JP5605773B2 - Ink composition for inkjet recording - Google Patents

Description

  The present invention relates to an ink composition for ink jet recording, and more particularly to an ink composition for ink jet recording applied to printing on cardboard.

  Due to the diversification of consumer needs for corrugated cardboard as a packaging material and the shortening of the life cycle of products to be packaged, development of printing technology that matches the tendency to produce small quantities of various products is required.

  When printing on cardboard using a flexographic printing machine, the flexographic printing machine requires a preparation time of about 5 to 10 minutes for exchanging printing plates, inks, etc. at each order change. When the preparation time of a high-speed printing machine capable of printing 300 sheets per minute requires 5 minutes, it is clear that the ratio of preparation time is considerably higher than the printing time in the case of a small number of printed sheets. Is big.

  Therefore, when printing a small amount of corrugated cardboard sheets, it is desired to adopt ink jet printing that does not require replacement work such as printing plates and ink.

  General ink jet recording inks are roughly classified into oil-based inks, UV inks, and water-based inks. Oil-based inks and UV inks have odor and toxicity. The water-based ink does not have such disadvantages, and the water-based pigment ink can be used for printing that requires water resistance and weather resistance.

  General-purpose water-based pigment inkjet recording inks are formulated with pigments, humectants, penetrants, resins, and water so that most of them are suitable for printing on plain paper or inkjet-dedicated media. (See Patent Document 1), the solid content is around 5% by weight, and there are few that exceed 10% at most.

  However, when ink-jet printing is performed on a corrugated cardboard sheet using such a general-purpose water-based pigment ink-jet recording ink, the corrugated sheet surface has a brown color tone, and the pigment sinks inside the paper fibers. For this reason, it is difficult to perform printing with the same print density and sufficiently concealment as flexographic printing.

  In general, as an aqueous inkjet recording liquid suitable for corrugated board printing, an emulsion resin and a pigment adjusted to a solid content of about 10 to 40% by weight are considered appropriate (Patent Document 2).

Japanese Patent Laid-Open No. 3-160068 (Claims) JP2007-161823 (paragraph 0016)

  However, inkjet recording inks containing an emulsion resin and having a solid content adjusted to 10% by weight or more so as to have printability on the corrugated cardboard surface can achieve a certain degree of effect in printing density and hiding properties. However, there is a problem that it is easy to form a film in a state exposed to air, or that particles do not easily form a film but tend to agglomerate and fuse with each other even before the film is formed.

  That is, if it stays in contact with air on the surface of the nozzle before being jetted by the nozzle of an inkjet printer, the emulsion resin tends to agglomerate and fuse as the moisture evaporates, and the particle size tends to increase. As the ink proceeds, a film is formed to cover the nozzle (with a diameter of about 20 μm), which may make it impossible to eject ink.

  Furthermore, as a technical issue on corrugated cardboard printing, it is necessary to enable ink jet recording that does not reduce the operating rate of the printing machine per predetermined time when printing on a small lot of corrugated cardboard with different colors for each lot. Therefore, there is a demand for an ink composition for inkjet recording that can be used stably without causing nozzle clogging or blockage for a long time.

  In particular, the emulsion resin in the ink composition is likely to be clogged in the recording liquid path and nozzle portion of an ink jet printer, and once nozzle clogging cannot be repaired, it becomes necessary to replace the head. .

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to have an appropriate printing density and concealing property on the corrugated cardboard surface, specifically, a high density ink for ink jet recording adjusted to a solid content of 15% by weight or more. However, it is an aqueous pigment ink jet recording ink composition that is difficult to cause nozzle clogging or can be easily recovered even if nozzle clogging occurs temporarily, and can be used stably for a long time. .

  In order to solve the above problems, in the present invention, an aqueous emulsion resin having a glass transition point of 16 ° C. or higher and an acid value of 10 mg KOH / g or more and a pigment are blended so that the solid content is 15% by weight or more. At the same time, an ink composition for ink jet recording was prepared by blending amino alcohol as a dispersion stabilizer.

  The ink composition for ink-jet recording of the present invention configured as described above is such that the resin particles do not extremely soften at a room temperature range of a glass transition point of 16 ° C. or higher, and the particles are not easily integrated even if they come into contact with each other. Since the aqueous emulsion resin is used as a binder, the particles hardly aggregate.

  Furthermore, since the aqueous emulsion resin employs an aqueous emulsion resin having an acid value of 10 mgKOH / g or more, aggregation of dispersed resin particles is suppressed, and an increase in particle diameter is prevented.

  Furthermore, since the solid content in the aqueous dispersion medium is blended to 15% by weight or more, the color difference between the printed surface and the cardboard fabric becomes larger than a predetermined value when printed on the brown cardboard surface. It is possible to express the same color as that of flexographic printing.

  In addition, by adding a required amount of amino alcohol as a dispersion stabilizer, the aqueous emulsion resin can improve the affinity between the resin particles and water and stabilize the dispersion state of the particles. Deterioration such as acidification is also suppressed, and stably dispersed particles are less likely to agglomerate and fuse and maintain a state in which the particle diameter is less likely to increase over time.

In the ink composition for ink-jet recording of the present invention, the amount of amino alcohol is preferably 0.5 to 20% by weight in order to ensure the action.
When the amount of amino alcohol is less than 0.5% by weight, it becomes difficult to sufficiently stabilize the dispersion state of the particles, and even when the amount exceeds 20% by weight, the dispersion stability is more than that. This is not preferable because it is not improved and the viscosity of the ink composition increases.

  An ink composition for ink jet recording that employs an acrylic emulsion resin or a styrene-acryl emulsion resin as an aqueous emulsion resin having a glass transition point of 16 ° C. or higher and an acid value of 10 mgKOH / g or higher depends on the compatibility with amino alcohol. It is preferable in order to more reliably exhibit the effect obtained.

The ink composition for ink jet recording according to the present invention preferably contains 7.5 to 30% by weight of a humectant such as glycerin.
If the moisturizing agent is less than 7.5% by weight, it is not preferable because when the amino alcohol having a relatively low boiling point is employed, the water evaporation rate of the aqueous dispersion medium cannot be sufficiently suppressed and the film formation cannot be sufficiently suppressed. Further, if the humectant is blended in a large amount exceeding 30% by weight, the viscosity of the ink composition is increased, which is not preferable.

  In addition, when printing with different colors for each cardboard, the cardboard made of the above ink-jet recording ink composition is used so that it can be used stably without causing nozzle clogging or clogging for a long time. An ink composition for inkjet recording for printing can be employed.

  Since this invention is an ink composition for ink jet recording in which an aqueous emulsion resin having a predetermined characteristic and a pigment are blended so as to have a predetermined solid content, and an amino alcohol is blended as a film formation inhibitor, the properties of the emulsion resin By adopting a predetermined blend of amino alcohol and humectant, even if the ink composition is allowed to stand at room temperature, aggregation and fusion of the emulsion resin accompanying evaporation of moisture in the ink composition are suppressed.

  After such an ink composition has landed on the paper surface, the solution portion of the ink composition penetrates into the paper, and the balance between the emulsion resin, amino alcohol and humectant is lost, and the emulsion resin aggregates on the paper surface. As a result, fusing and film formation occur, and printing with excellent print density and concealment becomes possible.

  Therefore, it is difficult to cause inkjet nozzle clogging, or even if nozzle clogging occurs temporarily, it can be easily recovered, and an aqueous pigment inkjet recording ink composition that can be used stably for a long time. In addition, the pigment can be easily fixed at a relatively high concentration on the surface of the brown corrugated cardboard sheet, and a printed matter having excellent print density and hiding property can be provided.

Embodiments of the aqueous pigment ink jet recording ink composition according to the present invention will be described below.
The ink composition for ink jet recording according to the embodiment has an aqueous emulsion resin and pigment having a glass transition point of 16 ° C. or higher and an acid value of 10 mgKOH / g or higher, and a solid content of 15% by weight or higher with respect to the aqueous dispersion medium. And an amino alcohol as a film formation inhibitor.

  The aqueous emulsion resin used in the present invention may be a commercially available aqueous emulsion resin as the raw material for the ink vehicle, or the resin raw material monomer may be polymerized by a well-known suspension polymerization method.

As described above, the glass transition point (Tg) of the emulsion resin is 16 ° C. or higher, and is 16 to 150 ° C., particularly 30 to 100 ° C. in order to effectively exhibit the effect. It is preferable.
The glass transition point (Tg) can be measured by a usual method, for example, using a thermal analyzer such as a differential scanning calorimeter (DSC). An example of the thermal analyzer is Diamond DSC manufactured by PerkinElmer. The present invention is not limited to the above device, and other devices can be used.

  In addition, an emulsion resin having an acid value of 10 mgKOH / g or more is used from the viewpoint of suppressing aggregation and film formation on the nozzle surface. In order to effectively express the effect, it is preferably 10 to 200 mgKOH / g, particularly 20 to 100 mgKOH / g. The acid value can be measured by an ordinary method, for example, a method described in JIS standard (JISK0070: 1992).

  Examples of the resin applied to the aqueous emulsion resin used in the present invention include acrylic resin, styrene resin, urethane resin, epoxy resin, and polyolefin resin, but are not particularly limited. These resins can be used alone or in combination of two or more.

The emulsion resin used in the embodiment is preferably blended in the ink composition in the form of an emulsion (for example, so-called “acrylic emulsion”) of resin particles obtained by emulsion polymerization of an unsaturated monomer.
This is because even if the resin particles are added as they are to the ink composition, the dispersion of the resin particles may be insufficient, so that the emulsion form is preferable for the production of the ink composition. The emulsion resin is preferably an acrylic or styrene-acrylic emulsion from the viewpoint of storage stability of the ink composition.

  The emulsion resin (acrylic emulsion or the like) can be obtained by a known emulsion polymerization method. For example, it can be obtained by emulsion polymerization of an unsaturated monomer (such as an unsaturated vinyl monomer) in water containing a polymerization initiator and a surfactant.

  Examples of unsaturated monomers include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl cyanide compounds generally used in emulsion polymerization. Examples include monomers, halogenated monomers, olefin monomers, and diene monomers. Furthermore, specific examples include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate. Acrylic acid esters such as dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl Methacrylate, n-hexyl methacrylate, 2-ethyl Hexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, methacrylic esters such as phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate, and vinyl esters such as vinyl acetate; vinyl such as acrylonitrile and methacrylonitrile Cyanides; halogenated monomers such as vinylidene chloride and vinyl chloride; simple aromatic vinyl such as styrene, α-methylstyrene, vinyltoluene, 4-t-butylstyrene, chlorostyrene, vinylanisole, vinylnaphthalene Olefins such as ethylene and propylene; dienes such as butadiene and chloroprene; vinyl ether, vinyl ketone, vinyl pyrrolide Vinyl monomers such as ethylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid and maleic acid; acrylamides such as acrylamide, methacrylamide and N, N′-dimethylacrylamide; 2-hydroxy Examples thereof include hydroxyl group-containing monomers such as ethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate, and these can be used alone or in combination of two or more.

  In addition to the polymerization initiator and surfactant used in emulsion polymerization, a chain transfer agent, further a neutralizing agent, and the like may be used according to a conventional method. In particular, ammonia and inorganic alkali hydroxides such as sodium hydroxide and potassium hydroxide are preferred as the neutralizing agent.

  Moreover, as the resin particles of the emulsion resin, any of a single phase structure and a multiphase structure (core-shell type) can be used.

  Commercially available acrylic or styrene-acrylic emulsion resins used in the present invention can be used, for example, BASF Japan, JONCRYL PDX-7145, the company: JONCRYL 852, the company: JONCRYL 631, center Product made by Rika Kogyo Co., Ltd .: a product group having a glass transition point of 16 ° C. or higher and an acid value of 10 mgKOH / g or higher, such as Rikabond ES-800.

  The emulsion resin has the property of thickening and aggregating when the ink lands on an image support such as paper, and has the effect of suppressing the penetration of colored components and further promoting the fixing to paper. In addition, depending on the type of emulsion resin, a film is formed on the paper, which has the effect of improving the abrasion resistance of the printed matter.

  The content of the emulsion resin is 5 to 20% by weight, preferably 7.5 to 15% by weight. When the content of the emulsion resin is less than 5% by weight, there are cases where a sufficient printing density cannot be obtained, and when the content is more than 20% by weight, the viscosity of the ink composition becomes high. It is not preferable.

  The pigment used in the present invention may be either an organic pigment or an inorganic pigment, and examples of the black pigment include carbon black pigments such as furnace black, lamp black, acetylene black, and channel black. Besides black pigments, in addition to the three primary color pigments of cyan, magenta and yellow, specific color pigments such as red, green, blue, brown and white, metallic luster pigments such as gold and silver, colorless or light body pigments, Plastic pigments may be used.

  Specific examples of pigments preferably used in the present invention include black for carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, or copper, iron (C.I. And CI pigment black 11), metals such as titanium oxide, and organic pigments such as aniline black (CI pigment black 1).

  Further, for color use, C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42, 53, 55, 81, 83, 95, 97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 138, 150, 153, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2, 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1, 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101, 104, 105, 106, 108, 112, 114, 122, 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment violet 1, 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15, 15: 1, 15: 2, 15: 3, 16, 17: 1, 56, 60, 63, C.I. I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

  The pigment used in the present invention may be a pigment to which a pigment dispersant has been added, a treated pigment having a polar functional group introduced into the surface of the particle by a chemical reaction, or a microcapsule type composite particle. Also good.

The pigment used in the invention is preferably used after being dispersed by a disperser together with a dispersant and other necessary additives according to various desired purposes.
As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. Among them, the particle size distribution when the dispersion with the sand mill is aimed at an average particle diameter of about 100 nm is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Further, the bead diameter is preferably 0.03 to 0.5 mm.

Specific examples of the polymer dispersant for dispersing the pigment include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxyalkylene alkyls. Activators such as ether phosphate, polyoxyalkylene alkylphenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinyl naphthalene derivative, acrylic Block copolymer and random copolymer comprising two or more monomers selected from acids, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives Beauty can be mentioned salts thereof.
The addition amount of the pigment dispersant is preferably 10 to 100 parts by weight with respect to 100 parts by weight of the pigment.

In addition, the surface of the pigment is treated with a resin to make it dispersible in water, and a hydrophilic functional group such as a sulfonic acid group, carboxyl group, carbonyl group or hydroxyl group is added to the surface of the pigment to add water. Self-dispersing pigments and the like that can be dispersed can be used.
Further, a pigment may be included in a microcapsule so that the pigment can be dispersed in water.
In dispersing the pigment, a surfactant can be used as an additive. As the surfactant, any of cationic, anionic, amphoteric and nonionic can be used.

  The volume average particle diameter of the pigment is preferably 10 to 1000 nm, and more preferably 50 to 500 nm. If the volume average particle size of the color material is too small than the above range, there may be a case where the printing density becomes low, while if it is over the above range, the storage stability and the jetting stability may not be ensured. It is not preferable.

The amount of these pigments is such that the aqueous emulsion resin and the pigment are blended so that the solid content is 15% by weight or more.
The solid content in the present invention refers to the weight% of the solid content after drying with respect to that before drying, and is represented by the following formula.
Solid content (%) = weight after drying (g) / weight before drying (g) × 100

  In order to mix the aqueous emulsion resin and the pigment so that the solid content is 15% by weight or more with respect to the aqueous dispersion medium, the pigment is subjected to a surface modification treatment and can be dispersed spontaneously without a dispersant. A non-self-dispersion type pigment dispersion in which a pigment is dispersed in water by using a pigment or using a dispersant or a surfactant in combination can be used.

In the present invention, the pigment content is preferably 5% by weight or more and 20% by weight or less, and more preferably 7.5 to 15% by weight within the range satisfying the above-described solid content condition.
When the pigment content is less than 5% by weight, a sufficient print density may not be obtained, which is not preferable. When the content is more than 20% by weight, the liquid ejection characteristics are unstable. This is not preferable.

Since the amino alcohol as a dispersion stabilizer used in the present invention hardly evaporates at room temperature, it contributes to dispersion stabilization of the emulsion resin as a neutralizing agent for the emulsion resin, and further suppresses aggregation of the emulsion resin and a film. Acts as a formation inhibitor.
Specifically, alkanolamines such as methanolamine, ethanolamine, propanolamine, butanolamine, or aromatic amino alcohols can be used, and primary, secondary, tertiary alcohols, etc. should be used without distinction. Can do. Specifically, monoethanolamine, diethanolamine, triethanolamine, ethyldiethanolamine, diethylethanolamine, tripropanolamine, 2-amino-2-methyl-1-propanol, methylethanolamine, methyldiethanolamine, dimethylethanolamine, ethyl Ethanolamine, dibutylethanolamine, diisopropanolamine and the like.

  The compounding amount of amino alcohol is 0.5 to 20% by weight, preferably 1 to 10% by weight. If the amino alcohol content is less than 0.5% by weight, emulsion resin aggregation or film formation occurs, and if the content exceeds 20% by weight, the viscosity of the ink composition increases, which is not preferable. .

As the humectant to be blended in the ink composition of the present invention, a conventional polyhydric alcohol and its ether or sugar alcohol are used alone or in order to prevent drying of the ink and to improve clogging prevention in the ink jet nozzle. The thing which mix | blended the seed | species or more can be mentioned.
Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1.2.6-hexanetriol, thiodiglycol, hexylene glycol, glycerin, and trimethylol. Examples include ethane and trimethylolpropane.

  Examples of the alkyl ether compound include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether. Alkyl ethers of polyhydric alcohols such as: urea, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sugars such as sugar alcohol, etc. These 1 type (s) or 2 or more types are used.

  The amount of the humectant is 7.5 to 30% by weight, preferably 10 to 20% by weight. When the amount of the humectant is less than 7.5% by weight, aggregation of the emulsion resin or film formation is likely to occur. When the content exceeds 30% by weight, the viscosity of the ink composition is high. Since it becomes high, it is not preferable.

The ink composition of the present invention may contain a penetrant as a component.
Specific examples of the penetrating agent include at least one selected from acetylene glycol surfactants, acetylene alcohol surfactants, silicon surfactants, alkylene glycol monoalkyl ethers, 1,2-alkylene glycols, and monohydric alcohols. Species are preferred.

  By adding these, the dryness of the printed matter is improved, and even if continuous printing is performed, the previous print portion is not transferred to the back side of the next print medium. Printing is possible.

  Further, as other additives, it contains at least an emulsion resin having a glass transition point of 16 ° C. or higher and an acid value of 10 mg KOH / g or higher, an amino alcohol, a humectant, and water. , Wax, antifoaming agent, dissolution aid, penetration control agent, viscosity modifier, pH adjuster, antioxidant, antifungal agent, corrosion for the purpose of ensuring storage stability, achieving stable ejection from the ink ejection head, etc. Various additives such as an inhibitor and a chelating agent for capturing metal ions that affect dispersion may be added.

<Preparation of pigment dispersion 1>
The components (a), (b), (c), and (d) were added in the following composition to make the total amount 100 parts by weight. The liquid was pre-stirred and then dispersed with a bead mill.
(a) 30 parts by weight of pigment (DIC Corporation: SYMULER RED 3090)
(b) Pigment dispersant (manufactured by Kyoeisha Chemical Co., Ltd .: Floren TG-760W, active ingredient amount 35%)
17.15 parts by weight
(c) Defoaming agent (manufactured by Nissin Chemical Industry Co., Ltd .: Orphin SK-14) 0.6 parts by weight
(d) Water remaining

<Preparation of pigment dispersion 2>
The components (e), (f), (c), and (d) were added in the following composition to make the total amount 100 parts by weight. The liquid was pre-stirred and then dispersed with a bead mill.
(e) 30 parts by weight of pigment (manufactured by DIC: SYMULER FAST YELLOW 4090G)
(f) Pigment dispersant (manufactured by Kyoeisha Chemical Co., Ltd .: Floren WK-13E, active ingredient amount 40%) 15 parts by weight
(c) Defoaming agent (manufactured by Nissin Chemical Industry Co., Ltd .: Orphin SK-14) 0.6 parts by weight
(d) Water remaining

Of the materials used in the examples and comparative examples, those other than the above-described pigment dispersion are listed below.
(1) Styrene-acrylic emulsion resin (manufactured by BASF Japan: JONCRYL PDX-7145, Tg 56 ° C., average particle size 0.16 μm, acid value: 32 mg KOH / g, weight average molecular weight 200,000 or more, solid content 50%)
(2) Styrene-acrylic emulsion resin (manufactured by BASF Japan: JONCRYL 852, Tg 31 ° C., average particle size 0.11 μm, acid value: 82 mg KOH / g, weight average molecular weight 200,000 or more, solid content 44%)
(3) Styrene-acrylic binder resin (manufactured by BASF Japan: JONCRYL 631, Tg 87 ° C., average particle size 0.11 μm, acid value: 25 mg KOH / g, weight average molecular weight 200,000 or more, solid content 49.5%)
(4) Styrene-acrylic emulsion resin (BASF Japan, JONCRYL 390, Tg-5 ° C., average particle size 0.09 μm, acid value: 54 mg KOH / g, weight average molecular weight 200,000 or more, solid content 46%)
(5) Styrene-acrylic emulsion resin (BASF Japan, JONCRYL 741, Tg 15 ° C., average particle size 0.10 μm, acid value: 51 mg KOH / g, weight average molecular weight 200,000 or more, solid content 49%)
(6) Styrene-acrylic emulsion resin (Chuo Rika Kogyo Co., Ltd .: Rikabond ES-800 Tg 50 ° C., average particle size 0.13 μm, acid value 10 mg KOH / g, weight average molecular weight 200,000 or more, solid content 50%)
(7) Styrene-acrylic emulsion resin (Chuo Rika Kogyo Co., Ltd .: Rikabond ES-35 Tg 30 ° C., average particle size 0.13 μm, acid value 6.7 mg KOH / g, weight average molecular weight 200,000 or more, solid content 46%)
(8) Amino alcohol (diethanolamine)
(9) Amino alcohol (triethanolamine)
(10) Amino alcohol (monoethanolamine)
(11) Amino alcohol (monoisopanolamine)
(12) Amino alcohol (2-amino-2-methyl-1-propanol)
(13) Triethylamine
(14) Moisturizer (glycerin)
(15) Water

[Examples 1 to 12, Comparative Examples 1 to 7]
Each component (% by weight) was added in the composition shown in Tables 1 and 2 to make the total amount 100% by weight. Thereafter, the mixture was stirred at room temperature and filtered through a membrane filter having a pore size of 5 μm to prepare an ink composition (aqueous pigment ink).
In addition, all the mixture ratios shown in Tables 1 and 2 are% by weight of the active ingredient, and the item numbers of the materials described above are added to the tables as necessary.

以上の実施例および比較例について、以下の評価試験を行ない、その結果を表１中に併記した。

The following evaluation tests were conducted on the above examples and comparative examples, and the results are also shown in Table 1.

<Evaluation test for film formation (measurement of maximum particle size)>
20 g of the ink compositions of Examples and Comparative Examples were placed in a petri dish having an inner diameter of 85 mm and left in a constant temperature and humidity room at a temperature of 23 ° C. and a humidity of 50% for 1 week. The ink on the petri dish surface was collected and dispersed in water, and then the maximum particle size was measured with a laser diffraction particle size distribution analyzer. The laser diffraction particle size distribution measuring apparatus was measured under the conditions of a refractive index of 1.60-0.50i using SALD-2100 manufactured by Shimadzu Corporation.

<Evaluation test for color difference (measurement of ink deposition amount and ΔE)>
Printing was performed with a commercially available printer using the ink compositions of Examples and Comparative Examples, and the evaluation was performed. For printing evaluation, an ink jet printer (PX-V630: manufactured by Seiko Epson Corporation) was used, and the entire surface was printed in a range of 18 cm in width and 24 cm in length of a flat paperboard liner (manufactured by Rengo: RKA210). After printing, the amount of weight increase was measured, and the amount of ink applied was calculated according to the following formula.
Ink amount (g / m ² ) = (weight of paper after printing (g) −weight of paper before printing (g)) / printing area (m ² )
In addition, the L *, a *, and b * values (color coordinate values in the UCS color space) of the printed surface of the liner left for one day are printed using a color tester (manufactured by Suga Test Instruments Co., Ltd .: SC-3). The color difference ΔE * ab between the surface and the liner was determined according to JIS Z 8722.

<Solid content measurement test>
Example and Comparative Example About 1 g of the ink composition was placed in a weighing bottle, preliminarily dried at 50 ° C., and then dried at 180 ° C. under reduced pressure. Three measurements were performed on one ink composition, and the average value calculated by the following formula was used as the solid content. This solid content is considered to be substantially equal to the total solid content of the pigment, pigment dispersant and emulsion resin.
Solid content (%) = weight after drying (g) / weight before drying (g) × 100

  As is clear from the results of Tables 1 and 2, the ink composition of Comparative Example 1 containing no diethanolamine had a particle diameter after standing larger than the nozzle diameter of 20 μm, and inkjet printing was impossible. became. Further, the ink compositions of Comparative Examples 2 and 3 employing a binder resin having a glass transition point lower than a predetermined value also had a large particle size after being left, making inkjet printing impossible. In addition, the ink composition of Comparative Example 4 using triethylamine instead of diethanolamine was unable to perform inkjet printing because a film was formed by evaporation.

  On the other hand, the example which is an ink composition in which an amino alcohol is blended using an aqueous emulsion resin having a glass transition point of 16 ° C. or higher and a pigment has a solid content of 15% by weight or more. However, the film does not easily agglomerate or fuse, and the particle diameter is difficult to increase. Even when exposed to air, the film was not formed.

Claims (3)

A water-based emulsion resin composed of an acrylic emulsion resin or styrene-acrylic emulsion resin having a glass transition point of 16 to 87 ° C. and an acid value of 10 to 82 mgKOH / g and a pigment are blended so that the solid content is 15% by weight or more. In addition, an ink composition for ink jet recording comprising 0.5 to 20% by weight of an amino alcohol composed of alkanolamine or aromatic amino alcohol as a dispersion stabilizer. The ink composition for ink jet recording according to claim 1, wherein a moisturizing agent is blended in an amount of 7.5 to 30% by weight. An ink composition for ink jet recording for corrugated cardboard printing, comprising the ink composition for ink jet recording according to claim 1 or 2 .