KR20000048203A - Water based ink - Google Patents

Abstract

PURPOSE: A water based ink employing a pigment as a coloring agent is provided. CONSTITUTION: A water based ink can achieve high water resistance, high color fastness to light and high color density, and cause little bluing, and in conjunction therewith, can achieve satisfactory ejection stability. The water based ink composition is composed of at least water, pigment as coloring agent, an organic solvent, a surface active agent and at least one kind of compound expressed by the formula(1)

Description

Water Based Ink

The present invention relates to an aqueous ink. More specifically, the present invention relates to an aqueous ink for an ink jet printing apparatus. More specifically, the present invention relates to an aqueous ink using a pigment as a colorant.

Inkjet printers (IJP) have rapidly spread as general-purpose printers due to the fact that processes such as development and fixing are not necessary, and color printing is easy. In particular, in recent years, an increase in printing density and speed of an inkjet printer have been progressed very rapidly. In addition, color printers that can print on plain paper are also available. In such a situation, there is an increasing demand for IJ ink, which is a printing liquid for an ink jet printer, and therefore, ink having better performance is required.

In general, IJ ink is classified into a dye-based ink using an aqueous dye as a colorant and a pigment-based ink using a pigment as a colorant. Currently, most inkjet printers use dye inks. Dye ink suffers from a lack of light resistance and water resistance of the printed image.

That is, in the case of the dye ink, the dye used as the colorant has a property of low light resistance. Therefore, the image printed with such dye ink inevitably lacks light resistance. On the other hand, dye inks usually use a high water solubility in order to prevent clogging during ejection. As a result, the image printed with the dye ink does not have sufficient water resistance. When a print comes in contact with water, it inevitably decolorizes and causes a significant color change. Therefore, in the case of dye inks, it has become an important task to develop a dye that satisfies three conditions of color tone, water resistance and light resistance. However, such materials have not been developed yet.

In recent years, pigment inks have been proposed as inks having high light resistance and water resistance. Examples of pigment inks for IJP are disclosed in Japanese Patent Laid-Open Nos. Hei 2-255875 and Hei 4-18462. By using the pigment ink as the printing liquid for IJP, it is possible to obtain a high quality image having high water resistance, light resistance and color density all with little bleeding.

On the one hand, however, the pigment ink has a disadvantage that it causes clogging of the head nozzle and worsens the ejection stability. As one method of preventing clogging of the pigment ink in the head nozzle, there is an example in which a pigment and a dispersant are blended as disclosed in Japanese Patent Laid-Open No. 4-189876. However, in this method, since the water-soluble resin is used as a dispersant, the viscosity of the ink may be high, causing solidification at the ejection nozzle portion, thereby causing ejection failure.

The present invention has been derived in view of the above problems. Accordingly, one object of the present invention is to provide an aqueous ink which can achieve high water resistance, light resistance and high color density and together achieve satisfactory ejection stability with little bleeding.

It is another object of the present invention to provide an aqueous ink capable of achieving high ejection stability while using a pigment as a colorant.

According to one aspect of the invention, there is provided an aqueous ink composition composed of at least water, a pigment which is a colorant, an organic solvent, a surfactant and at least one compound represented by the following formula (1).

<Formula 1>

Preferably, m and n in formula 1 are integers and the value of m + n is 1 to 30. In addition, the compound represented by Formula 1 may be contained in the aqueous ink composition in the range of 0.01 to 1.0% by weight. The pigment may be contained in the range of 0.1 to 25% by weight based on the composition.

Preferably, the organic solvent is a water soluble organic solvent and is contained in the aqueous ink composition in the range of 5 to 50% by weight. The organic solvent may comprise at least one organic compound selected from diethylene glycol, propylene glycol, polyethylene glycol, glycerin, triethylene glycol monobutyl ether and diethylene glycol monobutyl ether.

The static surface tension of the aqueous ink composition may range from 20 to 50 dyne / cm, pH value from 6.5 to 10, and viscosity from 1 to 10 cps.

According to another aspect of the invention, there is provided an aqueous ink composition comprising at least water, a pigment, at least one compound represented by the following formula (2) and at least one alkylene oxide polymer represented by the following formula (3).

Wherein R ₁ and R ₃ are branched alkyl groups having 4 to 17 carbon atoms, R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms, and m and n are zero or positive integers.

In formula, m1 and n1 are 0 or a positive integer, R is chosen from H, a C1-C10 alkyl group, and a C1-C10 alkoxy group.

The acetylene glycol-based compound represented by the formula (2) is preferably at least one acetylene glycol-based compound represented by the following formula (4).

Wherein m and n are zero or a positive integer.

The acetylene glycol-based compound and the alkylene oxide polymer may be contained in the aqueous ink composition in a ratio of 0.01 to 10: 0.01 to 5 by weight. The acetylene glycol compound and the pigment may be contained in the aqueous ink composition in a ratio of 0.01 to 10: 0.1 to 25 by weight. The aqueous ink composition may further contain an organic solvent. The acetylene glycol compound and the organic solvent may be contained in the aqueous ink composition in a ratio of 0.01 to 10: 5 to 50 by weight.

In Formulas 2 and 4, m + n is usually 1 to 30, and m1 and n1 of Formula 3 may each be a positive integer. The compound represented by Formula 2 may be contained in the range of 0.01 to 10.0% by weight based on the total amount of the aqueous ink composition. The compound represented by the formula (3) may be contained in the range of 0.01 to 5.0% by weight relative to the total amount of the aqueous ink composition. The pigment may be contained in the range of 0.1 to 25% by weight relative to the total amount of the aqueous ink composition.

The organic solvent may be contained in the range of 5 to 50% by weight relative to the total amount of the aqueous ink composition. It is preferable that an organic solvent is a water-soluble organic solvent. The organic solvent may comprise one or more organic compounds selected from diethylene glycol, propylene glycol, polyethylene glycol, glycerin, triethylene glycol monobutyl ether and diethylene glycol monobutyl ether.

The physical properties of the aqueous ink composition may have a static surface tension in the range of 20 to 50 dyne / cm, a pH value of 6.5 to 10, and a viscosity of 1 to 10 cps at 20 ° C.

Hereinafter, the present invention will be described in detail through preferred embodiments. In the following description, numerous details are set forth in order to provide a thorough understanding of the present invention, but those skilled in the art will clearly recognize that the present invention may be practiced without these details. On the other hand, well-known structures are not described in detail in order to avoid unnecessary difficulty.

Embodiment 1

The first embodiment of the aqueous ink according to the invention consists of water, pigments which are colorants, organic solvents and compounds of the invention. The aqueous ink contains at least one acetylene glycol compound represented by the following general formula (1) in the composition.

<Formula 1>

In the formula, m and n are integers.

As an acetylene glycol compound represented by the said Formula (1) which has an acetylene bond in a center structure, the compound represented by following formula (5) is mentioned, for example.

In consideration of the solubility of the ink, the compound is preferably an ethylene oxide adduct of acetylene glycol, such as represented by the following formula (6).

In the formula, m1 and n1 are integers of 1 or more.

Compounds of the kind represented by the formula (6) is an acetylene glycol compound represented by the formula (1) wherein m and n is an integer of 1 or more, the molecular weight is 30 or more and has an acetylene bond to the central structure and ethylene oxide is added It is not specifically limited. Examples of this kind of compound include acetylene glycols represented by the following formulas (7) and (8).

In consideration of the solubility of the ink, the acetylene glycol compound preferably has a value of m + n of 1 to 30.

In this embodiment, the amount of the acetylene glycol compound represented by Formula 1 to the aqueous ink composition is preferably in the range of 0.01 to 1.0% by weight of the composition. When the acetylene glycol compound represented by the formula (1) is used in the aqueous ink at less than 0.01% by weight, the effect of improving the pigment dispersibility, the ejection stability of the ink, and the ink storage stability becomes insufficient. On the other hand, when the acetylene glycol compound is used in excess of 1.0% by weight, the acetylene glycol compound may not be completely dissolved in the ink, which may cause a significant increase in viscosity due to undissolved matter. Therefore, the addition amount outside the above range is not preferable.

On the other hand, the aqueous ink containing the acetylene glycol compound represented by the formula (1) presented in this embodiment uses a pigment as a colorant. By using the pigment as a colorant of the ink, it is possible to obtain a high quality image having excellent water resistance and light resistance and little blurring. Examples of the pigment used in this embodiment include acidic pigments and basic pigments. For example, carbon black 7, titanium black, blue pigment 15, 22, 60, 64, red pigment 9, 97, 122, 123, 149, 169, 177, yellow pigment 20, 24, 86, 93, 109, 110, 148 , 153, and so on. However, it is not limited to the said specific pigment.

The amount of the colorant added in the aqueous ink of the present embodiment is preferably in the range of 0.5 to 25% by weight. If the coloring agent is added in excess of 25% by weight, the dispersibility of the pigment in water may decrease, which may cause clogging at the discharge portion of the print head. On the other hand, when the added amount of the colorant is less than 0.5% by weight, sufficient image density cannot be obtained.

The aqueous ink of this embodiment contains a mixed solvent which is a mixture of water and an organic solvent which is an aqueous medium. As the water used in the mixed solvent, ion exchange water is preferable in view of storage stability of the ink, but commercially available distilled water can also be used.

On the other hand, as the organic solvent, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 600, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol Monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, glycerin, triethanol Amine, formamide, dimethyl formamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, 1,3-dimethyl imidazolidine and the like can be used. However, organic solvents that can be used are not limited to those described above. The amount of the organic solvent added is preferably 50% by weight or less. If more than 50% by weight of organic solvent is added to the ink, high quality printed images cannot be obtained.

On the other hand, the aqueous ink of the present embodiment can be produced by mixing the aqueous resin with the dispersion aid of the pigment. As aqueous resin, the compound whose weight average molecular weight is 50000 or less is preferable. For example, a styrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a styrene-methacrylic acid copolymer, a styrene modified resin, a cellulose derivative, an acrylic modified resin and the like can be selected. However, the aqueous resin is not limited to the above.

In addition, a well-known additive can be mixed with the aqueous ink of this embodiment. For example, potassium carbonate, sodium carbonate, triethanolamine, etc. can be mixed as a pH adjuster. Moreover, sodium benzoate etc. can be mixed as an antifungal agent. As the chelating agent, diethylene triamine pentate sodium acetate or the like can be mixed. Additives that can be mixed into the aqueous ink of this embodiment are not limited to those described above.

The static surface tension of the aqueous ink of this embodiment is preferably in the range of 20 to 50 dyne / cm. In this embodiment, the static surface tension is the surface tension when the liquid level is stopped. The static surface tension value can be measured by the plate hanging method or the like. If the static surface tension is 50 dyne / cm or more or 20 dyne / cm or less, permeability and dryness of the ink may be deteriorated, and thus the quality of the printed image may be degraded.

In addition, the aqueous ink of the present embodiment preferably has a contact angle (static contact angle) of 30 ° or less after 30 seconds after the ink reaches the head member of the inkjet printing apparatus. The static contact angle can be measured by the droplet method (1 / 2θ). On the other hand, the contact angle 30 seconds after reaching indicates the contact angle between the ink and the measuring substrate 30 seconds after the ink reaches the measuring substrate. The head member represents the entire member forming the printhead of the inkjet printing apparatus, such as a Ni plate, SuS 304 plate, or the like. However, the head member is not limited to the above. Ink having a contact angle of more than 10 ° 30 seconds after reaching the head member has poor wettability to the ink passage of the print head, so as to suck bubbles and the like in the ink passage, thereby significantly lowering the discharge stability.

In addition, the aqueous ink of the present embodiment preferably has a contact angle (dynamic contact angle) of 30 ° or less after 0.1 seconds after the ink reaches the head member of the inkjet printing apparatus. The dynamic contact angle can be measured by the droplet method (1 / 2θ). On the other hand, the contact angle 0.1 seconds after reaching indicates the contact angle between the ink and the measuring substrate after 0.1 seconds after the ink reaches the measuring substrate. The head member represents the entire member forming the print head of the inkjet printing apparatus, such as a Ni plate, SuS 304 plate, or the like. However, the head member is not limited to the above. Ink having a contact angle of more than 30 DEG after 0.1 second after reaching the head member has poor wettability to the ink passage of the print head, so as to suck bubbles and the like in the ink passage, thereby significantly lowering the discharge stability.

The viscosity of the aqueous ink of this embodiment is preferably adjusted within the range of 1 to 10 cps. In the case of an aqueous ink having a viscosity of 10 cps or more, the ink ejection stability of the print head is lowered, and a high quality printed image cannot be obtained. Even when the viscosity of the aqueous ink is 1 cps or less, the ink ejection stability of the print head is lowered, and a high quality printed image cannot be obtained.

The aqueous ink of this embodiment preferably adjusts the pH value in the range of 6 to 10. By adjusting the pH value of the aqueous ink within the range of 6 to 10, long-term storage stability can be improved, and variations in physical properties such as surface tension and viscosity can be suppressed to obtain a high quality printed image.

The aqueous ink of this embodiment can be applied to an inkjet printing apparatus which performs printing by ejecting ink droplets. Here, the inkjet printing apparatus includes at least an inkjet printhead having a nozzle ejecting portion for ejecting ink droplets onto a paper which is a printing medium, an ink container containing the aqueous ink of the present embodiment described above, and an aqueous container from the ink container to the printhead. It is composed of ink supply means for supplying. However, the use of the aqueous ink of this embodiment varies. Therefore, the use of the aqueous ink of this embodiment is not limited to the inkjet printing apparatus.

Hereinafter, embodiments of the present invention will be described in more detail. It should be noted that the examples which follow are merely to aid in a clear understanding of the invention and should not be regarded as limiting the invention.

An aqueous ink was prepared according to the blending ratio of each example. Each component of each aqueous ink was mixed in a beaker and then filtered through an omnipoa JA type membrane filter to prepare the aqueous ink to be tested. Then, the static surface tension, viscosity, and pH value of the aqueous ink thus prepared were measured. Static surface tension was measured at the measurement temperature of 20 degreeC using the Wilhelmian surface tension meter (Japan Kyowa Kaimen Kagaku Co., Ltd., automatic surface tension meter CBVP-A3). The viscosity was measured at the measurement temperature of 20 degreeC using the automatic viscometer DVM-E2 (Doxmek Co., Ltd.). The pH value was measured at the measurement temperature of 20 degreeC using the personal pH meter pH81 (Yokogawa Denki Co., Ltd.).

<Example 1>

Compounding cost

Ink composition 1

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene Glycol Compound 10.05 parts

The acetylene glycol compound 1 is represented by the following formula (5).

<Formula 5>

The ink composition of Example 1 exhibited a characteristic that the static surface tension γ was 36.6 dyne / cm, the viscosity η was 4.1 cps, and the pH value was 7.56.

<Example 2>

Compounding cost

Ink composition 2

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene glycol compound 10.1part

The ink composition of Example 2 exhibited a characteristic that the static surface tension γ was 34.2 dyne / cm, the viscosity η was 4.1 cps, and the pH value was 7.58.

<Example 3>

Compounding cost

Ink composition 3

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene glycol compound 10.2part

The ink composition of Example 3 exhibited a characteristic that the static surface tension γ was 32.7 dyne / cm, the viscosity η was 4.3 cps, and the pH value was 7.44.

<Example 4>

Compounding cost

Ink composition 4

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene Glycol Compound 20.05 parts

The acetylene glycol compound 2 is represented by the following formula (1) wherein m + n = 10.

<Formula 1>

The ink composition of Example 4 exhibited the characteristics that the static surface tension γ was 37.6 dyne / cm, the viscosity η was 4.7 cps, and the pH value was 8.31.

Example 5

Compounding cost

Ink composition 5

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene glycol compound 2 0.1 parts

The ink composition of Example 5 exhibited a characteristic that the static surface tension γ was 34.2 dyne / cm, the viscosity η was 4.7 cps, and the pH value was 8.33.

<Example 6>

Compounding cost

Ink composition 6

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene Glycol Compound 20.2Parts

The ink composition of Example 6 exhibited a characteristic that the static surface tension γ was 32.2 dyne / cm, the viscosity η was 4.7 cps, and the pH value was 8.36.

<Example 7>

Compounding cost

Ink composition 7

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene glycol compound 3 0.01 parts

The acetylene glycol compound 3 is represented by the following formula (1) wherein m + n = 30.

<Formula 1>

The ink composition of Example 7 exhibited the characteristics that the static surface tension γ was 34.3 dyne / cm, the viscosity eta was 4.8 cps and the pH value was 8.22.

<Example 8>

Compounding cost

Ink composition 8

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene Glycol Compound 30.1part

The ink composition of Example 8 exhibited the characteristics that the static surface tension γ was 31.6 dyne / cm, the viscosity eta was 4.9 cps and the pH value was 8.01.

Example 9

Compounding cost

Ink composition 9

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

Acetylene glycol compound 30.2part

The ink composition of Example 9 exhibited a characteristic that the static surface tension γ was 27.1 dyne / cm, the viscosity eta was 4.9 cps and the pH value was 7.68.

A comparative example is then presented.

Comparative Example 1

An aqueous ink of the following composition from which the surface active agent was removed was prepared as Comparative Example 1. Each component of the aqueous ink was mixed in a beaker and then filtered through an omnipoa JA type membrane filter to prepare the aqueous ink to be tested. Then, the static surface tension, viscosity, and pH value of the aqueous ink thus prepared were measured by the method used for the measurement of the examples.

Compounding cost

Ink composition 10

Carbon black 10 parts

70 parts water

Dispersant (Emulgen A-90) 5 parts

Glycerin, 10 parts

The ink composition of Comparative Example 1 exhibited the characteristics that the static surface tension γ was 45.7 dyne / cm, the viscosity η was 4.6 cps and the pH value was 9.21.

Comparative Example 2

To the ink composition of Comparative Example 1 was added 0.2% by weight of acetylene glycol compound 4 represented by the following formula (9).

The ink composition of Comparative Example 2 exhibited the characteristics that the static surface tension γ was 35.4 dyne / cm, the viscosity η was 4.4 cps, and the pH value was 8.66.

Comparative Example 3

Surface tension in a similar manner to Comparative Example 1 was used as Comparative Example 3, in which the ink composition of 0.2 wt% of the acetylene glycol compound 5 represented by the following Chemical Formula 10 having m + n = 4 was added to the ink composition of Comparative Example 1. , Viscosity and pH values were measured.

The ink composition of Comparative Example 3 exhibited the characteristics that the static surface tension γ was 36.8 dyne / cm, the viscosity η was 4.7 cps, and the pH value was 7.84.

Comparative Example 4

Surface tension in a similar manner to Comparative Example 1 was used as Comparative Example 4, wherein the ink composition of 0.2 wt% of the acetylene glycol compound 6 represented by the following Chemical Formula 10 having m + n = 10 was added to the ink composition of Comparative Example 1. , Viscosity and pH values were measured.

<Formula 10>

The ink composition of Comparative Example 4 exhibited the characteristics that the static surface tension γ was 32.3 dyne / cm, the viscosity η was 5.0 cps, and the pH value was 7.91.

Comparative Example 5

A surface tension and a viscosity in a method similar to Comparative Example 1 were used as Comparative Example 5, in which an ink composition having 0.2% by weight of Compound 7 represented by Formula 11 having m + n> 30 was added to the ink composition of Comparative Example 1 And pH values were measured.

The ink composition of Comparative Example 5 exhibited the characteristics that the static surface tension γ was 30.9 dyne / cm, the viscosity η was 5.3 cps, and the pH value was 8.96.

Below, the evaluation result is demonstrated.

<Evaluation Criteria 1>

The contact angle 30 seconds after reaching the SUS 304 plate was measured as the static contact angle. On the other hand, a SUS plate (surface roughness ∇∇∇∇) was used as a measurement substrate. The measurement temperature was 20 ° C.

<Evaluation Criteria 2>

The contact angle 0.1 seconds after reaching the SUS 304 plate was measured as a dynamic contact angle. On the other hand, a SUS plate (surface roughness ∇∇∇∇) was used as a measurement substrate. The measurement temperature was 20 degreeC.

<Evaluation Criteria 3>

The dryness was tested by performing a printing test using a piezo-type inkjet printer having a resolution of 720 dpi and examining the drying time of the printed sample. Commercially available recycled paper was used as the printing paper. When the drying time was 10 seconds or less, the evaluation result was regarded as good (○), otherwise it was regarded as poor (X).

<Evaluation Criteria 4>

The discharge stability was investigated by printing 100 sheets of A4 paper. The evaluation result was good ((circle)) when all the printed images of 100 sheets were favorable, and it was set as bad (X) otherwise.

<Evaluation Criteria 5>

The storage stability of the aqueous ink composition was investigated by the following method. That is, the aqueous ink was stored in a polyethylene container at 60 ° C. for one month to investigate surface tension, change in viscosity and pH value, and presence or absence of a precipitate. When physical properties hardly changed and no precipitate was observed, the evaluation result was made into good ((circle)), otherwise it was set as bad (X).

<Evaluation result>

The evaluation results of each example and the comparative example are shown in Table 1 below.

Static contact angle Dynamic contact angle Dryness Discharge stability Storage stability Example 1 16.6 31.1 ○ ○ △ Example 2 8.7 27.4 ○ ○ ○ Example 3 6.2 27.1 ○ ○ ○ Example 4 19.1 24.0 ○ △ ○ Example 5 8.7 19.4 ○ ○ ○ Example 6 <5.0 9.9 ○ ○ ○ Example 7 28.3 31.4 △ △ △ Example 8 25.4 28.1 ○ ○ ○ Example 9 20.6 28.1 ○ ○ ○ Comparative Example 1 37.1 45.6 X X X Comparative Example 2 13.4 29.1 X △ △ Comparative Example 3 11.8 30.9 △ △ △ Comparative Example 4 14.7 34.3 △ △ △ Comparative Example 5 37.1 44.6 X X X

As described above, according to the aqueous ink of the present embodiment, high ejection stability could be achieved while using the pigment as the colorant.

On the other hand, according to the water-based ink according to the present invention, it is possible to realize high print quality which is excellent in water resistance and light resistance and does not bleed on paper.

Moreover, the aqueous inks of the present invention exhibited excellent storage stability.

Embodiment 2

<Water-based ink>

A second embodiment of the aqueous ink contains at least one acetylene glycol-based compound represented by formula (2) and at least one alkylene oxide polymer represented by formula (3).

<Formula 2>

Wherein R ₁ and R ₃ are branched alkyl groups having 4 to 17 carbon atoms, R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms, and m and n are zero or positive integers.

<Formula 3>

In formula, m1 and n1 are 0 or a positive integer, R is chosen from H, a C1-C10 alkyl group, and a C1-C10 alkoxy group.

In a preferred composition, the aqueous ink of the second embodiment contains an acetylene glycol-based compound and an alkylene oxide polymer in a weight ratio of 0.01 to 10: 0.01 to 5.

The aqueous ink of this embodiment contains a pigment as a colorant. Preferably, the aqueous ink contains an acetylene glycol compound and a pigment in a weight ratio of 0.01 to 10.0: 0.1 to 25.

On the other hand, the aqueous ink of this embodiment may contain one or more organic solvents. Preferably, the aqueous ink contains an acetylene glycol compound and an organic solvent in a weight ratio of 0.01 to 10: 5 to 50. In addition, the aqueous ink of the present embodiment contains water. The weight ratio of the acetylene glycol compound and water is 0.01 to 10:10 to 94.88.

<Acetylene Glycol Compounds Represented by Formula 2>

As described above, in formula (2), R ₁ and R ₃ are branched alkyl groups having 4 to 17 carbon atoms in which carbon atoms are bonded to have one or more branches. Preferably, the branched alkyl group may have a backbone of carbon atoms bonded so as not to have a branch, to which an alkyl group may be bonded to form one or more branches.

More preferably, R ₁ and R ₃ of Chemical Formula 2 are alkyl groups having branched chains by having an alkyl group having 1 to 10 carbon atoms (more preferably, 1 to 5 carbon atoms) bonded to a main chain having 3 to 7 carbon atoms having no branching. to be. The position of the main chain carbon atom to which the alkyl group is bonded may be selected as the position farthest from the triple bond portion of the carbon in the above formula (2) provided that branching occurs. The alkyl group bonded to the main chain may be a branched alkyl group or a branched alkyl group. In Formula 2, the alkyl groups of R ₁ and R ₃ may be the same alkyl group.

R ₂ and R ₄ in the formula (2) is an alkyl group having 1 to 10, more preferably 1 to 5 carbon atoms. This alkyl group may be a branched alkyl group or a branched alkyl group. In Formula 2, the alkyl groups of R ₂ and R ₄ may be the same alkyl group.

The acetylene glycol compound represented by Formula 2 may be a compound represented by Formula 4 below.

<Formula 4>

Wherein m and n are zero or a positive integer.

Alternatively, the acetylene glycol-based compound represented by Formula 2 may be a compound represented by the following Formula 5.

<Formula 5>

In consideration of the solubility of the ink, the acetylene glycol-based compound may be preferably an ethylene oxide adduct of acetylene glycol represented by the following formula (12).

In formula, m 'and n' are an integer of 1 or more.

The ethylene oxide adduct of acetylene glycol represented by the above formula (12) is not particularly limited as long as it is an acetylene glycol compound represented by the above formula (4) having a molecular weight of 30 or more, an acetylene bond in the center, and ethylene oxide added. For example, all acetylene glycol compound groups represented by the following formulas are possible.

Among the acetylene glycol compounds represented by the above formulas (2) and (4), an acetylene glycol compound having m + n of 1 to 30 is preferable in view of water resistance of the ink and dryness of the surface of the printing paper.

The amount of the acetylene glycol compound represented by Formula 2 to the aqueous ink composition is preferably 0.01 to 10.0 wt% based on the total amount of the aqueous ink composition. When the amount of the acetylene glycol compound represented by Formula 2 in the aqueous ink is less than 0.01% by weight, the effect of improving the ink discharge stability is insufficient. On the other hand, when the addition amount of the acetylene glycol compound represented by the formula (2) to the aqueous ink composition exceeds 10.0% by weight, the viscosity of the ink is significantly increased may cause poor discharge.

<Alkylene oxide polymer represented by Formula 3>

Usually, the water solubility of the acetylene glycol compound represented by the said Formula (2) is low. For example, when the acetylene glycol compound represented by the formula (2) is added to an aqueous ink containing about 70% by weight of water, the solubility limit is about 0.5% by weight.

When the acetylene glycol compound of formula (2) is added to an aqueous ink under environmental conditions with low solubility limits, the acetylene glycol compound of formula (2) may precipitate as an insoluble component in the ink and cause poor discharge. Therefore, it is necessary to improve the solubility of the acetylene glycol compound of formula (2) in the aqueous ink. Therefore, this embodiment uses the compound of formula 3 (alkylene oxide polymer) as a dissolution aid for dissolving the acetylene glycol compound of formula 2 in an aqueous ink.

By using the compound of formula 3 as a dissolution aid and adding the compound of formula 2 and the polymer of formula 3 together to the aqueous ink, the solubility of the compound of formula 2 can be significantly improved. In addition, in this embodiment, the compound of formula 3 is also used as a pigment dispersant. In general, in the case of pigment inks, the pigment particles are not dispersed in water, which is the main solvent, and may cause clogging upon ejection. In the case of the pigment ink containing the compound of the formula (3), excellent dispersibility of the pigment particles as a colorant is ensured storage stability and there is no clogging during discharge to achieve a high discharge stability.

The compound of formula 3 need not be specified as long as it is one of ethylene oxide polymer, propylene oxide polymer and ethylene oxide-propylene oxide copolymer. On the other hand, in the present embodiment, the amount of the polymer of Formula 3 added in the aqueous ink is preferably 0.01 to 5.0% by weight. When the addition amount of the polymer of the formula (3) is less than 0.01% by weight, there is a possibility that the effects as the pigment dispersant and the dissolution aid are insufficient. On the other hand, when the polymer of Formula 3 is added in excess of 5.0% by weight, the viscosity of the aqueous ink may increase significantly.

<Pigment>

In the aqueous ink of this embodiment, the colorant is a pigment. When using a pigment as a colorant of an ink, the light resistance and water resistance of the printed image can be improved as intended in the present invention. Pigments that can be used in this embodiment include acidic pigments, basic pigments and the like. For example, carbon black 7, titanium black, blue pigment 15, 22, 60, 64, red pigment 9, 97, 122, 123, 149, 169, 177, yellow pigment 20, 24, 86, 93, 109, 110 , 148, 153 and the like. However, the pigment is not limited to the above.

It is preferable that the addition amount of a coloring agent in the aqueous ink of this embodiment is 1-25 weight%. When the coloring agent is added in excess of 25% by weight, there is a possibility that the dispersibility of the pigment in water deteriorates and clogging occurs at the discharge portion of the print head. On the other hand, when the addition amount of the coloring agent is less than 0.5% by weight, it is impossible to obtain sufficient image density.

<Aqueous medium>

In the aqueous ink of the present embodiment, a mixed solvent composed of a combination of water and an organic solvent is used as the aqueous medium. As water used for the mixed solvent, ion-exchanged water is preferable in view of storage stability of the ink. However, commercially available distilled water can also be used.

<Organic solvent>

Organic solvents include ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol MW (weight average molecular weight) 200, polyethylene glycol MW300, polyethylene glycol MW600, ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, ethylene glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether , Glycerin, triethanol amine, formamide, dimethyl formamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, 1,3-dimethyl imidazolidine and the like can be used. However, the organic solvent used is not limited to the above-mentioned solvents.

The organic solvent is used as a penetrant. As for the addition amount of an organic solvent, 50 weight% or less is preferable. Inks containing an organic solvent in an amount of more than 50% by weight are difficult to obtain a high quality printed image, which causes clogging of the ink during discharge or cause of poor discharge.

<Additive>

In this embodiment, an aqueous ink is prepared by mixing an aqueous resin with a dispersant of a pigment. As the aqueous resin, a compound having a molecular weight of 50,000 or less is preferable. For example, a styrene-acrylic acid copolymer, a styrene-maleic acid copolymer, a styrene-methacrylic acid copolymer, a styrene modified resin, a cellulose derivative, an acrylic modified resin and the like can be selected. However, the aqueous resin is not limited to those described above.

In addition, the aqueous ink of this embodiment can be manufactured by mixing a well-known additive. For example, potassium carbonate, sodium carbonate, triethanolamine, etc. can be mixed as a pH adjuster. Moreover, sodium benzoate etc. can be mixed as an antifungal agent. Moreover, sodium diethylene triamine pentaacetate is mentioned as a chelating agent. The additives that can be mixed with the aqueous ink of the present embodiment are not limited to the additives described above.

<Characteristics of Water-based Inks>

On the other hand, the static surface tension of the aqueous ink of the present embodiment is preferably in the range of 20 to 50 dyne / cm at 20 ℃. In this embodiment, the static surface tension is the surface tension when the liquid level is at rest. The static surface tension value can be measured by the Wilhelmian method. When the static surface tension value is larger than 50 dyne / cm or smaller than 20 dyne / cm, the permeability and drying property of the ink onto the printing surface tend to be worse.

In addition, the aqueous ink of the present embodiment preferably has a contact angle (static contact angle) of 30 ° or less after 30 seconds after the ink reaches the head member of the inkjet printing apparatus. The static contact angle can be measured by the droplet method (1 / 2θ). On the other hand, the contact angle 30 seconds after reaching indicates the contact angle between the ink and the measuring substrate 30 seconds after the ink reaches the measuring substrate. Incidentally, the head member denotes all members forming the print head of the inkjet printing apparatus, for example, Ni plate, SuS 304 plate, and the like. However, the head member is not limited to the aforementioned members. Ink having a contact angle of more than 10 ° after 30 seconds after the ink reaches the head member has poor wettability when passing through the print head, so as to suck bubbles and the like in the ink passage, and the discharge stability is significantly worsened.

In addition, the aqueous ink of the present embodiment preferably has a contact angle (dynamic contact angle) of 30 ° or less after 0.1 seconds after the ink reaches the head member of the inkjet printing apparatus. The dynamic contact angle can be measured by the droplet method (1 / 2θ). On the other hand, the contact angle after 0.1 second has elapsed represents the contact angle between the ink and the measurement substrate after 0.1 second has elapsed since the ink reached the measurement substrate. On the other hand, the head member represents all the members forming the print head of the inkjet printing apparatus, for example, Ni plate, SuS 304 plate and the like. However, the head member is not limited to the aforementioned members. Ink having a contact angle of more than 30 ° after 0.1 seconds since the ink reaches the head member has poor wettability when passing through the print head, so as to suck bubbles and the like in the ink passage, and the discharge stability is significantly worsened.

On the other hand, it is preferable to adjust the viscosity of the aqueous ink of this embodiment in the range of 1-10 cps at 20 degreeC. In the case of an aqueous ink having a viscosity of 10 cps or more, the ink ejection stability of the print head is deteriorated, making it impossible to obtain a high quality print image. Even if the viscosity of the aqueous ink is 1 cps or less, the ink ejection stability of the print head is deteriorated and a high quality print image cannot be obtained.

The aqueous ink of this embodiment preferably adjusts the pH value within the range of 6.5 to 10. When the pH value of the aqueous ink is adjusted within the range of 6.5 to 10, long-term storage stability is improved, variations in physical properties such as surface tension and viscosity are suppressed, and a high quality printed image can be obtained.

<Ink container>

The ink storage container of the aqueous ink of this embodiment has an ink storage chamber for containing ink. At least the portion of the ink compartment in direct contact with the ink should be formed of a material that is inert to the aqueous ink composition. The material inert to the aqueous ink composition of this embodiment should not be dissolved by the aqueous ink of this embodiment during storage of the ink in the material and should not adversely affect the aqueous ink of this embodiment such as alteration. Therefore, the material of the ink compartment should be selected from resins, metals, ceramics, and the like which are inert to the aqueous ink of the present embodiment.

<Inkjet Printing Device>

The aqueous ink of the present embodiment can be used in an inkjet printing apparatus for ejecting and printing ink droplets. In the present specification, an ink jet printing apparatus includes at least an ink jet print head having a nozzle ejecting portion for ejecting ink droplets to a print medium, a container containing the aqueous ink of the present embodiment described above, and supplying aqueous ink from the ink container to the print head. It consists of ink supply means. However, the aqueous ink of this embodiment may have various uses. Therefore, the use of the aqueous ink of this embodiment is not limited to the inkjet printing apparatus.

Examples of the present invention will be discussed in more detail below. It is apparent that the embodiments described hereinafter are only for a clear understanding of the present invention and do not limit the present invention.

Each example of the aqueous ink was prepared according to the blending ratio of each example. Each component of each aqueous ink was mixed in a beaker and then filtered through an omnipoa JP type membrane filter to prepare a test aqueous ink. Then, the static surface tension, viscosity, and pH value of the obtained aqueous ink were measured. Static surface tension was measured using a Wilhelmian surface tension meter (automatic surface tension meter CBVP-A3, manufactured by Nippon Kyowa Kamen Co., Ltd.). Viscosity was measured at the measurement temperature of 20 degreeC with the automatic viscosity measuring system DVM-E2 (made by Tokmek KK). The pH value was measured at a measurement temperature of 20 ° C. with a personal pH meter pH 81 (manufactured by Yokogawa Denki Co., Ltd.).

Example 21

Compounding cost

Ink composition 21

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 40.5Part

Ethylene Oxide Polymer (MW 5000) 0.02 parts

Acetylene glycol compound 4 may be represented by the following formula (5).

<Formula 5>

The ink composition of Example 21 has the properties of static surface tension γ = 27.6 dyne / cm, viscosity η = 4.6 cps and pH value = 8.11.

<Example 22>

Compounding cost

Ink composition 22

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 41.0part

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 22 has the properties of static surface tension γ = 26.4 dyne / cm, viscosity η = 4.8 cps and pH value = 8.24.

<Example 23>

Compounding cost

Ink composition 23

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 4 2.0part

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 23 has the properties of static surface tension γ = 25.8 dyne / cm, viscosity η = 4.9 cps and pH value = 8.01.

<Example 24>

Compounding cost

Ink composition 24

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 50.05part

Ethylene Oxide Polymer (MW 5000) 0.02 parts

Acetylene glycol compound 5 may be represented by the following formula (4) wherein m + n = 10.

<Formula 4>

The ink composition of Example 24 has the properties of static surface tension γ = 29.1 dyne / cm, viscosity η = 4.9 cps and pH value = 7.54.

<Example 25>

Compounding cost

Ink composition 25

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 5 1.0 Part

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 25 has the properties of static surface tension γ = 27.3 dyne / cm, viscosity η = 5.2 cps and pH value = 7.94.

Example 26

Compounding cost

Ink composition 26

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 5 2.0 parts

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 26 has the properties of static surface tension γ = 26.3 dyne / cm, viscosity η = 5.3 cps and pH value = 8.02.

Example 27

Compounding cost

Ink composition 27

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 5 2.0 parts

Propylene oxide polymer (MW 5000) 0.05 part

The ink composition of Example 27 has the properties of static surface tension γ = 24.9 dyne / cm, viscosity η = 5.6 cps and pH value = 7.87.

<Example 28>

Compounding cost

Ink composition 28

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 5 2.0 parts

Ethylene Oxide-Propylene Oxide

0.05 parts of copolymer (MW 10000)

The ink composition of Example 28 has the properties of static surface tension γ = 27.2 dyne / cm, viscosity η = 6.2 cps and pH value = 7.52.

<Example 29>

Compounding cost

Ink composition 29

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 60.5 Parts

Ethylene Oxide Polymer (MW 5000) 0.02 parts

Acetylene glycol compound 6 may be represented by the following formula (4) m + n = 30.

<Formula 4>

The ink composition of Example 29 has the properties of static surface tension γ = 26.1 dyne / cm, viscosity η = 5.4 cps and pH value = 8.31.

<Example 30>

Compounding cost

Ink composition 30

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 61.0part

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 30 has the properties of static surface tension γ = 25.8 dyne / cm, viscosity η = 5.5 cps and pH value = 8.11.

<Example 31>

Compounding cost

Ink composition 31

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

Acetylene Glycol Compound 6 2.0part

0.05 part of ethylene oxide polymer (MW 5000)

The ink composition of Example 31 has the properties of static surface tension γ = 24.9 dyne / cm, viscosity η = 5.6 cps and pH value = 8.22.

Comparative Example 21

An aqueous ink having the following composition except for the surfactant was prepared as Comparative Example 21. Each component of the aqueous ink was mixed in a beaker and then filtered through an omnipoa JA type membrane filter to prepare an aqueous ink for testing. Then, the static surface tension, viscosity, and pH value of the prepared aqueous ink were measured by the method used for the measurement performed in the examples.

Compounding cost

Ink composition 32

Carbon Black Part 10

75 parts water

Dispersant Part 5

Glycerin 10 parts

The ink composition of Comparative Example 21 has the characteristics of static surface tension γ = 45.7 dyne / cm, viscosity η = 4.6 cps and pH value = 9.21.

Comparative Example 22

0.2 wt% of acetylene glycol compound 4 was added to the ink composition of Comparative Example 21 to prepare an ink composition of Comparative Example 22, and the surface tension, viscosity, and pH were measured in a similar manner to Comparative Example 21.

The ink composition of Comparative Example 22 has the characteristics of static surface tension γ = 32.4 dyne / cm, viscosity η = 4.4 cps and pH value = 8.10.

Comparative Example 23

The ink composition of Comparative Example 23 was prepared by adding 2.0 wt% of acetylene glycol compound 4 to the ink composition of Comparative Example 21. In this ink composition, the dispersibility was low, and a large amount of insoluble substance was present. Therefore, the discharge test could not be performed.

Comparative Example 24

0.2 wt% of acetylene glycol compound 5 was added to the ink composition of Comparative Example 21 to prepare an ink composition of Comparative Example 24, and the surface tension, viscosity, and pH were measured in a similar manner to Comparative Example 21.

The ink composition of Comparative Example 24 has the characteristics of static surface tension γ = 36.8 dyne / cm, viscosity η = 4.7 cps and pH value = 7.84.

Comparative Example 25

The ink composition of Comparative Example 25 was prepared by adding 2.0% by weight of acetylene glycol compound 5 to the ink composition of Comparative Example 21. In this ink composition, the dispersibility was low, and a large amount of insoluble substance was present. Therefore, the discharge test could not be performed.

Comparative Example 26

0.2 wt% of acetylene glycol compound 6 was added to the ink composition of Comparative Example 21 to prepare an ink composition of Comparative Example 26, and the surface tension, viscosity, and pH were measured in a similar manner to Comparative Example 21.

The ink composition of Comparative Example 26 has the properties of static surface tension γ = 29.3 dyne / cm, viscosity η = 5.1 cps and pH value = 7.12.

Comparative Example 27

The ink composition of Comparative Example 27 was prepared by adding 2.0 wt% of acetylene glycol compound 6 to the ink composition of Comparative Example 21. In this ink composition, the dispersibility was low, and a large amount of insoluble substance was present. Therefore, the discharge test could not be performed.

Comparative Example 28

To the ink composition of Comparative Example 21 was added a compound of formula 11 with m + n> 30 in an amount of 0.2% by weight and the surface tension, viscosity and pH were measured in a similar manner as in Comparative Example 21 above.

<Formula 11>

The ink composition of Comparative Example 28 has the properties of static surface tension γ = 30.9 dyne / cm, viscosity η = 5.3 cps and pH value = 8.96.

<Evaluation Criteria 1>

The contact angle 30 seconds after the ink droplet reached the SUS 304 plate was measured. The measurement temperature was 20 ° C.

<Evaluation Criteria 2>

The contact angle after 0.1 second after the ink droplet reached the SUS304 plate was measured. The measurement temperature was 20 ° C.

<Evaluation Criteria 3>

A print test was conducted with a piezo-type inkjet printing machine having a resolution of 720 dpi to confirm the sharpness of the image. Commercially available recycled paper was used as the printing paper.

(1) smear test

The printed image was examined and evaluated as follows.

○: does not spread

△: slightly smeared

×: smeared

(2) drying test

The drying time of a printed image was evaluated as follows.

○: drying time of 10 seconds or less

△: drying time of 10 seconds to 20 seconds

×: drying time over 20 seconds

(3) water resistance test

The print sample was soaked in water for 30 seconds and then the change in image density was confirmed. Color concentration was measured with a colorimeter (L *, a *, b *) to determine the change rate ΔE of the color concentration.

△ E = √ ((A * -a *) ² + (B * -b *) ² + (C * -c *) ² )

○: ΔE is less than 5

△: ΔE is 5 or more but less than 10

×: ΔE is 10 or more

<Evaluation Criteria 4>

The discharge stability was confirmed by printing 100 sheets of A4 paper.

○: All print images are good

△: there is some defective image

X: Many defective images.

<Evaluation Criteria 5>

The storage stability of the aqueous ink composition was confirmed by the following method. That is, the aqueous ink was stored in a polyethylene container at 60 ° C. for 1 month to confirm the change in surface tension, viscosity and pH value and the presence of precipitates.

○: little change in physical properties and no precipitate was observed

(Triangle | delta): There exists a change of a physical property and some sediment is observed.

X: There was a change in physical properties and a large amount of precipitate was observed.

Table 2 below shows the results of evaluation of static contact angle, dynamic contact angle, smearing, drying time and water resistance in the above embodiments and comparative examples. Table 3 shows the evaluation results of the discharge stability and the storage stability.

Static contact angle Dynamic contact angle Smearing Drying time Water resistance Example 21 8.8 25.9 ○ ○ ○ Example 22 6.7 25.1 ○ ○ ○ Example 23 11.3 23.5 ○ ○ ○ Example 24 8.6 19.7 ○ ○ ○ Example 25 <5.0 18.4 ○ ○ ○ 26 to implementation <5.0 17.1 ○ ○ ○ Example 27 <5.0 17.9 ○ ○ ○ Example 28 <5.0 17.0 ○ ○ ○ Example 29 9.6 28.6 ○ ○ △ Example 30 7.7 25.5 ○ ○ △ Example 31 <5.0 22.6 ○ ○ △ Comparative Example 21 37.1 45.6 × × × Comparative Example 22 - - - - - Comparative Example 23 11.8 28.1 △ △ ○ Comparative Example 24 - - - - - Comparative Example 25 10.6 28.7 ○ △ △ Comparative Example 26 - - - - - Comparative Example 27 13.6 32.5 △ ○ △ Comparative Example 28 37.1 44.6 × △ ×

Discharge stability Storage stability Example 21 ○ ○ Example 22 ○ ○ Example 23 ○ ○ Example 24 ○ ○ Example 25 ○ ○ Example 26 ○ ○ Example 27 ○ ○ Example 28 ○ ○ Example 29 ○ ○ Example 30 ○ ○ Example 31 ○ ○ Comparative Example 21 × ○ Comparative Example 22 ○ × Comparative Example 23 - - Comparative Example 24 △ △ Comparative Example 25 - - Comparative Example 26 ○ × Comparative Example 27 - - Comparative Example 28 × ×

The following effects were achieved by the invention described above.

According to the aqueous ink of the first embodiment of the present invention, high ejection stability can be achieved while using the pigment as a colorant.

Further, according to the aqueous ink according to this embodiment, it was possible to realize high print quality which was excellent in water resistance and light resistance and without bleeding on paper. Moreover, the aqueous inks of the present invention exhibited excellent storage stability.

The first effect of the aqueous ink of the second embodiment of the present invention is that it is excellent in water resistance and light resistance, has high color density and little bleeding, and at the same time achieves excellent ejection stability.

This is because the aqueous ink of the present embodiment contains at least one acetylene glycol-based compound of formula (2), at least one alkylene oxide polymer of formula (3), a pigment and water.

The second effect of the aqueous ink of this embodiment is that the drying speed on the printing paper surface is high, the permeability or permeability is excellent, there is little offset and the storage property is excellent. The reason is also as described above.

While the invention has been described and described in terms of exemplary embodiments, it will be apparent to those skilled in the art that various changes, reductions, and additions can be made within or within the invention without departing from the spirit and scope of the invention. Accordingly, the invention is not limited to the specific embodiments described above, but is intended to include all possible embodiments that may be made within the scope and equivalents of the features described in the appended claims.

Claims (25)

An aqueous ink composition comprising at least water, a pigment which is a colorant, an organic solvent, a surfactant, and at least one compound represented by the following general formula (1). <Formula 1> In the formula, m and n are integers. The aqueous ink composition of claim 1, wherein m and n are integers and the value of m + n is 1-30. The aqueous ink composition of claim 1, wherein 0.01 to 1.0 wt% of the compound represented by Chemical Formula 1 is contained. The aqueous ink composition according to claim 1, wherein the pigment is contained in an amount of 0.1 to 25 wt% based on the composition. The aqueous ink composition of claim 1, wherein the organic solvent is a water soluble organic solvent and is contained in the composition in the range of 5 to 50% by weight. The aqueous ink composition of claim 1, wherein the organic solvent comprises at least one organic compound selected from diethylene glycol, propylene glycol, polyethylene glycol, glycerin, triethylene glycol monobutyl ether, and diethylene glycol monobutyl ether. The aqueous ink composition of claim 1, wherein the static surface tension is in the range of 20 to 50 dyne / cm. The aqueous ink composition of claim 1, wherein the pH value ranges from 6.5 to 10. The aqueous ink composition of claim 1, wherein the viscosity is in the range of 1 to 10 cps. An aqueous ink composition comprising at least water, a pigment, at least one compound represented by formula (2) and at least one alkylene oxide polymer represented by formula (3). <Formula 2> Wherein R ₁ and R ₃ are branched alkyl groups having 4 to 17 carbon atoms, R ₂ and R ₄ are alkyl groups having 1 to 10 carbon atoms, and m and n are zero or positive integers. <Formula 3> In formula, m1 and n1 are 0 or a positive integer, R is chosen from H, a C1-C10 alkyl group, and a C1-C10 alkoxy group. The aqueous ink composition according to claim 10, wherein the acetylene glycol compound represented by Formula 2 is at least one acetylene glycol compound represented by Formula 4 below. <Formula 4> Wherein m and n are zero or a positive integer. The aqueous ink composition according to claim 10, wherein the acetylene glycol compound and the alkylene oxide polymer are contained in the composition in a weight ratio of 0.01 to 10: 0.01 to 5. The aqueous ink composition according to claim 10, wherein the acetylene glycol compound and the pigment are contained in the composition in a weight ratio of 0.01 to 10: 0.1 to 25. The aqueous ink composition according to claim 10, further containing an organic solvent. The aqueous ink composition according to claim 14, wherein the acetylene glycol compound and the organic solvent are contained in the composition in a weight ratio of 0.01 to 10: 5 to 50. 12. The aqueous ink composition of claim 11, wherein in formulas (2) and (4), m + n ranges from 1 to 30 and m1 and n1 in formula (3) are each positive integers. The aqueous ink composition according to claim 10, wherein the compound represented by the formula (2) is contained in a range of 0.01 to 10.0 wt% based on the total amount of the composition. The aqueous ink composition according to claim 10, wherein the compound represented by Formula 3 is contained in a range of 0.01 to 5.0 wt% based on the total amount of the composition. The aqueous ink composition according to claim 10, wherein the pigment is contained in the range of 0.1 to 25% by weight relative to the total amount of the composition. The aqueous ink composition according to claim 14, wherein the organic solvent is contained in the range of 5 to 50% by weight based on the total amount of the composition. The aqueous ink composition of claim 14, wherein the organic solvent is a water soluble organic solvent. 22. The aqueous ink composition of claim 21, wherein the organic solvent comprises at least one organic compound selected from diethylene glycol, propylene glycol, polyethylene glycol, glycerin, triethylene glycol monobutyl ether, and diethylene glycol monobutyl ether. The aqueous ink composition of claim 10, wherein the static surface tension is in the range of 20 to 50 dyne / cm at 20 ° C. The aqueous ink composition of claim 10, wherein the pH value ranges from 6.5 to 10. The aqueous ink composition of claim 10, wherein the viscosity is in the range of 1 to 10 cps at 20 ° C.