLB value of the acetylenediol-based surfactant (A1) within the above range, the values ​​of m1, n1, m2, n2 in the above general formula (1), and R 1 and R 2 One method is to change the structure.

[0044] From the viewpoint of improving print quality by ensuring a good orientation speed at the interface, suppressing blocking and migration, and improving ejection stability, the HLB value of the acetylenediol-based surfactant (A1) is 7 to 12, preferably 7 to 9. Having an HLB value within this range reduces the hygroscopicity of the ink film constituting the printed material, leading to further improvement in blocking resistance. Furthermore, it prevents the water-based inkjet ink from overflowing from the nozzle and prevents excessive adsorption to the generally hydrophobic pigment surface, improving the dispersion stability of the pigment and thus leading to further improvement in ejection stability.

[0045] The HLB (Hydrophile-Lipophile Balance) value is one of the parameters that represent the hydrophilicity or hydrophobicity of a material. There are various methods for calculating the HLB value, such as the Griffin method, the Davis method, and the Kawakami method, but in this disclosure, the HLB value of the acetylenediol-based surfactant (A1) is calculated using the Griffin method.

[0046] The Griffin method uses the molecular weight of the compound in question to determine the hydrophobicity, as shown in formula (2) below. Note that a smaller HLB value indicates higher hydrophobicity of the compound, while a larger HLB value indicates higher hydrophilicity.

[0047] Formula (2): HLB value = 20 × (sum of molecular weights of hydrophilic portions in the target compound) ÷ (molecular weight of the target compound)

[0048] The molecular weight of the acetylenediol-based surfactant (A1) is 400 to 650, more preferably 400 to 600, and even more preferably 400 to 580. Acetylenediol-based surfactants (A1) with a molecular weight within the above range have a moderately high orientation rate to the interface, which can suppress color bleeding and uneven coloring. Furthermore, they can prevent the occurrence and deterioration of blocking and migration. In this disclosure, the molecular weight of the acetylenediol-based surfactant (A1) refers to the formula weight, which can be determined by calculation.

[0049] Specific examples of acetylenediol-based surfactants (A1) include 2,4,7,9-tetramethyl-5-decine-4,7-diol, 2,5,8,11-tetramethyl-6-dodecine-5,8-diol, hexadeca-8-in-7,10-diol, 4,7-dipropyl-deca-5-in-4,7-diol, 6,9-dimethyl-tetradeca-7-in-6,9-diol, 3,6-diisopropyl-2,7-dimethylocta-4-in-3,6-diol, and octa Examples include ethylene oxide-modified or ethylene oxide and propylene oxide-modified compounds such as deca-9-in-8,11-diol, 7,10-dimethylhexadeca-8-in-7,10-diol, 5,8-dibutyldodeca-6-in-5,8-diol, 4,7-diisobutyl-2,9-dimethyldeca-5-in-4,7-diol, and 5,14-diethyl-8,11-dimethyloctadeca-9-in-8,11-diol. Note that one of the listed compounds may be used alone, or two or more may be used in combination. Furthermore, these compounds may be synthesized using conventionally known synthesis methods, or commercially available products may be used.

[0050] In particular, from the viewpoint of having high compatibility with water, which is the main component of water-based inkjet inks, and improving the print quality and ejection stability of printed materials, it is preferable to use one or more compounds selected from the group consisting of ethylene oxide-modified 2,4,7,9-tetramethyl-5-decine-4,7-diol; ethylene oxide and propylene oxide-modified 2,4,7,9-tetramethyl-5-decine-4,7-diol; and ethylene oxide-modified 2,5,8,11-tetramethyl-6-dodecine-5,8-diol, and it is especially preferable to use ethylene oxide and propylene oxide-modified 2,4,7,9-tetramethyl-5-decine-4,7-diol.

[0051] The amount of acetylenediol-based surfactant (A1) contained in the aqueous inkjet ink of this embodiment is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 3.5% by mass, even more preferably 0.3 to 2.5% by mass, particularly preferably 0.5 to 2.0% by mass, and most preferably 0.5 to 1.5% by mass of the total amount of aqueous inkjet ink. By using within the above range, it is possible to achieve a high level of simultaneous suppression of color bleeding and unevenness, improvement of ejection stability, and suppression of blocking and migration.

[0052] (Other surfactants) The aqueous inkjet ink of this embodiment may further contain, as surfactant (A), a surfactant other than the acetylenediol-based surfactant (A1) described above (i.e., different from (A1) described above) (also referred to in this disclosure as "other surfactants").

[0053] In the aqueous inkjet ink of this embodiment, one or more surfactants selected from the group consisting of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants (excluding acetylenediol-based surfactant (A1)) can be used as the other surfactant. In particular, it is preferable to use a nonionic surfactant other than acetylenediol-based surfactant (A1) (in this disclosure, also simply referred to as "nonionic surfactant (A2)") as the other surfactant, from the viewpoint of excellent compatibility with acetylenediol-based surfactant (A1) and improved ejection stability, print quality of printed materials, and blocking resistance.

[0054] (Nonionic surfactant (A2)) Examples of nonionic surfactants (A2) that can be used include acetylenediol-based surfactants (excluding acetylenediol-based surfactants (A1)), acetylene monool-based surfactants, siloxane-based surfactants, fluorine-based surfactants, and polyoxyalkylene monoalkyl ether-based surfactants (specifically, compounds having an ethylene oxide group and / or a propylene oxide group, where the total number of added moles of the ethylene oxide group and propylene oxide group is 5 to 100, and the number of carbon atoms in the alkyl or alkenyl group at the molecular terminus is 5 to 22); These other surfactants may be used individually or in combination of two or more.

[0055] In particular, it is preferable to use one or more nonionic surfactants (A2) selected from the group consisting of acetylenediol-based surfactants (excluding acetylenediol-based surfactant (A1)), siloxane-based surfactants, and polyoxyalkylene monoalkyl ether-based surfactants. These surfactants are preferable because they are well compatible with acetylenediol-based surfactant (A1) or can emulsify it, and as a result, it is expected that both improved discharge stability and suppression of color bleeding and uneven coloring can be achieved.

[0056] Among the above, the use of a siloxane-based surfactant as the nonionic surfactant (A2) is particularly preferable. When a siloxane-based surfactant is used as the other surfactant, it is less likely to adversely affect the discharge stability. Furthermore, after the droplet of water-based inkjet ink lands on the printing substrate, the siloxane-based surfactant orients on the droplet surface, lagging behind the orientation of the acetylenediol-based surfactant (A1). After orienting at the interface, the siloxane-based surfactant remains in a very stable state. As a result, the droplet can spread sufficiently, and color bleeding and unevenness can be suppressed to a higher level. Moreover, improved blocking resistance can also be expected.

[0057] In one embodiment, the content of the siloxane-based surfactant is preferably 20 to 850% by mass, and particularly preferably 40 to 400% by mass, relative to the content of the acetylenediol-based surfactant (A1). When the content of the siloxane-based surfactant is adjusted within the above range, it is easy to suppress color bleeding and unevenness, and to improve wetting spread and blocking resistance while achieving suitable discharge stability.

[0058] On the other hand, from the viewpoint of improving the blocking resistance and discharge stability of printed materials, it is preferable to use a combination of a siloxane-based surfactant and an acetylenediol-based surfactant with an HLB value greater than 12 and less than or equal to 19, and / or a polyoxyalkylene monoalkyl ether-based surfactant with an HLB value greater than 12 and less than or equal to 19 (specifically, a compound having an ethylene oxide group and / or a propylene oxide group, where the total number of added moles of the ethylene oxide group and the propylene oxide group is 5 to 100, and the number of carbon atoms of the alkyl or alkenyl group at the molecular terminus is 5 to 22) as the nonionic surfactant (A2).

[0059] The total amount of the acetylenediol-based surfactant having an HLB value greater than 12 and less than or equal to 19, and the polyoxyalkylene monoalkyl ether-based surfactant having an HLB value greater than 12 and less than or equal to 19, is preferably 10 to 250% by mass, and particularly preferably 25 to 120% by mass, relative to the content of the acetylenediol-based surfactant (A1). When the content is adjusted as described above, the effects of the acetylenediol-based surfactant (A1) can be suitably expressed, and suppression of color bleeding and uneven coloring, suppression of blocking, and improvement of discharge stability can all be achieved simultaneously.

[0060] The total amount of nonionic surfactant (A2) contained in the aqueous inkjet ink of this embodiment is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 2.5% by mass, even more preferably 0.3 to 2.0% by mass, and particularly preferably 0.4 to 1.5% by mass. By using the nonionic surfactant (A2) within the above range, it becomes easy to achieve a high level of both suppression of color bleeding and unevenness, ejection stability, and blocking resistance.

[0061] Below are examples of commercially available siloxane-based surfactants that can be used as nonionic surfactants (A2). BY16-201, FZ-77, FZ-2104, FZ-2110, FZ-2162, F-2123, L-7001, L-7002, SF8427, SF8428, SH3749, SH8400, 8032ADDITIVE, SH3773M (manufactured by Toray Dow Corning), TEGO Glide 100, TEGO Glide 410, TEGO Glide 432, TEGO Glide 435, TEGO Glide 440, TEGO Glide 450, TEGO Twin 4000, TEGO Twin4100, TEGO Wet240, TEGO Wet250, TEGO Wet260, TEGO Wet270, TEGO Wet280 (manufactured by Evonik), SAG-002, SAG-503A (manufactured by Nisshin Chemical Industry Co., Ltd.) BYK-331, BYK-333, BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-3420, BYK-3450, BYK-3451, BYK-3760, BYK-UV3500, BYK-UV3510 (manufactured by BYK-Chemie Co., Ltd.) KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-6004, KF-6011, KF-6012, KF-6013, KF-6015, KF-6016, KF-6017, KF-6043, KF-615A, KF-640, KF-642, KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.). The products listed above may be used individually or in combination of two or more. Alternatively, instead of these commercially available products, siloxane-based surfactants synthesized using conventionally known synthesis methods may be used.

[0062] The following are examples of commercially available acetylenediol-based surfactants with an HLB value greater than 12 and less than or equal to 19 that can be used as nonionic surfactants (A2). Surfinol 465, 485 (manufactured by Evonik), Orphine E1010, E1020, EXP.4200, EXP.4123 (manufactured by Nisshin Chemical Industry Co., Ltd.), Acetyleneol E100, E200 (manufactured by Kawaken Fine Chemical Co., Ltd.). The products listed above may be used individually or in combination of two or more. Alternatively, instead of these commercially available products, acetylenediol-based surfactants with an HLB value greater than 12 and less than or equal to 19, synthesized using conventionally known synthesis methods, may be used.

[0063] In particular, from the viewpoint of excellent compatibility with water, improved discharge stability, and prevention of deterioration of blocking resistance, it is preferable to use ethylene oxide modified products of 2,4,7,9-tetramethyl-5-decine-4,7-diol or 2,5,8,11-tetramethyl-6-dodecine-5,8-diol.

[0064] Below are examples of commercially available polyoxyalkylene monoalkyl ether surfactants with an HLB value greater than 12 and less than or equal to 19, which can be used as nonionic surfactants (A2). Nonion series (manufactured by NOF Corporation) such as Nonion K-220, K-230, K-2100W, P-210, P-213, E-212, E-215, E-230, S-215, S-220, B-250, EH-208, ID-206, ID-209, etc., Emulgen 108, 109P, 120, 123P, 147, 150, 220, 3 Emulgen series (manufactured by Kao Corporation) such as 20P, 350, 420, 430, 707, 709, 1108, 1118S-70, 1135S-70, 1150S-60, LS-106, LS-110, LS-114, etc., and Tarjitol series (manufactured by Dow Chemical Corporation) such as Tarjitol L-64, Tarjitol TMN-6, 10, 100X, etc. The products listed above may be used individually or in combination of two or more. Alternatively, instead of these commercially available products, polyoxyalkylene monoalkyl ether surfactants with an HLB value greater than 12 and less than or equal to 19, synthesized by conventionally known synthesis methods, may be used.

[0065] The total amount of surfactant contained in the aqueous inkjet ink of this embodiment is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 4.5% by mass, even more preferably 0.3 to 4.0% by mass, and particularly preferably 0.4 to 3.5% by mass, based on the total amount of the aqueous inkjet ink.

[0066] <Resin (R)> (Block resin (R1)) While random, alternating, block, and graft arrangements of monomer units constituting resins (polymers) are known, the aqueous inkjet ink of this embodiment uses a resin (R) in which monomer units are arranged in a block type (block resin). Specifically, the aqueous inkjet ink of this embodiment includes a block resin (R1) as the resin (R), which has a glass transition temperature (Tg) of 50 to 130°C, an acid value of 3 to 60 mgKOH / g, and where the value expressed as AVA-AVB is 50 to 450, with the highest acid value of each block being AVA (mgKOH / g) and the lowest being AVB (mgKOH / g).

[0067] Block resin is a resin in which two or more different resins (blocks) are covalently bonded together. Compared to random resin, block resin allows for the localization of hydrophilic and hydrophobic groups within the molecule, making it easier to control the solubility of the resin in aqueous media. Furthermore, even with a low acid value for the entire resin, block resin can exist stably in aqueous media without aggregation or entanglement of resin molecules, even without emulsifiers or other components. In addition, when water-based inkjet ink dries, it quickly forms a film as the water evaporates, easily becoming a continuous film, making it suitable for high-speed printing, for example. Moreover, because it does not contain low-molecular-weight components such as emulsifiers, as in emulsions, the ink film formed after drying the water-based inkjet ink of this embodiment exhibits good blocking resistance and migration resistance.

[0068] For example, a polymer with a chain-like molecular chain can be used as the block resin (R1). Furthermore, when the blocks contained in the block resin are designated as P1, P2, P3, etc., for example, a 2-block resin such as P1-P2, a 3-block resin such as P1-P2-P1, P1-P2-P3, and a 2×x block resin represented by (P1-P2)x (where x is an integer of 2 or more) can be used.

[0069] From the viewpoint of improving the storage stability and ejection stability of water-based inkjet inks, it is preferable to separate the functions of each block constituting the block resin (R1). Specifically, it is preferable to use a resin that has one or more blocks, each consisting of a block with high hydrophilicity that can prevent aggregation between resins or between solid components contained in the water-based inkjet ink and the resin due to steric repulsion, electrostatic repulsion, etc. (hereinafter referred to as "Block A") and a block with high hydrophobicity that can adsorb to pigments or form hydrophobic interactions between resin molecules (hereinafter referred to as "Block B").

[0070] From the above-mentioned viewpoints, the improvement of print quality, and the improvement of storage stability and ejection stability of the water-based inkjet ink, it is preferable that the acid value of block A in the block resin (R1) is greater than the acid value of block B. Specifically, among the acid values ​​of each block, the block with the highest acid value is designated as block A, and the block with the lowest acid value is designated as block B. When the acid value of block A is AVA (mgKOH / g) and the acid value of block B is AVB (mgKOH / g), the value expressed as AVA-AVB, that is, the difference between the acid value of block A and the acid value of block B, is preferably 50 to 450 (mgKOH / g), more preferably 80 to 430 (mgKOH / g), and particularly preferably 100 to 420 (mgKOH / g). In particular, if the above difference value is 450 (mgKOH / g) or less, the molecular chain portion corresponding to block A spreads out in the water-based inkjet ink, making it easier to form a uniform film when drying on the printing substrate, and improving migration resistance.

[0071] In this disclosure, the acid value of a resin refers to the number of milligrams of potassium hydroxide (KOH) required to neutralize the anionic functional groups contained in 1 gram of the resin. In this disclosure, the acid value of each block is that of a resin having the same composition as the monomer unit of each block.

[0072] In this disclosure, the acid value of the above resin is calculated by the following method. For example, if the above resin contains Wa mass% of monomer units in one molecule that have na acid groups with a va value and a molecular weight of Ma, its acid value (mgKOH / g) is determined by the following formula (3).

[0073] Formula (3): (Acid value) = {(va × na × Wa) ÷ (100 × Ma)} × 56.11 × 1000

[0074] In equation (3) above, the value "56.11" is the molecular weight of potassium hydroxide.

[0075] The glass transition temperature (Tg) of the above-mentioned block resin (R1) is 50 to 130°C, more preferably 50 to 120°C, from the viewpoint of improving blocking resistance. If the glass transition temperature is 50°C or higher, printed materials with excellent blocking resistance can be obtained regardless of the storage environment. If it is 120°C or lower, even in the case of high-speed printing or high-print-rate printing, the water-based inkjet ink will form a sufficient film, resulting in printed materials with excellent migration resistance in addition to blocking resistance.

[0076] The glass transition temperature of the resin in this disclosure is a value measured using a DSC (Differential Scanning Calorimeter). Specifically, approximately 10 mg of a dried resin sample is weighed on an aluminum pan and then placed in the sample holder of the DSC (for example, Shimadzu Corporation's "DSC-60Plus"). The value read from the baseline shift observed in the chart (DSC curve) obtained under a heating condition of 5°C / min (midpoint glass transition temperature) is defined as the glass transition temperature in this invention. Details regarding the measurement method of the glass transition temperature and how to read the chart can be found in JIS K 7121:2012.

[0077] The acid value of the block resin (R1) is 3 to 60 mg KOH / g. Furthermore, from the viewpoint of improving the storage stability of the water-based inkjet ink, and from the viewpoint of the molecular chain portion corresponding to block A spreading in the water-based inkjet ink, which facilitates uniform film formation on the printing substrate during drying and improves blocking resistance and migration resistance, an acid value of 10 to 60 mg KOH / g is preferable.

[0078] Examples of resins that can be used in the aqueous inkjet ink of this embodiment include acrylic resin, styrene resin, maleic acid resin, urethane resin, polyester resin, vinyl chloride resin, vinyl chloride-vinyl acetate resin, polyolefin resin, polyvinyl alcohol resin, and polyalkylene glycol resin. These resins may be used individually or in combination of two or more types.

[0079] In the aqueous inkjet ink of this embodiment, it is preferable to use a resin selected from the group consisting of acrylic resin, styrene resin, maleic acid resin, polyolefin resin, and polyalkylene glycol resin as each block constituting the block resin (R1). Furthermore, from the viewpoint of obtaining a highly hydrophilic A block, it is preferable to use an acrylic resin or maleic acid resin as the A block. On the other hand, from the viewpoint of obtaining a highly hydrophobic B block, it is preferable to use a resin selected from the group consisting of acrylic resin, styrene resin, polyolefin resin, and polyalkylene glycol resin as the B block.

[0080] In this disclosure, "acrylic resin" refers to a resin using one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters. In addition to the monomers listed above, styrene monomers may also be used as monomers constituting the acrylic resin. However, resins containing (anhydride) maleic acid (maleic acid and / or maleic anhydride) as the monomer are not included in "acrylic resin" in this disclosure.

[0081] On the other hand, "maleic acid resin" in this disclosure refers to a resin using at least (anhydrous) maleic acid as a monomer. Furthermore, the maleic acid resin may also use one or more elements selected from the group consisting of α-olefins, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, styrene, and styrene derivatives as monomers.

[0082] The number-average molecular weight (MnP) of the block resin (R1) is preferably 4,000 to 30,000, more preferably 5,000 to 28,000, and even more preferably 6,000 to 26,000. If the number-average molecular weight is 4,000 or higher, printed materials with excellent blocking resistance, migration resistance, water resistance, and abrasion resistance can be obtained, and if it is 30,000 or lower, it becomes easy to obtain an aqueous inkjet ink with excellent ejection stability.

[0083] Furthermore, from the viewpoint of improving discharge stability, the molecular weight distribution (PDI) of the block resin (R1) is preferably 1.0 or more and 1.8 or less. More preferably 1.0 or more and 1.6 or less. If it is 1.6 or less, migration resistance is improved regardless of the storage environment of the printed material, and it becomes easier to suppress deterioration of print quality when using surfactants with a medium molecular weight, such as acetylenediol-based surfactants (A1).

[0084] In this disclosure, the number-average molecular weight (MnP) and molecular weight distribution (PDI) of the resin are values ​​measured as follows: A gel permeation chromatography (GPC, e.g., "HLC-8320GPC" manufactured by Tosoh Corporation) equipped with two TSKgel® SuperMultIpore HZ-H columns (manufactured by Tosoh Corporation, 4.6 mm I.D. × 15 cm) is used, and tetrahydrofuran is used as the eluent to measure the mass-average molecular weight (Mw) and number-average molecular weight (Mn). The obtained number-average molecular weight (Mn) is defined as MnP, and the value of Mw / Mn is defined as PDI. Both Mw and Mn are polystyrene equivalent values ​​and can be calculated from a calibration curve created using TSK Standard polystyrene (manufactured by Tosoh Corporation) as a standard sample.

[0085] The synthesis method for the block resin (R1) described above is not limited, but living polymerization is preferred, and living radical polymerization is more preferred. Living radical polymerization methods include methods using sulfur-based reversible chain transfer (RAFT method), methods using organotellurium compounds (TERP method), methods using transition metal catalysts (ATRP method), and nitroxide-mediated radical polymerization (NMP method), depending on the method used to stabilize the polymerization growth ends. Among these, the RAFT method is preferred because it can control the polymerization of monomers other than conjugated monomers (monomers with substituents that have a resonance stabilization effect).

[0086] The block resin (R1) may be used for any application, such as pigment dispersion, binder, wax, or thickening. Furthermore, the block resin (R1) may be used for a single application or for multiple applications. For example, if the resin (R) contained in the aqueous inkjet ink is only one type of block resin (R1), and this block resin (R1) exhibits both the pigment dispersion and binder functions described later, then the block resin (R1) serves both the pigment dispersion and binder purposes. On the other hand, from the viewpoint of obtaining an aqueous inkjet ink that can suitably solve all of the problems of the present invention, namely, ejection stability, as well as the blocking resistance, migration resistance, and print quality of printed materials, it is preferable that each resin (R) contained in the aqueous inkjet ink of this embodiment is used for a single application. For example, in the aqueous inkjet ink of this embodiment, it is preferable to include the pigment dispersion resin and the binder resin separately, rather than using only one type of resin that serves both as a pigment dispersion resin and a binder resin.

[0087] Among the applications listed above, the block resin (R1) is preferably used in binder applications and / or pigment dispersion applications, and is particularly preferably used in binder applications, from the viewpoint that the film formation of the block resin (R1) improves the strength and barrier properties of the ink film, and improves blocking resistance and migration resistance.

[0088] (Binder resin) In one embodiment, the aqueous inkjet ink of this embodiment is preferable in which the blocking resin (R1) is used as a binder resin (also referred to in this disclosure as "binder resin") because it increases the strength of the printed material and improves the blocking resistance and migration resistance of the printed material.

[0089] In this disclosure, "binder application" refers to an application that imparts strength and / or adhesion to a printing substrate to an ink film. For example, the resin that constitutes the main component of the ink film is the resin used in the binder application (binder resin). That is, in one embodiment, the binder resin in this disclosure is the resin that accounts for 50% by mass or more (preferably 60% by mass or more, particularly preferably 70% by mass or more) of the resin components contained in the aqueous inkjet ink.

[0090] When block resin (R1) is used as a binder, the type of block resin (R1) may be one of those listed above. In particular, from the viewpoint of improving the strength and barrier properties of the ink film, and improving blocking resistance and migration resistance, it is preferable to use acrylic resin as block A and acrylic resin and / or styrene resin as block B of block resin (R1).

[0091] Furthermore, when block resin (R1) is used as a binder, the molar amount of monomer units contained in block A, which constitutes the block resin (R1), is preferably 2 to 40 mol%, and particularly preferably 5 mol% or more and less than 25 mol%, relative to the total molar amount of monomer units constituting the block resin (R1). By keeping the molar amount of monomer units contained in block A, which has high hydrophilicity, within the above range, the barrier properties and water resistance of the ink film are improved, and the blocking resistance and migration resistance are improved. In addition, deterioration of the ejection stability of water-based inkjet ink can be easily prevented.

[0092] (Pigment-dispersed resin) On the other hand, in the aqueous inkjet ink of this embodiment, which contains a pigment as a coloring agent, it is also preferable to use the block resin (R1) as a resin used for pigment dispersion (hereinafter also referred to as "pigment dispersion resin"). By using the block resin (R1) as a pigment dispersion resin, the blocking resistance and migration resistance of the printed material can be improved.

[0093] Examples of pigment-dispersing resins included in the aqueous inkjet ink of this embodiment include water-insoluble resins that encapsulate pigments, and resins in which the ratio of the amount of resin adsorbed on the pigment to the amount of the target resin added is 35% by mass or more.

[0094] When the block resin (R1) is used for pigment dispersion applications, the type of block resin (R1) may be one of those listed above. In particular, from the viewpoint of improving the strength and barrier properties of the ink film, as well as improving blocking resistance and migration resistance, and the ejection stability and print quality of the water-based inkjet ink, it is preferable to use an acrylic resin and / or maleic acid resin as the A block constituting the block resin (R1), and to use one or more resins selected from the group consisting of acrylic resin, styrene resin, and polyolefin resin as the B block.

[0095] Furthermore, when block resin (R1) is used for pigment dispersion applications, the molar amount of monomer units contained in block A, which constitutes the block resin (R1), is preferably 15 to 55 mol%, and particularly preferably 25 to 50 mol%, relative to the total molar amount of monomer units constituting the block resin (R1). By keeping the molar amount of monomer units contained in block A, which has high hydrophilicity, within the above range, the dispersibility of the pigment is improved, and the ejection stability of the water-based inkjet ink is enhanced. In addition, the block resistance and migration resistance of the printed material are also improved.

[0096] The preferred content of block resin (R1) in the aqueous inkjet ink of this embodiment depends on the application in which it is used, but is preferably 0.1 to 20% by mass, more preferably 0.5 to 15% by mass, and particularly preferably 1 to 12% by mass, of the total amount of the aqueous inkjet ink.

[0097] <Other resins> The aqueous inkjet ink of this embodiment may contain resins other than the blocking resin (R1) described above (hereinafter simply referred to as "other resins"). In that case, the form of the other resin may be a water-soluble resin, a hydrosol, or an emulsion. From the viewpoint of favorably exhibiting all of the effects of the present invention described above, the content of the other resin is preferably 30% by mass or less (0% by mass, i.e., no other resin may be included) and particularly preferably 20% by mass or less (0% by mass is also acceptable) of the total amount of resin contained in the aqueous inkjet ink. In particular, if the content of the other resin is 20% by mass or less, the ejection stability, as well as the blocking resistance and migration resistance of the printed material will be good.

[0098] When the above-mentioned other resins are used for binder applications, the types of other resins used for such binder applications may be those listed above. In particular, it is preferable that one or more are selected from the group consisting of acrylic resins, urethane resins, and polyester resins.

[0099] Furthermore, when the above-mentioned other resins are used for pigment dispersion applications, the types of other resins used for such pigment dispersion applications may be those listed above. In particular, the pigment dispersion resin is preferably one or more selected from the group consisting of acrylic resins, maleic acid resins, and polyester resins.

[0100] <Pigments> The aqueous inkjet ink of this embodiment contains a pigment as a coloring agent because it yields printed materials with high density or opacity, as well as excellent lightfastness, water resistance, and other properties.

[0101] As the above-mentioned pigments, any conventionally known organic and inorganic pigments can be used, for example, pigments represented by the following color index names can be used. Specifically, as red pigments, CI Pigment Red 2, 5, 7, 9, 12, 17, 22, 23, 31, 48:1, 48:2, 48:3, 48:4, 49:1, 49:2, 57:1, 57:2, 112, 122, 123, 146, 147, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 184, 188, 202, 207, 209, 254, 255, 260, 264, 266, 269, 282; Violet pigments include CI Pigment Violet 19, 23, 29, 32, 36, 37, 42, and 50; As orange pigments, CI Pigment Orange 1, 2, 3, 5, 7, 13, 14, 15, 16, 22, 34, 36, 38, 40, 43, 47, 48, 49, 51, 52, 53, 60, 61, 62, 64, 65, 66, 69, 71, 73; As blue pigments, CI Pigment Blue 15, 15:3, 15:4, 15:6, 16, 60, 64, 79; As green pigments, CI Pigment Green 7, 10, 36, 48; As yellow pigments, CI Pigment Yellow 1, 2, 3, 5, 12, 13, 14, 16, 17, 24, 73, 74, 83, 87, 93, 94, 95, 97, 98, 109, 110, 111, 112, 120, 126, 127, 128, 129, 137, 138, 139, 147, 150, 151, 154, 155, 166, 167, 168, 170, 180, 185, 213; As black pigments, CI Pigment Black 1, 7, 11; and, Examples of white pigments include CI Pigment White 4, 5, 6, and 21. These pigments may be used individually or in combination of two or more. Furthermore, a solid solution consisting of two or more of the pigments listed above can also be used as a pigment.

[0102] The pigment content in the aqueous inkjet ink of this embodiment may be adjusted depending on the intended use of the printed material produced using the aqueous inkjet ink. In one embodiment, the pigment content of the total amount of aqueous inkjet ink is preferably 0.5 to 30% by mass. In the case of inks other than white aqueous inkjet ink (aqueous white ink), the pigment content is more preferably 1 to 15% by mass, and particularly preferably 1.5 to 10% by mass, in order to obtain printed materials with high density and excellent print quality without worsening the ejection stability of the aqueous inkjet ink. On the other hand, in the case of aqueous white ink, the pigment content is more preferably 5 to 25% by mass, and particularly preferably 10 to 20% by mass, in order to obtain printed materials with high opacity without worsening the ejection stability of the aqueous white ink.

[0103] <Water-soluble organic solvents> The aqueous inkjet ink of this embodiment preferably contains a water-soluble organic solvent. Using this water-soluble organic solvent facilitates ensuring moisture retention near the nozzles in the inkjet head, improving ejection stability through compatibilization of the acetylenediol-based surfactant (A1), and improving print quality and blocking resistance of printed materials by improving the wettability of the aqueous inkjet ink droplets. In this disclosure, "water-soluble organic solvent" refers to a compound that has a solubility of 1% by mass or more in water at 25°C and is a liquid at 25°C.

[0104] The water-soluble organic solvents in this invention include monohydric alcohols having 1 to 6 carbon atoms, such as ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, isopentanol, neopentyl alcohol, 3,3-dimethyl-1-butanol, and 3,3-dimethyl-2-butanol; Alkanediols with 3 to 6 carbon atoms, such as 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, 3-methyl-1,3-butanediol, neopentyl glycol, 1,2-hexanediol, 2-methyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, and 3-methyl-1,5-pentanediol; Polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol (provided that the number of alkylene oxide groups is 4 or less); Alkylene glycol ethers represented by the following general formula (4); Methoxybutanols such as 3-methoxy-1-butanol and 3-methoxy-3-methylbutanol; Nitrogen-containing solvents such as 2-pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; Lactone solvents such as γ-butyrolactone and ε-caprolactone; etc. can be used. Only one kind of the above-listed water-soluble organic solvents may be used, or two or more kinds may be used in combination.

[0105] General formula (4): R 3 -O-(AO) p -H

[0106] In the above general formula (4), R 3 represents an alkyl group having 1 to 4 carbon atoms which may have a branch, AO represents an ethylene oxide group and / or a propylene oxide group, and p represents an integer of 1 to 3.

[0107] (alkanediols having 3 to 6 carbon atoms) In the aqueous inkjet ink of this embodiment, among the above-listed water-soluble organic solvents, it is preferable to use alkanediols having 3 to 6 carbon atoms. Since the proportion of the hydroxyl group in alkanediols having 3 to 6 carbon atoms with respect to the molecular weight is large, the hydrophilicity is particularly high, and they can exist uniformly in the aqueous inkjet ink. On the other hand, alkanediols having 3 to 6 carbon atoms do not get overly familiar with the acetylene diol-based surfactant (A1) and do not inhibit its orientation. As a result, it is considered to contribute to the improvement of the ejection stability, while facilitating the suppression of color bleeding and color unevenness. Also, alkanediols having 3 to 6 carbon atoms have the property of being difficult to destroy the dispersion state of the pigment described later, and can be suitably used also from the point of preventing the deterioration of the storage stability of the ink.

[0108] When using C3-C6 alkanediols as the water-soluble organic solvent, their content is preferably 5-30% by mass of the total amount of aqueous inkjet ink, and more preferably 10-25% by mass. By setting the content of C3-C6 alkanediols to 5% by mass or more, the effect of the acetylenediol-based surfactant (A1) can be fully utilized, making it easier to suppress color bleeding and uneven coloring. In addition, the drying properties on the printing substrate are favorable, and printed materials with excellent blocking resistance can be obtained. On the other hand, setting the above content to 30% by mass or less improves the discharge stability.

[0109] Alkanediols with 3 to 6 carbon atoms may be used alone or in combination of two or more types. Furthermore, alkanediols with 3 to 6 carbon atoms may be used together with other water-soluble organic solvents listed above.

[0110] <Alkylene glycol ethers> In the aqueous inkjet ink of this embodiment, it is also preferable to use a compound represented by the above general formula (4) (alkylene glycol ethers) from the viewpoint of obtaining an aqueous inkjet ink with particularly excellent print quality for printed materials, and from the viewpoint of functioning as a film-forming aid for the binder resin and obtaining printed materials with excellent blocking resistance and migration resistance. Specific examples of the above alkylene glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol isopropyl ether, and dipropylene glycol monobutyl ether.

[0111] Among the compounds listed above, in the general formula (4) above, R 3 However, it is preferable to use a compound that is an alkyl group having 2 to 4 carbon atoms (although it may be branched) and in which AO is a propylene oxide group. Since such compounds have relatively high hydrophobicity, they are thought to be easily compatible with block B in block resin (R1). As a result, block resin (R1) can exist stably and uniformly in aqueous inkjet ink, improving ejection stability. In addition, alkylene glycol ethers have high potential as film-forming aids, and a uniform ink film is easily formed, significantly improving blocking resistance and migration resistance.

[0112] In the above general formula (4), R 3However, specific examples of compounds in which the alkyl group has 2 to 4 carbon atoms (although it may be branched) and AO is a propylene oxide group include propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol isopropyl ether, and dipropylene glycol monobutyl ether.

[0113] When using the above-mentioned alkylene glycol ethers, the content is preferably 1 to 15% by mass, and more preferably 3 to 10% by mass, of the total amount of aqueous inkjet ink, because it improves the print quality of printed materials and functions suitably as a film-forming aid, suppressing the occurrence of blocking and migration, while suppressing the adhesion of aqueous inkjet ink to the nozzle end face of the inkjet head and improving ejection stability. The above-mentioned alkylene glycol ethers may be used alone or in combination of two or more types. They may also be used together with C3-C6 alkanediols and / or other water-soluble organic solvents other than the C3-C6 alkanediols and alkylene glycol ethers listed above.

[0114] In this embodiment, the aqueous inkjet ink offers improved drying properties on the printing substrate, making it easy to obtain printed materials with suppressed color bleeding, uneven coloring, and blocking. Furthermore, it also exhibits excellent ejection stability. Therefore, the amount of water-soluble organic solvent with a boiling point of 235°C or higher contained in the aqueous inkjet ink is preferably 0 to 5% by mass, and more preferably 0 to 2% by mass.

[0115] In this disclosure, "boiling point" refers to the value at 1 atmosphere and can be measured, for example, using a thermal analyzer. Furthermore, the statement "content (amount) is 0% by mass" indicates that the compound in question is not included.

[0116] The total amount of water-soluble organic solvent contained in the aqueous inkjet ink of this embodiment is preferably 5 to 45% by mass of the total amount of the aqueous inkjet ink. In particular, from the viewpoint of ensuring sufficient drying even on non-permeable substrates and improving print quality, the total amount of solvent is preferably 10 to 30% by mass.

[0117] <Other ingredients> The aqueous inkjet ink of this embodiment may contain pH adjusters, preservatives, and other additives in addition to the components described above. Examples of these other additives include crosslinking agents, preservatives, ultraviolet absorbers, and infrared absorbers. For each of these components, one or more conventionally known compounds can be used.

[0118] <Water> The water contained in the aqueous inkjet ink of this embodiment is preferably ion-exchanged water and / or reverse osmosis water. Furthermore, the water content in the aqueous inkjet ink is preferably 30 to 90% by mass, and particularly preferably 45 to 85% by mass, of the total amount of aqueous inkjet ink.

[0119] <Method for manufacturing water-based inkjet ink> The aqueous inkjet ink of this embodiment can be manufactured by conventionally known methods. For example, a pigment dispersion is prepared in advance by dispersing pigment in an aqueous medium. Then, water, resin (R), acetylenediol-based surfactant (A1), water-soluble organic solvent, etc., are added to the pigment dispersion, and after thorough stirring and mixing, coarse particles are removed by methods such as filtration and centrifugation. However, the manufacturing method of the aqueous inkjet ink of this embodiment is not limited to the method described above.

[0120] For example, when block resin (R1) is used as a pigment dispersion resin, the pigment dispersion can be produced by thoroughly mixing (premixing) pigment, block resin (R1), water, and optionally other resins, water-soluble organic solvents, surfactants (A), and other components, and then performing dispersion treatment using a disperser. Media-type dispersers such as paint shakers, bead mills, and attritors, as well as media-less dispersers such as pressure homogenizers and ultrasonic dispersers, can be used as the disperser. Furthermore, when using block resin (R1) as a binder resin, block resin (R1) can be used as the resin (R) added to the pigment dispersion.

[0121] <Characteristics of water-based inkjet inks> The aqueous inkjet ink of this embodiment preferably has a viscosity of 3 to 15 mPa·s at 25°C. Within this viscosity range, droplets of the aqueous inkjet ink can be stably ejected not only from inkjet heads with ejection frequencies of approximately 4 to 10 kHz, but also from inkjet heads with high ejection frequencies of approximately 20 to 70 kHz. In particular, when the viscosity of the aqueous inkjet ink of this embodiment is 4 to 10 mPa·s at 25°C, the aqueous inkjet ink can be stably ejected even when using an inkjet head with a design resolution of 600 dpi or higher. In this disclosure, the viscosity is measured using a cone-plate type rotational viscometer (E-type viscometer, cone angle 1°34') such as the "TVE25L viscometer" manufactured by Toki Sangyo Co., Ltd., under conditions of 25°C.

[0122] To obtain an aqueous inkjet ink with excellent ejection stability and print quality, the static surface tension of the aqueous inkjet ink of this embodiment at 25°C is preferably 18 to 35 mN / m, and particularly preferably 21 to 32 mN / m. In this disclosure, the static surface tension is measured at 25°C using the Wilhelmy method (plate method) with a device such as the "Automatic Surface Tension Meter CBVP-Z" manufactured by Kyowa Interface Science Co., Ltd.

[0123] In order to achieve a high level of both ejection stability and density or opacity of the printed material, the volume-based median diameter (D50) of the pigment contained in the aqueous inkjet ink of this embodiment is preferably 30 to 450 nm, more preferably 50 to 400 nm, and particularly preferably 70 to 350 nm. In this disclosure, the volume-based median diameter (D50) is the value measured by dynamic light scattering at a 25°C environment using a particle size distribution analyzer (for example, Microtrac-Bell's "Nanotrac UPA-EX150").

[0124] <Water-based inkjet ink set> The aqueous inkjet inks of this embodiment may be used individually, but they can also be used as a set of aqueous inkjet inks, combining two or more types of aqueous inkjet inks. Examples of such sets of aqueous inkjet inks include a set of four aqueous inkjet inks (process color ink set) consisting of cyan aqueous inkjet ink (aqueous cyan ink), magenta aqueous inkjet ink (aqueous magenta ink), yellow aqueous inkjet ink (aqueous yellow ink), and black aqueous inkjet ink (aqueous black ink); a set of five aqueous inkjet inks, further comprising aqueous white ink in addition to the process color ink set; and so on. It is preferable that all aqueous inkjet inks constituting the set of aqueous inkjet inks satisfy the requirements of the embodiments of the present invention described above.

[0125] <Ink Pretreatment Solution Set> Furthermore, the aqueous inkjet ink of this embodiment, and the set of aqueous inkjet inks, can also be used in combination with a pretreatment liquid containing a flocculant (in the form of an ink-pretreatment liquid set). By applying the pretreatment liquid containing a flocculant to the printing substrate before printing with the aqueous inkjet ink, a layer (ink flocculation layer) can be formed in which the solid components contained in the aqueous inkjet ink are intentionally flocculated. By depositing the aqueous inkjet ink onto this ink flocculation layer, the coalescence and mixing of the droplets of the aqueous inkjet ink can be prevented, and the print quality of the printed material can be significantly improved. Moreover, depending on the material used in the pretreatment liquid, the adhesion, blocking resistance, and migration resistance of the printed material can also be improved.

[0126] In this disclosure, "coagulant" means a component that can disrupt the dispersion state of pigments in an aqueous inkjet ink and cause them to aggregate, and / or insolubilize the resin (R) contained in the aqueous inkjet ink and thicken the aqueous inkjet ink. The coagulant used in the pretreatment liquid that can be combined with the aqueous inkjet ink of this embodiment preferably contains one or more compounds selected from polyvalent metal salts and organic acids, from the viewpoint of significantly improving print quality. Among these, polyvalent metal salts containing carboxylate ions and carboxylic acids are preferably used from the viewpoint of improving blocking resistance. Furthermore, from the viewpoint of improving migration resistance, it is preferable to use a polyvalent metal salt as the coagulant, and Ca 2+ Mg 2+ Zn 2+ , and, Al 3+ It is even more preferable to use a polyvalent metal salt containing one or more polyvalent metal ions selected from the group consisting of the following. Furthermore, from the viewpoint of achieving good print quality, blocking resistance, and migration resistance, it is particularly preferable to select a calcium carboxylate salt and / or a magnesium carboxylate salt as the flocculant.

[0127] When polyvalent metal salts and / or organic acids are used as flocculants, the total amount of these salts is preferably 2 to 30% by mass, and particularly preferably 3 to 25% by mass, relative to the total amount of the pretreatment solution.

[0128] Furthermore, from the viewpoint of adhesion to the printing substrate, as well as blocking resistance and migration resistance, the above pretreatment liquid preferably contains a resin, and it is particularly preferable to use a polyurethane resin emulsion and / or a polyolefin resin emulsion as the resin.

[0129] In addition, the above pretreatment solution may contain water-soluble organic solvents, surfactants, and other components such as pH adjusters, defoamers, thickeners, and preservatives as appropriate. The water-soluble organic solvents and surfactants that can be used in the pretreatment solution are the same as those used for the water-based inkjet ink. Furthermore, when the pretreatment solution contains a surfactant, it is preferable that the surfactant included is an acetylenediol-based surfactant (A1) from the viewpoint of obtaining printed materials with excellent blocking resistance and migration resistance.

[0130] <Inkjet Printing Method> The aqueous inkjet ink of this embodiment is used in an inkjet printing method. A typical inkjet printing method includes a step of ejecting the aqueous inkjet ink and a drying step of the aqueous inkjet ink that has landed on the printing substrate. That is, in the above printing method, the aqueous inkjet ink of this embodiment is ejected onto the printing substrate from an inkjet head having fine nozzles (ejection step). The aqueous inkjet ink ejected onto the printing substrate is then dried by a drying mechanism (drying step).

[0131] (Discharge process) One example of an inkjet head operation method in the ejection process is the shuttle (scan) method, which ejects and records aqueous inkjet ink while scanning the inkjet head back and forth in a direction perpendicular to the transport direction of the printing substrate. Another example of an operation method is the single-pass method, which ejects and records aqueous inkjet ink as the printing substrate passes under a fixedly positioned inkjet head. The inkjet head equipped with aqueous inkjet ink in this embodiment may employ either the shuttle method or the single-pass method. Among these, the single-pass method is preferred because it is less likely to cause misalignment in the landing position of the aqueous inkjet ink droplets, thereby improving the print quality of the printed material.

[0132] Regarding the ejection method from the inkjet head, any known method can be arbitrarily selected. Examples of such ejection methods include the piezoelectric method, which utilizes the volume change of a piezoelectric element; the thermal method, which ejects water-based inkjet ink using bubbles generated by heating with a heater; and the valve method, which ejects pressurized water-based inkjet ink while opening and closing the nozzle cover (valve) with a solenoid.

[0133] The amount of aqueous inkjet ink droplets ejected from the inkjet head is preferably 0.5 to 20 picoliters, and particularly preferably 0.5 to 15 picoliters, from the viewpoint of reducing drying load and improving print quality. Furthermore, from the viewpoint of improving print quality, it is preferable to adjust the printing conditions (specifically, the drive frequency and number of inkjet heads, and the printing speed). In one embodiment, the above printing conditions may be adjusted so that the recording resolution of the printed material is preferably 600 dpi or higher, more preferably 1200 dpi or higher.

[0134] (drying process) Drying methods used in the drying process include heating drying, hot air drying, infrared (e.g., infrared with a wavelength of 700-2500 nm) drying, microwave drying, and drum drying. One or more of these methods can be arbitrarily selected and used in the above drying process. When two or more of the above drying methods are used, each drying method may be used separately (e.g., consecutively) or simultaneously in combination. For example, by using heating drying and hot air drying in combination, the water-based inkjet ink can be dried more quickly than when each method is used individually.

[0135] In particular, from the viewpoint of preventing the boiling of the liquid component in the aqueous inkjet ink and obtaining printed materials with excellent print quality, when using the heat drying method, it is preferable to set the drying temperature to 35 to 100°C. When using the hot air drying method, it is preferable to set the hot air temperature to 50 to 250°C. From a similar viewpoint, when using the infrared drying method, it is preferable that 50% or more of the integrated value of the total output of the irradiated infrared rays is in the wavelength region of 700 to 1500 nm.

[0136] <Printed material> A printed material according to one embodiment of the present invention comprises a printing substrate and a printed layer formed using the aqueous inkjet ink of this embodiment. The printed layer is formed by drying aqueous inkjet ink that has been printed in the shape of an image and / or characters. The inkjet printing method described above can be suitably used as a method for printing aqueous inkjet ink in the shape of an image and / or characters and then drying to form a printed layer. The term "image" includes solid images (images printed at 100% density so as to completely cover the surface of the printing substrate) and seamless images such as checkerboard patterns.

[0137] <Printing base material> The printing substrate on which the aqueous inkjet ink of this embodiment is printed is not particularly limited, and any known substrates such as permeable substrates, poorly permeable substrates, and non-permeable substrates can be used as desired.

[0138] In this embodiment, the permeability of the printing substrate is determined by the amount of water absorbed, measured by a dynamic scanning liquid absorber. Specifically, the amount of pure water absorbed at a contact time of 100 msec, measured by the method described below, is 1 g / m². 2 Printing substrates with a water absorption rate of less than 1 g / m² are defined as "non-permeable substrates." 2 More than 6g / m 2 Printing substrates with a water absorption rate of less than 6 g / m² are classified as "low-penetration substrates." Furthermore, the above water absorption rate is 6 g / m². 2 The printing substrate described above is referred to as a "permeable substrate." The water absorption of the printing substrate can be measured, for example, using a dynamic scanning liquid absorber (e.g., Kumagai Riki Kogyo Co., Ltd.'s "KM500win") set to the conditions shown below, with a sample of the printing substrate measuring approximately 15-20 cm square, under conditions of 23°C and 50% RH. • Measurement method: Spiral scanning (Spiral Method) ·Measurement start radius: 20mm • Measurement end radius: 60mm ·Contact time: 10~1,000msec • Sampling points: 19 (measured at approximately equal intervals relative to the square root of the contact time) • Scanning interval: 7mm • Rotary table speed switching angle: 86.3 degrees • Headbox specifications: width 5mm, slit width 1mm

[0139] Examples of permeable substrates include uncoated papers such as newsprint, medium-grade paper, fine-grade paper, and recycled paper; fabrics such as cotton, synthetic fibers, silk, hemp, and nonwoven fabrics; and leather. Among these, uncoated papers such as newsprint, medium-grade paper, fine-grade paper, and recycled paper are preferred because they yield printed materials with excellent print quality.

[0140] Examples of non-permeable and poorly permeable substrates include plastic films and sheets such as polyvinyl chloride sheets, polyethylene terephthalate (PET) films, polypropylene films, polyethylene films, polyethylene sheets, nylon films, nylon sheets, polystyrene films, polystyrene sheets, and polyvinyl alcohol films; coated papers such as coated paper, art paper, and cast paper; metals such as aluminum, iron, stainless steel, and titanium; and glass.

[0141] The printing substrates listed above may have smooth or uneven surfaces. Furthermore, the printing substrates may be transparent, translucent, or opaque. In addition, the printing substrates may be in roll form or sheet form. Moreover, two or more of the listed printing substrates may be laminated together to form a printing substrate. A release adhesive layer may be provided on the opposite side of the printed surface, or an adhesive layer may be provided on the printed surface after printing.

[0142] Surface modification, such as corona treatment and plasma treatment, may be applied to the printing surface of the printing substrates listed above. Surface modification is preferable because it improves the wettability and spreadability of the aqueous inkjet ink of this embodiment, resulting in a printed material with excellent print quality and drying properties, as well as good abrasion resistance and substrate adhesion due to the uniformity of the printed surface.

[0143] <Post-coating treatment> Printed materials produced using the aqueous inkjet ink of this embodiment can be post-coated if necessary. Specific examples of post-coating include coating or printing of a post-coating composition, or lamination using methods such as dry lamination, solvent-free lamination, or extrusion lamination. Any of these methods may be selected, or a combination of several may be used.

[0144] Furthermore, when applying a post-coating treatment to a printed material by coating and printing with a post-coating composition, at least one of the following methods can be used for coating and printing: a method that prints without contact to the printing substrate, such as inkjet printing, and a method that prints by bringing the post-coating composition into contact with the printing substrate. In addition, when selecting a method that prints the post-coating composition without contact to the printing substrate, it is preferable to use an aqueous inkjet ink (clear ink) as the post-coating composition, which is substantially free of colorant components, by removing the pigment from the aqueous inkjet ink of this embodiment, in order to improve blocking resistance and migration resistance.

[0145] Furthermore, when laminating printed materials, it is preferable that the adhesive used to laminate the sealant substrate is composed of a mixture of a polyol component and a polyisocyanate component.

[0146] The polyol component mentioned above is a resin component having multiple hydroxyl groups. Considering its coating properties, wettability and penetration to the interface of printed materials, and the laminate strength that develops after aging, polyurethane resin and polyester resin are preferably used. In particular, it is preferable that the polyol component contains polyester polyol because it exhibits good wettability to the interface of printed materials obtained by the aqueous inkjet ink of this embodiment, for example, the ink film (or, in the case of using the pretreatment liquid mentioned above, the film obtained by further drying the pretreatment liquid (pretreatment film)), and also exhibits excellent laminate strength in the laminated printed material (laminated body). The polyol component may be a single component or multiple components may be used in combination.

[0147] Furthermore, the polyisocyanate component reacts with the polyol component to form urethane bonds, thereby increasing the molecular weight of the adhesive layer and improving the laminate strength. In particular, from the viewpoint of compatibility with the polyol component, wettability to the ink film obtained by the aqueous inkjet ink of this embodiment, and the laminate strength of the laminated printed material (laminated material), it is preferable that the polyisocyanate component contains a polyether-based urethane resin with isocyanate group ends. Also, from the same viewpoint as above, it is preferable that the amount of the polyisocyanate component is 50 to 80% by mass relative to the polyol component. Note that the polyisocyanate component may be a single component or multiple components may be used in combination.

[0148] Examples of sealant substrates used in the above lamination process include polypropylene films and polyethylene films, such as CPP (unoriented polypropylene) film and linear short-chain branched polyethylene (LLDPE) film. Alternatively, a film with a metal (oxide) vapor-deposited layer, such as aluminum oxide, may be used. [Examples]

[0149] The aqueous inkjet ink of this embodiment will be described in more detail below with reference to examples and comparative examples. In the following description, "parts" and "%" refer to "parts by mass" and "% by mass," respectively, unless otherwise specified.

[0150] <Example of Pigment Dispersion Resin 1 Production> Fifty-six parts of 2-butanone were charged into a reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer. Next, 28 parts of butyl methacrylate monomer, 16 parts of methacrylic acid, 0.3 parts of 2,2'-azobisisobutyronitrile polymerization initiator, and 2.2 parts of 2-(dodecylthiocarbonothio)-isobutyric acid were added. The reaction vessel was purged with nitrogen gas, and the contents were heated to 75°C. The polymerization reaction was then carried out for 3 hours while maintaining the internal temperature at 75°C to obtain a polymer of butyl methacrylate and methacrylic acid (block A). After the polymerization reaction described above was completed, the contents were cooled to room temperature, and then 44 parts of 2-butanone, 20 parts of the monomer styrene, and 43 parts of benzyl methacrylate were added to the reaction vessel. The reaction vessel was again purged with nitrogen gas, and the contents of the reaction vessel were heated to 75°C. The polymerization reaction was then carried out for 3 hours while maintaining the internal temperature at 75°C, thereby obtaining a pigment dispersion resin 1 having an AB block structure in which a copolymer (B block) consisting of styrene and benzyl methacrylate was added to the A block. After the contents of the reaction vessel were cooled to room temperature, 9.5 parts of dimethylaminoethanol were added to neutralize the pigment dispersion resin 1. Then, 150 parts of deionized water were added. The mixture was then heated, and 2-butanone was removed by distillation by azeotrope with the deionized water. Deionized water was then added to adjust the solid content to 20% by mass, thereby obtaining an aqueous solution of pigment dispersion resin 1 (solid content 20% by mass).

[0151] The obtained pigment-dispersed resin 1 had a mass-average molecular weight of 18,000, an acid value of 59 mgKOH / g, a glass transition temperature (Tg) of 57°C, and a molecular weight distribution (PDI) of 1.4.

[0152] In this disclosure, "aqueous solution" refers to a solution comprising an aqueous medium and components dispersed and / or dissolved in the aqueous medium.

[0153] <Example of Binder Resin 1 Production> 72.4 parts of 2-butanone were charged into a reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer. The reaction vessel was then purged with nitrogen gas and heated until the contents reached 80°C. Subsequently, a mixture of monomers—10 parts styrene, 5 parts methacrylic acid, 5 parts 2-hydroxyethyl methacrylate, 15 parts stearyl methacrylate, and 65 parts methyl methacrylate—and the polymerization initiator 2,2'-azobis(methyl isobutyrate) was added dropwise over 2 hours. After the dropwise addition was complete, the polymerization reaction was carried out for 3 hours while maintaining the internal temperature at 80°C. Then, 0.6 parts of 2,2'-azobis(methyl isobutyrate) were added, and the polymerization reaction was continued for another 2 hours at 80°C to obtain a solution of binder resin 1. After cooling the above binder resin 1 solution to room temperature, 4.7 parts of dimethylaminoethanol were added to neutralize binder resin 1, and then 140 parts of deionized water were added. Subsequently, the mixture was heated, and 2-butanone was removed by distillation by azeotrope with deionized water. Then, deionized water was added to adjust the solid content concentration to 30% by mass, thereby obtaining an aqueous solution of binder resin 1 (solid content concentration 30% by mass).

[0154] The obtained binder resin 1 had a mass-average molecular weight of 17,000, an acid value of 33 mgKOH / g, a Tg of 91°C, and a molecular weight distribution (PDI) of 2.1.

[0155] <Example of Binder Resin 2 Production> Twenty parts of toluene were charged into a reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer. Next, five parts of methyl methacrylate monomer and five parts of methacrylic acid, along with 0.9 parts of 2,2'-azobisisobutyronitrile polymerization initiator and 3.6 parts of 2-(dodecylthiocarbonothio)-isobutyric acid were added. The reaction vessel was purged with nitrogen gas, and the contents were heated to 75°C. The polymerization reaction was then carried out for 3 hours while maintaining the internal temperature at 75°C to obtain a polymer of methyl methacrylate and methacrylic acid (Block A). After the polymerization reaction described above was completed, the contents were cooled to room temperature, and then 60 parts of toluene, along with 5 parts of the monomers 2-hydroxyethyl methacrylate, 60 parts of methyl methacrylate, 15 parts of stearyl methacrylate, and 10 parts of styrene, were added to the reaction vessel. After purging the inside of the reaction vessel with nitrogen gas, the contents inside the reaction vessel were heated to 75°C, and then the polymerization reaction was carried out for 3 hours while maintaining the internal temperature at 75°C, thereby obtaining a binder resin 2 having an AB block structure in which a copolymer (B block) consisting of 2-hydroxyethyl methacrylate, methyl methacrylate, stearyl methacrylate, and styrene was added to the A block. After the contents of the reaction vessel were cooled to room temperature, 6.2 parts of dimethylaminoethanol were added to neutralize the binder resin 2. Then, 200 parts of deionized water were added. The mixture was then heated, and the toluene was removed by azeotropic distillation with water. Finally, deionized water was added to adjust the solid content to 30% by mass, thereby obtaining an aqueous solution of binder resin 2 (solid content 30% by mass).

[0156] The obtained binder resin 2 had a mass-average molecular weight of 17,600, an acid value of 33 mgKOH / g, a glass transition temperature of 91°C, and a molecular weight distribution (PDI) of 1.4.

[0157] <Manufacturing examples of binder resins 3-14> Aqueous solutions (solid content concentration 30% by mass) of binder resins 3 to 14 were obtained in the same manner as for binder resin 2, except that the monomers listed in Table 1 were used.

[0158] [Table 1]

[0159] The details of the meanings of the abbreviations listed in Table 1 above are as follows: • MAA: Methacrylic acid MMA: Methyl methacrylate BMA: Butyl methacrylate • 2HEMA:2-hydroxyethyl methacrylate SMA: Stearyl methacrylate St: Styrene ·αMS:α-methylstyrene

[0160] <Example of Binder Resin 15 Manufacturing> Ninety parts of 2-butanone were charged into a reaction vessel equipped with a gas inlet tube, thermometer, condenser, and stirrer. Next, 18.5 parts of the monomer methyl methacrylate, 6.5 parts of methacrylic acid, 0.5 parts of the polymerization initiator 2,2'-azobis(2,4-dimethylvaleronitrile), and 2.0 parts of 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid were added. The reaction vessel was purged with nitrogen gas, and the contents were heated to 80°C. The polymerization reaction was then carried out for 3 hours while maintaining the internal temperature at 80°C to obtain a polymer (P1 block) of methyl methacrylate and methacrylic acid. After the polymerization reaction described above was completed, the contents were cooled to below 50°C. Then, 9.5 parts of methyl methacrylate monomer, 15 parts of butyl methacrylate monomer, 5.5 parts of cyclohexyl methacrylate monomer, and 20 parts of styrene monomer were added to the reaction vessel. After purging the reaction vessel with nitrogen gas, the contents were heated to 80°C. The internal temperature was then maintained at 80°C, and 0.5 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) were added dropwise over 5 hours while stirring the contents. After the dropwise addition was completed, the polymerization reaction was carried out for a further 3 hours while maintaining the internal temperature at 80°C, thereby adding a copolymer (P2 block) consisting of methyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, and styrene to the P1 block. After the polymerization reaction described above was completed, the contents were cooled to below 50°C. Then, 5.5 parts of the monomer 2-hydroxyethyl methacrylate, 13 parts of methyl methacrylate, 5 parts of methoxypolyethylene glycol methacrylate (approximately 4 moles of ethylene oxide groups added), and 1.5 parts of methacrylic acid were added to the reaction vessel. The reaction vessel was then purged with nitrogen gas, and the contents were heated to 80°C. The internal temperature was then maintained at 80°C, and 0.5 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) were added dropwise over 5 hours while stirring the contents. After the dropwise addition was complete, the polymerization reaction was carried out for a further 3 hours while maintaining the internal temperature at 80°C. This added a copolymer (P3 block) consisting of 2-hydroxyethyl methacrylate, methyl methacrylate, methoxypolyethylene glycol methacrylate, and methacrylic acid to the P1-P2 block, thereby obtaining a binder resin 15 having a P1-P2-P3 block structure. After the contents of the reaction vessel were cooled to room temperature, 8.4 parts of dimethylaminoethanol were added to neutralize the binder resin 15. Then, 200 parts of deionized water were added. The mixture was then heated, and 2-butanone was removed by distillation by azeotropic mixing with water. Deionized water was then added to adjust the solid content to 30% by mass, thereby obtaining an aqueous solution of binder resin 15 (solid content 30% by mass).

[0161] The obtained binder resin 15 had a mass-average molecular weight of 19,000, an acid value of 52 gKOH / g, a glass transition temperature of 72°C, and a molecular weight distribution (PDI) of 1.6. The acid values ​​of each block constituting the binder resin 15 were 170 mgKOH / g for block P1, 0 mgKOH / g for block P2, and 39 mgKOH / g for block P3. Therefore, block P1 corresponds to block A, and block P2 corresponds to block B, and the value expressed as AVA-AVB is 170.

[0162] <Synthesis of Acetylenediol-based Surfactant 1> Acetylenediol-based surfactant 1 was synthesized using the method described in Example 4 of Japanese Patent Publication No. 2001-215690. Acetylenediol-based surfactant 1 has a general formula (1) in which R 1 is a methyl group, R 2 The compound has an isobutyl group, m1+n1 is 5, and m2+n2 is 2, with ethylene oxide and propylene oxide groups added in block form. The HLB value of acetylenediol surfactant 1 was 7.8 and the molecular weight was 563.

[0163] <Synthesis of Acetylenediol-based Surfactants 2-8> Acetylenediol-based surfactants 2-8 were synthesized by using the methods described in Examples 6 and 14 of Japanese Patent Publication No. 2001-215690, and further adjusting the amounts of ethylene oxide and propylene oxide used. The structures and HLB values ​​of acetyldiol-based surfactants 2-8 are shown in Table 2.

[0164] [Table 2]

[0165] Furthermore, since acetylenediol-based surfactants 5 and 6 do not have a propylene oxide group (m2 + n2 = 0 in general formula (1)), there is no specific addition form, and therefore the "Addition Form" column in Table 2 above is left blank.

[0166] <Manufacturing of Black Pigment Dispersion K1> 450g of carbon black (PrinteX85, manufactured by Orion Engineered Carbons), 90g of acrylic resin (a random polymer of styrene / acrylic acid / behenyl acrylate = 45 / 30 / 25 (mass ratio), with all acid groups neutralized by dimethylaminoethanol, acid value approximately 230mgKOH / g, mass average molecular weight approximately 20,000), and 2,460g of water were added to a mixing container (volume 10L) equipped with a stirrer, and stirred (premixed) for 1 hour. Next, the mixture was circulated and dispersed using a "DinoMill" (volume 0.6L) manufactured by Synmaru Enterprises, filled with 1,800g of zirconia beads with a diameter of 0.5mm. The D50 of the mixture was measured at regular intervals (e.g., every hour) using the aforementioned apparatus, and the circulating dispersion was terminated when the D50 fell below 120nm, thereby producing a black pigment dispersion K1 with a solid content of 15% by mass.

[0167] <Manufacturing of Cyanide Pigment Dispersion C1> Cyanide pigment dispersion C1 with a solid content of 15% by mass was prepared using the same raw materials and method as the black pigment dispersion K1 described above, except that LIONOL BLUE 7358G (CI Pigment Blue 15:3) manufactured by Toyo Color Co., Ltd. was used as the pigment and circulating dispersion was carried out until the D50 was 150 nm or less.

[0168] <Manufacturing of black pigment dispersion K2 and cyanide pigment dispersion C2> Except for using 450 g of an aqueous solution of pigment dispersion resin 1 instead of acrylic resin, and adding 2,100 g of water, a black pigment dispersion K2 with a solid content of 15% by mass was obtained using the same materials and method as the black pigment dispersion K1 described above. Furthermore, a cyan pigment dispersion C2 with a solid content of 15% by mass was prepared using the same raw materials and method as the black pigment dispersion K2 described above, except that LIONOL BLUE 7358G (CI Pigment Blue 15:3) manufactured by Toyo Color Co., Ltd. was used as the pigment and circulating dispersion was carried out until the D50 was 150 nm or less.

[0169] <Manufacturing of water-based inkjet inks> Using the black pigment dispersions K1 and K2 and the cyan pigment dispersions C1 and C2 manufactured by the method described above, each raw material was added to a mixing container equipped with a stirrer to achieve the formulations shown in each column of Table 3. After adding the raw materials, the mixture was heated to 50°C and mixed for another hour. Finally, it was filtered through a membrane filter with a pore size of 0.8 μm to produce a water-based inkjet ink. Furthermore, the water-based inkjet inks listed in each column of Table 3 were manufactured using the black pigment dispersion and the cyan pigment dispersion, respectively. In addition, a "water-based inkjet ink set" was created by combining the black ink and the cyan ink, which had the same composition other than the pigment dispersion.

[0170] In the manufacturing of water-based inkjet inks, the raw materials were added while stirring the mixture in the mixing container. Furthermore, the components were added in the order listed in the top row of each column in Table 3. However, when manufacturing water-based inkjet inks that did not contain one or more of these components, those components were omitted, and the next component was added in the correct order. For components containing two or more raw materials, the order of addition within that component was left to the user's discretion.

[0171] [Table 3-1]

[0172] [Table 3-2]

[0173] [Table 3-3]

[0174] [Table 3-4]

[0175] The meanings of the abbreviations and product names listed in Table 3 above are as follows. In Table 3, "bp" represents the boiling point (unit: °C), "HLB" represents the HLB value, "Tg" represents the glass transition temperature (unit: °C), and "PDI" represents the molecular weight distribution. • 1,2-PD: 1,2-propanediol (boiling point: 188°C) • 2m-2,4-PentD: 2-methyl-2,4-pentanediol (boiling point: 197°C) • 1,5-PentD: 1,5-pentanediol (boiling point: 239°C) • PM: Propylene glycol monomethyl ether (boiling point: 121°C) • PnB: Propylene glycol monobutyl ether (boiling point: 170°C) • DPnP: Dipropylene glycol monopropyl ether (boiling point: 212°C) • Surfinol 440: Acetylenediol-based surfactant manufactured by Evonik Japan (in general formula (1), R 1 is a methyl group, R 2 A compound in which isobutyl group, m1+n1 is 3-4, and m2+n2 is 0; molecular weight: 380; HLB value: 8.1) • Surfinol 465: Acetylenediol-based surfactant manufactured by Evonik Japan (in general formula (1), R 1 is a methyl group, R 2 (A compound in which isobutyl group, m1+n1 is 10, m2+n2 is 0, molecular weight: 666, HLB value: 13.2) • Surfinol 485: Acetylenediol-based surfactant manufactured by Evonik Japan (in general formula (1), R 1 is a methyl group, R 2 A compound in which isobutyl group, m1+n1 is 30, and m2+n2 is 0; molecular weight 1,546; HLB value: 17.1) Nonionic K-220: Polyoxyethylene lauryl ether (HLB: 16.5, nonionic surfactant manufactured by NOF Corporation) Nonionic K-204: Polyoxyethylene lauryl ether (HLB: 9.7, nonionic surfactant manufactured by NOF Corporation) TEGO Wet 280: Siloxane-based surfactant manufactured by Evonik Japan. • BYK-3420: Siloxane-based surfactant manufactured by Big Chemie Japan Co., Ltd. • TEGO Glide 100: Siloxane-based surfactant manufactured by Evonik Japan. • TEGO Glide 440: Siloxane-based surfactant manufactured by Evonik Japan. • AQ515: AQUACER515, polyethylene wax emulsion manufactured by BIC Chemie Japan, solids content concentration 35% by mass • Proxel GXL: Dipropylene glycol aqueous solution of 1,2-benzoisothiazole-3-one (1,2-benzoisothiazole-3-one:dipropylene glycol:water = 2:6:2, preservative manufactured by Arch Chemicals)

[0176] <Manufacturing of pretreatment solution> Each raw material was added to a mixing vessel equipped with a stirrer to achieve the formulation described in each column of Table 4. After adding the ingredients, the mixture was mixed for another hour, and then filtered through a membrane filter with a pore size of 0.8 μm to produce pretreatment solutions 1 to 6.

[0177] In preparing the pretreatment solution, the raw materials were added while stirring the mixture in the mixing container. The order of addition was ion-exchanged water, coagulant, water-soluble organic solvent, activator, other components (preservative), and resin. However, for components containing two or more raw materials, the order of addition within that component was left to the user's discretion.

[0178] [Table 4]

[0179] The details of the abbreviations and product names listed in Table 4 above that were not used in Table 3 are as follows. • Superflex 460S: Polyurethane aqueous dispersion manufactured by Daiichi Kogyo Seiyaku, solid content concentration 38% by mass • Hi-Tec E-6400: Polyethylene wax emulsion manufactured by Toho Chemical Co., Ltd., solid content concentration 35% by mass • PVA-105aq: A 10% by mass aqueous solution prepared by mixing 10 parts of Kuraray Poval 5-98 (polyvinyl alcohol resin) manufactured by Kuraray Co., Ltd. with 90 parts of ion-exchanged water and heating and dissolving it at 90°C.

[0180] <Preparation of OPP film substrate with pretreatment solution> Using an OSG System Products 250-OSP-02 non-wire bar coater, the pretreatment solution prepared in Table 4 was applied to a biaxially oriented polypropylene film "OPU-1" (20 μm thick, hereinafter also simply referred to as "OPP film") manufactured by Mitsui Chemicals Tohcello Co., Ltd. to a wet film thickness of 2.0 ± 0.2 μm. After application, the OPP film was placed in a 70°C air oven and dried for 1 minute to produce an OPP film substrate with the pretreatment solution applied.

[0181] <Creating printed materials> An inkjet printing system was installed with two Kyocera inkjet heads "KJ4B-EX1200-RC" (design resolution 1,200 dpi) mounted above a conveyor belt. Next, the water-based inkjet inks listed in Table 5 were filled into each inkjet head in the order of K and C, starting from the inkjet head on the upstream side in the direction of transport of the printing substrate. Then, the OPP film substrate, which had been treated with the pre-processing solution prepared above, was fixed onto the conveyor belt, and the conveyor belt was driven at a constant speed. As the OPP film substrate passed through the inkjet head mounting area, the water-based inkjet inks were ejected at a drop volume of 2 pL each to print the image. Immediately afterward, the printed substrate was placed in a forced-air constant-temperature incubator set to 70°C and dried for 3 minutes to produce a printed material.

[0182] The following two types of printed materials were produced using the above method. Furthermore, two types of printed materials were produced for each of the water-based inkjet inks. • Solid print: A print with 100% coverage (15cm wide x 25cm long). However, only the black ink from a set of water-based inkjet inks was used to create the solid print. • Gradient print: A print created by printing an image in a 10cm wide x 25cm long area, where each water-based inkjet ink is used so that the print density changes in 10% increments between 10% and 100% along the length, and areas printed with the same print density overlap (i.e., the total print density is 20% in 20% increments, ranging from 20% to 200%).

[0183] [Examples 1-41, Comparative Examples 1-11] The printed materials produced using the method described above were used in the combinations shown in Table 5, and evaluations 1, 2, and 4 described below were performed. In addition, evaluation 3 described below was performed using the black ink from the above-mentioned aqueous inkjet ink set. The results of these evaluations are shown in Table 5. However, for Examples 37 to 41, since the same aqueous inkjet ink set as in Example 1 was used, evaluation 3 was not performed.

[0184] <Evaluation 1: Print quality (color bleeding)> Based on the printing method described above, gradient prints were produced under two different conveyor drive speed conditions: 50 m / min and 75 m / min. The print quality (color bleeding) of the resulting gradient prints was then evaluated by observing the dot shape in the areas with a total print density of 40-160% using an optical microscope at 200x magnification. The evaluation criteria were as follows, with AA, A, B, and C ratings considered usable for practical purposes. AA: In a gradient print printed at a conveyor drive speed of 75 m / min, no dot merging or dot shape inconsistency was observed in the area with a total print density of 160%. A: In gradient prints printed at a conveyor drive speed of 75 m / min, dot merging and / or dot shape unevenness were observed in areas with a total print density of 100% or more, but no dot merging or dot shape unevenness was observed in areas with a total print density of 80% or less. B: In gradient prints printed at a conveyor speed of 75 m / min, dot merging and / or unevenness in dot shape were observed even in areas with a total print coverage of 80% or less. However, in gradient prints printed at a conveyor speed of 50 m / min, no color bleeding or unevenness was observed in areas with a total print coverage of 160%. C: In gradient prints printed at a conveyor drive speed of 50 m / min, dot merging and / or dot shape unevenness were observed in areas with a total print density of 100% or more, but no dot merging or dot shape unevenness was observed in areas with a total print density of 80% or less. D: Even in areas of a gradient print printed at a conveyor drive speed of 50 m / min where the total print coverage was 80% or less, dot merging and / or dot shape non-uniformity were observed.

[0185] <Evaluation 2: Evaluation of blocking resistance> The conveyor drive speed was set to 50 m / min, and the solid printed material manufactured using the method described above was cut into 4 cm x 4 cm squares. The printed side of the squares was then placed on top of the unprinted side of the same printing substrate (OPP film) used for printing. Next, this stacked piece was used as a test specimen, and a blocking test was conducted using a constant-load permanent strain tester (CO-201, manufactured by Tester Sangyo Co., Ltd.). The conditions for the blocking test were a load of 10 kg / cm². 2 The ambient temperature was 40°C, the ambient humidity was 80%RH, and the standing time was 24 hours. After 24 hours, the test specimen was removed from the constant-load permanent strain tester, and the stacked printed substrates were instantaneously peeled off while maintaining a 90-degree angle. The blocking resistance was then evaluated based on the feel when peeling (peel resistance) and the appearance of the printed surface after peeling (visual inspection). The evaluation criteria were as follows, with AA, A, B, and C ratings considered usable in practice. (Evaluation Criteria) AA: There was no peeling resistance, and no portion of the ink film adhered to the non-printed surface of the printing substrate. A: Although there was slight resistance during peeling, no portion of the ink film adhered to the non-printed surface of the printing substrate. B: A portion of the ink film was adhering to the non-printed surface of the printed substrate, and the extent of this was less than 5% of the area of ​​the overlapping portion. C: A portion of the ink film was adhering to the non-printed surface of the printed substrate, and the extent of this was between 5% and 10% of the overlapping area. D: A portion of the ink film was adhering to the non-printed surface of the printed substrate, and the extent of this adhering was more than 10% of the area of ​​the overlapping portion.

[0186] <Evaluation 3: Evaluation of dispensing stability> One of the inkjet heads in the inkjet printing machine used to produce the printed material was filled with black ink from a set of water-based inkjet inks. After printing a nozzle check pattern and confirming that there was no deflection or nozzle failure, 300 solid prints were produced continuously using the method described above. Subsequently, the nozzle check pattern was printed again, and the number of nozzles exhibiting deflection or nozzle failure was visually counted to evaluate the ejection stability. The evaluation criteria were as follows, with A, B, and C ratings considered to be for practical use. (Evaluation Criteria) A: There was absolutely no deflection or nozzle leak. B: There were no nozzle failures at all, but deflection occurred in 1 to 5 nozzles. C: There were no nozzle failures, but deflection occurred in 6 to 9 nozzles. D: Nozzle failure occurred, or deflection occurred in 10 or more nozzles.

[0187] <Rating 4: Migration Resistance> The conveyor drive speed was set to 50 m / min, and a solid print was obtained using the method described above. Next, using a solvent-free test coater, a solvent-free laminating adhesive (Toyo Morton Co., Ltd. "EA-N373A / B") was applied to the printed surface (ink film side) of the prepared solid print at a temperature of 60°C, a coating speed of 50 m / min, and an application rate of 2 g / m². 2The coating was applied under the specified conditions. Furthermore, the coated surface of the solvent-free laminate adhesive and the corona-treated surface of the CPP film (Futamura Chemical Co., Ltd.'s unoriented polypropylene film "FHK2" (thickness 25 μm)) were placed facing each other, and then left to stand (age) for one day in an environment of 40°C and 80% RH to cure the solvent-free laminate adhesive composition and produce a laminated product. The laminated material obtained above was placed in a migration cell (Gassner Glastechnik's "MigraCell® MC60") with the CPP film facing upwards, and then 50 mL of 95% ethanol solution was added. The contact area between the laminated material and the ethanol was 0.5 dm². 2 Subsequently, the migration cells were left standing in a 40°C oven for 10 days, after which the 95% ethanol solution was removed and concentrated to 2 mL or less under conditions of 40°C and 50 mmHg. If the amount of concentrated ethanol solution was less than 2 mL, it was placed in a 2 mL volumetric flask and filled up with 95% ethanol. Then, the amount of acetylene-based surfactant (A1) contained per 1 mL of the concentrated and filled-up ethanol solution was used as a sample, and the migration resistance was evaluated by quantifying the amount of acetylene-based surfactant (A1) contained in 1 mL of the concentrated and filled-up ethanol solution using a gas chromatograph-mass spectrometer (Agilent 7890A / 5975C, manufactured by Agilent Technologies). The evaluation criteria were as follows, with AA, A, B, and C ratings being considered usable in practice. AA: The elution amount of acetylene-based surfactant was 0.1 μg / mL or less. A: When the elution amount of acetylene-based surfactant is greater than 0.1 μg / mL and less than or equal to 1.0 μg / mL there were B: The amount of acetylene-based surfactant eluted was greater than 1.0 μg and less than or equal to 2.0 μg / mL. C: The amount of acetylene-based surfactant eluted was greater than 2.0 μg and less than or equal to 3.0 μg / mL. D: The elution amount of acetylene-based surfactant was greater than 3.0 μg / mL.

[0188] [Table 5-1]

[0189] [Table 5-2]

[0190] As shown in Table 5 above, Examples 1 to 41, which used the aqueous inkjet ink set having the configuration of this embodiment, showed superior ejection stability compared to Comparative Examples 1 to 11. Furthermore, the printed materials had good print quality and excellent resistance to blocking and migration.

Claims

1. A water-based inkjet ink comprising a pigment, a surfactant (A), and a resin (R), The surfactant (A) comprises an acetylenediol-based surfactant (A1) having a structure represented by the following general formula (1), a molecular weight of 400 to 650, and an HLB value of 7 to 12. The resin (R) comprises a block resin (R1) having a glass transition temperature of 50 to 130°C and an acid value of 3 to 60 mgKOH / g. A water-based inkjet ink in which, among the acid values ​​of each block constituting the block resin (R1), the highest is AVA (mgKOH / g) and the lowest is AVB (mgKOH / g), and the value expressed as AVA - AVB is between 50 and 450. General formula (1): 【Chemistry 1】 (In general formula (1), R 1 and R 2 Each of the following represents an alkyl group having 1 to 5 carbon atoms, which may be branched: EO represents an ethylene oxide group, and PO represents a propylene oxide group. Furthermore, m1 and n1 each represent integers from 1 to 10, and m2 and n2 each represent integers from 0 to 5. However, if m2 + n2 > 0, the addition pattern of the ethylene oxide group and propylene oxide group within the square brackets may be either block or random.

2. The aqueous inkjet ink according to claim 1, wherein the molecular weight distribution (PDI) of the block resin (R1) is 1.0 to 1.

8.

3. The surfactant (A) further comprises a nonionic surfactant (A2), The aqueous inkjet ink according to claim 1 or 2, wherein the nonionic surfactant (A2) includes a siloxane-based surfactant.

4. The aqueous inkjet ink according to claim 3, wherein the nonionic surfactant (A2) further comprises an acetylenediol-based surfactant having an HLB value greater than 12 and less than or equal to 19, and / or a polyoxyalkylene monoalkyl ether-based surfactant having an HLB value greater than 12 and less than or equal to 19.

5. A printed article comprising an aqueous inkjet ink according to claim 1 or 2 printed on a printing substrate.

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