JP6661731B2 - Ink package and method for manufacturing the same - Google Patents

Description

  The present invention relates to an ink package in which a container is less deformed even during long-term storage.

  2. Description of the Related Art In recent years, a variety of small lots of printed materials has been increased, and inkjet printing, which is an on-demand print that can easily cope with small lots of various types, has attracted attention as an alternative to conventional printing such as offset printing. In addition, inkjet printing is simpler than conventional offset printing, and has advantages such as economy and energy saving.

Ink jet printing is a printing method in which fine droplets of ink discharged from a printer head land on a recording medium, and then penetrate and fix to form dots, and an image is formed by collecting a large number of dots. Ink jet printing inks are required to have various properties, such as physical properties such as image quality and weather resistance of printed matter, as well as ink jet suitability such as ejection stability from a printer head and intermittent ejection stability.
As such an ink for ink jet printing, an ink containing a colorant such as a pigment, a binder resin for improving fixability to a printing material, and a solvent is generally used.
Further, it is known that these ink components cause deterioration due to moisture absorption and the like, and precipitates and the like are generated in the ink.
For this reason, as a container used for storing and transporting the ink, a container made of a material having a predetermined film thickness and having a low water vapor transmission rate is used (for example, Patent Document 1).

International Publication No. 2009/101708

By the way, when an ink package filled with ink is stored in a container for a long time, there is a problem that the container is deformed.
Further, when a container filled with ink is used as an ink cartridge of a recording apparatus, problems such as a deformation of the container, which makes it impossible to attach to the recording apparatus, and a possibility that ink leaks from the container may occur. is there.

  The present invention has been made in view of the above-described problems, and has as its main object to provide an ink package in which the container is less deformed even during long-term storage.

  As a result of repeated studies to solve the above problems, long-term storage of ink containing a polyalkylene glycol alkyl ether-based solvent as a solvent and an acrylic resin or a vinyl chloride-vinyl acetate copolymer resin as a binder resin in a container. When the container has a high tendency to deform, furthermore, when the gas remaining in the cavity of the deformed container is investigated and the oxygen partial pressure is low, the specific solvent and the binder resin as described above are used. When the containing ink is stored for a long time, oxygen in the container is absorbed by these ink components, and as a result, the inside of the container is decompressed, and it is found that the container is deformed, thereby completing the present invention. .

  That is, the present invention is an ink package comprising a container, an inkjet ink and a gas sealed in the container, wherein the inkjet ink comprises a polyalkylene glycol alkyl ether-based solvent and an acrylic resin (A ) And a binder resin containing at least one of a copolymer (B) having a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II): Is less than 0.2 atm, the container has a change in appearance when the internal pressure in a closed state is 0.8 atm or more, and the oxygen partial pressure is Provided is an ink package characterized by having no change in appearance due to reduced pressure.

(In the general formulas (I) and (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 3 carbon atoms, and X represents Represents a halogen atom.)

  According to the present invention, by using a gas whose oxygen partial pressure is in the above-described range and a container whose appearance does not change within the range of reduced pressure of the oxygen partial pressure, the specific solvent and the binder resin are used. Even if the ink-jet ink containing ink-jet ink is sealed in a container whose appearance changes when the internal pressure of the ink-jet ink in a sealed state is 0.8 atm or more, the container can be deformed even during long-term storage. Can be reduced.

  In the present invention, the gas preferably contains an inert gas. This is because by replacing the oxygen present in the voids of the container with the inert gas, a gas having an oxygen partial pressure of less than 0.2 atm can easily obtain an ink package sealed in the container. .

  In the present invention, the content of the polyalkylene glycol alkyl ether-based solvent is preferably 50 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the inkjet ink. Even when the content of the solvent is within the above range and the oxygen in the gas is dissolved and the consumption of oxygen by the binder resin is easy to proceed, by using the gas and the container, the ink package Can be reduced in deformation of the container. Therefore, the effects of the present invention can be more effectively exhibited.

  In the present invention, the container is preferably an inner surface-coated metal container having a metal container and a resin layer for coating the inner surface of the metal container, or a resin container. This is because by using the above-described container, it is possible to easily form a container having a strength that does not change its appearance within the range of the oxygen partial pressure. In addition, the reason is that the container has a simple structure and can be easily reduced in cost.

  The present invention is a method of manufacturing the above-described ink package, wherein an ink filling step of filling the inkjet ink so as to provide a void in the container, and filling the container with an inert gas, and filling the inside of the container. Providing a method of manufacturing an ink package, comprising: a replacement step of filling the gas with an oxygen partial pressure of less than 0.2 atm.

According to the present invention, the partial pressure of oxygen of the gas can be easily reduced to less than 0.2 atm by having the above-described substitution step.
Therefore, even when the ink-jet ink containing the specific solvent and the binder resin is sealed in a container whose appearance changes when the internal pressure in the sealed state is 0.8 atm or more, deformation of the container The above-mentioned ink package having a small amount can be easily obtained.

In the present invention, it is preferable to have an inspection step of inspecting whether or not the oxygen partial pressure of the gas is less than 0.2 atm during or after the substitution step.
By having the inspection step, it is possible to confirm that the oxygen partial pressure of the gas is less than 0.2 atm, and it is possible to stably obtain an ink package having a gas oxygen partial pressure of less than 0.2 atm. Because.

  ADVANTAGE OF THE INVENTION This invention produces the effect that an ink package with little deformation | transformation of a container can be provided even during long-term storage.

FIG. 2 is a schematic sectional view illustrating an example of the ink package of the present invention. It is explanatory drawing explaining the volume of the container in this invention. It is a flowchart showing an example of the manufacturing method of the ink package of the present invention.

The present invention relates to an ink package and a method for manufacturing the same.
Hereinafter, the ink package and the method for manufacturing the ink package of the present invention will be described.

A. First, the ink package of the present invention will be described.
The ink package of the present invention comprises a container, an inkjet ink and a gas sealed in the container, wherein the inkjet ink comprises a polyalkylene glycol alkyl ether-based solvent and an acrylic resin (A ) And a binder resin containing at least one of a copolymer (B) having a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II): Is less than 0.2 atm, the container has a change in appearance when the internal pressure in a closed state is 0.8 atm or more, and the oxygen partial pressure is It is characterized in that the appearance does not change due to the reduced pressure.

(In the general formulas (I) and (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 3 carbon atoms, and X represents Represents a halogen atom.)

Such an ink package of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the ink package of the present invention. The ink package 10 of the present invention includes a container 1, an inkjet ink 2 and a gas 3 sealed in the container 1.
Here, the inkjet ink 2 contains a polyalkylene glycol alkyl ether-based solvent and a binder resin containing at least one of the acrylic resin (A) and the copolymer (B). The oxygen partial pressure of the gas is less than 0.2 atm. The container 1 has a change in appearance when the internal pressure in a closed state is 0.8 atm or more, and has no change in appearance due to the reduced pressure of the oxygen partial pressure.
Further, in this example, the container 1 is formed separately from the container 1 and has a lid 4 that seals the container 1. Further, the ink package 10 includes a seal member 5 disposed between the container 1 and the lid 4.

According to the present invention, by using a gas having an oxygen partial pressure within the above-described range and a container having no change in appearance within the range of the oxygen partial pressure, an inkjet including the specific solvent and the binder resin is used. Even if the ink is sealed in a container whose appearance changes when the internal pressure in the sealed state is 0.8 atm or more, even if the ink package is stored for a long time, the container is less deformed. It can be.
Here, the reason why the deformation of the container is caused as a result of the absorption of oxygen in the container when the specific solvent and the binder resin are included as the inkjet ink is not clear, but is presumed as follows.

That is, the polyalkylene glycol alkyl ether-based solvent has a relatively high solubility for oxygen, and thus can dissolve oxygen in the container. However, the solvent alone cannot dissolve all of the oxygen in the container. it is conceivable that.
However, in the acrylic resin (A) and the copolymer (B), a hydrocarbon portion is decomposed, and a generated radical reacts with oxygen to generate a carboxy group, and is dissolved in a solvent. Since oxygen can be consumed by undergoing oxidative degradation by oxygen, oxygen in the container is absorbed into the inkjet ink over time.
Therefore, when the gas filled in the container is the atmospheric pressure of 1 atm, the oxygen in the gas, that is, about 0.2 atm is consumed by the binder resin via the solvent, and as a result, The internal pressure of the container is reduced to a partial pressure, that is, 0.8 atm reduced by 0.2 atm.
For this reason, when a container having a change in appearance when the internal pressure in a sealed state is 0.8 atm or more is used, the container is deformed due to long-term storage of the ink package.
That is, the deformation of the container may be caused by a solvent capable of dissolving oxygen (hereinafter, sometimes simply referred to as an oxygen-soluble solvent) and a resin capable of consuming oxygen (hereinafter, simply referred to as an oxygen-consuming resin). This is the first occurrence of the combination of

On the other hand, according to the present invention, a gas having an oxygen partial pressure in the above-described range and a container having no change in appearance within the range of the oxygen partial pressure are used. By using a gas whose oxygen partial pressure in the void is adjusted to be lower than that of the atmosphere and a container whose appearance does not change even when all the oxygen contained in the adjusted gas is consumed, oxygen An inkjet ink containing the above-mentioned specific solvent which is a soluble solvent and the above-mentioned specific binder resin which is an oxygen-consuming resin is sealed in a container having a change in appearance when the internal pressure in the closed state is 0.8 atm or more. Even if it is performed, the deformation of the container can be reduced even when the ink package is stored for a long period of time.
Further, as a result, even when the ink package is stored for a long period of time, the shape stability of the container is excellent, so that the ink package can be stably attached as an ink cartridge of a recording apparatus. can do. In addition, the ink package can be made less likely to leak ink due to damage to the container.

Further, by using a container having a change in appearance when the internal pressure in a sealed state is 0.8 atm or more (hereinafter, may be referred to as a specific container), the internal pressure is 0.8 atm or less. The ink package can be easily stored and transported compared to the case where a container made of a hard material that does not deform even when the ink package is used.
For example, as the hard material, a high-strength metal or a hard material such as glass can be used, but the specific container can be lighter than the hard material container. In addition, the specific container has less quality deterioration of the ink due to a reaction with an ink component such as occurs when the hard material is the metal, and the container is cracked as compared with the container where the hard material is glass or the like. Such a problem is unlikely to occur.
It is also conceivable to use a resin material having a large thickness as the hard material. However, the specific container can be made smaller and lighter as compared with such a thick film container.
For this reason, by using the specific container, the ink package can be easily stored and transported.

The ink package of the present invention has a container, an inkjet ink and a gas.
Hereinafter, each configuration of the ink package of the present invention will be described in detail.

1. Container The container in the present invention seals the ink-jet ink and gas.
The container has a change in appearance when the internal pressure in a closed state is 0.8 atm or more, and has no change in appearance due to the reduced pressure of the oxygen partial pressure.
In other words, the above-mentioned container means that the maximum internal pressure that causes a change in appearance is 0.8 atm or more and less than the internal pressure after the pressure reduction by the oxygen partial pressure.

In the present invention, sealing the ink-jet ink and gas means that there is no leakage of the ink-jet ink and there is substantially no gas permeation.
Further, it can be confirmed that there is substantially no gas permeation by using a sealing strength test based on JIS Z 0238.
Sealing strength test, more specifically, after preparing a container, after sealing, using a tester, after applying a constant internal pressure by filling a gas so that the internal pressure is higher than the external pressure by 0.04 MPa, Those which have no pressure change for 30 seconds and can maintain 0.04 MPa can be regarded as having substantially no gas permeation.
As a tester, FKT-100-J manufactured by Sun Chemical Co., Ltd. can be used.

The maximum internal pressure that causes a change in appearance is the largest internal pressure that causes a change in appearance, that is, the internal pressure at which the difference between the internal and external pressures is minimized.
The method of measuring the maximum internal pressure is not particularly limited as long as the method can accurately measure the maximum internal pressure.
The measuring method is, for example, filling a container with 80% by volume of pure water in the container (filling ratio: 80%), and filling the space (20% by volume in the container) with nitrogen at 1 atm. After filling the container, the container is sealed, and then, after leaving the container inside at 25 ° C. for one week in a state where the internal pressure in the container is reduced by discharging nitrogen from the container, a change in appearance is confirmed. A method for confirming the internal pressure can be used.
In addition, the above measurement can be performed under the conditions of 25 ° C. and an external pressure of 1 atm.

Here, that there is a change in appearance means that a change in a concave portion or the like can be visually confirmed.
More specifically, the above-mentioned appearance change means that the atmosphere is sealed in a container at 25 ° C. so that the internal pressure becomes 1 atm, and the volume of the container measured when the internal / external pressure difference is 0 atm ( Hereinafter, the volume may be referred to as a reference volume.).
Further, “no change in appearance” means that a volume change of less than 8% by volume with respect to the reference volume is observed or no volume change is observed.
The method for measuring the volume is not particularly limited as long as it can accurately measure the volume. For example, a general volume measuring method such as a method of immersing the container in a water tank or the like with the container closed is used. Can be used. The change in appearance is measured in an environment of 25 ° C.
Further, the volume in the change in appearance refers to the volume surrounded by the outer surface of the container. The volume of the container does not include a lid or the like formed separately from the container. For example, the volume of the container of FIG. 1 described above is indicated by a bold broken line in FIG.

  In the present invention, the expression that the internal pressure in a sealed state is 0.8 atm or more means that the internal pressure of the container is 0.8 atm or more when the external pressure of the container is 1 atm under an environment of a temperature of 25 ° C. This means that the difference between the internal pressure and the external pressure is within 0.2 atm.

The internal pressure that causes a change in the appearance of the container, that is, the lower limit of the maximum internal pressure (hereinafter, sometimes simply referred to as the maximum strength) is 0.8 atm or more. That is, when the internal pressure is 0.8 atm or lower, the container naturally has a change in appearance.
Here, under atmospheric pressure (1 atm), the oxygen partial pressure in the atmosphere is usually 0.2 atm.
Therefore, when the maximum strength of the container is 0.8 atm or more, the gas sealed in the container is the atmosphere, and all the oxygen contained in the gas is dissolved in the ink and consumed by the binder resin. In addition, a container having a strength that causes a change in appearance can be used.
Thereby, when the gas sealed in the container is the atmosphere, all of the oxygen contained in the gas is consumed, and a container using a material which does not change appearance even when the internal pressure becomes 0.8 atm. For example, the use of a high-strength metal container such as a thick steel can and a hard material container such as a glass container, and the use of a thick resin container and the like can be eliminated, and the container size and mass can be reduced. It can be small.
The maximum strength may be at least 0.8 atm, preferably at least 0.82 atm, more preferably at least 0.85 atm, and especially at least 0.87 atm. Is preferred. When the maximum strength is within the above range, the thickness of the material constituting the container can be reduced, and the size and mass of the container can be reduced. For this reason, the ink package can be easily stored and transported.
In addition, 1 atm is atmospheric pressure, and means that it is 101325 Pa.

In the present invention, the expression that there is no change in appearance due to the reduced pressure of the oxygen partial pressure means that when all of the oxygen in the gas sealed in the container is dissolved in the ink or consumed by the binder resin, the appearance is changed to the container. It means that it has a strength that does not change.
The oxygen partial pressure refers to the oxygen partial pressure when the gas is at 1 atm. Therefore, when the internal pressure of the container is reduced from 1 atm to less than 1 atm by storing the ink package for a long period of time, the oxygen partial pressure is calculated by reducing the internal pressure by the reduced pressure of oxygen. It is determined assuming that there is. For example, when the internal pressure is reduced from 1 atm to 0.9 atm and the oxygen partial pressure of the container after the pressure reduction is 0.1 atm, the oxygen partial pressure when the internal pressure of the container is 1 atm is 0. It is assumed that the pressure is 2 atm.

The internal pressure that causes a change in the appearance of the container, that is, the upper limit of the maximum internal pressure (hereinafter, may be simply referred to as minimum strength) is the internal pressure after all the oxygen for the oxygen partial pressure has been consumed, that is, The internal pressure may be less than the internal pressure obtained by subtracting the oxygen partial pressure from 1 atm (hereinafter, may be simply referred to as the internal pressure after full consumption), but may be 0.03 atm or lower than the internal pressure after full consumption. Preferably, the pressure is not more than 0.05 atm lower internal pressure, particularly preferably not more than 0.07 atm lower pressure. When the minimum strength is in the above-described range, the appearance can be stably maintained by reducing the partial pressure of oxygen.
For example, when the oxygen partial pressure of the gas is 0.05 atm, the minimum strength of the container may be less than 0.95. Further, when the oxygen partial pressure of the gas is 0.05 atm and the minimum strength is 0.05 atm lower than the internal pressure after the total consumption, the container is set to a pressure lower than 0.95 atm which is the internal pressure after the total consumption. It means that it deforms in appearance at an internal pressure of 0.90 atm or less, which is 0.050 atm lower, and does not change its appearance at an internal pressure of more than 0.90 atm.

The container is a box-shaped container that does not change in appearance regardless of the amount of ink filled in the container.
Here, the fact that there is no change in appearance regardless of the amount of ink to be filled means that, for example, under conditions where a pressure of 1 atm is applied to the surface of the ink-jet ink, the ink-jet ink is 50% by volume and 90% by volume of the volume in the container. This means that there is no change in the appearance of the container even when the amount of ink is different, such as when the amount of ink is filled.
More specifically, such a container can be a container that does not change in appearance when the internal pressure in a sealed state is in the range of 0.97 atm to 1 atm.

The above-mentioned container is used for storing and transporting ink, and is not particularly limited as long as it has the above-described strength. A container formed of a single layer material formed using a single material Or a container formed of a plurality of layers of a plurality of stacked materials.
Such a container is preferably an inner surface coated metal container having a metal container and a resin layer for coating the inner surface of the metal container, or a resin container.
This is because the container having the above strength can be easily formed by using the container. Also, because the structure is simple, it is easy to reduce the cost.

  The metal material constituting the metal container is not particularly limited as long as it can form a container having the above strength. Examples thereof include steel, tinplate, iron, aluminum, tin-free steel, and stainless steel plate. Among them, in the present invention, steel, tin-free steel and the like can be preferably used. This is because the metal material exhibits sufficient strength with a relatively thin film thickness. In addition, the reason is that the container can easily have a low moisture permeability.

The thickness of the body portion of the metal material constituting the metal container is not particularly limited as long as the container having the above strength can be formed, but is, for example, in the range of 0.1 mm to 3.0 mm. It is preferably within the range of 0.2 mm to 2.0 mm, and more preferably within the range of 0.3 mm to 1.5 mm. This is because when the film thickness is within the above-described range, the above-described strength can be easily obtained.
In addition, the said film thickness refers to the film thickness of the thinnest part of the body part of a container.
In addition, the body is generally provided substantially perpendicular to the bottom of the container, and is a portion that holds the inkjet ink together with the bottom.
Specifically, it is the site indicated by A in FIG. 1 already described.

  The resin material constituting the resin layer is not particularly limited as long as it can form a container having the above strength. For example, epoxy, polyethylene (PE), polypropylene (PP), polyethylene terephthalate ( PET), vinyl chloride, polystyrene, acryl, polycarbonate and the like. Among them, in the present invention, polyethylene, polypropylene and the like can be preferably used. This is because the resin material has low reactivity with each component in the ink-jet ink and can make the container excellent in storage stability of the ink.

  The thickness of the resin layer is not particularly limited as long as a container having the above strength can be formed, and varies depending on the constituent material and the thickness of the metal container. It is preferably in the range of 0.01 mm to 1.0 mm, particularly preferably in the range of 0.02 mm to 0.5 mm, and particularly in the range of 0.05 mm to 0.1 mm. preferable. This is because when the film thickness is within the above-described range, the above-described strength can be easily obtained.

  The resin material constituting the resin container is not particularly limited as long as the container having the above strength can be formed, and for example, may be the same as the resin material constituting the resin layer. it can.

  The thickness of the body portion of the resin material constituting the resin container is not particularly limited as long as the container having the strength described above can be formed, and for example, is 0.2 mm to 3.0 mm. , And more preferably, within a range of 0.5 mm to 2.5 mm, and particularly preferably, within a range of 1.0 mm to 2.0 mm. This is because when the film thickness is within the above-described range, the above-described strength can be easily obtained.

  The shape of the container is not particularly limited as long as the container having the above strength can be formed, but may be a general container shape used for storing ink-jet ink. Specifically, the shape can be a cylindrical shape, a rectangular parallelepiped shape, or the like.

The inner volume of the container is not particularly limited as long as the container having the above strength can be formed, and varies depending on the use and the like, but is in the range of 0.1 L to 200.0 L. In particular, it is preferably in the range of 0.25 L to 20.0 L, particularly preferably in the range of 0.3 L to 5.0 L, and particularly preferably in the range of 0.5 L to 5.0 L. It is preferable to be within the range of 1.2 L. This is because the above-mentioned internal volume allows the ink package to be easily stored and transported.
The internal volume of the container refers to the internal volume measured when the container is closed with a pressure difference between the internal and external pressures of 0 atm.

2. Gas The gas in the present invention is sealed in the above-mentioned container.
The oxygen partial pressure of the above gas is less than 0.2 atm.

  As described above, under atmospheric pressure (1 atm), the partial pressure of oxygen in the atmosphere is usually 0.2 atm. Therefore, a gas having an oxygen partial pressure of less than 0.2 atm means that oxygen in the atmosphere is artificially replaced with a gas other than oxygen.

The oxygen partial pressure may be less than 0.2 atm, preferably 0.15 atm or less, more preferably 0.1 atm or less, particularly 0.05 atm or less. It is preferred that This is because when the oxygen partial pressure is within the above range, a change in the appearance of the container can be stably suppressed.
The lower limit of the oxygen partial pressure is preferably as low as possible, and is preferably 0 atm. For example, by using a gas heavier than the atmosphere, such as argon, and filling in a box filled with that gas, It can be 0 atm. From the viewpoint of easy replacement of oxygen in the gas, the pressure is preferably 0.03 atm or more.
The oxygen partial pressure refers to the oxygen partial pressure when the gas is at 1 atm. Specifically, the oxygen partial pressure can be the same as the content described in the section “1. Container”. .

  The internal pressure of the gas in the container is not particularly limited as long as the oxygen partial pressure is within the above range, but may be 1 atm immediately after the container is sealed.

The component contained in the gas is not particularly limited as long as the oxygen partial pressure can be reduced to less than 0.2 atm, but preferably contains an inert gas. This is because by replacing the oxygen present in the voids of the container with the inert gas, a gas having an oxygen partial pressure of less than 0.2 atm can easily obtain an ink package sealed in the container. .
The inert gas in the present invention is not particularly limited as long as it has lower absorptivity by the binder resin than oxygen.
Specific examples of the inert gas include rare gases such as argon, xenon, and krypton; nitrogen, carbon dioxide, and the like.
In the present invention, the inert gas is preferably argon or nitrogen, and more preferably nitrogen. This is because the use of the inert gas reduces the absorbability with the binder resin and can reduce the cost.
The gas in the present invention may contain one kind of inert gas, or may contain two or more kinds of inert gases.

  The ratio of the gas to the internal volume of the container is appropriately set according to the use of the ink package, and is, for example, in the range of 2% by volume to 20% by volume of the internal volume of the container. In particular, the content is preferably in the range of 5% by volume or more and 15% by volume or less. This is because, when the ratio is within the above range, for example, ink leakage during transportation can be reduced.

3. Ink Jet Ink The ink jet ink of the present invention is sealed in the container.
The inkjet ink comprises a polyalkylene glycol alkyl ether-based solvent, an acrylic resin (A), a structural unit represented by the following general formula (I), and a structural unit represented by the following general formula (II). And a binder resin containing at least one of the copolymers (B).

(In the general formulas (I) and (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 3 carbon atoms, and X represents Represents a halogen atom.)

(1) Binder resin The binder resin in the present invention contains at least one of the acrylic resin (A) and the copolymer (B).
Further, the binder resin has a site which is easily decomposed, such as a hydrocarbon site, and a radical generated by the decomposition reacts with oxygen to generate a carboxyl group. Oxygen can be consumed by undergoing oxidative degradation.

(A) Acrylic resin (A)
The acrylic resin (A) in the present invention refers to a polymer compound including a polymer using at least one selected from (meth) acrylic acid and derivatives thereof as at least a monomer. However, the acrylic resin (A) is different from the copolymer (B) described later, and the acrylic resin (A) does not include the copolymer (B) described later.
According to the present invention, by using the acrylic resin (A) as the binder resin, the tackiness after printing is suppressed, and the set-off and sticking after winding and drying can be reduced.

The acrylic resin (A) is preferably selected from the group consisting of alkyl (meth) acrylate, aralkyl (meth) acrylate, alkoxyalkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, and (meth) acrylic acid. From a radically polymerizable monomer. It has at least one radically polymerizable ethylenic double bond in the molecule, and preferably has one radically polymerizable ethylenic double bond in the molecule, and can be polymerized in the presence of a radical polymerization initiator in a solvent. Various monomers can be used as long as they are radically polymerizable monomers. For example, a vinyl compound or a maleimide may be contained as a radical polymerizable monomer.
The acrylic resin (A) may be a homopolymer of one kind of radically polymerizable monomer or a copolymer using two or more kinds of radically polymerizable monomers.

Examples of the radical polymerizable monomer used for the acrylic resin (A) include (meth) acrylic acid;
Methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, benzyl (meth) acrylate, phenethyl (meth) acrylate, methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate (Meth) acrylates such as, 2-methylcyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and trifluoroethyl (meth) acrylate;
(Meth) acrylamides such as (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dibutyl (meth) acrylamide, phenyl (meth) acrylamide, and benzyl (meth) acrylamide;
Styrene, α-, o-, m-, p-alkyl, nitro, cyano, amide, ester derivatives of styrene, (meth) acrylic anilide, (meth) acryloylnitrile, acrolein, vinyl chloride, vinylidene chloride, vinyl fluoride Vinyl compounds such as, vinylidene fluoride, N-vinylpyrrolidone, vinylpyridine, N-vinylcarbazole, vinylimidazole, and vinyl acetate;
Monomaleimides such as N-benzylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, N-laurinmaleimide, N- (4-hydroxyphenyl) maleimide;
Examples include phthalimides such as N- (meth) acryloylphthalimide.
In the present invention, among the above-mentioned monomers, it is preferable to use a monomer having no hydroxyl group, which has excellent ejection stability of the inkjet ink and excellent drying property of the ink on a recording medium, and has no hydroxyl group and no amino group. More preferably, a monomer is used.

  The content of (meth) acrylic acid and a derivative thereof as a monomer in the acrylic resin (A) is excellent in the ejection stability of the inkjet ink and the drying property of the ink on the recording medium. The amount is preferably 70 parts by mass or more, more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more based on 100 parts by mass of the monomer constituting the resin (A).

  Particularly preferred acrylic resin (A) is a polymer of methyl (meth) acrylate alone, or a mixture of methyl (meth) acrylate, butyl (meth) acrylate, ethoxyethyl (meth) acrylate, and benzyl (meth) acrylate. A copolymer with at least one or more compounds selected from the group, among which a polymer of methyl (meth) acrylate alone or a copolymer of methyl (meth) acrylate and butyl (meth) acrylate Is more preferable. In the above copolymer, a total of at least one compound selected from the group consisting of butyl (meth) acrylate, ethoxyethyl (meth) acrylate, and benzyl (meth) acrylate with respect to 100 parts by mass of methyl (meth) acrylate. The amount is preferably from 0.01 to 15 parts by mass, more preferably from 0.1 to 15 parts by mass, still more preferably from 0.5 to 12 parts by mass. Such an acrylic resin (A) has excellent ejection stability and drying properties, and can be used as an inkjet ink suitable for high-speed printing.

The acrylic resin (A) has a weight average molecular weight of 5,000 or more and 150,000 or less from the viewpoint of excellent ejection stability of the inkjet ink and excellent drying property of the ink on a recording medium. Is more preferable, and in particular, it is still more preferably from 10,000 to 70,000.
In the present invention, the mass average molecular weight Mw is a value measured by GPC (gel permeation chromatography), and a high-speed GPC apparatus (manufactured by Tosoh Corp., HLC-8120GPC) is used. / Liter of N-methylpyrrolidone to which lithium bromide was added, and the polystyrene standard for the calibration curve was Mw 377400, 210500, 96000, 50400, 206500, 10850, 5460, 2930, 1300, 580 (Easi PS- manufactured by Polymer Laboratories). 2 series) and Mw 1090000 (manufactured by Tosoh Corporation), and the measurement was performed using TSK-GEL ALPHA-M x 2 columns (manufactured by Tosoh Corporation).

Further, the acrylic resin (A) has a glass transition temperature (Tg) of 40 ° C. from the viewpoint of excellent ejection stability of the inkjet ink and excellent drying property of the ink on the recording medium. The glass transition temperature (Tg) is more preferably 70 ° C. or higher.
In the present invention, the glass transition temperature (Tg) is a value measured by a differential scanning calorimeter (DSC) (for example, a differential scanning calorimeter “DSC-50” manufactured by Shimadzu Corporation). Although a plurality of glass transition temperatures may be observed, the present invention employs a main transition temperature having a larger endothermic amount.
Although the acid value of the acrylic resin (A) is not particularly limited, the acid value of the resin is 10 mgKOH / g or less from the viewpoint of excellent ejection stability of the inkjet ink and excellent drying property of the ink on a recording medium. Preferably, it is not more than 5 mgKOH / g.
In the present invention, the acid value refers to the mass (mg) of potassium hydroxide required to neutralize an acidic component contained in 1 g of a sample (solid content of a resin), and the acid value is determined by the method described in JIS K0070. This is a value measured by the method according to the following.

The amine value of the acrylic resin (A) is not particularly limited, but is preferably 10 mgKOH / g or less, from the viewpoint of excellent ejection stability of the inkjet ink and excellent drying property of the ink on a recording medium. It is more preferably at most 5 mgKOH / g, even more preferably at most 2 mgKOH / g.
In the present invention, the amine value refers to the mass (mg) of potassium hydroxide which is equivalent to the amount of hydrochloric acid necessary to neutralize 1 g of the solid content of the resin, and according to the method described in JIS K 7237. This is a value measured by the method according to the following.

The hydroxyl value of the acrylic resin (A) is not particularly limited, but is preferably 10 mgKOH / g or less from the viewpoint of excellent ejection stability of the inkjet ink and excellent drying property of the ink on a recording medium. Is preferably 5 mgKOH / g or less, more preferably 2 mgKOH / g or less.
In the present invention, the hydroxyl value is the number of mg of potassium hydroxide required to acetylate the OH group contained in 1 g of the solid content of the resin, and is based on acetic anhydride according to the method described in JIS K0070. Is measured by acetylating the OH groups in the sample using and titrating unused acetic acid with a potassium hydroxide solution.
The acid value, amine value, and hydroxyl value can be appropriately adjusted depending on the type and content of the monomers constituting the resin.

The radical polymerization initiator used when producing the acrylic resin (A) is preferably an organic peroxide, and is a hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, or peroxycarbonate. , Peroxyketal, and ketone peroxide-based organic peroxides. Among them, dialkyl peroxide-based, peroxyester-based, and diacyl peroxide-based organic peroxides are preferable.
Preferred specific examples of the radical polymerization initiator include, but are not limited to, t-butylperoxy-2-ethylhexanoate, t-butyl hydroperoxide, di-t-hexyl peroxide, and the like. is not.

The polymer and copolymer used as the acrylic resin (A) can be used alone or in combination of two or more.
Examples of the commercially available acrylic resin (A) include, for example, “Paraloid B99N” (methyl methacrylate-butyl methacrylate copolymer) Tg 82 ° C., weight average molecular weight 15,000, and “Paraloid B60” manufactured by Rohm and Haas Company. (Methyl methacrylate-butyl methacrylate copolymer) having a Tg of 75 ° C. and a weight average molecular weight of 50,000).

(B) Copolymer (B)
The copolymer (B) in the present invention is a copolymer having a structural unit represented by the general formula (I) and a structural unit represented by the general formula (II).

Examples of the halogen atom for X in the general formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and are preferably a chlorine atom or a bromine atom, and more preferably a chlorine atom.
Specific examples of the monomer forming the structural unit represented by the general formula (I) include vinyl chloride, vinyl bromide, isopropenyl chloride, and isopropenyl bromide. Further, the wettability and spreadability of the ink on the recording medium is improved, and the optical density is high, and from the viewpoint that a printed matter excellent in stretchability can be obtained, among them, vinyl chloride or isopropenyl chloride is preferable, and vinyl chloride is preferable. More preferred.

In addition, examples of the alkyl group for R ³ in the general formula (II) include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, preferably a methyl group or an ethyl group, and more preferably a methyl group. Is more preferred.
Specific examples of the monomer forming the structural unit represented by the general formula (II) include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, isopropenyl acetate, isopropenyl propionate, isopropenyl butyrate, and isobutyric acid. Isopropenyl, which is excellent in the ejection stability of the ink jet ink, improves the wet spreadability of the ink on the recording medium, has a high optical density, and can provide a printed matter excellent in stretchability. Among them, vinyl acetate or isopropenyl acetate is preferable, and vinyl acetate is more preferable.

Other monomers constituting the copolymer (B) can be appropriately selected from conventionally known monomers and used. For example, a (meth) acrylate monomer having no functional group, exemplified as the monomer of the acrylic resin (A) described above, and other monomers can be suitably used.
In the present invention, it is particularly preferable to include a hydroxyalkyl (meth) acrylate. By containing a hydroxyalkyl (meth) acrylate as the other monomer, the ejection stability of the inkjet ink is excellent, the wettability and spreadability of the ink on a recording medium are improved, the optical density is high, and the stretchability is also high. This is because excellent printed matter can be obtained.

  The hydroxyalkyl (meth) acrylate may be appropriately selected from conventionally known hydroxyalkyl (meth) acrylates. Above all, 2-hydroxy is excellent in that the ejection stability of the ink-jet ink is excellent, the wettability and spreadability of the ink on a recording medium are improved, and a printed material having a high optical density and excellent stretchability can be obtained. Ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 1,2-propanediol 2- (meth) acrylate, methyl α- (hydroxymethyl) (meth) acrylate, ethyl α- (hydroxymethyl) (meth) Acrylate, n-butyl α- (hydroxymethyl) (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate or 4-hydroxybutyl (meth) acrylate is preferable, and among them, 2-hydroxypropyl (meth) ) Acrylate or 1,2-propanediol 2- (meth) Acrylate are preferred. The hydroxyalkyl (meth) acrylate can be used alone or in combination of two or more.

In the present invention, the copolymer (B) preferably contains, as a main component, a structural unit represented by the general formula (I). Above all, it excels in the ejection stability of inkjet inks, improves the ink wetting and spreading on recording media, has high optical density, has excellent adhesion to recording media, and has excellent alcohol resistance and stretchability. From the viewpoint that a printed matter can be obtained, the proportion of the structural unit represented by the general formula (I) in the copolymer (B) is preferably 70% by mass or more and 95% by mass or less, and more preferably 75% by mass or more. It is more preferable that the content be 90% by mass or less.
The proportion of the structural unit represented by the general formula (II) in the copolymer (B) is preferably from 4% by mass to 10% by mass, more preferably from 5% by mass to 8% by mass. preferable.
The proportion of the structural unit derived from hydroxyalkyl (meth) acrylate in the copolymer (B) is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 17% by mass. More preferred. This is because blocking at the time of winding after printing or the like can be suppressed.
In the present invention, the main component refers to the entire structural unit constituting the copolymer (B).
A structural unit that accounts for 50% by mass or more.

  In addition, the ink jet ink has excellent ejection stability, improves ink spreading on recording media, has high optical density, has excellent adhesion to recording media, and has excellent alcohol resistance and stretchability. From the viewpoint that a printed matter can be obtained, the structural unit represented by the general formula (I) in the copolymer (B) is represented by the following formula, based on the total of all the structural units constituting the copolymer (B). The total ratio with the structural unit represented by the formula (II) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably substantially 100% by mass. preferable.

The molecular weight of the copolymer (B) used in the present invention may be appropriately selected and is not particularly limited, but is excellent in ejection stability of the inkjet ink, and improves wettability and spreadability of the ink on a recording medium. The number average molecular weight is preferably 10,000 or more, and more preferably 10,000 or more and 50,000 or less, from the viewpoint that a printed matter having high optical density and excellent stretchability can be obtained. It is more preferable, and in particular, it is still more preferably from 10,000 to 30,000.
In the present invention, the number average molecular weight Mn is measured by GPC under the same conditions as in the measurement of the weight average molecular weight described above.

  Further, in the present invention, it is possible to obtain a printed matter which is excellent in ejection stability of an ink-jet ink, has improved ink spreadability on a recording medium, has a high optical density, and has excellent stretchability. Therefore, the glass transition temperature (Tg) of the copolymer (B) is preferably 40 ° C. or higher, and more preferably 50 ° C. or higher.

  As a commercially available copolymer (B), for example, "Solvain TA3" (manufactured by Nissin Chemical Industry Co., Ltd.) (copolymer of 83% by mass of vinyl chloride, 4% by mass of vinyl acetate, 13% by mass of hydroxyalkyl acrylate, Tg of 65 ° C, (Number average molecular weight 24,000).

(C) Binder resin The binder resin in the present invention contains at least one of the acrylic resin (A) and the copolymer (B).

  The binder resin contains at least one of the acrylic resin (A) and the copolymer (B), but preferably contains both the acrylic resin (A) and the copolymer (B). When the binder resin contains both the acrylic resin (A) and the copolymer (B), the binder resin is excellent in ejection stability and intermittent ejection property even when applied to high-speed printing, and the ink on a recording medium can be used. This is because the wet film has excellent wet spreadability, excellent drying properties of the obtained coating film, and the obtained printed matter has high optical density and high quality, and can have excellent alcohol resistance and stretchability. .

  In the binder resin, the content ratio of the acrylic resin (A) and the copolymer (B) is (A) / (B) = 40/60 or more and 70/30 or less on a mass basis. By using it, it is excellent in ejection stability and intermittent ejection even when applied to high-speed printing, excellent in ink spreading on recording medium, excellent in drying property of obtained coating film, and obtained printed matter Has high optical density and high quality, and is also excellent in alcohol resistance and stretchability. Above all, it is preferable to use a combination of the acrylic resin (A) and the copolymer (B) in a content ratio of (A) / (B) = 40/60 or more and 60/40 or less on a mass basis. .

The binder resin may further contain another resin as long as the effects of the present invention are not impaired. As other resins, for example, a conventionally known vinyl chloride-vinyl acetate copolymer or the like is preferably mentioned.
Such other resins are excellent in ejection stability and intermittent ejection property even when applied to high-speed printing, are excellent in ink spreading on a recording medium, and are excellent in drying property of the obtained coating film, From the viewpoint that the obtained printed matter has high optical density and high quality, and is excellent in alcohol resistance and stretchability, the amount is preferably 20 parts by mass or less based on 100 parts by mass of the binder resin, and 10 parts by mass or less. It is more preferred that:

The total content of the binder resin may be appropriately adjusted. Among them, the total content of the binder resin is 4.9 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the total amount of the inkjet ink. Is preferably 5 to 30 parts by mass, and more preferably 6 to 25 parts by mass.
When the content is within the above-described range, the ink has excellent ejection stability and intermittent ejection even when applied to high-speed printing, and has excellent wettability and spreadability of the ink on a recording medium, and the obtained coating film. This is because the resulting printed matter has high optical density and high quality, and can also have excellent alcohol resistance and stretchability.

(2) Polyalkylene glycol alkyl ether-based solvent The polyalkylene glycol alkyl ether-based solvent in the present invention is contained as a main solvent of the inkjet ink and is capable of dissolving oxygen.
In addition, being contained as a main solvent means being contained in 60% by mass or more of the total solvent. In the present invention, the content is preferably 70% by mass or more of the total solvent, particularly preferably 80% by mass or more. This is because when the content is the above, low-odor and high-speed printing can be performed while maintaining the quality of the printed matter.

As such a polyalkylene glycol alkyl ether solvent, a polyalkylene glycol monoalkyl ether solvent and a polyalkylene glycol dialkyl ether solvent can be used.
In the present invention, among them, polyalkylene glycol dialkyl ether solvents can be preferably used. This is because high-speed printing is possible with low odor.

(A) Polyalkylene glycol monoalkyl ether solvent The polyalkylene glycol monoalkyl ether solvent can be appropriately selected from known solvents as solvents.
For example, those represented by the following general formula (III) can be mentioned. This is because the use of a compound represented by the following general formula (III) makes it possible to obtain a high-quality printed matter having excellent intermittent ejection properties and improved ink spreadability on a recording medium. .

(In the general formula (III), R ⁴ represents an alkyl group having 1 to 4 carbon atoms, R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents a methylene group or an ethylene group, and m represents 2 to 4 The plurality of R ⁵ and R ⁶ may be the same or different.)

Examples of the alkyl group having 1 to 4 carbon atoms in R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, and a butyl group, and among them, a methyl group or an ethyl group is preferable.
m is an integer of 2 to 4, and among them, m is preferably an integer of 2 to 3.

Among the polyalkylene glycol monoalkyl ether solvents represented by the general formula (III), dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, triethylene glycol monomethyl ether, or triethylene glycol monobutyl ether, among others, However, it is preferable because it is excellent in intermittent ejection property, improves ink wettability and spreadability on a recording medium, has high optical density, and can provide high-quality printed matter.
The polyalkylene glycol monoalkyl ether solvents represented by the general formula (III) can be used alone or in combination of two or more.

(B) Polyalkylene glycol dialkyl ether-based solvent The polyalkylene glycol dialkyl ether-based solvent can be appropriately selected from known solvents as solvents.

  The polyalkylene glycol dialkyl ether-based solvent is preferably represented by the following general formula (IV) from the viewpoint that high-speed printing can be performed while maintaining the quality of the printed matter.

(In the general formula (IV), R ⁷ and R ⁸ each independently represent an alkyl group having 1 to 4 carbon atoms, R ⁹ represents a hydrogen atom or a methyl group, and R ¹⁰ represents a methylene group or an ethylene group. , N is an integer of 2 to 4. A plurality of R ⁹ and R ¹⁰ may be the same or different.)

Examples of the alkyl group having 1 to 4 carbon atoms in R ⁷ and R ⁸ include a methyl group, an ethyl group, a propyl group, and a butyl group, and among them, a methyl group or an ethyl group is preferable.
n is an integer of 2 to 4, among which n is preferably an integer of 2 to 3, and n is more preferably 2.

Specific examples of the polyalkylene glycol dialkyl ether-based solvent represented by the general formula (IV) include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, and the like. Of these, diethylene glycol diethyl ether or diethylene glycol methyl ethyl ether is particularly preferred from the viewpoint that high-speed printing can be performed with low odor while maintaining the quality of the printed matter.
The polyalkylene glycol dialkyl ethers may be used alone or in combination of two or more.

(C) Polyalkylene glycol alkyl ether-based solvent As the polyalkylene glycol alkyl ether-based solvent, a polyalkylene glycol monoalkyl ether-based solvent and a polyalkylene glycol dialkyl ether-based solvent can be used.
In the present invention, any solvent containing at least one of a polyalkylene glycol monoalkyl ether-based solvent and a polyalkylene glycol dialkyl ether-based solvent, or both may be used.

The content of the polyalkylene glycol alkyl ether-based solvent may be appropriately adjusted according to the viscosity of the inkjet ink and the like, and is not particularly limited, but is preferably 50 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the inkjet ink. It is preferably from 60 parts by mass to 90 parts by mass, and particularly preferably from 70 parts by mass to 85 parts by mass. When the content of the solvent is within the above-mentioned range, the ink in the gas dissolves and the consumption of oxygen by the binder resin progresses while maintaining the quality of the printed matter and forming an inkjet ink capable of high-speed printing with low odor while maintaining the quality. Even in the case where the ink package is easily used, it is possible to reduce the deformation of the container by using the gas and the container. Therefore, the effects of the present invention can be more effectively exhibited.
In addition, from the viewpoint of suppressing a change in appearance, the content of the polyalkylene glycol alkyl ether-based solvent is preferably 50 parts by mass or more and 65 parts by mass or less per 100 parts by mass of the inkjet ink. It is preferable that the amount is not less than 60 parts by mass and not more than 10 parts by mass.

(3) Other Components The ink-jet ink of the present invention contains the binder resin and a polyalkylene glycol alkyl ether-based solvent, but usually contains a coloring material.
Further, the ink-jet ink may contain other solvents, various additives, and the like, if necessary.

(A) Coloring Material The coloring material in the invention can be appropriately selected from known coloring materials used in inkjet inks, and includes known dyes, organic pigments, inorganic pigments, and the like. As the coloring material, among others, it is preferable to use a pigment from the viewpoints of color development and weather resistance.

Examples of the organic pigment include insoluble azo pigments, soluble azo pigments, derivatives from dyes, phthalocyanine-based organic pigments, quinacridone-based organic pigments, perylene-based organic pigments, dioxazine-based organic pigments, nickel azo-based pigments, and isoindolinone-based organic pigments Organic solid solution pigments such as pyranthrone-based organic pigments, thioindigo-based organic pigments, condensed azo-based organic pigments, benzimidazolone-based organic pigments, quinophthalone-based organic pigments, isoindoline-based organic pigments, quinacridone-based solid-solution pigments, and perylene-based solid-solution pigments; Other pigments include carbon black and the like.
When an organic pigment is exemplified by a color index (CI) number, C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 20, 24, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 117, 120, 125, 128, 129, 130, 137, 138, 139, 147, 148, 150, 151, 153, 154, 155, 166, 168, 180, 185, 213, 214; I. Pigment Red 5, 7, 9, 12, 48, 49, 52, 53, 57, 97, 112, 122, 123, 147, 149, 168, 177, 180, 184, 192, 202, 206, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 238, 240, 242, 254; I. Pigment Orange 16, 36, 43, 51, 55, 59, 61, 64, 71; I. Pigment Violet 19, 23, 29, 30, 37, 40, 50; I. Pigment Blue 15, 15: 1, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64; I. Pigment Green 7, 36, 58, 59; C.I. I. Pigment Brown 23, 25, 26 and the like.

  Specific examples of the inorganic pigment include barium sulfate, iron oxide, zinc oxide, barium carbonate, barium sulfate, silica, clay, talc, titanium oxide, calcium carbonate, synthetic mica, alumina, zinc white, lead sulfate, yellow lead, Examples thereof include zinc yellow, red iron oxide (red iron (III)), cadmium red, ultramarine blue, dark blue, chromium oxide green, cobalt green, amber, titanium black, synthetic iron black, and inorganic solid solution pigments.

In the present invention, the pigment is C.I. I. Cyan pigments such as CI Pigment Blue 15: 3 and 15: 4; I. Green pigments such as CI Pigment Green 7, 36, 58 and 59; I. Magenta pigments such as CI Pigment Red 122 and 202, and Pigment Violet 19; It is preferably a yellow pigment such as I. Pigment Yellow 150, 155 or 180, or a black pigment such as carbon black. By including the pigment, absorption of oxygen by the inkjet ink tends to be promoted. For this reason, the effect of suppressing deformation of the container of the present invention can be more effectively exerted.
In the present invention, among others, the pigment is preferably a cyan pigment, a green pigment, a black pigment and a magenta pigment, and particularly preferably a cyan pigment, a green pigment and a black pigment, Among them, a cyan pigment and a green pigment are particularly preferable. The above pigments tend to be in the order of a cyan pigment, a black pigment, a magenta pigment and a yellow pigment when the pigments are arranged in ascending order in which the absorption of oxygen is promoted and the appearance of the pigment easily changes. Further, since the structure of the green pigment is similar to that of the cyan pigment, the appearance of the green pigment tends to be substantially the same as that of the cyan pigment. Therefore, by including the above-mentioned pigment as the above-mentioned pigment, the effect of suppressing deformation of the container of the present invention can be more effectively exerted.
The reason why such a pigment promotes the absorption of oxygen is not clear, but it is considered that the pigment acts as a catalyst for the consumption of oxygen by the binder resin.

The average dispersion particle diameter of the pigment is not particularly limited as long as the desired color development is possible, and varies depending on the type of the pigment used, but the dispersion stability of the pigment is good, and sufficient coloring power is obtained. From the viewpoint of obtaining, it is preferably in the range of 5 nm to 400 nm, and more preferably in the range of 30 nm to 300 nm. When the average dispersed particle diameter is equal to or less than the upper limit, nozzle clogging of the inkjet head is unlikely to occur, a highly reproducible homogeneous image can be obtained, and the obtained printed matter can be of high quality. Because. This is because light resistance may be reduced when the content is below the above lower limit.
The average dispersed particle diameter of the pigment was obtained by preparing a measurement sample obtained by diluting the ink about 50 times with ethyl diglycol acetate and measuring the ink by a dynamic scattering light method. Specifically, it can be measured at a measurement temperature of 25 ° C. using a laser diffraction / scattering type particle size analyzer Microtrac particle size analyzer UPA150 (manufactured by Nikkiso Co., Ltd.).

  The content of the pigment is not particularly limited as long as a desired image can be formed, and is appropriately adjusted. Specifically, the content varies depending on the kind of the pigment, but is preferably in the range of 0.05 to 25 parts by mass, and more preferably 0.1 to 25 parts by mass with respect to 100 parts by mass of the inkjet ink. More preferably, the amount is in the range of 20 parts by mass to 20 parts by mass. This is because when the content is within the above-mentioned range, it is possible to achieve an excellent balance between the dispersion stability of the pigment and the coloring power.

In the present invention, in order to disperse the pigment, it is preferable to use a combination of a dispersant.
Further, the use of the above dispersant tends to promote the absorption of oxygen by the inkjet ink. For this reason, the effect of suppressing deformation of the container of the present invention can be more effectively exerted.
The reason why such a dispersant promotes the absorption of oxygen is not clear, but is considered to be because it acts as a catalyst for the consumption of oxygen by the binder resin.

The dispersant can be appropriately selected from those conventionally used as dispersants.
As the dispersant, for example, a cationic, anionic, nonionic, amphoteric, silicone, or fluorine-based surfactant can be used. Among the surfactants, polymer surfactants (polymer dispersants) are preferable because they can be uniformly and finely dispersed.

  Examples of the polymer dispersant include (co) polymers of unsaturated carboxylic esters such as polyacrylic esters; (partial) amine salts of (co) polymers of unsaturated carboxylic acids such as polyacrylic acid , (Partially) ammonium salts and (partially) alkylamine salts; (co) polymers of hydroxyl group-containing unsaturated carboxylic acid esters such as hydroxyl group-containing polyacrylates and modified products thereof; polyurethanes; unsaturated polyamides; Siloxanes; long-chain polyaminoamide phosphates; polyethyleneimine derivatives (amides and their bases obtained by the reaction of poly (lower alkyleneimine) with free carboxyl group-containing polyester); polyallylamine derivatives (polyallylamine and free Polyester, polyamide or ester having carboxyl group and amide Compound reaction product obtained by the reaction of one or more compounds selected from the three compounds of (polyester amide)) and the like, is preferably used among others polyester dispersant.

When the pigment is dispersed using the above dispersant, the content of the dispersant is preferably 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the pigment, and 20 parts by mass or more. More preferably, it is 120 parts by mass or less. This is because if the content is within the above range, an inkjet ink having excellent dispersibility and dispersion stability can be obtained.
Further, by being within the above range, absorption of oxygen by the inkjet ink is promoted, and the effect of suppressing deformation of the container of the present invention can be more effectively exerted.

(B) Other Solvents Other solvents in the present invention are solvents other than the above-mentioned polyalkylene glycol alkyl ether solvents.
Such other solvents are not particularly limited as long as they do not react with each component in the ink-jet ink and do not inhibit the effects of the present invention, and those commonly used in ink-jet inks are used. can do.
Examples of the other solvents include a cyclic ester, ethylene glycol alkyl ether acetate, polyethylene glycol alkyl ether acetate, propylene glycol alkyl ether acetate, and polypropylene glycol alkyl ether acetate.

The cyclic ester refers to one in which a hydroxyl group and a carboxyl group in the same molecule are dehydrated and condensed to form a cyclic structure.
By containing the cyclic ester as a solvent, it is possible to improve the solubility of the binder resin and to provide an inkjet ink having excellent intermittent ejection properties and ejection stability.

In the present invention, the cyclic ester can be appropriately selected from known solvents as solvents. As the cyclic ester, a cyclic ester having a 4- to 7-membered ring structure is preferable, and a cyclic ester having a 5- to 7-membered ring structure is more preferable, from the viewpoint of excellent intermittent ejection properties.
Specific examples of the cyclic ester include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, and the like.
The cyclic ester can be used alone or in combination of two or more.

The content of the cyclic ester may be appropriately adjusted according to the viscosity of the inkjet ink and the like, and may be in the range of 3 parts by mass to 10 parts by mass with respect to 100 parts by mass of the inkjet ink.
When the content is within the above range, it is possible to improve the solubility of the binder resin and to provide an ink having excellent intermittent ejection property and ejection stability. In addition, it has a low odor, is excellent in drying properties, improves the wettability and spreadability of the ink on the recording medium, and can obtain a high-quality printed matter having a high optical density.
In the present invention, the content of the cyclic ester is preferably from 3.5 parts by mass to 9.5 parts by mass, more preferably from 4 parts by mass to 9 parts by mass, based on 100 parts by mass of the inkjet ink. preferable.
In particular, in order to obtain high-quality printed matter in high-speed printing, when emphasis is placed on the drying property, wet spreading property, and high optical density of the ink, the content of the cyclic ester is 100 parts by mass of the inkjet ink. It is preferably 3 parts by mass or more and 6 parts by mass or less, more preferably 3.5 parts by mass or more and 5.5 parts by mass or less, even more preferably 4 parts by mass or more and 5 parts by mass or less. .
On the other hand, when emphasis is placed on improving intermittent ejection properties and ejection stability in order to make the ink more suitable for the inkjet method, the content of the cyclic ester is 6 parts by mass or more based on 100 parts by mass of the inkjet ink. It is preferably at most 10 parts by mass, more preferably at least 6.5 parts by mass and at most 9.5 parts by mass, even more preferably at least 7 parts by mass and at most 9 parts by mass.

  By containing the ethylene glycol alkyl ether acetate as a solvent, it is possible to improve the solubility of the binder resin and to provide an inkjet ink having excellent intermittent ejection properties and ejection stability.

  Examples of the ethylene glycol alkyl ether acetate include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate.

The content of the ethylene glycol alkyl ether acetate may be appropriately adjusted depending on the viscosity of the ink-jet ink and the like, and may be contained at 5 parts by mass or less based on 100 parts by mass of the ink-jet ink. When the content is within the above range, low odor can be ensured even during high-speed printing. By containing ethylene glycol alkyl ether acetate, it is also possible to improve the solubility of the binder resin and to improve the intermittent ejection property.
On the other hand, from the viewpoint of reducing odor during drying of the coating film of the inkjet ink, the content of ethylene glycol alkyl ether acetate is preferably 3 parts by mass or less per 100 parts by mass of the inkjet ink, and more preferably 1 part by mass or less. Is more preferable, and it is even more preferable that it is not substantially contained.

  By containing the above-mentioned polyethylene glycol alkyl ether acetate, propylene glycol alkyl ether acetate, and polypropylene glycol alkyl ether acetate as a solvent, the solubility of the binder resin is improved, and the inkjet ink is excellent in intermittent discharge performance and discharge stability. It can be.

Examples of the polyethylene glycol alkyl ether acetate include diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, triethylene glycol methyl ether acetate, triethylene glycol ethyl ether acetate, and triethylene glycol butyl ether acetate.
Specific examples of propylene glycol alkyl ether acetate include propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate.
Specific examples of polypropylene glycol alkyl ether acetate include dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate, dipropylene glycol butyl ether acetate, tripropylene glycol methyl ether acetate, tripropylene glycol ethyl ether acetate, and tripropylene glycol. Butyl ether acetate.

The content of the polyethylene glycol alkyl ether acetate is preferably 2 parts by mass or less, more preferably 1 part by mass or less per 100 parts by mass of the inkjet ink, from the viewpoint of reducing odor during drying of the coating film. Is still more preferably not substantially contained.
The content of the propylene glycol alkyl ether acetate is preferably 5 parts by mass or less, more preferably 3 parts by mass or less per 100 parts by mass of the inkjet ink, from the viewpoint of reducing the odor when the coating film is dried. Is still more preferably not substantially contained.
Further, the content of the polypropylene glycol alkyl ether acetate is preferably 2 parts by mass or less, more preferably 1 part by mass or less per 100 parts by mass of the inkjet ink, from the viewpoint of reducing odor during drying of the coating film. More preferably, it is even more preferable that it is not substantially contained.

(C) Additives Additives include antioxidants, surfactants, defoamers, pH adjusters, viscosity adjusters, and the like.
Further, the additive preferably contains a resin stabilizer such as an antioxidant. This is because by including such a resin stabilizer, consumption of oxygen by the inkjet ink can be suppressed. For this reason, the deformation of the container can be more stably suppressed.

(4) Manufacturing method of inkjet ink The manufacturing method of the inkjet ink is not particularly limited, and can be appropriately selected from conventionally known methods. The above production method is, for example, a polyalkylene glycol alkyl ether-based solvent, a coloring material, and a dispersant, if necessary, to prepare a pigment dispersion, a binder resin to the pigment dispersion, and, if necessary, A method of obtaining an ink-jet ink by adding an optional additive component and stirring the mixture depending on the case may be used.

4. Ink Package The ink package of the present invention includes a container, an inkjet ink, and a gas, but may have another configuration as needed.
Such other configurations include a lid for sealing the container.
The lid is not particularly limited as long as it can seal the container, and is appropriately selected according to the shape of the container opening.
Further, the above-mentioned other configuration can include a seal member disposed between the container and the lid. As the sealing member, known members can be used as long as they have sealing properties.For example, a polyolefin foam layer / aluminum layer / sealant layer is provided, and the container is sealed by high-frequency induction heating or the like. Can be used. As the sealant layer, for example, a resin such as polyethylene terephthalate, polypropylene, or polyethylene can be used.
In addition, the said sealing member is not restricted to what is used with the said lid, What is used for sealing a container by using a sealing member alone may be used. Examples of using the seal member alone include, for example, a mode in which the container is used as a tape-shaped member that closes the opening of the container, or a seal member included in the whole or a part of the material forming the container, and can be sealed by heat compression. It can be used as a heat seal portion.

B. Next, a method for manufacturing the ink package will be described.
The method for producing an ink package of the present invention is the method for producing an ink package described above, wherein an ink filling step of filling the inkjet ink so as to provide a void in the container, and an inert gas filled in the container. And filling the container with the gas having an oxygen partial pressure of less than 0.2 atm.

The method for manufacturing such an ink package of the present invention will be described with reference to the drawings. FIG. 3 is a process chart showing an example of the method for producing an ink package of the present invention. As shown in FIG. 3 (a), the method for manufacturing an ink package of the present invention fills the container 1 with the ink-jet ink 2 so as to provide the void 1a, and then fills the void 1a with an inert gas. g, the oxygen in the gas 3a before the replacement existing in the space 1a is replaced by the inert gas g, so that the partial pressure of oxygen in the space 1a in the container 1 is reduced. The ink package 10 is obtained by filling the container 1 with a gas 3 having a pressure of less than 0.2 atm (FIG. 3B) and sealing the container 1 with a lid 4 (FIG. 3C).
In this example, as shown in FIG. 3A, an oxygen concentration meter 11 is installed in the gap 1a, and while supplying the inert gas g, the oxygen partial pressure of the gas existing in the gap 1a is increased. Is measured to confirm that the oxygen partial pressure of the gas is less than 0.2 atm.
FIG. 3A shows the ink filling step, FIG. 3B shows the replacement step and the inspection step, and FIG. 3C shows the sealing step.

According to the present invention, the partial pressure of oxygen of the gas can be easily reduced to less than 0.2 atm by having the above-described substitution step.
For this reason, even when the inkjet ink containing the specific solvent and the binder resin is sealed in a container whose appearance changes when the internal pressure in the sealed state is 0.8 atm or more, the The ink package with little deformation can be easily obtained.

The method for producing an ink package of the present invention includes the above-described ink filling step and replacement step.
Hereinafter, each step of the method for manufacturing an ink package of the present invention will be described.

1. Ink Filling Step The ink filling step in the present invention is a step of filling the ink jet ink so as to provide a void in the container.

The container and the ink-jet ink used in this step are the same as those described in the above section “A. Ink package”, and thus description thereof will be omitted.
The void portion is a space in the container not filled with the inkjet ink, and refers to a space in which the gas can be stored. Therefore, the volume of the void is the volume of the gas sealed in the container (at 25 ° C. and 1 atm), and the ratio of the void to the internal volume of the container is as described in “A. Ink Packaging”. The ratio of the "gas" of the "body" to the internal volume of the gas in the container can be the same.
Filling to provide a void means to fill the container with a volume of inkjet ink obtained by subtracting the volume of the void from the total volume of the container.

In this step, the method for filling the container with the inkjet ink may be the same as the method for filling a general inkjet ink.
In the present step, when the replacement step is performed before the present step, that is, when the present step is performed after the inside of the container is filled with the gas, the method of filling the container with the inkjet ink is performed under the following conditions. It is preferable to use a method in which the inkjet ink is filled at a filling rate that does not replace the gas filling the container.

2. Substitution Step The substitution step in the present invention is a step of filling the container with an inert gas and filling the container with the gas having an oxygen partial pressure of less than 0.2 atm.

  Since the container and the inert gas used in this step are the same as those described in the above section “A. Ink package”, description thereof will be omitted.

The filling method for filling the container with an inert gas in this step is not particularly limited as long as the inside of the container can be filled with the gas having an oxygen partial pressure of less than 0.2 atm. A general method of filling the gas in the container can be used.
The above-mentioned filling method is, for example, a method of disposing a nozzle tip in a container and supplying an inert gas from the nozzle, disposing the whole container in a box, and putting the entire box inside in an inert gas environment. Thus, a method of supplying an inert gas into the container can be given.
The internal pressure in the container after this step is preferably 1 atm. This is because it is easy to fill the inside of the container with an inert gas and fill the inside of the container with the gas having an oxygen partial pressure of less than 0.2 atm.

The execution timing of this step may be any timing before the ink filling step, during the ink filling step, and after the ink filling step.
Here, if the execution timing is before the ink filling step, the present step is to fill an empty container not filled with the inkjet ink with an inert gas. In addition, when the execution timing is after the ink filling step, the inert gas is filled in the void portion in the container provided in the ink filling step.

  The gas filled so as to fill the inside of the container in this step is the same as the content described in the above section “A. Ink package”, and the description thereof will be omitted.

3. Method for Producing Ink Package The method for producing an ink package of the present invention includes the above-described replacement step, but may include other steps as necessary.
As such another step, it is preferable to include an inspection step of inspecting that the oxygen partial pressure of the gas is less than 0.2 atm during or after the substitution step.
By having the inspection step, it is possible to confirm that the oxygen partial pressure of the gas is less than 0.2 atm, and it is possible to stably obtain an ink package having a gas oxygen partial pressure of less than 0.2 atm. Because.

(1) Inspection Step The inspection step in the present invention is a step of inspecting that the oxygen partial pressure of the gas is less than 0.2 atm during or after the replacement step.

The method for confirming the oxygen partial pressure of the gas in this step is not particularly limited as long as it can accurately measure the oxygen partial pressure of the gas present in the container, and is measured using an oxygen concentration meter. A method can be used.
The oxygen concentration meter is not particularly limited as long as it can accurately measure the oxygen concentration of the gas. For example, a trace oxygen analyzer RO-102-SDP manufactured by Iijima Electronics Co., Ltd. or the like is used. be able to.

During the replacement step refers to measuring the oxygen partial pressure of the gas in the container in parallel with the filling of the container with the inert gas. After confirming that the replacement has been completed, the replacement step is completed.
On the other hand, “after the completion of the replacement step” means that the replacement is performed after the completion of the replacement step, that is, after the replacement of the inert gas is stopped.

The execution timing of this step may be during the above replacement step or after the completion of the above replacement step.
When the execution timing is during the replacement step, the replacement step can be completed when the oxygen partial pressure reaches the specified value, and thus there is an advantage that the completion of the replacement step can be grasped in a timely manner.
Further, when the execution timing is after the end of the replacement step, there is an advantage that both steps do not need to be performed simultaneously and the steps are not complicated.

(2) Others Other steps other than the inspection step in the present invention include a sealing step of sealing the container after the replacement step.
Note that, for such other steps, a method generally used in a method for manufacturing an ink package can be used.

  Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention, and any device having the same function and effect can be realized by the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically with reference to Examples.

[Ink Preparation Example 1]
The following composition was used as the organic solvent.
-Diethylene glycol diethyl ether (DEDG): 75.01 parts by mass-Diethylene glycol methyl ethyl ether (MEDG): 4.31 parts by mass-γ-butyrolactone (GBL): 6.90 parts by mass

In a part of the solvent having the above composition, 3.0 parts by mass of phthalocyanine blue (Pigment Blue 15: 4) which is a cyan pigment as the pigment 1 and a dispersant (polyester polymer compound, manufactured by Takefu Fine Chemical Co., Ltd.) (Hinoact KF1-M)) and stirred for 1 hour at 3,000 rpm with a dissolver, followed by preliminary dispersion with a bead mill filled with zirconia beads (2 mm). The average particle size of the obtained coloring material particles was 5 μm or less. This dispersion was further performed using a nanomill filled with zirconia beads (0.3 mm) to obtain a colorant dispersion. The average particle size of the coloring material particles obtained by the main dispersion was 60 nm.
Then, while stirring the obtained colorant dispersion liquid at 4,000 rpm, 5.91 parts by mass of a binder resin 1 (“Paraloid B60” manufactured by Rohm & Haas Co.), which is an acrylic resin (A), and a copolymer (B) 3.78 parts by mass of binder resin 2 (“Solvain TA3” manufactured by Nissin Chemical Industry Co., Ltd.) and the remainder of the produced organic solvent were added to prepare an inkjet ink (ink A).

[Ink Preparation Examples 2 to 16]
Ink jet inks (Inks BP) were prepared in the same manner as in Ink Preparation Example 1, except that the composition of each component was changed as shown in Tables 1 and 2 below.
In Tables 1 and 2, Pigments 2 to 4 are nickel azo yellow (Pigment Yellow 150) as a yellow pigment, quinacridone magenta (Pigment Red 122) as a magenta pigment, and carbon black as a black pigment, respectively. It shows.
Further, the binder resin 3 described as the binder resin indicates “Solvain CLL” manufactured by Nissin Chemical Industry Co., Ltd., which is a copolymer (B).
In Tables 1 and 2, BGAc and MEDG described as solvents indicate butyl glycol acetate and diethylene glycol methyl ethyl ether.

[Evaluation of oxygen solubility of solvent]
With respect to the solvent used in the ink preparation examples, the solubility of oxygen was evaluated by the following method.

(Evaluation method for oxygen solubility)
Under a condition of 25 ° C., put 50 cc of solvent into a syringe, take 50 cc of oxygen into another syringe, connect two syringes, push the piston of the syringe containing oxygen, and syringe until the volume does not change. Shake well. Thereafter, the volume of oxygen was measured, and the volume reduced from 50 cc was defined as the solubility of oxygen. The results are shown in Table 3 below.

  From Table 3, it was confirmed that the polyalkylene glycol alkyl ether solvent had high oxygen solubility.

[Example 1]
As a container, the following 1 L HDPE container was prepared, and 1 L HDPE was filled with ink A so that the ink filling rate was 87% by volume.
Then, while measuring the oxygen concentration in the gas in the cavity of the container with an oxygen concentration meter, nitrogen was supplied to the cavity, and after confirming that the oxygen partial pressure was 0.05 atm, the supply of nitrogen was stopped. Stop and seal container with lid. Thus, an ink package was produced.

(1L HDPE)
・ Material: High density polyethylene ・ Thickness: 1.5mm
Diameter: 89.2 mm
-Height: 228.1 mm
・ Shape: Cylindrical ・ Internal volume: 1L
-Those whose appearance changes when the internal pressure in a closed state is 0.8 atm, and no change in appearance when the internal pressure is 0.9 atm.

[Examples 2 to 22 and Comparative Examples 1 to 4]
As containers, the following 1L plastic container, 200L HDPE container, inner surface resin-coated petroleum can was used, and the ink filling rate, oxygen partial pressure after replacement, replacement gas, and ink were changed as shown in Tables 4 to 6 below. In the same manner as in Example 1, an ink package was produced.

(1L poly)
・ Material: Polyethylene ・ Film thickness: 0.7mm
・ Diameter: 91.5mm
・ Height: 217mm
・ Shape: Cylindrical ・ Internal volume: 1L
-Those whose appearance changes when the internal pressure is 0.8 atm in a sealed state and does not change appearance when the internal pressure is 0.9 atm.

(200L HDPE)
・ Material: High density polyethylene ・ Thickness: 3.0mm
・ Diameter: 588mm
・ Height: 905mm
-Shape: cylindrical shape-Internal volume: 200L
-Those whose appearance changes when the internal pressure is 0.8 atm in a sealed state, and does not change appearance when the internal pressure is 0.9 atm.

(HB can (inside resin-coated petroleum can))
・ Material: Tin-free styrene (metal material) and polyolefin-based multilayer film (resin material)
・ Film thickness: metal material 0.32 mm, resin material 0.07 mm
-Width and depth: 238 mm x 238 mm
-Height: 349.5 mm
-Shape: rectangular parallelepiped shape-Inner volume: 19.25L
-Those whose appearance changes when the internal pressure is 0.8 atm in a sealed state and does not change appearance when the internal pressure is 0.9 atm.

[Evaluation]
The following evaluations were made regarding the presence or absence of changes in appearance, ejection stability, coating film drying property, ethanol resistance, and odor.

(1) Evaluation of presence / absence of change in appearance After storing each of the ink packages of Examples and Comparative Examples at 60 ° C. for 2 weeks, the presence / absence of change in appearance was evaluated. In addition, the evaluation of the container was performed by visual confirmation and the volume change of the container before and after storage. The results are shown in Tables 4 to 6 below.

(Evaluation criteria for visual change in appearance)
◎: No change ：: Very slight deformation is observed (deformation of practically acceptable level)
×: noticeable deformation

(Method of measuring volume change)
The sealed container was immersed in a water tank before ink filling and after storage at 60 ° C. for 2 weeks, and the volume change was confirmed.

(2) Evaluation of discharge stability Each of the inkjet recording inks of Examples and Comparative Examples was subjected to a piezo drive type inkjet head KM512MHX (Konica Corporation) in an environment of room temperature 25 ± 3 (° C.) and humidity 45 ± 5% RH. Using a discharge evaluation tester equipped with a Minolta Co., Ltd.), the maximum speed at which liquid droplets were continuously discharged while increasing the discharge speed by increasing the applied voltage and stable without disturbance was measured. The results are shown in Tables 4 to 6 below.

(Discharge stability evaluation criteria)
：: The maximum speed was 10 m / s or more.
Δ: The maximum speed was 8 m / s or more and less than 10 m / s.
X: The maximum speed was less than 8 m / s.
If the discharge stability evaluation is ○ or △, the discharge stability at the time of high-speed printing is excellent, and it is evaluated that it can be used without practical problems.

(3) Evaluation of Drying Property of Coating Film Each of the inkjet inks for inkjet recording of Examples and Comparative Examples was subjected to a piezo-driven inkjet head KM512MHX in an environment of room temperature 25 ± 3 (° C.) and humidity 45 ± 5% RH. Was printed on a recording medium (PVC sheet JT5829R, manufactured by Mac Tact Co.) at 720 dpi using a discharge evaluation tester equipped with a printer to form a coating film. The recording medium on which the coating film was formed was heated on a hot plate at 45 ° C., and the time during which tackiness disappeared was measured by finger touch. The results are shown in Tables 4 to 6 below.

(Dryability evaluation criteria)
：: dried within 2 minutes.
Δ: Exceeded 2 minutes and dried within 5 minutes.
X: It was not dried even after 5 minutes.
If the evaluation of the drying property is ○ or △, the drying property is excellent and it is evaluated that it can be used without any practical problem.

(4) Evaluation of ethanol resistance of coating film After forming a coating film in the same manner as in the evaluation of the drying property, the coating film was dried in an oven at 60 ° C for 5 minutes, and further dried at room temperature for 12 hours or more to obtain a dried coating film. Using a cloth impregnated with an aqueous ethanol solution (Ben Cotton, manufactured by Asahi Kasei Corporation), the coating film surface was wiped to observe whether the recording medium was visible. The same test was performed by changing the concentration of the aqueous ethanol solution, and the maximum concentration of ethanol that did not expose the recording medium was measured. The results are shown in Tables 4 to 6 below.

(Ethanol resistance evaluation criteria)
：: The recording medium was not exposed even when an ethanol aqueous solution of 50% or more was used.
Δ: The recording medium was exposed with an aqueous ethanol solution of 30% or more and less than 50%.
×: The recording medium was exposed with an aqueous ethanol solution of less than 30%.
If the ethanol resistance evaluation is ○ or Δ, the ethanol resistance is excellent, and it is evaluated that it can be used without practical problems.

(5) Odor test 0.5 g of each ink jet ink for ink jet recording of each of Examples and Comparative Examples was placed in a Petri dish, and allowed to stand on a hot plate at 45 ° C. for 2 minutes. The results are shown in Tables 4 to 6 below.

(Odor test evaluation criteria)
：: Almost no odor was observed.
Δ: Slight odor was observed.
X: An unpleasant odor was recognized.
If the odor test evaluation is ○ or Δ, the odor is low, and the odor is evaluated to be low even during high-speed printing.

[Summary]
From Tables 4 to 6, from the fact that a gas whose oxygen partial pressure is in the above range and a container whose appearance does not change within the range of the oxygen partial pressure, a specific solvent and a binder resin are contained. Even when the ink-jet ink is sealed in a container having an internal pressure of 0.8 atm or more and having a change in appearance in a sealed state, the above-mentioned ink package is to be less deformed even during long-term storage. I was able to confirm that I could do it.
In addition, it was confirmed that the pigment easily changed in appearance in the order of pigment 1 (cyan pigment), pigment 4 (black pigment), pigment 3 (magenta pigment), and pigment 2 (yellow pigment). .

DESCRIPTION OF SYMBOLS 1 ... Container 1a ... Void part 2 ... Ink jet ink 3 ... Gas 4 ... Lid 5 ... Seal member 10 ... Ink package

Claims (6)

A container,
An inkjet ink and gas sealed in the container,
An ink package comprising:
The inkjet ink has a polyalkylene glycol alkyl ether-based solvent, an acrylic resin (A), and a structural unit represented by the following general formula (I) and a structural unit represented by the following general formula (II). A binder resin containing at least one of the polymer (B),
The oxygen partial pressure of the gas is less than 0.2 atm;
The container has a change in appearance when the internal pressure in a sealed state is 0.8 atm or more, and has no change in appearance due to the reduced pressure of the oxygen partial pressure,
An ink package, wherein a maximum internal pressure at which an appearance of the container causes a change is 0.8 atm or more and less than an internal pressure after reducing the oxygen partial pressure.

(In the general formulas (I) and (II), R ¹ and R ² each independently represent a hydrogen atom or a methyl group, R ³ represents an alkyl group having 1 to 3 carbon atoms, and X represents Represents a halogen atom.)   The ink package according to claim 1, wherein the gas includes an inert gas.   3. The ink package according to claim 1, wherein the content of the polyalkylene glycol alkyl ether-based solvent is 50 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the inkjet ink. 4.   4. The container according to claim 1, wherein the container is an inner surface-coated metal container having a metal container and a resin layer that covers an inner surface of the metal container, or a resin container. 5. 3. The ink package according to claim 1. A method for producing an ink package according to any one of claims 1 to 4, wherein
An ink filling step of filling the inkjet ink so as to provide a void in the container,
Filling the container with an inert gas, and replacing the inside of the container with the gas having an oxygen partial pressure of less than 0.2 atm,
A method for producing an ink package, comprising:   6. The method for manufacturing an ink package according to claim 5, further comprising an inspection step of inspecting that the oxygen partial pressure of the gas is less than 0.2 atm during the replacement step or after the completion of the replacement step. .

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