Pigment dispersion composition, dispersion composition, active energy ray-curable ink composition, printing method and printing system

Abstract

To provide a pigment dispersion composition having improved dispersibility of a pigment, a dispersion composition, an active energy ray-curable ink composition, a printing method and a printing system.SOLUTION: There is provided a pigment dispersion composition which comprises a pigment, a dispersant and a dispersion medium, wherein the pigment has a sulfo group or a sulfonic acid derivative group and the dispersant is a polyallylamine having an alkyl ester side chain.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pigment dispersion composition, a dispersion composition, an active energy ray-curable ink composition, a printing method, and a printing system. More specifically, the present invention relates to a pigment dispersion composition having improved pigment dispersibility. [Background technology]

[0002] Inkjet printing is used in various printing fields because it can form images easily and inexpensively. One type of ink used in inkjet printing is active energy ray curable ink. In this specification, "active energy ray curable ink" is also simply referred to as "ink".

[0003] In the case of active energy ray curable ink, droplets of the ink are landed on a printing medium, and then irradiated with active energy rays to cure the ink, forming an image. Inkjet printing methods using active energy ray curable ink can form images even on non-absorbent printing media. In addition, images having high abrasion resistance and adhesion can be formed. For this reason, active energy ray curable ink has been attracting attention in recent years.

[0004] The active energy ray curable ink contains a pigment. Pigments are superior to dyes in terms of fastness due to their characteristics such as heat resistance and weather resistance. On the other hand, in the case of inks containing pigments, it is necessary to prevent pigment aggregation, pigment sedimentation, increase in the viscosity of the ink over time, and the like.

[0005] Patent Document 1 discloses a technique for a pigment composition containing a specific metal-containing azo pigment dispersant. However, the stability of the pigment composition is problematic in a high-temperature environment. In addition, if the pigment does not have sufficient dispersibility in a printed matter formed using an ink containing a pigment, the pigment cannot be sufficiently fixed to the print medium and is likely to move from the print medium. This phenomenon is called "migration." There has been a demand for further suppression of migration in printed matters formed using an ink containing the pigment composition. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2012-107157 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems and circumstances, and an object of the present invention is to provide a pigment dispersion composition, a dispersion composition, an active energy ray-curable ink composition, a printing method, and a printing system, which have improved pigment dispersibility. [Means for solving the problem]

[0008] Means for Solving the Problems The present inventors have investigated the causes of the above problems in order to solve the above problems. As a result, they have found that in a pigment dispersion composition containing a pigment, a dispersant, and a dispersion medium, the dispersibility of the pigment can be improved by providing a pigment having a sulfo group or a sulfonic acid derivative group and a dispersant which is a polyallylamine having an alkyl ester side chain, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0009] 1. A pigment dispersion composition containing a pigment, a dispersant, and a dispersion medium, The pigment has a sulfo group or a sulfonic acid derivative group, and The dispersant is a polyallylamine having alkyl ester side chains. A pigment dispersion composition comprising:

[0010] 2. The dispersion medium is an acrylate or a methacrylate. 2. The pigment dispersion composition according to claim 1,

[0011] 3. The predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.4. 2. The pigment dispersion composition according to claim 1,

[0012] 4. The acrylate or methacrylate has a repeating structure derived from ethylene oxide or propylene oxide. 3. The pigment dispersion composition according to claim 2,

[0013] 5. The dispersant has a repeating structure represented by the following general formula (1): 2. The pigment dispersion composition according to claim 1,

[0014] [ka]

[0015] (In general formula (1), m represents an integer in the range of 2 to 100, and n represents an integer in the range of 2 to 20.)

[0016] 6. A dispersion composition comprising a dispersant and a dispersion medium, the dispersant is a polyallylamine having alkyl ester side chains; The predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.4. A dispersion composition comprising:

[0017] 7. A pigment dispersion composition according to any one of items 1 to 5. 1. An actinic ray-curable ink composition comprising:

[0018] 8. Also contains a gelling agent 8. The actinic ray-curable ink composition according to item 7,

[0019] 9. A step of preparing a pigment dispersion composition, Produce the active energy ray-curable ink composition according to item 7. The present invention relates to a method for producing an active energy ray-curable ink composition.

[0020] 10. Using the active energy ray curable ink composition described in item 7 A printing method comprising:

[0021] 11. The active energy ray-curable ink composition according to item 7 is used. A printing system comprising: Effect of the Invention

[0022] According to the above-mentioned means of the present invention, it is possible to provide a pigment dispersion composition, a dispersion composition, an active energy ray-curable ink composition, a printing method, and a printing system, all of which have improved pigment dispersibility.

[0023] Although the mechanism by which the effects of the present invention are manifested or the mechanism by which the effects of the present invention are acted upon has not been clearly understood, it is speculated as follows.

[0024] A dispersant is necessary to stably disperse a pigment in a dispersion medium. The dispersant has affinity with both the pigment and the dispersion medium. Generally, cationic dispersants are known as dispersants for pigments having a sulfo group or a sulfonic acid derivative group. However, cationic dispersants have high polarity and low affinity depending on the type of dispersion medium. Therefore, it is difficult to stably disperse a pigment having a sulfo group or a sulfonic acid derivative group.

[0025] In particular, when the dispersion medium is an EO-modified, PO-modified, or alkyl chain-containing (meth)acrylate, it is difficult to stably disperse the pigment. In this specification, "EO-modified" in (meth)acrylate refers to a structure having an oxyethylene group (-CH2-CH2-O-). Also, "PO-modified" refers to a structure having an oxypropylene group (-CH2-CH(CH3)-O-). Details of EO-modification and PO-modification will be described later.

[0026] Among them, EO-modified, PO-modified or alkyl chain-containing (meth)acrylates are often contained in actinic energy ray-curable ink compositions. In other words, there has been a demand for improving the dispersibility of pigments having a sulfo group or a sulfonic acid derivative group in actinic energy ray-curable ink compositions.

[0027] The dispersant according to the present invention is an allylamine having an alkyl ester side chain. The dispersant has a high affinity with a pigment having a sulfo group or a sulfonic acid derivative group. The dispersant also has a high affinity with an EO-modified, PO-modified, or alkyl chain-containing (meth)acrylate as a dispersion medium. More specifically, the hydrophobic portion of the dispersant has a high affinity with the dispersion medium. Therefore, it is considered that the balance between the pigment, the dispersant, and the dispersion medium is maintained, improving the dispersibility of the pigment. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram showing an exemplary configuration of a printing device 100. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] The pigment dispersion composition of the present invention is a pigment dispersion composition containing a pigment, a dispersant, and a dispersion medium, characterized in that the pigment has a sulfo group or a sulfonic acid derivative group, and the dispersant is an allylamine having an alkyl ester side chain. This feature is a technical feature common to or corresponding to the following embodiments.

[0030] In an embodiment of the present invention, from the viewpoint of preparing an active energy ray-curable ink composition using the pigment dispersion composition, the dispersion medium is preferably an acrylate or a methacrylate.

[0031] In an embodiment of the present invention, from the viewpoint of the affinity between the dispersant and the dispersion medium, the predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is preferably within the range of 2.0 to 2.4.

[0032] As an embodiment of the present invention, from the viewpoint of affinity between the dispersant and the dispersion medium, the pigment dispersion composition preferably has a repeating structure of the acrylate or methacrylate derived from ethylene oxide or propylene oxide.

[0033] In an embodiment of the present invention, from the viewpoint of affinity between the dispersant and the dispersion medium, the dispersant in the pigment dispersion composition preferably has a repeating structure represented by the following general formula (1).

[0034] [ka]

[0035] (In general formula (1), m represents an integer in the range of 2 to 100, and n represents an integer in the range of 2 to 20.)

[0036] The dispersion composition of the present invention is a dispersion composition containing a dispersant and a dispersion medium, wherein the dispersant is an allylamine having an alkyl ester side chain, and the predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.4.

[0037] The active energy ray-curable ink composition of the present invention is characterized by containing the above-mentioned pigment dispersion composition.

[0038] In an embodiment of the present invention, from the viewpoint of fixing the ink on a print medium, the active energy ray-curable ink composition preferably further contains a gelling agent.

[0039] The method for producing an active energy ray-curable ink composition of the present invention is characterized by comprising a step of preparing a pigment dispersion composition, and producing the active energy ray-curable ink composition.

[0040] The printing method of the present invention is characterized by using the above-mentioned active energy ray-curable ink composition.

[0041] The printing system of the present invention is characterized by comprising the active energy ray-curable ink composition.

[0042] The present invention, its components, and modes and aspects for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after the symbol "to" are included as the lower limit and upper limit.

[0043] 1. Overview of pigment dispersion composition The pigment dispersion composition of the present invention is a pigment dispersion composition containing a pigment, a dispersant, and a dispersion medium, characterized in that the pigment has a sulfo group or a sulfonic acid derivative group, and the dispersant is an allylamine having an alkyl ester side chain.

[0044] In the present invention, the term "dispersant" refers to an additive for uniformly dispersing the pigment in the pigment dispersion composition in the dispersion medium. By including a dispersant, it is possible to suppress aggregation and sedimentation of the pigment. In addition, it is possible to reduce the viscosity of the pigment dispersion composition, and improve the stability. Hereinafter, it is also referred to as a "polyallylamine dispersant". In the present invention, the term "dispersion medium" refers to a medium in which a pigment, which is a dispersoid, is dispersed.

[0045] The pigment dispersion composition of the present invention can be mixed with other components as necessary and processed. Examples of processing include printing inks, paints, colored plastic products, etc. In this specification, an active energy ray curable ink used for printing by the inkjet method will be described. However, the pigment dispersion composition of the present invention can also be applied to inks used for other printing methods.

[0046] 2. Constitution of pigment dispersion composition The pigment dispersion composition of the present invention contains a pigment, a dispersant, and a dispersion medium. The pigment, dispersant, and dispersion medium will each be described below.

[0047] (1) Pigments The pigment according to the present invention has a sulfo group or a sulfonic acid derivative group. Hereinafter, the "sulfo group or sulfonic acid derivative group" will also be referred to as "sulfo group, etc." In the present invention, the term "sulfonic acid derivative group" refers to a functional group in which the hydrogen atom of a sulfo group (-SO3H) is replaced with another atom or a substituent. The sulfo group may form a salt.

[0048] In the present invention, the term "pigment" refers to a substance that has a coloring function and is insoluble in water and organic solvents. The pigment may be composed of one type of compound or two or more types of compounds. The pigment may be in the form of particles, and may further be in the form of particles having additives adsorbed on their surfaces. In the present invention, at least one of the compounds that constitute the pigment has a sulfo group or the like in its structure.

[0049] Common pigments include those listed in the Color Index. The Color Index is a database of color materials established by the British Society of Dyestuffs and Textile Chemists and the American Association of Textile Chemists and Dyers. Among the pigments listed in the Color Index, those having a sulfo group or the like in their chemical structure can be used in the present invention.

[0050] Specifically, one example is an anthraquinone derivative (alizarin red S) represented by the following formula (a): The color index number of the anthraquinone derivative represented by the following formula (a) is CI58005.

[0051] [ka]

[0052] Other examples of pigments having sulfo groups or the like include pigments in which sulfo groups or the like have been introduced by surface modification of the particles. Also included are pigments in which an additive having a sulfo group or the like has been adsorbed onto the surface of the particles. That is, in a conventionally known pigment, a sulfo group or the like can be introduced into the pigment by surface modifying the pigment particles or by adsorbing an additive onto the pigment particles.

[0053] The conventionally known pigments are not particularly limited and may be inorganic or organic pigments. Examples of inorganic pigments include titanium dioxide, iron oxide, cadmium sulfide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, yellow lead, and carbon black. Examples of organic pigments include azo pigments, diazo pigments, condensed azo pigments, thioindigo pigments, indanthrones, quinacridone pigments, anthraquinone pigments, benzimidazolone pigments, perylene pigments, perinone pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthrapyridine pigments, and dioxazine pigments.

[0054] (Surface modification) The pigment according to the present invention can be made to easily adsorb a polyallylamine dispersant to the pigment particles by introducing a sulfo group or the like into the pigment particles through surface modification. The surface modification can be carried out by a conventionally known method, for example, a method of subjecting the surface of the pigment particles to an oxidation treatment, a method of subjecting the surface to a treatment agent such as a silane coupling agent having a sulfo group, a method of subjecting the surface to a surface coupling treatment with an aromatic diazonium salt having a sulfo group, or the like.

[0055] Other surface modification methods include, for example, rosin treatment. In the present invention, sulfonated rosin is used. Here, the residue obtained by collecting balsams such as pine resin (the sap of plants of the pine family) and distilling turpentine essential oil is called "rosin". Rosin is a natural resin whose main components are abietic acid, palustric acid, isopimaric acid, etc. It is preferable that the pigment particles are surface-modified with sulfonated rosin. However, the strength of the bond between the pigment particles and the sulfonated rosin is not particularly limited, and the pigment particles and the sulfonated rosin may interact with each other through a relatively weak bond such as a hydrogen bond.

[0056] (Additives) The pigment according to the present invention can easily adsorb a polyallylamine dispersant to the pigment particles by adsorbing an additive to the pigment particles and introducing a sulfo group, etc. The additive can be a commercially available product or one synthesized by a conventionally known method.

[0057] An example of the additive will be described below, but the present invention is not limited thereto. When the pigment particles contain copper phthalocyanine, a sulfo group or the like can be introduced by adding a copper phthalocyanine sulfonic acid derivative. The copper phthalocyanine and the copper phthalocyanine sulfonic acid derivative interact with each other at sites having a common structure, so that the copper phthalocyanine sulfonic acid derivative is adsorbed to the pigment particles. As a method for synthesizing the copper phthalocyanine sulfonic acid derivative, a method of sulfonating copper phthalocyanine with concentrated sulfuric acid or fuming sulfuric acid can be mentioned. In addition, a method of sulfochlorinating copper phthalocyanine with chlorosulfonic acid and then hydrolyzing it with water can be mentioned.

[0058] When the pigment particles contain carbon black, sulfo groups and the like can be introduced by adding a sulfonic acid derivative of a styrene-based dispersant. Carbon black, which has a structure in which the π plane extends, and the sulfonic acid derivative of the styrene-based dispersant, which has π electrons, undergo π-π interaction (stacking), so the sulfonic acid derivative of the styrene-based dispersant is adsorbed to the pigment particles.

[0059] Specific examples of the pigment according to the present invention are given below. Examples of cyan pigments include sulfonated pigments such as Pigment Blue 15:3 and Pigment Blue 15:4. Examples of commercially available cyan pigments include "Paliogen (registered trademark) Blue EH 1900", "Heliogen (registered trademark) Blue D-7086, D7110F", and "FASTOGEN (registered trademark) Blue 5452K" (all manufactured by DIC Corporation). Examples of commercially available cyan pigments include "LIONOL BLUE FG-7400-G, FG-7397-G", "LIONOGEN BLUE LX-8059" (all manufactured by Toyo Ink Co., Ltd.).

[0060] Examples of magenta pigments include sulfonates such as perylene, quinacridone, naphthol, and carmine. Commercially available magenta pigments include "Chromofine (registered trademark) Red 6112JC" (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.), "FASTOGEN (registered trademark) SUPER MAGENTA RGT, JM04", "FASTOGEN (registered trademark) SUPER RED BRZ" (all manufactured by DIC Corporation), "5R-763", "5R-780", and "6B 690" (all manufactured by Fuji Color Co., Ltd.).

[0061] An example of the black pigment is carbon black, etc. An example of a commercially available black pigment is "Mitsubishi (registered trademark) Carbon Black MA-7" (manufactured by Mitsubishi Chemical Corporation). The pigment according to the present invention may be synthesized by the method described in Journal of the Chemical Society of Japan, Vol. 1972, No. 9, pp. 1712-1717, JP-A-10-110129, JP-A-2011-225834, Japanese Patent No. 7188661, or the like.

[0062] (2) Dispersant The ink of the present invention contains polyallylamine having an alkyl ester side chain as a dispersant. The ink of the present invention may also contain other dispersants as necessary to the extent that the effect is not impaired.

[0063] Details will be described later, but for example, the polyallylamine derivative described below is a reaction product between an alkyl ester or an alkyl ester amide and a polyallylamine. The polyallylamine has an amino group that exhibits basicity. A part of the amino group of the polyallylamine reacts with the alkyl ester or the alkyl ester amide to form a salt or an acid amide. This can impart a solvating function to the polyallylamine. In addition, a part of the amino group does not react and remains as an amino group, so that it is sufficiently adsorbed to the pigment. Therefore, it functions sufficiently as a pigment dispersant.

[0064] The dispersant preferably has a function of suppressing aggregation of pigments by steric hindrance in addition to a function of adsorbing to the pigment and a function of solvating the pigment, and therefore the pigment dispersant is preferably a polymer compound.

[0065] The content of the dispersant is preferably within a range of 10 to 60% by mass relative to the total mass of the pigment. When the content of the dispersant is 10% by mass or more, the dispersion stability of the pigment is improved. When the content of the dispersant is 60% by mass or less, the ejection stability of the ink from the inkjet head is improved.

[0066] (2.1) Components of polyallylamine derivatives Specifically, the dispersant according to the present invention is a compound in which the amino group on the side chain of polyallylamine is modified, and the component that modifies the amino group is an alkyl ester or a co-condensation product of an alkyl ester and a polyamide (alkyl ester amide). Hereinafter, the "compound in which the amino group on the side chain of polyallylamine is modified" will also be simply referred to as a "polyallylamine derivative".

[0067] The polyallylamine derivative has a structure represented by the following general formula (I).

[0068] [ka]

[0069] In the general formula (I), X and Y each independently represent a hydrogen atom, a polymerization initiator residue, or a chain transfer catalyst residue. 1 is a group represented by the following general formula (II) or (III), where n represents an integer in the range of 2 to 1000. 1 At least one of the above has a group represented by general formula (III).

[0070] [ka]

[0071] [ka]

[0072] In the general formulas (II) and (III), R 2 represents the residue obtained by removing the carboxy group from an alkyl ester or alkyl ester amide. 1 represents the position of the carbon bonded to In addition, general formula (II) indicates that the amino group is modified by an ionic bond.

[0073] The polyallylamine derivative can be obtained by reacting polyallylamine with an alkyl ester or an alkyl ester amide. Each component will be described below.

[0074] (2.1.1) Polyallylamine Polyallylamine can be obtained by polymerizing polyallylamine in the presence of a polymerization initiator and, in some cases, in the presence of a chain transfer catalyst.

[0075] The polymerization initiator is not particularly limited, and examples thereof include ketone peroxides such as methyl ethyl ketone, diacyl peroxides such as benzoyl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, peroxyketals such as 1,1-bis(t-butylperoxy)cyclohexane, hydroperoxides such as t-butyl hydroperoxide, peroxyesters such as t-butyl peroxypivalate, and others, azobisisoptylonitrile, hydrogen peroxide, ferrous salts, etc. Also, the polymerization initiators described in JP-B-2-14364 may be used.

[0076] The chain transfer catalyst is not particularly limited, and examples thereof include alkyl mercaptans such as lauryl mercaptan; thiocarboxylic acids such as mercaptoacetic acid, 2-mercaptopropionic acid, and 3-mercaptopropionic acid; and thiocarboxylic acid esters such as butyl thioglycolate and 2-ethylhexyl thioglycolate.

[0077] The number average molecular weight of the polyallylamine is not particularly limited as long as it is within the range of 150 to 100,000, but is preferably within the range of 600 to 20,000.

[0078] By setting the number average molecular weight to 150 or more, sufficient adsorption to the pigment can be obtained, and by setting the number average molecular weight to 100,000 or less, aggregation between the pigments can be suppressed.

[0079] Commercially available polyallylamine products may be used, such as "PAA-1LV", "PA-1L", "PA-1LV", "PAA-1.4L", "PAA-10C", "PAA-15", "PAA-15B", "PAA-L", "PAA-H", and "PAA-1L-15C" (all manufactured by Nitto Boseki Co., Ltd.).

[0080] Moreover, polyallylamine having an arbitrary molecular weight may be synthesized by using the method described in JP-B-2-14364.

[0081] (2.1.2) Alkyl esters The alkyl ester preferably has a structure represented by the following general formula (IV), which is a structure derived from a hydroxy fatty acid. In addition to the structure represented by the following general formula (IV), the alkyl ester may have a structure represented by the following general formula (V). The alkyl ester may be a structure in which the repeating structures represented by the following general formulas (IV) and (V) are randomly polymerized.

[0082] [ka]

[0083] In general formula (IV), R 3 represents a linear or branched alkylene group having a carbon atom number in the range of 2 to 20. a represents an integer of 2 to 100.

[0084] [ka]

[0085] In general formula (V), R 4 R represents an alkylene group having 2 to 20 carbon atoms, -C6H4-, or -CH=CH-. 5 R represents an alkylene group having 2 to 20 carbon atoms or a residue obtained by removing two hydroxy groups from a polyalkylene glycol. 4 and R 5 In the above formula, the alkylene group may be linear or branched, and b represents an integer of 2 to 100. In addition, the alkylene group may have an ether bond in the chain.

[0086] The alkyl ester in the alkyl ester amide preferably has a structure represented by the above general formula (IV), which is a structure derived from a hydroxy fatty acid. In addition to the structure represented by the above general formula (IV), the alkyl ester may have a structure represented by the above general formula (V). In addition, the alkyl ester may be a structure in which the repeating structures represented by the above general formulas (IV) and (V) are randomly polymerized.

[0087] The polyamide in the alkyl ester amide has, for example, a structure represented by the following general formula (VI) or (VII): In addition, the polyamide may be formed by randomly polymerizing the repeating structures represented by the following general formulas (VI) and (VII).

[0088] [ka]

[0089] In general formula (VI), R 6 represents a linear or branched alkylene group having a carbon atom number in the range of 2 to 20. c represents an integer of 2 to 100.

[0090] [ka]

[0091] In general formula (VII), R 4 R represents an alkylene group having 2 to 20 carbon atoms, -C6H4-, or -CH=CH-. 7 R represents an alkylene group having 2 to 20 carbon atoms. 4 and R 7 In the above formula, the alkylene group may be linear or branched. d represents an integer of 2 to 100.

[0092] (2.1.2.1) Method for synthesizing alkyl esters The synthesis of alkyl esters having the structures represented by the above general formulas (IV) and (V) will be described below.

[0093] (2.1.2.1.1) Synthesis of alkyl ester having the structure represented by general formula (IV) The alkyl ester having the structure represented by the above general formula (IV) can be synthesized using a hydroxy fatty acid having the structure represented by the following general formula (VIII) or a lactone represented by the following general formula (IX) as a raw material. The lactone represented by the following general formula (IX) can be synthesized by dehydration condensation of the hydroxy group and the carboxy group in the molecule of the hydroxy fatty acid.

[0094] Specifically, the alkyl ester can be synthesized by adding a polymerization catalyst to a hydroxy fatty acid alone, a lactone alone, or a mixture of a hydroxy fatty acid and a lactone, and then heating the mixture. The reaction temperature is preferably within the range of 120 to 220°C, and more preferably within the range of 160 to 210°C.

[0095] The reaction time is preferably within a range of 0.5 to 72 hours. By carrying out the reaction under a nitrogen gas flow, the degree of polymerization can be increased. By using a polymerization initiator, the reaction can be easily controlled. When lactone is used as a raw material, the amount of monocarboxylic acid in the polymerization initiator is preferably 0.5 mol or less per mol of lactone.

[0096] [ka]

[0097] [ka]

[0098] In the general formula (VIII) and the general formula (IX), R 3 represents a linear or branched alkylene group having 2 to 20 carbon atoms.

[0099] Examples of hydroxy fatty acids include glycolic acid, 2-hydroxycaproic acid, ricinoleic acid, ricinolenic acid, a mixture of 9- and 10-hydroxystearic acid, 12-hydroxystearic acid, castor oil fatty acid, hydrogenated castor oil fatty acid, and lactic acid.

[0100] Examples of lactones include ε-caprolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, 4-methylcaprolactone, and 2-methylcaprolactone.

[0101] Examples of the polymerization catalyst include quaternary ammonium salts such as tetramethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide, tetramethylammonium iodide, tetrabutylammonium iodide, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide, and benzyltrimethylammonium iodide; tetramethylphosphonium chloride, tetrabutylphosphonium chloride, tetramethylphosphonium bromide, tetrabutylphosphonium bromide, tetramethylphosphonium iodide, tetrabutylphosphonium iodide, and benzyltrimethylammonium iodide; quaternary phosphonium salts such as benzyltrimethylphosphonium chloride, benzyltrimethylphosphonium bromide, benzyltrimethylphosphonium iodide, tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, and tetraphenylphosphonium iodine; phosphorus compounds such as triphenylphosphine; organic carboxylates such as potassium acetate, sodium acetate, potassium benzoate, and sodium benzoate; alkali metal alcoholates such as sodium alcoholate and potassium alcoholate; tertiary amines; organic tin compounds; organic aluminum compounds; organic titanate compounds; and zinc compounds such as zinc chloride.

[0102] Examples of the polymerization initiator include monocarboxylic acids, such as aliphatic monocarboxylic acids such as acetic acid, propionic acid, caprylic acid, nonanoic acid, capric acid, octylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isononanoic acid, and arachic acid; and aromatic monocarboxylic acids such as benzoic acid and p-butylbenzoic acid.

[0103] (2.1.2.1.2) Synthesis of alkyl ester having the structure represented by general formula (V) The alkyl ester having the structure represented by the above general formula (V) can be synthesized by reacting a dibasic acid having the structure represented by the following general formula (X) with a diol having the structure represented by the following general formula (XI).

[0104] Specifically, the compound can be synthesized by adding a polymerization catalyst to a mixture of the dibasic acid and diol and heating the mixture. However, it is preferable to add a little excess of the dibasic acid. The reaction temperature is preferably within the range of 120 to 220°C, more preferably within the range of 160 to 210°C. The reaction time is preferably within the range of 0.5 to 72 hours. The degree of polymerization can be increased by carrying out the reaction under a nitrogen stream. The reaction can be easily controlled by using a polymerization initiator.

[0105] [ka]

[0106] [ka]

[0107] In general formula (X), R 4 represents an alkylene group having 2 to 20 carbon atoms, -C6H4-, or -CH=CH-. In formula (XI), R 5 R represents an alkylene group having 2 to 20 carbon atoms or a residue obtained by removing two hydroxy groups from a polyalkylene glycol. 4 and R 5 In the above formula, the alkylene group may be linear or branched.

[0108] Examples of dibasic acids include dibasic acids having an unsaturated bond, such as maleic anhydride and fumaric acid; aromatic dibasic acids, such as phthalic anhydride and terephthalic acid; and saturated dibasic acids, such as adipic acid and sebacic acid.

[0109] Examples of the diol include alkylene glycols such as ethylene glycol, propylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,6-hexanediol; and ether bond-containing diols such as diethylene glycol, dipropylene glycol, and triethylene glycol.

[0110] The polymerization catalyst and polymerization initiator that can be used are the same as those used in the synthesis of the alkyl ester having the structure represented by general formula (IV).

[0111] An alkyl ester in which the repeating units represented by general formula (IV) and general formula (V) are randomly polymerized can be synthesized by the following method. A polymerization catalyst is added to a mixture of either a hydroxy fatty acid alone, a lactone alone, or a mixture of a hydroxy fatty acid and a lactone, and an equimolar amount of the above diol and dibasic acid, and the mixture is heated. The reaction conditions are preferably the same as those for the synthesis of an alkyl ester having a structure represented by general formula (IV).

[0112] An alkyl ester in which the repeating units represented by general formula (IV) and general formula (V) are polymerized in a block form can be synthesized by the following method. An alkyl ester having a structure represented by general formula (IV) and an alkyl ester having a structure represented by general formula (V) are synthesized in advance. Then, these are subjected to dehydration condensation to obtain the alkyl ester.

[0113] The molecular weight of the alkyl ester is preferably within the range of 300 to 20,000. From the viewpoint of dispersibility of the pigment, the molecular weight is preferably within the range of 1,000 to 10,000. By having the molecular weight within the above range, the side chain of the dispersant can be made to an appropriate length, resulting in excellent dispersibility. By adjusting the molar ratio of the polymerization initiator, the raw materials hydroxy fatty acid, lactone, diol and dibasic acid, an alkyl ester having a desired molecular weight can be obtained. In addition, by observing the acid value of the reaction product during the synthesis reaction of the alkyl ester and adjusting the reaction time, an alkyl ester having a desired molecular weight can be obtained.

[0114] (2.1.2.2) Alkyl ester amide The alkyl ester amide is a co-condensation product of the alkyl ester and the polyamide described below. It can be synthesized by polymerizing one or more alkyl ester raw materials and one or more polyamide raw materials. Alternatively, it can be synthesized by pre-condensing the alkyl ester and the polyamide described below, respectively, and then co-condensing them. The reaction conditions are preferably the same as those for the synthesis of the polyamide described below. The molecular weight (degree of polymerization) of the alkyl ester amide can be measured by the acid value.

[0115] (2.1.2.2.1) Synthesis of polyamide having a structure represented by general formula (VI) The polyamide having the structure represented by the above general formula (VI) can be synthesized using a lactam having the structure represented by the following general formula (XII) or an aminocarboxylic acid having the structure represented by the following general formula (XIII) as a raw material.

[0116] Specifically, the compound can be synthesized by heating a lactam having a structure represented by the following general formula (XII), an aminocarboxylic acid having a structure represented by the following general formula (XIII), or a mixture of a lactam and an aminocarboxylic acid. The polycondensation reaction is preferably carried out under a nitrogen gas flow. The reaction temperature is preferably within a range of 110 to 250°C, and more preferably within a range of 150 to 210°C. By keeping the reaction temperature at 250°C or less, coloring of the reaction product can be suppressed, and by keeping the reaction temperature at 110°C or more, a sufficient reaction rate can be obtained.

[0117] The reaction time is preferably within the range of 0.5 to 72 hours. Furthermore, the use of a polymerization initiator makes it easy to control the reaction. Furthermore, the addition of a polymerization catalyst can shorten the reaction time. The molecular weight of the polyamide can be measured by the acid value. When lactam is used as the raw material, the amount of monocarboxylic acid in the polymerization initiator is preferably 0.5 mol or less per mol of lactam.

[0118] [ka]

[0119] [ka]

[0120] In the general formula (XII) and the general formula (XIII), R 6 represents a linear or branched alkylene group having 2 to 20 carbon atoms.

[0121] Examples of lactams include ε-caprolactam, ω-laurolactam, etc. Examples of aminocarboxylic acids include aminocaproic acid, 11-aminoundecanoic acid, etc. The polymerization catalyst and polymerization initiator may be the same as those used in the synthesis of the alkyl ester having the structure represented by general formula (IV).

[0122] (2.1.2.2.2) Synthesis of polyamide having a structure represented by general formula (VII) The polyamide having the structure represented by the above general formula (VII) can be synthesized using a dibasic acid having the structure represented by the above general formula (X) and a diamine represented by the following general formula (XIV) as raw materials.

[0123] [ka]

[0124] In general formula (XIV), R 7 represents a linear or branched alkylene group having 2 to 20 carbon atoms.

[0125] Examples of diamines include ethylenediamine, 1,4-diaminobutane, and hexamethylenediamine.

[0126] In the synthesis of the polyamide having the structure represented by the general formula (VII), the reaction conditions etc. can be the same as those in the synthesis of the polyamide having the structure represented by the above general formula (VI).

[0127] (2.1.3) Synthesis of polyallylamine derivatives The amino groups on the side chains of polyallylamine are modified with alkyl esters or alkyl ester amides to synthesize polyallylamine derivatives.

[0128] The amount of alkyl ester or alkyl ester amide having a free carboxy group is preferably 1 mole or more in total per mole of polyallylamine having n amino groups, where n is the same as n in the above general formula (I) and is an integer in the range of 2 to 1000. From the viewpoint of pigment dispersibility, the amount of alkyl ester or alkyl ester amide having a free carboxy group is more preferably in the range of 2 to 2n moles.

[0129] The alkyl ester or alkyl ester amide may be used alone or in combination of two or more kinds. Different types of alkyl ester or alkyl ester amide may be reacted with polyallylamine at the same time. A polymerization catalyst may be used in the reaction, and the polymerization catalyst may be the same as that used in the synthesis of the alkyl ester having the structure represented by general formula (IV). In addition, a solvent such as xylene or toluene may be used as a reaction solvent.

[0130] The reaction of polyallylamine with alkyl ester or alkyl ester amide is a salt formation reaction or an acid amide bond formation reaction via the free amino group of the former and the terminal free carboxy group of the latter. Depending on the type of alkyl ester or alkyl ester amide and the reaction conditions, an ester-amide exchange reaction also occurs simultaneously between the ester of the alkyl ester or alkyl ester amide and the amino group of the side chain of polyallylamine. In the reaction of polyallylamine with alkyl ester or alkyl ester amide, whether a salt or an acid amide is formed depends on the reaction conditions.

[0131] The salt formation reaction and the acid amide bond formation reaction proceed simultaneously. The reaction temperature in the acid amide bond formation reaction is preferably within the range of 90 to 250°C, more preferably within the range of 90 to 210°C, and even more preferably within the range of 100 to 210°C. By keeping the reaction temperature at 250°C or less, coloration of the reaction product can be suppressed, and by keeping the reaction temperature at 90°C or more, a sufficient reaction rate can be obtained. In addition, by carrying out the reaction under a nitrogen stream, a reaction product with little coloring can be obtained.

[0132] On the other hand, the reaction temperature in the salt formation reaction is preferably within the range of 20 to 140°C.

[0133] The polyallylamine derivative preferably has an acid amide bond. From the viewpoint of pigment dispersibility, it is preferable that the terminal carboxyl group of the alkyl ester or alkyl ester amide reacts with 1 mole of the polyallylamine having n amino groups at a ratio of 2 moles or more. Here, n is the same as n in the above general formula (I) and is an integer in the range of 2 to 1000.

[0134] In the above general formula (I), n R 1 Among them, the residues in the form of bonded via an acid amide bond represented by the above general formula (III) are present in the range of preferably 60 to 95%, more preferably 65 to 90%.

[0135] That is, 60% or more of the amino groups in the polyallylamine are covalently bonded to alkyl esters or alkyl ester amides via amide bonds. This makes it possible to suppress the aggregation of pigments, and the polyallylamine functions as a pigment dispersant. Also, 95% or less of the amino groups in the polyallylamine are covalently bonded to alkyl esters or alkyl ester amides via amide bonds. In other words, by leaving more than 5% of the amino groups as amino groups, the polyallylamine can be sufficiently adsorbed to the pigment, and functions as a pigment dispersant.

[0136] (amine value) In the polyester derivative, the amino group of the polyallylamine is bonded by a covalent bond within the above range. To achieve this, the amine value A is measured immediately after mixing the polyester or polyesteramide having a carboxy group at one end with at least one of the polyallylamine, and the amine value B is measured after the reaction is completed, and the change between these values ​​is calculated. (Formula) Percentage of covalent bonds of amino groups in polyester derivatives [%] ={(AB) / A}×100

[0137] The amine value immediately after mixing may be measured. However, since the reaction has not progressed immediately after mixing, the amine value of the polyallylamine used as a raw material can also be calculated from the masses of the polyester or polyesteramide and polyallylamine added to the reaction. Even if the carboxy group of the polyester or polyesteramide and the amino group of the polyallylamine form a salt, this does not affect the desired amine value.

[0138] In the synthesis of the polyallylamine derivative, the mass ratio of polyallylamine to alkyl ester or alkyl ester amide is preferably within the range of 1 / 5 to 1 / 30.

[0139] From the viewpoint of pigment dispersibility, the amine value (mgKOH / g) of the polyallylamine derivative is preferably within a range of 2.5 to 50, more preferably within a range of 5 to 30, and even more preferably within a range of 10 to 20. When the amine value is 2.5 or more, sufficient adsorption to the pigment can be achieved, and when the amine value is 50 or less, aggregation between the pigments can be suppressed.

[0140] The molecular weight of the polyallylamine derivative is preferably within the range of 2,000 to 100,000 from the viewpoint of pigment dispersibility.

[0141] The polyallylamine derivative may be prepared by directly modifying the amino group on the side chain of the polyallylamine with a hydroxy fatty acid or lactone, and may further include a dibasic acid, a diol, an aminocarboxylic acid, a lactam, or a diamine, if necessary.

[0142] (2.1.4) Specific examples of dispersants according to the present invention The dispersant according to the present invention may be a commercially available product. Examples of commercially available dispersants include "Solsperse 24000GR, 24000SC, 32000, 33000" (all manufactured by Lubrizol Nippon Corporation), "Ajisper PA111, PB711, PB821, PB822, PB824" (all manufactured by Ajinomoto Fine-Techno Co., Ltd.), and the like.

[0143] Further, the dispersant according to the present invention may be a compound described in Japanese Patent No. 1940521, Japanese Patent No. 1570685, Japanese Patent No. 3504268, JP-T-2003-509205, or the like.

[0144] (2.2) Other dispersants Examples of other dispersants that can be used in combination include polymer dispersants other than the above-mentioned dispersants, surfactants, etc. Among these, polymer dispersants are preferred.

[0145] Examples of polymer dispersants include (meth)acrylic resins, styrene-(meth)acrylic resins, hydroxy group-containing carboxylic acid esters, salts of long-chain polyaminoamides and high molecular weight acid esters, salts of high molecular weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high molecular weight unsaturated acid esters, modified polyurethanes, modified polyacrylates, polyether ester-type anionic surfactants, naphthalenesulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, stearylamine acetate, pigment derivatives, etc. However, among the pigment derivatives, sulfonic acid derivatives fall under the above-mentioned pigments. In order to improve dispersibility, a dispersing aid may be further contained, if necessary.

[0146] (3) Dispersion medium The dispersion medium according to the present invention is not particularly limited as long as it is a solvent capable of dispersing the pigment and dispersant. However, from the viewpoint of preparing an active energy ray-curable ink composition using the pigment dispersion composition, the dispersion medium is preferably a solvent used in ink. In other words, the dispersion medium is preferably a polymerizable compound capable of sufficiently dispersing the pigment and dispersant and cured by irradiation with active energy rays. The polymerizable compound as the dispersion medium will be described below.

[0147] Examples of the polymerizable compound include a radical polymerizable compound, a cationic polymerizable compound, or a mixture thereof. The compound includes a monomer, a polymer (oligomer or polymer), or a mixture thereof. The polymerizable compound may be contained alone or in combination of two or more kinds.

[0148] The content of the polymerizable compound is preferably within a range from 1 to 97% by mass, and more preferably within a range from 30 to 95% by mass, based on the total mass of the ink.

[0149] (CLogP value) The polymerizable compound preferably has a predicted 1-octanol / water partition coefficient CLogP value within the range of 2.0 to 2.4. When the CLogP value is within the above range, the dispersibility of the pigment is improved.

[0150] Here, the "LogP value" is a coefficient indicating the affinity of an organic compound to water and 1-octanol. "P" is the 1-octanol / water partition coefficient. More specifically, "P" is the ratio of the equilibrium concentrations of a compound in each solvent in a two-phase solvent of 1-octanol and water when a trace amount of a compound is dissolved as a solute in each solvent in the partition equilibrium state. The logarithm of the 1-octanol / water partition coefficient to the base 10 is indicated by "LogP". In other words, the "LogP value" is the logarithm of the 1-octanol / water partition coefficient, and is known as an important parameter that indicates the hydrophilicity or hydrophobicity of a molecule.

[0151] The "CLogP value" is a LogP value calculated by calculation, and is a predicted value. The CLogP value can be calculated by the fragment method, the atomic approach method, or the like. A specific method for calculating the CLogP value is the fragment method described in the literature (C. Hansch and A. Leo, "Substituent Constants for Correlation Analysis in Chemistry and Biology" (John Wiley & Sons, New York, 1969)).

[0152] Also included is a method using the commercially available software package listed below. The structural formula of the compound is created using ChemDraw Professional Ver.20.0.0.41 (manufactured by Cambridge Soft). Then, the CLogP value can be calculated using the "Chemical Properties" function in the software. The CLog values ​​described in this specification are values ​​calculated by this method.

[0153] (3.1) Radical polymerizable compound The term "radical polymerizable compound" refers to a compound having an ethylenically unsaturated bond capable of radical polymerization. Examples of the radical polymerizable compound include unsaturated carboxylic acids and their salts, unsaturated carboxylic acid ester compounds, unsaturated carboxylic acid urethane compounds, unsaturated carboxylic acid amide compounds and their anhydrides, acrylonitrile, styrene, unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Examples of the unsaturated carboxylic acids include (meth)acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid.

[0154] In this specification, (meth)acrylic acid is a general term for acrylic acid and methacrylic acid, and means one or both of them. "(meth)acrylate" is a general term for acrylate and methacrylate, and means one or both of them. "Acrylate" is a general term for acrylate monomers and acrylate oligomers, and means one or both of them. Similarly, "methacrylate" is a general term for methacrylate monomers and methacrylate oligomers, and means one or both of them.

[0155] Among them, the polymerizable compound is preferably an unsaturated carboxylic acid ester compound, more preferably a (meth)acrylate compound. The (meth)acrylate compound may be not only a monomer described below, but also an oligomer, a mixture of a monomer and an oligomer, a modified product, or the like.

[0156] (3.1.1) (Meth)acrylate compounds Examples of the (meth)acrylate compound of a monofunctional monomer include isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomylstyryl (meth)acrylate, isostearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, meth ... Examples of the acrylates include methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl-phthalate, and t-butylcyclohexyl (meth)acrylate.

[0157] Examples of the (meth)acrylate compound of a bifunctional monomer include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, PO adduct di(meth)acrylate of bisphenol A, hydroxypivalic acid neopentyl glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate.

[0158] Examples of the (meth)acrylate compound of a trifunctional or higher polyfunctional monomer include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, and pentaerythritol ethoxy tetra(meth)acrylate.

[0159] Among these, from the viewpoint of photosensitivity and the like, the (meth)acrylate compound is preferably stearyl (meth)acrylate, lauryl (meth)acrylate, isostearyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, isobornyl (meth)acrylate, tetraethylene glycol di(meth)acrylate, or glycerin propoxy tri(meth)acrylate.

[0160] The (meth)acrylate compound may be a modified product. Examples of the modified product include ethylene oxide modified (meth)acrylate compounds such as ethylene oxide modified trimethylolpropane tri(meth)acrylate and ethylene oxide modified pentaerythritol tetraacrylate; caprolactone modified (meth)acrylate compounds such as caprolactone modified trimethylolpropane tri(meth)acrylate; and caprolactam modified (meth)acrylate compounds such as caprolactam modified dipentaerythritol hexa(meth)acrylate. The term "modified product" refers to a compound into which a characteristic group (including a functional group, a substituent, a linking group, etc.) has been introduced in order to improve the chemical or physical properties of the main (or parent) compound according to a purpose. For example, by modifying the compound, the molecular weight can be adjusted while maintaining the reactivity of the compound.

[0161] Among them, the linking group to be introduced is preferably an oxyethylene group (-CH2-CH2-O-) or an oxypropylene group (-CH2-CH(CH3)-O-). It is also preferable that a plurality of these groups are introduced. In other words, the (meth)acrylate compound according to the present invention preferably has a repeating structure derived from ethylene oxide or propylene oxide. By having such a structure, the affinity with the dispersant can be further improved.

[0162] As an example, the structures of phenyl acrylate and phenol EO-modified acrylate are shown below. Note that Ph represents a phenyl group, and n is an integer of 1 or more. (Phenyl acrylate) CH2=CH-COO-Ph (Phenol EO modified acrylate) CH2=CH-CO-(OC2H4) n -O-Ph

[0163] The ink of the present invention may be a sol-gel phase transition type ink. In this case, it is preferable that at least a part of the polymerizable compound is an ethylene oxide modified (meth)acrylate compound. The ethylene oxide modified (meth)acrylate compound has high photosensitivity, and when the ink gels at low temperature, it is likely to form a house-of-cards structure. In addition, the ethylene oxide modified (meth)acrylate compound is likely to dissolve in other ink components at high temperature. The ethylene oxide modified (meth)acrylate compound has little cure shrinkage, and can suppress curling of the printed matter.

[0164] Examples of ethylene oxide modified (meth)acrylate compounds include 4EO modified hexanediol diacrylate "CD561" (molecular weight: 358), 3EO modified trimethylolpropane triacrylate "SR454" (molecular weight: 429), 6EO modified trimethylolpropane triacrylate "SR499" (molecular weight: 560), 4EO modified pentaerythritol tetraacrylate "SR494" (molecular weight: 528) (all manufactured by Sartomer); polyethylene glycol diacrylate "NK Ester A-400" (molecular weight: 508), polyethylene glycol diacrylate "NK Ester A-400" (molecular weight: 508), and polyethylene glycol diacrylate "NK Ester A-400" (molecular weight: 508). Acrylate "NK Ester A-600" (molecular weight: 742), polyethylene glycol dimethacrylate "NK Ester 9G" (molecular weight: 536), polyethylene glycol dimethacrylate "NK Ester 14G" (molecular weight: 770) (all manufactured by Shin-Nakamura Chemical Co., Ltd.); tetraethylene glycol diacrylate "V#335HP" (manufactured by Osaka Organic Chemical Industry Co., Ltd., molecular weight: 302); 3PO-modified trimethylolpropane triacrylate "Photomer (registered trademark) 4072" (manufactured by Cognis, molecular weight: 471, ClogP value: 4.90); 1,10-decanediol dimethacrylate Examples include "NK Ester DOD-N" (molecular weight: 310, ClogP value: 5.75), tricyclodecane dimethanol diacrylate "NK Ester A-DCP" (molecular weight: 304, ClogP value: 4.69), and tricyclodecane dimethanol dimethacrylate "NK Ester DCP" (molecular weight: 332, ClogP value: 5.12) (all manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0165] The (meth)acrylate compound may be a polymerizable oligomer. Examples of the polymerizable oligomer include an epoxy (meth)acrylate oligomer, an aliphatic urethane (meth)acrylate oligomer, an aromatic urethane (meth)acrylate oligomer, a polyester (meth)acrylate oligomer, and a linear (meth)acrylic oligomer.

[0166] The (meth)acrylate compound may be a commercially available product. Examples of commercially available (meth)acrylate compounds include "SR231 NS (diethylene glycol dimethacrylate, CLogP value: 2.04)", "SR212 B (1,3-butylene glycol diacrylate, CLogP value: 2.09)", "SR495B NS (caprolactone acrylate, CLogP value: 2.10)", "SR306 NS (tripropylene glycol diacrylate, CLogP value: 2.17)", and "SR444D NS (pentaerythritol triacrylate, CLogP value: 2.38)" (all manufactured by Sartomer).

[0167] In addition, examples of commercially available (meth)acrylate compounds include the Miramer (registered trademark) series. Specific examples include M222 (dipropylene glycol diacrylate, CLogP value: 2.04), M220 (tripropylene glycol diacrylate, CLogP value: 2.17), M144 (phenol EO-modified acrylate, CLogP value: 2.27), and M340 (pentaerythritol triacrylate, CLogP value: 2.38) (all manufactured by MIWON).

[0168] Other commercially available (meth)acrylate compounds include, for example, "EM223 (tripropylene glycol diacrylate, CLogP value: 2.17)", "EM222 (dipropylene glycol diacrylate, CLogP value: 2.36)", and "EM235-1 (pentaerythritol triacrylate, CLogP value: 2.38)" (all manufactured by Choko Materials Industry Co., Ltd.).

[0169] (3.2) Cationic polymerizable compounds The term "cationically polymerizable compound" refers to a compound having a cationically polymerizable group in the molecule. Examples of the cationically polymerizable compound include epoxy compounds, vinyl ether compounds, and oxetane compounds. These compounds may be contained alone or in combination of two or more.

[0170] (3.2.1) Epoxy compounds Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, aliphatic epoxides, etc. Among them, aromatic epoxides or alicyclic epoxides are preferred from the viewpoint of enhancing curability.

[0171] Examples of aromatic epoxides include diglycidyl ethers or polyglycidyl ethers obtained by reacting polyhydric phenols or their alkylene oxide adducts with epichlorohydrin. Examples of polyhydric phenols or their alkylene oxide adducts to be reacted include bisphenol A or its alkylene oxide adducts. Examples of alkylene oxides in the alkylene oxide adducts include ethylene oxide and propylene oxide.

[0172] Examples of the alicyclic epoxide include a cycloalkane oxide-containing compound obtained by epoxidizing a cycloalkane-containing compound with an oxidizing agent such as hydrogen peroxide, peracid, etc. Examples of the cycloalkane in the cycloalkane oxide-containing compound include cyclohexene, cyclopentene, etc.

[0173] Examples of the aliphatic epoxide include diglycidyl ethers or polyglycidyl ethers obtained by reacting an aliphatic polyhydric alcohol or its alkylene oxide adduct with epichlorohydrin. Examples of the aliphatic polyhydric alcohol include alkylene glycols such as ethylene glycol, propylene glycol, and 1,6-hexanediol. Examples of the alkylene oxide in the alkylene oxide adduct include ethylene oxide and propylene oxide.

[0174] (3.2.2) Vinyl ether compounds Examples of the vinyl ether compound include monovinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

[0175] Examples of the vinyl ether compound include divinyl ether compounds or trivinyl ether compounds such as ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether. From the viewpoints of curability, adhesion, and the like, a divinyl ether compound or a trivinyl ether compound is preferred.

[0176] (3.2.3) Oxetane compounds The oxetane compound is a compound having an oxetane ring. Examples of the oxetane compound include oxetane compounds described in JP-A-2001-220526, JP-A-2001-310937, and JP-A-2005-255821. More specifically, the compound represented by general formula (1) described in paragraph 0089 of JP-A-2005-255821, the compound represented by general formula (2) described in paragraph 0092 of the same publication, the compound represented by general formula (7) in paragraph 0107, the compound represented by general formula (8) in paragraph 0109, and the compound represented by general formula (9) in paragraph 0116 are included.

[0177] 3. Method for producing pigment dispersion composition The method for preparing (producing) the pigment dispersion composition is not particularly limited, and the pigment dispersion composition can be prepared by a known method. As the dispersion medium of the pigment dispersion composition, from the viewpoint of dispersibility and handleability with the polymerizable compound, it is preferable to use a polymerizable compound having a relatively low viscosity and a low molecular weight.

[0178] The pigment dispersion composition can be prepared by dispersing the pigment in a dispersion medium using the above-mentioned dispersant. The pigment can be dispersed using, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, or the like.

[0179] From the viewpoint of storage stability, the volume average particle size of the pigment in the pigment dispersion composition is preferably within the range of 90 to 180 nm, more preferably within the range of 110 to 140 nm. The particle size of the pigment can be measured, for example, using a particle size analyzer "Zetasizer Nano S" (manufactured by Malvern Panalytical).

[0180] 4. Dispersion composition The dispersion composition of the present invention is a dispersion composition containing a dispersant and a dispersion medium, wherein the dispersant is a polyallylamine having an alkyl ester side chain, and the predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.4.

[0181] That is, in the pigment dispersion composition, the dispersoid is a pigment, but in the dispersion composition, the dispersoid may be a component other than the pigment. By combining the dispersant and the dispersion medium, the dispersibility of a specific dispersoid is improved. The dispersoid preferably has a sulfo group or a sulfonic acid derivative group. The dispersoid is not limited to a pigment, and may be a functional particle.

[0182] 5. Constitution of active energy ray-curable ink composition The active energy ray-curable ink composition of the present invention is characterized by containing the above-mentioned pigment dispersion composition.

[0183] That is, the ink of the present invention contains the above-mentioned pigment, dispersant, and dispersion medium, and may further contain a gelling agent, a fatty acid, a polymerization initiator, a polymerization initiation aid, a polymerization inhibitor, and the like.

[0184] (1) Gelling agent In the present invention, the "gelling agent" refers to an organic substance that is solid at room temperature and becomes liquid when heated. The melting point of the gelling agent is preferably within a range of 30 to 150°C. The gelling agent is preferably soluble in a polymerizable compound described below at a temperature higher than the gelling temperature. In addition, the gelling agent is preferably crystallized in the ink at a temperature equal to or lower than the gelling temperature.

[0185] The "sol-gel phase transition temperature" refers to the temperature at which a material changes (transitions) from a sol state to a gel state. The "sol-gel phase transition temperature" is synonymous with the terms gel transition temperature, gel melting temperature, gel softening temperature, sol-gel transition point, and gel point.

[0186] When the gelling agent crystallizes in the ink, it is preferable that the plate-like crystals, which are the crystallized product of the gelling agent, form a three-dimensionally enclosed space. It is preferable that the plate-like crystals encapsulate the polymerizable compound in the space thus formed. Such a structure in which the polymerizable compound is encapsulated in the three-dimensionally enclosed space formed by the plate-like crystals is called a "house of cards structure."

[0187] The formation of the house-of-cards structure makes it possible to hold the liquid polymerizable compound and fix (pin) the ink droplets. Furthermore, it is possible to prevent the droplets from coalescing. In order to form the house-of-cards structure, it is preferable that the polymerizable compound and the gelling agent dissolved in the ink are compatible with each other. If the polymerizable compound and the gelling agent dissolved in the ink are phase-separated, it is difficult to form the house-of-cards structure.

[0188] The gelling agent is not particularly limited. Examples of gelling agents include ketone waxes such as dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosyl ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone, and palmityl stearyl ketone; Ester waxes such as behenyl behenate, icosanoic acid icosyl, stearyl stearate, palmityl stearate, cetyl palmitate, myristyl myristate, cetyl myristate, and myricyl cerotenate; Petroleum-based waxes such as paraffin wax, microcrystalline wax, and petrolactam; Vegetable waxes such as candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil, jojoba solid wax, and jojoba esters; Animal waxes such as beeswax, lanolin, and whale wax; Mineral waxes such as montan wax and hydrogenated wax; Hydrogenated castor oil or hydrogenated castor oil derivatives; Modified waxes such as montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives, and polyethylene wax derivatives; higher alcohols such as stearyl alcohol and behenyl alcohol; Hydroxystearic acids, such as 12-hydroxystearic acid; 12-Hydroxystearic acid derivatives; fatty acid amides such as lauric amide, stearic amide, behenic amide, oleic amide, erucic amide, ricinoleic amide, and 12-hydroxystearic amide; N-substituted fatty acid amides such as N-stearyl stearic acid amide and N-oleyl palmitic acid amide; Special fatty acid amides such as N,N'-ethylene bisstearylamide, N,N'-ethylene bis-12-hydroxystearylamide, and N,N'-xylylene bisstearylamide; Higher amines such as dodecylamine, tetradecylamine, and octadecylamine; fatty acid ester compounds such as stearyl stearic acid, oleyl palmitic acid, glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters, and polyoxyethylene fatty acid esters; esters of sucrose fatty acids such as sucrose stearate, sucrose palmitate, etc.; Synthetic waxes such as polyethylene wax and α-olefin maleic anhydride copolymer wax; Dimer acid; Dimer diol and the like. These may be contained alone or in combination of two or more.

[0189] The gelling agent used may be a commercially available product. Commercially available ketone waxes include, for example, "18-Pentatriacontanone" (manufactured by Alfa Aeser), "Hentriacontan-16-on" (manufactured by Alfa Aeser), and "Kao (registered trademark) Wax T1" (manufactured by Kao Corporation). Examples of ester waxes include "Unistar (registered trademark) M-2222SL" (manufactured by NOF Corporation), "Exepar (registered trademark) SS" (manufactured by Kao Corporation, melting point 60°C), "EMALEX (registered trademark) CC-18" (manufactured by Nippon Emulsion Co., Ltd.), "Amureps (registered trademark) PC" (manufactured by Kokyu Alcohol Kogyo Co., Ltd.), "Exepar (registered trademark) MY-M" (manufactured by Kao Corporation), "Sperm Acetate" (manufactured by NOF Corporation), and "EMALEX (registered trademark) CC-10" (manufactured by Nippon Emulsion Co., Ltd.). Commercially available fatty acid amides include, for example, the "Nikkaamide (registered trademark) series" (manufactured by Nippon Kasei Chemical Industry Co., Ltd.), the "ITOWAX series" (manufactured by Ito Oil Mills Co., Ltd.), and the "FATTYAMID series" (manufactured by Kao Corporation). Commercially available fatty acid ester compounds include, for example, the "EMALLEX (registered trademark) series" (manufactured by Nippon Emulsion Co., Ltd.), the "Rikemal (registered trademark) series" (manufactured by Riken Vitamin Co., Ltd.), and the "Poem (registered trademark) series, etc." (manufactured by Riken Vitamin Co., Ltd.). Commercially available sucrose fatty acid esters include, for example, the "Ryoto Sugar Ester (registered trademark) Series" (manufactured by Mitsubishi Chemical Foods Corporation). Examples of commercially available synthetic waxes include the "UNILIN (registered trademark) series" (manufactured by Baker-Petrolite). Commercially available dimer diol products include, for example, the "PRIPOR series" (manufactured by Croda).

[0190] Among them, the gelling agent is preferably a ketone wax, an ester wax, a higher fatty acid, a higher alcohol, or a fatty acid amide, and more preferably a ketone wax or an ester wax.

[0191] Particularly preferred gelling agents include compounds represented by the following general formula (G1) or (G2). General formula (G1):R 21 -CO-R 22 General formula (G2):R 23 -COO-R 24 In the formula, R 21 ~R 24 each independently represents an alkyl chain having a straight chain portion having 12 or more carbon atoms and which may be branched.

[0192] General formula (G1) is called ketone wax, and general formula (G2) is called fatty acid ester. These gelling agents can gel ink droplets more stably and with high reproducibility. Therefore, they can suppress the coalescence of ink droplets (dots) that land on the printing medium.

[0193] The sol-gel phase transition temperature of the ink can be set arbitrarily. From the viewpoints of stable ejection of ink droplets and the adverse effects associated with high-temperature heating, the sol-gel phase transition temperature is preferably within the range of 30 to 100° C. In addition, the sol-gel phase transition temperature is preferably a temperature between the temperature of the ink in the inkjet head and the temperature of the printing medium.

[0194] The sol-gel phase transition temperature can be measured, for example, by placing a gel-like test piece on a heat plate. The heat plate is then heated to measure the temperature at which the test piece loses its shape, and this temperature can be determined as the sol-gel phase transition temperature. Alternatively, the temperature can be measured using a commercially available viscoelasticity measuring device, for example, the viscoelasticity measuring device "MCR300" (manufactured by Physica).

[0195] The sol-gel phase transition temperature can be adjusted by the type, content, etc. of the polymerizable compound described below.

[0196] When the temperature of the ink droplets ejected from the inkjet head and landed on the printing medium drops below the sol-gel phase transition temperature, the ink droplets quickly gel. This prevents the dots (ink droplets) from mixing with each other or merging, allowing high-quality images to be formed even with high-speed printing. The gelled ink droplets are then irradiated with active energy rays and hardened, fixing them on the printing medium and forming a strong image film.

[0197] The ink droplets that land on the print medium quickly gel, making them less likely to spread on the print medium and preventing oxygen from entering the ink droplets. As a result, the ink is less susceptible to oxygen inhibition when curing.

[0198] The content of the gelling agent is preferably within the range of 1 to 10% by mass, more preferably within the range of 1 to 7% by mass, based on the total mass of the ink. When two or more types of gelling agents are contained, it is preferable that the total mass of these is within the above range. When the content of the gelling agent is 1% by mass or more, the ink undergoes a sufficient sol-gel phase transition. When the content of the gelling agent is 10% by mass or less, ink ejection stability from an inkjet head is obtained.

[0199] (2)Fatty acid The ink of the present invention may further contain a fatty acid. By containing a fatty acid, the storage stability and ejection stability of the ink are improved. Furthermore, by containing a fatty acid, the surface slip property of the ink when ejected onto a printing medium is good.

[0200] The fatty acid is preferably a compound having 12 or more carbon atoms. Examples of fatty acids include behenic acid (C 22 H 44 O2), arachidic acid (C 20 H 40 O2), stearic acid (C 18 H 36 O2), palmitic acid (C 16 H 32 O2), myristic acid (C 14 H 28 O2), lauric acid (C 12 H 24 O2), oleic acid (C 18 H 34 O2), erucic acid (C 22 H 42 O2) etc.

[0201] The fatty acids used may be commercially available products. Examples of commercially available products include "Lunac (registered trademark) BA", "Lunac (registered trademark) S-90V", "Lunac (registered trademark) S-98", "Lunac (registered trademark) P-70", "Lunac (registered trademark) P-95", "Lunac (registered trademark) MY-98", "Lunac (registered trademark) L-70", "Lunac (registered trademark) L-98" (all manufactured by Kao Corporation), "NAA (registered trademark)-222S beads", "NAA (registered trademark)-222 powder", "Beads Sakura Stearate", "Beads Camellia Stearate", "Powdered Sakura Stearate", "Powdered Camellia Stearate", "NAA (registered trademark)-160", "NAA (registered trademark)-142", "NAA (registered trademark)-122", "NAA (registered trademark)-34", "NAA (registered trademark)-35", and erucic acid (all manufactured by NOF Corporation).

[0202] The content of the fatty acid is preferably within a range of 0.01 to 10 ppm by mass, more preferably within a range of 0.01 to 0.18 ppm by mass, based on the total mass of the ink. When the content is 0.01 ppm by mass or more, the storage stability and ejection stability of the ink are good. In addition, when the ink is ejected onto a printing medium, the surface slipperiness of the ink is good, and so-called paper jams can be suppressed. When the content is 10 ppm by mass or less, the storage stability of the ink is good.

[0203] (3) Polymerization initiator The ink of the present invention may further contain a polymerization initiator. Specifically, when the active energy rays are electron beams, the ink may not contain a polymerization initiator, but when the active energy rays are ultraviolet rays, the ink preferably contains a polymerization initiator.

[0204] Polymerization initiators are classified into intramolecular bond cleavage type and intramolecular hydrogen abstraction type.

[0205] Examples of the intramolecular bond cleavage type polymerization initiator include acetophenone-based initiators such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoins such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acylphosphine oxide-based initiators such as 2,4,6-trimethylbenzoin diphenylphosphine oxide; benzyl glyoxy esters; and methylphenyl glyoxy esters.

[0206] Examples of the intramolecular hydrogen abstraction type polymerization initiator include benzophenone-based initiators such as benzophenone, o-benzoylmethylbenzoate-4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, acrylated benzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone-based initiators such as 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone; aminobenzophenone-based initiators such as Michler's ketone and 4,4'-diethylaminobenzophenone; 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0207] Although it depends on the constituent components of the ink, the content of the polymerization initiator is preferably within the range of 0.01 to 10% by mass with respect to the total mass of the ink.

[0208] The ink of the present invention may contain a photoacid generator as a polymerization initiator. Examples of photoacid generators include compounds used in chemically amplified photoresists or photocationic polymerization. For details, see Organic Electronics Materials Research Group (ed.), "Organic Materials for Imaging," Bunshin Shuppan (1993), pp. 187-192.

[0209] (4) Polymerization initiator assistant The ink of the present invention may further contain a polymerization initiator aid. The polymerization initiator aid may, for example, be a tertiary amine compound, and among these, an aromatic tertiary amine compound is preferred.

[0210] Examples of aromatic tertiary amine compounds include N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethylamino-p-benzoic acid ethyl ester, N,N-dimethylamino-p-benzoic acid isoamyl ethyl ester, N,N-dihydroxyethylaniline, triethylamine, and N,N-dimethylhexylamine.

[0211] Among them, the aromatic tertiary amine compound is preferably N,N-dimethylamino-p-benzoic acid ethyl ester or N,N-dimethylamino-p-benzoic acid isoamyl ethyl ester. These may be contained alone or in combination of two or more.

[0212] (5) Polymerization inhibitors The ink of the present invention may further contain a polymerization inhibitor. Examples of the polymerization inhibitor include (alkyl)phenols, hydroquinone, catechol, resorcin, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazyl, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, aluminum N-nitrosophenylhydroxylamine, tri-p-nitrophenylmethyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutyl cresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldoxime, methyl ethyl ketoxime, and cyclohexanone oxime.

[0213] (6)Other The ink of the present invention may further contain other components as necessary. The other components include various additives other than the additives described above, other resins, etc. The various additives other than the additives described above include, for example, surfactants, leveling additives, matting agents, ultraviolet absorbers, infrared absorbers, antibacterial agents, basic compounds for improving the storage stability of the ink, etc.

[0214] Examples of the basic compound include basic alkali metal compounds, basic alkaline earth metal compounds, and basic organic compounds such as amines. Examples of the other resin include resins for adjusting the physical properties of the cured film. Examples of the other resin include polyester, polyurethane, vinyl resin, acrylic resin, rubber-based resin, wax, and the like.

[0215] 6. Physical properties of active energy ray-curable ink composition The pigment dispersion composition of the present invention has excellent storage stability at 80° C. (high temperature). Accordingly, the ink of the present invention also has excellent storage stability at 80° C.

[0216] The ink of the present invention preferably has a viscosity at 80°C in the range of 3 to 20 mPa·s. This range ensures stable ejection of the ink from an inkjet head. Furthermore, the viscosity at 25°C is preferably 1000 mPa·s or more. This range allows the ink to gel sufficiently when cooled to room temperature after landing on a printing medium.

[0217] The ink preferably has a sol-gel phase transition temperature within the range of 40 to 70° C. When the ink has a phase transition temperature of 40° C. or higher, the ink is easily fixed since it thickens quickly after landing on a printing medium. Furthermore, when the ink has a phase transition temperature of 70° C. or lower, the ink can be ejected stably when the temperature at the time of ejection is set to about 80° C., which is normally used.

[0218] The viscosity of the ink at 25°C, the viscosity at 80°C, and the phase transition temperature can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer. For example, the ink is heated to 100°C, and while measuring the viscosity using a stress-controlled rheometer, the ink is cooled to 20°C under conditions of a shear rate of 11.7 (1 / s) and a temperature drop rate of 0.1°C / s to obtain a temperature change curve of the viscosity. Note that, for example, a "Physica MCR301" (cone plate diameter: 75 mm, cone angle: 1.0°, manufactured by Anton Paar) can be used as the stress-controlled rheometer.

[0219] The viscosities at 25°C and 80°C are determined by reading the viscosities at 25°C and 80°C, respectively, on the viscosity temperature curve. The phase transition temperature is determined as the temperature at which the viscosity becomes 200 mPa s on the viscosity temperature curve.

[0220] 7. Method for producing active energy ray-curable ink composition The method for producing an active energy ray-curable ink composition of the present invention includes a step of preparing the above-mentioned pigment dispersion composition, and is characterized in that the above-mentioned active energy ray-curable ink composition is produced. That is, first, the pigment dispersion composition is prepared, and then the pigment dispersion composition is mixed with other components to prepare an ink.

[0221] The pigment dispersion composition contains a polymerizable compound as a dispersion medium, and a further polymerizable compound may be added in the preparation (production) of the ink. The further polymerizable compound may be the same as the polymerizable compound used in the pigment dispersion composition. The further polymerizable compound may be a different type from the polymerizable compound contained in the pigment dispersion composition.

[0222] The method of mixing the components of the ink is not particularly limited, and they can be mixed by a known method. For example, other components of the ink may be added to the prepared pigment dispersion composition and mixed while heating. The obtained mixture is preferably filtered through a predetermined filter.

[0223] 8.Printing method The printing method of the present invention is characterized by using the above-mentioned active energy ray-curable ink composition.

[0224] The printing method of the present invention is preferably carried out by an inkjet method using the above ink. When a multicolor image is formed using a plurality of inks having different compositions, at least one of the plurality of inks may be the ink of the present invention.

[0225] In the printing method of the present invention, an inkjet printer is used. In general, inkjet printers are divided into on-demand type and continuous type depending on the ink ejection method. The inkjet printer used in the present invention may be of either type. Examples of on-demand type inkjet printers include electro-mechanical conversion type printers including single cavity type, double cavity type, bender type, piston type, share mode type, and shared wall type printers; and electro-thermal conversion type printers including thermal inkjet type and bubble jet (Bubble Jet is a registered trademark of Canon Inc.) type printers.

[0226] Inkjet printers are further divided into scan type and line type, depending on the scanning method of the head. The inkjet printer used in the present invention may be of either type. Either type may be selected depending on the resolution and printing speed of the printed matter (image). Since the ink of the present invention can be quickly fixed, a high-quality printed matter can be obtained even in high-speed printing using the line type.

[0227] The printing medium may be any printing medium on which an image can be formed using the ink of the present invention. Examples of the printing medium include non-absorbent printing media made of plastics including polyester, polyvinyl chloride, polyethylene, polyurethane, polypropylene, acrylic resin, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate, and polybutadiene terephthalate; non-absorbent inorganic printing media such as metals and glass; and papers such as printing coated paper and printing coated paper B.

[0228] Examples of the plastic film include a PP film, a PET film, an OPS film, an OPP film, an ONy film, a PVC film, a PE film, and a TAC film.

[0229] (1) The process of ejecting ink from the head In the step of ejecting the ink from the head, droplets of the ink are ejected from the nozzles of the head. The ejection method is not particularly limited.

[0230] The temperature of the ink inside the head is preferably within a range of 40 to 120° C., and more preferably within a range of 50 to 85° C. When the temperature of the ink inside the head is 40° C. or higher, the ejection stability of the ink from the head can be obtained. Also, when the temperature is 120° C. or lower, the volatilization of the ink components can be suppressed, and the thermal load on the head can be reduced.

[0231] When the temperature of the ink is within the range of 40 to 120° C., the viscosity of the ink is preferably within the range of 3 to 20 mPa·s.

[0232] It is also preferable to set the temperature of the ink in the head to be 10 to 40°C higher than the gelling temperature of the ink. By setting the temperature of the ink in the head to a gelling temperature + 10°C or higher, the ink does not gel inside the head or on the nozzle surface, and the ink can be ejected well. Furthermore, by setting the temperature of the ink in the head to a gelling temperature + 40°C or lower, the thermal load on the head can be reduced. In particular, in a head using a piezoelectric element, performance degradation due to thermal load is likely to occur, so it is preferable to set the temperature of the ink in the head within the above range.

[0233] The method of heating the ink is not particularly limited. For example, the ink can be heated by heating at least one of the ink supply system, the piping with a filter, the piezo head, etc., with a panel heater, a ribbon heater, warm water, etc. Examples of the ink supply system include an ink tank constituting the head carriage, a supply pipe, and a front chamber ink tank immediately before the head, etc.

[0234] From the viewpoint of printing speed and image quality, the amount of ink droplets ejected is preferably within the range of 2 to 20 pL.

[0235] (2) The process of depositing ink onto the print medium In the process of directly impacting ink on a print medium, the ink ejected in the previous process is impacted on the print medium.

[0236] From the viewpoint of fixing the ink, it is preferable that the temperature of the printing medium is lower than the temperature at which the ink is ejected, and is 60° C. or less. By keeping the temperature of the printing medium at 60° C. or less, the ink that has landed on the medium quickly thickens and can be fixed.

[0237] (3) A process of exposing the ink to active energy rays to harden the ink. In the process of irradiating the ink with active energy rays to cure the ink, the surface of the printing medium on which the ink has landed is irradiated with active energy rays.

[0238] As described above, examples of active energy rays include visible light, ultraviolet light, X-rays, electron beams, α rays, β rays, and γ rays. Among these, ultraviolet light is preferred from the viewpoint of ease of handling and minimal impact on the human body. Electron beams are preferred from the viewpoint of facilitating curing of the ink.

[0239] The ultraviolet light source is preferably a light-emitting diode (LED). By using an LED, it is possible to prevent the ink from melting due to the radiant heat of the light source, which can cause poor curing of the ink. Examples of LED light sources include water-cooled LEDs with a wavelength of 395 nm, such as those manufactured by Phoseon Technology, Heraeus, Kyocera, HOYA, and Integration Technology.

[0240] The amount of energy emitted by the active energy rays is 200 to 1000 mJ / cm 2 It is preferable that the amount of energy is within the range of 200 mJ / cm 2 By setting the energy amount to 1000 mJ / cm or more, the polymerizable compound can be sufficiently polymerized and crosslinked. 2 By setting the energy amount of the active energy rays to 300 to 800 mJ / cm or less, it is possible to suppress a decrease in the viscosity of the ink due to the heat of the active energy rays, and it is possible to suppress a decrease in the pinning property. 2 More preferably, it is within the range of 350 to 500 mJ / cm 2 It is more preferable that the ratio is within the range of 1.

[0241] (4) Drying the ink In the step of drying the ink, the ink is irradiated with active energy rays and then dried as necessary. The drying method may be air drying or drying by applying heat, but drying by applying heat is preferred.

[0242] 9. Printing System A printing system according to the present invention includes the ink described above. The printing system according to the present invention is a system that prints by ejecting the ink described above onto a printing medium. That is, the printing system according to the present invention includes a printing device and the ink described above.

[0243] The printing device of the printing system of the present invention will be described below. Note that, although the device that performs printing by a single pass method will be described below, the ink of the present invention can also be used in a device that performs printing by a scan method.

[0244] FIG. 1 is a schematic diagram showing an exemplary configuration of a printing device 100 used in the present invention. As shown in FIG. 1, the printing device 100 has an inkjet head 110, a transport path 120, an active energy ray irradiation unit 130, and a temperature control unit 140. In FIG. 1, an arrow A indicates the transport direction of a print medium 150. The inkjet head 110 and the active energy ray irradiation unit 130 are arranged in this order in contact with the transport path 120 from the upstream side to the downstream side in the transport direction of the print medium. The printing device 100 may have an oxygen concentration adjustment unit (not shown) for adjusting the oxygen concentration when the ink is irradiated with active energy rays.

[0245] 1, the printing device 100 has an ink flow path 170 and an ink tank 180 that stores ink to be supplied through the ink flow path 170. The ink flow path 170 is connected to a head carriage 160 that houses an inkjet head 110 for ink.

[0246] The head carriages 160 each house an inkjet head 110. The head carriages 160 include inkjet heads for each of the colors yellow (Y), magenta (M), cyan (C), and black (K). The head carriage 160 is fixedly disposed so as to cover the entire width of the print medium 150, for example.

[0247] The ink tanks 180 contain inks of various colors. Ink is supplied to the inkjet head 110 from the ink tanks 180. The ink of the present invention may be used for all of the inks of yellow (Y), magenta (M), cyan (C) and black (K), or may be used for only some of the inks. Of these, it is preferable to use the ink of the present invention for the cyan ink, magenta ink or black ink.

[0248] The inkjet head 110 ejects ink supplied from the ink tank 180 to the head carriage 160 via the ink flow path 170. At this time, it is preferable to heat the ink via the ink tank 180, the ink flow path 170, the head carriage 160, the inkjet head 110, etc. As described above, the temperature of the ejected ink is preferably within a range of 40 to 120°C, and more preferably within a range of 50 to 85°C.

[0249] The active energy ray irradiation unit 130 covers the entire width of the printing medium 150, and is disposed downstream of the head carriage 160 in the transport direction A of the printing medium 150. The active energy ray irradiation unit 130 irradiates the ink droplets that are ejected by the inkjet heads 110 and land on the printing medium 150 with active energy rays, thereby curing the droplets.

[0250] The temperature control unit 140 is disposed on the lower surface of the printing medium 150. The temperature control unit 140 adjusts the surface temperature of the printing medium 150 to 60° C. or less, lower than the temperature at which the ink is ejected. Examples of the temperature control unit 140 include various heaters. This allows the ink of the present invention to be quickly fixed after landing on the printing medium 150. Therefore, the ink of the present invention has high pinning properties and can suppress the seepage of the polymerizable compound from the formed dots.

[0251] Furthermore, an oxygen concentration adjusting section (not shown) adjusts the oxygen concentration of the atmosphere surrounding the surface of the ink that has landed on the print medium 150 when irradiating it with active energy rays. EXAMPLES

[0252] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the examples, the terms "parts" and "%" are used, but they represent "parts by mass" or "% by mass" unless otherwise specified. In the following examples, operations were carried out at room temperature (25° C.) unless otherwise specified.

[0253] 1. Preparation of Pigment Dispersion Composition (1) Preparation of Pigment Dispersion Composition 1 The following components and 0.3 mm zirconia beads "YTZ balls" (manufactured by Nikkato Corporation) were placed in a 100 mL plastic container. The mixture was dispersed for 3 hours using a paint shaker, and the zirconia beads were then removed to obtain pigment dispersion composition 1.

[0254] Cyan pigment "Paliogen(R) Blue EH 1900" (DIC Corporation) 20.0 parts by mass Polymer pigment dispersant "Ajisper PB881" (manufactured by Ajinomoto Fine-Techno Co., Ltd.) 6.5 parts by mass Phenol EO modified acrylate "Miramer (registered trademark) M144" (manufactured by MIWON) 73.2 parts by mass Photopolymerization inhibitor "Irgastab (registered trademark) UV10" (manufactured by BASF) 0.3 parts by mass

[0255] (2) Preparation of Pigment Dispersion Compositions 2 to 20 Pigment dispersion compositions 2 to 20 were obtained in the same manner as in Pigment dispersion composition 1, except that the pigment, dispersant, and dispersion medium were changed as shown in Table I.

[0256] 2. Ink Preparation (1) Preparation of Ink 1 The obtained pigment dispersion composition 1 was mixed with the following components and stirred for 45 minutes at 105° C. The mixture was then filtered through a 3 μm membrane filter (Teflon (registered trademark) manufactured by ADVANTEC Corporation) to obtain ink 1.

[0257] Pigment dispersion composition 1 (solid content concentration: 26.5% by mass) 10.0 parts by mass Polyethylene glycol #400 diacrylate 43.9 parts by weight 4EO modified pentaerythritol tetraacrylate 25.0 parts by mass 3PO modified trimethylolpropane triacrylate 15.0 parts by mass Photopolymerization initiator "IRGACURE (registered trademark) 819" (BASF) 6.0 parts by mass Photopolymerization inhibitor "Irgastab (registered trademark) UV10" (manufactured by BASF) 0.1 part by mass

[0258] (2) Preparation of Inks 2 to 20 Inks 2 to 20 were prepared in the same manner as in the preparation of Ink 1, except that the types and contents of the pigment, dispersant, and additives were changed as shown in Table II.

[0259] 3. Evaluation (1) Storage stability of pigment dispersion composition at high temperatures (evaluation of pigment dispersion composition) The volume average particle size of the pigment in each pigment dispersion composition was measured using a particle size analyzer "Zetasizer Nano S" (manufactured by Malvern Panalytical Co., Ltd.) Then, each pigment dispersion composition was stored at 80°C for one week, and the volume average particle size of the pigment was then measured using the same device.

[0260] The amount of change in the volume average particle size of the pigment before and after storage at high temperature (80° C.) was calculated and evaluated according to the following criteria: C or higher (A to C) was deemed to be acceptable for practical use. A: The change in particle size is 5 nm or less. B: The change in particle size is within the range of more than 5 nm and 10 nm or less. C: The change in particle size is within the range of more than 10 nm and 20 nm or less. D: The change in particle size is more than 20 nm.

[0261] (2) Migration of printed materials (evaluation of printed materials) Printing was performed using each ink, and the printed matter was evaluated. An inkjet recording device "KM512MHX" (manufactured by Konica Minolta) having an inkjet recording head was prepared. The inkjet recording head was equipped with a piezoelectric type inkjet nozzle.

[0262] Each ink was ejected from this inkjet recording device. 2 A solid image of 10 cm×10 cm was formed at a resolution of 720×720 dpi on a paper roll (Oji Paper Co., Ltd.). The solid image was then irradiated with 450 nm UV light for a cumulative total of 350 mJ.

[0263] A total of five prints obtained in the same manner were immersed in a container containing 100 mL of water at 40°C for 72 hours. The coated printing paper on which the solid image was formed was then removed from the container. The water in the container was then removed under reduced pressure, and the amount of residue was measured and evaluated according to the following criteria. A grade of C or higher (A to C) was deemed to be acceptable for practical use. In this case, "migration" refers to the phenomenon in which part of the ink is not sufficiently fixed to the coated paper and migrates from the coated paper. Part of the ink migrates from the coated paper and dissolves in the water in which it is immersed. When the water is removed from the liquid in the container after immersion, part of the migrated ink precipitates as a residue. This residue includes the components of the ink, particularly the pigment, polymerizable compound, etc.

[0264] A: The amount of residue is less than 3 mg. B: The amount of residue is more than 3 mg and less than 10 mg. C: The amount of residue is more than 10 mg and less than 20 mg. D: The amount of residue is more than 20 mg.

[0265] The configurations of pigment dispersion compositions 1 to 20 and inks 1 to 20 are shown in Tables I and II. The evaluation results of each ink are also shown in Tables I and II.

[0266] Details of the pigments, dispersants and dispersion media set forth in Tables I and II are provided below. (Pigments) EH 1900: "Paliogen (registered trademark) Blue EH 1900" (DIC Corporation) 6112JC: "Chromofine (registered trademark) Red 6112JC" (manufactured by Dainichiseika Color & Chemicals Co., Ltd.) RGT: "FASTOGEN (registered trademark) SUPER MAGENTA RGT" (DIC Corporation) JM04: "FASTOGEN (registered trademark) SUPER MAGENTA JM04" (DIC Corporation) 5R-763: "5R-763" (manufactured by Fuji Pigment Co., Ltd.) 6B 690: "6B 690" (manufactured by Fuji Pigment Co., Ltd.) MA-7: "Mitsubishi (registered trademark) Carbon Black MA-7" (manufactured by Mitsubishi Chemical Corporation) 7061B: "FASTOGEN (registered trademark) SUPER RED 7061B" (Pigment Violet-19, manufactured by DIC Corporation) Pigments other than "7061B" contain compounds having sulfo groups or sulfonic acid derivative groups. "7061B" mainly contains quinacridones that do not have sulfo groups or sulfonic acid derivative groups.

[0267] (Dispersant) PB881: "Ajispar PB881" (manufactured by Ajinomoto Fine-Techno Co., Ltd.) Solsperse 32000: "Solsperse 32000" (manufactured by Lubrizol Japan) Solsperse 33000: "Solsperse 33000" (manufactured by Lubrizol Japan) PB824: "Ajispar PB824" (manufactured by Ajinomoto Fine-Techno Co., Ltd.) PB821: "Ajispar PB821" (manufactured by Ajinomoto Fine-Techno Co., Ltd.) TEGO Dispers 650: "TEGO (registered trademark) Dispers 650" (manufactured by Evonik Japan) Dispersants other than TEGO Dispers 650 contain polyallylamine with alkyl ester side chains. TEGO Dispers 650 mainly contains polyether compounds.

[0268] (dispersion medium) M144: "Miramer (registered trademark) M144" (CLogP value: 2.27, phenol EO modified acrylate, manufactured by MIWON) M222: "Miramer (registered trademark) M222" (CLogP value: 2.04, dipropylene glycol diacrylate, manufactured by MIWON) M216: "Miramer (registered trademark) M216" (CLogP value: 3.33, neopentyl glycol PO-modified diacrylate, manufactured by MIWON Co., Ltd.) M220: "Miramer (registered trademark) M220" (CLogP value: 2.17, tripropylene glycol diacrylate, manufactured by MIWON) D0498: Diethylene glycol divinyl ether (product code: D0498, CLogP value: 0.468, manufactured by Tokyo Chemical Industry Co., Ltd.) P2928: Polyethylene glycol diglycidyl ether (product code: P2928, CLogP value: -4.36, manufactured by Tokyo Chemical Industry Co., Ltd.) M144 is a compound having a repeating unit derived from ethylene oxide (EO modified), M222, M216 and M220 are compounds having a repeating unit derived from propylene oxide (PO modified).

[0269] [Table 1]

[0270] [Table 2]

[0271] From the examples and comparative examples, it is understood that the pigment dispersion composition of the present invention can improve the dispersibility of the pigment. Specifically, the dispersibility of the pigment at high temperatures is improved, and the migration of the pigment in the printed matter can be suppressed.

[0272] A comparison of Examples 1 to 5 shows that the dispersibility of the pigment can be improved by setting the CLogP value of the dispersion medium within the range of 2.0 to 2.4. [Explanation of symbols]

[0273] 100 Printing equipment 110 Inkjet head 120 Transport Path 130 Active energy ray irradiation section 140 Temperature control unit 150 Print media 160 Head Carriage 170 Ink flow path 180 Ink Tank

Claims

1. A pigment dispersion composition comprising a pigment, a dispersant, and a dispersion medium, The pigment has a sulfo group or a sulfonic acid derivative group, and The dispersant is a polyallylamine having alkyl ester side chains. A pigment dispersion composition comprising:

2. The dispersion medium is an acrylate or a methacrylate. The pigment dispersion composition according to claim 1 .

3. The predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.

4. The pigment dispersion composition according to claim 1 .

4. The acrylate or methacrylate has a repeating structure derived from ethylene oxide or propylene oxide. The pigment dispersion composition according to claim 2 .

5. The dispersant has a repeating structure represented by the following general formula (1): The pigment dispersion composition according to claim 1 . 【Chemistry 1】 (In general formula (1), m is an integer in the range of 2 to 100, and n is an integer in the range of 2 to 20.)

6. A dispersion composition comprising a dispersant and a dispersion medium, the dispersant is a polyallylamine having alkyl ester side chains; The predicted 1-octanol / water partition coefficient CLogP value of the dispersion medium is within the range of 2.0 to 2.

4. A dispersion composition comprising:

7. A pigment dispersion composition according to any one of claims 1 to 5 is contained.

1. An actinic ray-curable ink composition comprising:

8. Further contains a gelling agent The actinic ray-curable ink composition according to claim 7 .

9. preparing a pigment dispersion composition; A method for producing the active energy ray-curable ink composition according to claim 7. The present invention relates to a method for producing an active energy ray-curable ink composition.

10. The active energy ray curable ink composition according to claim 7 is used. A printing method comprising:

11. The active energy ray curable ink composition according to claim 7 is included. A printing system comprising:

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