Inkjet ink composition, recorded matter, inkjet recording method, and inkjet recording system

Abstract

To provide: an inkjet ink composition which achieves both sufficient hardness and adhesion as a recorded matter, suppresses an increase in viscosity during long-term storage or retention and can suppress fluctuations in particle size and the generation of precipitates; a recorded matter; an inkjet recording method; and a recording system.SOLUTION: There is provided an inkjet ink composition which is cured by an active energy beam or heat and contains a compound having a structure represented by the general formula (1) or a salt thereof (A) and a hyperbranched acrylate oligomer or a polymer (B). (wherein, X represents a substituent having at least one selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group and their derivatives at the terminal. Q represents an oxygen atom or NR4, R4 represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an inkjet ink composition, a recorded matter, an inkjet recording method, and an inkjet recording system, and in particular to an inkjet ink composition and the like that can simultaneously achieve sufficient hardness and adhesion as a recorded matter, suppress an increase in viscosity during long-term storage or retention, and suppress fluctuations in particle size and the occurrence of precipitates. [Background technology]

[0002] In order to protect the circuit pattern on the printed wiring board of a printed circuit board, an insulating film (solder resist film) is formed by applying and curing ink. For example, an inkjet method is known as a method for forming the solder resist film. More specifically, inkjet ink (hereinafter simply referred to as "ink") is applied, cured by light, and then cured by heat.

[0003] Patent Document 1 discloses an inkjet ink for resist containing a photopolymerizable compound having an acidic group. Photopolymerizable compounds having an acidic group, such as carboxyl, phosphate, and sulfonic acid groups, have been used. However, when photopolymerizable compounds having a phosphate or sulfonic acid group are used, the viscosity and particle size of the ink tend to increase due to pigment aggregation. This creates problems, such as fluctuations in the ejection rate and clogging of the inkjet head filter, particularly when the ink remains at high temperatures in the ink pack or inkjet head. Furthermore, when photopolymerizable compounds having a carboxyl group are used, the viscosity and particle size are less likely to increase compared to compounds having a phosphate or sulfonic acid group, but there is a problem in that it is difficult to obtain sufficient hardness and adhesion as a resist film.

[0004] Patent Document 2 discloses a technology relating to an adhesive composition characterized by containing an acrylic resin, an ionic compound, and a polymeric carbodiimide. However, because the carbodiimide compound has a mechanism of suppressing hydrolysis by reacting with carboxylic acid, there is a problem that when used in inkjet ink, the viscosity of the ink tends to increase. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-37645 [Patent Document 2] Japanese Patent Application Publication No. 2018-178468 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above problems and circumstances, and an object of the present invention is to provide an inkjet ink composition, a recorded matter, an inkjet recording method, and an inkjet recording system that can achieve both sufficient hardness and adhesion as a recorded matter (e.g., a resist film), suppress an increase in viscosity during long-term storage or retention, and suppress fluctuations in particle size and the occurrence of precipitates. [Means for solving the problem]

[0007] In the course of investigating the causes of the above problems in order to solve them, the present inventors discovered that, among photopolymerizable compounds having a carboxy group, the use of a compound having a specific structure makes it difficult for pigment aggregation to occur and provides sufficient hardness and adhesion for a recorded product (e.g., a resist film). However, when using the compound having the specific structure, a hydrolyzed product precipitates in a high-temperature, high-humidity environment, causing problems such as clogging of the inkjet head filter. Therefore, the inventor discovered that by incorporating a compound having a specific structure and a hyperbranched acrylate oligomer or polymer, it is possible to achieve both sufficient hardness and adhesion as a recorded matter, suppress an increase in viscosity during long-term storage or retention, suppress fluctuations in particle size, and suppress hydrolysis even in high-temperature, high-humidity environments, thereby suppressing the occurrence of precipitates, thereby arriving at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. An inkjet ink composition that is curable by actinic radiation or heat, A compound (A) having a structure represented by the following general formula (1) or a salt thereof, Hyperbranched acrylate oligomer or polymer (B) and And, The content of the compound having a structure represented by the general formula (1) or its salt (A) is within a range of 3 to 20 mass %, and the content of the hyperbranched acrylate oligomer or polymer (B) is within a range of 10 to 30 mass %. An ink-jet ink composition comprising: [ka] [In the general formula (1), X represents a substituent having at least one group selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and derivatives thereof at its terminal.] Q represents an oxygen atom or NR4, and R4 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.]

[0009] 2. The ink-jet ink composition according to item 1, wherein in the general formula (1), X represents an acryloyl group or a methacryloyl group.

[0010] 3. The ink-jet ink composition according to item 1 or 2, wherein in the general formula (1), Q represents an oxygen atom.

[0011] 4. The ink-jet ink composition according to any one of items 1 to 3, wherein in the general formula (1), R1 represents an unsubstituted alkylene group having 1 or 2 carbon atoms.

[0012] 5. The inkjet ink composition according to any one of items 1 to 4, further comprising a polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B).

[0013] 6. The polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B) is caprolactam. ton 6. The ink-jet ink composition according to item 5, characterized in that it is a modified dipentaacrylate.

[0014] 7. The ink-jet ink composition according to any one of items 1 to 6, further comprising a (meth)acrylate compound (D) having a ClogP value in the range of 4.0 to 7.0.

[0015] 8. The ink-jet ink composition according to any one of items 1 to 7, further comprising a gelling agent (E).

[0016] 9. The ink-jet ink composition according to any one of items 1 to 8, which is used as an ink-jet ink for forming a solder resist pattern used on a printed circuit board.

[0017] 10. A recorded matter obtained by curing the inkjet ink composition according to any one of items 1 to 9 with actinic energy rays or heat.

[0018] 11. An inkjet recording method using an inkjet ink composition, comprising: Item 10. An ink-jet ink composition according to any one of items 1 to 9 is used, and a step of ejecting the inkjet ink composition from an inkjet head and landing it on a recording medium; and curing the inkjet ink composition that has landed on the recording medium with actinic energy rays or heat.

[0019] 12. An inkjet recording system using an inkjet ink composition, comprising: Item 10. An ink-jet ink composition according to any one of items 1 to 9 is used, and an inkjet recording system comprising an inkjet head that ejects the inkjet ink composition, an actinic energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with actinic energy rays, and a heating unit that heats the inkjet ink composition that has been irradiated with the actinic energy rays. [Effects of the Invention]

[0020]

[0016] The above-described means of the present invention can provide an inkjet ink composition, a recorded matter, an inkjet recording method, and an inkjet recording system that can achieve both sufficient hardness and adhesion as a recorded matter, suppress an increase in viscosity during long-term storage or retention, and suppress fluctuations in particle size and the occurrence of precipitates. The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0021] In general, compounds with ester bonds (or amide bonds) are hydrolyzed in the presence of water and acid to produce alcohols (or amines) and carboxylic acids. This reaction is an equilibrium reaction. The compound (A) having a structure represented by the general formula (1) or its salt in the present invention has a dicarboxylic acid structure, and coordinates to a metal substrate to adhere more firmly than a general carboxylic acid acrylate. However, the dicarboxylic acid generated by hydrolysis has low solubility in the monomer and is prone to precipitation. On the other hand, the hyperbranched acrylate oligomer or polymer (B) also has an acrylate structure, and it is thought that there is a possibility that unreacted hydroxyl groups remain in the molecule, or that hydroxyl groups are generated by hydrolysis. In addition, because it has a branched structure, it is thought that there is a possibility that one molecule contains multiple hydroxyl groups. Therefore, it is presumed that by using the compound or its salt (A) in combination with the hyperbranched acrylate oligomer or polymer (B), the concentration of hydroxy groups in the ink increases, and the equilibrium of the hydrolysis reaction of the compound or its salt (A) can be shifted toward the ester side, thereby suppressing hydrolysis. Furthermore, since the hyperbranched acrylate oligomer or polymer (B) has a branched structure, it may contain multiple hydroxyl groups in one molecule, and it is presumed that this can more efficiently suppress hydrolysis than using a hydroxyl group-containing compound other than the hyperbranched acrylate oligomer or polymer (B) in combination. DETAILED DESCRIPTION OF THE INVENTION

[0022] The inkjet ink composition of the present invention is an inkjet ink composition that is cured by actinic energy rays or heat, and is characterized by containing a compound (A) having a structure represented by the following general formula (1) or a salt thereof, and a hyperbranched acrylate oligomer or polymer (B): [ka] [In the general formula (1), X represents a substituent having at least one group selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and derivatives thereof at its terminal.] Q represents an oxygen atom or NR4, and R4 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0023] As an embodiment of the present invention, in the general formula (1), X represents an acryloyl group or a methacryloyl group, which is preferable in terms of improving the reactivity of the compound (A) having a structure represented by the general formula (1) or a salt thereof and improving adhesion. Furthermore, the substituent represented by X preferably has a total carbon number of 50 or less, more preferably 30 or less, in order to reduce the viscosity of the ink and improve inkjet suitability. In addition, in the general formula (1), it is preferable that Q represents an oxygen atom in order to improve adhesion. In addition, in the general formula (1), it is preferable that R1 represents an unsubstituted alkylene group having 1 or 2 carbon atoms in terms of enhancing adhesiveness.

[0024] It is preferable to further contain a polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B) in order to increase the hardness of the coating film. The polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B) is a caprolactam. ton A modified dipentaacrylate is preferred in that it inhibits hydrolysis of the compound having the structure represented by the general formula (1) or the salt thereof (A) and also improves acid resistance and alkali resistance.

[0025] It is preferable to further contain a (meth)acrylate compound (D) having a ClogP value in the range of 4.0 to 7.0, in order to reduce the water absorption rate of the ink and suppress hydrolysis of the compound having a structure represented by general formula (1) or its salt (A).

[0026] The inclusion of a gelling agent (E) is preferred because it can gelatinize the ink on the recording medium and temporarily fix it, thereby suppressing the ink from spreading. Furthermore, by reducing the water absorption of the ink, it is possible to suppress the hydrolysis of the compound having the structure represented by general formula (1) or its salt (A).

[0027] The inkjet ink composition of the present invention is preferably used as an inkjet ink for forming a solder resist pattern used on a printed circuit board, and is also preferably used for recorded materials cured by actinic energy rays or heat.

[0028] The inkjet recording method of the present invention is an inkjet recording method using an inkjet ink composition, characterized by comprising: a step of using the inkjet ink composition and ejecting the inkjet ink composition from an inkjet head to land on a recording medium; and a step of curing the inkjet ink composition that has landed on the recording medium by actinic energy rays or heat. This makes it possible to obtain a printed matter having excellent hardness and adhesion, and also to suppress an increase in viscosity during long-term storage or retention, and to suppress fluctuations in particle size and the occurrence of precipitates.

[0029] The inkjet recording system of the present invention is an inkjet recording system that uses an inkjet ink composition, and is characterized by having an inkjet head that uses the inkjet ink composition and ejects the inkjet ink composition, an actinic energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with actinic energy rays, and a heating unit that heats the inkjet ink composition that has been irradiated with the actinic energy rays. This makes it possible to obtain a printed matter having excellent hardness and adhesion, and also to suppress an increase in viscosity during long-term storage or retention, and to suppress fluctuations in particle size and the occurrence of precipitates.

[0030] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0031] [Inkjet ink composition of the present invention] The inkjet ink composition of the present invention is an inkjet ink composition that is cured by actinic energy rays or heat, and is characterized by containing a compound (A) having a structure represented by the following general formula (1) or a salt thereof, and a hyperbranched acrylate oligomer or polymer (B): [ka] [In the general formula (1), X represents a substituent having at least one group selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and derivatives thereof at its terminal.] Q represents an oxygen atom or NR4, R4 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and R1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.]

[0032] The inkjet ink composition of the present invention functions as an insulating film (solder resist) by being applied to a substrate and cured with light or heat in various fields, such as metal processing, electronic circuits, printed circuit boards, plate making, semiconductors, color filters, etc. Furthermore, since the inkjet ink composition can be removed with alkali after photocuring, it also functions as an etching resist used when forming an etching pattern on a substrate. Specifically, the ink-jet ink composition of the present invention is patterned by ink-jet printing on a conductive oxide film of copper, zinc, or the like formed on a substrate, and then cured with light to form a resist film. Next, the oxide film in the areas not covered by the resist film is removed with an acid etching solution, and the resist film covering the oxide film is further removed with an alkali, thereby forming a precise circuit or pattern. In addition to the above applications, the composition can also be suitably used for the purpose of patterning a film that has both adhesion and hardness on a substrate having an inorganic surface, such as a metal or glass substrate.

[0033] The ink-jet ink composition of the present invention is an ink composition that can be cured by actinic radiation. "Actinic rays" refer to rays that can impart energy to generate initiating species in the ink composition upon irradiation, and include α-rays, γ-rays, X-rays, ultraviolet rays, electron beams, etc. Among these, ultraviolet rays and electron beams are preferred from the viewpoint of curing sensitivity and ease of equipment availability, and ultraviolet rays are more preferred.

[0034] [1. Compound (A) having a structure represented by general formula (1) or a salt thereof] The ink-jet ink composition of the present invention (hereinafter also simply referred to as "ink") contains the compound (A) having a structure represented by the general formula (1) or a salt thereof, thereby achieving both hardness and adhesion as a recorded product and suppressing fluctuations in viscosity and particle size during long-term storage and retention.

[0035] In the general formula (1), X preferably represents an acryloyl group or a methacryloyl group, in order to improve the reactivity of the compound (A) having the structure represented by the general formula (1) or its salt and to improve adhesion. Furthermore, the substituent represented by X preferably has a total carbon number of 50 or less, more preferably 30 or less, in order to reduce the viscosity of the ink and improve inkjet suitability. In addition, in the general formula (1), it is preferable that Q represents an oxygen atom in order to improve adhesion. In addition, in the general formula (1), it is preferable that R1 represents an unsubstituted alkylene group having 1 or 2 carbon atoms in terms of enhancing adhesiveness. Furthermore, it is preferable that the compound having the structure represented by the general formula (1) is not a salt, in terms of improving compatibility with other monomers, increasing the hydrophobicity of the ink, and suppressing hydrolysis of the compound having the structure represented by the general formula (1) or its salt (A).

[0036] Specific examples of compounds having a structure represented by the general formula (1) or salts thereof are shown below, but the present invention is not limited to these.

[0037] [ka]

[0038] [ka]

[0039] The greater the content of the compound having a structure represented by general formula (1) or its salt (A), the greater the contribution to hardness and adhesion. However, if the content is too high, it will promote its own hydrolysis as an acid catalyst. Therefore, the content is preferably in the range of 1 to 50% by mass, and more preferably in the range of 3 to 20% by mass, based on the total mass of the ink.

[0040] [2. Hyperbranched acrylate oligomer or polymer (B)] By containing the hyperbranched acrylate oligomer or polymer (B), the ink of the present invention can suppress hydrolysis of the compound having a structure represented by the general formula (1) or its salt (A), thereby suppressing precipitation.

[0041] The hyperbranched acrylate oligomer according to the present invention is an acrylate oligomer having a hyperbranched (hyperbranched) structure.

[0042] In the present invention, the term "oligomer" refers to a compound in which the number of monomer bonds (degree of polymerization) is in the range of 2 to 10 and the weight-average molecular weight is in the range of 500 to 15,000. In the present invention, the term "polymer" refers to a compound having a bonding number (degree of polymerization) of 11 or more monomers and a weight-average molecular weight of more than 10,000. The polymer according to the present invention is preferably a polymer of the above-mentioned oligomer, for example.

[0043] In addition, in the present invention, the term "hyperbranched structure" refers to a dendritic compound having multiple branching points within one molecule, and is synthesized, for example, by the self-condensation of an AB2 type molecule having two types of substituents in one molecule, totaling three or more, or by the A2+B3 method, which is a condensation reaction between two molecules (A2 type, B3 type). Therefore, the hyperbranched structure in the present invention includes a dendrimer structure (tree-like structure), a star structure, and a graft structure.

[0044] Examples of commercially available hyperbranched acrylate oligomers include V#1000 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), CN2302, CN2303, CN2304 (all manufactured by Sartomer Co., Ltd.), SP1106 (all manufactured by Miwon Co., Ltd.), 6361-100, 6363 (manufactured by Choko Scientific Industrial Co., Ltd.), etc. These may be used alone or in combination of two or more.

[0045] The higher the content of the hyperbranched acrylate oligomer or polymer (B), the more it contributes to inhibiting the hydrolysis of the compound having a structure represented by general formula (1) or its salt (A). However, if the content is too high, the viscosity of the ink increases too much, making it difficult to eject the ink from an inkjet head. Therefore, the content is preferably in the range of 5 to 50% by mass, more preferably in the range of 10 to 30% by mass, based on the total ink.

[0046] [3. Polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups, which is not a hyperbranched acrylate oligomer or polymer] The ink of the present invention is preferable in that it contains a polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups (hereinafter simply referred to as "polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups") that is not the hyperbranched acrylate oligomer or polymer, and thereby the hardness of the coating film can be further increased. The polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups generally has large cure shrinkage and is prone to impairing adhesion to the substrate, but by using it in combination with the compound having a structure represented by general formula (1) or a salt thereof (A), the hardness of the coating film can be significantly increased while maintaining the necessary adhesion. Furthermore, from the viewpoint of increasing the hardness of the coating film, the polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups preferably has five or more (meth)acryloyl groups, and more preferably six or more (meth)acryloyl groups.

[0047] The ink of the present invention may contain only one type of polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups, or may contain multiple types of polyfunctional (meth)acrylate (C).

[0048] Examples of (meth)acrylates having three (meth)acryloyl groups (also referred to as "trifunctional (meth)acrylates") include trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, glycerin propoxy tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tri(meth)acrylates in which the three hydroxy groups of a triol obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane are substituted with (meth)acryloyloxy groups.

[0049] Examples of (meth)acrylates having four (meth)acryloyl groups (also called "tetrafunctional (meth)acrylates") include ditrimethylolpropane tetra(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate. Examples of (meth)acrylates having five (meth)acryloyl groups (also referred to as "pentafunctional (meth)acrylates") include dipentaerythritol penta(meth)acrylate. Examples of (meth)acrylates having six (meth)acryloyl groups (also called "hexafunctional (meth)acrylates") include dipentaerythritol hexa(meth)acrylate.

[0050] The (meth)acrylate may be a modified product. Examples of modified (meth)acrylates include ethylene oxide-modified (meth)acrylates such as ethylene oxide-modified trimethylolpropane tri(meth)acrylate and ethylene oxide-modified pentaerythritol tetra(meth)acrylate, propylene oxide-modified (meth)acrylates such as propylene oxide-modified trimethylolpropane tri(meth)acrylate and propylene oxide-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified (meth)acrylates such as caprolactone-modified trimethylolpropane tri(meth)acrylate, and caprolactone-modified (meth)acrylates such as caprolactone-modified trimethylolpropane tri(meth)acrylate. ton Caprolactam containing modified dipentaerythritol hexa(meth)acrylate ton Modified (meth)acrylates and the like are included. In particular, Caprolactam ton Modified dipentaerythritol hexaacrylate is particularly preferred because it can reduce the water absorption of the ink, thereby suppressing hydrolysis of the compound having a structure represented by general formula (1) or its salt (A), and further improving acid resistance and alkali resistance.

[0051] Examples of commercially available (meth)acrylates include M500 (pentafunctional acrylate, manufactured by Sartomer Co.), M600 (hexafunctional acrylate, manufactured by Sartomer Co.), and the like. Caprolactam ton Examples of commercially available modified dipentaerythritol hexaacrylates include DPCA20, DPCA30, DPCA60, and DPCA120 (all hexafunctional acrylates, manufactured by Nippon Kayaku Co., Ltd.).

[0052] The content of the polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups is preferably within a range of 5 to 50% by mass, more preferably within a range of 10 to 30% by mass, based on the total mass of the ink.

[0053] [4. (Meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0] The ink of the present invention preferably contains a (meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0, in order to reduce the water absorption rate of the ink and suppress hydrolysis of the compound having a structure represented by general formula (1) or its salt (A).

[0054] Examples of the (meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0 include propoxylated (2) neopentyl glycol diacrylate (molecular weight 471, ClogP 4.9), 1,10-decanediol dimethacrylate (molecular weight 310, ClogP 5.75), tricyclodecane dimethanol diacrylate (molecular weight 304, ClogP 4.69), and tricyclodecane dimethanol dimethacrylate (molecular weight 332, ClogP 5.12).

[0055] Examples of commercially available (meth)acrylate (D) products having a ClogP value within the range of 4.0 to 7.0 include SR834 (manufactured by Sartomer) (tricyclodecane dimethanol dimethacrylate), NK Ester DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.) (1,10-decanediol dimethacrylate), NK Ester NOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.) (1,9-nonanediol dimethacrylate), NK Ester A-DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.) (1,10-decanediol diacrylate), and NK Ester A-NOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.) (1,10-nonanediol diacrylate).

[0056] Furthermore, it is more preferable that the (meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0 is contained in an amount in the range of 10 to 40 mass % based on the total mass of the ink, in order to suppress hydrolysis of the compound having a structure represented by general formula (1) or a salt thereof (A).

[0057] Here, the "logP value" as used herein is a coefficient indicating the affinity of an organic compound for water and 1-octanol. The 1-octanol / water partition coefficient P is the distribution equilibrium when a trace amount of a compound is dissolved as a solute in two liquid phases of 1-octanol and water. It is the ratio of the concentrations of hydroxyl groups and hydroxyl groups to the logarithm logP of the base 10. That is, 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.

[0058] The "ClogP value" refers to a logP value calculated by calculation. The ClogP value can be calculated by the fragment method, the atomic approach method, or the like. More specifically, the ClogP value can be calculated using 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)) or the commercially available software package 1 or 2 listed below. Software package 1: MedChem Software (Release 3.54, August 1991, Medicinal Chemistry Project, Pomona College, Claremont, CA), Software package 2: ChemDraw Ultra ver. 8.0 (April 2003, CambridgeSoft Corporation, USA) The numerical values ​​of the ClogP values ​​described in the present specification and elsewhere are "ClogP values" calculated using Software Package 2.

[0059] [5. Polymerization initiator] The ink of the present invention can be cured by radical polymerization or ionic polymerization, but in the present invention, it is preferable to use a radical polymerization initiator as the polymerization initiator. The ink of the present invention may contain only one type of polymerization initiator, or may contain two or more types of polymerization initiators.

[0060] Examples of the radical polymerization initiator include an α-cleavage type radical polymerization initiator (also referred to as a "Norrish type I polymerization initiator") and a hydrogen abstraction type radical polymerization initiator (also referred to as a "Norrish type II polymerization initiator").

[0061] The content of the α-cleavage type radical polymerization initiator is preferably within a range of 0.3 to 6% by mass relative to the total mass of the ink of the present invention, and the content of the hydrogen abstraction type radical polymerization initiator is preferably within a range of 0.5 to 10% by mass relative to the total mass of the ink of the present invention.

[0062] The α-cleavage type radical polymerization initiator is an initiator that cleaves after photoexcitation to directly give an initiating radical. A hydrogen abstraction radical polymerization initiator is a photopolymerization initiator that is activated by active energy rays (e.g., ultraviolet light) to generate free radicals by abstracting hydrogen from a second compound, which then becomes the actual initiating free radical. This second compound is called a polymerization synergist or coinitiator. Both the α-cleavage type radical polymerization initiator and the hydrogen abstraction type radical polymerization initiator can be used alone or in combination in the present invention.

[0063] Examples of the α-cleavage type radical polymerization initiator include acetophenone-based initiators, benzoin-based initiators, acylphosphine oxide-based initiators, benzyl and methylphenyl glyoxyesters.

[0064] Examples of acetophenone-based initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzil 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.

[0065] Examples of benzoin-based initiators include benzoin, benzoin methyl ether, and benzoin isopropyl ether. Examples of the acylphosphine oxide initiator include 2,4,6-trimethylbenzoindiphenylphosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

[0066] Examples of hydrogen abstraction type radical initiators include benzophenone-based initiators, thioxanthone-based initiators, aminobenzophenone-based initiators, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0067] Examples of benzophenone-based initiators include 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. Examples of thioxanthone initiators include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone.

[0068] Examples of aminobenzophenone initiators include Michler's ketone and 4,4'-diethylaminobenzophenone.

[0069] [6. Polymerization inhibitors] The ink of the present invention preferably further contains a polymerization inhibitor, which can reduce the adhesiveness between the multiple curable compounds. In the present invention, the term "polymerization inhibitor" includes all compounds that are added to inhibit polymerization reactions during the preparation of ink containing a polymerizable compound or during storage after preparation.

[0070] In the present invention, various conventionally known polymerization inhibitors can be used, but from the viewpoint of exerting the effect, it is more preferable to contain any one of an N-oxyl-based polymerization inhibitor, a phenol-based polymerization inhibitor containing an ot-butyl group, and a polymerization inhibitor having two or more aromatic rings.

[0071] Among these, it is more preferable to contain an N-oxyl-based polymerization inhibitor from the viewpoint of adhesion to printed wiring boards. In the ink of the present invention, the content of the polymerization inhibitor is preferably within the range of 0.05 to 0.5% by mass relative to the total mass of the ink.

[0072] [6-1. N-oxyl polymerization inhibitors] Examples of the N-oxyl polymerization inhibitor include 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, and Irgastab (registered trademark) UV10 (manufactured by BASF).

[0073] [6-2. Phenol-based polymerization inhibitors] Examples of the phenolic polymerization inhibitor include 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-t-butyl-p-cresol (butylated hydroxytoluene: BHT), 4-methoxyphenol, and 2-methoxy-4-methylphenol.

[0074] [6-3.Quinone-based polymerization inhibitors] Examples of the quinone polymerization inhibitor include hydroquinone, methoxyhydroquinone, benzoquinone, 1,4-naphthoquinone, and p-tert-butylcatechol.

[0075] [6-4. Amine-based polymerization inhibitors] Examples of the amine-based polymerization inhibitor include alkylated diphenylamine, N,N'-diphenyl-p-phenylenediamine, and phenothiazine.

[0076] [6-5. Other polymerization inhibitors] Other examples include copper dithiocarbamate polymerization inhibitors such as copper dimethyldithiocarbamate, copper diethyldithiocarbamate, and copper dibutyldithiocarbamate.

[0077] Only one of these may be contained, or two or more of them may be contained. Among these, N-oxyl and quinone polymerization inhibitors are preferred, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 2,6-di-t-butyl-p-cresol (butylated hydroxytoluene: BHT), 2,4-di-tert-butylphenol, and naphthoquinone, etc., are preferred as polymerization inhibitors having two or more aromatic rings.

[0078] [7. Gelling Agents] The ink of the present invention preferably further contains a gelling agent. The inclusion of a gelling agent makes it possible to gel the ink on the recording medium, temporarily fixing it (pinning it), and inhibiting the ink from spreading. Furthermore, by reducing the water absorption of the ink, it is possible to inhibit the hydrolysis of the compound (A) having the structure represented by the general formula (1) above.

[0079] The gelling agent preferably crystallizes at a temperature below the gelling temperature of the ink. The term "gelation temperature" refers to the temperature at which, when a composition that has been converted into a sol or liquid by heating is cooled, the gelling agent undergoes a phase transition from sol to gel, causing a sudden change in the viscosity of the composition. Specifically, the solated or liquefied composition is cooled while measuring its viscosity using a viscoelasticity measuring device (e.g., MCR300, manufactured by Anton Paar), and the temperature at which the viscosity suddenly increases can be determined as the gelation temperature of the composition.

[0080] In the present invention, when the gelling agent crystallizes in the ink, a structure in which the polymerizable compound (a compound involved in polymerization, such as polyfunctional compound A, acrylate oligomer, or monomer) is encapsulated in the three-dimensional space formed by the gelling agent crystallized into a plate shape, i.e., a so-called house-of-cards structure, is formed. To form this house-of-cards structure, it is preferable that the polymerizable compound and the gelling agent dissolved in the ink are compatible with each other.

[0081] Examples of gelling agents suitable for forming house-of-card structures include aliphatic ketones, aliphatic esters, petroleum waxes, vegetable waxes, animal waxes, mineral waxes, hydrogenated castor oil, modified waxes, higher fatty acids, higher alcohols, hydroxystearic acid, fatty acid amides including N-substituted fatty acid amides and special fatty acid amides, higher amines, esters of sucrose fatty acids, synthetic waxes, dibenzylidene sorbitol, dimer acid and dimer diol.

[0082] Among these, from the viewpoint of improving pinning properties, aliphatic ketones, aliphatic esters, higher fatty acids, and higher alcohols having a hydrocarbon group with 9 to 25 carbon atoms are preferred. Only one type of gelling agent may be contained, or two or more types may be contained.

[0083] [7-1. Aliphatic ketones] Examples of aliphatic ketones include dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosyl ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone, and palmityl stearyl ketone.

[0084] [7-2. Aliphatic esters] Examples of fatty acid esters include fatty acid esters of monoalcohols such as behenyl behenate, eicosanoic acid icosyl, and oleyl palmitate; and fatty acid esters of polyhydric alcohols such as glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters, and polyoxyethylene fatty acid esters.

[0085] Examples of commercially available products of the above aliphatic esters include the EMALEX (registered trademark) series manufactured by Nippon Emulsion Co., Ltd., and the Rikemal (registered trademark) series and Poem (registered trademark) series manufactured by Riken Vitamin Co., Ltd.

[0086] [7-3. Higher fatty acids] Examples of higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid.

[0087] [7-4. Higher Alcohols] Examples of higher alcohols include stearyl alcohol and behenyl alcohol.

[0088] [7-5. Suitable gelling agents] In the present invention, the gelling agent is particularly preferably an aliphatic ketone represented by the following general formula (G1) or an aliphatic ester represented by the following general formula (G2).

[0089] General formula (G1): R1-CO-R2

[0090] (In general formula (G1), R1 and R2 each independently represent an alkyl group having 12 to 26 carbon atoms, which includes a linear portion and may include a branch. R1 and R2 may be the same or different.)

[0091] General formula (G2): R3-COO-R4

[0092] (In general formula (G2), R3 and R4 each independently represent an alkyl group having 12 to 26 carbon atoms, which includes a linear portion and may include a branch. R3 and R4 may be the same or different.)

[0093] In general formulas (G1) and (G2), when the number of carbon atoms in the linear or branched hydrocarbon group is 12 or more, the crystallinity of the aliphatic ketone represented by general formula (G1) or the aliphatic ester represented by general formula (G2) is further increased, and more sufficient spaces are created in the house-of-card structure. As a result, the polymerizable compound is more easily encapsulated in the spaces, improving the pinning ability of the ink.

[0094] Furthermore, since the number of carbon atoms in the linear or branched hydrocarbon group is 26 or less, the melting point of the aliphatic ketone represented by general formula (G1) or the aliphatic ester represented by general formula (G2) does not increase excessively, i.e., the melting point can be set to a temperature that is easy to handle, and there is no need to excessively heat the ink when ejecting it.

[0095] Examples of aliphatic ketones represented by general formula (G1) include dilignoceryl ketone (carbon number: 23, 24), dibehenyl ketone (carbon number: 21, 22), distearyl ketone (carbon number: 17, 18), dieicosyl ketone (carbon number: 19, 20), dipalmityl ketone (carbon number: 15, 16), dimyristyl ketone (carbon number: 13, 14), dilauryl ketone (carbon number: 11, 12), lauryl myristyl ketone (carbon number: 13, 14), Examples include lauryl palmityl ketone (carbon number: 11, 14), lauryl palmityl ketone (carbon number: 11, 16), myristyl palmityl ketone (carbon number: 13, 16), myristyl stearyl ketone (carbon number: 13, 18), myristyl behenyl ketone (carbon number: 13, 22), palmityl stearyl ketone (carbon number: 15, 18), palmityl behenyl ketone (carbon number: 15, 22), and stearyl behenyl ketone (carbon number: 17, 22). The number of carbon atoms in parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

[0096] Examples of commercially available aliphatic ketones represented by general formula (G1) include 18-Pentatriacontanone and Hentriacontan-16-one manufactured by Alfa Aeser, and Kaowax T-1 manufactured by Kao Corporation.

[0097] Examples of aliphatic esters represented by general formula (G2) include behenyl behenate (number of carbon atoms: 21, 22), icosanoic acid icosyl (number of carbon atoms: 19, 20), stearyl stearate (number of carbon atoms: 17, 18), palmityl stearate (number of carbon atoms: 16, 17), lauryl stearate (number of carbon atoms: 12, 17), cetyl palmitate (number of carbon atoms: 6, 15), stearyl palmitate (number of carbon atoms: 15, 18), myristoyl stearate (number of carbon atoms: 16, 17), methyl ... Examples of esters include myristyl myristate (carbon numbers: 13, 14), cetyl myristate (carbon numbers: 13, 16), octyldodecyl myristate (carbon numbers: 13, 20), stearyl oleate (carbon numbers: 17, 18), stearyl erucate (carbon numbers: 18, 21), stearyl linoleate (carbon numbers: 17, 18), behenyl oleate (carbon numbers: 18, 22), and arachidyl linoleate (carbon numbers: 17, 20). The number of carbon atoms in parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

[0098] Commercially available examples of the aliphatic ester represented by general formula (G2) include Unistar (registered trademark) M-2222SL and Sperm Acetate manufactured by NOF Corporation, Exepar (registered trademark) SS and Exepar (registered trademark) MY-M manufactured by Kao Corporation, EMALEX (registered trademark) CC-18 and EMALEX (registered trademark) CC-10 manufactured by Nippon Emulsion Co., Ltd., and Amleps (registered trademark) PC manufactured by Kokyu Alcohol Kogyo Co., Ltd.

[0099] In the present invention, the content of the gelling agent is preferably within the range of 1 to 10% by mass relative to the total mass of the ink.

[0100] [8. Other Ingredients] [8-1. Surfactants] The ink of the present invention may further contain a surfactant, if necessary. Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers; cationic surfactants such as alkylamine salts and quaternary ammonium salts; and silicone-based and fluorine-based surfactants.

[0101] [8-2. Colorants] The ink of the present invention may further contain a colorant, if necessary. The colorant may be a pigment or a dye, but is preferably a pigment from the viewpoints of having good dispersibility in the constituent components of the ink and excellent weather resistance. The pigment is not particularly limited, and examples thereof include organic pigments or inorganic pigments having the following numbers listed in the Color Index.

[0102] The ink of the present invention may contain only one type of colorant, or may contain two or more types of colorants, and may be toned to a desired color. The content of the colorant is preferably within a range of 0.1 to 20% by mass, and more preferably within a range of 0.2 to 10% by mass, relative to the total mass of the ink.

[0103] (pigment) Red or magenta pigment Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, and 257; Pigment Violet 3, 19, 23, 29, 30, 37, 50, and 88; and Pigment Orange. 13, 16, 20, 36 or a mixture thereof.

[0104] Blue or cyan pigment Examples of blue or cyan pigments include pigments selected from Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17:1, 22, 27, 28, 29, 36, and 60, or mixtures thereof.

[0105] Green Pigment Examples of green pigments include pigments selected from Pigment Green 7, 26, 36, and 50, and mixtures thereof.

[0106] Yellow pigment Examples of yellow pigments include pigments selected from Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, and 193, or mixtures thereof.

[0107] Black pigment Examples of black pigments include pigments selected from Pigment Black 7, 28, and 26, and mixtures thereof.

[0108] <Examples of commercially available pigments> Examples of commercially available pigments include Black Pigment (manufactured by Mikuni), Chromofine Yellow 2080, 5900, 5930, AF-1300, 2700L, Chromofine Orange 3700L, 6730, Chromofine Scarlet 6750, Chromofine Magenta 6880, 6886, 6891N, 6790, 6887, Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, and Chromofine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Chromofine Black A-1103, Seika Fast Yellow 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770, Seika Fast Red 8 040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmine 6B 1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B 800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (all manufactured by Dainichi Seika Color & Chemicals Mfg. Co., Ltd.; "Chromofine" is a registered trademark of the company); KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (manufactured by DIC);Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow1705, Colortex Orange 202, Colortex Red101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Violet600, Pigment Red 122, Colortex Blue516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (all manufactured by Sanyo Dye Co., Ltd.; "Colortex" and "Finecol" are registered trademarks of the company); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (all manufactured by Toyo Ink Co., Ltd.; "Lionol" is a registered trademark of the company); Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostapearm Blue B2G (all manufactured by Hoechst Industries); Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (all manufactured by Clariant; "Novoperm" and "Hostaperm" are registered trademarks of the company); carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, and CF9 (all manufactured by Mitsubishi Chemical);

[0109] Pigment Dispersion 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.

[0110] The pigment is preferably dispersed so that the volume average particle size of the pigment particles is preferably within a range of 0.08 to 0.5 μm, and the maximum particle size is preferably within a range of 0.3 to 10 μm, more preferably within a range of 0.3 to 3 μm. The dispersion of the pigment is adjusted by selecting the pigment, dispersant and dispersion medium, dispersing conditions, filtering conditions, and the like.

[0111] <Dispersant> The ink of the present invention may further contain a dispersant to improve the dispersibility of the pigment. Examples of dispersants include carboxylic acid esters having a hydroxy group, 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, polymer copolymers, modified polyurethanes, modified polyacrylates, polyether ester-type anionic surfactants, naphthalene sulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, and stearylamine acetate. Examples of commercially available dispersants include the Solsperse (registered trademark) series manufactured by Avecia and the PB series manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0112] <Dispersion aid> The ink of the present invention may further contain a dispersing aid, if necessary. The dispersing aid may be selected depending on the pigment. The total content of the dispersant and dispersion aid is preferably within the range of 1 to 50% by mass relative to the total mass of the pigment.

[0113] 《Dispersion medium》 The ink of the present invention may further contain a dispersion medium for dispersing the pigment, if necessary. The ink of the present invention may contain a solvent as a dispersion medium, but in order to suppress the solvent from remaining in the formed image, it is preferable to use the above-mentioned monomer (particularly a monomer with low viscosity) as the dispersion medium.

[0114] [8-3. Other additives] The ink of the present invention may further contain a coupling agent, a solvent, etc., as required.

[0115] (coupling agent) The ink of the present invention may further contain various coupling agents as needed, which can improve adhesion to printed wiring boards. Examples of various coupling agents include silane-based, titanium-based, and aluminum-based coupling agents.

[0116] (solvent) The ink of the present invention is preferably solvent-free from the viewpoint of rapid curing and ejection stability, but solvents may be added to adjust the ink viscosity.

[0117] [Method of manufacturing the inkjet ink composition of the present invention] The ink of the present invention can be prepared by mixing (A) a compound having a structure represented by the general formula (1) or a salt thereof, (B) a hyperbranched acrylate oligomer or polymer, and any other components under heating. The resulting mixture is preferably filtered through a predetermined filter. When preparing an ink containing a pigment, it is preferable to prepare a pigment dispersion containing the pigment and a polymerizable compound, and then mix the pigment dispersion with other components. The pigment dispersion may further contain a dispersant.

[0118] The pigment dispersion can be prepared by dispersing a pigment in a polymerizable compound. 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. A dispersant may be added at this time.

[0119] [Recording of the present invention] The recorded matter of the present invention is characterized by being obtained by curing the inkjet ink composition of the present invention described above with actinic energy rays or heat. That is, the recorded matter of the present invention refers to an object recorded on a recording medium by the inkjet recording method described below using the inkjet ink composition of the present invention. Note that, in the present invention, the term "cured product" simply refers to an object obtained by curing the inkjet ink composition of the present invention, but is essentially synonymous with the recorded matter.

[0120] [Inkjet recording method of the present invention] The inkjet recording method of the present invention is characterized by comprising the steps of: using the inkjet ink composition of the present invention; ejecting the inkjet ink composition from an inkjet head and allowing it to land on a recording medium; and curing the inkjet ink composition that has landed on the recording medium by actinic energy rays or heat.

[0121] In the inkjet method, ink is ejected from an inkjet head and landed on a recording medium. Because the inkjet method makes it easy to apply ink only to the necessary areas, it is particularly suitable for forming solder resist patterns and printing characters.

[0122] In the step of curing by irradiation with active energy rays, the ink may be cured immediately after the step of landing the ink, or may be cured all at once after the step of landing the ink is completed. The ink of the present invention has a relatively high viscosity at room temperature (25°C) and does not spread easily after landing on a recording medium, so there is no need to cure the ink immediately after landing on the recording medium, and the ink can be discharged over a certain fixed / predetermined range, landed on the recording medium, and then cured all at once. By curing all at once, ejection defects due to light leakage can be reduced.

[0123] In the present invention, "batch irradiation," "batch heating," and "batch curing" refer to the process of ejecting a plurality of ink droplets in a certain fixed / predetermined area, causing them to land on a recording medium, and then simultaneously irradiating all of the ink droplets that have landed within that certain area with active energy rays or heating them to harden them. In other words, rather than hardening each ink droplet that has landed on the recording medium, the process refers to the process of landing the ink, irradiating it with active energy rays or heating it, and hardening it all at once in a certain fixed / predetermined area (for example, by landing all of the ink necessary to form a predetermined image (pattern)).

[0124] It is also preferable to form a solder resist film for use on a printed circuit board by the ink jet recording method of the present invention.

[0125] The inkjet recording method of the present invention will be described below. The inkjet recording method of the present invention comprises (1) a step of ejecting the ink of the present invention from an inkjet head and causing it to land on a recording medium, and (2) a step of curing the ink that has landed on the recording medium with actinic energy rays or heat.

[0126] [Step (1)] In step (1), the ink of the present invention is ejected from the nozzles of an inkjet head and deposited on a recording medium, which is not particularly limited but is preferably a printed circuit board.

[0127] The ejection method from the inkjet head may be either an on-demand method or a continuous method. The on-demand inkjet head may be of either an electro-mechanical conversion type, such as a single cavity type, double cavity type, bender type, piston type, shear mode type, or shared wall type, or an electro-thermal conversion type, such as a thermal inkjet type or a Bubble Jet (registered trademark) type (Bubble Jet is a registered trademark of Canon Inc.).

[0128] Discharging ink droplets from an inkjet head in a heated state provides stable discharge. The temperature of the ink when filled into the inkjet head is preferably within the range of 40 to 100°C, and from the viewpoint of further enhancing discharge stability, it is more preferably within the range of 40 to 90°C. The viscosity of the ink at the discharge temperature is preferably within the range of 7 to 15 mPa·s, and more preferably within the range of 8 to 13 mPa·s.

[0129] When using a sol-gel phase transition ink containing a gelling agent, the temperature of the ink when filled into the inkjet head is preferably within the range of (gelation temperature + 10) to (gelation temperature + 30)°C of the ink. By keeping the temperature of the ink inside the inkjet head at (gelation temperature + 10)°C or higher, the ink does not gel inside the inkjet head or on the nozzle surface, and sufficient ejection stability is obtained. Furthermore, by keeping the temperature of the ink at (gelation temperature + 30)°C or lower, temperature-induced deterioration of the components contained in the ink is prevented.

[0130] The method for heating the ink is not particularly limited. For example, at least one of the ink supply system, such as the ink tank constituting the head carriage, the supply pipe, and the anterior ink tank immediately before the head, the piping with a filter, and the piezo head, can be heated by a panel heater, a ribbon heater, or heated water.

[0131] The amount of ink droplets ejected is preferably within the range of 2 to 20 pL from the viewpoint of recording speed and image quality.

[0132] The recording medium is not particularly limited, and can be made of various metals, glass, ceramics, polyimide films, PET films, etc. In order to improve adhesion, it is preferable for the surface to contain an inorganic material such as metal or glass. Examples of metals include copper, aluminum, iron, and oxides thereof. It is particularly suitable for use with printed circuit boards that contain an inorganic material such as metal or glass on the surface. Examples of printed circuit boards that can be used include copper-clad laminates for high-frequency circuits made of glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, etc., and copper-clad laminates of all grades (FR-4, etc.) can be used suitably.

[0133] [Step (2)] In step (2), the ink that has landed on the recording medium is cured by actinic radiation or heat. The ink of the present invention can be cured by only irradiation with actinic radiation or only heating, but it is preferable to cure the ink by at least irradiation with actinic radiation, and more preferably by heating.

[0134] Examples of active energy rays include electron beams, ultraviolet rays, α rays, γ rays, and X-rays, with ultraviolet rays being preferred. The ultraviolet light can be irradiated at a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology Co., Ltd. Using an LED as the light source can prevent ink from melting due to the radiant heat of the light source, thereby preventing poor ink curing.

[0135] The peak irradiance of ultraviolet light having a wavelength in the range of 370 to 410 nm on the surface of the solder resist film is 0.5 to 10 W / cm 2 It is preferable that the range is 1 to 5 W / cm 2 From the viewpoint of suppressing the radiant heat from being irradiated onto the ink, the amount of light irradiated onto the solder resist film is set to 1000 mJ / cm. 2 It is preferable that it is less than 10 ...

[0136] The irradiation of active energy rays is preferably carried out within 0.001 to 300 seconds after the ink has landed, and more preferably within 0.001 to 60 seconds in order to form a highly precise solder resist film.

[0137] To prevent polymerization inhibition caused by oxygen, it is preferable to cure the ink by irradiating the deposited ink with active energy rays in an atmosphere with an oxygen concentration of 0.1 to 10.0% by volume. To prevent blooming, the oxygen concentration is more preferably 0.5 to 8.0% by volume, and even more preferably 0.5 to 6.0% by volume.

[0138] The heating method is preferably, for example, placing the product in an oven set at a temperature in the range of 110 to 180° C. for 10 to 90 minutes.

[0139] [Inkjet recording system of the present invention] The inkjet recording system of the present invention is characterized by using the inkjet ink composition of the present invention and comprising an inkjet head that ejects the inkjet ink composition, an actinic energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with actinic energy rays, and a heating unit that heats the inkjet ink composition that has been irradiated with the actinic energy rays.

[0140] That is, the system of the present invention uses a recording apparatus having an inkjet head that ejects an inkjet ink composition, an actinic energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with actinic energy rays, and a heating unit that heats the inkjet ink composition that has been irradiated with actinic energy rays, and the ink of the present invention.

[0141] From the viewpoint of ejection stability and printing accuracy, the recording method of the inkjet recording apparatus is preferably a scan method.

[0142] The inkjet recording apparatus used in the present invention comprises an inkjet head that ejects the ink of the present invention onto a recording medium, an actinic energy ray irradiation unit that irradiates the ink of the present invention that has landed on the recording medium with actinic energy rays (e.g., ultraviolet rays) to cure the ink of the present invention, and a heating unit that applies heat to further promote curing.

[0143] Types of inkjet recording devices (printers) include single-pass printers and serial printers. Single-pass printers are equipped with a line head having a length equivalent to the width of the recording medium (recording medium width), and the head is fixed and (almost) does not move, so printing is performed in one pass (single pass).

[0144] On the other hand, in a serial printer, printing is usually performed in two or more passes (multi-pass) while the head moves back and forth (shuttle movement) in a direction perpendicular to the conveyance direction of the recording medium.

[0145] In a single-pass printer, multiple inkjet heads must be arranged in a line head, which requires a relatively large number of inkjet heads, but in a serial printer, it can be configured with only a small number of recording heads.

[0146] In the present invention, either type of printer can be used, and preferably, a serial printer can be used. [Example]

[0147] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively.

[0148] <Preparation of Yellow Pigment Dispersion Y> Dispersant 1 and Dispersant 2 shown below and the dispersion medium were placed in a stainless steel beaker, heated on a hot plate at 65°C for 1 hour while stirring and dissolving, and then cooled to room temperature. The pigment shown below was added to this, and the mixture was placed in a glass bottle together with 200 g of zirconia beads with a diameter of 0.5 mm and sealed. This was dispersed in a paint shaker until the desired particle size was reached, and then the zirconia beads were removed.

[0149] Dispersant 1: PX4701 (manufactured by BASF) 6.0 parts by mass Dispersant 2: Solsperse 22000 (manufactured by Lubrizol Japan) 0.3 parts by mass Dispersion medium: Dipropylene glycol diacrylate (containing 0.2% UV-10) 61.5 parts by mass Pigment: PY185 (BASF, Paliotol Yellow D1155) 10.2 parts by mass

[0150] <Preparation of Cyan Pigment Dispersion C> Dispersion liquid Y was prepared in the same manner as in the preparation of the yellow pigment dispersion liquid Y, except that the dispersant, dispersion medium, and pigment were changed as shown below.

[0151] Dispersant: PX4701 (BASF) 7.0 parts by mass Dispersion medium: Dipropylene glycol diacrylate (containing 0.2% UV-10) 70 parts by mass Pigment: PB15:4 (Dainichi Seika Chemicals, Chromofine (registered trademark) Blue 6332JC) 23 parts by mass

[0152] The acidic acrylate (used in the inks of the comparative examples), the compound having a structure represented by general formula (1) above or its salt (A), the hyperbranched acrylate oligomer or polymer (B), the polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups and not a hyperbranched acrylate oligomer or polymer, the (meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0, the polymerization initiator, the polymerization inhibitor, the gelling agent, the hydrolysis inhibitor, and other monomers used in preparing the inks below are as follows:

[0153] <Acidic acrylate> Phosphate acrylate: Light Ester P-2M (Kyoeisha Chemical Co., Ltd.)

[0154] [ka]

[0155] <Compound (A) Having a Structure Represented by General Formula (1) or a Salt Thereof> A-1: The above-mentioned exemplary compound A-1 A-2: The above-mentioned exemplary compound A-2 A-3: Exemplary compound A-3

[0156] <Hyperbranched acrylate oligomer or polymer (B)> B-1: CN2304 (Sartomer) (18-functional hyperbranched polyester acrylate) B-2: SP1106 (Miwon) (18-functional dendritic acrylate) B-3: 6361-100 (manufactured by Choko Chemical Industry Co., Ltd.) (octafunctional hyperbranched polyester acrylate)

[0157] <(C) Polyfunctional (meth)acrylate having three or more (meth)acryloyl groups, which is not a hyperbranched acrylate oligomer or polymer> C-1: M600 (Miwon) (hexafunctional (meth)acrylate: dipentaerythritol hexaacrylate) C-2: M500 (manufactured by Miwon Co., Ltd.) (5-functional (meth)acrylate: dipentaerythritol pentaacrylate) C-3: DPCA120 (manufactured by Nippon Kayaku Co., Ltd.) (6-functional (meth)acrylate: caprolact ton modified dipentaerythritol hexaacrylate)

[0158] <(Meth)acrylate (D) with a ClogP value in the range of 4.0 to 7.0> SR834 (manufactured by Sartomer Co., Inc.) (tricyclodecane dimethanol dimethacrylate) (molecular weight 304, ClogP 4.69) NK Ester DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.) (1,10-decanediol dimethacrylate) (molecular weight 310, ClogP 5.75)

[0159] <Polymerization initiator> Type I (Norrish type I) A: Omnirad® 907, manufactured by IGM Resins (B.V.) Type I (Norrish type I) B: Omnirad® 819, manufactured by IGM Resins (B.V.) Type II (Norrish type II): Speedcure® ITX, manufactured by Lambson

[0160] <Polymerization inhibitor> Irgastab® UV-10, manufactured by BASF

[0161] <Gelling agent> Gelling agent A: Exceparl SS (manufactured by Kao Corporation) (aliphatic ester represented by the general formula (G2))

[0162] <Hydrolysis inhibitor> Carbodiimide: V02B, manufactured by Nisshinbo Chemical Co., Ltd.

[0163] <Other monomers> M222: Dipropylene glycol diacrylate (Miwon)

[0164] <Ink Preparation> Ink 6 was prepared by mixing the following components and filtering them through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC. Compound (A) Having a Structure Represented by General Formula (1) or a Salt Thereof A-1 10.0 parts by mass <Hyperbranched acrylate oligomer or polymer (B)> B-1 20.0 parts by mass <Polymerization initiator> Type I Type A 3.0 parts by mass Type I Type B 3.0 parts by mass Type II 2.0 parts by mass Polymerization inhibitor Irgastab® UV-10 0.1 parts by weight Pigment dispersion Dispersion liquid Y 0.7 parts by mass Dispersion liquid C 0.5 parts by mass Other Monomers M222 remainder

[0165] Each ink was prepared in the same manner as in the preparation of ink 6, except that the types and amounts of (A), (B), (C), (D), acidic acrylate, gelling agent, hydrolysis inhibitor, and other monomers were changed to those shown in Table I. In preparing the ink, the "balance" refers to the amount remaining after subtracting the amounts of the various compounds added when the total amount is 100 parts by mass. In addition, in Table I, "(A)" means a compound having a structure represented by general formula (1) or a salt thereof (A), "(B)" means a hyperbranched acrylate oligomer or polymer (B), "(C)" means a polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups that is not a hyperbranched acrylate oligomer or polymer, and "(D)" means a (meth)acrylate (D) having a ClogP value in the range of 4.0 to 7.0.

[0166] <Formation of ink-cured film by inkjet method> Each ink was loaded into an inkjet recording device having an inkjet recording head equipped with a piezoelectric inkjet nozzle. Using this device, a solder resist pattern was formed on a copper-clad laminate for printed wiring boards (FR-4, thickness 1.6 mm, size 150 mm × 95 mm) to obtain a cured film (or cured product).

[0167] The ink supply system consists of an ink tank, ink flow path, a sub-ink tank just before the inkjet recording head, piping with a metal filter, and a piezo head. The ink is heated to 80°C from the ink tank to the head. A heater is also built into the piezo head, heating the ink temperature inside the recording head to 80°C. The piezo head has a nozzle diameter of 22 μm, and the nozzles with a nozzle resolution of 360 dpi are arranged in a staggered pattern to form a nozzle row with a resolution of 720 dpi.

[0168] Using this inkjet device, a voltage was applied so that the droplet volume would be 6.0 pL, and a 20 mm × 50 mm solid pattern was printed on the substrate so that each pattern would be 20 μm thick. After that, an LED lamp (395 nm, 8 W / cm) manufactured by Phoseon Technology was used to print the pattern. 2 , water cooled unit) to 1W / cm 2 , 500mJ / cm 2 The coating was then cured by placing it in an oven set at 150°C for 60 minutes to obtain a cured film.

[0169] [evaluation] <Viscosity fluctuation> The viscosity of each ink at 80°C was measured using a Physica MCR301 (manufactured by Anton Paar) with a shear rate of 1000 (1 / s). Measurements were taken immediately after preparation and after storage at 85°C for 4 days, and the ink was evaluated according to the following criteria. (standard) Viscosity fluctuation is less than 0.7 mPa·s △Viscosity fluctuation is 0.7 mPa·s or more but less than 1.0 mPa·s × Viscosity fluctuation is 1.0 mPa·s or more

[0170] <Average particle size variation> The average particle size (Z-average) of each ink was measured by dynamic light scattering using a Datasizer Nano ZSP (Malvern). The ink was diluted 200 times before measurement. Measurements were performed at 25°C. Measurements were performed immediately after preparation and after storage at 85°C for 4 days, and were evaluated according to the following criteria. (standard) Average particle size variation is less than 15 nm △Average particle size fluctuation is 15nm or more and less than 30nm ×Average particle size fluctuation is 30 nm or more

[0171] <Adhesion> For the solid pattern print sample thus prepared, grid-shaped cuts were made in the cured film according to the cross-cut method of JIS standard K5600, adhesive tape was attached to the cuts, and the tape was then peeled off to observe the peeling state of the cured film. (standard) ◎: The adhesion remaining rate is 100%. ◯: The residual adhesion rate is 80% or more and less than 100%. △: The residual adhesion rate is 60% or more and less than 80%. ×: The residual adhesion rate is less than 60%.

[0172] <Pencil hardness> The pencil hardness of the surface of the prepared print sample of the solid pattern was measured in accordance with the method described in JIS standard K-5400.

[0173] <Precipitation property> Approximately 10 g of the prepared ink was placed in a transparent heat-resistant tube and stored at 85°C, and then stored for 1 day, 4 days, 1 week, and 2 weeks, and the presence or absence of an increase in precipitates was visually observed before and after storage. (standard) ◎: No increase in precipitates observed even after 2 weeks. ◯: No increase in precipitates was observed after 1 week, but an increase in precipitates was observed after 2 weeks. △: No increase in precipitates was observed after 4 days, but an increase in precipitates was observed after 1 week. ×: Increase in precipitated area observed after 1 day.

[0174] <Acid resistance> The solid pattern thus formed was immersed in a 10% aqueous HCl solution at 25° C. for 30 minutes, then washed with pure water, wiped to remove water, and evaluated in the same manner as in the adhesion test described above. (standard) ◎: The adhesion remaining rate is 100%. ◯: The residual adhesion rate is 80% or more and less than 100%. △: The residual adhesion rate is 60% or more and less than 80%. ×: The residual adhesion rate is less than 60%.

[0175] <Alkali resistance> The solid pattern thus formed was immersed in a 10% aqueous solution of NaOH at 25° C. for 30 minutes, then washed with pure water, wiped to remove water, and evaluated in the same manner as in the adhesion test described above. (standard) ◎: The adhesion remaining rate is 100%. ◯: The residual adhesion rate is 80% or more and less than 100%. △: The residual adhesion rate is 60% or more and less than 80%. ×: The residual adhesion rate is less than 60%.

[0176] [Table 1]

[0177] As shown in the above results, the ink of the present invention has higher adhesion and sufficient hardness than the ink of the comparative example, and is able to suppress an increase in viscosity during long-term storage or retention, and is able to suppress fluctuations in particle size and the occurrence of precipitates. In particular, Caprolactam ton It can be seen that ink 9 using modified dipentaacrylate has excellent acid resistance and alkali resistance.

Claims

1. An inkjet ink composition that is curable by actinic radiation or heat, comprising: a compound (A) having a structure represented by the following general formula (1) or a salt thereof; A hyperbranched acrylate oligomer or polymer (B), and an inkjet ink composition, wherein the content of the compound having a structure represented by general formula (1) or a salt thereof (A) is within a range of 3 to 20% by mass, and the content of the hyperbranched acrylate oligomer or polymer (B) is within a range of 10 to 30% by mass. 【Chemical 1】 In the general formula (1), X represents a substituent having at least one group selected from an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, and derivatives thereof at its terminal. Q is an oxygen atom or NR ４ represents R ４ represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. R 1 represents an unsubstituted alkylene group having 1 to 6 carbon atoms.

2. 2. The ink-jet ink composition according to claim 1, wherein in the general formula (1), X represents an acryloyl group or a methacryloyl group.

3. 3. The ink-jet ink composition according to claim 1, wherein Q in the general formula (1) represents an oxygen atom.

4. In the general formula (1), R 1 represents an unsubstituted alkylene group having 1 or 2 carbon atoms; The ink-jet ink composition according to any one of claims 1 to 3, wherein

5. 5. The inkjet ink composition according to claim 1, further comprising a polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B).

6. 6. The ink-jet ink composition according to claim 5, wherein the polyfunctional (meth)acrylate (C) having three or more (meth)acryloyl groups other than the hyperbranched acrylate oligomer or polymer (B) is a caprolactone-modified dipentaacrylate.

7. 7. The ink-jet ink composition according to claim 1, further comprising a (meth)acrylate compound (D) having a ClogP value in the range of 4.0 to 7.

0.

8. 8. The ink-jet ink composition according to claim 1, further comprising a gelling agent (E).

9. 9. The ink-jet ink composition according to claim 1, which is used as an ink-jet ink for forming a solder resist pattern used on a printed circuit board.

10. A recorded matter, wherein the ink-jet ink composition according to any one of claims 1 to 9 is cured by actinic energy rays or heat.

11. An inkjet recording method using an inkjet ink composition, comprising: The ink-jet ink composition according to any one of claims 1 to 9 is used, and a step of ejecting the inkjet ink composition from an inkjet head and landing it on a recording medium; and curing the inkjet ink composition that has landed on the recording medium by using actinic energy rays or heat.

12. 1. An inkjet recording system using an inkjet ink composition, comprising: The ink-jet ink composition according to any one of claims 1 to 9 is used, and an inkjet recording system comprising an inkjet head that ejects the inkjet ink composition, an actinic energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with actinic energy rays, and a heating unit that heats the inkjet ink composition that has been irradiated with the actinic energy rays.

Images