Aqueous inkjet ink and printed matter

Abstract

To provide an aqueous inkjet ink which, even when printed on a low-absorbency printing substrate, can stably obtain printed matter that exhibits no beading but has excellent blocking resistance and migration resistance, where the ink also has good continuous ejection properties.SOLUTION: An aqueous inkjet ink comprises a pigment, a binder resin, a water-soluble organic solvent, an unmodified acetylenediol-based surfactant (A1), and an alkylene oxide-modified acetylenediol-based surfactant (A2) having an HLB value of 4-10, where the contents of the unmodified acetylenediol-based surfactant (A1) and the alkylene oxide-modified acetylenediol-based surfactant (A2) are prescribed and the ratio between the content of the unmodified acetylenediol-based surfactant (A1) and the content of the alkylene oxide-modified acetylenediol-based surfactant (A2) is 10-5,000.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous inkjet ink and a printed matter produced using the aqueous inkjet ink.

Background Art

[0002] With the trend towards smaller print runs and diverse market needs in printing, the popularity of digital printing methods has been rapidly advancing. Since digital printing methods do not require a printing plate, they are capable of handling small print runs, and it is possible to reduce printing costs and miniaturize printing devices.

[0003] An inkjet printing method, which is a type of digital printing method, involves flying and landing minute droplets of ink from an inkjet head onto a printing substrate (hereinafter also simply referred to as "substrate" in the present application), and printing an image or characters (hereinafter collectively also referred to as "printed matter". Note that the above "image" also includes seamless images such as solid images and checkerboard patterns) on the printing substrate. Compared with other digital printing methods, it is excellent in terms of the size and cost of the printing device, ease of full-colorization, etc., and in recent years, its use has also been increasing in industrial printing applications.

[0004] Inks used in the inkjet printing method cover a wide range, such as oil-based, solvent-based, active energy ray-curable, and water-based. Heretofore, solvent-based and active energy ray-curable inks have been used in industrial printing applications. However, in recent years, due to considerations and responses regarding environmental and human hazards, the demand for water-based inks has been increasing.

[0005] In recent years, there has been an increasing demand for the packaging market as a development destination for aqueous inks (referred to as "aqueous inkjet inks" in this application and simply as "inks" hereinafter) used in inkjet printing methods. In the packaging market, printing is performed on printing substrates such as paper containers, labels, and packaging films. Also, as materials for these printing substrates, there are low-absorbency ones such as coated paper and art paper, as well as non-absorbent ones such as polypropylene films, polyethylene terephthalate films, and nylon films. Therefore, when promoting the development of aqueous inkjet inks for the packaging market, it is required that printed matter with excellent color reproducibility and printing image quality, and furthermore, characteristics that can withstand actual use can be produced for both low-absorbency substrates and non-absorbent substrates.

[0006] On the other hand, most of the aqueous inkjet inks that have existed so far are for printing on highly absorbent substrates such as plain paper and special paper. When such aqueous inkjet inks are used, especially on non-absorbent substrates, since the aqueous inkjet inks are not absorbed by penetrating into the substrate, the drying of the droplets of the aqueous inkjet inks that have landed on the substrate becomes insufficient, and a phenomenon (beading) occurs in which the droplets attract and combine with each other. When beading occurs, the deterioration of solid filling (the occurrence of areas where the ink does not adhere in a printed matter with a print rate of 100%), uneven density, color mixing bleeding, etc. occur, resulting in a significant decrease in the printing image quality.

[0007] As a method for suppressing the above beading, a method of reducing the surface tension of the aqueous inkjet ink is known. Further, a surfactant is often used as the material for reducing the surface tension. In particular, in order to sufficiently reduce the surface tension of the aqueous inkjet ink immediately after landing on the printing substrate, it is preferable to select a compound having a small molecular weight and a high orientation rate to the droplet surface (gas-liquid interface) as the surfactant. However, generally, such a surfactant is hardly compatible with water. Therefore, for example, in the aqueous inkjet ink present near the nozzles of the inkjet head, there is a risk that the surfactant will be intensively oriented at the gas-liquid interface. Then, the surface tension of the aqueous inkjet ink present near the nozzle is locally reduced, and a phenomenon occurs in which the aqueous inkjet ink overflows from the nozzle to the outside. In particular, when continuous ejection occurs and such ink overflow from the nozzle occurs and progresses, it becomes a factor of ejection failure (deterioration of continuous ejection property) such as nozzle clogging or flight deviation.

[0008] In addition, surfactants with a low molecular weight and a high orientation rate will be present in large amounts on the surface of the droplet, that is, on the surface of the layer (ink layer) formed by drying the printed ink. Therefore, for example, when the printed matter is wound up and stored, there is also a risk of blocking (a phenomenon in which a part of the ink layer is taken by the printing substrate when peeling off the printing substrate attached to the ink layer).

[0009] Furthermore, when manufacturing a laminate containing an ink layer inside and using it as a package such as a pouch (bag), the low molecular weight and high orientation rate surfactant present on the surface of the ink layer and / or bleeding (a phenomenon in which a certain component oozes out to the layer surface over time) to the surface of the ink layer may pass through each layer constituting the laminate and reach the surface of the laminate (migration). In particular, when the surfactant migrates to the surface in contact with the content, it may have an adverse effect on the safety of the content. Therefore, for example, when using the laminate in food packaging applications or cosmetic packaging applications, it may become a fatal problem.

[0010] As described above, conventionally, it has been an extremely difficult situation to simultaneously solve all of print image quality improvement, continuous dischargeability, blocking resistance, and migration resistance.

[0011] As an example of suppressing beading when printing on a low-absorbing substrate or a non-absorbing substrate by controlling the type and amount of surfactant, Patent Document 1 discloses a silicone-based surfactant having a specific structure and a nonionic surfactant having an HLB value of 6.0 or more and less than 12.0 (for example, polyoxyalkylene alkyl ether-based surfactants such as "Lutensol XL40" manufactured by BASF and "GENAPOL EP2564" manufactured by Clariant) ink composition (set); Patent Document 2 discloses an ink containing a polyoxyalkylene alkyl ether-based surfactant having a specific structure and an HLB value of 5.0 to 13.0 determined by actual measurement; and Patent Document 3 discloses an ink in which a silicone-based surfactant and a fluorine-based surfactant are used in combination with a glycol ether-based organic solvent, respectively. On the other hand, in Patent Documents 1 to 3 described above, specifically, a low-absorbing substrate such as coated paper is used for the evaluation of beading. As described above, when an aqueous inkjet ink is printed on a non-absorbing substrate such as a resin film, the aqueous inkjet ink does not penetrate into the substrate at all, so beading is more likely to occur than when printed on a low-absorbing substrate. Regarding the aqueous inkjet inks specifically disclosed in Patent Documents 1 to 3, they were not sufficient in terms of improving beading when printed on a non-absorbing substrate.

[0012] In addition, Patent Document 4 discloses an inkjet recording method using an aqueous ink containing a specific acetylene glycol (acetylene diol-based surfactant) and a nonionic surfactant, and defining the blending amounts and blending ratios of the respective components. Further, in the main examples of the aqueous ink specifically disclosed in Patent Document 4, 2,4,7,9-tetramethyl-5-decyne-4,7-diol is used as the above acetylene glycol, and a polyoxyalkylene alkyl ether-based surfactant such as polyoxyethylene lauryl ether (the number of added moles of ethylene oxide groups is 12) is used as the above nonionic surfactant. Here, since the above 2,4,7,9-tetramethyl-5-decyne-4,7-diol corresponds to the above "compound having a small molecular weight and a high orientation rate at the droplet surface (gas-liquid interface)", the above aqueous ink is considered to be effective in terms of suppressing beading. On the other hand, in Patent Document 4, it cannot be said that sufficient consideration has been given particularly regarding blocking resistance and migration resistance, and actually, the blocking resistance and migration resistance of the above aqueous ink were not satisfactory.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0014] The present invention has been made to solve the above problems, and an object thereof is to stably obtain a printed matter that has no beading, is excellent in blocking resistance and migration resistance even when printed on a low-absorbency printing substrate, and also has good continuous dischargeability, and to provide an aqueous inkjet ink.

Means for Solving the Problems

[0015] As a result of intensive studies by the present inventors, it has been found that all of the above-described problems can be solved simultaneously and at a high level by an aqueous inkjet ink having the following configuration.

[0016] That is, one embodiment of the present invention relates to an aqueous inkjet ink shown in the following [1] to [5], and a printed matter manufactured using the above aqueous inkjet ink shown in the following [6]. [1] An aqueous inkjet ink containing a pigment, a binder resin, a water-soluble organic solvent, and an acetylene diol-based surfactant (A), wherein the acetylene diol-based surfactant (A) includes an unmodified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10, the content of the unmodified acetylene diol-based surfactant (A1) is 10 to 2000 ppm with respect to the total amount of the aqueous inkjet ink, the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) is 0.2 to 5% by mass with respect to the total amount of the aqueous inkjet ink, and the ratio [surfactant (A2) / surfactant (A1)] of the content of the unmodified acetylene diol-based surfactant (A1) to the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) is in the range of 10 to 5000, an aqueous inkjet ink. [2] The aqueous inkjet ink according to [1], further comprising a nonionic surfactant (B) other than the acetylene diol-based surfactant. [3] The aqueous inkjet ink according to [2], wherein the mass factor addition HLB value calculated by the following formula (1) is 0.3 to 2.0. Formula (1):

Number

Advantages of the Invention

[0017] According to the present invention, even when printed on a low-absorbency printing substrate, a printed matter without beading, excellent in blocking resistance and migration resistance can be stably obtained, and the continuous ejection property is also good. It has become possible to provide an aqueous inkjet ink.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the aqueous inkjet ink of the present invention (hereinafter, also simply referred to as "the ink of the present invention") and a printed matter obtained by printing the aqueous inkjet ink will be described. The present invention is not limited to the following description content, and also includes various modified examples implemented without departing from the gist of the invention.

[0019] Generally, water, which is the main solvent of aqueous inkjet ink, has a high surface tension and is difficult to spread wet on a printing substrate. In addition, when droplets of the aqueous inkjet ink landing on the printing substrate are in a state where the surface tension is high and they are not dried and come into contact with adjacent undried droplets, a force acts on each droplet in the direction of reducing the surface area, so that the droplets attract each other and beading occurs. As described above, when beading occurs, the solid filling deteriorates, the density becomes uneven, color mixing and bleeding occur, etc., and the printed image quality is significantly reduced.

[0020] Also, as a method for suppressing beading, it is preferable to use a surfactant having a small molecular weight and a high orientation rate to the droplet surface (gas-liquid interface). However, since such a surfactant is hardly compatible with water, for example, in the aqueous inkjet ink present near the nozzles of the inkjet head, there is a risk that the surfactant is concentratedly oriented at the gas-liquid interface and the ink overflows from the nozzles to the outside. Such a phenomenon is a factor in the deterioration of the continuous ejection property.

[0021] Furthermore, surfactants with low molecular weight and high orientation speed are present in large quantities on the surface of the ink layer. Then, due to the movement of surfactant molecules caused by heat or humidity, etc., blocking may occur. In addition, these surfactants may bleed to the surface of the laminate including the ink layer, which may cause migration.

[0022] On the other hand, in order to suppress the deterioration of continuous discharge property and the occurrence of blocking and migration, if the amount of the surfactant with low molecular weight and high orientation speed is reduced, then the occurrence of beading described above cannot be suppressed, and it becomes difficult to obtain a printed matter with good print quality.

[0023] As described above, surfactants with low molecular weight and high orientation speed are effective in improving print quality, but on the other hand, a trade-off occurs with characteristics such as continuous discharge property, blocking resistance, and migration resistance.

[0024] Therefore, in order to solve the above-mentioned trade-off, as a result of the inventors' intensive studies, it has been found that an unmodified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having a specific HLB value are used in combination at a specific ratio and the respective blending amounts are specified, leading to the present invention. Although the details of the mechanism by which the above-mentioned problems can be preferably solved by the aqueous inkjet ink having the above configuration are unclear, the inventors speculate as follows.

[0025] First, the ink of the present invention contains an acetylene diol-based surfactant. Generally, since the acetylene group contained in the acetylene diol-based surfactant does not undergo bond rotation, the molecular structure is less likely to be deformed compared to surfactants consisting only of single bonds, such as polyoxyethylene alkyl ether-based surfactants, etc., and even with a small amount of addition, the expected effects are exhibited.

[0026] Further, the ink of the present invention contains, as an acetylene diol-based surfactant, an unmodified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10. Among these, the unmodified acetylene diol-based surfactant (A1) corresponds to the above-mentioned "surfactant having a low molecular weight and a high orientation rate", and in the case of the ink of the present invention, it is an essential material from the viewpoint of suppressing beading. Further, from the viewpoint that not only the suppression of beading but also the continuous discharge property, and the blocking resistance and migration resistance of the printed matter are all in good states by the combined use with other materials described later, in the present invention, the content of the unmodified acetylene diol-based surfactant (A1) is in the range of 10 to 2,000 ppm in the total amount of the ink.

[0027] Furthermore, in the ink of the present invention, the alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10 is used in the ink in an amount of 0.2 to 5% by mass and in a range of 10 to 5,000 times the content of the unmodified acetylene diol-based surfactant (A1). Although the detailed principle is not clear, when the alkylene oxide-modified acetylene diol-based surfactant (A2) is used in the above content and ratio, the alkylene oxide-modified acetylene diol-based surfactant (A2) forms an emulsified state with the unmodified acetylene diol-based surfactant (A1) having a similar structure, and the excessive orientation of the unmodified acetylene diol-based surfactant (A1) is suppressed. Also, since the blending amount of the unmodified acetylene diol-based surfactant (A1), which is a low molecular weight surfactant, itself is small, the ink of the present invention can prevent the deterioration of the continuous discharge property and can obtain a printed matter and a laminate in which blocking and migration are less likely to occur.

[0028] Furthermore, some non-modified acetylene diol surfactants (A1) are oriented at the gas-liquid interface together with the alkylene oxide-modified acetylene diol surfactant (A2) that forms an emulsified state. As a result, in the ink of the present invention, an effect equal to or greater than the amount of the non-modified acetylene diol surfactant (A1) added to the ink is exhibited, and further suppression of beading becomes possible.

[0029] As described above, in order to simultaneously and highly solve the above-described problems, the ink having the configuration of the present invention is essential.

[0030] In addition to the above-described acetylene diol surfactant, the ink of the present invention can further use a nonionic surfactant (B) other than the acetylene diol surfactant. The nonionic surfactant (B) can be expected to have an effect of greatly reducing the static surface tension. Therefore, it is considered that the nonionic surfactant (B) functions effectively in a time region later than "from when the ink droplet lands on the printing substrate to several tens of milliseconds", which is the time region in which the non-modified acetylene diol surfactant (A1) mainly functions. Since the behavior in this time region mainly affects wet spreading and improvement of image density, the combined use of the nonionic surfactant (B) can significantly improve the finally obtained printing image quality. Also, although the detailed principle is unknown, it is considered that by using the nonionic surfactant (B) and the acetylene diol surfactant in combination, an interaction acts between them and they can act like a lump of surfactant. As a result, during continuous ejection, it is considered that the nonionic surfactant (B) prevents the orientation of the non-modified acetylene diol surfactant (A1) at the gas-liquid interface, similar to the alkylene oxide-modified acetylene diol surfactant (A2). As a result, the overflow of the ink from the nozzle is suppressed, and further improvement in continuous ejection performance becomes possible.

[0031] Furthermore, the nonionic surfactant (B) present on the surface of the ink layer can reduce the surface energy of the ink layer surface. Therefore, even if another printing substrate or the like adheres to the surface, the adhesion of the printing substrate can be reduced, and the blocking resistance can be improved. In addition, as described above, in the ink of the present invention, since the surfactant is considered to exist in a lump, the surfactant is less likely to bleed to the surface of the ink layer, and it is considered that migration can be prevented.

[0032] Note that the water-based inkjet inks specifically disclosed in Patent Documents 1 to 3 are different from the ink of the present invention in that they do not contain any acetylene diol-based surfactants. Further, the water-based inkjet ink specifically disclosed in Patent Document 4 is different from the ink of the present invention in that the content of the unmodified acetylene diol-based surfactant (A1) (the “(A) component” in the examples of Patent Document 4) greatly exceeds 2000 ppm, or in that it does not contain any of the unmodified acetylene diol-based surfactants (A1).

[0033] Subsequently, the main components constituting the ink of the present invention will be described below.

[0034] <Unmodified acetylene diol-based surfactant (A1)> As described above, the unmodified acetylene glycol-based surfactant (A1) has a low molecular weight, further low hydrophilicity, and a high orientation rate at the gas-liquid interface. In addition, it can reduce the surface tension of the ink immediately after landing on the printing substrate and suppress beading.

[0035] In the present invention, the non-modified acetylene glycol-based surfactant (A1) is contained in an amount of 10 to 2,000 ppm in the total amount of the ink. The content of the non-modified acetylene glycol-based surfactant (A1) is preferably 50 to 1,000 ppm, more preferably 50 to 300 ppm. By using it within the above range and further in combination with the surfactants described later, beading is suppressed and solid filling is improved, so that a printed matter having good print quality can be obtained. In addition, since the blending amount is small in the first place, deterioration of continuous dischargeability hardly occurs, and blocking and migration in the printed matter can also be prevented.

[0036] Specific examples of the non-modified acetylene diol-based surfactant (A1) that can be used in the present invention include 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, hexadeca-8-yne-7,10-diol, 4,7-dipropyl-deca-5-yne-4,7-diol, 6,9-dimethyl-tetradeca-7-yne-6,9-diol, 3,6-diisopropyl-2,7-dimethylocta-4-yne-3,6-diol, octadeca-9-yne-8,11-diol, 7,10-dimethylhexadeca-8-yne-7,10-diol, 5,8-dibutyldodeca-6-yne-5,8-diol, 4,7-diisobutyl-2,9-dimethyl-deca-5-yne-4,7-diol, 5,14-diethyl-8,11-dimethyloctadeca-9-yne-8,11-diol, and the like. Among them, from the viewpoint of compatibility with other materials in the ink of the present invention, it is preferable to use 2,4,7,9-tetramethyl-5-decyne-4,7-diol and / or 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol. Note that only one of the above compounds may be used, or two or more thereof may be used in combination. In addition, the above compounds may be those synthesized by a conventionally known method, or commercially available products may be used. Examples of commercially available products include Surfynol 104, Surfynol DF110D, Surfynol 82 manufactured by Evonik Corporation, and Acetylenol E00 manufactured by Kawaken Fine Chemicals Co., Ltd.

[0037] <Alkylene Oxide-Modified Acetylene Diol-Based Surfactant (A2)> In the ink of the present invention, an alkylene oxide-modified acetylene diol-based surfactant (A2) is used together with an unmodified acetylene diol-based surfactant (A1). As described above, the alkylene oxide-modified acetylene diol-based surfactant (A2) emulsifies the unmodified acetylene diol-based surfactant (A1) and also exhibits its own surfactant performance, thereby enabling the production of a printed matter without beading and having excellent blocking resistance and migration resistance. Furthermore, an ink with excellent continuous dischargeability can be obtained. From this perspective, the HLB value of the alkylene oxide-modified acetylene diol-based surfactant (A2) is 4 to 10, preferably 7 to 9. When the HLB value is within the above range, it is possible to particularly suppress beading in the printed matter and improve the continuous dischargeability.

[0038] The HLB (Hydrophile-Lipophile Balance) value is one of the parameters representing the hydrophilic and hydrophobic properties of a material. Note that the smaller the HLB value, the higher the hydrophobicity of the material, and the larger the HLB value, the higher the hydrophilicity of the material. As methods for obtaining the HLB value, there are a method of actual measurement by experiment and a method of calculation from the molecular structure. As the method of calculation from the molecular structure, there are the Griffin method, the Davis method, the Kawakami method, etc. In the present invention, except for the case of the silicone-based surfactant described later, the value calculated using the Griffin method is used as the HLB value.

[0039] The Griffin method is a method generally used for non-ionic materials and is obtained by the following formula (2) using the molecular weight of the target material.

[0040] Formula (2): HLB value = 20 × (sum of molecular weights of hydrophilic parts) ÷ (molecular weight of the material)

[0041] On the other hand, in the case of the silicon-based surfactant described below, since it is generally a mixture containing many compounds, as the HLB value, the value measured by the method described on page 324 of "Surfactant Handbook" (edited by Ichiro Nishi et al., Industrial Publishing Co., Ltd., 1960) is used.

[0042] To explain the specific measurement method, after dissolving 0.5 g of the target material in 5 mL of ethanol, while stirring the solution, titrate it at 25 °C using a 2 mass% aqueous phenol solution. Then, take the point where the above solution becomes turbid as the end point, and use the amount of the aqueous phenol solution dropped until the end point (denoted as A (mL)) to calculate the HLB value by the following formula (3).

[0043] Formula (3): HLB value = 0.89 × A + 1.11

[0044] The addition amount of the alkylene oxide-modified acetylene diol-based surfactant (A2) with an HLB value of 4 to 10 is 0.2 to 5 mass% based on the total amount of the ink. From the viewpoints of improving the continuous discharge property and suppressing beading and blocking in the printed matter, the above addition amount is preferably 0.5 to 3 mass%, more preferably 0.8 to 2.5 mass%. Also, from the viewpoint of forming a suitable emulsified state with the unmodified acetylene diol-based surfactant (A1) and assisting the function of the unmodified acetylene diol-based surfactant (A1), improving the continuous discharge property, and further preventing beading, blocking, and migration in the printed matter, the ratio of the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) to the content of the unmodified acetylene diol-based surfactant (A1) is 10 to 5000, preferably 30 to 500, more preferably 50 to 300.

[0045] Specific examples of the above alkylene oxide-modified acetylene diol-based surfactant (A2) include compounds represented by the following general formula (4).

[0046] General formula (4): [Chemical formula]

[0047] In general formula (4), R 1 and R 2 each represent an alkyl group having 1 to 5 carbon atoms which may have a branch, EO represents an ethylene oxide group, and PO represents a propylene oxide group. Also, m1, m2, n1, and n2 each represent an integer from 0 to 30, and m1 + n1 + m2 + n2 is an integer from 1 to 120. However, the addition pattern of the ethylene oxide groups and propylene oxide groups within [ ] may be either block or random.

[0048] The molecular weight of the alkylene oxide-modified acetylene diol-based surfactant (A2) having the structure represented by the above general formula (4) is preferably from 300 to 1,200, more preferably from 350 to 900, and even more preferably from 400 to 700. The acetylene diol-based surfactant (A2) having a molecular weight within the above range has a high orientation rate at the gas-liquid interface similar to the unmodified acetylene diol-based surfactant (A1), so that it is easy to suppress beading, and furthermore, blocking and the like can also be prevented. Note that the molecular weight of the above alkylene oxide-modified acetylene diol-based surfactant (A2) refers to the formula weight and can be obtained by calculation.

[0049] As the alkylene oxide-modified acetylene diol-based surfactant represented by the above general formula (4), those synthesized by a conventionally known method may be used, or commercially available products may be used. Examples of commercially available products of the compound represented by general formula (4) include Surfynol 420, Surfynol 440, Surfynol 465, Surfynol 485, Surfynol 2502, Dynol 604, 607 manufactured by Evonik; Orfin series manufactured by Nissin Chemical Industry Co., Ltd.; Acetylenol E13T, E40, E60, E100, E200, etc. manufactured by Kawaken Fine Chemicals Co., Ltd.

[0050] <Nonionic surfactant (B)> As described above, in the present invention, in addition to the acetylene diol-based surfactant (A), a nonionic surfactant (B) other than the acetylene diol-based surfactant can be used in combination. By using the nonionic surfactant (B), an interaction acts between the nonionic surfactant (B) and the acetylene diol-based surfactant (A), and they act like a single surfactant, thereby further improving the continuous discharge property and preventing blocking and migration in the printed matter. Further, since the nonionic surfactant (B) gradually orientates at the gas-liquid interface as compared with the acetylene diol-based surfactant (A), it is possible to promote the wet spreading of the ink droplet after several tens of milliseconds from when the ink droplet lands on the printing substrate, and it is also possible to uniformly wet-spread the ink droplet, so that the print quality of the printed matter can be improved.

[0051] The HLB value of the nonionic surfactant (B) is preferably from 6 to 14, more preferably from 8 to 11. If the HLB value is within the above range, a strong interaction acts with the alkylene oxide-modified acetylene diol-based surfactant (A2), and a suitable emulsified state is formed, so that the continuous discharge property is improved and it is considered that a printed matter in which blocking and migration do not occur can be obtained.

[0052] Furthermore, from the viewpoint that the interaction between the acetylene diol-based surfactant (A) and the nonionic surfactant (B) can be strengthened and a suitable emulsified state can be created, resulting in good continuous discharge property and anti-blocking property, the mass factor addition HLB value calculated by the above formula (1) is preferably from 0.3 to 2.0, more preferably from 0.5 to 1.5, and still more preferably from 0.8 to 1.3. The HLB value is a value determined by the structure of the surfactant molecule, etc. In order to evaluate the influence of the entire surfactant present in the ink, in the above formula (1), after multiplying the HLB value by the blending amount of the surfactant, that is, the amount of the above surfactant molecule, the sum is taken for comparison.

[0053] The content of the nonionic surfactant (B) in the present invention is preferably 0.3 to 3% by mass, more preferably 0.5 to 2% by mass, in the total amount of the ink. Further, the ratio of the content of the nonionic surfactant (B) to the total amount of the content of the unmodified acetylene diol-based surfactant (A1) and the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) (the value represented by "content of nonionic surfactant (B) / {content of acetylene diol-based surfactant (A1) + content of acetylene diol-based surfactant (A2)}") is preferably 0.3 to 2.0, more preferably 0.5 to 1.5. When the content of the nonionic surfactant (B) and the ratio of the above content are within the above ranges, it is easy for the surfactants to form an emulsion state and function as a lump of surfactants, so that the continuous discharge property is good, and a printed matter without blocking and migration can be obtained.

[0054] In the present invention, the nonionic surfactant (B) may be synthesized by a conventionally known method or a commercially available product may be used. Examples of the type of the nonionic surfactant (B) include acetylene monoalcohol-based surfactants, silicone-based surfactants, fluorine-based surfactants, polyoxyalkylene alkyl ether-based surfactants, polyoxyalkylene aryl ether-based surfactants, polyalkylene glycol alkylate-based surfactants, and the like. These compounds may be used alone or in combination of two or more.

[0055] Among them, in the present invention, from the viewpoints of being likely to interact with the acetylene glycol-based surfactant (A) and being able to easily reduce the surface energy of the ink layer and reduce blocking, it is particularly preferable to include a silicone-based surfactant as the nonionic surfactant (B).

[0056] The silicone-based surfactant preferably used in the present invention is a compound represented by the following general formula (5).

[0057] General formula (5): [Chem.]

[0058] In general formula (5), p is an integer of 0 or more, and q is an integer of 1 or more. Also, R 3 is a methyl group or a structure represented by the following general formula (6), and R 4 is an alkyl group having 1 to 6 carbon atoms or a structure represented by the following general formula (6). However, when R 3 is a methyl group, p is 0.

[0059] General formula (6): [Chem.]

[0060] In general formula (6), r is an integer from 1 to 6, s is an integer from 0 to 50, and t is an integer from 0 to 50. However, s + t is 1 or more. Also, R 5 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a (meth)acrylic group. The addition pattern of the ethylene oxide group and the propylene oxide group in [ ] may be block or random.

[0061] The silicone surfactant in the present invention may be synthesized by a conventionally known method or a commercially available product may be used. Examples of commercially available products include SF8428, FZ-2162, 8032 ADDITIVE, SH3749, FZ-77, L-7001, L-7002, FZ-2104, FZ-2110, F-2123, SH8400, SH3773M manufactured by Toray Dow Corning; BYK-345, BYK-346, BYK-347, BYK-348, BYK-349, BYK-3420 manufactured by BYK Chemie; TEGO Wet250, TEGO Wet260, TEGO Wet270, TEGO Wet280, TEGO Glide100, TEGO Glide410, TEGO Glide432, TEGO Glide435, TEGO Glide440, TEGO Glide450, TEGO Twin 4000, TEGO Twin 4100, TEGO Twin 4200 manufactured by Evonik; KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-640, KF-642, KF-643 manufactured by Shin-Etsu Chemical Co., Ltd.; Silface SAG series of Nisshin Chemical Industry Co., Ltd., etc. These commercially available products may be used alone or in combination of two or more.

[0062] In order for the acetylene diol-based surfactant (A) to behave like a single surfactant, it is preferable that an interaction occurs between the acetylene diol-based surfactant (A). On the other hand, from the viewpoint of further improving the continuous discharge property and the improvement of solid filling in the printed matter, it is preferable that the acetylene diol-based surfactant (A) is compatible to some extent. From the above viewpoints, it is preferable to use two or more silicone surfactants in combination as the nonionic surfactant (B). Further, as the two or more silicone surfactants, it is particularly preferable to use a combination of those having HLB values measured by the above-described method that differ by 2 or more.

[0063] In the present invention, a polyoxyalkylene alkyl ether surfactant can also be used as the nonionic surfactant (B). The polyoxyalkylene alkyl ether surfactant has good compatibility with water and acetylene diol surfactants, and can improve the printing image quality such as suppressing beading without affecting these materials.

[0064] As the polyoxyalkylene alkyl ether surfactant, for example, a compound in which the number of moles of added ethylene oxide groups and / or propylene oxide groups is 5 to 100 moles and the number of carbon atoms of the terminal hydrocarbon group is 6 to 22 can be used. The terminal hydrocarbon group may be, for example, a linear alkyl group (which may have a branched structure), a linear alkenyl group (which may have a branched structure), an alicyclic alkyl group (to which one or more alkyl groups may be added), or an aromatic group (to which one or more alkyl groups may be added). Examples of commercially available products of polyoxyalkylene alkyl ether surfactants include Emulgen series such as Emulgen 104P, 105, 106, 108, 109P, 120, 123P, 150, 210, 220, 306P, 320P, 350 (manufactured by Kao Corporation), Braunon series such as Braunon EL-1502.2, 1505, 1507, 1509, 1515, 1521, 1530, 1540P, CH-302L, 305, 310L, 315L, 320L, 325L, 330L, 340, SR-702L, 705, 707, 711, 715, 720, 730, 750F, BE-5, 10, 20, 30, BN-3 (manufactured by Aoki Yushi Kogyo Co., Ltd.), Nonion series such as Nonion K-204, 220, 230, 2100W, P-208, 210, 213, E-202, 205, 212, 215, 230, S-202, 207, 215, 220, EH-204, 208, ID-203, 206, 209 (manufactured by NOF Corporation), Lutensol series such as Lutensol XL40, 50, 60, 70, 80, 90, XP30, 40, 50, 60, 70, 80, 90, 100 (manufactured by BASF SE), Newcol series such as Newcol 2302, 2303, 2305, 2308, 2310, 2320, 2360 (manufactured by Nippon Emulsion Co., Ltd.), and the like. Only one of the above-listed products may be used, or two or more thereof may be used in combination. Furthermore, as the polyoxyalkylene alkyl ether surfactant, those synthesized by conventionally known synthesis methods may be used.

[0065] <Water-soluble organic solvent> In the present invention, a water-soluble organic solvent is used for improving continuous ejection performance by ensuring moisture retention on the inkjet head, preventing beading by improving the compatibility of the above-described surfactant, etc. In the present application, the "water-soluble organic solvent" refers to a substance having a solubility in water at 25°C of 1 mass% or more and being a liquid at 25°C.

[0066] As the water-soluble organic solvent in the present invention, monohydric alcohols having 1 to 6 carbon atoms such as ethanol, propanol, isopropanol, butanol, isobutanol, tert-butanol, isopentanol, dimethylbutanol; alkanediols having 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, 1,2-hexanediol; polyalkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol; alkylene glycol ethers represented by the following general formula (7); methoxybutanols such as 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol; nitrogen-containing solvents such as 2-pyrrolidone, N-methylpyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide; lactone solvents such as γ-butyrolactone, ε-caprolactone; etc. can be used. The above water-soluble organic solvents may be used alone or in combination of two or more.

[0067] General formula (7): R 6 -O-(AO) u -H

[0068] In the above general formula (7), R 6represents 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 u represents an integer of 1 to 3.

[0069] ≪1,2 - Propanediol≫ In the present invention, among the water - soluble organic solvents shown above, it is preferable to use 1,2 - propanediol. Since 1,2 - propanediol has a large proportion of hydroxyl groups with respect to its molecular weight, it has particularly high hydrophilicity and can be uniformly present in the aqueous ink - jet ink. On the other hand, 1,2 - propanediol does not overly associate with the acetylene glycol - type surfactant (A) and the nonionic surfactant (B), so it does not inhibit the orientation of these surfactants. As a result, it is considered that beading can be suppressed. In addition, since the boiling point is moderately low at 188°C, it not only suppresses the drying of the ink on the nozzle and improves the continuous ejection property, but also volatilizes quickly after printing, resulting in an ink excellent in drying property and anti - blocking property. In addition, 1,2 - propanediol also has the property of being difficult to disrupt the dispersion state of the pigment described later, can prevent the deterioration of the storage stability of the ink, and as a result, can also be suitably used from the point of further improving the continuous ejection property.

[0070] When using 1,2 - propanediol as the water - soluble organic solvent, its content is preferably 5 to 30% by mass in the total amount of the ink, and more preferably 10 to 25% by mass. By setting the content of 1,2 - propanediol to 5% by mass or more, the effect of the surfactant can be fully exerted, so that beading suppression becomes easy. In addition, the drying property on non - absorbent substrates becomes suitable, and a printed matter excellent in anti - blocking property can be obtained. On the other hand, by setting the above - mentioned content to 30% by mass or less, the continuous ejection property is improved. Note that 1,2 - propanediol may be used together with water - soluble organic solvents other than the 1,2 - propanediol listed above.

[0071] ≪Specific alkylene glycol ethers≫ In the present invention, from the viewpoint of obtaining an ink having particularly excellent drying properties and obtaining a printed matter having excellent blocking resistance by functioning as a film-forming aid for a surfactant, among the compounds represented by the above general formula (7), 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, and dipropylene glycol monopropyl ether, it is also preferable to use one or more alkylene glycol ethers selected from the group consisting of (hereinafter also referred to as "specific alkylene glycol ethers" in the present application).

[0072] When using the above specific alkylene glycol ethers, from the viewpoint of achieving both improvement in drying properties on a non-absorbent substrate and improvement in continuous dischargeability by suppressing ink sticking at the nozzle interface, the content thereof is preferably 1 to 15% by mass, more preferably 3 to 10% by mass in the total amount of the inkjet ink. The above propylene glycol ethers may be used alone or in combination of two or more. Further, it may be used together with 1,2-propanediol and / or a water-soluble organic solvent other than 1,2-propanediol and the specific alkylene glycol ethers listed above.

[0073] In the present invention, from the point that a printed matter having excellent drying properties even on a non-absorbent substrate and not causing beading and blocking can be obtained, and further from the point that an ink having excellent continuous dischargeability can be obtained, the amount of the water-soluble organic solvent having a boiling point of 235°C or higher contained in the ink is preferably 0 to 5% by mass, more preferably 0 to 2% by mass.

[0074] In addition, the "boiling point" in this application is the value under 1 atm, and can be measured using, for example, a thermal analyzer. Further, the description "the content (blending amount) is 0% by mass" indicates that the target compound is not contained.

[0075] The total content of the water-soluble organic solvent contained in the aqueous inkjet ink of the present invention is preferably 5 to 40% by mass based on the total amount of the ink. Among them, from the viewpoint of ensuring sufficient drying property even on a non-absorbent substrate, the total blending amount is more preferably 10 to 35% by mass.

[0076] <Binder resin> In the present invention, a binder resin is used because the abrasion resistance, blocking resistance, migration resistance, etc. of the printed matter can be remarkably improved.

[0077] Generally, as the binder resin used in aqueous inkjet ink, water-soluble resins, as well as hydrosols and emulsions, which are each a kind of water-insoluble resin, are known. Here, the "water-soluble resin" refers to a resin in which a 1% by mass aqueous mixture of the target pigment dispersion resin is transparent to the naked eye under the condition of 25°C. The "hydrosol" refers to a form in which acidic and / or basic functional groups are present in the resin structure among "water-insoluble resins" (resins that are not water-soluble resins) and are dispersed in a dispersion medium without using an emulsifier such as a surfactant or a polymer. On the other hand, the "emulsion" refers to a form in which the above emulsifier is adsorbed and / or bonded to the resin surface and is forcibly dispersed in a dispersion medium. In this application, the above hydrosol and the above emulsion are also collectively referred to as "resin fine particles".

[0078] ≪Water-soluble resin≫ In one embodiment, in the present invention, it is preferable to use a water-soluble resin and / or a hydrosol as the binder resin. These resins are compatible with an aqueous medium (a medium composed of a liquid containing at least water) without using an emulsifier, and at least a part of the above resins swells and / or dissolves in the above aqueous medium. Therefore, near the nozzles of the inkjet head, clogging due to precipitation of the above resins is less likely to occur, and the continuous discharge property is excellent. Further, since these resins can function as a compatibilizer for the non-modified acetylene diol-based surfactant (A1), the non-modified acetylene diol-based surfactant (A1) is uniformly oriented at the gas-liquid interface, and the occurrence of beading in the printed matter can also be suppressed.

[0079] Examples of the types of resins that can be used as the water-soluble resin and the hydrosol include acrylic resins, urethane resins, and polyester resins. Among them, considering the storage stability and continuous discharge property of the ink, as well as the rub resistance of the printed matter, acrylic resins are preferably used.

[0080] In addition, the "acrylic resin" in the present application refers to a resin using at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters as the polymerizable monomer (styrene-based monomers may be further used).

[0081] In the present invention, as the water-soluble resin, a resin synthesized by a conventionally known method or a commercially available product may be used. There is no particular limitation on its configuration, and for example, resins having a random structure, a block structure, a comb structure, a star structure, etc. can be arbitrarily used.

[0082] When a water-soluble resin is used as the binder resin, the weight-average molecular weight is preferably in the range of 5,000 or more and 50,000 or less, and more preferably in the range of 10,000 or more and 40,000 or less. By setting the weight-average molecular weight to 5,000 or more, the abrasion resistance of the printed matter is improved, and it becomes easier to suppress beading. Further, by setting the weight-average molecular weight to 50,000 or less, the continuous ejection property from the inkjet head becomes good.

[0083] Incidentally, the weight-average molecular weight of the resin can be measured by a conventional method. For example, it is a value measured as the weight-average molecular weight in terms of polystyrene measured using a TSKgel column (manufactured by Tosoh Corporation) and GPC (manufactured by Tosoh Corporation, HLC-8120GPC) equipped with an RI detector, with THF used as the developing solvent.

[0084] The acid value is also important when selecting a water-soluble resin. When a water-soluble resin is used as the binder resin, the acid value is preferably 5 to 80 mgKOH / g, and more preferably 15 to 50 mgKOH / g. By setting the acid value to 5 mgKOH / g or more, even if the resin solidifies near the nozzle of the inkjet head, it can be dissolved again in the ink, so clogging of the nozzle is easily suppressed and the continuous ejection property is improved. Further, if the acid value is 80 mgKOH / g or less, a printed matter excellent in water resistance and abrasion resistance can be obtained, and it becomes easy to function as a compatibilizer for the non-modified acetylene diol-based surfactant (A1), so a printed matter without beading is easily obtained.

[0085] The "acid value of the resin" is the number of milligrams of potassium hydroxide (KOH) required to neutralize the acid groups contained in 1 g of the resin. In the present application, as the acid value, a value calculated by the following method is used. For example, when the resin contains Wa mass% of a polymerizable monomer having va acid groups and a molecular weight of Ma in the polymerizable monomers constituting the resin, the acid value (mgKOH / g) is obtained by the following formula (8).

[0086] Formula (8): (Acid value) = {(va × na × Wa) ÷ (100 × Ma)} × 56.11 × 1000

[0087] In the above formula (8), the numerical value "56.11" is the molecular weight of potassium hydroxide.

[0088] The content of the water-soluble resin is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass, and still more preferably 2 to 6% by mass based on the total amount of the ink. If the content of the water-soluble resin is 0.5% by mass or more, the unmodified acetylene diol-based surfactant (A1) can be sufficiently solubilized, the storage stability of the ink is improved, and beading in the printed matter can also be suppressed. If it is 10% by mass or less, the viscosity of the ink can be suppressed within a suitable range, and an ink excellent in continuous dischargeability can be obtained.

[0089] ≪Resin fine particles≫ On the other hand, generally, resin fine particles such as hydrosols and emulsions have a higher molecular weight compared to water-soluble resins. Also, when the same amount of resin is blended, the resin fine particles can lower the viscosity of the ink compared to the case of water-soluble resins. Therefore, by using resin fine particles, a larger amount of resin can be contained in the ink, and it becomes easier to improve the scratch resistance, blocking resistance, and migration resistance of the printed matter.

[0090] Among the resins used as resin fine particles, examples of the types of resins that can be used as emulsions include acrylic resins, urethane resins, polyester resins, styrene-butadiene resins, acrylonitrile-butadiene resins, vinyl chloride resins, polyolefin resins, etc. Among them, considering the points that it is easy to maintain the storage stability of the ink and to improve the scratch resistance and blocking resistance of the printed matter, emulsions of one or more resins selected from the group consisting of acrylic, urethane, polyester, and polyolefin resins can be preferably used. When using a hydrosol as the resin fine particles, from the viewpoint of improving the rub resistance and blocking resistance of the printed matter, it is preferable to use one or more resins selected from the group consisting of acrylic resins, urethane resins, and polyester resins. Further considering the above-mentioned viewpoint of improving continuous dischargeability, it is particularly preferable to use an acrylic resin.

[0091] However, when the binder resin in the ink is resin fine particles, especially when using an emulsion, it is necessary to consider the minimum film-forming temperature (MFT) of the resin fine particles. When using resin fine particles with a low MFT, depending on the water-soluble organic solvent added to the ink, the MFT of the resin fine particles may further decrease, and even at room temperature, the resin fine particles may adhere near the nozzles of the inkjet head, causing clogging. Especially in the case of an emulsion, once the film is formed, it is difficult to redissolve it in the ink, so there is a risk that the continuous dischargeability will be impaired by the adhered emulsion. To avoid such problems, it is preferable to adjust the type and amount of the polymerizable monomer constituting the emulsion so that the MFT of the emulsion is 60°C or higher. Also, when using a hydrosol as the resin fine particles, the possibility of deterioration of continuous dischargeability is not as high as in the case of an emulsion. On the other hand, by using a hydrosol with an MFT of 60°C or higher, it is possible to reduce the factors that can deteriorate continuous dischargeability. Therefore, also in the case of a hydrosol, it is preferable to set the MFT to 60°C or higher.

[0092] The above MFT can be measured, for example, by an MFT tester manufactured by Tester Sangyo Co., Ltd.

[0093] When using an emulsion, its content is preferably 2 to 15% by mass, more preferably 4 to 8% by mass, based on the total amount of the ink. If the content of the emulsion is 2% by mass or more, the rub resistance and blocking resistance are improved. If it is 15% by mass or less, the viscosity of the ink can be suppressed within a suitable range, and the ink will have excellent continuous dischargeability.

[0094] <Pigment> The ink of the present invention contains a pigment. As the pigment, an inorganic pigment and / or an organic pigment can be arbitrarily used. Further, these pigments may be used alone or in combination of two or more. The content of the pigment is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, and still more preferably 2 to 7% by mass based on the total mass of the ink.

[0095] When an inorganic pigment is used as the pigment, specific examples include titanium oxide, zinc white, zinc sulfide, lead white, calcium carbonate, precipitated barium sulfate, white carbon, alumina white, kaolin clay, talc, bentonite, carbon black, black iron oxide, cadmium red, red iron oxide, molybdenum red, molybdate orange, chrome vermilion, lead yellow, cadmium yellow, yellow iron oxide, titanium yellow, chromium oxide, viridian, titanium cobalt green, cobalt green, cobalt chromium green, victoria green, ultramarine, dark blue, cobalt blue, cerulean blue, cobalt silica blue, cobalt zinc silica blue, manganese violet, cobalt violet, etc. can be used.

[0096] Among the above-listed carbon blacks, those produced by the furnace method or the channel method can be used. Among them, carbon black produced by the furnace method or the channel method, having a primary particle diameter of 11 to 40 nm and a specific surface area by the BET method of 50 to 400 m 2Those having properties such as a volatile content of 0.5 to 10% and a pH of 2 to 10 are preferred. As commercially available products having such specifications, for example, No. 33, 40, 45, 52, 900, 2200B, 2300, MA7, MA8, MCF88 (manufactured by Mitsubishi Chemical Corporation), RAVEN1255 (manufactured by Birla Carbon), REGAL330R, 400R, 660R, MOGUL L, ELFTEX415 (manufactured by Cabot Corporation), NIPex90, NIPex150T, NIPex160IQ, NIPex170IQ, NIPex75, PrinteX35, PrinteX85, PrinteX90, PrinteX95, PrinteXU (manufactured by Orion Engineered Carbons), etc. are available, and all can be preferably used.

[0097] On the other hand, examples of organic pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, quinophthalone pigments, dye lake pigments, fluorescent pigments, and the like.

[0098] Specifically, when exemplified by the Color Index, as cyan pigments, C.I. Pigment Blue 1, 2, 3, 15:1, 15:3, 15:4, 15:6, 16, 21, 22, 60, 64, etc. can be mentioned.

[0099] Also, as magenta pigments, C.I. Pigment Red 5, 7, 9, 12, 31, 48, 49, 52, 53, 57, 97, 112, 120, 122, 146, 147, 149, 150, 168, 170, 176, 177, 178, 179, 184, 185, 188, 202, 206, 207, 209, 238, 242, 254, 255, 264, 269, 282, C.I. Pigment Violet 19, 23, 29, 30, 32, 36, 37, 38, 40, 50, etc. can be mentioned.

[0100] Examples of yellow pigments include C.I.Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 74, 83, 86, 93, 94, 95, 109, 110, 117, 120, 125, 128, 129, 137, 138, 139, 147, 148, 150, 151, 154, 155, 166, 168, 180, 185, 213, etc.

[0101] Examples of black pigments include aniline black (C.I.Pigment Black 1), perylene black (C.I.Pigment Black 31, 32), azomethine azo black, etc. In addition, a plurality of the above-mentioned cyan pigments, magenta pigments, yellow pigments, and colored pigments such as the following brown pigments and orange pigments can be mixed to form a black pigment.

[0102] Examples of pigments other than the above include C.I.Pigment Green 7, 10, 36, C.I.Pigment Brown 3, 5, 25, 26, C.I.Pigment Orange 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, 62, 63, 64, 71, etc.

[0103] <Pigment dispersion resin> In order to maintain the storage stability and continuous dischargeability of the ink for a long period, the above pigments are preferably used after being dispersed in the ink. As methods for stably dispersing and holding the pigments in the ink, (1) a method of coating at least a part of the pigment surface with a pigment dispersion resin, (2) a method of adsorbing a water-soluble and / or water-dispersible surfactant on the pigment surface, (3) a method of chemically and / or physically introducing a hydrophilic functional group onto the pigment surface and dispersing it in the ink without a pigment dispersion resin or a surfactant (self-dispersing pigment), etc. can be mentioned.

[0104] The ink of the present invention preferably selects the method (1) among the above, that is, the method using a pigment-dispersing resin. This is because by selecting and examining the composition, weight-average molecular weight, etc. of the polymerizable monomer constituting the resin, the pigment coating ability and charge of the pigment-dispersing resin can be easily adjusted. Therefore, even for fine pigments, it is possible to stably impart storage stability, and furthermore, a printed matter excellent in continuous dischargeability, color development property, and color reproducibility can be obtained.

[0105] Examples of the above pigment-dispersing resin include acrylic resins, styrene-(anhydrous) maleic acid resins, α-olefin-(anhydrous) maleic acid resins, urethane resins, polyester resins, and the like. Among them, from the viewpoint of strengthening the adsorption to the pigment and improving the storage stability and continuous dischargeability, it is preferable to use one or more resins selected from acrylic resins, styrene-(anhydrous) maleic acid resins, and α-olefin-(anhydrous) maleic acid resins. In the present application, “(anhydrous) maleic acid” represents maleic acid and / or maleic anhydride.

[0106] When a water-soluble resin is used as the pigment-dispersing resin, its acid value is preferably 60 to 400 mgKOH / g. By setting the acid value within the above range, the dispersion stability of the pigment, as well as the storage stability and continuous dischargeability of the ink, can be made suitable. Further, as the above acid value, more preferably it is 100 to 350 mgKOH / g, and still more preferably it is 120 to 300 mgKOH / g. On the other hand, when a water-insoluble resin is used as the pigment-dispersing resin, its acid value is preferably 0 to 100 mgKOH / g, more preferably 5 to 90 mgKOH / g, and still more preferably 10 to 80 mgKOH / g. If the acid value is within the above range, a printed matter excellent in drying property and blocking resistance can be obtained, and the dispersion stability of the pigment and the continuous dischargeability of the ink are also improved. The acid value of the pigment-dispersing resin can be measured in the same manner as in the case of the above binder resin.

[0107] The weight average molecular weight of the pigment dispersion resin is preferably from 5,000 to 100,000. By setting the weight average molecular weight to 5,000 or more, the dispersion stability of the pigment and the storage stability of the ink can be made suitable. Further, by setting the weight average molecular weight to 100,000 or less, the continuous ejection property can be made good. The above weight average molecular weight is more preferably in the range of 10,000 to 50,000, and still more preferably in the range of 15,000 to 30,000. Incidentally, the weight average molecular weight of the pigment dispersion resin can be measured in the same manner as in the case of the binder resin described above.

[0108] The blending amount of the pigment dispersion resin with respect to the blending amount of the pigment is preferably from 1 to 120% by mass. By setting the ratio of the pigment dispersion resin to 1% by mass or more with respect to the blending amount of the pigment, the viscosity of the ink can be suppressed within a range suitable for use in inkjet printing applications, and the continuous ejection property is improved. Further, by setting it to 120% by mass or less, the dispersion stability of the pigment and the storage stability of the ink can be made good. The blending amount of the pigment dispersion resin with respect to the blending amount of the pigment is more preferably from 2 to 100% by mass, and still more preferably from 5 to 50% by mass.

[0109] <Water> The water contained in the ink of the present invention is preferably ion-exchanged water (deionized water), rather than general water containing various ions.

[0110] The amount of water contained in the ink of the present invention is preferably in the range of 20 to 90% by mass with respect to the total amount of the ink.

[0111] <Other components> Further, in addition to the above components, the ink of the present invention can appropriately use additives such as a pH adjuster, an ultraviolet absorber, and a preservative in order to impart desired physical property values as necessary. The addition amount of these additives is preferably from 0.01% by mass to 10% by mass with respect to the total mass of the ink.

[0112] <Method for producing ink> Examples of the method for producing the ink of the present invention containing the above-described components include the following method. However, the method for producing the ink of the present invention is not limited to the following.

[0113] First, a pigment-dispersed resin aqueous solution in which a pigment-dispersed resin and water are mixed is produced. Next, a pigment and, if necessary, a water-soluble organic solvent or the like are added to the pigment-dispersed resin aqueous solution, and after premixing (pre-mixing) by mixing and stirring, a dispersion treatment is performed using a dispersion means described later. Further, if necessary, a centrifugation treatment or the like is performed to remove coarse particles, thereby obtaining a pigment dispersion. Thereafter, an unmodified acetylene diol-based surfactant (A1), an alkylene oxide-modified acetylene diol-based surfactant (A2), a binder resin, a water-soluble organic solvent, water, and, if necessary, a nonionic surfactant (B) and other components are added to the pigment dispersion and mixed and stirred well. Then, the obtained mixture is filtered to remove coarse particles, whereby the ink of the present invention can be obtained.

[0114] In the present application, the "aqueous solution" refers to a solution containing an aqueous solvent and components dispersed and / or dissolved in the aqueous solvent.

[0115] As described in the above method for producing the ink, it is effective to perform a premixing treatment before the dispersion treatment. By the premixing treatment, the wetting spreadability of the pigment surface is improved, and the adsorption of the pigment-dispersed resin to the pigment surface is promoted, so it can be preferably carried out.

[0116] Moreover, the disperser that can be used for the dispersion treatment of the pigment may be any commonly used disperser. For example, a ball mill, a roll mill, a sand mill, a bead mill, a nanomizer, etc. can be mentioned. Among them, a bead mill is preferably used. Examples of the bead mill include a super mill, a sand grinder, an agitator mill, a Glen mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).

[0117] Since the ink of the present invention is for inkjet printing, from the viewpoint of preventing clogging at the nozzles and the like, it is preferable to use a pigment having an optimal particle size distribution. As a method for obtaining a pigment having a desired particle size distribution, there are a method of reducing the size of the grinding media of the disperser mentioned above, a method of increasing the filling rate of the grinding media, a method of lengthening the dispersion treatment time, a method of classifying with a filter, a centrifuge, etc. after the dispersion treatment, and combinations of these methods. The particle size distribution of the ink can be measured using, for example, a NanoTrac UPA-EX150 manufactured by Microtrac Bell Co., Ltd.

[0118] <Ink set> The ink of the present invention may be used alone, but can also be used as an ink set combining a plurality of colors according to the application. The combination is not particularly limited, but a full-color image can be obtained by using three colors of cyan, yellow, and magenta. In addition, by adding black ink, the black color feeling can be improved and the visibility of characters and the like can be increased. Furthermore, by adding colors such as orange and green, it is also possible to improve color reproducibility. When printing on a printing substrate other than white, a clear image can be obtained by using white ink in combination. Also, an ink set containing, as a constituent, an ink (clear ink) substantially free of a colorant component obtained by excluding the pigment from the ink of the present invention may be used.

[0119] <Ink - pretreatment liquid set> The aqueous inkjet ink of the present invention can also be used in the form of an ink - pretreatment liquid set in combination with a pretreatment liquid containing a flocculant. By applying the pretreatment liquid containing a flocculant onto the printing substrate, a layer (ink flocculation layer) for intentionally aggregating the solid components contained in the ink can be formed. Then, by landing the ink of the present invention on the ink flocculation layer, bleeding between ink droplets and unevenness in density can be prevented, and the printing image quality of the printed matter can be significantly improved. Furthermore, depending on the material used for the pretreatment liquid, the adhesion and blocking resistance of the printed matter can also be improved.

[0120] As used herein, the "flocculant" refers to a component contained in an aqueous inkjet ink that can disrupt and aggregate the dispersed state of pigments and / or insolubilize the resin contained in the aqueous inkjet ink to thicken the aqueous inkjet ink. From the perspective of significantly improving the printing quality, the flocculant used in the pretreatment liquid combined with the ink of the present invention preferably contains at least one selected from metal salts and cationic polymer compounds. Among them, from the perspective of obtaining excellent printing quality, it is preferable to use a metal salt as the flocculant, and Ca 2+ 、Mg 2+ 、Zn 2+ 、and Al 3+ It is particularly preferable to contain a salt of one or more polyvalent metal ions selected from the group consisting of. When a metal salt is used as the flocculant, its content is preferably 2 to 30% by mass, and particularly preferably 3 to 25% by mass, based on the total amount of the pretreatment liquid.

[0121] In addition, water-soluble organic solvents, surfactants, pH adjusters, defoamers, thickeners, preservatives, etc. can be appropriately added to the pretreatment liquid. The water-soluble organic solvents and surfactants that can be used in the pretreatment liquid are the same as those in the case of the above ink. When the pretreatment liquid contains a surfactant, from the perspective of obtaining a printed matter with excellent blocking resistance and migration resistance, it is preferable that the pretreatment liquid contains an unmodified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10.

[0122] <Printing substrate> As described above, the ink of the present invention can be particularly preferably used for non-absorbent substrates such as films. Specifically, polyolefin resins such as polyethylene, biaxially stretched polypropylene (OPP), and unstretched polypropylene (CPP); polyester resins such as polyethylene terephthalate (PET), polycarbonate, and polylactic acid; polystyrene resins such as polystyrene, AS resin, and ABS resin; polyamide resins such as nylon; chlorine-containing resins such as polyvinyl chloride and polyvinylidene chloride; cellophane; or films or sheets made of these composite materials can be used. These printing substrates may be subjected to surface treatments such as corona treatment or plasma treatment. Further, a precoating treatment may be performed with a precoating composition containing one or more resins selected from the group consisting of urethane resins, acrylic resins, and olefin resins (however, different from the pretreatment liquid described above).

[0123] <Method for manufacturing printed matter> The ink of the present invention is used in a printing method in which the ink is ejected from the nozzles of an inkjet head and droplets of the ink are attached onto a substrate.

[0124] Further, after applying the ink of the present invention onto a substrate, it is preferable to dry the ink on the substrate by a drying mechanism. Examples of the drying method used in the drying mechanism include a heat drying method, a hot air drying method, an infrared ray (for example, infrared ray with a wavelength of 700 to 2500 nm) drying method, a microwave drying method, and a drum drying method. Also, the above drying methods may be used alone, used successively in plurality, or used in combination simultaneously. For example, by combining a heat drying method and a hot air drying method, the ink can be dried faster than when each is used alone.

[0125] <Postcoating treatment> The printed matter produced using the ink of the present invention can be post-coated on the printing surface as needed. Specific examples of the post-coating treatment include coating or printing with a post-coating composition, and lamination processing such as dry lamination, solventless lamination, and extrusion lamination. Any of them can be selected, or a plurality of them can be combined.

[0126] When the printed matter is post-coated by applying and printing the post-coating composition, as the above coating and printing methods, either a method of printing non-contact with the printing substrate like inkjet printing or a method of printing by bringing the post-coating composition into contact with the printing substrate can be adopted. Further, when selecting a method of printing the post-coating composition non-contact with the printing substrate, as the above post-coating composition, it is preferable to use an ink (clear ink) obtained by excluding the pigment from the ink of the present invention and substantially not containing a colorant component.

[0127] When laminating the printed matter, the adhesive used for laminating the sealant substrate is preferably composed of a mixture of a polyol component and a polyisocyanate component.

[0128] The above polyol component is a resin component having a plurality of hydroxyl groups. In view of coatability, wet spreading and penetration properties to the printed matter interface, and lamination strength exhibited after aging, polyurethane resins and polyester resins are preferably used. Among them, since the wet spreading property with respect to the interface of the printed matter obtained by the ink of the present invention, for example, the printing layer (printed part) or the pretreatment liquid layer (non-printed part) is good, and the lamination strength of the laminated printed matter (laminate) is also excellent, it is preferable that the polyol component contains polyester polyol. Note that the above polyol component may be a single component or a plurality of components may be used in combination.

[0129] The polyisocyanate component reacts with the above polyol component to form a urethane bond, thereby increasing the molecular weight of the adhesive layer and improving the laminating strength. Among them, from the viewpoints of compatibility with the polyol component, wetting spreadability of the ink of the present invention with respect to the interface of the printed matter obtained, and laminating strength of the laminated printed matter (laminate), it is preferable that the above polyisocyanate component contains a polyether-based urethane resin having an isocyanate group at the terminal. Further, from the same viewpoints as above, the blending amount of the above polyisocyanate component is preferably 50 to 80% by mass with respect to the polyol component. Note that the above polyisocyanate component may be a single component or a plurality of components may be used in combination.

[0130] Examples of the sealant base material used for the above laminating process include polypropylene films and polyethylene films such as CPP films and linear short-chain branched polyethylene (LLDPE) films. Further, a film formed with a metal (oxide) vapor deposition layer such as aluminum oxide may also be used.

Examples

[0131] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0132] <Production Example of Pigment Dispersion Resin Solution 1> 90 parts of butanol was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, and the inside of the reaction vessel was replaced with nitrogen gas. Next, after heating until the inside of the reaction vessel reached 110°C, a mixture of 30 parts of acrylic acid, 35 parts of behenyl acrylate, and 35 parts of styrene, which are polymerizable monomers; and 4 parts of V-601 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), which is a polymerization initiator, was added dropwise into the above reaction vessel over 2 hours. After the completion of the dropwise addition, the polymerization reaction was continued for 3 hours while maintaining the internal temperature at 110°C. Then, 0.4 part of V-601 was added, and the polymerization reaction was continued for 1 hour while maintaining the internal temperature of the reaction vessel at 110°C to obtain a solution of pigment dispersion resin 1. Next, after cooling the contents in the reaction vessel to room temperature, 38 parts of dimethylaminoethanol was added to neutralize Pigment Dispersion Resin 1, and then 100 parts of ion-exchanged water was added. Thereafter, the contents were heated to 100 °C or higher, butanol was azeotroped with ion-exchanged water to distill off the butanol, and then ion-exchanged water was added to adjust the solid content concentration to 50%, thereby obtaining an aqueous solution 1 of Pigment Dispersion Resin with a solid content concentration of 50%. The molecular weight of the obtained Pigment Dispersion Resin 1 was 16,000, and the acid value was 234 mgKOH / g.

[0133] <Production Example of Pigment Dispersion Resin Solution 2> 56 parts of 2-butanone was charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer. Next, 56 parts of benzyl methacrylate, which is a polymerizable monomer, 0.3 part of 2,2'-azobisisobutyronitrile, which is a polymerization initiator, and 2.2 parts of 2-(dodecylthiocarbonothioylthio)-isobutyric acid were respectively added. After replacing the inside of the reaction vessel with nitrogen gas, the contents in the reaction vessel were heated until they reached 75 °C, and then a polymerization reaction was carried out for 3 hours while maintaining the internal temperature at 75 °C, thereby obtaining a polymer (A block) composed of benzyl methacrylate. After completion of the above polymerization reaction, after cooling the contents to room temperature, 44 parts of 2-butanone, 28 parts of butyl methacrylate, and 16 parts of methacrylic acid were respectively charged into the reaction vessel. After replacing the inside of the reaction vessel with nitrogen gas again, the contents in the reaction vessel were heated until they reached 75 °C, and then a polymerization reaction was carried out for 3 hours while maintaining the internal temperature at 75 °C, thereby obtaining Pigment Dispersion Resin 2 having an A-B block structure in which a copolymer (block B) composed of butyl methacrylate and methacrylic acid was added to the above A block. Thereafter, after cooling the contents in the reaction vessel to room temperature, 17 parts of dimethylaminoethanol was added to neutralize the pigment dispersion resin 2, and then 150 parts of ion-exchanged water was further added. Thereafter, the contents were heated, 2-butanone was azeotroped with ion-exchanged water to distill off the 2-butanone, and then ion-exchanged water was added to adjust the solid content concentration to 50%, thereby obtaining an aqueous solution 2 of the pigment dispersion resin with a solid content concentration of 50%. The molecular weight of the obtained pigment dispersion resin was 23,000, and the acid value was 104 mgKOH / g.

[0134] <Production Example of Cyan Pigment Dispersion Liquid 1> 20 parts of LIONOGEN BLUE FG-7358G (C.I.Pigment Blue15:3, manufactured by Toyo Color Co., Ltd.), 15 parts of the aqueous solution 1 of the pigment dispersion resin, and 65 parts of ion-exchanged water were mixed and preliminarily dispersed with a disper. Then, using a dyno mill with a volume of 0.6 L filled with 1,800 g of zirconia beads with a diameter of 0.5 mm, this dispersion was carried out to obtain cyan pigment dispersion liquid 1.

[0135] <Production Example of Cyan Pigment Dispersion Liquid 2> A cyan pigment dispersion liquid 2 was produced by the same raw materials and method as the above cyan pigment dispersion liquid 1, except that the aqueous solution 2 of the pigment dispersion resin was used instead of the aqueous solution 1 of the pigment dispersion resin.

[0136] <Production Example of Binder Resin 1> 72.4 parts of 2-butanone was charged into a reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer, and the inside of the reaction vessel was purged with nitrogen gas. Next, after heating the inside of the reaction vessel to 80 °C, a mixture of 15 parts of styrene, 4.5 parts of methacrylic acid, 5.0 parts of 2-hydroxyethyl methacrylate, 20 parts of stearyl methacrylate, 55.5 parts of methyl methacrylate, which are polymerizable monomers; and 4 parts of V-601 (manufactured by Fuji Film Wako Pure Chemical Corporation), which is a polymerization initiator, was added dropwise into the above reaction vessel over 2 hours. After completion of the dropwise addition, the polymerization reaction was continued for 3 hours while maintaining the internal temperature at 80 °C. Then, 0.6 part of V-601 was added, and the polymerization reaction was continued for 2 hours while maintaining the internal temperature at 80 °C to obtain a solution of binder resin 1. Next, after cooling the contents in the reaction vessel to 50 °C, 4.7 parts of dimethylaminoethanol was added to neutralize binder resin 1, and then 140 parts of water was added. Thereafter, the contents were heated to 78 °C or higher, 2-butanone was azeotroped with water to distill off the 2-butanone, and then water was added to adjust the solid content concentration to 30% to obtain an aqueous solution of binder resin 1 with a solid content concentration of 30%. The weight average molecular weight of the obtained binder resin 1 was 17,000.

[0137] <Synthesis of non-modified acetylene diol-based surfactant (A1)> Using the method described in Example 1 of JP-A-2002-356451 and using methyl isobutyl ketone as the raw material ketone, 2,4,7,9-tetramethyl-5-decyne-4,7-diol (non-modified acetylene diol-based compound 1, HLB value = 3.0) was synthesized. Similarly, by using methyl isoamyl ketone as the raw material ketone, 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol (non-modified acetylene diol-based compound 2, HLB value = 2.7) was synthesized.

[0138] <Synthesis of alkylene oxide-modified acetylene diol-based surfactant (A2)> Using the method described in Example 1 of U.S. Patent No. 3,268,593, starting from the above non-modified acetylene diol compound 1 (2,4,7,9-tetramethyl-5-decyne-4,7-diol), by adjusting the amount of ethylene oxide and the synthesis conditions (pressure, temperature, time), alkylene oxide-modified acetylene diol surfactants (modified acetylene diol compounds 1 to 4, 6 to 11) with different amounts of ethylene oxide modification were synthesized. Also, starting from the non-modified acetylene diol compound 2 (2,5,8,11-tetramethyl-6-dodecyne-5,8-diol), by adjusting the amount of ethylene oxide and the synthesis conditions (pressure, temperature, time), an ethylene oxide-modified acetylene diol surfactant (modified acetylene diol compound 5) with an HLB value of 8 was synthesized. Furthermore, using the method described in Example 1 of JP-A-2001-215690 and starting from the modified acetylene diol compounds 10 and 11, ethylene oxide-propylene oxide-modified acetylene diol surfactants (modified acetylene diol compounds 12 and 13) in which a propylene oxide group was added to the above modified acetylene diol compounds 10 and 11 were synthesized.

[0139] The details of the modified acetylene diol compounds 1 to 13 produced above (starting materials, number of moles of ethylene oxide groups (and propylene oxide groups) added, and HLB values) are as shown in Table 1 below.

[0140]

Table 1

[0141] <Production Example of Ink 1> 35.6 parts of ion-exchanged water, 20 parts of 1,2-propanediol, 0.001 part (10 ppm) of non-modified acetylene-based compound 1, 1.5 parts of modified acetylene diol compound 4, 1.0 part of BYK-349 (a silicone surfactant manufactured by BYK Chemie, HLB value = 10.2), 0.2 part of TEGO Glide 100 (a silicone surfactant manufactured by Evonik, HLB value = 6.8), 16.7 parts of an aqueous solution of binder resin 1, and 25 parts of cyan pigment dispersion liquid 1 were sequentially added to a mixing container, and then stirred with a disper until it became sufficiently uniform. Thereafter, filtration was performed using a membrane filter with a pore size of 1 μm to remove coarse particles that cause head clogging, and Ink 1 was prepared.

[0142] <Production Examples of Inks 2 to 105> Inks 2 to 105 were prepared in the same manner as in the production example of Ink 1C, except that the raw materials described in Table 2 were used.

[0143]

Table 2

[0144]

Table 2

[0145]

Table 2

[0146]

Table 2

[0147]

Table 2

[0148]

Table 2

[0149] The details of the product names listed in Table 2 above are as follows. · NeoCryl A-1127 (acrylic emulsion manufactured by DSM, solid content concentration 44%, MFT 7°C) · NeoRez R-600 (urethane emulsion manufactured by DSM, solid content concentration 33%, MFT less than 0°C) · BYK 349 (silicone-based surfactant manufactured by BYK Chemie, HLB value = 10.2) · BYK 3420 (silicone-based surfactant manufactured by BYK Chemie, HLB value = 13.8) · BYK 3451 (silicone-based surfactant manufactured by BYK Chemie, HLB value = 10.8) · TEGO Glide100 (silicone-based surfactant manufactured by Evonik, HLB value = 6.8) · TEGO Glide440 (silicone-based surfactant manufactured by Evonik, HLB value = 12.7) · TEGO Twin 4200 (silicone-based surfactant manufactured by Evonik, HLB value = 8.2) · Braunon EL-1502.2 (polyoxyethylene lauryl ether manufactured by Aoki Yushi Co., Ltd., HLB value = 6.3) · Braunon EL-1505 (polyoxyethylene lauryl ether manufactured by Aoki Yushi Co., Ltd., HLB value = 10.5) · Braunon EL-1515 (polyoxyethylene lauryl ether manufactured by Aoki Yushi Co., Ltd., HLB value = 14.9) · Braunon EL-1530 (polyoxyethylene lauryl ether manufactured by Aoki Yushi Co., Ltd., HLB value = 17.4) · Braunon BN-3 (polyoxyethylene beta-naphthol ether manufactured by Aoki Yushi Co., Ltd., HLB value = 9.6) · Lutensol XP30 (nonionic surfactant manufactured by BASF, HLB value = 9.1) · Lutensol XP50 (nonionic surfactant manufactured by BASF, HLB value = 11.6) · Lutensol XP100 (nonionic surfactant manufactured by BASF, HLB value = 14.7)

[0150] [Examples 1 - 93, Comparative Examples 1 - 12] The following evaluations were performed on the inks prepared above. The evaluation results were as shown in Table 3.

[0151] <Evaluation 1: Beading (Solid Filling)> The inkjet ejection device equipped with a head (KJ4B - 1200) manufactured by Kyocera Corporation and installed in an environment of 25°C was filled with each of the inks prepared above. After printing a nozzle check pattern and confirming that the ink was ejected normally from all nozzles, it was left for 1 minute. Then, under the printing conditions of a frequency of 40 kHz and 1200×1200 dpi, solid printing with a printing rate of 100% was performed on a PET film (FE2001, thickness 12 μm) manufactured by Futamura Chemical Co., Ltd., and then dried in an 85°C air oven for 1 minute to obtain a solid printed matter. And the evaluation of beading (solid filling) was carried out by visually checking the number of streaks (parts where the ink did not adhere to the printing substrate and looked like streaks) existing in the obtained solid printed matter. The evaluation criteria were as follows, and the ◎, ○, and △ evaluations were regarded as the practical applicable areas. ◎: The number of streaks visible to the naked eye was 5 or less. ○: The number of streaks visible to the naked eye was 6 - 10 or less. △: The number of streaks visible to the naked eye was 11 - 20 or less. ×: The number of streaks visible to the naked eye was 21 or more.

[0152] <Evaluation 2: Continuous Ejection Property> The inkjet ejection device equipped with a head (KJ4B - 1200) manufactured by Kyocera Corporation was filled with each of the inks prepared above. After printing a nozzle check pattern and confirming that the ink was ejected normally from all nozzles, the ink was continuously ejected from all nozzles for 1 hour under the condition of a frequency of 40 kHz. Then, the nozzle check pattern was printed again, and the evaluation of the continuous ejection property was carried out by checking the number of nozzles from which the ink was not ejected (the number of nozzle dropouts). The evaluation criteria were as follows, and the ◎◎, ◎, ○, and △ evaluations were regarded as the practical applicable areas. ◎◎: There was no nozzle dropout at all. ◎: The number of nozzle drop-outs was 1 to 2 ○: The number of nozzle drop-outs was 3 to 6 △: The number of nozzle drop-outs was 7 to 10 ×: The number of nozzle drop-outs was 11

[0153] <Evaluation 3: Blocking resistance> Using the same printing conditions and printing substrate as in the above Evaluation 1, after obtaining a solid print with a printing rate of 100%, it was cut out into a 4 cm × 4 cm square. Also, the PET film used as the printing substrate (however, the one not used for printing) was cut out in the same way as the solid print. Then, a test piece was prepared by overlapping the ink layer of the cut-out solid print so that it faced the non-printed surface (back surface) of the above PET film, and a blocking test was carried out using a permanent distortion tester. The environmental conditions for the blocking test were a load of 10 kg / cm 2 , a temperature of 40°C, 80% RH, and a test period of 24 hours, and a load was applied using a constant load type permanent distortion tester manufactured by Tester Sangyo Co., Ltd. Then, after 24 hours, while maintaining an angle of 90 degrees, the PET film was instantaneously pulled and peeled off, and the blocking resistance was evaluated from the degree of resistance felt when peeling and the state of the ink layer (visual observation) after peeling. The evaluation criteria are as follows, and the ◎◎, ◎, ○, and △ evaluations were regarded as the practical applicable range. ◎◎: The ink layer was not taken onto the PET film, and there was no resistance when peeling ◎: The ink layer was not taken onto the PET film, but there was a slight resistance when peeling ○: Less than 5% of the total area of the ink layer was observed to be taken onto the PET film △: 5% or more and less than 10% of the total area of the ink layer was observed to be taken onto the PET film ×: 10% or more of the total area of the ink layer was observed to be taken onto the PET film

[0154] <Evaluation 4: Migration resistance> Using the same printing conditions and printing substrate as in the above Evaluation 1, a solid print with a print rate of 100% was obtained. Next, using a solventless test coater, a solventless laminating adhesive ("EA-N373A / B" manufactured by Toyo Morton Co., Ltd.) was applied to the printed surface (ink layer side) of the produced solid print at a temperature of 60°C, a coating speed of 50 m / min, and a coating amount of 2 g / m 2 under the conditions of. Further, after overlapping the coated surface of the above solventless laminating adhesive and the corona-treated surface of a CPP film (unoriented polypropylene film "FHK2" (thickness: 25 μm) manufactured by Futamura Chemical Co., Ltd.) so that they face each other, the composition was allowed to stand (age) for 1 day in an environment of 40°C and 80% RH to cure the above solventless laminating adhesive composition and produce a laminated product. The laminated product obtained above was set in a migration cell ("Mgracell (registered trademark) MC60" manufactured by Gassner Glastechnik Co., Ltd.) with the CPP film on the upper side, and then 50 mL of a 95% ethanol solution was added. The contact area between the above laminated product and ethanol was 0.5 dm 2 . Thereafter, the migration cell was allowed to stand in an oven at 40°C for 10 days, and then the 95% ethanol solution was taken out and concentrated to 2 mL under the conditions of 40°C and 50 mmHg. Then, using the concentrated ethanol solution as a sample, the amount of the acetylene-based surfactant was quantified using a gas chromatograph mass spectrometer ("Agilent 7890A / 5975C" manufactured by Agilent Technologies, Inc.) to evaluate the migration resistance. The evaluation criteria were as follows, and ◎, ○, and △ evaluations were defined as the practical use possible range. ◎: The elution amount of the acetylene-based surfactant was 0.1 μg / mL or less. ○: The elution amount of the acetylene-based surfactant exceeded 0.1 μg / mL and was 1.0 μg / mL or less. △: The elution amount of the acetylene-based surfactant exceeded 1.0 μg and was 3.0 μg / mL or less. ×: The elution amount of the acetylene-based surfactant exceeded 3.0 μg / mL.

[0155]

Table 3

[0156]

Table 3

[0157] As is clear from Examples 1 to 93, by using the aqueous inkjet ink of the present invention containing a non-modified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10 in a predetermined blending amount and blending ratio, and further containing a binder resin, a printed matter having no beading, good solid filling, and excellent blocking resistance and migration resistance could be obtained. In addition, the aqueous inkjet ink of the present invention also had good continuous dischargeability.

Claims

1. An aqueous inkjet ink containing a pigment, a binder resin, a water-soluble organic solvent, and an acetylene diol-based surfactant (A), wherein the acetylene diol-based surfactant (A) includes an unmodified acetylene diol-based surfactant (A1) and an alkylene oxide-modified acetylene diol-based surfactant (A2) having an HLB value of 4 to 10, the content of the unmodified acetylene diol-based surfactant (A1) is 10 to 2000 ppm with respect to the total amount of the aqueous inkjet ink, the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) is 0.2 to 5% by mass with respect to the total amount of the aqueous inkjet ink, and the ratio [surfactant (A2) / surfactant (A1)] of the content of the unmodified acetylene diol-based surfactant (A1) to the content of the alkylene oxide-modified acetylene diol-based surfactant (A2) is in the range of 10 to 5000. An aqueous inkjet ink.

2. The aqueous inkjet ink according to claim 1, further comprising a nonionic surfactant (B) other than the acetylene diol-based surfactant.

3. The aqueous inkjet ink according to claim 2, wherein the mass factor-added HLB value calculated by the following formula (1) is 0.3 to 2.

0. Formula (1): 【Number 1】 (In formula (1), i represents the type of surfactant used as the non-modified acetylene diol-based surfactant (A1), and l represents the number of types of surfactants used as the non-modified acetylene diol-based surfactant (A1). Also, j represents the type of surfactant used as the alkylene oxide-modified acetylene diol-based surfactant (A2), and m represents the number of types of surfactants used as the alkylene oxide-modified acetylene diol-based surfactant (A2). Also, k represents the type of surfactant used as the nonionic surfactant (B), and n represents the number of types of surfactants used as the nonionic surfactant (B). Also, HLB i represents the HLB value of surfactant i, and WT i represents the content (mass%) of surfactant i with respect to the total mass of the aqueous inkjet ink, and HLB j represents the HLB value of surfactant j, and WT j represents the content (mass%) of surfactant j with respect to the total mass of the aqueous inkjet ink, and HLB k represents the HLB value of surfactant k, and WT k represents the content (mass%) of surfactant k with respect to the total mass of the aqueous inkjet ink.)

4. The aqueous inkjet ink according to claim 2 or 3, wherein the nonionic surfactant (B) includes a silicone-based surfactant.

5. The aqueous inkjet ink according to any one of claims 1 to 3, wherein the water-soluble organic solvent includes 1,2-propanediol, and the content of the 1,2-propanediol is 5 to 30% by mass with respect to the total amount of the aqueous inkjet ink.

6. A printed matter obtained by printing the aqueous inkjet ink according to any one of claims 1 to 3 on a printing substrate.

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