JP6712379B1 - Method for producing water-based inkjet ink and inkjet printed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent C.I., which is excellent in drying property, image quality of printed matter, scratch resistance of printed matter, and dispersion stability and ejection stability. I. It is to provide an aqueous inkjet ink containing Pigment Red 185. In addition to the above-mentioned characteristics, a printed matter having excellent adhesiveness and color reproducibility can be obtained even for a non-permeable substrate such as a plastic substrate. I. It is to provide an aqueous inkjet ink containing Pigment Red 185. SOLUTION: C. I. Pigment Red 185, a binder resin (a-1) having an acid value of 1 to 80 mgKOH/g, a surfactant, and a water-soluble organic solvent, and having a boiling point of 240° C. or higher under 1 atm. The inkjet ink has a solvent content of 8% by mass or less based on the total amount of the inkjet ink. [Selection diagram] None

Description

The present invention provides C.I. I. The present invention relates to an aqueous inkjet ink containing Pigment Red 185, and a method for producing an inkjet printed product using the aqueous inkjet ink.

The digital printing method has been rapidly spread with the reduction of printing lots and diversification of needs. The digital printing method does not require a plate, so it supports small lots, reduces costs,
It is possible to reduce the size of the printing apparatus.

The inkjet printing method, which is a type of digital printing method, means that minute droplets of ink are ejected and landed from an inkjet head onto a recording medium, and images and characters (hereinafter collectively referred to as “printed matter”) are formed on the recording medium. It is a method of forming. Compared to other digital printing methods, it is superior in size and cost of a printing device, running cost at the time of printing, and ease of full-color printing, and in recent years, it has been increasingly used in industrial printing applications.

Inks used in ink jet printing methods include oil-based, solvent-based, active energy ray-curable, and water-based inks. So far, solvent-based and active energy ray-curable inks have been used in industrial printing applications. However, in recent years, consideration of environmental and human hazards
Demand for water-based ink is increasing from the standpoint of handling.

Further, in recent years, in order to expand the applications of the ink jet printing method, in addition to industrial printing applications, development to packaging applications such as paper containers, labels, and packaging films is required. In that case, the color reproducibility and the image quality are higher than those of low-permeability substrates such as coated paper and art paper, and non-permeable substrates such as polypropylene film and polyethylene terephthalate (PET) film. Therefore, it is required to form a printed matter having characteristics that can be used in actual use.

In particular, for packaging purposes, red color reproducibility is often required for sales promotion designs, corporate corporate colors, national colors in emerging countries, and the like. Generally, red color is formed by superimposing yellow color and magenta color, but in order to further enhance the color reproducibility of the red area, attempts have been made to set special color inks of orange color and red color ( See Patent Documents 1 to 3).

However, the use of the special color ink is not a preferable measure from the viewpoint of reducing the size and cost of the printing apparatus. Therefore, how to improve the color reproducibility among the three process colors of yellow, cyan, and magenta is very important.

Generally, dyes and pigments are known as colorants used in inks, but in consideration of characteristics required for packaging applications, pigments excellent in light resistance and moisture resistance of printed matter are preferably selected. Further, there are various kinds of pigments, and one of them is benzimidazolone pigment, which is a pigment excellent in balance of color development, light resistance, chemical resistance and the like. Further, various benzimidazolone pigments exhibiting a magenta color which is a process color are also known, and one of them is C.I. I. Pigment Red 185 has been often studied so far in inkjet ink applications (see Patent Documents 4 to 5).

For example, in Patent Document 4, C.I., which is a pseudo one-dimensional crystalline color organic pigment, is disclosed. I. Pigment Red 185, and further an aqueous inkjet ink containing a water-soluble organic solvent, a surfactant, and a water-soluble resin is disclosed. However, the acid value of the water-soluble resin which is said to be preferably used in Patent Document 4 is 90 to 130. The present inventors have found that C.I. I. Pigment Red 185 and a resin having an acid value of about 90 were used together to prepare and evaluate an aqueous inkjet ink, and it was found that the dispersion stability was poor. To impart dispersion stability, as described in Patent Document 4, C.I. I. Pigment Red 185 needs to be quasi one-dimensionally crystallized, but the manufacturing load such as equipment and cost is large,
Not the preferred method. In addition, since the ink compositions described in the examples include a total amount of 10 mass% of tetrapropylene glycol and triethylene glycol monobutyl ether, which are water-soluble organic solvents having a high boiling point, When printed on a low-permeability substrate or a non-permeable substrate used for various purposes, it is easily expected that the printed matter will be inferior in drying property, image quality and scratch resistance.

Further, in Patent Document 5, C.I. I. Pigment Red 185 and C.I. I. Pigment Red 122 and a pigment dispersion liquid coated with an anionic group-containing resin, and an aqueous recording liquid (inkjet ink) containing the pigment dispersion liquid are disclosed. However, the above-mentioned Patent Document 5
In order to improve the properties of the water-based inkjet ink and the printed matter formed by the water-based inkjet ink, C.I. I. There is no description of materials suitable for combination with Pigment Red 185. In addition, the aqueous recording liquid described in Examples does not contain a binder resin, and triethylene glycol monobutyl ether is 1
It is contained in an amount of 0% by mass, and when printed on a low-permeability base material or a non-permeability base material, like the ink compositions described in Examples of Patent Document 4, drying property, image quality and scratch resistance are obtained. It is highly likely that the printed matter will be inferior to

JP 2004-276397 A JP, 2015-199849, A International Publication No. 2017/61507 JP, 2003-12982, A JP, 2006-57044, A

The present invention has been made to solve the above problems, and its purpose is to provide excellent drying properties, image quality of printed matter, and resistance (rubbing resistance) of printed matter, and further dispersion stability and ejection stability. Also excellent for C.I. I. It is to provide an aqueous inkjet ink containing Pigment Red 185. Further, a further object of the present invention is to obtain a printed matter which is excellent in adhesion and color reproducibility in addition to the above-mentioned properties even for a non-permeable substrate such as a plastic substrate. I. It is to provide an aqueous inkjet ink containing Pigment Red 185.

As a result of intensive studies conducted by the present inventors to solve the above problems, a binder resin having a specific acid value, a surfactant, a water-soluble organic solvent, C.I. I. It was found that the above problems can be solved by using Pigment Red 185 in combination and further limiting the content of the water-soluble organic solvent having a specific boiling point, and completed the present invention.

That is, the present invention is an aqueous inkjet ink containing a colorant, a binder resin (A), a surfactant, and a water-soluble organic solvent,
The colorant is C.I. I. Pigment Red 185,
The binder resin (A) has an acid value of 1 to 80 mgKOH/g (
a-1) included,
The present invention relates to a water-based inkjet ink in which the content of the water-soluble organic solvent having a boiling point of 240° C. or higher under 1 atmosphere is 8% by mass or less based on the total amount of the inkjet ink.

In the present invention, the binder resin (a-1) is at least one selected from the group consisting of acrylic resin, styrene acrylic resin, urethane resin, urethane-acrylic composite resin, and olefin resin. Related to inkjet ink.

In the present invention, the water-soluble organic solvent contains an alkanediol having 2 to 5 carbon atoms,
The present invention relates to the water-based inkjet ink.

The present invention also relates to the above aqueous inkjet ink, wherein the surfactant contains a surfactant having an HLB value of 0 to 5.

Further, in the present invention, the surfactant contains a surfactant having an HLB value of 6 to 18,
The present invention relates to the water-based inkjet ink.

The present invention also relates to the above water-based inkjet ink, wherein the total amount of the chain amide-based solvent, the cyclic amide-based solvent, and the cyclic carbamate-based solvent is 3% by mass or less based on the total amount of the water-based inkjet ink.

In addition, the present invention provides a nitrogen-containing compound having a pKa value at 25° C. of 2 or less, or 10 or more (however, a chain amide solvent, a cyclic amide solvent, and a cyclic carbamate solvent are excluded). The present invention relates to the water-based inkjet ink, wherein the total amount is 1% by mass or less based on the total amount of the inkjet ink.

The present invention also relates to a method for producing an inkjet printed material, which comprises ejecting the above-mentioned aqueous inkjet ink from an inkjet head and applying it to a non-permeable substrate.

According to the present invention, the drying property, the image quality of the printed matter, and the resistance (rubbing resistance) of the printed matter are excellent,
Furthermore, C.I., which has excellent dispersion stability and ejection stability, I. It has become possible to provide an aqueous inkjet ink containing Pigment Red 185. Further, for non-permeable base materials such as plastic base materials, in addition to the above properties, printed matter having excellent adhesion and color reproducibility can be obtained.
C. I. It has become possible to provide an aqueous inkjet ink containing Pigment Red 185.

The water-based inkjet ink of the present invention (hereinafter, also simply referred to as "water-based ink" or "ink") will be described below with reference to preferred embodiments. In the present specification, the “aqueous medium” means a medium made of a liquid containing at least water.

C. contained in the water-based ink of the present invention. I. Pigment Red 185 has the following structure and is known as a pigment excellent in color development and light resistance.

As shown in the above structure, C.I. I. Pigment Red 185 includes an isoindoline structure, an azo group, and the like in its molecular structure, and has many nitrogen atoms and oxygen atoms. In addition, since there are naphthol structure and aromatic ring structure, it is considered that intermolecular interactions such as hydrogen bond and π interaction are very strong.

In aqueous inks, the pigments are generally present in the aqueous medium in a dispersed state. However, C.I. I. Pigment Red 185, which has a strong intermolecular interaction, is easily destroyed in the dispersed state due to a subtle change in balance in the water-based ink. Particularly in the case of inkjet ink, it is necessary to control the physical properties such as viscosity, surface tension, and pH in order to stably eject from the inkjet head, and the materials that can be used are limited. It will be difficult. That is, C.I. I. In the water-based inkjet ink containing Pigment Red 185, maintaining a suitable dispersed state and satisfying the properties as an inkjet ink are both major problems for those skilled in the art.

For example, a high-boiling solvent having low volatility is often used in an aqueous inkjet ink in order to secure wettability and spread on a recording medium and obtain a printed matter having excellent image quality. However, when printed on a non-permeable substrate described below, the water-based ink droplets are likely to remain on the recording medium for a long time, and coalescence of the ink droplets may occur, resulting in bleeding and uneven density. May occur. Further, the high boiling point solvent remaining in the printed matter may deteriorate the scratch resistance of the printed matter.

In order to solve the above-mentioned problem, for example, a method of using a highly volatile solvent in combination, or reducing the amount of a low-boiling solvent having a high boiling point can be considered. However, since a solvent having high volatility generally tends to destroy the dispersed state of the pigment, C.I. I. Pigment Red 185 is difficult to use in combination with a pigment having a strong intermolecular interaction. Further, problems may occur such that the ink is dried before it sufficiently spreads on the recording medium and causes white spots, and the ink is dried and solidified on the nozzle surface of the inkjet head, causing ejection bending and ejection failure. ..

Further, a binder resin may be added to the water-based inkjet ink for the purpose of improving scratch resistance of the printed matter. However, there is a possibility that an acid group or the like present in the binder resin interacts with a polar group in the pigment or a material that contributes to the dispersion of the pigment and destroys the dispersed state. Particularly as described above, C.I. I. Pigment Red 185 contains a large number of nitrogen atoms and oxygen atoms in its molecular structure, so that dispersion stability is likely to deteriorate. Further, the ink containing the binder resin is likely to be dried and solidified on the nozzle surface, and the ejection stability is likely to be lowered.

Therefore, as a result of intensive studies by the present inventors, a binder resin having a specific acid value, a surfactant, and a water-soluble organic solvent in combination, further, the content of the water-soluble organic solvent having a specific boiling point, It has been found that by limiting the amount, dispersion stability, ejection stability, drying property, image quality of printed matter, and scratch resistance of printed matter are all achieved at the same time. The reason is not clear, but the following is considered.

First, the water-based ink of the present invention contains a binder resin (a-1) having a low acid value and a low affinity with water which is the main component of the ink. Therefore, it is considered that the binder resin (a-1) quickly moves to the gas-liquid interface in the process of drying after the droplets of the aqueous ink have landed on the recording medium. Moreover, when the abundance ratio of the water-soluble organic solvent increases with the drying of the ink droplets on the recording medium, the binder resin (a-1) dissolves in the water-soluble organic solvent and is locally present at the gas-liquid interface. Cause thickening or film formation. As a result, it is considered that bleeding between ink droplets and uneven density are suppressed, and the image quality is improved.

Further, the acid value of the binder resin (a-1) is defined, and the binder resin (a-1)
) By limiting the amount of acid groups in C. I. Pigment Red 185 is maintained in a dispersed state.

On the other hand, the binder resin (a-1) having a small acid value does not easily return to the original state once formed into a film even in the presence of an aqueous medium. This is preferable from the viewpoint of improving the scratch resistance of the printed matter, but on the other hand, if ink forms a film on the nozzle surface of the inkjet head, at least a part of the nozzle will be blocked, and Since it is difficult to return to the above state, there is a risk of deterioration of ejection stability. Therefore, in the present invention, this problem is solved by additionally using a surfactant. Generally, a surfactant has a hydrophobic group and a hydrophilic group in the molecule. In the ink of the present invention, it is considered that the binder resin (a-1) and the hydrophobic group in the surfactant molecule have an affinity with each other, and water and the hydrophilic group in the surfactant molecule have an affinity with each other. In the ink in the inkjet head, the binder resin (a-1) is in a state of being protected by the surfactant, and the binder resin (a-1)
It is considered that the film formation of a-1) is suppressed. On the other hand, in the ink droplets landed on the recording medium, when the surfactant moves to the solid-liquid interface formed by the recording medium and the ink due to the influence of the change in the abundance ratio of the constituent materials in the ink accompanying the drying. Conceivable. As a result, it is considered that the ink droplets quickly spread on the recording medium and, in combination with the effect of thickening or film formation by the binder resin (a-1), the ink has excellent image quality and dryness of the printed matter. ..

In addition, the water-based inkjet ink of the present invention may contain a water-soluble organic solvent having a boiling point of 240° C. or higher under 1 atmosphere (hereinafter, also referred to as “high-boiling point organic solvent”). It is 8 mass% or less with respect to the total amount of the inkjet ink, and it is preferable not to include it. Generally, the high boiling point organic solvent is a compound having a large number of functional groups capable of forming hydrogen bonds and/or having a large molecular weight. Therefore, a high boiling point organic solvent and C.I. I. Pigment Red 185 forms a hydrogen bond, and C.I. I. The material contributing to the dispersion of Pigment Red 185 preferentially interacts with the high boiling point organic solvent, which may destroy the dispersed state of the pigment. Further, since the high-boiling point organic solvent is not easily dried, it may remain in the printed matter for a long period of time after printing, leading to deterioration of drying property, scratch resistance and image quality. Based on the above consideration, the present inventor has conducted extensive studies, and as a result, the boiling point at 1 atmospheric pressure was 24.
It has been found that by limiting the amount of the water-soluble organic solvent having a temperature of 0° C. or higher to 8% by mass or less, it is possible to prevent deterioration of dispersion stability, drying property, scratch resistance of printed matter, and image quality.

As described above, C.I. I. In order to obtain a water-based inkjet ink that is compatible with all of dispersion stability, ejection stability, drying property, image quality of printed matter, and scratch resistance of printed matter, even though it contains Pigment Red 185, the constitution of the present invention is Considered essential.

Subsequently, each component constituting the water-based inkjet ink of the present invention will be described below.

<C. I. Pigment Red 185>
The water-based inkjet ink of the present invention contains C.I. I. Pigment Red 185
including. As described above, C.I. I. Pigment Red 185 has excellent color developability and light resistance, and when used in combination with an ink having a magenta color and an ink having a red color, a printed matter having excellent color reproducibility can be obtained.

From the viewpoint of obtaining a printed matter having excellent color reproducibility, C.I. I. The content of Pigment Red 185 is preferably 0.5 to 10% by mass, more preferably 1 to 9% by mass, and particularly preferably 2 to 8% by mass, based on the total amount of the water-based ink. ..

In the present invention, from the viewpoint of obtaining a printed matter having excellent color reproducibility, C.I. I. Pigment Red 18
Pigments other than 5 may be used in combination.

C. I. Pigments other than Pigment Red 185 are preferably orange pigments, magenta pigments, violet pigments, and the like, and may contain magenta pigments and/or violet pigments from the viewpoint that a printed matter having excellent color reproducibility in the red region can be obtained. It is particularly suitable. The C. I. When a magenta pigment and/or a violet pigment is used as a pigment other than Pigment Red 185, the blending amount is C.I. I. Pigment Red 185 is preferably contained in an amount of 10 to 100% by mass, and particularly preferably 20 to 70% by mass.

C. I. Pigment Red 185, an orange pigment that can be used with C.I.
I. Pigment Orange 13, 16, 17, 22, 24, 34, 36, 38, 40, 43
, 51, 60, 62, 64, 71, 72, 73 and the like. Among them, C.I. I. Pigment Red 185 is not easily destroyed in the dispersed state, and the C.I. I. Pigment Red 1
C. 85 from the viewpoint of excellent color reproducibility when mixed with C. I. Pigment Orange 36, 38,
One or more selected from the group consisting of 43, 60, 62, 64 and 72 can be preferably used.

In addition, C.I. I. Examples of magenta organic pigments that can be used with Pigment Red 185 include C.I. I. Pigment Red 5, 7, 12, 22, 23, 31, 48 (Ca), 48
(Mn), 49, 52, 53, 57 (Ca), 57:1, 112, 122, 146, 14
7, 150, 202, 207, 209, 238, 242, 254, 255, 266, 26
9, 282 and the like. Among them, C.I. I. Pigment Red 185 is not easily destroyed in the dispersed state, and the C.I. I. Pigment Red 185, C.I. I. Pigment Red 122, 150, 202, 209, and 282 can be preferably used one or more selected from the group consisting of.

In addition, C.I. I. Examples of violet pigments that can be used with Pigment Red 185 include C.I. I. Pigment Violet 19, 23, 29, 30, 37, 40, 42, 4
3, 50 and the like. Among them, C.I. I. Pigment Red 185 is not easily destroyed in the dispersed state, and the C.I. I. Pigment Red 185, C.I. I. Pigment Violet 19, 23, 32, and 42 can be preferably used one or more selected from the group consisting of.

Among the pigments exemplified and selected above, benzimidazolone pigment, quinacridone pigment,
At least one selected from the group consisting of dioxazine pigments is preferably selected. Both pigments have an aromatic ring structure or C.I. I. Pigment Red 185 has a partial structure similar to that of C.I. I. This is because it is difficult to destroy the dispersed state of Pigment Red 185 and an aqueous ink having excellent dispersion stability can be obtained. Further, these pigments are also suitable from the viewpoint of color reproducibility of printed matter.

The pigments exemplified and selected above may be used alone or in combination of two or more kinds. Further, the two or more kinds of pigments may form a solid solution, in which case,
It is preferable to use a solid solution containing a quinacridone pigment from the viewpoint of dispersion stability and improvement of color reproducibility of printed matter. Specific examples of solid solutions that can be preferably used in the present invention include C.I. I.
Pigment Red 122 and C.I. I. Pigment Violet 19 and C.I. I
． Pigment Red 202 and C.I. I. Pigment Violet 19 and C.I.
I. Pigment Red 209 and C.I. I. Pigment Violet 19 and a solid solution containing C
． I. Pigment Red 282 and C.I. I. Pigment Violet 19 and a solid solution,
C. I. Pigment Red 122 and C.I. I. Pigment Red 146 and a solid solution containing C
． I. Pigment Red 122 and C.I. I. Pigment Red 150, a solid solution containing C.I.
I. Pigment Red 122 and C.I. I. Pigment Red 254 and C.I. I
． Pigment Red 122 and C.I. I. Pigment Red 269 and the like as a solid solution.

<Pigment dispersion resin>
C. I. As a method for stably dispersing and holding a pigment containing Pigment Red 185 in an aqueous inkjet ink, (1) a method of coating at least a part of the pigment surface with a pigment dispersion resin, (2) water solubility and/or water dispersibility Method of adsorbing the surface active agent on the surface of the pigment, (3) Method of chemically/physically introducing a hydrophilic functional group onto the surface of the pigment and dispersing it in the ink without a dispersing resin or a surface active agent (self-dispersible pigment ) And the like.

For the aqueous inkjet ink of the present invention, the method (1) among the above, that is, the method using a pigment-dispersed resin is preferably selected. This is because it is possible to easily adjust the coating ability of the pigment-dispersed resin to the pigment and the charge of the pigment-dispersed resin by selecting and examining the polymerizable monomer composition and molecular weight of the resin. Even in this case, dispersion stability can be imparted, and a printed matter having excellent ejection stability, color development, and color reproducibility can be obtained.

The type of the pigment dispersion resin is not particularly limited, and examples thereof include acrylic resin, styrene acrylic resin, maleic acid resin, styrene maleic acid resin, olefin maleic acid resin, urethane resin, ester resin (polyhydric carboxylic acid and polyhydric alcohol. However, the polycondensation product thereof is not limited to these. Among them, it is preferable to use at least one selected from the group consisting of acrylic resin, styrene acrylic resin, urethane resin, and ester resin from the viewpoint of material selectivity and ease of synthesis. Further, from the viewpoint of improving dispersion stability and discharge stability of the water-based ink, it is preferable to use a resin of the same type as the binder resin (A) described later.

The above pigment-dispersed resin can be synthesized by a known method or a commercially available product can be used. The structure is also not particularly limited, and for example, a resin having a random structure, a block structure, a comb structure, a star structure, or the like can be used. Further, a water-soluble resin or a water-insoluble resin may be selected as the pigment dispersion resin. The “water-insoluble resin” refers to a pigment-dispersed resin of interest, which is not transparent to the naked eye at 25° C./1% by mass water mixture.

In the present invention, when a water-soluble resin is used as the pigment-dispersed resin, its acid value is 50 to 45.
It is preferably 0 mgKOH/g, more preferably 100 to 400 mgKOH/g. Particularly preferably, it is 150 to 350 mgKOH/g. By setting the acid value within the above range, it is possible to maintain the dispersion stability of the pigment and to stably eject the pigment from the inkjet head. Further, it becomes possible to maintain the ejection stability on the inkjet head. Further, the solubility of the pigment-dispersed resin in water can be ensured, and the interaction between the pigment-dispersed resins is preferable, so that the viscosity of the pigment-dispersed liquid can be suppressed, which is preferable.

On the other hand, when a water-insoluble resin is used as the pigment dispersion resin, the acid value is 0 to 100 mgKO.
H/g is preferable, 5-90 mgKOH/g is more preferable, and 10
More preferably, it is -80 mgKOH/g. When the acid value is within the above range, a printed matter having excellent dryness and scratch resistance can be obtained.

The acid value of the resin in this specification is a known device, for example, AT-610 manufactured by Kyoto Electronics Manufacturing Co., Ltd.
Can be measured by a potentiometric titration method.

In the water-based inkjet ink of the present invention, it is preferable to introduce an aromatic group into the pigment-dispersing resin from the viewpoint of improving the adsorption ability for the pigment and ensuring the dispersion stability. Particularly in the case of the present invention, C.I. I. Pigment Red 185 interacts with the aromatic ring structure contained in the pigment-dispersed resin, whereby the C.I. I. Pigment Red 185 has a significantly improved adsorption ability of the pigment-dispersed resin. As a result, even if the pigment is finely dispersed, the dispersion stability of the water-based ink, the ejection stability, and the color reproducibility of the printed matter can be ensured for a long period of time. Examples of the aromatic group include a phenyl group, a naphthyl group, an anthryl group, a tolyl group, a xylyl group, a mesityl group, and an anisyl group.
It is not limited to these. Of these, a phenyl group and a tolyl group are preferable from the viewpoint of sufficiently ensuring dispersion stability.

C. I. The content of the aromatic ring-containing monomer is 5 to 75% by mass based on the total amount of the pigment-dispersed resin, from the viewpoints of achieving both the dispersion stability of the ink containing Pigment Red 185, the printing quality, and the drying property. Preferably, it is 5 to 65% by mass, more preferably 10 to 50% by mass.
Is even more preferable.

In addition to the aromatic group, it is particularly preferable to introduce an alkyl group having 8 to 36 carbon atoms into the pigment dispersion resin. By setting the number of carbon atoms of the alkyl group to 8 to 36, the viscosity of the pigment dispersion liquid is lowered, and C.I. I. This is because it is possible to improve the dispersion stability of the ink containing Pigment Red 185 and stabilize the ejection. The number of carbon atoms in the alkyl group is more preferably 1
It is 0 to 30, more preferably 12 to 24 carbon atoms. The alkyl group has 8 to 8 carbon atoms.
Within the range of 36, both linear and branched chains can be used, but linear ones are preferred. As the linear alkyl group, ethylhexyl group (C8), lauryl group (
C12), myristyl group (C14), cetyl group (C16), stearyl group (C18), aralkyl group (C20), behenyl group (C22), lignoceryl group (C24), serotoyl group (C26), montanyl group (C28). , A melissyl group (C30), a dotriacontanyl group (C32), a tetratriacontanyl group (C34), a hexatriacontanyl group (C36) and the like.

The content of the monomer containing an alkyl chain having 8 to 36 carbon atoms is 5 to 60% by mass based on the total amount of the pigment dispersion resin from the viewpoint of achieving both low viscosity of the pigment dispersion and scratch resistance of the printed matter. Is preferable, 10 to 55 mass% is more preferable, and 15 to 50 mass% is particularly preferable.

When a water-soluble resin is used as the pigment dispersion resin, it is preferable that the acid groups in the resin are neutralized with a base in order to increase the solubility in the water-based ink. Whether the amount of the base added is excessive can be confirmed by, for example, preparing a 10% by mass aqueous solution of the pigment dispersion resin and measuring the pH of the aqueous solution. C. I. From the viewpoint of improving the dispersion stability of the ink containing Pigment Red 185, the pH of the aqueous solution is preferably 7 to 11,
． It is more preferably 5 to 10.5.

As the above-mentioned base for neutralizing the pigment dispersion resin, triethylamine, monoethanolamine, diethanolamine, N-methyldiethanolamine, dimethylaminoethanol, diethylaminoethanol, organic amine solvents such as aminomethylpropanol, aqueous ammonia, water. Examples thereof include, but are not limited to, alkali metal hydroxides such as lithium oxide, sodium hydroxide and potassium hydroxide, and alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium hydrogen carbonate and potassium carbonate. ..

When a water-soluble resin is used as the pigment dispersion resin, its weight average molecular weight is 1,000 to 5
It is preferably in the range of 10,000, more preferably in the range of 5,000 to 40,000, still more preferably in the range of 10,000 to 35,000, and
It is particularly preferable that the range is from 00 to 30,000. When the weight average molecular weight is within the above range, C.I. I. Pigment Red 185 is stably dispersed in water, and viscosity adjustment when applied to water-based ink is easy to perform. When the weight average molecular weight is 1,000 or more,
Since the pigment-dispersed resin becomes difficult to dissolve in the water-soluble organic solvent added to the water-based ink, C.I. I. Pigment Red 185 is more strongly adsorbed to the pigment dispersion resin, and dispersion stability is improved. When the weight average molecular weight is 50,000 or less, the viscosity at the time of dispersion is kept low, the dispersion stability of the ink and the ejection stability from the inkjet head are improved, and stable printing is possible for a long period of time.

The blending amount of the pigment dispersion resin is preferably 1 to 100 mass% with respect to the blending amount of the pigment. By setting the ratio of the pigment dispersion resin within the above range, the viscosity of the pigment dispersion liquid is suppressed, and the dispersion stability and ejection stability of the aqueous inkjet ink are improved. The ratio of the pigment to the pigment-dispersed resin is more preferably 2 to 50% by mass, and particularly preferably 4 to 45% by mass.

<Dispersion aid>
In the water-based inkjet ink of the present invention, C.I. I. Pigment Red 185 significantly improves the dispersion stability and the ejection stability, and also enables the fine dispersion of the pigment to improve the color reproducibility of the printed matter. When selecting the method 2), a dispersion aid may be used in combination. The dispersion aid is a material that contributes to the improvement of the adsorption rate of the pigment dispersion resin or the surfactant with respect to the pigment. In the present invention, conventionally known materials can be arbitrarily used as the dispersion aid, and in particular, compounds called dye derivatives can be preferably used. The dye derivative is a compound in which a substituent is introduced into an organic dye molecule, and as the organic dye, a monoazo dye, a disazo dye, a polyazo dye, an anthraquinone dye, an isoindolinone dye, an isoindoline dye. , Quinacridone dye, quinophthalone dye, dioxazine dye, diketopyrrolopyrrole dye, slene dye, thioindigo dye, naphthalocyanine dye, phthalocyanine dye, perinone dye, perylene dye, benzimidazolone dye , Metal complex dyes, and the like. The above "dye" is
It is a general term for pigments and dyes.

Examples of dye derivatives that can be preferably used in the present invention include the following general formulas (1) to (3).
The compound represented by

General formula (1):

In the general formula (1), P is an n ₁ -valent organic dye residue, n ₁ is an integer of 1 or more, and Z ₁ is a sulfonic acid group or a carboxyl group. n ₁ is preferably ₁ to 5, more preferably 1 to 3, still more preferably 1 to 2, and most preferably 1. Further, Z ₁ is preferably a sulfonic acid group.

General formula (2):

In the general formula (2), P is an n ₂ -valent organic dye residue, n ₂ is an integer of 1 or more, Z ₂ is SO ₃ ⁻ or COO ⁻ , Z ₃ is an alkali metal cation, NH ₄ ^+. , Primary ammonium cation, secondary ammonium cation, tertiary ammonium cation, or quaternary ammonium cation. n ₂ is preferably 1-5, more preferably 1-
3, more preferably 1 to 2, most preferably 1.

General formula (3):

In the general formula (3), P is an n ₃ -valent organic dye residue, n ₃ is an integer of 1 or more, and R ₁ is an organic group represented by the following general formula (4). n ₃ is preferably 1 to 5, more preferably 1 to 3, still more preferably 1 to 2, and most preferably 1.

General formula (4):

In the general formula (4), R ₂ represents a (m+1)-valent organic residue, m represents an integer of 1 or more, and R ₃ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 10 carbon atoms. R ₂ has 1 carbon
It is preferably an alkylene group having 10 to 10, more preferably an alkylene group having 1 to 5 carbon atoms.
Further, it is preferable that all R ₃ are hydrogen atoms.

In the general formulas (1) to (3), the structure of the organic dye residue (P) is not necessarily C
． I. Pigment Red 185 need not match the structure of C.I. I
． Pigment Red 185, that is, the organic dye residue (P)
Is preferably a monoazo dye residue or a benzimidazolone dye residue. As a result, C.I. I. Pigment Red 185 is easily adsorbed, and the effect of improving dispersion stability is easily exhibited.

When the pigment derivative represented by the general formula (4) is used in combination with a pigment dispersion resin having an aromatic ring structure, C.I. I. Pigment Red 185 can be miniaturized and the particle size distribution can be narrowed. As a result, the amount of coarse particles contained in the water-based ink is remarkably reduced, so that the ejection stability from the inkjet head and the dispersion stability can be improved. Further, it is possible to obtain a printed matter having excellent color reproducibility.

When the dispersion aid is used in the present invention, its blending amount is C.I. I. Pigment Red 185 is preferably added in an amount of 0.1 to 10% by mass, and particularly preferably 0.5 to 5% by mass. When the content is 0.1% by mass or more, C.I. I. Pigment Red 185 has a sufficient addition ratio, and dispersion stability, ejection stability, and color reproducibility of printed matter are improved. When the content is 10% by mass or less, the fineness of the pigment is prevented from progressing more than necessary.
It is possible to improve the dispersion stability and prevent deterioration of the light resistance of the printed matter.

<Binder resin (A)>
In the water-based inkjet ink of the present invention, the binder resin (A) is used to improve the scratch resistance of the printed matter. Two or more resins may be used in combination as the binder resin (A). In that case, at least one of the two or more resins is the binder resin (a-1) described later.

The "binder resin" in the present specification is a resin used for binding a layer of a printed matter (printing layer, ink layer) to a recording medium. As described below, the ink of the present invention may contain a pigment-dispersed resin, but the pigment-dispersed resin and the binder resin are distinguished by the adsorption rate to the pigment. That is, a resin having an adsorption rate of 50% by mass or more with respect to the total amount of the pigment is determined as a pigment dispersion resin, and a resin having an adsorption rate of less than 50% by mass is determined as a binder resin.

As a method of confirming whether the resin present in the water-based ink is the binder resin in the present specification, there is a method of measuring the adsorption rate with respect to the pigment. For example, if necessary, an aqueous ink diluted with water is subjected to a centrifugal separation treatment (for example, at 30,000 rpm for 4 hours) to separate the pigment and the supernatant. Then, when the solid content contained in the supernatant liquid is measured and the solid content is larger than 50% by mass with respect to the total amount of the resin contained in the aqueous ink, the resin is judged to be a binder resin.

Water-soluble resins and resin fine particles are generally known as forms of binder resins for water-based inks, and either one may be selected and used in the present invention, or both may be used in combination. For example, the resin fine particles have a higher molecular weight than the water-soluble resin, can enhance the scratch resistance of the printed matter, and are excellent in the image quality of the printed matter. A water-based inkjet ink using a water-soluble resin as a binder resin has excellent ejection stability. In the present specification, the term “water-soluble resin” refers to a resin that is not the above-mentioned water-insoluble resin, that is, a resin in which a 25° C./1% by mass water mixture of the target resin is transparent to the naked eye. ..

As described above, the inkjet ink of the present invention contains the binder resin (a-1) having an acid value of 1 to 80 mgKOH/g as the binder resin (A). In addition, C.I. I. Pigment Red 185 preferably has a dispersion stability of 3 to 60 mgKOH/g, particularly preferably from the viewpoint that a printed matter having excellent image quality can be obtained by rapidly moving to a gas-liquid interface. It is 5-40 mgKOH/g. The binder resin (a-1)
The acid value of can be measured in the same manner as the acid value of the pigment dispersion resin.

Examples of the binder resin (A) used in the present invention include acrylic resin, styrene acrylic resin, urethane resin, urethane-acrylic composite resin, styrene butadiene resin, vinyl chloride resin, styrene maleic acid resin, ester resin, olefin resin and the like. To be Among them, the binder resin (a-1) is made of an acrylic resin, a styrene-acrylic resin, a urethane resin, a urethane-acrylic composite resin, and an olefin resin from the viewpoint that an ink having excellent dispersion stability and ejection stability can be obtained. It is preferred to use one or more resins selected from the group. In general, urethane resins, urethane-acrylic composite resins, and olefin resins have low glass transition temperatures, and therefore are suitably selected from the viewpoint of adhesion to non-permeable substrates such as plastic substrates and image quality.

The glass transition temperature of the binder resin (A) can be selected, for example, as follows according to the required characteristics. Specifically, it improves ejection stability and scratch resistance of printed matter, and is also excellent in drying resistance and blocking resistance (a phenomenon in which a printing layer sticks to another recording medium when the recording media after printing are stacked). In order to obtain the ink, the glass transition temperature is preferably 60 to 140°C, more preferably 70 to 135°C, and particularly preferably 80 to 130°C.

On the other hand, when the ink of the present invention is used for a non-permeable base material such as a plastic base material, from the viewpoint of image quality and adhesion, urethane resin, urethane-acrylic composite resin, and olefin resin are used. One or more resins selected from the group consisting of and/or a glass transition temperature of -120 to 45°C (preferably -80 to 25°C, more preferably -).
It is preferable to use one or more resins selected from the group consisting of acrylic resins having a temperature of 60 to 15° C.) and styrene acrylic resins.

The glass transition temperature is a value measured using a DSC (differential scanning calorimeter), and can be measured as follows, for example. About 2 mg of the dried resin sample was weighed on an aluminum pan,
A DSC measuring device (for example, DSC-manufactured by Shimadzu Corporation) using the aluminum pan as a test container
Set it in the holder inside 60Plus). Then, the measurement is performed under a temperature rising condition of 5° C./min,
The temperature of the baseline shift read from the obtained DSC chart is the glass transition temperature in this specification.

Further, from the viewpoints of adhesion to a plastic substrate, scratch resistance of printed matter, and blocking resistance, as a binder resin (a-1), an olefin resin, an acrylic resin, a styrene acrylic resin, a urethane resin, and a urethane resin. It is preferable to include one or more kinds of resins selected from acrylic composite resins.

The binder resin (A) can be synthesized by a known method or a commercially available product can be used. The structure is also not particularly limited, and for example, a resin having a random structure, a block structure, a comb structure, a star structure, or the like can be used.

When a water-soluble resin is used as the binder resin (a-1) in the present invention, its weight average molecular weight ensures ejection stability from an inkjet nozzle, and excellent adhesion and resistance to various recording media. 5,000 to 5 from the viewpoint that a printed matter having scratch resistance can be obtained.
It is preferably 50,000, more preferably 8,000 to 45,000, still more preferably 10,000 to 40,000.

The weight average molecular weight of the binder resin (a-1) in the present invention can be measured by a conventional method. For example, a polystyrene conversion value measured using THF as a developing solvent using a GPC measuring device (HLC-8120GPC manufactured by Tosoh Corporation) equipped with a TSKgel column manufactured by Tosoh Corporation and an RI detector is a weight average in the present specification. The molecular weight.

The content of the binder resin (A) with respect to the total amount of the ink is preferably 1 to 15% by mass, more preferably 2 to 12% by mass, and further preferably 4 to 10% by mass in terms of solid content. preferable. By setting the amount of the binder resin (A) within the above range, it is possible to obtain an ink excellent in scratch resistance, drying property, and further image quality of printed matter without lowering dispersion stability and discharge stability. it can.

Further, from the viewpoint that an ink having excellent dispersion stability and ejection stability as well as excellent adhesion to a plastic substrate and image quality can be obtained, the content of the binder resin (a-1) is not limited to the binder resin (A ) It is preferably 20 to 100% by mass, more preferably 35 to 100% by mass, and particularly preferably 50 to 100% by mass based on the total amount.

<Surfactant>
In the present invention, by using in combination with the binder resin (a-1), ejection stability,
From the viewpoint that an aqueous inkjet ink having excellent image quality of printed matter and excellent drying property can be obtained, at least one surfactant is contained. Generally, as a surfactant, an acetylene diol type,
A variety of acetylene alcohol-based, siloxane-based, acrylic-based, fluorine-based, polyoxyalkylene-based, etc. are known according to the application, but the water-based inkjet ink of the present invention is based on acetylene diol-based and/or siloxane-based. It is preferable to include a surfactant, and it is particularly preferable to include a siloxane-based surfactant. The acetylene diol-based surfactant and the siloxane-based surfactant are C.I. present in the droplets of the aqueous ink after landing on the recording medium. I. It is considered that the pigment is rapidly oriented to the interface without being affected by Pigment Red 185. As a result, the wettability of the water-based ink can be improved even on a non-permeable substrate, and the ink droplets can be promptly smoothed. In addition to the improvement in the drying property, the bleeding and the contrast of the droplets can be improved. It is possible to obtain a printed matter with less unevenness and excellent image quality. When a siloxane-based surfactant is used, in addition to the above, the scratch resistance of the printed matter is also improved. In particular, in the present invention, although details are unclear, an acetylene diol-based surfactant and a siloxane-based surfactant are used in combination because an aqueous ink excellent in ejection stability is obtained in addition to the above-mentioned characteristics improvement. Is preferred.

Examples of the acetylene diol-based surfactant used in the present invention include 2,4,7,9
-Tetramethyl-5-decyne-4,7-diol, 2,5,8,11-tetramethyl-6
-Dodecin-5,8-diol, hexadec-8-yne-7,10-diol, 6,9-
Dimethyl-tetradec-7-yne-6,9-diol, 7,10-dimethylhexadeca-
Examples include, but are not limited to, 8-in-7,10-diol and its ethylene oxide and/or propylene oxide adducts.

The siloxane-based surfactant that can be preferably used in the present invention has, for example, one or more ethylene oxide groups and/or one or more propylene oxide groups at the side chain and/or both ends of the polydimethylsiloxane chain. Examples thereof include siloxane-based surfactants. Specifically, 8032 ADDITIVE, FZ-2104, F manufactured by Toray Dow Corning
Z-2120, FZ-2122, FZ-2162, FZ-2164, FZ-2166, F
Z-2404, FZ-7001, FZ-7002, FZ-7006, L-7001, L-
7002, SF8427, SF8428, SH3748, SH3749, SH3771M
, SH3772M, SH3773M, SH3775M, SH8400, BYK-331, BYK-333, BYK-345, BYK-346, BYK-347 manufactured by Big Chemie.
, BYK-348, BYK-349, BYK-UV3500, BYK-UV3510, B
YK-UV3530, BYK-UV3570, TEGOWet250 manufactured by Evonik,
TEGOWet 260, TEGOWet 270, TEGOWet 280, TEGOGli
de410, TEGOGlide432, TEGOGlide435, TEGOGlid
e440, TEGOGlide 450, KF-351A, KF-35 manufactured by Shin-Etsu Chemical Co., Ltd.
2A, KF-353, KF-354L, KF-355A, KF-615A, KF-640
, KF-642, KF-643, KF-644, KF-945, KF-6011, KF-
6012, KF-6015, KF-6017, KF-6020, KF-6204, X-2
2-4515, Silface SAG series manufactured by Nissin Chemical Industry Co., Ltd., and the like.

In addition, examples of the polyoxyalkylene-based surfactant that can be preferably used in the present invention include compounds represented by the following general formula (1).

General formula (1):

R-O-(EO)m-(PO)n-H

In the general formula (1), R is an alkyl group having 8 to 22 carbon atoms, or 8 to 22 carbon atoms.
Is an alkenyl group having 8 to 22 carbon atoms, or an alkylcarbonyl group having 8 to 22 carbon atoms, or 8 to
22 represents an alkenylcarbonyl group. The R may have a branched structure. EO represents an ethylene oxide group and PO represents a propylene oxide group. m is the number of average added moles of EO, is a number of 2 to 50, n is the number of average added moles of PO, 0 to 5
It is a number of zero. When n is not 0, the addition order of (EO)m and (PO)n does not matter, and the addition may be block or random.

It is preferable that the surfactant used in the present invention is divided into a hydrophobic group and a hydrophilic group in the molecule. Therefore, of the above-exemplified surfactants, those having a hydrophilic ethylene oxide group are particularly preferably selected.

Further, from the viewpoint that the affinity with the binder resin (a-1) is enhanced, an ink having excellent dispersion stability and ejection stability can be obtained, and a printed matter having excellent image quality without bleeding and uneven density can be obtained. , It is preferable to use a surfactant having an HLB value of 0 to 5, and it is particularly preferable to include a surfactant having an HLB value of 0 to 4.

In particular, in addition to dispersion stability and ejection stability, on a non-permeable substrate such as a plastic substrate, there is little bleeding between ink droplets and uneven density, and a printed matter with excellent image quality can be obtained. A surfactant having an HLB value of 0 to 5 (preferably 0 to 4) and an HLB value of 6 to 18
It is preferable to use together with a surfactant (preferably 7 to 18, particularly preferably 8 to 16).

The HLB (Hydrophile-Lipophile Balance) value is one of the parameters indicating the hydrophilicity/hydrophobicity of a material, and the smaller the value, the higher the hydrophobicity, and the larger the value, the higher the hydrophilicity. Various methods for calculating the HLB value from the chemical structure are known, and various methods for actual measurement are also known. In the present invention, like the acetylene diol-based surfactants and polyoxyalkylene-based surfactants, If the structure of the compound is clearly known,
The HLB value is calculated using the Griffin method. The Griffin method is a method of calculating the HLB value using the following formula (2) using the molecular structure and molecular weight of the target material.

Formula (2):

HLB value=20×(sum of molecular weight of hydrophilic part)÷(molecular weight of material)

On the other hand, when a compound of unknown structure such as a siloxane-based surfactant is contained, for example, refer to "Handbook of Surfactants" (edited by Nishiichiro et al., Sangyo Tosho Co., Ltd., 1960), p. The HLB value of the surfactant can be experimentally determined by the following method described in H.324. Specifically, 0.5 g of a surfactant is dissolved in 5 mL of ethanol, and then the solution is diluted with 25
The mixture was titrated with a 2% by mass aqueous phenol solution while stirring at 0° C., and the point where the solution became cloudy was taken as the end point. When the amount of the phenol aqueous solution required up to the end point is A (mL), the following formula (3
), the HLB value can be calculated.

Formula (3):

HLB value=0.89×A+1.11

The content of the surfactant (B) in the inkjet ink of the present invention is preferably 0.2 to 4 mass% with respect to the total amount of the ink. More preferably, it is 0.5 to 2 mass %.

<Water-soluble organic solvent>
The water-based inkjet ink of the present invention contains a water-soluble organic solvent. In the present invention, alcohol-based solvents, glycol ether-based solvents, polyalkylene glycol-based solvents and the like can be preferably used as the water-soluble organic solvent. The term "water-soluble organic solvent" used herein means 25°C.
-At 1 atm, the solubility in water is 5 g/100 g H ₂ O or more, and indicates a liquid. Further, among the pH adjusters described later, those which satisfy the above conditions are included in the water-soluble organic solvent.

As described above, the aqueous inkjet ink of the present invention has a boiling point of 24 at 1 atm.
The content of the water-soluble organic solvent at 0° C. or higher is 8% by mass or less (may be 0% by mass) with respect to the total amount of the aqueous inkjet ink. In particular, a water-soluble organic compound having a boiling point of 240° C. or more at 1 atm from the viewpoint of obtaining a printed matter having excellent drying properties, image quality, and scratch resistance with respect to a non-permeable substrate such as a plastic substrate. The content of the solvent is 5% by mass or less (
0% by mass is more preferable, 2% by mass or less is more preferable (may be 0% by mass), and 1% by mass or less (may be 0% by mass) ) Is particularly preferable.

The boiling point under 1 atmosphere can be measured by using a thermal analyzer such as DSC (Differential Scanning Calorimetry).

Examples of the water-soluble organic solvent having a boiling point of 240° C. or more under 1 atmosphere include glycerin, 3-methyl-1,5-pentanediol, 1,6-hexanediol, triethylene glycol monomethyl ether, and triethylene glycol monobutyl ether. , Tetraethylene glycol dimethyl ether, diethylene glycol, triethylene glycol, tripropylene glycol, tetrapropylene glycol, 2-pyrrolidone, ε-caprolactone, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600 and the like.

The water-soluble organic solvent used in the present invention has a weighted average value of boiling points of 100 to 1 atm.
It is preferably 235°C, more preferably 120 to 210°C, and 120 to 210°C.
It is particularly preferable that the temperature is 195°C. Further, in consideration of the image quality on a non-permeable substrate such as a plastic substrate, 120 to 180° C. is particularly suitable. When the weighted average value of the boiling points of the water-soluble organic solvent at 1 atm is 100° C. or higher, the ejection stability from the inkjet head is improved. Further, when the weighted average value is 235° C. or less, the drying quality does not occur on the recording medium, and the remaining water-soluble organic solvent does not cause bleeding between the water-based ink droplets and improves the image quality. In addition, the adhesion to the non-permeable substrate such as the plastic substrate and the scratch resistance of the printed matter are improved. In addition, in the calculation of the weighted average value of the boiling points, the water-soluble organic solvent having a boiling point of 240° C. or more under 1 atmosphere is also included. In addition, the weighted average value of boiling points under 1 atm is obtained by adding the multiplied values of the boiling points under 1 atm calculated for each water-soluble organic solvent and the mass ratio to the total amount of the water-soluble organic solvent. This is the value obtained.

Further, from the viewpoint of keeping the weighted average value of the boiling points of the water-soluble organic solvent within the above range, the blending amount of the water-soluble organic solvent having a boiling point of 100 to 220° C. under 1 atmosphere is equal to the total amount of the water-soluble organic solvent in the ink. On the other hand, it is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 85% by mass or more.

Illustrating the water-soluble organic solvent preferably used in the present invention,
As monohydric alcohol solvents, ethanol, 1-propanol, isopropanol, 1
-Butanol, 2-butanol, 3-butanol, isobutanol, 3-methoxy-1-
Butanol, 3-methoxy-3-methyl-1-butanol, etc.
As the dihydric alcohol solvent (diol solvent), ethylene glycol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4 -Butanediol, 2,3-butanediol,
1,2-pentanediol, 1,3-pentanediol, 1,2-hexanediol, 2
-Methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol,
3-methyl-1,3-butanediol, etc.
Examples of trivalent or higher alcohol-based solvents (polyol-based solvents) include 1,2,4-butanetriol and diglycerin.
As the glycol ether solvent, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, diethylene glycol monoisopropyl ether, Diethylene glycol monoisobutyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Methyl butyl ether, triethylene glycol methyl butyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, triethylene glycol methyl ethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, propylene glycol monomethyl Ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, propylene glycol dimethyl ether, tripropylene glycol dimethyl ether, etc.
As a polyalkylene glycol solvent, dipropylene glycol, etc.
As the chain amide solvent, N,N-dimethylformamide, N,N-dimethyl-β-methoxypropionamide, N,N-dimethyl-β-ethoxypropionamide, N,N-
Dimethyl-β-butoxypropionamide, N,N-dimethyl-β-pentoxypropionamide, N,N-dimethyl-β-hexoxypropionamide, N,N-dimethyl-β
-Heptoxypropionamide, N,N-dimethyl-β-2-ethylhexoxypropionamide, N,N-dimethyl-β-octoxypropionamide, N,N-diethyl-β
-Butoxypropionamide, N,N-diethyl-β-pentoxypropionamide, N
, N-diethyl-β-hexoxypropionamide, N,N-diethyl-β-heptoxypropionamide, N,N-diethyl-β-octoxypropionamide and the like,
As a cyclic amide solvent, N-methylpyrrolidone, N-ethylpyrrolidone, etc.
As a cyclic carbamate solvent, 3-methyl-2-oxazolidinone, 3-ethyl-2
-Oxazolidinone, etc.
Each is mentioned, but not limited to.

The water-soluble organic solvent used in the present invention, a printed matter having excellent image quality and dryness is obtained,
From the viewpoint of obtaining an aqueous ink having excellent compatibility with the binder resin (a-1) and the surfactant, and further, having a low viscosity of the water-soluble organic solvent itself and an excellent ejection stability, the hydroxyl group is 1 A water-soluble organic solvent having one or two is suitably selected. Above all, although details are unknown,
C. I. Pigment Red 185 is less likely to adversely affect the dispersion stability,
A water-soluble organic solvent having two hydroxyl groups, that is, a diol solvent is particularly preferably selected.

Among the diol-based solvents, it is preferable to use at least one alkanediol having 2 to 5 carbon atoms, more preferably an alkanediol having 3 to 4 carbon atoms, and particularly preferably an alkanediol having 3 carbon atoms. is there.

The content of the water-soluble organic solvent used in the present invention is 1 to the total amount of the inkjet ink.
It is preferably 30% by mass. In addition, ensuring ejection stability on the inkjet head,
It is more preferably 3 to 27% by mass, and even 5 to 25% by mass from the viewpoint that a printed matter having excellent adhesion, drying property, and image quality can be obtained even with a non-permeable material. Is particularly preferable.

<Water>
As the water contained in the water-based inkjet ink of the present invention, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions. Further, the content thereof is preferably in the range of 20 to 90% by mass in the total mass of the ink.

<Other ingredients>
In addition to the above components, the water-based inkjet ink of the present invention may optionally contain a pH adjustor in order to obtain an ink having desired physical properties. As a compound that can be used as a pH adjuster, for example,
Examples of the alkanolamine include triethylamine, monoethanolamine, diethanolamine, N-methyldiethanolamine, dimethylaminoethanol, diethylaminoethanol, aminomethylpropanol, and the like.
Other nitrogen-containing compounds include ammonia water, monoethylamine, diethylamine, triethylamine, cyclohexylamine, benzylamine, urea and piperidine.
Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide,
As alkali metal carbonates, lithium carbonate, sodium carbonate, sodium hydrogen carbonate,
Potassium carbonate,
As the acidic compound, hydrochloric acid, sulfuric acid, acetic acid, citric acid, maleic acid, maleic anhydride, succinic acid, tartaric acid, malic acid, phosphoric acid, boric acid, fumaric acid, malonic acid, ascorbic acid, glutamic acid, etc.
Each is mentioned, but not limited to. The above pH adjusters may be used alone or in combination of two or more.

The blending amount of the pH adjusting agent is preferably 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, and 0.2 to 1.5% by mass with respect to the total amount of the aqueous inkjet ink.
Is most preferable.

In addition to the above components, the water-based inkjet ink of the present invention may further contain additives such as defoaming agents, preservatives, infrared absorbers, and ultraviolet absorbers in order to obtain ink having desired physical properties. Can be added appropriately. The addition amount of these additives is preferably 0.01 to 10 mass% with respect to the total mass of the ink.

The aqueous inkjet ink of the present invention preferably contains substantially no polymerizable monomer.

<pKa value of nitrogen-containing compound>
As described above, the water-based inkjet ink of the present invention includes a water-soluble organic solvent and/or p.
A nitrogen-containing compound can be used as the H adjuster. On the other hand, depending on the nitrogen-containing compound used, C.I. I. Since the dispersion stability and the ejection stability of Pigment Red 185 may be adversely affected, it is preferable to limit the amount in the present invention.

Specifically, the total amount of the chain amide-based solvent, the cyclic amide-based solvent, and the cyclic carbamate-based solvent is 3% by mass or less (may be 0% by mass) with respect to the total amount of the aqueous inkjet ink. The amount is preferably 1% by mass or less (more preferably 0% by mass). Although the detailed reason is unknown, when a large amount of these compounds is blended, dispersion stability and ejection stability tend to be deteriorated.

Even for compounds other than the above, the pKa value at 25° C. is 2 or less (preferably,
The pKa value is 4 or less), or 10 or more (preferably the pKa value is 9.5 or more).
As for the nitrogen-containing compound, the total amount of the compounded compound is 3 with respect to the total amount of the water-based inkjet ink.
The amount is preferably not more than mass% (may be 0 mass%), and is preferably not more than 1 mass% (0 mass%
Is also preferable). This is because these compounds have strong acidity or basicity and may also adversely affect dispersion stability and ejection stability.

The pKa value of the present invention can be measured by a known method, for example, a potentiometric titration method. Further, as an example of a nitrogen-containing compound having a pKa value of 2 or less at 25° C., urea (pKa value=0
． 2), and examples of the nitrogen-containing compound having a pKa value at 25° C. of 10 or more include cyclohexylamine (pKa value=10.6) and monoethylamine (pKa value=1.
0.7), diethylamine (pKa value=11.0), triethylamine (pKa value=10)
． 7) and piperidine (pKa value=11.2).

<Method for producing water-based inkjet ink>
The water-based inkjet ink of the present invention comprising the above components can be produced by a known method. Particularly, from the viewpoint that an ink having excellent dispersion stability and ejection stability can be obtained, C.I.
I. A manufacturing method in which a pigment dispersion liquid containing Pigment Red 185 is manufactured in advance and then the pigment dispersion liquid, the binder resin (a-1), the surfactant and the like are mixed is suitably selected. Hereinafter, an example of the method for producing the water-based inkjet ink of the present invention will be described, but as described above, the production method is not limited to the following.

(1) Production of Pigment Dispersion Liquid (1-1) Method of Dispersing Treatment Using Water-Soluble Pigment Dispersion Resin When a water-soluble resin is used as the pigment dispersion resin, the pigment dispersion resin, water, and water-soluble as necessary. The organic solvent is mixed and stirred to prepare an aqueous pigment dispersion resin solution. In the pigment dispersion resin aqueous solution, C.I. I. Pigment Red 185 is added, mixed and stirred (premixing), and then dispersed using a disperser. Then, if necessary, centrifugation, filtration, and adjustment of solid content are performed to obtain a pigment dispersion liquid.

(1-2) Method of Dispersing Treatment Using Water-Insoluble Pigment Dispersion Resin Further, C.I. I. In the case of producing a dispersion liquid of Pigment Red 185, a pigment dispersion resin solution is prepared by dissolving the pigment dispersion resin in an organic solvent such as methyl ethyl ketone in advance and neutralizing the pigment dispersion resin as needed. To the pigment dispersion resin solution, C.I. I. Pigment Red 185 and water are added,
After mixing and stirring (premixing), dispersion treatment is performed using a disperser. Then, the organic solvent is distilled off by vacuum distillation, and if necessary, centrifugal separation, filtration, and solid content adjustment are carried out to obtain a pigment dispersion liquid.

In the above methods (1-1) and (1-2), C.I. I. The disperser used in the dispersion treatment of Pigment Red 185 may be any commonly used disperser,
Examples include ball mills, roll mills, sand mills, bead mills, and nanomizers. Among the above, the bead mill is preferably used, and specifically, it is commercially available under the trade name of super mill, sand grinder, agitator mill, gren mill, dyno mill, pearl mill, cobol mill and the like.

In the above methods (1-1) and (1-2), as a method of controlling the particle size distribution of the pigment dispersion liquid, the size of the grinding media of the above-mentioned disperser is adjusted, and the material of the grinding media is changed. To increase the filling rate of the grinding media, to change the shape of the stirring member (agitator), to lengthen the dispersion processing time, to classify with a filter or centrifuge after the dispersion processing, and these methods The combination of In order to keep the pigment in a suitable particle size range, it is preferable that the diameter of the grinding media of the disperser is 0.1 to 3 mm. Further, glass, zircon, zirconia, and titania are preferably used as the material of the grinding media.

(1-3) Method of Grinding and Kneading Treatment Using Pigment Dispersion Resin Furthermore, in the present invention, the method of grinding and kneading treatment described below can also be preferably used. C. I.
Pigment Red 185, the pigment-dispersed resin, the water-soluble organic solvent, and the inorganic salt are kneaded by a kneader, and then water is added to the resulting mixture, and the mixture is stirred. Then, the inorganic salt and, if necessary, the water-soluble organic solvent are removed by centrifugation, filtration, and washing, and the solid content is further adjusted to obtain a pigment dispersion liquid.

The kneader used in the above method (1-3) may be any generally used disperser, but a high-viscosity mixture can be kneaded and a pigment dispersion liquid containing fine pigments can be obtained. The kneader or trimix is preferably used from the viewpoint that a printed matter having excellent quality and color reproducibility can be obtained. The particle size distribution of the resulting pigment dispersion can be controlled by adjusting the temperature during kneading.

As the inorganic salt, sodium chloride, barium chloride, potassium chloride, sodium sulfate, potassium sulfate and the like can be preferably used.

(2) Preparation of Aqueous Inkjet Ink In the pigment dispersion obtained above, the binder resin (a-1), the surfactant, the water-soluble organic solvent, water, and, if necessary, the above-mentioned pH adjuster and Add other additives and stir/mix. If necessary, the mixture may be stirred and mixed while being heated in the range of 40 to 100°C.

(3) Removal of Coarse Particles Coarse particles contained in the above mixture are removed by a technique such as filtration separation and centrifugation to obtain an aqueous inkjet ink. As a method for filtering and separating, a known method can be appropriately used. When a filter is used, its pore size is preferably 0.3 to 5 μm, more preferably 0.5 to 3 μm. When performing filtration, the filter may be used alone or in combination of two or more.

<Characteristics of water-based inkjet ink>
The aqueous inkjet ink of the present invention preferably has a viscosity at 25° C. adjusted to 3 to 20 mPa·s. Within this viscosity range, stable ejection characteristics are exhibited from a head having a normal frequency of 4 to 10 KHz to a high frequency head of 10 to 70 KHz. In particular, by setting the viscosity at 25° C. to 4 to 10 mPa·s, stable ejection can be performed even when used for an inkjet head having a design resolution of 600 dpi or more. The viscosity can be measured by a conventional method. Specifically, it can be measured using an E type viscometer (TVE25L type viscometer manufactured by Toki Sangyo Co., Ltd.) and 1 mL of ink.

In addition, the water-based inkjet ink of the present invention has a static surface tension of 18 to 35 mN/m at 25° C. from the viewpoint of obtaining a water-based inkjet ink that can be stably ejected and a printed material having excellent image quality. Is preferable and 20-32 mN/m is especially preferable. The static surface tension refers to the surface tension measured by the Wilhelmy method under an environment of 25° C., and can be measured using a platinum plate using CBVP-Z manufactured by Kyowa Interface Science Co., Ltd., for example.

Furthermore, from the viewpoint that the surfactant is oriented immediately after landing on the recording medium, and excellent image quality is obtained by obtaining suitable wettability on the recording medium, the inkjet ink of the present invention has a maximum bubble pressure method. According to the above, the dynamic surface tension at 10 milliseconds is preferably 26 to 36 mN/m, more preferably 28 to 36 mN/m, particularly preferably 30 to 36 mN.
/M. The dynamic surface tension in the present specification can be measured in a 25° C. environment using, for example, a bubble pressure dynamic surface tensiometer BP100 manufactured by Kruss.

The aqueous inkjet ink of the present invention preferably has an average secondary particle diameter (D50) of the pigment of 40 to 500 nm, more preferably 50 to 400 nm, particularly preferably 50 to 400 nm, in order to obtain a printed matter having excellent color developability. It is preferably 60 to 300 nm. In order to keep the average secondary particle diameter within the preferable range, the pigment dispersion treatment step may be controlled as described above.
The average secondary particle diameter (D50) of the pigment means a median diameter measured by a dynamic light scattering method using a particle size distribution measuring instrument (for example, Microtrac UPAEX-150 manufactured by Microtrac Bell).

<Set of water-based inkjet ink>
The water-based inkjet ink of the present invention may be used in a single color, but may also be used as a set of water-based inkjet ink in which a plurality of colors are combined according to the application. Above all, by using in combination with the yellow ink and/or the magenta ink, it is possible to obtain a printed matter having excellent color reproducibility especially in the red region. Also, by adding black ink, it is possible to improve the feeling of blackness and improve the visibility of characters and the like. Furthermore, when printing on a recording medium other than white, a clear image can be obtained by using white ink together.

<Ink-pretreatment liquid set>
The water-based inkjet ink of the present invention is combined with a pretreatment liquid containing a flocculant to form an ink-
It can also be used in the form of a pretreatment liquid set. By applying the pretreatment liquid containing the aggregating agent onto the recording medium, it is possible to form a layer (ink aggregating layer) for intentionally aggregating the solid component contained in the aqueous inkjet ink. By causing the water-based inkjet ink to land on the ink aggregation layer, bleeding between ink droplets and color unevenness can be prevented, and the image quality of printed matter can be significantly improved. Further, depending on the material used in the pretreatment liquid, the adhesion, scratch resistance, and blocking resistance of the printed matter can also be improved.

The term “aggregating agent” as used herein means to destroy the dispersed state of pigments or resin fine particles to cause aggregation, and/or to insolubilize the water-soluble resin to increase the viscosity of the aqueous inkjet ink, which is contained in the aqueous inkjet ink. Means an ingredient that can The aggregating agent used in the pretreatment liquid to be combined with the aqueous inkjet ink of the present invention preferably contains at least one selected from metal salts and cationic polymer compounds from the viewpoint of significantly improving image quality. Among them, from the viewpoint of obtaining excellent image quality, it is preferable to use a metal salt as the aggregating agent, and a polyvalent metal selected from the group consisting of Ca ²⁺ , Mg ²⁺ , Zn ²⁺ and Al ^3+. It is particularly preferred to include ionic salts. When a metal salt is used as the aggregating agent, the content thereof is preferably 2 to 30 mass% with respect to the total amount of the pretreatment liquid, and 3 to
It is particularly preferably 25% by mass.

In addition, an organic solvent, a surfactant, a pH adjuster, an antifoaming agent, an antiseptic agent, etc. can be appropriately added to the pretreatment liquid. The materials that can be specifically used are the same as those in the case of the water-based inkjet ink.

The static surface tension of the pretreatment liquid is 20 to 45 mN/m from the viewpoint that a printed matter having excellent image quality can be obtained when used in combination with the water-based inkjet ink of the present invention.
Is more preferable, and it is more preferable that it is 23-40 mN/m. It is particularly preferably 25 to 37 mN/m. The static surface tension of the pretreatment liquid can be measured by the same method as the static surface tension of the water-based inkjet ink.

<Inkjet recording method>
The water-based inkjet ink of the present invention is used in a recording method in which it is discharged from an inkjet head and applied onto a recording medium.

As the pass method in the inkjet recording method, a single-pass method in which inkjet ink is ejected onto a recording medium only once for recording, and a short shuttle head is reciprocally scanned in a direction perpendicular to the conveying direction of the recording medium. However, either of the serial method of discharging and recording may be adopted. However, in the case of the serial method, it is necessary to adjust the ejection timing in consideration of the movement of the inkjet head, and the landing position is likely to shift. Therefore, when printing the water-based inkjet ink of the present invention, a single-pass method,
In particular, a pass system in which the recording medium is passed under the fixed inkjet head is preferably used.

There is no particular limitation on the method of ejecting ink, and known methods such as a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezo element, a bubble is formed by heating ink, and the generated pressure is controlled. A thermal inkjet (bubble jet [registered trademark]) method or the like to be used can be used.

In addition, the amount of ink droplets ejected from the inkjet head is 0.2 to 30 picoliters from the viewpoint of a great effect of reducing the drying load, and the improvement of color reproducibility and other image quality. It is more preferably 1 to 20 picoliters.

It is preferable to provide a mechanism for drying the ink on the recording medium after the aqueous inkjet ink of the present invention is applied on the recording medium by an inkjet printing method. As a drying method used in the drying mechanism, a heat drying method, a hot air drying method, an infrared ray (for example, a wavelength of 700 to
2500 nm infrared ray) drying method, microwave drying method, drum drying method and the like.

In the present invention, from the viewpoint of preventing bumping of the liquid component in the ink and obtaining a printed matter excellent in color reproducibility and image quality, when the heat drying method is adopted, the drying temperature is set to 35 to 100°C.
When the hot air drying method is adopted, the hot air temperature is preferably 50 to 250°C. From the same viewpoint, when the infrared drying method is adopted, it is preferable that 50% or more of the integrated value of all outputs of infrared rays used for infrared irradiation be present in the wavelength region of 700 to 1500 nm.

The above drying methods may be used alone, a plurality of them may be continuously used, or they may be used in combination at the same time. For example, by using the heating drying method and the hot air drying method together, the ink can be dried more quickly than when each is used alone.

<Recording medium>
The recording medium for printing the ink of the present invention is not particularly limited, and any known recording medium can be used. Among them, a non-permeable substrate or a difficult-to-penetrate substrate is suitable, and it can be particularly suitably used for a non-permeable substrate. In this specification, the permeability of the recording medium is judged by the amount of water absorption measured by a dynamic scanning liquid absorption meter. Specifically, a recording medium having a water absorption of pure water of less than 1 g/m ² at a contact time of 100 msec, which is measured by the following method, is defined as an “impermeable substrate” and is 1 to 10 g/m ² . The recording medium is referred to as a "hardly penetrable base material".

The water absorption of the recording medium can be measured, for example, under the following conditions. KM500win manufactured by Kumagai Riki Kogyo Co., Ltd. was used as a dynamic scanning liquid absorption meter, and a pure water was used under the following conditions using a recording medium of about 15 to 20 cm square at 23° C. and 50% RH. The transfer amount of
・Measurement method: Spiral scanning
・Measurement start radius: 20mm
・Measurement end radius: 60mm
・Contact time: 10 to 1,000 msec
・Sampling points: 19 (measured at almost equal intervals to the square root of the contact time)
・Scan interval: 7 mm
-Rotary table speed switching angle: 86.3 degrees-Headbox condition: width 5 mm, slit width 1 mm

Examples of non-permeable or hardly permeable substrates are polyvinyl chloride, polyethylene terephthalate (PET), plastic substrates such as polypropylene, polyethylene, nylon, polystyrene, polyvinyl alcohol, coated paper, art paper, cast paper. Examples of such coated paper bases, metal bases such as aluminum, iron, stainless steel and titanium, and glass bases. The above-mentioned substrate may have a smooth surface of the print medium, may have irregularities, or may be transparent, semitransparent, or opaque. Also, two or more of these recording media may be stuck together. Further, a release adhesive layer or the like may be provided on the side opposite to the printed surface, and an adhesive layer or the like may be provided on the printed surface after printing. The shape of the recording medium used in the inkjet recording method of the present invention may be roll-like or sheet-like.

Incidentally, the wettability of the water-based inkjet ink of the present invention is improved, the image quality and the drying property are improved, and since the printed material surface is uniform, the scratch resistance and the adhesiveness can also be improved. It is also preferable to apply a surface modification method such as corona treatment or plasma treatment to the permeable substrate or the hardly permeable substrate.

<Coating process>
The printed surface of the printed matter produced using the ink set of the present invention may be coated, if necessary. Specific examples of the coating treatment include coating/printing of a coating composition, dry laminating method, solventless laminating method, laminating processing by extrusion laminating method, and the like, and either may be selected. You may combine both.

When the printed material is coated by coating/printing the coating composition, the coating/printing method includes a method of printing without contact with a recording medium, such as inkjet printing, and a recording medium. On the other hand, either of the methods in which the coating composition is brought into contact with and printed is used. Further, when the method of printing the coating composition in a non-contact manner with respect to the recording medium is selected, the coating composition contains a colorant component substantially excluding the pigment from the aqueous inkjet ink of the present invention. It is preferable to use a clear ink.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following description, “part” and “%” are respectively “part by mass” and “mass %” unless otherwise specified.
Is represented.

<Production Example of Pigment Dispersion Resin 1>
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, butanol 93.4
Parts were charged and purged with nitrogen gas. The inside of the reaction vessel was heated to 110° C., and a mixture of 30 parts of acrylic acid as a polymerizable monomer, 35 parts of styrene, 35 parts of lauryl methacrylate, and 6 parts of V-601 (manufactured by Wako Pure Chemical Industries) as a polymerization initiator. The mixture was added dropwise over 2 hours to carry out a polymerization reaction. After completion of dropping, the mixture was reacted at 110° C. for 3 hours, and then 0.6 part of V-601 was added, and further 11
The reaction was continued at 0°C for 1 hour. Then, the reaction system was cooled to room temperature, 39 parts of dimethylaminoethanol was added for neutralization, and then 100 parts of water was added. Then, add 1 to the mixed solution.
After heating to 00° C. or higher to distill off butanol, water was used to adjust the solid content to 30% to obtain an aqueous solution (solid content 30%) of Pigment Dispersion Resin 1. The weight average molecular weight of Pigment Dispersion Resin 1 measured by the method described above was 16,000, and the acid value was 230.

<Production Example of Pigment Dispersion Resin 2>
A reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer was charged with 95 parts of methyl ethyl ketone and replaced with nitrogen gas. The inside of the reaction vessel is heated to 80° C., and 70 parts of styrene as a polymerizable monomer, 5 parts of acrylic acid, 10 parts of methyl methacrylate, 15 parts of polypropylene glycol methacrylate (Blenmer PP-500 manufactured by NOF CORPORATION), and polymerization start A mixture of 3.5 parts of V-65 (manufactured by Wako Pure Chemical Industries, Ltd.) as an agent was added dropwise over 3 hours to carry out a polymerization reaction. After completion of dropping, the mixture was reacted at 80° C. for 1 hour, 0.7 part of V-65 was added, and the reaction was further continued at 80° C. for 4 hours. After that, 25 parts of methyl ethyl ketone was added, the reaction system was cooled to room temperature, and then the solid content was adjusted to 30% by using methyl ethyl ketone.
A methyl ethyl ketone solution (solid content 30%) of Pigment Dispersion Resin 2 was obtained. The weight average molecular weight of Pigment Dispersion Resin 2 measured by the method described above was 26,000, and the acid value was 30.

<Production Example of Pigment Dispersion Resin 3>
A reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer was charged with 100 parts of diethylene glycol and replaced with nitrogen gas. The inside of the reaction vessel was heated to 110° C., 20 parts of acrylic acid as a polymerizable monomer, 60 parts of benzyl methacrylate, 20 parts of methoxypolyethylene glycol methacrylate (Blenmer PME-1000 manufactured by NOF CORPORATION), and perbutyl as a polymerization initiator. A mixture of 5 parts of O (manufactured by NOF CORPORATION) was added dropwise over 3 hours to carry out a polymerization reaction. After completion of the dropwise addition, the mixture was reacted at 110° C. for 1 hour, cooled to room temperature, and adjusted to have a solid content of 30% by adding diethylene glycol. 30%). Incidentally, measured by the method described above,
The pigment-dispersed resin 3 had a weight average molecular weight of 13,000 and an acid value of 155.

<Production Example of Dispersion Aid 1>
According to the method described in paragraph Nos. 0180 to 0181 of JP-A-2017-21091, Dispersion Aid 1 which is a benzimidazolone dye derivative was obtained.

<Production Example of Red Pigment Dispersion Liquid 1>
In a mixing container equipped with a stirrer, Clariant NOVOPERM CARMINE H
20 parts of F4C (CI Pigment Red 185), 20 parts of an aqueous solution of the pigment dispersion resin 1 (solid content: 30%), and 60 parts of water were sequentially added, and then premixing was performed. After that, main dispersion was performed using a dyno mill having a volume of 0.6 L, which was filled with 1800 g of zirconia beads having a diameter of 0.5 mm, to obtain a red pigment dispersion liquid 1 (pigment concentration 20%).

<Production Example of Red Pigment Dispersion Liquid 2>
In a mixing container equipped with a stirrer, Clariant NOVOPERM CARMINE H
20 parts of F4C (CI Pigment Red 185), 20 parts of an aqueous solution of the pigment dispersion resin 1 (solid content: 30%), 0.8 parts of the dispersion aid 1 produced above, and 59. After 2 parts and 1 part were sequentially added, premixing was performed. After that, a main dispersion was performed using a dyno mill having a volume of 0.6 L, which was filled with 1800 g of zirconia beads having a diameter of 0.5 mm, to obtain a red pigment dispersion liquid 2 (pigment concentration 20%).

<Production Example of Red Pigment Dispersion Liquid 3>
In a mixing container equipped with a stirrer, a solution of pigment dispersion resin 2 in methyl ethyl ketone (solid content 30%
) After adding 20 parts and 8 parts of methyl ethyl ketone, while stirring, 50 parts of water and 0.3 part of dimethylaminoethanol were further added and stirred for 30 minutes. Next, NOVOPERM CARMINE HF4C (CI Pigment Red 18 manufactured by Clariant Co., Ltd.
20 parts of 5) was added and premixing was performed. Then, the main dispersion was performed using a Dyno mill having a volume of 0.6 L filled with 1800 g of zirconia beads having a diameter of 0.5 mm. Then
The obtained dispersion was taken out, 15 parts of water was added, and then methyl ethyl ketone was distilled off under reduced pressure using an evaporator. Then, the solid content concentration was adjusted to 26% to obtain a red pigment dispersion liquid 3 (pigment concentration 20%).

<Production Example of Red Pigment Dispersion Liquid 4>
25 parts of NOVOPERM CARMINE HF4C (CI Pigment Red 185) manufactured by Clariant, 125 parts of sodium chloride, and a diethylene glycol solution of Pigment Dispersion Resin 3 29. Parts and 4.9 parts of diethylene glycol were put into a stainless steel kneader and then kneaded at 80° C. for 3 hours. This mixture was placed in a mixing vessel equipped with a stirrer, to which 716 parts of water had been added in advance, and then the mixture was stirred for 1 hour while heating to about 40° C. to obtain a slurry mixture. After that, sodium chloride and diethylene glycol are removed by repeating filtration and washing with water, and further, a part of water is distilled off under reduced pressure, and water is added as necessary so that the solid content concentration becomes 27%. By adjusting, a red pigment dispersion liquid 5 (pigment concentration 20%) was obtained.

<Production Example of Red Pigment Dispersion Liquid 5>
Clariant NOVOPERM CARMINE HF4C (CI Pigment Red 185) 25 parts, sodium chloride 125 parts, Toyo Adre's Ceramer 1608
(Olefin maleic acid resin) 8.8 parts and diethylene glycol 15.2 parts were charged into a stainless steel kneader and then kneaded at 80° C. for 3 hours. This mixture
After adding 726 parts of water in advance into a mixing container equipped with a stirrer, about 40°C
The mixture was stirred for 1 hour while heating to give a slurry mixture. After that, sodium chloride and diethylene glycol are removed by repeating filtration and washing with water, and further, part of the water is distilled off under reduced pressure, and water is added as necessary so that the solid content concentration becomes 27%. By adjusting, a red pigment dispersion liquid 5 (pigment concentration 20%) was obtained.

<Production Example of Magenta Pigment Dispersion Liquids 1-2, Violet Pigment Dispersion Liquid 1,>
Magenta Pigment Dispersions 1 and 2 and Violet Pigment Dispersion 1 (both having a pigment concentration of 20%) were obtained in the same manner as in Red Pigment Dispersion 1 except that the pigments shown below were used.
-Magenta pigment dispersion 1: Ink Jet Magenta E-S
(Cl. CI Pigment Red 122)
-Magenta pigment dispersion 2: Cinquasia Magenta K 4535
(BASF CI Pigment Red 202)
・Violet pigment dispersion 1: Cromophthal Violet L 5805
(CI Pigment Violet 23 manufactured by BASF)

<Production example of binder resins 1 to 8 (water-soluble acrylic resin, water-soluble styrene acrylic resin)>
Composition of mixture dropped into butanol (type and amount of polymerizable monomer, and amount of V-601), amount of V-601 added after reacting at 110° C. for 3 hours, and used for neutralization Pigment Dispersion Resin 1 except that the amount of dimethylaminoethanol prepared was changed as shown in Table 1.
By the same operation as described above, an aqueous solution (solid content: 30%) of binder resins 1 to 8, which is a water-soluble acrylic resin or a water-soluble styrene acrylic resin, was obtained.

Table 1 also shows the acid value, glass transition temperature, and weight average molecular weight of the binder resins 1 to 8. The abbreviations of the polymerizable monomers listed in Table 1 are as follows.
-St: Styrene-MAA: Methacrylic acid-MMA: Methyl methacrylate-BA: Butyl acrylate-STMA: Stearyl methacrylate

<Production Example of Binder Resins 9 to 11 (Styrene Acrylic Resin Fine Particles)>
40 parts of water and 0.2 parts of Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a surfactant were charged into a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser and a stirrer to prepare an aqueous solution of the surfactant. Created. In another mixing container, 69 parts of butyl acrylate as a polymerizable monomer, 30 parts of styrene, 1 part of methacrylic acid, and 1.8 parts of Aqualon KH-10 as a surfactant.
Parts and 51.2 parts of water were added and mixed well to prepare an emulsion precursor.

1.5 parts of the prepared emulsion precursor was added to a reaction vessel containing a surfactant aqueous solution and mixed well. Then, the inside of the reaction vessel was heated to 60° C., and after substituting with nitrogen gas, 1 part of a 5% aqueous solution of potassium persulfate and 0.2 part of a 1% aqueous solution of anhydrous sodium bisulfite were added to the reaction vessel. Was maintained at 60° C., the polymerization reaction was started. After reacting at 60° C. for 5 minutes, the remainder (151.5 parts) of the emulsion precursor, 9 parts of a 5% aqueous solution of potassium persulfate, and 1.8 parts of a 1% aqueous solution of anhydrous sodium bisulfite were added to 1. Dripping over 5 hours,
After that, the reaction was continued for another 2 hours. Then, after cooling the reaction system to 30° C., diethylaminoethanol was added to adjust the pH of the mixed solution to 8.5, and the solid content was adjusted to 30 with water.
% To obtain an aqueous dispersion of the binder resin 9 (solid content 30%), which is fine styrene methacrylic resin particles.

Further, except that the polymerizable monomer was changed as shown in Table 2, the same operation as that for the binder resin 9 was performed, and an aqueous dispersion of the binder resins 10 to 11 (styrene content 30%, solid content: 30%) was obtained. ) Got.

Table 2 also shows the acid values and glass transition temperatures of the binder resins 9 to 11. Moreover, among the abbreviations of the polymerizable monomers listed in Table 2, the abbreviations of the materials not listed in Table 1 are as follows.
-PME-400: methoxy polyethylene glycol methacrylate (Broiler PME-400 manufactured by NOF CORPORATION)

<Production Example of Binder Resins 12 (Styrene Acrylic Resin Fine Particles) to 13 (Acrylic Resin Fine Particles)>
In a reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer, 20 parts of toluene, 7.5 parts of methacrylic acid as a polymerizable monomer, 7.5 parts of methyl methacrylate, and 2,2′-as a polymerization initiator. 0.9 parts of azobisisobutyronitrile and 3.6 parts of 2-(dodecylthiocarbonothioylthio)-isobutyric acid were charged and replaced with nitrogen gas. 75 in the reaction vessel
A copolymer (A block) composed of methacrylic acid and methyl methacrylate was obtained by heating at 0° C. and performing a polymerization reaction for 3 hours.

After the completion of the above polymerization reaction, the reaction system was cooled to room temperature, and then 60 parts of toluene and 15 parts of methyl methacrylate, 10 parts of styrene, 45 parts of butyl acrylate and 45 parts of lauryl methacrylate as a polymerizable monomer were placed in a reaction vessel. Parts were charged and replaced with nitrogen gas. Then, by heating the inside of the reaction vessel to 75° C. and performing a polymerization reaction for 3 hours, A− in which a copolymer (B block) composed of methyl methacrylate, styrene, butyl acrylate, and lauryl methacrylate was added to the A block. A B block polymer (binder resin 12) was obtained.
Then, after cooling the reaction system to room temperature, add 9 mL of dimethylaminoethanol to the reaction vessel.
． After neutralizing by adding 3 parts, 200 parts of water was added. Then, the mixed solution is heated to distill off toluene, and then the solid content is adjusted to 30% with water to obtain an aqueous dispersion of the binder resin 12, which is styrene (meth)acrylic resin fine particles. (Solid content 30%) was obtained.

Further, an aqueous dispersion (solid content: 30%) of the binder resin 13, which is acrylic resin fine particles, was obtained by the same operation as that for the binder resin 12 except that the polymerizable monomer was changed as shown in Table 3. It was

In addition, in Table 3, the acid value, the glass transition temperature, and the weight average molecular weight of the binder resins 12 to 12 are also shown. Further, among the abbreviations of the polymerizable monomers listed in Table 3, the abbreviations of the materials not listed in Tables 1 and 2 are as follows.
・LMA: Lauryl methacrylate

<Production Example of Binder Resins 14 to 16 (Water-Soluble Urethane Resin)>
In a reaction vessel equipped with a gas inlet tube, a thermometer, a condenser, and a stirrer, 43.5 parts of polypropylene glycol (molecular weight 1,000) as a polymerizable monomer, 44.5 parts of isophorone diisocyanate, and dibutyltin dilaurate. After 007 parts was charged and the atmosphere was replaced with nitrogen gas, the inside of the reaction vessel was heated to 100° C. and a polymerization reaction was carried out for 5 hours. After cooling the reaction system to about 60° C., 150 parts of methyl ethyl ketone, 9.0 parts of dimethylolpropionic acid, and 3 parts of neopentyl glycol were added, and after heating the inside of the reaction vessel to 80° C., a polymerization reaction was performed. It was Then, after cooling the reaction system to room temperature, 20 parts of methanol was added to stop the reaction. Next, water was added, and an aqueous potassium hydroxide solution was further added with stirring to neutralize. Then, the mixed solution is heated under reduced pressure to distill off methyl ethyl ketone and unreacted methanol, and the solid content is adjusted to 10% by using water to obtain a binder resin which is a urethane water-soluble resin. An aqueous solution of 14 (solid content 10%) was obtained.
In addition, an aqueous dispersion of binder resins 15 to 16 (a water-soluble urethane resin) was prepared by the same operation as that of the binder resin 14 except that the polymerizable monomer was changed as shown in Table 4.
(Solid content 10%) was obtained.

In addition, Table 4 also shows the acid values and weight average molecular weights of the binder resins 14 to 16. Also,
Abbreviations of the polymerizable monomers listed in Table 4 are as follows.
・PPG1000: polypropylene glycol (molecular weight 1,000)
・PTMG2000: polytetramethylene ether glycol (molecular weight 2,000)

-IPDI: isophorone diisocyanate-DMPA: dimethylol propionic acid-NPG: neopentyl glycol

<Production Example of Binder Resins 17 to 18 (Urethane Resin Fine Particles)>
In a reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer, 150 parts of methyl ethyl ketone, and polypropylene glycol (molecular weight 2,000) as a polymerizable monomer 3
4.3 parts, isophorone diisocyanate 22.7 parts, hexamethylene diisocyanate 1
After 7.2 parts and 23.9 parts of dimethylolpropionic acid were charged and purged with nitrogen gas, the inside of the reaction vessel was heated to 80° C. to carry out a polymerization reaction for 6 hours. Then, 1.9 parts of trimethylolpropane was further added, and the reaction was continued at 80°C. Then, the reaction system was cooled to room temperature, water was added, and an aqueous potassium hydroxide solution was further added with stirring to neutralize. Then, the mixed solution is heated under reduced pressure to distill off the methyl ethyl ketone, and then the solid content is adjusted to 20 with water.
% To obtain an aqueous dispersion of binder resin 17 (solid content 20%), which is urethane resin fine particles.
Further, an aqueous dispersion (solid content 10%) of the binder resin 18, which is urethane resin fine particles, was obtained by the same operation as the binder resin 17 except that the polymerizable monomer was changed as shown in Table 5. It was

In addition, Table 5 also shows the acid values of the binder resins 17 to 18. Among the abbreviations of the polymerizable monomers listed in Table 5, the abbreviations of the materials not listed in Table 4 are as follows.
・PPG2000: polypropylene glycol (molecular weight 2,000)
PC(HD) 2000: Polycarbonate diol (molecular weight 2,000) having 1,6-hexanediol as the main skeleton
・HDI: hexamethylene diisocyanate ・TMP: trimethylolpropane

<Binder resin 19 (urethane/acrylic composite resin fine particles), 20 to 21 (olefin resin fine particles)>
In the ink production examples described below, in addition to the binder resins 1 to 18, commercially available urethane/acrylic composite resin particles described below and olefin resin particles described below were used as the binder resins 19 to 21.
Binder resin 19: Juliano W600 (urethane/acrylic composite resin fine particles manufactured by Arakawa Chemical Industry Co., Ltd., solid content 35% (containing 5% isopropyl alcohol), acid value 20
mgKOH/g, glass transition temperature -55°C)
Binder resin 20: Aurolen AE-301 (manufactured by Nippon Paper Industries Co., solid content 30%,
Acid value 25mgKOH/g, melting point 70°C)
Binder resin 21: ZE-1224 (manufactured by Hoshiko PMC, solid content 30%, acid value 50
(mgKOH/g, melting point 70°C)

<Production Example of Aqueous Inkjet Inks 1-84>
The materials described below were sequentially added to the mixing container while stirring with a disper, and stirred until sufficiently uniform. Then, filtration was performed with a membrane filter having a pore size of 1 μm to obtain an aqueous inkjet ink 1:
Red pigment dispersion 1 (pigment concentration 20%) 7.5 parts Binder resin 1 aqueous solution (solid content 30%) 16.7 parts 1,2-propanediol 15 parts Surfynol 420 1 part Proxel GXL 0.05 part ・Ion-exchanged water 59.75 part

Further, aqueous inkjet inks 2 to 84 were obtained in the same manner as in the aqueous inkjet ink 1 except that the materials shown in Table 6 below were used.

The materials described in Table 6 are as follows (water-soluble organic solvent)
・IPA: Isopropyl alcohol (boiling point: 83°C)
・MFG: Propylene glycol monomethyl ether (boiling point: 120° C.)
・1,2-PD: 1,2-propanediol (boiling point: 188°C)
・1,2-BD: 1,2-butanediol (boiling point: 192°C)
・1,2-HD: 1,2-hexanediol (boiling point: 223°C)
・IPDG: Diethylene glycol monoisopropyl ether (boiling point: 207° C.)
DMPA: N,N-dimethyl-β-methoxypropionamide (boiling point: 215° C.)
・DMTG: Triethylene glycol dimethyl ether (boiling point: 216°C)
・BDG: diethylene glycol monobutyl ether (boiling point: 231° C.)
・DEG: diethylene glycol (boiling point: 244°C)
-2-PY: 2-pyrrolidone (boiling point: 245°C)
・GY: glycerin (boiling point: 290°C)
(Surfactant)
・S. 104: Surfynol 104 (acetylene diol type surfactant manufactured by Nisshin Chemical Industry Co., Ltd., HLB value: 3.0)
・S. 440: Surfynol 420 (acetylene diol-based surfactant manufactured by Nisshin Chemical Industry Co., Ltd., HLB value: 4.0)
・S. 465: Surfynol 465 (acetylene diol-based surfactant manufactured by Nisshin Chemical Industry Co., Ltd., HLB value: 13.2)
-TW280: TEGO Wet 280 (Siloxane-based surfactant manufactured by Evonik, HLB value: 3.5)
-TG432: TEGO Glide 432 (Siloxane-based surfactant manufactured by Evonik, HLB value: 7.5)
BYK347: BYK-347 (Siloxane-based surfactant manufactured by BYK Chemie, HL
B value: 8.6)
-TG440: TEGO Glide 440 (Siloxane-based surfactant manufactured by Evonik, HLB value: 13.5)
S-202: Nonion S-202 (polyoxyalkylene-based surfactant manufactured by NOF CORPORATION,
In the general formula (1), R is a cetyl group, m is 10, a compound in which n is 0, H
LB value: 4.9)
P-210: Nonion P-210 (polyoxyalkylene-based surfactant manufactured by NOF CORPORATION,
In the above general formula (1), R is a stearyl group, m is 2, and n is a compound,
HLB value: 12.9)
-E750: Emalex 750 (a polyoxyalkylene surfactant manufactured by Nippon Emulsion Co., Ltd., a compound in which R is a lauryl group, m is 50, and n is 0 in the general formula (1), HLB value: 15. 6)
(PH adjuster)
・28% NH ₃ : 28% ammonia water (pKa value of ammonia: 9.3)
DMAE: dimethylaminoethanol (pKa value: 9.9, boiling point: 133°C)
CHA: cyclohexylamine (pKa value: 10.6, boiling point: 134°C)
(Other)
Proxel GXL: 1,2-benzisothiazole-3-one solution (preservative) manufactured by Arch Chemicals

[Examples 1 to 77 (inkjet inks 1 to 77), Comparative examples 1 to 7 (inkjet inks 78 to 84)]
The following evaluations 1 to 5 were carried out on the water-based inkjet inks 1 to 84 produced above. The evaluation results are shown in Table 7.

<Evaluation 1: Evaluation of dispersion stability>
The average secondary particle diameter (D50) of the water-based inkjet inks 1 to 84 produced above was measured at 25° C. using Microtrac UPAEX-150 manufactured by Microtrac Bell. The ink was stored in a thermostat at 70° C., accelerated for a predetermined period of time, and then D50 was measured again at 25° C. to confirm the change before and after the lapse of time to evaluate the dispersion stability. The evaluation criteria are as follows, and the evaluation criteria values 2 to 3 were set as the practicable area.
3: The rate of change in viscosity after storage for 2 weeks was less than ±5% 2: The rate of change in viscosity after storage for 1 week was less than ±5%, but the rate of change in viscosity after storage for 2 weeks was ±5% The viscosity change rate after 1:1 storage was ±5% or more.

<Evaluation 2: Evaluation of ejection stability (standby ejection property)>
The inkjet head KJ4B-QA (manufactured by Kyocera Corp., design resolution 600 dpi) is installed on the upper part of a conveyor that can convey a recording medium, and the water-based inkjet ink 1 produced above
~ 84 each. After a nozzle check pattern was printed and it was confirmed that there was no nozzle omission, the nozzle was allowed to stand by for a predetermined time in an environment of 25°C. After that, the nozzle check pattern was printed again and the number of missing nozzles was counted to evaluate the ejection stability (standby ejection property). The evaluation criteria are as follows, and the evaluation criteria values 2 to 4 were set as the practicable area.
No nozzle omission even after waiting for 4:3 hours 3: No nozzle omission even after waiting for 2 hours, but no nozzle omission after waiting for 3 hours There was no nozzle omission even after waiting for 2:1 hours, but after waiting for 2 hours, 1 or more nozzle omission occurred, waiting for 1:1 hour. After that, one or more nozzles were missing.

<Evaluation 3: Evaluation of dryness>
The inkjet printing apparatus used in Evaluation 2 was filled with each of the aqueous inkjet inks 1 to 84 produced above, and then, with a drop volume of 12 pL, OPU-1 (biaxially stretched polypropylene film, thickness 20 μm) manufactured by Mitsui Chemicals Tohcello, Inc. Solid image on top (printing rate 1
(00%) was printed, and the printed matter was placed in a 50° C. air oven within 10 seconds. Then, the printed matter was taken out at predetermined time intervals, and the surface was rubbed with a finger to visually observe whether or not the ink could be taken off, thereby evaluating the drying property. The evaluation criteria are as follows, and the evaluation criteria values 2 to 4 were set as the practicable area.
4: Even if the printed material was rubbed with the finger after the drying time of 30 seconds, the ink on the printed surface could not be removed. 3: When the printed material was rubbed with the finger after the drying time of 30 seconds, the ink on the printed surface was removed, but after 45 seconds, the ink was rubbed. However, the ink on the printed surface could not be removed 2: When the printed material was rubbed with a finger after 45 seconds of drying time, the ink on the printed surface was removed, but even after rubbing 1 minute, the ink on the printed surface was not removed 1: Drying time It did not dry even after 1 minute, and the ink on the printed surface was removed by rubbing the printed material with a finger

<Evaluation 4: Evaluation of scratch resistance>
The inkjet printing apparatus used in Evaluation 2 was filled with each of the water-based inkjet inks 1 to 84 produced above, and then with a drop volume of 12 pL, OK top coat manufactured by Oji Paper Co., Ltd. + (coated paper, basis weight 104.7 g/m 2). ² ) Solid image on top (printing rate 100%)
Was printed, and the printed matter was put into a 70° C. air oven within 10 seconds. After being dried for 1 minute, the printed matter was taken out of the oven, rubbed a predetermined number of times with a test white cotton cloth (Kanakin No. 3) while rubbing a predetermined number of times, and visually observing whether or not the ink could be removed to evaluate scratch resistance. .. The evaluation criteria are as follows, and the evaluation criteria values 2 to 3 were used as the practicable area. 3: No scratches on the printing surface or ink peeling was observed even after rubbing 20 times. The surface was not scratched or the ink was not peeled, but the surface was scratched or peeled off when the ink was rubbed 20 times. The scratched surface or the ink was peeled off after rubbing 1:10 times. Was

<Evaluation 5: Evaluation of image quality (coated paper)>
The inkjet printing apparatus used in Evaluation 2 was filled with each of the water-based inkjet inks 1 to 84 produced above, and then with a drop volume of 12 pL, OK top coat manufactured by Oji Paper Co., Ltd. + (coated paper, basis weight 104.7 g/m 2). ² ) A gradation patch image having a printing rate of 10% to 80% and a printing rate changed every 10% was printed thereon, and the printed matter was put into a 70° C. air oven within 10 seconds. After drying for 1 minute, the printed matter was taken out of the oven, and the presence or absence of uneven density was visually observed to evaluate the image quality of the coated paper. The evaluation criteria were as follows, and the evaluation criteria values 2 to 4 were used as the practicable area 4: No density unevenness was observed at any printing rate 3: No density unevenness was observed at a printing rate of 70% or less 2: No uneven density was observed at a printing rate of 60% or less. 1: Uneven density was apparent at a printing rate of 60%.

As a result of the evaluation, a binder resin having an acid value of 1 to 80 mgKOH/g, a surfactant,
A water-soluble organic solvent is included, and the content of the water-soluble organic solvent having a boiling point of 240° C. or higher is 8
It was confirmed that the water-based inkjet inks 1 to 77 having a mass% or less have practical quality in all of dispersion stability, ejection stability, drying property, scratch resistance of printed matter, and image quality. Was done.

In addition, the water-based inkjet ink 35 evaluated by changing the type of the surfactant used.
-43, 48-52, two or more kinds of siloxane-based surfactants are used together as the surfactant, and one of the two or more kinds of surfactants has an HLB value of 0 to 5, Water-based inkjet inks 50 and 52 having another HLB value of 6 to 18 have ejection stability of 4 levels and image quality on coated paper of 3 levels, and the case where the surfactant is used alone. By comparison, it was confirmed that it was particularly excellent.

The water-based inkjet inks 70 to 74 are examples in which a nitrogen-containing compound is used as a water-soluble organic solvent or a pH adjuster. As a result of the evaluation, it was found that the dispersion stability and the ejection stability of the aqueous inkjet inks 72 to 74 were deteriorated as compared with the aqueous inkjet inks 61 that did not use the basic compound. In these aqueous inkjet inks, N,N-dimethyl-β-methoxypropionamide which is a chain amide solvent, 2-pyrrolidone which is a cyclic amide solvent, or cyclohexylamine having a pKa value of 10 or more is used. Although the detailed reason is unknown, it was confirmed that the effects of the present invention can be suitably exhibited by reducing the blending amount of these nitrogen-containing compounds.

On the other hand, the aqueous inkjet ink 79 (Comparative Example 2) using a binder resin having an acid value of 0 mgKOH/g is inferior in ejection stability and has an acid value of 80 mgK.
Aqueous inkjet ink 78, 80 (using a binder resin larger than OH/g)
In Comparative Examples 1 and 3), it was confirmed that the dispersion stability was poor. If the acid value of the binder resin is too small, even if a surfactant is used in combination, it is not possible to prevent clogging of the nozzle surface of the inkjet head. Conversely, if the acid value is too large, the acid groups in the binder resin are But C.I. I. It is considered that the pigment red 185 and the pigment-dispersed resin interact with each other to destroy the dispersed state.

On the other hand, when the binder resin is not used like the water-based inkjet ink 81 (Comparative Example 4), the dispersion stability and the ejection stability are improved, but the printed matter is significantly inferior in scratch resistance and image quality. turn into. When no surfactant was used as in the case of the water-based inkjet ink 82 (Comparative Example 5), it was not possible to suppress the film formation of the binder resin (a-1) in the ink, resulting in poor ejection stability. It is considered to become ink. Furthermore, the boiling point is 2
With the aqueous inkjet inks 83 and 84 (Comparative Examples 6 and 7) in which the content of diethylene glycol or glycerin was 40% or higher and the content of diethylene glycol or glycerin was 10% by mass, deterioration of drying property and scratch resistance was confirmed. It is considered that the high boiling point solvent remained in the printed matter for a long period of time after printing, leading to deterioration of the drying property and the scratch resistance.

[Examples 78 to 150, Comparative Examples 8 to 11]
As described above, when used for a non-permeable substrate such as a plastic substrate, it is preferable to include the binder resin (a-1) having a glass transition temperature of 45° C. or lower. Therefore, among the water-based inks containing a binder resin satisfying the above conditions (however, 81 is a comparative example, no binder resin is contained), water-based inkjet inks 1 to 6 and 1
With respect to 1 to 77 and 81 to 84, the following evaluations 6 to 7 were also performed to evaluate the image quality and adhesion to the non-permeable substrate. The results are as shown in Table 8.

<Evaluation 6: Evaluation of image quality (film)>
The image quality of the film was evaluated by the same method and evaluation criteria as in Evaluation 5 above except that OPU-1 (biaxially oriented polypropylene film, thickness 20 μm) manufactured by Mitsui Chemicals Tohcello was used as the recording medium. ..

<Evaluation 7: Evaluation of adhesion>
The ink jet printing apparatus used in Evaluation 2 was filled with the above-prepared water-based ink jet inks 1 to 6, 11 to 77, and 81 to 84, and then a drop volume of 12 pL
And OPU-1 manufactured by Mitsui Chemicals Tohcello Co. (biaxially oriented polypropylene film, thickness 20 μm)
A solid image (printing rate 100%) was printed on the top, and the printed matter was put into a 70° C. air oven within 10 seconds. After drying for 1 minute, the printed matter was taken out of the oven, and cellophane tape (width: 18 mm) manufactured by Nichiban Co. was firmly attached to the surface of the printed matter with the pad of the finger. Then, the adhesiveness was evaluated by holding the tip of the cellophane tape and momentarily pulling it off while keeping the angle of 45 degrees, and then visually observing the surface of the printed matter. The evaluation criteria are as follows, and the evaluation criteria values 2 to 4 were set as the practicable area.
4: The ratio of the peeled area to the area where the cellophane tape was applied was less than 10% 3: The ratio of the peeled area to the area where the cellophane tape was applied was 10% or more 20
% Was less than 2: The ratio of the peeled area to the area where the cellophane tape was stuck was 20% or more and 30
% Was less than 1: %, the peeled area from the contact surface of the cellophane tape was 30% or more

As a result of the evaluation, it was confirmed that each of the water-based inkjet inks 1 to 6 and 11 to 77 (Examples 78 to 150) was excellent in image quality and adhesion to the polypropylene film. Among them, among the water-based inkjet inks 2, 11 to 23 evaluated by changing the type of the binder resin (A), the water-based inkjet inks 17 to 17 using the urethane resin, the urethane-acrylic composite resin, or the olefin resin. In No. 23, the evaluation standard value of the image quality with respect to the film was 3, and the evaluation standard value of the adhesiveness was 3 to 4, and it was confirmed that the film had particularly excellent quality as compared with the ink using other resins.

On the other hand, it was confirmed that the water-based inkjet inks 81 to 84 (Comparative Examples 8 to 11) had a practically problematic level of 1 for the image quality evaluation standard value for the film. The above results indicate that the water-based inkjet ink having the constitution of the present invention, in particular, the water-based inkjet ink containing the binder resin selected from the above is excellent in image quality and adhesion to a non-permeable substrate such as a polypropylene film. Is shown.

Claims (8)

An aqueous inkjet ink containing a colorant, a binder resin (A), a surfactant, and a water-soluble organic solvent,
The colorant is C.I. I. Pigment Red 185,
The binder resin (A) has an acid value of 1 to 80 mgKOH/g (
a-1) included,
A water-based inkjet ink, wherein the content of the water-soluble organic solvent having a boiling point of 240° C. or higher under 1 atmosphere is 8% by mass or less based on the total amount of the inkjet ink. The aqueous solution according to claim 1, wherein the binder resin (a-1) is at least one selected from the group consisting of an acrylic resin, a styrene acrylic resin, a urethane resin, a urethane-acrylic composite resin, and an olefin resin. Inkjet ink. The water-based inkjet ink according to claim 1, wherein the water-soluble organic solvent contains an alkanediol having 2 to 5 carbon atoms. The water-based inkjet ink according to claim 1, wherein the surfactant contains a surfactant having an HLB value of 0 to 5. The aqueous inkjet ink according to any one of claims 1 to 4, wherein the surfactant contains a surfactant having an HLB value of 6 to 18. The aqueous inkjet according to any one of claims 1 to 5, wherein the total amount of the chain amide-based solvent, the cyclic amide-based solvent, and the cyclic carbamate-based solvent is 3% by mass or less based on the total amount of the aqueous inkjet ink. ink. The total content of nitrogen-containing compounds having a pKa value at 25° C. of 2 or less, or 10 or more (however, a chain amide solvent, a cyclic amide solvent, and a cyclic carbamate solvent are excluded) is the ink jet The water-based inkjet ink according to claim 1, which is 1% by mass or less based on the total amount of the ink. A method for producing an inkjet printed material, comprising ejecting the aqueous inkjet ink according to any one of claims 1 to 7 from an inkjet head and applying the inkjet ink to a non-permeable substrate.