JP7753879B2 - Thermosetting inkjet ink - Google Patents

Description

The present invention relates to a thermosetting inkjet ink, and more particularly to a thermosetting inkjet ink using a thermosetting composition that has excellent storage stability at high temperatures and excellent thermosetting properties of the cured film surface under high temperature and high humidity conditions.

Poly(meth)acrylate resins (hereinafter referred to as "acrylic resins") are highly transparent and impact resistant, and are easy to thermoplastically form and color. As a result, they are used as a substitute for inorganic glass in window materials for buildings and vehicles, as well as for a variety of other applications, such as components in electrical and electronic devices, daily necessities, and office supplies.

Acrylic resins can be produced by adding a radical generator to (meth)acrylate, which generates radicals when irradiated with active energy rays such as ultraviolet light or electron beams, and subjecting the mixture to radical polymerization (crosslinking reaction). Acrylic resins can also be produced by adding a peroxide to (meth)acrylate and heating the mixture to cause radical polymerization.

For example, Patent Document 1 describes a curable composition used in a method for producing poly(meth)acrylate by polymerizing a monomer having a (meth)acrylate group in the presence of an isocyanate.
Patent Document 2 reports a polyurethane composition containing an acrylate having a functional group that reacts with isocyanate.

It is also known that these thermosetting compositions and photocurable compositions are used to form coating films using photolithography development methods or screen printing methods, thereby forming etching resists, solder resists, and markings for printed circuit boards.

A method for manufacturing printed circuit boards using an inkjet printer has already been proposed, in which an etching resist is formed by using an inkjet printer to draw a conductor circuit pattern on a copper-clad laminate for printed wiring boards, followed by etching (see, for example, Patent Document 3). Compared to photolithography, which requires a photomask, or screen printing, which uses resist ink or marking ink and requires a screen plate, this method significantly reduces the number of steps and effort required, while also reducing the need for consumables such as developers, various inks, and cleaning solvents. It also reduces wastewater, which is expected to contribute to a cleaner environment.

It has also been proposed to form a hardened film of solder resist by using an inkjet method with light and heat (see, for example, Patent Documents 4, 5, 6 and 7).
Specifically, Patent Document 6 discloses a photocurable thermosetting composition that contains an acryloyl group-containing monomer, a blocked polyisocyanate having a triazine skeleton, and a photopolymerization initiator, and is used for printing by an inkjet method.
Furthermore, Patent Document 7 discloses a white curable composition for printed wiring boards to be applied to copper wiring and substrates, which contains titanium oxide, a (meth)acrylate having a hydroxy group, a photopolymerization initiator, a wetting and dispersing agent having an acid value, and a specific bifunctional (meth)acrylate compound (excluding those having a hydroxy group).

However, the storage stability of these thermosetting compositions and thermosetting inkjet inks, particularly at high temperatures, and the thermosetting properties of the cured film surface under high temperature and high humidity conditions are still insufficient, and improvements are desired.

Patent No. 6259394 Special Publication No. 2010-523775 Patent No. 5731746 Patent No. 4936725 Patent No. 5969208 Patent No. 6069300 Patent No. 6488345

The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide a thermosetting inkjet ink using a thermosetting composition that has excellent storage stability at high temperatures and excellent thermosetting properties of the cured film surface under high temperature and high humidity conditions.

In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors found that by adding a specific amount of a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate (A) to a thermosetting composition comprising a blocked isocyanate (A) and a poly(meth)acrylate (C), the storage stability at high temperatures can be significantly improved and the thermosetting properties of the cured film surface under high temperature and high humidity conditions can also be increased, thereby arriving at the present invention.
That is, the above-mentioned problems of the present invention are solved by the following means.

1. A thermosetting inkjet ink containing a blocked isocyanate (A),
The composition contains a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate (A), and a (meth)acryloyl group-containing monomer (C) having no functional group capable of reacting with the blocked isocyanate,
the compound (B) is contained in a range of 0.1 to 20 parts by mass and the blocked isocyanate (A) is contained in a range of 1 to 10 parts by mass relative to 100 parts by mass of the (meth)acryloyl group-containing monomer (C) ;
Contains a gelling agent and undergoes sol-gel phase transition depending on temperature.
The thermosetting inkjet ink is characterized in that the gelling agent is a compound having a structure represented by the following general formula (G1) or (G2) :
General formula (G1): R ₁ -CO-R ₂
General formula (G2): R ₃ -COO-R ₄
(In the formula, R ₁ to R ₄ each independently represent an alkyl chain having 12 or more carbon atoms and a linear portion, which may be branched.)

2. The thermosetting inkjet ink according to item 1, further comprising a photopolymerization initiator.

3. The thermosetting inkjet ink described in item 1 or 2, wherein the functional group of the compound (B) capable of forming a hydrogen bond with the blocked isocyanate (A) is at least one selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a mercapto group.

4. The thermosetting inkjet ink according to item 3, wherein the compound (B) is a (meth)acryloyl group-containing monomer.

5. The thermosetting inkjet ink according to any one of items 1 to 4, wherein the compound (B) is contained in an amount within a range of 1 to 10 parts by mass per 100 parts by mass of the (meth)acryloyl group- containing monomer (C).

6. The thermosetting inkjet ink described in any one of items 1 to 5, characterized in that the viscosity at 25°C is in the range of 1 to 1 x 10 ⁴ Pa·s, and the sol-gel phase transition occurs at a temperature in the range of 40°C or higher and lower than 100°C.

7. The thermosetting ink-jet ink according to any one of items 1 to 6 , which is a thermosetting ink-jet ink for forming a solder resist pattern used on a printed circuit board.

The above-described means of the present invention can provide a thermosetting inkjet ink using a thermosetting composition that has excellent storage stability at high temperatures and thermosetting properties of the cured film surface under high temperature and high humidity conditions.

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.
The stability of blocked isocyanate (A) is explained using the following Structure 1. Structure 1 shows a structure in which blocked isocyanate (A), whose terminal isocyanate group is blocked with a blocking group, is hydrogen-bonded with compound (B) having active hydrogen.

When compound (B), which has a functional group (containing an active hydrogen atom) capable of hydrogen bonding with blocked isocyanate (A), hydrogen bonds with the R-NHC(=O)-Block (Block represents a blocking group) portion of blocked isocyanate (A), blocked isocyanate (A) and compound (B) form a stable six-membered ring structure, as shown in Structure 1 below, which is believed to improve storage stability at high temperatures. Note that R represents a residue of a blocked isocyanate group, R' represents a residue of a functional group (XH) containing active hydrogen, and X preferably represents an oxygen atom, sulfur atom, or nitrogen atom.

Surprisingly, the curing properties of the cured film surface are also improved under high temperature and high humidity conditions. This is thought to be because, after the blocking agent of blocked isocyanate (A) is released during thermal curing, the isocyanate group reacts with compound (B), causing the R' moiety of compound (B), which is primarily composed of a hydrocarbon group, to protrude outward from the molecule, making it easier to orient on the surface of the cured film, thereby increasing the hydrophobicity of the cured film surface.

The thermosetting composition of the present invention is a thermosetting composition containing a blocked isocyanate (A), and the composition contains a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate (A), and a (meth)acryloyl group-containing monomer (C) that does not have a functional group capable of reacting with the blocked isocyanate, wherein the compound (B) is contained in an amount of 0.1 to 20 parts by mass and the blocked isocyanate (A) is contained in an amount of 1 to 10 parts by mass per 100 parts by mass of the (meth)acryloyl group-containing monomer (C). This feature is a technical feature common to or corresponding to each of the following embodiments (configurations).

In an embodiment of the present invention, it is preferable to contain a photopolymerization initiator from the viewpoint of improving the curability of the surface of the cured film.
Furthermore, it is preferable that the functional group that can form a hydrogen bond with the blocked isocyanate (A) that the compound (B) has is at least one selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a mercapto group, since this allows the curability of the film surface to be maintained at a high level.
Furthermore, in the present invention, the compound (B) is preferably a (meth)acryloyl group-containing monomer, which can further increase the degree of polymerization of the entire thermosetting composition, thereby improving the thermosetting properties.
As an embodiment of the present invention, from the viewpoint of exerting the effects of the present invention, it is preferable that the compound (B) is contained in an amount within a range of 1 to 10 parts by mass per 100 parts by mass of the (meth)acryloyl group-containing monomer (C).
In addition, the inkjet ink preferably contains the thermosetting composition of the present invention.
Furthermore, in the present invention, the thermosetting inkjet ink preferably contains a gelling agent and undergoes a sol-gel phase transition depending on the temperature, thereby increasing the hydrophobicity of the cured film and providing excellent curability of the film surface under high temperature and high humidity conditions.
It is preferable that the viscosity at 25°C is in the range of 1 to 1 x 10 ⁴ Pa·s and that the sol-gel phase transition occurs at a temperature in the range of 40°C or higher but lower than 100°C, since this allows the ink-jet ink to be ejected with low viscosity.
Furthermore, it is preferable that the gelling agent is a compound having a structure represented by general formula (G1) or general formula (G2), since this increases the hydrophobicity of the cured film and provides excellent curability of the film surface under high temperature and high humidity conditions.
Furthermore, from the viewpoint of being able to obtain a cured film with high surface hardness, the thermosetting inkjet ink of the present invention is preferably a thermosetting inkjet ink for forming a solder resist pattern used on a printed circuit board.

The present invention, its components, and modes and aspects for implementing the invention are described in detail below. Note that in this application, the symbol "to" is used to mean that the numerical values before and after it are included as both the lower limit and upper limit.

In the present invention, "(meth)acryloyl group" means an acryloyl group or a methacryloyl group, and "(meth)acrylate" means an acrylate or a methacrylate.

Overview of Thermosetting Composition
The thermosetting composition of the present invention is a thermosetting composition containing a blocked isocyanate (A), and the thermosetting composition contains a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate (A), and a (meth)acryloyl group-containing monomer (C) that does not have a functional group capable of reacting with the blocked isocyanate, characterized in that the compound (B) is contained in an amount within a range of 0.1 to 20 parts by mass and the blocked isocyanate (A) is contained in an amount within a range of 1 to 10 parts by mass per 100 parts by mass of the (meth)acryloyl group-containing monomer (C).

The thermosetting composition and thermosetting inkjet ink of the present invention use blocked isocyanate (A) as a thermosetting agent. The blocking agent in blocked isocyanate (A) is released by heating at high temperatures, for example, 110 to 180°C for 10 to 60 minutes, thereby initiating thermosetting. However, in reality, the blocking agent is released and the reaction proceeds gradually from temperatures lower than the above, around 80°C, resulting in a problematic increase in viscosity. This problem can be improved by raising the dissociation temperature of the blocking agent, but this results in insufficient thermosetting properties.

Therefore, in the present invention, by interacting a blocked isocyanate (A) having a dissociation temperature within the above temperature range with a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate, we have succeeded in achieving both shelf life and curing properties at high temperatures.

It is also preferable that the number of -NCO functional groups in the blocked isocyanate and the number of active hydrogen-containing moieties in compound (B), which has a functional group capable of hydrogen bonding with the blocked isocyanate, are the same (same number of moles). However, it has been found that the effects of the present invention can also be achieved when, for example, 1 mole of compound (B) with one active hydrogen-containing moiety is used per mole of a trifunctional blocked isocyanate compound. This is presumably because the charge balance of the entire blocked isocyanate molecule is disrupted when it acts on R-NHC(=O)-Block.

On the other hand, containing a large amount of compound (B) having a hydrophilic functional group capable of forming hydrogen bonds can make the composition particularly susceptible to the effects of high temperatures and high humidity, which may reduce the curability of the film surface. However, in the present invention, the problem of reduced curability of the film surface is solved by including 0.1 to 20 parts by mass of compound (B) having a functional group capable of forming a hydrogen bond with a blocked isocyanate relative to the (meth)acryloyl group-containing monomer (C) that does not have a functional group capable of reacting with blocked isocyanate, which is the majority of thermosetting compositions and thermosetting inkjet inks, and by including 0.1 to 20 parts by mass of blocked isocyanate (A) relative to 100 parts by mass of the (meth)acryloyl group-containing monomer (C).

In addition, in the present invention, it is preferable to further use a photopolymerization initiator. The use of a photopolymerization initiator can increase the degree of polymerization of the cured film and also improve the curability of the cured film surface under high temperature and high humidity conditions. This is believed to be due to the fact that, as the (meth)acryloyl group-containing monomer (C) undergoes polymerization upon irradiation with light, the viscosity of the film increases, pushing the relatively low molecular weight blocked isocyanate (A) and compound (B) to the surface of the cured film. Subsequently, as described above, during thermal curing, the blocking agent of the blocked isocyanate (A) is released, causing the isocyanate group to react with compound (B). This causes the R' moiety of compound (B), which is primarily composed of a hydrocarbon group, to protrude outward from the molecule, facilitating orientation at the surface of the cured film, further enhancing the hydrophobicity of the cured film surface.

Furthermore, the compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate of the present invention is preferably at least one selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a mercapto group. It is believed that this compound has high nucleophilicity and can efficiently act on the R-NHC(=O)-Block moiety of the blocked isocyanate (A), effectively blocking the isocyanate group.

The present invention also preferably includes a gelling agent. It is believed that this is because the portion of the gelling agent consisting of a linear or branched long-chain hydrocarbon group has a high affinity with the R in the R-NHC(=O)-Block of the blocked isocyanate, which is primarily composed of a hydrocarbon group, making it easier for the -NHC(=O)-Block portion to protrude outward from the molecule, facilitating interaction with compound (B) according to the present invention. It is also believed that the increased hydrophobicity of the cured film results in excellent thermosetting properties of the cured film surface under high temperature and humidity conditions.

<<Details of the Thermosetting Composition>>
The thermosetting composition of the present invention will be described in detail below, including its constitution.

[Blocked isocyanate (A)]
In the present invention, a blocked isocyanate (A) having an isocyanate group protected with a thermally dissociable blocking agent is used. By using such a blocked isocyanate (A) in the thermosetting composition, storage stability at high temperatures can be improved. As the compound having an isocyanate group, a polyfunctional isocyanate having two or more isocyanate groups in the molecule is preferred.

(polyfunctional isocyanate)
The polyfunctional isocyanate is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule.

Specific examples include aromatic polyisocyanates such as 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), and 1,5-naphthalene diisocyanate (NDI); hexamethylene diisocyanate (HDI) aliphatic polyisocyanates such as trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, and norbornane diisocyanatomethyl (NBDI); alicyclic polyisocyanates such as transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), and H6TDI (hydrogenated TDI); polyisocyanates such as polymethylene polyphenylene polyisocyanate; and biuret, isocyanurate, and carbodiimide-modified products thereof.

In the present invention, any of these isocyanates may be used alone or in combination of two or more.

(Blocking agent)
Known blocking agents can be used, for example, alcohols such as ethanol, n-propanol, isopropanol, t-butanol, and isobutanol, phenols such as phenol, chlorophenol, cresol, xylenol, and p-nitrophenol, alkylphenols such as p-t-butylphenol, p-sec-butylphenol, p-sec-aminophenol, p-octylphenol, and p-nonylphenol, basic nitrogen-containing compounds such as 3-hydroxypyridine, 8-hydroxyquinoline, and 8-hydroxyquinaldine, diethyl malonate, ethyl acetoacetate, and acetylacetone. Examples of such active methylene compounds include acid amides such as acetamide, acrylamide, and acetanilide; acid imides such as succinimide and maleimide; imidazoles such as 2-ethylimidazole and 2-ethyl-4-methylimidazole; pyrazoles such as pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole; lactams such as 2-pyrrolidone and ε-caprolactam; oximes of ketones or aldehydes such as acetoxime, methyl ethyl ketone oxime, cyclohexanone oxime, and acetaldoxime; ethyleneimine; and bisulfites.

The thermally dissociable blocking agent is preferably at least one compound selected from the group consisting of oxime compounds, pyrazole compounds, and active ethylene compounds, in terms of ink storage stability and thermal dissociation properties.
Examples of the oxime compounds include formamide oxime, acetaldoxime, acetoxime, methyl ethyl ketone oxime, and cyclohexanone oxime.

Examples of pyrazole compounds include pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole, etc.

Activated ethylene compounds include dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc.

Examples of polyfunctional isocyanate compounds having an isocyanate group protected with the blocking agent include 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate, 2-[(3-butylidene)aminooxycarbonylamino]ethyl methacrylate, 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl acrylate, and 2-[(3-butylidene)aminooxycarbonylamino]ethyl acrylate.

The content of blocked isocyanate (A) is 0.1 to 20 parts by mass, and preferably 1 to 10 parts by mass, per 100 parts by mass of (meth)acryloyl group-containing monomer (C). If (A) is less than 0.1 part by mass, thermal curing is insufficient, and if it is more than 20 parts by mass, the high-temperature storage stability of the thermosetting composition and thermally configured inkjet ink is reduced.

The above blocking agents may be used alone or in combination of two or more types, or multiple types of blocked isocyanates blocked with a single or two or more types of blocking agents may be used.

Examples of commercially available blocked isocyanates include BI7961 and BI7992 (both manufactured by Baxenden), MF-K60X (manufactured by Asahi Kasei Chemicals), VPLS2253, and BL4265SN (both manufactured by Sumika Bayer Urethane Co., Ltd.).

[Compound (B) Having a Functional Group Capable of Forming a Hydrogen Bond with Blocked Isocyanate]
In the present invention, the "functional group capable of forming a hydrogen bond with a blocked isocyanate" refers to a functional group having active hydrogen, and examples thereof include a hydroxy group, a carboxy group, an amino group, and a mercapto group.

Preferred hydroxyl groups include C1 to C18 alcohols, phenols, and (meth)acrylates containing a hydroxyl group. Specific examples include phenol, p-cresol, ethyl salicylate, ethyl p-hydroxybenzoate, propylene glycol, and propylene glycol monomethyl ether.

Preferred carboxy groups are C1 to C18 aliphatic carboxylic acids and aromatic carboxylic acids. Specific examples include benzoic acid.

Preferably, the amino group is a primary amine or a secondary amine, such as a C1 to C18 aliphatic amine or aromatic amine. Specific examples include aniline and acetanilide.

As the mercapto group, C1 to C18 aliphatic mercaptans and aromatic mercaptans are preferred, and specific examples include 1-butanethiol and thiophenol.

Furthermore, in the present invention, it is preferable that compound (B) is a monomer containing a (meth)acryloyl group. The monomer containing a (meth)acryloyl group is preferably an acrylate.

Examples of monofunctional (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxymethylcyclohexylmethyl (meth)acrylate, p-hydroxymethylphenylmethyl (meth)acrylate, ( Examples of the hydroxyalkyl (meth)acrylate include 2-(hydroxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxyethoxy)ethyl (meth)acrylate, methyl α-hydroxymethylacrylate, ethyl α-hydroxymethylacrylate, hydroxyalkyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate.

Examples of polyfunctional (meth)acrylates having hydroxy groups include 2-hydroxy-3-acryloyloxypropyl methacrylate, dipentaerythritol penta(meth)acrylate, ethylene oxide-added pentaerythritol tetra(meth)acrylate, trimethylolpropane diacrylate, glycerin di(meth)acrylate, glycerin acrylate methacrylate, pentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol propionate tri(meth)acrylate, hydroxypivalaldehyde-modified dimethylolpropane tri(meth)acrylate, sorbitol tri(meth)acrylate, sorbitol tetra(meth)acrylate, sorbitol penta(meth)acrylate, pentaerythritol tri(meth)acrylate, and the like.

Furthermore, when the functional group capable of forming a hydrogen bond with the blocked isocyanate (A) is a hydroxy group, it is preferable that the compound (B) is a compound represented by the following general formula (1) or a polyfunctional acrylate having a hydroxy group.

General formula (1)
Z-R ₄ -OH
(In general formula (1), Z represents CH ₂ ═CR ₁ —COO—. R ₁ represents a hydrogen atom or a methyl group. R ₄ represents an organic residue containing 2 to 20 carbon atoms.)

In the above general formula (1), the organic residue represented by _R4 is preferably a linear, branched, or cyclic alkylene group having 2 to 20 carbon atoms, an alkylene group having 2 to 20 carbon atoms having an oxygen atom in its structure via an ether bond and/or an ester bond, or an optionally substituted aromatic group having 6 to 11 carbon atoms. Among these, a linear, branched, or cyclic alkylene group having 2 to 6 carbon atoms, or an alkylene group having 2 to 9 carbon atoms having an oxygen atom in its structure via an ether bond is preferred.

Specific examples of the compound (B) represented by the general formula (1) include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4-hydroxycyclohexyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxymethylcyclohexylmethyl (meth)acrylate, p-hydroxymethylphenylmethyl (meth)acrylate, 2-(hydroxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxy)ethyl (meth)acrylate, 2-(hydroxyethoxyethoxyethoxy)ethyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl acrylate.
Examples of polyfunctional acrylates having a hydroxy group include pentaerythritol triacrylate and dipentaerythritol pentaacrylate.

More preferred examples of compound (B), from the standpoint of curing speed, include 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, or alicyclic carboxylic acid-based epoxy acrylates such as pentaerythritol triacrylate and acrylic modified products of hexahydrodiphthalic acid glycidyl diester, and dipentaerythritol pentaacrylate, with pentaerythritol triacrylate being particularly preferred.

Examples of (meth)acryloyl group-containing monomers having a carboxy group include acrylic acid, methacrylic acid, etc.

The content of compound (B) is preferably in the range of 0.1 to 20 parts by mass of blocked isocyanate (A) per 100 parts by mass of (meth)acryloyl group-containing monomer (C), and more preferably in the range of 1 to 10 parts by mass. If the content of compound (B) is less than 0.1 part by mass, storage stability at high temperatures will be poor, and if it is more than 20 parts by mass, the curing properties of the cured film of the thermosetting composition and thermally configured inkjet ink under high-temperature and high-humidity conditions will be reduced.

[(Meth)acryloyl Group-Containing Monomer (C) Having No Functional Group Reactive with Blocked Isocyanate]
In the present invention, the (meth)acryloyl group-containing monomer (C) that does not have a functional group capable of reacting with a blocked isocyanate has one or more (meth)acryloyl groups in one molecule.
The (meth)acryloyl group-containing monomer is a compound that does not have a functional group capable of reacting with isocyanate. The functional group capable of reacting with isocyanate has already been described in the description of compound (B).

Examples of the (meth)acrylate used in the present invention include monofunctional (meth)acrylates such as 2-(2-ethoxyethoxy)ethyl (meth)acrylate, butyl (meth)acrylate, stearyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, and 2-phenoxyethyl (meth)acrylate, as well as 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and diethylene Examples of the polyfunctional (meth)acrylate compound include difunctional (meth)acrylates such as glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and neopentyl glycol diacrylate, trifunctional (meth)acrylates such as trimethylolpropane triacrylate, and polyfunctional (meth)acrylate compounds including tetrafunctional or higher functional (meth)acrylates such as ditrimethylolpropane tetraacrylate and dipentaerythritol hexaacrylate.
The above-mentioned (meth)acryloyl group-containing monomers may be used alone or in combination of two or more kinds.

[Gelling agent]
The gelling agent according to the present invention is preferably maintained in a uniformly dispersed state in the cured film cured by light and heat, which makes it possible to prevent moisture from penetrating into the cured film.
The gelling agent is preferably at least one compound selected from the group consisting of compounds represented by the following general formula (G1) and (G2), in that it can be dispersed in the cured film without inhibiting the curing of the ink. Furthermore, it is preferable in that it has good pinning properties in inkjet printing, can achieve both fine lines and a thick film, and has excellent fine line reproducibility.

General formula (G1): R ₁ -CO-R ₂
General formula (G2): R ₃ -COO-R ₄
(In the formula, R ₁ to R ₄ each independently represent an alkyl chain having 12 or more carbon atoms and a linear portion, which may be branched.)
The ketone wax represented by the general formula (G1) or the ester wax represented by the general formula (G2) has a linear or branched hydrocarbon group (alkyl chain) with 12 or more carbon atoms, which further enhances the crystallinity of the gelling agent, improves water resistance, and creates more sufficient spaces in the house-of-card structure described below. This makes it easier for ink media such as solvents and photopolymerizable compounds to be fully enclosed in the spaces, thereby improving the pinning ability of the ink.

In addition, it is preferable that the number of carbon atoms in the linear or branched hydrocarbon group (alkyl chain) is 26 or less.If the number of carbon atoms is 26 or less, the melting point of the gelling agent will not be excessively high, so there is no need to heat the ink excessively when ejecting it.

From the above viewpoint, it is particularly preferable that R ₁ and R ₂ or R ₃ and R ₄ are linear hydrocarbon groups having 12 to 23 carbon atoms.

From the viewpoint of increasing the gelling temperature of the ink and causing the ink to gel more rapidly after landing, it is preferable that either _R1 or _R2 , or either _R3 or _R4 , is a saturated hydrocarbon group having from 12 to 23 carbon atoms.
From the above viewpoint, it is more preferable that both R ₁ and R ₂ or both R ₃ and R ₄ are saturated hydrocarbon groups having 11 or more but less than 23 carbon atoms.

Examples of ketone waxes represented by the general formula (G1) include dilignoceryl ketone (C24-C24), dibehenyl ketone (C22-C22), distearyl ketone (C18-C18), dieicosyl ketone (C20-C20), dipalmityl ketone (C16-C16), dimyristyl ketone (C14-C14), dilauryl ketone (C12-C12), lauryl myristyl ketone ( Examples of ketones include lauryl palmityl ketone (C12-C14), lauryl palmityl ketone (C12-C16), myristyl palmityl ketone (C14-C16), myristyl stearyl ketone (C14-C18), myristyl behenyl ketone (C14-C22), palmityl stearyl ketone (C16-C18), palmityl behenyl ketone (C16-C22), and stearyl behenyl ketone (C18-C22). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

Commercially available examples of ketone waxes represented by general formula (G1) include Stearonne (manufactured by Alfa Aeser; Stearon), 18-Pentatriacontanon (manufactured by Alfa Aeser), Hentriacontan-16-on (manufactured by Alfa Aeser), and Kaowax T-1 (manufactured by Kao Corporation).

Examples of fatty acids or ester waxes represented by general formula (G2) include behenyl behenate (C21-C22), icosanoic acid icosyl (C19-C20), stearyl stearate (C17-C18), palmityl stearate (C17-C16), lauryl stearate (C17-C12), cetyl palmitate (C15-C16), and stearyl palmitate (C15-C18). ), myristyl myristate (C13-C14), cetyl myristate (C13-C16), octyldodecyl myristate (C13-C20), stearyl oleate (C17-C18), stearyl erucate (C21-C18), stearyl linoleate (C17-C18), behenyl oleate (C18-C22), and arachidyl linoleate (C17-C20). The number of carbon atoms in the parentheses indicates the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

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

Since these commercially available products are often mixtures of two or more types, they may be separated and purified as necessary before being incorporated into the ink. Of these gelling agents, ketone waxes, ester waxes, higher fatty acids, higher alcohols, and fatty acid amides are preferred from the perspective of further enhancing pinning properties.

The content of the gelling agent according to the present invention is preferably within the range of 0.5 to 5.0% by mass relative to the total mass of the ink. By keeping the content of the gelling agent within this range, the solubility of the gelling agent in the solvent component and the pinning effect are improved, and the water resistance of the cured film is also improved. From the above perspective, it is more preferable that the content of the gelling agent in the inkjet ink is within the range of 0.5 to 2.5% by mass.

Furthermore, from the following viewpoint, it is preferable that the gelling agent crystallizes in the ink at a temperature below the gelling temperature of the ink. The gelling temperature is the temperature at which the gelling agent undergoes a phase transition from sol to gel when ink that has been solated or liquefied by heating is cooled, causing a sudden change in the viscosity of the ink. Specifically, the solated or liquefied ink is cooled while its viscosity is measured using a viscoelasticity measuring device (e.g., MCR300, manufactured by Physica), and the temperature at which the viscosity suddenly increases can be determined to be the gelling temperature of the ink.

[Photopolymerization initiator]
As the photopolymerization initiator according to the present invention, it is preferable to use a photoradical initiator when the photopolymerizable compound is a radical polymerizable compound, and to use a photoacid generator when the photopolymerizable compound is a cationically polymerizable compound.

The thermosetting inkjet ink of the present invention may contain only one type of photopolymerization initiator, or may contain two or more types of photopolymerization initiators.
The photopolymerization initiator may be a combination of both a photoradical initiator and a photoacid generator.

Photoradical initiators include cleavage-type radical initiators and hydrogen abstraction-type radical initiators.

Examples of cleavage-type radical initiators include acetophenone-based initiators, benzoin-based initiators, acylphosphine oxide-based initiators, and benzyl and methylphenyl glyoxyesters.

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.

Examples of benzoin-based initiators include benzoin, benzoin methyl ether, and benzoin isopropyl ether.

Examples of acylphosphine oxide initiators include 2,4,6-trimethylbenzoindiphenylphosphine oxide.

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.

Examples of benzophenone-based initiators include benzophenone, o-benzoylbenzoic acid methyl-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.

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

Examples of photoacid generators include the compounds described in "Organic Materials for Imaging," edited by the Organic Electronics Materials Research Group, Bunshin Publishing (1993), pages 187-192.

The content of the photopolymerization initiator may be within a range that allows the ink to be sufficiently cured, and may be, for example, within a range of 0.01 to 10% by mass relative to the total mass of the thermosetting inkjet ink of the present invention (hereinafter simply referred to as the ink of the present invention).

Examples of commercially available photopolymerization initiators include Irgacure TPO (manufactured by BASF), 819 (manufactured by BASF), Irgacure 379 (manufactured by BASF), Genocure ITX (manufactured by Rahn A.G.), and Genocure EPD (manufactured by Rahn A.G.).

The ink of the present invention may further contain a photopolymerization initiator aid, a polymerization inhibitor, etc. as necessary.

The photopolymerization initiator aid may be a tertiary amine compound, preferably an aromatic tertiary amine compound.

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. Of these, N,N-dimethylamino-p-benzoic acid ethyl ester and N,N-dimethylamino-p-benzoic acid isoamyl ethyl ester are preferred. These compounds may be used alone or in combination.

[Colorant]
The ink of the present invention may further contain a colorant, if necessary.
The colorant may be a dye or a pigment, but a pigment is preferred because it has good dispersibility in the components of the ink and excellent weather resistance. The pigment is not particularly limited, but examples include organic pigments or inorganic pigments with the following numbers listed in the Color Index.

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, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Examples of the pigment include pigments selected from Orange 13, 16, 20, and 36, and mixtures thereof.

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, 60, or mixtures thereof.

Examples of green pigments include pigments selected from Pigment Green 7, 26, 36, 50, or mixtures thereof.

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, 193, or mixtures thereof.

Examples of black pigments include pigments selected from Pigment Black 7, 28, 26, or mixtures thereof.

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, and 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, 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, Seikafast Red 8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seikafast Carmine 6B1476T-7, 1483LT, 3840, 3870, Seikafast Bordeaux 10B-430, Seikalite Rose R40, Seikalite Violet B800, 7805, Seikafast Maroon 460N, Seikafast Orange 900, 2900, Seikalite Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (all manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.); 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 Brown B610N, Colortex Violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (all manufactured by Sanyo Dye Co., Ltd.); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (all manufactured by Toyo Ink Co., Ltd.), Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostaperm Blue B2G (all manufactured by Hoechst Industries Ltd.); Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (all manufactured by Clariant); 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).

Pigments can be dispersed using, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, and paint shaker.

It is preferable to disperse the pigment so that the volume average particle size of the pigment particles is preferably within the range of 0.08 to 0.5 μm, and the maximum particle size is preferably within the range of 0.3 to 10 μm, and more preferably within the range of 0.3 to 3 μm.

Pigment dispersion is adjusted by selecting the pigment, dispersant, and dispersion medium, dispersion conditions, filtration conditions, etc.

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, etc. Examples of commercially available dispersants include the Solsperse series from Avecia and the PB series from Ajinomoto Fine-Techno Co., Ltd.

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

The ink of the present invention may further contain a dispersion medium for dispersing the pigment, if necessary. A solvent may be included in the ink as the dispersion medium, but to prevent solvent residue in the formed image, it is preferable to use a photopolymerizable compound (especially a low-viscosity monomer) as described above as the dispersion medium.

Dyes include oil-soluble dyes, etc.

Oil-soluble dyes include the following types of dyes. Examples of magenta dyes include MS Magenta VP, MS Magenta HM-1450, MS Magenta HSo-147 (all manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Red-1, AIZEN SOT Red-2, AIZEN SOT Red-3, AIZEN SOT Pink-1, SPIRON Red GEH SPECIAL (all manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, MACROLEX ROT5B (all manufactured by Bayer Japan KK), KAYASET Red B, KAYASET Red 130, KAYASET Red 802 (all manufactured by Nippon Kayaku Co., Ltd.), PHLOXIN, ROSE BENGAL, ACID Red (all manufactured by Daiwa Kasei Co., Ltd.), HSR-31, DIARESIN Red K (all manufactured by Mitsubishi Kasei Corporation), and Oil Red (manufactured by BASF Japan Ltd.).

Examples of cyan dyes include MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, and MS Cyan VPG (all manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, and SIRIUS SUPRA TURQ. Blue FB-LL 330% (all manufactured by Bayer Japan Ltd.), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, Light Blue BGL-5200 (all manufactured by Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, OleosolFast Blue GL (all manufactured by Daiwa Chemical Industry Co., Ltd.), DIARESIN Blue P (manufactured by Mitsubishi Chemical Corporation), SUDAN Blue 670, NEOPEN Blue 808, ZAPON Blue 806 (all manufactured by BASF Japan Ltd.), and the like.

Examples of yellow dyes include MS Yellow HSm-41, Yellow KX-7, Yellow EX-27 (all manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Yellow-1, AIZEN SOT Yellow W-3, AIZEN SOT Yellow-6 (all manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, MACROLEX FLUOR. Examples of the yellow paint include KAYASET Yellow 10GN (all manufactured by Bayer Japan Ltd.), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow A-G, KAYASET Yellow E-G (all manufactured by Nippon Kayaku Co., Ltd.), DAIWA Yellow 330HB (manufactured by Daiwa Chemical Industry Co., Ltd.), HSY-68 (manufactured by Mitsubishi Chemical Corporation), SUDAN Yellow 146, NEOPEN Yellow 075 (all manufactured by BASF Japan Ltd.), and the like.

Examples of black dyes include MS Black VPC (manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Black-1, AIZEN SOT Black-5 (all manufactured by Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESORIN Black BS (all manufactured by Bayer Japan), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Chemical Industry Co., Ltd.), HSB-202 (manufactured by Mitsubishi Chemical Corporation), NEPTUNE Black X60, NEOPEN Black X58 (all manufactured by BASF Japan), etc.

The ink of the present invention may contain one or more colorants and may be toned to a desired color.
The content of the colorant is preferably in the range of 0.1 to 20% by mass, and more preferably in the range of 0.4 to 10% by mass, based on the total amount of the ink.

[Other ingredients]
The ink of the present invention may further contain other components including a polymerization inhibitor and a surfactant, as long as the effects of the present invention are obtained. The ink of the present invention may contain only one of these components, or two or more of them.

(Polymerization inhibitor)
Examples of the polymerization inhibitor include (alkyl)phenols, hydroquinone, catechol, resorcinol, 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-nitrosophenylhydroxyamine, 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.

Examples of commercially available polymerization inhibitors include Irgastab UV10 (manufactured by BASF) and Genorad 18 (manufactured by Rahn A.G.).

The amount of polymerization inhibitor can be set as desired as long as the effects of the present invention are achieved. The amount of polymerization inhibitor can be, for example, 0.001% by mass or more and less than 1.0% by mass of the total mass of the ink.

(Surfactant)
Examples of the surfactant 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.

Examples of silicone surfactants include polyether-modified polysiloxane compounds, specifically Tego Rad 2250 manufactured by Evonik; KF-351A, KF-352A, KF-642, and X-22-4272 manufactured by Shin-Etsu Chemical Co., Ltd.; BYK307, BYK345, BYK347, and BYK348 manufactured by BYK ("BYK" is a registered trademark of the company); and TSF4452 manufactured by Momentive Performance Materials.

The fluorine-based surfactant refers to a surfactant in which part or all of the hydrogen atoms bonded to the carbon atoms of the hydrophobic group of a normal surfactant are substituted with fluorine.
Examples of fluorine-based surfactants include Megafac F manufactured by DIC Corporation ("Megafac" is a registered trademark of DIC), Surflon manufactured by AGC Sei Chemical Co., Ltd. ("Surflon" is a registered trademark of AGC Sei Chemical Co., Ltd.), Fluorad FC manufactured by 3M Corporation ("Fluorad" is a registered trademark of 3M), Monflor manufactured by Imperial Chemical Industries, Ltd., Zonyls manufactured by E.I. duPont Nemelas and Company, Licowet VPF manufactured by Lubewerke-Hoechst, and FTERGENT manufactured by Neos Corporation ("FTERGENT" is a registered trademark of 3M).

The amount of surfactant can be set as desired as long as the effects of the present invention are achieved. The amount of surfactant can be, for example, 0.001% by mass or more and less than 1.0% by mass of the total mass of the ink.

(Curing accelerator)
In the present invention, a curing accelerator may be contained as needed. The curing accelerator is not particularly limited as long as it accelerates the thermal curing of the resin component.
Examples of the curing accelerator include imidazoles, dicyandiamide derivatives, dicarboxylic acid dihydrazide, triphenylphosphine, tetraphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazole-tetraphenylborate, and 1,8-diazabicyclo[5.4.0]undecene-7-tetraphenylborate.

(Coupling Agent)
In the present invention, various coupling agents may be contained as necessary, which can improve adhesion to copper foil.
Examples of various coupling agents include silane-based, titanium-based, and aluminum-based coupling agents.

(Ion scavenger)
In the present invention, an ion scavenger may be contained as needed. The inclusion of an ion scavenger has advantages such as adsorbing ionic impurities and improving the insulating properties of the cured film when it absorbs moisture.

Examples of ion trapping agents include inorganic ion adsorbents such as triazine thiol compounds, bisphenol-based reducing agents, zirconium compounds, and antimony-bismuth-based magnesium aluminum compounds.

(solvent)
In the thermosetting composition of the present invention and the ink of the present invention, it is essentially preferable to use no solvent from the viewpoint of curability, but a solvent may be added to adjust the viscosity of the ink.

[Physical properties]
The ink of the present invention preferably contains a gelling agent. In this case, it is preferable that the viscosity of the ink of the present invention at 25°C is in the range of 1 to 1 x ¹⁰ Pa s, since this allows the ink to be sufficiently gelled when it lands and is cooled to room temperature, thereby improving pinning properties.

In addition, from the viewpoint of further improving ejection properties from an inkjet head, the viscosity of the ink of the present invention at 80°C is preferably in the range of 3 to 20 mPa·s, and more preferably in the range of 7 to 9 mPa·s.

Furthermore, when the ink of the present invention contains a gelling agent, it preferably has a phase transition point in the range of 40°C or higher but lower than 100°C. If the phase transition point is 40°C or higher, the ink will gel quickly after landing on the recording medium, resulting in higher pinning properties. Furthermore, if the phase transition point is lower than 100°C, the ink will be easier to handle and have higher ejection stability.

From the viewpoint of enabling the ink to be ejected at lower temperatures and reducing the load on the image forming device, it is more preferable that the phase transition point of the ink of the present invention be within the range of 40 to 60°C.

The viscosity at 80°C, viscosity at 25°C and phase transition point of the ink of the present invention can be determined by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer.

In the present invention, these viscosities and phase transition points are values obtained by the following method.

The ink of the present invention is heated to 100°C, and the viscosity is measured using a Physica MCR301 (manufactured by Anton Paar) at a shear rate of 1000 (1/s). The ink is then cooled to 20°C under conditions of a shear rate of 11.7 (1/s) and a cooling rate of 0.1°C/s to obtain a temperature change curve of viscosity.

The viscosity at 80°C and the viscosity at 25°C can be determined by reading the viscosity at 80°C and 25°C on the viscosity temperature curve. The phase transition point can be determined as the temperature at which the viscosity reaches 200 mPa·s on the viscosity temperature curve.

From the perspective of further improving ejection performance from an inkjet head, it is preferable that the average dispersed particle size of the pigment particles according to the present invention is in the range of 50 to 150 nm, and that the maximum particle size is in the range of 300 to 1,000 nm. A more preferable average dispersed particle size is in the range of 80 to 130 nm.

The average dispersed particle size of pigment particles in this invention refers to the value determined by dynamic light scattering using a Datasizer Nano ZSP (manufactured by Malvern). Note that inks containing colorants are highly concentrated, and light does not pass through this measuring device, so the ink is diluted 200 times before measurement. The measurement temperature is room temperature (25°C).

[Method for forming solder resist film]
The thermosetting inkjet ink of the present invention is preferably an ink for forming a solder resist pattern used on a printed circuit board. When a solder resist pattern (solder resist film) is formed using the thermosetting inkjet ink of the present invention, it is possible to prevent moisture from penetrating into the solder resist film, resulting in good adhesion between the copper foil and the solder resist film on the printed circuit board, and also preventing copper migration and suppressing deterioration of insulation properties.

The method for forming a solder resist film using the thermosetting inkjet ink of the present invention preferably includes the steps of (1) ejecting the ink of the present invention from the nozzle of an inkjet head and causing it to land on a printed circuit board on which a circuit has been formed, and (3) heating the ink to fully cure it.

When the ink of the present invention contains a compound having a photopolymerizable functional group and a photopolymerization initiator, it is preferable to include a step (step (2)) between steps (1) and (3) above, in which the deposited ink is irradiated with actinic light to temporarily cure the ink.

<Step (1)>
In the step (1), droplets of the ink of the present invention are ejected from an inkjet head and landed on a printed circuit board, which is a recording medium, at positions corresponding to the resist film to be formed, thereby forming a pattern.

The ejection method from the inkjet head can be either on-demand or continuous.

On-demand inkjet heads may be of any electro-mechanical conversion type, such as single cavity type, double cavity type, bender type, piston type, shear mode type, and shared wall type, or of an electro-thermal conversion type, such as thermal inkjet type and bubble jet (registered trademark) type (bubble jet is a registered trademark of Canon Inc.).

Ejection stability can be improved by ejecting ink droplets from the inkjet head in a heated state. The ink temperature when ejected is preferably in the range of 40 to 100°C, and more preferably in the range of 40 to 90°C to further improve ejection stability. In particular, it is preferable to eject the ink at an ink temperature that results in a viscosity in the range of 7 to 15 mPa·s, more preferably in the range of 8 to 13 mPa·s.

To improve the ejection properties of sol-gel phase transition ink from the inkjet head, it is preferable that the temperature of the ink when filled into the inkjet head be set to between (gelation temperature + 10)°C and (gelation temperature + 30)°C. If the temperature of the ink inside the inkjet head is (gelation temperature + 10)°C or higher, the ink will not gel inside the inkjet head or on the nozzle surface, which will result in a decrease in ink ejection properties. On the other hand, if the temperature of the ink inside the inkjet head is within (gelation temperature + 30)°C, the ink will not become too hot, causing degradation of the ink components.

There are no particular restrictions on the method for heating the ink. For example, at least one of the ink supply system, such as the ink tank that makes up the head carriage, the supply pipe, and the anterior ink tank immediately before the head, the filtered piping, and the piezo head, can be heated using a panel heater, ribbon heater, or heated water.

The volume of ink droplets ejected is preferably within the range of 2 to 20 pL in terms of recording speed and image quality.

The printed circuit board is not particularly limited, but may be made of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth/non-woven cloth epoxy, glass cloth/paper epoxy, synthetic fiber epoxy, copper clad laminates for high frequency circuits made from fluorine, polyethylene, PPO, cyanate ester, etc., and copper clad laminates of all grades (FR-4, etc.), as well as polyimide film, PET film, glass substrate, ceramic substrate, wafer plate, stainless steel plate, etc.

<Step (2)>
In the step (2), the ink that has landed in the step (1) is irradiated with actinic rays to temporarily cure the ink.
The actinic ray can be selected from, for example, electron beams, ultraviolet rays, α rays, γ rays, and X-rays, and is preferably ultraviolet rays.

UV light can be irradiated at a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology. Using an LED as the light source can prevent poor ink curing caused by the ink melting due to the radiant heat from the light source.

The ultraviolet light irradiation is carried out so that the peak irradiance of ultraviolet light having a wavelength in the range of 370 to 410 nm on the surface of the resist film is preferably in the range of 0.5 to 10 W/cm ² , more preferably in the range of 1 to 5 W/cm ^2. From the viewpoint of suppressing radiant heat from being irradiated onto the ink, the amount of light irradiated onto the resist film is preferably less than 500 mJ/cm ² .

Irradiation with actinic light is preferably carried out between 0.001 and 300 seconds after ink landing, and more preferably between 0.001 and 60 seconds to form a highly precise resist film.

<Step (3)>
In the step (3), after the temporary curing in the step (2), the ink is further heated to be fully cured.
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 60 minutes.

In addition to being used as an ink for forming the solder resist pattern described above, the thermosetting inkjet ink of the present invention can also be used as an adhesive, sealant, circuit protectant, etc. for electronic components.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

Example 1
[Preparation of Thermosetting Compositions 1-1 to 1-44]
The blocked isocyanate (A), the compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate, and the (meth)acryloyl group-containing monomer (C) having no functional group capable of reacting with the blocked isocyanate were blended in the proportions shown in Tables I to III, and the mixture was stirred with a dissolver to obtain thermosetting compositions 1-1 to 1-44.

[Preparation of Thermosetting Compositions 1-45 to 1-58]
The combined amount of the compound (B) having a functional group capable of hydrogen bonding with the blocked isocyanate (A) and the (meth)acryloyl group-containing monomer (C) having no functional group capable of reacting with the blocked isocyanate was 96% by mass of the entire thermosetting composition. The addition ratio is shown in Table III. Furthermore, the following amounts of a photopolymerization initiator and a photopolymerization initiator aid were blended:
This was stirred with a dissolver to obtain thermosetting compositions 1-45 to 1-58.
Photopolymerization initiator Irgacure TPO (manufactured by BASF): 1.0% by mass
Photopolymerization initiator Genocure ITX (manufactured by Rahn A.G.): 3.0% by mass

[Formation of Cured Films 1-1 to 1-58]
Using these thermosetting compositions 1 to 58, films with a thickness of 30 μm were formed on BT substrates using an applicator (manufactured by ERICHSEN), and thermosetting compositions 1-1 to 1-44 were cured at 160° C. for 30 minutes to form cured films 1-1 to 1-44.
Furthermore, for the thermosetting compositions 1-45 to 1-58, the films were cured by irradiating them with an LED lamp (395 nm, 8 W/cm ² , water cooled unit) manufactured by Phoseon Technology at 500 mJ/cm ² , and then curing them at 160°C for 30 minutes to form cured films 1-45 to 1-58.

The compounds shown in the table below are shown.
<Blocked Isocyanate (A)>
A-1: Trixene BI7961 (manufactured by LANXESS, biuret type, blocking agent: DMP (dimethylpyrazole))
A-2: Trixene BI7982 (manufactured by LANXESS, blocking agent: DMP)
A-3: Trixene BI7992 (manufactured by LANXESS, blocking agent: DMP/DEM (diethyl malonate), active ethylene-based compound)
A-4: BL4265SN (manufactured by Sumika Bayer Urethane Co., Ltd., blocking agent: MEKO (methyl ethyl ketoxime), an oxime-based compound)
A-5: Trixene BI7991 (manufactured by LANXESS, biuret type, blocking agent: DMP/DEM)
A-6: Desmodur BL 1100/1 (manufactured by Sumika Bayer Urethane Co., Ltd., blocking agent: ε-caprolactam)

<Compound (B) Having a Functional Group Capable of Forming a Hydrogen Bond with Blocked Isocyanate>
B-1: Ethyl salicylate B-2: Ethyl p-hydroxybenzoate B-3: p-cresol B-4: Benzoic acid B-5: Aniline B-6: Acetanilide B-7: Thiophenol B-8: 2-hydroxybutyl acrylate (Light Ester HOB-A: manufactured by Kyoeisha Chemical Co., Ltd.)
B-9: Alicyclic carboxylic acid-based epoxy acrylate (DA-722: manufactured by Nagase ChemteX Corporation)
B-10: Dipentaerythritol pentaacrylate (Miramer M500: manufactured by MIWON Co., Ltd.)
B-11: Methacrylic acid B-12: 2-hydroxy-3-phenoxypropyl acrylate (Light Acrylate M-600A: manufactured by Kyoeisha Chemical Co., Ltd.)
B-13: 2-hydroxy-3-acryloyloxypropyl methacrylate (Light Ester G-201P, manufactured by Kyoeisha Chemical Co., Ltd.)

<(Meth)acryloyl Group-Containing Monomer (C) Having No Functional Group Reactive with Blocked Isocyanate>
C-1: Dipropylene glycol diacrylate (DPGDA: M222 manufactured by Miwon)
C-2: TMP(EO)9TA (trimethylolpropane EO-modified triacrylate) (EM2382, manufactured by Choko Chemical Co., Ltd.)
C-3: Phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer (urethane acrylate AH-600: manufactured by Kyoeisha Chemical Co., Ltd.)

"evaluation"
The storage stability at high temperatures and the pencil hardness of the cured film were evaluated.
[Storage stability at high temperatures]
The viscosity of each of the prepared thermosetting compositions 1-1 to 1-58 was measured at 25°C, and then the composition was stored in a sealed container at 85°C for 500 hours. The composition was then allowed to cool to 25°C, and the viscosity after high-temperature treatment was measured. The viscosity increase rate (%) was calculated and evaluated according to the following criteria.
The viscosity was measured using a Physica MCR301 (manufactured by Anton Paar) at a shear rate of 1000 (1/s).
Viscosity increase rate (%)=(viscosity after 500 hours−initial viscosity)/initial viscosity×100.

◎: Viscosity increase rate is less than 5% ○: Viscosity increase rate is 5% or more and less than 10% △: Viscosity increase rate is 10% or more and less than 20% ×: Viscosity increase rate is 20% or more or solidification

[Pencil hardness]
Each of the cured films 1-1 to 1-58 formed by heat curing or heat curing and photocuring was subjected to a pencil hardness test using a Hi-uni made by Mitsubishi Pencil Co., Ltd. in accordance with JIS K 5400.

Specifically, the wood of the pencil was scraped off, leaving a lead 5-6 mm long. The tip of the lead was polished smoothly with abrasive paper to give the pencil a circular cross section. This pencil was held at a 45-degree angle to the sample surface, and a weight of 1 kg was applied to the sample surface, scratching the coating at a 45-degree angle. The maximum hardness of the pencil whose coating did not reach the substrate was evaluated.

[Pencil hardness under high temperature and humidity conditions]
Each of the cured films 1-1 to 1-58 formed by the above-described heat curing or heat curing plus photocuring was left to stand for 500 hours under conditions of 85°C and a relative humidity of 85%. Thereafter, the pencil hardness was evaluated in the same manner as described above, and the peeling state of the cured film was observed.
The results are shown in Tables I to III. In the following tables, the blocked isocyanate (A)
The compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate and the (meth)acryloyl group-containing monomer (C) not having a functional group capable of reacting with the blocked isocyanate are referred to as the compound (B) having a functional group capable of forming a hydrogen bond and the (meth)acryloyl group-containing monomer (C), respectively.

As is clear from the results shown in Tables I to III, compounds within the scope of the present invention are materials that exhibit excellent storage stability and thermosetting properties when stored at high temperatures, as well as excellent thermosetting properties under high temperature and high humidity conditions. Furthermore, it can be seen that thermosetting compositions containing 1 to 10 parts by mass of a compound (B) having a functional group capable of forming a hydrogen bond, or 1 to 10 parts by mass of a blocked isocyanate (A), per 100 parts by mass of a (meth)acryloyl group-containing monomer (C), exhibit even better ink storage stability.

It is also apparent that when the compound (B) having a functional group capable of forming a hydrogen bond is a (meth)acryloyl group-containing monomer, the ink storage stability and pencil hardness are excellent.
Furthermore, it is clear that the thermosetting composition irradiated with light using a photopolymerization initiator has excellent pencil hardness.

Example 2
[Preparation of Inkjet Ink]
<Preparation of Yellow Pigment Dispersion>
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, after which the pigment shown below was added, 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.

Dispersant 1: EFKA7701 (manufactured by BASF) 5.6 parts by mass Dispersant 2: Solsperse 22000 (manufactured by Lubrizol Japan)
0.4 parts by mass Dispersion medium: dipropylene glycol diacrylate (containing 0.2% UV-10) 80.6 parts by mass Pigment: PY185 (manufactured by BASF, Paliotol Yellow D1155)
13.4 parts by mass

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

Dispersant: EFKA7701 (manufactured by BASF) 7 parts by mass Dispersion medium: dipropylene glycol diacrylate (containing 0.2% UV-10) 70 parts by mass Pigment: PB15:4 (Dainichiseika Chemicals, Chromofine Blue 6332JC)
23 parts by mass

<Gelling agent>
The gelling agents used were as follows:
D-1: Distearyl ketone D-2: Behenyl behenate

<Photopolymerization initiator>
The TPO and ITX described in Example 1 were used.

<Blocked Isocyanate (A)>
A-1 to A-6 described in Example 1 were used.
<Compound (B) Having a Functional Group Capable of Forming a Hydrogen Bond with Blocked Isocyanate>
B-1 to B-13 described in Example 1 were used.

<(Meth)acryloyl Group-Containing Monomer (C) Having No Functional Group Reactive with Blocked Isocyanate>
The above-mentioned C-1 to C-3 were used.

[Preparation of Thermosetting Inkjet Ink]
Thermosetting inkjet inks were each formulated according to the composition shown below, stirred with a dissolver, and filtered through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC Corporation to prepare thermosetting inkjet inks 2-1 to 2-68.

Preparation of Thermosetting Inkjet Inks 2-1 to 2-41
The total amount of the blocked isocyanate (A), the compound (B) having a functional group capable of forming a hydrogen bond, and the (meth)acryloyl group-containing monomer (C) having no functional group capable of reacting with the blocked isocyanate was 93.0 parts by mass of the entire composition. The addition ratios are shown in Tables IV and V. The following components were also contained.
Yellow pigment dispersion: 1.0% by mass
Cyan pigment dispersion: 2.0% by mass
Photopolymerization initiator: TPO: 1.0% by mass
Photopolymerization initiator: ITX: 3.0% by mass

Preparation of Thermosetting Inkjet Inks 2-42 to 2-56
The blocked isocyanate (A), the compound (B) having a functional group capable of hydrogen bonding, and the (meth)acryloyl group-containing monomer (C) not having a functional group capable of reacting with the blocked isocyanate were combined to account for 90.0 parts by mass of the entire composition. The addition ratios are shown in Tables V and VI. The following components were also included:
Yellow pigment dispersion: 1.0% by mass
Cyan pigment dispersion: 2.0% by mass
Gelling agent D-1: 2.0% by mass
Gelling agent D-2: 1.0% by mass
Photopolymerization initiator: TPO: 1.0% by mass
Photopolymerization initiator: ITX: 3.0% by mass

Preparation of Thermosetting Inkjet Inks 2-57 to 2-62
The total amount of the blocked isocyanate (A), the compound (B) having a functional group capable of hydrogen bonding, and the (meth)acryloyl group-containing monomer (C) not having a functional group capable of reacting with the blocked isocyanate was 97.0 parts by mass of the entire composition. The addition ratios are shown in Table VI. The following components were also included.
Yellow pigment dispersion: 1.0% by mass
Cyan pigment dispersion: 2.0% by mass

Preparation of Thermosetting Inkjet Inks 2-63 to 2-68
The total amount of the blocked isocyanate (A), the compound (B) having a functional group capable of hydrogen bonding, and the (meth)acryloyl group-containing monomer (C) not having a functional group capable of reacting with the blocked isocyanate was 94.0 parts by mass of the entire composition. The addition ratios are shown in Table VI. The following components were also included.
Yellow pigment dispersion: 1.0% by mass
Cyan pigment dispersion: 2.0% by mass
Gelling agent D-1: 2.0% by mass
Gelling agent D-2: 1.0% by mass

(Measurement of Viscosity and Gel Phase Transition Temperature)
The viscosity at 80° C. and gel phase transition temperature of each of the prepared thermosetting inkjet inks were measured using a Physica MCR301 (manufactured by Anton Paar) at a shear rate of 1000 (1/s).

Here, the gel phase transition temperature represents the temperature at which the complex viscosity becomes 1 Pa·s or greater in the viscoelasticity curve obtained by changing the temperature at a cooling rate of 0.1°C/s, a strain of 5%, an angular frequency of 10 radians/s, and a cooling rate of 0.1°C/s.

The viscosity at 25° C. of the inks containing the gelling agent of the present invention was in the range of 1 to 1×10 ⁴ Pa·s, whereas the viscosity of the inks not containing the gelling agent was less than 1 Pa·s.
Furthermore, the gel phase transition temperatures of the inks containing the gelling agent of the present invention were all between 40 and 100° C., but the gel phase transition phenomenon was not observed in the inks containing no gelling agent.

<Patterning with thermosetting inkjet ink>
Each of the prepared thermosetting inkjet inks was loaded into an inkjet recording apparatus having an inkjet recording head equipped with a piezoelectric inkjet nozzle. Using this apparatus, a pattern was formed on a copper-clad laminate for printed wiring boards (FR-4, thickness 1.6 mm, size 150 mm × 95 mm).

The ink supply system consists of an ink tank, ink flow path, a sub-ink tank immediately before the inkjet recording head, piping with a metal filter, and a piezo head. The ink is heated to 90°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 90°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 of 720 dpi.

Using this inkjet device, a voltage was applied to form dots with a droplet volume of 6.0 pl, and a 20 mm x 50 mm solid pattern and a comb-shaped pattern with lines and spaces of 100 μm were printed on the substrate, each with a thickness of 20 μm.The ink layer was then temporarily cured by irradiating it with an LED lamp (395 nm, 8 W/ ^cm2 , water-cooled unit) manufactured by Phoseon Technology at 500 mJ/ ^cm2.Then , the ink layer was placed in an oven set to 150°C for 60 minutes for full curing, and a print sample was obtained.

"evaluation"
The ink-jet ink prepared above and the coating film formed thereon were evaluated for shelf life of the ink-jet ink and pencil hardness of the coating film formed thereon in the same manner as in Example 1.
The results are shown in Tables IV to VI.

As is clear from the results shown in Tables IV to VI, the thermosetting inkjet ink of the present invention is a material with excellent storage stability and thermal and photocurability. Furthermore, it can be seen that compositions containing 1 to 10 parts by mass of a compound (B) having a functional group capable of forming a hydrogen bond, or 1 to 10 parts by mass of a blocked isocyanate (A), per 100 parts by mass of a (meth)acryloyl group-containing monomer (C) have even better ink storage stability.

It has also been found that ink storage stability is even better when the compound (B) having a functional group capable of hydrogen bonding has a specific functional group. This is presumably because the structure facilitates hydrogen bonding with the blocked moiety of the blocked isocyanate.

It is also found that adding a gelling agent to the heat- and light-curable composition of the present invention further improves the ink storage stability and heat-curing properties.

The thermosetting composition of the present invention has excellent storage stability at high temperatures and excellent thermosetting properties of the cured film surface under high temperature and high humidity conditions, making it suitable for use in thermosetting inkjet inks.

Claims (7)

A thermosetting inkjet ink containing a blocked isocyanate (A),
The composition contains a compound (B) having a functional group capable of forming a hydrogen bond with the blocked isocyanate (A), and a (meth)acryloyl group-containing monomer (C) having no functional group capable of reacting with the blocked isocyanate,
the compound (B) is contained in a range of 0.1 to 20 parts by mass and the blocked isocyanate (A) is contained in a range of 1 to 10 parts by mass relative to 100 parts by mass of the (meth)acryloyl group-containing monomer (C) ;
Contains a gelling agent and undergoes sol-gel phase transition depending on temperature.
The thermosetting inkjet ink is characterized in that the gelling agent is a compound having a structure represented by the following general formula (G1) or (G2) :
General formula (G1): R ₁ -CO-R ₂
General formula (G2): R ₃ -COO-R ₄
(In the formula, R ₁ to R ₄ each independently represent an alkyl chain having 12 or more carbon atoms and a linear portion, which may be branched.) 2. The thermosetting inkjet ink according to claim 1, further comprising a photopolymerization initiator. 3. The thermosetting inkjet ink according to claim 1, wherein the functional group of the compound (B) capable of forming a hydrogen bond with the blocked isocyanate (A) is at least one selected from the group consisting of a hydroxy group, a carboxy group, an amino group, and a mercapto group. 4. The thermosetting inkjet ink according to claim 3, wherein the compound (B) is a (meth)acryloyl group-containing monomer. 5. The thermosetting inkjet ink according to claim 1, wherein the compound (B) is contained in an amount in the range of 1 to 10 parts by mass per 100 parts by mass of the (meth)acryloyl group- containing monomer (C). 6. The thermosetting inkjet ink according to claim 1, wherein the viscosity at 25°C is in the range of 1 to 1 x 10 4 Pa·s, and the sol-gel phase transition occurs at a temperature in the range of 40°C or higher but ^lower than 100°C. 7. The thermosetting ink-jet ink according to claim 1 , which is a thermosetting ink-jet ink for forming a solder resist pattern used on a printed circuit board.